The Lentil: Botany, Production and Uses

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The Lentil

Botany, Production and Uses

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The Lentil Botany, Production and Uses

Edited by

William Erskine,1 Fred J. Muehlbauer,2 Ashutosh Sarker3 and Balram Sharma4 1Centre

for Legumes in Mediterranean Agriculture (CLIMA), The University of Western Australia, Australia 2USDA-ARS, 303 Johnson Hall, Washington State University, USA 3International Center for Agricultural Research in the Dry Areas (ICARDA), Aleppo, Syria 4Division of Genetics, Indian Agricultural Research Institute, New Delhi, India

CABI Head Ofﬁce Nosworthy Way Wallingford Oxfordshire OX10 8DE UK

CABI is a trading name of CAB International CABI North American Ofﬁce 875 Massachusetts Avenue 7th Floor Cambridge, MA 02139 USA

Tel: +44 (0)1491 832111 Fax: +44 (0)1491 833508 E-mail: [email protected] Website: www.cabi.org

Tel: +1 617 395 4056 Fax: +1 617 354 6875 E-mail: [email protected]

© CAB International 2009. All rights reserved. No part of this publication may be reproduced in any form or by any means, electronically, mechanically, by photocopying, recording or otherwise, without the prior permission of the copyright owners. A catalogue record for this book is available from the British Library, London, UK. Library of Congress Cataloging-in-Publication Data The lentil : botany, production and uses / William Erskine . . . [et al.], editors. p. cm. Includes bibliographical references and index. ISBN 978-1-84593-487-3 (alk. paper) 1. Lentils. 2. Lentils–Research. I. Erskine, William. II. Title. SB351.L55L46 2009 635’.658–dc22 2008045710 ISBN-13:

978 1 84593 487 3

Typeset by AMA Dataset Ltd, Preston, UK. Printed and bound in the UK by the MPG Books Group. The paper used for the text pages in this book is FSC certiﬁed. The FSC (Forest Stewardship Council) is an international network to promote responsible management of the world’s forests.

Contents

Contributors Foreword

vii xi

1. Introduction W. Erskine, F.J. Muehlbauer, A. Sarker and B. Sharma

1

2. Global Production, Supply and Demand W. Erskine

4

3. Origin, Phylogeny, Domestication and Spread J.I. Cubero, M. Pérez de la Vega and R. Fratini

13

4. Plant Morphology, Anatomy and Growth Habit M.C. Saxena

34

5. Agroecology and Crop Adaptation M. Materne and K.H.M. Siddique

47

6. Genetic Resources: Collection, Characterization, Conservation and Documentation B.J. Furman, C. Coyne, B. Redden, S.K. Sharma and M. Vishnyakova 7. Genetics of Economic Traits B. Sharma

64 76

8. Genetic Enhancement for Yield and Yield Stability A. Sarker, A. Aydogan, S. Chandra, M. Kharrat and S. Sabaghpour

102

9. Breeding for Short Season Environments M. Matiur Rahman, A. Sarker, S. Kumar, A. Ali, N.K. Yadav and M. Lutfor Rahman

121

10. Improvement in Developed Countries F.J. Muehlbauer, M. Mihov, A. Vandenberg, A. Tullu and M. Materne

137

11.

155

Advances in Molecular Research R. Ford, B. Mustafa, M. Baum and P.N. Rajesh

v

vi 12. Breeding and Management to Minimize the Effects of Drought and Improve Water Use Efﬁciency R. Shrestha, K.H.M. Siddique, D.W. Turner and N.C. Turner

Contents

172

13. Soil Nutrient Management S.S. Yadav, D.L. McNeil, M. Andrews, C. Chen, J. Brand, G. Singh, B.G. Shivakumar and B. Gangaiah

194

14. Cropping Systems and Production Agronomy M. Ali, K.K. Singh, S.C. Pramanik and M. Omar Ali

213

15. Biological Nitrogen Fixation and Soil Health Improvement M.A. Quinn

229

16. Mechanization J. Diekmann and Y. Al-Saleh

248

17. Diseases and their Management W. Chen, A.K. Basandrai, D. Basandrai, S. Banniza, B. Bayaa, L. Buchwaldt, J. Davidson, R. Larsen, D. Rubiales and P.W.J. Taylor

262

18. Insect Pests and their Management R. Ujagir and O.M. Byrne

282

19. Virus Diseases and their Control S.G. Kumari, R. Larsen, K.M. Makkouk and M. Bashir

306

20. Weed Management J.P. Yenish, J. Brand, M. Pala and A. Haddad

326

21. Parasitic Weeds D. Rubiales, M. Fernández-Aparicio and A. Haddad

343

22. Seed Quality and Alternative Seed Delivery Systems Z. Bishaw, M. Makkawi and A. Aziz Niane

350

23. Nutritional and Health-beneﬁcial Quality M.A. Grusak

368

24. Postharvest Processing and Value Addition Albert Vandenberg

391

25. Food Preparation and Use R.S. Raghuvanshi and D.P. Singh

408

26. The Impact of Improvement Research: the Case of Bangladesh and Ethiopia A.A. Aw-Hassan, S. Regassa, Q.M. Shaﬁqul Islam and A. Sarker

425

Index

447

The colour plate section can be found following p.224

Contributors

Ali, Asghar, Pulse Programme, National Agricultural Research Centre, Park Road, Islamabad, Pakistan, [email protected] Ali, Masood, Indian Institute of Pulses Research, Kanpur 208024, Uttar Pradesh, India, masoodali53@ rediffmail.com Ali, Mohamed Omar, Pulses Research Centre, Bangladesh Agriculture Research Institute, Ishurdi, Pabna, Bangladesh, [email protected] Al-Saleh, Yahya, University of Aleppo, Agricultural Faculty, Rural Engineering Department, Aleppo, Syria, [email protected] Andrews, Mitchell, School of Sciences, University of Sunderland, Sunderland SR1 3SD, UK, [email protected] Aw-Hassan, Aden A., International Center for Agricultural Research in the Dry Areas (ICARDA), PO Box 5466, Aleppo, Syria, [email protected] Aydogan, A., Central Research Institute for Field Crops (CRIFC), Ankara, Turkey, akadir602000@ yahoo.com Banniza, Sabine, Crop Development Centre, University of Saskatchewan, 51 Campus Drive, Saskatoon, SK S7N 5A8, Canada, [email protected] Basandrai, Ashwani K., CSK Himachal Pradesh Agricultural University, Hill Agricultural Research and Extension Centre, Dhaulakuan, Dist. Sirmour-173001, India, [email protected] Basandrai, Daisy, CSK Himachal Pradesh Agricultural University, Hill Agricultural Research and Extension Centre, Dhaulakuan, Dist. Sirmour-173001, India, [email protected] Bashir, Muhammad, Crop Diseases Research Institute, National Agricultural Research Centre (NARC), Park Road, Islamabad, Pakistan, [email protected] Baum, Michael, International Center for Agricultural Research in the Dry Areas (ICARDA), PO Box 5466, Aleppo, Syria, [email protected] Bayaa, Bassam, Faculty of Agriculture, University of Aleppo and International Center for Agricultural Research in the Dry Areas (ICARDA), PO Box 5466, Aleppo, Syria, [email protected] Bishaw, Zewdie, Seed Unit, International Center for Agricultural Research in the Dry Areas (ICARDA), PO Box 5466, Aleppo, Syria, [email protected] Brand, Jason, Department of Primary Industries Victoria, Horsham, Private Bag 260, Horsham, Victoria 3401, Australia, [email protected]

vii

viii

Contributors

Buchwaldt, Lone, Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK, S7N 0X2, Canada, [email protected] Byrne, Oonagh M., School of Plant Biology/Centre for Legumes in Mediterranean Agriculture (M080), The University of Western Australia, 35 Stirling Highway, Crawley WA 6009, Australia, [email protected] Chandra, S., Indian Institute of Pulses Research (IIPR), Kanpur 208024, Uttar Pradesh, India, mali@ iipr.ernet.in Chen, Chengci, Central Agricultural Research Center, Montana State University, Moccasin, MT 59462, USA, [email protected] Chen, Weidong, United States Department of Agriculture (USDA) Agriculture Research Service (ARS), Washington State University, Pullman, WA 99164, USA, [email protected] Coyne, C., Western Regional Plant Introduction Station, 59 Johnson Hall, Pullman, WA, USA, [email protected] Cubero, J.I., Departamento de Mejora Genética Vegetal, Instituto de Agricultura Sostenible (CSIC), Apartado 4084, 14080 Córdoba, Spain, [email protected] Davidson, Jenny, South Australian Research and Development Institute, GPO Box 397, Adelaide, SA 5001, Australia, [email protected] Diekmann, Jürgen, International Center for Agricultural Research in the Dry Areas (ICARDA), PO Box 5466, Aleppo, Syria, [email protected] Erskine, William, Centre for Legumes in Mediterranean Agriculture (CLIMA), The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia, [email protected]. au Fernández-Aparicio, M., Institute for Sustainable Agriculture, CSIC, Apdo 4084, E-14080 Córdoba, Spain, [email protected] Ford, Rebecca, BioMarka, Faculty of Land and Food Resources, The University of Melbourne, Victoria, 3010, Australia, [email protected] Fratini, R., Departamento de Biología Molecular, Universidad de León, León, Spain, richard.fratini@ unileon.es Furman, B.J., United States Department of Agriculture (USDA) Agriculture Research Service (ARS), Subarctic Agricultural Research Unit, 533 East Fireweed Avenue, Palmer, AK 99645, USA, Bonnie. [email protected] Gangaiah, B., Division of Agronomy, Indian Agricultural Research Institute, New Delhi, India, [email protected] Grusak, Michael A., United States Department of Agriculture (USDA) Agriculture Research Service (ARS), Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, 1100 Bates Street, Houston, TX 77030, USA, [email protected] Haddad, Atef, International Center for Agricultural Research in the Dry Areas (ICARDA), PO Box 5466, Aleppo, Syria, [email protected] Islam, Q.M., Shaﬁqul, Bangladesh Agricultural Research Institute, Joydebpur, Gazipur-1701, Bangladesh, qazishaﬁ[email protected] Kharrat, M., National Institute for Agronomic Research (INRAT), Tunis, Tunisia, moha.kharrat@ gmail.com Kumar, Shiv, Indian Institute of Pulses Research, Kanpur 208024, India, [email protected] Kumari, Safaa G., International Center for Agricultural Research in the Dry Areas (ICARDA), PO Box 5466, Aleppo, Syria, [email protected] Larsen, Richard, United States Department of Agriculture (USDA) Agriculture Research Service (ARS), 24106 N. Bunn Road, Prosser, WA 99350, USA, [email protected] Lutfor Rahman, M., Bangladesh Agricultural Research Institute, Gazipur 1701, Bangladesh, Lutfur@ bari.gov.bd Makkawi, Mohamed, Seed Technology Unit, Dhaid Research Station, Ministry of Environment and Water, PO Box 12503, Dhaid, Sharjah, United Arab Emirates, [email protected]

Contributors

ix

Makkouk, Khaled M., International Center for Agricultural Research in the Dry Areas (ICARDA), PO Box 5466, Aleppo, Syria, [email protected] Materne, M., Grains Innovation Park, Department of Primary Industries, Private Bag 260, Horsham, Victoria 3401, Australia, [email protected] Matiur Rahman, M., Bangladesh Agricultural Research Institute, Gazipur 1701, Bangladesh, [email protected] McNeil, David L., School of Agricultural Science, University of Tasmania, Hobart, Tasmania, Australia, [email protected] Mihov, Miho, Dubroudja Agricultural Institute, General Toshevo, 9520, Bulgaria, [email protected] Muehlbauer, Fred J., United States Department of Agriculture (USDA) Agriculture Research Service (ARS), 303 Johnson Hall, Washington State University, Pullman, WA 99164-6434, USA, muehlbau@ wsu.edu Mustafa, Barkat, BioMarka, Faculty of Land and Food Resources, The University of Melbourne, Victoria, 3010, Australia, [email protected] Niane, Abdoul Aziz, Seed Unit, International Center for Agricultural Research in the Dry Areas (ICARDA), PO Box 5466, Aleppo, Syria, [email protected] Pala, Mustafa, International Center for Agricultural Research in the Dry Areas (ICARDA), PO Box 5466, Aleppo, Syria, [email protected] Pérez de la Vega, M., Departamento de Biología Molecular, Universidad de León, León, Spain, m. [email protected] Pramanik, S.C., Indian Institute of Pulses Research, Kanpur 208024, Uttar Pradesh, India, [email protected] Quinn, Mark A., Department of Crop and Soil Sciences, Washington State University, Pullman, WA 99164-6420, USA, [email protected] Raghuvanshi, Rita S., Dean, College of Home Science, G.B. Pant University of Agriculture and Technology, Pantnagar 263145, India, [email protected] Rajesh, P.N., United States Department of Agriculture (USDA) Agriculture Research Service (ARS) and Department of Crop and Soil Sciences, 303 Johnson Hall, Washington State University, Pullman, WA 99164-6434, USA, [email protected] Redden, B., Australian Temperate Field Crops Collection, Department of Primary Industries, Private Bag 260, Horsham, Victoria 3401, Australia, [email protected] Regassa, Senait, Oxfam America-Horn of Africa Regional Ofﬁce, Addis Ababa, PO Box 25779 code 1000, Ethiopia, [email protected] Rubiales, Diego, Institute for Sustainable Agriculture, Consejo Superior de Investigaciones Cientíﬁcas (CSIC), Apdo 4084, E-14080 Córdoba, Spain, [email protected] Sabaghpour, S., Dryland Agricultural Research Institute, Kermenshah, Iran, [email protected] Sarker, Ashutosh, International Center for Agricultural Research in the Dry Areas (ICARDA), PO Box 5466, Aleppo, Syria, [email protected] Saxena, Mohan C., A-22/7 DLF City, Phase 1, Gurgaon, Haryana 122002, India, m.saxena@cgiar. org Sharma, Balram, Division of Genetics, Indian Agricultural Research Institute, New Delhi 110012, India, [email protected] Sharma, S.K., National Bureau of Plant Genetic Resources, Pusa Campus, New Delhi 110012, India, [email protected] Shivakumar, B.G., Division of Agronomy, Indian Agricultural Research Institute, New Delhi, India, [email protected] Shrestha, R., National Grain Legumes Research Program, Rampur, Nepal, renuka_shrestha@hotmail. com Siddique, K.H.M., Institute of Agriculture/Centre for Legumes in Mediterranean Agriculture, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia, [email protected]

x

Contributors

Singh, D.P., Dean, College of Post Graduate Studies, G.B. Pant University of Agriculture and Technology, Pantnagar 263145, India, [email protected] Singh, Guriqbal, Department of Plant Breeding, Genetics and Biotechnology, Punjab Agricultural University, Ludhiana, Punjab, India, [email protected] Singh, K.K., Indian Institute of Pulses Research, Kanpur 208024, Uttar Pradesh, India, singhkk28@ rediffmail.com Taylor, Paul W.J., BioMarka/Center for Plant Health, School of Land and Environment, The University of Melbourne, Victoria 3010, Australia, [email protected] Tullu, Abebe, Crop Development Centre, University of Saskatchewan, Saskatoon, SK S7N 5A8, Canada, [email protected] Turner, David W., School of Plant Biology, Faculty of Natural and Agricultural Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia, David.Turner@ uwa.edu.au Turner, Neil C., Centre for Legumes in Mediterranean Agriculture, M080, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia, [email protected] Ujagir, Ram, Department of Entomology, G.B. Pant University of Agriculture and Technology, Pantnagar 263145, India, [email protected] Vandenberg, Albert, Crop Development Centre, University of Saskatchewan, Saskatoon, SK S7N 5A8, Canada, [email protected] Vishnyakova, M., Leguminous Crops Genetic Resources Department, N.I. Vavilov Institute of Plant Industry (VIR), 42–44, Bolshaya Morskaya Street, 190000, St Petersburg, Russia, m.vishnyakova@ vir.nw.ru Yadav, N.K., National Grain Legumes Research Program, Rampur, Nepal, nkyadav56@rediffmail. com Yadav, S.S., National Agricultural Research Institute (NARI), Kana Aburu Haus PO Box 4415 Lae 411, Morobe Province, Papua New Guinea, [email protected] Yenish, Joseph P., Department of Crop and Soil Sciences, Washington State University, Pullman, WA 99164-6420, USA, [email protected]

Foreword

Lentil, its ancient origins notwithstanding, is very much a crop for today’s world – which must confront the problems of food security, poverty and water scarcity, and find sustainable food systems in a changing climate. Lentil can help address each of these concerns. It has highly digestible, proteinrich grain, ‘fixes’ nitrogen through association with bacterial rhizobia, uses water efficiently, and is a vital component of cereal-based systems in marginal environments. Once considered primarily a food for the poor, its virtues are now widely appreciated. I clearly recall my appointment as the first lentil breeder at the International Center for Agricultural Research in the Dry Areas (ICARDA), and the excitement of being a young researcher at a young research centre. I contributed to the excellent book Lentils, edited by Colin Webb and Geoffrey Hawtin, published by CABI in 1981. Twenty-seven years later, it is time to take stock of the progress made. During this period, the global area under lentil cultivation has grown by over 70%. Production has increased by nearly 160%, partly due to the increase in cultivated area, but more importantly because productivity has increased by two-thirds. Clearly, considerable progress has been made in translating research results into higher yields at farm level. However, with population growth fuelling an ever-increasing demand for food, further yield improvements will be needed. It is my earnest hope that this book, which provides a comprehensive review of current lentil research, will act as a ‘knowledge platform’ for further advances. Mahmoud Solh Director General, ICARDA

xi

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1

Introduction

W. Erskine,1 F.J. Muehlbauer,2 A. Sarker3 and B. Sharma4 1The

University of Western Australia, Crawley, Western Australia, Australia; State University, Pullman, Washington, USA; 3International Center for Agricultural Research in the Dry Areas (ICARDA), Aleppo, Syria; 4Indian Agricultural Research Institute, New Delhi, India 2Washington

The lentil (Lens culinaris Medikus subsp. culinaris) is a lens-shaped grain legume well known as a nutritious food. It grows as an annual bushy leguminous plant typically 20–45 cm tall, which produces many small purseshaped pods containing one to two seeds each. The morphology of the crop is detailed by Saxena (Chapter 4, this volume). Lentil seed is a rich source of protein, minerals (K, P, Fe, Zn) and vitamins for human nutrition (Bhatty, 1988). Furthermore, because of its high lysine and tryptophane content, its consumption with wheat or rice provides a balance in essential amino acids for human nutrition. Lentil straw is also a valued animal feed (Erskine et al., 1990). Lentils were among the earliest of humankind’s plant domesticates (einkorn and emmer wheats, barley, pea, flax and lentil) and are associated with the start of the ‘agricultural revolution’ in the Near East (see Cubero et al., Chapter 3, this volume). The crop was part of the assemblage of neareastern grains that spread across the Old World. It is now produced across the dry areas of the globe and, in the Old World, from Bangladesh in the east to Morocco in the west, and from Russia in the north to Ethiopia in the south. The adaptation of the crop is discussed by Materne and Siddique (Chapter 5, this volume). With these origins it can be no surprise that the crop is well referenced in early literature. Esau sold his birthright for a mess of pottage made of lentils (Bible Genesis 25: 29–34). Lentils are also listed in the Koran (Second Surah; Al-Baqarah) as one of the products of the earth which the Jews asked Moses to request from God, following the period in which manna and quails were the only food available to them. A paste of cooked lentils was found in Egypt in a 12th-Dynasty tomb at Thebes (2400–22 bc). The Romans used lentils widely in soups and Apicius, who in the 1st century wrote the oldest surviving book on cookery, included a recipe for lenticulata – a wellspiced dish of lentil and mussels with honey and vinegar. Its ancient and © CAB International 2009. The Lentil: Botany, Production and Uses (eds W. Erskine et al.)

1

2

W. Erskine et al.

rather more obscure uses include being used as packing material to transport a Middle Kingdom obelisk from Egypt to Rome in the reign of the Emperor Caligula, and as the preferred feed for the Roman army’s information network – carrier pigeons (Nygaard and Hawtin, 1981). Today orange split and dehulled lentil is an important dal eaten with rice and wheat in South Asia. In the Middle East lentil soup and mujaddarah (whole lentil with cracked wheat or rice) are popular. Uses of lentil are covered by Raghuvanshi and Singh (Chapter 25, this volume). Currently lentil is primarily grown in the developing world with a particular concentration in Asia where India and Turkey are the largest producing countries (see Erskine, Chapter 2, this volume). Global production of lentil is at c.3.6 million t. In the New World, Canada is the leading producer followed by the USA and Mexico with pockets of production in Argentina, Chile, Colombia, Ecuador and Peru. In Europe, Spain, France and Russia are the major lentil producers. Australia has come to dominate southern hemisphere production since the late 1990s. Internationally the trade in small-seeded, red cotyledon lentil is dominated by Australia, Canada and Turkey, whereas the market in the large-seeded, ‘green’ lentil is held by Canada and the USA. Countries in the Indian subcontinent, West Asia and North Africa are the major importers of red lentil. Southern Europe and South America import large-seeded green lentils. Spain is a major importer of the so-called Spanish brown lentil produced in the US Pacific Northwest. Lentil is an important food legume crop component of farming and food systems of many countries globally. It plays an important role in human, animal and soil health improvement occupying a unique position in cereal-based cropping systems. Its ability in nitrogen fixation and carbon sequestration improves soil nutrient status, which in turn provides sustainability in crop production systems. Lentil is tolerant of different soil types and of low fertility and this has assured its place as a crop of marginal lands. Globally lentil productivity was only 560 kg/ha during the period 1961–1963 and reached 950 kg/ha by 2004–2006. Despite the increase, these current yields are still low by comparison with other crops because of the limited yield potential of lentil landraces, which are also vulnerable to an array of stresses. Yield limiting factors are lack of seedling vigour, slow leaf area development, high rate of flower drop, low pod setting, poor dry matter, low harvest index, lack of lodging resistance, low or no response to inputs, and exposure to various biotic and abiotic stresses. The major abiotic limiting factors to production are low moisture availability (see Shrestha et al., Chapter 12, this volume) and high temperature stress in spring, and, at high elevations, cold temperatures in winter. Mineral imbalances like boron, and salinity and sodicity though localized do cause substantial yield loss (see Yadav et al., Chapter 13, this volume). Among biotic stresses, lentil rust, vascular wilt and Ascochyta blight diseases are the most important fungal pathogens (see Chen et al., Chapter 17, this volume). Additional constraints to production include agronomic problems of pod dehiscence and lodging, and suboptimal crop management.

Introduction

3

Adequate variability for many of the crop’s genetic constraints exists within the crop gene pool allowing manipulation through plant breeding (see Furman et al., Chapter 6; Sharma, Chapter 7; Sarker et al., Chapter 8; Rahman et al., Chapter 9; and Muehlbauer et al., Chapter 10, all in this volume). However, several other important traits, such as biomass yield, pod shedding, nitrogen fixation, resistance to pea leaf weevil (Sitona sp.) and aphids, and the parasitic weed broomrape (Orobanche sp.) are not currently addressable by breeding because of insufficient genetic variation. Molecular approaches may be applied to solve some of these intractable problems. Looking forward, escalating costs to produce inorganic nitrogen fertilizer, reducing availability of water for agriculture, climate change, and an increasingly nutrition-conscious consumer society collectively give a bright future for a highly nutritious food produced by a nitrogen-fixing crop like lentil adapted to the cereal-based farming systems in marginal lands.

References Bhatty, R.S. (1988) Composition and quality of lentil (Lens culinaris Medik.): a review. Canadian Institute of Food Science and Technology 21, 144–160. Erskine, W., Rihawe, S. and Capper, B.S. (1990) Variation in lentil straw quality. Animal Feed Science and Technology 28, 61–69. Nygaard, D.F. and Hawtin, G.C. (1981) Production, trade and uses. In: Webb, C. and Hawtin, G.C. (eds) Lentils. Commonwealth Agricultural Bureau, Slough, UK, pp. 7–13.

2

Global Production, Supply and Demand W. Erskine The University of Western Australia, Crawley, Western Australia, Australia

2.1. Introduction This chapter surveys global and national production, export and demand/ consumption of lentil. It provides an update on the topic written in 1981 by Nygaard and Hawtin in Lentils (Nygaard and Hawtin, 1981). The chapter is based primarily on FAOSTAT – the statistical database of the United Nations Food and Agriculture Organization (FAO, 2008), which provides country-/ global-level estimates of crop production, area harvested, yield, exports, imports and consumption since 1961. So we can see the ‘big picture’. But crucially it provides no hint of the situation at the sub-national, district and importantly household level.

2.2. Production, Productivity and Area Globally lentil ranks sixth in terms of production among the major pulses after dry bean, pea, chickpea, faba bean and cowpea (Table 2.1). World lentil production constituted 6% of total dry pulse production in 2003–2006. World lentil production has risen steadily by four times (412%) from an average of 917,000 t in 1961–1963, when data collection started, to 3,787,000 t in 2004–2006 (Fig. 2.1). The growth is clearly in two phases: Phase 1 was from 1961 to 1979 with a growth rate of b = 25,900 t/year (R2 = 0.85) and Phase 2 since 1980 with a faster growth of b = 79,100 t/year (R2 = 0.84). The production gains come from a combination of increases in both area sown and productivity per hectare. The area harvested in the same time period has risen steadily from 1.639 million ha in 1961–1963 to 3.982 million ha in 2004–2006 with b = 60,200 ha/year (R2 = 0.95) (Fig. 2.1).

4

© CAB International 2009. The Lentil: Botany, Production and Uses (eds W. Erskine et al.)

Global Production, Supply and Demand Table 2.1. 2008).

5

Global production as dry grain of major pulses from 2003 to 2006 (Source: FAO,

Pulse

Production (1000 t)

Beans Peas Chickpeas Faba beans Cowpeasa Lentils Pigeon peasa Other pulsesa Total pulsesa only available to 2003–2004.

4.5

Area harvested (million ha)

4.5 4.0

4.0

b = 60.2; R 2 = 0.95

3.5

3.5 3.0

3.0 2.5

2.5

2

b = 79.1; R = 0.84

2.0

2.0

1.5

1.5 1.0

1.0 0.5

0.5

2

b = 25.9; R = 0.85

06

03

20

00

20

20

97

94

19

91

19

88

19

85

19

82

19

79

19

76

19

73

19

70

19

67

19

19

64

0

19

61

0

19

Production (million t)

aData

18,791 11,167 7,979 4,452 3,890 3,563 3,185 6,334 59,361

Years

Fig. 2.1. Annual evolution of global lentil production (million t; ◆) and area harvested (million ha; ■) since 1961 (Source: data from FAO, 2008).

Global lentil productivity was only 560 kg/ha in 1961–1963, while it reached 950 kg/ha by 2004–2006, increasing overall by a healthy rate of 8.6 kg/ha/year (R2 = 0.85) (Fig. 2.2). Lentil production is concentrated in the developing world, whence 75% of production emanated in 2002–2006. The ‘big three’ lentil producers are India, followed by Canada and then Turkey, which collectively accounted for 68% of global production in 2002–2006 (Fig. 2.3 and Table 2.2). Most lentils are grown in Asia, where production totalled 2,300,890 t in 2002–2006 accounting for 61% of lentil production globally (Table 2.2). India is the biggest lentil producing country in the world, producing 972,100 t of lentil from 1.492 million ha in 2002–2006. In Asia the top league of lentil producers comprises in descending order India, Turkey, Nepal, Syria, China, Bangladesh and Iran, all of which produce more than 100,000 t/year. To this list Pakistan may be added as the only other substantial producer.

6

W. Erskine 1200 y = 8.6111x + 503.7 R 2 = 0.849

Mean yield (kg/ha)

1000 800 600 400 200 0 1961

1966

1971

1976

1981 1986 Year

1991

1996

2001

2006

Fig. 2.2. Annual global mean grain yields (kg/ha) since 1961 (Source: FAO, 2008).

Europe 1% Other Asia 19% Turkey 16%

Canada 26%

India 26% Other North America 6% Africa 3%

Australasia 3% South America 0%

Fig. 2.3. Distribution of global lentil production among India, Canada and Turkey (the ‘big three’ producers) and by continent (Source: FAO, 2008).

Other Asian countries listed in Table 2.2 regularly produce less than 5000 t/ year. Over the last two decades lentil production has dropped markedly in Iraq, Jordan and Lebanon. Yields in Asia averaged 817 kg/ha, which is significantly below the world average of 936 kg/ha. So those areas where lentils are most important are those with the lowest yield. Within Asia, productivity is particularly

Global Production, Supply and Demand

7

Table 2.2. Global, continental and national lentil production (1000 t), area harvested (1000 ha) and mean yield (kg/ha) from 2002–2006 (Source: FAO, 2008).

Region

Country

Africa Algeria Egypt Eritrea Ethiopia Kenya Madagascar Malawi Morocco Tunisia Asia Armenia Azerbaijan Bangladesh China India Iran Iraq Israel Jordan Lebanon Myanmar Nepal Pakistan Palestine Syria Tajikistan Turkey Uzbekistan Yemen Europe Bulgaria Croatia Cyprus Czech Republic France Greece Hungary Iceland Italy Macedonia Russia Slovakia Spain Ukraine

Area (1000 ha) 146.74 1.15 1.03 0.50 89.56 0.37 1.13 1.59 49.60 1.80 2817.36 0.01 1.14 130.20 69.00 1491.50 225.54 2.25 0.10 0.88 0.80 3.64 186.03 38.65 0.84 143.90 0.45 439.90 0.90 9.32 55.15 1.99 0.09 0.01 0.00 10.32 1.47 0.45 1.76 0.10 8.20 0.83 29.83 0.10

Production (1000 t) 94.56 0.54 1.82 0.03 64.00 0.57 0.73 1.54 24.45 0.88 2300.89 0.02 2.11 118.95 144.23 972.10 113.23 2.00 0.03 0.57 0.80 1.84 159.34 21.90 0.54 159.33 0.40 596.34 0.35 6.81 41.74 2.27 0.12 0.01 0.00 14.78 1.75 0.53 0.03 1.21 0.08 8.64 1.00 11.26 0.06

Productivity (kg/ha) 644 468 1761 60 715 1520 647 973 493 490 817 2125 1856 914 2090 652 502 889 300 644 1000 504 857 567 643 1107 889 1356 389 731 757 1140 1280 565 333 1432 1188 1189 688 764 1053 1216 378 600 (Continued)

8

W. Erskine

Table 2.2. continued

Region

Country

Area (1000 ha)

Production (1000 t)

Productivity (kg/ha)

Canada Mexico USA

887.11 708.20 7.72 171.19

1227.30 985.35 7.36 234.60

1383 1391 953 1370

141.23 139.63 1.60 13.28 1.50 1.16 3.90 3.16 3.56 4060.86

126.95 124.00 2.95 9.08 2.00 0.89 1.10 2.08 3.01 3800.52

899 888 1844 684 1333 769 282 658 846 936

North and Central America

Australia and Oceania Australia New Zealand South America Argentina Chile Colombia Ecuador Peru World

low in South Asia with mean yields in Bangladesh, India, Nepal and Pakistan averaging 914, 652, 857, and 567 kg/ha, respectively. Africa accounts for only 2.4% of lentil production globally and African production is characterized by a low mean yield of 644 kg/ha. The only significant producers are Ethiopia with a mean harvested area of 90,000 ha and Morocco with 50,000 ha. Over the last three decades lentil production in both Algeria and Egypt, once substantial, has dwindled to insignificance. Both have become major importers. Europe accounts for just 1.1% of global lentil production with 42,000 t produced annually in 2002–2006. In terms of area harvested the main producers in Europe, in descending order, are Spain, France and Russia. Lentil production in North America constitutes 32.2% of the total global picture. Canada is the dominant player producing an average of 985,000 t with a high average yield of 1391 kg/ha. Canada is now the world’s second largest lentil producer after India and this emergence into global lentil production has arisen since the 1980s. In South America total lentil production averaged only 9080 t/year and is now not significant globally because of decreases in production over the last two decades in Argentina, Chile and Colombia, where lentil was formerly important. Australasia has arisen to prominence in lentil production through the widespread production of the crop in Australia, where the area harvested was 140,000 ha and production 124,000 t in 2002–2006. This growth in lentil production in Australia occurred in the late 1990s.

Global Production, Supply and Demand

9

Looking nationally at the importance of lentils against other pulses, lentil dominates the pulse sector in Nepal and constituted 60% of total dry pulse production in 2002–2006. Elsewhere the percentage of lentil against total pulse production was in descending order: Syria 52%, Bangladesh 35% (not accounting for grass pea), Turkey 34%, Jordan 20%, Canada 19% and Iran 16% in 2002–2006. In India – the world’s largest lentil producer – lentil production accounted for only 7% of the total pulse production of 13.4 million t in 2002–2006. The seedcoat colour of lentils can be green, tan, grey, brown or black and the colour is often accompanied by mottling and speckling patterns. Cotyledons are yellow, red or uncommonly green. Lentil production comprises approximately 70% of red cotyledon small-seeded rounded lentils, typically 2–4.5 mm in diameter called red lentils; 25% large-seeded (4–6 mm in diameter) more flattened seeds with yellow cotyledons, commonly known as green lentils; and 5% brown lentils and other types.

2.3. Exports The annual global export of lentil was 1,140,805 t in 2003–2005. This comprised 31.7% of production globally. Canada dwarfed other lentil exporting nations by annually shipping 441,925 t of lentil in 2001–2005 (Table 2.3). The top five exporters collectively accounted for 81% of global exports and after Canada, the other important exporters fall into two groups: (i) the major developing-world producers – India and Turkey; and (ii) middle-ranking production countries in the developed world – Australia and USA, where the crop is grown primarily as an export commodity. The export trade is composed of different lentil types: small ‘red’ lentils sold as either red splits; red de-hulled but un-split, called ‘football’; and small-seeded entire grains (usually with red, and unusually yellow, cotyledons); and green lentils – large-seeded more flattened seeds with yellow cotyledons. Although reliable data are unavailable on the relative importance of these various sectors, approximately 60% of world trade is in red lentils, 35% in the greens, and 5% the browns and others. Table 2.3. Average annual exports (t) of lentil from top exporting nations from 2001 to 2005 (Source: FAO, 2008). Country

Exports (t)

Canada India Turkey Australia USA Syria Nepal China

441,925 140,687 127,669 107,701 105,976 39,470 34,934 25,066

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W. Erskine

2.4. Demand/Consumption We have already seen that lentil is primarily grown in the developing world and especially in Asia. The major lentil-growing nations in the developed world (Canada, USA and Australia) grow lentil to export it mostly to the developing world (Table 2.3). So the increasing demand for lentil consumption is one from the developing world spurred by growing numbers of mouths to feed. There can be little doubt that the main driver for increased demand and consumption of lentil is the increasing population in Asia. Turning to the other side of the coin, as 31.7% of the crop is exported so – very importantly – 68.3% is eaten locally. Lentil grain has a high level of protein, and also contains dietary fibre, vitamin B1 and minerals (see Grusak, Chapter 23, this volume). Lentils are mostly mixed with the carbohydrate staples rice and wheat, which results in a complete protein diet (see Chapter 23). So the crop is making a major contribution to diets, especially in the Third World of Asia. Turning to imports (Table 2.4), the situation is much more diversified than for exports, for which the trade is concentrated among five key players, with the top ten importers spanning only 59% of global trade. Among importing countries there are several types: ●

First, there are India and Turkey, both of which are both major producers and trading nations. They import in order to complete trading contracts

Table 2.4. Imports (t) of lentil into the top-40 importing countries (including food aid) from 2001 to 2005 (Source: FAO, 2008). Rank

Country

Imports (t)

Rank

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Bangladesh Egypt Sri Lanka Algeria Pakistan Colombia Spain India Turkey Italy Sudan Mexico Saudi Arabia France Peru Germany Morocco Ecuador Venezuela USA

117,306 97,574 93,172 57,288 55,078 53,956 49,990 49,638 31,929 30,397 30,027 28,540 26,029 24,199 21,867 21,228 16,560 14,521 14,519 13,984

21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

Country Ethiopia UK Netherlands Chile Belgium Greece Brazil Eritrea Israel Jordan Canada Lebanon Malaysia Argentina Haiti Kuwait Iran South Africa Portugal Panama

Imports (t) 13,927 13,793 13,060 12,851 12,377 11,290 10,837 9,322 9,044 7,793 7,516 6,679 6,233 6,041 4,768 4,694 4,586 4,389 4,085 4,052

Global Production, Supply and Demand

11

Table 2.5. Extract from FAO lentil consumption data (kg/capita/year) (Source: FAO, 2008). Country Canada Sri Lanka Nepal Syria Turkey Eritrea Lebanon Algeria Jordan Colombia Iran Bangladesh

●

●

●

●

Consumption (kg/capita/year) 6.0 4.5 4.1 3.7 2.9 2.9 2.6 2.3 2.2 2.1 1.5 1.5

when on occasion national production is insufﬁcient to meet export demands. Second, there are those countries where historically lentil was grown and consumed and there remains a residual demand in the diet for lentil grain. But in these countries production has dropped over the last few decades. Such countries include Egypt, Algeria, Pakistan and Colombia. A third but similar group of countries are those which have rapidly growing populations, a high consumption demand but still maintain lentil production. This group comprises Mexico and Bangladesh, which both import from their much larger neighbours. Fourth, there are European countries such as Spain, Italy and France where there is a demand for vegetarian food like lentil and this demand outstrips the local supply. Finally, there are countries such as Sri Lanka and those of the Middle East where the crop is not produced but lentil forms part of the diet.

Consumption data from FAO in Table 2.5 confirm the importance of lentil in the diet in several very poor countries such as Bangladesh, Eritrea, Nepal and Sri Lanka. Macro-data give no picture of the consumption of the crop within countries by region and by social group. However, pulses are generally consumed by the poorer sector of the population who cannot afford meat products as a result of their high price. In Bangladesh it is recognized that protein deficiency and vitamin A deficiency are major nutritional problems, with consequences to Bangladesh’s health (Rosenberg, 2005). The consumption and use of lentil at the local level has been investigated within nutrition surveys in Ethiopia (Yetneberk and Wondimu, 1994) and Syria (Mokbel, 1986; Ghosh, 2004). Lentil is an important dietary item in several – often poor – parts of the Third World, contributing to warding off malnutrition through

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W. Erskine

a balanced diet. Clearly the old adage that lentils are ‘poor man’s meat’ still remains firmly applicable today.

References Food and Agriculture Organization (FAO) (2008) FAOSTAT Statistical Database of the United Nations Food and Agriculture Organization (FAO), Rome. Available at: http://faostat.fao.org/site/567 (accessed 18 June 2008). Ghosh, S.A. (2004) Poverty, household food availability and nutritional well-being of children in north west Syria. PhD thesis, University of Massachusetts, Amherst, Massachusetts, USA. Mokbel, M. (1986) Nutritional and dietary patterns in rural Syria: implications for ICARDA mandate crops. Farming Systems Research Report No. 18. International Center for Agricultural Research in the Dry Areas (ICARDA), Aleppo, Syria. Nygaard, D.F. and Hawtin, G.C. (1981) Production, trade and uses. In: Webb, C. and Hawtin, G.C. (eds) Lentils. Commonwealth Agricultural Bureau, Slough, UK, pp. 7–13. Rosenberg, I.H. (2005) Interdepartmental Committee on Nutrition for National Defense Surveys in Asia and Africa. Journal of Nutrition 135, 1272–1275. Yetneberk, S. and Wondimu, A. (1994) Utilization of cool season food legumes in Ethiopia. In: Telaye, A., Bejiga, G., Saxena, M.C. and Solh, M.B. (eds) Cool-Season Food Legumes of Ethiopia. International Center for Agricultural Research in the Dry Areas (ICARDA), Aleppo, Syria, pp. 60–73.

3

Origin, Phylogeny, Domestication and Spread J.I. Cubero,1 M. Pérez de la Vega2 and R. Fratini2 1Instituto

de Agricultura Sostenible (CSIC), Córdoba, Spain; 2Universidad de León, León, Spain

3.1. Historical Data Lentil was one of the first domesticated plant species, its remains being as old as those of einkorn, emmer, barley and pea (Harlan, 1992). It has been cultivated for 10,000 years in the most difficult agricultural environments, being perhaps second only to barley in this sense. The plant was given the scientific name Lens culinaris in 1787 by Medikus, a German botanist and physician (for references given in this section, see Cubero, 1981). Since 3029 bp, at least, they were popular and appreciated in Egypt, being offered as presents to the gods. According to Athenaeus, ‘Alexandria is full of lentil dishes.’ Around 2100 years ago lentils had the same price as wheat, but later the price declined, as Martial states in one of his Epigrams: ‘receive lentils of the Nile, a present for Pelusium; they are cheaper than spelt…’. Martial and also Juvenal, another Roman writer, described a lentil dish eaten by the poorest, in which lentils were cooked together with the pods. The Greek philosopher Theophrastus (~2300 bp) mentions ‘a white kind that is sweeter’. The ancient Greek enjoyed lentils very much, especially in soups. Aristophanes (2400 bp) said: ‘You who dare to insult lentil soup, sweetest of delicacies.’ The Greeks also made bread out of lentil flour. In Rome, Columella (~1950 bp) said that they were too valuable as human food to be used as animal fodder, even when they were used to feed pigeons; he placed them only after faba beans among pulses. Romans imported lentils from Egypt, where Pliny described the growing of lentil plants from seed and reported the varieties sown at the time; he described two varieties ‘one rounder and blacker, the other normal in shape’. Pliny also mentioned the medicinal properties of lentils and a variety of ways of boiling or otherwise cooking lentil seeds for a number of remedies. At the same time, the naturalist Dioscorides (~1950 bp) mentions lentils in his De Materia Medica, and Apicius gives details of several lentil recipes. © CAB International 2009. The Lentil: Botany, Production and Uses (eds W. Erskine et al.)

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J.I. Cubero et al.

In the Middle Ages, lentil was a minor crop. Al Awam, a writer from southern Spain in the 12th century, mentions two varieties: one of them ‘large and white’ that, when soaked in water, does not produce a black tint; a second being a ‘wild’ species of very poor quality. The 15th-century Hortus Sanitatis, collecting information from the Dioscorides and other ancient references, lists some medicinal properties of lentils. In Spain, GabrielAlonso de Herrera writes in 1502 ‘the best ones are the biggest ones … they are large and white and do not produce a black tint in water.’ He also mentions that lentils were grown in light and dry soils, in rather cool places and generally in fallow lands: ‘their culture is not expensive at all since it is not necessary to plough to sow them’. If they are grown it is because ‘in some years lentils were very well sold’. Tournefort, based on several authors of the 17th century, lists seven ‘species’, briefly described as: (i) vulgaris, reddish seed (perhaps var. variabilis Bar.); (ii) vulgaris, yellowish seed (var. vulgaris Bar.?); (iii) vulgaris, blackish seed; (iv) maculata, marbled (var. dupuyensis Bar.); (v) major (var. macrosperma Bar.); (vi) hungarica major, perennis (perhaps nummularis Bar.); and (vii) monanthos (perhaps a type not known in Europe at the present time). Tournefort’s description and drawings are excellent. The only doubtful point is the qualification of perennis given to hungarica. Miller, in 1741, lists only three ‘species’: (i) vulgaris, common lentils; (ii) major, greater lentils; and (iii) monanthos, lentils with a single flower. He states that: there are several varieties of the first and second sorts, which differ from each other in the colour of their flowers and fruits; but they are accidental and will often arise from the same seeds … these plants are very common in the warm parts of Europe, and in the Archipelago, where they are food of the poorer sort of people … these plants are one of the least of the pulse kind … they will be grown upon a dry barren soil best.

As in the time of Columella, lentils were also used to feed pigeons. A rural ‘Cyclopaedia’ (sic) of the mid-19th century mentions that they were introduced into England from France during the 15th century, and by the middle of the 19th century Britain had four varieties that were briefly described as big, small, red and yellow. Thus, it seems that the European variety structure was largely the same from the 16th to the 19th century and probably the same as in the Middle Ages. If lentils have been maintained by farmers through the ages, it is most likely because they grow in poor soils, rough climates and harsh conditions for humans, animals and crops. In many cases, they may be the only source of protein available to farmers.

3.2. The Genus Lens and the Vicieae The word Lens was used by Tournefort to name his genus III of his classis X (De herbis et suffruticihus). Lens had been already used by most of the many ‘Theatri’, ‘Prodomi’, ‘Horti’ and ‘Historiae Plantarum’ during the

Origin, Phylogeny, Domestication and Spread

15

16th century, but Tournefort was the first to use this word to designate a specific genus (historical references in Cubero, 1981). After him, Lens was also considered a genus by Miller, and by Adanson (who separated Tournefort’s Vicia, Ervum and Lens), and by Moench who included his Lens esculenta (= L. culinaris Medikus) and Lens monantha (= Vicia monanthos) in his Lens genus. Linnaeus included it into Cicer and later in Ervum. The Linnean Ervum was split very soon into Ervum and Lens, and later into Ervilia as well. The first to use Lens systematically in a modern concept was Godron (1843), who established the differential characteristics of Vicia, Ervum and Ervilia; but during the 19th century, most of the authors followed the Linnean treatment; others preferred Godron’s. Boissier included Ervilia and the non-Lens Ervum species in Vicia, keeping the name Ervum for the actual Lens (Ervum Boissier is thus a synonym of Lens Miller). Some others included Lens in Vicia and even in Cicer and Lathyrus. The idea of merging Lens into Vicia has been kept up to recent times as well as the use of Ervum Boissier instead of Lens. All the other names, including Ervum sensu Linnaeus, were abandoned by the end of the 19th century. There was also confusion concerning the author to whom the name Lens had to be credited. Even in recent times, well known floras have credited it sometimes to Adanson, Moench and Tournefort and also to Grenier and Godron. Finally, the Congress on Botanical Nomenclature decided in 1966 to conserve Miller as the author. Lens Miller is, thus, a nomen conservatum, having priority over older names (Gunn, 1969). All the confusion just described has a strong biological basis. The tribe Vicieae is formed by four closely related genera and many intermediate forms have been recognized. They are the sources of abundant synonyms as well as of newly proposed genera. The four genera are Vicia L., Lathyrus L., Pisum L. and Lens Miller. Cicer L. was separated in a monotypic tribe, Cicerae (Kupicha, 1977). Many other genera were included previously in the tribe (for example, Ervum L., Ervilia L., Faba L., etc.) and the synonyms are many. A differential set of characteristics of the four Vicieae genera (Vicia, Lens, Pisum and Lathyrus) was given by Cubero (1981). Most of the characteristics overlap to a variable degree. Species of doubtful systematic position, sometimes raised to generic status, are frequent. For most of the morphological characters there is a ‘continuum’ from one genus to the others, especially for Vicia and Lens. In fact, Bueno (1976) studied the genus Vicia including a macrosperma accession of L. culinaris as a reference. She used a total of 59 characters (42 quantitative and 17 qualitative); the distance of Vicia faba to the closest species was much greater than that of lentils to many Vicia species, thus, challenging the independence of Lens if the old genus Faba was included in Vicia. The debate concerning a genus Lens separated from Vicia is old. Linnaeus observed: ‘[Lens] only differs from Vicia by the stigma.’ Boissier observed that Lens seems to be a Vicia with some Lathyrus characters, in particular those referring to the style. Lens seems to be one of the extremes

16

J.I. Cubero et al.

of the ‘vicieoid continuum’ as intermediate forms are found both in Vicia and in Lens, for example in Vicia section lenticula, Vicia sativa platysperma and Vicia lunata. Perhaps the best example is Lens montbretii, whose taxonomic position was doubtful (Cubero, 1981), moved to Vicia montbretii although considered as a ‘lentoid Vicia’ because of its calyx, style and flattened seeds (Ladizinsky and Sakar, 1982), although molecular data clearly distinguish Lens from V. montbretii (Mayer and Bagga, 2002). Vavilov (1949/50) showed that more or less flattened seeds can be found in all four genera; he mentioned this character as one good example of his ‘law of homologous series of variation’. The morphological ‘continuum’ can be also observed in a parallel response under domestication in lentil (L. culinaris), common vetch (V. sativa) and grass pea (Lathyrus sativus), as shown by Erskine et al. (1994). The confusion arises from the fact that the genera of Vicieae are members of a young group in active evolution radiating from a single origin, hence showing a mixture of characters. We denominate ‘a genus’ a cluster of forms sharing a greater proportion of characters than other forms, but the presence of intermediate species among genera as well as of intermediate species within a genus is unavoidable. We try to define our taxa in the most accurate way, but our words will never contain all the natural variation.

3.3. Taxonomy of Lens Morphological and molecular studies The morphological characteristics of the Lens species as well as synonyms are given by Cubero (1981). Table 3.1 summarizes the main differential characters among the species included in Lens. Intermediate forms are not infrequent, as the different Lens species are also radiating from a common ancestor. Thus, it is not surprising that Boissier described his Ervum cyaneum as a mixture of ervoides, nigricans and orientalis characters. It is easy to find herbarium specimens successively determined as nigricans and orientalis, or peduncles in orientalis without and in ervoides with awns, orientalis with large pods, strongly pubescent forms of culinaris and orientalis from Syria, Palestine and Turkey, as well as pubescent culinaris from India, and ervoides with long and large leaflets. Some authors have suggested that nigricans could have been cultivated in some areas of Turkey, but Ladizinsky (1979) thought instead that these forms could be culinaris with nigricans stipules. He also points out that the populations of nigricans reported from orientalis areas could be orientalis forms with nigricans stipules. The taxonomy was always confused with a lingering doubt about the subspecific or specific status of Lens orientalis, and the phylogenetic position of Lens nigricans within the genus. As L. orientalis is clearly the wild ancestor of the cultigen (see below), its status has to be considered as subspecific

Culinaris group differential characters (Source: Cubero, 1981; Ladizinsky, 1993, 1997; Ferguson et al., 2000).

Character Toothed stipules Leaflets per leaf Rachis length (mm) Aristate peduncle or awn Calyx teeth/corolla ratio Peduncle/rachis ratio Pod pubescent Seed diameter (mm)

ervoides

nigricans

lamottei

odemensis

tomentosus

orientalis

culinaris

No 4–6 5–15 Rarely <1 >1 Yes 2–3

Yes 6–8 8–25 Yes ≥1 >1 No 2.5–3.5

Slightly 6–10 7–10 Yes >1 >1 No 2.5–3.5

Slightly 6–8 8–20 Yes = >1 No 2.5–3.5

No 6–12 7–20 Yes >1 >1 No 2.5–3.5

No 6–8 5–25 Yes <1 >1 Rarely 2.5–3.5

No 10–16 20–50 Yes ≠1 ≠1 Rarely 4–9

Origin, Phylogeny, Domestication and Spread

Table 3.1.

17

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J.I. Cubero et al.

(i.e. L. culinaris ssp. orientalis; Harlan and De Wet, 1971). The classical structure of the genus included L. culinaris, L. orientalis, L. nigricans and Lens ervoides (Ladizinsky, 1979). In 1984, accessions of nigricans were reclassified as odemensis and a new taxonomy of the genus was proposed, Lens culinaris with cultigen subspecies culinaris and wild ssp. orientalis and odemensis, and Lens nigricans with two subspecies, nigricans and ervoides (Ladizinsky et al., 1984). However, Ladizinsky later recognized the following taxa: L. culinaris, with subspecies culinaris and orientalis, Lens odemensis, L. ervoides and L. nigricans (Ladizinsky, 1993). Two new species have been recently added to the genus, Lens tomentosus (ex L. orientalis; Ladizinsky, 1997) and Lens lamottei (ex L. nigricans; Van Oss et al., 1997). Traditional taxonomy was based on morphology; however, morphological similarities or dissimilarities do not necessarily reflect phylogenetic relationships, sometimes they are the consequence of evolutionary convergence. For instance, Fratini et al. (2006) using pollen and pistil morphological characteristics, and pollen functioning, found that L. odemensis and L. nigricans clustered closely to each other and both to L. c. orientalis, next to this cluster was L. c. culinaris microsperma; L. ervoides was loosely related to all these taxa, but L. c. culinaris macrosperma was clearly separated from all other Lens taxa including the microspermas (Table 3.2). Studies are very much dependent on both the sets of accessions and the characteristics evaluated; even with the same Lens accessions, different clusters have been obtained depending on whether quantitative or qualitative characters were scored (Ahmad et al., 1997). Ferguson et al. (2000), using morphological as well as molecular markers, considered both odemensis and tomentosus as subspecies of L. culinaris. The following classification of the genus Lens was proposed by these authors: L. culinaris, with four subspecies, namely, culinaris, orientalis, tomentosus and odemensis, L. ervoides, L. nigricans and L. lamottei. This nomenclature is currently being used by the National Centre for Biotechnology Information (NCBI). Table 3.2 shows different studies from the year 2001 onwards which have genetically grouped Lens species according to several criteria. Besides the study by Zimniak-Przybylska et al. (2001), whose phylogenetic nomenclature based on SDS-PAGE coincides with the study of Ferguson et al. (2000), the rest of the studies using other molecular markers have all clustered tomentosus and odemensis in a group apart from that including culinaris and orientalis. Recent phylogenetic analyses based upon internal transcribed spacer (ITS) sequences, molecular markers and convicilin sequences strongly suggest: (i) the divergent condition of nigricans from the remaining Lens species; (ii) the close relationship between culinaris and orientalis supporting their subspecific status; (iii) the relationships between the other taxa are less clear cut; however (a) tomentosus is the sister taxon to the culinarisorientalis group, (b) lamottei is probably the closest relative to ervoides, and (c) odemensis is generally joined to the culinaris–orientalis–tomentosus cluster (Mayer and Bagga, 2002; Sonnante et al., 2003; Durán and Pérez de la Vega, 2004).

Lens species clustered according to molecular markers, hybridization and morphological characteristics (year 2001 onwards). Clusters

Methoda

Group 1

SDS-PAGE

1 1 1 1 1 1

culinaris orientalis tomentosus odemensis culinaris orientalis

1 1 1 1

culinaris orientalis culinaris orientalis

ITS

ITS + cpDNA ITS

Group 2

Group 3

2 ervoides 2 lamottei

3 nigricans

ZimniakPrzybylska et al. (2001)

2 2 2 2 2

tomentosus odemensis ervoides lamottei odemensis

3 nigricans

Mayer and Bagga (2002)

2 2 2 2

tomentosus odemensis lamottei ervoides

3 ervoides 3 nigricans

Group 4

4 nigricans

Group 5

Group 6

Origin, Phylogeny, Domestication and Spread

Table 3.2.

Reference

Mayer and Bagga (2002) Sonnante et al. (2003)

19

(Continued)

20

Table 3.2.

continued Clusters

Methoda

Group 1

Group 2

Group 3

Group 4

Group 5

Group 6

Reference

FISH highly repeated DNA RAPD + ISSR

1 1 1 1 1 1

culinaris orientalis culinaris orientalis culinaris orientalis

2 tomentosus

3 odemensis

4 lamottei

5 ervoides

6 nigricans

Galasso (2003)

2 tomentosus

3 odemensis

4 lamottei

5 ervoides

6 nigricans

2 odemensis 2 nigricans

3 ervoides

1 1 1 1

culinaris(m) orientalis odemensis nigricans

2 ervoides

3 culinaris(M)

Durán and Pérez de la Vega (2004) Fratini et al. (2004); Fratini and Ruiz (2006) Fratini et al. (2006)

Crossability

Morphological (flower traits)b

aAbbreviations

used: cpDNA, chloroplast DNA; FISH, fluorescent in situ hybridization; ISSR, inter-simple sequence repeats; ITS, internal transcribed spacer; RAPD, random amplified polymorphic DNA. b(m), microsperma; (M), macrosperma.

J.I. Cubero et al.

Origin, Phylogeny, Domestication and Spread

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In addition, Galasso (2003), by means of in situ hybridization of highly repeated DNA sequences, found: (i) a typical fluorescent in situ hybridization (FISH) karyotype for each species; (ii) very little variation within species (except in odemensis); (iii) a great similarity between ssp. culinaris and ssp. orientalis; and (iv) favoured the separation of tomentosus and culinaris into different species, as well as that of lamottei and nigricans, in both cases despite their morphological similarity (van Oss et al., 1997). Galasso (2003) also mentioned that two Syrian tomentosus accessions were more similar in her study to culinaris than to the other tomentosus accessions, as Ferguson et al. (2000) had also found between Syrian tomentosus and orientalis. It would be interesting to find out if this similarity is a result of a misclassification, as Galasso suggests. As a summary of this section, taxonomic analyses based on morphological and/or biochemical markers ranged from four species in 1979, namely, L. culinaris, L. orientalis, L. nigricans and L. ervoides; to two species in 1984: L. culinaris (with subspecies culinaris (the cultigen), orientalis and odemensis) and L. nigricans (with ssp. nigricans and ervoides); again to four species in 1993, i.e. L. culinaris (ssp. culinaris and orientalis), L. odemensis, L. nigricans and L. ervoides; to also four species in the year 2000, i.e. L. culinaris (ssp. culinaris, orientalis, tomentosus and odemensis), L. nigricans, L. ervoides and L. lamottei; and finally to six species after 2000, which are L. culinaris (ssp. culinaris and orientalis), L. odemensis, L. tomentosus, L. nigricans, L. ervoides and L. lamottei. The contradictory results of different studies are a consequence of the evolutionary process itself. Lens species share many common structural and biochemical features, and the distances obtained in different studies are a function of the origin of the accessions involved in them, as well as of the particular characters and molecular markers chosen. Subtle differences can place accessions in distinct clusters. It is not a mistake of the experimental method, rather it is a consequence of a radiating evolution. Fig. 3.1 shows the geographical distribution of Lens species.

Defining biological species Crosses among species and subspecies help to clarify the systematics of the genus by establishing biological barriers to the access to a common gene pool. Ladizinsky (1979) made crosses between culinaris (three accessions representing extreme values for some characteristics as, for example, the seed), orientalis (four) and nigricans (one). The F1 generation of the culinaris × orientalis crosses grew normally in which the F2 generation segregated for growth habit, flower colour, pod dehiscence and seedcoat colour. Meiosis was almost normal with the presence of a quadrivalent in most of the cells examined and, in very few cases, a trivalent and one univalent. This result supported previous proposals considering orientalis as a subspecies of culinaris. The similarity between them, and even the possible relationship of common descent, was first pointed out by Barulina (1930) and later by Zohary (1972).

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O D T L E N

L. culinaris ssp. orientalis L. odemensis L. tormentosus L. lamottei L. ervoides L. nigricans 0 250 500

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Fig. 3.1. Geographical distribution of Lens species.

1000 km

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According to Ladizinsky (1979), culinaris and orientalis share the same karyotype, comprising two pairs of metacentrics (one of them with a secondary constriction), two pairs of large submetacentrics and three acrocentrics. Lens nigricans has a slightly different karyotype: four pairs of metacentrics (one of them with a secondary constriction too) and three of acrocentrics. However, other authors have found different karyotypes than those described by Ladizinsky. Thus, Balyan et al. (2002) describe the karyotype of nigricans as constituted by one pair of metacentric, three of submetacentric and two acrocentric chromosomes. Different strains of culinaris microsperma differ in the number of metacentrics, submetacentrics and acrocentrics, and orientalis strains in the position of the NOR locus (proximal or distal to the centromere) and the number of 5S loci (one or two) (Fernández et al., 2005). Likewise, Galasso (2003) described intraspecific karyotype variations in several Lens species. These results indicate that karyotypic variation within Lens can be higher than expected and this is important for the following section. The first hybrids between culinaris and nigricans also developed normally. However, later on (Ladizinsky et al., 1984), crosses with other accessions of nigricans were unviable. Therefore, in 1984, the former nigricans accession was reclassified as L. odemensis and the members of the genus Lens were grouped in two biological species, as mentioned above (Ladizinsky et al., 1984). The two subspecies of L. culinaris are easily crossed with each other (Ladizinsky, 1979; Fratini et al., 2004), although fertility of their intersubspecific hybrids depends on the chromosome arrangement of the wild parent (Ladizinsky, 1979; Ladizinsky et al., 1984). Three crossability groups have been identified in the wild ssp. orientalis: a common, a unique, and an intermediate. Crosses between members of the common and unique groups yield aborted seeds which can be rescued by embryo culture; members of the intermediate group are cross-compatible with the other two groups (Ladizinsky, 1993; van Oss et al., 1997). Subspecies orientalis is readily crossed with L. odemensis, the hybrids are vegetatively normal but partially sterile due to meiotic irregularities resulting from three chromosome rearrangements between the parental strains (Ladizinsky, 1993). Lens tomentosus is morphologically closer to L. c. ssp. orientalis than to any other Lens taxon, nevertheless, they are isolated one from another by hybrid embryo breakdown, complete sterility and five chromosomal rearrangements (van Oss et al., 1997), which supports the idea of a specific status for tomentosus. Likewise, L. tomentosus is reproductively isolated from L. lamottei and L. odemensis by hybrid-embryo abortion (van Oss et al., 1997). Linkage studies have revealed chromosomal rearrangements between L. culinaris and L. odemensis (Ladizinsky, 1993), which could possibly explain why certain accessions of odemensis are freely crossed with culinaris (Ladizinsky, 1979) and others need embryo rescue (Fratini and Ruiz, 2006). Lens odemensis is cross incompatible with nigricans and ervoides due to hybridembryo abortion (Ladizinsky et al., 1984; Ladizinsky, 1993).

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The morphological differences between L. nigricans and L. lamottei are limited to stipule shape; however, the two species differ by four reciprocal translocations and one paracentric inversion, resulting in the complete sterility of their hybrids (Ladizinsky et al., 1984). Lens nigricans × L. ervoides interspecific hybrids are vegetatively normal but completely sterile (Ladizinsky, 1993). Fratini and Ruiz (2006) made extensive crosses between L. c. ssp. culinaris and L. nigricans, L. ervoides and L. odemensis. Hybrids between the cultigens and the other species were viable only through embryo rescue; the rates of adult plants obtained were low: 9% with odemensis and 3% with nigricans and ervoides. Previously, it had been already shown that crosses between culinaris and nigricans or ervoides needed embryo rescue to recover interspecific hybrids (Ladizinsky et al., 1984; Ladizinsky, 1993). Therefore, in view of the above, it seems that odemensis belongs to the secondary gene pool and nigricans and ervoides can be classified in the tertiary gene pool (Ladizinsky, 1993).

A summary about the phylogeny of the genus Hybridization barriers support the idea of six differentiated species. Lens c. orientalis obviously belongs to the primary gene pool, L. odemensis rather to the second. However, the success in such crosses (needing embryo rescue or not) depends on the particular accessions used in the study. Lens nigricans and L. ervoides belong to the tertiary gene pool, but can become part of the secondary gene pool by means of embryo rescue. Further hybridization studies are needed to establish whether L. tomentosus and L. lamottei belong to the secondary or tertiary gene pool.

3.4. Taxonomy of the Cultivated Lentil Alefeld cited in Cubero (1981) recognized eight subspecies including both orientalis and nigricans (he used L. esculenta Moench.): (i) schniffspahni (syn. orientalis); (ii) himalayensis (syn. nigricans); (iii) punctata (syn. culinaris); (iv) hypochloris; (v) nigra (syn. culinaris); (vi) vulgaris; (vii) nummularia; and (viii) abyssinica. His subspecific names were later used by Barulina to name her varieties. Between Alefeld and Barulina there were no detailed studies, floras giving only simple varietal names (e.g. var. pilosisima Schur., var. microsperma Baumg. and var. macrosperma Baumg.). Barulina raised the two last names to the subspecific status, although molecular evidences indicate that they are varieties within the subspecies L. c. culinaris. Thus, for instance, macrosperma and microsperma accessions from Spain are more similar than microspermas from different European countries (Durán and Pérez de la Vega, 2004). The most detailed and complete study of the cultivated lentil was made by Barulina (1930), a disciple and latterly wife of N.I. Vavilov.

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She considered two subspecies, according to the size of the seed, the main objective of human selection. Barulina also considered the geographical distribution of clustered characters, defining regional groups or greges. The main characters in her study to define subspecies were pods, seeds and distinct differences in the length of flowers. Secondary characters included size of leaflets, length of vegetation and height of plants. Important characters with which to define the groups within the subspecies included dehiscence, length of calyx teeth, and number of flowers per peduncle. Varietal identification was realized choosing convenient, non-geographical and sometimes utilitarian characters. Barulina’s description of macrosperma and microsperma is as follows. (A) Lens culinaris ssp. macrosperma (Baumg. pro var.) Barulina. Large pods (15–20 × 7.5–10.5 mm), generally flat. Large flattened seeds (Ø 6–8 mm). Cotyledons yellow or orange. Flowers large (7–8 mm long), white with veins, rarely light blue. Peduncles with two to three flowers. Calyx teeth long. Large leaflets (15–27 × 4–10 mm), oval (length:width ratio = 3–3.5). Plant height from 25–75 cm. No geographical groups. 12 varieties. (B) ssp. microsperma (Baumg. pro var) Barulina. Pods small or medium (6–15 × 3.5–7 mm), convex. Seed flattened-subglobose (diameter:thickness ratio = 1.5–3), small or medium (Ø 3–6 mm), diverse in colour and pattern. Flowers small (5–7 mm long) from white to violet. Peduncles bearing one to four flowers. Leaflets small (8–15 × 2–5 mm), elongated, linear or lanceolate (length:width ratio = 4–5). Height of plants 15–35 cm. 46 varieties grouped in six greges: europeae, asiaticae, intermediae, subspontanea, aethiopicae and pilosae (see Cubero, 1981 for details).

The geographical distribution of subspecies and greges can be seen in Fig. 3.2, drawn according to Barulina’s own map.

3.5. The Centre of Origin The three main problems regarding the biological nature of any crop are: (i) where and when the biological species originated; (ii) where and when that species became a crop; and (iii) how it has evolved as a crop. Archaeological data were given by Cubero (1981) and this is summarized in Fig. 3.3. The oldest remains were found in Hacilar (Turkey), Ramad (Syria), Jarmo (Iraq), Jericho (Palestine), Beidha (Jordan) and Ali Kosh (Iran) dated around 9000 bp, in aceramic Neolithic layers. Even older remains were found in Mureybit (Syria), c.10,500 bp, but they were wild lentils. The oldest Greek lentils were dated around 8000 bp, then Central Europe (5000–7000 bp, from classical Neolithic to early Bronze; in both regions there are some doubtful nigricans seeds). Late arrivals were those of India (3000–4000 bp) and Western Europe (France, Germany: 3000–3500 bp). Egypt also shows a later arrival (c.5000 bp) than in Greece and Central Europe but conditions in the Nile Delta are not favourable for preserving agricultural remains.

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macrosperma europeae asiaticae intermediae microsperma subspontanea aethiopicae pilosae 0 250 500

Distribution of L. culinaris ‘greges’ according to Barulina.

J.I. Cubero et al.

Fig. 3.2.

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Origin, Phylogeny, Domestication and Spread

BP

–9500 9500–8000 8000–6500 6500– 0

250

500 km

Fig. 3.3. Archaeological data. Lines indicate, respectively, the main distribution area of the orientalis and the proposed domestication area within it.

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Concerning the place of origin of lentils as a crop, according to the archaeological data, the distribution of wild species and the existence of the remains of both wild and cultivated lentils in the same region, the Near East is the obvious candidate. Ladizinsky (1999) found the cultivated lentil to be monomorphic for several characters, but considerable polymorphism was found to exist in the wild accessions of ssp. orientalis. However, three accessions from eastern Turkey and northern Syria were shown to share the above characters with the cultigen and therefore can be regarded to be members of the genetic stock from which the cultivated lentil was domesticated. Zohary (1999) comes to the conclusion that lentil was domesticated once or only a few times, this conclusion being based on founder effects revealed by chromosome and DNA polymorphisms, as well as evidence from domestication traits and species diversity. Lev-Yadun et al. (2000) suggested a place close to or overlapping the area where einkorn and emmer wheats were domesticated in the Fertile Crescent (Fig. 3.3). Barulina (1930), instead, suggested the eastern border of south-west Asia as a possible centre of origin of the cultivated lentil, as the region between Afghanistan, India and Turkistan (i.e. the Himalaya–Hindu Kush junction) showed the highest proportion of endemic varieties, a pure Vavilovian criterion to define centres of origin. She noticed that the area of distribution of wild lentils did not overlap much with that of the domesticated ones, but she maintained her idea considering that the eastern part of the orientalis area of distribution reaches Turkmenia. Today, the abundance in endemic forms of the cultigen as the most important criterion to locate a centre of origin is taken as a secondary argument (Ethiopia is also rich in endemism and it is not a candidate for centre of origin). De Candolle’s ideas were taken up again some time ago (Harlan, 1992). Thus, the overlap between the wild ancestor and the cultigen and the archaeological remains connecting both are sine qua non conditions to establish such a centre of origin. Figures 3.1 and 3.2 show the distribution of wild and cultivated lentils (Barulina’s greges of L. culinaris are used for that purpose). Three groups are restricted to very concrete areas: pilosae to the Indian subcontinent, aethiopicae to Ethiopia and Yemen, and subspontanea to the Afghan regions closest to the Indian subcontinent. All three have very small and dark-coloured seeds, violet flowers, few flowers per peduncle, calyx teeth much shorter than the corolla, few leaflets per leaf, and dwarf plants. On this common background, each one of these three greges shows a distinct character: pilosae – a strong pubescence; subspontanea – very dehiscent pods, being purple coloured before maturity; and aethiopicae – pods with a characteristic elongated apex. These particular characteristics are shown together with a cluster of primitive characteristics closely related to orientalis. The other three microsperma groups (europeae, asiaticae and intermediae) and macrosperma are rather cosmopolitan and are clearly intermixed, even when intermediae has a rather restricted area. Seeds are variable in size, but in general, they are wider than 4 mm. They have more flowers per peduncle, more leaflets per leaf, and the calyx teeth are equal to or larger

Origin, Phylogeny, Domestication and Spread

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than the corolla. White flowers are common, seeds being diverse in colour. Figures 3.1 and 3.2 suggest that subspontanea overlaps only with orientalis, and aethiopicae with ervoides; pilosae does not overlap with any wild lentil. All other microsperma as well as macrosperma lentils overlap to a greater or lesser extent with all the known wild lentils. On the other hand, no lentils have been found in the sites dating back to the seventh millennium bp in Turkmenia. The high degree of endemism that exists in the Afghanistan– Indian–Turkmenian area is better explained, as in all other species, by an intense genetic drift, typical of highly diversified environments, coupled with artificial selection carried out by very diverse human populations, with drastic genetic fixation and losses providing secondary centres of diversity. To sum up, the area from western Turkey to northern Iraq contains not only all the wild lentils but also ‘lentoid’ characters such as flattened pods and seeds present in other species like V. montbretii (a bridge between Vicia and Lens?) and V. lunata. The known data point to the southern Turkey– northern Syria region as the most likely place of lentil domestication. Some populations of orientalis were unconsciously subjected to automatic selection here, leading to a new crop, Lens culinaris.

3.6. The Spreading of Lentil Culture Figure 3.3 shows that lentils follow the spreading of the Neolithic agricultural techniques (Harlan, 1992), being first cultivated in the Fertile Crescent, then moving to Greece, Central and Western Europe along the Danube, to the Nile Delta, and eastwards to India. From Greece, lentils found their way to Central Europe through the Danube. There are lentil archaeological remains in the Iberian Peninsula since the early Neolithic, the oldest ones corresponding to the eastern part of the Peninsula. In particular in the cave ‘de les Cendres’, there are remains of several crops (Triticum monococcum, Triticum dicoccum, Triticum aestivum, barley, pea, grass pea, lentil and faba bean, i.e. a typical Near East crop complex) dated by 14C to 7540 ± 140 bp. According to the seed size, the archaeological lentil findings in the Iberian Peninsula fall within the range of the microsperma sizes (Buxó, 1997). Intermediae forms reached Sicily, and asiaticae forms reached Sardinia, Morocco and Spain (Fig. 3.2), suggesting the arrival in these countries of lentil stocks from Central Europe, or from the route of the isles. The lentils probably reached the cradle of Indoeuropean people after the Greek ancestors split, as suggested by De Candolle (1882) on linguistic grounds: Greek for lentil is phakos, but lens in Latin, lechja in Illyrian, and lenzsic in Lithuanian. It is likely that the ancient Greeks took the word from the aboriginal Mediterranean populations they conquered. Figure 3.2 shows that central Russia, then Siberia, was more likely reached from the western coast of the Black Sea or from the Danube valley rather than from Mesopotamia or Central Asia.

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The arrival of lentils to the Nile Delta had to be much earlier than the archaeological remains suggest due to its proximity, both geographical and cultural, to the Fertile Crescent; but the Delta environment is not helpful in preserving organic materials. Ethiopia was probably reached from the Arabian coast (at that time it was the Arabia Felix, more humid and fertile than nowadays) rather than by the Nile. Lentils likely travelled in the Near East complex (along with barley, wheat, chickpea, faba bean, etc.), established in the Ethiopian highlands since primitive times, and have been evolving since then in isolation, producing much endemism that allowed Vavilov to place the centres of origin of crop plants that only arrived there by farming. Indeed, aethiopicae exhibits very primitive characters, meaning that lentils probably also arrived at a very primitive stage of domestication. Lentils did not reach India before 4000 bp, probably carried by the Indoeuropean invasion (De Candolle, 1882) through Afghanistan, but again there is the problem of availability of archaeological findings. Primeval introduction was probably performed by very small samples of a common origin as the variability found in the Indian subcontinent in the local landraces is very limited, in spite of being the largest lentil-growing region in the world; the asynchrony in flowering of the local pilosae ecotype, probably a consequence of a long reproductive isolation period, is now being broken by plant breeding methods in order to widen the genetic base available (Erskine et al., 1998). The diversity in the centre of origin seems to be well maintained. By using molecular markers, Ferguson et al. (1998) located areas of high diversity for the wild relatives: L. culinaris ssp. orientalis (south-west Turkey, north-west and south Syria, and in Jordan), L. odemensis (south Syria), L. ervoides (coastal border region between Syria and Turkey) and L. nigricans (west Turkey).

3.7. Evolution of the Cultivated Forms Lens orientalis is the wild form out of which the cultigen developed. Lens culinaris forms show, in general, greater height, longer rachis and greater number of leaflets per leaf, greater leaflet area, greater number of flowers per peduncle, peduncle shorter or equal to the rachis, higher frequency of white flowers, and also larger pods and seeds. All these characters are related to the increase in yield. Seed size is the only character that can indicate domestication in archaeological remains. It was mentioned above that there are cultivated groups with some primitive characters; up to the Middle Ages there were ‘blackish’ and ‘not sweet’ varieties, as well as others with ‘normal’ and ‘rounder’ seeds. Obviously, they could be impurities coming from mixtures with some vetches (for example, Vicia angustifolia or Vicia platysperma), as subsistence farmers did not worry very much about botanical purity. But these forms could also be mixtures with wild Lens species or any real primitive landrace. Figure 3.2 shows a clear regional varietal facies according to Barulina’s study, performed when modern agriculture had not reached these regions.

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Western lentils have the main characters of big seeds, a high number of large leaflets, and calyx teeth longer than the corolla. A great discussion is raised on the origin of some characteristics of the cultigen. Lens odemensis could have provided the genetic raw material for bigger seeds and all the correlated characters. Crosses between culinaris and odemensis (then classified as nigricans; Ladizinsky et al., 1984) resulted in a greater development of tendrils while culinaris shows, although rarely, branched tendrils. Calyx teeth are also larger in the western lentils, a character that can be correlated with leaflet area; calyx teeth are shorter than corolla in orientalis but as long as the corolla in odemensis. The opposite is true for the eastern lentils, orientalis playing the leading role in crop evolution. The original stock of pilosae (Indian endemism) could have been originated in south Turkey–north Syria, where hairy orientalis and culinaris forms are found. The short calyx of aethiopicae forms could have an ervoides origin. The origin of such facies can be attributed to the classical sources of variation in crop evolution: mutation, migration, selection, genetic drift and crosses with companion weeds (wild lentils). Figure 3.1 shows that orientalis is the only one spreading eastwards, ervoides to the south (Ethiopia), and both nigricans and ervoides to the west. Some L. odemensis accessions can be readily crossed with the cultigen (Ladizinsky et al., 1984). Lens nigricans and L. ervoides should be excluded because crosses with the cultigen result in hybrid embryo abortion (Ladizinsky et al., 1984; Fratini and Ruiz, 2006), but it cannot be ruled out that these crosses eventually (even if sporadically) succeed in natural environments, nor that all strains of nigricans and ervoides behave in a similar way. Thus, if the distribution of wild lentils was the same as that at the Barulina’s time, the regional facies can be explained. To sum up, lentils were domesticated, in the Near East or, more accurately, in the foothills of the mountains of southern Turkey and northern Syria. The raw materials were populations of orientalis, but primitive farmers could also have used some other species of the genus, whose similarity has been shown in the present chapter, in mixed populations rather than in pure strands. But orientalis and odemensis forms are the most likely candidates to have been companion weeds of the cultigen. However, molecular marker analyses have indicated that the genetic variability within cultivated lentils is relatively low (Sonnante et al., 2003; Durán and Pérez de la Vega, 2004), which supports the idea that microsperma and macrosperma morphotypes are simple variants for quantitative traits resulting from disruptive selection (Sonnante et al., 2003). It is difficult to establish how much the wild relatives have contributed to the cultigen gene pool.

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J.I. Cubero et al. Balyan, H.S., Houben, A. and Ahne, R. (2002) Karyotype analysis and physical mapping of 18S-5.8S-25S and 5S riboosmal RNA loci in species of genus Lens Miller (Fabaceae). Caryologia 55, 121–128. Barulina, H. (1930) Lentils of the USSR and other countries. Bulletin of Applied Botany, Genetics and Plant Breeding 40, 265–304. (in Russian with English summary) Bueno, M.A. (1976) Taxonomía y Cariología en el Género Vicia. Doctoral thesis, Universidad Complutense, Madrid, Spain. Buxó, R. (1997) Arqueología de las Plantas. Crítica (ed.), Barcelona, Spain. Cubero, J.I. (1981) Origin, domestication and evolution. In: Webb, C. and Hawtin, G.C. (eds) Lentils. Commonwealth Agricultural Bureau, Slough, UK, pp. 15–38. De Candolle, A.P. (1882; reprinted 1967) Origins of Cultivated Species. Hafner, London, UK. Durán, Y. and Pérez de la Vega, M. (2004) Assessment of genetic variation and species relationships in a collection of Lens using RAPD and ISSR. Spanish Journal of Agricultural Research 4, 538–544. Erskine, W., Smartt, J. and Muehlbauer, F.J. (1994) Mimicry of lentil and the domestication of common vetch and grass pea. Economic Botany 48, 326–332. Erskine, W., Chandra, S., Chaudary, M., Malik, I.A., Sarker, A., Sharma, B., Tufail, M. and Tyagi, M.C. (1998) A bottleneck in lentil: widening the genetic base in South Asia. Euphytica 101, 207–211. Ferguson, M.E., Ford-Lloyd, B.V., Robertson, L.D., Maxted, N. and Newbury, H.J. (1998) Mapping of geographical distribution of genetic variation in the genus Lens for enhanced conservation of plant genetic resources. Molecular Ecology 7, 1743–1755. Ferguson, M.E., Maxted, N., Van Slageren, M. and Robertson, L.D. (2000) A reassessment of the taxonomy of Lens Miller (Leguminosae, Papilionoideae, Vicieae). Botanical Journal of the Linnean Society 133, 41–59. Fernández, M., Ruiz, M.L., Linares, C., Fominaya, A. and Pérez de la Vega, M. (2005) The 5S rDNA genome regions of Lens species. Genome 48, 937–942. Fratini, R. and Ruiz, M.L. (2006) Interspecific hybridization in the genus Lens applying in vitro embryo rescue. Euphytica 150, 271–280. Fratini, R., Ruiz, M.L. and Pérez de la Vega, M. (2004) Intra-specific and inter-subspecific crossing in lentil (Lens culinaris Medik.) Canadian Journal of Plant Science 84, 981–986. Fratini, R., García, P. and Ruiz, M.L. (2006) Pollen and pistil morphology, in vitro pollen grain germination and crossing success of Lens cultivars and species. Plant Breeding 125, 501–505. Galasso, I. (2003) Distribution of highly repeated DNA sequences in species of the genus Lens Miller. Genome 46, 1118–1124. Godron, D.A. (1843) Flora Lorraine. Vol. 1. Grimblot, Raybois et Cie, Nancy, France. Gunn, C.R. (1969) Genera, types and lectotypes in the tribe Vicieae (Fabaceae). Taxon 18, 725–733. Harlan, J. (1992) Crops and Man. American Society of Agronomy, Madison, Wisconsin, USA. Harlan, J.R. and De Wet, J.M.J. (1971) Towards a rational classification of cultivated plants. Taxon 20, 509–517. Kupicha, F.K. (1977) The delimitation of the tribe Vicieae (Leguminosae) and the relationships of Cicer L. Botanical Journal of the Linnean Society 74, 131–162. Ladizinsky, G. (1979) The origin of lentil and its wild gene pool. Euphytica 28, 179–187. Ladizinsky, G. (1993) Wild lentils. Critical Reviews in Plant Science 12, 169–184.

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Ladizinsky, G. (1997) A new species of Lens from south-east Turkey. Botanical Journal of the Linnean Society 123, 257–260. Ladizinsky, G. (1999) Identification of the lentil wild genetic stock. Genetic Resources and Crop Evolution 46, 115–118. Ladizinsky, G. and Sakar, D. (1982) Morphological and cytochemical characterization of Vicia montbretii Fisch. & Mey (Synonym: Lens montbretii (Fisch. & Mey) Davis & Plitmann). Botanical Journal of the Linnean Society 85, 209–212. Ladizinsky, G., Braun, D., Goshen, D. and Muehlbauer, F.J. (1984) The biological species of the genus Lens. Botanical Gazette 145, 253–261. Lev-Yadun, S., Gopher, A. and Abbo, S. (2000) The cradle of agriculture. Science 288, 1602–1603. Mayer, M.S. and Bagga, S.K. (2002) The phylogeny of Lens (Leguminosae): new insight from ITS sequence analysis. Plant Systematics and Evolution 232, 145–154. Miller, P. (1741) The Gardener’s Dictionary, 2nd edn. Printed for the author, London, UK. Sonnante, G., Galasso, I. and Pignone, D. (2003) ITS sequence analysis and phylogenetic inference in the genus Lens Mill. Annals of Botany 91, 49–54. van Oss, H., Aron, Y. and Ladizinsky, G. (1997) Chloroplast DNA variation and evolution in the genus Lens Mill. Theoretical and Applied Genetics 94, 452–457. Vavilov, N.I. (1949/50) The Origin, Variation, Immunity and Breeding of Cultivated Plants. Selected Writings of N.I. Vavilov. Translated by K. Starr Chester. Chronica Botanica Vol. 13. The Chronica Botanica Co., Waltham, Massachusetts, USA. Zimniak-Przybylska, Z., Przybylska, J. and Krajewski, P. (2001) Genetic resources, Lens, lentil, SDS-PAGE, seed globulins. Journal of Applied Genetics 42, 435–447. Zohary, D. (1972) The wild progenitor and the place of origin of the cultivated lentil Lens culinaris. Economic Botany 26, 326–332. Zohary, D. (1999) Monophyletic vs. polyphyletic origin of crops on which agriculture founded in the Near East. Genetic Resources and Crop Evolution 46, 133–142.

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Plant Morphology, Anatomy and Growth Habit Mohan C. Saxena*

International Center for Agriculture Research in the Dry Areas (ICARDA), Aleppo, Syria *Present address: A-22/7 DLF City, Gurgaon, Haryana, India

4.1. Introduction The lentil is a slender, softly pubescent, light green, annual herbaceous plant (Fig. 4.1), generally between 20 and 30 cm tall, although there are cultivars as short as 15 cm and as tall as 75 cm (Duke, 1981; Muehlbauer et al., 1985). The plant is indeterminate and it exhibits considerable variation in its growth habit, with single stem and erect to semi-erect and compact growth to much branched low bushy forms, mainly depending on genotype although environmental conditions affect the expression of these characters (Saxena and Hawtin, 1981). Under optimum environmental conditions, as obtained in late-winter and early-spring season sowings in the Mediterranean region of West Asia and North Africa (WANA), lentil plants make fast vegetative and reproductive growth and reach maturity in 75–100 days after sowing. In this respect, lentil, of all cool-season food legume crops, compares well with barley (Hordeum vulgare), which is the fastest growing winter cereal and well adapted to dry rain-fed conditions in the WANA region. However, in most lentilproducing countries, plant growth of the winter-sown crop is rather slow in the early vegetative phase because of suboptimum ambient temperatures and it gains momentum only in spring when temperatures rise. As a result, the winter-sown crop takes 120–160 days to reach maturity (Saxena and Hawtin, 1981), extending to 180 days in some environments of West Asia. Moisture supply during the reproductive phase of crop growth much affects the complete realization of the growth and yield potential of lentil genotypes. The lentil plant exhibits a wide range of morphological variations in both its vegetative and its reproductive organs. That is why a major early attempt to classify cultivated lentils into subspecies by Barulina (1930) was mainly based on the characteristic morphological features of pods and 34

© CAB International 2009. The Lentil: Botany, Production and Uses (eds W. Erskine et al.)

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Fig. 4.1. Lentil plant structure: (a) dry seed; (b) moisture-imbibed seed; (c) a newly emerged seedling showing hypogeal germination; (d) a young seedling showing two bifoliate leaves; (e) branch with leaves, ﬂowers and pods of microsperma lentil.

seeds, length of flower, size of leaflets, and plant height. Lentil cultivars were grouped in two intergrading clusters of seed sizes: (i) small-seeded lentils (microsperma) with relatively small and swollen pods (6–15 × 3.5–7.0 mm) and small seeds (3–6 mm diameter); and (ii) large-seeded lentils (macrosperma) with relatively large flattened pods (15–20 × 7.5–10.5 mm) and large seeds ranging in diameter between 6 and 9 mm (Fig. 4.2). It appears that with domestication there was not only the development of pod indehiscence but also a gradual increase in seed size as testified by the fact that macrosperma forms appear more recently in archaeological sequence – only in the first millennium bc (Zohary and Hopf, 2000). However these two groups are freely intercrossable and a complete range of seed sizes, from microsperma to macrosperma types, is present in the cultivated species (Muelbauer et al., 1985). During the last decades, through broadening of the genetic base, these two groups of lentils have become indistinguishable, and the grouping is no longer much used by lentil workers.

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Fig. 4.2. Variation in pods and seeds of lentil. Top row, macrosperma type lentil: (a and b) pods; (c) side view and (d) front view of seed. Bottom row, microsperma type lentil: (e and f) pods; (g) side view and (h) front view of seed.

4.2. Root System The lentil plant has a slender taproot system with a mass of fibrous lateral roots. Large genotypic variation has been reported in root growth in terms of taproot length, number of lateral roots, total root length, root weight (Sarker et al., 2005) and number of hairs per unit root surface area (Gahoonia et al., 2005). Genotypic differences have also been observed in the rate of root growth (Gahoonia et al., 2005; Sarker et al., 2005). Because of the importance of root traits in the capture of moisture and inorganic nutrients from soil, particularly on low fertility and water-holding-capacity soils, positive association has been observed between rate and amount of root surface development and the crop yield (Gahoonia et al., 2005; Sarker et al., 2005). Sarker et al. (2005) attributed the drought tolerance of breeding line ILL 6002, derived from a cross between Canadian cultivar ‘Liard’ (ILL 4349) and Argentinean cultivar ‘Precoz’ (ILL 4605), mainly to its root characteristics of fast growth and large number of lateral roots. Interesting variations in pattern of root growth in different ecotypes of lentils adapted to different types of soils in major lentil production areas in the Indian subcontinent have been reported by Nezamuddin (1970). The patterns recognized on the basis of depth and lateral proliferation were: (i) a much-branched, shallow root system going down only to a depth of about 15 cm; (ii) a slender deep taproot going down to 36 cm depth; and (iii) an intermediate form (Fig. 4.3). The shallow, profusely branched roots were found on light alluvial soils with the small-seeded lentil ecotypes with highly branched shoots. The deep root system was found in the ecotypes

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grown on heavy black cotton soils in central India that tend to develop large cracks on the surface and thus rapidly lose moisture from the top soil layer. These ecotypes have sparsely branched shoots and relatively large seed although they belong to microsperma type. The intermediate root system types are grown in the Punjab and the North-West Frontier Province of Pakistan. The taproot and the laterals in the upper soil layer carry numerous small round or elongated nodules (Fig. 4.4) when the plant grows on a medium that contains appropriate strains of Rhizobium. Most nodules however become oblong because of the presence of an apical meristem, and several, particularly those on the taproot, become multi-lobed as a result of bifurcation of the apical meristem. The nodules may start appearing as early as 15 days after emergence, but the peak growth in their number and mass occurs when the plant reaches peak vegetative growth, and it starts declining with the onset of flowering, although this could be delayed to some extent if the soil moisture supply at that time would improve by rain or irrigation (Saxena and Hawtin, 1981). Healthy nodules have a pinkish white appearance and when cut show pink discoloration of leghaemoglobin. The nodules provide good medium for the growth of larvae of Sitona weevil and can therefore be seen bored and eaten by them in fields infested by Sitona, the insect mainly prevailing in the WANA region (see Ujagir and Byrne, Chapter 18, this volume). The affected plants show severe nitrogen deficiency mainly because of curtailed nitrogen fixation.

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Fig. 4.4. Taproot and laterals showing elongated nodules.

4.3. Stems and Plant Structure The lentil stems are thin, square and ribbed at the angles and generally herbaceous and weak; particularly at the early vegetative stage, but in several genotypes they get stronger with advancement in age. The basal part of the stem becomes woody and lignified as plant growth advances. The degree of pubescence varies with genotypes, from almost glabrous to very hairy, and hairs are rather fine and soft. The stems are generally light green in colour but in several genotypes they may have varying degrees of anthocyanin pigmentation – ranging from only on the basal parts to the whole of the stems, while in others it could be completely absent. Depending on genotype and the growth environment, the plant height may range from 15 to 75 cm. A study by Malhotra et al. (1974), with 47 diverse lentil genotypes grown on sandy loam soil in northern India in a spacing of 50 cm × 10 cm, showed that the plant height ranged from 17 to 55 cm. Tullu et al. (2001), in their 2-year study with a core collection of lentil germplasm comprising 287 accessions from diverse geographical regions (Asia, Africa, North America, South America and Europe) and 15 registered cultivars, grown under tilled and no-till production systems in Washington, USA, confirmed that plant height at maturity was not only affected by genotypes but also by the environment. The height varied at the no-till site from 15 to 40 cm in 1996 and from 20 to 63 cm in 1997, while the respective ranges for the conventional tillage site were 19–43 cm and 20–60 cm. The average

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was 27 cm in 1996 and 37 cm in 1997. This difference was attributed to better rainfall distribution in 1997 than in 1996. The plant canopy width also showed large genotypic variation, and, as an average of four environments, it ranged from 8 to 18 cm at flowering and from 12 to 32 cm at maturity. Plant height and canopy width were highly correlated with total biomass and seed yield. As plant height is highly influenced by environment, assigning an absolute value for the height of a specific cultivar may be of limited value. The course of growth in plant height is also highly influenced by environment (Saxena and Hawtin, 1981). The internodal length is rather small in the lower part of the stem and it becomes progressively bigger in the upper part up to 75% of the height, and then decreases again. Most of the nodes are formed by the time of peak flowering. The dry weight accumulation in the stem follows a sigmoid course and the rate of accumulation is highly influenced by both genotype and environment. Studies at the International Center for Agriculture Research in the Dry Areas (ICARDA), Syria, in a Mediterranean environment, showed that when lentil was sown in winter the rate of dry matter accumulation in the stem was very slow in the first 90–100 days and then it increased sharply with age. In the case of the springsown crop the early slow growth phase was rather short. Improvement in moisture supply increased dry matter accumulation, late in the season, particularly in the spring-sown crop. Almost 50% of stem dry matter was accumulated after the peak in flowering, indicating that the stem continued to be an active sink for photosynthates and perhaps other plant nutrients even during reproductive growth (Saxena and Hawtin, 1981). There is thus scope for exploiting genotypic differences in remobilizing the nutrients from stem to seed formation for improving the harvest index in lentil. Lentil genotypes show large differences in their branching pattern, although the expression of this trait is also greatly influenced by environment. Nezamuddin (1970) described the branching pattern in lentil genotypes grown in India. The pattern ranges from erect compact, with a narrow branch angle, to prostrate or spreading where the branch angle is rather wide and the lower branches remain lying close to the ground. Several intermediate types are also found. The plant may have only a few or many primary branches that arise directly from the main stem, and often many secondary branches arising from primary branches. In some cases there could be even tertiary branches. Malhotra et al. (1974) reported a range of 1.5–11.1 primary branches per plant in their study of 47 lines evaluated under spaced planting. The production of branches is highly affected by plant population, the number decreasing with increasing plant density (Wilson and Teare, 1972). A schematic depiction of different branching patterns and plant structure, observed in the lentil germplasm evaluated at Tel Hadya, Syria, is shown in Fig. 4.5 (Saxena and Hawtin, 1981). A highly branched bushy pattern was typified by the accession no. 43633; a sparsely branched, tall erect type by cultivar ‘Laird’ (ILL 4349); a moderately branched, semi-tall erect plant structure by the Egyptian cultivar ‘Giza 9’ and the Argentinean cultivar

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Fig. 4.5. Schematic depiction of variation in branching pattern and plant structure in lentil: (a) highly branched bushy; (b) sparsely branched, tall erect; (c) moderately branched, semi-tall erect; (d) moderate to highly branched, semi-tall, subcompact; (e) moderate to highly branched, short, subcompact.

‘Precoz’ (ILL 4605); a moderate to highly branched, semi-tall, subcompact pattern by Syrian landrace ‘Local Large’ (ILL 4400); and a moderate to highly branched, short, subcompact pattern by Syrian landrace ‘Local Small’ (ILL 4401). A ratio of plant height to canopy width is a good measure of plant structure and it has been used to characterize growth habit in lentil germplasm evaluation (Ferguson and Robertson, 1999).

4.4. Leaves Lentil leaves are alternate, compound and pinnate with one to eight pairs of subsessile or sessile, ovate, elliptical or lanceolate leaflets. Each leaf is subtended by a small pair of stipules. The rachis is 4–5 cm in length and it may terminate in a bristle or simple (sometimes dichotomous) tendril having a length that may be similar to that of the rachis, particularly in the upper leaves (Fig. 4.1). Some genotypes develop tendrils at a fairly early stage of growth, while most tend to develop the tendrils only on leaves that unroll just before flowering. At maturity the tendrillous habit keeps the canopy upright, helping in machine harvest. Some other genotypes remain tendrilless. The colour of the leaves can be yellowish green, light yellow green, dull green, dark green or dark bluish green. Under low temperature conditions, the leaves may develop purplish discoloration, which disappears as the temperatures increase. Leaf chlorosis is also common under low temperature and high moisture conditions on calcareous soils in the Mediterranean

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region, but the leaves gain their normal green colour as the season advances, and temperature and moisture conditions become optimum. The leaf pubescence may be absent, slight, medium or dense. The leaflets of macrosperma types are relatively larger in size (15–27 mm in length, 4–10 mm in width) than those of microsperma type (8–15 mm long and 2–5 mm broad) and the former are generally oval (length:width ratio = 3–3.5) and rarely elongated while the latter are elongated, linear or lanceolate (length:width ratio = 4–5) (Barulina, 1930). Szucs (1972) studied the relationship between the leaflet width and seed diameter in 49 microsperma and 45 macrosperma types and reported high positive correlation. The number of leaflets varies among genotypes, and within a genotype with nodal position. The first two leaves are simple, scale like and largely fused with two scale-like stipules (Fig. 4.1d). The following two or more leaves are bifoliate and the subsequent ones are multifoliate. There are no stipels. There is a small pulvinus at the base of each leaflet which causes the leaflets to fold up together in the evening or during the day when the plant experiences moisture stress.

4.5. Flowers and Flowering The lentil plants are indeterminate and they come to flower after a period of vegetative growth, the length of which varies considerably between genotypes grown in a single location. The flowering is acropetal; hence lower nodes may bear pods close to maturity while younger nodes may carry flowers (Fig. 4.1e). The duration of flowering of a single plant and crop stands varies enormously; it may range from less than 10 days to longer than 40 days depending on the genotype and the environment. The flowers are borne on a single axillary raceme inflorescence, with a slender peduncle, 2–5.5 cm long (mostly 3–4 cm long), on a reproductive node. The rachis of the inflorescence ends in a filiform apex (Fig. 4.1e). There are no bracts. The number of peduncles per plant varies with genotype, but more so by environment. Malhotra et al. (1974) reported a range from 10 to 150 peduncles per plant in their evaluation of 47 lentil genotypes in India. Each peduncle bears from one to four flowers (sometimes as many as seven flowers have been found). The flowers are complete, have typical papilionaceous structure, and are small (4–9mm long). Their standard petal is white, pink, purple, light purplish blue, or pale blue (Muehlbauer et al., 1985). In some genotypes it is white with light purplish blue veins. The wings and keel are generally white, but wings may have a violet-blue tinge. The calyx tube divides near its base into five narrow pointed lobes that curve over and beyond the corolla. The stamens are diadelphous (nine plus one) with the upper vexillary stamen free. The ovary contains one or two ovules (sometimes three ovules) and it terminates in a short curved style. The style is pilose on the inner side and the stigma is slightly swollen and glandular. The flowers are cleistogamous and almost exclusively self-pollinated although some cross-pollination (less than 0.08%) may occur through thrips

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and other such insects but not by wind or honeybees (Muehlbauer et al., 2002). Petals expand at a rate equivalent to about one-quarter of the length of sepals every 24 hours and most flowers would have been pollinated by the time petal length exceeds three-quarters that of sepals. Thus, the timing of emasculation for artificial hybridization in a breeding programme is critical. The opening of all flowers on a single branch takes about 2 weeks to complete (Nezamuddin, 1970). Flowers open before 10.00 h on cloudless days but not until 17.00 h when the sky is overcast. At the end of the second day and on the third day all open flowers close completely and the colour of the corolla begins to fade. The visual appearance of the pod occurs after 3–4 days.

4.6. Pods Lentil pods are oblong, laterally compressed, bulging over the seeds, 6–20 mm long and 3.5–11.0 mm wide; rounded to slightly cuneate at the base, short beaked, smooth, with persistent calyx, and they contain one to three seeds. As mentioned earlier, the main distinguishing feature between macrosperma and microsperma types is the size and shape of the pods and seeds (Fig. 4.2). The unripe pods are usually green although in some genotypes the colour can be purple, violet or spotted. Their lateral expansion is complete before grain filling starts. To start with, the pods are flat and as the grain filling advances, they become somewhat swollen over the seeds. This is particularly conspicuous in the microsperma types in which the pod surface becomes convex while in the macrosperma types it remains generally flat (Fig. 4.2). As the crop reaches maturity, the colour of the pods changes and, depending on the genotype, the pod wall becomes straw-coloured, light beige, light brown, dull brown or spotted. The number of pods per peduncle normally varies from one to four although up to six have been found. Muehlbauer (1974) studied the genotypic difference in the number of pods per peduncle in 45 space-planted diverse lentil lines. The frequency of one pod to the peduncle was greatest, closely followed by that of two pods per peduncle, whereas the frequency of three pods per peduncle was very low. The number of pods per plant, which is a very important yield determinant in lentil, varies considerably depending on the genotype as well as the environment. In an evaluation of Indian lentil genotypes, planted with a spacing of 50 cm × 10 cm, Malhotra et al. (1974) observed a range from 17.2 pods to 216 pods per plant, whereas, Singh and Singh (1969) found more than 500 pods per plant in a crop planted with 60 cm × 30 cm spacing.

4.7. Seeds Lentil seeds are typically lens shaped (Fig. 4.2). Their diameter ranges from 2 to 9 mm (Barulina, 1930). The large-seeded types generally have a diameter

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range from 6 to 9 mm, medium size from 5 to 6 mm, and the small from 3 to 5 mm. They may have a globose shape (diameter:thickness ratio ranging from 1.5 to 2.5) or flattened (diameter:thickness ratio ranging from 2.5 to 4). The testa colour can be pink, yellow, green, dark green, grey, brown or black. In some genotypes the testa has dark brown or black spots, speckling or mottling (Muehlbauer et al., 2002). The seed surface is generally smooth but in some large-seeded types it may be wrinkled. The hilum is narrowly elliptical and minute, and its colour is white or dull brown. The cotyledon colour may be orange, yellow or green, the latter turning yellow after a period of storage (Kay, 1979; Duke, 1981; Muehlbauer et al., 1985). The number of seeds per plant is closely correlated with the number of pods per plant, and is, therefore, an important yield attribute. Muehlbauer (1974), in his evaluation of 45 diverse lines of lentil, observed a range from 17.6 to 139.6 pods per plant, with a mean of 62.6 pods per plant. The 100-seed weight may range from 1.07 to 8.55 g depending on genotype. The environmental effect on seed weight is generally not very conspicuous. The 100-seed weight in the range from 1.1 to 4 g is found in the small-seeded types, while the large-seeded types generally have a range from 4 to 8.2 g (Barulina, 1930). The evaluation of a core collection of 287 lentil germplasm accessions by Tullu et al. (2001) revealed that the variation ranged from 1.3 to 7.4 g/100 seeds, with an overall mean of 3.6 g. Also there was a highly significant variation for seed size between and within yellowand red-cotyledon types, a range from 1.7 to 7.4 g/100 seeds for yellowcotyledon-type accessions and from 1.3 to 5.2 g/100 seeds for red-cotyledon accessions. The country of origin was a major factor in determining the seed weight and seed colour in the tested accessions. The seeds show a 3–4 week period of dormancy after harvest and the duration varies with genotypes. Non-dormant seeds, when placed in moist soil at optimum temperature, rapidly imbibe moisture attaining complete imbibition in 12 h. Small-seeded lentils imbibe water which is 85% of their initial air-dry weight, while the large-seeded lentils imbibe more than 100% of their initial airdry weight. The germination is hypogeal (Fig. 4.1), and the emergence in the field occurs in 7–9 days in the spring-sown crop in the Mediterranean region as the ambient temperature is around 20°C, while the winter-sown crop may take 25–30 days to emerge because the temperatures are less than 10°C.

4.8. Anatomy Barulina (1930) has investigated the anatomical characteristics of roots, stem, leaf, fruit and seeds of lentil and provides illustrations and a short description of each of these parts. The transverse section of the taproot of lentil reveals that its epidermal cells are small and compact and bear root hairs. The cortex comprises multiple layers of thin parenchymatic cells. The central cylinder, bound by endodermis, has both primary and secondary xylems, bast bundles, and phloem in between the bast bundles and secondary xylem.

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The transverse section of the stem of adult lentil plants is typical of dicotyledonous plants with a small pith in the centre and conspicuous vascular bundles. Primary and secondary xylem tissues are intercepted by modular rays and are bounded by phloem tissues. In the angular sides of the stem there are bundles of mechanical fibres in the cortical region. These contribute to the strength of the stem. In addition, in the transverse sections of the stem of large-seeded lentils fibro vascular bundles are visible at the angular parts. The medulla of the stem is often filled with starch grains. The anatomical structure of the branch is very similar to that of the stem except that the central part is rather large and filled with parenchymatic tissues. The epidermal cells of the leaf are covered with a thin cuticle and they are interspersed with simple lens-shaped stomata. Below a compact layer of palisade tissues, there are several layers of spongy parenchyma, both containing chloroplasts. In the cross-section of the leaf at the midrib the bundle of mechanical fibres can be seen. There are also cells filled with calcium oxalate crystals. The cross-section of the cover of unripe pods shows an outer and inner epidermis, the outer one conspicuously lined with cuticle. Immediately below the outer epidermis are parenchymatic tissues containing chloroplasts. Interspersed are the cells loaded with oxalate crystals. Below the parenchymatic tissues and above the lower epidermis are mechanical fibre tissues. The cross-section of the seed testa shows a conspicuous cuticular layer followed by a thin light layer just above the long and compact palisade tissues constituting the epidermis. There is a layer of hypoderma just below the epidermis and this is followed by several layers of thin-walled parenchyma. The cotyledons have a thin layer of epidermis followed by large storage cells containing starch crystals.

4.9. Growth Habits in Lentil and Plant Types Adapted to Different Agroecological Conditions A combination of plant structure and development traits determines the plant type of a genotype. An ideal plant type for a given environment is one that provides the best adaptation to that environment (Lal, 2001). Stem height, number of branches, and angle of branching, which determines the canopy width, are the key traits that determine the structure of a plant. The rate of early vegetative growth and ground-cover development (which is a reflection of early vigour and which affects interception of radiation and water use efficiency and the size of the vegetative frame of the plant; Silim et al., 1993), phenological traits in relation to the prevailing environmental conditions, and the ability of the plants to partition photosynthate and other nutrients into the seed are some of important developmental and physiological traits to be considered for designing an ideal plant type for a particular agroecological situation.

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According to Kusmenoglu and Muehlbauer (1998), increased seed yield in lentil has been obtained through development of cultivars with shorter vegetative and generative growth periods, greater rates of crop and seed growth, and a higher seed-partitioning coefficient. This strategy is preferred for the regions where there is little or no rainfall during the later stages of crop growth and development (Silim et al., 1993). For irrigated conditions, where no serious water scarcity is expected during the critical stages of crop growth, a different growth habit and plant structure might be needed. According to Solanki et al. (2007), the ideal types of lentil for these conditions should be the ones that do not revert back to vegetative growth on receiving irrigation at the time of flowering and are late maturing to be able to make full use of the long growing season made possible by irrigation. An erect plant type with shorter internodes and strong stem, so that the crop may not lodge, and bearing pods 10–15 cm above the ground surface permitting mechanized harvest, would be of additional advantage. Cultivar ‘Matilda’ is a good example of this type of lentil adapted to the Wimmera region of Victoria, Australia, where rains do occur late in growing season (Brouwer, 1995). Several researchers (Solanki et al., 1992, 2007; Lal, 2001; Om Vir and Gupta, 2002) have proposed plant ideotypes that would adapt to different agroecological conditions in India. As the conditions in different lentilgrowing areas are vastly different, Lal (2001) has suggested the following different plant types to cover major production systems: (i) for dry/rain-fed conditions – deep root system with high root volume, profuse branching, semi-spreading to spreading growth habit to prevent evaporation, low transpiration, pubescent foliage, reduced biomass, high harvest index and short duration; (ii) for assured moisture conditions – erect to semi-erect growth habit with short internodes, compact plant type with restricted branching, high biomass production capacity and long duration; (iii) for intercropping with other crops – erect and compact growth habit with shorter internodes and a capacity to have good photosynthesis at low-light intensity; (v) for relay cropping/multiple cropping – fast germination capacity, high early vigour, early flowering and responsiveness to improved agronomic inputs.

References Barulina, H. (1930) Lentils of the USSR and other countries. Bulletin of Applied Botany, Genetics and Plant Breeding Supplement 40. USSR Institute of Plant Industry of the Lenin Academy of Agricultural Science Leningrad, USSR, pp. 265. Brouwer, J.B. (1995) Lens culinaris (lentil) cv. Matilda. Australian Journal of Experimental Agriculture 35(1), 117. Duke, J.A. (1981) Handbook of Legumes of World Economic Importance. Plenum Press, New York, pp. 52–57. Ferguson, M.E. and Robertson, L.D. (1999) Morphological and phenological variation in wild relatives of lentil. Genetic Resources and Crop Evolution 46, 3–9. Gahoonia, T.S., Ali, O., Sarker, A., Rahman, M.M. and Erskine, W. (2005) Root traits, nutrient uptake, multi-location grain yield and benefit-cost ratio of two lentil (Lens culinaris, Medik.) varieties. Plant and Soil 272, 153–161.

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M.C. Saxena Kay, D. (1979) Food Legumes. Tropical Products Institute Crop and Products Digest No. 3. Tropical Products Institute, London, UK, pp. 48–71. Kusmenoglu, I. and Muehlbauer, F.J. (1998) Genetic variation for biomass and residue production in lentil (Lens culinaris Medik.). II. Factors determining seed and straw yield. Crop Science 38, 911–915. Lal, S. (2001) Plant type concept in pulses. Souvenir: National Symposium on Pulses for Sustainable Agriculture and Nutritional Security, 17–19 April, New Delhi. Indian Society of Pulses Research and Development (ISPRD), Kanpur, India, pp. 56–62. Malhotra, R.S., Singh, K.B. and Singh, J.K. (1974) Genetic variability and genotypeenvironmental interaction studies in lentil. Journal of Research Punjab Agricultural University 10(1), 17–21. Muehlbauer, F.J. (1974) Seed yield components in lentils. Crop Science 14, 403–406. Muehlbauer, F.J., Cubero, J.I. and Summerfield, R.J. (1985) Lentil (Lens culinaris Medik.). In: Summerfield, R.J. and Roberts, E.I.I. (eds) Grain Legume Crops. Colins, London, UK, pp. 266–311. Muehlbauer, F.J., Summerfield, R.J., Kaiser, W.J., Clement, S.L., Boerboom, C.M., Welsh-Maddux, M.M. and Short, R.W. (2002) Principles and Practices of Lentil Production. United States Department of Agriculture (USDA) Agriculture Research Service (ARS). Available at: http://www.ars.usda.gov/is/np/lentils/lentils.htm (accessed on 28 February 2008). Nezamuddin, S. (1970) Miscellaneous, Masur. In: Kachroo, P. (ed.) Pulse Crops of India. Indian Council of Agricultural Research, Krishi Bhawan, New Delhi, pp. 306–313. Om Vir and Gupta, V.P. (2002) Analysis of relationships of yield factors in microsperma × macrosperma derivatives of lentil. Legume Research 25(1), 15–20. Sarker, A., Erskine, W. and Singh, M. (2005) Variation in shoot and root characteristics and their association with drought tolerance in lentil landraces. Genetic Resources and Crop Evolution 52(1), 87–95. Saxena, M.C. and Hawtin, G.C. (1981) Morphology and growth patterns. In: Webb, C. and Hawtin, G.C. (eds) Lentils. Commonwealth Agricultural Bureau, Slough, UK, pp. 39–52. Silim, S.N., Saxena, M.C. and Erskine, W. (1993) Adaptation of lentil to Mediterranean environment. I. Factors affecting yield under drought conditions. Experimental Agriculture 29, 9–19. Singh, K.B. and Singh, S. (1969) Genetic variability and interrelationship studies on yield and other quantitative characters of lentils. Indian Journal of Agricultural Science 39, 737–741. Solanki, I.S., Singh, V.P. and Wadia, R.S. (1992) Model plant type in lentil (Lens culinaris Medik.). Legume Research 15(1), 1–6. Solanki, I.S., Yadav, S.S. and Bahl, P.S. (2007) Varietal adaptation, participatory breeding and plant type. In: Yadav, S.S., McNeil, D.L. and Stevenson, P.C. (eds) Lentil: an Ancient Crop for Modern Times. Springer, Dordrecht, The Netherlands, pp. 255–274. Szucs, A. (1972) Study of the cultural value of lentil varieties. Agrobotanika 14, 103–124. Tullu, A., Kusmenoglu, I., McPhee, K.E. and Muehlbauer, F.J. (2001) Characterization of core collection of lentil germplasm for phenology, morphology, seed and straw yields. Genetic Resources and Crop Evolution 48, 143–152. Wilson, V.E. and Teare, I.D. (1972) Effect of between and within row spacing on components of lentil yield. Crop Science 12, 507–510. Zohary, D. and Hopf, M. (2000) Domestication of Plants in Old World, 3rd edn. Oxford University Press, UK, pp. 328.

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Agroecology and Crop Adaptation M. Materne1 and K.H.M. Siddique2

1Department 2The

of Primary Industries, Horsham, Victoria, Australia; University of Western Australia, Crawley, Western Australia, Australia

5.1. Introduction Lentil (Lens culinaris Medikus ssp. culinaris) is one of the world’s oldest cultivated plants. It was domesticated in the ‘Fertile Crescent’ of the Near East over 7000 years ago (see Cubero et al., Chapter 3, this volume). Lentil was introduced into the Indo-Gangetic Plain around 2000 bc and now half of the world’s current lentil production is in South Asia. In the Americas, lentil production became widespread in Chile, Argentina and Brazil (Barulina, 1930), prior to expanding into the Palouse region of north-eastern USA in 1916 and western Canada in 1969 (Muehlbauer and McPhee, 2002). In Australia, significant commercial cultivation of lentil only began in 1994. Lentil has become established in a wide range of agroecological environments but production is limited in tropical areas. The spread of lentil from the centre of origin has been accompanied by the selection of traits important for adaptation to environments that can be defined by climate, soil and their impact on season length, abiotic and biotic stresses.

5.2. Production Environments Temperature, and the distribution and quantity of rainfall are the main determinants of where and when lentil is grown around the world. In West Asia, North Africa and Australia lentil is sown in winter in areas that receive annual rainfall of 300–450 mm. In these regions, low temperatures and radiation restrict vegetative growth during winter, but growth is rapid in spring when temperatures are rising. Ripening occurs prior to, or early in summer, when temperatures and evaporation are high and rainfall low. In subtropical regions of Pakistan, India, Nepal and Bangladesh, lentil is also grown as a winter (‘rabi’) crop but temperatures are higher and crops are grown © CAB International 2009. The Lentil: Botany, Production and Uses (eds W. Erskine et al.)

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primarily on residual soil moisture from monsoon rains. In high altitude and/or latitude areas such as central Turkey, USA, Europe and Canada, where the winters are too cold for lentils to grow reliably, sowing is delayed until spring. Lentils are grown on stored moisture and/or snow melt supplemented by rainfall during spring and summer when temperatures are warm and day lengths long. In broad terms lentils have been selected for adaptation to these three major climatic regions of the world. Within each growing region, variations in climate, soils, and their interactions affect lentil productivity and quality either directly or indirectly through their influence on foliar and soil-borne diseases, pests and interactions with rhizobia. While natural selection has been important in establishing crops in traditional lentil-growing areas, the development of new cultivars and/or cultural practices will improve the adaptation, yield and quality of lentil in traditional and newer growing regions. For example, late sowing in the USA and Turkey avoids extremely cold temperatures and the lentil cultivars grown are adapted to growing in summer. Within a region, traits may provide benefits for adaptation over large areas such as with water stress, or smaller areas such as those that occur with local and variable soil toxicities in Australia. To a large extent, cultural practices have been based on the use of landraces but this is changing as new varieties, agronomic, technological, cultural and financial opportunities become available.

5.3. Phenological Adaptation to the Environment Importance of phenology for adaptation The clustering of traits that define the phenological adaptation of lentil to an ecological environment indicates that local environments are important in the evolution of lentil (Erskine et al., 1989). Matching a crop’s phenology to an environment is a key part of improving adaptation and increasing crop yields. The major constraints to seed production in most environments are drought and high temperatures, particularly during flowering and seed growth. Summerfield et al. (1989) reported that, under controlled conditions, progressively warmer temperatures post-flowering restricted vegetative growth, accelerated progress towards reproductive maturity and reduced seed yield in lentil. In temperate and Mediterranean environments, crops are also at risk from frost during flowering and pod fill. Flowering time is particularly important for adaptation as it determines the length of the vegetative phase (sowing to flowering), and determines the climatic conditions that the crop will be exposed to during reproductive growth. Lentil genotypes adapted to West Asia and high latitudes flower too late and produce few pods when grown in southern Asia (Indian subcontinent) because reproductive development begins when conditions are increasingly hot and dry. Similarly, lentils from high latitudes flower and mature too late for economic yields when grown in winter in West Asia and southern Australia. Alternatively, in high latitude countries such as

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North America, lentils from the Middle East and South Asia flower too early and biomass production and seed yields are low. Adaptation to an environment does not necessarily infer optimum adaptation in any one year due to the variability of climate. For example, flowering time and the length of the reproductive period were negatively correlated with seed yield in a very dry year in Syria but not in a wetter year (Silim et al., 1993). In a similar environment in Australia, dry years are also associated with an increase in the frequency of frosts and earlier flowering may expose crops to a greater risk of damage. If flowering is too early in these environments crops cannot produce adequate biomass to sustain large seed yields in average or higher rainfall years.

Flowering response of lentil to photoperiod and temperature Understanding the flowering response of lentil has been a key to understanding adaptation. Roberts et al. (1988) found no evidence for a specific low-temperature response in lentil, while Tyagi and Sharma (1981) reported a small response. Like most annual winter crops, the timing of phenological events in lentil is modulated primarily by the responsiveness to photoperiod and temperature (Summerfield et al., 1985, 1996). In lentil, Erskine et al. (1990) characterized 231 accessions for their flowering response to photoperiod and temperature in glasshouse experiments which were confirmed in field experiments in Syria and Pakistan (Erskine et al., 1994). In both studies, a large proportion of the variation among accessions for time to first flower and response to temperature and photoperiod was related to origin. In particular, sensitivity to photoperiod was dependent on latitude of origin. Accessions from lower latitude countries such as India, Ethiopia and Egypt have a longer non-responsive phase, are less sensitive to photoperiod and more sensitive to temperature (Erskine et al., 1994). A lower sensitivity to photoperiod improved adaptation at lower latitudes by ensuring that flowering occurs at shorter daylengths and is not delayed past the optimal and before temperatures rapidly increase. The dissemination of lentil into new environments has caused selection of different regionally specific balances between photoperiod and temperature for the control of flowering. For example, in Australia, the most broadly adapted lentil cultivars were inherently late to flower but had a relatively large response to temperature and small response to photoperiod (Materne, 2003). Flowering in these genotypes is delayed when days are cooler and shorter, characteristics of a long growing season, but relatively early at lower latitudes where winter temperatures are higher and the length of the growing season is shorter. Inherently early, photoperiod-responsive genotypes, including landraces from Syria, are more specifically adapted to winter sowing in longer season areas of southern Australia. Inherently early, temperature-responsive but photoperiod-insensitive genotypes, such as ‘Precoz’, are specifically adapted to winter sowing in lower latitude short season environments. Inherently late genotypes with only moderate responses

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to temperature and photoperiod were too late to flower in all winter sowing areas of Australia and are specifically adapted to growing in the warm long days of summer at higher latitudes. The photothermal model and climatic data have also been used to select genotypes suited to winter sowing in the highlands of central and eastern Anatolia (Keatinge et al., 1996).

5.4. Impact of Abiotic Stresses on Lentil Adaptation Water availability Water availability, in particular rainfall in dryland farming, is a major determinant of grain yield in most crops whether it occurs during the growing season or prior to sowing and stored in the soil for later use by the crop. In lentil, total growing season rainfall accounted for 41–55% of the total variation in seed yield over many sites and seasons in the West Asia and North Africa (WANA) region (Erskine and Saxena, 1993); up to 80% of the variation in seed yield over several seasons at one site in Syria (Erskine and El Ashkar, 1993), and 56% of the total variation in seed yield among 11 diverse lentil genotypes in south-eastern Australia (Materne, 2003). Compared to pulses such as faba bean and chickpea, lentil is grown in drier areas of WANA with as little as 250 mm of annual rainfall. However, a lack of water is the major limitation to lentil production worldwide and, in its most severe form, drought results in crops with no economic grain yield (see Shrestha et al., Chapter 12, this volume). Autumn- or winter-sown crops in Mediterranean environments are likely to experience intermittent drought during vegetative growth and terminal drought during reproduction when temperatures are rising and rainfall is decreasing. Spring-sown crops in Mediterranean environments and winter-sown crops in the semiarid tropics rely on available soil moisture and experience increasing water stress during the growing season. In South Asia, drought may also occur during plant establishment if sowing is delayed and plant roots cannot reach subsoil moisture. Natural selection and breeding under variable rainfed environments has resulted in landraces and cultivars that have increased water use efficiency and are responsive to moisture availability. Crops must access and use as much water as possible to produce biomass and seed while not losing tissues that have been produced using water. Appropriate phenology, resistance to abiotic diseases and tolerance to abiotic stresses are likely to be important in increasing water use efficiency in an environment. Various mechanisms such as high early vigour, and early flowering and maturity have been proposed for escaping terminal drought. In Syria, the midflowering genotypes ILL 4400 and ILL 4401 had high seed yields in most seasons (Murinda and Saxena, 1983) but they were intolerant to drought in another study where early flowering genotypes were highest yielding (Silim et al., 1993). Similarly, early flowering and maturing genotypes were high yielding in low rainfall, low yielding environments in Australia but the yields

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of these genotypes were low compared to the best mid-flowering genotypes over eight locations and 5 years (Materne, 2003). Although early flowering is important for drought escape, it is not effective if genotypes have a relatively low mean yield over many seasons and sites, due to an inability to respond to increasing available soil moisture. Genotypes that were responsive to temperature for flowering were the most broadly adapted in Australia and may avoid drought by flowering at an optimal time in most years but earlier in drought years when temperatures are often higher (Materne, 2003). Early sowing has been advocated in many areas to avoid rising temperatures and drought during reproduction, and to maximize yields. However, early sowing may expose crops to increased weed competition, diseases and abiotic stresses. Thus, addressing constraints to enable early sowing is another effective method of improving tolerance to terminal drought.

Waterlogging Lentil does not tolerate waterlogging at germination compared to cereals, and vegetative growth and roots are severely depressed by waterlogging after emergence (Jayasundara et al., 1998). Waterlogging can reduce lentil yields at any time during the growing season especially in lower lying areas or on poorly structured soils where drainage is impeded. In Nepal, sowing of lentil after rice is delayed until the soil dries, but in most areas of the world waterlogging is avoided by not growing the crop in prone areas or by using drainage systems. The sensitivity of lentil and potential sensitivity of nitrogen fixation to waterlogging and anaerobic conditions makes irrigation more difficult and its poor growth response explains the low use of lentil in irrigated cropping systems. Opportunities exist to improve adaptation to waterlogging (Bejiga and Anbessa, 1995).

Temperature Temperature has been shown to influence the evolution and adaptation of lentil worldwide and, with water availability, essentially determines the growing season for lentil. The effects of temperature on flowering have been discussed. Erskine (1996) also found that among 171 lentil genotypes from Syria and Turkey, large-seeded (macrosperma) accessions had a longer reproductive period than small-seeded (microsperma) accessions in Syria. He concluded that larger seeded accessions were higher yielding in cooler seasons due to a longer seed-filling period, but were lower yielding at higher temperatures. Worldwide, green lentils are more prominent in colder areas where lentil is grown in summer and matures when temperatures are cooler. Conversely, red lentils dominate production in winter-growing areas where temperatures are increasing during seed maturation. Extremes of temperature during lentil growth and reproduction can result in more

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specific and dramatic effects. For example, high temperatures during spring reduce seed set and cause rapid maturation in West Asia, North Africa and Australia while cold winters limit production to spring sowing in higher altitude or latitude regions. Low temperature In the USA and Turkey, lentil are traditionally grown in spring as cold winter temperatures kill lentil plants. However, large yield increases have been achieved by sowing lentil in winter rather than spring if problems associated with a lack of winter hardiness can be overcome (Muehlbauer and McPhee, 2002). Genotypes able to survive temperatures below freezing during vegetative growth have been selected from field environments where they survived temperatures as low as –26.8°C (Erskine et al., 1981; Hamdi et al., 1996; Stoilova, 2000; Chen et al., 2006) and in controlled environments using a cold treatment of –15°C (Ali et al., 1999). Cold tolerant genotypes originated from high elevation areas, indicating that lentil has adapted to growing at colder temperatures in these areas rather than relying on avoidance (Hamdi et al., 1996). In the USA, winter hardy types have been selected and evaluated with a range of agronomic practices to initiate winter sowing of lentil, but reliability of production is still a major issue (Chen et al., 2006). In some Mediterranean environments such as in Australia, frost during the reproductive period can cause major economic losses by killing flowers, pods and seeds with associated reductions in seed yield and quality. Currently, the only mechanism for limiting frost damage is avoidance by using later flowering genotypes or delaying sowing. However, the benefits of these strategies may be small or non-existent in years when frosts occur, and result in lower yields in other years (Materne, 2003). High temperatures Summerfield et al. (1989) reported that under controlled conditions, progressively warmer temperatures post-flowering restricted vegetative growth, accelerated progress towards reproductive maturity and reduced seed yield. High temperatures associated with strong winds and dry soils are especially damaging. Rhizobia are also susceptible to higher temperatures, particularly when conditions are moist (Malhotra and Saxena, 1993). Earlier flowering and maturity can avoid high temperatures in winter-sowing environments but may expose crops to a greater risk of frost damage in some environments and may limit yield potential.

Nutrient toxicities Lentil are typically grown and adapted to neutral to alkaline soils but yields are compromised where soils are acidic, sodic, saline or have high levels of boron. Alleviating such toxicity problems through soil modification is not

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an economic or practical solution and therefore growing more tolerant cultivars is considered the best approach to overcoming these constraints. Boron Boron toxicity is an increasingly recognized problem of agriculture in the arid areas of West Asia and Australia (Ralph, 1991; Yau and Erskine, 2000; Hobson et al., 2006). Levels as low as 4 ppm have produced visual toxicity symptoms on lentil 26 days after sowing compared with barley and oats at 47 and 37 days, respectively (Chauhan and Asthana, 1981). Hobson et al. (2003) identified lines with tolerance to boron among landraces from Ethiopia (ILL 2024), Afghanistan (ILL 213A, ILL 1818, ILL 1763, ILL 1796) and the Middle East (ILL 5845), while accessions from Europe had the least tolerance. These origins of tolerance are consistent with wheat (Moody et al., 1988), winter barley (Yau, 2002) and field pea (Bagheri et al., 1994) and indicate where excess boron is potentially a problem. When grown in a reconstituted core resembling ‘natural’ high soil boron distribution in Australia, ILL 2024 had no significant reduction in yield where high subsoil boron (18.2 mg/kg) occurred at a depth of either 30 or 10 cm in the soil profile compared with reductions of 32 and 91%, respectively, in the Australian cultivar ‘Cassab’ (Hobson et al., 2004). While the two tolerant accessions ILL 2024 and ILL 213A were generally characterized by an ability to partially exclude boron from shoot tissues, ILL 2024 had less leaf toxicity symptoms but ILL 213A maintained better growth at high leaf boron concentrations (Hobson, 2007). Boron deficiency has been identified as a limitation to lentil production on soils in Nepal (Srivastava et al., 1999) and India (Sakal et al., 1988). Germplasm from South Asia exhibit least symptoms of boron deficiency while those from the Middle East had the most severe symptoms (Srivastava et al., 2000), supporting the data from boron toxicities studies. Gahoonia et al. (2005) found lentil lines with different root morphologies better able to scavenge micronutrients such as boron from the soil and increase yield by 10–20%. There is increasing evidence that the same genetic mechanisms are likely to control tolerance to both boron deficiency and toxicity, predominantly boron exclusion (Yau and Erskine, 2000; Dannel et al., 2002). This dual control may restrict the adaptability of lentils from South Asia to Australia and West Asia and vice versa. Salinity Salinity occurs mainly in arid and semi-arid regions such as in West and Central Asia and in Australia, and where irrigation has led to salinization in the Indo-Gangetic Plain of South Asia, West Asia, North Africa, western USA and Australia (McWilliam, 1986; Saxena et al., 1993; Nuttall et al., 2003). Legumes are relatively sensitive to salt; lentil is comparatively more sensitive than field pea and faba bean and similar to chickpea (Saxena et al., 1993). Variation in the tolerance of lentil to MgSO4, NaCl, Na2SO4 and MgCl2 has been identified (Jana and Slinkard, 1979) but most research has focused

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on tolerance to NaCl. NaCl tolerant accessions have been identified based on seedling symptoms: DL 443 and Pant L 406 (Rai et al., 1985), ILL 5845, ILL 6451, ILL 6788, ILL 6793 and ILL 6796 (Ashraf and Waheed, 1990) and LG 128 (ILL 3534) (Maher et al., 2003). Importantly, a positive correlation was observed between salt tolerance at different stages of growth (Ashraf and Waheed, 1993). Maher et al. (2003) found that tolerant lentil accessions were unaffected by NaCl concentrations commonly found in Australia but the growth of local cultivars was severely reduced. High-yielding breeding lines with improved NaCl tolerance have since been identified and commercialized in Australia (Materne et al., 2006). The response of crops to salinity is affected by many other environmental factors such as soil water status, relative humidity, temperature and nutrition (Saxena et al., 1993; Lachaal et al., 2002). For example, lentils that are slow growing were found to be more sensitive to salt than those growing rapidly (Lachaal et al., 2002). Breeding for increased vigour and the elimination of other abiotic and biotic stresses may offer potential to indirectly reduce the effects of salinity. Sodicity In lentil, increasing soil sodicity (10–25 exchangeable sodium percentage, ESP) reduced plant height, leaf area, leaf dry weight, total biomass production and seed yield in lentil, and reduced both the nitrate reductase activity in the leaf and the total concentration of nitrogen (Singh et al., 1993). Gupta and Sharma (1990) found lentil had a sodicity threshold of 14.0% compared to a value of 40.2% for wheat. Sodicity also results in poor soil structure which can inhibit root growth and water penetration, thus limiting the plants’ access to water and nutrients or causing transient waterlogging. Breeding for stronger roots or waterlogging tolerance may overcome some of the effects of sodicity but research is limited.

Iron and zinc deficiencies Symptoms of iron deficiency are common in lentil, especially on high pH soils where iron becomes less available. In Syria, iron deficiency symptoms were positively correlated with cold susceptibility, which supports observations in other parts of the world and the proposition that wet conditions on calcareous soils increase the development of iron deficiency symptoms and together they affect root activity (Erskine et al., 1993). Yield losses of 18–25% were recorded among genotypes susceptible to iron deficiency in India (Ali et al., 2000). Similarly, in Syria, yield losses of 47% were reported in genotypes with severe iron deficiency symptoms, but no yield loss occurred in accessions with mild visual symptoms (Erskine et al., 1993). Genotypes from relatively warmer climates such as in India and Ethiopia are more sensitive to iron deficiency, while those from the Middle Eastern countries such as Syria and Turkey have high levels of tolerance (Erskine et al., 1993; Ali et al.,

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2000). The dramatic symptoms associated with iron deficiency enable the relatively simple selection of tolerant genotypes in target areas such as the Middle East and Australia. Among the cool season pulses, lentil is the most sensitive to zinc deficiency (Ali et al., 2000). In developed countries, iron and zinc deficiencies are ameliorated through the application of fertilizers, but the use of efficient cultivars will increasingly become important as fertilizer costs increase. Poor nitrogen fixation, due to factors affecting the host, the rhizobia and the symbiosis between the two, can cause nitrogen deficiency and reduced yield in lentil. In this case the adaptation of both the host and rhizobia and the symbiotic relationship are important to ensure good nitrogen fixation, high yield and rotation benefits to cereals. While rhizobia are well adapted to some soils, their persistence and performance can be relatively poor on acid or saline soils (Slattery and Pearce, 2002). Rhizobia strains have been identified that are more tolerant to these soil types and, with a compatible host that is also inherently tolerant to the soil stress, offers opportunities to improve adaptation to acidic or saline soils (Rai and Singh, 1999; Slattery and Pearce, 2002). However, the ability to implement improved rhizobia on fertile, alkaline soils that had a long history of host crops and naturally high levels of rhizobia may be difficult (Slattery and Pearce, 2002).

5.5. Impact of Diseases on Lentil Adaptation In traditional lentil-growing areas diseases have coevolved over thousands of years whereas in newer areas diseases often accompany the spread of lentil, becoming significant only if adapted to the environment. As a result, quarantine restrictions on plant matter and seed occur in some countries to limit the introduction and establishment of diseases. Major diseases of lentils are outlined in Chapter 17. Resistance or tolerance to major disease is a key to the adaptation of lentil in most areas, especially where cultural controls such as fungicides are unavailable or uneconomic. In recent years, resistant cultivars have become available to farmers. For example, Fusarium wilt-resistant cultivars have been released in Syria, and Stemphyllium blight- and rustresistant cultivars in Bangladesh. Although host resistance is an attractive method of disease control, more virulent pathotypes can arise through introduction, recombination or mutation and lead to susceptibility of the crop. This process of coevolution between diseases and host necessitates ongoing breeding and highlights the importance of understanding the pathogen population. Diseases also interact with agronomic practices that change the environmental conditions in which the crop grows and crop growth, thus impacting on the adaptation of disease and host. For example, in Australia, early sowing increased the prevalence of the diseases caused by Ascochyta lentis and Botrytis spp. (Knights, 1987; Materne, 2003).

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5.6. Impact of Management on Lentil Adaptation Management techniques and lentil genotypes grown have evolved over a long period of time and are relatively stable in traditional lentil-growing areas. However, with globalization, lentil germplasm has been distributed around the world and new methods and tools have become available to farmers. These can be used to improve yield and profitability if optimal management practices are used with genotypes adapted to the practices. Management is increasingly being recognized as a key component in genotype by environment interactions. Agronomic management is discussed in more detail in Chapter 14.

Impact of time of sowing on lentil adaptation Lentil is sown after the onset of autumn rains in Mediterranean climates, after the harvest of summer crops in tropical and subtropical regions and in spring in colder areas (Muehlbauer et al., 1995). In the USA, Turkey and New Zealand large yield increases are achieved by sowing lentil in winter rather than spring, however problems with a lack of winter hardiness and/ or increased incidence of diseases, along with weed control issues, must be addressed before winter sowing becomes widespread. The early sowing of lentil often produces the highest seed yield in most environments. However, a delay in sowing may result in the higher yield where early sowing increases the incidence and severity of a disease, insects, weeds or excessive vegetative growth and severe lodging. Early sowing increases yield potential as it lengthens the vegetative growth period, but this also increases the period of coincidence of pathogens, pests and weeds with the crop to increase biotic stress pressure. Therefore resistance to diseases and pests, suitable control strategies, or changes in morphology to reduce disease, such as improved lodging resistance to avoid Botrytis grey mould, may be needed in order to gain the benefits of early sowing. Management practices can also impact on the relative yield response of genotypes and significant interactions between genotype and sowing rate, application of irrigation, row spacing, and sowing depth can also affect yield and thus adaptation.

Impact of weed management methods on lentil adaptation As a result of their slow growth during winter and short stature, lentil competes poorly with weeds and weed control is a major limitation to growing lentil worldwide, particularly with early sowing. In many traditional lentilgrowing countries weeds are removed by hand, but this is time consuming and increasingly uneconomical due to high labour costs. Tillage also reduces

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the impact of weeds but this can delay sowing and increase the risk of erosion and soil degradation. Production in some regions, especially North America and Australia, is dependent on herbicides for weed control. However, broadleaf-herbicide options are limited and most can cause injury to the lentil crop. Cultivars with improved tolerance to herbicides such as diflufenican and metribuzin, 4-(4-chloro-o-tolyloxy)butyric acid (MCPB) (Muehlbauer and Slinkard, 1983), trifluralin (Basler, 1981) or Clearfield Lentil® with tolerance to imidazolinone herbicides (Holm et al., 2002), and with good early vigour offer potential to improve weed control in lentil. Crop topping and weed wick wiping techniques have also been developed to control difficult weeds in Australia (Preston, 2002). However, crop topping is more difficult in later maturing and taller crops and may not be compatible with cultivars that have improved harvestability. The ability to effectively control weeds is vital if lentil is to be adapted to high-input continuous-cropping systems where good weed control is targeted in all crops.

Impact of harvesting methods on lentil adaptation The large-scale production of lentil in developed countries occurs with mechanized harvesting systems, yet many traditional lentil-producing countries are still harvesting by hand. None the less, hand harvesting is considered a major constraint to lentil production and its high cost has caused a large decrease in lentil production in Jordan and Syria (Erskine et al., 1991). Cultivars adapted to mechanical harvesting have been released in Syria, Lebanon, Iraq and Turkey and their use, combined with mechanized harvesting, increased net returns to growers (Sarker and Erskine, 2002). Short height, pod drop, pod dehiscence, lodging and uneven ripening cause seed losses in crops that are machine harvested (Erskine, 1985; Silim et al., 1989; Erskine et al., 1991; Ibrahim et al., 1993). The optimal time for harvesting lentil is also relatively short with plants dropping pods, shattering and lodging if they are harvested too late. Mechanized harvest is a multidimensional problem that can be solved by using suitable cultivars, methods such as rolling to ensure a smooth seedbed, and a harvester setup effective for lentil, including the use of flexi-fronts. Desiccation or swathing also allows timely harvest especially where temperatures are declining at harvest time such as in Canada. Breeding can assist harvest mechanization through the development of taller, non-lodging cultivars that mature evenly and retain their pods and seeds at maturity. However, in the USA, tall, erect cultivars had lower yield and competed poorly with weeds compared to shorter branching types (Muehlbauer et al., 1995). Erskine and Goodrich (1988) found that lodging increased with plant height and late maturity and therefore tall or late genotypes must have good lodging resistance for machine harvest. Breeding lines that were erect at harvest are also more prone to pod-drop due to high winds, highlighting the need to simultaneously breed for both traits (Materne et al., 2002).

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Improving adaptation through understanding genotype by environment interactions in lentil The key to understanding adaptation is in the interpretation of genotype by environment interactions (GxE) and how genotypes respond to a changing environment. It is of particular importance where breeding programmes are developing cultivars for soils, climates and biotic factors that vary widely across locations and years. Most of these environmental conditions are a result of natural variation but some such as soil fertility and weed control can be affected by management over time. Management practices can also impact on the relative yield response of genotypes and significant interactions between genotype and sowing rate, sowing time and application of irrigation have been identified in lentil. The complexity of adaptation is demonstrated in the significant GxE in all studies conducted on lentil, even though the potential to identify GxE is often limited by the number and/or diversity of genotypes, sites or years. The great challenge is to identify genotypes that are broadly adapted across a defined region, or genotypes specifically adapted to particular regions, and the traits that are important for this adaptation. The first indications and explanation of GxE in lentil occurred when morphological differences in lentil landraces were related to specific adaptation to a region, for example flowering time (Barulina, 1930; Erskine and Witcombe, 1984; Erskine et al., 1989). Many other examples of soil, climate and biotic factors have been reviewed that can explain GxE between diverse regions. Within a region, GxE can be difficult to explain. Hamdi et al. (1991) found only small GxE in West Asia but specific adaptation can be identified from other studies. ILL 4400 and ILL 4401 had a high yield in most years and sites in Syria (Murinda and Saxena, 1983) but were intolerant to drought and were lower yielding than earlier flowering genotypes in dry environments (Silim et al., 1993). Under irrigation in Egypt GxE was significant for yield in the 1 year of testing and were related to differences in soil type and temperature (Hamdi and Rebeia, 1991). In two separate studies in India, some lentil genotypes were identified that were stable in yield over 3 years of testing and others that were better adapted to low- and high-yielding years (Sharma, 1999; Solanki, 2001). Sharma (1999) proposed early maturity for stable yields. In Ethiopia, significant GxE was explained by the distribution of seasonal rainfall with later maturing genotypes being favoured when rainfall occurred over a longer period (Bejiga et al., 1995). In some studies the highest yielding genotypes were the most unstable for yield and performed poorly in low-yielding environments, but high-yielding genotypes with average stability in yield were considered to have the greatest economic potential (Bejiga et al., 1995; Chowdhury et al., 1998; Elwafa, 1999; Sharma, 1999; Solanki, 2001). However, this was not the case in Australia where the intermediate flowering group of cultivars had the highest and most stable yields (Materne, 2003). While flowering response explained much of the variation in grain yield across sites in this study, Indian genotypes had the desired flowering response for broad adaptation but were

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low yielding across Australia, indicating that other factors were also important for adaptation.

5.7. Conclusion Lentil has historically been grown as a source of protein to complement cereals in the diet. However, the adaptation of lentil is increasingly related to its economic value to farmers who ultimately decide to grow the crop. To improve adaptation, the key traits that facilitate increased production (level and reliability of seed production), farming system benefit and price (quality of seed), or reduce cost must be identified, quantified and addressed through improved production technology and breeding. More specifically, profitability is a culmination of a species interaction with the environment, in particular the quantity and distribution of rainfall and temperature which influences the length of growing season, soil characteristics and biotic stresses, and cultural practices. Farming system benefits include those involved with rotation, such as providing a disease break or improving soil nutrition, weed management, and the timing and simplicity of total farm operation.

References Ali, A., Johnson, D.L. and Stushnoff, C. (1999) Screening lentil (Lens culinaris) for cold hardiness under controlled conditions. Journal of Agricultural Science, Cambridge 133, 313–319. Ali, M., Dahan, R., Mishra, J.P. and Saxena, N.P. (2000) Towards the more efficient use of water and nutrients in food legume cropping. In: Knight, R. (ed.) Proceedings of the Third International Food Legumes Research Conference. Vol. 34. Kluwer Academic Publishers, Dordrecht, The Netherlands, pp. 99–105. Ashraf, M. and Waheed, A. (1990) Screening of local/exotic accessions of lentil (Lens culinaris Medic.) for salt tolerance at two growth stages. Plant and Soil 128, 167– 176. Ashraf, M. and Waheed, A. (1993) Responses of some local/exotic accessions of lentil (Lens culinaris Medic.) to salt stress. Journal of Agronomy and Crop Science 170, 103–112. Bagheri, A., Paull, J.G. and Rathjen, A.J. (1994) The response of Pisum sativum L. germplasm to high concentrations of soil boron. Euphytica 75, 9–17. Barulina, H. (1930) Lentils of the USSR and other countries. Bulletin of Applied Botany, Genetics and Plant Breeding Supplement 40. USSR Institute of Plant Industry of the Lenin Academy of Agricultural Science Leningrad, USSR, 265 pp. (English summary) Basler, F. (1981) Weeds and their control. In: Webb, C. and Hawtin, G. (eds) Lentils. Commonwealth Agricultural Bureau, Slough, UK, pp. 143–154. Bejiga, G. and Anbessa, Y. (1995) Waterlogging tolerance in lentil. LENS Newsletter 22, 8–10. Bejiga, G., Tsegaye, S. and Tullu, A. (1995) Stability of seed yield of lentil varieties (Lens culinaris Medik.) grown in the Ethiopian highlands. Crop Research 9, 337–343.

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M. Materne and K.H.M. Siddique Chauhan, R.P.S. and Asthana, A.K. (1981) Tolerance of lentil, barley and oats to boron in irrigation water. Journal of Agricultural Science, Cambridge 97, 75–78. Chen, C.C., Miller, P., Muehlbauer, F., Neill, K., Wichman, D. and McPhee, K. (2006) Winter pea and lentil response to seeding date and micro- and macro-environments. Agronomy Journal 98, 1655–1663. Chowdhury, A.K., Newaz, M.A., Nilofar, N., Uddin, M.S. and Ali, M. (1998) Genotype × environment interaction in lentil. Bangladesh Journal of Scientiﬁc and Industrial Research 33, 107–111. Dannel, F., Pfeffer, H. and Romheld, V. (2002) Uptake of boron in higher plants – uptake, primary translocation and compartmentation. Plant Biology 4, 193–204. Elwafa, A.A. (1999) Mean performance and phenotypic stability in lentils (Lens culinaris Medik). Assiut Journal of Agricultural Sciences 30, 63–76. Erskine, W. (1985) Selection for pod retention and pod dehiscence in lentils. Euphytica 34, 105–112. Erskine, W. (1996) Seed-size effects on lentil (Lens culinaris) yield potential and adaptation to temperature and rainfall in West Asia. Journal of Agricultural Science, Cambridge 126, 335–341. Erskine, W. and El Ashkar, F. (1993) Rainfall and temperature effects on lentil seed yield in Mediterranean environments. Journal of Agricultural Science, Cambridge 121, 347–354. Erskine, W. and Goodrich, W.J. (1988) Lodging in lentil and its relationship with other characters. Canadian Journal of Plant Science 68, 929–934. Erskine, W. and Saxena, M.C. (1993) Problems and prospects of stress resistance breeding in lentil. In: Singh, K.B. and Saxena, M.C. (eds) Breeding for Stress Tolerance in Cool-season Food Legumes. John Wiley and Sons, Chichester, UK, pp. 51–62. Erskine, W. and Witcombe, J.R. (1984) Lentil Germplasm Catalog. International Center for Agricultural Research in the Dry Areas (ICARDA), Aleppo, Syria. Erskine, W., Myveci, K. and Izgin, N. (1981) Screening a world lentil collection for cold tolerance. LENS Newsletter 13, 19–27. Erskine, W., Adham, Y. and Holly, L. (1989) Geographic distribution of variation in quantitative traits in a world lentil collection. Euphytica 43, 97–103. Erskine, W., Ellis, R.H., Summerfield, R.J., Roberts, E.H. and Hussain, A. (1990) Characterisation of responses to temperature and photoperiod for time to flowering in a world lentil collection. Theoretical and Applied Genetics 80, 193–199. Erskine, W., Diekmann, J., Jegatheeswaran, P., Salkini, A., Saxena, M.C., Ghanaim, A. and Ashkar, F.E.L. (1991) Evaluation of lentil harvest systems for different sowing methods and cultivars in Syria. Journal of Agricultural Science, Cambridge 117, 333–338. Erskine, W., Saxena, N.P. and Saxena, M.C. (1993) Iron deficiency in lentil: yield loss and geographic distribution in a germplasm collection. Plant and Soil 151, 249–254. Erskine, W., Hussain, A., Tahir, M., Bahksh, A., Ellis, R.H., Summerfield, R.J. and Roberts, E.H. (1994) Field evaluation of a model of photothermal flowering responses in a world lentil collection. Theoretical and Applied Genetics 88, 423–428. Gahoonia, T.S., Omar, A., Sarker, A., Rahman, M.M. and Erskine, W. (2005) Root traits, nutrient uptake, multi location grain yield and benefit-cost ratio of two lentil (Lens culinaris, Medikus) varieties. Plant and Soil 272, 153–161. Gupta, S.K. and Sharma, S.K. (1990) Response of crops to high exchangeable sodium percentage. Irrigation Science 11, 173–179. Hamdi, A. and Rebeia, B.M.B. (1991) Genetic and environmental variation in seed yield, seed size and cooking quality of lentil. Annals of Agricultural Science 29, 51–60.

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Hamdi, A., Erskine, W. and Gates, P. (1991) Relationships among economic characters in lentil. Euphytica 57, 109–116. Hamdi, A., Kusmenoglu, I. and Erskine, W. (1996) Sources of winter hardiness in wild lentil. Genetic Resources and Crop Evolution 43, 63–67. Hobson, K.B. (2007) Investigation of boron toxicity in lentil. PhD thesis, The University of Melbourne, Melbourne, Australia. Hobson, K., Armstrong, R., Connor, D., Nicolas, M. and Materne, M. (2003) Genetic variation in tolerance to high concentrations of soil boron exists in lentil germplasm. In: Solutions for a Better Environment. Proceedings of the 11th Australian Agronomy Conference, Australian Society of Agronomy, 2–6 February 2003, Geelong, Victoria, Australia. Available at: http://www.regional.org.au/au/asa/2003/ c/1/hobson.htm (accessed 2 December 2008). Hobson, K., Armstrong, R.D., Nicolas, M.E., Connor, D.J. and Materne, M.A. (2004) Boron tolerance of lentil – highlights of a research program. In: New Directions for a Diverse Planet. Proceedings of the Fourth International Crop Science Congress, 26 September–1 October 2004, Brisbane, Australia. Available at: http://www. cropscience.org.au/icsc2004/symposia/6/2/1028_hobsonkb.htm (accessed 2 December 2008). Hobson, K., Armstrong, R., Nicolas, M., Connor, D. and Materne, M. (2006) Response of lentil (Lens culinaris) germplasm to high concentrations of soil boron. Euphytica 151, 371–382. Holm, F.A., Slinkard, A.E. and Vandenberg, A. (2002) Lentil Plants having Increased Resistance to Imidazolinone Herbicides. Patent number 2002302232. Ibrahim, M., Erskine, W., Hanti, G. and Fares, A. (1993) Lodging in lentil as affected by plant population, soil moisture and genotype. Experimental Agriculture 29, 201–206. Jana, M.K. and Slinkard, A.E. (1979) Screening for salt tolerance in lentils. LENS Newsletter 6, 25–27. Jayasundara, H.P.S., Thomson, B.D. and Tang, C. (1998) Responses of cool season grain legumes to soil abiotic stresses. Advances in Agronomy 63, 77–153. Keatinge, J.D.H., Aiming, Qi, Kusmenoglu, I., Ellis, R.H., Summerfield, R.J., Erskine, W. and Beniwal, S.P.S. (1996) Using genotypic variation in flowering responses to temperature and photoperiod to select lentil for the west Asian highlands. Agriculture and Forest Meteorology 78, 53–65. Knights, E.J. (1987) Lentil: a potential winter grain legume crop for temperate Australia. Journal of the Australian Institute of Agricultural Science 53, 271–280. Lachaal, M., Grignon, C. and Hajji, M. (2002) Growth rate affects salt sensitivity in two lentil populations. Journal of Plant Nutrition 25, 2613–2625. Maher, L., Armstrong, R. and Connor, D. (2003) Salt tolerant lentils – a possibility for the future? In: Solutions for a Better Environment. Proceedings of the 11th Australian Agronomy Conference, Australian Society of Agronomy, 2–6 February 2003, Geelong, Victoria, Australia. Available at: http://www.regional.org.au/au/ asa/2003/c/1/hobson.htm (accessed 2 December 2008). Malhotra, R.S. and Saxena, M.C. (1993) Screening for cold and heat tolerance in coolseason food legumes. In: Singh, K.B. and Saxena, M.C. (eds) Breeding for Stress Tolerance in Cool-season Food Legumes. John Wiley and Sons, Chichester, UK, pp. 227–244. Materne, M.A. (2003) Importance of phenology and other key factors in improving the adaptation of lentil (Lens culinaris Medikus) in Australia. PhD thesis, The University of Western Australia, Perth, Western Australia. Materne, M., McMurray, L., Nitschke, S., Regan, K., Heuke, L., Dean, G. and Carpenter, D. (2002) The future of Australian lentil production. In: Brouwer, J.B.

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M. Materne and K.H.M. Siddique (ed.) Proceedings of Lentil Focus 2002, Horsham, Victoria, Australia. Pulse Australia, Sydney, pp. 14–18. Available at: [email protected] (accessed 2 December 2008). Materne, M., Regan, K., McMurray, L., Nitschke, S., Dean, G., Heuke, L. and Matthews, P. (2006) Breeding for NaCl tolerance and improved adaptation in lentil. In: Mercer, C.F. (ed.) Breeding for Success: Diversity in Action. Proceedings of the 13th Australasian Plant Breeding Conference, 18–21 April, Christchurch, New Zealand. New Zealand Grass Association, Christchurch, New Zealand, pp. 1198– 1203. McWilliam, J.R. (1986) The national and international importance of drought and salinity effects on agricultural production. Australian Journal of Plant Physiology 13, 1–13. Moody, D.B., Rathjen, A.J., Cartwright, B., Paull, J.G. and Lewis, J. (1988) Genetic diversity and geographic distribution of tolerance to high levels of soil boron. In: Proceedings of the 7th International Wheat Genetics Symposium. Institute of Plant Science Research, Cambridge, UK, pp. 859–865. Muehlbauer, F.J. and McPhee, K.E. (2002) Future of North American lentil production. In: Brouwer, J.B. (ed.) Proceedings of Lentil Focus 2002, Horsham, Victoria, Australia. Pulse Australia, Sydney, pp. 8–13. Available at: [email protected]. au (accessed 2 December 2008). Muehlbauer, F.J. and Slinkard, A.E. (1983) Lentil improvement in the Americas. In: Saxena, M.C. and Varma, S. (eds) Proceedings of the International Workshop on Faba Beans, Kabuli Chickpeas and Lentils in the 1980s, Aleppo, Syria. International Center for Agricultural Research in the Dry Areas (ICARDA), Aleppo, Syria, pp. 351–366. Muehlbauer, F.J., Kaiser, W.J., Clement, S.L. and Summerfield, R.J. (1995) Production and breeding of lentil. Advances in Agronomy 54, 283–332. Murinda, M.V. and Saxena, M.C. (1983) Agronomy of faba beans, lentils, and chickpeas. In: Saxena, M.C. and Varma, S. (eds) Proceedings of the International Workshop on Faba Beans, Kabuli Chickpeas and Lentils in the 1980s, Aleppo, Syria. International Center for Agricultural Research in the Dry Areas (ICARDA), Aleppo, Syria, pp. 229–244. Nuttall, J.G., Armstrong, R.D. and Connor, D.J. (2003) Evaluating physicochemical constraints of calcarosols on wheat yield in the Victorian southern Mallee. Australian Journal of Agricultural Research 54, 487–497. Preston, C. (2002) Managing an eternal pest – weeds. In: Brouwer, J.B. (ed.) Proceedings of Lentil Focus 2002, Horsham, Victoria, Australia. Pulse Australia, Sydney, pp. 69–73. Available at: [email protected] (accessed 2 December 2008). Rai, R. and Singh, R.P. (1999) Effect of salt stress on interaction between lentil (Lens culinaris) genotypes and Rhizobium spp. strains: symbiotic N2 fixation in normal and sodic soils. Biology and Fertility of Soils 29, 187–195. Rai, R., Nasar, S.K.T., Singh, S.J. and Prasad, V. (1985) Interactions between Rhizobium strains and lentil (Lens culinaris Linn.) genotypes under salt stress. Journal of Agricultural Science, Cambridge 104, 199–205. Ralph, W. (1991) Boron problems in the southern wheat belt. Rural Research 153, 4–8. Roberts, E.H., Summerfield, R.J., Ellis, R.H. and Stewart, K.A. (1988) Photo-thermal time for flowering in lentils (Lens culinaris Medic.) and the analysis of potential vernalisation responses. Annals of Botany 61, 29–39. Sakal, R., Singh, A.P. and Sinha, R.B. (1988) Differential reaction of lentil varieties to boron application in calcareous soil. LENS Newsletter 15, 27–29.

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Sarker, A. and Erskine, W. (2002) Lentil production in the traditional lentil world. In: Brouwer, J.B. (ed.) Proceedings of Lentil Focus 2002, Horsham, Victoria, Australia. Pulse Australia, Sydney, pp. 35–40. Available at: [email protected] (accessed 2 December 2008). Saxena, N.P., Johansen, C., Saxena, M.C. and Silim, S.N. (1993) The challenge of developing biotic and abiotic stress resistance in cool-season food legumes. In: Singh, K.B. and Saxena, M.C. (eds) Breeding for Stress Tolerance in Cool-season Food Legumes. John Wiley and Sons, Chichester, UK, pp. 245–270. Sharma, R.K. (1999) Stability behaviour of some lentil genotypes under north western Himalayan conditions. Annals of Agricultural Research 20, 195–197. Silim, S.N., Saxena, M.C. and Erskine, W. (1989) Effect of cutting height on the yield and straw quality of lentil and on a succeeding wheat crop. Field Crops Research 21, 49–58. Silim, S.N., Saxena, M.C. and Erskine, W. (1993) Adaptation of lentil to the Mediterranean environment. I. Factors affecting yield under drought conditions. Experimental Agriculture 29, 9–19. Singh, B.B., Tewari, T.N. and Singh, A.K. (1993) Stress studies in lentil (Lens esculenta Moench). III. Leaf growth, nitrate reductase activity, nitrogenase activity and nodulation of two lentil genotypes exposed to sodicity. Journal of Agronomy and Crop Science 171, 196–205. Slattery, J.F. and Pearce, D. (2002) Development of elite inoculant Rhizobium strains in southeastern Australia. In: Herridge, D. (ed.) Inoculants and Nitrogen Fixation of Legumes in Vietnam. Australian Centre for International Agricultural Research (ACIAR) Proceedings 109. ACIAR, Canberra, pp. 86–94. Solanki, I.S. (2001) Stability of seed yield and its component characters in lentil (Lens culinaris). Indian Journal of Agricultural Sciences 71, 414–416. Srivastava, S.P., Joshi, M., Johansen, C. and Rego, T.J. (1999) Boron deficiency of lentil in Nepal. LENS Newsletter 26, 22–24. Srivastava, S.P., Bhandari, T.M.S., Yadav, C.R., Joshi, M. and Erskine, W. (2000) Boron deficiency in lentil: yield loss and geographic distribution in a germplasm collection. Plant and Soil 219, 147–151. Stoilova, T. (2000) Evaluation of lentil germplasm accessions for winter hardness in Bulgaria. Bulgarian Journal of Agricultural Science 6, 61–164. Summerfield, R.J., Roberts, E.H., Erskine, W. and Ellis, R.H. (1985) Effects of temperature and photoperiod on flowering in lentils (Lens culinaris Medic.). Annals of Botany 56, 659–671. Summerfield, R.J., Muehlbauer, F.J. and Short, R.W. (1989) Controlled environments as an adjunct to field research on lentils (Lens culinaris). V. Cultivar responses to above- and below-average temperatures during the reproductive period. Experimental Agriculture 25, 327–341. Summerfield, R.J., Ellis, R.H. and Crawford, P.Q. (1996) Phenological adaptation to cropping environment from evaluation of descriptors of times to flowering to the genetic characterisation of flowering responses to photoperiod and temperature. Euphytica 92, 281–286. Tyagi, M.C. and Sharma, B. (1981) Effect of photoperiod and vernalization on flowering and maturity in macrosperma lentils. Pulse Crops Newsletter 1(2), 40–41. Yau, S.K. (2002) Comparison of European with West Asian and North African winter barleys in tolerance to boron toxicity. Euphytica 123, 307–314. Yau, S.K. and Erskine, W. (2000) Diversity of boron-toxicity tolerance in lentil growth and yield. Genetic Resources and Crop Evolution 47, 55–61.

6

Genetic Resources: Collection, Characterization, Conservation and Documentation

B.J. Furman,1* C. Coyne,2 B. Redden,3 S.K. Sharma4 and M. Vishnyakova5 1International

Center for Agriculture Research in the Dry Areas (ICARDA), Aleppo, Syria; 2Western Regional Plant Introduction Station, Pullman, Washington, USA; 3Department of Primary Industries, Horsham, Victoria, Australia; 4National Bureau of Plant Genetic Resources, New Delhi, India; 5N.I. Vavilov Institute of Plant Industry (VIR), St Petersburg, Russia *Present address: United States Department of Agriculture (USDA) Agriculture Research Service (ARS), Palmer, Alaska, USA

6.1. Major Ex Situ Collections Conservation of Lens germplasm is almost entirely ex situ as seed, including wild and domestic annuals as well as wild perennials. The International Center for Agricultural Research in Dry Areas (ICARDA) has the global mandate for research on lentil improvement, and thus houses the world collection of Lens, which includes around 10,800 accessions. The ICARDA lentil genetic resources collection includes 8860 accessions of cultivated lentil from more than 70 different countries representing four major geographic regions (Fig. 6.1), 1373 ICARDA breeding lines, and 583 accessions of six wild Lens taxa, representing 24 countries (Table 6.1; see Cubero et al., Chapter 3, this volume). The majority of the ICARDA collection (48%) consists of accessions from Central and West Asia and North Africa, the centre of origin and primary diversity (Zohary and Hopf, 1988; Ferguson and Erskine, 2001; see Cubero et al., Chapter 3, this volume), while South Asia contributed an additional 25%. All members of Lens are self-pollinating diploids (2n = 2x = 14; Sharma et al., 1996), although relatively high levels of outcrossing have been reported (Erskine and Muehlbauer, 1991). The lentil accessions in the ICARDA collection have been obtained from 113 ICARDA collection missions (46%), 56 donor institutions (44%) and ICARDA’s breeding programme (10%). Collection missions contributed 1734 cultivated and 374 wild accessions. However, based on the numbers of 64

© CAB International 2009. The Lentil: Botany, Production and Uses (eds W. Erskine et al.)

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Wild Lens Cultivated lentil

Fig. 6.1. Distribution of the ICARDA lentil collection locations. 65

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B.J. Furman et al. Table 6.1. Wild Lens accessions maintained at ICARDA. Number of Taxonomic name Lens culinaris ssp. odemensis L. culinaris ssp. orientalis L. culinaris ssp. tomentosus Lens ervoides Lens lamottei Lens nigricans Total

Countries represented 4 14 2 15 3 8 46

Accessions 65 268 11 166 10 63 583

wild Lens accessions available, germplasm from North African countries such as Algeria, Libya, Sudan and Tunisia appear to be under-represented in the collection, as does germplasm from the new Central and West Asian republics of the former Soviet Union (Ferguson and Erskine, 2001). Recent missions to Central Asia and the Caucasus have substantially decreased geographic gaps from this region, yielding a total of 122 cultivated and 27 wild Lens accessions (K. Street, ICARDA, Syria, personal communication). Studies on the distribution of genetic variation (Ferguson et al., 1998) suggest that the overall collection priority for wild species should focus on south-west Turkey, particularly the provinces of Burdur, Isparta and Afyon. The other major collections worldwide include those at the Australian Temperate Field Crops Collection (ATFCC) in the Department of Primary Industries, Victoria, Australia (http://149.144.200.50:8080/QMWebRoot/ SiteMain.jsp) with 5250 accessions, Pullman United States Department of Agriculture (USDA) Agricultural Research Service (ARS) with 2797 accessions (http://www.ars.grin.gov/), the N.I. Vavilov All-Russian Research Institute of Plant Industry (VIR) (http://vir.nw.ru/) with 2396 accessions, and the National Bureau of Plant Genetic Resources, India with 2212 accessions (Dwivedi et al., 2006). In addition, many countries maintain working collections associated with their national breeding programmes. Such collections are conserved for short- to medium-term utility, and thus storage conditions may not be as stringent for maintenance of viability as in the major collections. The major collections follow the recommended storage guidelines for genebanks (FAO/IPGRI, 1994), containing a base collection of over 100 seeds at between –18 and –20°C for long-term conservation and an active collection of at least 1000 seeds at 2–5°C for medium-term storage and distribution. Seeds are dried to 15% relative humidity before storage. Seeds are stored in moisture-proof containers. Vacuum and heat sealing of plasticlined foil envelopes is one of the common genebank procedures for base collections, allowing seeds to remain viable for up to 100 years given optimal storage conditions. The active collections are generally stored in plastic screw-top containers for easier access. The active collections should retain

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high viability for at least 30 years, given high initial viability, low seed moisture and immediate storage postharvest. Optimization of storage conditions is an inexpensive and efficient means of extending seed longevity, as well as reducing the annual costs for maintenance of high levels of seed viability in the active collections. The base collections are necessary to maintain the genetic integrity of the seed samples of accessions as originally received, as well as provide very long-term conservation of genetic diversity. They are also utilized to replenish seed stocks in the active collections when necessary. Regeneration of the active collections occurs when seed numbers get low or if there is a risk of low seed viability. Viability tests are therefore carried out regularly to determine the need for regeneration. In addition, safety duplicate collections for long-term storage in other locations are maintained. For example, ICARDA maintains safety duplications in both Mexico and India. A third collection is being prepared for inclusion in the newly developed Arctic Genebank at Svalbard, Norway. ICARDA similarly maintains the safety backup collection for the National Board of Plant Genetic Resources, India. A decision guide for seed regeneration and precautions to maintain genetic integrity is outlined by Sackville Hamilton and Chorlton (1997). The major collections make their seed available upon request. ICARDA distributes approximately 1000 or more accessions/year, free of charge, upon agreement to the Standard Material Transfer Agreement. The other institutes have similar guidelines. These collections are utilized for crop improvement, basic research and augmentation of national collections.

6.2. Core Collections ICARDA was responsible for creating a ‘reference’ core (also referred to as ‘composite’) collection for lentil as part of a large-scale programme of the Consultative Group on International Agricultural Research (CGIAR) Generation Challenge Program that aims to explore the genetic diversity of the global germplasm collections held by the CGIAR research centres (http:// www.generationcp.org). The global composite collection of 1000 lentil accessions was established representing the overall genetic diversity and agroclimatological range of lentil. This collection was compiled from landraces, wild relatives and elite germplasm and cultivars representing the overall ICARDA collection in both distribution and type. The methodology combined classical hierarchical cluster analyses using agronomic traits, and two-step cluster analyses using agroclimatological data linked to the geographical coordinates of the accessions’ collection sites (Furman, 2006). The hierarchical cluster analysis ensured that the level of variation found in the larger collection was maintained in the composite collection. In addition, 64 accessions of landraces, released cultivars and breeding materials for their resistances to a number of stresses affecting lentil production were included in the composite collection upon recommendation of ICARDA breeders.

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The USDA ARS lentil collection selected a core of 234 accessions based on country of origin (Simon and Hannan, 1995). Recently, the core was extended (384 accessions) to add mapping population parents, cultivars and wild accessions, and a subset of pure lines was created. This pure line subset will be distributed to scientists interested in linkage disequilibrium mapping in lentil.

6.3. In Situ Conservation There has been no systematic attempt to conserve Lens diversity in situ using either on-farm techniques or reserves. However, protected areas throughout the range of the genus undoubtedly contain Lens species. Conservation of Lens is passive in these protected areas (species presence and genetic diversity is not being actively managed or monitored) and is thus susceptible to genetic erosion. More active conservation of Lens diversity is found in a few managed reserves of the eastern Mediterranean (e.g. Ammiad in eastern Galilee, Israel; in Turkey at Kaz Dag, Aegean Region; and Amanos, Mersin and Ceylanpinar in the south-east). The latter reserve is particularly important as this area is one of the two centres of genetic diversity for Lens culinaris ssp. orientalis (Ferguson et al., 1998). A second centre was identified in southern Syria (Ferguson et al., 1998), and Maxted (1995) proposed the establishment of a genetic reserve for Vicieae species in the region of Mimas, Djebel Druze in southern Syria. Recently this area was designated as a genetic reserve by the Syrian Scientific Agricultural Research Commission, as part of their Global Environment Facility funded ‘Conservation and Sustainable Use of Dryland Agrobiodiversity’ project (Maxted et al., 2003). Although recent progress has been made towards in situ conservation in the areas of highest Lens genetic diversity, there remains an urgent need to systematically establish both reserves for the wild species of Lens and on-farm projects to conserve the ancient landraces of cultivated Lens species.

6.4. Characterization and Evaluation of Collections The goals of maintaining germplasm collections include preservation of genetic diversity of the species as well as providing information necessary for their utilization. As such there are three major activities of any genebank (Reed et al., 2004): 1. Maintaining genebank inventory using passport information including accession identiﬁers, taxonomic classiﬁcation, country of origin and site data with referencing by latitude, longitude and altitude, whenever possible, dates of acquisition, collector/donor details, synonyms for accessions acquired from other genebanks, etc. 2. Obtaining and documenting accession characterization data using standard trait descriptors (IBPGR, 1985).

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3. Evaluation of accessions for key agronomic traits to enhance their potential for utilization. Maintenance of reliable passport information is essential for accurate record keeping. It is also important to provide information as to the conditions in which the accessions would be likely to be adapted. Characterization data describe discrete classifications for morphological traits such as colours of seed, stems and flowers, as well as standards for quantitative traits such as flowering time, plant height, 100-seed weight, etc. Full records are very important to check for duplication of accessions and for quality assurance on identity. This can be an issue in genebanks with multiple sources of accessions, as well as large numbers of accessions and species. Targeted and more efficient utilization of germplasm by plant breeders/researchers can be achieved if the trait characteristics of accessions are known. These can include the agronomic, disease reaction, yield and quality data of accessions in a particular study, and over different studies for each accession. For example, ICARDA published the Lentil Germplasm Catalog (Erskine and Witcombe, 1984) providing a listing of 20 trait evaluations for 4550 lentil accessions. Since its publication, characterization data have increased for over 4000 additional accessions. Working with world lentil germplasm that is conserved at ICARDA has revealed substantial variability among landraces and wild species for economically important traits. Studies on genetic variability have been conducted since the early 1980s among germplasm of diverse origin. Morphological traits were critically examined in variable climatic conditions for use in breeding and selection programmes (Sarwar et al., 1982; Sindhu and Mishra, 1982; Erskine and Witcombe, 1984; Erskine et al., 1985, 1989; Erskine and Choudhary, 1986; Lakhani et al., 1986; Baidya et al., 1988; Ramgiry et al., 1989; Sarker et al., 2005). These studies revealed responses of flowering to temperature and photoperiod (Erskine et al., 1990, 1993, 1994), tolerances to abiotic stresses (Erskine et al., 1981; Summerfield et al., 1985; Erskine and Goodrich, 1991; Hamdi et al., 1992; Ibrahim et al., 1993; Silim et al., 1993a, b; Hamdi and Erskine, 1996; Srivastava et al., 2000; Yau and Erskine, 2000; Malhotra et al., 2004; Sarker et al., 2004, 2005), genetic variability and sources of resistance to fungal diseases (Khare et al., 1991; Agarwal et al., 1993; Bayaa et al., 1994, 1995, 1997; Abou-Zeid et al., 1995; Robertson et al., 1996; Bayaa and Erskine, 1998; Nasir and Bretag, 1998; Malhotra et al., 2004) and viruses (Makkouk et al., 2001). A number of these accessions possessed multiple resistances (Robertson et al., 1996). Such desirable variability in the crop gene pool allows for genetic enhancement through plant breeding. Unfortunately several other important traits, such as nitrogen fixation, resistance to pea leaf weevil (Sitona sp.), aphids and broomrape (Orobanche sp.) are not currently addressable by breeding due to lack of sufficient genetic variation (Sarker and Erskine, 2006). Evaluation of wild species for resistance to key stresses, including winter hardiness, drought tolerance and resistance to lentil vascular wilt and Ascochyta blight, demonstrated sufficient variability for these traits

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(Bayaa et al., 1994, 1995; Hamdi and Erskine, 1996; Hamdi et al., 1996; Robertson et al., 1996; Nasir and Bretag, 1998). Variation in agronomic characters was also explored within wild germplasm. Results showed that there was no striking variation within the wild species for seed and straw yields. Direct selection of wild lentil germplasm for biomass yield under dry conditions is apparently of little value for transfer to cultivated lentil. The ICARDA composite collection has been evaluated for key morphological and quantitative traits (B. Furman, California, unpublished). In addition, the composite collection has been characterized with 24 simple sequence repeat (SSR) markers (e.g. Hamwieh et al., 2005) and diversity parameters such as polymorphic information contents, allelic diversity, etc. have been determined (publication in preparation). This should allow for the extraction of core and reference collections for use by breeders and geneticists. Large-scale genotyping is also underway on the lentil core collection held by the USDA/ARS in Pullman, Washington, USA using 39 mapped SSRs (C. Coyne, Washington, personal communication). The ARS studies are for fine mapping of disease resistance quantitative trait loci (QTL) identification (F. Muehlbauer, Washington, personal communication).

6.5. Utilization of Lentil Germplasm In general, breeders narrow the genetic diversity of their breeding populations in the process of selecting the required trait combinations for improved varieties (Maxted et al., 2000). Genebanks aim to conserve the original landrace diversity both for current and for unforeseen future needs in breeding, as well as surveying and enhancement of germplasm diversity for key traits and identification of novel genes in wild relatives. The provision of an evaluation/passport database covering the major world collections means that targeted multiple trait searches of most of the available lentil germplasm can now be carried out more efficiently and effectively. Strategies such as allele pyramiding in key traits and sourcing of novel genes from wild relatives should now be easier to realize. The standard practice of genebanks to document passport data on the origin, synonyms and collection data, with details of source location and associated agriculture, enables the traceability of accessions along with details of collection procedure and evolutionary status. In addition, such data provide information about likely adaptation characteristics in relation to the physical environment and the local climatic regime. Unless conservation is linked to utilization there is a risk that genebanks may become museums (Maxted et al., 2000). Knowledge of the growth characteristics and reactions to abiotic and biotic stresses of accessions is thus exceedingly important. Each of the major genebanks has their own documentation system that can be utilized by curators for efficient maintenance and distribution of seed. In addition, these data can now be outsourced for multiple traits from combined databases, such as constructed by ATFCC, using International

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Crop Information Systems (ICIS) platforms for digital search and retrieval across relational databases over countries and years. An example is the ATFCC International Lentil Information System (ILIS) evaluation database for lentil germplasm, which combines databases of ICARDA, USDA and ATFCC, enabling a more comprehensive search of the combined genetic resources over large collections for multiple trait expressions (http://149.144.200.50:8080/QMWebRoot/SiteMain.jsp). As far as possible, the internationally standard descriptors (IBPGR, 1985) are used for trait records in ILIS. Additionally ILIS has options for converting quantitative trait data to a 1–9 scale based on arithmetic division of the range of values (outlying values quality checked and filtered out), or on statistical normalization of data from each location/year set to a mean of 0 (zero) and a range of +/–2 standard deviations for 95% of the variation if distributed as a standard normal distribution. These conversions eliminate the environmental component from observed values, as well as the genotype × environment interaction, to provide genetic comparisons of landraces for trait expressions. These data can be combined across locations and years, and across different genebanks, to enable initially simple searching for accessions with either high or low trait expressions according to breeding goals. Selected accessions can then be requested online from genebanks, and the breeder then has a prospective subset of germplasm for validation in the respective target environments for farmer clients, and choice of parents for the breeding programme. The ILIS database allows online users to run search–query interrogations for germplasm with multiple trait expressions, currently from the combined ICARDA, USDA and ATFCC collections. This is a very powerful search engine to assist genebank clients, to add value to the collections, and to facilitate utilization for crop improvement. It is becoming more necessary in the current trend for economic rationalization to demonstrate and justify the expense for genebank operations, in both the short term with current crop improvement outcomes, and the long term where a genetic insurance strategy may be very prescient to cope with a looming climate change. Close linkage of lentil collections with breeders, pathologists and students, for evaluating key traits is becoming a significant genebank activity. The ATFCC staff actively work with lentil breeders in germplasm enhancement for evaluation of tolerances to salinity, frost, herbicides and disease (Redden et al., 2006). Similarly, ICARDA has identified sources of resistance to rust, vascular wilt and Ascochyta blight in the domestic gene pool, and found additional sources of resistance to vascular wilt and Ascochyta blight, and greater cold tolerance in the wild progenitor L. culinaris ssp. orientalis (Ferguson, 2000). Two important new developments in molecular genetics are its applicability to genebanks. One is the use of molecular markers for DNA ‘fingerprint’ characterization of individual accessions. These tools enable the identity of accessions between collections to be confirmed, detection of duplicates within collections, and analyses of genetic relatedness among accessions to define the structure of genetic diversity within a species/genus. This knowledge assists

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breeders seeking allelic diversity for particular traits. The other application is the capacity of allele mining for various traits using association genetics, both within species/wild relative collections, and across species with comparative genomics (Spooner et al., 2005).

References Abou-Zeid, N., Erskine, W. and Bayaa, B. (1995) Preliminary screening of lentil for resistance to downy mildew. Arab Journal of Plant Protection 13, 17–19. Agarwal, S.C., Singh, K. and Lal, S.S. (1993) Plant protection of lentil in India. In: Erskine, W. and Saxena, M.C. (eds) Proceedings of Seminar on Lentil in South Asia, New Delhi, India. International Center for Agricultural Research in the Dry Areas (ICARDA), Aleppo, Syria, pp. 147–167. Baidya, B.N., Eunus, A.N. and Sen, S. (1988) Estimations of variability and correlation in yield and yield contributing characters in lentil (Lens culinaris). Environment and Ecology 6, 694–697. Bayaa, B. and Erskine, W. (1998) Diseases of lentil. In: Allen, D.J. and Lenne, J.M. (eds) Pathology of Food and Pasture Legumes. CAB International, Wallingford, Oxon, UK, pp. 423–471. Bayaa, B., Erskine, W. and Hamdi, A. (1994) Response of wild lentil to Ascochyta fabae f.sp. lentis from Syria. Genetic Resources and Crop Evolution 41, 61–65. Bayaa, B., Erskine, W. and Hamdi, A. (1995) Evaluation of a wild lentil collection for resistance to vascular wilt. Genetic Resources and Crop Evolution 42, 231–235. Bayaa, B., Erskine, W. and Singh, M. (1997) Screening lentil for resistance to fusarium wilt: methodology and sources of resistance. Euphytica 98, 69–74. Dwivedi, S.L., Blair, M.W., Upadhyaya, H.D., Serraj, R., Balaji, J., Buhariwalla, H.K., Ortiz, R. and Crouch, J.H. (2006) Using genomics to exploit grain legume biodiversity in plant breeding. In: Janick, J. (ed.) Plant Breeding Reviews 26. John Wiley and Sons, Hoboken, New Jersey, USA, pp. 171–357. Erskine, W. and Choudhary, M.A. (1986) Variation between and within lentil landraces from Yemen Arab Republic. Euphytica 35, 695–700. Erskine, W. and Goodrich, W.J. (1991) Variability in lentil growth habit. Crop Science 31, 1040–1044. Erskine, W. and Muehlbauer, F.J. (1991) Allozyme and morphological variability, outcrossing rate and core collection formation in lentil germplasm. Theoretical and Applied Genetics 83, 119–125. Erskine, W. and Witcombe, J.R. (1984) Lentil Germplasm Catalog. International Center for Agricultural Research in the Dry Areas (ICARDA), Aleppo, Syria. Erskine, W., Myveci, K. and Izgin, N. (1981) Screening a world lentil collection for cold tolerance. LENS Newsletter 8, 5–8. Erskine, W., Williams, P.C. and Nakhoul, H. (1985) Genetic and environmental variation in the seed size, protein, yield and cooking quality of lentils. Field Crops Research 12, 153–161. Erskine, W., Adham, Y. and Holly, L. (1989) Geographic distribution of variation in quantitative characters in a world lentil collection. Euphytica 43, 97–103. Erskine, W., Ellis, R.H., Summerfield, R.J., Roberts, E.H. and Hussain, A. (1990) Characterization of responses to temperature and photoperiod for time to flowering in a world lentil collection. Theoretical and Applied Genetics 80, 193–199. Erskine, W., Saxena, N.P. and Saxena, M.C. (1993) Iron deficiency in lentil: yield loss and geographic distribution in a germplasm collection. Plant and Soil 151, 249–254.

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Erskine, W., Hussain, A., Tahir, M., Bahksh, A., Ellis, R.H., Summerfield, R.J. and Roberts, E.H. (1994) Field evaluation of a model of photothermal flowering responses in a world lentil collection. Theoretical and Applied Genetics 88, 423–428. Ferguson, M. (2000) Lens spp: conserved resources, priorities for collection and future prospects. In: Knight, R. (ed.) Proceedings of Third International Food Legumes Research Conference (IFLRC III): Linking Research and Marketing Opportunities for Pulses in the 21st Century. Adelaide, Australia, 22–26 September 1997. Kluwer Academic Publishers, Dordrecht, The Netherlands, pp. 613–620. Ferguson, M.E. and Erskine, W. (2001) Lentils (Lens L.). In: Maxted, N. and Bennett, S.J. (eds) Plant Genetic Resources of Legumes in the Mediterranean. Kluwer Academic Publishers, Dordrecht, The Netherlands, pp. 132–157. Ferguson, M.E., Ford-Lloyd, B.V., Robertson, L.D., Maxted, N. and Newbury, H.J. (1998) Mapping of geographical distribution of genetic variation in the genus Lens for enhanced conservation of plant genetic diversity. Molecular Ecology 7, 1743–1755. Food and Agriculture Organization (FAO)/International Plant Genetic Resources Institute (IPGRI) (1994) Genebank Standards. FAO/IPGRI, Rome, Italy. Furman, B.J. (2006) Methodology to establish a composite collection: case study in lentil. Plant Genetic Resources: Conservation and Utilization 4, 2–12. Hamdi, A. and Erskine, W. (1996) Reaction of wild species of the genus Lens to drought. Euphytica 91, 173–179. Hamdi, A., Erskine, W. and Gates, P. (1992) Adaptation of lentil seed yield to varying moisture supply. Crop Science 32, 987–990. Hamdi, A., Küsmenogˇlu, I. and Erskine, W. (1996) Sources of winter hardiness in wild lentil. Genetic Resources and Crop Evolution 43, 63–67. Hamwieh, A., Udupa, S.M., Choumane, W., Sarker, A., Dreyer, F., Jung, C. and Baum, M. (2005) A genetic linkage map of Lens sp. based on microsatellite and AFLP markers and the localization of Fusarium vascular wilt resistance. Theoretical and Applied Genetics 110, 669–677. Ibrahim, M., Erskine, W., Hanti, G. and Fares, A. (1993) Lodging in lentil as affected by plant population soil moisture and genotype. Experimental Agriculture 29, 201–206. International Board for Plant Genetic Resources (IBPGR) (1985) Lentil Descriptors. IBPGR and International Center for Agricultural Research in the Dry Areas (ICARDA), IBPGR Secretariat, Rome, Italy. Khare, M.N., Agrawal, S.C. and Jain, A.C. (1991) Diseases of Lentil and their Control. Jawaharlal Nehru Krishi Vishwa Vidyalaya, Jabalpur, Madhya Pradesh, India. Lakhani, J.P., Holker, S. and Misra, R. (1986) Genetics of seedling vigor and hard seed in lentil. LENS Newsletter 13, 10–12. Makkouk, K., Kumari, S., Sarker, A. and Erskine, W. (2001) Registration of six lentil germplasm lines with combined resistance to viruses. Crop Science 41, 931–932. Malhotra, R.S., Sarker, A. and Saxena, M.C. (2004) Drought tolerance in chickpea and lentil – present status and future strategies. In: Rao, S.C. and Ryan, J. (eds) Challenges and Strategies for Dryland Agriculture. Special Publication 32, Crop Science Society of America, Madison, Wisconsin, USA, pp. 257–274. Maxted, N. (1995) An ecogeographic study of Vicia subgenus Vicia. Systematic and Ecogeographic Studies in Crop Genepools 8. International Board of Plant Genetic Resources, Rome, Italy. Maxted, N., Erskine, W., Singh, D.P., Robertson, L.D. and Asthana, A.N. (2000) Are our germplasm collections museum items? In: Knight, R. (ed.) Proceedings of Third International Food Legumes Research Conference (IFLRC III): Linking Research and Marketing Opportunities for Pulses in the 21st Century. Adelaide,

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B.J. Furman et al. Australia, 22–26 September 1997. Kluwer Academic Publishers, Dordrecht, The Netherlands, pp. 589–602. Maxted, N., Guarino, L. and Shehadeh, A. (2003) In situ techniques for efficient genetic conservation and use: a case study for Lathyrus. In: Forsline, P.L., Fideghelli, C., Knuepffer, H., Meerow, A., Nienhus, J., Richards, K., Stoner, A., Thorn, E., Tombolato, A.F.C. and Williams, D. (eds) Proceedings of XXVI International Horticultural Congress: Plant Genetic Resources, the Fabric of Horticulture’s Future. Acta Horticulturae 623. International Society for Horticulture Science, Leuven, Belgium, pp. 41–60. Nasir, M., and Bretag, T. (1998) Screening lentil for Ascochyta blight resistance. Annual Report, Centre for Legumes in Mediterranean Agriculture 14, 2–6. Ramgiry, S.R., Paliwal, K.K. and Tomar, S.K. (1989) Variability and correlations of grain yield and other qualitative characters in lentil. LENS Newsletter 16, 19–21. Redden, B., Enneking, D., Balachandra, R., Murray, K., Smith, L. and Clancy, T. (2006) The Australian temperate field crops collection of genetic resources for pulses and oilseeds. In: Mercer, C.F. (ed.) Proceedings of 13th Australian Plant Breeding Conference. New Zealand Grassland Association, Christchurch, New Zealand, pp. 838–843. Reed, B.M., Engelmann, F., Dulloo, M.E. and Engels, J.M.M. (2004) Technical Guidelines for the Management of Field and In Vitro Germplasm Collections. International Plant Genetic Resources Institute (IPGRI) Technical Handbook No. 7. IPGRI, Rome, Italy. Robertson, L.D., Singh, K.B., Erskine, W. and Abd El Moneim, A.M. (1996) Useful genetic diversity in germplasm collections of food and forage legumes from West Asia and North Africa. Genetic Resources and Crop Evolution 43, 447–460. Sackville Hamilton, N.R. and Chorlton, K.K. (1997) Regeneration of Accessions in Seed Collections: a Decision Guide. Handbook for Genebanks No. 5. International Board for Plant Genetic Resources, Rome, Italy, 75 pp. Sarker, A. and Erskine, W. (2006) Recent progress in the ancient lentil. Journal of Agricultural Sciences, Cambridge 144, 1–11. Sarker, A., Erskine, W. and Saxena, M.C. (2004) Global perspective on lentil improvement. In: Masood Ali, Singh, B., Kumar, S. and Dhar, V. (eds) Pulses in New Perspective. Indian Society of Pulses Research and Development, Indian Institute for Pulses Research, Kanpur, India, pp. 543. Sarker, A., Erskine, W. and Singh, M. (2005) Variation in root and shoot traits and their relationship in drought tolerance in lentil. Genetic Resources and Crop Evolution 52, 87–95. Sarwar, D.M., Kaul, A.K. and Quader, M. (1982) Correlation studies in lentils. LENS Newsletter 9, 22–23. Sharma, S.K., Knox, M.R. and Ellis, T.H.N. (1996) AFLP analysis of the diversity and phylogeny of Lens and its comparison with RAPD analysis. Theoretical and Applied Genetics 93, 751–758. Silim, S.N., Saxena, M.C. and Erskine, W. (1993a) Adaptation of lentil to the Mediterranean environment. I: Factors affecting yield under drought conditions. Experimental Agriculture 29, 9–19. Silim, S.N., Saxena, M.C. and Erskine, W. (1993b) Adaptation of lentil to the Mediterranean environment. II: Response to moisture supply. Experimental Agriculture 29, 21–28. Simon, C. and Hannan, R. (1995) Development and use of core subsets of cool-season food legume germplasm collections. HortScience 30, 907. Sindhu, J.S. and Mishra, H.O. (1982) Genetic variability in Indian microsperma type lentil. LENS Newsletter 9, 10–11.

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Spooner, D., van Truenen, R. and de Vicente, M.C. (2005) Molecular Markers for Genebank Management. International Plant Genetics Resources Institute (IPGRI) Technical Bulletin No. 10. IPGRI, Rome, Italy. Srivastava, S.P., Bhandari, T.M.S., Yadav, C.R., Joshi, M. and Erskine, W. (2000) Boron deficiency in lentil: yield loss and geographic distribution in a germplasm collection. Plant and Soil 219, 147–151. Summerfield, R.J., Roberts, E.H., Erskine, W. and Ellis, R.H. (1985) Effects of temperature and photoperiod on flowering in lentils (Lens culinaris Medic.). Annals of Botany 56, 659–671. Yau, S.K. and Erskine, W. (2000) Diversity of boron-toxicity tolerance in lentil growth and yield. Genetic Resources and Crop Evolution 47, 55–61. Zohary, D. and Hopf, M. (1988) Domestication of Plants in the Old World. Clarendon Press, Oxford, UK.

7

Genetics of Economic Traits B. Sharma

Indian Agricultural Research Institute, New Delhi, India

7.1. Introduction Although lentil is among the most prominent grain legumes globally, its economic position strengthened significantly when it became important in international trade about two decades ago. This, coupled with the International Center for Agricultural Research in the Dry Areas’ (ICARDA) focused attention on the crop as its world mandate, served as a stimulus for enhanced research in the area of genetics, breeding and biotechnology. This chapter deals with the genetics of characters showing discrete, identifiable and contrasting phenotypes. The inheritance and selection for traits displaying continuous variation is covered by Sarker et al. in Chapter 8, Rahman et al. in Chapter 9 and Muehlbauer et al. in Chapter 10, and gene mapping, linkage and the use of marker-assisted selection are covered by Ford et al. in Chapter 11 (all in this volume).

7.2. Induced Mutagenesis Well-identified traits with contrasting phenotypes in different genetic backgrounds are a prerequisite to embark upon genetic analysis. Attempts to identify such genetically analysable traits genetically in lentil germplasm yielded only about three dozen morphological traits for which dominant and recessive phenotypes were available (Mishra and Sharma, 2003). Clearly it is essential to discover more genes by induced mutation. A few hundred mutations is a reasonably good starting base for linkage studies. Some induced mutations also have breeding value, while many others may serve as dependable selectable markers and donors for economic traits. As in other crops, chlorophyll mutations are easily induced in lentil (Sharma and Sharma, 1981a; Dixit and Dubey, 1986a) and are recessive to the normal 76

© CAB International 2009. The Lentil: Botany, Production and Uses (eds W. Erskine et al.)

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green phenotype (Vandenberg and Slinkard, 1987, 1989) and have been reported by Solanki and Sharma (2005) and Ladizinsky (1985). A wide range of mutations are reported for plant height, growth habit, branching pattern, stem structure including fasciation, leaf morphology including a leaf mutant with complex tendril structure, inflorescence, calyx shape, flower structure, pod characters, glabrous, waxless, short rachis, acute pod, sterility and seedcoat colour, curled apex, stunted growth, radicle hypertrophy, bilobed cotyledon leaves, tricotyly, barren apex, and giant seedlings (Sharma and Sharma, 1978c, d, e, 1979, 1980a; Dixit and Dubey, 1986a; Tyagi and Gupta, 1991; Tripathi and Dubey, 1992; Ramesh and Tyagi, 1999; Vandana et al., 1999). The mutation frequency can be increased manifoldly by identifying M1 plants with maximum mutagenic damage in terms of seedling injury and sterility (Sarker, 1985; Sharma, 1986; Sarker and Sharma, 1988, 1989; Solanki, 1991; Solanki and Sharma, 2000). Mutations in dwarfing genes had a great impact in the history of plant breeding. Such mutations were reported in lentil by Sharma and Sharma (1981b). Ladizinsky (1997) isolated two spontaneous dwarf mutations (genes df1 and df2) from a segregating population. Independently induced dwarf mutations were given different names by their respective authors, for example compact and bushy (Sharma and Sharma, 1978a, b). Tirdea and Mancas (1986) isolated several mutations with high amino acid content. Mutations of a physiological nature (Sharma and Sharma, 1980b) such as early mutations (Sharma and Sharma, 1982) and male sterility (Sharma and Sharma, 1978f) have a potential for developing varieties and hybrids with better adaptability.

7.3. Inheritance of Morphological Traits Growth habit Ladizinsky (1979) reported incomplete dominance of bushy/erect growth habit and proposed the gene symbol Gh. The gene analysed in this study appears to be different from the recessive ert gene discovered and mapped subsequently (Emami and Sharma, 1999a). The erect phenotype denoted by ert is recessive to the most prevalent growth habit in lentil in which the plant remains procumbent for about a month and the branches start growing upright thereafter. This growth habit can be called semi-erect or semispreading. The wild relatives of cultivated lentil have prostrate stems for much longer. The gene Ert has been linked with three other genes: Rdp, Bl and Gs (Emami and Sharma, 1999a; Kumar et al., 2004a, 2005a).

Red foliage Several studies have analysed red pigmentation of different plant parts in lentil: epicotyl (gene Gs for green stem; Ladizinsky, 1979), leaf (gene Bl for brown leaf; Emami and Sharma, 1996a) and pods (gene Grp for green pod;

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Vandenberg and Slinkard, 1989; and Pdp for pod with violet stripes; Havey and Muehlbauer, 1989). The gene symbol for anthocyanin development on immature pods was changed to Rdp (red pod) by Emami (1996) with a view to avoid ambiguity as ‘green pod’ (for which gene Grp was first proposed) could be a contrasting phenotype for a variety of colours of the pod wall, that were dominant in some cases (e.g. yellow pods of chlorophyll mutations, or green plants producing yellow pods as the recessive gene gp in pea), and recessive in others (against red pod). The Gs—Rdp linkage was the first to be reported (Ladizinsky, 1979; Zamir and Ladizinsky, 1984; Havey and Muehlbauer, 1989; Muehlbauer et al., 1989; Weeden et al., 1992) and was called Linkage Group 1 of lentil.

Light green foliage The intensity of leaf colour within the normal range of foliage colour has also been considered to be a major property distinguishing the macrosperma lentils from microsperma, the former being yellowish green. The variety ‘Precoz’ is a well-known example. Genetic analysis (Kumar, 2002) between normal green and light green genotypes showed segregation of a single gene with normal green as dominant identified by gene symbol Gl. It was also found linked with the genes for plant height, pubescence development, and number of leaflets per leaf in the order Ph—Gl—Pub—Hl (Kumar et al., 2005c).

Leaflet shape, size and number The shape and size of leaflets are traits of taxonomic significance as the macrosperma lentils differ from microsperma by their leaf size and morphology. Kumar et al. (2005d) identified two contrasting phenotypes for leaf shape: oval and acute. The trait was reported to be monogenic, oval being dominant over acute. Gene symbol Ol is proposed. It is linked with the genes for leaflet size (Blf), stipule size (Lst) and pod size (Lpd), and the ‘Globe’ mutant (Kumar et al., 2006, unpublished data). Crosses between genotypes with broad and narrow leaflets showed monogenic inheritance with incomplete dominance. This trait was identified by gene symbol Blf (Kumar et al., 2004b) and its linkage with the genes Ol, Lst, Lpd and Glo established (Kumar et al., 2006, unpublished data). The phenotype with high number of leaflet pairs (more than six in any leaf on a plant) is monogenically dominant over the one with fewer leaflets (Kumar et al., 2005c). It has been given the gene symbol Hl.

Tendril formation The paripinnate compound leaf of lentil terminates with or without an apical unbranched tendril that varies in size from a spur to 5 cm or more in

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length in different genotypes. Vandenberg and Slinkard (1989) analysed the inheritance of the presence or absence of tendrils and showed the tendrilless phenotype to be monogenic recessive, and proposed the gene symbol Tnl. Distortion of segregation may occur due to misclassification of the F2 plants with rudimentary tendrils. Out of nine crosses attempted by Kumar (2002) F2 segregation fitted well to a 3:1 ratio in only four crosses. Five crosses had an excess of tendril-less plants. None had an excess of tendrilled plants. Crosses showing abnormal segregation had Lens 6163 as the male or female parent. Obviously, Lens 6163 is a tendril-potent genotype with minute tendrils. As a result, some of the tendrilled F2 plants were included in the tendril-less class. Monogenic inheritance of tendril formation has been confirmed (Vaillancourt and Slinkard, 1992; Emami, 1996).

Plant pubescence Pubescence development has been considered an important attribute in lentil taxonomy and is a major criterion to distinguish microsperma from macrosperma lentils. This trait has been treated differently by workers mainly because the intensity of pubescence varies across plant parts and developmental stages. Generally, maximum expression of pubescence is seen on the growing tips at the vegetative stage and on the inflorescence. Vandenberg and Slinkard (1989) analysed the relationship between pubescent and glabrous pods and assigned the gene symbol Glp. Emami (1996) observed that pubescence on the peduncle is a more reliable trait and redesignated the gene as Pdp. Kumar (2002) on a closer look concluded that pubescence, when present, is noticeable on the entire plant, with a variable degree of expression on different organs and gradually disappearing on aged parts. Thus, a plant has to be either totally pubescent or glabrous. The gene symbol was therefore again changed to Pub and later shown to be linked to the gene for light green foliage (Hoque, 2001; Hoque et al., 2002b). With two additional morphological markers the linkage sequence was extended to Ph—Gl— Pub—Hl (Kumar et al., 2004a, 2005c).

Plant height Tallness in plants is almost universally shown to be dominant over dwarfness since Mendel’s times. It is associated with the synthesis or working efficiency of gibberellins and other growth hormones. Tallness is dominant over dwarfness in lentil also. The gene Ph for plant height, first reported by Tahir et al. (1994), belongs to the linkage group comprising eight morphological (Ph, Gl, Pub, Hl, P, Mot, Brt, Pi) and at least 13 isozyme markers (cf. Kumar et al., 2005c). In addition to this discrete segregation in the F2, plant height has been found to be quantitatively inherited (Haddad et al., 1982).

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Globe mutant Gupta et al. (1983) induced a globular-shaped ornamental dwarf mutation in Lens 830 that is recessive to the wild phenotype. These observations were confirmed by Emami (1996) and Kumar (2002). Its linkage has been established with the genes for leaflet shape (Ol) and size of leaflets (Blf), stipule size (Lst) and pod size (Lpd) (Kumar et al., 2006, unpublished data).

Stem fasciation Stem fasciation as a genetic trait has been known in plants since the times of G. Mendel. Induced mutations for stem fasciation in lentil were variously reported by Sharma (1977), Sharma and Sharma (1980a), Tyagi and Gupta (1991) and Solanki (1991), and was always found to be recessive (Sharma and Sharma, 1977).

Stipule size The stipules of lentil vary from very small (4 mm long, 1 mm broad) to very large (11 mm long, 4 mm broad). Crosses between extreme phenotypes (Kumar, 2002) revealed that stipule size has Mendelian monogenic inheritance with incomplete dominance. Gene symbol Lst was proposed for stipule size. Its linkage with the genes Ol, Blf, Lpd and Glo for other morphological traits has been demonstrated (Yogesh et al., unpublished data).

Flowering time Although flowering time is highly influenced by temperature and photoperiod (Summerfield et al., 1985), genetic control of days to flower is well established in plant species. These two environmental factors have played a vital role in the adaptation of lentil in spatially isolated parts of the globe (Erskine et al., 1989, 1990). A model of photothermal response of flowering was developed on the basis of field evaluation of the ICARDA world collection (Erskine et al., 1994) and this genetic variation has been successfully used to select lentil genotypes for the West Asian highlands (Keatinge et al., 1996). Kant and Sharma (1975) observed that all microsperma lines in a germplasm collection were early (flowering in 60–80 days) and the remaining macrosperma genotypes originating from the western hemisphere were always late, producing flowers after 80 days. Some of these macrosperma genotypes did not produce flowers under the short-day conditions of Indian winter. Sarker et al. (1998, 1999) concluded monogenic inheritance of flowering time with earliness being recessive, for which gene symbol Sn was proposed. Early flowering transgressive segregation in F2 is a consequence of interaction between recessive sn and minor genes for earliness. It was also concluded

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that flowering time in lentil is determined by this major gene in combination with a polygenic system. Earliness was shown to be linked to Scp (the gene for seedcoat pattern that was replaced by the Mot–Spt locus; Emami, 1996) and Pep (for pubescent peduncle, now Pub) in Linkage Group 5. The recombination fraction between Sn and Pep was estimated to be 38 ± 8.7. Another analysis of flowering time in lentil (Emami, 1996) based on 25 crosses between early, medium and late maturing strains in all possible combinations revealed its quantitative nature with continuous variation and transgressive segregation in the F2 without maternal effect. Interestingly, the widest range of transgressive segregation was recorded when early maturing microsperma varieties developed in India (e.g. PKVL-1, Lens 830, Pant L 406, Pant L 639, etc.) were crossed with the earliest divergent macrosperma variety ‘Precoz’ of Latin American origin, as by Tyagi and Sharma (1989). The parent varieties flowered after 70–72 days, but their hybrids threw transgressants that flowered as early as 45–47 days and as late as 120 days. In the same experiment, crosses among microsperma varieties did not yield transgressive segregants flowering earlier than 60 days. Clearly, microsperma and macrosperma lentils have different sets of genes controlling flowering time, and all microsperma genotypes share the same gene pool. Similar transgressive segregation can be expected for other economically important traits. Flower colour Several flower colours have been identified in lentil, namely violet, pink, blue and purple. The intensity of flower colour varies depending on genotype, age of flower, and is subject to temperature and sunlight conditions. Red (or pink) flowers were never observed in a large germplasm collection maintained at the Division of Genetics, Indian Agricultural Research Institute, Delhi nor in the ICARDA lentil collection (A. Sarker, personal communication). Probably, the terms violet (Lal and Srivastava, 1975), blue (Ladizinsky, 1979) and purple (Kumar, 2002) have been used synonymously. Accordingly, different gene symbols have been assigned, for example V for violet and P for pink (Lal and Srivastava, 1975), W for white (Wilson and Hudson, 1978), and P for purple (Kumar, 2002). The possibility of multiple alleles to explain some of the intermediate colours cannot be ruled out. Lal and Srivastava (1975) and Gill and Malhotra (1980) reported complete monogenic dominance of violet flower over white flower. Kumar et al. (2005b) confirmed monogenic complete dominance of purple flower over white and reported its linkage with mottled seed pattern and brown ground colour of testa in the sequence P—Mot—Brt. This is in agreement with Hoque et al. (2002a). Number of flowers per peduncle The number of flowers borne on a peduncle in lentil may have an impact on its productivity potential. Its genetic analysis is complicated because flower

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number per peduncle is inconsistent in expression declining with plant age, and is highly influenced by the environment. This may cause misclassification of F2 plants. Nevertheless, considering its breeding value Gill and Malhotra (1980) concluded that flower number is a monogenic trait with the two-flower phenotype dominant over three-flowered. Subsequent studies of Emami (1996) and Kumar (2002) produced contrary results. The latter author used the prolificacy potential to classify plants. A plant was treated as three-flowered or four-flowered if it produced that many flowers even on a single peduncle. Using this procedure both these studies concluded that higher flower number per peduncle is dominant.

Pod size The size of lentil pods varies in a wide range and is often but not completely associated with seed size. The inheritance of pod size was studied by Kumar et al. (2005e) who found monogenic inheritance with incomplete dominance and no maternal effects. This trait was assigned gene symbol Lpd which is a member of the linkage group Lst—Ol—Blf—Lpd—Glo (Kumar et al., 2006, unpublished data).

Pod dehiscence Pod dehiscence is a trait of great economic value as it sometimes causes significant losses before or during harvest. Pod dehiscence is a survival trait in wild species such as Lens orientalis. Among the cultivated lentils also, the oriental microsperma lentils have a higher degree of dehiscence than their occidental macrosperma counterparts. Ladizinsky (1979, 1985) found the dehiscent phenotype to be completely dominant over indehiscence and assigned gene symbol Pi. The inheritance of the indehiscence trait was confirmed by Vaillancourt and Slinkard (1992). Among cultivated lentils, a response to selection for pod indehiscence indicates the presence of quantitative variation for the trait (Erskine, 1985). The Pi gene was shown to be linked to isozyme locus Gal-1 (Havey and Muehlbauer, 1989) in what was called Linkage Group 1 in the following order: Pgm-c—Fk—Pgd-p—Me-2—Aat-c—Gal-1—Pi—Gh/Ert (Tahir and Muehlbauer, 1994). Tahir et al. (1993), however, did not show close linkage of Pi to Gh/Ert and placed it in a different linkage segment and also changed the numbering of linkage groups. Havey and Muehlbauer (1989) also placed the Pi and Gh/Ert genes in different linkage segments.

Seedcoat colour Seedcoat colours have been given several names in the literature, for example black, grey, brown, beige, yellowish grey, tan and green. As observed

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by Emami (1996), the lack of precision in naming testa colours may be partly due to the influence of cotyledon pigments on the colour of seedcoat. He noticed that the pigments of orange, pinkish orange (called brown by Emami and Sharma, 1996b, c) and green cotyledons are absorbed in the testa tissue distorting its true colour. Seeds with colourless testa and orange cotyledons appear pinkish and those with green cotyledons appear green. However, the seedcoat may have green colour of its own – a hypothesis that needs to be confirmed experimentally. The pigment of yellow cotyledons does not appear to have such a migratory effect. Therefore it would be desirable to use only yellow-cotyledon genotypes for genetic analysis of testa colour where genotypes with different seedcoat colours and patterns are used as parents. The black testa is obviously dominant or hyperstatic over all other colours. Care must be taken, especially in the case of black seed colour, to distinguish black seeds caused by ground colour and due to dense black spotting. It appears that the so-called tan colour is the colourless situation although Vandenberg and Slinkard (1990) concluded that tan testa is produced by a dominant gene (Tgc) that in combination with another gene, Ggc for grey seedcoat, gives rise to brown testa. Recessive homozygotes for both genes (ggcggctgctgc) produce seeds with green testa. According to this hypothesis, if the three major genes for testa colour (Blt, Ggc and Tgc) are in dominant homozygous (also heterozygous) condition, the seeds will appear black. The migration of green pigment from cotyledons into seedcoat was never considered in these studies. Absorption of orange, brown (pinkish yellow) and green pigments by seedcoat from cotyledons can modify its colour phenotype markedly. The lentil seedcoat has three (or four) basic colours, that is black (if it is really different from black spotting), brown, grey and green. Other colours are a result of either epistatic effects or colour distortions. The green colour of testa, if such a trait exists, could give other hues in combination with brown and grey ground colours. Black seedcoat With proper care, it is possible to identify genotypes that are black seeded because of ground colour and not due to black spotting as strains with black spotting on non-black ground colour are available. The black testa colour has an interesting mode of inheritance (Emami and Sharma, 2000; Sharma et al., 2004a). Vandenberg (1987) found one dominant gene with codominant expression for black seedcoat in one cross and two recessive genes for the same phenotype (i.e. black testa recessive) in two other crosses (Vandenberg and Slinkard, 1990). It is difficult to understand the absence of black pigment being dominant over its presence. All other studies (Vaillancourt and Slinkard, 1992; Emami, 1996; Emami and Sharma, 2000; Sharma et al., 2004a) confirmed monogenic inheritance of black testa. These workers also observed that the F1 plants produce a mixture of black and non-black (brown, grey, green or colourless) seeds. The numbers of black and non-black seeds born on the F1 plants do not make a genetic ratio.

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Vandenberg (1987) described this phenomenon as ‘codominant’ expression of dominant and recessive alleles for black testa. It must be remembered that codominance is simultaneous expression of the two alleles (phenotypes) of a gene in each cell of the same organism. Genetic analysis shows that the F2 plants give a perfect ratio of 3 black + mixture : 1 true breeding non-black. Emami and Sharma (2000) called it a case of dosage effect, incomplete dominance or lack of penetrance/expressivity and concluded that the heterozygous plants produce seeds with black and non-black testa as a result of the quantity of black pigment accumulated in the testa in the course of development. Apparently, the seeds that develop on the upper nodes during late reproductive phase run short of time to accumulate black pigment in sufficient quantity with a single dose of dominant Blt gene before the plant completes its life cycle. This conclusion is supported by the fact that the dominant homozygotes with two doses (Blt Blt) produce seeds with black testa only. Gene symbol Blt was proposed for black seedcoat with new interpretation of its manifestation and inheritance. Vandenberg (1987) and Vandenberg and Slinkard (1990) concluded that black testa colour is controlled by two recessive genes (blsc1 and blsc2) in one cross but it was inherited monogenically in another. However, Vaillancourt and Slinkard (1992) subsequently demonstrated monogenic inheritance of black testa colour and also concluded that Vandenberg’s hypothesis about two-gene control of black testa trait was caused by an error in scoring of the F2 phenotypes. Emami’s (1996) results were in complete agreement with those of Vaillancourt and Slinkard (1992). In view of the uncertainties caused by the Vandenberg’s report, Emami and Sharma (2000) considered his gene symbol Blsc to be invalid and proposed a new gene symbol, Blt, for black testa with monogenic control. Brown, grey and green seedcoat The inheritance of brown seedcoat in lentil was investigated by Ladizinsky (1979), Vandenberg (1987), Vandenberg and Slinkard (1990), Singh and Singh (1993), Emami (1996) and Kumar (2002). Ladizinsky (1979) reported brown testa to be dominant over yellowish grey. In all these studies brown testa displayed monogenic dominance over grey and tan. Vandenberg and Slinkard (1990) further demonstrated digenic dominance of brown testa over green. Both grey and tan were shown to be dominant over green. Consequently, a two-gene hypothesis was proposed: gene Ggc for grey and Tgc for tan testa. Thus, double dominant GgcTgc genotypes produce brown seeds while seeds with green testa will be born on recessive homozygous ggctgc plants. This hypothesis has not been challenged in other studies even though the authors did not examine the possibility of pigments migrating from cotyledons into the testa of developing seeds. Kumar et al. (2005b) however proposed the gene symbol Brt for brown testa, which is now included in the short gene map P—Mot—Brt (Hoque et al., 2002a; Kumar et al., 2005b).

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Tannin in seedcoat Presence of tannin in lentil seedcoat can be detected only if all other pigments are absent and the seed appears colourless. Vaillancourt et al. (1986) analysed the inheritance of tannin in the seedcoat. Presence of tannin was monogenically dominant over its absence, for which gene symbol Tan was proposed. Presence of tannins (proanthocyanidins) in the seedcoat leads to its discoloration (browning) during storage (Bezeda, 1980). Although lentil strains with black testa are generally high in tannins, a strain (PI 211602) with the highest tannin content of 2.29% of its seedcoat among the germplasm of 87 lines screened did not have black testa.

Seedcoat spotting Ladizinsky (1979), Vandenberg and Slinkard (1990) and Emami (1996) observed the presence of spotting on the testa to be dominant over the spotless phenotype. Seedcoat pattern is designated by a generalized gene symbol Scp. Vandenberg and Slinkard (1990) identified two types of spotting, that is spotting (gene Scps) and dotted (Scpd), and concluded that they are multiple alleles at the Scp locus. This however was untenable as they also had true breeding strains with a mixture of both ‘spotted’ and ‘dotted’ patterns, which was called the ‘flex’ phenotype. A closer look on the lentil genotypes in a germplasm collection by Emami (1996) led him to confirm the two types of seedcoat pattern in lentil, however, both behaving as independent traits, each dominant over the spotless phenotype and giving perfect monogenic segregation in the F2. One pattern consisted of minute round spots distributed uniformly over the seedcoat, and the other comprised patches of irregular shape sparsely spread over the seed. They were named as mottling and speckling, respectively, and designated by gene symbols Mot and Spt. Attempts to recombine the Mot and Spt genes indicated tight linkage with Scp (Mot—Spt) locus. The Mot gene (synonymous with Scpd) was placed between the P (purple flower) and Brt (brown testa) genes (see above).

Seed size Even though the cultivated lentils are divided into microsperma and macrosperma primarily on the basis of differences in seed size, there is continuous distribution for the trait. Taking seed size as a criterion, typical Indian lentils (microsperma) form a group of genotypes with 1000-grain weight between 12–35 g. Typically, macrosperma lentils generally weigh above 35 g/1000 seeds. Ladizinsky (1979) crossed L. orientalis and a cultivar of Lens culinaris (both with seed diameters between 4 and 5 mm) with a cultivated strain having 8 mm seed size (a macrosperma genotype) and observed intermediate seed size in the F1 with continuous variation in the next generation. Further, none of the segregants reached the level of the large-seeded parent.

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Seed size is an economic trait of great significance and deserves the attention of geneticists and breeders accordingly. It is a special attribute in lentil consumption and trade. The wholesale price of small- and large-seeded lentils differs by a large margin depending on the consumer preference and farmers’ choice. An important study of lentil seed mass was made by Abbo et al. (1991) using quantitative trait loci (QTL) analysis to analyse the continuous variation expressed in segregating populations. They showed that seed weight was under polygenic control with partial dominance for low seed weight alleles.

Hard seededness The inheritance of hard seedcoat with poor absorption of water by the testa appears to be complicated. Ladizinsky (1985) reported hard seedcoat to be a monogenically inherited trait and designated it with gene symbol Hsc. Vaillancourt and Slinkard (1992) also reported monogenic inheritance but of an opposite nature. Hard seedcoat was dominant over soft seed in a cross with Lens ervoides (Ladizinsky, 1985) and in another cross between cultivated lentils (Vaillancourt and Slinkard, 1992). However, in crosses with L. culinaris ssp. orientalis hard seedcoat was recessive. It is a unique situation that even among wild relatives hard seed is reported to be dominant in one species (L. ervoides) and recessive in the other (L. orientalis). According to Ladizinsky (1985), pod dehiscence (Pi) in L. orientalis is controlled by two complementary genes, one of which is linked to Hsc for hard seedcoat at 18 map units. Vaillancourt and Slinkard (1992) also observed that in some crosses seeds imbibed water but remained dormant for 2–3 weeks. Thus germination was influenced by the genetically caused hard coat as well as physiological dormancy. Vaillancourt and Slinkard (1992) recorded continuous variation for germination in such crosses. The genes for pod indehiscence (pi) and soft seeds that germinate without dormancy (Hsc/hsc) must have played an important role in domestication of lentil as they should have been subject to intensive human selection in the early history of lentil cultivation.

Cotyledon colour Genetics of cotyledon colour in lentil presents a fascinating picture. Cotyledon colour has attracted the attention of geneticists and lentil breeders owing to its market value. The microsperma lentils are predominantly orange (hence they are called red lentils) and macrosperma lentils usually produce yellow cotyledons (they are called green lentils in trade jargon because varieties with light-green seedcoats are most preferred and traded). As cotyledons are sporophytic tissue, their colour can be visualized in the freshly harvested seeds, and segregation for colour can be recorded in the seeds harvested from F1 plants. Emami (1996) constructed a simple

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device to see cotyledon colour in intact seeds (Emami and Sharma, 1996b) without scratching the seedcoat (as done by Slinkard (1978) and Sinha et al. (1987)) and then improved the device into a compact seed scanner (Sharma et al., 2005). The analysis of cotyledon colour has involved crossing genotypes with red and yellow cotyledons (Tschermak-Seysenegg, 1928; Wilson et al., 1970; Singh, 1978; Slinkard, 1978; Sinha et al., 1987; Emami, 1996; Kumar, 2002) with orange found to be dominant over yellow. Slinkard (1978) designated the gene as Yc. However, in addition to the well-known bright-yellow cotyledon, there is another yellow phenotype with a pinkish or brownish tinge, which was called ‘brown’ so as to distinguish the two variants of yellow cotyledons. The two yellow phenotypes are distinguishable, preferably against visible light or under ultraviolet fluorescence (a technique proposed by Wilson et al. (1970) and Papp (1980) and personal communication). Genetic analysis (Emami and Sharma, 1996b, c) revealed the independent nature of the two yellow colours and named their controlling genes as Y and B, respectively. The double dominant YB leads to orange cotyledons, while double recessive plants (yybb) fail to develop pigment in their cotyledons and remain green at maturity. The inhibitory gene hypothesis of Slinkard (1978) suggesting involvement of gene i-Yc has not been confirmed. Nevertheless, Vaillancourt and Slinkard (1993) subsequently demonstrated linkage between the putative inhibitory gene i-Yc for cotyledon colour and isozyme markers Aco I, grp and Aat-p. Thus, existence of two genes associated with yellow cotyledon colour is confirmed. The i-Yc gene proposed by Slinkard (1978) could be the B gene of Emami and Sharma (1996b, c). Another gene was discovered in this study (Emami, 1996; Emami and Sharma, 1999b; Sharma and Emami, 2002), which in the recessive state gives rise to dark-green cotyledons (much darker than the yybb cotyledons). It was named as Dg. Sharma and Emami (2002) concluded that while genes Y and B are individually involved in the synthesis of the yellow and brownish components of the orange complex, respectively, gene Dg acts on their common precursor at an earlier stage in the synthesis of cotyledon pigments and, when mutated, blocks its synthesis. Consequently, both the yellow and the brown pigments are eliminated simultaneously and the cotyledons acquire deep-green colour. The dgdg (dark-green) situation should be functionally equivalent to yybb homozygotes which, however, produce light-green cotyledons. This also suggests that Dg is more effective in its function and the two other genes are ‘leaky’ in the recessive condition. Thus, Dg has a recessive epistatic effect on the other two pigment genes and the three genes (Y, B, Dg), in different combinations, give rise to five F2 phenotypes in the ratio of 27 orange:9 yellow:9 brown:3 light green:16 dark green (Sharma et al., 2004b).

Protein content Lentil is the richest source of dietary proteins among plants that are consumed without industrial processing. Attempts to analyse the inheritance

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of seed protein in lentil (Hamdi et al., 1991; Chauhan and Singh, 1995; Tyagi and Sharma, 1995) revealed the quantitative nature of this trait. This has been the pattern in almost all crops. Protein content on a dry weight basis varied from 20.4 to 28.3% in a sample of 32 germplasm lines and cultivars (Tyagi and Sharma, 1995). Hamdi et al. (1991) analysed 3663 germplasm accessions from all lentil-growing regions of the world and recorded a range of 34.0–86.0 g/1000-grain weight and 25.7–29.8% seed protein. Seed protein content had negligible correlation with grain yield and seed size (r = –0.1 and 0.17, respectively). Protein content is almost universally (especially in cereals; Watson et al., 1965) negatively correlated with seed size. This principle does not seem to apply in the case of lentil. In fact, Tyagi and Sharma (1995) observed that protein content in lentil has a positive, although statistically non-significant (r = 0.26), correlation with seed size.

Abiotic stresses Frost injury Cold tolerance is an essential requirement when lentils are cultivated during winter or at high altitudes. In recent years, winter hardiness has acquired special significance in West Asia as winter planting of lentil has become increasingly popular due to ICARDA’s efforts (Sarker et al., 2002; Emami and Sharma, 2005). Sources of cold resistance have been identified among germplasm (Erskine et al., 1981; Spaeth and Muehlbauer, 1991), including wild species (Hamdi et al., 1996). Eujayl et al. (1999) reported monogenic inheritance of radiation-frost tolerance and assigned gene symbol Frt. This gene was also tagged with random amplified polymorphic DNA (RAPD) marker OPS-16750 at 9.1 cM. Kahraman et al. (2004a, b) concluded that winter hardiness in lentil is a polygenic trait and several QTLs together accounted for 42% of the variation in their recombinant inbred line populations. Further study of the inheritance of winter hardiness and discovery of additional QTLs may account for additional variation and improve prospects for marker-assisted selection. Drought tolerance The water requirement of lentil is low. In fact, excessive water supply is damaging to the crop. This explains the farmers’ choice of lentil in droughtprone arid regions. Wild relatives of lentil may serve as a good resource to reduce its water requirement further (Hamdi and Erskine, 1997). A reliable screening technique for drought tolerance in cowpea in the greenhouse described by Singh et al. (1999) may be used in lentil as well. Soil factors Genetic variation has been found in lentil for response to salinity, nutrient deficiency and toxicity but no genetic analysis has yet been reported. This

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variability is covered by Yadav et al. in Chapter 13 (this volume). Briefly genetic variation in salinity tolerance was reported by Jana and Slinkard (1979), Ashraf and Waheed (1990, 1993) and Ashraf and Zafar (1997). Variations in response to iron and boron deficiency and boron toxicity have been found (Erskine et al., 1993; Srivastava et al., 2000; Yau and Erskine, 2000; Sharma and Sarker, 2008).

Disease resistance Rust resistance Rust requires humid conditions for pathogen growth. It is the most important disease in India economically (Singh and Sandhu, 1988) with reported losses of up to 70% of the lentil crop as a result of rust (Erskine and Sarker, 1997; Negussie et al., 2005). ‘Precoz’, a germplasm accession received from ICARDA in the early 1980s, was found to be universally rust resistant in multilocation trials in India (B. Sharma, unpublished data, reported in the Workshop Proceedings of All-India Coordinated Project on Pulses, Kanpur). Most studies on the inheritance of lentil rust resistance have reported monogenic control, resistance being dominant over susceptibility (Sinha and Yadav, 1989; Singh and Singh, 1992; Chauhan et al., 1996; Kumar et al., 1997a, b). However, besides reports of incomplete resistance, duplicate dominant genes controlling resistance have also appeared frequently (Singh and Singh, 1990; Lal et al., 1996; Kumar et al., 1997b, 2001; Chahota et al., 2002; Mishra, 2006). Only one unconfirmed report suggested rust resistance as a recessive trait in the variety DPL 21. Mishra (2006) also confirmed that the dominant gene for resistance in the variety ‘Precoz’ (macrosperma from Latin America) is different from that in Pant L 4 which is of Indian origin (microsperma). Thus two separate genes controlling rust resistance have evolved in spatially (may be also temporally) isolated groups of lentil. The gene symbols proposed are Urf1 in ‘Precoz’, Urf2 in Pant L 4, E 153 and Lens 4147, and the unconfirmed urf3. Two varieties (Pant L 639 and Pant L 408) developed at Pantnagar (India) were widely rust resistant when they were commercialized. More than a decade after their release for cultivation, Chahota et al. (2002) reported Pant L 639 to be susceptible at Palampur (425 m above mean sea level, 1200 mm rainfall) and Jaacch (428 m above msl, 1500 mm rainfall) in Himachal Pradesh, where ‘Precoz’ was still resistant. The inoculum was multiplied from a single rust colony. It needs to be confirmed whether it is a case of resistance breakdown or race-specific reaction of the variety Pant L 639. ‘Precoz’ was crossed with two susceptible varieties (i.e. Pant L 639 and Lens 259) and with both varieties F2 segregation was in the ratio 15 resistant:1 susceptible at three locations. Lal et al. (1996) had earlier reported two dominant genes for rust resistance in ‘Precoz’ at Palampur, when it was crossed with six susceptible genotypes. This is unequivocal proof that ‘Precoz’ carries two dominant genes (and not one) for rust resistance.

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Wilt resistance Occurrence of wilt in lentil is frequently associated with moisture stress and the intensity of disease depends on inoculum saturation in the soil. Therefore it is imperative to have an accurate screening technique for proper germplasm evaluation and genetic analysis. A highly efficient method of field screening has been developed at ICARDA where a wilt-sick plot of large size ensures complete mortality of susceptible genotypes (Bayaa et al., 1995; Sarker et al., 2004). Continuous efforts have been made to breed wilt-resistant lentils (Izuqierdo and Morse, 1975). Repeated screening of 500 accessions from the core collection of lentil germplasm at ICARDA for 3 years yielded 34 strains that were confirmed for wilt resistance (Sarker et al., 2004). Rigorous screening through F5–F8 led to the identification of 753 resistant lines. Interestingly, 71.6% of wilt-resistant selections were small seeded, whereas only 40.9% of large-seeded selections were resistant to wilt, suggesting that the gene(s) for small seed are loosely associated with wilt-resistance genes. On the basis of a test of allelism, Kamboj et al. (1990) concluded that wilt resistance in lentil is conferred by five dominant genes, two of which were duplicate in the variety Pant L 234 and two others complementary in JL 446 and LP 286. Abbas (1995), however, found only one dominant gene for wilt resistance in crosses at ICARDA. Eujayl et al. (1998b) also recorded monogenic inheritance for wilt resistance and designated the gene as Fw. It was tagged with RAPD marker OPK-15900 with 10.8 cM map distance between them. This study also established linkage of Fw with the RAPD markers OP-B17800 and OP-D15500 in coupling phase and OP-C04650 in repulsion phase. Hamwieh et al. (2005) identified one SSR and another AFLP marker that linked with Fw at distances of 8.0 and 3.5 cM, respectively. Ascochyta blight resistance Ascochyta blight has worldwide occurrence and causes severe damage to lentil yield and grain quality (Muehlbauer and Chen, 2007). In India it is mainly confined to the mountainous regions where lentil is cultivated during warm summers with high humidity. Tivoli et al. (2006) listed the sources of resistance to foliar diseases of lentil, including blight. Searches for sources of blight resistance have been made at many centres (Ahmed and Morrall, 1996; Ahmed et al., 1996). The germplasm accessions PI 339283 from Canada (Andrahennadi et al., 1996) and ILL 358 in Australia (Nasir and Bretag, 1996) have been reported to be the top-ranking blight-resistant genotypes. Blight resistance was shown to be monogenic recessive in the variety ‘Laird’, and two strains from the ICARDA germplasm collection (ILL 538 and ILL 5684) by Tay and Slinkard (1989). Ahmad et al. (1997) reported two complementary dominant genes for blight resistance in a cross between L. ervoides and Lens odemensis. However, only one dominant gene was found in this study when genotypes of L. culinaris were crossed with each other. The existence of two complementary dominant genes within the cultivated lentils was established by Nguen et al. (2001). Ford et al. (1999) mapped two

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RAPD markers, RV01 and RB18, in flanking positions of the resistance gene Ral1 (Abr1) 8.0 and 3.5 cM away. Two more RAPD markers (UBC2271290 and OPD-10870) were located in flanking positions of the recessive gene for resistance, ral2, at 6.4 cM and 10.5 cM distances, respectively, in the variety ‘Indianhead’ (Chowdhury et al., 2001). Anthracnose resistance Resistance to anthracnose in lentil has been reported to be under the control of one recessive gene, lct-1, in cultivar ‘Indianhead’, and two dominant genes, designated as LCt-2 (in PI 320937) and LCt-3 (in PI 345629) (Buchwaldt et al., 2003). Two races of the causal organism, Colletotricum truncatum, were isolated and named as Ct1 and Ct0. Anthracnose-resistant germplasm accessions and the Canadian cultivars ‘CDC Robin’, ‘CDC Redberry’ and ‘CDC Viceroy’ were resistant to race Ct1 but susceptible to Ct0. In fact, no genotype resistant to race Ct0 was identified. However, Tullu et al. (2005) observed that species from the secondary gene pool of Lens (several accessions of L. ervoides, Lens lamottei and Lens nigricans) showed high to medium levels of resistance to the anthracnose race Ct0. Tullu et al. (2003) tagged the LCt-2 locus with RAPD markers OPE061250 and UBC704700 in flanking positions at 6.4 cM and 10.5 cM, respectively. Stemphylium blight and powdery mildew These are other locally important diseases of lentil, for which sources of resistance are available (B. Sharma, Delhi, India, unpublished results). However, their inheritance patterns have not been subjected to genetic analysis. Virus resistance Pea seed-borne mosaic virus (PSbMV) is the only prominent disease in lentil, which is transmitted through seed as well as by aphids (Hampton and Muehlbauer, 1977). Four germplasm strains immune to PSbMV were identified by Haddad et al. (1978): PI 212610, 251786, 297745 and 368648. Their crosses with the susceptible varieties ‘Tekoa’ and ‘Precoz’ segregated into 3 susceptible:1 immune ratio in the F2. Monogenic inheritance and the recessive nature of viral immunity were confirmed in all four crosses. The gene symbol sbv was proposed to denote the PSbMV resistance in lentil.

Allozyme variation Allozyme variations had been the markers of choice for mapping in lentil (Zamir and Ladizinsky, 1984; Tadmor et al., 1987; Havey and Muehlbauer, 1989; Muehlbauer et al., 1989; Vaillancourt and Slinkard, 1992, 1993; Tahir et al., 1993) before DNA markers became available (Eujayl et al., 1997, 1998a; Rubeena et al., 2003). Short linkage sequences were reported on the basis of linkages among allozymes used in different crosses (Gulati et al., 2002).

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Cytogenetic studies Knowledge of cytological structure helps in planning breeding strategies, particularly in crosses involving allopolyploid species and wild relatives. The possibility of successful hybridization between different Lens species and subspecies has been demonstrated by several studies. Chromosomal behaviour in distant hybridization will be a matter of concern in lentil breeding. Several attempts have been made to define the standard karyotype of lentil but frequently reported contradictory results. The total chromosome length of 39.31 μm was reported in the variety Pant L 639 by Gupta and Singh (1981) and 31.77 μm in Type 36 by Dixit and Dubey (1986b). The total chromatin length varied from 28.2 to 72.3 μm in different microsperma cultivars of L. culinaris ssp. culinaris (Dixit and Dubey, 1986b). Sindhu et al. (1983) reported that the total chromosome length varies from 21.47 μm in L. ervoides to 30.4 μm in L. orientalis. The pooled length of L. culinaris chromosomes was 27.43 μm. The lowest chromatin length of 16.9 μm was reported by Lavania and Lavania (1983). It has also been demonstrated that L. orientalis and L. culinaris contain higher amounts of DNA in their genomes than L. ervoides. This observation corresponds with their chromatin length. The chromosome structure has also been shown to vary in different species and among genotypes of the same species. According to Sindhu et al. (1983), the chromosome complement in the somatic tissues of L. culinaris, L. orientalis and L. nigricans includes three sub-metacentric (one of them with a secondary constriction), one metacentric and three acrocentric chromosome pairs. This can be taken as the most widespread karyotype of lentil. However, there are several variations. Lens ervoides has four submetacentric chromosomes (one of which is satellited) and three acrocentric chromosomes. The variety Pant L 639 carries four metacentric, three submetacentric and no acrocentric chromosomes (Gupta and Singh, 1981) while L. ervoides has three acrocentric and four sub-metracentric chromosomes (Sindhu et al., 1983). Metacentric chromosomes are absent in L. ervoides. At the other extreme was variety Lens 3847 in which all the seven chromosomes are sub-metacentric (Lavania and Lavania, 1983). All three types of chromosomes (three acrocentric, one metacentric, three sub-metacentric) are present in L. culinaris (Sindhu et al., 1983). The secondary constriction is located on the fifth chromosome of L. ervoides and on the fourth chromosome of other species (Gupta and Singh, 1981). However, inconsistent reports have appeared about the number of satellited chromosomes in cultivated lentil. One satellited chromosome was reported by Bhattacharjee (1951), Sharma and Mukhopadhyaya (1962) and Sinha and Acharya (1974) but no satellited chromosome was found in germplasm accessions carrying EC (i.e. exotic collection) numbers (Sinha and Acharya, 1974), and the varieties Pant L 639 (Gupta and Singh, 1981) and Type 36 (Dixit and Dubey, 1986b) of Indian origin. In conclusion, it seems difficult to define a standard karyotype for Lens species, subspecies and further lower taxa. There could be karyotypic groups, which need to be identified.

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Two cytological aberrations in the form of chromosomal breaks have been identified and the break points were successfully used as markers in gene mapping (Tahir et al., 1993). Chromosomal interchanges have been reported in lentil and mapped (Tadmor et al., 1987; Gupta et al., 1999). Gupta et al. (1985) identified a spontaneous trisomic in the progeny of an interchange heterozygote. A triploid plant of lentil was described by Gupta et al. (1984). Tetraploids were created experimentally by Gupta and Singh (1982). Chromosomal eliminations and translocations lead to distorted segregation ratios in crosses of ssp. odemensis with other subspecies (Vaillancourt and Slinkard, 1992). Goshen et al. (1982) identified three reciprocal translocations in ssp. culinaris × ssp. odemensis crosses. The progenies of intersubspecific hybrids frequently have more abnormal segregation than intraspecific crosses.

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Sharma, S.K. and Sharma, B. (1980b) Induced mutations of physiological nature in lentil. Indian Journal of Genetics and Plant Breeding 40(1), 290–294. Sharma, S.K. and Sharma, B. (1981a) Induced chlorophyll mutations in lentil. Indian Journal of Genetics and Plant Breeding 41(3), 328–333. Sharma, S.K. and Sharma, B. (1981b) NMU induced dwarf mutations in lentil (Lens culinaris Medic.). Science and Culture 47(6), 230–232. Sharma, S.K. and Sharma, B. (1982) Induced early mutations in large seeded lentil. Indian Journal of Agricultural Research 16(2), 79–82. Sindhu, J.S., Slinkard, A.E. and Scoles, G.J. (1983) Studies on variation in Lens. I. Karyotype. Lentil Experimental News Service 10(1), 14. Singh, B.B., Mai-Kodomi, Y. and Terao, T. (1999) A simple screening method for drought tolerance in cowpea. Indian Journal of Genetics and Plant Breeding 9(2), 211–220. Singh, J.P. and Singh, I.S. (1990) Genetics of rust resistance in lentil (Lens culinaris). Indian Journal of Pulses Research 3(2), 132–135. Singh, J.P. and Singh, I.S. (1992) Genetics of rust resistance in lentil (Lens culinaris). Indian Journal of Agricultural Science 62, 337–338. Singh, J.P. and Singh, I.S. (1993) Genetics of seed coat colour in lentil. Euphytica 66, 231–233. Singh, K. and Sandhu, T.S. (1988) Screening of cultivars of lentil for resistance to rust (Uromyces fabae (Pers.) de Bary). Indian Journal of Pulses Research 8, 67–68. Singh, T.P. (1978) Inheritance of cotyledon colour in lentil. Indian Journal of Genetics and Plant Breeding 38(1), 11–12. Sinha, R.P. and Yadav, B.P. (1989) Inheritance of resistance to rust in lentil. Lens Newsletter 16, 41. Sinha, R.P., Chaudhary, S.K. and Sharma, R.N. (1987) Inheritance of cotyledon colour in lentil. LENS Newsletter 14(1/2), 3. Sinha, S.S.N. and Acharya, S.S. (1974) Karyotype analysis in some varieties of Lens culinaris. Cytologia 37, 673–685. Slinkard, A.E. (1978) Inheritance of cotyledon colour in lentils. Journal of Heredity 69, 139–140. Solanki, I.S. (1991) Induction and early generation selection of polygenic mutations in lentil (Lens culinaris Medik.). PhD thesis, Division of Genetics, Indian Agricultural Research Institute, New Delhi, India. Solanki, I.S. and Sharma, B. (2000) Significance and effectiveness of classifying the M1 material based on mutagenic damage for inducing macro and micromutations in lentil (Lens culinaris Medik.). Journal of Genetics and Breeding 54(2), 149–155. Solanki, I.S. and Sharma, B. (2005) Induction and isolation of macromutations in different groups of mutagenic damage in lentil (Lens culinaris Medik.). Journal of Lentil Research 2, 34–38. Spaeth, S.C. and Muehlbauer, F.J. (1991) Registration of three germplasms of winter hardy lentil. Crop Science 31(5), 1395. Srivastava, S.P., Bhandari, T.M.S., Yadav, C.R., Joshi, M. and Erskine, W. (2000) Boron deficiency in lentil: yield loss and geographic distribution in a germplasm collection. Plant and Soil 219, 147–151. Summerfield, R.J., Roberts, E.H., Erskine, W. and Ellis, R.H. (1985) Effect of temperature and photoperiod on flowering in lentils (Lens culinaris). Annals of Botany 56, 659–671. Tadmor, Y., Zamir, D. and Ladizinsky, G. (1987) Genetic mapping of an ancient translocation in the genus Lens. Theoretical and Applied Genetics 73, 883–892.

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B. Sharma Tahir, M. and Muehlbauer, F.J. (1994) Gene mapping in lentil with recombinant inbred lines. Journal of Heredity 85(4), 306–310. Tahir, M., Simon, C.J. and Muehlbauer, F.J. (1993) Gene map of lentil: a review. LENS Newsletter 20(2), 3–10. Tahir, M., Muehlbauer, F.J. and Spaeth, S.C. (1994) Association of isozyme markers with quantitative trait loci in random single seed descent derived lines of lentil (Lens culinaris Medik.). Euphytica 75, 111–119. Tay, J. and Slinkard, A.E. (1989) Transgressive segregation for Ascochyta resistance in lentil. Canadian Journal of Plant Sciences 69, 547. Tirdea, G. and Mancas (1986) Study of the amino acid content of some varieties and mutant lines of lentil (Lens esculenta Moench). Agronomie 28, 67–69. Tivoli, B., Baranger, A., Avila, C.M., Banniza, S., Barbetti, M., Chen, W., Davidson, J., Lindeck, K., Kharrat, M., Rubiales, D., Sadiki, M., Sillero, J.C., Sweetingham, M. and Muehlbauer, F.J. (2006) Screening techniques and sources of resistance to foliar diseases caused by major necrotrophic fungi in grain legumes. Euphytica. Special Issue: Resistance to Biotic and Abiotic Stresses in Legumes 147(1–2), 223–253. Tripathi, A. and Dubey, D.K. (1992) Frequency and spectrum of mutations induced by separate and simultaneous application of gamma rays and ethyl methane sulphonate (EMS) in two microsperma varieties of lentil. LENS Newsletter 19(1), 3–8. Tschermak-Seysenegg, E. (1928) Lentil and field bean crosses. Sityringsber Akademy Wissenschaft Wein Mathematics Natural Kl. I, Abt. 137, 171–181. Tullu, A., Buchwaldt, L., Warkentin, T., Tar’an, B. and Vandenberg, A. (2003) Genetics of resistance to anthracnose and identification of AFLP and RAPD markers linked to the resistance gene in PI 320937 germplasm of lentil (Lens culinaris Medikus). Theoretical and Applied Genetics 106(3), 428–434. Tullu, A., Buchwaldt, L., Lulsdorf, M., Banniza, S., Bartlow, B., Slinkard, A.E., Sarker, A., Tar’an, B., Warkentin, T. and Vandenberg, A. (2005) Sources of resistance to anthracnose (Colletotricum truncatum) in wild Lens species. Genetic Research and Crop Evolution 51(2), 111–120. Tyagi, B.S. and Gupta, P.K. (1991) Induced mutations for fasciation in lentil (Lens culinaris Med.). Indian Journal of Genetics and Plant Breeding 51, 326–331. Tyagi, M.C. and Sharma, B. (1989) Transgressive segregation for early flowering through conventional breeding in lentil. LENS Newsletter 16(1), 3–6. Tyagi, M.C. and Sharma, B. (1995) Protein content in lentil (Lens culinaris Medik.). In: Sharma, B., Kulshreshtha, V.P., Gupta, N. and Mishra, S.K. (eds) Genetic Research and Education: Current Trends and the Next Fifty Years. Indian Society of Genetics and Plant Breeding, New Delhi, India, pp. 1031–1034. Vaillancourt, R.E. and Slinkard, A.E. (1992) Inheritance of new genetic markers in lentil (Lens Miller). Euphytica 64, 227–236. Vaillancourt, R.E. and Slinkard, A.E. (1993) Linkage of morphological and isozyme loci in lentil. Canadian Journal of Plant Science 73, 917–926. Vaillancourt, C.E., Slinkard, A.E. and Reichert, R.D. (1986) The inheritance of condensed tannin concentration in lentil. Canadian Journal of Plant Science 66, 241–246. Vandana, Tripathi, A. and Dubey, D.K. (1999) Frequency and spectrum of mutations induced by ethyl methane sulphonate (EMS) and diethyl sulphate (DES) in lentil var. K 85. LENS Newsletter 21(1), 16–19. Vandenberg, A. (1987) Inheritance and linkage of several qualitative traits in lentil. PhD thesis, University of Saskatchewan, Saskatoon, Saskatchewan, Canada. Vandenberg, A. and Slinkard, A.E. (1987) Inheritance of a xantha chlorophyll deficiency in lentil. Journal of Heredity 78, 130.

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Vandenberg, A. and Slinkard, A.E. (1989) Inheritance of four new qualitative genes in lentil. Journal of Heredity 80, 320–322. Vandenberg, A. and Slinkard, A.E. (1990) Genetics of seed coat colour and pattern in lentil. Journal of Heredity 81, 484–488. Watson, C.A., McNeal, F.F. and Bregs, M.A. (1965) Evaluation of quality potential of foreign wheats for breeding programme. Cereal Science Today 11, 157. Weeden, N.F., Muehlbauer, F.J. and Ladizinsky, G. (1992) Extensive conservation of linkage relationships between pea and lentil genetic maps. Journal of Heredity 83, 123–129. Wilson, V.E. and Hudson, L.W. (1978) Inheritance of lentil flower colour. Journal of Heredity 69, 129–130. Wilson, V.E., Law, L.W. and Warner, R.L. (1970) Inheritance of cotyledon colour in Lens culinaris (Medik.). Crop Science 10, 205–207. Yau, S.K. and Erskine, W. (2000) Diversity of boron toxicity tolerance in lentil growth and yield. Genetic Resources and Crop Evolution 47, 53–61. Zamir, D. and Ladizinsky, G. (1984) Genetics of allozyme variants and linkage groups in lentil. Euphytica 33, 329–336.

8

Genetic Enhancement for Yield and Yield Stability

A. Sarker,1 A. Aydogan,2 S. Chandra,3 M. Kharrat4 and S. Sabaghpour5 1International

Center for Agriculture Research in the Dry Areas (ICARDA), Aleppo, Syria; 2Central Research Institute for Field Crops (CRIFC), Ankara, Turkey; 3Indian Institute of Pulses Research (IIPR), Kanpur, Uttar Pradesh, India; 4National Institute for Agronomic Research (INRAT), Tunis, Tunisia; 5Dryland Agricultural Research Institute, Kermenshah, Iran

8.1. Introduction Lentil (Lens culinaris Medikus subsp. culinaris) is one of the ancient crops of world agriculture as evident from its occurrence in archaeological excavations. Cultivated lentil originated from L. culinaris Medikus subsp. orientalis in the Near East arc and Asia Minor, and considerable diversity in forms and morphological variants are available in these areas (Zohary, 1972; Zohary and Hopf, 1973; Williams et al., 1974; Ladizinsky, 1979). It is a self-pollinated, annual diploid (2n = 2x = 14) species, is a short, slender annual legume that was among early-domesticates in the Fertile Crescent of the Near East. Since domestication, lentil has become an important staple pulse crop traditionally grown in West Asia, the Indian subcontinent, East and North Africa, and to a lesser extent, in Central Asia, the Caucasus and southern Europe. In the recent past, lentil is also cultivated in South and North America and in Oceania. It plays an important role in human and animal nutrition and in soil health improvement. Its cultivation enriches soil nutrient status by adding nitrogen, carbon and organic matter, which promotes sustainable crop production systems. Lentil is one of the important pulses for crop intensification in West and Central Asia, and diversification in South Asia (Sarker et al., 2004b). Lentil seed is a rich source of protein, minerals (K, P, Fe, Zn) and vitamins for human nutrition (Bhatty, 1988; Savage, 1988), and the straw is a valued animal feed (Erskine et al., 1990a). Furthermore, because of its high lysine and tryptophan content, its consumption with wheat/rice provides a balance of essential amino acids for human nutrition. Lentil is predominantly eaten in the Indian subcontinent as boiled or fried dal. It has a consistency like soup and is usually eaten with unleavened bread (roti). Boiled 102

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rice is also served as a staple with lentil dal. Khichri is made from a mixture of splitted/dehulled lentil and cracked wheat or rice. In West Asia and North Africa, Mujaddarah, made of whole lentil and immature wheat seed, is a popular dish. Of course, lentil soup is popular all over. Also, lentil may be deep-fried and eaten as snack, or combined with cereal flour in the preparation of such foods as bread and cake. Lentil, like other pulse crops, provides nutritional security to low-income consumers in many developing countries. Because of its multifaceted importance, various national programmes and the International Center for Agricultural Research in the Dry Areas (ICARDA) are engaged in research and development to improve yield through improved agronomic practices and genetic enhancement. World lentil production has tripled from 1.1 million t in 1971 to 3.84 million t in 2006, and this has been accompanied by increased yields from 611 to 898 kg/ha, respectively (FAO, 2007). Three top-ranking countries, namely, India, Canada and Turkey have increased their productivity and production. Although the area planted to lentil in Turkey has declined in recent years, lentil area has increased greatly in India, Canada, Australia and Ethiopia. However, area expansion and productivity has increased in the developed world most particularly in Canada and the USA, compared to the traditional lentil-growing countries.

8.2. Historical Perspectives The domestication of lentil occurred, together with that of emmer and einkorn wheat, barley, pea, chickpea, bitter vetch and flax, during the Neolithic Agricultural Revolution, which is thought to have taken place in the eastern Mediterranean around the 8th and 7th millennia bc (Zohary and Hopf, 1973). Lentil spread rapidly with that of Neolithic agriculture to the Nile Valley, Europe and Central Asia. It was part of the Harappan crop assemblage in the Indian subcontinent between 2250 and 1750 bc (Zohary and Hopf, 1993). After 1500 ad, the Spanish introduced lentil to South America via Chile (Solh and Erskine, 1984). More recently it has been cultivated in Mexico, Canada, the USA, New Zealand and Australia. Although lentil was cultivated as early as 8000 bc in the Middle East (Hansen and Renfrew, 1978), it remained an under-exploited and underresearched crop until recently. Systematic research for its improvement started at some national institutions and at ICARDA, Syria, during the last three decades. Under the Consultative Group of International Agricultural Research (CGIAR), ICARDA has the world mandate for lentil improvement. The lentil improvement programme at ICARDA is closely linked with the national agricultural research systems and with advanced research institutes in the world to address this mission. The breeding objectives at ICARDA and in national programmes are targeted to yield improvement and its stability and to address specific needs of various agroecological regions. A world collection of wild and cultivated lentil germplasm is maintained at ICARDA and has been instrumental in

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the development of improved genetic stocks suitable to different environmental niches. Except for a few traits, sufficient variability for important economic characters including stress resistance is present in the germplasm for use in breeding programmes. Following a bulk-pedigree method, the lentil breeding programme at ICARDA constructs new genotypes to deliver to the national programmes through the International Nursery Network.

8.3. Constraints to Production Addressable by Breeding Average lentil yields are low because of the limited yield potential of landraces, which are also vulnerable to an array of stresses. The yield limiting factors are lack of seedling vigour, slow leaf area development, high rate of flower drop, low pod setting, poor dry matter, low harvest index, lack of lodging resistance, low or no response to inputs, and various biotic and abiotic stresses. The major abiotic limiting factors to lentil production are low moisture availability and high temperature stress in spring, and, at high elevations, cold temperatures in winter. Mineral imbalances like boron, iron, salinity and sodicity though localized do cause substantial yield loss. Among biotic stresses, rust, vascular wilt and Ascochyta blight diseases caused by Uromyces viciaefabae (Pers.) Schroet., Fusarium oxysporum f. sp. lentis Schlecht and Ascochyta fabae Speg. f. sp. lentis, respectively, are globally important fungal pathogens of lentil (Agarwal et al., 1993; Bayaa and Erskine, 1998). Other diseases such as Botrytis blight (Botrytis cinerea Pers.), Stemphylium blight (Stemphylium botryosum Wallr.), collar rot (Sclerotium rolfsii Sacc.), root rot (Rhizoctonia solani Kuhn) and stem rot (Sclerotinia sclerotiorum (Lib.) de Bary) appear locally, but cause substantial yield loss (Sarker et al., 2004a). Additional constraints to production include agronomic problems of pod dehiscence and lodging, and inadequate crop management practices by growers. Adequate variability for many of the important traits exists within the crop gene pool allowing manipulation through plant breeding. However, several other important traits, such as biomass yield, pod shedding, nitrogen fixation and aphids, and the parasitic broomrape (Orobanche sp.) are not currently addressable by breeding because of insufficient genetic variation within cultivated germplasm and crossable wild species.

8.4. Genetic Resources and Variation in Key Traits The international lentil breeding programme is built upon the foundation of the germplasm collections and their efficient use. A large number of germplasm accessions are maintained at ICARDA; the National Bureau of Plant Genetic Resources, India; the Vavilov Institute of Plant Industry, Russia; and at the United States Department of Agriculture (USDA), USA. The ICARDA collection is by far the largest and comprises 10,282 cultivated accessions from 72 countries and 583 wild species accessions from 24 countries. Among cultivated species conserved at ICARDA, c.17% are breeding lines, developed at ICARDA through cross breeding.

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Marked variation among the characters for use in breeding and selection programmes has been reported for various morphological characters (Sindhu and Mishra, 1982; Erskine and Witcombe, 1984; Erskine et al., 1989; Ramgiry et al., 1989), responses in flowering to temperature and photoperiod (Summerfield et al., 1985; Erskine et al., 1990b, 1994a), winter hardiness (Erskine et al., 1981; Sarker and Erskine, 2006), iron-deficiency chlorosis (Erskine et al., 1993), boron imbalances (Srivastava et al., 2000; Yau and Erskine, 2000) and drought tolerance (Hamdi et al., 1996; Sarker et al., 2001). Germplasm and new breeding lines resistant to fungal diseases (Bayaa and Erskine, 1998; Sarker et al., 2004a) and viruses (Makkouk et al., 2001) are available at ICARDA. Wild relatives also have shown considerable variability for morphological traits (Robertson and Erskine, 1997), winter hardiness (Hamdi et al., 1996), Fusarium wilt and Ascochyta blight resistance (Bayaa et al., 1994, 1995), anthracnose resistance (Tullu et al., 2005) and susceptibility to Sitona weevil (Mustafa et al., 2008).

8.5. Breeding Strategies and Approaches From the onset of the breeding programme at ICARDA, a multidisciplinary approach involving breeders, plant protectionists, agronomists, postharvest technologists, socio-economists has been followed to develop and transfer improved varieties/technologies to farmers. The improvement programme also follows a decentralized breeding strategy to develop cultivars for shortseason environments of southerly latitude countries and winter-hardy cultivars for the highlands. Among diseases, rust screening is done at hot spots in Bangladesh, India and Ethiopia, and Ascochyta blight evaluation in Pakistan. Recently, the lentil breeding programme has adopted Participatory Varietal Selection (PVS) to enhance adoption of improved varieties as indicated by Witcombe and Joshi (1996). Although over the past two decades a number of lentil cultivars have been released in many countries, their adoption by farmers has been slow for several reasons: poor adaptation to varying environments and vulnerability of pests and diseases, inadequacy of the seed distribution system, lack of extension services and inattention to consumers’ tastes. In this context, it is imperative that farmers are involved in the development of high-yielding lentil cultivars and production technology, right from the start. With their native wisdom, first-hand knowledge of the crop and cropping systems and other local conditions, farmers can be effective collaborators in this endeavour.

8.6. Major Agroecology and Specific Breeding Objectives Knowledge of the patterns of variation in the world germplasm collection is the key to understanding factors affecting lentil adaptation. The geographic distribution of variation of landraces in the world lentil collection for

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morphological characters, temperature and photoperiod effects on flowering, winter hardiness, iron-deficiency chlorosis and boron imbalances collectively illustrate the specificity of adaptation in lentil. Additional information on the specificity of adaptation within the crop has come from collaborative yield trials of common entries evaluated at widely differing locations. Understanding of genotypes and environmental factors, the local constraints to production and consumer requirements of different geographic areas for seed as food and straw as feed, has been a guide to the international breeding programme at ICARDA for developing new genetic materials for a series of separate, but finely geographically-targeted streams, linked closely to national breeding programmes (Robertson and Erskine, 1997). The major target agroecological regions of production of lentil are: (i) South Asia, East Africa and Yemen; (ii) low to medium elevation areas in the Mediterranean; and (iii) the high elevation area of West Asia and North Africa. These regions correspond to the maturity groups of early, medium and late maturity (Table 8.1). Within each of these major regions there are specific target areas. In addition, lentil improvement activities have recently been extended to the Central Asia and the Caucasus (CAC) region where the initial thrust is to study lentil adaptation to the prevailing agroclimatic conditions. For Latin America, large-seed, yellow-cotyledon lentils, suitable for mechanical harvest with resistance to rust and Ascochyta blight are preferred. The lentil breeding programme generally uses parents of diverse origin with known traits with the aim to combine gene(s) that contribute to yield and resistance to major biotic and abiotic stresses. Wide crosses among cultigens are also done by manipulating planting dates and providing 18 h extended light period to the parents to attain synchrony in flowering. In addition, crosses are made to study the inheritance pattern of specific trait(s) and to develop recombinant populations for biotechnological research. More than 250 crosses are commissioned at ICARDA every year. At present the programme uses breeding lines in hybridization, developed through crossing multiple parents, thus allowing recombination of desirable genes in newly constructed genotypes for yield improvement and stability over years and across production zones.

8.7. Breeding Methodologies In the early stages of lentil cultivar development, most of the cultivars released have been derived from pure line selection within heterogeneous landraces (Muehlbauer, 1992). Due to increased efforts in lentil breeding nationally and internationally, new lentil cultivars/genotypes are now being developed through cross breeding. The methods of breeding lentil are similar to those utilized in breeding other self-pollinated crops that include pure line selection or hybridization followed by the bulk method, the pedigree method, the single seed descent, or some modification of these procedures. At ICARDA a bulk-pedigree method is used, where single plant

Region A. South Asia and East Africa

B. Mediterranean low to medium elevation

Key traits for recombination 1. India, Pakistan, Nepal and Ethiopia 2. Bangladesh 3. Yemen 1. 300–400 mm annual rainfall 2. <300 mm annual rainfall 3. Morocco 4. Egypt

C. High elevation D. Central Asia and the Caucasus E. Latin America

1. Anatolian highlands 2. North African highlands

Seed yield, early maturity, resistance to root diseases, rust and Ascochyta blight Seed yield, extra-earliness and combined resistance to rust and Stemphylium blight diseases Early maturity, Ascochyta blight resistance Biomass (seed + straw), attributes for mechanical harvest and wilt resistance Biomass, drought escape through earliness and wilt resistance Biomass, attributes for mechanical harvest and combined resistance to rust, Ascochyta blight and wilt Seed yield, response to irrigation, earliness and Fusarium wilt resistance Biomass, winter hardiness and Ascochyta blight resistance Seed yield, low level of winter hardiness and rust resistance Seed yield, large-seed, good standing ability Large-seed, resistance to rust and Ascochyta blight

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Table 8.1. Target agroecological regions of lentil production and key breeding aims.

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selection is done from F4 bulks to develop F5 progeny. A scheme of breeding methodology followed at ICARDA is shown below. Hybridization (Parent A × Parent B): at Tel Hadya, ICARDA HQ (year 1) Conﬁrmation for hybridity (F1) at summer nursery, Lebanon (year 1) F2 bulks grown at Tel Hadya, ICARDA HQ (year 2) F3 grown at summer nursery in Lebanon (year 2) F4 grown at Tel Hadya and single plant selection performed (year 3) F5 families evaluated for agronomic traits and Fusarium wilt reaction in wiltsick plot at Tel Hadya (year 4) F6 progenies are evaluated for yield, agronomic traits and Fusarium wilt at Tel Hadya (year 5) F7 ﬁxed lines are evaluated in preliminary yield trials at three contrasting locations: Breda, Tel Hadya (Syria) and Terbol (Lebanon) F8 advanced yield trials at these three locations except those bred for southerly latitude countries F9 incorporation in international nurseries Mutation breeding programmes are underway at the Bangladesh Institute of Nuclear Agriculture (BINA), Bangladesh; the Indian Agricultural Research Institute (IARI), India; and the National Institute of Agricultural Biology (NIAB), Pakistan. Enormous variability has been created for economic traits. Generally, gamma rays are used to create macromutations and EMS (ethyl methane sulfonate), NEU (nitroso ethyl urea) and SA (sodium azide) are useful to generate micromutations in lentil.

8.8. Breeding Achievements Broadening the genetic base in South Asia About 50% of the world’s lentil is grown in South Asia (FAO, 2007). The region grows only small-seeded red lentil, pilosae type, an endemic group with a narrow genetic variability, short stature and early maturity. For a long time, lentil improvement programmes in South Asia were handicapped due to lack of access to sufficient genetic variability for improvement because of lack of overlap in flowering with introduced lentils. Most materials of West Asian origin, when grown in short-season environments of South Asia, come to flower when the South Asian landraces are maturing (Ceccarelli et al., 1994). This observation prompted research on the environmental factors that control flowering in lentil. Summerfield et al. (1985) concluded that temperature and photoperiod modulate flowering in lentil. In a comprehensive study with a broad spectrum of lentil germplasm, Erskine et al. (1994b) found that germplasm of Indian origin are more sensitive to temperature and less responsive to photoperiod than germplasm from West Asia. To widen the narrow genetic base of lentil in South Asia, in an early attempt, ‘Precoz’, a bold-seeded, early-maturing germplasm of Argentine origin and other early maturing exotic germplasm was introduced from

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ICARDA and utilized in breeding programmes in the region (Erskine et al., 1998). This led to the development of improved cultivars and a yield jump in Bangladesh (‘Barimasur-2’ and ‘Barimasur-4’) (Sarker et al., 1999a, b), Nepal (‘Shekher’ and ‘Shital’) and Pakistan (‘Manshera-98’, ‘Shiraz-96’, ‘Masoor-93’ and ‘Masoor-2002’). ‘Precoz’ when evaluated under both Indian and Syrian environments was shown to have a major gene Sn for early flowering (Sarker et al., 1999c). As a spin-off to research towards broadening the genetic base and based on findings of quantitative responses to photothermal effects, Summerfield et al. (1985) proposed a model for flowering in lentil. According to the model, rates of progress towards flowering (i.e. 1/f, the reciprocal of the time to first flower, f in all genotypes vernalized or not) were linear functions of both mean temperature, t, and photoperiod, p, with no interactions between the two terms. So, over a wide range of conditions covering the photothermal regimes experienced by the lentil crop worldwide, time to flowering was described by the equation: 1/f = a + bt + cp where a, b and c are constants which differ between genotypes and the value of which provide a sound basis for screening germplasm for sensitivity to temperature and photoperiod. Although these two environmental factors affect the same phenological event, Summerfield et al. (1985) suggested that the responses are under separate genetic control.

Identification and exploitation of resistance to abiotic stresses Winter hardiness In the highlands of central Anatolia of Turkey, Iran, Afghanistan and Baluchistan province of Pakistan, lentil production can be increased significantly by shifting sowing from spring to early spring or winter planting. The winter crop allows optimum vegetative growth and higher water use efficiency which leads to higher yield. There is a potential to replace about 400,000 ha of spring lentil with a winter lentil in the highlands of West Asia (Sakar et al., 1988). Spring-sown lentils in the highlands frequently suffer from terminal drought, which can be avoided by early sowing; this also allows taller canopy development suitable for machine harvest. Cultivars with winter hardiness (such as ‘Kafkas’, ‘Cifci’ and ‘Uzbek’) are now being cultivated in Turkey. Several additional lines are identified for future release (LC 9978057, LC 9977006, LC 9977116, LC 9978013, ILL 759, ILL 1878, ILL 4400, ILL 7155, ILL 8146, ILL 8611 and ILL 9832). In Iran lines with winter hardiness, early growth vigour and rapid ground cover (ILL 662, ILL 857, ILL 975, ILL 1878) are under on-farm evaluation. Selection at the Arid Zone Research Center, Baluchistan, Pakistan resulted in the release of cultivar ‘ShirAZ-96’, based on ICARDA germplasm for winter cultivation (Sarker and Erskine, 2006).

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The focus in winter/autumn sowing is to translate the research results into production gains on-farm; in this regard weed control is critical. Production increases from early sowing are only possible in combination with winter hardiness of the cultivars. Drought tolerance Tolerance to moisture stress is a key trait in rain-fed lentil production. Drought is the major abiotic stress in many countries of the world (Johansen et al., 1994). In the Mediterranean environment of West Asia and North Africa, lentil generally suffers from terminal drought (Sarker et al., 2001). In South Asia, the crop is grown on conserved soil moisture, and occasionally faces intermittent drought. Drought-tolerance research, particularly development of screening techniques for the identification of drought-tolerant genotypes, became a key research issue in ICARDA’s crop improvement strategy (Malhotra et al., 2004). Drought-tolerance mechanisms, such as escape, dehydration avoidance and dehydration tolerance have been used to select drought-tolerant genotypes. Traits like early seedling establishment, early growth vigour and rapid ground coverage, high biomass development, early flowering and maturity were taken into consideration to select droughttolerant genotypes. Selection in drought-prone sites (at the Syrian experimental station Breda and farmer’s fields where rainfall <280 mm) is the key to success in identification of drought-tolerant genotypes. Seedling shoot and root traits such as taproot length and lateral root number are important traits for drought tolerance (Sarker et al., 2005). The resulting droughttolerant lines are made available to national programmes through the Lentil International Drought Tolerant Nursery (LIDTN) (Malhotra et al., 2004). Salinity tolerance Soil salinity is a major obstacle to crop production in arid and semi-arid regions of the world. Like other field crops, lentil often suffers from soil salinity. The crop is very sensitive to salinity. Nevertheless, some genetic variation in response to salinity has been reported (Ashraf and Waheed, 1990; Ameen, 1999). Mineral imbalances Soil mineral imbalances sometimes pose a serious threat to lentil production locally. Boron (B) toxicity occurs primarily in some arid areas in alkaline soils and is reported from Australia, India, Pakistan, Iraq, Peru and Turkey. Screening has revealed significant variation in B toxicity with tolerance reported in lentil (Yau and Erskine, 2000). By contrast, B deficiency is a problem in other regions, such as the eastern Terai plain of Nepal, eastern India and northern Bangladesh, where the soil is leached. Landraces from Nepal and Bangladesh were shown to be tolerant to B deficiency, and accessions of West Asian origin were highly inefficient in B-deficient soil (Srivastava et al., 2000). Among B-deficiency tolerant lines, ILL 2580, ILL 5888, ILL

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8009 and ILL 8010 showed higher potential in the B-deficient Chitwan region of Nepal and in the northern region of Bangladesh. Gene mining and utilization to combat biotic stresses Diseases Among biotic stresses, diseases, caused by various fungal pathogens, are the most devastating yield-limiting factors of lentil. Of them, Fusarium wilt, rust and Ascochyta blight are globally important diseases over a wide range of environments and are addressed by the international breeding programme at ICARDA. Screening techniques for these diseases have been developed and sources of resistance have been identified. Fusarium wilt-resistant lines have been identified through rigorous screening in a >15-year-old wilt-sick plot at ICARDA, Tel Hadya. Systematic screening of all new germplasm and breeding lines is carried out. Recently a total of 34 new sources of resistance were identified from 1500 accessions of diverse origin and included in the breeding programme (Sarker et al., 2004a). Rust-resistant lines have been reported from India, Bangladesh and Ethiopia, and some are released as varieties (Agarwal et al., 1993; Bakr, 1993; Bejiga et al., 1998). Lentil accessions with a high level of resistance have been identified for foliar as well as for seed infection of Ascochyta blight and are being used in a breeding programme. Sources of resistance to minor diseases and viruses are also reported (Agarwal et al., 1993; Bakr, 1993; Makkouk et al., 2001; Tullu et al., 2005). Three disease nurseries, namely, the Lentil International Rust Nursery (LIRN), the Lentil International Fusarium Wilt Nursery (LIFWN) and the Lentil International Ascochyta Blight Nursery (LIABN) are made available to national programmes. The next goal is to ensure multiple disease resistance over specific production zones. Construction of suitable plant type for mechanical harvest Lentil production in Australia, Canada and the USA has been completely mechanized since cultivation began. However, the availability of combine harvesters, tall plant stature and large field sizes contrast with the situation in the Mediterranean basin. Lentil cultivation in West Asia and North Africa has been threatened due to rising cost of agricultural labour with hand harvesting accounting for approximately 47% of the total cost of production. Therefore to reduce costs, it is essential that lentil harvest be mechanized. To address this constraint, ICARDA has developed economic machine harvest systems for lentil cultivation involving cultivars with improved standing ability, a flattened seedbed and the use of cutter bars. The Center has developed and promoted with NARS a lentil production package that includes mechanization and the use of improved cultivars with good standing ability. Such cultivars include ‘Idlib-2’, ‘Idlib-3’ and ‘Idlib-4’ in Syria, ‘Hala’

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and ‘Rachayya’ in Lebanon, ‘IPA-98’ in Iraq, ‘Saliana’ and ‘Kef’ in Tunisia, and ‘Firat-87’ and ‘Sayran-96’ in Turkey. On average, mechanical harvesting combined with improved cultivars having good standing ability reduces harvest costs by 17–20% (ICARDA, 2001). Development of micronutrient-dense cultivars Currently, there has been interest at national and international levels to enhance the nutrient content in our food. One approach is to develop nutrient-dense cultivars in staple foods. In this endeavour, the first step is to characterize the genetic diversity for nutrient content that exists in current cultivars and genotypes, and use this information in breeding. In preliminary screening of 1645 lentil accessions comprised of breeding lines, landraces and released cultivars, iron (Fe) content varied from 41 to 132 mg/ kg and zinc (Zn) content ranged from 22 to 78 mg/kg, which suggest scope of improvement in these traits through plant breeding (ICARDA, 2007). Some of the identified cultivars are under ‘fast-tracking’ to disseminate to farmers in Ethiopia, Bangladesh, Nepal, Syria, Turkey, Portugal and Morocco (Table 8.2). The most commonly grown improved cultivars are also being crossed with micronutrient-dense accessions to enrich the cultivars with higher micronutrients. The high content lines are being delivered to national programmes through the International Nursery Network. High content × high content lines are being crossed to develop transgressive segregants with even higher contents. For example, parents with an Fe content >80 mg/kg are being used to develop cultivars with an Fe content of >120 mg/kg. Similarly, high Zn content accessions are included in a crossing programme to develop cultivars with >85 mg/kg of Zn. Nutrient-dense lentil cultivars could provide marketing opportunities for producers, thereby increasing sales. An additional benefit to farmers is that under some soil conditions (e.g. low mineral availability), nutrient-dense cultivars have the potential to improve seedling establishment and resistance to certain diseases. Varietal releases by national programmes As we stated earlier, ICARDA supplies national breeding programmes through the International Nursery Network with a range of genetically fixed materials and segregating populations. These are for use in selection programmes according to the national programme’s specific needs. On the basis of yield, phenological adaptation, agronomically desirable traits, resistance to prevailing stresses, quality aspects, farmers’ and consumers’ preference, etc., national scientists identify and select promising lines/single plants for further evaluation and eventual release for commercial cultivation. In this endeavor, to date 104 lentil cultivars have been registered by 31 countries emanating from ICARDA-supplied genetic materials for high yield, disease resistance, drought tolerance, suitability to harvest mechanization and seed traits (Table 8.3).

Cultivars with high concentration of Fe and Zn.

Cultivar

Country

‘Alemaya’ ‘Idlib-2’ ‘Idlib-3’ ‘Idlib-4’ ‘Barimasur-4’ ‘Barimasur-5’ ‘Barimasur-6’ ‘Abda’

Ethiopia Syria Syria Syria Bangladesh Bangladesh Bangladesh Morocco

Fe (mg/kg)

Zn (mg/kg)

82.3 73.2 72.3 68.5 86.2 86.0 85.2 69.7

66.0 52.3 51.2 62.4 51.1 59.0 66.1 56.3

Cultivar

Country

Fe (mg/kg)

‘Meyveci-2001’ ‘Beleza’ ‘Shital’ ‘Shekhar’ ‘Khajurah-1’ ‘Khajurah-2’ ‘Sisir’ ‘Alemaya’

Turkey Portugal Nepal Nepal Nepal Nepal Nepal Ethiopia

64.5 74.0 75.7 83.4 78.8 100.7 98.0 82.0

Zn (mg/kg) 53.4 56.6 59.0 56.0 58.0 59.0 64.0 66.0

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Table 8.3.

Lentil varieties released by national programmes that emanated from ICARDA-supplied genetic materials.

Region

Country

Asia

Bangladesh, India, Nepal, Pakistan, China, Afghanistan, Iran, Iraq, Syria, Lebanon, Jordan, Yemen, Turkey Ethiopia, Egypt, Morocco, Libya, Tunisia, Algeria, Lesotho, Sudan Argentina, Canada, Ecuador, USA

Africa The Americas Oceania Europe Central Asia and the Caucasus

Australia, New Zealand Portugal Georgia, Uzbekistan, Azerbaijan

No. of varieties 53

30 7 10 2 2

Traits High yield; wilt, rust, Stemphylium blight and Ascochyta blight resistance; better standing ability; high biomass; early maturity; winter hardiness High yield; wilt and rust resistance; early maturity; resistance to lodging; winter hardiness High yield; rust and Ascochyta blight resistance; good standing ability High yield; Ascochyta blight resistance; erect canopy High yield; erect; large seed; tall High yield; large seed; tall

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20 18 16 14 Variety

12 10

13

6

11 9

4

0

10

9 7

6 2

18

17

8

3 1

0

Landrace Crosses Landrace Crosses Landrace Crosses Landrace Crosses Landrace Crosses Landrace Crosses 1980–1984

1985–1989

1990–1994

1995–1999

2000–2004

2005–2007

Year of release

Fig. 8.1. Trend of cultivar releases from landraces and cross breeding.

Of these, 44 varieties were directly released from germplasm in the early phase of lentil improvement and 60 cultivars have been released from breeding lines in the recent past. There is a clear trend of increasing development of new cultivars through cross breeding (Fig. 8.1). The breeding lines were developed involving multiple parents of diverse origin. A yield potential up to 3.42 t/ha has been observed from large plot trials in Ethiopia. Cultivars developed through hybridization have wide adaptation and stable yields as a result of the buffering effect of genes aggregated from diverse multiple parents.

8.9. Evolution of the International Breeding Programme The lentil breeding strategy at ICARDA has changed with time. Initially, in Stage 1, variation in the germplasm collection was directly exploited. Selection was made among and within locally adapted landraces. These selections were distributed to national programmes through the International Nursery Network to test for local adaptation. As a result many cultivars released by national programmes are actually selections from landraces in the ICARDA germplasm collection (Robertson et al., 1996). These Stage-1 registrations emphasize first the value of direct exploitation of landraces and secondly the under-exploited nature of lentil germplasm. The particular combinations of characters required for specific regions were often not found ‘on the shelf’ in the germplasm collection. Consequently,

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ICARDA started hybridization and selection from segregating populations from crosses made at ICARDA to produce fixed lines as Stage 2 material. Such selections were then distributed after multiplication to the national programmes for selection in their respective agroclimatic zones. This has resulted in the release of a number of cultivars in different regions. However, lentil lines developed from selection at ICARDA in West Asia are mostly limited to adaptation to the home region. As a result, the breeding programme has decentralized to work closely with national programmes. For the other regions, at Stage 3, crosses are agreed upon with national cooperators and made at ICARDA, Tel Hadya, Syria and then country-specific segregating populations shipped to national cooperators for local selection and release as cultivars. Approximately 250 such crosses are made annually at ICARDA. Selections made by national programmes are then fed back into the International Nursery Network for wider distribution. In Stage 4, the national programmes directly use ICARDA-derived material in their own hybridization programme and selections are made locally.

8.10. Future Directions Exciting gains in sustainable production arise from the integration of a change in agronomic practice with a high-yielding new cultivar. Several such prospects exist for lentil and are given below. In South Asia, large areas are left fallow over winter following the harvest of rainy-season paddy rice. Farmers need early-maturing, diseaseresistant varieties with late sowing potential for such situations or when land becomes available for lentil planting after the monsoon floodwater has subsided. When such extra-early maturing cultivars with combined resistance to diseases will be available, the prospect will open of a major expansion of lentil production in the post-rice system in the Indian subcontinent. In some areas around the Mediterranean, such as in south Syria, lentil production has ceased primarily because of severe yield losses caused by Sitona weevil. With the identification of sources of resistance to this insect in wild species, most particularly in L. culinaris ssp. orientalis, it may be possible to construct lentil genotypes resistant to this pest (Mustafa et al., 2008). In the highlands of West Asia, still a vast majority of lentil is currently spring sown. However, adoption and expansion of sowing in winter, coupled with the use of a winter-hardy cultivar will give substantial yield advantages. Although agronomic constraints to winter-sowing lentil in the highlands require further research, substantial yield increase can be expected in the future to augment the area and production in this agroecological zone. Molecular tagging of genes responsible for resistance to biotic and abiotic stresses needs to be done to assist the breeding programme. Further, research on functional genomics to address some of the key problems should be initiated. Development of transgenics for drought tolerance using dreb1A gene (Liu et al., 1998) and to control Orobanche through incorporation

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of the Bar gene (Thompson et al., 1987) and other notorious weeds need to be exploited. In-depth physiological research to meet challenges due to the effect of climate change is warranted to assist breeding programmes.

References Agarwal, S.C., Singh, K. and Lal, S.S. (1993) Plant protection of lentil in India. In: Erskine, W. and Saxena, M.C. (eds) Proceedings of the Seminar on Lentil in South Asia, 11–15 March 1991, New Delhi, India. ICARDA, Aleppo, Syria, pp. 147–165. Ameen, A. (1999) Saline irrigation practices and salt tolerance of lentil varieties. MSc. thesis, Bari, Italy. Ashraf, M. and Waheed, A. (1990) Screening of local/exotic accessions of lentil (Lens culinaris Medic.) for salt tolerance at two growth stages. Plant and Soil 128, 167–176. Bakr, M.A. (1993) Plant protection of lentil in Bangladesh. In: Erskine, W. and Saxena, M.C. (eds) Proceedings of the Seminar on Lentil in South Asia, 11–15 March 1991, New Delhi, India. ICARDA, Aleppo, Syria, pp. 177–186. Bayaa, B. and Erskine, W. (1998) Diseases of lentil. In: Allen, D.J. and Lenne, J.M. (eds) The Pathology of Food and Pasture Legumes. CAB International, Wallingford, Oxon, UK, pp. 423–472. Bayaa, B., Erskine, W. and Hamdi, A. (1994) Response of wild lentil to Ascochyta fabae f. sp. lentis from Syria. Genetic Resources and Crop Evolution 41, 61–65. Bayaa, B., Erskine, W. and Hamdi, A. (1995) Evaluation of a wild lentil collection for resistance to vascular wilt. Genetic Resources and Crop Evolution 42, 231–235. Bejiga, G., Tadesse, N. and Erskine, W. (1998) We fixed rust, now wilt. ICARDA Caravan 9, 12. Bhatty, R.S. (1988) Composition and quality of lentil (Lens culinaris Medik.): a review. Canadian Institute of Food Science and Technology 21(2), 144–160. Ceccarelli, S., Erskine, W., Hamblin, J. and Grando, S. (1994) Genotype by environment interaction and international breeding programs. Experimental Agriculture 30, 177–182. Erskine, W. and Witcombe, J.R. (1984) Lentil Germplasm Catalog. International Center for Agricultural Research in the Dry Areas (ICARDA), Aleppo, Syria. Erskine, W., Myveci, K. and Izgin, N. (1981) Screening a world lentil collection for cold tolerance. LENS Newsletter 8, 5–8. Erskine, W., Adham, Y. and Holly, L. (1989) Geographic distribution of variation in quantitative characters in a world lentil collection. Euphytica 43, 97–103. Erskine, W., Rihawe, S. and Capper, B.S. (1990a) Variation in lentil straw quality. Annals of Feed Science Technology 28, 61–69. Erskine, W., Ellis, R.H., Summerfield, R.J., Roberts, E.H. and Hussain, A. (1990b) Characterization of responses to temperature and photoperiod for time to flowering in a world lentil collection. Theoretical and Applied Genetics 80, 193–199. Erskine, W., Saxena, N.P. and Saxena, M.C. (1993) Iron deficiency in lentil: yield loss and geographic distribution in a germplasm collection. Plant and Soil 151, 249–254. Erskine, W., Hussain, A., Tahir M., Baksh, A., Ellis, R.H., Summerfield, R.J. and Roberts, E.H. (1994a) Field evaluation of a model of photothermal flowering responses in a world lentil collection. Theoretical and Applied Genetics 88, 423–428.

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A. Sarker et al. Erskine, W., Tufail, M., Russell, A., Tyagi, M.C., Rahman, M.M. and Saxena, M.C. (1994b) Current and future strategies in breeding lentil for resistance to biotic and abiotic stresses. Euphytica 73, 127–135. Erskine, W., Chandra, S., Chaudhury, M., Malik, I.A., Sarker, A., Sharma, B., Tufail, M. and Tyagi, M.C. (1998) A bottleneck in lentil: widening the genetic base in South Asia. Euphytica 101, 207–211. Food and Agriculture Organization (FAO) (2007) Production Yearbook. FAO, Rome, Italy. Hamdi, A., Kusmenoglu, I. and Erskine, W. (1996) Sources of winter-hardiness in wild lentil. Genetic Resources and Crop Evolution 43, 63–67. Hansen, J. and Renfrew, J.M. (1978) Palaeolithic-Neolithic seed remains at Franchthi cave, Greece. Nature 271, 349–352. International Center for Agricultural Research in the Dry Areas (ICARDA) (2001) Germplasm Program Annual Report. ICARDA, Aleppo, Syria. International Center for Agricultural Research in the Dry Areas (ICARDA) (2007) Development of Lentil Cultivars with High Concentration of Fe, Zn and b-Carotene. Annual Report for HarvestPlus Challenge Program 2007. ICARDA, Aleppo, Syria, pp. 1–14. Johansen, C., Baldev, B., Brouwer, J.B., Erskine, W., Jermyn, W.A., Li Juan, L., Malik, B.A., Miah, A.A. and Silim, S.N. (1994) Biotic and abiotic stresses constraining productivity of cool season food legumes in Asia, Africa and Oceania. In: Muehlbauer, F.J. and Kaiser, K.J. (eds) Expanding the Production and Use of Cool Season Food Legumes. Kluwer Academic Publishers, Dordrecht, The Netherlands, pp. 175–194. Ladizinsky, G. (1979) The origin of lentil and its wild genepool. Euphytica 28, 179–187. Liu, Q., Kasuga, M., Sakuma, Y., Abe, H., Miura, S., Yamaguchi-Sinozaki, K. and Shinozaki, K. (1998) Two transcription factors, DREB1 and DREB2, with an EREBP/AP2 DNA binding domain separate two cellular signal transduction pathways in drought and low temperature responsive gene expression, respectively in Arabidopsis. Plant Cell 10, 1391–1406. Makkouk, K., Kumari S., Sarker, A. and Erskine, W. (2001) Registration of six lentil germplasm lines with combined resistance to viruses. Crop Science 41, 931–932. Malhotra, R.S., Sarker, A. and Saxena, M.C. (2004) Drought tolerance in chickpea and lentil – present status and future strategies. In: Rao, S.C. and Ryan, J. (eds) Challenges and Strategies for Dryland Agriculture. Crop Science Society of America (CSSA) Special Publication 32. CSSA, Madison, Wisconsin, USA, pp. 257–274. Muehlbauer, F.J. (1992) Use of introduced germplasm in cool-season food legume cultivar development. In: Shands, H.L. and Weisner, L.E. (eds) Use of Plant Introductions in Cultivar Development. Part 2. Crop Science Society of America (CSSA) Special Publication 20. CSSA, Madison, Wisconsin, USA, pp. 49–73. Mustafa, E.-B., Sarker, A., Erskine, W. and Joubi, A. (2008) First sources of resistance to sitona weevil (Sitona crinitus Herbst) in wild Lens species. Genetic Resources and Crop Evolution 55, 1–4. Ramgiry, S.R., Paliwal, K.K., and Tomar, S.K. (1989) Variability and correlations of grain yield and other qualitative characters in lentil. LENS Newsletter 16(1), 19–21. Robertson, L.D. and Erskine, W. (1997) Lentil. In: Fuccillo, D., Sears, L. and Stapliton, P. (eds) Biodiversity in Trust. Conservation and Use of Plant Genetic Resources in Consultative Group of International Agricultural Research (CGIAR) Centers. Cambridge University Press, London, UK, pp. 128–138.

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Robertson, L.D., Singh, K.B., Erskine, W. and El Moneim, A.A.M. (1996) Use of genetic diversity in germplasm collections to improve food and forage legumes for West Asia and North Africa. Genetic Resources and Crop Evolution 43, 447–460. Sakar, D., Durutan, N. and Meyveci, K. (1988) Factors, which limit the productivity of cool season food legumes in Turkey. In: Summerfield, R.J. (ed.) World Crops: Cool Season Food Legumes. Kluwer, Dordrecht, The Netherlands, pp. 137–146. Sarker, A. and Erskine, W. (2006) Recent progress in the ancient lentil. Journal of Agricultural Sciences, Cambridge 144, 1–11. Sarker, A., Erskine, W., Hassan, M.S. and Debnath, N. (1999a) Registration of ‘Barimasur-2’ lentil. Crop Science 39, 875. Sarker, A., Erskine, W., Hassan, M.S., Afzal, M.A. and Murshed, A.N.M.M. (1999b) Registration of ‘Barimasur-4’ lentil. Crop Science 39, 876. Sarker, A., Erskine, W., Sharma, B. and Tyagi, M.C. (1999c) Inheritance and linkage relationships of flowering time and morphological loci in lentil (Lens culinaris Medikus). Journal of Heredity 90, 270–275. Sarker, A., Malhotra, R.S., Erskine, W. and Saxena, M.C. (2001) Drought resistance in chickpea and lentil in Mediterranean environments. In: Proceedings of Legumes in Mediterranean (LEGUMED) Symposium, Rabat, Morocco. AEP-France, Rabat, Morroco, pp. 119–126. Sarker, A., Bayaa, B., El-Hassan, H. and Erskine, W. (2004a) New sources of resistance for Fusarium wilt in lentil (Lens culinaris Medikus subsp. culinaris). Journal of Lentil Research 1, 30–33. Sarker, A., Erskine, W., Bakr, M.A., Rahman, M.M., Yadav, N.K., Ali, A. and Saxena, M.C. (2004b) Role of lentil in human nutrition and crop diversification in Asia region. In: Gowda, C.L.L. and Pande, S. (eds) Role of Legumes in Crop Diversiﬁcation and Poverty Reduction in Asia. Joint Cereal and Legume Asia Network (CLAN) Steering Committee Meeting, 10–12 November 2003, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, Andhra Pradesh, India. ICRISAT, Patancheru, Andhra Pradesh, India, pp. 24–31. Sarker, A., Erskine, W. and Singh, M. (2005) Variation in shoot and root characteristics and their association with drought tolerance in lentil landraces. Genetic Resources and Crop Evolution 52, 87–95. Savage, G.P. (1988) The composition and nutritive value of lentils (Lens culinaris). Nutrition Abstracts and Reviews (Series A) 58, 320–343. Sindhu, J.S. and Mishra, H.O. (1982) Genetic variability in Indian microsperma type lentil. LENS Newsletter 9, 10–11. Solh, M. and Erskine, W. (1984) Genetic resources of lentil. In: Witcombe, J.R. and Erskine, W. (eds) Genetic Resources and their Exploitation – Chickpeas, Faba Beans and Lentils. Martinus Nijhoff/Dr W. Junk Publishers for International Center for Agriculture Research in the Dry Areas (ICARDA) and International Board for Plant Genetic Resources (IBPGR), The Hague, pp. 201–224. Srivastava, S.P., Bhandari, T.M.S., Yadav, C.R., Joshi, M. and Erskine, W. (2000) Boron deficiency in lentil: yield loss and geographic distribution in a germplasm collection. Plant and Soil 219, 147–151. Summerfield, R.J., Roberts, E.H., Erskine, W. and Ellis, R.H. (1985) Effects of temperature and photoperiod on flowering in lentils (Lens culinaris Medic.). Annals of Botany 56, 659–671. Thompson, C.K., Rao, M.N., Tizard, R., Crameri, R., Davies, J.E., Lauwereys, M., and Botterman, J. (1987) Characterization of the herbicide resistance gene bar from Streptomyces hygroscopicus. The European Molecular Biology Organization Journal 6, 2519.

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9

Breeding for Short Season Environments

M. Matiur Rahman,1 Ashutosh Sarker,2 Shiv Kumar,3 Asghar Ali,4 N.K. Yadav5 and M. Lutfor Rahman1 1Bangladesh

Agricultural Research Institute, Gazipur, Bangladesh; 2International Center for Agricultural Research in the Dry Areas (ICARDA), Aleppo, Syria; 3Indian Institute of Pulses Research, Kanpur, India; 4National Agricultural Research Centre, Islamabad, Pakistan; 5National Grain Legumes Research Program, Rampur, Nepal

9.1. Introduction Lentil (Lens culinaris ssp. culinaris Medik.) from South Asia contributes 34% to global production. The crop was introduced to the region from West Asia through Afghanistan around 2000 bc (Cubero, 1981) and is grown extensively under varied agroclimatic conditions. South Asian lentils have limited genetic variation for agromorphological traits (Erskine et al., 1989, 1998; Erskine and Saxena, 1993) and this is an apparent result of a bottleneck during introduction of the germplasm to the region. Natural selection and farmer selection for adaptation and local preferences have had a profound effect on seed traits, pubescence, size of vegetative organs, phenology, plant height and pod shape as well as flowering responses. Lentils from South Asia are exclusively of the pilosae ecotype which is characterized by dense pubescence on vegetative organs (Barulina, 1930) and rudimentary tendrils (Vandenberg and Slinkard, 1989). The main driver behind this differentiation was adaptation to match the prevailing climatic factors, particularly photoperiod and temperature (Erskine et al., 1989). Cultivated lentils have been described as belonging to two seed groups: macrosperma (6–9 mm diameter) and microsperma (2–5 mm). There are strong preferences for small seed types with red cotyledons among consumers in the South Asian countries while preference for the large-seeded lentil with yellow cotyledons is limited to a few pockets in North Pakistan and India. Central India is one region where large-seeded cultivars of microsperma lentil are preferred over small-seeded ones.

9.2. Present Status In South Asia, the lentil is extensively grown in India, Nepal, Bangladesh and Pakistan where 1.83 million ha are cultivated with total production of © CAB International 2009. The Lentil: Botany, Production and Uses (eds W. Erskine et al.)

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1.30 million t and average productivity of 699 kg/ha accounting for 46% of the global area and 34% of global production (see Erskine, Chapter 2 this volume). Although during the past two and a half decades (1980–2006) production has increased in the region, the production increase was 53% during 1981–1991, 23% during 1991–2001 and <2% since the beginning of this century. Analysis of each country for the period 1981–2006 showed that India and Nepal experienced positive growth in area and production of lentil, whereas it was negative in Bangladesh and Pakistan. In Nepal, lentil cultivation has recently been extended in the hill and mountain regions with substantial gain in productivity (Shrestha et al., 2005). Presently, India accounts for 76% and 80% of the total South Asian production and area, respectively, in the region, followed by Nepal (12%, 10%), Bangladesh (9.2%, 7.7%) and Pakistan (1.5%, 2.3%).

9.3. Production Base Lentil is grown in South Asia as a post-rainy season crop mostly under rainfed conditions in areas where scanty rainfall is frequently observed. The lentil crop season is characterized by mild and relatively short winters during the vegetative phase and high temperatures with receding soil moisture during the reproductive phase. As a result, the crop experiences terminal drought and forced maturity. A substantial area of South Asia lentil is grown as the only legume in the winter season in rotation with summer crops such as rice, maize, sorghum, cotton and jute. However, it is also grown as an intercrop with wheat, barley, mustard, linseed, grasspea or field pea. In Bangladesh and the north-eastern states of India and Nepal, lentil is relay cropped with rice in which the lentil seeds are sown in the standing rice crop about 15 days before its harvest under the utera system or immediately after the harvest of rice under the paira system. In both cropping systems, lentil is grown predominantly on residual soil moisture.

9.4. Production Constraints The average yield of lentil in South Asia (699 kg/ha) is 24% lower than the world average (1053 kg/ha) (FAO, 2007). The reasons for low yield are occurrence of various biotic, abiotic and edaphic factors at different growth stages (Ali et al., 2000; Haqqani et al., 2000; Matiur Rahman et al., 2000; Pandey et al., 2000). Being a cool-season crop, lentil is grown on conserved soil moisture in the post-rainy season and generally, no rainfall except occasional scattered showers occur during winter in the region. As a result, soil water deficit during crop establishment and in the post-flowering period emerges as the major yield constraint along with the rising temperature. Salinity and deficiencies of soil nutrients are also observed locally in the region. For example, boron deficiency has been identified as a limiting

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factor in some parts of Nepal. Lentil is also sensitive to zinc and iron deficiency and poor nitrogen fixation. The crop often encounters pod dehiscence and lodging as well under the conditions prevalent in the region. Vascular wilt caused by Fusarium oxysporum Schlect. f. sp. lentis Vasudeva and Srinivasan and rust caused by Uromyces viciae-fabae (Pers.) de Bary are widespread diseases inflicting serious yield losses across the countries. Stemphylium blight caused by Stemphylium botrysum Wallr. in Bangladesh and Nepal, Ascochyta blight (Ascochyta lentis Bond and Vassil) and Botrytis grey mould (Botrytis cinerea Pers. Ex Fr.) in Pakistan, and collar rot (Sclerotium rolfsii Sacc.), root rot (Rhizoctonia solani Kuhn) and stem rot (Sclerotinia sclerotiorum) in India and Nepal are also of economic importance. Among insects, aphid (Aphis craccivora Koch) is an important field pest while bruchids (Bruchus spp. and Callosobruchus spp.) cause serious grain losses during storage. These stresses appear individually and/or in combination with varying intensity depending on the location and year, thus, causing great fluctuation in lentil production in the region. Hence, development of resistant varieties against major diseases and realizing the yield potential of existing commercial cultivars have been given priority in the past while there have been limited efforts towards breaking yield barriers in lentil in South Asia.

9.5. Timing of Flowering The onset of flowering is an important phenological event for the short period of the vegetative phase, and determines the potential of the crop under the climatic conditions to which the crop will be exposed during reproductive growth. The optimum flowering response differs between regions and is simple to measure within a target region (Erskine et al., 1994a). Being a quantitative long day plant, wide genetic variation for flowering response to photoperiod and temperature has been reported in the global germplasm repository at the International Center for Agricultural Research in the Dry Areas (ICARDA) (Erskine et al., 1990). Presently, the understanding of the genetic control of flowering is limited. However, the available results show that early flowering is largely determined by a single recessive gene sn in addition to some polygenes (Sarker et al., 1999). This results in transgressive segregation in the progeny of crosses between early and late flowering parents (Tyagi and Sharma, 1989; B. Sharma, Chapter 7 this volume). Sowing time has a profound effect on flowering pattern, productivity and success of the crop as it causes considerable change in the plant environment with respect to temperature, photoperiod and availability of soil moisture (Ramakrishna et al., 2000). The optimum planting time of lentil in Pakistan, northern India, Nepal and Bangladesh is the last week of October to mid-November depending on the location and soil moisture (Ahad Mia and Matiur Rahman, 1993; Ali et al., 1993; Neupane and Bharati, 1993) while in central India and Pakistan highlands (> _1000m altitude), lentil is planted

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from September to mid-October (Ali et al., 1991, 1993). Delay in planting progressively shortens the growing period as a result of the rapid rise in temperature accompanied by low moisture availability which leads to inadequate biomass production, poor pod filling and forced maturity (Erskine et al., 1994b; Ali et al., 2000). Optimum temperature for lentil growth and development ranges from 15 to 25°C (Clarke et al., 2005). Crop duration is extended by cool weather (Summerfield, 1981). The lentil season in South Asia coincides with a sharp rise in temperature (>30°C) by the end of February in central India, West Bengal, Bangladesh and early April in northern India, Nepal and Pakistan. The rising temperatures coupled with receding soil moisture push the plants into forced maturity. Thus, the crop duration in this region varies from 100 to 140 days depending on location. Therefore, cultivars with high yield potential should have a crop duration of around 100 days in central India, 110 days in Bangladesh and 140 days in the cooler areas of the region.

9.6. History of Improvement Lentil breeding has a relatively short history of organized research as compared to other major crops such as maize and soybean. The earliest record of organized research in South Asia goes back to 1943 when a lentil breeding programme was taken up under the State Department of Agriculture in different provinces of undivided India. This received a further boost with the establishment of the All India Coordinated Pulses Improvement Project in 1967. With the creation of ICARDA in 1977, lentil improvement programmes in South Asian countries received valuable assistance by having access to global germplasm, yield nurseries and basic information. This collaboration has resulted in the development of improved cultivars and widening of the genetic base. Over the years, these countries have established sound lentil breeding programmes. The lentil breeding programme in Nepal began in 1977 and systematic genetic improvement started in 1985 with the establishment of the National Grain Legume Research Program (Bharati and Neupane, 1991). The Bangladesh Agricultural Research Institute (BARI) launched a pulse research programme in 1991. In Pakistan, the National Agricultural Research Centre in Islamabad has major responsibility for lentil improvement. The work initiated in 1981 under the National Coordinated Research Programme on pulses.

9.7. Germplasm Collection of genetic resources in India started in the early 1960s under a Rockefeller Foundation programme which was funded by PL 480 assistance and extended to other South Asian countries in 1977 under the Arid Lands Agricultural Development Program (ALAD). The global lentil germplasm repository of 8748 landrace accessions and 479 wild accessions maintained

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at ICARDA contains 86 accessions from Bangladesh, 2118 from India, 475 from Nepal and 297 from Pakistan (Sarker et al., 2005). Among the national genebanks, India and Bangladesh hold 2238 and 2045 accessions, respectively. In addition, a large number of introductions in the form of exotic lines and yield nurseries have also been accumulated to enrich the local gene pool. About 7533 accessions in India and 2500 in Bangladesh have been introduced through ICARDA. Studies on quantitative agromorphological variation in germplasm from 13 countries revealed that the Indian lentils have limited variation. India and Pakistan lie among the countries with the lowest quantitative agromorphological variation. The group was characterized by early flowering and maturity, low biological yield, short stature, lowest pod height and small seeds (Erskine et al., 1989). Evaluation of 456 germplasm accessions showed large variability in the indigenous collection in India (Table 9.1).

9.8. Breeding Objectives The major target of the current breeding programmes in South Asian countries is to match crop duration with the target environments coupled with resistance to major diseases and improved seed size. Genotypes which mature relatively early are better adapted to variable environments. Thus, short duration cultivars with rapid grain fill may avoid substantial terminal stress (Summerfield, 1981). It is, therefore, essential to breed short duration cultivars combining resistance to key biotic and abiotic stresses (Saxena et al., 2005). Extra earliness combined with resistance to rust and Stemphylium blight is important for the short season environment of Bangladesh and the eastern and central regions of India while genotypes resistant to root diseases and rust are crucial for Nepal and central India. Medium duration cultivars are also widely cultivated in Nepal. Ascochyta blight is Table 9.1.

Mean and range for various traits in Indian lentil germplasm.

Trait Days to 50% ﬂowering Days to maturity Plant height (cm) Primary branches Pod length (cm) Pod width (cm) Pods per peduncle Peduncles per plant Pods per plant Yield per plant (g) 100-grain weight (g) Seeds per pod Seed diameter (mm)

Mean

Minimum

Maximum

127.5 179.6 31.4 2.9 1.1 0.5 2.0 36.7 55.0 12.0 2.90 2.02 0.44

108 154 17 1 0.9 0.4 1 11 14 0.4 1.6 1 0.35

199 202 57 7 1.7 0.9 3 110 180 31.3 8.5 3 0.67

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important in the highlands of north India and Pakistan. Adequate variability for these traits exists within lentil genetic resources allowing for manipulation through breeding (Erskine et al., 1989).

9.9. Breeding Strategy Efficient screening techniques depend on the ability to reproduce the most probable conditions of stress in the target environment (Wery et al., 1994). It requires defining the most frequently occurring stress in the crop cycle and reproducing it in conditions where screening of a large number of genotypes can be made. These two steps are essential for the reproducibility of screening. The next step is to define the plant traits required in the target environment. As mentioned earlier, terminal heat stress is frequently associated with soil moisture deficiency at the reproductive stage. Therefore, germplasm must be planted at the appropriate time at the screening location so as to ensure that the stress coincides with the critical crop stages. Since seed yield is not a reliable criterion for selection under stress conditions (Muehlbauer et al., 1985), it is suggested that indirect selection be practised through selecting traits that have high heritability and that are strongly associated with yield. Although one cannot expect any single trait to determine yield under drought in view of the variability of stress and complexity of yield, early growth vigour has shown strong correlation with biomass and seed yield in lentil and is of practical value in predicting final yield under a short duration environment (Erskine and Saxena, 1993). The early flowering and maturing cultivars of lentil display a typical drought-avoidance strategy at the reproductive stage when high temperature and water deficit induce rapid senescence and early maturity (Erskine et al., 1994a; Shrestha et al., 2006a). For biotic stresses, particularly diseases, field screening at hot spots, as well as pot screening or glasshouse screening under controlled conditions, has been standardized and is being employed for identification of resistant donors (Khare et al., 1993; Gaur and Chaturvedi, 2004) and inheritance studies. Field screening in sick plots of large size has been perfected with remarkable success at ICARDA. Under short-duration rainfed environments, the superior performance of lentil genotypes from South Asia and derivatives from crosses between South and West Asian lentils has been associated with rapid canopy cover, early phenology and high harvest index (Shrestha et al., 2005). Higher grain yield in the derivatives from crosses between the South and West Asian genotypes is attributed to larger seed size introgressed from the West Asian genotypes in the typical short duration background of South Asian genotypes (Shrestha et al., 2006a). Therefore, genotypes with rapid ground cover, early phenology, a prolonged flowering and podding period, leading to increased dry matter production, more pods, high harvest index, efficient water use and large seeds should be selected for the short duration environment of South Asia (Shrestha et al., 2005). Crossing of superior parental lines from the South and West Asian germplasms, early generation selection, and

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evaluation under a range of environments could be the preferred breeding strategy for further improvement towards adaptation and increased yield of this important legume crop in South Asia (Shrestha et al., 2005). As lentils have an indeterminate growth habit, water deficit at the reproductive stage affects both vegetative and reproductive development by reducing leaf area, dry matter production, number of branches and, consequently, the number of flowers, pods and seeds. Under water deficit conditions, the number of pods and seeds and seed size are most important traits related to seed yield in lentil (Shrestha et al., 2006b). Correlations between traits must be given careful consideration and interpretation by plant breeders. Number of pods per plant, seeds per pod, secondary branches per plant, plant height and straw yield are reported to have significant positive correlation with grain yield in lentil (Erskine, 1983; Singh and Singh, 1991; Pandey et al., 1992). Thus, selection for increasing seed yield would not adversely affect straw yield. Muehlbauer et al. (1985) concluded that branching pattern and number of fruits to reach maturity are the most important characters that contribute positively to yield. Therefore, early maturing plants having early growth vigour and a greater number of pods should be selected for short season environments, as they will be able to escape terminal stresses. In South Asia, small-seeded and semi-spreading cultivars are mostly grown under normal and late sown situations, and yields are stable because the plants are able to fill the available space by initiating lateral branches and compensating for poor emergence. Early flowering combined with early growth vigour, large seeds and cold tolerance are some of the desirable attributes of new plant types. For late sown conditions, semi-spreading growth, early maturity and large seeds are important traits (Singh, 1997).

9.10. Creation of Variability The scope of selection for desirable genotypes depends on the extent of exploitable genetic variability. Some of the promising traits in the indigenous gene pool of South Asia are early maturity and more pods per plant and per cluster (Bhag Singh and Rana, 1993). Extreme specificity of adaptation limits the scope of direct introduction of exotic germplasm in the region. Sharma et al. (1993) reported that most of the Indian lentils (microsperma type) are early maturing and the Mediterranean macrosperma lentils are late maturing. Podding potential was higher in small-seeded genotypes than large-seeded ones and smallseeded types have better stability. This variability should be exploited to widen the genetic base through hybridization. A wide range of variation, including transgressive segregation, was obtained both for crop duration and for seed size from a cross between indigenous microsperma and exotic macrosperma (‘Precoz’) types, resulting in selection of extra short duration and erect genotypes (gene Ert) with large seeds and tolerance to key stresses (Sharma et al., 1993; Tufail et al., 1993; Emami and Sharma, 1999). Therefore, introgression of exotic genes from diverse origins into locally adapted cultivars should be the approach for widening the genetic variability.

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9.11. Breeding Methods The methods of breeding lentil are similar to those utilized to breed other self-pollinated crops and include pure line selection, back crossing and hybridization, followed by bulk pedigree, single seed descent or some modification of these selection procedures. The bulk-pedigree method has been the preferred breeding method. Porta-Puglia et al. (1993) described different breeding methodologies for single and multiple stress resistance in coolseason food legumes. They suggested pedigree selection for disease resistance and the bulk-pedigree method for abiotic stresses. ICARDA follows the bulk-pedigree method in which the crosses are advanced as bulks from F2 to F4 and the selected plants are carried forward as plant progenies from F5 onwards. Although many cultivars have been released in South Asia targeting specific traits and environments, not all are suitable for the short duration environment. Therefore, only short duration cultivars released after 1980 (100–140 days) are listed in Table 9.2. So far, seven high-yielding disease-resistant cultivars have been released for cultivation in Bangladesh, 29 in India, five in Nepal and seven in Pakistan.

Pure line selection In the early stages of lentil breeding, most of the cultivars released were derived from selection within the heterogeneous landraces. Most of the expansion in the range of adaptation has resulted from empirical selection of superior performance of individual genotypes in new climate zones. A large number of landraces collected from different regions were evaluated and based on multilocation testing for yield and disease reaction, and superior genotypes with wide adaptability were commercialized. Some of the popular cultivars developed through this method are: L 9-12, T 36, BR 25, C 31, JL 1, Pant L 406, Pant L 639, Lens 830, Lens 4076, B 77, ‘Vipasha’, VL 1, K 75, JL 3 and VL 4 in India; ‘Barimasur 1’ in Bangladesh; ‘Shital’ in Nepal; and ‘Masoor 85’ in Pakistan. Cultivars found popular in one country/region are often introduced and acclimatized in similar conditions prevailing in another country through ICARDA and if found suitable, are released as cultivars. Among the lentil cultivars released through introductions from ICARDA are: ‘Vipasha’ and VL 507 in India; ‘Mansehra 89’ and ‘Shiraz 96’ in Pakistan; and ‘Simal’, ‘Sikhar’, ‘Khajura Masuro 1’ and ‘Khajura Masuro 2’ in Nepal. Recombination breeding Recombination breeding, or the selection–crossing–selection cycle, consists of controlled crossing between parents of choice followed by pedigree selection or its various modifications in the segregating generations for the targeted trait(s). The lentil breeding programmes generally use parents of diverse origin with known traits with the aim to combine genes that contribute to

Country

Cultivar

Year

Pedigree

Days to maturity

100-grain weight (g)

Grain yield (t/ha)

Bangladesh

‘Barimasur 1’ ‘Barimasur 2’ ‘Barimasur 3’ ‘Barimasur 4’ ‘Barimasur 6’ ‘Barimasur 7’ ‘Binamasur 1’ Pant L 234 ‘Asha’ Pant L 639 ‘Ranjan’ LL 56 ‘Malika’ ‘Arun’ LL 147 ‘Sapna’ Jawahar Lentil 1 Pant Lentil 4 Lens 4076 ‘Priya’ ‘Pusa Vaibhav’ ‘Garima’ ‘Narendra Masur 1’ ‘Sheri’ ‘Subrata’

1991 1993 1996 1996 2006 2006 2002 1980 1980 1981 1982 1983 1986 1986 1986 1991 1991 1993 1993 1995 1996 1996 1997 1997 1998

Local selection F3 ICARDA Local cross F3 ICARDA F3 ICARDA F3 ICARDA Mutation Selection from P 230 Selection from Jorhat local L 9-12 × T 8 Mutant of B 77 L 9-12 × L 32-1 Local selection Mutant of BR 25 PL 284-67 × NP 21 L 9-12 × JLS 2 Local selection UPL 175 × (PL 184 × P 285) PL 234 × PL 639 PL 406 × L 4076 (L 3875 × P 4) PKVL 1 ‘Pusa 2’ × NO. 4 ‘Precoz’ × L 9-12 JLS 1 × LG 171 JLS 2 × T 36

110–115 110–115 100–105 115–120 105–110 105–110 125–130 135–140 120–125 140–145 120–125 150–155 130–135 125–130 140–145 135–140 120–125 140–145 130–135 130–135 130–135 135–140 120–130 130–135 120–125

1.5–1.6 1.2–1.3 2.2–2.3 1.7–1.8 1.9–2.0 2.2–2.3 1.5–1.6 2.3 1.5 1.7 1.7 1.9 2.7 2.5 1.8 2.7 2.5 1.7 2.8 2.7 1.8 2.6 2.6 3.4 2.8

1.5–1.8 1.5–2.0 1.7–2.0 2.0–2.2 1.8–2.0 2.0–2.5 1.5–2.0 2.1–2.5 1.7–1.9 2.1–2.3 2.0–2.1 1.6–1.8 2.1–2.4 2.1–2.3 1.9–2.1 2.0–2.3 1.5–1.7 2.1–2.4 2.1–2.3 2.1–2.4 2.3–2.6 2.0–2.2 2.0–2.4 2.3–2.5 1.8–2.1

India

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(Continued)

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Table 9.2. Short duration cultivars released in South Asia.

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Table 9.2. continued

Country

Pakistan

Nepal

Cultivar

Year

Pedigree

Days to maturity

100-grain weight (g)

Grain yield (t/ha)

JL 3 ‘Noori’ KLS 218 HUL 57 IPL 406 ‘Masoor 85’ ‘Mansehra 89’ ‘Masoor 93’ ‘Shiraz 96’ NIAB Masoor 02 Masoor 04 NIAB Masoor 06 ‘Simal’ ‘Sikhar’ ‘Khajura Masuro 1’ ‘Khajura Masuro 2’ ‘Shital’

1999 2000 2005 2005 2007 1985 1989 1993 1996 2002 2004 2006 1989 1989 1999 1999 2004

Local selection K 75 × PL 639 KLS133 × L9362 Mutant of HUL 1 DPL35 × EC157634/382 Local selection ‘Precoz’ 18-12 × ILL 4400 ILL 5865 ‘Precoz’ × ‘Masoor-85’ ICARDA selection Mutant of ILL 2580 LG 7 (ILL 3512) ILL 4404 ILL 3746 (LG 198) Pant L 639 ILL 2580

115–120 110–120 120–125 121 125–130 120–130 90–110 110–120 140–160 90–110 100–120 90–110 140–143 140–143 125–128 130–134 130–133

3.0 2.7 1.9 1.8 3.9 1.8 4.0–5.0 2.5 2.8 2.5–3.0 2.5 2.2 1.4–1.8 1.3–1.6 1.3–1.7 1.4–1.9 1.8–2.0

2.0–2.2 2.1–2.3 1.4–1.6 1.4–1.5 1.7–1.9 1.5–1.7 2.1–2.5 1.9–2.1 1.8–2.2 1.5–1.8 1.9–2.1 1.4–2.1 2.1–2.5 2.5–3.0 1.5–2.0 2.1–2.5 1.8–2.0 M. Matiur Rahman et al.

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yield and resistance to major biotic and abiotic stresses. Crosses between genotypes from South Asia and West Asia which greatly differ in their photoperiod requirements are made either by raising them under long-day conditions during summer in hilly areas or by providing 18 h of extended light to attain synchrony in flowering. The first cultivar emanating from recombination breeding in the region was Pant L 639 in 1981. This was followed by a spate of high-yielding disease-resistant cultivars from such efforts (Table 9.2). However, the genetic base of these cultivars remained narrow as South Asian improvement programmes have not used genes from exotic sources on a wide scale. This bottleneck for lentil improvement in the region has recently been broken (Erskine et al., 1998) with the introduction of exotic early flowering materials into the Indian subcontinent. For example, flowering of ‘Precoz’, an early maturing Argentinean landrace, is well synchronized with the local South Asian germplasm. Studies showed that ‘Precoz’ has a major gene sn for earliness and produces early and extra early transgressive segregants that can fit well in the short growing periods of South Asia (Sarker et al., 1999). ‘Precoz’ has been used extensively to incorporate such traits as large-seed size, disease (mainly rust) resistance and early vigour in the background of locally adapted cultivars since 1985. ‘Precoz’ was first received in India in the 1982/83 cropping season when its extra-earliness among macrosperma lentils was noted. It must be noted that a great majority of macrosperma genotypes received from the western hemisphere are extremely late under the conditions of the Indian subcontinent. Some of them do not flower even after 140 days from sowing when the crop matures under temperature extremes above 40°C. Crosses between ‘Precoz’ and local lentils have resulted in the development of a wide spectrum of extra bold and extra early cultivars in India (NDL 1 and DPL 58) and Pakistan (‘NIAB Masoor 02’).

Mutation breeding Mutation breeding has definite merit for simply inherited traits and where suitable and efficient screening procedures are available to identify economically useful mutants from sufficiently large populations of mutagenized material. There are a few reports of mutation breeding in lentil. Experience with lentil mutagenesis has shown that the macrosperma cultivars are more mutable than the microsperma genotypes. Mutation breeding has been successful in developing lentil cultivars with specific traits. So far, seven mutant cultivars including three cultivars each in India (‘Ranjan’, ‘Arun’ and HUL 57) and Bangladesh (‘Bina Masur 1’, ‘Bina Masur 2’ and ‘Bina Masur 3’) and one in Pakistan (‘NIAB Masoor 2006’) have been reported.

9.12. Future Perspectives The productivity of the present cultivars is quite low and needs to be improved through change in the existing plant type and insulation against

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multiple stresses. Introgression of economically valuable traits through wide crosses holds promise for a number of important traits, particularly tolerance to abiotic and biotic stresses. This requires comprehensive screening of the available germplasm in hot spots and under controlled conditions for directed improvement in lentil. Exciting gains in sustainable production and expansion of the crops to new niches can be made from incorporation of desired traits with changes in agronomic practices. Several such prospects exist for lentil in South Asia. The diseases such as rust, wilt and Ascochyta blight are key problems; however, lentil could be put into production in the large areas that are left fallow during winter after the harvest of late paddy. For this potential use, super-early photo-thermo-insensitive cultivars that can be grown successfully under late sown situations are needed. Once super-early-maturing cultivars with multiple disease resistance are available, a major breakthrough in lentil production in the rice-based cropping systems in the Indian subcontinent could be realized. Until recently, a major limitation to genomics-enabled lentil improvement has been unavailability of locus-specific PCR-based codominant markers and precise mapping and tagging of useful genes (Ford et al., 2007). However, recent developments in simple sequence repeat (SSR) marker technology for lentil at ICARDA (Hamwieh et al., 2005) indicates progress in this area and possibly will lead to further development. Genes for resistance to biotic and abiotic stresses need to be tagged with molecular markers for effective use in breeding. Some of the major genes or quantitative trait loci (QTLs) imparting resistance to Fusarium wilt and Ascochyta blight have been tagged (Eujayl et al., 1998; Ford et al., 1999; Chowdhury et al., 2001). Further research on functional genomics to address some of the key problems should be initiated. This requires availability of appropriate mapping populations, and identification and validation of trait-associated markers across different environments (Ford et al., 2007). On the technological front, lentil needs a major breakthrough in yield levels through morphophysiological changes in plant type, and dissection of abiotic stresses into its components. Lentil germplasm has shown tremendous genetic variation for protein and micronutrient (iron and zinc) contents. This provides scope for biofortification of high-yielding varieties for augmenting nutritional values of the crop.

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Ali, M., Saraf, C.S., Singh, P.P., Rewari, R.B. and Ahlawat, I.P.S. (1993) Agronomy of lentil in India. In: Erskine, W. and Saxena, M.C. (eds) Lentil in South Asia. Proceedings of Seminar on Lentil in South Asia, 11–15 March 1991, New Delhi, India. International Center for Agricultural Research in the Dry Areas (ICARDA), Aleppo, Syria, pp. 103–127. Ali, M., Joshi, P.K., Pande, S., Asokan, M., Virmani, S.M., Ravikumar and Kandpal, B.K. (2000) Legumes in the Indo-Gangetic plain of India. In: Johansen, C., Duxbury, J.M., Virmani, S.M., Gowda, C.L.L., Pande, S. and Joshi, P.K. (eds) Legumes in Rice and Wheat Cropping Systems of the Indo-Gangetic Plain – Constraints and Opportunities. International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, Hyderabad, India and Cornell University, USA, pp. 35–70. Barulina, H. (1930) Lentils of the USSR and other countries. Bulletin of Applied Botany, Genetics and Plant Breeding Supplement 40. USSR Institute of Plant Industry of the Lenin Academy of Agricultural Science Leningrad, USSR, pp. 1–319. Bhag Singh and Rana, R.S. (1993) Genetic resources of lentil in India. In: Erskine, W. and Saxena, M.C. (eds) Lentil in South Asia. Proceedings of Seminar on Lentil in South Asia, 11–15 March 1991, New Delhi, India. International Center for Agricultural Research in the Dry Areas (ICARDA), Aleppo, Syria, pp. 11–21. Bharati, M.P. and Neupane, R.K. (1991) Genetic resources and breeding of lentil in Nepal. In: Erskine, W. and Saxena, M.C. (eds) Lentil in South Asia. Proceedings of Seminar on Lentil in South Asia, 11–15 March 1991, New Delhi, India. International Center for Agricultural Research in the Dry Areas (ICARDA), Aleppo, Syria, pp. 82–91. Chowdhury, M.A., Andrahennaadi, C.P., Slinkard, A.E. and Vandenberg, A. (2001) RAPD and SCAR markers for resistance to ascochyta blight in lentil. Euphytica 118, 331–337. Clarke, H., Khan, T., Croser, J., White, P., Singh, S.P., Lulsdrof, M., Hunbury, C. and Ryan, M. (2005) Temperature tolerance in food legumes. In: Kharkwal, M.C. (ed.) Abstracts of Fourth International Food Legume Research Conference (IFLRC IV), 18–22 October, 2005. New Delhi, India, p. 21. Cubero, J.I. (1981) Origin, taxonomy and domestication. In: Webb, C. and Hawtin, G.C. (eds) Lentils. Commonwealth Agricultural Bureau, Slough, UK, pp. 15–38. Emami, M.K. and Sharma, B. (1999) Linkage between three morphological markers in lentil. Plant Breeding 118(6), 579–581. Erskine, W. (1983) Relationship between the yield of seed and straw in lentil. Field Crops Research 7, 115–121. Erskine, W. and Saxena, M.C. (1993) Problems and prospects for stress resistance breeding in lentil. In: Singh, K.B. and Saxena, M.C. (eds) Breeding for Stress Tolerance in Cool-Season Food Legumes. John Wiley and Sons, Chichester, UK, pp. 51–62. Erskine, W., Adham, Y. and Holly, L. (1989) Geographical distribution of variation in quantitative traits in a world lentil collection. Euphytica 43, 97–103. Erskine, W., Ellis, R.H., Summerfield, R.J., Roberts, E.H. and Hussain, A. (1990) Characterization of responses to temperature and photoperiod for time to flowering in a world lentil collection. Theoretical and Applied Genetics 80, 193–199. Erskine, W., Hussain, A., Tahir, M., Bahksh, A., Ellis, R.H., Summerfield, R.J. and Roberts, E.H. (1994a) Field evaluation of a model of photo-thermal flowering responses in a world lentil collection. Theoretical and Applied Genetics 88, 423–428. Erskine, W., Tufail, M., Russell, A., Tyagi, M.C., Rahman, M.M. and Saxena, M.C. (1994b) Current and future strategy in breeding lentil for resistance to biotic and abiotic stresses. In: Muehlbauer, F.J. and Kaiser, W.J. (eds) Expanding the Production

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M. Matiur Rahman et al. and Use of Cool Season Food Legumes. Proceedings of the Second International Food Legume Research Conference (FLRC II), Cairo, Egypt, 12–16 April, 1992. Kluwer Academic Publishers, Dordrecht, The Netherlands, pp. 559–571. Erskine, W., Chandra, S., Chaudhary, M., Malik, I.A., Sarker, A., Sharma, B., Tufail, M. and Tyagi, M.C. (1998) A bottleneck in lentil: widening its genetic base in South Asia. Euphytica 101, 207–211. Eujayl, I., Erskine, W., Bayya, B., Baum, M. and Pehu, E. (1998) Fusarium vascular wilt in lentil: inheritance and identification of DNA markers for resistance. Plant Breeding 117, 497–499. Food and Agriculture Organization (FAO) (2007) Statistics on Lentil. Available at: www.fao.org/site/336 (accessed on 20 September 2007). Ford, R., Pang, E.C.K. and Taylor, P.W.J. (1999) Genetics of resistance to ascochyta blight (Ascochyta lentis) of lentil and the identification of closely linked RAPD markers. Theoretical and Applied Genetics 98, 93–98. Ford, R., Rubeena, Redden, R.J., Materne, M. and Taylor, P.W.J. (2007) Lentil. In: Kole, C. (ed.) Genome Mapping and Molecular Breeding in Plants. Volume 3. Pulses, Sugar and Tuber Crops. Springer-Verlag, Berlin–Heidelberg, pp. 91–108. Gaur, P. and Chaturvedi, S.K. (2004) Genetic options for managing biotic stresses in pulse crops. In: Ali, M., Singh, B.B., Kumar, S. and Vishwa Dhar (eds) Pulses in New Perspective. Indian Society of Pulses Research and Development, Indian Institute for Pulse Research (IIPR), Kanpur, India, pp. 91–111. Hamwieh, A., Choumane, W., Udapa, S.M., Dreyer, F., Jung, C. and Baum, M. (2005) A genetic linkage map of lentil based on microsatellite and AFLP markers and localization of Fusarium vascular wilt resistance. Theoretical and Applied Genetics 110, 669–677. Haqqani, A.M., Zahid, M.A. and Malik, M.R. (2000) Legumes in Pakistan. In: Johansen, C., Duxbury, J.M., Virmani, S.M., Gowda, C.L.L., Pande, S. and Joshi, P.K. (eds) Legumes in Rice and Wheat Cropping Systems of the Indo-Gangetic Plain – Constraints and Opportunities. International Crops Research Institute for the SemiArid Tropics (ICRISAT), Patancheru, Hyderabad, India and Cornell University, USA, pp. 98–128. Khare, M.N., Bayya, B. and Beniwal, S.P.S. (1993) Selection methods for disease resistance in lentil. In: Singh, K.B. and Saxena, M.C. (eds) Breeding for Stress Tolerance in Cool Season Food Legumes. John Wiley and Sons, Chichester, UK, pp. 107–121. Matiur Rahman, M., Bakr, M.A., Mia, F., Idris, K.M., Gowda, C.L.L., Jagdish Kumar, Deb, U.K., Malek, M.A. and Sobhan, A. (2000) Legumes in Bangladesh. In: Johansen, C., Duxbury, J.M., Virmani, S.M., Gowda, C.L.L., Pande, S. and Joshi, P.K. (eds) Legumes in Rice and Wheat Cropping Systems of the Indo-Gangetic Plain – Constraints and Opportunities. International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, Hyderabad, India and Cornell University, USA, pp. 5–34. Muehlbauer, F.J., Cubero, J.I. and Summerfield, R.J. (1985) Lentil. In: Summerfield, R.J. and Roberts, E.H. (eds) Grain Legume Crops. Collins, London, UK, pp. 266–311. Neupane, R.K. and Bharati, M.P. (1993) Agronomy of lentil in Nepal. In: Erskine, W. and Saxena, M.C. (eds) Lentil in South Asia. Proceedings of Seminar on Lentil in South Asia, 11–15 March 1991, New Delhi, India. International Center for Agricultural Research in the Dry Areas (ICARDA), Aleppo, Syria, pp. 139–145. Pandey, A., Singh, D.P. and Singh, B.B. (1992) Interrelationship of yield and yield components in lentil (Lens culinaris Medik.) germplasm. Indian Journal of Pulses Research 5, 142–144.

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Pandey, S.P., Yadav, C.R., Sha, K., Pande, S. and Joshi, P.K. (2000) Legumes in Nepal. In: Johansen, C., Duxbury, J.M., Virmani, S.M., Gowda, C.L.L., Pande, S. and Joshi, P.K. (eds) Legumes in Rice and Wheat Cropping Systems of the Indo-Gangetic Plain – Constraints and Opportunities. International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, Hyderabad, India and Cornell University, USA, pp. 71–97. Porta-Puglia, A., Singh, K.B. and Infantino, A. (1993) Strategies for multiple-stress resistance breeding in cool-season food legumes. In: Singh, K.B. and Saxena, M.C (eds) Breeding for Stress Tolerance in Cool-Season Food Legumes. John Wiley and Sons, Chichester, UK, pp. 411–427. Ramakrishna, A., Gowda, C.L.L. and Johansen, C. (2000) Management factors affecting legumes production in the Indo-Gangetic plain. In: Johansen, C., Duxbury, J.M., Virmani, S.M., Gowda, C.L.L., Pande, S. and Joshi, P.K. (eds) Legumes in Rice and Wheat Cropping Systems of the Indo-Gangetic Plain – Constraints and Opportunities. International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, Hyderabad, India and Cornell University, USA, pp. 156– 175. Sarker, A., Erskine W., Sharma, B. and Tyagi, M.C. (1999) Inheritance and linkage relationships of days to flower and morphological loci in lentil (Lens culinaris Medikus ssp. culinaris). Journal of Heredity 90(2), 270–275. Sarker, A., Erskine, W. and Saxena, M.C. (2005) ICARDA and the South Asian lentil improvement programmes. Journal of Lentil Research 2, 39–45. Saxena, N.P., Saxena, M.C., Johansen, C., Khanna-Chopra, R., Krishnamurthy, L. and Saran, R. (2005) Characterization of drought and adaption of cool season food legumes to water limiting environment. In: Kharkwal, M.C. (ed.) Abstracts of the Fourth International Food Legume Research Conference (IFLRC IV), 18–22 October, 2005, New Delhi, India, pp. 20–21. Sharma, B., Tyagi, M.C. and Asthana, A.N. (1993) Progress in breeding bold seeded lentil in India. In: Erskine, W. and Saxena, M.C. (eds) Lentil in South Asia. Proceedings of Seminar on Lentil in South Asia, 11–15 March 1991, New Delhi, India. International Center for Agricultural Research in the Dry Areas (ICARDA), Aleppo, Syria, pp. 22–38. Shrestha, R., Siddique, K.H.M., Turner, N.C., Turner, D.W. and Berger, J.D. (2005) Growth and seed yield of lentil (Lens culinaris Medikus) genotypes of West Asian and South Asian origin and crossbreds between the two under rainfed conditions in Nepal. Australian Journal of Agricultural Research 56, 971–981. Shrestha, R., Turner, N.C., Siddique, K.H.M., Turner, D.W. and Speijers, J. (2006a) A water deficit during pod establishment in lentils reduces flower and pod numbers but not seed size. Australian Journal of Agricultural Research 57, 427–438. Shrestha, R., Turner, N.C., Siddique, K.H.M. and Turner, D.W. (2006b) Physiological and seed yield response to water deficits among lentil genotypes from diverse origins. Australian Journal of Agricultural Research 57, 903–915. Singh, D.P. (1997) Tailoring the plant type in pulse crops. Plant Breeding Abstracts 67(9), 1213–1220. Singh, D.P. and Singh, B.B. (1991) Evaluation of exotic germplasm in lentil. Narendra Deva Journal of Agricultural Research 6, 304–306. Summerfield, R.J. (1981) Adaptation to environments. In: Webb, C. and Hawtin, G.C. (eds) Lentils. Commonwealth Agricultural Bureau, Slough, UK, pp. 91–110. Tufail, M., Malik, I.A., Chaudhury, M., Ashraf, M. and Saleem, M. (1993) Genetic resources and breeding lentil in Pakistan. In: Erskine, W. and Saxena, M.C. (eds) Lentil in South Asia. Proceedings of Seminar on Lentil in South Asia, 11–15 March

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M. Matiur Rahman et al. 1991, New Delhi, India. International Center for Agricultural Research in the Dry Areas (ICARDA), Aleppo, Syria, pp. 58–75. Tyagi, M.C. and Sharma, B. (1989) Transgressive segregation for early flowering through conventional breeding in lentil. Lentil Experimental News Service (LENS) 16(1), 3–6. Vandenberg, A. and Slinkard, A.E. (1989) Inheritance of four qualitative genes in lentil. Journal of Heredity 80, 320–322. Wery, J., Silim, S.N., Knights, E.J., Malhotra, R.S. and Cousin, R. (1994) Screening techniques and sources of tolerance to extremes. In: Muehlbauer, F.J. and Kaiser, W.J. (eds) Expanding the Production and Use of Cool Season Food Legumes. Proceedings of the Second International Food Legume Research Conference (IFLRC II), 12–16 April, 1992, Cairo, Egypt. Kluwer Academic Publishers, Dordrecht, The Netherlands, pp. 439–546.

10

Improvement in Developed Countries

Fred J. Muehlbauer,1 Miho Mihov,2 Albert Vandenberg,3 Abebe Tullu3 and Michael Materne4 1Washington

State University, Pullman, Washington, USA; 2Dubroudja Agricultural Institute, General Toshevo, Bulgaria; 3University of Saskatchewan, Saskatoon, Canada; 4Department of Primary Industries, Horsham, Victoria, Australia

10.1. Introduction Cultivated lentil (Lens culinaris Medikus subsp. culinaris) had its origin in the Near East arc where the crop was domesticated an estimated 8000 years ago (Zohary, 1972; Ladizinsky, 1979). The lentil crop is now grown successfully on all continents except Antarctica. Lentil is adapted to most soils and climates, but is especially important in arid and semi-arid regions. Lentil is a quantitative long day plant and flowers in progressively longer days. It is grown as a winter crop in the Mediterranean region, South Asia, Australia and parts of South America. Though winter-hardy germplasm is available, the crop is primarily spring sown in most highland regions (>850 m above sea level) of West Asia, North Africa and in North America. Most of the world’s lentil crop is grown in the developing countries of West Asia, North Africa, East Africa and South Asia, where it is an important human food for local populations; while in developed countries production is targeted to specific international markets and speciality types. Demand for the large green type with yellow cotyledons, typical of ‘Brewer’, ‘Laird’ and other similar cultivars produced in Canada and the northern plains states of the USA, has driven production; however, increased international market demand for small red-cotyledon types has led to recent increased production of that type in Canada, USA and Australia. Several other types have importance for niche markets, for example the ‘Pardina’ preferred in Spain and several other types such as ‘Eston’. Domestic use of lentil in developed countries has remained rather minimal despite extensive domestic marketing efforts to increase consumption. Priorities and breeding goals usually differ between regions depending on critical location-specific problems and special considerations related to farmers’ needs and consumer demands. In developing countries particularly in the West Asia and North Africa region, the major breeding goals © CAB International 2009. The Lentil: Botany, Production and Uses (eds W. Erskine et al.)

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are development of cultivars with higher yields, resistance to major diseases, suitability for mechanical harvesting and improved residue yields because of the value placed on lentil straw as animal feed. By contrast, improved disease resistance, reduced tendencies to lodge, reduced pod and seed shatter, increased seed yield and improved seed quality traits are principal breeding goals in developed countries. Techniques of breeding lentil are similar to those used for other self-pollinating crops with some modifications.

10.2. Types of Cultivars A wide range of lentil cultivars is used throughout the world with the small diameter red-cotyledon type accounting for most of the production followed by the large and small yellow-cotyledon types. Green lentils range from 4 to 8 mm in diameter and cultivars can be divided into three market classes: large, medium and small. The typical large green lentil has lightgreen seedcoats with little or no mottling and cotyledons are yellow. There are no truly green-cotyledon lentils in the market at the present time although genetic stocks with green (light and deep) cotyledons are known (see Sharma, Chapter 7, this volume). Lentils with yellow cotyledons and virtually spotless testa are called ‘green lentil’, a term that is a common market jargon in developed countries. This expression is not used in the major lentilproducing and -consuming region of South Asia. In Canada, the large green type typical of ‘Laird’ and more recently ‘CDC Glamis’, ‘CDC Sovereign’, ‘CDC Grandora’, ‘CDC Plato’, ‘CDC Greenland’ and most recently the imidazolinone-tolerant cultivar ‘CDC Improve’ have dominated production. While in the USA, ‘Brewer’, ‘Merrit’, ‘Pennell’ and ‘Riveland’ are the predominant cultivars. Large green lentils are marketed as whole seeds and so uniformity of size, shape and colour is important for marketing. In Australia, the trend has been towards production of the small red type for export to South Asia and the Middle East. Lentil production in Australia began with the cultivars ‘Digger’, ‘Northfield’ (these two being the most significant), ‘Matilda’, ‘Cobber’, ‘Aldinga’, ‘Callisto’ and ‘Kye’. Now these cultivars have been replaced with ‘Nugget’ and more recently ‘Nipper’. US and Canadian production is also targeted to South Asia; however, considerable tonnage is exported to countries of southern Europe, particularly Spain, Italy and Greece. The medium category of green lentils include ‘Richlea’, ‘CDC Vantage’, ‘CDC Meteor’ and the imidazolinone-tolerant ‘CDC Impress’. The small category includes ‘Eston’, ‘Pardina’ and ‘CDC Milestone’ and more recently ‘CDC Viceroy’. Green lentils at harvest have yellow cotyledons with green seedcoats that progressively turn brown with age. Browning due to ageing will however occur only in the lentil strains having tannins in their seedcoat. Important export markets for medium and small green lentils exist in Algeria, Italy, Greece, Morocco and Spain, as well as South America. Canadian production of small red lentils has become equal to that of green lentils, starting with the cultivars ‘Redwing’ and ‘Crimson’, then ‘CDC Robin’ and ‘CDC Blaze’ and more recently ‘CDC Rouleau’, ‘CDC Rosetown’

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and ‘CDC Redberry’. The most recent cultivars, including ‘CDC Imperial’, ‘CDC Impact’, ‘CDC Impala’ and ‘CDC Maxim’, are tolerant to imidazolinone herbicides. US and Canadian red lentil production is targeted to South Asia; however, considerable tonnage is exported to Mediterranean countries, Egypt and Turkey. As with green lentils, cultivars of red lentils can be separated into small, medium and large sizes, although the size of each group is smaller than for green lentils. This is because the so-called ‘green lentils’ owe their origin to the microsperma subspecies and the red lentils are descendants of the microsperma subspecies which are also called Indian lentils (pilosae). Each country has preference for different sized red lentils based predominantly on the types traditionally grown and consumed. At one extreme Bangladesh prefers very small red lentils and Sri Lanka prefers large red lentils. Red lentil cultivars typically have brown or grey to black seedcoats resulting from various degrees of black spotting or mottling (see Sharma, Chapter 7, this volume) with red cotyledons but there is small production of red lentils with pale green seedcoats. The shape of red lentils is an important factor in the process of decortication (removal of the seedcoats) with round and thick seeds being preferred to flat and thin seeds. There is a huge market for decorticated red lentils in South Asia where they are sold under the name of ‘Malka Masoor’. Cultivars such as ‘Pardina’, important in Spain, and ‘Naslada’, important in Bulgaria, and ‘CDC LeMay’, the mottled French green type, also represent distinct lentil cultivars. Black seeded (‘Beluga’ in the USA, or ‘Indianhead’ in Canada) and white-seeded zero tannin cultivars are produced on a limited scale for speciality markets. Cultivars representing each of these quality types have been released for the local conditions in North America, Australia and elsewhere, including Bulgaria.

10.3. Genetic Resources Utilization, Interspecific Hybridization and Introgression Substantial genetic resources for use in lentil breeding are maintained at the International Center for Agricultural Research in the Dry Areas (ICARDA), Aleppo, Syria, and also by national programmes, particularly the USA, Canada, Australia, Russia, India and a number of other important repositories (Table 10.1). These genetic resources comprise landraces, breeding lines, cultivars and related wild species, and represent significant genetic variation that is readily available on request. In North America and Australia, landraces have been widely used in breeding programmes for resistance to diseases such as Ascochyta blight and Botrytis grey mould and tolerance to abiotic stresses such as boron toxicity and excess salinity. Resistance to anthracnose found in Lens ervoides germplasm is being exploited in Canada by introgressing the resistance genes into cultivated backgrounds (Tullu et al., 2006). This successful use of L. ervoides holds promise as a source of genes for resistance to other diseases and possibly for plant habit, biomass production and other important agronomic and marketing

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Table10.1. Major genebanks and the estimated number of accessions of lentil as of 2005.

Country

Abbreviation

Institution

1

Australia

ATFCC

2 3 4 5 6 7 8 9 10 11 12

Bangladesh Bulgaria Georgia Greece Israel India Spain Italy Canada New Zealand Pakistan

NBPGR IPGR GASU GGB IGB NBPGR, ARI SIA ISCI PGR NPGS NBPGR

13

Poland

NCPGR

14 15 16

Portugal Russia USA

ENMP VIR USDA, ARS

17 18

Syria Slovakia

ICARDA RIPP

19 20 21

Turkey Czech Republic Hungary

AARI AGRITC ABI

The Australian Temperate Field Crops Collection, Victorian Institute for Dryland Agriculture (VIDA), Australia National Bank for Plant Genetic Resources Dacca, Bangladesh Institute for Plant Genetic Resources, Sadova, Bulgaria Georgia Agrarian State University, Tbilisi, Georgia Greek Gene Bank, Thessaloniki, Greece Israel Gene Bank for Agricultural Crops, Volcani Center, Bet-Dagan, Israel National Bureau of Plant Genetic Resources, New Delhi, India Servicio de Investigacion Agraria, Valladolid, Spain Instituto Sperimentale per le Colture Industriali, Bologna, Italy Plant Gene Resources, Ottawa, Canada National Plant Germplasm System, Wellington, New Zealand National Bank for Plant Genetic Resources, Islamabad, Pakistan National Centre for Plant Genetic Resources, Radzikow, Poland Estacao Nacional de Melhoramento de Plants, Elvas, Portugal Vavilov Institute of Plant Industry, St Petersburg, Russia United States Department of Agriculture, Agriculture Research Service, Pullman, Washington, USA International Center for Agricultural Research in Dry Areas, Aleppo, Syria Research Institute of Plant Production, Genebank of the Slovak Republic, Piestany, Slovak Republic Aegean Agricultural Research Institute, Menemen-Izmir, Turkey AGRITEC Research, Breeding and Services Ltd, Sumperk, Czech Republic Institute for Agrobotany, Tapioszele, Hungary

No. of accessions 3,841 1,518 532 36 97 204 8,482 603 348 2,345 678 2,576 4 215 3,338 2,484 10,113 279 615 80 866

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No.

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traits. Further exploitation of L. ervoides and the other wild Lens species seems warranted.

10.4. Crossing Techniques in Lentil Healthy plants with well-developed flowers are important for successful lentil crossing. Female flowers selected for emasculation should have corolla petals that are unopened and have reached approximately three-quarters the length of the sepals, although this will vary depending on the parental line (Plate 1A). The cleistogamous self-pollinating flowers are small and care must be taken to avoid injury during emasculation. For emasculation, the petals are carefully folded back (Plate 1C) to expose the anthers, which are carefully removed using sharply pointed forceps (Plate 1D). More advanced flowers with very recently dehisced anthers are chosen as a source of pollen (Plate 1B) and can be identified quickly with some practice. The emasculated flower (Plate 1E) is pollinated immediately. A common technique is to use the pollen-laden stigma of the male parent as a brush to carefully apply the pollen to the stigma of the female flower (Plate 1F). Pollen should have a bright yellow to orange appearance and should be visible on the surface of the stigma of the female flower (Plate 1F). After pollination, the petals are carefully returned to their original positions covering the ovary and stigma. Early to mid-morning is generally most appropriate for lentil crossing. For further information on lentil crossing techniques and appropriate environmental conditions see reviews by Muehlbauer et al. (1980, 1985) and Muehlbauer and Slinkard, (1981). Rather simple equipment is needed for lentil crossing and includes magnifying glasses, a pair of sharply pointed forceps, a vial of 95% alcohol, and small tags. Viewing of flower parts can be improved with visors that provide 5× to 10× magnification. Forceps to be used for emasculation and pollination are immersed in the alcohol between crosses to prevent contamination by foreign pollen. Small tags are used to record the parents, dates and the identity of the person making the cross. Some crossing programmes use colour-coded string to label the crossed flowers. Developing pods of crossed flowers become visible in 3–4 days. Several morphological markers are used to confirm hybridity of the crossed seeds. For example red versus yellow cotyledon colour has often been used as a genetic marker to easily identify hybrid seeds, but only when the yellow-cotyledon parent is used as female. Likewise, the gs gene for stem coloration is also a useful marker to identify F1 hybrids at seedling stage where the male and female parents have purple and green stems, respectively. Molecular markers are also an obvious approach to identify F1 hybrids and can be used effectively to eliminate selfed seeds. Where large seed-size differences exist between parental lines, it is advisable to use the large-seeded parental line as the female parent. Such genotypes also have larger flowers that are easy to handle. This makes emasculation easier and also reduces the chances for pod shatter. The larger

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seeded parent with corresponding pod size can accommodate the large hybrid seeds within their pod walls while the pods of the smaller seeded parent often cannot. Some breeders use the smaller seeded parent as female because two hybrid seeds are often set in the pods of the smaller seeded parent. When crosspollination is successful, ovary development is rapid and the developing hybrid seeds are conspicuous in the pods. Harvesting of the crossed pods is always done by hand when they turn yellow-brown. Harvested pods should be allowed to dry completely in envelopes or small muslin cloth bags before the seeds are removed. Hybrid seeds can be kept temporarily at room temperature; however, for long-term storage, lentil breeding material should be stored at about 10°C with 30% relative humidity or in a freezer at –20°C. Crossing blocks vary with the preferences of the breeder and numerous layouts have been described that are effective in placing the female and male parents in close proximity. When crosses are made in controlled environments, pot-grown plants are used and can be placed in close vicinity for ease of crossing. Crossing plans in controlled environment generally include several plantings of the parental material at predetermined intervals to ensure synchrony in flowering of parents differing in phenology. This also ensures availability of flowers over a longer period.

10.5. Methods Used in Lentil Breeding Pure line selection either within local landraces or introduced germplasm has been an important means of developing lentil cultivars with uniformity and adaptation to local conditions. However, lentil improvement programmes established in developed countries in the past three to four decades have been largely based on hybridization and selection. ICARDA, USA, Bulgaria, Canada and later Australia have developed breeding programmes that rely on selection within populations derived from crosses involving germplasm accessions with specific traits needed to solve important production or quality problems. Breeding lines and advanced material from those programmes have been released as improved cultivars and have found their way into breeding programmes of many developing countries. The methods of breeding lentil are similar to those followed in the breeding of other self-pollinated crops and include combinations of bulk, pedigree, and single-seed descent procedures. SSD and mutation breeding has been employed for specific purposes. The use of doubled haploids in lentil is not yet possible, but recent progress made in developing electroporation techniques to induce doubled haploids in field pea (Ochatt et al., 2007) and chickpea (Grewal et al., 2008) may soon be adapted to lentil. In Canada, unadapted germplasm is introduced into the breeding stream using a process of systematic introduction of new germplasm, or SINGing. Since most lentil germplasm is completely unadapted to the long day environment of the Canadian prairies, it has become a standard practice to use multi-parent crosses to dilute the genetic contribution of unadapted parents. Three cycles of crossing are used to produce large numbers of F1

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seeds for field screening. Using this approach it is possible to produce threeway crosses and five-way crosses in which a 50% genetic contribution to the cross is made by a parent with the best agronomic performance. During the crossing cycles it is possible to use gamete selection (Singh, 1994) to select for seedcoat and cotyledon characters.

Bulk population Bulk population, often with some modification, has been the preferred method for lentil breeding because of the ease of application and because of inherent difficulties when applying other methods to lentil. Bulk population breeding of lentil is simple, requires minimal record keeping, and is not labour intensive. The simplicity and relatively low cost of the bulk method makes it attractive to most lentil breeders and also provides sufficient seed of segregating populations for evaluation and selection under diverse environments. This aspect is especially important for traits such as winter hardiness, where natural selection is relied upon to identify the most winter-hardy plants. However, caution is needed when using the system in lentil since good seed set on individual plants within a bulk population may not necessarily ensure retention of desirable genotypes during generation advancement. Therefore careful monitoring of bulk populations and their composition is important. Mass selection for seed size, shape and colour is easily applied to bulk populations during generation advancement. Slinkard et al. (2000) described the recombinant-derived family (RDF), also known as the F2-derived family, method for lentil breeding whereby early generation selection for yield is practised in F2:4, F2:5 and F2:6 families to eliminate inferior crosses and inferior F2-derived families. Additional screening of F2 populations and F2-derived F3 families in rows or microplots in disease nurseries can be integrated into the selection process, provided that sufficient numbers of plants produce adequate quantities of seed. Regional trials are conducted on the best F2:7 and F2:8 families. Results of those trials determine which F2-derived families are refined by selection for phenotypic traits and considered for release as improved cultivars. Advantages of the RDF method include: yield testing in early generations leading to rapid elimination of low-yielding crosses and families; and a shortened time period from the initial cross to the final cultivar release. Another advantage is that selection can be based on phenotypic characters such as canopy architecture, pod distribution and lodging as early as the F3. This favours selection for mechanical harvesting systems. It is also possible to apply mass selection for specific seed diameter and thickness during generation advancement. Also, there is some benefit to be derived from the fact that the resulting cultivars have a degree of heterogeneity that may improve adaptation to the environment leading to more stable yields. The heterogeneity maintained in the resulting cultivars may be a disadvantage of the RDF method and prevent application for Plant Variety Protection (PVP). Although PVP has generated little interest among lentil breeders in developed countries

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this is likely to change in Australia where Plant Breeder Rights (PBR) can play an important role in the effective collection of end-point royalties. The US lentil breeding programme uses a modified bulk method whereby the populations are advanced in bulk to the F4 followed by visual selection for desired plant and seed types. Bulks are retained in the breeding programme for advancement to the F5 and F6 with selection in each generation for desired types. Populations of selected bulks are grown in the glasshouse during the off-season and the resulting plants are sown into individual plant rows in the field for further selection. Selected lines are then evaluated for agronomic traits, disease resistance, seed quality traits and yield. Promising selections are tested widely and depending on performance, released as improved cultivars. Breeding methodology in Australia is also based on a bulk population method with single pod selection at F2 and F3 and single plant selection at F4. The F2, F3 and F4 populations are grown in the field during the growing season and Ascochyta blight-infested lentil stubble is spread over the plots as a source of inoculum to screen for resistance to this disease. Natural selection for Ascochyta blight resistance is followed by mass selection for freedom from Ascochyta blight blemishes using an electronic colour sorter. Machine harvesting is purposely delayed to shift the population towards reduced pod drop and seed shatter. With delayed harvest, those genotypes in the population that are prone to shatter will have lost their seeds while those that resist shatter will retain their seeds and be harvested, thus shifting the population towards shatter-resistant genotypes. Mass selection for seed shape (roundness) is accomplished using sieves and selection for seed colour is accomplished using the electronic colour sorter. Seed from pods of F2 and F3 plants is grown over summer in tubes in the glasshouse. Progenies from seed of single pods (selected from F2 and F3 plants) and F4 plants are sown in 5 m rows (approximately 8000) in the field during the winter season. Selection among those progeny rows is based on resistance to Ascochyta blight, plant height, resistance to lodging, pod drop and shattering, vigour/biomass, and timing of flowering and maturity. Seed from selected rows is assessed visually for seed colour, size, shape and freedom from Ascochyta blight blemishes. Selected lines are evaluated for yield, quality and harvestability across the target range of environments. Stage 1 trials are unreplicated and located at three sites, stage 2 trials have two replications and eight sites and stage 3 trials have three replications and eight sites. Row-by-column designs are used and trials are spatially analysed. Screening for the two major diseases, Ascochyta blight and Botrytis grey mould are done for entries in all stages of testing in the field and controlled environments, respectively. Breeding lines are also screened for tolerance to the major herbicides in the field and toxicity to boron and salinity (NaCl) using soil-based media in a controlled environment. Physical, milling and cooking qualities of the lines are assessed in the laboratory. All potential new lentil cultivars are evaluated for response to commonly used agronomic practices and a management package made available to farmers to maximize the benefits of new cultivars.

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Promising selections are subjected to pedigree seed production in collaboration with PB Seeds, the commercial seed partner for the breeding programme. The breeding programme’s major focus is on small, medium and medium-large red lentils and large green lentils; however, small and medium green lentils and other niche types are also produced. Simple and complex crosses are made in the glasshouse during the growing season, which enables crosses to be made using field pollen of elite lines. Pedigree selection The pedigree selection breeding method is not particularly suited to lentil breeding because of plant architecture and plasticity, which allows the plants to occupy available space. The response of lentil plants to available space is a disadvantage in selection because performance as individual widely spaced plants often is entirely different from performance in more dense stands of the same genotype. Selection based on yields of individual plants has been ineffective for lentil breeding (Erskine et al., 1990). However, selection of individual plants for highly heritable traits such as seed size, flowering time and height is likely to be successful. Population sizes for effective use of the pedigree method for lentil breeding will depend on the genetics and heritability of the traits under consideration and resources available to the breeding programme. Single seed descent (SSD) SSD is well suited to rapid generation advance in lentil breeding provided there is a facility (glasshouses or off-season nurseries) for growing the populations several times in a year. The primary advantages of the SSD method are the maintenance of genetic variation during generation advance and the minimal space required for the method. Haddad and Muehlbauer (1981) found more genetic variation was maintained by SSD compared to the same populations advanced by the bulk method. In their study, three SSD-derived populations had 10, 9, and 13% more erect lines, respectively, when compared with the same hybrid populations advanced by the standard bulk method. SSD has been used effectively to develop recombinant inbred lines (RILs) for use in genetic linkage analyses and development of genetic maps of the lentil genome (Eujayl et al., 1998; Kahraman et al., 2004; Hamwieh et al., 2005). Development of RIL populations is currently underway for mapping of the genes for resistance to rust, Stemphyllium blight, Ascochyta blight and Sclerotinia white mould using the SSD method. Mutation breeding Mutation breeding merits consideration in a lentil breeding programme where a desired trait may not exist in available germplasm. The approach is feasible where suitable screening methods are available and can be employed

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to evaluate large populations of mutagenized plants. Mutation breeding has the promise of improvement of important traits in lentil without altering the genetic background. While this may not always be true, other breeding techniques such as the backcross method may be used to return the genetic background to the desired type. Mutations have been important for genetic mapping and genomic approaches towards identification of important gene functions. A number of effective physical and chemical mutagens are available including X-rays, gamma-rays, fast and slow neutrons, ethyl methane sulfonate (EMS), ethyl nitrous-urea (ENU), methyl nitrous-urea (MNU) and sodium azide (NaN3). Effectiveness of chemical mutagens depends on mutagen concentration and treatment conditions and the ability to identify micro-mutations in the mutagenized material. Eight lentil cultivars developed through induced mutations using irradiation have been registered in India, Bulgaria and Canada (Bhatia et al., 2001; Mihov et al., 2001; Toker et al., 2007). Cultivars developed by mutagenesis reportedly vary for vegetative growth period, plant height, seed size and colour. An interesting dwarf mutant was isolated from mutagen treatment of ‘Tadjikskaya’ (Mihov et al., 2001). The dwarf mutant has significantly shorter internodes and increased branching. The mutant may be of interest to researchers working on morphological development and comparative genomics. Mutants for flowering traits, plant growth habit and seed quality variations have been described and may have similar interest in studies of genomics and morphological development as well as value for breeding purposes. EMS treatment was used in Canada to identify a lentil line with tolerance to imidazolinone herbicides. The trait was patented (http://www. patentstorm.us/patents/7232942-description.html) and licensed for use in Clearfield™ lentil cultivars. The trait has been transferred to cultivars in all market classes, resulting in the release of a series of herbicide-tolerant cultivars including ‘CDC Imperial’, ‘CDC Impact’, ‘CDC Improve’, ‘CDC Impala’, ‘CDC Impress’ and ‘CDC Maxim’. Clearfield™ lentil cultivars are now widely available in Canada. The backcross method Backcross breeding provides predictable results and is generally used for simply inherited traits with high heritability, for example herbicide tolerance. Backcrossing of the genes for resistance to diseases such as Fusarium wilt and viruses are prime candidates for improvement of lentil by backcross breeding. The brief history of lentil breeding often means that breeding programmes are targeting improvements in many traits simultaneously rather than incorporating a single gene into an elite cultivar. Population improvement and germplasm enhancement Population improvement has not had an important role in lentil breeding primarily because of the difficulties in making the necessary numbers of

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crosses and the lack of an efficient male sterility/restorer system. However, a form of cyclical recurrent selection may be warranted in order to concentrate minor genes for important quantitatively inherited traits. The process requires a careful choice of parents, intercrossing to develop a heterogeneous population of heterozygous plants, screening for the trait of interest and intercrossing of selected individuals to form the base population for the next cycle of selection. The process is repeated for several cycles and during the progression through the successive cycles mean performance is evaluated for the amount of genetic variation available for effective selection. The resulting improved population can then be used in the breeding programme to develop trait-specific cultivars. The method has been used successfully in Canada to improve resistance to anthracnose. Each year, multi-parent hybrids are used to develop F2-derived Fs micro-plots which are screened in a field disease nursery that is inoculated with anthracnose-infested lentil debris. Single plants from the most resistant micro-plot in the top 5–10 resistant populations are selected as parents to begin a new cycle of selection. Breeders have become increasingly aware of the need to better coordinate germplasm enhancement within regional breeding programmes. The Australian lentil breeding programme has developed a formalized approach to incorporate germplasm enhancement using traditional and biotechnological approaches. With this approach it is hoped to locate and incorporate new characteristics into improved cultivars rapidly. Through this mechanism the breeding programme is well positioned to collaborate with and provide adapted backgrounds for new biotechnological advances that may occur (e.g. genetic modification, doubled haploids, etc.) and implement the technology. It is also expected that advanced breeding techniques and germplasm enhancement successfully employed in other pulses will be extended to lentil. For example developments in tissue culture of peas may open avenues for use in lentils. Identification of the DNA sequence with specific functions in the model species may aid in locating and cloning genes with the same or similar function in lentils. A series of projects that use sequence-based approaches to develop marker-based strategies for increasing genetic gain in lentil have started in Canada, the USA and Australia.

10.6. Selection Procedures for Special Traits Traits needed for mechanized and extensive production in developed countries include predictable flowering times, tall plants with upright growth habit and minimal pod and seed shattering. In traditional lentil-growing regions, optimal flowering response is represented in indigenous landraces. However, in new production areas optimal flowering response and yield potential are determined during germplasm assessment. Flowering time in lentil has been reviewed (Roberts et al., 1988) indicating that progress towards flowering is predictable and depends on temperature and photoperiod. Where major changes in crop agronomy were introduced (e.g. tolerance of diseases) there is also a need to re-establish optimal flowering physiology under the

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altered circumstances. In Australia, selection for genotypes that are responsive to temperature but not photoperiod for flowering is done by measuring flowering times at two key sites. Important cultivars with broad rather than specific adaptation in new production areas include ‘Crimson’ and ‘Eston’ in the USA, and ‘Digger’ and ‘Nugget’ in Australia. Tall upright growth habit with resistance to lodging is an important trait under selection in developed countries. Upright habit is essential for adaptation to machine harvesting while reducing the potential for the pods to come in contact with soil surfaces causing staining, seed decay and reduced product quality. Plant height index as a selection tool has been established by the US breeding programme. According to the procedure, the ratio of canopy height at maturity relative to canopy height in the full flowering stage is calculated and used as a selectable trait. Selections with ratios close to 1.0 are considered to have good resistance to lodging while lower ratios indicate less lodging resistance. The cultivars ‘Pennell’ and ‘Merrit’ were selected for their resistance to lodging using the plant height index. In Canada, a selection technique for lodging resistance is under development. It is based on using a roller to flatten plots just prior to flowering, then visually assessing recovery after 3 days. The cultivar ‘CDC Redberry’ is highly resistant to lodging in Canada, resulting in its quick adoption by lentil growers. In Australia, genotypes with good lodging resistance are more prone to pod drop caused by strong winds at maturity and improved resistance to pod drop is a key breeding aim. Fungicides are often available for the economic control of diseases; nevertheless, genetic resistance is a major focus towards improving reliability of yield and increase profitability. Identification of resistant/tolerant germplasm, determining the inheritance of the trait and formulating selection procedures for use in breeding are the primary approaches used in breeding. Of particular importance in Canada and Australia is the prevalence of Ascochyta blight caused by Ascochyta lentis, which has devastated production and product quality in those countries. Of nearly equal importance in Canada is anthracnose caused by Colletotricum truncatum; however, resistance has been found in L. ervoides and is being transferred to cultivated backgrounds. Foliar fungal diseases are particularly devastating in cool and humid environments typical of the winter growing season in Australia, the cool and wet spring conditions in Canada, and the northern plains states of the USA. The cultivar ‘Nipper’ released in Australia has good resistance to grey mould and Ascochyta blight. Progress in finding germplasm sources with resistance or tolerance to these foliar fungal diseases has been reviewed by Tivoli et al. (2006). Most traits needed for efficient lentil production are selected under normal field conditions using well-designed nurseries with suitable checks. Reportedly, selection for yield under variable rainfed conditions has increased water use efficiency through an increased response to moisture availability (Erskine et al., 1993; Materne and McNeil, 2007). However, breeding has increasingly focused on addressing abiotic and biotic constraints, particularly disease. In the USA and Turkey (Central Anatolia), large yield increases

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have been achieved by sowing lentil in winter rather than spring using genotypes tolerant to cold temperatures (Kusmenoglu and Aydin, 1995; Hamdi et al., 1996; Muehlbauer and McPhee, 2002). The cultivar ‘Morton’ was developed in the USA for autumn sowing into standing cereal stubble. The standing stubble helps with winter survival by trapping snow and providing some protection from freezing temperatures and desiccating winds. Although generally adapted to alkaline soils, lentil growth can be affected by hostile subsoil factors such as high pH, toxic levels of boron and salinity and sodicity. Although variation in tolerance to these factors has been identified, breeding efforts to target these stresses has been, to our knowledge, relatively limited. Breeding lines with improved tolerance to boron, derived from ILL 2024, have been developed in Australia and based on controlled environment experiments could improve yields by up to 91% in the target regions (Hobson et al., 2006). Similarly, lines with improved tolerance to NaCl have been developed and are soon to be released in Australia. These lines have great potential as they are the highest yielding entries in advanced yield trials (Materne and McNeil, 2007). In the breeding programme, boron screening involves growing plants in soil that is high in boron and rating symptom expression, while for NaCl screening, plants are grown in sand media to which saline water is added after emergence. ICARDA has the world mandate for lentil improvement and the Center has been instrumental in developing high-yielding cultivars with greater total biomass yield, drought tolerance and resistance to disease. Since 1980, more than 100 lentil cultivars that can be traced back to ICARDA-generated material have been released by various national programmes. The released cultivars represent improvement for resistance to pod shattering, lodging, greater plant height, enhanced yield potential and improved adaptation. As a result large production increases have been realized in areas of Turkey, South Asia and other countries of West Asia and North Africa. Developments in lentil germplasm have also benefited the developed countries where the material is routinely used in breeding programmes to broaden the genetic base for traits under selection.

10.7. Trait Selection for Domestic Markets For most domestic markets in developed countries, large-seeded lentils with yellow cotyledons and light-green seedcoats are preferred; however, there is increased interest in small red-cotyledon cultivars. Many of the traits needed for domestic markets in developed countries are the same as those needed for export markets. Mass selection for physical seed characteristics is done by hand picking, using sieves or mechanization using small-scale equipment such as gravity tables or electronic colour sorters. Since most of the lentil crop in developed countries is exported, trait selection is export-market driven. The important traits under selection are mostly cosmetic and concern outward physical appearance, minimal mechanical damage to the seeds during harvesting

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and processing, short cooking times and good visual appearance after cooking. Recent work on the genetics of green seedcoat colour in Canada showed that this trait had medium to high heritability (Davey, 2007). Selection in breeding programmes for market traits use, methods developed by individual breeding programmes with most based on the procedures developed at ICARDA. Procedures used for determining percentage water uptake, time for cooking and qualities after cooking have been developed at ICARDA (Erskine et al., 1985). A small portable decortication machine is used to decorticate small red lentils to determine percentage yield during the process and also to assess colour of the resulting product. Breeding for processing and cooking quality will become increasingly important as markets and consumers have more choice and become more sophisticated in their preferences.

10.8. Trait Selection for International Markets Breeding programmes in developed countries monitor their breeding material to ensure that new cultivars have quality traits that are acceptable to international markets. In the case of small red-cotyledon cultivars, consideration is given to the yield of the split product and the depth of red coloration of the cotyledons after decortication. Quality traits such as protein and amino acid concentrations are a lesser concern. Breeders in North America are concerned with large-seeded green lentils in the size range of 7–8 mm in diameter and with yellow cotyledons and light-green seedcoats that lack mottling. While large green lentils have been the primary focus of breeding in North America, within the past decade other types particularly the small-seeded red-cotyledon type, have taken on greater importance for export. In addition to the large green and small red types, medium-sized yellow lentils typical of the cultivar ‘Eston’ have gained some importance while the small brown type with yellow cotyledons typical of ‘Pardina’ have been widely grown in the USA primarily for export to Spain, and small marbled types with yellow cotyledons typical of ‘CDC LeMay’ have been grown for export primarily to France. In contrast to North America, lentil production in Australia is predominantly of the red type but the first widely adapted green lentil ‘Boomer’ has recently been released for production and to develop export opportunities. For the smaller red-cotyledon types, seed thickness is most important since there is a direct correlation between decortication yield and seed thickness with the thicker seeds generally having higher decortication yields and less cotyledon chipping. Diameter is also important as markets range from those that prefer larger splits to those that prefer small round lentils that can be decorticated without splitting (the so-called ‘footballs’ and referred to in India as ‘Malka Masoor’). At ICARDA and in Canada, efforts are underway to understand the heritability of the content of micronutrients such as iron and zinc in lentil. In many countries, lentils are regarded as important sources of micronutrients, and research of this type will expand in future. Once heritability estimates

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are established, appropriate breeding strategies for biofortification can be devised. In future, this information may lead to the development of breeding programmes with specific objectives for micronutrient content.

10.9. Linkages and Networks with International Programmes With ICARDA having the world mandate for improving lentil it is important that national lentil research programmes and particularly the breeding programmes have close linkages with the Center. Based on close collaboration, large and sustainable increases in lentil production have been achieved in Canada, the USA, Australia, Turkey and South Asia. Collaboration with ICARDA has formed the basis of breeding in developed countries and currently strong ties of collaboration exist there. The most valued result of linkages of ICARDA with breeding programmes in developed countries has been the germplasm exchanges for mutual benefit and discussion of problem areas leading to research collaboration. ICARDA maintains the most extensive world collection of lentil germplasm that includes the largest number of accessions of wild species and also the largest collection of landraces and improved germplasm. This resource has been used extensively for breeding and genetic investigations. Linkage projects with ICARDA have been able to map the quantitative trait loci (QTL) for tolerance to cold and winter injury in lentil and to foster the introduction of winter germplasm into the USA, Turkey and Central Asia. Other productive linkage projects have led to the first genetic linkage map of the lentil genome (Hamwieh et al., 2005) and the mapping of genes for resistance to Fusarium wilt. An ongoing linkage project between ICARDA and the USA is working towards understanding the genetics of resistance to rust and Stemphylium blight in lentil and placing the relevant resistance genes on the lentil genetic map. An effort is currently underway in Canada in collaboration with the USA and Australia to identify genetic stocks and hybrid populations that can be used for in-depth genomics research on lentil which is expected to improve our understanding of the lentil genome and how it compares to other cool-season food legumes and to the model legume species, Medicago truncatula and Lotus japonicus.

10.10. Summary and Conclusions Lentil breeding in developed countries has focused on developing cultivars to meet international market demands, increasing yields through improved disease resistance and improving quality traits. Systematic germplasm collection in the centre of origin for the wild species has provided a means to broaden the genetic base for breeding and selection. The expanded lentil germplasm pool is being exploited for resistance to disease, for example resistance to anthracnose found in L. ervoides. Additional exploitation of the

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wild species may be forthcoming for resistance/tolerance to other biotic stresses and especially abiotic stresses such as heat and drought. Progress has been made in recent years towards understanding the genetics of important traits in lentil and location of the genes on the lentil genetic map. While lentil genomics is currently far behind that of the major legume crops such as pea, chickpea, dry bean and soybean, efforts are underway in several labs in developed countries towards marker development and genetic mapping. Markers closely linked to genes of interest are being sought for such traits as resistance to Fusarium wilt, Stemphyllium blight, rust, Ascochyta blight, anthracnose, winter hardiness, resistance to drought and a number of other important traits. Lentil research programmes have not identified improved nitrogen fixation as an important priority either by management or genetic manipulation. With increased costs of nitrogen fertilizers this aspect of lentil research may acquire increased importance. Current estimates of nitrogen fixation by lentil crops are few and indicate only nominal contributions to soil nitrogen status. Excellent cooperation has been developed among lentil breeders in developed countries and exchanges of breeding materials have taken place on a regular basis as well as exchanges of information at regional, national and international conferences and workshops. In most countries breeding programmes are funded by local government and much of the advisory, cultivar-testing and seed-distribution roles are also controlled by government agencies. However, in developed countries private investment is important. In Canada, the USA and Australia, farmers invest in lentil research, including breeding, through research levies collected on production. In these and other countries private companies have increased investment in the cultivar release process by undertaking the multiplication of new cultivars, distribution of seed and, in the case of Australia, collecting royalties for investment back into agricultural research. In Canada, the Saskatchewan Pulse Growers Organization supplies operational funds for the lentil breeding programme and in return, receives the rights to commercialize all lentil breeding lines produced by the breeding programme. In the USA, the USA Dry Pea and Lentil Council collects an assessment on the first sale of the lentil crop with the funds collected being allocated to marketing and research programmes.

References Bhatia, C.R., Maluszynski, M., Nichterlein, K. and van Zanten, L. (2001) Grain legume cultivars derived from induced mutations and mutations affecting nodulation. Mutation Breeding Review 13, 1–44. Davey, B.F. (2007) Green seed coat colour retention in lentil (Lens culinaris). MSc. thesis, University of Saskatchewan, Saskatoon, Saskatchewan, Canada. Erskine, W., Williams, P.C. and Nakhoul, H. (1985) Genetic and environmental variation in the seed size, protein, yield and cooking quality of lentils. Field Crops Research 12, 153–161.

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Erskine, W., Isawi, J. and Masoud, K. (1990) Single plant selection for yield in lentil. Euphytica 48, 113–116. Erskine, W., Tufail, M., Russell, A., Tyagi, M.C., Rahman, M.M. and Saxena, M.C. (1993) Current and future strategies in breeding lentil for resistance to biotic and abiotic stresses. Euphytica 73, 127–135. Eujayl, I., Baum, M., Powell, W., Erskine, W. and Pehu, E. (1998) A genetic linkage map of lentil (Lens sp.) based on RAPD and AFLP markers using recombinant inbred lines. Theoretical and Applied Genetics 97, 83–89. Grewal, R., Lulsdorf, M., Croser, J., Vandenberg, A. and Warkentin, T.D. (2008) Progress towards androgenesis from intact anther culture in chickpea (Cicer arietinum L.). In: Seventh Canadian Workshop, International Association of Plant Tissue Culture, Saskatchewan, Saskatoon, Canada. University of Saskatchewan, Saskatoon, Saskatchewan, Canada, p. 18. Haddad, N.I. and Muehlbauer, F.J. (1981) Comparison of random bulk population and single-seed-descent methods for lentil breeding. Euphytica 30, 643–651. Hamdi, A., Kusmenoglu, I. and Erskine, W. (1996) Sources of winter hardiness in wild lentil. Genetic Resources and Crop Evolution 43, 63–67. Hamwieh, A., Udupa, S.M., Choumane, W., Sarker, A., Dreyer, F., Jung, C. and Baum, M. (2005) A genetic linkage map of Lens sp. based on microsatellite and AFLP markers and the localization of fusarium vascular wilt resistance. Theoretical and Applied Genetics 110, 669–677. Hobson, K., Armstrong, R. and Nicolas, M. (2006) Response of lentil (Lens culinaris) germplasm to high concentrations of soil boron. Euphytica 151, 371–382. Kahraman, A., Kusmenoglu, I., Aydin, N., Aydogan, A., Erskine, W. and Muehlbauer, F.J. (2004) QTL mapping of winter hardiness genes in lentil. Crop Science 44, 13–22. Kusmenoglu, I. and Aydin, N. (1995) The current status of lentil germplasm exploitation for adaptation to winter sowing in the Anatolian highlands. In: Keatinge, J.D.H. and Kusmenoglu, I. (eds) Autumn Sowing of Lentil in the Highlands of West Asia and North Africa. Central Research Institute for Field Crops (CRIFC), Ankara, Turkey, pp. 63–71. Ladizinsky, G. (1979) The origin of lentil and its wild genepool. Euphytica 28, 179–187. Materne, M. and McNeil, D.L. (2007) Breeding methods and achievements. In: Yadav, S.S., McNeil, D.L. and Stevenson, P.C. (eds) Lentil: an Ancient Crop for Modern Times. Springer, Dordrecht, The Netherlands, pp. 241–253. Mihov, M., Stoyanova, M. and Mehandjiev, A. (2001) Some results of application of experimental mutagenesis on lentil (Lens culinaris Medik.). Proceedings of Higher Institute of Agriculture Plovdiv, Bulgaria. Vol. XLVI, book 2. Agricultural University, Plovdiv, Bulgaria, pp. 397–400. Muehlbauer, F.J. and McPhee, K.E. (2002) Future of North American lentil. In: Proceedings of the Australian Lentil Focus National Conference. Horsham, Australia. Pulse Australia Ltd, Sydney, pp. 30–34. Muehlbauer, F.J. and Slinkard, A.E. (1981) Genetics and breeding methodology. In: Webb, C. and Hawtin, G.C. (eds) Lentils. Commonwealth Agricultural Bureau, Slough, UK, pp. 69–90. Muehlbauer, F.J., Slinkard, A.E. and Wilson, V.E. (1980) Lentil. In: Fehr, W.R. and Hadley, H.H. (eds) Hybridization of Crop Plants. American Society of Agronomy, Madison, Wisconsin, USA, pp. 417–426. Muehlbauer, F.J., Cubero, J.I. and Summerfield, R.J. (1985) Lentil (Lens culinaris Medic.). In: Summerfield, R.J. and Roberts, E.H. (eds) Grain Legume Crops. Collins, UK, pp. 262–311.

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11

Advances in Molecular Research

Rebecca Ford,1 Barkat Mustafa,1 Michael Baum2 and P.N. Rajesh3 1The

University of Melbourne, Victoria, Australia; 2International Center for Agricultural Research in the Dry Areas (ICARDA), Aleppo, Syria; 3Washington State University, Pullman, Washington, USA

11.1. Introduction Advances have been made towards understanding the lentil genome and the development and application of molecular markers to advance breeding strategies. However, the routine application of markers to lentil breeding programmes worldwide is limited, most likely because of lack of resources for broad validation and implementation. Meanwhile, rapid biotechnological advances are fast transforming the field of lentil molecular genetics into an integrative science resulting from the fusion of statistics, computer science, mathematics, genomics and biology. The molecular maps, genomics approaches and the availability of gene sequences from lentil as well as the full genomes of the model organisms are beginning to illuminate the complex and intertwined nature of responses to both biotic and abiotic stimuli. In particular, the utilization of recently available gene sequences in lentil is playing a key role in broadening our understanding of the complexity of the biological systems they underpin.

11.2. Genomics and Gene Identification One method to identify functionally associated genes is global gene expression profiling, usually performed at the mRNA level. Essentially, this aims to identify RNAs that are present in a specific tissue sample at a particular time and in response to a particular stimulus. Gene expression is the cellular process that transcribes the genetic information of the DNA into short-lived mRNA and from mRNA to proteins, which ultimately determines the functionality of the gene. Therefore, characterizing the RNA population under a particular environmental and/or developmental condition may provide a window to understand the dynamic function of genes as well as their mutual © CAB International 2009. The Lentil: Botany, Production and Uses (eds W. Erskine et al.)

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role in a particular regulatory system. Gene expression profiling holds tremendous promise for dissecting the regulatory mechanisms and transcriptional networks that are involved in defence responses to pathogen attack or physiological responses to abiotic stress such as drought, cold or salinity. Various approaches have been developed for analysing differential gene expression. These include: cDNA-amplified fragment length polymorphism (cDNA-AFLP) (Bachem et al., 1998), suppression subtractive hybridization (SSH) (Diatchenko et al., 1996), and serial analysis of gene expression (SAGE) (Velculescu et al., 1995), differential display (Liang and Pardee, 1992; Walsh et al., 1992), massively parallel signature sequencing (MPSS™) and microarray technology (Schena et al., 1995). Of these, microarray technology has become the method of choice for large-scale systemic analysis of differential gene expression profiling. Microarrays comprise DNA probes immobilized to a solid substrate (Shalon et al., 1996; DeRisi et al., 1997). To these probes, fluorescently labelled nucleic acid molecules (typically cDNA prepared by reverse-transcription or mRNA) are hybridized. Implemented in the context of well-designed experiments, microarrays may provide highthroughput and simultaneous analysis of mRNA for hundreds or thousands of genes. This method is semi-quantitative, sensitive to low abundance transcripts that are represented on a given array and has been successfully used to study plant responses to various biotic and abiotic factors in Arabidopsis thaliana (Reymond et al., 2000; Cheong et al., 2002; Seki et al., 2002), Medicago truncatula (Fedorova et al., 2002; Küster et al., 2004), soybean (Glycine max) (Maguire et al., 2002; Thibaud-Nissen et al., 2003) and chickpea (Cicer arietinum) (Coram and Pang, 2005; Mantri et al., 2007). Two major types of microarrays are used: cDNA microarrays and oligonucleotide microarrays. cDNA arrays comprise complementary DNA (cDNA) probes of ~300–5000 nucleotides, each representing a gene, that are immobilized to a solid surface such as a glass slide, nitrocellulose or nylon membrane. The probes are usually PCR products generated from cDNA libraries or from genomic DNA. Oligonucleotide microarrays or ‘GeneChips’ comprise 20–80 nucleotide probes synthesized either in situ (on-chip), by photo-lithography (Fodor et al., 1991) or by conventional synthesis followed by on-chip immobilization. On the chip, a gene is represented by a set of oligos, thus conferring greater specificity. Following hybridization of the probe (usually mRNA or cDNA), GeneChip arrays employ a single channel detection system. In general, the oligonucleotide arrays require extensive sequence data and computational input to produce the gene-specific oligonucleotide probes, and the manufacture and data analyses of arrays require proprietary technology. Indeed, the cost of oligonucleotide microarray fabrication and usage is substantially higher than for cDNA microarrays. Alternatively, cDNA microarrays may be constructed using existing cDNA libraries, thus fabrication is dependent upon the availability of a suitable cDNA clone collection. They may also be used in ‘two-colour’ co-hybridization experiments that allow direct comparison of transcript abundance among two mRNA populations of interest (treatment and control) on the same slide. This approach helps to remove experimental variability introduced during

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array fabrication and individual hybridizations. A cDNA microarray system measures the relative increase or decrease in mRNA between different treatments or tissues of interest. A prerequisite for designing a cDNA microarray is the existence of a suitable cDNA library or expressed sequence tag (EST)-enriched library that has been constructed to contain genes related to the biological condition under investigation. A search of GenBank for lentil sequences (conducted on 06/10/07) returned no ESTs and only 485 genome survey sequences (GSS). In comparison, there were 1960 ESTs and 48,339 GSS from chickpea, 1333 ESTs and 50,208 GSS from cowpea (Vigna unguiculata), and 87,189 ESTs from field pea (Pisum sativum). Thus, lentil may be regarded as an orphan crop when it comes to gene discovery and functional genomics studies. However, considerable genome sequence and ESTs are available for the model legume species Medicago truncatula, which will benefit lentil through comparative and syntenic approaches (Zhu et al., 2005; Phan et al., 2007). Medicago truncatula cDNA microarrays (commercially available or custom made) may thus be used to study gene expression in lentil. Although M. truncatula microarrays have not yet been used to study gene expression in lentil, a multi-species cDNA microarray (PulseChip) was used to identify homologous genes differentially regulated in lentil in response to the important fungal pathogen Ascochyta lentis (B. Mustafa, 2007, unpublished results). The PulseChip comprised ESTs from cDNA libraries enriched for genes involved in the reactions between chickpea and Ascochyta rabiei, and between Lathyrus sativus and Mycosphaerella pinodes. Differential gene transcript profiles were assessed among the resistant (ILL 7537) and susceptible (ILL 6002) lentil genotypes at 6, 24, 48, 72 and 96 h after inoculation (hai) with A. lentis (AL4 isolate). The non-redundant differentially expressed genes for each accession and time point were hierarchically clustered using Euclidean metrics. In total, 25 differentially expressed sequences were up-regulated and 56 were down-regulated in ILL 7537 and 26 were upregulated and 44 were down-regulated in ILL 6002. Several candidate defence genes were characterized from lentil including; a b-1, 3-glucanase, a pathogenesis-related protein from the Bet v I family, a pea disease resistance response protein 230 (DRR230-a), a disease resistance response protein (DRRG49-C), a PR4 type gene and a gene encoding an antimicrobial SNAKIN2 protein, all of which have been fully gene sequenced (Ford et al., 2007). Several transcription factors were also recovered at 6 hai and future aims will be to further biologically characterize these and earlier responses, to gain a comprehensive understanding of the key pathogen recognition and defence pathways to A. lentis in lentil. Also, the full-length gene sequences will be used in transgenic studies to further characterize function.

11.3. Genetic Manipulation through Transformation Commonly, the particle bombardment and the Agrobacterium tumefaciens infection methods have been used to introduce genes with novel functions

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not readily available in the gene pool of that species. With the explosion of sequence information available in the databases, transformation systems have also become useful tools to study gene function via RNA interference ‘knockout’, T-DNA insertion or transforming a genotype lacking a particular gene. Thus a robust, reproducible and efficient transformation system combined with a protocol to regenerate complete fertile plants from transformed cells is essential to fully study plant gene functions. Following the initial report of shoot regeneration (Bajaj and Dhanju, 1979) from apical meristems, shoot regeneration was achieved routinely with various explants such as apical meristems (Bajaj and Dhanju, 1979), stem nodes (Polanco et al., 1988; Singh and Raghuvanshi, 1989; Ahmad et al., 1997), cotyledonary node (Warkentin and McHughen, 1992; Sarker et al., 2003a), epicotyls (Williams and McHughen, 1986), decapitated embryo, embryo axis and immature seeds (Polanco and Ruiz, 2001) as well as cotyledonary petioles (Khawar and Özcan, 2002). The induction of functional roots on in vitro-developed shoots has been the most challenging part of lentil micropropagation. To date, no reliable and reproducible efficient rooting protocol is available. The difficulty to induce roots is thought to be associated with the use of cytokinins to obtain multiple shots from the initial explants (Mohamed et al., 1992; Sarker et al., 2003b). Among the several studies conducted on root induction from shoots, Fratini and Ruiz (2003) reported 95% rooting efficiency from nodal segments cultured in an inverted orientation in media with 5 μM indole acetic acid (IAA) and 1 μM kinetin (KN). Sarker et al. (2003b) reported 30% rooting efficiency on Murashige and Skoog (MS) medium supplemented with 25 mg/l indole butyric acid (IBA). More recently Newell et al. (2006) obtained 100% rooting efficiency on nodal micro-cuttings placed inverted in a mixture of sphagnum peat, coarse river sand and perlite at a 0.5:2:2 ratio, and concluded that the improved rooting efficiency was due to greater aeration. To date, transformation of lentil has been reported through A. tumefaciens-mediated gene transfer (Warkentin and McHughen, 1992; Lurquin et al., 1998; Sarker et al., 2003a) and biolistic transformation including electroporation (Chowrira et al., 1996) and particle bombardment (Gulati et al., 2002; Mahmoudian et al., 2002). Warkentin and McHughen (1992) first reported the susceptibility of lentil to A. tumefaciens and later evaluated a number of explant types including: shoot apices, epicotyl, root, cotyledons and cotyledonary nodes. All explants showed transient b-glucuronidase (GUS) expression at the wound sites except cotyledonary nodes, which were subsequently transformed by Sarker et al. (2003b). Öktem et al. (1999) reported the first transient and stable chimeric transgene expression on cotyledonary lentil nodes using particle bombardment. Gulati et al. (2002) reported the regeneration of the first fertile transgenic lentil plants on MS medium with 4.4 μM benzyladenine (BA), 5.2 μM gibberellic acid (GA3) and chlorsulfuron (5 nM for 28 days and 2.5 nM for the rest of the culture period), followed by micrografting and transplantation in soil. Most recently, Khatib et al. (2007) have developed herbicide-resistant lentil through A. tumefaciens-mediated transformation. This was achieved

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with a plasmid construct pCGP1258, harbouring the bar gene conferring resistance to the herbicide glufosinate ammonium that was transformed using A. tumefaciens strain AgL0. Three lentil lines, ILL 5582, ILL 5883 and ILL 5588, were used and a high selection pressure of 20 mg/l of glufosinate was applied to the explants for 18 weeks. Survival shoots were subsequently grafted onto non-transgenic rootstock and plantlets were transferred to soil and acclimatized. The presence of the transgene was confirmed by PCR and the gene function was confirmed via herbicide application.

11.4. Molecular Screening of Existing Germplasm Resources The International Center for Agricultural Research in the Dry Areas (ICARDA) is participating in the genetic diversity analysis of the global lentil germplasm collections held by the Consultative Group of International Agricultural Research’s (CGIAR) research centres. As a part of Subprogram 1, of the CGIAR’s Generation Challenge Program, a project will identify a ‘composite collection’ of germplasm for individual crops and characterize each composite set using anonymous molecular markers. The overall goal of this project is to study diversity across given genera and identify genes for resistance to biotic and abiotic stresses that can be used in crop improvement programmes. ICARDA is responsible for creating the composite collection for lentil and analysing these accessions for diversity using microsatellite markers. ICARDA has the global mandate for lentil improvement and holds the largest global collection of genetic resources with >11,000 accessions. From this collection, a global composite collection of 1000 lentil accessions landraces, wild relatives, elite germplasm and cultivars has been established at ICARDA (Furman, 2006). These will be analysed for molecular diversity at 30 simple sequence repeat (SSR) loci to: (i) obtain detailed information on baseline levels of genetic variability within the composite collection of lentil; (ii) determine geographic patterns in the genetic structure of the composite collection; and (iii) provide genome-wide marker information for future analysis of stress functional and comparative genomics in the Challenge Program.

11.5. Molecular Markers: New Resources Most recently, many resources have gone towards the development of microsatellite and gene-specific type markers in lentil, preferentially for the development of markers for use in marker-assisted trait selection. Microsatellite or SSR markers are generally codominant, unilocus, multi-allelic and species specific. Produced from primers designed to the flanking sequence of mainly di- and trinucleotide repeats, they have become a marker of choice in many species to gain understanding of genetic relationships, evolutionary insights and for molecular mapping.

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The successful isolation of microsatellite markers involves several distinct steps: 1. Constructing and screening the small insert genomic library with SSR motifs. 2. Sequencing the positive clones. 3. Designing primers that can amplify SSR loci. 4. Determining polymorphic SSR primers. At each stage, there is the potential to lose microsatellite loci, and thus the number of loci that will finally constitute the working primer set will be a fraction of the original number of clones sequenced. Therefore, the development of microsatellite markers requires a considerable amount of laboratory effort. Constructing a small insert genomic library is advantageous for microsatellite cloning for two reasons. First, a small insert library can contain a small array of microsatellites that are more stable in Escherichia coli. Second, positive clones can be sequenced without subcloning (Weising et al., 1998). For the library construction, various restriction enzymes, such as PstI, TaqI, AluI, RsaI, MobI and Sau3AI, have been used in different plant species (Jarret and Bowen, 1994; Röder et al., 1995; Winter et al., 1999). In general, restriction enzymes that are four-base-pair cutters are superior to six-base-pair cutters for acquiring a large number of small genomic fragments that represent the entire genome (Weising et al., 1998). However, depending on the genomic sequence, different four-base-pair cutters may have different efficiencies with regard to cloning microsatellites. A Sau3AI genomic library was constructed from the cultivated accession ILL 5588 and screened with (GT)10, (GA)10, (GC)10, (GAA)8, (TA)10 and (TAA) probes. Dinucleotide repeats were observed more frequently than trinucleotide repeats or other motifs (Table 11.1). The microsatellite motifs were classified as perfect, imperfect, compound perfect or compound imperfect repeats according to the modified classification of Weber (1990). The simple/perfect repeats were predominant (56.8%), followed by compound/perfect (16.1%). The compound/imperfect (12.7%) occurred least often (Table 11.1). Among the perfect repeats, (CA/GT)n motifs were the most abundant, comprising 24.2% of the isolated clones, followed by (AT/ TA)n repeats (8.9%). Most recently, 126 new SSR markers were generated using a magnetic bead capture method at Washington State University by the United States Department of Agriculture (USDA) Agriculture Research Service (ARS) under the direction of Weidong Chen and P.N. Rajesh. EST-based intron-targeted amplified polymorphic (ITAP) markers have also recently been developed from close relative species and applied to lentil. ESTs were compared from phylogenetically distant M. truncatula, Lupinus albus and G. max species to produce 500 ITAP markers that could be applied to related temperate legume species such as lentil (Phan et al., 2007). Also, 126 M. truncatula cross-species markers were used to generate comparative genetic maps of lentil (Lens culinaris Medik.) and white lupin (L. albus Linn.) and macrosyntenic relationships between lentil and field pea were observed (Phan et al., 2007).

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Table 11.1. Frequency of microsatellite motif type observed in the lentil genomic library (Source: M. Baum, 2007, unpublished results). Type

Microsatellite motif

Simple

Perfect

CA/GT CG/GC CT/GA CTT/GAA AT/TA ATT/TAA Others types Total

Imperfect

CA/GT CG/GC CT/GA CTT/GAA AT/TA ATT/TAA Other types Total

Compound

Perfect Imperfect Total

Overall total

Number

Occurence (%)

57 2 7 3 21 7 37

24.2 0.8 3.0 1.3 8.9 3.0 15.7

134

56.8

21 0 1 0 3 1 8

8.9 0.0 0.4 0.0 1.3 0.4 3.4

34

14.4

38 30 68

16.1 12.7 28.8

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100

11.6. Genome and Gene Mapping In general, whole genome analysis is intended for the following four purposes: (i) development of molecular markers such as restriction fragment length polymorphism (RFLP), EST, resistant gene analogue (RGA) and single nucleotide polymorphism (SNP); (ii) genetic mapping of the molecular markers and traits using suitable mapping populations; (iii) gene discovery; and (iv) sequencing. Furthermore, development of whole genome maps is not only useful to identify molecular markers linked to the traits of interest but also for genome characterization such as to determine the recombination rate at different parts of the genome, to classify the genome into gene rich and gene poor regions and to discover the repetitive element abundant regions. Since lentil has little genomic sequence available, the initial genetic mapping efforts have been initiated with arbitrary markers such as random amplified polymorphic DNA (RAPD), AFLP and inter simple sequence repeat (ISSR) markers which are designed to scan the entire genome and amplify multiple bands at low stringent conditions. Although such random markers are preferred for initial mapping analysis, they are often not consistent or reproducible and the results vary from lab to lab. However, the

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newly developed gene/locus specific markers are reproducible and represent definite genomic regions. Although a few agronomically important traits are governed by single genes, most are quantitative in nature and governed by quantitative trait loci (QTL), which are influenced by environmental factors. Since the expression of a QTL is likely to vary among populations and environments, their genomic location and effect must be determined for a specific genetic background and environment (Bagge et al., 2007). In such cases, mapping arbitrary markers will be less informative than mapping ESTs in association with traits of interest. In addition, if the genes are already available for phenotypic traits, designing function-associated markers will have tremendous application in marker-assisted breeding. These markers are essentially polymorphic sites within the genes that contribute directly to phenotypic trait variation (Bagge et al., 2007). Hence, in order to effectively apply genomics in breeding, the availability of genomic tools and extensive genomic information is required including genome linkage maps that are of usable density, built with robust and reproducible markers that may be transferable for integration across genetic backgrounds. A summary of the available comprehensive linkage maps and the types of markers and crosses used in their construction is provided (Table 11.2). Although genetic mapping (linkage analysis) began in lentil in 1984 (Zamir and Ladizinsky, 1984), DNA-based molecular markers were not used until 1989. Havey and Muehlbauer (1989) mapped RFLP markers generated from a genomic library using an F2 population derived from an interspecific cross (Lens orientalis × L. culinaris). In spite of the advantage of developing a linkage map rapidly, an F2 population is not a permanent resource for long-term mapping studies and limits the number and type of phenotypes that may be assessed. Eujayl et al. (1998a) generated the first linkage map using recombinant inbred lines (RILs) with 177 markers (89 RAPD, 79 AFLP, six RFLP and three morphological markers). Of late, there have been significant efforts to map single locus specific markers. As mentioned

Table 11.2. Published genetic linkage maps for lentil; mapping populations and types of markers mapped. Population mapped

Marker types mappeda

Citation

Interspeciﬁc F2 Inter-subspeciﬁc RILb Intraspeciﬁc F2 Intraspeciﬁc RIL Inter-subspeciﬁc F2 Inter-subspeciﬁc RIL Intraspeciﬁc RIL

RFLP, isozymes, morphological RFLP, RAPD, AFLP RAPD, ISSR, RGA RAPD, ISSR, AFLP RAPD, ISSR, AFLP, SSR AFLP, SSR SSR, ITAP

Havey and Muehlbauer (1989) Eujayl et al. (1998a) Rubeena et al. (2003) Kahraman et al. (2004) Durán et al. (2004) Hamwieh et al. (2005) Phan et al. (2007)

a AFLP, ampliﬁed fragment length polymorphism; ISSR, inter simple sequence repeat; ITAP, intron-targeted ampliﬁed polymorphic; RAPD, random ampliﬁed polymorphic DNA; RFLP, restriction fragment length polymorphism; RGA, resistant gene analogue; SSR, simple sequence repeat. b RIL, recombinant inbred line.

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previously, Phan et al. (2007) recently constructed the first linkage map using sequence-based and gene-specific markers. P.N. Rajesh (2007, unpublished results) mapped PCR-based RFLP markers, cross-species gene specific (CSS) markers and SSR markers from other closely related species such as pea and M. truncatula using an intraspecific F2 population derived from crossing ‘Pardina’ × ‘Pennell’. Such cross-species markers will help to establish macrosynteny between lentil and other legumes. In addition, SNPs were discovered from 16,158 bp CSS and 4270 bp RFLP sequences. One SNP was detected every 311 bp in CSS and every 251 bp in RFLP sequences between the two cultivars. Also, one SNP was detected every 281 bp in CSS between the parental lines, ILL 5588 and L692-16-1(s), used for map construction by Hamwieh et al. (2005). At ICARDA an F2 population of a wider cross, L92-013 (ILL 5588 (L. culinaris) × L692-16-1(s) (L. orientalis)) was used to develop RILs with an increased chance for polymorphism among parents and segregating progeny by advancing individual F2 plants to F6 using single seed descent (SSD) (Eujayl et al., 1998a). Using a logarithmic odds (LOD) score of 4.0 and maximum distance of 25 cM, a total of 177 markers (89 RAPD, 79 AFLP, six RFLP and three morphological markers) were mapped in seven major linkage groups covering 1073 cM. Marker distances ranged from 0.3 cM to 23.4 cM with an average spacing of 6 cM. RAPD markers were more evenly distributed among linkage groups than AFLP markers, which tended to cluster particularly in linkage group 2. The morphological markers, pod indehiscence (Pi), seedcoat pattern (Scp) and flower colour (W) were also mapped. Building on this, another map comprising 283 markers distributed over 14 linkage groups was constructed, including 39 microsatellite markers (Table 11.3) and five morphological markers of seedcoat pattern (Scp), flower colour (W), pod indehiscence (Pi), Fusarium wilt resistance (Fw) and radiation frost tolerance locus (Rf). The map was constructed using 86 recombinant inbred lines derived from the cross ILL 5588 × L 692-16-1(s), which had been previously used for the lentil linkage map (Eujayl et al., 1997, 1998a, b, 1999). The new map spanned 750.5 cM (Kosambi function) with an average distance between two markers of 2.7 cM. The Fusarium vascular wilt resistance was localized on LG 6, and this resistance gene was flanked by microsatellite marker SSR59-2B and AFLP marker p17m30710 by a distance of 8.0 cM and 3.5 cM, respectively. Further analysis for the association between these markers and Fw was confirmed. However, only SSR59-2B was closely linked with Fw at the estimated linkage distance 19.7 cM (Fig. 11.1; Hamwieh et al., 2005).

11.7. Trait Mapping, QTL Analysis and Marker-assisted Breeding In lentil, several morphological markers exist such as colour of the cotyledon (Yc), anthocyanin in stem (Gs), seedcoat pattern or spotting (Scp), pod dehiscence-indehiscence (Pi), early flowering (Sn) and ground colour of the seed (Ggc). These were mapped onto the lentil genome (Eujayl et al., 1998a;

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Table 11.3. Distribution of SSR markers within the integrated linkage map of lentil (Source: Hamwieh et al., 2005). Linkage group

Length of the linkage group (cM)

Total no. of markers

No. of SSR markers

1 2 3 4 5 6 7 8 9 10 11 12 13 14

93.3 63.5 171.9 90.1 69.6 98.3 47.4 41.6 26.5 13.4 8.5 3.5 7.7 15.2

50 47 41 45 19 35 21 10 3 3 2 2 3 2

12 4 4 5 2 4 1 5 1 0 0 0 0 1

Total

750.5

283

39

Durán et al., 2004). These traits exhibited monogenic dominant mode of inheritance and hence are qualitative in nature (Durán et al., 2004). Other mapped qualitatively inherited traits include; Fusarium vascular wilt resistance (Fw) (Eujayl et al., 1998b), anthracnose disease resistance (Lct-2) (Tullu et al., 2003) and seedling frost tolerance (Frt) (Eujayl et al., 1999). To date, quantitatively inherited traits have been mapped by Durán et al. (2004) who detected five QTL for height of the first ramification, three for plant height, five for flowering, seven for pod dehiscence, one for shoot number and one for seed diameter. Five and four QTL were identified for winter survival and winter injury, respectively, and were mapped using a population of 106 RILs derived from WA8649090 × ‘Precoz’ (Kahraman et al., 2004). In this study, the experiments were conducted in multiple locations and only one of five QTL was expressed in all environments. Primary mapping of Ascochyta blight resistance using an F2 population derived from ILL 7537 × ILL 6002 identified three QTL (QTL-1, QTL-2 and QTL-3) accounting for 47% (QTL-1 and QTL-2) and 10% (QTL-3) of disease variance (Shaika, 2004). Identification and mapping of QTL conferring resistance to Stemphylium blight, rust and white mould fungal diseases using recombinant inbred line populations are underway (W. Chen, Washington State, 2007, personal communication), as is mapping of physical seed quality traits such as size, shape and colour, as well as resistance to Ascochyta blight at maturity growth stages (R. Ford, 2007, unpublished results). To date, most quantitative traits have been mapped using F2 populations (<100). Since quantitative traits are influenced by both genetic and

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Fig. 11.1. A genetic linkage map of Lens sp. based on microsatellite, AFLP, RAPD and morphological markers. The marker names beginning with an asterisk are those markers mapped by Eujayl et al. (1998b). The values on the left side of the individual linkage groups represent distance in centimorgans calculated using the Kosambi mapping function (Source: reproduced from Hamwieh et al., 2005).

environmental effects, RILs or near isogenic lines (NILs) would be more suitable populations to accurately dissect their components. One of the primary objectives of associating markers with phenotypic traits is to expedite crop breeding through marker-assisted selection (MAS).

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Ideally, the genes controlling a trait of interest are the perfect marker for MAS. However, this is often made difficult because cloning of the genes is labour intensive and time consuming. Alternatively, marker(s) that are tightly linked to and flanking a gene locus that conditions a sizable portion of the genetic variation accounting for the trait may be selected for with the premise that the associated chromosomal region contains the functional gene(s). Often, genetically linked markers to traits of interest are identified by coarse mapping and these have limited use in MAS because of the distance and hence chance of recombination between marker and actual gene locus. Therefore, genomic regions where the trait is mapped should be characterized at high resolution (since recombination rates may vary at different genomic regions) and be validated across genetic backgrounds, in order to determine their utility in MAS. Also, physical characterization of genomic regions of interest will facilitate cloning of the gene to develop direct markers (candidate genes) and/or physically closer markers to the gene, increasing the reliability for MAS. Marker types most useful for MAS should be locus specific, highly reproducible and easy to discern. These include sequence tagged site (STS), sequence characterized amplified region (SCAR) or allele specific amplified primer (ASAP), specific polymorphic locus amplification test (SPLAT) and PCR-based RFLP markers. When locus specific markers are not size polymorphic among the parental lines used in the breeding programmes, sequence discriminative methods are required. These include SNP, cleaved amplified polymorphic site (CAPS) and derived CAPS (dCAPS) markers. Meanwhile, there are several markers available for different traits that have the potential for use in MAS and gene pyramiding (Table 11.4). These include SCARW19 and SCARB18 linked to and flanking the AbR1 A. lentis resistance loci (Nguyen et al., 2001; Tar’an et al., 2003). These enabled successful pyramiding of the AbR1 and ral2 A. lentis resistance loci together with the LCt2 Colletotrichum truncatum (anthracnose) resistance loci (Tar’an et al., 2003).

11.8. The Future of Lensomics To better target genes that are functionally associated with traits of interest for breeding purposes, several approaches are predicted for the future. These include the use of emerging genomic sequence for the development of gene family specific degenerate primers. This approach has already been taken, to identify novel defence-related genes within various resistance genes families. RGAs are a family of sequences associated with pathogen defence but with unknown function at the time of isolation. These have been isolated and characterized from lentil using degenerate oligonucleotide primers (Yaish et al., 2004; R. Ford, 2007, unpublished results), and recently associated with defence to A. lentis (B. Mustafa, 2007, unpublished results). Yaish et al. (2004) isolated 32 RGA sequences from ILL 5588 using degenerate primers designed to conserve motifs in the NBS domain of NBS–LRR resistance

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Table 11.4. Molecular markers closely associated with desirable lentil breeding traits for use in marker-assisted selection.

Trait mapped

Associated molecular markers

Fusarium wilt resistance (Fw) Ascochyta blight resistance (AbR1) Ascochyta blight resistance (ral 2) Ascochyta blight resistance (mapped as a QTL) Anthracnose resistance (Lct 2) Frost tolerance (Frt) Winter hardiness Fusarium wilt resistance (Fw)

OPK15 RV01, RB18, SCARW19 UBC227, OPD-10 C-TTA/M-AC (QTL1 and QTL2), M20 (QTL3) OPE06, UBC704 OPS-16 UBC808-12 SSR59-2B, p17m30710

Citation Eujayl et al. (1998a) Ford et al. (1999) Chowdhury et al. (2001) Rubeena et al. (2003) Tullu et al. (2003) Eujayl et al. (1999) Kahraman et al. (2004) Hamwieh et al. (2005)

proteins. Predicted amino acid sequences showed they contained typical conserved motifs present in the majority of known plant NBS–LRR genes and that they phylogenetically belonged to the TIR-NBS-LRR subclass. R. Ford (2007, unpublished results) isolated a further five TIR-NBS-LRR and one Pto kinase type RGA sequences from ILL 7537. Genetic mapping of RGA markers will potentially identify the genomic regions where the genes are located that functionally regulate signal transduction and/or defence pathways. This will also facilitate map-based cloning of the resistance genes. Other major gene families of interest should become the targets for future isolation and trait association mapping. These may underpin the control of expression of other breeding goals (such as disease resistance, abiotic tolerance and physical attributes) and include those thought to act as transcription factors and in key biochemical pathways (i.e. Myb genes). With the advancement in functional genomics, expression QTL (eQTL) can be identified for the traits of interest by coupling global genome gene expression profiling and suitable genetic materials and analysis. Since eQTL affect the expression of the genes for the trait of interest, the markers linked to this eQTL will have enormous reliability in MAS compared to the markers identified by traditional QTL analysis. Other biotechnology approaches such as proteomics and metabolomics will no doubt begin to emerge for lentil, in order to discover and better characterize the functional mechanisms behind the breeding targets. Ultimately, and with sufficient funding, the combination of lentil ‘omics’ data will enable the precise formulation of superior and high-yielding genotypes, adapted to a multitude of environments and market preferences.

References Ahmad, M., Fautrer, A.G., McNeil, V., Hill, G.D. and Burritt, D.J. (1997) In vitro propagation of Lens species and their F1 interspecific hybrids. Plant Cell Tissue and Organ Culture 47, 169–176.

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R. Ford et al. Bachem, C., Oomen, R. and Visser, R. (1998) Transcript imaging with cDNA-AFLP: a step-by-step protocol. Plant Molecular Biology Reporter 16, 157–173. Bagge, M., Xia, X. and Lubberstedt, T. (2007) Functional markers in wheat. Current Opinion in Plant Biology 10, 211–216. Bajaj, Y.P.S. and Dhanju, M.S. (1979) Regeneration of plants from apical meristem tips of some legumes. Current Science 48, 906–907. Cheong, Y.H., Chang, H.S., Gupta, R., Wang, X., Zhu, T. and Luan, S. (2002) Transcriptional profiling reveals novel interactions between wounding, pathogen, abiotic stress, and hormonal responses in Arabidopsis. Plant Physiology 129, 661–677. Chowdhury, M.A., Andrahennadi, C.P., Slinkard, A.E. and Vandenberg, A. (2001) RAPD and SCAR markers for resistance to ascochyta blight in lentil. Euphytica 118, 331–337. Chowrira, G.M., Akella, V.F., Fuerst, P.E. and Lurquin, P.F. (1996) Transgenic grain legumes obtained by in planta electroporation-mediated gene transfer. Molecular Biotechnology 5, 85–86. Coram, T.E. and Pang, E.C.K. (2005) Isolation and analysis of candidate Ascochyta blight defence genes in chickpea. Part II: Microarray expression analysis of putative defence-related ESTs. Physiological and Molecular Plant Pathology 66, 201–210. DeRisi, J., Iyer, V. and Brown, P. (1997) Exploring the metabolic and genetic control of gene expression on a genomic scale. Science 278, 680–686. Diatchenko, L., Lau, Y.-F.C., Campbell, A.P., Chenchik, A., Moqadam, F., Huang, B., Lukyanov, S., Lukyanov, K., Gurskaya, N., Sverdlov, E.D. and Siebert, P.D. (1996) Suppression subtractive hybridization: a method for generating differentially regulated or tissue-specific cDNA probes and libraries. Proceedings of the National Academy of Science 93, 6025–6030. Durán, Y., Fratini, R., García, P. and Vega, M.P. (2004) An intersubspecific genetic map of Lens. Theoretical and Applied Genetics 108, 1265–1273. Eujayl, I., Baum, M., Erskine, W., Pehu, E. and Muehlbauer, F.J. (1997) The use of RAPD markers for lentil genetic mapping and the evaluation of distorted F2 segregation. Euphytica 96, 405–412. Eujayl, I., Baum, M., Powell, W., Erskine, W. and Pehu, E. (1998a) A genetic linkage map of lentil (Lens sp.) based on RAPD and AFLP markers using recombinant inbred lines. Theoretical and Applied Genetics 97, 83–89. Eujayl, I., Erskine, W., Bayaa, B., Baum, M. and Pehu, E. (1998b) Fusarium vascular wilt in lentil: inheritance and identification of DNA markers for resistance. Plant Breeding 117, 497–499. Eujayl, I., Erskine, W., Baum, M. and Pehu, E. (1999) Inheritance and linkage analysis of frost injury in a lentil population of recombinant inbred lines. Crop Science 39, 639–642. Fedorova, M., van de Mortel, J., Matsumoto, P.A., Cho, J., Town, C.D., VandenBosch, K.A., Gantt, J.S. and Vance, C.P. (2002) Genome-wide identification of nodulespecific transcripts in the model legume Medicago truncatula. Plant Physiology 130, 519–537. Fodor, S., Read, J., Pirrung, M., Stryer, L., Lu, A. and Solas, D. (1991) Light-directed, spatially addressable parallel chemical synthesis. Science 251, 767–773. Ford, R., Pang, E.C.K. and Taylor, P.W.J. (1999) Genetics of resistance to ascochyta blight of lentil and the identification of closely linked markers. Theoretical and Applied Genetics 98, 93–98. Ford, R., Viret, L., Pang, E.C.K., Taylor, P.W.J., Materne, M. and Mustafa, B. (2007) Defence responses in lentil to Ascochyta lentis. In: Proceedings of the Australasian

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Plant Pathology Conference, Adelaide, Australia. The Australasian Plant Pathology Society, Adelaide, Australia, 64 pp. Fratini, R. and Ruiz, M.L. (2003) A rooting procedure for lentil (Lens culinaris Medik.) and other hypogeous legumes (pea, chickpea and Lathyrus) based on explant polarity. Plant Cell Reports 21, 726–732. Furman, B.J. (2006) Methodology to establish a composite collection: case study in lentil. Plant Genetic Resources: Conservation and Utilization 4, 2–12. Gulati, A., Schryer, P. and McHughen, A. (2002) Production of fertile transgenic lentil (Lens culinaris Medik) plants using particle bombardment. In Vitro Cellular and Developmental Biology – Plant 38, 316–324. Hamwieh, A., Udupa, S.M., Choumane, W., Sarker, A., Dreyer, F., Jung, C. and Baum, M. (2005) A genetic linkage map of lentil based on microsatellite and AFLP markers and localization of Fusarium vascular wilt resistance. Theoretical and Applied Genetics 110, 669–677. Havey, M.J. and Muehlbauer, F.J. (1989) Linkages between restriction fragment length, isozyme, and morphological markers in lentil. Theoretical and Applied Genetics 77, 395–401. Jarret, R.L. and Bowen, N. (1994) Simple sequence repeats (SSRs) for sweet potato germplasm characterization. Plant Genetic Resources Newsletter 100, 9–11. Kahraman, A., Kusmenoglu, I., Aydin, N., Aydogan, A., Erskine, W. and Muehlbauer, F.J. (2004) QTL mapping of winter hardiness genes in lentil. Crop Science 44, 13–22. Khatib, S., Koudsieh, B., Ghazal, J.E., Barton, H., Tsujimoto and Baum, M. (2007) Developing herbicide resistant lentil (Lens culinaris Medikus subsp. culinaris) through Agrobacterium mediated transformation. Arab Journal of Plant Protection 25(2), 185–192. Khawar, K.M. and Özcan, S. (2002) Effect of indole-3-butyric acid on in vitro root development in lentil (Lens culinaris Medik.). Turkish Journal of Botany 26, 109–111. Küster, H., Hohnjec, N., Krajinski, F., El Yahyaoui, F., Manthey, K., Gouzy, J., Dondrup, M., Meyer, F., Kalinowski, J., Brechenmacher, L., van Tuinen, D., Gianinazzi-Pearson, V., Puhler, A., Gamas, P. and Becker, A. (2004) Construction and validation of cDNA-based Mt6k-RIT macro- and microarrays to explore root endosymbioses in the model legume Medicago truncatula. Journal of Biotechnology 108, 95–113. Liang, P. and Pardee, A. (1992) Differential display of eukaryotic messenger RNA by means of the polymerase chain reaction. Science 257, 967–971. Lurquin, P.F., Cai, Z., Stiff, C.M. and Fuerst, P. (1998) Half embryo cocultivation technique for estimating the susceptibility of pea (Pisum sativum L.) and lentil (Lens culinaris Medik) cultivars to Agrobacterium tumefaciens. Molecular Biotechnology 9, 175–179. Maguire, T.L., Grimmond, S., Forrest, A., Iturbe-Ormaetze, I., Meksem, K. and Gresshoff, P. (2002) Tissue-specific gene expression in soybean (Glycine max) detected by cDNA microarray analysis. Journal of Plant Physiology 159, 1361–1374. Mahmoudian, M., Yücel, M. and Öktem, H.A. (2002) Transformation of lentil (Lens culinaris M.) cotyledonary nodes by vacuum infiltration of Agrobacterium tumefaciens. Plant Molecular Biology Reporter 20, 251–257. Mantri, N.L., Ford, R., Coram, T.E. and Pang, E.C.K. (2007) Transcriptional profiling of chickpea genes differentially regulated in response to high-salinity, cold and drought. BMC Genomics 8, 303. Mohamed, M.F., Read, P.E. and Coyne, D.P. (1992) Plant regeneration from in vitro culture of embryonic axis explants in common and tepary beans. Journal of the American Society of Horticultural Science 117, 332–336.

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R. Ford et al. Newell, C.A., Growns, D.J. and McComb, J. (2006) Aeration is more important than shoot orientation when rooting lentil (Lens culinaris Medik.) Cv. ‘Digger’ microcuttings in vitro. In Vitro Cellular and Developmental Biology – Plant 42, 197–200. Nguyen, T.T., Taylor, P.W.J., Brouwer, J.B., Pang, E.C.K. and Ford, R. (2001) A novel source of resistance in lentil (Lens culinaris ssp. culinaris) to ascochyta blight caused by Ascochyta lentis. Australasian Plant Pathology 30, 211–215. Öktem, H.A., Mahmoudian, M., Eyidooan, F. and Yücel, M. (1999) GUS gene delivery and expression in lentil cotyledonary nodes using particle bombardment. Lens Newsletter 26, 3–6. Phan, H.T.T., Ellwood, S.R., Hane, J.K., Ford, R., Materne, M. and Oliver, R.P. (2007) Extensive macrosynteny between Medicago truncatula and Lens culinaris ssp. Culinaris. Theoretical and Applied Genetics 114, 549–558. Polanco, M.C. and Ruiz, M.L. (2001) Factors that affect plant regeneration from in vitro culture of immature seeds in four lentil (Lens culinaris Medik.) cultivars. Plant Cell Tissue and Organ Culture 66, 133–139. Polanco, M.C., Pelaez, M.I. and Ruiz, M.L. (1988) Factors affecting callus and shoot formation from in vitro cultures of Lens culinaris Medik. Plant Cell Tissue and Organ Culture 15, 175–182. Reymond, P., Weber, H., Damond, M. and Farmer, E.E. (2000) Differential gene expression in response to mechanical wounding and insect feeding in Arabidopsis. Plant Cell 12, 707–719. Röder, M.S., Plaschke, J., König, S.U., Börner, A., Sorrells, M.E., Tanksley, S.D. and Ganal, M.W. (1995) Abundance, variability and chromosomal location of microsatellites in wheat. Theoretical and Applied Genetics 246, 327–333. Rubeena, Ford, R. and Taylor, P.W.J. (2003) Construction of an intraspecific linkage map of lentil (Lens culinaris ssp. culinaris). Theoretical and Applied Genetics 107, 910–916. Sarker, R.H., Biswas, A., Mustafa, B.M., Mahbub, S. and Hoque, M.I. (2003a) Agrobacterium-mediated transformation of lentil (Lens culinaris Medik.). Plant Tissue Culture 13, 1–12. Sarker, R.H., Mustafa, B.M., Biswas, A., Mahbub, S., Nahar, S.M.M., Mahbub, S., Hashem, R. and Hoque, M.I. (2003b) In vitro regeneration in lentil (Lens culinaris Medik.). Plant Tissue Culture 13, 155–163. Schena, M., Shalon, D., Davis, R. and Brown, P. (1995) Quantitative monitoring of gene expression patterns with a complimentary DNA microarray. Science 270, 467–470. Seki, M., Narusaka, M., Ishida, J., Nanjo, T., Fujita, M., Oono, Y., Kamiya, A., Nakajima, M., Enju, A., Sakurai, T., Satou, M., Akiyama, K., Taji, T., Yamaguchi-Shinozaki, K., Carninci, P., Kawai, J., Hayashizaki, Y. and Shinozaki, K. (2002) Monitoring the expression profiles of 7000 Arabidopsis genes under drought, cold and high-salinity stresses using a full-length cDNA microarray. The Plant Journal 31, 279–292. Shaika, R. (2004) Gene pyramiding in lentil: mapping resistance loci to Ascochyta lentis in the cross ILL7537 × ILL5588. PhD thesis, The University of Melbourne, Australia. Shalon, D., Smith, S. and Brown, P. (1996) A DNA microarray system for analysing complex DNA samples using two-colour fluorescent probe hybridization. Genome Research 6, 639–645. Singh, R.K. and Raghuvanshi, S.S. (1989) Plantlet regeneration from nodal segment and shoot tip derived explants of lentil. Lens Newsletter 16, 33–35. Tar’an, B., Buchwaldt, L., Tullu, A., Banniza, S., Warkentin, T. and Vandenberg, A. (2003) Using molecular markers to pyramid genes for resistance to ascochyta blight and anthracnose in lentil (Lens culinaris Medik). Euphytica 134, 223–230.

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Thibaud-Nissen, F., Shealy, R.T., Khanna, A. and Vodkin, L.O. (2003) Clustering of microarray data reveals transcript patterns associated with somatic embryogenesis in soybean. Plant Physiology 132, 118–136. Tullu, A., Buchwaldt, L., Warkentin, T., Taran, B. and Vandenberg, A. (2003) Genetics of resistance to anthracnose and identification of AFLP and RAPD markers linked to the resistance gene in PI 320937 germplasm of lentil (Lens culinaris Medikus). Theoretical and Applied Genetics 106, 428–434. Velculescu, V.E., Ahang, L., Vogelstein, B. and Kinzler, K.W. (1995) Serial analysis of gene expression. Science 270, 484–487. Walsh, J., Chada, K., Dalal, S., Cheng, R., Ralph, D. and McClelland, M. (1992) Arbitrarily primed PCR fingerprinting of RNA. Nucleic Acids Research 20, 4965– 4970. Warkentin, T.D. and McHughen, A. (1992) Agrobacterium tutumefaciens-mediated beta-glucuronidase (GUS) gene expression in lentil (Lens culinaris Medik.) tissues. Plant Cell Reports 11, 274–278. Weber, J.L. (1990) Informativeness of human (dC-dA)n (dG-dT)n polymorphisms. Genomics 7, 524–530. Weising, K., Winter, P., Hüttel, B. and Kahl, G. (1998) Micro-satellite markers for molecular breeding. Journal of Crop Production 1, 113–143. Williams, D.J. and McHughen, A. (1986) Plant regeneration of the legume Lens culinaris Medik (lentil) in vitro. Plant Cell Tissue and Organ Culture 7, 149. Winter, P., Pfaff, T., Udupa, S.M., Hüttel, B., Sharma, P.C., Sahi, S., Arreguin-Espinoza, R., Weigand, F., Muehlbauer, F.J. and Kahl, G. (1999) Characterization and mapping of sequence tagged microsatellite sites in the chickpea (Cicer arietinum L) genome. Molecular and General Genetics 262, 90–101. Yaish, M.W., Saenz de Miera, L.E. and Perez de la Vega, M. (2004) Isolation of a family of resistance gene analogue sequences of the nucleotide binding site (NBS) type from Lens species. Genome 47, 650–659. Zamir, D. and Ladizinsky, G. (1984) Genetics of allozyme variants and linkage groups in lentil. Euphytica 33, 329–336. Zhu, H., Choi, H.-K., Cook, D.R. and Shoemaker, R.C. (2005) Bridging model and crop legumes through comparative genomics. Plant Physiology 137, 1189–1196.

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Breeding and Management to Minimize the Effects of Drought and Improve Water Use Efficiency R. Shrestha,1 K.H.M. Siddique,2 David W. Turner2 and Neil C. Turner2 1National

Grain Legumes Research Program, Chitwan, Rampur, Nepal; 2The University of Western Australia, Crawley, Western Australia, Australia

12.1. Introduction Lentil (Lens culinaris Medikus subsp. culinaris) is an important cool-season grain legume crop, mainly grown in South Asia, West Asia and North Africa. In recent years the area under lentil production has also expanded in Canada, Australia and the USA. It is grown as a winter crop either on stored soil moisture after summer rainfall in subtropical regions or on limited rainfall in Mediterranean-type environments. Usually growth is restricted by cool temperatures during vegetative growth in winter and by high temperatures and terminal drought in spring and early summer (Yusuf et al., 1979; Shah et al., 1987; Erskine and Saxena, 1993; Shrestha, 1996). This chapter reviews the effects of water deficits on growth and yield of lentil and explores the genetic and agronomic options to minimize the effects of drought on dry matter (DM) production and seed yields.

12.2. Effects of Water Deficits Dry matter production With an adequate water supply, DM in lentil increases rapidly over time, while water deficits reduce the accumulation of above-ground DM at maturity by up to 32–61% (Ashraf et al., 1992; Turay et al., 1992; Shrestha et al., 2006b). Water deficits reduce the number of leaves and nodes, leaf area, and increase the rate of leaf senescence (Shrestha, 2005). Lentil genotypes vary significantly in the above-ground DM they produce under water deficits (Ashraf et al., 1992; Shrestha et al., 2006b). As lentil has an indeterminate growth habit, growth continues after flowering, and the imposition of water deficits in the reproductive phase reduces plant height, leaf area and foliage 172

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DM as well as reproductive structures. There are genotypic differences in the partitioning of DM to seeds, pod wall and foliage (leaf, stem and flowers) with water deficits, with the proportion of DM in the seeds affected by water shortage in some but not all genotypes (Shrestha, 2005).

Flower and pod formation In indeterminate legume species, the total number of seeds produced is a function of the number of nodes, the number of flowers per node and the proportion of flowers that develop into mature pods (Egli, 1998). In lentil, water deficits reduce the total number of flowers produced by up to 45% and reduce the flowering duration by 12 days compared with adequately watered lentils. However, a mild water deficit during early flowering that was relieved during pod development stimulated flower production by 28−39% in some genotypes (Shrestha et al., 2006b). Terminal drought significantly reduces the total numbers of filled pods and seeds produced and increases the number of single-seeded pods compared with double-seeded pods (Shrestha, 2005). A severe water deficit imposed during podding stopped the production of new flowers and pods and reduced the final pod and seed numbers by 60−70% compared with adequately watered lentils (Fig. 12.1), while seed abortion (empty pods) increased by 55−75% (Shrestha, 2005).

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Seed development The dry weight accumulation of an individual seed follows a sigmoid growth pattern, with an initial lag phase, followed by a rapid (linear) increase in DM to a maximum and the final phase where DM accumulation rate reaches zero at physiological maturity (Fig. 12.2). Final seed size (weight per seed) depends on how fast (seed growth rate, SGR) and how long (seed fill duration, SFD) seed growth continues. In lentil, the SGR ranged from 1.2 to 2.5 mg/seed/day and there was a positive correlation between SGR and seed size (Shrestha et al., 2006a). Water deficits at the end of embryo cell division (i.e. during the lag phase of early seed filling) affect the number of cotyledonary cells, while

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Fig. 12.2. Changes in seed size with time after flowering in West Asian (‘Cassab’), crossbred (ILL 7979) and South Asian (‘Simal’) lentil genotypes grown under adequately watered (a, b, c) and water-deficit (d, e, f) conditions. The lines are the predicted values using a linear mixed model with cubic spline up to 50 days after commencement of flowering. Flowering dates: {, 64–76 days after sowing (DAS); , 79–88 DAS; Δ, 121–130 DAS; ∇, 133–146 DAS; and ◊, 150–164 DAS (Source: adapted from Shrestha et al., 2006a).

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water deficits during the linear phase of seed development affect cell expansion and DM accumulation (Munier-Jolain and Ney, 1998; Saini and Westgate, 2000). Water deficits also reduce the final seed size by shortening SFD as a result of a reduction in assimilate supply rather than inhibition of SGR (Egli, 1998). A water deficit during early pod development or seed filling alters both the source and the sink strength and maintains the flux of assimilates to the developing embryo without affecting seed size or SGR (Egli, 1998). Moreover, the ability of plants to mobilize storage reserves to the seed (Turner et al., 2005) and the ability of developing seeds to maintain a favourable water status at low water potential helps to maintain SGR, seed size and prolong the SFD under water deficits (Westgate and Grant, 1989). In lentil, a water deficit during the reproductive phase reduced both the source (leaf area and/or assimilates) and the sink strength (abortion of flowers, pods and seeds resulting in reduced pod and seed numbers) thus maintaining SGR and the final size of the seeds that remained. The lack of a significant effect of water deficit on SFD in lentil may be related to its relatively small seed size (Shrestha et al., 2006a).

Seed yield and harvest index In lentil, there is a positive association between seed yield and the number of reproductive nodes, total number of flowers, number of pods, number of seeds, total DM, and harvest index (HI) (Shrestha, 2005). However, neither seed size nor seeds per pod were correlated with seed yield. A transient water deficit during flowering increased seed yield by 10−41% and HI by 18−21% in some genotypes due to increases in the numbers of pods (26−66%) and seeds (22−30%) (Shrestha et al., 2006b), whereas terminal drought reduces seed yield by reducing pod and seed numbers (Shrestha et al., 2006a).

Nitrogen fixation Symbiotic N2 fixation in lentil ranges from 69 to 154 kg N/ha (Kurdali et al., 1997; Schulz et al., 1999; Schmidtke et al., 2004) where the amounts of N2 taken up from the soil ranged from 58 to 61 kg N/ha (Schmidtke et al., 2004). Under favourable conditions about 58−80% of N2 is derived from the atmosphere (Saxena and Silim, 1990; Badarneh and Ghawi, 1994; Kurdali et al., 1997). Water deficits affect N2 fixation either through reduced carbon supply to the nodules (Subbarao et al., 1995) or reduced flow of carbon into nodules via the phloem (Serraj et al., 1999) or through a direct effect on the activity of the nodules (Durand et al., 1987; Subbarao et al., 1995). Water deficits decrease the nitrogenase activity of nodules (Durand et al., 1987; Serraj et al., 1999) through increasing the resistance of oxygen diffusion to the bacteroids (Durand et al., 1987), thereby decreasing the number of effective nodules, nodule dry weight, number of bacteroids and leghaemoglobin content (Rathore et al., 1992).

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12.3. Crop Management to Improve Water Use Efficiency Yield (Y) in water-limited environments is a function of water use or evapotranspiration (ET), the efficiency of conversion of the water to DM (water use efficiency, WUE) and the conversion of vegetative DM to a harvestable yield (HI) (Passioura, 1977): Y = ET × WUE × HI ET has two components, crop transpiration and soil evaporation. Losses by runoff and deep drainage below the root zone are considered minimal in crops such as lentil grown in low-rainfall Mediterranean environments or on residual soil water. However, soil evaporation can be high and minimizing the proportion of ET lost as soil evaporation is essential to maximize WUE and yield. Thus to maximize yields in water-limited environments, agronomic practices to maximize crop transpiration, WUE and HI, and minimize water loss by soil evaporation are required. Water use, dry matter production and seed yield In dryland environments crop water use or ET is correlated with seasonal rainfall and its distribution, with greater losses in wet seasons than in dry seasons (Zhang et al., 2000). Soil evaporation is greatest during the early stages of crop growth, when the canopy cover is small. Early planting coupled with early vigorous growth reduce soil evaporation. In a glasshouse study 85% of the variation in water use in lentil was explained by leaf area and 70% by DM accumulation at flowering (Shrestha, 2005). Seed and straw yields showed a linear increase with the amount of water applied by supplemental irrigation (Zhang et al., 2000; Shrestha, 2005). It is therefore not surprising that total seasonal rainfall accounted for about 40% of the variation in mean seed yield in Mediterranean environments, with up to 80% of the variance in mean seed yield accounted for at a single site (Erskine and El Ashkar, 1993). Similarly, at a Mediterranean site, Sarker et al. (2003) reported 77% of the variation in seed and straw yields were due to seasonal rainfall and temperature, with a positive correlation between seed and straw DM and total seasonal rainfall. However, in Western Australia, with a Mediterraneantype climate, seed yield was not correlated with total water use or with water use before flowering (Leport et al., 1998), but was positively correlated with post-flowering water use (Siddique et al., 2001). There are a range of crop management practices such as minimum tillage, appropriate fertilizer use, improved weed/disease/insect management, timely planting, narrow row width and crop rotations that contribute to high grain yield by increasing rainfall use efficiency of dryland crops (Siddique et al., 1998a; Debaeke and Aboudrare, 2004; Turner, 2004; Sarker and Erskine, 2006). These crop management strategies in a rainfed environment increase water stored in the soil at sowing, increase soil water extraction,

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reduce water losses by soil evaporation, runoff, through-flow, deep drainage, optimize the seasonal water use pattern between pre- and post-anthesis use, and improve the tolerance of a water deficit and recovery from it (Debaeke and Aboudrare, 2004; Turner, 2004). Relay cropping of lentil in rice fields (broadcasting of seed 1–2 weeks before the rice harvest) is a common practice in South Asia in ensuring the use of residual soil water (NGLIP, 1988). Early sowing, selection of varieties with rapid canopy coverage, adequate plant population, optimum fertilizer application and close spacing help to cover the soil surface, suppress weed growth and thereby increase WUE (Cooper et al., 1987). Sowing date is the major factor influencing yield and yield components in lentil (Krarup, 1984; Gray and de-Delgado, 1986; Karim et al., 1987; Mohamed, 1988; Singh et al., 1990; Aziz, 1992; Shoaib, 1992; Varshney, 1992; Shrestha, 1996; Siddique et al., 1998b). Siddique et al. (1998b) showed that in the short-season Western Australian Mediterranean-type environment delaying sowing reduced yields by up to 30 kg/ha/day at some sites, while a seed yield reduction of 15 kg/ha/day was reported in the warm-temperate environment of the Kathmandu Valley (Shrestha, 1996). Crop water use decreased with later planting and water use in the post-flowering period was particularly reduced by a delay in planting. Under rainfed environments in Nepal and Jordan early-sown lentils produced greater yield as a result of adequate vegetative biomass, long grain-filling periods and greater number of pods (Neupane and Shrestha, 1991; PAC, 1994; Shrestha, 1996; Rahman et al., 2002). In West Asia and North Africa early-sown lentil had 20–25% higher seed yield compared with the late-sown lentil (cited in van Duivenbooden et al., 2000).

Water use efficiency Rainfall received during the winter months in the Mediterranean environments of West Asia and Australia, usually occurs in frequent small showers and hence soil evaporation may constitute 30–50% of ET (160–353 mm) (Table 12.1). In South Asia, where lentils are grown on stored soil water (ET ranged from 134 to 194 mm), the surface soil is dry and hence soil evaporation is low relative to Mediterranean environments. For example, at Tel Hadya in northern Syria with its Mediterranean climate, soil evaporation (80 mm) contributed 28% of the seasonal ET in lentil (Zhang et al., 2000). The overall WUE values in this study ranged from 3.6 to 30.3 kg DM/ha/ mm and from 0.6 to 20.0 kg seed yield (grain)/ha/mm under rainfed conditions. Supplemental irrigation had the values to 2.8–29.6 kg DM/ha/mm and 1.0–11.2 kg grain/ha/mm, depending upon genotype, growing environment and water use (Table 12.1). Siddique et al. (1998a) showed that lentil could achieve a WUE of 20 kg/ha/mm in south-western Australia, but in the majority of situations the values of WUE were below 15 kg/ha/mm (Table 12.1). One of the reasons for the lower WUE was a delay in planting (Siddique et al., 1998a). Analysis of seed yields and water use using the French and Schultz (1984) method and a soil evaporation (intercept) of

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Fig. 12.3. Relationship between (a) seed yield and (b) above-ground DM and cumulative water use for selected lentil genotypes from West Asia (•), South Asia (■) and crossbreds (▲) (Shrestha et al., 2005). Data from studies in India () (Sharma and Prasad, 1984), Tel Hadya, Syria ({) (Silim et al., 1987; Zhang et al., 2000), Breda, Syria (◊) (Silim et al., 1993b) and south-west Western Australia (Δ) are also included. Lines are based on an intercept of 115 mm and water use efficiencies of (a) 15 (− −), 10 (....) and 5 (——) kg grain/ha/mm, and (b) 40 kg DM/ha/mm (Source: Siddique et al., 1998a, 2001).

115 mm (Siddique et al., 1998a, 2001) showed that in rainfed environments of Nepal the WUE of the small-seeded lentils (South Asian and crossbreds) were similar at 10–15 kg grain/ha/mm to those in Western Australia, India and Syria, while the large-seeded lentils (West Asian) had WUE for grain of less than 5 kg/ha/mm (Fig. 12.3a). The WUE for DM of the small-seeded genotypes was about 40 kg DM/ha/mm, whereas the large-seeded genotype had only half of this value (Fig. 12.3b). Siddique et al. (1998b) studied the effect of sowing rate (20–120 kg/ha) on growth and seed yield of lentil at 13 sites over three seasons in the cropping regions of south-western Australia. On average, the profitability of lentil crops in south-western Australia can be maximized with a plant density of about 150 plants/m2. It is likely that higher plant densities (up to 230 plants/m2) are optimal when growing conditions are unfavourable and the growth of individual plants is limited (e.g. in low rainfall environments, through delayed sowing or with early maturing cultivars). Lentil crops sown at high densities may also be better able to compete with weeds, be less prone to aphids and virus attack, help reduce soil evaporation and are likely to be taller and hence easier to harvest than low-density crops. However, Krarup (1984), Gray and de-Delgado (1986), Karim et al. (1987), Mohamed (1988), Neupane and Shrestha (1991), Shrestha (1996) and Rahman et al. (2002) reported no effect of seed rates on seed yield and yield components, which may be due to the small range of seed rates studied (for example, 30–60 kg of seed/ha by Shrestha, 1996).

Crop water use (mm)

WUEDM (kg/ha/mm)

Region

Irrigated

Rainfed

Soil depth (m)

West Asia

267–445 – 283 277–318 –

160–353 213–326 93 87–95 195–321

1.8 – – 1.8 1.0

– – 10.6–12.3 7.9–13.8 –

– – 352–678 – a183–388 b115–228 269–312 231–249 –

179–266 174–273 222–339c 182 134 – 159–179 169 194– d278

1.7 1.4 0.4 1.7 1.2 1.2 1.2 0.6 0.6

– – 2.8–4.1 – – – 10.1–12.3 29.6 –

Australia

South Asia

WUEGRAIN (kg/ha/mm)

Irrigated

Rainfed

Irrigated

Rainfed

9.2–18.1 14.2–22.6 5.5–8.8 5.5–9.8 6.6–14.9 5.2 13.5–30.3 8.5–13.1 c3.6–6.2 – – – 7.3 24.2–26.2 8.2–18.9

3.4–8.1 – 4.3–5.3 2.4–6.3 –

2.1–4.5 3.9–9.1 0.9–3.1 0.6–3.4 1.0–6.0 10.7 3.8–20 2.4–7.2 c1.3–2.4 4.0 7.3–12.5 – 2.3 10.4 1.8–7.0

– – 1.0–2.0 – 5.3–10.0 9.1–11.2 4.6–5.4 7.6–10.6 –

Reference Zhang et al. (2000) Silim et al. (1987) Saxena and Silim (1990) Silim et al. (1993b) Badarneh and Ghawi (1994) Sarker et al. (2003) Siddique et al. (1998a) Siddique et al. (2001) Shrestha (2005) Leport et al. (1998) Yusuf et al. (1979) Saraf and Baitha (1985) Sharma and Prasad (1984) Lal et al. (1988) Shrestha et al. (2005)

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Table 12.1. Crop water use (evapotranspiration (ET), mm), water use efﬁciency (WUE, kg/ha/mm) for total above-ground DM (WUEDM) and seed yield (WUEGRAIN) of lentil grown under supplemental irrigation and rainfed environments in West Asia, South Asia and Australia (Source: adapted from Shrestha, 2005).

a Growing

season rainfall + irrigation. water extraction + irrigation. c Intermittent water deﬁcit at ﬂowering/podding. d Long season West Asian genotype that used the late-season rainfall. b Soil

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As lentil is a poor competitor, weed species flourish and compete for water, nutrients and light (Walsh et al., 2004), leading to reduced seed yields (Kayan and Adak, 2006). Use of selective herbicides, mechanical and or hand weeding generally improve yield and WUE of lentil crops in dryland environments. Increased fertilizer use and deep ripping resulting in excessive vegetative growth may lead to an increase in ET and hence greater water deficit at flowering and in the post-flowering period when crops grow on stored soil water (Turner, 2004). In lentil, excess nitrogen (with adequate soil moisture) results in excessive vegetative growth reducing seed yield, however, high rates of nitrogen fertilizers are seldom used in lentil as it is a N2 fixing legume.

Harvest index The ratio of grain yield to total above-ground DM, the HI, is determined by the DM accumulated and the amount of water available for seed development after podding. In lentil, HI decreases with delay in sowing, and this is associated with less water availability after flowering (Siddique et al., 1998b). Thus, early planting and good early establishment by seed priming will increase the HI.

12.4. Mechanisms of Drought Resistance and their Use in Breeding Drought resistance is the ability of a genotype to produce higher yield than another when subjected to periodic water deficits (Turner, 1979). Two frameworks for the adaptation of plants to drought have been proposed (Turner, 2003), namely a drought-resistance and a yield-component framework. The drought-resistance framework deals with the specific morphological, physiological and biochemical characteristics that enable plants to adapt to low water availability, while the yield-component framework focuses on yield under water-limited conditions and the components of yield, namely water use, WUE and HI (Turner, 2003). For survival and improved yields under rainfed conditions, plants usually possess more than one adaptive mechanism (Khanna-Chopra, 1982). While the yield-component framework has been helpful in analysing the management practices to improve yields in water-limited environments, we adopt the drought-resistance framework for considering the traits that assist in improving yields of lentil in water-limited environments. Drought-resistance mechanisms have been divided into three categories (e.g. by Turner, 2003): 1. 2. 3.

Drought escape. Dehydration avoidance. Dehydration tolerance.

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Drought escape The mechanism identified as important in drought escape is the ability of a plant to complete its life cycle before the commencement of severe water deficits (Boyer, 1996). This involves rapid phenological development such as rapid germination and seedling establishment, early flowering, early podding, early maturity, and phenological plasticity to take advantage of longer and cooler seasons (Turner et al., 2001). In lentil, flower initiation is affected by temperature, photoperiod and vernalization (Summerfield et al., 1984; Erskine et al., 1989a, b; McKenzie and Hill, 1989). Lentil is predominantly a long-day (15−16 h photoperiod) plant (Saxena and Wassimi, 1984), but genotypes vary considerably from neutral to acute sensitivity in their responsiveness to photoperiod and temperature (Summerfield et al., 1985b), and many genotypes show a quantitative vernalization requirement (Summerfield et al., 1985a). Genotypes originating from lower latitudes (Ethiopia, Sudan, Egypt and India) have a shorter critical photoperiod than genotypes from higher latitudes (USSR, Turkey), and the magnitude of photoperiodic response depends on temperature differences (Saxena and Wassimi, 1984; Erskine, 1997). In the Mediterranean environments of North Africa and West Asia where lentil is sown in March/April (spring), vegetative growth coincides with progressively lengthening days and warmer temperature, and flowering occurs at a photoperiod of 11.6−12.0 h. In South Asia, northern Argentina and Australia lentil is sown in autumn and vegetative growth coincides with shortening days and cooler temperatures (Sinha, 1977; Erskine and Hawtin, 1983; Erskine et al., 1994a; Shrestha et al., 2005) and flowering occurs at a photoperiod of about 10.6−11.0 h (Erskine, 1983; Waldia et al., 1988; Shrestha et al., 2005). Mediterranean/West Asian genotypes flower late when grown under South Asian conditions and as a result, the duration of flowering and pod filling is truncated by rising temperatures and decreasing rainfall in spring and early summer, resulting in poor DM accumulation, very few pods and poor seed yield (Erskine and Hawtin, 1983; Shrestha et al., 2005). In contrast, genotypes originating from South Asia and Ethiopia, when sown in South Asia, flower and pod early and thereby escape drought in rainfed environments (Hamdi et al., 1992). Differences in phenological development contribute 45−60% of the variation in seed yield in South Asia (Silim et al., 1993a; Erskine et al., 1994b; Siddique et al., 2003). Therefore, the appropriate drought strategy for lentil in environments where water deficits and high temperatures at the reproductive stage induce senescence and early maturity is drought escape (Erskine et al., 1994b; Thomson et al., 1997; Zhang et al., 2000; Siddique et al., 2003; Shrestha et al., 2006a). Initiation of flowering can be unaffected, advanced or delayed in lentil depending on the severity of water deficits and the crop growth habit (van Kessel, 1994). In the case of mild water deficits, advancement in the time of flowering may be related to higher plant temperature as a consequence of reduced transpiration. While early flowering and rapid phenological development give higher seed yields and higher yield stability than late

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flowering under terminal drought, seed yields may be reduced when there is an unpredictable intermittent drought (Siddique et al., 2003). Thus droughtinduced early maturity is advantageous in dry seasons, but high yield is often associated with longer growth duration, late flowering and greater water use (Blum, 1997). The ability of plants to adjust the duration of different growth phases in response to the availability of soil water during the growing season, that is developmental plasticity (Turner, 1979; Subbarao et al., 1995), enables a plant to produce higher yields when the growing period is longer and is an important mechanism in unpredictable climates and under favourable soil water regimes. While lentil is an indeterminate plant, this quality varies with genotypes. In lentil a period of water deficit enhances pod fill and hence the length of pod filling varies depending on the degree and duration of water shortage, particularly in late-maturing genotypes (van Kessel, 1994). The indeterminate nature of some lentil genotypes is a beneficial trait that contributes to developmental plasticity.

Dehydration avoidance Both morphological and physiological mechanisms contribute to dehydration avoidance. Morphological mechanisms Morphological modifications such as reduction in leaf size, shape and numbers, leaf orientation (change in leaf angle) and leaf rolling are mechanisms that postpone dehydration because radiation absorption and water loss are reduced (Kramer, 1980; Turner et al., 2001). With increasing water deficits, the rate of leaf production decreases (Mwanamwenge et al., 1997; Shrestha, 2005) and leaves became smaller (Mwanamwenge et al., 1997). In lentil, yellow cotyledons appear to be associated with high DM production (Tullu et al., 2001) and light-coloured foliage at the vegetative stage is associated with vigorous early growth and establishment (Silim et al., 1993a). Increased stomatal and cuticular resistance, by increased pubescence, and waxiness help to reduce water loss. Lentil genotypes with greater wax deposition on the leaf surfaces showed considerable tolerance to water deficits (Ashraf et al., 1992). Under rainfed environments, anthocyanin pigment production in genotypes from South Asia and crossbreds between South Asian and West Asian genotypes is a mechanism that enhances cold tolerance (Summerfield et al., 1985a). Leaf hairs reduce gas exchange, increase leaf reflectance and reduce leaf heating (Monneveux and Belhassen, 1997). Leaf drop and rapid senescence of the physiologically older leaves are also adaptive mechanisms for reducing water loss (Monneveux and Belhassen, 1997). Deep rooting and high root density are common morphological mechanisms to improve water uptake by extracting water from greater depth (Turner, 1986). Legumes have lower root length densities (RLD) than cereals when grown in similar soils (Gregory, 1986). Lentil has greater RLD in

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the upper 0−30 cm soil layer than in the deeper soil layers (60−160 cm) (Sharma and Prasad, 1984; Silim et al., 1993b; Adak and Biesantz, 1997; Shrestha et al., 2005), and the rooting depth of lentil under rainfed conditions is about 0.8 m (Gregory, 1986; Siddique et al., 2001). A large vigorous root system is a major feature of drought resistance under water deficits when water is available deep in the soil profile and is replenished each year (Ludlow and Muchow, 1988). Dehydration-avoiding species usually have deep rooting ability (Boyer, 1996), but increased rooting depth and RLD do not always reflect the ability of a genotype to extract more soil water if the wet profile is shallow (Ludlow and Muchow, 1988). The ratio of root-toshoot DM in lentil increased by 14–100% compared with well-watered lentil when water deficits were imposed at the reproductive stage (Shrestha, 2005). The increase in the root-to-shoot ratio was the result of the relatively greater reduction in shoot growth than in root growth rather than an increase in absolute root weight (Shrestha, 2005). Sarker et al. (2005) reported significant variation in taproot length, lateral root number, total root length and total root weight among lentil genotypes of diverse origins. Genotypes with a long taproot and more lateral roots have increased drought tolerance and are being used for breeding high-yielding cultivars under water-limited conditions (Sarker and Erskine, 2005; Sarker et al., 2005). Lentil genotypes from South Asia have the highest RLD (at pod filling) followed by the crossbreds (South Asia × West Asia), and the lowest in the West Asian genotypes when grown in the rainfed environment of Nepal (Shrestha et al., 2005). Physiological mechanisms Low stomatal conductance is an efficient adaptive response to short periods of water deficit (Franca et al., 2000). Stomatal closure allows plants to maintain tissue turgour and volume for normal metabolic function by maintaining water uptake and reducing water loss (Kramer, 1980; Turner et al., 2001). There is considerable variation in the sensitivity of stomata to increasing water deficits among grain legumes (Leport et al., 1998; Shrestha, 2005). In lentil, stomatal conductance under well-watered conditions varied from 169 to 400 mmol/m2/s but decreased markedly to 19−100 mmol/m2/s as the leaf water potential decreased below –2.5 MPa (Leport et al., 1998; Shrestha, 2005). No differences among genotypes in the stomatal response to water deficits were observed (Shrestha et al., 2006b) and stomatal conductance has not been used as a selection criterion in lentil. Differences in stomatal conductance will influence the rate of photosynthesis (PN), but water deficits can affect the rate of photosynthesis by affecting the photosynthetic capacity of the leaf as well as stomatal conductance and can influence the remobilization of carbon to the grain in assimilate redistribution. With an adequate water supply, leaf PN in lentil ranged from 16.6 to 17.0 μmol/m2/s during flowering in both the field and the glasshouse (Leport et al., 1998; Shrestha, 2005) and 8 μmol/m2/s during podding (Shrestha, 2005). Leaf PN was reduced by 22–53% when water was withheld at flowering and podding, and reached very low values when the leaf water

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potential fell to –2.5 MPa (Shrestha, 2005) to –3.0 MPa (Leport et al., 1998). However, no differences among genotypes were observed in the sensitivity of photosynthesis to water deficits (Shrestha, 2005) and breeders have not focused on selecting lines with differences in photosynthesis in lentil. When water deficits are severe, particularly under terminal drought where the current PN is impaired during seed filling, remobilization of stem reserves to the grain can be important (Turner et al., 2005). Therefore, yield stability under terminal water deficits depends on the ability of crops to mobilize assimilates, accumulated before and immediately post-flowering, to the seed (Turner et al., 2001). Genotypes vary in the proportion of pre-flowering assimilate transferred to grain. In late-maturing lentils, stem reserves act as a source of carbon for seed filling, while PN is the major source of assimilates in early maturing genotypes (Clements et al., 1997). In general, grain legumes show poor remobilization of assimilates produced before flowering to the seed compared with cereals. This is because of the greater demand for assimilates for N2 fixation and through competition for assimilates between vegetative and reproductive organs as a result of their indeterminate growth habit. Nodules respire about 40% of the carbon assimilated photosynthetically at the vegetative stage (Salon et al., 2001), but in lentil, higher concentrations of nitrogen in the leaves at flowering (36−41 mg/g) compared with maturity (18−22 mg/g) suggests that there may be remobilization of nitrogen from the leaf to the seed during pod filling (Whitehead et al., 2000). In lentil, low soil water almost halved N2 fixation compared with an adequate water supply (Saxena and Silim, 1990) and genetic variation in N2 fixation among legume cultivars with response to water deficits has been reported (Serraj et al., 1999). Also, the genotypic differences in the growth and survival of rhizobial strains (Rhizobium leguminosarum) to increasing soil water deficits (–1.5 MPa) have been reported by Athar (1998), but both the genetic variation in N2 fixation and the tolerance of water deficits by rhizobia have to be exploited by breeders and agronomists. Osmotic adjustment (OA) is an important physiological mechanism by which plants synthesize and accumulate solutes in cells in response to water deficits in the soil and/or plant (Turner and Jones, 1980). This net accumulation of solutes lowers the osmotic potential or increases the osmotic pressure of the cells and draws water into the cells and tissues and hence contributes to the maintenance of turgour, stomatal conductance, photosynthesis and plant growth at progressively lower leaf water potentials (Turner and Jones, 1980; Subbarao et al., 1995). In a rainfed environment in Western Australia, lentil showed a high degree of OA (0.6 MPa) with decreasing leaf water potential (Leport et al., 1998; Turner et al., 2001) and has been shown to range from 0.0 to 1.8 MPa in a range of genotypes and soil water potentials (Ashraf et al., 1992; Clements et al., 1997; Shrestha, 2005). In a glasshouse study lentil genotypes showed variation in OA during flowering, but this variation was a result of the varying degrees of soil water deficit among the genotypes (Fig. 12.4). The values of osmotic potential were lower at podding than flowering, but no solute accumulation occurred during the drying cycle at podding (Shrestha, 2005). The solutes that accumulate through

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Osmotic adjusment (MPa)

2.5 2.0 1.5 1.0 0.5 0.0 –30

–25 –20 –15 –10 –5 Cumulative leaf water potential (MPa)

0

Fig. 12.4. Relationship between osmotic adjustment (calculated as the difference in osmotic potential at 100% relative water content between adequately watered and droughted plants) and cumulative predawn leaf water potential (r2 = –0.62; highly significant at P = 0.01 level) of six lentil genotypes: ‘Cassab’ ({), ILL 6829 (Δ), ILL 7979 (▲), ILL 7982 (∇), ‘Khajura 2’ (■) and ‘Simal’ () when water was withheld at flowering (Source: Shrestha, 2005).

OA are reportedly transported from the senescing leaves to the developing seeds when the rate of leaf photosynthesis reaches zero (Leport et al., 2003). Positive correlations between OA and seed yield have been reported for some species, but no correlation between OA and seed yield or DM have been observed in lentil (Francis and Siddique, 2001) and no selection for OA has been conducted in breeding lentil for water-limited environments. In those rainfed environments in which the crop grows on residual soil water, one of the mechanisms that increases the efficiency of water use is increased transpiration efficiency (TE). TE is the transpiration per unit DM or grain yield (Fischer, 1981) or, at the level of leaf, the moles of carbon (C) or CO2 fixed per mole of water lost by transpiration (Arnon, 1992). Measurement of the instantaneous TE of the leaf is possible with portable gas exchange equipment, but an integrated measure of TE is difficult and labour intensive, requiring the measurement of plant transpiration and soil evaporation and the changes in DM over the same period. Carbon isotope discrimination (CID) can be used as an indirect and rapid tool to measure TE and has been used in wheat to develop high TE cultivars of wheat for waterlimited environments (Richards, 2006). In lentil, CID values showed significant variation among genotypes, plant parts and age (17.8% in seed to 22.9% in the leaf at flowering) under adequate water supply, and its values differed significantly with response to watering regimes (Matus et al., 1995a, b). Lentils also had lower discrimination values under water deficit than in wellwatered conditions. Johnson et al. (1995) reported a negative correlation between CID and TE in lentil. However, Matus et al. (1996) and Turner et al.

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(2007) found no correlation between CID and TE in different genotypes of lentil grown under adequately watered conditions and concluded that CID is not a useful selection tool for TE in lentil. Selection for high TE by any technique has not been undertaken in lentil breeding programmes.

Dehydration tolerance Dehydration tolerance is the ability of plant membranes to withstand mechanical injury/degradation, or the ability of membranes and cytoplasm to withstand protein denaturation and where cells continue metabolism at low leaf water status (Turner et al., 2001). Most crop plants die as dehydration reaches a critical level (Turner et al., 2001). Crop species and genotypes vary in the lethal water potential (lowest water potential experienced by the last viable leaf) (Flower and Ludlow, 1987). In lentil the mechanism of dehydration tolerance or the level of critical water potential needs further investigation.

12.5. Conclusion Lentil is an important source of protein and other nutrients essential for human health, its straw is a valuable feed for livestock. The crop is primarily grown in rainfed conditions, where it is frequently subjected to moisture deficit conditions. In South Asia, lentil is grown during the winter months on residual soil water after the harvest of rice, while in West Asia and in other Mediterranean-type environments such as Australia it is usually sown during the wet winter months, but in both cases a reducing soil water supply coupled with increasing temperatures during reproductive development in spring results in terminal drought and a limitation to yield. Rapid phenological development allows the crop to complete its life cycle before the onset of severe terminal drought, and therefore is an important trait for crop adaptation in water-limited environments. Lentils exhibit drought escape whereby terminal drought induces early maturity and senescence. Lentil has an indeterminate growth habit and water deficits during the vegetative stage reduce canopy development, net photosynthesis and hence assimilate supply. Water deficits during the reproductive period reduce the reproductive sinks to compensate for the reduced assimilate supply. Mild water deficits, however, promote flower production and therefore increase seed yield in some lentil genotypes. Although physiological parameters such as leaf photosynthesis, stomatal conductance and OA are affected by water deficits, no direct correlation between these traits and seed yield has been observed. Also, as there was no genotypic variation in rates of leaf photosynthesis and stomatal conductance, and as variation in OA among genotypes was related to varying degrees of drying, breeding for increased yields using these physiological traits has not been pursued to date.

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The major impact of water deficits in lentil is on reproductive processes. Water deficits restrict crop growth, reduce flower production by almost half and reduce the number of fruiting nodes with a significant increase in the proportion of fruiting nodes bearing a single pod. Pod and seed numbers are further reduced as a result of increased abortion of flowers and pods. The reduction in seed number as a result of reduced flower production and increased flower/pod abscission under water deficits are similar to those observed in other legume species. However, water deficits do affect the number of seeds per pod, suggesting that the reduction in seed number balanced the reduced supply of assimilates and helped to maintain seed size. Seed size and SGR in lentil are conserved under terminal drought, as in other grain legumes. Reduced pod and seed numbers are a compensatory mechanism in response to reduced assimilate supply induced by water deficits, and so the SGR and seed size are maintained. As seed size in lentil is the primary determinant of quality and price in the marketplace especially for green lentil, the ability to maintain seed size under water deficits is of particular benefit as the majority of lentils are grown in rainfed environments. Agronomic options to improve yields in water-limited environments centre around early planting in Mediterranean-type environments and rapid establishment in the post-rainy season where lentils are grown on residual soil water. Seed priming has been shown to benefit yields by increasing plant establishment when lentils are sown just prior to, or immediately after, harvest of a previous rice crop. Minimum tillage with stubble retention will also lead to improved crop establishment, reduced soil evaporation loss and greater WUE. Lentil genotypes (pilosae, microsperma type) from South Asia flower and mature early so that the crop matures before there is an abrupt temperature increase and soil water recedes. The large-seeded genotypes from Chile, Greece, Iran, Iraq, Jordan, Syria, Tunisia and Turkey show a greater degree of cold tolerance than small-seeded lentils. In South Asia to date, breeding has concentrated on selection of large-seeded types and yield improvement through early flowering, an increase in DM and disease resistance. Specific crosses have been made to incorporate the drought-resistance traits from the South Asian genotypes, specifically early flowering, with the high yield and high DM of the West Asian genotypes. This hybridization and population improvement helps to broaden the genetic base of commercial genotypes.

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Fischer, R.A. (1981) Optimizing the use of water and nitrogen through breeding of crops. Plant and Soil 58, 249–278. Flower, D.J. and Ludlow, M.M. (1987) Variation among accessions of pigeonpea (Cajanus cajan) in osmotic adjustment and dehydration tolerance of leaves. Field Crops Research 17, 229–243. Franca, M.G.C., Thi, A.T.P., Pimentel, C., Rossiello, R.O.P., Zuily-Fodil, Y. and Laffray, D. (2000) Differences in growth and water relations among Phaseolus vulgaris cultivars in response to induced drought stress. Environmental and Experimental Botany 43, 227–237. Francis, C.M. and Siddique, K.H.M. (2001) Final Report: Improvement in Drought and Disease Resistance in Lentil in Nepal, Pakistan and Australia. Centre for Legumes in Mediterranean Agriculture, The University of Western Australia, Crawley, Western Australia, pp. 1–87. French, R.J. and Schultz, J.E. (1984) Water use efficiency of wheat in a Mediterraneantype environment. 1. The relation between yield, water use and climate. Australian Journal of Agricultural Research 35, 743–764. Gray, L.N. and de-Delgado, G.C. (1986) Sowing dates for lentil in Salta, Argentina (Lens culinaris). LENS Newsletter 13, 19–27. Gregory, P.J. (1986) Root growth of chickpea, faba bean, lentil, and pea and effects of water and salt stresses. In: Summerfield, R.J. (ed.) World Crops: Cool Season Food Legumes, a Global Perspective of the Problems and Prospects for Crop Improvement in Pea, Lentil, Faba Bean and Chickpea. Kluwer Academic Publishers, Dordrecht, The Netherlands, pp. 813–828. Hamdi, A., Erskine, W. and Gates, P. (1992) Adaptation of lentil seed yield to varying moisture supply. Crop Science 32, 987–990. Johnson, R.C., Muehlbauer, F.J. and Simon, C.J. (1995) Genetic variation in water-use efficiency and its relation to photosynthesis and productivity in lentil germplasm. Crop Science 35, 457–463. Karim, M.F., Rahman, M.M. and Maniruzzaman, A.F.M. (1987) Effect of date of sowing and seed rate on lentil [in Bangladesh]. AGRIS Database (1989–1990). Available at: http://www.fao.org/agris/search/display.do?f=./1989/v1509/BD8825320.xml; BD8825320 (accessed 4 December 2008). Kayan, N. and Adak, M.S. (2006) Effect of soil tillage and weed control methods on weed biomass and yield of lentil (Lens culinaris Medic.). Archives of Agronomy and Soil Science 52, 697–704. Khanna-Chopra, R. (1982) Physiological and Biochemical Basis of Adaptation to Water Stress in Crop Plants. Water Technology Centre, Indian Agricultural Research Institute, New Delhi, India, pp. 1–73. Kramer, P.J. (1980) Drought, stress, and the origin of adaptations. In: Turner, N.C. and Kramer, P.J. (eds) Adaptation of Plants to Water and High Temperature Stress. Wiley-Inter Science, New York, pp. 7–19. Krarup, A.H. (1984) The effect of sowing dates and rates on lentil yield components. LENS Newsletter 11, 18–20. Kurdali, F., Kalifa, K. and Al Shamma, M. (1997) Cultivar differences in nitrogen assimilation, partitioning and mobilization in rain-fed grown lentil. Field Crops Research 54, 235–243. Lal, B., Gupta, M.P.C. and Pandey, R.K. (1988) Response of lentil to different irrigation schedules. LENS Newsletter 15, 20–23. Leport, L., Turner, N.C., French, R.J., Tennant, D., Thomson, B.D. and Siddique, K.H.M. (1998) Water relations, gas exchange and growth of cool-season grain legumes in a Mediterranean-type environment. European Journal of Agronomy 9, 295–303.

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R. Shrestha et al. Leport, L., Turner, N.C., French, R.J., Thomson, B.D. and Siddique, K.H.M. (2003) Physiological responses of cool-season grain legumes to drought in the low rainfall Mediterranean environment of south-western Australia. In: Saxena, N.P. (ed.) Management of Agricultural Drought: Agronomic and Genetic Options. Science Publishers Inc., Enfield, New Hampshire, USA, pp. 163–172. Ludlow, M.M. and Muchow, R.C. (1988) Critical evaluation of the possibilities for modifying crops for high production per unit of precipitation. In: Bidinger, F.R. and Johansen, C. (eds) Drought Research Priorities for the Dryland Tropics. International Crops Research Institute for the Semi-Arid Tropics, Patancheru, Andhra Pradesh, India, pp. 179–211. Matus, A., Slinkard, A.E. and van Kessel, C. (1995a) C-13 isotope discrimination at several growth-stages in lentil, spring wheat and canola. Canadian Journal of Plant Science 75, 577–581. Matus, A., Slinkard, A.E. and van Kessel, C. (1995b) Carbon-isotope discrimination and indirect selection for seed yield in lentil. Crop Science 35, 679–684. Matus, A., Slinkard, A.E. and van Kessel, C. (1996) Carbon isotope discrimination and indirect selection for transpiration efficiency at flowering in lentil (Lens culinaris Medikus), spring bread wheat (Triticum aestivum L), durum wheat (T. turgidum L), and canola (Brassica napus L). Euphytica 87, 141–151. McKenzie, B.A. and Hill, G.D. (1989) Environmental control of lentil (Lens culinaris) crop development. Journal of Agricultural Science 113, 67–72. Mohamed, A.K. (1988) Effect of sowing method, rate and date on lentil in Shendi area of the Sudan. LENS Newsletter 15, 23–25. Monneveux, P. and Belhassen, E. (1997) The diversity of drought adaptation in the wide. In: Belhassen, E. (ed.) Drought Tolerance in Higher Plants: Genetical, Physiological and Molecular Biological Analysis. Kluwer Academic Publishers, Dordrecht, The Netherlands, pp. 7–14. Munier-Jolain, N.G. and Ney, B. (1998) Seed growth rate in grain legumes 2. Seed growth rate depends on cotyledon cell number. Journal of Experimental Botany 49, 1971–1976. Mwanamwenge, J., Siddique, K.H.M. and Sedgley, R.H. (1997) Canopy development and light absorption of grain legume species in a short season Mediterranean-type environment. Journal of Agronomy and Crop Science 179, 1–7. National Grain Legume Improvement Program (NGLIP) (1988) Annual Report 1987/88. NGLIP, National Agricultural Research and Services Center, Lalitpur, Nepal, pp. 85–87. Neupane, R.K. and Shrestha, R. (1991) Report on varietal and agronomical studies on lentil. Paper presented at the Winter Crop Workshop in Nepal Agricultural Research Council (NARC), Kathmandu, Nepal, 16–20 September. Pakhribas Agricultural Center (PAC) (1994) Lentil Planting Date. Annual Report 1992– 93. PAC, Dhankuta, Nepal, p. 20. Passioura, J.B. (1977) Grain yield, harvest index, and water use of wheat. The Journal of the Australian Institute of Agricultural Science 43, 117–120. Rahman, A., Tawaha, M. and Turk, M.A. (2002) Effect of dates and rates of sowing on yield and yield components of lentil (Lens culinaris Medik.) under semi-arid conditions. Pakistan Journal of Biological Sciences 5, 531–532. Rathore, R.S., Singh, P.P., Khandwe, R. and Khandwe, N. (1992) Effect of irrigation schedules, phosphorus levels and phosphate-solubilizing organisms 3. Nodulation. LENS Newsletter 19, 32–35. Richards, R.A. (2006) Physiological traits used in breeding of new cultivars for waterscarce environments. Agricultural Water Management 80, 197–211.

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Saini, H.S. and Westgate, M.E. (2000) Reproductive development in grain crops during drought. Advances in Agronomy 68, 59–96. Salon, C., Munier-Jolain, N.G., Duc, G., Voisin, A.S., Grandgirard, D., Larmure, A., Emery, R.J.N. and Ney, B. (2001) Grain legume seed filling in relation to nitrogen acquisition: a review and prospects with particular reference to pea. Agronomie 21, 539–552. Saraf, C.S. and Baitha, S.P. (1985) Water use patterns and water requirement of lentil planted on different dates. LENS Newsletter 12, 12–15. Sarker, A. and Erskine, W. (2005) Genetic improvement for drought tolerance in lentil. In: INTERDROUGHT-II, The Second International Conference on Integrated Approaches to Sustain and Improve Plant Production Under Drought Stress, Rome, Italy, 24–28 September, p. 58. Available at: http://www.plantstress.com/id2/ (accessed 18 December 2007). Sarker, A. and Erskine, W. (2006) Recent progress in the ancient lentil. The Journal of Agricultural Science 144, 19–29. Sarker, A., Erskine, W. and Singh, M. (2003) Regression models for lentil seed and straw yields in Near East. Agricultural and Forest Meteorology 116, 61–72. Sarker, A., Erskine, W. and Singh, M. (2005) Variation in shoot and root characteristics and their association with drought tolerance in lentil landraces. Genetic Resources and Crop Evolution 52, 89–97. Saxena, M.C. and Silim, S.N. (1990) Food Legume Improvement Program: Annual Report 1990. International Center for Agricultural Research in the Dry Areas (ICARDA), Aleppo, Syria. Saxena, M.C. and Wassimi, N. (1984) Photoperiodic response of some diverse genotypes of lentil (Lens culinaris Medi.). LENS Newsletter 11, 25–29. Schmidtke, K., Neumann, A., Hof, C. and Rauber, R. (2004) Soil and atmospheric nitrogen uptake by lentil (Lens culinaris Medik.) and barley (Hordeum vulgare ssp. nudum L.) as monocrops and intercrops. Field Crops Research 87, 245– 256. Schulz, S., Keatinge, J.D.H. and Wells, G.J. (1999) Productivity and residual effects of legumes in rice-based cropping systems in a warm-temperate environment. I. Legume biomass production and N fixation. Field Crops Research 61, 23–35. Serraj, R., Sinclair, T.R. and Purcell, L.C. (1999) Symbiotic N2 fixation response to drought. Journal of Experimental Botany 50, 143–155. Shah, S.M., Mishra, N.K. and Shrestha, K.P. (1987) Winter cereals and food legumes in mountainous areas. In: Srivastava, J.P., Saxena, M.C., Varma, S. and Tahir, M. (eds) International Symposium on Problems and Prospects of Winter Cereals and Food Legume Production in the High-elevation Areas of West Asia, Southeast Asia and North Africa. International Center for Agricultural Research in the Dry Areas (ICARDA), Aleppo, Syria, pp. 197–210. Sharma, S.N. and Prasad, R.P. (1984) Effect of soil moisture regimes on the yield and water use of lentil (Lens culinaris Medic). Irrigation Science 5, 285–293. Shoaib, Y.O. (1992) Effect of sowing date and seeding rate on lentil in Eastern Libya. LENS Newsletter 19, 21–23. Shrestha, R. (1996) Effect of planting dates and seed rates on lentil (var. Simal) at Khumaltar (1993/94–1995/96). In: National Winter Crop Workshop. Regional Agricultural Research Station, Bhairahawa. Nepal Agricultural Research Council, Bhairahawa, Lumbini, Nepal. Shrestha, R. (2005) Adaptation of Lentil (Lens culinaris Medikus subsp. culinaris) to rainfed environments – response to water deficits. PhD thesis, The University of Western Australia, Crawley, WA, Australia.

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R. Shrestha et al. Shrestha, R., Siddique, K.H.M., Turner, N.C., Turner, D.W. and Berger, J. (2005) Growth and seed yield of lentil (Lens culinaris Medikus) genotypes of West Asian and South Asian origin and crossbreds between the two under rainfed conditions in Nepal. Australian Journal of Agricultural Research 56, 971–981. Shrestha, R., Turner, N.C., Siddique, K.H.M., Turner, D.W. and Speijers, J. (2006a) A water deficit during pod development in lentils reduces flower and pod number but not seed size. Australian Journal of Agricultural Research 57, 427–438. Shrestha, R., Turner, N.C., Siddique, K.H.M. and Turner, D.W. (2006b) Physiological and seed yield responses to water deficits among lentil genotypes from diverse origins. Australian Journal of Agricultural Research 57, 903–915. Siddique, K.H.M., Loss, S.P., Pritchard, D.L., Regan, K.L., Tennant, D., Jettner, R.L. and Wilkinson, D. (1998a) Adaptation of lentil (Lens culinaris Medik.) to Mediterranean-type environments: effect of time of sowing on growth, yield, and water use. Australian Journal of Agricultural Research 49, 613–626. Siddique, K.H.M., Loss, S.P., Regan, K.L. and Pritchard, D.L. (1998b) Adaptation of lentil (Lens culnaris Medik) to Mediterranean-type environments: response to sowing rates. Australian Journal of Agricultural Research 49, 1057–1066. Siddique, K.H.M., Regan, K.L., Tennant, D. and Thomson, B.D. (2001) Water use and water use efficiency of cool season grain legumes in low rainfall Mediterraneantype environments. European Journal of Agronomy 15, 267–280. Siddique, K.H.M., Loss, S.P. and Thomson, B.D. (2003) Cool season grain legumes in dryland Mediterranean environments of Western Australia: significance of early flowering. In: Saxena, N.P. (ed.) Management of Agricultural Drought: Agronomic and Genetic Options. Science Publishers Inc., Enfield, New Hampshire, USA, pp. 151–161. Silim, S.N., Saxena, M.C. and Erskine, W. (1987) Food Legume Improvement Program: Annual Report for 1987. International Center for Agricultural Research in the Dry Areas (ICARDA), Aleppo, Syria, pp. 94–98. Silim, S.N., Saxena, M.C. and Erskine, W. (1993a) Adaptation of lentil to the Mediterranean environment. 1. Factors affecting yield under drought conditions. Experimental Agriculture 29, 9–19. Silim, S.N., Saxena, M.C. and Erskine, W. (1993b) Adaptation of lentil to the Mediterranean environment. 2. Response to moisture supply. Experimental Agriculture 29, 21–28. Singh, K., Singh, S., Jain, A. and Singh, P. (1990) Effect of sowing date and row spacing on the yield of lentil varieties. LENS Newsletter 17, 9–10. Sinha, S.K. (1977) Food Legumes: Distribution, Adaptability and Biology of Yield. Food and Agriculture Organization (FAO), Rome. Subbarao, G.V., Johansen, C., Slinkard, A.E., Rao, R.C.N., Saxena, N.P. and Chauhan, Y.S. (1995) Strategies for improving drought resistance in grain legumes. Critical Reviews in Plant Sciences 14, 469–523. Summerfield, R.J., Muehlbauer, F.J. and Roberts, E.H. (1984) Controlled environments as an adjunct to field research on lentils (Lens culinaris). 3. Photoperiodic lighting and consequences for flowering. Experimental Agriculture 20, 1–18. Summerfield, R.J., Muehlbauer, F.J. and Roberts, E.H. (1985a) Lens culinaris. In: Halevy, A.H. (ed.) Handbook of Flowering. CRC Press, Boca Raton, Florida, pp. 118–124. Summerfield, R.J., Roberts, E.H., Erskine, W. and Ellis, R.H. (1985b) Effects of temperature and photoperiod on flowering in lentils (Lens culinaris Medic.). Annals of Botany 56, 659–671. Thomson, B.D., Siddique, K.H.M., Barr, M.D. and Wilson, J.M. (1997) Grain legume species in low rainfall Mediterranean-type environments. 1. Phenology and seed yield. Field Crops Research 54, 173–187.

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Tullu, A., Kusmenoglu, I., McPhee, K.E. and Muehlbauer, F.J. (2001) Characterization of core collection of lentil germplasm for phenology, morphology, seed and straw yields. Genetic Resources and Crop Evolution 48, 143–151. Turay, K.K., McKenzie, B.A. and Andrews, M. (1992) Effect of water stress and nitrogen on canopy development and radiation interception of lentil. Proceedings Agronomy Society of New Zealand 22, 115–119. Turner, N.C. (1979) Drought resistance and adaptation to water deficits in crop plants. In: Mussell, H. and Staples, R.C. (eds) Stress Physiology in Crop Plants. John Wiley and Son, New York, pp. 343–367. Turner, N.C. (1986) Adaptation to water deficits – a changing perspective. Australian Journal of Plant Physiology 13, 175–190. Turner, N.C. (2003) Drought resistance: a comparison of two research frameworks. In: Saxena, N.P. (ed.) Management of Agricultural Drought: Agronomic and Genetic Options. Science Publishers Inc., Enfield, New Hampshire, USA, pp. 89–102. Turner, N.C. (2004) Agronomic options for improving rainfall-use efficiency of crops in dryland farming systems. Journal of Experimental Botany 55, 2413–2425. Turner, N.C. and Jones, M.M. (1980) Turgor maintenance by osmotic adjustment: a review and evaluation. In: Turner, N.C. and Kramer, P.J. (eds) Adaptation of Plants to Water and High Temperature Stress. John Wiley and Sons, New York, pp. 87–103. Turner, N.C., Wright, G.C. and Siddique, K.H.M. (2001) Adaptation of grain legumes (pulses) to water-limited environments. Advances in Agronomy 71, 193–231. Turner, N.C., Davies, S.L., Plummer, J.A. and Siddique, K.H.M. (2005) Seed filling in grain legumes (pulses) under water deficits with emphasis on chickpea (Cicer arietinum L.). Advances in Agronomy 87, 211–250. Turner, N.C., Palta, J.A., Shrestha, R., Ludwig, C., Siddique, K.H.M. and Turner, D.W. (2007) Carbon isotope discrimination is not correlated with transpiration efficiency in three cool-season grain legumes (pulses). Journal of Integrative Plant Biology 49, 1478–1483. van Duivenbooden, N.M., Pala, C.S. and Bielders, C.L. (2000) Cropping systems and crop complementarity in dryland agriculture: a review. Netherlands Journal of Agricultural Science 48, 213–236. van Kessel, C. (1994) Seasonal accumulation and partitioning of nitrogen by lentil. Plant and Soil 164, 69–76. Varshney, J.G. (1992) Effect of sowing dates and row spacing on the yield of lentil varieties. LENS Newsletter 19, 20–21. Waldia, R.S., Singh, V.P. and Kharb, R.P.S. (1988) Stability of seed yield of some lentil genotypes in relation to seed size. LENS Newsletter 15, 17–19. Walsh, M., Siddique, K.H.M., Hashem, A. and Seymour, M. (2004) Weed management in grain legume crops in Western Australia. Journal of Lentil Research 1, 37–42. Westgate, M.E. and Grant, D.T. (1989) Effect of water deficits on seed development in soyabean. 1. Tissue water status. Plant Physiology 91, 975–979. Whitehead, S.J., Summerfield, R.J., Muehlbauer, F.J., Coyne, C.J., Ellis, R.H. and Wheeler, T.R. (2000) Crop improvement and the accumulation and partitioning of biomass and nitrogen in lentil. Crop Science 40, 110–120. Yusuf, M., Singh, N.P. and Dastane, N.G. (1979) Effect of frequency and timings of irrigation on grain yield and water use efficiency of lentil. Annals of Arid Zone 18, 127–134. Zhang, H., Pala, M., Oweis, T. and Harris, H. (2000) Water use and water-use efficiency of chickpea and lentil in a Mediterranean environment. Australian Journal of Agricultural Research 51, 295–304.

13

Soil Nutrient Management

S.S. Yadav,1 David L. McNeil,2 Mitchell Andrews,3 Chengci Chen,4 Jason Brand,5 Guriqbal Singh,6 B.G. Shivakumar7 and B. Gangaiah7 1National

Agricultural Research Institute (NARI), Papua New Guinea; 2University of Tasmania, Hobart, Tasmania, Australia; 3University of Sunderland, Sunderland, UK; 4Central Agricultural Research Center, Montana State University, Moccasin, Montana, USA; 5Department of Primary Industries, Horsham, Victoria, Australia; 6 Punjab Agricultural University, Ludhiana, Punjab, India; 7Indian Agricultural Research Institute, New Delhi, India

13.1. Introduction If soil fertility is non-limiting and the crop is relatively free from weeds and diseases through all growth stages, then lentil growth is greatly dependent on weather conditions. In this situation, physiological processes respond to changes in air and soil temperature, solar radiation, moisture availability and wind speed. The importance of weather inputs is highlighted by the inputs into a lentil crop growth model (LENMOD) developed and calibrated in experiments carried out on a silt loam soil at Lincoln, Canterbury, New Zealand (43.38°S, 172.30°E, 11 m above sea level). The model was created using the cultivar ‘Titore’, a small-seeded, red variety of lentil (McKenzie and Hill, 1989; McKenzie et al., 1994). LENMOD assumes soil fertility is non-limiting and requires the input of daily values of maximum and minimum air temperature, solar radiation, precipitation, potential evapo-transpiration and day length. With only these inputs, LENMOD has accurately predicted lentil growth in a wide variety of situations (Andrews et al., 2001). However, in many situations soil fertility is, or may become, limiting and long- and short-term availability, and addition and removal of nutrients can become a major limitation on lentil production. Under these circumstances, there is a need to determine the biological and economic consequences of the available options for dealing with limitations affecting yield and productivity. The options available are varied and include addition of nutrients in organic or inorganic forms, biological additions (e.g. rhizobia), crop modifications and soil management and ameliorations. The economics and effectiveness of these treatments will interact with the variety, availability of products, yield expectations, state of local knowledge, 194

© CAB International 2009. The Lentil: Botany, Production and Uses (eds W. Erskine et al.)

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growing system, local economics and destiny of the crop. This chapter will consider all these management options and interactions as they apply to both high productivity and subsistence cropping of lentils.

13.2. Nutrient Requirements of Lentil Nutrient removal by the lentil crop The magnitude of nutrient removal from the soil by a lentil crop is dependent on nutrient availability, crop growth and development, and ultimately yield. Traditionally, lentil is grown for subsistence or local consumption on marginal lands on stored soil moisture with no inorganic nutrient input. Under these conditions, lentil yields are relatively low, for example, average yields in India are 0.7 t/ha (FAOSTAT, 2006). However, in several countries, in particular Canada and the USA, over the past 25 years, lentil production has increased greatly in high fertility soils with adequate soil moisture. Under these conditions, yields of 3 t/ha can be achieved (Andrews et al., 2001; FAOSTAT, 2006). The concentrations of essential and beneficial nutrient elements reported in lentil seed are shown in Table 13.1, along with their role in lentil growth and development. Table 13.2 indicates the removal of nutrients by high- and low-yielding lentil crops based on the range of concentrations given in Table 13.1. Generally, lentils obtain the major proportion of their N requirements via N2 fixation and on average (but with a high degree of variability) their residues contribute around 20 kg N/ha to the soil N pool (McNeil and Materne, 2007). However, there will be a net removal of all other nutrients from the system on harvest of lentil seed. The magnitude of this loss will depend on the concentrations of nutrients in the seed and seed yield. For some nutrients, for example Co, losses are small and are likely to be replenished ‘naturally’. However, in other cases, losses will be substantial, especially under high productivity. For example, P loss will be in the range 2.94–7.25 g/kg of seed (Table 13.1) and soil P levels could eventually limit plant growth if P fertilizer is not applied. Therefore in many situations there will be effects of nutrient addition and the response of the lentil crop to different nutrient fertilizers will now be considered. Nutrient requirements of the lentil plant With respect to macronutrients, there have been reports of positive responses to addition of N, P, K, S, Mg and Ca although their effects are not consistent. Generally, lentil can fix adequate amounts of N for growth, and addition of N fertilizer does not increase yield (McNeil and Materne, 2007). However, lentil, as other grain legumes, can take up and assimilate N from the soil prior to nodulation to an extent that affects growth (Andrews et al., 1992). If sown into soil with extremely low available N or cold, wet soil, addition of 10–25 kg N/ha at sowing can stimulate early growth, nodulation

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Table 13.1. Concentrations of essential and beneﬁcial nutrient elements in lentil seed, the role of these elements and the recommendation in relation to their application to lentil crops (Sources: Andrews et al., 2001; Raven et al., 2004; Urbano et al., 2007; Yadav et al., 2007).

Nutrient

Concentration (g/kg)a

N

37.2–48.8

K

2.4–23.7

Ca Mg

0.42–2.10 0.49–2.20

P

2.94–7.25

S

1.00

Cl

NAd

Fe

0.065–0.133

B

0.009–0.011

Mn Zn

0.012–0.054 0.025–0.062

Cu

0.009–0.032

Mo

0.007–0.013

Ni Na Si Co

0.001–0.003 0.11–0.79 NA < 0.001

Roleb

Recommendationc

Nucleic acids, proteins, cofactors Cofactor for many enzymes, osmoticum Signalling, osmoticum Cofactor for many enzymes, osmoticum Nucleic acids, cofactors, regulation Amino acids, lipids, osmoticum Cofactor for photosystem II, osmoticum Cofactor for many redox reactions Cofactor in cell walls

10–25 kg N/ha under speciﬁc conditions 22–74 kg K/ha under speciﬁc conditions Not recommended Not recommended

Cofactor for photosystem II Enzyme cofactor, e.g. carbonic anhydrase Enzyme cofactor, e.g. cytochrome oxidase Enzyme cofactor including nitrogenase Enzyme cofactor, e.g. urease Osmoticum Mechanical, leaf posture Vitamin B12, synthesized by rhizobia

20 kg P/ha under speciﬁc conditions 20 kg S/ha under speciﬁc conditions Not recommended As per need under speciﬁc conditions 0.5–1.1 kg B/ha under speciﬁc conditions Not recommended 2–6 kg Zn/ha under speciﬁc conditions Not recommended 9–35 g Mo/ha under speciﬁc conditions Not recommended Not recommended Not recommended Not recommended

aTaken

from Andrews et al. (2001), Urbano et al. (2007) and Yadav et al. (2007). from Raven et al. (2004). cReferences given in text. dNA, not available. bModiﬁed

and N2 fixation (McKenzie et al., 2007). Application of higher doses of N fertilizer or addition of N to fertile soils is likely to have a negative effect on nodulation and N2 fixation (Turay et al., 1991; Cash et al., 2001). The literature shows a wide variation in the response of lentils to application of P. McKenzie et al. (2007) emphasized this point by presenting results from trials in different countries which range from no response to a 60% increase in yield with additional P up to around 20 kg/ha. In central Montana of the USA, triple super-phosphate was applied to a clay-loam soil

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Table 13.2. Removal of essential and beneﬁcial nutrients in lentil seed, based on maximum and minimum seed concentrations (cf. Table 13.1) and unlimited (3 t/ha) and limited (0.7 t/ha) production environments. Nutrient removal in seed at 3 t/ha crop (kg/ha)

Nutrient removal in seed at 0.7 t/ha crop (kg/ha)

Nutrient

Minimum

Maximum

Minimum

Maximum

N K Ca Mg P S Fe B Mn Zn Cu Mo Ni Na Co

111.600 7.200 1.260 1.470 8.820 3.000 0.195 0.027 0.036 0.075 0.027 0.021 0.003 0.330 0.003

146.400 71.100 6.300 6.600 21.750 3.000 0.399 0.033 0.162 0.186 0.096 0.039 0.009 2.370 0.003

26.040 1.680 0.294 0.343 2.058 0.700 0.046 0.006 0.008 0.018 0.006 0.005 0.001 0.077 0.001

34.160 16.590 1.470 1.540 5.075 0.700 0.093 0.008 0.038 0.043 0.022 0.009 0.002 0.553 0.001

containing 14 ppm extractable Olsen-P. Significant yield increase occurred only once in the 2-year study with the lentil variety ‘Vantage’ at the rate of 14.7 kg P/ha compared to the unfertilized control. However, the increase of forage yield due to P application was much more apparent than that of grain yield (Wen et al., 2008). There are regions of Bangladesh, India, Pakistan and other South Asian countries, where application of around 20 kg P/ ha is likely to increase lentil yield (Ali et al., 2000). Also, in high production systems, additional P at around 20 kg/ha could be beneficial especially if soil P concentration (sodium acetate extract) is less than 4 ppm (Muehlbauer et al., 1995; Mahler, 2007). Similarly, there are areas in South Asia where lentil yield is likely to respond to addition of 20 kg S/ha (Ali et al., 2000) and the general recommendation under improved practice is to add around 20 kg S/ha especially if soil tests give SO4_S concentrations of less than 10 ppm (Muehlbauer et al., 1995; Mahler, 2007). There are few reports in the literature of lentil yield responding to additional K, Mg or Ca (Ali et al., 2000; McKenzie et al., 2007). Nevertheless, in the USA, Muehlbauer et al. (1995) recommended application of 22 kg K/ha to lentil based on a sandy or eroded soil while Mahler (2007) recommended application of 56 kg K/ha if sodium-acetate-extracted soil K is 50–70 ppm and 74 kg K/ha if soil K is less than 50 ppm. Addition of K may improve lentil cooking quality (Wassimi et al., 1978). The literature indicates that Zn, Mo and B are the micronutrients most likely to limit lentil growth in the major lentil-growing areas while Mn and

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Fe may limit lentil growth locally and lentil yields may increase with seed treatments or foliar sprays of ferrous sulfate (Ali et al., 2000). There are a number of reports of a yield response of lentil to additional Zn in the range 2–6 kg/ha (Sharma et al., 1993; Jain et al., 1995; Srivastava et al., 1999). Lentils are particularly susceptible to Zn deficiency when grown after paddy crop as Zn deficiency is common in these soils (Saxena, 1981). The critical limit for available Zn ranges from about 0.5 to 1.81 ppm depending on the extractant used (Saxena, 1981; Mahler, 2007). Mahler (2007) recommended application of 6 kg Zn/ha when Zn soil test levels were less than 0.6 ppm. Also, Shuknesha (1977) reported that soil P and Zn can interact such that when the P : Zn ratio is greater than about 400, Zn may become limiting. Molybdenum is a component of the nitrogenase enzyme and is thus a key micronutrient for legumes. Seed treatment with Mo has been reported to increase seed yields in Bulgaria, India and the USA (Golubev and Lugovskikh, 1974; Ali et al., 2000; Mahler, 2007). Application of 9–35 g Mo/ha is recommended in the USA for soils of pH < 5.7 as a routine treatment, or every third time lentils are grown in a soil (Muehlbauer et al., 1995; Mahler, 2007). Boron deficiency has been reported to limit lentil growth in soils in India, Nepal and the USA (Sakal et al., 1988; Srivastava et al., 1999; Mahler, 2007). For example, application of 0.5 kg B/ha increased yield from 0.1 to 1.5 t/ha in a trial in Nepal (Srivastava et al., 1999). Mahler (2007) recommended application of 1.12 kg B/ha to soils testing less than 0.5 ppm B. Considerable variation in tolerance to B deficiency exists within lentil germplasm and it is possible to select genotypes for low B soils (Sakal et al., 1988; Srivastava et al., 2000).

13.3. Nutrient Management involving Chemical, Organic and Biological Sources Adequate nutrition is essential for optimum crop growth and grain yield and quality of lentil. Table 13.2 indicates the minimum quantities of nutrients that will need to be replaced to maintain the nutrient status of the soil. However, response to applied nutrients, in terms of biomass production and grain yield, will only occur where the availability of a nutrient in soil is below the critical levels to maintain adequate growth. Nutritional response will also depend on the yield potential of the crop which will tend to be lower in water limited situations, that is a crop with a potential of 3 t/ha grain yield will require more nutrients than a crop with 0.7 t/ha potential. Some nutrients need to be replaced regularly, while others almost never because of high natural concentrations and inputs from residues and biological processes. Availability of a nutrient can be influenced by many soil factors such as pH, water status, buffering capacity and clay content (Marschner, 1993). In addition, nutrient availability can often vary throughout a cropping season as a result of changes in soil temperature, water status and depletion from crop usage.

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Improved nutrition can improve the tolerance of the crop to disease and other biotic and abiotic stresses (Marschner, 1993). Conversely, where nutrition promotes excessive vegetative growth, it can create conditions conducive to fungal disease. Excessive vegetative growth can also place a crop at greater risk of yield loss from terminal drought, particularly in rainfed cropping regions, as the vigorous growth consumes moisture reserves that could be utilized during grain fill. Macro- and micronutrients essential to lentil crop growth are similar to most other crop species. However, ultimately, for maximum yield and quality most nutrients will act synergistically, in that the full response to the addition of one nutrient will only be observed when there are adequate concentrations of other nutrients. Macronutrients As lentils have the ability to fix N, in most cases, a lentil crop can be grown without additional N when adequate levels of other nutrients and Rhizobium bacteria are available, particularly those that are critical for nodulation and N2 fixation (see Quinn, Chapter 15, this volume). Additional N up to 20 kg/ha can be beneficial (Kumar et al., 1993; Carter and Materne, 1997; McKenzie et al., 2007). However, high levels of N can reduce nodulation and N2 fixation, but generally do not result in significant yield loss (Bremer et al., 1989; Singh et al., 1997). Phosphorus is one of the most critical nutrients for optimum crop growth and grain yield in lentil. Several studies which have been mentioned earlier also have indicated that in low P soils, application of approximately 10–20 kg P/ha will generally maximize yields (Kumar et al., 1993; Carter and Materne, 1997; Ali et al., 2000). Low P can also reduce nodulation and N2 fixation processes (Gupta and Sharma, 1989; R. Norton, Horsham, 2003, personal communication). Gupta and Sharma (1989) also reported increases in seed protein with addition of P fertilizer. Similar to N and P, positive grain yield and biomass response to K, S, Mg and Ca have been observed (Singh and Chauhan, 1987, 2005; Srinivasarao et al., 2003; Kiss et al., 2004). Increased K and Mg have also been shown to have benefits for N2 fixation (Srinivasarao et al., 2003; Kiss et al., 2004). Micronutrients Additional micronutrient application can have significant effects on crop growth and yield. Increases in biomass and/or yield have been recorded for Zn (Khurana et al., 1998), Mn (Brennan and Bolland, 2003), Fe (Singh et al., 1985), Mo (Biswapati et al., 1998) and B (Srivastava et al., 2000) when soil availability was limited. Increased levels of grain protein have also been measured with additional Zn (Dawood and El-Far, 1994) and Mn (Brennan and Bolland, 2003). Nutrients to maximize crop growth and yield can be supplied through both biological (e.g. bio- or organic fertilizers and crop residues) and inorganic chemical methods as discussed below.

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Organic sources Farmyard manure (FYM) conserves N during the initial phase of the crop cycle, reduces N loss and provides better synchronization of N availability and crop N demand during the latter part of the annual crop cycle (Ghoshal, 2002). Application of 10 t FYM/ha increased the grain yield of lentil considerably (Sinha and Sakal, 1993). Even the lower dose of 5 t FYM/ha has been reported to increase the grain yield of lentil by 12.7% (Sekhon et al., 2008), 17.9% (Singh et al., 2003) and 20.2% (Singh and Sekhon, 2006). FYM not only provides macro- and micronutrients to the crop but also improves physical and biological properties of the soil, which help in improving the grain yield. However, application of FYM to lentil is not a common practice among farmers.

Chemical fertilizers A range of solid and liquid chemical fertilizers are used on lentils. In most cases, the solid chemical fertilizers are in a granulated form and applied at, or near, sowing. Most of the fertilizers used currently are referred to as ‘high analysis’, meaning that the fertilizer has been processed to contain accurate amounts of prescribed nutrients. Two of the most common high analysis fertilizers used in Australia are ‘Grain Legume Super’ and ‘MonoAmmonium Phosphate’ having N–P–K–S ratio of 0:15:0:7 and 10:22:0:0, respectively (Day et al., 2006). These are often applied with added Zn concentrations of up to 5%. Low analysis products such as super-phosphate can also be used to provide P. While these products contain a known amount of P, they have not been highly refined and may contain many additional macro- and micronutrients beneficial for growth. Generally, with the solid, granular fertilizers, the focus is applying sufficient P to maintain growth. One risk with solid, granular fertilizers is that they are in a highly concentrated form, and if placed too close to the seed, they can be toxic. Hence, in many mechanized regions of the world, technologies have been developed to place the fertilizer below or to the side of the seed. Liquid fertilizers can also be used at sowing, but are most commonly used on a crop to correct nutrient deficiencies that appear during the season. As liquids can often be taken up through the leaves, rapid responses to their application (e.g. crop colour change) can be observed compared with the granular fertilizers. Similar to the high analysis granular fertilizers, they generally contain accurate concentrations of nutrients.

Crop residues Crop residues are generally considered as waste. However, they contain large amounts of nutrients and are also a good source of organic matter. Wheat residue applied in combination with fertilizer to a rice-lentil rotation

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increased the activity of soil organic matter, thereby enhancing the nutrient supply rate, which in turn resulted in increased crop growth and better grain yields (Singh, 1995). However, crop residues are not always available for use in nutrient management as they have alternate uses as animal feed especially in developing countries. In some countries such as India (especially northern India), rice straw from the combine-harvested crop is burnt, which not only results in loss of nutrients but also causes environmental pollution. The use of rice straw as an effective nutrient management option needs to be evaluated and, if found suitable, should be popularized.

13.4. Management of Toxic Elements in Lentil pH Management and pH interactions Lentil grows well on slightly acidic (5.5–6.5 pH) to moderately alkaline (7.5–9.0 pH) soils. However, it shows best production performance at neutral pH. Lentil performance is severely hampered in soils with acidic (<5.0) and high (>9.0) pH. Soil pH influences nutrient availability, making some nutrients deficient while others highly available to the point of becoming toxic for growing plants. The effects of soil pH and nutrient availability and their management are discussed below with respect to lentil.

Soil acidity Soil acidity leads to deficiency of P, K, Ca, Mo and B. It can also lead to toxicity of Al, Fe and Mn. Molybdenum deficiency leads to hampered nodulation and symbiotic N2 fixation of legumes. Owing to the above effects, lentil productivity was reduced by 71% in acidic soil as compared to normal soil (Dwivedi, 1996). To alleviate the adverse effects of acidity, liming of soils is advocated to bring the soil pH to around 6.0. A decrease in exchangeable Al, Fe and Mn (as a result of their precipitation as carbonates, oxides and hydroxides, respectively) coupled with an increase in pH, exchangeable Ca and Mg and available nutrients with application of 6 t lime/ha (Table 13.3) resulted in increased lentil seed yield from 325 to 1125 kg/ha (Dwivedi, 1996). The increased availability of P at higher soil pH was ascribed to reduced P fixation while the increased N availability was a result of the accelerated decomposition of organic matter coupled with increased biological activity. Liming increases the availability of soil reserve Mo by increasing pH, hence, the response to Mo fertilization in the presence of lime would be minimal. Besides lime, P and Mo fertilization were found effective in alleviating the Mo deficiency for lentil in acidic soils in the descending order of Mo > P > lime (Mandal et al., 1998). The interaction effects of P (at medium levels of 25 kg/ha) and Mo fertilization on dry matter production and Mo uptake by lentil were found to be positive (Mandal et al., 1998). This was possibly

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Table 13.3. Effect of liming on soil pH, yield and nutrient availability for lentil in an acidic soil (Source: Dwivedi, 1996).

Lime dose (t/ha) 0.0 1.5 3.0 4.5 6.0 CDb P = 0.05 aOC, bCD,

Exchangeable cations Cmol (p+) (kg/ha)

Available nutrients (kg/ha)

pH

Yield (kg/ha)

Al

Fe

Mn

Ca

Mg

N

P2O5

K 2O

OCa

4.6 4.8 5.3 5.9 6.7 4.6

325 475 615 700 1125 685

1.90 1.70 1.40 1.00 0.50 0.25

0.09 0.06 0.05 0.03 0.01 0.02

0.06 0.05 0.03 0.02 0.01 0.01

1.2 1.8 2.4 3.2 4.5 0.5

0.9 1.2 1.8 2.2 2.5 0.8

185 210 225 250 280 15

4.6 5.7 8.3 10.5 13.6 2.5

410 435 465 440 425 18

0.75 0.90 1.02 1.05 1.16 –

Organic carbon. Critical difference.

because of alleviation of Al toxicity owing to its precipitation as aluminophosphates by P fertilization (Haynes and Ludecke, 1981). Rhizobium becomes ineffective in acidic soils; hence, pelleting of Rhizobium-inoculated seeds with CaCO3 enhanced lentil performance (Sarkar and Pal, 1986). The mobility of surface-applied lime is low; thus, it has little impact in situations where subsoil acidity is a problem. Gypsum application is useful in ameliorating subsoil acidity by precipitation of active Al as Al2(SO4)3 and thus increasing the Ca:Al ratio of soil. Fly ash, owing to its alkaline nature, is also effective in ameliorating soil acidity. Similarly, phosphate rocks with low free carbonate content can also act as liming materials for acidic soils. Although the increases in soil pH are low with rock phosphate application, the decrease in exchangeable Al is significant with a corresponding increase in exchangeable Ca of soils.

Salinity and alkalinity Salinity Lentil is one of the most salinity sensitive crops and when it is grown on residual moisture in the post-rainy season (after rice or fallowing in the rainy season in South Asia) it is prone to salinity stress as salts accumulate in the soil solution and are then precipitated towards the soil surface as the soil dries out. Lentil yield and its biological N contribution get reduced by 90–100% (Hoorn et al., 2001; Katerji et al., 2003) at an electrical conductivity (ECe) of 3.1. At over 0.8 ECe in saline soils, deficiency of K and Ca (Finck, 1977) coupled with the toxicity of Na sulfates and chlorides results in reduced nodulation of legumes (Bhardwaj, 1975). This results in poor yield performance. Salinity-induced nodulation inhibition in lentil was ascribed to inhibition of root hair expansion leading to root curling (Sprent and Zahran, 1988).

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An increase in NaCl concentration in soil resulted in increased uptake of Na and Cl, and reduced dry weight, K concentration and K:Na ratio of lentil. The decrease in K:Na ratio indicates the antagonism of Na on K (Turan et al., 2007). Hence, K fertilization is effective in counteracting the effects of Na at low to moderate levels of salinity. However, under high salinity situations, K fertilization may be futile in excluding Na from plants. The high chloride (Cl–1) content of saline soils competitively inhibits phosphate (PO4–3) uptake of plants (Zhukovskaya, 1973). Selection of salinity-tolerant genotypes is the most effective way of overcoming the salinity impacts (Maher et al., 2003). Application of Ca was found to reduce the Na:Ca ratio and the deleterious effects of NaCl salinity on germination and seedling growth of lentil were reduced at a 14:1 ratio (Astaraei and Forouzan, 2000). Inoculation of lentil seeds with Rhizobium in a saline soil with an ECe of 6 dS/m increased dry matter production by 22.9% (Ahmad et al., 1986). Inoculation also increased the N and P contents of plants. Seed pelleting of Rhizobium-inoculated seeds with CaSO4 enhanced lentil performance in a saline soil (Poi, 2005). Alkalinity Alkaline soils are characterized by the occurrence of excess Na that adversely affects the physical properties of soil under waterlogging and nutrient availability to plants. In sodic soil (pH >8.5), N availability (owing to high volatilization losses) as well as Fe is reduced. The reduced Fe availability is due to high CaCO3 (Singh et al., 1985) and production of bicarbonate with decomposing organic matter that increases the available phosphate which reduces Fe availability to the plant (Brown et al., 1959). Zinc availability is reduced as a result of increased Zn fixation (Gupta et al., 1987). Manganese is also less available (Brennan and Bolland, 2003). Sodic soils can also lead to toxic concentrations of P (Chabra et al., 1981; Gupta et al., 1987), B and Mo. The application of gypsum reduces the available P (Chabra et al., 1981) by lowering pH and ECe. Gypsum was more efficient in reducing these parameters than pyrite (Misra et al., 2007). Gypsum application also decreases the toxicity of Mo to plants owing to antagonistic effects of sulfate on the molybdate ion. Similarly, gypsum aids in the transformation of B from highly soluble sodium metaborate to relatively insoluble calcium metaborate (Gupta, 1979): this can result in substantial increases in lentil yield. Zinc fertilization (20 ppm) in alkaline soils enhanced nodulation and biomass production of lentil. Zinc induces alkalinity tolerance in lentil owing to reduced Na uptake and increased K, Ca and Mg uptake resulting in a narrowing down of the Na:K and Na:(Ca + Mg) ratios (Misra and Tiwari, 1998). In calcareous soils, the critical limit of available Fe was estimated as 6.95 and 74.5 ppm in soil and lentil plant, respectively. In soils with <6.95 ppm available Fe, lentil yield increase varied from 13.31 to 53.97% with application of 10 ppm Fe (Sakal et al., 1984). Though Fe deficiency is not seen as a limitation on lentil production in Mediterranean climates where it originated,

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significant increases (14–108%) in straw yield were reported with Fe fertilization (Erskine et al., 1993; Zaiter and Ghalayani, 1994). This can be of immense value, as straw is highly important in these areas. It is observed that though germination was not hampered up to a level of exchangeable sodium percentage (ESP) 30, lentil plants failed to survive beyond 25 ESP (Ashraf and Waheed, 1990). A decrease of 50% in biomass production of lentil was recorded at 26 ESP (Das and Mehrotra, 1971). The seed yield of lentil was reduced from 1.7 to 0.2 t/ha with an increase in ESP from 8.5 to 36.0. The K, Ca, N and Mg uptake of lentil and crude protein content of seeds also decreased at higher levels of ESP (Singh, 1988).

Toxicities In specific environments, a number of other elements can reach toxic levels sufficient to reduce lentil growth. In a wide variety of situations globally, excess B can limit growth of lentil. In particular, B toxicity is a problem in some arid areas of West Asia and Australia (Yau and Erskine, 2000; McNeil and Materne, 2007). The variation in lentil germplasm to B toxicity can be used to select B tolerant lines (Hobson et al., 2006). Lentil may also be grown in soils contaminated with heavy metals (e.g. As) either naturally or by human input. Under these circumstances, plant growth or safety for consumption may be affected. A variety of solutions have been proposed, such as inoculation with arbuscular mycorrhizal fungi (Ahmed et al., 2006), breeding for altered uptake or modifying water management.

13.5. Strategies for Optimizing Nutrient Use Efficiency in Lentil Nutrients are required to enhance productivity and/or improve the quality of the produce. However, the nutrient use efficiency of lentil is very low. The nutrients can either be lost from the system and cause environmental pollution or are not effectively utilized by the crop. This results in increased cost of production and lower profits for farmers. The nutrient requirements of lentil will depend greatly on soil status and yield potential of the crop. There is a need to increase the nutrient use efficiency using the following strategies.

Diagnostic tools for nutrient status Before raising a crop, the soil should be analysed to assess the status of macro- and micronutrients so that the crop is fertilized as per its need. The response to applied P, for example, depends upon the initial P status in the soil. In low and medium P soils, lentil responded significantly to 40 kg P2O5/ha, whereas in high P soils, the response was significant only up to 20 kg P2O5/ha (Dhillon and Vig, 1996). It was also found that organic C content was a superior index to Olsen-P for assessing P availability to lentil.

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Plant samples can also be analysed to assess the nutrient needs of the crop. For lentil, the critical P concentrations in shoots, leaves and grains are reported to be 0.28%, 0.33% and 0.26%, respectively (Rashid and Bughio, 1993). Similarly, leaf analysis could be used to assess the requirements for S fertilization (Huang et al., 1992).

Time and method of fertilizer application in relation to environment Phosphorus and K are generally applied at the time of sowing the crops. However, they may also be applied by foliar application. Foliar spray with solutions of calcium superphosphate at 11.9 kg/ha or a mixture of 23.8 kg calcium superphosphate + 11.9 kg K2SO4/ha resulted in significant increases in yield and yield components of lentil (Zahran et al., 1998). Drought conditions decrease the Zn uptake by lentil (Gulser et al., 2004). Soil application of 12.5 kg ZnSO4/ha provided the highest grain yield of lentil compared with soil application of 6.25 or 25 kg ZnSO4/ha or foliar application of Zn (Azad et al., 1993). However, Gangwar and Singh (1994) reported that when Zn was applied through seed coating as ZnO or to soil or by foliar application as ZnSO4, the grain yields from the three application methods were in the order seed coating > foliar application > soil application.

Integrated use of different nutrient sources To obtain optimum yields, the crop needs various nutrients in balanced doses, which could be applied through different sources. The application of 18 kg N + 46 kg P2O5 + 20 kg K2O + 25 kg ZnSO4/ha in combination provided the highest nodulation (Jain et al., 1995) and grain yield of lentil (Sharma et al., 1993) in comparison with a range of less complex nutrient treatments. Yadav et al. (2008) reported higher grain yield and N uptake by lentil with the combined inoculation of Rhizobium and Azospirillum brasilense. The combination of phosphobacterial inoculation and 35 kg P2O5/ha provided higher water use efficiency, total P uptake and net returns compared with no P application or 35 kg P2O5/ha alone (Venkateswarlu and Ahlawat, 1993). In the absence of Rhizobium inoculation, application of 12.5 kg N + 40 kg P2O5/ha is recommended (PAU, 2006). However, when seed is inoculated with Rhizobium, then 12.5 kg N + 20 kg P2O5/ha is sufficient, thus offering an opportunity to save 20 kg P2O5/ha (Zarei et al., 2006).

13.6. Economics of Nutrient Management in Lentil Socio-economic factors Under all farming conditions, economic considerations (the cost of inputs and expected returns from the output) should be taken into account before

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deciding the nature of nutrient management. When the expenditure on a nutrient is not sufficiently compensated by way of increased yield and monetary returns, application of nutrients in the form of manures or fertilizers is not warranted. Only when there is reasonable assurance that the crop yield will be increased sufficiently to compensate for the costs of nutrients, does the possibility exist of going for optimum doses of nutrients.

13.7. Economics of Application of Nutrients and Biofertilizers While many experiments have looked at the impact of different nutrients on the productivity of lentil, much less work has been reported on the economics of lentil nutrient management. A brief account of the reports on the economics of the application of nutrients and biofertilizers to lentil is now given. Due to ability of lentil to fix atmospheric N2, little attention has been given to the economics of N application. However, use of Rhizobium inoculants for managing N nutrition has been considered. In soils lacking adequate rhizobia, additional gross return, net return and net return per rupee of investment of Rs2521, Rs2496 and Rs0.57, respectively, were obtained after Rhizobium inoculation (Arpana et al., 2002). Phosphorus availability can be an important factor determining the success of many legumes including lentil. Besides inorganic sources, P solubilizing bacteria and vesicular arbuscular mycorrhizae fungi have been utilized to enhance the availability of P and increase the productivity and monetary returns of lentil. Phosphobacterial inoculation alone or with 35 kg P2O5/ha gave highest water use efficiency and net returns in a multi-treatment experiment in Delhi, India (Venkateswarlu and Ahlawat, 1993). In an experiment in Pakistan, application of P at the rate of 50 kg P2O5/ha gave a return of Rs9.0 for each rupee invested in fertilizer (Khan et al., 2006). (The approximate exchange rate is US$1 = Indian Rs42.) Potassium is the third most important element needed for healthy growth and productivity of lentil. It is often adequate in many lentil-growing areas. However, lentil can show economic responses to application of K. In Uttar Pradesh, India, application of 40 kg K2O/ha produced an additional yield of 273 kg/ha, a net return of US$65 and a benefit:cost ratio of 11 to 1 (IPNI, 2007). There are also reports that application of 20–30 kg S/ ha would be sufficient to realize higher economic returns from lentil and in some areas, increased monetary returns were observed up to 50 kg S/ ha (Shivakumar et al., 1995). Application of some micronutrients (Fe, Mo and B) has had a positive effect on the growth and development of lentil in many areas but their economics has not been studied in detail. However, in the B deficient areas of eastern India, an 8% increase in benefit:cost ratio was observed in lentil when boronated NPK was used (Dibyendu et al., 2006). The economics of a few combinations of nutrients has been studied. In central India, the heart of the lentil belt, application of 18 kg N + 46 kg

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P2O5 + 20 kg K2O + 20 kg S/ha was observed to give the highest net returns when compared to any individual or other combined applications (Gwal et al., 1995). Sharma (1996) reported significantly higher grain yield, net return and benefit:cost ratio with the application of 20 kg N + 50 kg P2O5/ha along with Rhizobium seed inoculation compared to individual applications or other combinations. Shah et al. (2000) reported that a 40 kg N + 80 kg P/ha combination gave a net return of US$189 as compared to the unfertilized control and there was an income of US$7 for each dollar invested on fertilizers. The net return per rupee of investment with application of chemical N:P:K fertilizer at 20:40:20 kg/ha (Rs2.70) or 5 t FYM/ ha (Rs2.69) was superior over the control (Rs2.41) (Arpana et al., 2002). As lentil is cultivated in many cropping systems, both sequential and mixed cropping, quite often nutrient studies have been carried out for the system rather than for the individual crops. Since it is difficult to separate individual crop requirements in systems, it is useful to have a general understanding of the system requirements rather than the component crop requirements. The fertilizer treatment of 80 kg N + 30 kg K/ha to rice and 10 kg N + 60 kg P2O5/ha to utera lentil (relay seeding of lentil before rice harvest) in a rice–lentil cropping system, resulted in a net return of Rs12,215/ha. The total net income was more than doubled by applying fertilizer to both crops under residual soil moisture (Dwivedi and Sharma, 2005). As lentil is an important component of many farming systems, nutrient management for the whole system will be more useful than for individual components. Further, the economics of nutrient management for all nutrients taken together rather than for individual nutrient applications is needed because of potential antagonistic or synergistic effects.

References Ahmad, M., Athar, M. and Niazi, B.H. (1986) Effect of Rhizobium inoculation on growth and crude protein/nitrogen contents of lentil in relation to salinity. LENS Newsletter 13, 16–19. Ahmed, F.R.S., Killham, K. and Alexander, I. (2006) Influences of arbuscular mycorrhizal fungus Glomus mosseae on growth and nutrition of lentil irrigated with arsenic contaminated water. Plant and Soil 283, 33–41. Ali, M., Dahan, R., Mishra, J.P. and Saxena, N.P. (2000) Towards the more efficient use of water and nutrients in food legume cropping. In: Knight, R. (ed.) Linking Research and Marketing Opportunities for Pulses in the 21st Century. Kluwer Academic Publishers, Dordrecht, The Netherlands, pp. 355–368. Andrews, M., Hill, G.D., Raven, J.A. and Sprent, J.I. (1992) Nitrate effects on leaf growth of grain legumes prior to nodulation: species differences relate to nitrate uptake. In: Proceedings of the First European Conference on Grain Legumes. L’Association Européenne de Recherche sur les Protéagineuse (AEP), Paris, France, pp. 139–140. Andrews, M., McKenzie, B.A., Joyce, A. and Andrews, M.E. (2001) The potential of lentil, Lens culinaris, as a grain legume crop in the UK: an assessment based on a crop growth model. Annals of Applied Biology 139, 293–300.

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S.S. Yadav et al. Arpana, Bharati, V., Kumar, S.D., Sushma, Prasad, S.M. and Prasad, T.N. (2002) Yield and economics of late sown lentil as affected by inoculation, fertility and irrigation. Journal of Applied Biology 12, 31–34. Ashraf, M. and Waheed, A. (1990) Screening of local/exotic accessions of lentil Lens culinaris Medic. for salt tolerance at two growth stages. Plant and Soil 128, 167–176. Astaraei, A.R. and Forouzan, G.M. (2000) Effect of calcium ion on germination and seedling growth of lentil Lens culinaris Medik. in different levels of salinity. Biban 5, 37–49. Azad, A.S., Manchanda, J.S., Gill, A.S. and Bains, S.S. (1993) Effect of zinc application on grain yield, yield components and nutrient content of lentil. LENS Newsletter 202, 30–33. Bhardwaj, K.K.R. (1975) Survival and symbiotic characteristics of rhizobium in saline alkali soils. Plant and Soil 43, 377–383. Biswapati, M., Pal, S. and Mandal, L.N. (1998) Effect of molybdenum, phosphorus and lime application to acid soils on dry matter yield and molybdenum nutrition of lentil. Journal of Plant Nutrition 211, 139–147. Bremer, E., Van Kessel, C. and Karamanos, R. (1989) Inoculant, phosphorus and nitrogen responses of lentil. Canadian Journal of Plant Science 69, 691–701. Brennan, R.F. and Bolland, M.D.A. (2003) Application of fertilizer manganese doubled yields of lentil grown on alkaline soils. Journal of Plant Nutrition 26, 1263–1276. Brown, J.C., Lunt, O.R., Holmes, R.S. and Tiffin, L.O. (1959) The bicarbonate ion as indirect cause of iron chlorosis. Soil Science 88, 260–266. Carter, J. and Materne, M.A. (1997) Lentil Growers Guide. Department of Natural Resources and Environment, Victoria, Australia. Cash, D., Lockerman, R., Bowman, H. and Welty, L. (2001) Growing lentils in Montana. MontGuide MT199615AG. Montana State University Extension Service, Bozeman, Montana, USA. Chabra, R., Abrol, I.P. and Singh, M.V. (1981) Dynamics of phosphorus during reclamation of sodic soils. Soil Science 132, 319–322. Das, S.K. and Mehrotra, C.L. (1971) Salt tolerance of some agricultural crops during early growth stages. Indian Journal of Agricultural Sciences 41, 882–885. Dawood, R.A. and El-Far, I.A. (1994) Response of agronomic and quality characteristics of lentil to foliar microelements. Assiut Journal of Agricultural Sciences 25, 143–154. Day, T., Day. H., Hawthorne, W., Mayfield, A., McMurray, L., Rethus, G. and Turner, C. (2006) In: Lamb, J. and Poddar, A. (eds) Grain Legume Handbook. Finsbury Press, Riverton, South Australia, Australia. Dhillon, N.S. and Vig, A.C. (1996) Response of lentil to P in relation to organic carbon and Olsen-P in soil. Journal of the Indian Society of Soil Science 44, 433–436. Dibyendu, S., Biswapati, M., Sarkar, A.K., Singh, S., Jena, D., Patra, D.P. and Phillips, M. (2006) Performance of boronated NPK in B deficient soils. Indian Journal of Fertilizers 1, 57–59. Dwivedi, G.K. (1996) Tolerance of some crops to soil acidity and response to liming. Journal of the Indian Society of Soil Science 44, 736–741. Dwivedi, R.K. and Sharma, R.S. (2005) Nutrient management of utera lentil (Lens culinaris) under rice-based cropping system. Crop Research Hisar 29, 179–181. Erskine, W., Saxena, N.P. and Saxena, M.C. (1993) Iron deficiency in lentil: yield loss and geographic distribution in a germplasm collection. Plant and Soil 151, 249–254. FAOSTAT (2006) Available at: www.fao.org/statistics/countrystat (accessed 5 February 2007). Finck, A. (1977) Soil salinity and plant nutritional status. In: Proceedings of the International Conference on Managing Saline Water for Irrigation. Texas Tech University, Lubbock, Texas, USA, pp. 199–210.

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Gangwar, K.S. and Singh, N.P. (1994) Studies on zinc nutrition on lentil in relation to dry matter accumulation, yield and N, P uptake. Indian Journal of Pulses Research 7, 33–35. Ghoshal, N. (2002) Available pool and mineralization rate of soil N in a dryland agroecosystem: effect of organic soil amendment and chemical fertilizer. Tropical Ecology 43, 363–366. Golubev, V.D. and Lugovskikh, M.A. (1974) Pre-sowing treatment of lentil seeds with ammonium molybdate. Khimiya v Selskom Khozyaisve 12, 24–25. (in Russian) Gulser, F., Togay, Y. and Togay, N. (2004) The effects of zinc application on zinc efficiency and nutrient composition of lentil (Lens culinaris Medic.) cultivars. Pakistan Journal of Biological Sciences 7, 751–759. Gupta, B.R. and Sharma, A.K. (1989) Interactive effect of Rhizobium and phosphorus on nodulation, crop yield and nitrogen fixation in lentil (Lens culinaris Medic.). Farm Science Journal 4, 47–53. Gupta, I.C. (1979) Note on the effect of leaching and gypsum on detoxification of boron in a saline, sodic soil. Current Agriculture 3, 231–234. Gupta, R.K., Van den Elshout, S. and Abrol, I.P. (1987) Effect of pH on Zn adsorption precipitation reactions in an alkali soil. Soil Science 143, 198–204. Gwal, H.B., Tiwari, R.J. and Gupta, D.K. (1995) Fertilizer management of lentil under rainfed conditions in Madhya Pradesh. LENS Newsletter 22, 11–12. Haynes, R.J. and Ludecke, T.D. (1981) Yield and root morphology and chemical composition of two pasture legumes as affected by lime and phosphorus application. Plant and Soil 62, 241–254. Hobson, K., Armstrong, R., Nicolas, M., Connor, D. and Materne, M.A. (2006) Response of lentil (Lens culinaris Medic.) germplasm to high concentrations of soil boron. Euphytica 151, 371–382. Hoorn, J.W., Katerji, N., Hamdy, A. and Mastrorilli, M. (2001) Effect of salinity on yield and nitrogen uptake of four grain legumes, and on biological nitrogen contribution from soil. Agricultural Water Management 51, 887–898. Huang, W.Z., Schoenau, J.J. and Elmy, K. (1992) Leaf analysis as a guide to sulfur fertilization of legumes. Communications in Soil Science and Plant Analysis 23, 1031–1042. International Plant Nutrition Institute (IPNI) (2007) Institute Annual Report. IPNI, Norcross, Georgia, USA. Jain, R.C., Tiwari, R.J. and Nema, D.P. (1995) Integrated nutrient management for lentil under rain-fed conditions in Madhya Pradesh. II. Nodulation, nutrient content and economics. LENS Newsletter 22, 13–15. Katerji, N., Hoorn, J.W., Hamdy, A. and Mastrorilli, M. (2003) Salinity effect on crop development and yield analysis of salt tolerance according to several classification methods. Agricultural Water Management 62, 37–66. Khan, H., Ahmad, F., Ahmad, S.Q., Sherin, M. and Abdul Bari, A. (2006) Effect of phosphorus fertilizer on grain yield of lentil. Sarhad Journal of Agriculture 22, 433–436. Khurana, M.P.S., Bansal, R.L. and Nayyar, V.K. (1998) Influence of zinc application on yield and micronutrient nutrition of lentil grown on Typic Ustochrepts. LENS Newsletter 25, 38–41. Kiss, S.A., Stefanovitis-Banyai, E. and Takacs, M. (2004) Magnesium-content of rhizobium nodules in different plants: the importance of magnesium in nitrogen fixation of nodules. Journal of the American College of Nutrition 23, 751–753. Kumar, P., Agarwal, J.P. and Chandra, S. (1993) Effect of inoculation, nitrogen and phosphorus on growth and yield of lentil. LENS Newsletter 20, 57–59.

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S.S. Yadav et al. Maher, L., Armstrong, R. and Connor, D. (2003) Salt tolerant lentils – a possibility for the future? Solutions for a better environment. Proceedings of the 11th Australian Agronomy Conference, Geelong, Victoria, Australia, 2–6 February 2003, pp. 0–4. Mahler, R.L. (2007) Peas and Lentils. Northern Idaho Fertiliser Guide. Current Information Series No. 448. Available at: www.uidaho.edu/wgfert (accessed 27 July 2007). Mandal, B., Pal, S. and Mandal, L.N. (1998) Effect of molybdenum, phosphorus and lime application to acidic soils on dry matter yield and molybdenum nutrition of lentil. Journal of Plant Nutrition 21, 139–147. Marschner, H. (1993) Mineral Nutrition of Higher Plants. Academic Press, London, UK. McKenzie, B.A. and Hill, G.D. (1989) Environmental control of lentil (Lens culinaris) crop development. Journal of Agricultural Science, Cambridge 113, 67–72. McKenzie, B.A., Hill, G.D. and Gallagher, J.N. (1994) Computer simulation model of lentil growth and development. LENS Newsletter 21, 31–35. McKenzie, B.A., Andrews, M. and Hill, G.D. (2007) Nutrient and irrigation management. In: Yadav, S.S., McNeil, D.L. and Stevenson, P.C. (eds) Lentil: an Ancient Crop for Modern Times. Springer, Dordrecht, The Netherlands, pp. 145–158. McNeil, D.L. and Materne, M.A. (2007) Rhizobium management and nitrogen fixation. In: Yadav, S.S., McNeil, D.L. and Stevenson, P.C. (eds) Lentil: an Ancient Crop for Modern Times. Springer, Heidelberg, pp. 127–143. Misra, S.K. and Tiwari, K.N. (1998) Effect of salt and zinc stress on performance of different cultivars of lentil. Indian Journal of Pulses Research 11, 43–47. Misra, S.M., Tiwari, K.N. and Sai Prasad, S.V. (2007) Reclamation of alkali soils: influence of amendments and leaching on transformation and availability of phosphorus. Communications in Soil Science and Plant Analysis 38, 1007–1028. Muehlbauer, F.J., Kaiser, W.J., Clement, S.L. and Summerfield, R.J. (1995) Production and breeding of lentil. Advances in Agronomy 54, 283–332. Poi, S.C. (2005) Establishment of grain legumes with effective Rhizobium in some problem soils of West Bengal. In: Kharkwal, M.C. (ed.) Abstracts of the Fourth International Food Legumes Research Conference, October 2005, New Delhi, India, p. 264. Punjab Agricultural University (PAU) (2006) Package of Practices for Crops of Punjab, Rabi 2006–07. PAU, Ludhiana, India. Rashid, A. and Bughio, N. (1993) Evaluating internal phosphorus requirement of rapeseed, chickpea, lentil, and wheat by seed analysis. Communications in Soil Science and Plant Analysis 24, 1359–1369. Raven, J.A., Handley, L.L. and Wollenweber, B. (2004) Plant nutrition and water use efficiency. In: Bacon, M.A. (ed.) Water Use Efﬁciency in Plant Biology. Blackwell Publishing, Oxford, UK, pp. 171–197. Sakal, R., Singh, B.P. and Singh, A.P. (1984) Determination of threshold value of iron in soils and plants for the response of rice and lentil to iron application in calcareous soil. Plant and Soil 82, 141–148. Sakal, R., Singh, A.P. and Sinha, R.B. (1988) Differential reaction of lentil cultivars to boron application in calcareous soil. LENS Newsletter 15, 27–29. Sarkar, H.K. and Pal, A.K. (1986) Efficacy of Rhizobium inoculation, liming and pelleting with CaCO3 in lentil cultivation in the acid laterite soil of West Bengal. Environment and Ecology 4, 67–77. Saxena, M.C. (1981) Agronomy of lentils. In: Webb, C. and Hawtin, G. (eds) Lentils. Commonwealth Agricultural Bureau, Farnham, UK, pp. 111–129. Sekhon, H.S., Singh, G., Khanna, V., Sharma, P. and Ram, H. (2008) Effect of FYM, phosphorus and phosphorus solubilizing bacteria on microbial traits, growth and yield of lentil. Ecology, Environment and Conservation 14, 159–163.

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Shah, N.H., Hafeez, F.Y., Arshad, M. and Malik, K.A. (2000) Response of lentil to Rhizobium leguminosarum bv viciae strains at different levels of nitrogen and phosphorus. Australian Journal of Experimental Agriculture 40, 93–98. Sharma, A.K., Billore, S.D. and Singh, R.P. (1993) Integrated nutrient management for lentil under rainfed conditions. LENS Newsletter 20, 15–16. Sharma, M.C. (1996) Economic response of lentil to seed rate, row spacing, Rhizobium inoculation and chemical fertilization. LENS Newsletter 23, 1518. Shivakumar, B.G., Saraf, C.S. and Patil, R.R. (1995) Effect of phosphorus and sulfur levels and limited irrigation on the performance of macrosperma lentil. LENS Newsletter 22, 19–23. Shuknesha, A. (1977) Influence of zinc on survival of rhizobia, nutrient uptake and nitrogen fixation by lentil (Lens esculenta Moench). Pantnagar Journal of Research 2, 259. Singh, B.P., Sakal, R. and Singh, A.P. (1985) Response of lentil varieties to iron application on highly calcareous soils of Bihar. Indian Journal of Agricultural Sciences 55, 56–58. Singh, G. and Sekhon, H.S. (2006) Effect of farmyard manure, phosphorus and seed rate on the growth and yield of bold-seeded lentil. Journal of Plant Science Research 22, 243–245. Singh, H. (1995) Nitrogen mineralization, microbial biomass and crop yield as affected by wheat residue placement and fertilizer in a semi-arid tropical soil with minimum tillage. Journal of Applied Ecology 32, 588–595. Singh, O.N., Sharma, M. and Dash, R. (2003) Effect of seed rate, phosphorus and FYM application on growth and yield of bold seeded lentil. Indian Journal of Pulses Research 16, 116–118. Singh, S.B. (1988) Effect of soil sodicity on the growth and chemical composition of lentil. India Journal of Pulses Research 1, 152–155. Singh, S., Gangwar, M.S. and Singh, H.P. (1997) Effect of N, P and K fertilization on nodulation, N-concentration in nodules and plant growth of lentil. Annals of Agricultural Research 18, 120–123. Singh, V. and Chauhan, D.V.S. (1987) Effect of phosphorus and sulphur on yield and quality of lentil (Lens esculenta M.). Annals of Plant Physiology 1, 227–232. Singh, Y.P. and Chauhan, C.P.S. (2005) Effect of sulphur, phosphorus and Rhizobium inoculation on yield, content of micronutrients and phosphorus utilization of lentil. Indian Journal of Pulses Research 18, 211–213. Sinha, R.B. and Sakal, R. (1993) Effect of pyrite and organic manures on sulphur nutrition of crops in calcareous soil. I. Direct effect on lentil. Journal of the Indian Society of Soil Science 41, 312–315. Sprent, J.I. and Zahran, H.H. (1988) Infection and development and functioning of nodules under drought and salinity. In: Beck, D.P. and Materon, L.A. (eds) Nitrogen Fixation by Legumes in the Mediterranean Agriculture. Martinus Nijhof, Dodrecht, The Netherlands, pp. 145–151. Srinivasarao, C., Masood, A., Ganeshamurthy, A.N. and Singh, K.K. (2003) Potassium requirements of pulse crops. In: Better Crops. Potash and Phosphate Institute, Saskatoon, Saskatchewan, Canada, pp. 8–11. Srivastava, S.P., Joshi, M., Johansen, C. and Rego, T.J. (1999) Boron deficiency of lentil in Nepal. LENS Newsletter 26, 22–24. Srivastava, S.P., Bhandari, T.M.S., Yadav, C.R., Joshi, M. and Erskine, W. (2000) Boron deficiency in lentil: yield loss and geographic distribution in a germplasm collection. Plant and Soil 219, 147–151. Turan, M.A., Turkmen, N. and Taban, N. (2007) Effect of NaCl on stomatal resistance and proline, chlorophyll, Na, Cl and K concentrations of lentil plants. Journal of Agronomy 6, 378–381.

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14

Cropping Systems and Production Agronomy

Masood Ali,1 K.K. Singh,1 S.C. Pramanik1 and Mohamed Omar Ali2 1Indian

Institute of Pulses Research, Kanpur, Uttar Pradesh, India; 2Bangladesh Agriculture Research Institute, Ishurdi, Bangladesh

14.1. Introduction Lentil (Lens culinaris Medikus subsp. culinaris) was among the first crops domesticated in West Asia and introduced into the Indo-Gangetic Plains around 2000 bc (Cubero, 1981). It has become an important food legume crop in the farming and food systems of many countries like West Asia, the Indian subcontinent, Ethiopia and North Africa and to a lesser extent in southern Europe. Its seed is a rich source of protein, minerals and vitamins for human nutrition, and the straw is a valued animal feed (see Grusak, Chapter 23, this volume; Erskine et al., 1990). Furthermore, as a result of its high lysine and tryptophan content, its consumption with cereal provides balanced nutrition. It has the potential to cover the risk generally encountered in dryland agriculture (Kumvanshi et al., 2004). Its ability to sequester nitrogen and carbon improves soil nutrient status, which in turn provides sustainability to production systems. Lentil is produced in over 48 countries worldwide though the major lentil-producing region is South Asia (see Erskine, Chapter 2, this volume). In India, cultivation extends from the warm regions of Madhya Pradesh and Maharashtra to the cold areas of Ladakh in Kashmir at an altitude of over 3500 m above sea level. The crop is thus widely adapted ecologically, primarily for rainfed systems and grown by a wide range of farmers from small to large. Lentil growers in different countries face the challenges of relatively similar biotic and abiotic stresses which are responsible for low productivity.

14.2. Lentil in Cropping Systems Lentil is grown as a winter crop largely under rainfed conditions in residual/ conserved moisture. However, in the northern regions of India, like Punjab, © CAB International 2009. The Lentil: Botany, Production and Uses (eds W. Erskine et al.)

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Haryana and western Uttar Pradesh, it is also irrigated. Depending upon annual precipitation and distribution, ground water availability, and demands of the local cropping cycle, lentil is grown in different cropping systems as a monocrop or as a component of double cropping, mixed cropping and relay cropping. In Bangladesh, lentil is mostly grown in the upland rice (aus)/jute (Corchorus capsularis L.) fallow-lentil cropping pattern, and is usually sown by midNovember. It is also broadcast in aman rice 7–10 days before harvest to capitalize on residual moisture. These practices ensure profitable use of rice fallows. More than 85% of the lentil area in Bangladesh is concentrated in the medium-high topography lands of Jessore, Faridpur, Kushtia and Rajshahi districts. The inclusion of lentil in various cropping systems benefits the companion crop or succeeding crop by improving the physical and chemical properties of soil as a result of biological nitrogen fixation and other rotational effects (Ahlawat et al., 1981; Prakash et al., 1986; George and Prasad, 1989; Ali, 1994; Shah et al., 2003; Wisal, 2003). Experiments conducted in the temperate ecosystem of Kashmir, India showed that nutrient status and the balance of nutrients were significantly influenced by the cropping system. The rice-lentil system increased the nutrient status of soil (Singh and Sofi, 2007). Results from two different experiments conducted in dry farming areas of Central Anatolia (Haymana-Ankara and Gözlü-Konya) to detect the effect of fallow and winter lentil and different tillage systems on wheat yields proved that sowing of winter lentil was more profitable instead of leaving land fallow before wheat. Results showed that protein content of wheat was increased by 2.12–2.15% after lentil in Haymana and Gözlü (Eser and Adak, 1999).

Monocropping Monocropping lentil is a common practice in India in the heavy textured soils of the Bundelkhand region of Uttar Pradesh and Madhya Pradesh, where rainfall does not support a good kharif (monsoon) crop. Hence, fields are left fallow during the kharif season and lentil is sown on the conserved moisture. It is also practised in heavy rainfall areas (>1000 mm) of Bihar, west Bengal, Orissa and eastern Uttar Pradesh in the areas of the Diara lands and Tal lands. In these areas, frequent floods and poor drainage do not allow raising a kharif crop. Thus lentil is sown as monocrop after the floodwater recedes. Diara lands are highly fertile due to the deposition of silt during flood and hence a bumper crop of lentil is harvested. In West Asia and North Africa (WANA) lentil is sown in rainfed cropping areas that receive from 300 to 450 mm annual average rainfall. At the lower end of this rainfall spectrum it is taken in rotation with barley, whereas from 350 to 450 mm the predominant cereal is durum wheat and less commonly bread wheat. Temperatures are moderate in winter and relatively hot in summer leading to low and high evapotranspiration in winter and summer, respectively.

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Double cropping Lentil is recognized as being important for crop diversification in South Asia (Sarkar et al., 2004) and consequently its area is expanding. Rice-lentil is a common production system practised in the lowlands of India, Pakistan, Bangladesh and Nepal. In India double cropping with lentil is generally practised after the harvest of kharif crops. The common crop rotations are: rice-lentil; maize-lentil; cotton-lentil; pearl millet-lentil; sorghum-lentil; and groundnut-lentil. In Bangladesh, on the medium-high topography lands of Kushtia, Rajbari, Magura and Jessore districts, which have sandy loam soils, lentil is sown in a broadcast aus paddy rice/jute-fallow-lentil cropping system, whereas on the medium-low topography, which has clay loam soil, lentil is grown after the receding floodwater. The common cropping system in this area is jute-fallow-lentil while the low-lying areas of Faridpur, Kushtia, Rajbari and Natore, which have heavy clay soils, the broadcast aman (long season) rice-lentil-fallow system is adopted.

Mixed cropping In mixed cropping in South Asia, seeds of the component crops are mixed and broadcast. Mixed cropping is practised in rainfed areas under moisture stress conditions as an insurance against adverse biotic and abiotic factors as well as being an economical and efficient use of farm inputs. Reduction in seed yield of lentil was greater in mixed cropping with wheat in an irrigated environment (Ahlawat and Sharma, 1985). Popular crops for mixed cropping systems with lentil are Indian mustard, barley and chickpea. In Turkey, the mixture of 70–80% lentil + 20–30% wheat gave the highest landequivalent ratio for straw and grain yields (Cftc and Ülker, 2005).

Intercropping Under this system, lentil is grown along with other crops in a definite row ratio/planting geometry. The common intercrops with lentil are wheat, barley, Indian mustard and linseed in South Asia. For mixed/intercropping an optimum seeding and planting configuration is very important to achieve high total productivity. In various experiments, lentil + mustard (5:1 or 2:1 row ratio) and lentil + linseed (4:2 or 5:1 row ratio) showed higher yield than growing lentil alone (Sarkar and Pal, 2005; Sekhon et al., 2007; Yadav and Tripathi, 2007). Singh and Rana (2006) reported that a paired row (30/90 cm) of Indian mustard + lentil (two rows) intercropping system proved productive as it gave 370 kg/ha extra yield of lentil without significantly affecting the seed yield of mustard. Lentil is also intercropped with winter wheat and barley; however, lentil + wheat/barley intercropping is not always productive and profitable (Gangasaran and Giri, 1985; Prakash et al., 1986). In Bangladesh,

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Ahmed et al. (1987) found that the most profitable seeding ratio for wheat and lentil was 100:50. Rehman and Shamsuddin (1981) reported that maximum total productivity, land equivalent ratio (LER) and net return under wheat/lentil intercropping was obtained when 30% of the wheat seed rate was sown between lentil rows spaced 30 cm apart. Experimental results on the intercropping of lentil with linseed at different planting configurations also revealed the advantage of intercropping over lentil grown as a sole crop (Miah and Rahman, 1993). In the North Eastern Plains of India, western Terai of Nepal and a large area of Bangladesh, lentil is also intercropped successfully with autumn sugarcane (Srivastava, 1975; Giri, 2005). In autumn, sugarcane-lentil intercropping revealed higher cane equivalent yield than sugarcane alone. In this system, sugarcane is planted in the first week of October and two rows of lentil may be sown 30 cm apart between two rows of sugarcane. Since lentil is a legume crop, there is no need for applying nitrogen fertilizer. The lentil crop can be harvested by the end of March or first week of April. Fertilizer is applied to the sugarcane after the lentil harvest. This system provides 1500–1600 kg/ha of additional lentil yield with no adverse effect on cane yield. Lentil is rarely intercropped outside South Asia.

Relay cropping Relay planting of lentil in rice is practised in South Asia (Saxena, 1981; Ali et al., 1993). Under relay cropping, lentil is broadcast into the standing rice crop (paira or utera cropping) 10–15 days before rice harvest. Relay cropping with rice is generally practised in Chattishgarh and the eastern region of India and eastern Terai of Nepal. In sandy loam soil of the mediumtopography areas of Jessore, Chuadanga, Magura, Meherpur, Kushtia, Rajshahi and the Pabna district of Bangladesh farmers also grow lentil in relay cropping with rice. This practice takes advantage of the residual moisture remaining after rice, gains time and economizes the inputs and ultimately is more productive than normal sowing (Chakraborty et al., 1976; Roysharma et al., 1984; Gupta and Bhowmick, 2005).

14.3. Production Agronomy Climate Lentil requires a cold climate. It is sown as a winter season crop in South Asia and lowland WANA. It is cultivated in a wide range of climatic conditions. The adaptation of lentil to different agroclimatic conditions is covered in more detail by Materne and Siddique (see Chapter 5, this volume). It can be grown successfully up to 3500 m above sea level. It is generally grown on moisture conserved during the rainy season with no inorganic nutrient

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input in South Asia. Under these conditions, lentil yields are relatively low, for example, the average yield in India is 0.7 t/ha (see Erskine, Chapter 2, this volume). However, in several countries, particularly Canada and the USA, over the past 25 years, lentil production has increased greatly due to better crop management (Andrews et al., 2001).

Soil Lentil is adapted to various soil types, from sand to clay loam, provided there is good internal drainage. Lentil does not tolerate flooding or waterlogged conditions, and does best on deep, sandy loam soils that are moderate in fertility. Good drainage is required, because even short periods of exposure to waterlogging or flooded field conditions results in wilting and drying of plants (because excess moisture causes a lack of oxygen supply to roots, preventing root respiration). A soil pH near 7.0 is best for lentil production. Lentil performance is severely hampered in soils with acidic pH (<5) and alkaline pH (>9). Soil pH influences nutrient availability, making some nutrients deficient while other nutrients become highly available and toxic to growing plants. A decrease in exchangeable Al, Fe and Mn (due to their precipitation as carbonates, oxides and hydroxides, respectively) coupled with an increase in pH, exchangeable Ca, Mg and available nutrients with application of 6 t lime/ha resulted in increased lentil seed yield from 325 to 1125 kg/ha (Dwivedi, 1996). In India lentil is grown on a variety of soils such as light loams and alluvial soils of the Punjab and Uttar Pradesh to black cotton soils of Madhya Pradesh. This crop is also suited to poorer types of soils, low-lying situations such as in paddy fields and even to soils of moderate alkalinity.

Cultivars The genotype plays an important role in realizing high productivity. Since genotype × environment interactions are significant, choice of a genotype depends on prevailing agroclimatic conditions, cropping systems, farmers’ choice and local market preferences, etc. Lentil genotypes show significant variation with respect to their productivity, stability and adaptability. Lentil varieties that are suitable for different agroclimatic conditions and cropping systems have been discussed by Sarker et al. (Chapter 8, this volume), Rahman et al. (Chapter 9, this volume) and Muelhbauer et al. (Chapter 10, this volume).

Seedbed preparation/land preparation Land preparation varies according to the soil type, climate and preceding crop in the field. Tillage options and seedbed preparation particularly in

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North America, Australia and the WANA region are covered by Diekmann and Al-Saleh (Chapter 16, this volume). A firm, smooth seedbed with most of the previous crop residues incorporated is best for lentil. Uneven surface, large clods, stones or protruding crop residue can interfere with seed placement and complicate later swathing and combining. The soil for the cultivation of lentil should be made friable and weed free so that seeding could be done at a uniform depth. For optimum germination and crop establishment in South Asia, a temperature range of 15–25°C is desirable. On heavy soils, one deep ploughing followed by two to three cross harrowing, especially under rainfed conditions, ensures proper conservation of moisture in the soil and better germination and growth of the crop. In developed countries, a heavy roller is used to smooth the soil surface after planting and to ensure good soil-to-seed contact for uniform germination and emergence. This practice also provides a smooth surface to facilitate harvesting either by direct combining or swathing (Muehlbauer et al., 1998). Work on tillage management of rice-based sequential cropping systems at the Indian Institute of Pulses Research, Kanpur, showed that relay planting of lentil in the standing crop of rice gave low yields as compared with crop grown with cross harrowing after the harvest of rice (Kumar and Ali, 1995). In light soils, less tillage is needed to prepare an ideal seedbed. In rainfed areas, where moisture is conserved during the preceding monsoon, land preparation should not be done using a soil-turning plough to ensure minimum loss of water. Tomar and Singh (1991) reported higher uptake of N and P by lentil with one ploughing as compared with zero tillage on sandy loam soils of Agra, Uttar Pradesh. After harrowing, the field should be given a gentle slope and nicely compacted using a wooden plank. There should be proper moisture in the soil at the time of sowing for good germination of seeds and to support the plant stand. Direct seeding (no-till) of lentil into standing stubble left after cereal (wheat or barley) harvest is becoming an option in developed countries where soil erosion is a problem. Direct seeding is recommended in the USA for autumn-sown lentil as a means of conserving soil moisture and to provide some surface protection to reduce winter injury for the developing lentil plants (Chen et al., 2006).

Sowing time Since lentil is grown in diverse types of agroecological zones in different cropping systems, its planting time varies accordingly. The time of sowing is very important in relation to plant growth and phenological development to realize the full grain yield. Timely planting reduces incidence of rust (Chaudhary and De, 2005), aphids and Stemphylium (Hossain et al., 2006; Ihasanul Huq and Khan Nowsher Ali, 2007). Delayed sowing of lentil reduced the incidence of soil-borne pathogens, collar rot and stunt (Agrawal et al., 1976; Singh and Dhingra, 1980). However, in Bangladesh delayed planting has been reported to increase disease and insect infestation and hamper

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growth (Khan and Miah, 1986). Lentil is generally grown after the rainy season on conserved soil moisture. Due to short and mild winters in India, Bangladesh and Ethiopia, the life cycle of lentil is limited to 100–120 days. In South Asia, sowing of lentil begins in mid-October and continues to early December; however, the optimum seeding time is before 15 November (Sekhon et al., 1986; Singh and Ram, 1986; Ahmad and Motior, 1993; Ali et al., 1993; Neupane and Bharati, 1993; Singh et al., 2005; Ihasanul Huq and Khan Nowsher Ali, 2007). In Dholi and Bihar, India, a crop sown on 25 October outyielded crops sown on 4 November and 4 December. There was a drastic reduction in yield and yield attributes of lentil when sown on 4 December (Kumar et al., 2005). However, planting can be delayed in the foothills and eastern parts of Punjab to the end of November without much loss in yield (Saxena and Yadav, 1976; Dhingra et al., 1983). In the central zone of India where moisture is limiting, lentil is sown in mid-October. In Assam and adjoining states, sowing is recommended in the first or second week of October. Late planting leads to less vegetative growth and forced maturity and consequently the grain filling is affected. Delay in planting causes reduction in yield but the magnitude of reduction is large after 15 November (Ali et al., 1993; Nandan et al., 2007). In relay planting, broadcasting of seed depends on the timing of the end of the monsoon cycle and the maturity of the rice crop. In the Andean region of Latin America, sowing of lentil is generally done in the early winter period following the onset of the rains. The lentil is sensitive to weed competition. Throughout its range under winter rainfed conditions in the lowland Mediterranean region, sowing is generally delayed to allow cultivation after the early rains for weed control. So early sowing with adequate provision for weed control generally results in major yield gains. In such areas lentil is normally planted at the beginning of the winter season with an appropriate sowing time being up to the middle of December (Saxena, 1981). In southern Australia, where a dryland Mediterranean-type climate is prevalent, early sowing (late April to early May) allowed a longer period for vegetative and reproductive growth, rapid canopy development, greater absorption of photosynthetically active radiation (PAR), more water use, and, hence, greater dry matter production, seed yield and water use efficiency than delayed sowing (Siddique et al., 1998). In cold-prone highland areas of West Asia (above 859 m above sea level) and in parts of the USA (see below), the crop is spring sown. Spring-sown lentils in the highlands frequently suffer from terminal drought. However, shifting sowing from spring to early spring or winter sowing using winterhardy cultivars can increase lentil production significantly. Winter cropping allows optimum vegetative growth and the development of higher yield potential (frequently >50% of spring-sown yields) and provides higher water use efficiency from winter precipitation, providing the cultivar is winter hardy. There is the potential to replace about 400,000 ha of spring lentil with a winter crop in the highlands of West Asia (Sakar et al., 1988). Research on autumn sowing of lentil in these highlands including modelling sowing time from climatic data is summarized in Keatinge et al. (1996).

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Cultivars with winter hardiness are now being cultivated in Turkey and in Iran such lines are under on-farm evaluation. The focus in winter/autumn sowing is to translate the research results into production gains; in this regard weed control is critical. In Argentina and Chile, sowing is done from May to early July, and the lentils are harvested in November and December. Due to low temperatures that cause winter killing of most lentil cultivars, lentil crops in Canada and the USA are planted in early spring. In the states of Idaho, Oregon and Washington in the USA the crop is planted in mid- to late April; while in the northern plains states of North Dakota and Montana and the western provinces of Canada, the crop is usually planted in early to mid-May depending on conditions.

Plant population, spacing and methods of planting Response of lentil to plant densities has been variable, depending upon genotype, planting time and growing conditions. Seeding rate varies from region to region and with seed size. In South Asia, a seed rate of 30–40 kg/ ha is recommended (Zaman and Miah, 1989). In West Asian countries, a higher seed rate of 100–120 kg/ha produces higher yield, the optimum plant stand being 275–300 plants/m2 (Silim et al., 1990). In Alberta, Canada 107 seeds/m2, in the states of Washington Idaho, 215 seeds/m2, (Muehlbauer et al., 1998) and in North Dakota, 172–220 seeds/m2 was optimum (Eriksmoen et al., 2008). Bukhtiar et al. (1991) reported that in lentil the seed rate varied according to seed size. The small-seeded cultivar L9-6 produced a higher yield with a seeding rate of 30 kg/ha while large-seeded cultivar AARIL 355 gave more yield with a 40 kg/ha seed rate. In Bangladesh a seed rate of 30–35 kg/ha with a plant density of 250 plants/m2 has been found optimum (Rahman and Miah, 1989). A seed rate of 40–45 kg/ha for large-seeded lentil and 30 kg/ha for small seeded have been reported as optimum by other workers (Khare et al., 1991; Singh and Singh, 2002). A reduction in seed yield because of delayed planting could be minimized to a certain extent by relatively closer spacing and use of a higher seed rate. A seed rate of 40 and 60 kg/ha gave the same yield when planted on 1 December but when planted on 15 and 30 December a significantly higher yield was obtained with a 60 kg/ha seeding rate (Ahlawat et al., 1982). Nandan et al. (2007) found the higher seed rate of 60 kg/ha optimum over 40 kg in Dholi, Bihar, India. Under utera conditions, a higher seed rate is generally used as all seeds broadcast in a standing rice field do not germinate and the seedlings are damaged. In West Bengal, a seed rate of 70–80 kg/ha gave a higher yield under utera conditions (Gupta and Bhowmick, 2005; Anonymous, 2006). Seed rates of 40 kg/ha and 60 kg/ha were found to be optimum under conditions at Kanpur and Dholi, Bihar, respectively (Kumar et al., 2005). Raised-bed planting has emerged as a promising management technique. At Kanpur, India, raised-bed planting increased grain yield significantly, reduced irrigation requirements, improved branching and podding,

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and increased water use efficiency over traditional flat-bed planting (Singh, 2006). In agriculturally mechanized countries, lentil is planted using grain drills, but elsewhere it is still hand broadcast (Gowda and Kaul, 1982) or seeding is carried out behind a desi (country) plough with a porah (the funnel attached behind the wooden plough used to sow seeds at the appropriate depth). Planting in rows promotes a uniform plant stand, allows for ease of weeding and other cultural operations and improves productivity. Lentil seeds should be sown at about 3–4 cm deep in rows 20 cm apart (Singh et al., 2005). Bidirectional sowing in a row rectangularity of 22.5 × 30 cm gave higher yield than unidirectional sowing in north India (Kler and Dhillon, 1982).

Fertilizer management Lentils are generally grown under very low input conditions in otherwise inherently low productive soils and consequently yields are low. Saxena (1981) reported that a lentil crop yielding 2 t/ha removed 100 kg N, 28 kg P2O5 and 78 kg K2O and essential nutrients from the soil. Studies on the relative contribution of production inputs under different agroecological conditions in India revealed that in the central zone, fertilizer was the premier input followed by weed management (Ali et al., 1993). Judicious and balanced use of nutrients helps the plant to grow vigorously and give maximum yield besides developing resistance against biotic and abiotic stresses. Thus it is imperative that the required nutrients are applied to realize higher productivity. Information is reviewed on soil nutrient management by Yadav et al. (Chapter 13, this volume) and on biological nitrogen fixation and soil health improvement by Quinn (Chapter 15, this volume).

Seed priming Seed priming is another technology through which substantial yield improvement can be achieved. Seed priming is a technique in which seed is soaked in water overnight prior to sowing. This is generally done to hasten germination, especially in cool temperatures and dry soils. Priming of seeds advances germination by inducing biochemical changes in the seed. Seed priming (immersing seeds in water for 8 h) prior to planting increased yields by 29–38% in different agroecological conditions (Ali et al., 2003). Ali et al. (2005) reported that seed priming increased seed yield from 30 to 37% in Bangladesh. Priming improved plant stands, enhanced early vigour and resulted in early maturity, reduced disease and increased yield. Seed priming is quite beneficial in population management especially under rice-relay cropping systems. Experiments conducted during 2005–2006 in India revealed that sowing sprouted seeds was beneficial.

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Water management Crop water requirements depend on soil type, slope of the field, date of sowing, crop duration, temperature and other factors. Field estimates of the consumptive use of water have been made for different parts of Egypt and North India. El-Gibadi and Badawi (1978), using the Blaney and Criddle formula, indicated that the consumptive use of water in lower, middle and upper Egypt was 365, 364 and 391 mm, respectively. Most lentil crops in India are grown on conserved soil moisture as a monocrop or on residual moisture (after rice harvest) under rainfed conditions. Moisture stress is usually the single most important bottleneck to achieve the potential grain yields in the Indian subcontinent. Aspects of drought physiology and the optimization of water use efficiency are to be found in Shrestha et al. (Chapter 12, this volume). Different workers reported water requirements in the range of 155–483 mm in India (Tickoo et al., 2005). Saraf and Baitha (1979) computed the water requirements of lentil by following the actual soil moisture depletion on a sandy loam soil of North India. Water requirements of timely sown lentil ranged from 155 mm with one irrigation to 214 mm with four irrigations. About 67% of the total soil moisture depletion occurred from the first 30 cm soil layer and 25% from second 30 cm layer. On sandy loam soils with a low water-holding capacity, a positive response to between one and three irrigations has been recorded on lighttextured soils (Ahlawat and Rana, 2005). Flowering is the most critical period for irrigation. The highest grain yield of 1547 kg/ha was obtained when irrigation was scheduled at an irrigation water (depth):cumulative pan evaporation (IW:CPE) ratio of 0.6 coupled with 70 kg P2O5/ha, which was 70% higher than the control at the same level of irrigation (Venkateswarlu and Ahlawat, 1993). In black clay soils of Jabalpur and sandy loam soils of Pusa and Bikramganj, the optimum IW:CPE ratio was observed to be 0.6 requiring two to three irrigations to produce maximum yields. However, the irrigation water requirement as well as the total water use was highest at Jabalpur. At Pantnagar, Ludhiana and Delhi locations in India, two irrigations of 6–7 cm depth at different critical stages were adequate (Prihar and Sandhu, 1987). An experiment conducted in the Mediterranean region at the main station at the International Center for Agricultural Research in the Dry Areas (ICARDA) indicated grain and biomass yield of lentil increased with increased supplemental irrigation at the reproductive stage (Oweis et al., 2004). The response to irrigation depended on available soil moisture and rainfall during the crop growth period. Experiments at Alberta, Canada indicated that lentil yields increased significantly by supplemental irrigation during drought years in comparison to wet years (Agriculture and Agri-Food Canada, 2008). Raised-bed planting economizes water as compared to flat-bed planting. At Kanpur, India, lentil planted on raised beds saved 20–25% irrigation water and increased the grain yield (Pramanik et al., 2007). Lentil is also highly susceptible to over-watering. Temporary waterlogging can cause

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severe damage. Therefore, only light irrigation is advocated and excess water should be removed by drainage.

Weed management Lentils are poor competitors against weeds because the plants are slender and neither branch sufficiently nor grow tall enough to suppress weeds. Weeds cause heavy losses to the lentil crop as they rob the soil of its nutrients and moisture. The magnitude of loss depends upon weed species and their intensity, growing conditions, soil fertility and soil moisture. A full treatment of weed management is to be found in Yenish et al. (Chapter 20, this volume).

Effect of integrated management Integrated management for fertilizers, manures, weeding and inoculum application has tremendous effect on lentil production. Ali et al. (2003) reported that a combination of cow dung at 3 t/ha, chemical fertilizers at 20:40:20 kg/ha of NPK, and one hand-weeding at 30 days after emergence was the optimum management practice for economically viable production. Miah and Rahman (1993) also reported that proper tillage accompanied by the application of chemical fertilizers, weeding and disease control can significantly increase lentil productivity.

Harvesting Lentil should be harvested when plants begin to turn yellow and pods are yellow-brown to brown. The mature crop should be harvested at the earliest date so as to avoid shattering of pods and loss of seeds. It is desirable to harvest the crop during the morning hours to avoid breakage of plants and shattering losses. The crop should be cut at 5–7.5 cm from the ground level to minimize breakage. The crop is harvested by hand pulling, cutting with sickle bars or by direct combining, depending on field conditions and availability of equipment. A detailed account of the mechanization of harvest is given by Diekmann and Al-Saleh (Chapter 16, this volume). The handharvested crop is spread on the threshing floor for further drying and run under tractor/bullocks for threshing. The threshed crop is cleaned manually or by winnowing. Where the crop is to be cut using sickle bars or swathers, it is advisable to do this operation at higher moisture content of 18–20% to avoid yield losses. Where direct combining is practised, the plants should be sufficiently dry for ease of operation and the seeds should be at or below 12% moisture content. In some cases in the USA and Canada, the crop is sprayed with a desiccant to promote uniform maturity and to ease the combining operation.

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After harvest, the seed, at a moisture content of 9–10%, should be stored in airtight containers. For protection against bruchids in storage, the seeds may be treated with certain oils (mustard/castor/neem/mahua (Maduca indica)/coconut/groundnut/sesame) at 9–12 ml/kg or mixed with inert material (charcoal powder or lime) or plant product (annola seed powder or neem leaf powder/asafoetida/neem seed powder) at 9–12 g/kg seed to avoid losses resulting from storage grain pests (Anonymous, 2006).

Drying and storage Lentil seed after harvest should be adjusted to moisture contents of 9–10% to prevent damage from mould-causing and storage pests. Lentil can be dried in heated air dryers, but the maximum temperature should not exceed 43°C to avoid cracking of seedcoats. Natural air drying has advantages over heated air, but it is necessary to have a properly designed system. The design must ensure good airflow through the seed. This requires that thinner layers of the seed must be used in this process. Further information on the postharvest processing of lentil can be found in Vandenberg (Chapter 24, this volume).

References Agarwal, S.C., Khare, M.N. and Kushwaha, L.S. (1976) Effect of sowing dates on the collar rot of lentil caused by Sclerotium rolfsii Sacc. Jawaharlal Nehru Krishi Vishwa Vidyalaya Research Journal 10, 172–173. Agriculture and Agri-Food Canada (2008) Prairie Farm Rehabilitation Administration. Available at: www.Agr.gc.ca/pfra/csideft (accessed 15 April 2008). Ahlawat, I.P.S. and Rana, D.S. (2005) Concept of efficient water use in pulses. In: Singh, G., Sekhon, H.S. and Kolar, J.S. (eds) Pulses. Agrotech Publishing Academy, Udaipur, India, pp. 313–339. Ahlawat, I.P.S. and Sharma, R.P. (1985) Water and nitrogen management in wheatlentil intercropping system under late sown conditions. Journal of Agricultural Science 105, 697–701. Ahlawat, I.P.S., Singh, A. and Saraf, C.S. (1981) Effects of winter legumes on the nitrogen economy and the productivity of the cereals. Experimental Agriculture 17, 57–62. Ahlawat, I.P.S., Singh, A. and Saraf, C.S. (1982) Yield of lentil cultivars as affected by date and rate of seeding under late sown conditions. Indian Journal of Agronomy 27(3), 259–262. Ahmad, A.M. and Motior, R.M. (1993) Agronomy of lentil in Bangladesh. Genetic resources and breeding of lentil in Bangladesh. In: Erskine, W. and Saxena, M.C. (eds) Lentils in South Asia. Proceedings of the Seminar on Lentil in South Asia, 11–15 March 1991, New Delhi, India. International Center for Agricultural Research in the Dry Areas (ICARDA), Aleppo, Syria, pp. 128–138. Ahmed, A., Rahman, A. and Kelley, T.G. (1987) Study on the mixed cropping of wheat and lentil at varying seeding ratios under different levels of fertility. Bangladesh Journal of Agricultural Research 12, 53–59.

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C Plate 1. Lentil crossing technique showing (A) the approximate size and stage of a typical female flower; (B) stage of a typical male flower; (C) folding back of the corolla of a female flower to expose the anthers during emasculation. Continued

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F Plate 1. Lentil crossing technique showing (D) removal of the anthers; (E) an emasculated female flower showing the stigma, style and ovary; and (F) completion of pollination showing the presence of pollen on the stigma of the female flower and the pollen laden stigma of a male flower used as a source of pollen. (Photographs courtesy of Henry Moore Jr Photographer II, Biomedical Communications Unit, Washington State University, Pullman, Washington 99164 USA).

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Plate 2. Fungal diseases of lentil. (A) Lentil rust on pods; (B) aecia and pycnidia of lentil rust on leaves; (C) stem lesions and sporulation of Botrytis grey mould; (D) Stemphylium blight on leaves; (E) sunken lesions of anthracnose on a lentil stem; (F) conidia and mycelium of powdery mildew on a lentil leaf.

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C Plate 3. (A) Yellowing and stunting symptoms caused by Bean leaf roll virus (left) as compared to a healthy plant (right); (B) yellowing and stunting symptoms caused by Faba bean necrotic yellows virus on susceptible lentil genotypes (left and right) as compared to a resistant lentil genotype (middle); (C) yellowing and reddening symptoms with stunting on different lentil genotypes inoculated with Soybean dwarf virus. Continued

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F Plate 3. (D) mosaic symptoms on lentil leaves caused by Broad bean stain virus (left) as compared to a healthy plant (right); (E) severe mottling caused by Pea enation mosaic virus-1; and (F) seedcoat symptoms of lentil seeds from plants infected with Broad bean stain virus (left) as compared to healthy-looking seeds (right).

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B Plate 4. (A) Detection of Bean leaf roll virus by tissue-blot immunoassay (TBIA) in infected lentil stem blot (right) as compared to a healthy plant (left); and (B) detection of Broad bean stain virus by TBIA in an infected lentil seedling in a group of 25 seedlings blotted on the nitrocellulose membrane as one sample.

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Plate 5. (A) Patch of dodder-infested lentil plants; (B) detail of lentil plants infected by dodder; (C) closer detail of dodder-infected plant showing massed clusters of mature dodder flowers, fruits and seeds; (D) lentil field severely affected by Orobanche crenata; (E) closer detail of O. crenata plants infecting lentils. Continued

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Plate 5. (F) Orobanche aegyptiaca plant infecting lentil; (G) detail of germinated broomrape seed contacting lentil root; (H) early tubercle formation; (I) developed broomrape tubercle with crown of roots with anchoring function; (J) lentil plants removed from pots showing broomrapes at different stages of development.

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Ali, M. (1994) Agronomy. In: Ali, M., Asthana, A.N. and Mehta, S.L. (eds) 25 years of Research on Pulses in India. Proceedings of International Symposium on Pulses Research, Indian Society of Pulses Research and Development, 2–6 April 1994, Indian Agricultural Research Institute, New Delhi, India. Indian Institute of Pulses Research, New Delhi, India, pp. 19–21. Ali, M., Saraf, C.S., Singh, P.P., Riwari, R.B. and Ahlawat, I.P.S. (1993) Agronomy of lentil in India. In: Erskine, W. and Saxena, M.C. (eds) Lentils in South Asia. Proceedings of the Seminar on Lentil in South Asia, 11–15 March 1991, New Delhi, India. International Center for Agricultural Research in the Dry Areas (ICARDA), Aleppo, Syria, pp. 103–127. Ali, M.O., Sarkar, A., Rahman, M.M., Gahoonia, T.S. and Uddin, M.K. (2005) Improvement of lentil yield through seed priming in Bangladesh. Journal of Lentil Research 2, 54–59. Ali, O., Sarkar, A., Rahman, M.M. and Gahoonia, T.S. (2003) Lentil cultivation under relay cropping in Bangladesh. Krishi Katha 3, 12–16. Andrews, M., McKenzie, B.A., Joyee, A. and Andrews, M.E. (2001) The potential of lentil, Lens culinaris, as a grain legume crop in the UK: an assessment based on a crop growth model. Annals of Applied Biology 139, 293–300. Anonymous (2006) Annual Report, All India Coordinated Research Project on MULLaRP (2005–2006). Indian Institute of Pulses Research, Kanpur, India, 85 pp. Bukhtiar, B.A., Naseem, B.A. and Tufail, M. (1991) Effect of seed rate on grain yield and its components of small and large seeded lentils. Journal of Agriculture, Lahore 29, 339–345. Cftc, V. and Ülker, M. (2005) Economic benefits of mixed cropping of lentil (Lens culinaris) with wheat (Triticum aestivum) and barley (Hordeum vulgare) at different seeding ratios. Indian Journal of Agricultural Sciences 75, 100–102. Chakraborty, L.N., Sen, S.N., Mandal, S.K., Gupta, S.K. and Mukherjee, D. (1976) Possibility of utilizing rice fallows in west Bengal. Field Crop Abstracts 29(Abstract 2382), p. 212. Chaudhary, R.G. and De, R. (2005) Effect of zinc sulphate and management of lentil rust. Indian Journal of Agricultural Sciences 75, 148–149. Chen, C., Miller, P., Muehlbauer, F., Neill, K., Wichman, D. and McPhee, K. (2006) Winter pea and lentil response to seeding date and micro- and macroenvironments. Agronomy Journal 98, 1655–1663. Cubero, J.I. (1981) Origin, taxonomy and domestication. In: Webb, C. and Hawtin, G. (eds) Lentils. Commonwealth Agricultural Bureau, Slough, UK, pp. 15–38. Dhingra, K.K., Gill, A.S., Tripathi, H.P. and Sekhon, H.S. (1983) Response of lentil genotypes to date of planting under different agro climatic conditions of Punjab. Journal of Research, Punjab Agricultural University 2, 1–5. Dwivedi, G.K. (1996) Tolerance of some crops to soil acidity and response to liming. Journal of the Indian Society of Soil Science 44, 736–741. El-Gibadi, A.A. and Badawi, A.Y. (1978) Estimate of irrigation needs of lentil in Egypt. Egyptian Journal of Soil Science 18, 159–179. Eriksmoen, E., Riveland, N., Halvorson, M. and Henson, R. (2008) Effects of seeding rate on lentil production in North Dakota. Available at: www.ag.ndsu.nodak.edu/ carringt/agronomy/research (accessed on 4 April 2008). Erskine, W., Rihawi, S. and Capper, B.S. (1990) Variation in lentil straw quality. Animal Feed Science and Technology 28, 61–69. Eser, D. and Adak, M.S. (1999) Effect of fallow, winter lentil, nitrogen fertilization and different soil tillage on wheat yield in the dry farming areas of Central Anatolia. Turkish Journal of Agricultural Forestry 23, 567–576.

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Singh, I.P., Naimuddin, G., Sanjeev and Brahm, P. (eds) National Symposium on Legumes for Ecological Sustainability: Emerging Challenges and Opportunities. Indian Institute of Pulses Research, Kanpur, India, p. 65. Neupane, R.K. and Bharati, M.P. (1993) Agronomy of lentil in Nepal. In: Erskine, W. and Saxena, M.C. (eds) Lentils in South Asia – Proceedings of the Seminar on Lentil in South Asia. International Center for Agricultural Research in the Dry Areas (ICARDA), Aleppo, Syria, pp. 139–146. Oweis, T., Ahmed, H. and Pala, M. (2004) Lentil production under supplemental irrigation in a Mediterranean environment. Agricultural Water Management 68, 251–265. Prakash, V., Tandaon, J.P. and Prasad, K. (1986) Studies on intercropping in rainfed wheat. Annals of Agricultural Research 7, 258–262. Pramanik, S.C., Singh, N.B. and Singh, K.K. (2007) Improving land and water productivity in rabi pulses through raised bed planting technique. In: Sahu, R.K. (ed.) South Asian Conference on Water in Agriculture: Management Option for Increasing Crop Productivity per Drop of Water. Indira Gandhi Krishi Viswa Vidyalaya, Raipur, Chatishgarh, India, pp. 16–17. Prihar, S.S. and Sandhu, B.S. (1987) Irrigation of Field Crops: Principle and Practices. Indian Council of Agricultural Research, New Delhi, India, 140 pp. Rahman, M.M. and Miah, A.A. (1989) Study on seedling mortality and plant competition of lentil at a wide range of population densities. In: Research Report on Pulse Agronomy. Pulses Research Center, Bangladesh Agricultural Research Institute, Joydebpur, Gazipur, Bangladesh, pp. 27–33. Rehman, M.A. and Shamsuddin, M. (1981) Intercropping of lentil and wheat. Bangladesh Journal of Agricultural Research 6, 27–31. Roysharma, R.P., Thakur, H.C., Sharma, H.M., Mishra, S.S. and Thakur, S.S. (1984) Effect of fertilization and inoculation of paira and late sown pure lentil. Indian Journal of Agronomy 29, 459–462. Sakar, D., Durutan, N. and Meyveci, K. (1988) Factors, which limit the productivity of cool season food legumes in Turkey. In: Summerfield, R.J. (ed.) World Crops: Cool Season Food Legumes. Kluwer, Dordrecht, The Netherlands, pp. 137–146. Saraf, C.C. and Baitha, S.P. (1979) Effect of varying soil moisture regimes and phosphorus levels on growth, yield and consumptive use of water by lentils planted on different dates under Delhi conditions. Lentil Experimental News Service (LENS) 6, 1–5. Sarkar, B. and Pal, A.K. (2005) Water use and yield of rapeseed (Brassica campestris var. yellow sarson) and lentil (Lens culinaris Medik.) grown as sole crop and as intercrop. Journal of Interacademicia 9, 10–15. Sarkar, R.K., Malik, G.C. and Pal, P.K. (2004) Effect of lentil and linseed under varying plant density and row arrangement on productivity and advantages in system under rainfed upland. Indian Journal of Agronomy 49, 241–243. Saxena, M.C. (1981) Agronomy of lentils. In: Webb, C. and Hawtin, G.C. (eds) Lentils. Commonwealth Agricultural Bureau, Slough, UK, pp. 111–129. Saxena, M.C. and Yadav, D.S. (1976) Agronomic studies on lentil under subtropical conditions of Pantnagar, India. Lentil Experimental News Service (LENS) 3, 17–26. Sekhon, H.S., Dhingra, K.K., Sandhu, P.S. and Bhandari, S.C. (1986) Effect of time of sowing, phosphorus and herbicides on the response to Rhizobium inoculation. Lentil Experimental News Service (LENS) 13, 15–17. Sekhon, H.S., Singh, G. and Ram, H. (2007) Lentil based cropping systems. In: Yadav, S.S., McNeil, D.L. and Stevenson, P.C. (eds) Lentil: an Ancient Crop for Modern Times. Springer Verlag, Dordrecht, The Netherlands, pp. 107–126.

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M. Ali et al. Shah, Z., Shah, S.H., Peoples, M.B., Schwenke, G.D. and Herridge, D.F. (2003) Crop residue and fertilizer N effects on nitrogen fixation and yields of legume-cereal rotations and soil organic matter. Field Crop Research 83, 1–11. Siddique, K.H.M., Loss, S.P., Pritchard, D.L., Regan, K.L.D., Jettner, R.L. and Wilkinson, D. (1998) Adaptation of lentil (Lens culinaris Medik.) to Mediterranean-type environments: effect of time of sowing on growth, yield, and water use. Australian Journal of Agricultural Research 49, 613–626. Silim, S.N., Saxena, M.C. and Erskine, W. (1990) Seeding density and row spacing for lentil in rainfed Mediterranean environments. Agronomy Journal 82, 927–930. Singh, A.K. and Singh, N.P. (2002) Performance of bold-seeded lentil (Lens culinaris) varieties under varying seed rates in normal and late sown conditions. Indian Journal of Agronomy 47, 227–230. Singh, D.K. and Sofi, K.A. (2007) Production potential of rice (Oryza sativa L.) based cropping system at different nutrient management under temperate ecosystem of Kashmir. Journal of Farming Systems Research and Development 13, 204–208. Singh, G. and Dhingra, K.K. (1980) Effect of sowing dates and varietal reaction on the incidence of lentil rust. Journal of Research Punjab Agricultural University 17, 233–235. Singh, I., Sardana, V. and Sekhon, H.S. (2005) Influence of row spacing and seed rate on seed yield of lentil (Lens culinaris) under different sowing dates. Indian Journal of Agronomy 50, 308–310. Singh, N.B. (2006) Enhancing the Productivity of Lentil through Population Management, Annual Report 2005–06. Indian Institute of Pulses Research, Kanpur, India, 21 pp. Singh, N.P. and Ram, A. (1986) Effect of sowing dates and row spacing on the performance of lentil cultivars. Lentil Experimental News Service (LENS) 13, 15–17. Singh, T. and Rana, K.S. (2006) Effect of moisture conservation and fertility on Indian mustard (Brassica juncea) and lentil (Lens culinaris) intercropping system under rainfed conditions. Indian Journal of Agronomy 51, 267–270. Srivastava, S.C. (1975) Performance of legumes as intercrops in sugarcane. Indian Journal of Genetics 35, 269–270. Tickoo, J.L., Sharma, B., Mishra, S.K. and Dikshit, H.K. (2005) Lentil (Lens culinaris) in India: present status and future perspectives. Indian Journal of Agricultural Sciences 75, 539–562. Tomar, S.P.S. and Singh, R.P. (1991) Effect of tillage, seed rates and irrigation on the growth, yield, and quality of lentil. Indian Journal of Agronomy 36(2), 143–147. Venkateswarlu, U. and Ahlawat, I.P.S. (1993) Effect of soil moisture regime, seed rate and phosphorus fertilizers on growth, yield attributes and yield of late sown lentil (Lens culinaris). Indian Journal of Agronomy 38, 236–243. Wisal, M. (2003) Strategies for improving wheat productivity and soil organic matter in irrigated and rainfed environments. PhD thesis, North West Frontier Province (NWFP) Agricultural University, Peshawar, Pakistan. Available at: http://eprints. hec.gov.pk/536 (accessed on 15 April 2008). Yadav, R.A. and Tripathi, A.K. (2007) Studies on linseed based pulses intercropping in Bundelkhand tract of Uttar Pradesh. In: Pramanik, S.C., Singh, B.B., Singh, I.P., Naimuddin, G., Sanjeev and Brahm, P. (eds) National Symposium on Legumes for Ecological Sustainability: Emerging Challenges and Opportunities. Indian Institute of Pulses Research, Kanpur, pp. 20–21. Zaman, A.F.M. and Miah, A.A. (1989) Effect of different levels of management on the grain yield of lentil. In: Advances in Pulses Research in Bangladesh – Proceedings of the Second National Workshop on Pulses. Bangladesh Agricultural Research Institute, Joydebpur, Bangladesh, pp. 67–73.

15

Biological Nitrogen Fixation and Soil Health Improvement Mark A. Quinn Washington State University, Pullman, Washington, USA

15.1. The Importance of Biological Nitrogen Fixation and Legumes Legumes have always been a critical component of agroecosystems throughout the world because of their ability to convert atmospheric N into usable plant protein, their ability to grow in N-poor soils, and their contribution to the pool of soil N that can be used by succeeding crops. The approximately 250 million ha of legumes grown in the world fix about 90 trillion g of N each year (Graham and Vance, 2000). It has been estimated that nitrogenfixing legumes save approximately US$7–10 billion on N fertilizer each year (Herridge and Rose, 2000; Hardarson et al., 2003). The fixed N is used directly for plant growth and maintenance, and provides an excellent source of protein for humans and livestock. Six main genera of bacteria are involved in the symbiotic relationship with legumes: Rhizobium, Bradyrhizobium, Sinorhizobium, Azorhizobium, Mesorhizobium and Allorhizobium, and are collectively known as rhizobia. There is often taxonomic specificity between species of legumes and rhizobia. For example, Rhizobium leguminosarum bv. viciae is the symbiont of all Lens species, but also forms associations with other members of the Vicieae (i.e. Vicia, Pisum, Lathyrus). The strength of the symbiotic relationship that determines the degree of nodulation and nitrogen fixation is affected by numerous factors, including legume and bacteria genotype, abiotic conditions, and interactions with other organisms. Many of these factors are under the control of growers of cultivated legumes. Legume cultivation is particularly important in N-poor soils where they can reduce the need for costly inorganic fertilizers. Nitrogen deficiencies are common in tropical and subtropical soils that have mineral fractions with a low capacity to retain nutrients and water (Boddey et al., 1997). Not only does nitrogen fixation allow the growth of legumes in these N-poor soils, but also it can indirectly increase soil N levels and, thus, support the growth © CAB International 2009. The Lentil: Botany, Production and Uses (eds W. Erskine et al.)

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of other crops grown with the legumes or the succeeding crops after legumes. Nitrogen-fixing legumes are an important component of healthy soil to provide sustainable crop production systems.

15.2. Nodulation and Nitrogen Fixation in Lentil At regional and global scales, the contribution of nitrogen fixation to crops is substantial. Lupwayi and Kennedy (2007) estimated that in 1974, about 171 million kg N2 was fixed by field pea, lentil, dry bean and chickpea crops in the Canadian prairies, and about 40 million kg N2 was fixed by grain legumes in the USA. This represented about 7% of total fertilizer N used by farmers. At a global level, crop legumes may fix about 90 trillion g N/year (Graham and Vance, 2000), with lentils accounting for about 0.35 trillion g N/year (McNeil and Materne, 2007). At a local scale, nitrogen fixation by lentils is also substantial (Table 15.1). Unkovich and Pate (2000) reviewed various methods and problems with estimating the amount of biological nitrogen fixation by crops, and found a high degree of variation in recorded estimates within individual crops, between years and between locations. Estimates of the percentage of plant N derived from fixation in lentils ranged from 28 to 87% with an average of 63%. Walley et al. (2007) summarized results from 38 field experiments with lentils conducted in Canada and reported a range of 9–88% N derived from fixation, with a median value of 60%. Other grain legumes have similar ranges (Peoples and Craswell, 1992; Unkovich and Pate, 2000; Walley et al., 2007). For lentils and other grain legumes, the theoretical proportion of N derived from fixation ranges from 0 if soil N is high and/or if soils contain no effective rhizobia, to 100% if soil N if very low and soils contain compatible strains of rhizobia. The empirical values reported in Table 15.1 for individual field experiments reflect this range. Researchers have examined and linked a variety of factors responsible for the broad range of estimates, including lack of effective strains of native rhizobia, lentil genotype, use of inoculants, soil type, existing soil N levels, crop phenology and type of cropping system (Table 15.1). The exact role of these factors on the contribution of nodulation and nitrogen fixation to soil health will be discussed below. Published estimates of the total amount of N fixed by lentil range from 0 to 192 kg N/ha (Table 15.1), with an average value of about 80 kg N/ha in shoots and roots. This estimate is similar to quantities fixed by chickpea and dry bean (Unkovich and Pate, 2000). In contrast, up to 327–450 kg N/ ha is fixed by lupin, fababean and soybean. The lentil root system takes up about 20–25% of fixed N in the plant, or about 22 kg N/ha in the roots and nodules (Unkovich and Pate, 2000). In comparison, chickpea, lupin and lucerne invest more than 40% of fixed N in their root systems. The amount of N sequestered in nodulated roots is important because this is a source of N available for subsequent crops, along with any surface residue incorporated into the soil. Unless used as a green manure (see Table 15.1), most of the fixed N is removed as grain, leaving only a small percentage in the soil.

Estimates of nitrogen ﬁxation in lentil.

Location

N ﬁxed (%)

Total N ﬁxed (kg/ha)

N added to soil (kg/ha)

Pakistan

9–48

9–48

–

Pakistan Jordan

56–85 80–83

46–85 –

16–33 –

Syria Syria Syria

58–68 0–93 55–69

111–154 18–82 10–55

– – –

Syria, France Egypt

63–75 52–55

88–147 127–139

– –

Canada

72–87

129–192

–

Canada

0–72

0–81

–

Canada

0–76

0–105

–

Canada

55–77

10–14

–

Canada Canada USA Australia

62–72 86 – 61

– 149 67–110 169

– 59a 0–70 169a

Australia

60–90

60–110

–

aAfter

Variability factors

References

Rhizobia strain; plant genotype; uninoculated control Year; incorporation of residue Rhizobia strain; plant genotype; uninoculated control Plant genotype; plant phenology Year; added N Year; location; intensity of management Year; location, soil insecticide Rhizobia strain; uninoculated control Year; plant genotype; uninoculated control Year; plant genotype; location; uninoculated control Rhizobia strain; plant genotype; location; uninoculated control Intercropped with ﬂax versus monocrop; added N Conventional tillage versus no-till End of growing season estimate Year; location One crop tested; used as a green manure Year

Hafeez et al. (2000) Shah et al. (2003) Badarneh and Gwawi (1994) Kurdali et al. (1997) McNeill et al. (1996) Keatinge et al. (1988) Beck et al. (1991) Moawad et al. (1998) Rennie and Dubetz (1986) Bremer et al. (1988)

Biological Nitrogen Fixation and Soil Health Improvement

Table 15.1.

Bremer et al. (1990) Cowell et al. (1989) Matus et al. (1997) van Kessel (1994) Smith et al. (1987) Rochester et al. (1998) Peoples et al. (2001)

grain removal.

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Ghosh et al. (2007) concluded that the carryover of N from grain legumes for succeeding crops (e.g. sorghum, pearl millet, maize, castor) in dry lands, and marginal and sub-marginal lands ranged from 35 to 120 kg N/ha. The carryover for lentils is probably at the lower end of the range, estimated as 45 kg N/ha by McNeil and Materne (2007) and 23 kg N/ha by van Kessel and Hartley (2000). In comparison to other grain legumes (i.e. common bean, chickpea), lentils are likely to have positive N balances (Walley et al., 2007). As discussed below, the carryover N is just one aspect of soil health provided by lentils.

15.3. Factors that Affect the Contribution of Lentils to Soil Health The exact contribution of lentils to soil health depends on numerous abiotic, biotic and production factors that affect nitrogen fixation and the decomposition of lentil roots and surface debris (Table 15.2). Abiotic factors, such as soil temperature, soil pH, soil salinity and soil nutrients affect rhizobia, the plant, and/or the rhizobia-plant symbiosis. Biotic factors that affect the contribution of lentils to soil health includes both intrinsic and extrinsic factors. Intrinsic biotic factors include lentil genotype, strain of rhizobia and the plant genotype–rhizobia strain interaction. Extrinsic biotic factors are organisms that affect the plant or rhizobia, such as plant pathogens, weeds, rhizobial competitors and beneficial soil microbes (e.g. mychorrizas, growthpromoting bacteria). Agronomic factors that affect N inputs into soil include fertilizer regimes, tillage and planting methods, irrigation, mixed and intercropping, crop rotations, and use of green manures.

Abiotic soil factors Saline soils constitute approximately 19.5% of irrigated land and 2.1% of dryland agriculture in the world (FAO, 2000), and are a significant challenge to growing lentils and other grain legumes. Rai and Singh (1999) studied the effects of salt stress on lentils and rhizobia and found that saline soils inhibited nodulation and activities of nitrogenases, glutamine synthetase and NADH-dependent glutamate synthase in R. leguminosarum. They were able to identify two rhizobia strains and four lentil genotypes that were more tolerant of saline soils, exhibiting greater nodulation, nitrogen fixation, total plant N and plant biomass compared to indigenous strains. Moawad and Beck (1991) evaluated 229 isolates of R. leguminosarum from lentil-growing regions of West Asia-North Africa and found considerable variation in salt and heat tolerance. Considerable progress has been made in the selection of legumes and effective rhizobia for acidic soils (Giller and Cadisch, 1995), which comprise about 1.6 billion ha in the world (Graham and Vance, 2000). Slattery et al. (2004) conducted a survey of the effectiveness of rhizobia communities at 50 sites in southern Australia and found that nitrogen-fixing effectiveness

Factors that affect the contribution of the rhizobia-lentil symbiosis to soil health.

Factor

Variables

Affect on the rhizobia-lentil symbiosis

Abiotic factors

Temperature pH Salinity Soil N Soil phosphorus

Susceptible to extremes; adapted to cool soil temperatures Susceptible to extremes; prefer slightly alkaline to neutral soils Susceptible to high salinity Too much N inhibits nodulation and nitrogen ﬁxation; adapted to low N conditions Limiting factor for nitrogen ﬁxation; uptake can be enhanced by mycorrhizas and P-solubilizing bacteria Zn, Bo and Mo deﬁciencies affect nodulation and nitrogen ﬁxation Interact with rhizobia strains to affect nodulation and nitrogen ﬁxation High degree of variability in competitiveness, response to abiotic conditions, nodule initiation and nitrogen ﬁxation Numerous strains compete for nodule initiation sites; inoculant strains must be competitive with indigenous strains Pathogens and herbivorous insects can reduce nodulation and nitrogen ﬁxation by directly feeding on the root system; foliar pests indirectly affect nodulation and nitrogen ﬁxation by reducing photosynthate production; weeds compete for P and micronutrients and indirectly affect nitrogen ﬁxation via their effect on foliage growth Very little known about the effects of bacteria-feeding protozoa and microinvertebrates on rhizobia populations; involved in nutrient cycling Can increase P uptake and nitrogen ﬁxation

Intrinsic biotic factors Extrinsic biotic factors

Micronutrients Lentil genotype Rhizobia strain Intra-strain competition Plant pests

Soil microinvertebrates

Crop production factors

Mychorrhizas; Psolubilizing bacteria Inoculants Fertilizers Tillage Intercropping Crop rotation

233

Green manure

Essential in rhizobia-deﬁcient soils; must be competitive with indigenous strains and adapted to abiotic conditions; must be compatible with lentil genotypes N fertilizers reduce nitrogen ﬁxation Reduces soil organic matter; variable affects on nodulation and nitrogen ﬁxation Little or no direct transfer of N to non-legumes; increased nitrogen ﬁxation when non-legume uses soil N; increases soil pool of N Viable alternative to fallow periods and continuous cereal production; often have a positive N effect on soils Provides abundant N as a green manure; can increase organic matter in comparison to fallow; prevents soil erosion

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Table 15.2.

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was related to soil pH and location. Only 54% of the sites had sufficient resident populations of R. leguminosarum bv. viciae for effective nodulation of lentils. Low populations (<10 rhizobia/g soil) of R. leguminosarum bv. viciae were found in acidic soils. Evans (2005) also found that strains of R. leguminosarum vary considerably in their ability to nodulate lentil, fix N and contribute to plant growth in acidic soils. High alkalinity also reduces nodulation, nodule biomass and leghaemoglobin content of lentil nodules (Misra et al., 2002). Existing soil N and P contents affect nodulation, nitrogen fixation and growth of lentils and other legumes. Phosphorus deficiencies are frequently cited as limiting nitrogen fixation (Giller and Cadisch, 1995) and approximately 33% of arable land is deficient in P, a common problem in tropical and subtropical soils (Graham and Vance, 2000). Arpana et al. (2002) looked at the effect of inoculation, fertilizers and irrigation on uptake of nutrients by lentils grown in Bihar, India over a 2-year period. They found that inoculated lentils increased the availability of N, P and K, when fertilized and irrigated, compared with uninoculated controls. Researchers have reported 0–59% increases in lentil yield in response to added P (McKenzie et al., 2007). Inoculation of lentils and added P has been shown to increase root biomass, number of nodules, plant growth and nutrients (Shah et al., 2002; Balyan and Singh, 2005). Soil micronutrients also affect the contribution of nodulation and nitrogen fixation to soil health (Wani et al., 1995). Prasad et al. (2004) found that rhizobia strain and S affected grain yield of lentil, nodules per plant, S content in nodules, total N uptake, and nitrogenase activity. Additions of micronutrients (Mo, Co, B) was shown to increase lentil nodule biomass, plant biomass, N content, seed yield, seed size, and N and P content of seed for lentil, chickpea and lupin (Yanni, 1992). The concentration of soil N affects nodulation and nitrogen fixation of all legumes. High levels of soil N reduce nodulation and fixation, thus minimizing the benefit of the symbiotic relationship. This occurs because nitrogen fixation requires considerable energy and nutrients, whereas the uptake of soil N is metabolically less expensive for the plant. Also, removing N from soils lessens competition from other species. Considerable research has been conducted to select genotypes and strains of rhizobia that maximize nitrogen fixation in N-rich soils (Giller and Cadisch, 1995; Wani et al., 1995; Herridge and Rose, 2000). However, it is unclear if this would actually improve soil health and benefit cropping systems because, in the end, it may increase the loss of N from soils through leaching and volatilization (Giller and Cadisch, 1995). It doesn’t seem to be a particularly sustainable approach and is likely to degrade soil health. The maximum contribution of lentils and other legumes to soil health occurs in N-poor soils. When soil N levels are low, the growth of some legume species may benefit from a small amount of added N until nodulation and nitrogen fixation begin (van Kessel and Hartley, 2000). The greatest benefit of nitrogen fixation is realized in N-poor soils that have adequate amount of P and micronutrients, and suitable strains of effective rhizobia.

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235

Biotic soil factors The contribution of the rhizobia-lentil symbiosis to soil health is affected by intrinsic biotic factors, such as plant genotype, strain of R. leguminosarum bv. viciae, and interactions between the two. Studies have shown significant variation among lentil genotypes in nodule number, nodule biomass and nitrogen fixation (Bhattacharyya and Sengupta, 1984; Hafeez et al., 2000), root-hair density and micronutrient uptake (Gahoonia et al., 2006), and root growth and weight (Sarker et al., 2005). Small-seeded genotypes of lentils have greater nodule biomass than those of large seeds, and vary in total fixed N and soil N uptake (Kurdali et al., 1997). Several studies have shown considerable variation between strains of R. leguminosarum bv. viciae in nodule number and biomass, nitrogen fixation, proportion of N derived from fixation, total plant N content, grain yields and root growth (Bremer et al., 1990; Hafeez et al., 2000; MartinezRomero, 2003). May and Bohlool (1983) screened 31 strains of R. leguminosarum for their ability to fix N in lentils. The rhizobia used in their experiment came from a variety of locations and diverse sources, and included strains isolated from lentil nodules. The isolates varied widely from ineffective (35% of isolates) to highly effective. Ventorino et al. (2007) assessed genetic diversity of 98 strains of R. leguminosarum bv. viciae nodulating Vicia faba plants, and found that 53% of the isolates showed a high occurrence and persistence in the soil. Indigenous populations of rhizobia are often not adequate to support nitrogen fixation in lentils. Soils that have not been ‘conditioned’ to grow lentils typically are devoid of effective rhizobial strains and must be inoculated. For example, in the Great Plains Region of the USA, most lentil production occurs on soils that were originally free of indigenous R. leguminosarum (Bremer et al., 1990) and needed to be inoculated to increase yield through nitrogen fixation. Slattery et al. (2004) conducted a survey of the effectiveness of rhizobia communities at 50 sites in southern Australia. They found that only 54% of the sites had sufficient resident populations of R. leguminosarum bv. viciae for effective nodulation of lentils. Hafeez et al. (2000) found that a specific strain of R. leguminosarum bv. viciae (i.e. Lc26) fixed 243% more N than indigenous populations of rhizobia in N- and rhizobia-poor soils in Pakistan. Although indigenous strains may not be suitable for forming symbiotic relationships with specific legume species, they often exhibit higher tolerance to adverse conditions found in their soils, including tolerance to salt, higher temperatures and desiccation, and may be excellent sources of genetic variation for improving the effectiveness of rhizobia strains growing in marginal soils (Zahran, 2001). Extrinsic biotic factors affecting nodulation and nitrogen fixation of lentils include the numerous other species that affect rhizobia in the soil, the plant-rhizobia symbiosis, and the plant. Intra-strain competition among rhizobia for nodule initiation sites is an important extrinsic biotic factor because strains that are effective at fixing N must also be competitive. May and Bohlool (1983) inoculated lentil with different strains of rhizobia and

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found that competitiveness depended on rhizobia strain, lentil genotype and soil type. Moawad et al. (1998) found that in field-grown lentils, inoculant strains were not able to compete with indigenous rhizobia; the established rhizobia occupied 76–88% of the total nodules formed on inoculated plants. In contrast, Shah et al. (2002) reported that inoculated strains of R. leguminosarum bv. viciae were highly competitive with indigenous rhizobia, being recovered from 71–95% of lentil root nodules. The difference between these studies reflects the previous crop history of the soil. Because nodulation, nitrogen fixation and photosynthesis are linked, factors that reduce photosynthate production and nodulation (e.g. insects pests, plant pathogens, weeds) can adversely affect symbiosis and nitrogen fixation in lentil. For example, Weigand et al. (1992) conducted a 3-year field study on the effects of a nodule-feeding insect (Sitona crinitus), planting date and fertilizer and insecticide applications on plant damage and yield of lentil in different locations in northern Syria. They found that the insect caused significant nodule damage (up to 75%) and yield reductions. The overall effect of the insect was related to precipitation and planting date. Non-rhizobial microorganisms have been shown to enhance the symbiotic relationship that contributes to soil health. Chanway et al. (1989) examined the effect of plant growth-promoting rhizobacteria on grain legumes and found that lentil inoculated with the bacteria had greater emergence, growth, nodulation and root weight. In contrast, pea (Pisum sativum) was not affected by the rhizobacteria. Zarei et al. (2006) conducted a greenhouse study to evaluate the effect of arbuscular mycorrhizas (AM) and indigenous rhizobacteria strains on lentils in a calcareous soil with high pH and low amounts of available P and N. They found that mycorrhizas, rhizobial strain and addition of P had significant effects on nitrogen fixation in lentil, and the effect of rhizobia and the AM was synergistic. Lentils inoculated with phosphate-solubilizing bacteria can increase above- and below-ground biomass, nodulation, and P-use efficiency (Singh et al., 2005). Crop production factors The contribution of nodulation and nitrogen fixation to soil health and sustainability depends on how the legumes and rhizobia are used by land managers. Agricultural factors, such as the selection of plant genotype and fertilizer regime have been discussed above. Additional factors that affect the contribution of lentils to soil health are applications of inoculants, tillage methods, their use in intercropping systems and crop rotation sequences, and their use as green manures. These cropping system factors affect N inputs into soils, as well as soil moisture and organic matter content. Inoculants Nodulation and nitrogen fixation are totally dependent on the presence of effective strains of rhizobia in the soil, and there have been numerous cases of crop failure because of the absence of the compatible and effective strains.

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The adoption of rhizobia inoculants has allowed the successful introduction of many legumes into new farming regions, and has enhanced crop productivity in regions where legumes have been grown previously. However, widespread adoption of inoculants has not occurred in all regions and crops (Graham and Vance, 2000). For example, Hall and Clark (1995) found that only 30% of farmers in an established soybean-growing region in Thailand were willing to adopt new inoculant technologies, perhaps because most relied on N fertilizer to grow soybean. Deaker et al. (2004) reviewed the current status of seed inoculation technology and concluded that there is a clear benefit from using commercial inoculants, with several studies reporting yield increases of up to 25%. Singleton et al. (1992) conducted a review of 228 field experiments in more than 20 countries and 19 species of legumes. They found that growth responses to inoculation were highly variable, but the majority of field studies showed significant yield increases. Under standard field conditions, an average of 46% of studies showed significant positive responses to inoculation, ranging from 10% with common bean to 70% with mung bean. Forty-eight percent of 27 field experiments with lentils showed a positive response. Evans (2005) attributed the failure of the standard inoculant strain, WSM1274, in Western Australia, to survival problems in acidic soils. Chemining’wa and Vessey (2006) estimated the abundance and effectiveness of resident populations of R. leguminosarum bv. viciae at 20 sites in Canada and compared nodulation of uninoculated and inoculated pea. Nodulation was negligible in pea at two sites with no history of growing grain legumes, and abundant at sites with a previous history of inoculation. Commercial inoculation resulted in a 19% increase in above-ground dry weight of pea plants and a 22% increase in number of nodules (but no effect on nodule biomass). Bremer et al. (1990) compared 14 strains of R. leguminosarum bv. viciae with two genotypes of lentils at three sites in Canada and found that inoculation increased grain yields by up to 27–166% over uninoculated controls. The results depended on location, rhizobia strain and lentil genotype. These factors also affected the amount of fixed N. Shah et al. (2002) reported that inoculation of lentil with R. leguminosarum bv. viciae strain Lc26 increased yields by 393 kg/ha compared with uninoculated controls. Chandra and Navneet (2003) tested the effect of inoculation of different lentil genotypes on nodulation and yield over a 3-year period. They found that inoculation of lentils increased nodule biomass from 29 to 64%, and mean grain yield by 15 to 20%, compared with controls. In a review of the benefits of inoculants, van Kessel and Hartley (2000) concluded the following: 1. The response to inoculants is greatest when the legume is planted in new areas where soils lack appropriate rhizobia. 2. The response to inoculants depends on the number of rhizobia already in the ﬁeld. 3. Nitrogen ﬁxation via inoculated rhizobia is dependent on the availability of soil N and the N demands of the crop.

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4. The response to inoculation is site speciﬁc and depends on numerous other abiotic factors, such as soil pH, salinity, temperature and moisture. 5. There is signiﬁcant variation in the effectiveness of different rhizobia strains and the nodulation and nitrogen ﬁxation of different plant genotypes. Bullard et al. (2005) reviewed problems associated with the use of inoculants in Australian agricultural systems from 1953 to 2003. These problems included loss of effectiveness and poor competitive ability of inoculant strains, poor viability of rhizobia because of contaminants in peat carriers, exposure to high temperatures or low temperatures in storage, ethylene oxide residues left after sterilization, and high pH of material used to coat seeds. As few as 100 rhizobia/seed may be sufficient in rhizobia-free, moist soils. In contrast, greater than 106 rhizobia/seed may be required if soils are not suitable for rhizobia growth and survival. Problems with quality control of inoculants have hampered their acceptance and use by farmers. Gomez et al. (1997) evaluated 18 commercial soybean inoculants in Argentina, and found three contained no detectable rhizobia, five with fewer than 107 rhizobia/g of carrier, and 14 with more contaminants than rhizobia. Currently, there are no international standards for quality and application rates for inoculants (Stephens and Rask, 2000). Many countries (e.g. Australia, The Netherlands, Rwanda, Thailand, Russia, Canada, France) regulate minimum populations of rhizobia, contaminants per unit weight of product, viable number of rhizobia per seed, and/or rate of application. The USA and the UK leave product quality and rates to the discretion of the manufacturer. As an example of quality standards, Australia has established the following: (i) >109 rhizobia colony forming units (cfu)/g of moist peat; (ii) contaminants not detectable at a dilution level of 10–6; and (iii) minimum moisture contents of peat packets (Bullard et al., 2005). Standards were established for peat and for pre-inoculated seeds. There have been many improvements in inoculant quality, standards for number of rhizobia per seed, and in storage and application methods. In spite of quality controls and improved technology, the full potential of inoculation has not been realized because of the numerous site-specific abiotic and biotic factors that affect the lentil-rhizobia symbiosis, and because the survival of rhizobia on pre-inoculated seeds is still a significant problem because of desiccation. Improvements are being made on strain selection and the use of desiccant protectants and adhesives. Inoculants are produced in three different forms: powder with a peat moss carrier; liquid; and granular. Peat-based powdered inoculants are usually applied directly to seeds and are the most common form of delivery. Sterile peat flour is generally used because it supports higher rhizobia populations and has a greater shelf life. Sticking agents are often used to enhance coverage of seeds. A significant disadvantage of seed inoculants is that seeds are limited in the number of rhizobia that coat the seed; smallseeded legumes may only carry a few thousand rhizobia. Another disadvantage is that seeds treated with fungicides or other chemicals may not be suitable carriers of inoculant. Sedge peat carriers used in inoculants generally

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support the growth of rhizobia because they have a high water-holding capacity, a suitable pH, allow uniform dispersion of rhizobia and are nontoxic. Liquid inoculants can be applied to the seed or in the furrow during planting and can have similar efficacy to peat-based inoculants. However, liquid formulations may have a lower shelf life and need to be stored under cool temperatures. The direct application of inoculant to the soil near the seed (soil inoculation) is generally more effective than seed inoculation, particularly in acidic, arid, cool or wet soils (Lupwayi and Kennedy, 2007). Granular inoculants, which are growing in usage, are applied at seeding in the furrow or below the seed. They are most suitable with modern equipment that allows the simultaneous placement of seed, fertilizer and/or inoculant. Granular formulations allow much more control of application rates and placement in the soil. It is currently recommended that granular inoculants be placed directly below or to the side of the seed, instead of in the seedbed. An advantage of granular inoculants is that they are more compatible with other seed treatments because the rhizobia are not in direct contact with the chemicals. Kyei-Boahen et al. (2002) evaluated the efficacy of different seed and soil inoculation methods for chickpea at sites in Saskatchewan, Canada. They found that nodulation after seed inoculation was restricted to the crown region of the root system, whereas soil inoculation increased nodulation of lateral roots. Further, granular inoculant placed below the seed increased seed yield by 17–36% and 5–14% over the liquid and peat-based inoculants, respectively, depending on chickpea cultivar. They concluded that both peat and granular inoculants were equally effective in establishing successful symbiosis, but that placing granular inoculant 2.5–8.0 cm below the seed may improve yield and quality. The selection of the appropriate rhizobia strains are crucial to the successful use of the inoculant. As discussed above, the selected strains must be competitive with indigenous strains, and must have high rates of nodulation and nitrogen fixation. Ideally, the strains must be adapted to the particular soils, climate and plant genotypes used in a geographic region. Tillage Soil health and sustainability are affected significantly by tillage. Conventional tillage reduces soil organic matter, lowers soil water-holding capacity, lowers soil fertility, increases wind and water erosion and increases problem with nutrient runoff. Loss of organic matter after tillage is particularly severe in the tropics (Graham and Vance, 2000). Soil health can be increased greatly by adopting conservation tillage methods of planting, including minimum tillage and no-till. No-till involves the planting of a crop into the stubble of a previous crop. It increases soil organic matter, soil fertility and soil water-holding capacity, and decreases nutrient runoff, soil erosion and fuel costs. Grain legumes are important components of no-till systems because they provide an inexpensive source of soil N for subsequent crops, use less soil water than non-legumes, depending on the specific legumes

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and its root system, and serve to break up the life cycle of crop pests, which can be a problem in no-till and continuous cereal cropping systems. No-till and minimum tillage methods lower mineralization and nitrification rates, and increase immobilization of N (van Kessel and Hartley, 2000). This leads to a decrease in available N, which stimulates nitrogen fixation of legumes planted in no-till soil. van Kessel and Hartley (2000) reviewed field studies involving conservation tillage systems, and found the following: 1. Under conservation tillage the percentage of N from ﬁxation in soybean increased from < 75% under conventional tillage to 85%. 2. Soybean nodulation improved substantially under zero tillage and the average amount of total N2 ﬁxed increased from 180 to 232 kg N/ha. 3. Nitrogen ﬁxation increased by 31% in pea and by 10% in lentil after 4 years in zero tillage in a semi-arid environment. 4. No-till had no effect on nitrogen ﬁxation of chickpea and soybean under low rainfall conditions and high soil nitrate levels. Other studies have shown that the benefit of legumes in no-till systems occurs because of the extra soil moisture conserved from leaving standing stubble over the winter, increasing snow trapping and moisture conservation, and the improved microclimate during the growing season (Miller et al., 2002). Because of the low residue produced by lentils, they do not necessarily prevent erosion when used in no-till systems, at least not in comparison with soil residues from no-till wheat. Thus, it is important to maximize conservation of lentil residue when grown in highly erodible soils. Intercropping Intercropping and mixed cropping of legumes with other crops are common practices in Latin America, Africa and South Asia, which greatly contributes to soil health improvement. For example, more than half of lentil in Bangladesh is grown mixed and intercropped with cereals and broadleaf crops (Sarker et al., 2004). Several studies have shown increased yields, in terms of land equivalent ratios, of non-legumes intercropped with grain legumes, such as chickpea, peas and lentils (van Kessel and Hartley, 2000). Gunes et al. (2007) studied nutrient uptake and yields of intercropped wheat and chickpea and found that mean N content of wheat seed and chickpea seed were 11.2 and 10.2% greater, respectively, when intercropped than when grown alone. Phosphorus content of seed was also significantly greater for both crops, and the land equivalent ratio for aboveground biomass and grains was greater than 1.0, indicating significant benefits of intercropping. Beck et al. (1991) conducted field experiments in France and Syria to examine the effect of intercropping lentils and other grain legumes with cereals on nitrogen fixation, root biomass and the transfer of N from the annual legumes to the cereals. They found no evidence of direct transfer of N from pea to barley when intercropped. The percentage of N in pea derived from nitrogen fixation was 39% higher when intercropped with barley, than

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when grown alone. They concluded that on fertile soils, it is beneficial to intercrop with a legume because of increased N production, greater nitrogen fixation efficiency, and/or greater N mineralization. Non-legume crops grown with grain legumes reduce N pools in soils, thus increasing nitrogen fixation of the companion legume crop. Differences in N demands also reduce competition between legume and cereal intercrops. Green manures Lentils and other grain legumes can be used as both green manures and cover crops. When used as a green manure, lentil is incorporated into the soil before fixed N is transferred to grain to maximize the amount of N added to the soil. Cover crops are typically used to prevent soil erosion and loss of soil organic matter and nutrients. The main benefits of green manures are the addition of organic matter, C, N and other nutrients to the soil, and the protection they offer against erosion when used instead of fallow. Nitrogen inputs of legume green manure range from 45–224 kg N/ha and the amount of N made available to subsequent crops ranges from 40 to 60% of the legume grain N, depending on species (Sullivan, 2003). Bremer and van Kessel (1992) found that about 40% of N in lentil green manure potentially was available for subsequent wheat crops in Canada, but lentil straw was not a significant source of N. Rochester et al. (1998) reported 169 kg N/ha was added to the soil by lentils used as a green manure in Australia (Table 15.1). Biederbeck et al. (2005) showed that lentils and other grain legumes used as green manure had significant effects on soil quality when compared with traditional fallow-wheat cropping systems. In their study conducted in Saskatchewan, Canada, lentils and the other legumes were incorporated into the soil at full bloom and soils were analysed after growing wheat in the sixth year of the experiment, 15 months after the last green fallow period. Their results showed that green fallow returned 208% more N to the soil than fallow-wheat, and increased soil organic matter and total soil N by 11 and 9%, respectively. Lentil green fallow increased populations of bacteria, filamentous fungi, yeasts, nitrifiers and denitrifiers by 101–406%. Activities of microbial degradative enzymes were similarly elevated. The percentage of C and N as microbial biomass were 2.7 and 3.8, respectively, much greater than the percentage sequestered in microbes in a fallow-wheat system. Zentner et al., (1996) conducted a study from 1988 to 1993 to compare the effect of two rotations, green manure–wheat–wheat and fallow–wheat– wheat, on N and water resources. They found that, in general, wheat yields after green manure were lower than after fallow because of reduced availability of soil moisture. Grain protein was greater on green manure fallowed mid-season compared to conventional fallow. Brandt (1996) reported on a 5-year study of summer-fallow alternatives. In his study, wheat after lentil green manure produced comparable yields to wheat after fallow, wheat after wheat, and wheat after grain lentil. Wheat after grain lentil was an

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excellent alternative to fallow because of profits from the crop, but lentil green manure was also considered superior to fallow. Crop rotations with lentils Studies have shown increased yields and protein contents of cereals grown in rotation with lentil and other grain legumes, compared to continuous cereals (Wright, 1990; Stevenson and van Kessel, 1996; Gan et al., 2003; Miller et al., 2003). This ‘rotation effect’ is likely to be the result of several causes including the addition of N to soils (Campbell et al., 1992; Badaruddin and Meyer, 1994; van Kessel and Hartley, 2000; Gan et al., 2003), more soil moisture (Miller et al., 2002, 2003; Gan et al., 2003) and suppression of diseases (Stevenson and van Kessel, 1996). Typically, the growth response of cereals in rotation with grain legumes varies considerably among locations, soil types, years and level of soil N. Walley et al. (2007) provided an excellent review of the actual benefit of grain legumes to the pool of soil N for crops grown in rotation with the legumes. It is often assumed that nitrogen fixation will enhance soil N, but the amount left in the soil depends on how much is removed in grain at harvest. Legume seeds are generally high in protein and, thus, remove a substantial amount of N from the soil. The N increment, Ninc, is the incremental change in soil N due to planting legumes and is highly correlated with nitrogen fixation, but is also highly variable. If the amount of N fixed is greater than the amount removed at harvest (i.e. Ninc >1), then there is a net N benefit for subsequent crops. Walley et al. (2007) assessed a total of 230 published estimates on nitrogen fixation of different grain legumes, including 79 estimates from lentil studies. As expected the estimates of the percentage of N derived from fixation varied considerably because of differences in abiotic, biotic and crop production factors. However, residual soil N seemed particularly important in determining the percentage of N from fixation because of the general inhibitory affect of soil N on nitrogen fixation. Their analysis indicated that lentils need to derive 47.8% of N from fixation to achieve a positive net balance, which they typically exceed. They concluded that lentil, field pea and faba bean are most likely to have a positive N balance, whereas, common bean and kabuli chickpea are likely to have a negative balance. Unless lentil is used as a green manure (see Table 15.1), the actual amount of N returned to the soil is rather small. For example, Biederbeck et al. (1996) estimated that lentil had a net N balance of 9 kg/ha in Canadian prairie soils. Bremer and van Kessel (1992) estimated that about 7% of N in lentil residue was mineralized in the following growing season, and concluded that lentil residue was not a significant source of N for subsequent crops. Although lentils and other pulse crops may not contribute very much N to subsequent crops, it still is greater than N released from cereal residue. Overall, the contribution of lentils to soil health in rotation systems may be cumulative, and may involve other non-N benefits such as improvement in soil moisture and disease suppression.

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Kurdali, F., Kalifa, K. and Al-Shamma, M. (1997) Cultivar differences in nitrogen assimilation, partitioning and mobilization in rain-fed grown lentil. Field Crops Research 54, 235–243. Kyei-Boahen, S., Slinkard, A.E. and Walley, F.L. (2002) Evaluation of rhizobial inoculation methods for chickpea. Agronomy Journal 94, 851–859. Lupwayi, N.Z. and Kennedy, A.C. (2007) Grain legumes in northern Great Plains. Impact on selected biological soil processes. Agronomy Journal 99, 1700–1709. Martinez-Romero, E. (2003) Diversity of Rhizobium-Phaseolus vulgaris symbiosis: overview and perspective. Plant and Soil 252, 11–23. Matus, A., Derksen, D.A., Walley, F.L., Loeppky, H.A. and van Kessel, C. (1997) The influence of tillage and crop rotation on nitrogen fixation in lentil and pea. Canadian Journal of Plant Science 77, 197–200. May, S.N. and Bohlool, B.B. (1983) Competition among Rhizobium leguminosarum strains for nodulation of lentils (Lens esculenta). Applied and Environmental Microbiology 45, 960–965. McKenzie, B.A., Andrews, M. and Hill, G.D. (2007) Nutrient and irrigation management. In: Yadav, S.S., McNeil, D. and Stevenson, P.C. (eds) Lentil: an Ancient Crop for Modern Times. Springer, Dordrecht, The Netherlands, pp. 145–158. McNeil, D.L. and Materne, M. (2007) Rhizobium management and nitrogen fixation. In: Yadav, S.S., McNeil, D. and Stevenson, P.C. (eds) Lentil: an Ancient Crop for Modern Times. Springer, Dordrecht, The Netherlands, pp. 127–143. McNeill, A.M., Pilbean, C.J., Harris, H.C. and Swift, R.S. (1996) Seasonal variation in the suitability of different methods for estimating biological nitrogen fixation by grain legumes under rain fed conditions. Australian Journal of Agricultural Research 47, 1061–1073. Miller, P.R., McConkey, B.G., Clayton, G.W., Brandt, S.A., Staricka, J.A., Johnston, A.M., Lafond, G.P., Schatz, B.G., Baltensperger, D.D. and Neill, K.E. (2002) Pulse crop adaptation in the Northern Great Plains. Agronomy Journal 94, 261–272. Miller, P.R., Gan, Y., McConkey, B.G. and McDonald, C.L. (2003) Pulse crops for the Northern Great Plains. II. Cropping sequence effects on cereal, oilseed, and pulse crops. Agronomy Journal 95, 980–986. Misra, S.K., Upadhyay, R.M. and Tiwari, V.N. (2002) Effects of salt and zinc on nodulation, leghaemoglobin and nitrogen content of rabi legumes. Indian Journal of Pulses Research 15, 145–148. Moawad, H. and Beck, D. (1991) Some characteristics of Rhizobium leguminosarum isolates from uninoculated field-grown lentil. Soil Biology and Biochemistry 23, 917–925. Moawad, H., Badr El-Din, S.M.S. and Abdel-Aziz, R.A. (1998) Improvement of biological nitrogen fixation in Egyptian winter legumes through better management of Rhizobium. Plant and Soil 204, 95–106. Peoples, M.B. and Craswell, E.T. (1992) Biological nitrogen fixation: investments, expectations and actual contributions to agriculture. Plant and Soil 141, 13–39. Peoples, M.B., Bowman, A.M., Gault, R.R., Herridge, D.F., McCallum, M.H., McCormick, K.M., Norton, R.M., Rochester, I.J., Scammell, G.J. and Schwenke, G.D. (2001) Factors regulating the contribution of fixed nitrogen by pasture and crop legumes to different farming systems of eastern Australia. Plant and Soil 228, 29–41. Prasad, A.K., Murtuza, M., Singh, A.P. and Mallick, M.K. (2004) Effect of seed inoculation with Rhizobium strains and sulphur on nodulation and nitrogen nutrition of lentil (Lens culinaris L.). Journal of Research, Birsa Agricultural University 16, 187–195.

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M.A. Quinn Rai, R. and Singh, R.P. (1999) Effect of salt stress on interaction between lentil (Lens culinaris) genotypes and Rhizobium spp. strains: symbiotic N2 fixation in normal and sodic soils. Biology and Fertility of Soils 29, 187–195. Rennie, R.J. and Dubetz, S. (1986) Nitrogen-15-determined nitrogen fixation in fieldgrown chickpea, lentil, fababean, and field pea. Agronomy Journal 78, 654–660. Rochester, I.J., Peoples, M.B., Constable, G.A. and Gault, R.R. (1998) Faba beans and other legumes add nitrogen to irrigated cotton cropping systems. Australian Journal of Experimental Agriculture 38, 253–260. Sarker, A., Erskine, W., Bakr, M.A., Rahman, M.M., Afzal, M.A. and Saxena, M.C. (2004) Lentil Improvement in Bangladesh. Asia-Pacific Association of Agricultural Research Institutions Publication 2004/1. Asia-Pacific Association of Agricultural Research Institutions, Bangkok, Thailand. Sarker, A., Erskine, W. and Singh, M. (2005) Variation in shoot and root characteristics and their association with drought tolerance in lentil landraces. Genetic Resources and Crop Evolution 52, 89–97. Shah, N.H., Hafeez, F.Y., Arshad, M. and Malik, K.A. (2002) Response of lentil to Rhizobium leguminosarum bv. viciae strains at different levels of nitrogen and phosphorus. Australian Journal of Experimental Agriculture 40, 93–98. Shah, Z., Shah, S.H., Peoples, M.B., Schwenke, G.D. and Herridge, D.F. (2003) Crop residue and fertiliser N effects on nitrogen fixation and yields of legume-cereal rotations and soil organic fertility. Field Crops Research 83, 1–11. Singh, K.K., Srinivasarao, C. and Ali, M. (2005) Root growth, nodulation, grain yield, and phosphorus use efficiency of lentil as influenced by phosphorus, irrigation, and inoculation. Communications in Soil Science and Plant Analysis 36, 1919–1929. Singleton, P.W., Bohlool, B.B. and Nakao, P.L. (1992) Legume response to rhizobial inoculation in the tropics: myths and realities. In: Lal, R. and Sanchez, P.A. (eds) Myths and Science of Soils of the Tropics. Soil Science Society of America and American Society of Agronomy, Madison, Wisconsin, USA, pp. 135–155. Slattery, J.F., Pearce, D.J. and Slattery, W.J. (2004) Effects of resident communities and soil type on the effective nodulation of pulse legumes. Soil Biology and Biochemistry 36, 1339–1346. Smith, S.C., Bezdicek, D.F., Turco, R.F. and Cheng, H.H. (1987) Seasonal N2 fixation by cool-season pulses based on several 15N methods. Plant and Soil 97, 3–13. Stephens, J.H.G. and Rask, H.M. (2000) Inoculant production and formulation. Field Crops Research 65, 249–258. Stevenson, F.C. and van Kessel, C. (1996) The nitrogen and non-nitrogen rotation benefits of pea to succeeding crops. Canadian Journal of Plant Science 76, 735–745. Sullivan, P. (2003) Overview of Cover Crops and Green Manures. Available at: www. attra.ncat.org/attra-pub/covercrop.html (accessed 8 January 2008). Unkovich, M.J. and Pate, J.S. (2000) An appraisal of recent field measurements of symbiotic N2 fixation by annual legumes. Field Crops Research 65, 211–228. van Kessel, C. (1994) Seasonal accumulation and partitioning of nitrogen in lentil. Plant and Soil 164, 69–76. van Kessel, C. and Hartley, C. (2000) Agricultural management of grain legumes: has it led to an increase in nitrogen fixation? Field Crops Research 65, 165–181. Ventorino, V., Chiurazzi, M., Aponte, M., Pepe, O. and Moschetti, G. (2007) Genetic diversity of a natural population of Rhizobium leguminosarum bv. viciae nodulating plants of Vicia faba in the Vesuvian area. Current Microbiology 55, 512–517. Walley, F.L., Clayton, G.W., Miller, P.R., Carr, P.M. and Lafond, G.P. (2007) Nitrogen economy of pulse crop production in the Northern Great Plains. Agronomy Journal 99, 1710–1718.

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Wani, S.P., Rupela, O.P. and Lee, K.K. (1995) Sustainable agriculture in the semi-arid tropics through biological nitrogen fixation in grain legumes. Plant and Soil 174, 29–49. Weigand, S., Pala, M. and Saxena, M.C. (1992) Effect of sowing date, fertilizer and insecticide on nodule damage by Sitona crinitus Herbst (Coleoptera: Curculionidae) and yield of lentil (Lens culinaris Medik.) in northern Syria. Zeitschrift fuer Pﬂanzenkrankheiten und Pﬂanzenschutz (Germany, F.R.) 99, 174–181. Wright, A.T. (1990) Yield effect of pulses on subsequent cereal crops in the northern prairies. Canadian Journal of Plant Science 70, 1023–1032. Yanni, Y.G. (1992) Performance of chickpea, lentil and lupin nodulated with indigenous or inoculated rhizobia micropartners under nitrogen, boron, cobalt and molybdenum fertilization schedules. World Journal of Microbiology and Biotechnology 8, 607–613. Zahran, H.H. (2001) Rhizobia from wild legumes: diversity, taxonomy, ecology, nitrogen fixation and biotechnology. Journal of Biotechnology 91, 143–153. Zarei, M., Saleh-Rastin, N., Alikhani, H. and Aliasgharzadeh, N. (2006) Response of lentil to co-inoculation with phosphate-solubilizing rhizobial strains and arbuscular mychorrhizal fungi. Journal of Plant Nutrition 29, 1509–1522. Zentner, R.P., Campbell, C.A., Biederbeck, V.O. and Selles, F. (1996) Indianhead black lentil as green manure for wheat rotations in the Brown soil zone. Canadian Journal of Plant Science 76, 41–422.

16

Mechanization

Jürgen Diekmann1 and Yahya Al-Saleh2 1International

Center for Agricultural Research in the Dry Areas (ICARDA), Aleppo, Syria; 2University of Aleppo, Aleppo, Syria

16.1. Introduction In comparison with most other field crops mechanization in lentil is an issue because of the crop’s short stature and its tendency to lodge. Lentil mechanization is currently organized around an extremely wide range of techniques. Mediterranean areas are partially mechanized with a full range of labour-intensive techniques still being practised in small-scale farming in the majority of Middle Eastern countries, including hand broadcasting of the seeds to establish the crop, often hand weeding and hand harvesting. The reasons are cheap and available labour and limited availability of modern agronomic production schemes. Also, the crop often lodges and seedbeds have a preponderance of stones and are usually not level. Among the harvest methods, hand harvesting is often preferred because of the market value of the straw for feeding small ruminants and the fact that straw losses are kept to a minimum. However, increased exports from Canada, Australia and the USA, where mechanization is universally applied, impacts world lentil prices in a downward direction, whereas countries with high production costs because of lack of mechanization stand to lose market share. At present the most important producers in the Middle East are Syria, Turkey and Iran. A reduction of lentil production area in other countries of the region and elsewhere may be related to high production costs where mechanization was not achieved. India is presently one of the top producers with very little mechanization. At the same time India is planning for increased use of zero-tillage techniques, particularly in connection with rice production (Hobbs et al., 1997). This may be an opportunity for a greater move towards mechanization. Other parts of the world, particularly Australia and North America, have low labour availability and high labour costs. In fact, their processing power is expressed in ha/h/person, rather than man h/ha! While in traditional 248

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production areas 20–30 man days are required to harvest a single hectare, 1–4 ha/h/person can be harvested in a fully mechanized scheme. Harvesting can be mechanized as a two-stage operation with cutting and threshing being done separately, or as a single-stage (‘combine’) harvesting. Preconditions for mechanized harvesting are: 1. The crop has to be upright and without pod dehiscence. 2. The minimum height of the lowest pod is 10 cm above the soil surface. 3. A level and smooth seedbed or soil surface rather than a ridged and uneven surface that is common with traditional production systems. 4. The combine must be adapted so that it has: low cutting heights by adjustment of the cutting table; small working widths (preferably 3–4 m) with rigid headers so it is well adapted to cope with lateral soil-surface undulations (ﬂexible headers can operate with wider working widths); low drum speeds and a concave (ﬁxed grid around part of the drum, through which the thrashed grain has to pass) with smooth and rounded surfaces for low seed breakage.

16.2. Field Selection Selecting fields for lentil production considering mechanization involves a check for physical obstacles to the passage of cutter bars/combines. The ideal areas from this perspective are of course flat, level fields without stones or other obstacles to low cutting heights. Cultivation on slopes is manageable as long as the surfaces are levelled laterally and longitudinally in a way to allow uniform cutting heights at about 3–8 cm. This aim can be reached when all previous operations, particularly tillage and traffic on the field (e.g. during previous harvest), have aimed to eliminate undulations and improve on levelling. Fields under zero tillage require special attention, as no levelling through tillage is possible (Anon., 2008). The need for a flat surface calls for rolling after planting in most cases. Additionally in zero-till areas stubble from the previous crop may be a problem and so fields should be selected where stubble has been cut short, chopped and evenly distributed.

16.3. Soil Tillage Lentils are typically grown in rotation with cereals. In the Middle East cereal-crop residues are either removed for use in animal feeding, incorporated by tillage or burned. In North America and Australia, straw is often kept at the surface, or incorporated shallowly to reduce soil erosion in conservation agriculture systems. Three basic options exist for seedbed preparation: deep tillage, shallow tillage or zero tillage.

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Deep tillage Deep tillage provides good incorporation of straw and stubble, mostly through mouldboard ploughing. Deep tillage is best carried out when residues have been chopped to a maximum length of 10 cm, either by a chopper integrated into the combine or operated by a tractor following the swathes of straw. The best timing for deep tillage is when soils are relatively dry to avoid compaction. In heavy clays mouldboard ploughs should only be operated under dry conditions, because sticky soil hampers soil inversion by sticking to the surface of the mouldboards.

Shallow tillage Shallow tillage is an appropriate choice if only small quantities of residue are to be incorporated and the soil is not compacted from previous management. Duckfoot tines or disc harrows can be operated more cheaply and faster than mouldboard or disc ploughs and can leave a more levelled surface. Under conditions of residual moisture being left from the previous season, two tillage operations may be required for efficient weed control.

Zero tillage Direct seeding offers three possible advantages: ● ● ●

Reduced erosion risks. Lower operation costs. Reduced moisture evaporation losses.

This technique requires suitable planting equipment particularly under stony conditions. Where residual moisture is available from the previous season, chemical weed control (e.g. with herbicides such as glyphosate) is required to control summer weeds. For lentil harvesting there may be a problem with surface undulation, as the degree of levelling by rolling is limited, particularly on heavy clays. Zero-tillage techniques are in wide use in Australia and North America, but are rarely adopted by farmers in the Middle East.

16.4. Seedbed Preparation In the Middle East appropriate agricultural equipment for seedbed preparation is rarely available. The most frequently used equipment is a duckfoot cultivator combined with a levelling bar. This equipment provides some degree of levelling, but it leaves seedbeds far too loose and inadequately levelled. Another factor producing uneven seedbeds is the widely used hard tyres of the ‘diagonal’ type which are usually of a size requiring about

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a 1.6 bar inflation rate. It is recommended to use ‘radial’ tyres with a size large enough to require no more than 1–1.2 bar internal pressure. Recommended equipment for seedbed preparation if used properly will achieve a medium soil structure and sufficient firmness for good control of the planting depth and soil-to-seed contact, while preventing the formation of deep tyre tracks during planting and weed-control operations. Combining seedbed preparation and planting in one operation improves field levelling while reducing the number of equipment passes over the field. This can be achieved by combining relatively short harrows with a conventional seeder or through the use of other tillage-plus-planting units, as often used in North America and Australia.

16.5. Seeding Most seeders used in the eastern Mediterranean region are simple models with actively ‘digging’ tines that are able to complete the planting operation in seedbeds that are minimally prepared. This is a robust and inexpensive solution to seedbed preparation and can be improved for mechanized harvesting by rolling the fields after seeding; however, seed rates of two to two-and-a-half times the normal rate are required to achieve an adequate plant stand. Good seeding equipment can reduce seed rates by 50 kg/ha or more and provide a saving of an estimated US$20–40/ha. This is an amount sufficient to pay for recommended solutions to the problem of seeding and crop establishment. Recommended seeding machines are able to plant at row spacings of 10–20 cm and control the planting depth precisely enough to place the majority of seeds at 3–5 or 4–6 cm depths or other preferred depths. For further discussion of seeding rates see Ali et al. (Chapter 14, this volume). A levelling device, either as a simple bar or tine system following the coulters, is recommended for good seed cover. This is important to promote high germination percentage rates as well as for safety with preemergence herbicides. A report (Anon., 2007a) from Australia indicates that lentils are well suited to no-till, reduced tillage and stubble retention systems. If the crop is sown with the appropriate equipment direct seeding into standing cereal stubble is often possible.

16.6. Rolling Rolling after seeding generally smooths the soil surface and promotes rapid germination and uniform emergence by improving seed-and-soil contact. In addition, rolling smooths and levels the soil surface and presses stones into the soil, which is a prerequisite for subsequent harvest by cutting plants with cutter bars at a stubble height of less than 10 cm. Rolling should be avoided when the seeds are germinating to avoid excessive damage to the emerging plants. Suitable rollers are for example Cambridge or crosskill rollers, but also rollers assembled with V-shaped rings are suitable. It is

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important to leave a profiled surface, as otherwise flat, sealed surfaces increase the risk of erosion with heavy rainfall. Rolling is only recommended where surfaces are dry. Rollers should have a weight of 400–700 kg/m working width. Working widths of rollers can range from just 3 m to 12 m, or more. Rolling after emergence is recommended until the 5–7 node stage is reached (Anon., 2007b). Also, a minimum time span of 2 days between rolling and herbicide application is recommended. Rolling should not follow immediately after frost (Anon., 2000).

16.7. Weed Management Lentil production in the Middle East includes manual weed control, although mechanized inter-row cultivation and herbicides are available. Weed management is also discussed by Yenish et al. (Chapter 20 this volume). Hand weeding does not have an impact on the choice of a harvesting system. Mechanized weed control, like inter-row cultivation, use of a weed brush or a weeding harrow may have a negative effect on mechanized harvest, because surfaces may become undulating, and/or stones may be brought up onto the surface and increase the necessary stubble length at harvest time, which increases pod losses. In most cases plants, at the time of inter-row cultivation, are too tall for a subsequent rolling operation. From experience at the International Center for Agricultural Research in the Dry Areas (ICARDA) it can be said that only hand weeding or inter-row cultivation are economic and/or efficient. Inter-row cultivation is the most efficient mechanized method of weed control; weeding harrows that work across the surface have not worked satisfactorily (Fig. 16.1). Weed brushes are not designed for cheap, economic operations, but for (horticultural) high-value crops. While they do a good and efficient job of weed control, they are too expensive and have insufficient capacity for large-scale agriculture. Inter-row cultivators depend on the crop being planted by a seeder, because the operation requires parallel rows with equal distances. The working width of the seeder must match the working width of the inter-row cultivator. Row spacings from 30 cm and wider are required (Diekmann et al., 1992). For lentils, 30–40 cm row spacings are ideal where inter-row cultivation is planned. Soil problems can occur on heavy clay soils especially when the soil is wet and sticky, while a preponderance of stones can obstruct the blades of the inter-row cultivation equipment. Working depths should be as shallow as possible and just deep enough to cut off the weeds below the soil surface. Where harvest is planned to be mechanized, either by cutter bars, swathers or combines, inter-row cultivation will usually require longer stubble heights and is likely to increase pod losses. Reasons for slow adoption of herbicides for weed control can be the costs and the risk of reduced

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(a)

(b)

(c)

(d)

Fig. 16.1. Mechanical weed control: (a) hand-pushed weeding hoes; (b) inter-row cultivator in double-row planting (most economic tool); (c) weeding brush for high-value crops; and (d) weeding harrow (high capacity but low efficiency).

yields under dry and/or cold conditions. Lack of experience in the use of herbicides may also be a factor preventing their more widespread use. Complete mechanization is easiest to achieve when weed control is entirely by chemical means. This is the standard approach in Australia and North America (Anon., 2007a, b). Parasitic weeds (Orobanche sp., Cuscuta sp.) are problematic for traditional and mechanized production. Thus far the only means of control is through the use of systemic herbicides that reduce parasitism of host plants. Manual removal of parasitic weeds is not proven to be efficient because of the late visibility of the weeds and at the time of visibility of the parasite, most of the damage to growth and yield has taken place.

16.8. Harvest The harvesting method remains the most diverse part of lentil production, with hand harvesting still being practised in the Middle East and Asian countries (Fig. 16.2). Lentil harvest in North America and Australia is fully

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(b)

(a)

(d)

(c)

(e)

Fig. 16.2. (a) Lentil harvest in Syria at present is often organized as hand pulling; (b) drying in heaps for 5–10 days; (c) followed either by traditional threshing; (d) or threshing with a combine; (e) which also chops and bags the straw.

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mechanized, with either two-stage (swathing and threshing) or single-stage (‘combining’) methods. Hand harvesting Plants are pulled at the half-green/half-brown stage and left in small heaps in the field or transported to the threshing area and left for drying before being threshed. Threshing may be done by hand, by animal-drawn threshers or by stationary threshers. It has been estimated that 20 man days are required to harvest a hectare of lentils yielding 1200 kg of grain and 1800 kg of straw (Khayrallah, 1981). Labour costs are a limiting factor for economical production using these traditional methods (Papazian, 1983). Two-stage harvest The two-stage harvest in the Middle East typically starts with use of a cutter bar, followed by manual collection of the dried material and transport to the threshing place at the farm or village. During the 1980s ICARDA tested several methods to mechanize the cutting as a first step (Erskine et al., 1991). This included using existing cutter bars as well as other concepts. Lentil pulling As straw sales are part of the income from a lentil crop, several attempts were made to simulate hand pulling by machine, without increasing the loss of straw. The first development was made at Reading University in 1960, followed by Snobar (1979) in Jordan and Tauscher in Turkey and ICARDA. The Tauscher system is functional and achieves lentil pulling at the same stage as hand harvesting with acceptable losses (<10% for grain and straw), but the 2 m wide machine was not cost effective. The capacity of the trialed machine was about 0.5 ha/h and would leave the pulled crops in a swathe (Friedrich, 1988). Soybean blades Another idea that was tested was to use soybean cutting blades to simulate hand pulling, in order not to loose straw. The blades were designed to cut the lentil crop at a shallow depth of 2–5 cm below the soil surface. The problem is that just too often moisture is available in that layer from recent rains. This produces clogging of the blades, because of the sticky soil. The idea is therefore impractical. Cutter bars Cutter bars are acceptable where straw losses of about 20% can be tolerated. Preconditions for the use of cutter bars are reasonably levelled fields and no

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(b)

(d)

(c)

Fig. 16.3. Knife arrangements for lentil harvest: (a) single knife and rigid fingers; (b) double knife; (c) double knife with bottom knife fixed; and (d) flexible cutter bar.

large stones on the surface. The optimum height of cutting is about 5 cm (Friedrich, 1988). For conventional cutter bars with rigid fingers, stones cause the biggest problem. For this reason a double-knife system, without rigid fingers, is the most suitable for cutting close to the soil surface (Fig. 16.3). Cutter bars of about 2 m working width are suitable for smaller areas and can be a first step towards mechanization under Middle Eastern conditions. The recommended cutter bar is designed to operate even if small stones or other obstacles are at the cutting level. This is usually a problem for the standard cutter bars, where damage to the knife blades is frequent with very low cutting heights. The problem occurs when hard objects get stuck between the rigid fingers, obstructing the passage of the knife. The double-knife cutter bar has no rigid fingers, but two oscillating knife assemblies (Fig. 16.4). Unfortunately this equipment is no longer widely available, because the market for standard mowers has moved to disc-anddrum mowers, which are not suitable for lentil harvest. The discs and drums rotate with high speed and cause pod losses through strong vibrations, even at the half-green/half-brown maturity stage, which is the correct time for this harvesting method. Double-knife cutter bars are still made and used in Turkey. The advantage of the use of cutter bars is that cutting is at about the same maturity stage as for hand harvesting, which reduces the risk of pod loss and pod dehiscence.

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(a)

(b)

(c)

(d)

Fig. 16.4. Harvest machinery being tested: (a) self-mobile cutter bar; (b) double-knife cutter bar; (c) lentil puller; and (d) soybean blades.

Swathers In fully mechanized schemes, like in North America and Australia, higher capacity equipment, like self-mobile swathers with 3–12 m working widths, are used. These machines are also available with double-knife cutting systems. Machines of this type are used where separating cutting from threshing has an advantage. Reasons to carry out harvest in a two-stage manner can be that the climate does not stop the crop growth. Lentils have an indeterminate growth habit and will not come to maturity without heat or drought stress (Anon., 2007b). Swathing is recommended when one-third of the bottom pods turn yellow to brown and seeds rattle when pods are shaken. Also the machine capacity at cutting is higher than with singlestage techniques. The forward speed for swathers may be as high as about 15 km/h under ideal conditions. The swathe formed by the machine is left to dry, which may take from a few days to up to 2 weeks (Muehlbauer et al., 1998). A further advantage of this technique is that all the vegetation, including weeds and volunteers, is cut at an earlier stage, which may keep fields cleaner by avoiding renewed seed setting. Threshing is then done with combine equipment with a pick-up header, which is working at a width of 2–3 m. A disadvantage of this technique is the need for two separate field operations.

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Single-stage harvest Full mechanization can be achieved with standard combines. Under Middle East conditions the limitation in width is required because of the simple, rigid design of the older types of combines used, as well as the relatively small field sizes that favour 3 m (maximum of 4 m) wide tables which can follow contours easily. Similar to cutter bars and swathers, combine headers may also be equipped with knife systems adapted to very low cutting heights, such as replacing the rigid-finger plus single-knife system with a double-knife system in which both knives are active, or with a double-knife system in which one is fixed and the other oscillates. The targeted cutting height is below 10 cm so that all pods can be undercut. While the double-knife system with two oscillating knives is considered the best and most reliable, the demand was too low to permit manufacturers to offer it on these standard, narrow tables. Instead, various combine manufacturers offer replacement of the fingers by additional triangular, fixed blades under the oscillating knife. The oscillating knife needs to be held close to the fixed blades by additional plates every 20–30 cm. This system is much safer to operate and is almost undisturbed by stones. The problem comes with the gaps between the fixed plates and the oscillating blades. Any moisture in the plant stems or in the soil will often create a layer of sticky coating. This must be removed to avoid gaps between the knife and plate, making a clean cut impossible. A simple way to remove the coating is by brushing at regular intervals with a broom dipped in water with dish-washing liquid. The simple replacement of the rigid fingers by triangular plates may not be sufficient to achieve low losses. Many standard knives of combine cutting tables are working with an inclination towards the soil surface. This is a good working principle with stubble lengths over 10 cm, but where short stubbles are required the knife should work horizontally. This can be achieved by adjusting the angle between the steel holding the knife assembly and the front edge of the table. The reel requires reel tine covers, which are metal boards with rubber flaps, operating like paddles. Their function is to ensure the proper flow of harvested material, particularly pods of lentils. The reel speed should match the ground speed, with a maximum of 10% higher speed for the reel. In North America and Australia the large areas to be harvested have led to the development of headers which are mounted with flexible cutterbar assemblies. For very large working widths the left and right halves of the headers can also be tilted. Both options together offer working widths up to 12 m. Another factor that enables the use of such working widths is that lentils are grown mostly on stone-free soils in these regions. Beside losses at the header a second critical point with lentil threshing is the risk of breaking seeds during the drum-concave passage. The drum has to be operated at a relatively low speed, with a circumferential speed below 13 m/s. This specification is required because the drum diameters of various combine models and manufacturers range from 45 cm to 66 cm. A

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drum with a 45 cm diameter performs well for lentils at a speed of 300 rpm, about 7 m/s, provided the crop is dry. The concave must be as smooth as possible. First of all it must be assured that the de-awning bars, used for barley and sometimes durum, are removed. The grid of the concave must not have any sharp edges. A wire concave is preferable to avoid breakage. It performs better than a perforated steel sheet, because it has a higher percentage of clearance. Concaves with about 8 mm (and up to 12 mm) open space can be used. Clearance of the concave at the inlet side is recommended to be up to 17 mm, and at the outlet side up to 15 mm. This can be reduced in case of unsatisfactory results. If reducing the concave clearance does not work, the drum speed may be increased (Gerdes, 1987). Timing of threshing is critical as the best performance is possible at grain moisture contents of 16–22%. This ensures low pod breakage, but requires drying or aeration of the crop after threshing. If the crop is already dryer than 16% moisture, it is best to work in the early morning with a low drum speed and a wider concave opening. Below 12% moisture the risk of cracking increases substantially (Anon., 2007b). This requirement shortens the time window for any field down to a few days, particularly under conditions in the Middle East. The sieve settings are similar to cereal threshing. The top sieve (frogmouth) can be opened up to 1.5 times of the lentil diameter and the sieve extension slightly wider. The bottom sieve can be an adjustable frogmouth sieve with about 10 mm clearance or a round-hole sieve with even larger holes. The use of flat sieves reduces the amount of broken grains (Gerdes, 1987). As lentils are relatively heavy, wind (draught) intensity has to be relatively high. Cleaning needs to be adjusted so that returns are as low as possible to avoid the risk of broken grains. In the Middle East farmers value the straw almost as much as they do that of the grain. It is therefore essential not only to maintain a low cutting height, keeping short stubble, but also to enable collection of the non-grain material. Farmers have therefore converted standard combines into units that collect, chop and bag the straw. This is of interest as long as the market pays high prices for the chopped and bagged product. In other areas, such as in the USA, Canada and Australia, straw is not harvested and collected but is incorporated into the soil. Also, the size of combines in these areas is larger than in the Middle East and harvesting may be done with cutting tables up to 10 m wide. For thinner, shorter or lodged crops harvest direction may have to be one way (Anon., 2007a).

16.9. Cleaning and Storage In West Asia and North Africa, after hand harvesting and two-stage harvest, it is now more common for threshing to be carried out by combines being hand fed, rather than with the old village-type (stationary) threshers. Basically the same settings apply as described under the heading ‘Single-stage harvest’, from concave clearance to sieve opening and wind.

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According to Muehlbauer et al. (1985) typical grading for marketable products is specified as: ● ●

Red lentils: <3 mm diameter, with 50% being larger than 4.35 mm. Yellow lentils: <5 mm, with 50% being larger than 7 mm.

Lentil seeds are more prone to mechanical damage than other pulses. Handling and especially the use of augers should be kept to a minimum (Anon., 2007a).

16.10. Losses Al-Saleh (2000) compared losses from various harvesting systems. Hand harvesting had the lowest losses of about 8% of straw and 11% of grain. Systems based on double-knife cutter bars created 15% straw losses and 16% grain losses. Swathers with augers produced 22% straw losses and 23% grain losses. The combine adapted at ICARDA with a 3 m header and a double-knife cutter bar achieved 30% straw losses and 16% grain losses. These values are not absolute, but show the range of losses and indicate that hand harvesting and single-stage combining produce the least amount of grain losses.

16.11. Costs In industrialized countries only fully mechanized techniques are feasible because of relatively high labour costs. Also the value of straw is not a major component of income to the producer. Therefore the only choices are to opt for a two-stage harvest, if losses or forced ripening (drying) are an issue, or otherwise choose the most economic way of direct combine harvesting. In countries with lower labour costs all alternatives from hand pulling to full mechanization are possible. The costs of hand pulling are of interest for example in Syria or Turkey. Hand pulling required 42% of the total production costs according to a survey conducted in Turkey (Özcan, 1986). Logically, Turkey shows a considerable degree of mechanization mainly through the use of cutter bars. A more recent survey in Syria and Turkey (Al-Saleh, 2000) revealed that 44% of total production costs were required for hand pulling and 65% of the total costs for pulling and threshing. A double-knife cutter bar reduced the portion for harvesting costs to 33% and harvest-plus-threshing costs to 52%. Single-stage (combine) harvesting reduced harvest-plus-threshing costs to 20% of the total.

References Al-Saleh, Y. (2000) Suriye ve Türkiye de mercimek ve nohut hasadında mekanizasyon olanaklarının belirmesi üzerine bir aras¸tırmaç. PhD thesis, Çukurova Universitesi, Adana, Türkiye.

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Anon. (2000) Lentil production. In: Pulse Production Manual. Saskatchewan Pulse Growers, Saskatoon, Saskatchewan, pp. 1–32. Available at: www.saskpulse.com/ media/pdfs/ppm-lentil.pdf (accessed 29 November 2007). Anon. (2007a) Lentils in South Australia and Victoria. Pulse Australia, Bungwahl, New South Wales, 20 pp. Available at: www.pulseaus.com.au/crops/lentils/476/lentils %20fs%20/2007%20final.pdf (accessed 29 November 2007). Anon. (2007b) Red Lentil Production. Government of Saskatchewan. Available at: www.agriculture.gov.sk.ca/Default.aspx?DN=a88f57f0-242b-40f6-8755-1fc6df4 dfa14 (accessed 30 October 2007). Anon. (2008) Lentil: Crop Establishment and Production. West Australian Department of Agriculture. Available at: www.agric.wa.gov.au/content/fcp/lp/lent/cp/lentesaintr. htm (accessed 22 May 2008). Diekmann, J., Bansal, R.K. and Monroe, G.E. (1992) Developing and delivering mechanization for cool season food legumes. In: Expanding the Production and Use of Cool Season Food Legumes. Kluwer Academic Publishers, Dordrecht, The Netherlands, pp. 517–528. Erskine, W., Diekmann, J., Jegatheeswaran, P., Salkini, A., Saxena, M.C., Ghanaim, A. and El Ashkar, F. (1991) Evaluation of lentil harvest systems for different sowing methods and cultivars in Syria. Journal of Agricultural Science, Cambridge 117, 333–338. Friedrich, T. (1988) Untersuchungen zur Mechanisierung der Linsenernte nach dem Rupfprinzip im Vergleich zu anderen Linsenernteverfahren in Syrien. Dissertation MEG-141, Universität Göttingen, Göttingen, Germany. Gerdes, J. (1987) Combine Instruction. Claas Company, Harsewinkel, Germany, pp. 75–78. Hobbs, P.R., Giri and Grace, P. (1997) Reduced and zero tillage options for the establishment of wheat after rice in South Asia. Consortium Paper Series 2. RiceWheat Consortium for the Indo-Gangetic Plaines, New Delhi, India. Khayrallah, W.E. (1981) The mechanization of lentil harvesting. In: Webb, C. and Hawtin, G. (eds) Lentils. International Center for Agricultural Research in the Dry Areas (ICARDA), Aleppo, Syria, pp. 131–141. Muehlbauer, F.J., Cubero, J.I. and Summerfield, R.J. (1985) Lentil (Lens culinaris Medic.). In: Summerfield, R.J. and Roberts, E.H. (eds) Grain Legume Crops. Collins, London, UK, pp. 266–311. Muehlbauer, F.J., Summerfield, R.J., Kaiser, W.J., Clement, S.L., Boerboom, C.M., Welsh-Maddux, M.N. and Short, R.W. (1998) Principles and Practice of Lentil Production. US Department of Agriculture, Agricultural Research Service. ARS 141. p. 26. Available at: www.ars.usda.gov/is/np/lentils/lentilsintro.htm?pf=1 (accessed 30 November 2007). Özcan, M.T. (1986) Mercimek Hasat ve Harman Yöntemlerinin I˙s¸ verimi, Kalitesi, Enerji Tüketimi ve Maliyet Yönünden Kars¸ılas¸tırılması ve Uygun Bir Hasat Makinesi Gelis¸tirilmesi Üzerinde Aras¸tırmalar. Türkiye Zirai Donatım Kurumu Yayınları, Yayın No 46. Ankara, Türkiye. Papazian, J. (1983) Lentil harvesting. Lens Newsletter 10(2), 1–6. Snobar, B. (1979) A mechanical technique to harvest lentils. Research Journal of University of Jordan VI(2), 7–14.

17

Diseases and their Management

Weidong Chen,1 Ashwani K. Basandrai,2 Daisy Basandrai,2 Sabine Banniza,3 Bassam Bayaa,4 Lone Buchwaldt,5 Jenny Davidson,6 Richard Larsen,7 Diego Rubiales8 and Paul W.J. Taylor9 1USDA-ARS,

Washington State University, Pullman, Washington, USA; 2CSK Himachal Pradesh Agricultural University, Dhaulakuan, India; 3University of Saskatchewan, Saskatoon, Canada; 4International Center for Agricultural Research in the Dry Areas (ICARDA), Aleppo-Syria; 5Agriculture and Agri-Food Canada, Saskatoon, Canada; 6South Australian Research and Development Institute, Adelaide, Australia; 7United States Department of Agriculture (USDA) Agriculture Research Service (ARS), Prosser, Washington, USA; 8Institute for Sustainable Agriculture, CSIC, Córdoba, Spain; 9The University of Melbourne, Victoria, Australia

17.1. Introduction Lentil is an important crop in many parts of the world, cultivated under various production systems. Lentil crops are affected by a number of diseases caused by bacteria, fungi, viruses and nematodes. Some diseases are common in most lentil-growing regions worldwide, whereas others are limited to certain production areas. The economic importance of a particular disease is not necessarily related to its geographic distribution. A disease may have limited occurrence, but still it may cause significant economic losses. Under conducive conditions, these diseases, singly or collectively can cause significant reductions in both grain yield and quality. Hence, proper management of these diseases is necessary to ensure sustainable productivity and profitability of lentil. This chapter reviews the important fungal and nematode diseases of lentil and their management. Virus diseases and parasitic weeds of lentil are subjects of Chapters 19 and 21, respectively, of this book. The important foliar diseases include Ascochyta blight, rust, Botrytis grey mould, anthracnose, Stemphylium blight and powdery mildew, and important soil-borne diseases are Fusarium wilt, Sclerotinia stem rot and nematode diseases. Attempts have been made to include the most recent information on these diseases, however, the readers are also referred to previous reviews by Khare (1981), Agrawal and Prasad (1997), Morrall (1997), Bayaa and Erskine (1998), Davidson et al. (2004) and Taylor et al. (2007). 262

© CAB International 2009. The Lentil: Botany, Production and Uses (eds W. Erskine et al.)

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17.2. Ascochyta Blight Ascochyta blight is prevalent throughout the world where lentils are grown and can cause yield losses of up to 70% (Gossen and Morrall, 1983). The pathogen infects leaves, stems, petioles, pods and seeds (Taylor et al., 2007). On leaves, young lesions consist of small necrotic spots that enlarge to 3–5 mm in diameter and change colour to tan or dark brown. Reddish-brown to black pycnidia form in the middle of mature lesions. On stems, lesions are brown and variable in size. In severe infections, the lesions often girdle the stem or petiole, killing the epidermal and cortical cells, leading to stem breakage. Pod infection may result in seed infection. Heavily infected seeds are shrivelled and discoloured with a whitish mycelium and pycnidia. There may be difficulties in distinguishing Ascochyta blight from anthracnose based on leaf and stem symptoms alone when both diseases occur together. Nevertheless, pycnidia in the lesions formed by Ascochyta blight may be distinguished with a handheld lens from acervuli and/or microsclerotia formed by anthracnose. Causal organism Ascochyta blight of lentil is caused by Ascochyta lentis Bond. & Vassil., which produces conidia in immersed, depressed globose pycnidia (175–300 μm in diameter). Conidia measure 13–17 μm in length and 4–6 μm in width. Ascochyta lentis is heterothallic, and requires two mating types to produce its teleomorph state Didymella lentis W.J. Kaiser, B.C. Wang and J.D. Rogers. Ascochyta lentis is morphologically indistinguishable from Ascochyta fabae. However, host specificity and compatibility in mating separate the two species (Kaiser et al., 1997). Disease cycle and epidemiology Ascochyta lentis relies on rain splash to spread conidia from infected debris on the soil surface to newly planted lentil and from plant to plant. Long distance dispersal occurs through seed-borne inoculum. Wetness periods of 24–48 h and temperatures of 10–15°C are optimum for infection (Pedersen and Morrall, 1994). Initial infection of leaves can take place within 10–12 h from germinated conidia. Macroscopic symptoms do not become evident until 7–9 days after infection. Pseudothecia of the teleomorph stage D. lentis may also develop on lentil debris and thus liberate ascospores under suitable environmental conditions at the beginning of the crop-growing season. Management Integrated disease management is partly effective in controlling Ascochyta blight of lentil in developing countries where application of fungicides is not

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practical and economical. The impact of the disease can be reduced through planting resistant varieties, crop rotation, early sowing by avoiding periods of high leaf wetness and optimum temperature, use of disease-free seed and burning of infected debris and stubble after harvest (Taylor et al., 2007). Seed-borne inoculum can be reduced by sun drying, or hot water and dry heat treatment of seeds, however, care must be taken that germination is not adversely affected (Ahmed and Beniwal, 1991). Fungicides reported to provide the best protection from seed-borne infection include benomyl, carbendazim, carbathin, iprodion and thiabendazole (Bretag, 1989). The fungicides captafol, chlorothalonil, folpet and metiram, provide good protection against foliar infection. In breeding for resistance to Ascochyta blight, knowledge of pathogenic diversity is important when choosing appropriate isolates to screen for resistance (Taylor and Ford, 2007). Since resistance to A. lentis has been found to be controlled by specific resistance genes (Ford et al., 1999; Nguyen et al., 2001), there is the likelihood that new pathotypes of A. lentis may evolve, thus deployment of resistant varieties needs to be monitored for potential resistance breakdown.

17.3. Rust Rust is a widespread foliar disease of lentil and is an economically important disease in Algeria, Bangladesh, Ethiopia, India, Italy, Morocco, Pakistan and Nepal. Early infection accompanied by conducive environmental conditions can result in complete crop failure, while yield losses in research plots have been reported to vary from 30 to 60% depending on the cultivar and disease severity (Sepulveda, 1985; Singh et al., 1986). Lentil rust is characterized by lesions on the stems and leaves that result in leaf drop and premature plant death. The pathogen can be seen as yellowish-white pycnidia and aecial cups on leaflets and on pods, either singly or in small circular groups (Plate 2A and 2B). Brown and oval to circular uredinial pustules, up to 1 mm in diameter, develop on either surface of leaflets, branches, stems and pods. The dark brown to black and elongated telia are formed later in the season mainly on branches and stems. Infected plants have a dark brown to blackish appearance, visible in affected patches of the field or in the whole field. In severe infections plants dry up, forming only small, shrivelled seeds.

Causal organism Rust is caused by the autoecious fungus Uromyces viciae-fabae (Pers.) Schroet. Spermagonia are subepidermal and globoid. Aecia and uredinia are initially subepidermal, erumpent later. Aeciospores are spheroidal, 18–26 μm in diameter, and yellowish brown in colour. Urediniospores are borne in single pediceles, mostly echinulate, with three to four germination pores

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and measure 22–28 × 19–22 μm. Telia are subepidermal in origin, then erumpent on leaves, but remain covered by the epidermis on stems for an extended period. Teliospores are borne singly on pedicels, are globose to subglobose, one-celled, measuring 25–40 × 18–26 μm, with a single germination spore. Uromyces viciae-fabae was regarded as the causal organism of rust in faba bean, vetch and lentil. However, some degree of host specialization is recognized, suggesting that U. viciae-fabae may be a species complex with different host ranges. Based on differences in host specialization, morphology of spores, and substomal vesicle, a new classification into host-specialized isolates (ex. Vicia faba L., Vicia sativa L. and Lens culinaris L.) has been suggested (Emeran et al., 2005). These groups were also clearly separated by molecular markers (Emeran et al., 2008).

Disease cycle and epidemiology The disease first occurs during the flowering and early podding stages as aecia which may further develop into secondary aecia or uredinia. The resulting aeciospores and urediniospores are the source of further disease spread during the cropping season. Uredinia usually appear a little later in the season followed by the development of telia. The fungus survives between crop seasons as teliospores and is also carried with seed as a contaminant in the form of small pieces of infected plant debris. High humidity and cloudy weather with temperatures of 20–22°C favour disease development (Agarwal et al., 1993).

Management Integrated management of rust includes control of volunteer plants and removal of infected lentil debris. It is advisable to use clean seeds without rust contamination, and to treat the seed with a suitable fungicide such as diclobutrazole. Rust can also be effectively managed by a number of foliar fungicides, although this needs to be adjusted in order to be economical. Preventive fungicide sprays of mancozeb at the early disease development stage have been recommended. The use of host plant resistance is the best means of rust management. Several rust-resistant cultivars have been released in different countries, with resistance originally identified at the International Center for Agricultural Research in the Dry Areas (ICARDA), Syria and in India (Basandrai et al., 2000; Tikoo et al., 2005). There is no clear evidence for the existence of races. The international testing of lentil genotypes differing in resistance to rust has shown that the reaction to rust of individual lines is the same. Although the rust resistance in lentils seems to be durable, it is likely to break down eventually. Little is known on the inheritance of resistance to rust. Both complete and partial resistance exist and monogenic resistance

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has been reported (Sinha and Yadav, 1989). Field resistance of lentil to rust is governed either by a single dominant gene, by two independently inherited dominant genes, by two complementary genes or by three independently inherited genes (Basandrai et al., 2005).

17.4. Botrytis Grey Mould Botrytis grey mould of lentil has been reported from Australia, Bangladesh, Canada, Colombia, Nepal, New Zealand and Pakistan. It is not uncommon for yield losses to exceed 50% and in extreme cases total crop loss occurs (Bayaa and Erskine, 1998; Davidson et al., 2004). Disease symptoms first develop on flowers and pods, and as dark green spots on the lower foliage that later become pale tan coloured. Senescent or injured plant tissues are also most prone to infection (Davidson et al., 2004). Masses of conidia are formed within the canopy and are released into the air when the canopy is disturbed. Infection of flowers and pods affects seed formation. Infected seeds may be discoloured and shrivelled, but do not always show clear symptoms. Infected seedlings from contaminated seeds are yellow and stunted, with grey fungal growth on the stem at the soil line and usually die after 1 or 2 weeks (Bayaa and Erksine, 1998; Davidson et al., 2004).

Causal organisms Botrytis grey mould is caused by Botrytis cinerea Pers. Ex Fr. and Botrytis fabae Sard (Bayaa and Erskine, 1998; Davidson and Krysinska-Kaczmarek, 2007). Botrytis cinerea is ubiquitous and non-specific with the ability to infect over 200 plant species including lucerne, beans, chickpea, field pea, safflower and sunflower (Ellis and Waller, 1974a), while B. fabae has a more restricted host range occurring mostly on Leguminosae, particularly faba bean (V. faba), common vetch (V. sativa) and lentil (Ellis and Waller, 1974b). In culture, B. cinerea and B. fabae have similar white, cottony mycelial growth that turns grey with age. Conidiophores are brown, erect and septate, 16–30 μm thick, frequently 2 mm long and branched near the cluster. Conidia are produced in clusters at the ends of branches and are hyaline, single-celled, ovoid or spherical, with a thin wall. Conidia of B. cinerea from lentil are generally smaller than those of B. fabae, but vary depending on environmental conditions (Ellis and Waller, 1974a, b). Sclerotia of B. cinerea are generally larger (2–4 × 1–3 mm) than those of B. fabae (1–1.7 mm diameter), but the size and shape is highly variable (Ellis and Waller, 1974b; Bayaa and Erskine, 1998). The teleomorphs of B. cinerea, Botryotinia fuckeliana (de Bary) Whetzel and of B. fabae, Botryotinia fabae J.Y. Lu & T.H. Wu, have not been reported on lentil (Bayaa and Erskine, 1998).

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Disease cycle and epidemiology Botrytis spp. produce masses of wind-borne conidia on infected and dead tissues under humid conditions at 15–25°C (Plate 2C), and epidemics can develop very quickly in comparison with other diseases (Davidson et al., 2004; Davidson and Krysinksa-Kaczmarek, 2007). The conidia are dry and dispersed by air currents in large numbers and may also be carried by rain droplets (Ellis and Waller, 1974a). Botrytis spp. can infect lentil at any growth stage, but severe epidemics generally develop in humid conditions after the canopy has closed at flowering and podding stages (Bayaa and Erskine, 1998; Davidson et al., 2004; Davidson and Krysinksa-Kaczmarek, 2007). Sclerotia, which are highly resistant to adverse conditions, are probably the main survival structure. They may survive for long periods if they are not buried in the soil where they decay more quickly. Mycelium can also survive saprophytically in plant debris for extended periods (Ellis and Waller, 1974a, b; Bayaa and Erskine, 1998).

Management Since Botrytis grey mould is more severe and frequent under humid conditions, avoiding dense canopies is an important component of integrated disease management in lentil (Bayaa and Erksine, 1998). Delayed sowing and reduced seeding rates as well as wide row spacings result in more open canopies during crop maturation, and thus reduce the likelihood of epidemics. Weed control and optimum fertilizer use, particularly avoiding high nitrogen levels, are also important strategies to prevent dense canopies and reduce disease severity. It is important to plant seed with less than 5% grey mould infection. Seed treatments with fungicides such as benomyl, carboxin, chlorothalonil, thiabendazole or thiram can reduce seed-borne inoculum and seedling blight (Bayaa and Erskine, 1998; Davidson et al., 2004). Destruction of infected debris through grazing, burning or burying residues reduces the carry-over of inoculum into the following season. A 3-year crop rotation allows time for the infected residue to break down (Bayaa and Erskine, 1998; Davidson et al., 2004). The foliar fungicides benomyl, boscalid, carbendazim, chlorothalonil, mancozeb, thiabendazole, tridemorph and vinclozolin have been found to be effective against Botrytis grey mould, but can be uneconomic. Several applications are required if conditions remain favourable for the disease (Bayaa and Erskine, 1998; Davidson et al., 2004). However, precaution should be taken to prevent development of fungicide resistance since Botrytis spp. are prone to evolve resistance to some synthetic, systemic fungicides (Raposo et al., 1996). Resistant germplasm of lentil has been identified in several breeding programmes and commercial cultivars have been released with better resistance to Botrytis grey mould (Bayaa and Erskine, 1998; Davidson et al., 2004).

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17.5. Anthracnose Anthracnose is a serious disease of lentil in Canada where it was discovered first in 1987. It has been subsequently reported in North Dakota, USA and Bulgaria, and there is evidence of its occurrence in Bangladesh, Brazil, Ethiopia, Morocco, Pakistan and Syria (Morrall, 1997). The first symptoms develop when the lentil crop starts to flower. Necrotic lesions can be found on the lower leaflets and many of them fall to the soil surface (Buchwaldt et al., 1996). This premature leaf drop is characteristic for anthracnose. Lesions also develop on the stems starting at the base and spreading to the top part of the plant. They are tan coloured often with a defined reddish or black border, and the deepest lesions create indentations along the stem (Plate 2E). Symptoms caused by anthracnose and Ascochyta blight are very similar, but the presence of acervuli and microsclerotia produced by the anthracnose pathogen or pycnidia produced by the Ascochyta pathogen makes it possible to distinguish the two diseases. Plants severely attacked by anthracnose disease turn brown and areas of lodged and dying plants can be seen in the field.

Causal organism Lentil anthracnose is caused by Colletotrichum truncatum (Schw.) Andrus & Moore. The pathogen produces conidia and setae in acervuli on infected plants and in culture. The conidia are single-celled, hyaline and slightly falcate, 18–30 μm long by 3–6 μm wide. The black setae are 60–120 μm long by 3.5–8.0 μm wide and protrude above the spore mass. The pathogen produces black pinhead-sized microsclerotia. These are particularly abundant at the stem base, where they can be seen with the naked eye. Microsclerotia are resting structures consisting of a couple of hundred heavily melanized cells, able to survive in the soil in periods when host plants are absent (Buchwaldt et al., 1996). A teleomorph stage of C. truncatum pathogenic on lentil has not been found in nature, but perithecia with mature asci have been induced in the laboratory by inoculating stem pieces with different isolates (Armstrong-Cho and Banniza, 2006). Each ascus contains eight singlecelled ascospores measuring 12–20 μm long by 5–8 μm wide. The sexual stage is Glomerella truncata. Disease cycle and epidemiology The pathogen survives in the field as microsclerotia on infected lentil debris that is the primary source of inoculum. The initial infection occurs when microsclerotia or conidia come in contact with lower leaves and stems of a new lentil crop. Microsclerotia are also dispersed by wind either in dust generated during harvest of infected crops or on plant debris from fields. The disease is polycyclic and spreads rapidly in the field in periods of rain. Conidia of C. truncatum are readily dispersed by rain droplets to the

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surrounding plants. The optimum temperature range for infection and production of new conidia is 20–24°C, which results in a latent period of approximately 13 days (Chongo and Bernier, 2000). Colletotrichum truncatum is a hemibiotrophic pathogen. In the biotrophic phase, a conidium forms an appressorium from which an infection peg penetrates the wall of a single epidermal plant cell. Primary hyphae grow inside the host cell for 2–3 days without killing the infected cell. In the necrotrophic phase secondary hyphae colonize the surrounding tissue both inter- and intracellularly resulting in appearance of necrotic symptoms 5–6 days after infection. Management Colletotrichum truncatum from lentil also attacks faba bean (V. fabae L.), other Vicia species, and pea (Pisum sativum L.). A 3-year crop rotation is recommended to allow adequate reduction of the soil-borne inoculum. Tillage of fields with anthracnose-infected stubble should be avoided in areas with long cold winters, such as in Canada, to take advantage of the breakdown of infectivity that occurs on the soil surface when the pathogen is exposed to extreme temperatures and repeated wetting and drying. Undoubtedly, the ability of the pathogen to survive in the soil differs under other climatic conditions. The level of seed-borne inoculum is often less than 1%, and the significance of seed-borne inoculum remains to be determined. Several foliar fungicides, such as chlorothalonil and several strobilurin products, efficiently control anthracnose when applied preventatively; some chemicals in the latter group also have a slightly systemic effect. The optimum time of fungicide application in Canada is between the 8 and 12 node stage and approximately 1 week prior to flowering (Chongo et al., 1999). An above normal and premature leaf drop at this time is the best indication that anthracnose is likely to become a problem. It is important to apply a fungicide before the canopy becomes too dense in order to obtain the best possible coverage of the lower portion of the stems. A second application 10–14 days later may be necessary under high disease pressure and frequent rainfall. Two morphologically identical races are present in Canada (Buchwaldt et al., 2004). Isolates of race Ct1 are unable to infect lines such as ‘Indianhead’, PI 320937, PI 345629 and PI 468901 (United States Department of Agriculture (USDA) Agriculture Research Service (ARS), Pullman, Washington). Single major genes, either dominant or recessive, conferring resistance to race Ct1 have been utilized in Canada to develop cultivars with an improved level of anthracnose resistance under field conditions (Buchwaldt et al., 2004). So far, sources of resistance to race Ct0 have not been found in cultivated lentil, but are available in wild Lens species (Tullu et al., 2006).

17.6. Stemphylium Blight Stemphylium blight of lentil is the most devastating disease in Bangladesh, eastern Nepal and north-eastern India, where yield losses above 80% have

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been recorded (Bakr and Ahmed, 1992; Sinha and Singh, 1993). Reports on the disease have also been published from Canada, Egypt, Hungary, Syria and the USA (Bayaa and Erskine, 1998; Morrall et al., 2006). Initial symptoms often appear in the upper canopy in the form of small, light-beige lesions that enlarge and coalesce (Plate 2D). Leaves, pedicels, flowers and entire branches can become necrotic resulting in a characteristic blighted appearance of lentil plants. Severe infection can significantly reduce plant biomass, lower seed yield, decrease seed size and result in seed staining and lower germination rates. Causal organism Stemphylium botryosum Wallr. produces light-brown to black conidia with a length-to-width ratio of 1:1.5. Conidia (dictyospores) are partitioned by a median transverse septum, and secondary trans- and longi-septa and range in size from 24 × 14 μm to 40 × 26 μm. The fungus has been reported from a wide range of host species including asparagus, canola, lucerne, cotton, tomato, garlic, mango, pear, onion, clover and lentil. It sporulates profusely on host tissue, but its pseudothecia have only been observed in culture. The teleomorph stage is the ascomycete Pleospora tarda E.G. Simmons. Septate ascospores of 40 × 17 μm are formed in subcylindrical asci measuring approximately 200 × 40 μm that develop in pseudothecia (Bayaa and Erskine, 1998). Disease cycle and epidemiology Airborne conidia of S. botryosum are commonly found in the environment and are formed on conidiophores that produce successive generations of spores. They germinate with several germ tubes that penetrate primarily through stomata, and invade plant tissues including seed. The fungus produces the phytotoxin stemphol, which has been implicated in lesion formation on various hosts (Solfrizzo et al., 1994). Conidial germination and infection of lentil can occur at temperatures from 5 to above 30°C in the presence of free water. Optimal conditions for Stemphylium blight epidemics are characterized by high relative humidity, cloudy days and moderate to warm temperatures (Sinha and Singh, 1993). While Stemphylium blight symptoms can be observed early in the growing season in Bangladesh and India, the disease appears during the last third of the growing season in Canada. Infected lentil debris and alternate hosts as well as saprophytic growth enable S. botryosum to survive between crops. Management In Bangladesh and India, Stemphylium blight is managed through late seeding of lentil, fungicide applications and the use of resistant cultivars.

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Three applications of iprodione, propineb, mancozeb or sulfur, sprayed at 7-day intervals once symptoms were observed, significantly reduced disease severity and increased yield by 23–40% (Bakr and Ahmed, 1992). The resistant cultivars ‘Barimasur-4’, ‘Barimasur-5’ and ‘Barimasur-6’ were developed in Bangladesh in cooperation between ICARDA and the Bangladesh Agricultural Research Institute (BARI).

17.7. Powdery Mildew Powdery mildew has been reported from many countries such as Cyprus, Ethiopia, India, Siberia, Sudan, Syria, Tanzania and the former USSR. In India and Sudan, the disease occurs in severe forms almost every year on susceptible varieties. It becomes more severe in the Indian province of Rajasthan, especially under dry weather conditions. In North America, powdery mildew is often observed after lentil starts flowering in the field, whereas it occurs at any growth stages under greenhouse conditions. The disease poses a serious problem on breeding materials in plastic- or glasshouses in both India and Syria, and in India it is also recorded in off-season nurseries in Trans Himalayan regions, such as Lahaul Spiti and Sangla, but it is rarely seen in the field during the cropping season. Symptoms are observed on the upper surface of older leaves (Beniwal et al., 1993). A fine powdery, white growth of conidia and mycelium initiates as small spots and spreads rapidly to cover the entire surface of leaves (Plate 2F), stems and pods. Later, the leaflets become dry and curled, and are shed prematurely, causing considerable reduction in yield and seed quality. The seeds from infected plants remain small and shrivelled.

Causal organisms Powdery mildew of lentil is caused by the ectoparasites Erysiphe pisi DC. and Erysiphe polygoni DC. and the endoparasite Leveillula taurica (Lév.) Arnaud. The anamorph stage of E. polygoni, Oidium sp., has been frequently reported, and the anamorph stage of L. taurica, Oidiopsis taurica Salmon, has been reported from the former USSR and Jordan. Recent evidence showed that Erysiphe trifolii also infects lentil (Attanayake et al., 2008).

Disease cycle and epidemiology The anamorph stage is responsible for spread of the disease. The teleomorph stage has been reported to occur in India and Sudan (Chitale et al., 1971). Moderately high temperatures and moderate relative humidity favour disease development.

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Management Many lentil genotypes are reported resistant to powdery mildew (Tikoo et al., 2005), and should be planted whenever possible. Foliar sprays with fungicides benomyl, tridemorph, aqueous sulfur, karathane (dinocap), calixin or sulfex (ferrous bisulfide) as well as certain insecticides (Quinalphos, Tnazophos, Phoxim) applied at 10–15 day intervals are effective in suppressing powdery mildew growth (Beniwal et al., 1993).

17.8. Fusarium Wilt Fusarium wilt of lentil is an important soil-borne disease, and causes significant yield loss under dry and warm conditions. The disease occurs in most lentil production regions, and has been reported to occur in at least 26 countries (Agrawal and Prasad, 1997; Bayaa and Erskine, 1998). Fusarium wilt of lentil can be observed at the seedling and reproductive stages. It usually occurs during the reproductive stages from flowering to pod filling, causing yellowing, leaf curling and stunted growth. Infected plants show reduced root development, sometimes with yellowish-brown discoloration of vascular tissue and poorly developed nodules (Beniwal et al., 1993).

Causal organism The fungal pathogen Fusarium oxysporum Schlecht. :Fr. f. sp. lentis Vasudeva and Srinivasan causes Fusarium wilt disease of lentil. The fungus produces three kinds of asexual spores: microconidia, macroconidia and chlamydospores. Microconidia are single celled, kidney shaped, ellipsoid to ovoid, cylindrical, oblong or slightly curved, and hyaline, often agglutinated into false heads. Macroconidia are 1–5 septate, nearly straight to fusiform, falcate, slender and thin-walled. Terminal or intercalary chlamydospores are formed on mycelium. They are generally single celled, rarely two-celled, spherical to pyriform, smooth and hyaline. The teleomorph state of the fungus has not been observed.

Disease cycle and epidemiology Fusarium wilt is a monocyclic disease. The initial inoculum level is very important for determining the incidence and severity of the disease. The pathogen survives as chlamydospores and dormant mycelium in infected plant debris. The fungus can also be seed-borne either as systemic infection inside the seeds or as a contaminant on the seeds. Seed-borne inoculum is an important source for the introduction of the disease into new production areas. Warm soil temperature 20–30°C and dry soil conditions (25% water holding capacity) are the two most important environmental factors favouring

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development of the disease (Khare, 1981). Other environmental conditions such as soil type, aeration, pH and fertility, as well as soil microflora may also affect the disease development. Soil-borne lentil-infecting nematodes, such as Ditylenchus spp., Meloidogyne spp. and Pratylenchus spp., interact synergistically with F. oxysporum f. sp. lentis to increase disease severity (De et al., 2001).

Management Proper diagnosis is the first step in managing Fusarium wilt of lentil. A recent history of Fusarium wilt increases the likelihood of its reoccurrence. Reduced root systems with discoloration, but without external fungal growth on stunted plants suggest Fusarium wilt infestation. Definitive identification of the pathogen requires pathogenicity tests on susceptible lentil plants. Planting of resistant cultivars is the most economical means for its management. Resistance sources have been identified and incorporated into lentil cultivars and resistant cultivars are available in several countries (Bayaa and Erskine, 1998; Tikoo et al., 2005; Stoilova and Chavdarov, 2006). Some high-yielding lentil lines have been reported to be resistant to multiple diseases including rust, Ascochyta blight and Fusarium wilt (Bayaa and Erskine, 1998). However, resistance alone is not sufficient for satisfactory management of the disease. So a number of cultural practices should be used in conjunction in managing the disease. Seeds for planting should be free of infection and contamination, particularly when expanding lentil production into new areas. If disease-free and clean seeds are not available, fungicide treatments should be implemented. Seed treatment with carboxin and thiram, thiram, pentachloronitrobenzene, carbendazim, benomyl, or with boric acid plus KMnO4 can reduce seed infection. Direct application of fungicides to the soil after planting for the control of Fusarium wilt is not economical because of the high cost and technical difficulty during the growing season. Another management option is to select early maturing varieties or adjust planting time, so that plants can escape hot weather conditions during the vulnerable growing stages. However, the most suitable planting date varies depending on the climatic conditions of the production regions. The principle is to reduce the overlap of susceptible growth stages with hot weather conditions. Cultural practices like applying manure or composts that enhance populations of general microflora or supplementation with selected antagonistic biocontrol agents may be feasible on subsistence or small farms.

17.9. Sclerotinia Stem Rot Sclerotinia stem rot has a worldwide distribution and occurs on more than 400 plant species in 75 families (Boland and Hall, 1994). Economic loss can occur in lush lentil canopies under wet conditions (Akem et al., 2006). Infected plants exhibit bleached lesions on stems, leaves, pedicels and pods,

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which are sometimes covered by a characteristic cottony white mycelium occasionally harbouring dark sclerotia. Stem infection can cause wilting of plants (Bolten et al., 2006).

Causal organism The disease is caused by Sclerotinia sclerotiorum (Lib.) de Bary. The fungus produces black, rounded to elongate sclerotia of up to 1 cm in length. Sclerotia can germinate directly by mycelium (myceliogenically) and can grow rapidly over host tissue and ramify intra- and intercellularly. No spores are formed, though globose spermatia of unknown function extruded through phialides at the tips of microconidiophores which are often present in the mycelium. Sclerotia can also germinate carpogenically to produce one to several light- to dark-brown apothecia. These are generally 0.5–2 cm in diameter, funnel shaped to discoid with a layer of asci (the hymenium) on the upper surface. Eight elliptical to ovoid, hyaline, unicellular ascospores develop within each ascus, and are forcibly ejected from asci (Clarkson et al., 2003; Bolten et al., 2006).

Disease cycle and epidemiology The disease is promoted by high plant density, excessive vegetative growth and high precipitation in the last third of the lentil-growing season (Akem et al., 2006). Infection on lentil is initiated through ascospores released from carpogenically germinating sclerotia, as well as through myceliogenically germinated sclerotia that have overwintered on or near the soil surface. Specific soil temperature and moisture levels are required to trigger carpogenic germination (Morrall, 1977). Senescent flower petals are the sites of infection by ascospores providing them with nutrients required for successful invasion of the host tissue. Once abscised and in contact with healthy tissue, the infected senescent petals are sources of inoculum for leaves and stems. Evidence has also emerged on the ability of germinating ascospores to directly invade healthy, green lentil tissue. Plants become more susceptible to infection as they mature. Contact with the soil by lodging plants and between healthy and infected plant parts in dense canopies also result in infection. Invasion of the tissue is facilitated by the production of cell-wall degrading enzymes and oxalic acid, which cause yellowing and development of bleached lesions. Sclerotia formed on infected lentil tissue are returned to the soil upon harvest or threshed out with the seed (Bolten et al., 2006).

Management Crop rotation has limited efficacy in controlling Sclerotinia stem rot because of the longevity of sclerotia and the pathogen’s wide host range. High levels

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of resistance to the disease have not been found in lentil, but some cultivars consistently perform better. Whereas early fungicide applications can prevent or reduce flower petal infection, late season control through fungicides is ineffective because the dense canopy prevents penetration of the fungicide to the lower plant canopy. Fungicide applications may not always control the disease and may not be economical (Bolten et al., 2006).

17.10. Nematode Diseases Nematode diseases of lentil are commonly observed worldwide and are often important diseases in India, Syria, Turkey and in African countries. The stem nematode is common in the temperate regions of the world comprising Europe and the Mediterranean region, North and South America, northern and southern Africa, Asia and Oceania (Agrawal and Prasad, 1997). Common above-ground symptoms of nematode diseases are similar to those associated with plants with an impaired root system, because the nematodes usually feed on and damage roots. Symptoms include stunting, chlorosis, yellowing, wilting and plant death, which often appear in patches in the field. However, these symptoms are not specific for nematode diseases. Therefore, definitive diagnoses require examination of root systems and the attached soil. The characteristic feature of root-knot nematode is the presence of small galls on roots (Beniwal et al., 1993). Some lateral rootlets may develop out of the galls. The galls are similar to nitrogen-fixing nodules in size and shape, but galls are easily differentiated from nodules by lack of colour and swelling of the root diameter. The most characteristic features of infection by cyst nematodes are the presence in roots of lemon-shaped cysts (i.e. leathery bodies of adult females) (Agrawal and Prasad, 1997). The main symptoms and damage caused by root-lesion nematodes are lesions or discoloration of roots and lack of branching along the main roots (Beniwal et al., 1993). Stem nematodes cause brownish necrotic lesions on the bases of stems, stunted and distorted leaves and stems. Lentil is very susceptible to stem nematodes at the seedling stage.

Causal organisms Many plant parasitic nematodes are associated with lentil. The economically important nematodes of lentil include: root-knot nematodes (Meloidogyne incognita (Kofoid & White) Chitwood and Meloidogyne javanica (Treub) Chitwood); cyst nematode (Heterodera ciceri Vovlas, Greco & Di Vito); rootlesion nematodes (Pratylenchus thornei Sher & Allen, Pratylenchus penetrans (Cobb) Chitwood and Oteifa and Pratylenchus mediterraneus Corbett); and stem nematode (Ditylenchus dipsaci (Kühn) Filipjev).

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Disease cycle and epidemiology Plant parasitic nematodes have four moults of juvenile stages and then proceed to adult egg-laying females. Eggs hatch and produce second-stage juveniles that seek and infect host tissue. Egg fertilization is not necessary for many species. The egg and juvenile stages are resistant to adverse conditions and enable nematodes to survive from season to season. Some species take 1 year to complete a single life cycle (egg to egg), while some others can complete several cycles during one growing season. Females either deposit eggs into the soil around the infected roots or they are encased in the female body (cyst). Cyst nematodes can survive for long periods of time without a host. These are more prone than other plant parasitic nematodes to unintentional long-distance transport because their resistant cyst stage can tolerate long periods of desiccation and adhere to soil particles on vehicles and clothing. Stem nematodes at the fourth juvenile stage invade seedlings and damage the growing tips of leaves and stems. After entering the host plants, they mature into adults, feed and lay eggs. If the soil dries up in late spring or summer, the fourth-stage juveniles can enter a state of anhydrobiosis in either the plant or soil and can survive high temperature and desiccation. The host range of the cyst nematode is limited to Leguminosae, mainly chickpea, lentil, pea and grass pea, while other lentil nematodes generally have wider host ranges. Root-knot nematodes infect many vegetable, horticultural, cereal and legume crops. The host range of root-lesion nematodes includes many cereal, legume and oilseed species. Stem nematode can attack over 450 plant species including many weed species. Races are reported in stem nematodes, and some races have limited host ranges. Nematodes are notorious for interacting with other soil-borne fungal pathogens additively or synergistically (Tiyagi et al., 1988; Anver et al., 1991).

Management Crop rotation is a general practice in managing nematode diseases, and it is particularly effective in controlling cyst nematodes because of their narrow host range. Even with the nematodes that have wide host ranges, some crops are less favourable than others. In general, rotation with cereal and Brassica species are effective in managing root-knot nematodes. Another effective measure is to plant resistant or tolerant varieties whenever possible, which sometimes can significantly reduce the nematode population. Where lentil is produced as a winter crop, solarization in the summer for 6–8 weeks can also effectively reduce the nematode population (Linke et al., 1991). Since many weeds are alternate host of the nematodes, good weed control is another effective measure in reducing nematode populations. Seed treatments with nematicides and soil amendments with organic matter can reduce disease severity as well (Gaur and Mishra, 1990).

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Table 17.1.

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List of bacterial and other fungal and nematode diseases of lentil.

Disease name

Pathogen

References

Alternaria blight

Alternaria alternata (Fries) Keissler

Aphanomyces root rot

Aphanomyces euteiches C. Drechsler Xanthomonas sp. Pseudomonas radiciperda Fusarium solani (Mart.) Sacc.

Gupta and Das (1964); Kaiser (1992) Lamari and Bernier (1985)

Bacterial leaf spot Bacterial root rot Black root rot Black streak root rot Cercospora leaf spot Collar rot Cylindrosporium leaf spot and stem canker Downy mildew Dry root rot Helminthosporium leaf spot Leaf yellowing Phoma leaf spot Pythium root and seedling rot Reniform nematode Wet root rot

aPathogenicity

Thielaviopsis basicola (Berk. & Broome) Ferraris Cercospora lensii Sharma et al. Sclerotium rolfsii Sacc. Cylindrosporium sp.

Agrawal and Prasad (1997) Agrawal and Prasad (1997) Karahan and Katrcoglu (1993) Bowden et al. (1985) Sharma et al. (1978) Beniwal et al. (1993); Khare (1981) Bellar and Kebabeh (1983)

Peronospora lentis Gäumann Macrophomina phaseolina (Tassi) Goidanich Helminthosporium sp.a

Mittal (1997) Kaiser (1992); Vishunavat and Shukla (1979) Karahan and Katrcoglu (1993) Cladosporium herbarum (Pers.) Kaiser (1992); Karahan and Link Katrcoglu (1993) Phoma medicaginis Malbr. & Roum. Kaiser (1992) Pythium ultimum Trow, Pythium spp. Paulitz et al. (2004)

Rotylenchulus reniformis Linford & Oliveira Rhizoctonia solani Kühn, teleomorph: Thanatephorus cucumeris (Frank) Donk

Anver et al. (1991); Gaur and Mishra (1990) Kaiser (1992); Karahan and Katrcoglu (1993)

not conﬁrmed.

17.11. Other Diseases Due to limitation of space, a number of bacterial, fungal and nematode diseases of lentil not covered in details in this chapter are listed in Table 17.1, some of which might be quite important locally. There are others for which very little information is available. Reporting and more detailed studies on those diseases are encouraged.

References Agarwal, S.C., Singh, K. and Lal, S.S. (1993) Plant protection of lentil in India. In: Erskine, W. and Saxena, M.C. (eds) Lentil in South Asia. International Center for Agricultural Research in the Dry Areas (ICARDA), Aleppo, Syria, pp. 147–165.

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W. Chen et al. Agrawal, S.C. and Prasad, K.V.V. (1997) Diseases of Lentil. Science Publisher Inc., Enfield, New Hampshire. Ahmed, S. and Beniwal, S.P.S. (1991) Ascochyta blight of lentil and its control in Ethiopia. Tropical Pest Management 37, 368–373. Akem, C., Bellar, M. and Bayaa, B. (2006) Comparative growth and pathogenicity of geographical isolates of Sclerotinia sclerotiorum on lentil genotypes. Plant Pathology Journal 5, 67–71. Anver, S., Tiyagi, S.A., Yadav, A. and Alam, M.M. (1991) Interactions between Rotylenchulus reniformis and Macrophomina phaseolina on lentil. Pakistan Journal of Nematology 9, 127–130. Armstrong-Cho, C.L. and Banniza, S. (2006) Glomerella truncate sp. Nov., the teleomorph of Colletotrichum truncatum. Mycological Research 110, 951–956. Attanayake, R.P., Glawe, D., McPhee, K., Dugan, F. and Chen, W. (2008) Taxonomic complexity of powdery mildew pathogens found on lentil and pea in the US Pacific Northwest. Phytopathology 98, S15. Bakr, M.A. and Ahmed, F. (1992) Development of Stemphylium blight of lentil and its chemical control. Bangladesh Journal of Plant Pathology 8, 39–40. Basandrai, D., Basandrai, A.K. and Vipan, K. (2000) Evaluation of lentil (Lens culinaris) germplasm against rust and Ascochyta blight. Indian Journal of Agricultural Sciences 70, 804–805. Basandrai, D., Basandrai, A.K., Thakur, H.L. and Thakur, S.K. (2005) Inheritance of field resistance against lentil rust (Uromyces viciae fabae) in lentil (Lens culinaris L.). In: Proceedings of International Food Legumes Research Conference IV, Indian Agricultural Research Institute (IARI), New Delhi, India, 18–22 October 2005. IARI, New Delhi, India, p. 336. Bayaa, B. and Erskine, W. (1998) Diseases of lentils. In: Allen, D.J. and Lenné, J.M. (eds) The Pathology of Food and Pasture Legumes. CAB International, Wallingford, Oxon, UK, pp. 423–471. Bellar, M. and Kebabeh, S. (1983) A list of diseases and injuries and parasitic weeds of lentils in Syria, Survey 1979–1980. LENS Newsletter 10, 30–31. Beniwal, S.P.S., Bayaa, B., Weigand, S., Makkouk, K. and Saxena, M.C. (1993) Field Guide to Lentil Diseases and Insect Pests. International Center for Agricultural Research in the Dry Areas (ICARDA), Aleppo, Syria. Boland, G.J. and Hall, R. (1994) Index of plant hosts of Sclerotinia sclerotiorum. Canadian Journal of Plant Pathology 16, 93–108. Bolten, M.D., Thomma, B.P.H.J. and Nelson, B.D. (2006) Sclerotinia sclerotiorum (Lib.) de Bary: biology and molecular traits of a cosmopolitan pathogen. Molecular Plant Pathology 7, 1–16. Bowden, R.L., Wiese, M.V., Crock, J.E. and Auld, D.L. (1985) Root rot of chickpeas and lentils caused by Thielaviopsis basicola. Plant Disease 69, 1089–1091. Bretag, T.W. (1989) Evaluation of fungicides for the control of ascochyta blight in lentils. Tests of agrochemicals and cultivars. Annals of Applied Biology (Suppl.), 44–45. Buchwaldt, L., Morrall, R.A.A., Chongo, G. and Bernier, C.C. (1996) Windborne dispersal of Colletotrichum truncatum and survival in infested lentil debris. Phytopathology 86, 1193–1198. Buchwaldt, L., Anderson, K.L., Morrall, R.A.A., Gossen, B.D. and Bernier, C.C. (2004) Identification of lentil germplasm resistant to Colletotrichum truncatum and characterization of two pathogen races. Phytopathology 94, 236–243. Chitale, K., Tyagi, R.N.S. and Bhatnagar, L.G. (1971) Perfect stage of Erysiphe polygoni from India. Indian Phytopathology 34, 540–541.

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Chongo, G. and Bernier, C.C. (2000) Effects of host, inoculum concentration, wetness duration, growth stage and temperature on anthracnose in lentil. Plant Disease 84, 544–548. Chongo, G., Bernier, C.C. and Buchwaldt, L. (1999) Control of anthracnose in lentil using partial resistance and fungicide application. Canadian Journal of Plant Pathology 21, 16–22. Clarkson, J.P., Staveley, J., Phelps, K., Young, C.S. and Whipps, J.M. (2003) Ascospore release and survival in Sclerotinia sclerotiorum. Mycological Research 107, 213–222. Davidson, J.A. and Krysinska-Kaczmarek, K. (2007) Effects of inoculum concentration, temperature, plant age and interrupted wetness on infection of lentil (Lens culinaris) by Botrytis spp. conidia. Australasian Plant Pathology 36, 389–396. Davidson, J.A., Pande. S., Bretag, T.W., Lindbeck, K.D. and Krishna-Kishore, G. (2004) Biology and management of Botrytis spp. in legume crops. In: Elad, Y., Williamson, B., Tudzynski, P. and Delen, N. (eds) Botrytis: Biology, Pathology and Control. Kluwer Academic Publishers, Dordrecht, The Netherlands, pp. 295–318. De, R.K., Ali, S.S. and Dwivedi, R.P. (2001) Effect of interaction between Fusarium oxysporum f. sp. lentis and Meloidogyne javanica on lentil. Indian Journal of Pulses Research 14, 71–73. Ellis, M.B. and Waller, J.M. (1974a) Sclerotinia fuckeliana (conidial state: Botrytis cinerea). Commonwealth Mycological Institute (CMI) Descriptions of Pathogenic Fungi and Bacteria 431. Ellis, M.B. and Waller, J.M. (1974b) Botrytis fabae. Commonwealth Mycological Institute (CMI) Descriptions of Pathogenic Fungi and Bacteria 432. Emeran, A.A., Sillero, J.C., Niks, R.E. and Rubiales, D. (2005) Morphology of infection structures helps to distinguish among rust fungi infecting leguminous crops. Plant Disease 89, 17–22. Emeran, A.A., Román, B., Sillero, J.C., Satovic, Z. and Rubiales, D. (2008) Genetic variation among and within Uromyces species infecting legumes. Journal of Phytopathology 156, 419–424. Ford, R., Pang, E.C.K. and Taylor, P.W.J. (1999) Genetics of resistance to ascochyta blight (Ascochyta lentis) of lentil and identification of closely linked molecular markers. Theoretical and Applied Genetics 98, 93–98. Gaur, H.S. and Mishra, S.D. (1990) Integrated control of nematodes in lentil with aldicarb, neem cake and seed treatment with thimet and its residual effect on the subsequent mung crop. Indian Journal of Entomology 51, 283–287. Gossen, B.D. and Morrall, R.A.A. (1983) Effect of ascochyta blight on seed yield and quality of lentils. Canadian Journal of Plant Pathology 5, 168–173. Gupta, P.K. and Das, C.R. (1964) Alternaria leaf blight of lentil. Current Science 33, 562–563. Kaiser, W.J. (1992) Fungi associated with the seeds of commercial lentils from the US Pacific Northwest. Plant Disease 76, 605–610. Kaiser, W.J., Wang, B.C. and Rogers, J.D. (1997) Ascochyta fabae and A. lentis: host specificity, teleomorphs (Didymella), hybrid analysis and taxonomic status. Plant Disease 81, 809–816. Karahan, A. and Katrcoglu, Y.Z. (1993) Occurrence and distribution of fungal diseases on lentil in Ankara Province. Journal of Turkish Phytopathology 22, 27–33. Khare, M.N. (1981) Diseases of lentils. In: Webb, C. and Hawtin, G. (eds) Lentils. Commonwealth Agricultural Bureaux, Slough, UK, pp. 163–172. Lamari, L. and Bernier, C.C. (1985) Etiology of seedling blight and root rot of fababean (Vicia faba) in Manitoba. Canadian Journal of Plant Pathology 7, 139–145.

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W. Chen et al. Linke, K.H., Saxena, M.C., Sauerborn, J. and Masri, H. (1991) Effect of Soil Solarization on the Yield of Food Legumes and on Pest Control. Food and Agriculture Organization (FAO) Plant Production and Protection Paper 109. FAO, Rome, pp. 139–154. Mittal, R.K. (1997) Effect of sowing dates and disease development in lentil as sole and mixed crop with wheat. Journal of Mycology and Plant Pathology 27, 203–209. Morrall, R.A.A. (1977) A preliminary study on the influence of water potential on sclerotium germination in Sclerotinia sclerotiorum. Canadian Journal of Botany 55, 8–11. Morrall, R.A.A. (1997) Evolution of lentil diseases over 25 years in western Canada. Canadian Journal of Plant Pathology 19, 197–207. Morrall, R.A.A., Carriere, B., Pearse, C., Schmeling, D. and Thomson, L. (2006) Seedborne pathogens of lentil in Saskatchewan in 2005. Canadian Plant Disease Survey 86, 104–106. Nguyen, T.T., Taylor, P.W.J., Brouwer, J.B., Pang, E.C.K. and Ford, R. (2001) A novel source of resistance in lentil (Lens culinaris ssp. culinaris) to ascochyta blight caused by Ascochyta lentis. Australasian Plant Pathology 30, 211–215. Paulitz, T.C., Dugan, F., Chen, W. and Grünwald, N.J. (2004) First Report of Pythium irregulare on lentils in the United States. Plant Disease 88, 310. Pedersen, E.A. and Morrall, R.A.A. (1994) Effect of cultivar, leaf wetness duration, temperature and growth stage on infection and development of ascochyta blight of lentil. Phytopathology 84, 1024–1030. Raposo, R., Delcan, J., Gomez, V. and Melgarejo, P. (1996) Distribution and fitness of isolates of Botrytis cinerea with multiple fungicide resistance in Spanish greenhouses. Plant Pathology 45, 497–505. Sepulveda, R.P. (1985) Effect of rust, caused by Uromyces fabae (Pers.) de Bary, on the yield of lentils. Agricultura Tecnica 45, 335–339. Sharma, M.D., Mishra, R.P. and Jain, A.C. (1978) Cercospora lensii sp. nov.: a new species of Cercospora on lentil. Current Science 47, 774–775. Singh, K., Jhooty, J.S. and Cheema, H.S. (1986) Assessment of losses in lentil yield due to rust caused by Uromyces fabae. LENS Newsletter 13, 28. Sinha, J.N. and Singh, A.P. (1993) Effect of environment on the development and spread of Stemphylium blight of lentil. Indian Phytopathology 46, 252–253. Sinha, R.P. and Yadav, B.P. (1989) Inheritance of resistance to rust in lentil. LENS Newsletter 16, 41. Solfrizzo, M., Strange, R.N., Sabia, C. and Visconti, A. (1994) Production of a toxin stemphol by Stemphylium species. Natural Toxins 2, 14–18. Stoilova, T. and Chavdarov, P. (2006) Evaluation of lentil germplasm for disease resistance to Fusarium wilt (Fusarium oxysporum f. sp. lentis). Journal of Central European Agriculture 7, 121–126. Taylor, P.W.J. and Ford, R. (2007) Diagnostics, genetic diversity and pathogenic variation of cool season food and feed legumes. European Journal of Plant Pathology 119, 127–133. Taylor, P.W.J., Lindbeck, K., Chen, W. and Ford, R. (2007) Lentil diseases. In: Yadav, S.S., McNeil, D.L. and Stevenson, P.C. (eds) Lentil: an Ancient Crop for Modern Times. Springer, Dordrecht, The Netherlands, pp. 291–313. Tikoo, J.L., Sharma, B., Mishra, S.K. and Dikshit, H.K. (2005) Lentil (Lens culinaris) in India: present status and future perspectives. Indian Journal of Agricultural Sciences 75, 539–562. Tiyagi, S.A., Zaidi, S.B.I. and Alam, M.M. (1988) Interaction between Meloidogyne javanica and Macrophomina phaseolina on lentil. Nematologia Mediterranea 16, 221–222.

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18

Insect Pests and their Management Ram Ujagir1 and Oonagh M. Byrne2

1G.B. 2The

Pant University of Agriculture and Technology, Pantnagar, India; University of Western Australia, Crawley, Western Australia, Australia

18.1. Introduction Lentil (Lens culinaris Medik. subsp. culinaris) is mainly cultivated in South Asia, West Asia, North Africa, the Nile valley region, North America, South America, Eastern Europe and Australia. The lentil crop is attacked by a wide range of insect pest species, only some of which are economically important, requiring control measures: these include aphids, cutworms, pod borers, thrips, leaf and seed weevils. Other pests infesting lentil, but not causing major economic damage, are root aphids, leaf miner, lygus bug, lucerne weevil, semilooper and armyworms. At the initial stage of crop growth, wire worms, lucerne flea and cutworms and Agrotis ipsilon cause the most damage to lentil. During the vegetative stage foliage feeders such as bud weevil, grasshopper, Sitona crinitus, chrysomelids, cicadellids, Spodoptera exigua, Autographa gamma, Chromatomyia horticola, bugs, aphids and leaf miners impact most. Thrips and aphids cause most damage at the reproductive stage of crop growth. At the podding stage grasshoppers and the pod borers, Helicoverpa armigera and Etiella, cause most damage. Bruchus lentis and Bruchus ervi infest the lentil crop at podding, causing seed losses in storage. Callosobruchus maculatus and Callosobruchus chinensis also attack lentil seed in storage. Viruses transmitted by insect vectors such as aphids can impact on lentil production. Insect damage can lead to subsequent fungal and bacterial diseases (Hariri, 1981).

18.2. Pest Complex Infesting Lentil Crop The pest spectrum of lentil is wide with the crop being attacked by a large number of insect pests. Bhatnagar and Sehgal (1989) reported about 20 insect 282

© CAB International 2009. The Lentil: Botany, Production and Uses (eds W. Erskine et al.)

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species infesting lentil in the northern Terai region of India. Among them aphids, leaf miners and semiloopers attack the lentil crop at vegetative and flowering stages, while pod-borer infestation occurs at late flowering and post-reproductive stages. About 20 insect pests were found to be associated with the crop in Ethiopia (Ali and Habtewold, 1993); most important among these are the pea aphid, African bollworm and bean bruchid. The occurrence and status of different insect pests associated with lentil has been reported to vary over geographical regions. A list of insects known to be associated with lentil globally is given in Table 18.1. One of the most important groups of insect pests of the crop are the aphids, Aphis craccivora and Acrythosiphon pisum particularly in dry seasons in West Asia and North Africa (Thakur et al., 1984; Erskine et al., 1994; Singh and Saxena, 1994). Sehgal and Ujagir (1980) reported the leaf miner, C. horticola, as a major insect pest causing direct damage to the lentil crop through foliage feeding. Hammad (1978), Singh and Dhooria (1971), Erskine et al. (1994) and Singh and Sharma (2001) reported that the pod borer Etiella zinckenella Treische, was a major pest of lentils in the Indian Punjab and also in West Asia, and North and East Africa. Erskine et al. (1994) observed that the species Apion ervi feeds on lentil. Grasshoppers, in particular Melanoplus bivittatus (Say), are reported as an economic problem in lentil crops at flowering and early pod stages in Canada (Olfert and Slinkard, 1999). Over the last decade in south-eastern Anatolia, Turkey, lygus bugs, Exolygus (= Lygus) pratensis, have come to be considered the most important insect seed pest in red lentil because feeding adults damage the seed, causing chalky spot syndrome (Özberk et al., 2006). In the Terai region of Nepal, Pandey et al. (2000) reported A. ipsilon, A. pisum, H. armigera, C. chinensis and C. maculatus as major and Phyllotreta sinuate, Athalia lugens proxima (Klug) and Adonia variegata as minor pests of lentil. Storage pests are important in all production areas and infestations can result in complete loss of the crop (Singh and Saxena, 1994). The principal storage weevils of lentil are C. maculatus and C. chinensis species. Bruchus lentis is the most widespread and damaging of the seed-feeding bruchid pests of lentil (Erskine et al., 1994).

18.3. Estimation of Losses Caused by the Insect Pest Complex Perez-Andueza et al. (2004) reported aphids (A. craccivora and A. pisum), B. lentis, thrips (Thrips tabaci and Thrips angusticeps) and leaf weevil (Sitona lineatus) as key pests of lentil in Spain. The average damage caused by insect pests to lentil during a 2-year study ranged from 24 to 59% (PerezAndueza et al., 2004). Leaf damage by Sitona weevil was assessed in former Czechoslovakia under laboratory conditions by Sedivy (1972) who reported 1–75% leaf damage. Sitona weevil, S. crinitus Herbst, is the principal field pest of lentil in West Asia and North Africa (Erskine et al., 1994; Singh and Saxena, 1994).

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Table 18.1.

Insect pests associated with the lentil crop.

Order and family

Scientiﬁc name

Orthoptera

Melanoplus bivittatus (Say) Melanoplus sanguinipes (Fabr.) Melanoplus packardii (Scudder) Camnula pellucida (Scudder) Bemisia tabaci (Gennadius)

Nature of damage/ plant parts attacked

Country/continent

References

Minor

Asia, North Africa, Canada

Olfert and Slinkard (1999)

Suck the sap from foliage and ﬂowers Minor Suck the sap from tender parts of plant Vector of viral diseases

Egypt

Hammad (1978)

Europe, Asia, America, Africa Worldwide

Suck the sap from tender parts of plant

America, Europe, Asia, Africa

Vector of viral diseases

Worldwide

Suck the sap from tender parts of plant Suck the sap from tender parts of plant Vector of viral diseases

North-west Paciﬁc region India

Hariri (1981), Mokiyar (1985), Bhatnagar and Sehgal (1989) Makkouk and Kumari (2001), Jones and Coutts (2008) Tahhan and Hariri (1982), Thakur et al. (1984), Bhatnagar and Sehgal (1989) Makkouk and Kumari (2001), Jones and Coutts (2008) Halfhill (1982)

Root damage

Syria

Miridae

Smynthurodes betae (Westwood) Lygus elisus (Vand) Lygus hesperus (Knight) Exolygus pratensis (Linnaeus)

Pod and seed damage Pod and seed damage Pod and seed damage

Pentatomidae

Nezara viridula (Linnaeus)

Suck the sap from foliage

America Europe South-east Anatolia, Turkey Europe, Africa, Asia, Australia and America

Hemiptera Aleyrodidae Aphididae

Acrythosiphon pisum (Harris)

Aphis craccivora (Koch)

Macrosiphum creelii (Davis) Myzus persicae (Sulzer)

Defoliators – ﬂower, buds, foliage, early pods

Worldwide

Sekhon et al. (1979), Bhatnagar and Sehgal (1989) Makkouk and Kumari (2001), Jones and Coutts (2008) Pandey et al. (2000) Fye (1982) Schotzko and O’Keeffe (1986) Özberk et al. (2006) Hariri (1981)

R. Ujagir and O.M. Byrne

Status

Coreidae Lygaeidae

Lepidoptera Noctuidae

Phycitidae

Balclutha sp. Empoasca sp. Cletus signatus Walker Graptostethus servus (Fabricius) Eusarcocoris ventralis Westwood Piezodorus rubsofasciatus Fabricius Agrotis ipsilon (Hufnagel) Helicoverpa (Heliothis) armigera (Hubner) Laphygma exigua (Hubner) Spodoptera praeﬁca (Hubner) Spodoptera exigua (Hubner)

Foliage Foliage Foliage Foliage

Minor Minor Minor Minor

India India India India

Bhatnagar and Sehgal (1989) Bhatnagar and Sehgal (1989) Bhatnagar and Sehgal (1989) Bhatnagar and Sehgal (1989)

Suck the sap from foliage Suck the sap from vegetative parts Cut the stem Damage the pod and seed Defoliation Defoliation Defoliation

Minor

India

Bhatnagar and Sehgal (1989)

Minor

India

Bhatnagar and Sehgal (1989)

Syria, Egypt Syria, India

Spodoptera littoralis (Boisd.) Trichoplusia ni (Hubner) Thysanoplusia oricholcea (Fab.) Etiella behrii (Zeller)

Defoliation Defoliation Defoliation Pod and seed damage Pod and seed damage Damage the pods

Zaazou et al. (1975) Tahhan and Hariri (1982), Paharia (1983) Sacharov (1916) Halfhill (1982) Sacharov (1916), Brown and Dewhurst (1975) Brown and Dewhurst (1975) Hariri (1981) Bhatnagar and Sehgal (1989) Pandey et al. (2000)

Etiella zinckenella (Tretsche) Tortricidae

Diptera Agromyzidae

Laspreyresia nigracana (Fabricius)

Autographa gamma (Linnaeus) Chromatomyia horticola (Goureau)

Foliage feeder Mines the leaves

Minor

Major

India America, Syria India, Africa, Near East Near East Syria Europe, India Victoria, South Australia India, USA, Egypt

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Cicadellidae

Singh and Dhooria (1971), Hammad (1978) Sedivy and Suchanek (1978)

North America, former Czechoslovakia, Europe, Mediterranean Nepal, Syria Pandey et al. (2000) Europe, Africa, India Sehgal et al. (1980), Mandal (1982), Bhatnagar and Sehgal (1989)

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(Continued)

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Table 18.1. continued

Order and family

Cecidomyiidae

Coleoptera Bruchidae

Nature of damage/ plant parts attacked

Ophiomyia phaseoli (Tryon) Liriomyza spp.

Leaves and stem Leaves

Contarinia spp. Contarinia lentis (Aczel)

Damage leaves Damage leaves

Bruchidius quinqueguttatus (Oliv.) Bruchus atomarius (L.)

Bruchus lentis (Froel.)

Damage pods and seeds Damage pods and seeds Damage pods and seeds Damage pods and seeds Pods and seeds

Bruchus ervi (Froel.)

Pods and seeds

Callosobruchus maculatus (Fabricus)

Flowers, pods, seeds

Callosobruchus chinensis (Linnaeus)

Flowers, pods, seeds

Apion ervi (Kirby)

Leaves, buds, ﬂowers

Apion trifolii (Linnaeus)

Leaves, buds, ﬂowers

Bruchus signaticornis (Gyll.) Bruchus tristiculus (Fahrs.)

Apionidae

Status

Country/continent

References

Egypt West Africa, North Africa and South America Europe, Africa, India France, former Czechoslovakia Mediterranean, South-west Asia Euro-siberian

Harakly and Assem (1980) Stevenson et al. (2007)

Europe, North Africa, America Mediterranean, Near East Europe, Africa and Asia Europe, Nepal, North Africa, Southwest Asia, India Europe, Asia, USA, Australia, Mediterranean Europe, Asia, USA, Australia, Mediterranean Europe, South-west Asia Europe, USSR, South-west Asia, Mediterranean

Alkan (1966)

Kemkemian (1979) Minssen and Pacqueteau (1969), Kolesik and Kolesik (1989) Hammad (1978) Hammad (1978)

Hammad (1978) Gibson and Raina (1973) Pandey et al. (2000)

Staneva (1982), Pandey et al. (1985) Staneva (1982), Pandey et al. (1985) Sakamoto et al. (1983) Melamed-Madjar (1968)

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Scientiﬁc name

Apion pomonae (F.) Apion punctigerum (Payk.) Apion seniculus (Kirby) Curculionidae

Sitona crinitus (Herbst)

Sitona macularius (Marsham) Sitona limosus (Rossi) Tychius aorominus quinonepunctatus (Linnaeus) Chrysomelidae Altica coerulea (Oliver) Aulacophora foveicollis (Lucas) Phyllotreata chotanica (Duvivier) Hypera postica (Gyllenhal) Coccinellidae Thysanoptera Thripidae

Brumoides suturalis Fab. Epilachna spp. Thrips anguisticeps (Uzel) Kakothrips robustus (Uzel) Frankliniella spp. Thrips tabaci (Lind.)

Damage leaves and seeds Damage leaves and seeds Damage leaves and seeds Damage leaves and seeds Foliage and root nodules

Major

Foliage and root nodules Damage seedlings and nodules Pod and seed Foliage feeder Foliage feeder Foliage feeder Foliage feeder

Minor Minor Minor Minor

Minor Damage foliage Damage foliage Minor Suck the sap from plant Minor Suck the sap from plant Suck the sap from plant Suck the sap from plant

Turkey and Syria

Zeran and Yabas (1984)

Europe, former USSR, Turkey, Syria Europe, former USSR, Syria Europe, former USSR, Turkey Europe, West Asia, South-west Asia, North Africa, former USSR Former USSR

Rivnay (1962)

Syria

Melamed-Madjar (1968)

Romania

Boguleanu et al. (1971)

India India India West Asia, Europe, USA India India Syria

Bhatnagar and Sehgal (1989) Bhatnagar and Sehgal (1989) Bhatnagar and Sehgal (1989) Bhatnagar and Sehgal (1989)

Nepal, Asia, Africa Syria Spain

Melamed-Madjar (1968) Melamed-Madjar (1968) Kilic et al. (1968)

Insect Pests and their Management

Apion arrogans (Wenk.)

Hariri (1981)

Bhatnagar and Sehgal (1989) Bhatnagar and Sehgal (1989) Beniwal et al. (1993), Pandey et al. (2000) Beniwal et al. (1993), Pandey et al. (2000) Beniwal et al. (1993), Pandey et al. (2000) Perez-Andueza et al. (2004) 287

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Several workers have reported C. horticola as an important pest of legumes (Lefroy, 1909; Tahhan and Hariri, 1982). The damage to lentil leaves has been reported to be as high as 5.5% from mid-April to mid-May (Tahhan and Hariri, 1982). The bean aphid, A. craccivora, has been widely reported from America, Europe, Africa, Asia and Australia. Tahhan and Hariri (1982) observed that the feeding of bean aphids on young lentil plants caused a reduction in the relative growth rate and efficiency of production of new tissues at an average plant infestation level of about 17.5%. The pod borer, H. armigera, has been reported as the major pest attacking the lentil crop. Field infestation of 26% by pod borer was observed during a survey in Syria (Tahhan and Hariri, 1982). Paharia (1983) reported that damage caused by the lentil pod borer, E. zinckenella, under field conditions was the main limiting factor in the production of lentil and gram. Lentil pod borer can cause from 31 to 50% loss in yield (Memon and Memon, 2005). Singh and Dhooria (1971) reported that the pod borer E. zinckenella caused 10.6% damage to lentil grain and a loss in seed weight. Sandhu and Verma (1968) assessed the losses caused by E. zinckenella to lentil pods as 12–15%. Experiments at the International Center for Agricultural Research in the Dry Areas (ICARDA) showed that small lentil seed infested with B. ervi did not germinate, while 20% of infested large seeds germinated (Hariri, 1981). Infestation by C. chinensis also affects seed germination. Germination of large and small lentil varieties was 84 and 25%, respectively, when the seeds harboured one bruchid each; 32 and 5% when there were two bruchids per seed; and 20 and 0% when each seed had three bruchids. In a survey in Syria, Tahhan and Hariri (1982) observed that 93% of fields were infested by bruchids with damage to 1.9% of plants. Zeran and Yabas (1984) observed that bruchid feeding resulted in the formation of swelling and spots on the buds and inhibited capsule production, leading to considerable crop losses. They also studied the morphology and nature of damage caused by Apion sp. on the crop. Economic losses resulting from damage by lygus bug, bud weevil and Sitona spp. are reported for red lentil exports in Turkey (Özberk et al., 2006). Summerfield et al. (1982) reported that feeding by Lygus sp. on immature reproductive structures caused formation of poor quality seeds (chalky spot) and reduced economic yield. Lentil weevil, B. lentis, and spotted pea weevil, Tychius quinquepunctatus, were reported to be the major pests of lentil in Italy. The seed damage due to lentil weevil ranged from 6 to 29% under field conditions and 5.5 to 14.5% at harvest (Isidoro et al., 2001).

18.4. Insect-spread Viruses The lentil crop is susceptible to a variety of insect-borne virus diseases which can severely reduce the crop yield and are mostly spread by aphids (see Kumari et al., Chapter 19, this volume, for details on viral diseases).

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Lentil yellows disease The disease is caused by Bean leaf roll virus (BLRV), Beet western yellows virus (BWYV) or Subterranean clover red leaf virus (SCRLV). These viruses are transmitted through the sap and by aphid in the non-persistent manner. A number of aphids can transmit these viruses, but important ones include A. pisum, Aphis fabae, A. craccivora and Myzus persicae.

Bean yellow mosaic The disease is caused by Bean yellow mosaic virus (BYMV) and is transmitted through aphids A. pisum, A. fabae, A. craccivora and M. persicae.

Broad bean stain The disease is caused by Broad bean stain virus (BBSV). Vectors of this virus are weevils Apion vorax and Sitona spp.

Pea seed-borne mosaic The disease is caused by the Pea seed-borne mosaic virus (PSbMV). Transmission of the virus occurs by aphids A. pisum, A. craccivora and A. fabae.

Cucumber mosaic The disease is caused by Cucumber mosaic virus (CMV) and is transmitted by several species of aphids.

Other viruses Other viruses which cause diseases in lentil include Bean leaf roll virus (BLRV), Faba bean necrotic yellows virus (FBNYV), Soybean dwarf virus (SBDV) and Lucerne mosaic virus. They are also transmitted by aphids (Makkouk and Kumari, 2001; Jones and Coutts, 2008).

18.5. Pest Management Lentil is grown in diverse environments under varying levels of pest pressure around the world. Very few insects have attained the status of economic pest of the crop. Low temperatures during the crop growth period,

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short duration of crop growth, small leaf area and relatively small pod size may be some of the reasons for low pest attack. However, certain situations such as late planting increase the vulnerability to pest attack. Therefore, successful cultivation of the crop should include effective management through forecasting, monitoring and modelling of the economic insect fauna.

Monitoring methods Monitoring and forecasting systems for lentil are in their infancy. The use of pheromone and sticky traps is becoming popular among growers. The following examples will illustrate some of the different monitoring programmes developed for a few important pests. Aphids Insecticide treatment for pea aphid control should be considered when an economic threshold of 30–40 aphids are collected per 180° sweep of a 38 cm (15 inch) diameter insect net, when few natural enemies are present, and when aphid numbers do not decline over a 2-day period (Homan et al., 1991). An aphid-tracking network was recently developed for the Washington State region of the USA. Lygus bugs Adult lygus-bug activity can be monitored during blooming and podding by making 25 × 180° sweeps in at least five randomly selected places in a field. Chemical control is applied when 7–10 adults are collected per 25 sweeps (O’Keeffe et al., 1991). Pod borer, Helicoverpa Adult male populations can be monitored by pheromone-baited traps to understand the onset of infestation and to study population dynamics. Lentils are very susceptible to native budworm damage from early podding to pod fill – peak moth flights coincide with the flowering to pod filling stage of late-sown lentil. The crop should be monitored from late flowering and sprayed when the economic threshold reaches >1 larva in 10 sweeps (one larva/m2). Etiella Management is based on timing of sprays to target adult moths. Management is facilitated by downloadable Etiella Degree–Day models to identify onset of flight activity within the crop. Monitoring should continue at 4–5 day intervals, using sweep nets, light or pheromone traps. Action is recommended for a threshold of 1–2 Etiella per 20 sweeps.

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Cultural control Cultural control includes some of the oldest pest control practices known, such as manuring for vigorous growth, crop rotation, manipulation of sowing date, mixed cropping and field sanitation, etc. Such practices may be helpful in overall reduction of the population of harmful insects in the crop. The sowing date may be manipulated in order to ensure that a susceptible stage does not coincide with peak pest numbers. However, different pests respond to time of sowing in different ways, and it may be difficult to design a programme that offers protection against all potential pests. Early or timely sowing ensures that the crop escapes the damage by pod borers such as H. armigera in India. Thus lentil sown from mid-October to mid-November is almost free from H. armigera whereas late (December) sowing increases the risk of pod borer and leaf miner infestations. Certain weeds can act as hosts for lentil pests and such species should be eliminated from the field. Since the suitability of the plant host depends not only on the species, but also on its growth stage, generalization about the suitability of the alternative host should be made with care. Vicia spp., Melilotus spp. and Chenopodium are among the hosts of H. armigera, leaf miner and bean aphid. Intercropping is likely to find a place in reducing pest problems. A few examples are available from India, where intercropping with mustard, coriander and linseed may lead to increase in spider and braconid parasitoids.

Host plant resistance Very little research has been conducted to identify resistant varieties against various lentil pests. The use of resistant cultivars in an integrated pest management (IPM) programme depends on the efficacy of other pest control options available. In a review of research achievements for plant resistance to insect pests of cool-season food legumes by Clement et al. (1994), the consensus view was that insect pest resistance research and breeding was ‘undervalued and underfunded’. The state of affairs has changed little since then, and although there has been some notable progress in the identification of new sources of resistance, there has been less progress in resistant variety development. The situation is probably in part influenced by economics and a lack of resources, as well as the intricate nature of the plant-insect interrelationship. Helicoverpa armigera Six out of 18 cultivars (L 1282, LL 116, L 830, LL 78, LG 11 and HPL 5) consistently showed low pod-borer attack compared to check variety Pant L 639 and Pant L 406 in India (Ujagir, 1993).

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Etiella zinckenella Eleven genotypes out of 79 were categorized as least susceptible to the infestation of E. zinckenella (Jaglan et al., 1993). Tolerance to E. zinckenella was identified in lentil line LL 147 (Brar et al., 1989). However, there have been no recorded attempts to incorporate these lines into breeding programmes (Erskine et al., 1994). Bruchids Singh and Sharma (2001) screened seven cultivars of lentil for their response to the oviposition and development of the pulse beetle. Cultivar K-75 had the minimum growth index and slowest developmental period of the insect. In another study, lentil varieties 79-1 and ‘Precoz’ were found resistant against Callosobruchus analis (Shafique and Ahmad, 2002). Ecological resistance to B. lentis under field conditions has been discussed by Clement et al. (1994). Genetic differences in L. culinaris genotypes have been found against B. lentis (Chopra and Pajni, 1987), although no attempt in resistance breeding has been undertaken (Erskine et al., 1994). Sitona crinitus Host plant resistance has recently become a potential option in the control of S. crinitus. El-Bouhssini et al. (2008) identified resistance to S. crinitus in wild species of lentil originating from Turkey, Syria and Croatia: Lens nigricans, L. culinaris ssp. odemensis, Lens ervoides and L. culinaris ssp. orientalis. One of the resistant accessions, ILWL245 of L. culinaris ssp. orientalis is crossable with the cultigen, and the goal is now to transfer resistance to cultivated lentil, as well as to study the inheritance of resistance (El-Bouhssini et al., 2008). Sedivy (1972) tested several lentil cultivars against Sitona for feeding damage and found differences in the amount of damage. Weigand and Pimbert (1993) recommend feeding damage as the scoring method of choice in host-resistance screening for Sitona and described a laboratorybased screening protocol for this. The ‘Yerli Kirmizi’ variety of lentil was reported to be resistant against S. crinitus (Erman et al., 2005). Aphids Weigand and Pimbert (1993) reported that there were genotypic differences between lentil genotypes in resistance screening for A. craccivora, using a technique developed for screening in faba bean. Mechanisms of resistance to A. pisum in lentil genotypes have been investigated by Andarge and Westhuizen (2004). Genetic differences were observed in lentil germplasm under natural infestation with A. craccivora and Acyrthosiphon kondoi in New Zealand (Erskine et al., 1994). Muehlbauer and Kaiser (1994) reported that resistance to aphids (and weevils) in lentil is incomplete and polygenic. To date there are no reports of resistant varieties released to farmers from this genetic material.

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Emerging technologies Over the past two decades the genomics revolution has enabled rapid progress in functional genetics and proteomics of legume crops including lentil. There has been some progress in our understanding of lentil-insect interactions using these rapidly evolving technologies, which, in time, should lead to practical crop protection applications. For a recent report on the progress and applications of molecular research in lentil itself, see Ford et al. (Chapter 11, this volume) and Muehlbauer et al. (2006). Genomics and plant defence The secondary plant compounds lectins, proteinase inhibitors (PIs) and alpha-amylase inhibitors (AAIs) play a major role in plant defence and are particularly well featured within the legume family (Ryan, 1990; Chrispeels and Raikhel, 1991). Lentil PIs (trypsin and chymotrypsin inhibition sites) have been used to investigate host-pathogen co-evolution (Sonnante et al., 2005). There is a common functionality among many of these defence gene families. Using functional and comparative genomics approaches, macrosyntenic relationships are being explored in model and crop legumes including lentil (Zhu et al., 2002). For example, lectin genes on linkage group VII in field pea have homologous regions in lentil. PIs and lectins from different plant origins have an inhibitory effect on the adult lucerne weevil, Hypera postica (Elden, 2000). Comparative genomics provides an opportunity to fast-track lentil improvement by interpreting the information obtained from equivalent genome regions in related legumes. This approach is likely to target generalist insect pests; finding syntenic regions for specialist insect pests of lentil might be a greater challenge. The following insect pests of Medicago truncatula may be candidates for gene synteny comparisons with lentil: blue-green aphid (Acyrthosiphon kondoi), pea aphid (A. pisum), cowpea aphid (A. craccivora), red-legged earth mite (Halytodeus destructor), lucerne flea (Sminthurus viridus) and Sitona weevils (Sitona discoideus, Sitona humeralis). Genes have been identified that control phytoalexins, chitinases, glucanases and lipoxigenases (the LOX genes). The jasmonic acid (JA) pathway plays a major role in inducing resistance to a broad spectrum of insects. The ‘omics revolution is providing us with increasing evidence that many legume-defence mechanisms are conditioned by resistance gene analogues (RGAs), damage response regions (DRR), flavonoids, plant defence-related genes (e.g. str246N), gibberellin c-20 oxidase, maysin synthesis, glycosylflavone and NADH dehydrogenase, which may facilitate new approaches to crop protection and improvement (Young et al., 2005; Howe and Jander, 2008). Genetic transformation The Bacillus thuringiensis gene that controls insecticidal Delta endotoxin production has been introduced into rhizobial strains – a model that has

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potential to control pea leaf weevil if introduced into its lentil host (Erskine et al., 1994). Mutation breeding Mutation breeding may have potential for inducing monogenic resistance to insects in lentil; however, it is likely to pose a major challenge for polygenic resistances underlying complex plant-insect interactions. Induced mutations seem to be undergoing resurgence – for a global perspective on mutation-derived crop varieties see Ahloowalia et al. (2004). In-vitro hybridization Embryo rescue techniques have been successful in overcoming hybridization barriers to obtain hybrids between cultivated lentil and L. nigricans ssp. ervoides and L. nigricans ssp. nigricans (Muehlbauer et al., 1994). Biological control The role of natural enemies has been studied for a number of insect pests, and in several cases they have been shown to play a significant role, reducing the need for pesticide application or other control measures. Aphids Aphids have many natural enemies, including ladybird beetles, parasitic wasps, lacewings and syrphid flies (Homan et al., 1991). Stark et al. (2004) reported Coccinella septumpunctata (L.), predator and Diaertiella rapae (McIntosh), parasitoid of pea aphid Acrythosiphon pisum. The feeding potential of spiders on A. craccivora was studied by Sebastian and Sudhikumar (2003) and the spider species Lycosa poonaensis (Tikader and Malhotra) and Lycosa tista (Tikader) consumed the highest number of prey. A predator complex including C. septumpunctata, Micraspis discolor, Menochilus sexmaculatus and Coccinella transversalis were found feeding on A. craccivora by Sharma et al. (1991). Sharma and Yadav (1993) reported the effectiveness of aphidophagous coccinellids in controlling the population of A. craccivora. They worked out the possibilities of ecologically sound aphid management in lentil by exploiting the insect-plant relationship against the pest in favour of its natural enemies. Damage caused by the pea aphid, A. pisum, is a limiting factor in lentil production in several countries. Andarge (2001) worked on the multifaceted approach in order to keep A. pisum below economic threshold. Beauveria bassiana was found to be significantly effective in reducing the population of A. pisum compared to the control. The botanical product Neemolin also proved to be highly efficient in reducing the bean aphid population. Grasshopper Dysart (1995) reported that egg pods of grasshopper species were parasitized by four species of scelionid wasps, including Scelio opacus, which was

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the dominant parasitoid species, accounting for 92% of all parasitized pods of lentil. Songa and Holliday (1997) reported the high feeding potential of adult carabid beetles, Pterostichus corvus (Leconte) and Pterostichus femoralis (Kirby) on the eggs of M. bivittatus. Seed beetle, B. lentis Isidoro et al. (2001) reported Uscana spp. as an egg parasitoid of B. lentis with variable efficacy (1–21%). Pupal and larval parasitoids were also observed. Pod borer, E. zinckenella Marwoto (2003) reported Trichogrammatoidea bactrae-bactrae as an effective biocontrol agent for Etiella spp. Other important natural enemies include Macrocentrus ancylovorus, Bracon piger, Apanteles beaussetensis, Bracon pectoralis, Phanerotoma planifrons and Cyrtotyx lichtensteini. Cutworm, A. ipsilon Among the wasps known to attack this cutworm are Apanteles marginiventris (Cresson), Microplitis feltiae Muesebeck, Microplitis kewleyi Muesebeck, Meteorus autographae Muesebeck, Meterorus leviventris (Wesmael) (Hymenoptera: Braconidae); Campoletis argentifrons (Cresson), Campoletis ﬂavicincta (Ashmead), Hyposoter annulipes (Cresson) and Ophion ﬂavidus Brulle (Hymenoptera: Ichneumonidae). The cutworm larvae consume about 24% less foliage and cut about 36% fewer seedlings when parasitized by M. leviventris. Thus considerable benefit is derived from parasitism in addition to the eventual death of the host larvae. Other parasitoids known from black cutworm include flies often associated with other ground-dwelling noctuids, including Archytas cirphis Curran, Bonnetia comta (Fallen), Carcelia formosa (Aldrich and Webber), Chaetogaedia monticola (Bigot), Eucelatoria armigera (Coquillett), Euphorocera claripennis (Macquart), Gonia longipulvilli Tothill, Gonia sequax Williston, Lespesia archippivora (Riley), Madremyia saundersii (Williston), Sisyropa eudryae (Townsend) and Tachinomyia panaetius (Walker) (Diptera: Tachinidae) (University of Florida, 2008). Leaf miners, Liriomyza trifolii and C. horticola According to previous records, all natural enemies of agromyzids are Hymenopterans of Chalcidoidea, Ichneumonidea and Cynipodea. Among these, chalcid parasitoids are reported to constitute the most dominant group (Murphy and LaSalle, 1999). Some of the other potential parasitoids recorded are given in Table 18.2. Pod borer, H. armigera Over 78 species of arthropod parasitoids and 33 species of predators have been reported to directly prey on a specific life stage of H. armigera within

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Parasitoid species and their hosts (Source: Lütﬁye, 2004).

Parasitoids

Pest

Diglyphus iseae Diglyphus chabrias Neochrysocharis arvensis Neochrysocharis formosa Pediobius acantha Chrysocharis sp. Hemiptarsenus sp.

L. trifolii and C. horticola L. trifolii and C. horticola L. trifolii and C. horticola L. trifolii Unknown species Unknown species L. trifolii

India (Manjunath et al., 1989). Similarly, a number of natural enemies have been reported from Pakistan, South-east Asia, China, Australia, eastern and southern Africa and Western Europe. Recently, Sithanantham et al. (2005) prepared a list of about 134 parasitoids and 82 predators of eggs, larvae and pupae reported from India and elsewhere. The most important orders are Coleoptera, Hemiptera, Hymenoptera, Neuroptera, Orthoptera and Araneida. Among these, Trichogramma on eggs, Campoletis on larvae, and predatory birds are the most important biotic agents of H. armigera in northern India. Viruses, bacteria, protozoa, fungi and nematodes are important pathogens which cause diseases in H. armigera. The success achieved in chickpea with commercial formulation of B. thuringiensis and nuclear polyhedrosis viruses may be extended to lentil to reduce crop damage and increase grain yield where H. armigera is a serious problem.

Chemical control Due to ready availability, effectiveness and rapid control of pest populations, insecticides are popular among farmers. Sufficient numbers of selective pesticides are available to treat target pests without causing damage to the predatory insects. Sitona weevil Effective control of Sitona by spraying with chlorinated pinene, trichlorphon (Khlorofos), carbaryl (Sevin) and dimethoate (Bi-58) and dusting with methyl parathion (Metafos) was reported by Petrukha (1970). Carbofuran and aldicarb were effective in reducing the damage caused by Sitona spp. (Solh et al., 1986). Erman et al. (2005) tested different insecticides against S. crinitus on the lentil crop and reported the application of oxydemeton methyl to be most effective in decreasing the nodule damage caused by the weevil. Weigand et al. (1994) reported that lentil seed treated with furathiocarb (Promet) provided good control against Sitona spp. In a study in Syria, carbofuran effectively controlled Sitona spp. (Hariri and Tahhan, 1983).

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Helicoverpa spp. Memon and Memon (2005) worked on the comparative efficacy of four different insecticides against the pod borer (Helicoverpa spp.) on the lentil crop. Spinosad was the most effective insecticide in reducing the pod borer population and decreasing pod damage, followed by chlorpyrifos and endosulfan. The maximum increase in seed yield per hectare was obtained with spinosad. Barroga and Barrers (1969) reported that dimethoate, phosphamidon, methyl parathion, monocrotophos, promecarb, bromophos and naled were effective in reducing the damage caused by Heliothis sp. At Pantnagar (India), endosulfan, monocrotophos, quinalphos and triazophos, besides synthetic pyrethroids fenvalerate, decamethrin and cypermethrin gave effective control of pod-borer damage during the period 1979–1981 (Sehgal and Ujagir, 1980, 1982). Tahhan and Hariri (1982) reported that the insecticides deltamethrin and methidathion were effective in the control of H. armigera on lentil. The effect of crude PI extracts from seeds of lentil and other pulse crops on the insecticidal activity of B. thuringiensis var. kurstaki HD-1 against neonate larvae of H. armigera by the diet incorporation method was investigated by Gujar (2004). A mixture of B. thuringiensis var. kurstaki and PIs of lentil varieties ILL 8095 and L 4626 was found to act synergistically in controlling H. armigera. Aphids Sharma et al. (1991) reported cypermethrin and endosulfan to be effective against A. craccivora. Aphids transmitting viruses could be reduced by seed treatment with imidacloprid (Makkouk and Kumari, 2001). Systemic insecticides also control aphids on lentil (Thakur et al., 1984). Leaf miner Several pesticides administered separately as well as in a combination of sprays, dust and granular formulations have been found effective in controlling the damage by leaf miner (Atwal et al., 1969; Vyas and Saxena, 1982). The application of phosphamidon, dimethoate, monocrotophos, endosulfan, methyl demeton and dicrotophos effectively controlled this pest. Bruchus lentis Lambdacyhalothrin and endosulfan applied at the flowering stage of a lentil crop provide control of B. lentis. Lygus bug In Turkey, lygus bug has been indirectly controlled by aerial insecticide that was applied to a cereal crop infested with sunn pest (Eurogaster integreceps L.) (Özberk et al., 2006). However, the government programme was suspended leading to an increase in the population and damage cause by lygus bug.

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Etiella Application of deltamethrin and esfenvalerate to target adult moths prior to egg lay were found to be effective in containing Etiella within the acceptable industry threshold of <1% insect-damaged grain in 2004 and 2005 trials in Australia.

Insecticide resistance Cytochrome P450 DNA and mRNA expression has been investigated in different strains of lygus bugs that had different susceptibility to pyrethroid insecticides (Zhu and Snodgrass, 2003). Annotated expressed sequence tags (ESTs) and xenobiotic detoxifications have also been studied in the aphid Myzus persicae (Sulzer) (Figueroa et al., 2007). There is scope for future research into understanding gene regulation and biochemical pathways of P450s and how they influence insecticide susceptibility, leading to protocols that may reduce the risk of insecticide resistance developing.

18.6. Concluding Remarks IPM includes effective use of various compatible pest control measures to reduce pest populations below damaging levels and optimize yield with minimum damage to the environment. This review clearly shows that considerable knowledge already exists about pest management systems in lentil to initiate formulation of IPM strategies. Modification to IPM approaches can be made later on as our knowledge on host plant resistance, economic threshold level (ETL) and economic injury level (EIL) for different pests in the agroecosystem of the locality increases. Thus, based on the results and experience gained so far in the lentil crop, the following agenda for IPM is suggested. Information on crop-loss assessment by major pests of lentil crop in different agroecological zones needs to be fully documented to prioritize our research on pest management and host plant resistance studies on the key pests in each area. For this, a survey needs to be planned, coupled with methodology combining systematic sampling with statistics. Climate change is likely to play a role in decision making in future IPM strategies, along with greater adoption of novel technologies, over the coming years. Manipulation of the date of sowing, intercropping and crop rotation have given significant reduction in populations of pod borers, foliage feeders and soil pests. Promoting the right kind of cropping systems, by raising companion and/or barrier crops such as coriander, mustard and linseed, will certainly minimize the population of Helicoverpa and Etiella and other pests. Systematic studies on host plant resistance against key endemic pests and the biochemical/biophysical basis for such resistance can make rapid

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progress in the development of insect-resistant cultivars. Development of multiple resistances or at least moderate resistance against key pests of the area should be the research priorities. In recent years, there have been reports of resistant germplasm to many key pests of lentil. For example, Rembold and Schroth (1993) reviewed research achievements in the improvement of resistance in lentil and other food legumes against a wide range of insect pests, however, the factors responsible for this resistance are yet to be identified. Sequencing of genomes in model legumes has led to progress in our understanding of the underlying genetics and biochemistry of lentil-insect interactions (Sato et al., 2007). Shared synteny of genes on chromosomes with model legumes should lead to a better insight into how lentil genes function in response to insect pests. Using molecular technology, plant resistance (R) genes have been isolated and transferred to susceptible varieties. Transferable molecular markers, such as microsatellites (simple sequence repeats; SSRs), have great potential in marker-assisted selection for resistance, but adoption in lentil breeding programmes is not yet available. It must be noted that so far, effective insect resistance has not been obtained, and only a few durable R genes have been isolated. These too have limitations for their applications across taxonomic barriers (ICAR, 2007). Certain biocontrol agents such as Chrysops spp., Campoletis spp., Trichogramma spp., Bacillus thuringiensis and nuclear polyhedrosis virus (NPV) are suitable candidates for improving the biological control of some of these pests. More potential strains of NPV, bacteria and other insect pathogens need to be identified from the areas where they are virulent. Research should be intensified into finding effective plant-derivative pesticides that are within the reach of farmers in rural areas. This will require identification of more such plants, evaluation of their extracts for insecticidal properties and application methodology. Studies on proper sampling methodology and ETLs and EILs of key endemic pests of the lentil crop are needed to generate databases for judicious need-based application of ecofriendly chemical insecticides so as to minimize risks of insecticide resistance and pest resurgence. Even with the present level of knowledge, IPM can significantly reduce chemical pesticide inputs. Governments, industry and funding bodies will need to invest in research programmes that encompass these technical challenges, and through education and training of key field and scientific personnel get through this bottleneck.

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19

Virus Diseases and their Control

Safaa G. Kumari,1 Richard Larsen,2 Khaled M. Makkouk1 and Muhammad Bashir3 1International

Center for Agricultural Research in the Dry Areas (ICARDA), Aleppo, Syria; 2United States Department of Agriculture (USDA) Agriculture Research Service (ARS), Prosser, Washington, USA; 3Crop Diseases Research Institute, National Agricultural Research Centre (NARC), Islamabad, Pakistan

19.1. Introduction Biotic and abiotic factors limit yields and cause yield instability of lentil. Many of the diseases that affect lentil, especially those induced by viruses, can also infect other food and forage legumes. The relative importance of virus diseases varies depending on geographical location and agroecological conditions. Yield losses from virus infection vary from little or none to complete crop failure depending on the time and severity of infection. Worldwide, lentils are susceptible to at least 30 different virus species representing 16 genera from nine families with genomes comprised of single-stranded RNA or DNA (Table 19.1) (Bos et al., 1988; Fonseca et al., 1995; Makkouk et al., 2003a; Abraham et al., 2006; Taylor et al., 2007). Among the most important viruses that infect lentil are Bean leafroll virus (BLRV), Bean yellow mosaic virus (BYMV), Beet western yellows virus (BWYV), Cucumber mosaic virus (CMV), Faba bean necrotic yellows virus (FBNYV), Pea enation mosaic virus-1 (PEMV-1), Pea seed-borne mosaic virus (PSbMV) and Pea streak virus (PeSV). In this chapter, we review transmission, ecology and epidemiology of the economically most important viruses that infect lentil. We also describe sensitive assays available for detection and appropriate measures for control.

19.2. Viruses Reported to Infect Lentil Large-scale surveys carried out during the last two decades have shown that the most widespread viruses in lentil include six that cause yellowing/ 306

© CAB International 2009. The Lentil: Botany, Production and Uses (eds W. Erskine et al.)

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Table 19.1. Virus species reported to infect lentil by natural and/or artiﬁcial inoculation. Virus taxonomy adopted in this table is based on the most recent ICTV report (Source: Fauquet et al., 2005). Mode of transmission Virus species

Genomea

Abbreviation

Genus

Family

Vectorsb

Alfalfa mosaic virus Artichoke latent virus Bean common mosaic virus Bean leafroll virus Bean pod mottle virus Bean yellow mosaic virus Beet western yellows virus Broad bean mottle virus Broad bean stain virus Broad bean true mosaic virus Broad bean wilt virus-1 Chickpea chlorotic dwarf virus Chickpea chlorotic stunt virus Chickpea ﬁliform virus Chino del tomate virus Cucumber mosaic virus Faba bean necrotic yellows virus Pea enation mosaic virus-1 Pea seed-borne mosaic virus Pea streak virus Peanut stunt virus Quail pea mosaic virus Red clover vein mosaic virus Soybean dwarf virus Subterranean clover stunt virus Tobacco streak virus Tomato black ring virus Tomato spotted wilt virus Tomato yellow leaf curl virus Turnip mosaic virus

ssRNA ssRNA ssRNA

AMV ArLV BCMV

Alfamovirus Potyvirus Potyvirus

Bromoviridae Potyviridae Potyviridae

Aphids NP Aphids NP Aphids NP

+ + +

ssRNA ssRNA ssRNA

BLRV BPMV BYMV

Luteovirus Comovirus Potyvirus

Luteoviridae Comoviridae Potyviridae

Aphids P Beetles Aphids NP

– + +

ssRNA

BWYV

Polerovirus

Luteoviridae

Aphids P

–

ssRNA ssRNA ssRNA

BBMV BBSV BBTMV

Bromovirus Comovirus Comovirus

Bromoviridae Comoviridae Comoviridae

Beetles Beetles Beetles

+ + +

ssRNA ssDNA

BBWV-1 CpCDV

Fabavirus Mastrevirus

Comoviridae Geminiviridae

Aphids NP Leafhoppers

+ –

ssRNA

CpCSV

Polerovirus

Luteoviridae

Aphids P

–

ssRNA ssDNA ssRNA ssDNA

CpFV CdTV CMV FBNYV

Potyvirus Begomovirus Cucumovirus Nanovirus

Potyviridae Geminiviridae Bromoviridae Nanoviridae

Aphids NP Whiteﬂies Aphids NP Aphids P

+ – + –

ssRNA

PEMV-1

Enamovirus

Luteoviridae

Aphids P

+

ssRNA

PSbMV

Potyvirus

Potyviridae

Aphids NP

+

ssRNA ssRNA ssRNA ssRNA

PeSV PSV QPMV RCVMV

Carlavirus Cucumovirus Comovirus Carlavirus

Flexiviridae Bromoviridae Comoviridae Flexiviridae

Aphids NP Aphids NP Beetles Aphids

+ + + +

ssRNA ssDNA

SbDV SCSV

Luteovirus Nanovirus

Luteoviridae Nanoviridae

Aphids P Aphids P

– –

ssRNA ssRNA ssRNA ssDNA

TSV TBRV TSWV TYLCV

Ilarvirus Nepovirus Tospovirus Begomovirus

Bromoviridae Comoviridae Bunyaviridae Geminiviridae

Thrips Nematodes Thrips Whiteﬂies

+ + + –

ssRNA

TuMV

Potyvirus

Potyviridae

Aphids NP

+

a ss,

single stranded. NP, aphids in non-persistent manner; Aphids P, aphids in persistent manner.

b Aphids

Sap

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Table 19.2. Viruses of regional or global economic importance reported to naturally infect lentil (Source: Bos et al., 1988; Makkouk et al., 2003a). Geographical distribution Virus species AMV BCMV BLRV BYMV BWYV BBWV-1 BBMV BBSV CpCDV CpCSV CMV FBNYV PEMV-1 PSbMV PeSV SbDV TSWV

America

Europe

Africa

Asia

Australasia

+ + + – – – – – – – – – + + + – +

– – – – – – – – – – – – + – – – –

+ – + + + – + + – + + + – + – + –

+ + + + + + + + + – + + + + – + –

+ – – + + – – – – – + – – + – + –

stunting/necrosis and approximately ten viruses that cause mosaic or mottling symptoms (Table 19.2) (Makkouk et al., 2003a). Viruses causing yellowing and stunting symptoms are the most important worldwide, and include BLRV, BWYV, FBNYV, Chickpea chlorotic dwarf virus (CpCDV) and Soybean dwarf virus (SbDV) (= Subterranean clover red leaf virus; SCRLV). These viruses induce symptoms of leaf rolling, reddening, yellowing and stunting (Plate 3A, B, C) and plants infected at early growth stages usually exhibit shortened internodes and pronounced proliferation of axillary shoots. These viruses are phloem-limited and transmitted by aphids except CpCDV which is always transmitted by leafhoppers. They are not transmitted mechanically or by seed and can have a marked effect on yield. The most important viruses affecting lentil causing mosaic and mottling (Plate 3D, E) are: PSbMV, CMV, PEMV-1, PeSV, BYMV, Alfalfa mosaic virus (AMV) and Broad bean stain virus (BBSV). Symptoms caused by these viruses are often confused with those resulting from nutrient deficiency, physiological disorders, herbicide damage or waterlogging. Several viruses impair the quality of lentil seeds thereby rendering them less attractive to consumers. For example, BBSV infection leads to undesirable staining of lentil seedcoats, which makes the grain unsuitable for marketing (Plate 3F).

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Viruses causing yellowing and stunting symptoms Bean leafroll virus (BLRV) Lentil plants infected naturally with BLRV were first observed in Iran by Kaiser et al. (1968), and it is known to be among the most important viruses that infect lentil. The virus is reported to occur on lentil in Bangladesh, Ethiopia, Iran, Iraq, Syria, Tunisia and the USA (Kaiser, 1973; Klein et al., 1991; Bakr, 1993; Tadesse et al., 1999; El-Muadhidi et al., 2001; Kumari, 2002; Makkouk et al., 2003b). A yield reduction of 91% has been reported when plants were infected with BLRV at the pre-flowering stage, while at the flowering stage infection may result in only 50% yield loss (Kaiser et al., 1968). In Washington, USA, up to 80% disease incidence was noted in some fields during an epidemic year (Klein et al., 1991). Infection with BLRV is restricted to legume species including faba bean, lentil, pea and chickpea in many parts of the world (Bos et al., 1988; Makkouk et al., 2003a). The main symptoms produced by the virus are interveinal chlorosis, yellowing, stunting, leaf rolling, reddening and thickening of the leaves and suppression of flowering and pod set. Entire leaflets can turn red in cool temperatures. BLRV is transmitted only by aphids in a persistent, non-propagative manner. Acyrthosiphon pisum Harris, Aphis craccivora Koch., Aphis fabae (Scopoli) and Myzus persicae (Sulz.) are the most common aphid species reported to transmit BLRV (Kaiser, 1973; Cockbain, 1983). Beet western yellows virus (BWYV) BWYV was first isolated by Duffus (1961) in California and is synonymous with Malva yellows virus and turnip mild yellows virus. BWYV occurs on lentil in Ethiopia, Iran, New Zealand, Pakistan, Syria and Turkey (Fletcher, 1993; Tadesse et al., 1999; Makkouk et al., 2001a, 2003b; Kumari, 2002). BWYV is not restricted to leguminous species as in the case of other legume luteoviruses (e.g. BLRV). It infects many crop and weed species, which belong to the families Brassicaceae and Compositae in addition to Fabaceae. Symptoms of BWYV on lentil include yellowing or bronzing with leaflets becoming leathery and brittle. Usually, leaf margins become reddish, but the entire leaflets may turn red under cool conditions. Plants are severely stunted or may die if infected early. Internodes become shortened in the upper plant parts infected at a late growth stage. Pods in the infected plants are reduced in size and poorly filled or may remain seedless. BWYV is aphid transmitted in a persistent, non-propagative manner. The main aphid vectors are M. persicae, A. craccivora, A. pisum and Aulacorthum solani (Kltb.) (Boswell and Gibbs, 1983; Cockbain, 1983). Chickpea chlorotic dwarf virus (CpCDV) CpCDV was first reported on chickpea in India (Horn et al., 1993), and later in Egypt, Ethiopia, Iran, Iraq, Pakistan, Sudan, Syria and Yemen (Makkouk

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et al., 2003a). It occurs on lentil in Pakistan and Iran (Makkouk et al., 2001a, 2003b). Crop loss is proportional to virus incidence in the field, as CpCDVinfected plants produce little or no grain. The virus is reported to naturally infect chickpea, lentil, faba bean (Makkouk et al., 2003a), sugarbeet and bean in Iran (Farzadfar et al., 2002), and Phaseolus bean and other wild species in Sudan (Ali et al., 2004). The main symptoms of CpCDV are reddening or yellowing of leaflets with severe stunting. CpCDV is transmitted by leafhopper in a circulative non-propagative manner, such as Orosius orientalis (Matsumura) in India (Horn et al., 1993) and Orosius albicinctus Distant in Syria (Kumari et al., 2004). Faba bean necrotic yellows virus (FBNYV) FBNYV was first reported from faba bean near Lattakia, Syria (Katul et al., 1993), and was later reported on lentil in Ethiopia, Iran, Iraq, Pakistan, Syria and Turkey (Makkouk et al., 1992, 2001a, 2003b; Bayaa et al., 1998; Tadesse et al., 1999; El-Muadhidi et al., 2001). In epidemic years the virus can be very damaging, as observed in Middle Egypt during 1992, 1997 and 1998, and in Tunisia in 2001. In Middle Egypt, losses due to FBNYV infection on faba bean during 1992 reached 80–90% (Makkouk et al., 1994). In West Asia and North Africa, FBNYV is considered the most damaging virus on food legume crops. FBNYV is reported to naturally infect faba bean, pea, chickpea, lentil, cowpea, Egyptian clover, French bean and many forage legume species (Katul et al., 1993; Makkouk et al., 1998, 2003a). Leaves of infected plants become thick and brittle and show interveinal chlorotic blotches starting from the leaf margins. The uppermost young leaves remain very small and cupped upwards, whereas the older leaves are rolled downwards. New shoots, leaves and flowers develop poorly. Approximately 3–4 weeks after infection is established, interveinal chlorosis becomes necrotic and plants then die within 5–7 weeks. The host range of FBNYV is restricted to the family Fabaceae. Three aphid species, A. pisum, A. craccivora and A. fabae are the reported vectors of FBNYV in a circulative non-propagative manner (Franz et al., 1998; Makkouk et al., 1998).

Viruses causing mosaic and mottling Bean yellow mosaic virus (BYMV) BYMV was reported in lentil by Kaiser et al. (1968) in Iran, with high reductions in yield (Kaiser, 1973). The virus occurs on lentil in Bangladesh, Egypt, Ethiopia, Iran, Iraq, Jordan, New Zealand, Syria and Turkey (Kaiser, 1973; Russo et al., 1981; Makkouk et al., 1992, 1993, 2003b; Bakr, 1993; Fletcher, 1993; Bayaa et al., 1998; Tadesse et al., 1999; Al-Mabrouk and Mansour, 2000; El-Muadhidi et al., 2001). BYMV is reported to occur on several other legumes

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including pea, faba bean and chickpea in North America, Europe, Africa, Asia and Australasia, as well as a few non-legume hosts (Bos et al., 1988; Makkouk et al., 2003a). The effect of BYMV on yield depends, to a great extent, on the time of infection and virus strain. In a field experiment in Syria, sap inoculation of lentil with BYMV at pre-flowering and flowering stages led to 96 and 34% yield reductions, with seed transmission rates of 0.83 and 0.3%, respectively (Kumari et al., 1994). BYMV symptoms on lentil include chlorosis, mild mosaic or mottling, and stunting. Leaves often become twisted or curled with necrosis along the margins. Flowering and pod formation is reduced as a result of infection and consequently little seed is produced. BYMV is transmitted mechanically and by aphids in a non-persistent manner. Acyrthosiphon pisum, A. fabae, A. craccivora, M. persicae and Macrosiphum euphorbiae (Thomas) are among the most common aphid vectors (Cockbain, 1983; Edwardson and Christie, 1986). Broad bean stain virus (BBSV) Lentil has been reported to be infected by BBSV under natural conditions (Bos et al., 1988; Makkouk et al., 2003a). In addition to lentil, the virus occurs naturally on pea, faba bean and several other legumes in Europe, Africa, Asia and Australasia. It was reported also to occur on lentils in Ethiopia, Iran, Jordan, Syria and Turkey (Makkouk et al., 1987, 1992, 2003b; Bayaa et al., 1998; Tadesse et al., 1999; Al-Mabrouk and Mansour, 2000). In lentils, very mild mottling occurs in response to BBSV infection which is often not readily observable. Grain yield losses varied from 14% to 61% and the seed transmission rates of BBSV were found to range from 0.2% to 32.4% when 19 lentil genotypes were inoculated at the flowering stage (Makkouk and Kumari, 1990). Infection of lentil plants at pre-flowering, flowering and pod stages resulted in seed transmission rates of 20.6, 19.1 and 1.5%, respectively (Kumari et al., 1993). BBSV also has been detected in grower’s seed in Turkey (Fidan and Yorganci, 1990). BBSV is transmitted primarily by beetle species Apion aestivum Germ., Apion arrogans Wencher, Sitona crinita Herbst, Sitona limosa Rossi and Sitona lineatus L. (Cockbain et al., 1975; Makkouk and Kumari, 1989, 1995). Cucumber mosaic virus (CMV) CMV was first recorded to infect lentil in Iran (Kaiser et al., 1968). The virus naturally infects lentil in Australia, Ethiopia, India, Iran, Nepal, New Zealand, Pakistan and Syria (Kaiser, 1973; Rangaraju and Chenulu, 1981; Fletcher, 1993; Karki, 1993; Mouhanna et al., 1994; Jones and Coutts, 1996; Tadesse et al., 1999; Makkouk et al., 2001a). The virus is reported to cause economic losses in chickpea and lentil crops in West Australia (Jones and Coutts, 1996), and has caused a significant reduction in lentil yields in Iran (Kaiser, 1973). In India, the incidence of CMV on different lentil cultivars varied from 5 to 100% (Rangaraju and

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Chenulu, 1981), and in New Zealand virus incidence was below 11%, and three fields were found with 77, 87 and 93% CMV infection (Fletcher, 1993). In 1995 experimental plots of lentil varieties ‘Rajah’ and ‘Titore’ inoculated with CMV yielded 17% and 19% less, respectively, than the uninoculated control (Fletcher et al., 1999). Kaiser (1973) reported yield reductions of 87% and 75% when the lentil cultivar ‘Ghazvin’ was inoculated with CMV at pre-flowering and flowering stages, respectively. CMV has a wide host range and infects more than 800 species of both monocotyledonous and dicotyledonous plants from over 85 families. It is also reported to naturally infect pea, faba bean and chickpea (Bos et al., 1988). The symptoms produced in response to CMV infection include interveinal chlorosis, growth stunting, proliferation of axillary shoots and a reduction in leaf size, with adverse effects on flower and pod formation. Seeds produced are small, discoloured and shrivelled (Kaiser, 1973; Rangaraju and Chenulu, 1981). CMV is transmitted mechanically and by over 60 aphid species in a non-persistent manner. The main aphid vectors are A. pisum, A. fabae, A. craccivora, M. persicae, M. euphorbiae, Rhopalosiphum padi L. and A. solani (Edwardson and Christie, 1986). The virus is reported to be seed-transmitted in lentil (Jones and Coutts, 1996; Makkouk and Attar, 2003). Pea enation mosaic virus-1 (PEMV-1) What is commonly referred to as Pea enation mosaic virus is a symbiotic coinfection of two viruses, Pea enation mosaic virus-1 (PEMV-1, genus Enamovirus, family Luteoviridae) and Pea enation mosaic virus-2 (PEMV-2, genus Umbravirus, not assigned to a family). The disease is often simply referred to by the acronym PEMV. PEMV-1 is readily transmitted mechanically, a property dependent on its multiplication in cells co-infected with PEMV-2. PEMV-1 and PEMV-2 are transmitted by several aphid species, such as A. pisum, A. craccivora, M. persicae, M. euphorbiae, R. padi and A. solani (Cockbain, 1983; Edwardson and Christie, 1986). Natural occurrence of the virus on lentil was reported in Italy by Vovlas and Rana (1972), in Ethiopia (Tadesse et al., 1999) and Iran (Makkouk et al., 2003b). It was found also to occur in the USA (Aydin et al., 1987), especially in the Palouse region (Kaiser, 1987). It is also found in Europe and Asia (Bos et al., 1988; Kumari et al., 2001; Makkouk et al., 2003a). Surveys conducted in Syria during the period 1997–2001 showed that PEMV-1 was widely distributed in the major lentil-growing areas, with virus incidence reaching more than 50% at some locations. When six lentil genotypes inoculated with PEMV-1 before flowering were evaluated, yield losses varied from 16% (ILL 7706) to 50% in ILL 6031 (Kumari et al., 2001). Symptoms caused by PEMV-1 and PEMV-2 in lentil include reduced growth, leaf rolling, leaf mottling, tip wilting and plant necrosis. Infected plants are severely stunted with twisted and malformed leaves that frequently exhibit vein clearing and translucent flecks. Pods from infected plants also are misshapen, poorly filled and often show protrusions on the

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surface. These symptoms were severe in lentil fields in Syria (Kumari et al., 2001) and in chickpea and lentil fields in eastern Washington (Klein et al., 1991). In addition to lentil, PEMV-1 is reported to infect pea, French bean, soybean, faba bean, chickpea and several other legume hosts. Pea seed-borne mosaic virus (PSbMV) The natural occurrence of PSbMV in lentil fields was first reported from the USA (Hampton and Muehlbauer, 1977). The virus is known to occur on lentils in Algeria, Egypt, Ethiopia, Iran, Iraq, Jordan, Morocco, New Zealand, Pakistan, Syria, Tunisia, Turkey and the USA (Hampton and Muehlbauer, 1977; Hampton, 1982; Aftab et al., 1992; Makkouk et al., 1992, 1993, 2001a, 2003b; Fletcher, 1993; Kassim, 1997; Bayaa et al., 1998; Tadesse et al., 1999; Al-Mabrouk and Mansour, 2000). There are several strains of PSbMV but the three most common strains include P-1 and P-4 isolated from Pisum sativum and the L-1 strain from lentil (Alconero et al., 1986). All three strains infect lentil and chickpea. The L-1 strain causes a more severe reaction on chickpea and lentil than P-1 or P-4. In Pakistan Aftab et al. (1992) noted severe mosaic symptoms of PSbMV on lentil cultivar ‘Precoz’ showing chlorotic lesions on leaves, stunting of plants with shortening of internodes and a reduction in flower and pod formation. The decrease in plant height, number of pods, number of seeds and yield per plant as a result of infection was 51, 58, 66 and 73%, respectively. Kumari et al. (1993) reported 28, 27 and 23% yield losses in the field due to lentil PSbMV infection at pre-flowering, flowering and post-flowering stages, respectively. Symptoms may vary in lentil due to genotype, virus strain and environmental effects. Other symptoms of infection include narrowed leaves, downward leaf rolling, mottling or chlorosis of the leaves with shoot tip necrosis and reduced seed size. Seed-filled pods may be abnormal in shape and size. Necrotic line patterns that are common on infected pea and faba bean seeds are rare on lentil seeds. Yield losses from PSbMV infection in Syria varied from 3% in the cultivar ‘Redchief’ to 61% in ILL 6245 when 20 lentil genotypes were inoculated mechanically with PSbMV at flowering; however, four genotypes (ILL 6198, ‘Crimson’, ‘Palouse’ and ‘Redchief’) were found highly tolerant to infection (Kumari and Makkouk, 1995). PSbMV is transmitted mechanically and by several aphid species including A. pisum, A. fabae, A. craccivora, M. persicae and R. padi in the nonpersistent manner (Makkouk et al., 1993). Seed transmission rates of PSbMV in lentil vary widely (0–44%) depending on host and virus isolate (Hampton and Muehlbauer, 1977; Makkouk et al., 1993; Kumari and Makkouk, 1995; Abraham and Makkouk, 2002). Pea streak virus (PeSV) PeSV was first reported on lentils in the USA (Hagedorn and Walker, 1949), Canada and Germany (Bos, 1973). The host range is relatively small and includes pea, lentil, faba bean, chickpea (Kaiser et al., 1993) and the forage

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legumes lucerne and clover. PeSV was found to infect lentil under natural conditions in the Palouse region of the USA (Kaiser, 1987). The most common symptoms associated with PeSV include stunting, yellowing of leaflets and wilting of the terminal shoots. Vascular discoloration also may be observed, a condition that contributes to plant death, especially at the seedling stage. Pods, when formed, are poorly filled and seeds are misshapen. PeSV is transmitted by mechanical inoculation and by the pea aphid (A. pisum) in a non-persistent manner. It is not transmitted by seed or by pollen.

Other viruses In addition to the viruses mentioned above, other viruses of lesser significance were reported to cause damage to lentil in specific countries and in limited areas, such as AMV (Kaiser et al., 1968; Jones and Coutts, 1996; AlMabrouk and Mansoor, 2000; Makkouk et al., 2003b; Bekele et al., 2005), broad bean mottle virus (BBMV) in Morocco (Fortass and Diallo, 1993), Ethiopia (Bekele et al., 2005) and Syria (Mouhanna et al., 1994), Broad bean wilt virus-1 (BBWV-1) in Syria (Makkouk et al., 1992), Tomato spotted wilt virus (TSWV) in Brazil (Fonseca et al., 1995), Chickpea chlorotic stunt virus (CpCSV) in Ethiopia (Abraham et al., 2006), Syria and Tunisia (Kumari et al., 2007), and Soybean dwarf virus (SbDV) in Australia (Johnstone and Guy, 1986), Japan (Tamada, 1973), Ethiopia and Syria (Makkouk et al., 1997).

19.3. Epidemiology All viruses of major importance in lentil crops are mostly transmitted by insect vectors (Table 19.1). The viruses transmitted by aphids in a nonpersistent manner (e.g. BYMV, PeSV and PSbMV) are acquired by the vector within a few seconds, transmission can occur in an equally short period, aphids remain viruliferous for only short periods of time, and they can spread the virus over short distances. In contrast, the persistently transmitted viruses (e.g. BLRV, FBNYV and PEMV-1) can be retained and transmitted in most cases for the life of the vector although transmission efficiency is reduced significantly in adults compared to the early nymphal stages. The persistently transmitted viruses require an acquisition period of several minutes to several hours. The latent period in the vector can range from a few hours (PEMV-1) to more than 100 h (BLRV). The inoculation access period can be for few minutes or as long as 1 h. The persistently transmitted viruses can spread over long distances, with the ability of an individual insect to transmit them to many plants. Table 19.3 summarizes the most important vectors reported to transmit lentil viruses worldwide. Weed hosts, and perennial crops such as lucerne, vetch and clover are the main sources of inoculum for many of the viruses that infect lentil. Most nonpersistently transmitted viruses that infect lentil are also seed-transmissible.

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Table 19.3. Major insect vectors reported to transmit lentil viruses. Vector Aphids: Acyrthosiphon pisum Harris

Aphis fabae (Scopoli)

Aphis craccivora Koch.

Myzus persicae (Sulz.)

Macrosiphum euphorbiae (Thomas) Rhopalosiphum padi L. Aulacorthum solani (Kltb.) Beetles: Acalymma trivittata Mannerheim Apion aestivum Germ. Apion aethiops Hbst. Apion arrogans Wencher Apion radiolus Kirby Apion vorax Hbst.

Viruses transmitted

References

AMV, BBWV, BLRV, BWYV, BYMV, CMV, FBNYV, PEMV, PeSV, PSbMV, SbDV AMV, BBWV, BLRV, BYMV, CMV, FBNYV, PSbMV AMV, BBWV, BLRV, BWYV, BYMV, CMV, FBNYV, PEMV, PSbMV AMV, BBWV, BLRV, BWYV, BYMV, CMV, PEMV, PSbMV AMV, BBWV, BLRV, BYMV, CMV, PEMV CMV, PEMV, PSbMV AMV, BWYV, CMV, PEMV, SbDV

Cockbain (1983), Edwardson and Christie (1986), Makkouk et al. (1990, 1993, 1997), Franz et al. (1998), Kumari et al. (2001) Kaiser (1973), Cockbain (1983), Edwardson and Christie (1986), Makkouk et al. (1990, 1993) Boswell and Gibbs (1983), Cockbain (1983), Edwardson and Christie (1986), Makkouk et al. (1990, 1993), Franz et al. (1998) Cockbain (1983), Edwardson and Christie (1986), Makkouk et al. (1990, 1993), Kumari et al. (2001) Cockbain (1983), Edwardson and Christie (1986) Edwardson and Christie (1986), Makkouk et al. (1993) Cockbain (1983), Edwardson and Christie (1986)

BBMV

Walters and Surin (1973)

BBSV BBSV, BBTMV BBMV, BBSV BBMV BBMV, BBSV, BBTMV

Colaspis ﬂavida Say Diabrotica undecimpunctata Mannerheim Hypera variabilis Herbst Pachytychius strumarius Gyll Sitina lineatus var. viridifrons Motsch Sitona crinita Herbst Sitona limosa Rossi Sitona lineatus L.

BBMV BBMV

Cockbain et al. (1975) Cockbain et al. (1975) Makkouk and Kumari (1989, 1995) Fortass and Diallo (1993) Cockbain et al. (1975), Cockbain (1983) Walters and Surin (1973) Walters and Surin (1973)

BBMV BBMV BBMV

Fortass and Diallo (1993) Fortass and Diallo (1993) Borges and Louro (1974)

BBSV BBMV, BBSV BBMV, BBSV, BBTMV

Smicronyx cyaneus Gyll Spodoptera exigua Hübner Leafhoppers: Orosius orientalis (Matsumura)

BBMV BBMV

Makkouk and Kumari (1995) Makkouk and Kumari (1995) Cockbain et al. (1975), Fortass and Diallo (1993), Makkouk and Kumari (1995) Fortass and Diallo (1993) Ahmed and Eisa (1999)

CpCDV

Horn et al. (1993)

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Table 19.4. Viruses that can be transmitted through lentil seeds. Virus AMV BYMV BBSV CMV

PSbMV

Seed transmission rate (%) 0.1–5.0 0.1–1.4 0.3–0.83 0.8 14.0 0.1–1.0 0.05–37.0 0.1–9.5 5.0–44.0 6.0

References Jones and Coutts (1996) Makkouk and Attar (2003) Kumari et al. (1994) Jones and Coutts (1996) Makkouk and Azzam (1986) Jones and Coutts (1996) Fletcher et al. (1999) Makkouk and Attar (2003) Hampton and Muehlbauer (1977) Makkouk et al. (1993)

Virus transmission via seed is of dual importance. The virus-infected seeds act both as source of inoculum and as vehicle of virus dissemination. Of the 20 viruses reported to infect lentil, five are seed-transmitted (Table 19.4). Viruses that infect the embryo may also be transmitted by pollen although this occurs rarely in lentil. Infection of lentil after flowering rarely leads to seed infection. Usually infected seeds appear normal except in some cases where visible symptoms are observed on stained seeds, as in the case of infection by BBSV.

19.4. Virus Detection Early detection and accurate diagnosis of viral diseases is critical for application of appropriate control measures. It is also important to determine the area of distribution. The last three decades have witnessed significant developments in improving the sensitivity of the methods to detect lentil viruses.

Immunological protein-based methods The development of enzyme-linked immunosorbent assay (ELISA) for plant viruses (Clark and Adams, 1977) was a major step forward that replaced earlier serological methods such as gel diffusion, especially for large-scale testing. This was enhanced further with the development of monoclonal antibody technology and its application to a large number of legume viruses. Specific reagents (monoclonal and/or polyclonal antibodies) have been developed for most viruses affecting lentil, and using them in a variety of ELISA tests available has made lentil virus diagnosis simple and fast. At present, antibodies for detecting most of the lentil viruses are available (Kumari and Makkouk, 2007). A number of ELISA variants were developed which further improved sensitivity of virus testing. In many laboratories in

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developing countries, facilities for sophisticated tests are lacking. For this reason tissue-blot immunoassay (TBIA) was developed to identify most legume viruses (Makkouk and Kumari, 1996). TBIA is a reliable simple test to detect all lentil viruses reported and it is especially recommended for virus surveys (Makkouk et al., 2001a, 2003b) and for evaluating virus-host interactions (Kumari and Makkouk, 2003). Plate 4 illustrates how lentil viruses are detected in infected plants by using TBIA.

Molecular nucleic acid-based methods Nucleic acid hybridization has been used successfully for the detection of many viruses (Pesic and Hiruki, 1988; Martin and D’Arcy, 1990). Cloning of plant viral nucleic acids and the development of non-radioactive detection methods has increased the utility of nucleic acid hybridization for virus detection. The development of polymerase chain reaction (PCR) has greatly improved the sensitivity and utility of hybridization and other nucleic acidbased assays. Immunocapture PCR combines the advantages of serology and PCR (or reverse-transcription PCR (RT-PCR) for RNA viruses) into a very sensitive method of detection (Shamloul et al., 1999). Many primers for detecting lentil viruses by PCR have been reported (Kumari and Makkouk, 2007). This technique has now been adapted for the detection of both DNA and RNA viruses with either single- or double-stranded genomes. In addition to detection of viruses in infected plants, RT-PCR can also be used for detection of viruses in their vectors (Shamloul et al., 1999).

19.5. Control of Virus Diseases As there is no direct practical way of curing crops from virus infection, all current control strategies emphasize measures that prevent or reduce infection. Control measures can be classified as those that: (i) control the virus; (ii) are directed towards avoidance of vectors or reducing their incidence; and (iii) integrated approaches, which combine all possible control components in a way to complement each other and be applied by farmers as a single control package.

Methods directed to control the virus Reducing sources of infection Five viruses affecting lentil are seed-borne (Table 19.4). For these viruses, it is always recommended to use virus-free seed for planting, especially when the virus is also transmitted by active vectors. The use of genotypes or cultivars resistant to the virus or to seed transmission is an effective control measure. Kumari and Makkouk (1995) reported that lentil cultivars ‘Redchief’

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and ‘Palouse’ had the lowest seed transmission rate of PSbMV with the lowest yield loss among the 20 lentil genotypes evaluated. In another study, they found that ‘Redchief’ had the lowest seed transmission rate (0.2%) and lowest yield loss (14%) among the 19 lentil genotypes evaluated (Makkouk and Kumari, 1990). Seed transmission of BBSV was reduced to zero when seeds were exposed to 70°C for 28 days; however, this treatment caused an unacceptable reduction (57%) in seed germination (Kumari and Makkouk, 1996). Such an approach could be useful to eliminate seed infection in germplasm accessions deposited in genebanks, but is not economical for commercial production. Roguing symptomatic plants is a widely used phytosanitary measure to remove sources of virus infection from standing crops. However, when virus incidence within a field is high, this control measure may not be practical. Over-wintering or over-summering crops, which could play the role of sources of infection, should be avoided through spatial isolation. Such methods are more effective with non-persistent viruses than with persistent viruses. With non-persistent viruses, such as BYMV, a few hundred metres isolation may adequately reduce virus spread. In contrast, persistently transmitted viruses such as BLRV can be carried from lucerne fields over long distances making it more difficult to avoid. Breeding for virus resistance Host resistance, when available, is the most acceptable component of virus control because it is environment friendly, practical and economically acceptable to farmers. Several workers have reported lentil lines resistant to viruses. Four accessions (PI 212610, PI 251786, PI 297745 and PI 368648) are immune to PSbMV. This resistance is controlled by the single recessive gene sbv (Haddad et al., 1978). Accessions PI 212611, PI 212903, PI 343025, PI 370632 and PI 379368 were also found to be resistant, and PI 368648 was immune to PSbMV (Hampton, 1982). Genotypes PI 472547 and PI 472609 were reported to be tolerant to PEMV (Aydin et al., 1987). The genotype ILL 7163 displayed a high level of resistance to BYMV and moderate resistance to CMV (McKirdy et al., 2000; Latham et al., 2001), while genotype ILL 5480 was moderately resistant to AMV (Latham and Jones, 2001). Six lentil genotypes were identified with combined resistance to different viruses (Makkouk et al., 2001b): ILL 75 had resistance to BLRV, FBNYV and SbDV; and ILL 74, ILL 85, ILL 213, ILL 214 and ILL 6816 were resistant to FBNYV and BLRV. Two cultivars from the USA, ‘Redchief’ and ‘Palouse’, were highly tolerant to PSbMV infection. This tolerance was expressed as very low grain yield loss due to infection and with a low seed transmission rate (Kumari and Makkouk, 1995). ‘Redchief’ was also reported to be tolerant to BBSV earlier with low seed-transmission rates (Makkouk and Kumari, 1990). At present, a number of legumes are being transformed with viral genes (coat protein, replicase, etc.) to produce virus-resistant varieties (Chowrira et al., 1998; Chu et al., 1999). No genetically transformed cultivars are available in the market for immediate use by farmers, but genetic transformation could

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be a useful alternative, especially for viruses against which no resistance genes have been identified.

Methods directed towards avoidance of vectors or reducing their incidence Cultural practices Various practices such as planting date, high seeding rate and narrow row spacing, use of early maturing cultivars, and using border plantings that are a non-host of the virus have proved effective in reducing virus incidence in lentil crops. Manipulation of planting date to avoid exposure of plants to peak vector populations at the most vulnerable early growth stages is a standard virus control measure widely recommended for use in legume crops (Thresh, 2003). Virus vector control (chemical control) Application of insecticides helps to decrease the spread of some lentil viruses vectored by insects. However, it is often ineffective because its success depends on the mechanism of virus transmission and the mode of action of the insecticide selected. In general, success in reducing virus spread by chemical control of vectors is considerably greater with persistently than with non-persistently transmitted viruses. This is mostly because the incoming viruliferous vectors carrying non-persistently transmitted viruses are not killed fast enough to prevent probing and subsequent virus inoculation to the sprayed plants. Oil sprays can be used instead, but are not always cost effective because of the repeated applications required. The most effective insecticides to control non-persistently aphid-borne viruses are the newer generation of synthetic pyrethroids (Loebenstein and Raccah, 1980), because of their rapid breakdown and greater anti-feedant activity. Field experiments at ICARDA showed that seed treatment with the systemic insecticide imidacloprid (Gaucho®) significantly improved yields of moderately resistant and susceptible lentil genotypes, but had no effect on the yield of resistant genotypes. Seed treatment was also effective in increasing seed yield of BLRV and FBNYV-inoculated plots, but had no effect in SbDV-inoculated plots (Makkouk and Kumari, 2001).

Integrated approach Each of the control measures described in this chapter provides only partial control, but combining genetic resistance, cultural practices and chemical sprays is expected to check virus spread. The use of host resistance, whether obtained by classical breeding or genetic engineering, and one or two welltimed insecticide applications coupled with optimal planting date and early roguing of virus-infected plants could offer reasonable and economic virus disease control and stabilize lentil production. However, selecting the best

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mix of measures for each virus-crop combination and production situation requires knowledge of the epidemiology of the causal virus and the mode of action and effectiveness of each individual control measure. Each strategy must be affordable to the farmer and fulfill the requirements of being environmentally friendly and socially acceptable. It should also be compatible with control measures already in use against other pests and pathogens.

19.6. Concluding Remarks This chapter has described the major aspects of the economically important viruses of lentil. Certainly, not all viruses have been discussed because of space constraints. There are many other minor viruses which may be of local importance in lentil that have not been discussed here. In addition, new viruses or their strains are expected to be discovered or introduced that will affect lentil. For example, CpCSV has recently been reported on lentil and chickpea in Ethiopia and on other food legume crops in Syria (Abraham et al., 2006; Kumari et al., 2007). This new virus might become important for lentil with time. Work is currently in progress to study the etiology, epidemiology and economic importance of this novel virus. Lentil is an important crop for the resource-poor farmers in developing countries. Therefore disease control measures must be practicable, affordable and suitable for situations in these countries. In addition, agricultural researchers, breeders, extension agents and growers must continually adjust disease management strategies to cope with changing conditions.

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Bakr, M.A. (1993) Plant protection of lentil Bangladesh. In: Erskine, W. and Saxena, M.C. (eds) Lentil in South Asia. Proceedings of the Seminar on Lentils in South Asia, 11–15 March 1991, New Delhi, India. International Center for Agricultural Research in the Dry Areas (ICARDA), Aleppo, Syria, pp. 177–184. Bayaa, B., Kumari, S.G., Akkaya, A., Erskine, W., Makkouk, K.M., Turk, Z. and Ozberk, I. (1998) Survey of major biotic stresses of lentil in South-East Anatolia, Turkey. Phytopathologia Mediterranea 37, 88–95. Bekele, B., Kumari, S.G., Ali, K., Yusuf, A., Makkouk, K.M., Aslake, M., Ayalew, M., Girma, G. and Hailu, D. (2005) Survey for viruses affecting legume crops in Amhara and Oromia Regions in Ethiopia. Phytopathologia Mediterranea 44, 235–246. Borges, M.D. and Louro, O. (1974) A biting insect as a vector of broad bean mottle virus? Agronomia Lusitiana 36, 215–216. Bos, L. (1973) Pea Streak Virus. Description of Plant Viruses No. 112. Commonwealth Mycological Institute, Key, Surrey, UK, 4 pp. Bos, L., Hampton, R.O. and Makkouk, K.M. (1988) Viruses and virus diseases of pea, lentil, faba bean and chickpea. In: Summerfield, R.J. (ed.) World Crops: Cool Season Food Legumes. Kluwer Academic Publishers, Dordrecht, The Netherlands, pp. 591–615. Boswell, K.F. and Gibbs, J. (1983) Viruses of Legumes: Descriptions and Keys from Virus Identiﬁcation and Data Exchange. Australian National University, Canberra, 139 pp. Chowrira, G.M., Cavileer, T.D., Gupta, S.K., Lurquin, P.F. and Berger, P.H. (1998) Coat protein-mediated resistance to pea enation mosaic virus in transgenic Pisum sativum L. Transgenic Research 7, 265–271. Chu, P.W.G., Anderson, B.J., Khan, M.R.I., Shukla, D. and Higgins, T.J.V. (1999) Production of bean yellow mosaic virus resistant subterranean clover (Trifolium subterraneum) plants by transformation with the virus coat protein gene. Annals of Applied Biology 135, 469–480. Clark, M.F. and Adams, A.N. (1977) Characteristics of the microplate method of enzyme-linked immunosorbent assay for the detection of plant viruses. Journal of General Virology 34, 475–483. Cockbain, A.J. (1983) Viruses and virus-like disease of Vicia faba L. In: Hebblethwaite P.D. (ed.) The Faba Bean (Vicia faba L.). Butterworths, London, UK, pp. 421–461. Cockbain, A.J., Cook, S.M. and Bowen, R. (1975) Transmission of broad bean stain virus and Echtes Ackerbohnenmosaik Virus to field beans (Vicia faba) by weevils. Annals of Applied Biology 81, 331–339. Duffus, J.E. (1961) Economic significance of beet western yellows (radish yellows) on sugar beet. Phytopathology 51, 605–607. Edwardson, J.R. and Christie, R.G. (1986) Viruses Infecting Forage Legumes. Monograph 14 (three volumes). Florida Agricultural Experiment Stations, Gainesville, Florida, USA, 742 pp. El-Muadhidi, M.A., Makkouk, K.M., Kumari, S.G., Jerjess, M., Murad, S.S., Mustafa, R.R. and Tarik, F. (2001) Survey for legume and cereal viruses in Iraq. Phytopathologia Mediterranea 40, 224–233. Farzadfar, S., Pourrahim, R., Golnaraghi, A.R., Shahraeen, N. and Makkouk, K.M. (2002) First report of sugar beet and bean as natural hosts of chickpea chlorotic dwarf virus in Iran. Plant Pathology 51, 795. Fauquet, C.M., Mayo, M.A., Maniloff, J., Desselberger, U. and Ball, L.A. (2005) Virus Taxonomy: Classiﬁcation and Nomenclature of Viruses. Eighth Report of the International Committee on Taxonomy of Viruses. Elsevier Academic Press, San Diego, California, USA, 1259 pp.

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S.G. Kumari et al. Fidan, U. and Yorganci, U. (1990) Investigations on the detection and seed transmission of the virus diseases occurring on the pulse crops in the Aegean region. II. Seed transmission of virus diseases by grower seed and seeds of artificially infected pulse crops. Journal of Turkish Phytopathology 19, 1–5. Fletcher, J.D. (1993) Surveys of virus disease in pea, lentil, dwarf and broad bean crops in South Island, New Zealand. New Zealand Journal of Crop and Horticultural Science 21, 45–53. Fletcher, J.D., Russell, A.C. and Butler, R.C. (1999) Seed-borne cucumber mosaic virus in New Zealand lentil crops: yield affects and disease incidence. New Zealand Journal of Crop and Horticultural Science 27, 197–204. Fonseca, M.E.N., Botteux, L.S., De Avila, A.C., Lima, M.I. and Kitazima, E.W. (1995) Detection of tomato spotted wilt tospovirus in lentil. Plant Disease 79, 320. Fortass, M. and Diallo, S. (1993) Broad bean mottle bromovirus in Morocco; curculionid vectors, and natural occurrence in food legumes other than faba bean (Vicia faba L.). Netherlands Journal of Plant Pathology 99, 219–226. Franz, A., Makkouk, K.M. and Vetten, H.J. (1998) Acquisition, retention and transmission of faba bean necrotic yellows virus by two of its aphid vectors, Aphis craccivora (Koch) and Acyrthosiphon pisum (Harris). Journal of Phytopathology 146, 347–355. Haddad, N.I., Muehlbauer, F.J. and Hampton, R.O. (1978) Inheritance of resistance to pea seedborne mosaic virus in lentils. Crop Science 18, 613–615. Hagedorn, D.J. and Walker, J.C. (1949) Wisconsin pea streak. Phytopathology 39, 837–847. Hampton, R.O. (1982) Incidence of the lentil strain of pea seed-borne mosaic virus as a contaminant of Lens culinaris germplasm. Phytopathology 72, 695–698. Hampton, R.O. and Muehlbauer, F.J. (1977) Seed transmission of pea seed-borne mosaic virus in lentils. Plant Disease Reporter 61, 235–238. Horn, N.M., Reddy, S.V., Roberts, I.M. and Reddy, D.V.R. (1993) Chickpea chlorotic dwarf virus, a new leafhopper-transmitted geminivirus of chickpea in India. Annals of Applied Biology 122, 467–479. Johnstone, G.R. and Guy, P.L. (1986) Epidemiology of viruses persistently transmitted by aphids. In: Proceedings of the Workshop on Epidemiology of Plant Virus Diseases. IX/1–IX/7 International Society of Plant Pathology, Orlando, Florida, USA, pp. 6–8. Jones, R.A.C. and Coutts, B.A. (1996) Alfalfa mosaic and cucumber mosaic virus infection in chickpea and lentil: incidence and seed transmission. Annals of Applied Biology 129, 491–506. Kaiser, W.J. (1973) Etiology and biology of viruses affecting lentil (Lens esculenta Moench.) in Iran. Phytopathologia Mediterranea 12, 7–14. Kaiser, W.J. (1987) Disease problems on dry peas, lentils, chickpea and faba beans. In: Grain Legumes as Alternative Crops: a Symposium. Centre for Alternative Crops and Products, University of Minnesota, St Paul, Minnesota, USA, pp. 157– 174. Kaiser, W.J., Danesh, D., Okhovat, M. and Mossahebi, H. (1968) Diseases of pulse crops (edible legumes) in Iran. Plant Disease Reporter 52, 687–691. Kaiser, W.J., Klein, R.E., Larsen, R.C. and Wyatt, S.D. (1993) Chickpea wilt incited by pea streak carlavirus. Plant Disease 77, 922–926. Karki, P.B. (1993) Plant protection of lentil in Nepal. In: Erskine, W. and Saxena, M.C. (eds) Lentil in South Asia. Proceedings of the Seminar on Lentils in South Asia, 11–15 March 1991, New Delhi, India. International Center for Agricultural Research in the Dry Areas (ICARDA), Aleppo, Syria, pp. 187–191.

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Kassim, N.A. (1997) Studies on certain viruses on chickpea and lentil in Ninevah Governorate. PhD thesis, University of Mousul, Iraq, pp. 167. Katul, L., Vetten, H.J., Maiss, E., Makkouk, K.M., Lesemann, D.E. and Casper, R. (1993) Characteristics and serology of virus-like particles associated with faba bean necrotic yellows. Annals of Applied Biology 123, 629–647. Klein, R.E., Larson, R.C. and Kaiser, W.J. (1991) Virus epidemic of grain legumes in eastern Washington. Plant Disease 75, 1186. Kumari, S.G. (2002) A study on luteoviruses affecting cool-season food legumes. PhD thesis, Aleppo University, Aleppo, Syria, 230 pp. Kumari, S.G. and Makkouk, K.M. (1995) Variability among twenty lentil genotypes in seed transmission rated and yield loss induced by pea seed-borne mosaic potyvirus infection. Phytopathologia Mediterranea 34, 129–132. Kumari, S.G. and Makkouk, K.M. (1996) Inactivation of broad bean stain comovirus in lentil seeds by dry heat treatment. Phytopathologia Mediterranea 35, 124–126. Kumari, S.G. and Makkouk, K.M. (2003) Differentiation among bean leafroll virus susceptible and resistant lentil and faba bean genotypes on the basis of virus movement and multiplication. Journal of Phytopathology 151, 19–25. Kumari, S.G. and Makkouk, K.M. (2007) Virus diseases of faba bean (Vicia faba L.) in Asia and Africa. Plant Viruses 1, 93–105. Kumari, S.G., Makkouk, K.M. and Ismail, I.D. (1993) Survey of seed-borne viruses in lentil in Syria and their effects on lentil yield. Arab Journal of Plant Protection 11, 28–32. Kumari, S.G., Makkouk, K.M. and Ismail, I.D. (1994) Seed transmission and yield loss induced in lentil (Lens culinaris Med.) by bean yellow mosaic potyvirus. LENS Newsletter 21, 42–44. Kumari, S.G., Makkouk, K.M. and Bayaa, B. (2001) Pea enation mosaic virus-1 infecting lentil in Syria, and further information on its host range, purification, serology and transmission characteristics. Arab Journal of Plant Protection 19, 65–72. Kumari, S.G., Makkouk, K.M., Attar, N., Ghulam, W. and Lesemann, D.-E. (2004) First report of chickpea chlorotic dwarf virus infecting spring chickpea in Syria. Plant Disease 88, 424. Kumari, S.G., Makkouk, K., Asaad, N., Attar, N. and Hlaing Loh, M. (2007) Chickpea chlorotic stunt virus affecting cool-season food legumes in West Asia and North Africa. In: Controlling Epidemics of Emerging and Established Plant Virus Diseases – the Way Forward, Tenth International Plant Virus Epidemiology Symposium, 15–19 October 2007, Hyderabad, India, p. 147 (abstract). Latham, L.J. and Jones, R.A.C. (2001) Alfalfa mosaic and pea seed-borne mosaic viruses in cool season crops, annual pasture, and forage legumes: susceptibility, sensitivity, and seed transmission. Australian Journal of Agricultural Research 52, 771–790. Latham, L.J., Jones, R.A.C. and McKirdy, S.J. (2001) Cucumber mosaic cucumovirus infection of cool season crop, annual pasture and forage legumes: susceptibility, sensitivity, and seed transmission. Australian Journal of Agricultural Research 52, 683–697. Loebenstein, G. and Raccah, B. (1980) Control of non-persistently transmitted aphidborne viruses. Phytoparasitica 8, 221–235. Makkouk, K.M. and Attar, N. (2003) Seed transmission of cucumber mosaic virus and alfalfa mosaic virus in lentil seeds. Arab Journal of Plant Protection 21, 49–52. Makkouk, K.M. and Azzam, O.I. (1986) Detection of broad bean stain virus in lentil seed groups. LENS Newsletter 13, 37–38.

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S.G. Kumari et al. Makkouk, K.M. and Kumari, S.G. (1989) Apion arrogans, a weevil vector of broad bean mottle virus. FABIS Newsletter 25, 26–27. Makkouk, K.M. and Kumari, S.G. (1990) Variability among 19 lentil genotypes in seed transmission rates and yield loss induced by broad bean stain virus infection. LENS Newsletter 17, 31–33. Makkouk, K.M. and Kumari, S.G. (1995) Transmission of broad bean stain comovirus and broad bean mottle bromovirus by weevils in Syria. Journal of Plant Disease and Protection 102, 136–139. Makkouk, K.M. and Kumari, S.G. (1996) Detection of ten viruses by the tissue-blot immunoassay (TBIA). Arab Journal of Plant Protection 14, 3–9. Makkouk, K.M. and Kumari, S.G. (2001) Reduction of spread of three persistently aphid-transmitted viruses affecting legume crops by seed-treatment with imidacloprid (Gaucho®). Crop Protection 20, 433–437. Makkouk, K.M., Bos, L., Azzam, O.I., Katul, L. and Rizkallah, A. (1987) Broad bean stain virus: identification detectability in faba bean leaves and seeds, occurrence in West Asia and North Africa and possible wild hosts. Netherlands Journal of Plant Pathology 93, 97–106. Makkouk, K.M., Kumari, S.G. and Bos, L. (1990) Broad bean wilt virus: host range, purification, serology, transmission characteristics, and occurrence in faba bean in West Asia and North Africa. Netherlands Journal of Plant Pathology 96, 291–300. Makkouk, K.M., Kumari, S.G. and Al-Daoud, R. (1992) Survey of viruses affecting lentil (Lens culinaris Med.) in Syria. Phytopathologia Mediterranea 31, 188–190. Makkouk, K.M., Kumari, S.G. and Bos, L. (1993) Pea seed-borne mosaic virus: occurrence in faba bean (Vicia faba L.) and lentil (Lens culinaris Med.) in West Asia and North Africa, and further information on host range, purification, serology, and transmission characteristics. Netherlands Journal of Plant Pathology 99, 115–124. Makkouk, K.M., Rizkallah, L., Madkour, M., El-Sherbeeny, M., Kumari, S.G., Amriti, A.W. and Solh, M.B. (1994) Survey of faba bean (Vicia faba L.) for viruses in Egypt. Phytopathologia Mediterranea 33, 207–211. Makkouk, K.M., Damsteegt, V., Johnstone, G.R., Katul, L., Lesemann, D.E. and Kumari, S.G. (1997) Identification and some properties of soybean dwarf luteovirus affecting lentil in Syria. Phytopathologia Mediterranea 36, 135–144. Makkouk, K.M., Vetten, H.J., Katul, L., Franz, A. and Madkour, M.A. (1998) Epidemiology and control of faba bean necrotic yellows virus. In: Hadidi, A., Khetarpal, R.K. and Koganezawa, H. (eds) Plant Virus Disease Control. American Phytopathological Society (APS) Press, The American Phytopathological Society, St Paul, Minnesota, USA, pp. 534–540. Makkouk, K.M., Bashir, M., Jones, R.A.C. and Kumari, S.G. (2001a) Survey for viruses in lentil and chickpea crops in Pakistan. Journal of Plant Diseases and Protection 108, 258–268. Makkouk, K.M., Kumari, S., Sarker, A. and Erskine, W. (2001b) Registration of six lentil germplasm lines with combined resistance to viruses. Crop Science 41, 931–932. Makkouk, K.M., Kumari, S.G., Hughes, J.A., Muniyappa, V. and Kulkarni, N.K. (2003a) Other legumes: faba bean, chickpea, lentil, pigeonpea, mungbean, blackgram, lima bean, horegram, bambara groundnut and winged bean. In: Loebenstein, G. and Thottappilly, G. (eds) Virus and Virus-like Diseases of Major Crops in Developing Countries. Kluwer Academic Publishers, Dordrecht, The Netherlands, pp. 447–476. Makkouk, K.M., Kumari, S.G., Shahraeen, N., Fazlali, Y., Farzadfar, Sh., Ghotbi, T. and Reza Mansouri, A. (2003b) Identification and seasonal variation of viral diseases of chickpea and lentil in Iran. Journal of Plant Diseases and Protection 110, 157–169.

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Martin, R.R. and D’Arcy, C.J. (1990) Relationships among luteoviruses based on nucleic acid hybridization and serological studies. Intervirology 31, 23–30. McKirdy, S.J., Jones, R.A.C., Latham, L.J. and Coutts, B.A. (2000) Bean yellow mosaic potyvirus infection of alternative annual pasture, forage and cool season crop legumes: susceptibility, sensitivity and seed transmission. Australian Journal of Agricultural Research 51, 325–345. Mouhanna, A.M., Makkouk, K.M. and Ismail, I.D. (1994) Survey of virus disease of wild and cultivated legumes in the coastal region of Syria. Arab Journal of Plant Protection 12, 12–19. Pesic, Z. and Hiruki, C. (1988) Comparison of ELISA and dot-hybridization for detection of alfalfa mosaic virus in alfalfa pollen. Canadian Journal of Plant Pathology 10, 116–122. Rangaraju, R. and Chenulu, V.V. (1981) Occurrence of intervenal chlorosis of lentil in India. Current Science 50, 191–192. Russo, M., Kishtah, A.A. and Tolba, M.A. (1981) A disease of lentil caused by bean yellow mosaic virus in Egypt. Plant Disease 65, 611–612. Shamloul, A.M., Hadidi, A., Madkour, M.A. and Makkouk, K.M. (1999) Sensitive detection of banana bunchy top and faba bean necrotic yellows viruses from infected leaves, in vitro tissue cultures, and viruliferous aphids using polymerase chain reaction. Canadian Journal of Plant Pathology 21, 326–337. Tadesse, N., Ali, K., Gorfu, D. Abraham, A., Lencho, A., Ayalew, M., Yusuf, A., Makkouk, K.M. and Kumari, S.G. (1999) Survey for chickpea and lentil virus diseases in Ethiopia. Phytopathologia Mediterranea 38, 149–158. Tamada, T. (1973) Strains of soybean dwarf virus. Annals of the Phytopathological Society of Japan 39, 27–34. Taylor, P., Lindbeck, K., Chen, W. and Ford, R. (2007) Lentil diseases. In: Yadav, S.S., McNeil, D.L. and Stevenson, P.C. (eds) Lentil: an Ancient Crop for Modern Times. Springer, Dordrecht, The Netherlands, pp. 291–313. Thresh, J.M. (2003) Control of plant virus diseases in Sub-Saharan Africa: the possibility and feasibility of an integrated approach. African Crops Science Journal 11, 199–223. Vovlas, C. and Rana, G.L. (1972) Market virus diseases of market garden plants in Apulia, VII. Lens esculenta Moench, a natural host of pea enation mosaic virus. Phytopathologia Mediterranea 11, 97–102. Walters, H.J. and Surin, P. (1973) Transmission and host range studies of broad bean mottle virus. Plant Disease Reporter 57, 833–836.

20

Weed Management

Joseph P. Yenish,1 Jason Brand,2 Mustafa Pala3 and Atef Haddad3 1Washington

State University, Pullman, Washington, USA; 2Department of Primary Industries, Horsham, Victoria, Australia; 3International Center for Agricultural Research in the Dry Areas (ICARDA), Aleppo, Syria

20.1. Introduction Lentil competes very poorly with weeds. This poor competitive ability is due in part to the short stature and slow early season growth rates (Basler, 1981). Yield reductions of 20–84% due to competition from weeds have occurred (Saxena and Wassimi, 1980; Salkini and Nygaard, 1983; Knott and Halila, 1986; Kumar and Kolar, 1989; Al Thahabi et al., 1994; Boerboom and Young, 1995; Mohamed et al., 1997). Crop yield losses are primarily a result of competition with weeds for nutrients, moisture and space. However, additional losses are due to weeds harbouring insects and pathogens that adversely affect lentils. Moreover, losses in harvest efficiency and reduced crop quality may result from weed infestations. Actual yield, quality and other losses will vary with the intensity of infestations and species makeup of weed infestations (Bhan and Kukula, 1987). Generally, weeds emerging before or at the time of crop emergence have a greater competitive advantage than those emerging later (O’Donovan et al., 1985; Dieleman et al., 1995; Knezevic et al., 1995; Bosnic and Swanton, 1997). Slow emergence, short plant height and late canopy cover of coolseason legumes in general and lentils specifically, allow weeds to compete effectively. A study by Moes and Domitruk (1995) showed average emergence for lentils, chickpeas, dry peas and wheat of 21, 23, 18 and 17 days after planting, respectively, in a no-tillage system. Moreover, the same study showed average canopy closure of 62, 69, 56 and 53 days after planting for the same respective species. Slower crop emergence and canopy closure provides opportunity for weeds to germinate and establish with little competition from the crop. The earlier weeds emerge relative to the crop, the greater the yield loss if left uncontrolled (Kropff et al., 1992). Early establishing weeds, particularly those emerging before the crop, have a competitive advantage over the later emerging crop and will severely reduce yields if 326

© CAB International 2009. The Lentil: Botany, Production and Uses (eds W. Erskine et al.)

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not controlled. Later emerging weeds will compete with the crop as it produces seed and can directly reduce seed size or quality. Additionally, several important weeds in lentil such as Lathyrus aphaca L., Vicia sativa L. and Vicia hirsuta (L.) Gray, produce seed similar in shape and size to that of lentil and separation from the crop is difficult, resulting in lowered quality and value of the harvested crop (Brand et al., 2007). Seed quality and yield may also be reduced indirectly by weeds interfering with the harvest. Heavy, wet or immature weed vegetation may interfere with mechanical or hand harvest of lentil. Weeds containing sticky latex sap, such as prickly lettuce (Lactuca serriola L.), may cause further problems as the latex disrupts the normal operation of machinery and causes contaminants to adhere to the seed (Yenish, 2007). The critical weed-free period is defined as the period of crop growth during which the crop must be kept weed free to prevent yield loss due to weed interference (Weaver and Tan, 1987; Van Acker et al., 1993). Singh et al. (1996) indicated that weeds could be allowed to grow in lentil from 34 or 41 days after emergence with crop yield losses not greater than 10% (Fig. 20.1).

(a)

(b) 100 Yield (% of weed-free control)

Yield (% of weed-free control)

100 90 80 70 60 50 40 30 20 10

0

70 60 50 40 30 20 0

10 20 30 40 50 60 70 80 90 100 110

0

10 20 30 40 50 60 70 80 90 100 110

(d) 100

100 Yield (% of weed-free control)

Yield (% of weed-free control)

80

10

10 20 30 40 50 60 70 80 90 100 110

(c)

90

90 80 70 60 50 40 30 20 10

0

10 20 30 40 50 60 70 80 90 100 110

90 80 70 60 50 40 30 20 10

Time after lentil emergence (days)

Fig. 20.1. Lentil seed yield response to increasing length of weed-free period (—) and duration of weed-infested period (---) in days after lentil emergence at: (a) Madaba, Jordan, 1988/89; (b) Mshager, Jordan, 1988/89; (c) Mshager, Jordan, 1989/90; and (d) Jubaiha, Jordan, 1989/90 (Source: Singh et al., 1996).

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Seed yield (% of weed-free control)

100 80 60 40 20 0 0

60 72 12 24 36 48 Time after lentil emergence (days)

Fig. 20.2. Lentil seed yield response to increasing length of weed-free period (—) and duration of weed-infested period (---) in days after lentil emergence at Rubatab, Sudan, 1992–1994 (Source: Mohamed et al., 1997).

This research was conducted at four non-irrigated locations in Jordan and also concluded that crop yield losses were not greater than 10% when weeds were controlled from emergence up to 85 or 99 days after emergence. Figure 20.2 shows the critical weed-free period between 2 and 4 weeks after seeding for a study conducted in Sudan under irrigation (Mohamed et al., 1997). A study in Tunisia estimated the critical weed-free period for lentil at 16 weeks after emergence for a location with a low to medium severity of weed infestation and 4 weeks for a separate location where the infestation was described as severe (Knott and Halila, 1986). An Australian study conducted by McDonald et al. (2007) indicated that lentil loss due to weed density followed the yield loss model described by Cousens (1985a, b). Additionally, the study showed that the actual yield loss response varied with variety and environment. Maximum yield loss due to weeds in the McDonald study varied from 50 to 60% between years and locations (Fig. 20.3). Tepe et al. (2005) showed yield losses due to weeds differed between lentil cultivars at the same weed density in a study conducted in Turkey. Comparisons of lentil yields in weedy and weed-free treatments resulted in measured yield losses of 35–67% depending on the cultivar. However, the ranked order of yield loss for the cultivars was different between the 2 years of the study. The study did not identify any particular lentil trait that may have influenced its ability to compete with or tolerate competition with weeds.

20.2. Problem Weeds The species of weeds commonly infesting lentil fields vary with changing production environments. Soil characteristics, moisture amount, precipitation

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2500 Minlaton 2002

Minlaton 2003

Horsham 2003

Lentil yield (kg/ha)

2000

1500

1000

500

0 0

10

20

30

40

50

60

Canola density (plant/m2)

Fig. 20.3. Relationship between weed (volunteer canola) density and lentil yield at Minlaton, South Australia in 2002 and 2003 and Horsham, Victoria in 2003 (Source: McDonald et al., 2007).

pattern, crop rotation, temperature, latitude, altitude, fertility, weed control technology and other factors interact to determine weed flora and intensity. Generally, weeds causing significant losses in lentils are categorized as annual monocots, annual dicots, perennial monocots, perennial dicots and parasitic (Table 20.1). Production manuals for the various cropping regions are the best local sources for identification, importance and management of weed species (Wilding et al., 1998; Hnatowich, 2000; Singh et al., 2001; Moorthy et al., 2002; Holding and Bowcher, 2004; Day et al., 2006). Typically the most problematic weed species in lentil have a similar ecology and biology as the crop. Generally, cool-season broadleaf weeds are the most difficult to control in lentils. Problem annual broadleaf or dicot species in lentil include those of the Asteraceae, Brassicacae, Chenopodiaceae, Fabaceae and Polygonaceae, among other families (Brand et al., 2007). While many annual grass (Poaceae) or monocot species are selectively and effectively controlled with herbicides, Avena, Lolium, Phalaris, Poa, Setaria and other species are commonly reported in lentils (Table 20.1). Generally, the most troublesome grass weeds in lentil are classified as cool-season species categorized as C3 plants based on their photosynthetic system. Perennial weeds such as members of the Convolvulaceae, Asteraceae, Poaceae and other families can also be problematic in lentil production. Weeds that are specific problems in lentil are problems within a crop rotation and not specific to the lentil crop alone. An exception to this is parasitic plants which are partially or completely obligate to lentil. Orobanche and Cuscuta spp. have been reported to be parasitic weeds of lentil and other legumes (see Rubiales et al., Chapter 21, this volume).

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Table 20.1.

Common weed ﬂora of lentil crop.

Category Family

Scientiﬁc name

Common name

Category

Liliaceae Annual monocots Poaceae

Asphodelus tenuifolius Avena spp.

Wild onion Wild oat

Bromus spp.

Brome grass

Fabaceae Annual dicots (continued) Fumariaceae

Critesion murinum Lolium spp. Phalaris minor Poa annua Polypogon monspeliensis

Barley grass Ryegrass Little seed canarygrass Annual bluegrass Annual rabbitsfoot grass

Setaria viridis

Green foxtail

Vulpia bromoides Amaranthus spp. Bifora testiculata Anthemis cotula Gnaphalium indicum Lactuca serriola Launaea nudicaulis

Silver grass Pigweeds Bifora Mayweed chamomile Cudweed Prickly lettuce Skeletonweed

Annual dicots

Amaranthaceae Apiaceae Asteraceae

Arrow weed Sow thistle Tarweed Small bugloss Sheep weed Swine cress Musk weed Wild radish Wild mustard Corn spurry Common lambsquarters Kochia

Parasitic

Scientiﬁc name

Common name

Lathyrus aphaca Medicago spp. Medicago denticulata Melilotus alba Melilotus indica Vicia spp. Vicia villosa Fumaria spp. Polygonum spp.

Wild pea Medic Bur clover

White sweet clover Yellow sweet clover Common vetch Woolly pod vetch Fumitory Polygonaceae Buckwheat/ Wireweed Rumex dentatus Wood sorrel Rubaceae Gallium spp. Bedstraw Solanaceae Solanum spp. Nightshade Cyperaceae Cyperus rotundus Nut grass Poaceae Cynodon dactylon Bermuda grass Asteraceae Canada thistle Cirsium arvense Convolvulaceae Convolvulus Field bindweed arvensis Resedaceae Reseda spp. Mignonette Convolvulaceae Cuscuta spp. Dodder Orobancheaceae Orobanche spp. Broomrape

J.P. Yenish et al.

Pluchea lanceolata Sonchus spp. Boraginaceae Amsinckia spp. Anchusa arvensis Buglosoides arvensis Brassicaceae Coronopus didimus Myagrum perfoliatum Raphanus raphanistrum Sinapis arvensis and Sisymbrium spp. Caryophyllaceae Spergula arvensis Chenopodiaceae Chenopodium album Kochia scoparia

Perennial monocots Perennial dicots

Family

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20.3. Methods of Weed Control There are five recognized weed control techniques (Anderson, 1983). These include preventive, cultural, mechanical, chemical and biological. Mixing two or more of these weed management principles is the basis for integrated weed management. Each of the five principal techniques is of equal value in managing weeds in lentil with the exception of biological control. Few biological methods of weed control have proven effective in annual cropping systems and individual weed species which are problematic in legumes are largely a function of cropping systems or rotation rather than the individual crop of lentil. Preventive weed control The most cost effective form of weed control is preventive. A quote attributed to the 13th-century English judge Henry de Bracton, ‘an ounce of prevention is worth a pound of cure’, is very true in the realm of weed management. The definition of preventive weed management is to eliminate the introduction or spread of specified weed species in an area not currently infested with these plant species (Radosevich et al., 1997). The size of the geographic area may vary from an individual field to an entire continent. While much of preventive weed control could be regulatory in nature, there is still much that an individual farmer can do to prevent the introduction of weeds. In fact, individual farmer practices are more likely to be effective in preventing weeds than any regulatory practices. Individual farmers concentrating on preventing weed introduction often need only to plant weed-free seed, use manure generated from weedfree hay, feed or bedding, clean field equipment (particularly harvest equipment) and prevent weeds that are encroaching on their property from spreading seed or other vegetative propagules onto their land (Young et al., 2000). Typically, weed-free seed is easy to obtain, but normal cleaning or screening methods may provide certain weeds a method of effective entry. Specific weed pests such as wild pea or vetches produce seed similar in shape and size to that of lentil and removing this seed through cleaning may be difficult (Erskine et al., 1994; Brand et al., 2007). It is best to avoid seed from fields or regions with known infestations of these and similar weeds. Once seed cleaning is completed, growers need to adequately destroy screenings through composting, hammer mill or other methods. Livestock manure can also be a source of weed seed entering a farming operation. Feed and hay should be inspected prior to feeding or mixing. Even if feed, hay and bedding are thought to be weed free, manure should be composted to further eliminate weed seed through the temperatures generated. Temperatures as high as 83°C may be required to adequately reduce weed-seed viability, although some species may lose viability at lower temperatures (Wiese et al., 1998). Acquired animals should also be quarantined to allow the digestive system to completely empty of foreign

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feed. Additionally, hair, wool, hides and hooves should be inspected to make sure no weed seed is trapped either directly or encased in mud or other foreign matter. Equipment should be cleaned prior to removal from and entry into fields to prevent weed dispersal (Anderson, 1983). Methods for cleaning equipment may be as simple as removing seed, rhizomes, etc. by hand or as high tech as radiation treatments. Special care needs to be paid to harvest equipment since weeds typically mature at the same time as the crop and modern harvest equipment is an effective means to disperse weed seed within and between fields. In cases where residue is removed from crop fields for the purpose of offsite separation of grain and stover, that residue should be disposed of at the processing site rather than the farmer transporting it back to his own fields for disposal. When the stover is used for the livestock feed, the manure should be composted or otherwise treated to kill viable weed seed prior to spreading the manure back on to fields. Mixing of stover from multiple fields and then returning a portion to each field will spread weeds quite effectively. Irrigation water is also a common source of weed-seed influx. Kelley and Bruns (1975) in a detailed study of the US Pacific Northwest’s Columbia River calculated as much as 15,000 seed/ha could be disseminated onto fields by unscreened irrigation waters. Incoming irrigation water should be screened or other apparatus used to remove weed seed from the water prior to applying it to a field. Controlling encroaching populations of weeds is also important for preventing new weed infestations. Most weed seed falls less than 1 m from the mother plant (Radosevich et al., 1997). Thus, patches of weeds tend to creep across a given area if allowed to naturally disperse. At the same time, longrange dispersal of weed seeds is important in the colonization of new weed patches. Therefore, the nearest patches of weeds that are encroaching on a particular area are the most threatening to that area, while weed seeds travelling long distances are a potential future problem after they colonize into weed patches. Preventive weed control could also be applied to weed species that are already present in fields within the farming operation. This is particularly important in regions where chemical weed control is a large component of weed management programmes. Preventing external influxes of weed seed from outside sources is important in keeping herbicide-resistant weed biotypes out of the farming operation. Moreover, preventive weed management could isolate a weed infestation to one field or a portion of one field within a grower operation. In areas with high herbicide use, a weed seed in screenings or as a seed contaminant probably survived a herbicide application to the field in which it was produced. Therefore there is a greater potential for that seed to be resistant to the herbicide than the wild type. Of course, the mother plant may have emerged after the herbicide application, or it may not have been sprayed because of poor herbicide application or equipment problems, in which case the plant is unlikely to be herbicide resistant. However, the potential exists to bring herbicide resistance into the

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farming operation by using screenings or contaminated seed or to move resistant weeds within and between fields.

Cultural weed control Cultural methods of weed management utilize practices that are common to good crop management (Smith and Martin, 1995). The goal is to manage a crop or cropping system to maximize crop competition with weeds. In other words, make the crop as healthy and competitive as possible to lessen or better tolerate weed competition. Tools for cultural weed control include use of competitive cultivars, timeliness of planting, cover crops, and competitive rotational crops or rotational crops with different life cycles. Planting crops with differing life cycles in rotation prevents population increases of any single species of weed (Radosevich et al., 1997). Additionally, practices such as optimal fertilizer placement and timing, optimal irrigation timing, and other input timing or placement can benefit the crop at the expense of weeds (Di Tomaso, 1995). Cultural practices are generally applied within, between, and throughout the crop rotation. Unfortunately, lentil is usually the weakest competitor in the rotations in which they are grown. Typically, cultural weed control in rotational crops keep weed populations low and benefits are realized in the yield and quality of lentils. Lentil provides little to no opportunity for cultural weed control within the rotation. Ultimately, the value of lentil as a cultural weed control tool within a crop rotation is directly related to differences in the ecology and biology between the lentil and other crops in the rotation. A primary rotational weed control benefit to lentil is the management of parasitic plants. Unfortunately, with the dormant seed life of Orobanche and Cuscuta spp. being 14 (Lopez-Granados and Garcia-Torres, 1999) and 60 years (British Columbia Ministry of Agriculture, Food and Fisheries, 2002), respectively, the rotational interval between susceptible crops may be impractical. There are several cultural practices commonly involved with lentil production that makes them more prone to losses from weed competition. Very early spring or winter planting of lentil have shown greater yield potential than later spring seeding (Sarker and Erskine, 2007). However, effective weed control is critical to fully realizing this increased yield potential. Delayed sowing reduces early vigour, crop competitiveness, and resulting yield potential (Mishra et al., 1996; Holding and Bowcher, 2004). However, delayed seeding provides greater opportunity for weed control by mechanical or chemical methods prior to sowing (Brenzil et al., 2006; Day et al., 2006). In North America, autumn-seeded lentils have a substantial yield advantage over spring-seeded lentils. However, weed competition and limited post-emergence control options are major obstacles to fully realizing the greater yield of autumn-seeded lentils. Moreover, weed competition may be equal or greater from winter annual weeds and cold-weather-tolerant weeds than with spring annual weeds present in a spring-seeded crop.

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Lentil cultivars vary in growth habit and morphology (Erskine and Goodrich, 1991) and differences in competitive ability could be expected. However, research has been inconclusive with Tepe et al. (2005) reporting minor differences in competitiveness between cultivars, but indicating that none of the cultivars were really effective as a ‘stand-alone’ component for weed control in lentils. McDonald et al. (2007) also showed that differences in early vigour between genotypes were insufficient to affect the competitive ability of lentil. Seeding depth, rate and row spacing influence lentil establishment, competitiveness and yield. Seeding at 3–5 cm depth increases plant emergence, height, plant dry weight and grain yield compared to seeding at 8–10 cm. However, greater crop injury has been observed due to pre-emergence herbicide applications with shallow compared to deeper seed placement (van Rees, 1997; Brand et al., 2001). Greater seeding rates also reduce weed populations due to greater crop competition (Boerboom and Young, 1995; Ball et al., 1997; Paolini et al., 2003; McDonald et al., 2007). Narrow row spacing theoretically improves crop competition against weeds as the lentil crop reaches full canopy closure earlier than with wider spacing. However, Chaudhary and Singh (1987) found no effect of row spacing on final weed populations. Although the crop is likely to be less competitive with weeds with wider row spacing, wider spacing can allow more efficient weed removal by tillage or hand weeding. Rotational crops in lentil production systems vary greatly within and between production areas. In some areas of the Indian subcontinent, lentil may be grown in rotation with millet, sorghum, maize, cotton, guar, sesame or rice (Ali et al., 1993). In other areas, lentil may be grown in rotation with wheat, barley or forage crops (Yenish, 2007). While the most common practice of growing lentil is as a sole crop, there are instances where lentil is grown as part of a crop mixture. In other situations, the crop may be grown in relay with other crops to allow two harvested crops a year. Regardless of crop rotation, lentil is an attractive crop because of the disease, fertility and monetary benefits it brings to the rotation. Lentil is not grown to provide a weed control benefit. Moreover, lentil could become a liability with regards to weed control because of the increased weed-seed production due to poor competition or limitations of the use of soil-persistent herbicides in rotational crops. Cultural control of weeds is an important part of cropping systems. Managing weeds by cultural methods means reduced expenditure on pesticides, fuel and labour. While cultural management of weeds is an important part of crop rotations that include lentil, lentils are usually the beneficiary of the positive aspects of cultural weed control rather than a benefactor.

Mechanical weed control Mechanical methods are the primary approach to weed control in lentil. Mechanical practices range from tractor-powered tillage to weed removal by hand hoeing or pulling. Pulling weeds by hand or removal

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by human-powered equipment such as a wheel hoe is common in less industrialized countries (Knott and Halila, 1986; Bhan and Kukula, 1987). However, even in these countries labour costs are becoming prohibitive (Solh and Pala, 1990). In more industrialized production, mechanical control of weeds is limited by the narrow row spacing commonly used. Row spacing is too narrow to allow between-row cultivation without damaging the crop. Mechanical weed control is limited to aggressive and multiple tillage operations prior to planting, with ploughs, cultivators or discs and postplanting to early post-emergence use of a harrow, cultipacker or rotary hoe. In order to be effective, mechanical weed control must be repeated throughout the critical weed-free period. This often means that the initial weeding may occur before lentil emergence. Light tillage with a cultipacker, harrow or rotary hoe can be effective to some degree in removing small weed seedlings without excessive damage to lentil seedlings. Generally, more aggressive tillage will damage lentil and may result in reduced yields compared to non-weeded fields. Thus, mechanical control of weeds in lentils after crop emergence is largely limited to hand weeding only. The frequency of weed removal by mechanical methods varies with production systems and environment. Experimentally, up to five mechanical weed removals have been necessary to ensure weed-free conditions in lentils or other legumes (Knott and Halila, 1986). However, competition from weeds may occur as weeds are allowed to develop into a stage that allows for proper identification and grasping for removal. Weeds are in competition with the crop during this time and often there is physical damage to the crop as weeds are removed by hand or machine. Traditionally, due to its short stature lentil has been grown in systems where the soil has been cultivated to create a flat seedbed and stubble removed to allow good establishment and ease of harvest. These conditions are also generally regarded as optimal for pre-emergence herbicide applications. Cultivation of soil can incorporate weed seed into top soil layers allowing for maximum germination when soil is moist and the potential for a knockdown herbicide or follow-up cultivation to control emerging weeds prior to sowing in some situations (Roberts, 1981). Deep tillage can also bury weed seed below their optimum emergence depth inducing dormancy and inhibiting germination by reducing the oxygen concentration (Preston, 2007). Future disturbance may reintroduce the seed to an appropriate depth for germination. Tillage can also stimulate the germination of some weed species by damaging the seedcoat, which breaks seed dormancy. Stubble from previous crops can be removed by burning or physical incorporation into the soil. Burning can reduce weed numbers of some species. Walsh and Newman (2006) found that all seed of annual ryegrass (Lolium rigidum Gaudin) and wild radish (Raphanus raphanistrum L.) were destroyed by burning, provided burning temperatures were above 400 and 500°C, respectively. Removing stubble and allowing the soil to be solarized can have a significant impact on weed populations. Linke (1994) showed that soil solarization reduced the population in most weed species present, with only a minority increasing in population.

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Currently, farmers in the more developed regions of the world are adopting no-tillage systems with minimal soil disturbance and crop residue conservation. No-tillage systems greatly reduce the opportunity for preplant mechanical weed control. However, reduced tillage systems may have an advantage in managing the soil weed seedbank. Minimum soil disturbance ensures that most weed seeds are left on the soil surface. Seed survival of weed species such as green foxtail and wild oat (Avena fatua L.) are reduced fivefold by leaving seed on the surface in comparison with burying by tillage (Banting et al., 1973; Saga and Mortimer, 1976; Thomas et al., 1986). Modelling and field observations have confirmed trends that preventing seed entry into the surface seedbank will reduce weed populations in the long term (Mohler, 1993; Anderson, 2004; Preston, 2007). Additionally, standing stubble can provide trellising for the crop, resulting in higher canopy and improved machine harvest.

Chemical weed control Chemical weed control is synonymous with using herbicides to control weeds. Herbicides are regulated by various government agencies and laws. Products available vary greatly between regulatory entities. Further complicating matters are the limited number of herbicide manufacturers and relatively limited markets for potential lentil herbicides. Moreover, herbicides that are effective for controlling the weed spectrum in one particular lentil production system in one particular geographic area may have limited activity against weeds in another production system due to poor efficacy or soil persistence. Thus, discussing specific herbicides is somewhat pointless as recommendations for one country may be ineffective or illegal in another country or even different regions of the same nation. That being said, discussion in this section will be general in nature and specific only to make a point. Readers need to be aware to follow all local laws and regulations, seeking out specific recommendations from local agronomists, extension personnel or other qualified individuals or entities. Non-selective herbicides may be used alone or as an aid to tillage in controlling weeds prior to planting or emergence of grain legumes (McKay et al., 2002). Herbicides such as glyphosate or paraquat do not have activity once they come into contact with the soil (Vencill, 2002). These herbicides are commonly used in no-tillage or reduced tillage production systems to ensure control of weeds with no or minimal tillage prior to lentil planting (Baker et al., 1996). More typically, control of weeds prior to planting is done using tillage operations which are applied specifically for weed control or provide effect weed control while preparing a suitable seedbed (Knott and Halila, 1986). Often residual herbicides are applied prior to planting lentil (Bhan and Kukula, 1987). These residual herbicides will provide control against weeds that emerge over the following few days to several weeks following herbicide application. The exact duration of weed control will vary with herbicide

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characteristics, rate, environmental conditions or other factors. Ideally, residual herbicides will provide effective weed control from time of application until the lentil crop progresses beyond the critical weed-free period or the full-bloom stage as noted earlier. Herbicides that have provided effective broadleaf-weed control with no or acceptable crop injury include several dinitroanalines (trifluralin, pendemethalin and others), triazines (metribuzin), acetanalides (metolachlor) (Bhan and Kukula, 1987; Solh and Pala, 1990) and imidazolinones (imazethapyr) (Lyon and Wilson, 2005). These herbicides may be mechanically incorporated with sweep cultivators, discs, harrow or other tillage tools prior to planting or applied following planting, but prior to crop emergence. In some instances, residual herbicides may be tank-mixed with glyphosate or other non-selective herbicide. Often, it is necessary to combine or tank-mix one or more herbicides in order to broaden the spectrum of weeds controlled (Bruff and Shaw, 1992; Hydrick and Shaw, 1994; Zhang et al., 1995). Post-emergence herbicides available for lentils are very limited relative to the number of products available for more widely grown legume crops such as soybean (Zollinger, 2006). Grass weeds can be effectively controlled by aryloxyphenoxy propionate or cyclohexanedione herbicides with excellent crop safety (McKay et al., 2002). However, resistant grass weed populations have developed through heavy use of these herbicides in legumes and rotational crops such as cereals (Delye, 2005). Herbicides for post-emergence broadleaf control are extremely limited for lentil and include only a few herbicides, the legal use of which is changing with regulating agencies between countries. Crop safety is often limiting with post-emergence broadleaf herbicides in lentils. Controlling weeds or desiccating a crop to aid in harvest can be done by mechanical or chemical options (McKay et al., 2002). While mowing or swathing the crop is possible, it is often not the best method of control since lentils often do not cure well in the swathe (Hnatowich, 2000). Similarly, a crop with uneven maturity will have great variability in seed size and quality when swathed or mowed prior to harvest. Chemical desiccation can be achieved using products such as glyphosate or paraquat (McKay et al., 2002). Given that weed control options are limited (particularly for broadleaf weeds), chemical desiccation is often necessary to aid in the mechanical aspects of harvest or the timeliness to ensure successful dry-down of weeds and crops prior to harvest.

20.4. Integrated Weed Management Maredia (2003) defines integrated pest management as: A pest management system that, in the context of the management associated environment and the population dynamics of the pest species, utilizes all suitable techniques and methods in as compatible a manner as possible to maintain the pest populations at levels below those causing economically

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More simply, integrated weed management uses all weed-control strategies to effectively control weeds in a safe, cost-effective and environmentally sound manner. Currently, all or nearly all lentils are grown under some form of integrated pest management. Integrated weed management in lentils is a necessity due to its poor competitiveness, lack of effective herbicides, the need to rotate crops as part of disease or other pest management, and other reasons. Generally, lentils are able to be successfully grown due to integrated pest management throughout the rotation. Lentils, by themselves, have limited benefit in a truly integrated cropping system.

20.5. Summary Lentil is a very poor competitor against weeds. Most previously published compendia on lentil production note lack of effective herbicides and the need to expand available herbicides. Most herbicides labelled for use in lentils were initially developed for the soybean market and happened to have safety in lentils. However, the introduction and phenomenal success of glyphosate-resistant soybeans have largely lessened the development of herbicides for use in soybeans. Moreover, while the development of herbicide-resistant technology was mentioned by some as a potential method to provide outstanding weed control in minor crops, actual development of herbicide-resistant minor crops has been non-existent (Devine, 2005). Given the reduction in new herbicide molecules being discovered and labelled for use in any crops, it is unlikely that new herbicides for use in lentils will be developed without the development of herbicide-resistant lentils. Even if herbicide-resistant technology develops for use in lentils, growers must learn to effectively control weeds using integrated weed management. Herbicide-resistant lentils might serve to limit cultivar development of lentils and limit the germplasm available with resistance to certain diseases and pests (Devine, 2005). Heavy use of a single herbicide would tend to be increased through the use of herbicide-resistant crop systems and it would be likely that herbicide-resistant weeds would develop or there would be a weed species shift (Ball, 1992). Thus, the development of additional herbicides for lentils through transgenic means or otherwise, are unlikely to produce a sustainable system of lentil production by itself. Integrating existing practices is the most likely answer to sustained lentil production within a cropping system.

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McKay, K., Miller, P., Jenks, B., Riesselman, J., Neill, K., Buschena, D. and Bussan, A.J. (2002) Growing chickpea in the Northern Great Plains. Extension Bulletin A-1236. North Dakota State University, Fargo, North Dakota, USA, 8 pp. Mishra, J.S., Singh, V.P. and Bhan, V.M. (1996) Response of lentil to date of sowing and weed control in Jabalpur, India. LENS Newsletter 23, 18–23. Moes, J. and Domitruk, D. (1995) Relative competitiveness of no-till sown crops. In: Lafond, G.P., Plas, H.M. and Smith, E.G. (eds) Bringing Conservation Technology to the Farm. Prairie Agricultural Research Initiative – Agriculture and Agri-Food Canada. Available at: http://paridss.usask.ca/factbook/cfarms/moes.html (accessed 21 July 2008). Mohamed, E.S., Noural, A.H., Mohamed, G.E., Mohamed, M.I. and Saxena, J.C. (1997) Weeds and weed management in irrigated lentil in northern Sudan. Weed Research 37, 211–218. Mohler, C.L. (1993) A model of the effects of tillage on emergence of weed seedlings. Ecological Applications 3, 53–73. Moorthy, B.T.S., Mishra, J.S. and Dubey, R.P. (2002) Teaching Manual on Recent Advances in Weed Management. National Research Centre for Weed Science, Maharajpur, Jabalpur, India. O’Donovan, J.T., de St Remy, E.A., O’Sullivan, P.A., Dew, D.A. and Sharma, A.K. (1985) Influence of the relative time of emergence of wild oat (Avena fatua) on yield loss of barley (Hordeum vulgare) and wheat (Triticum aestivum). Weed Science 33, 498–503. Paolini, R., Colla, G., Saccardo, F. and Campiglia, E. (2003) The influence of crop plant density on the efficacy of mechanical and reduced-rate chemical weed control in lentil (Lens culinaris Medik.). Italian Journal of Agronomy 7, 85–94. Preston, C. (2007) Weed biology – the missing link to better weed management. Grains Research and Development Corporation, Kingston, Australian Capitol Territory, Australia. Available at: http://www.rangemedia.com.au/grdc2007/pdf/Wagga%20 Wagga/Chris%20Preston1.pdf (accessed 21 July 2008). Radosevich, S., Holt, J. and Ghersa, C. (1997) Weed Ecology: Implications for Management, 2nd edn. John Wiley and Sons, New York. Roberts, H.A. (1981) Seed banks in soils. Advances in Applied Biology 6, 1–55. Saga, G.R. and Mortimer, A.M. (1976) An approach to the study of population dynamics of plants with special reference to weeds. Advances in Applied Biology 1, 1–47. Salkini, A.B. and Nygaard, D. (1983) Survey of weeds in lentils in north and northeastern Syria. Lens 10, 17–20. Sarker, A. and Erskine, W. (2007) Recent progress in the ancient lentil. Journal of Agricultural Science 144, 19–24. Saxena, M.C. and Wassimi, N. (1980) Crop weed competition studies in lentils. Lens 7, 55–57. Singh, M., Saxena, M.C., Abu-Irmaileh, B.E., al-Thahabi, S.A. and Haddad, N.I. (1996) Estimation of critical period of weed control. Weed Science 44, 273–283. Singh, V.P., Dixit, A., Mishra, J.S., Singh, P.K., Raghuwanshi, M.S. and Bhan, V.M. (2001) Cropping system: an approach to integrated weed management. Pesticide Information 27, 14–21. Smith, A.E. and Martin, L.D. (1995) Weed management systems for pastures and hay crops. In: Smith, A.E. (ed.) Handbook of Weed Management Systems. Marcel Dekker, New York, pp. 477–517. Solh, M.B. and Pala, M. (1990) Weed control in chickpea. Options Mediterraneennes – Serie Seminaries 9, 93–99.

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J.P. Yenish et al. Tepe, I., Erman, M., Yazlik, A., Levent, R. and Ipek, K. (2005) Comparison of some winter lentil cultivars in weed-crop competition. Crop Protection 24, 585–589. Thomas, A.G., Banting, J.D. and Bowes, G. (1986) Longevity of green foxtail seeds in a Canadian praire soil. Canadian Journal of Plant Science 66, 189–192. Van Acker, R.C., Weise, S.F. and Swanton, C.J. (1993) The critical period of weed control in soybeans (Glycine max (L.) Merr.). Weed Science 41, 194–200. van Rees, H. (1997) The Southern Mallee and Northern Wimmera Crop and Pasture Production Manual. Grains Research and Development Corporation, Kingston, Australian Capitol Territory, Australia. Vencill, W.K. (ed.) (2002) Herbicide Handbook, 8th edn. Weed Science Society of America, Lawrence, Kansas, USA. Walsh, M. and Newman, P. (2006) Burning narrow windrows for weed seed destruction. In: Turner N.C., Acuna T. and Johnson, R.C. (eds) Proceedings of the 13th Australian Agronomy Conference. Australian Society of Agronomy, Gosford, New South Wales, Australia. Weaver, S.E. and Tan, S.C. (1987) Critical period of weed interference in transplanted tomatoes and its relation to water stress and shading. Canadian Journal of Plant Science 67, 575–583. Wiese, A.F., Sweeten, J.M., Bean, B.W., Salisbury, C.D. and Chenault, E.W. (1998) High temperature composting of cattle feedlot manure kills weed seed. Applied Engineering in Agriculture 14, 377–380. Wilding, J.L., Barnett, A.G. and Amor, R.L. (1998) Crop Weeds. R.G. and F.J. Richardson Publishers, Melbourne, Victoria, Australia. Yenish, J.P. (2007) Weed management in chickpea. In: Yadav, S.S., Redden, B., Chen, W. and Sharma, B. (eds) Chickpea Breeding and Management. CAB International, Wallingford, Oxon, UK, pp. 233–245. Young, F.L., Matthews, J., al-Menoufi, A., Sauerborn, J., Pierterse, A.H. and Kharrat, M. (2000) Integrated weed management for food legumes and lupines. In: Knight R. (ed.) Linking Research and Marketing Opportunities for Pulses in the 21 Century. Kluwer Academic Publishers, Dordrecht, The Netherlands, pp. 481–490. Zhang, J., Hamill, A.S. and Weaver, S.E. (1995) Antagonism and synergism between herbicides: trends from previous studies. Weed Technology 9, 86–90. Zollinger, R.K. (2006) 2006 North Dakota Weed Control Guide. North Dakota State University (NDSU) Extension Service Bulletin W-253. NDSU, Fargo, North Dakota, USA. Available at: www.ag.ndsu.nodak.edu/weeds/w253/w253w.htm (accessed 21 July 2008).

21

Parasitic Weeds

D. Rubiales,1 M. Fernández-Aparicio1 and A. Haddad2 1Institute

for Sustainable Agriculture, CSIC, Córdoba, Spain; 2International Center for Agricultural Research in the Dry Areas (ICARDA), Aleppo, Syria

21.1. Introduction Over 4000 species of angiosperms are able to directly invade and parasitize other plants. A few of them are weedy and parasitize cultivated plants. They belong to various plant families, and attach to host roots, shoots or branches. Aerial parts of lentil plants can be infected by dodders (Cuscuta spp.), whereas roots can be infected by broomrapes (Orobanche spp.) causing significant damage.

21.2. Dodders Dodders have a broad host range, being widely distributed. The most important species is Cuscuta campestris Yuncker that is a problem in some areas of the Middle East, and a threat to lentil in certain locations. It has fine, yellow or orange, thread-like branches which grow and entwine around the stems and other aboveground parts of the host (Plate 5A–C). The stem of the parasite is tough, curling and leafless and bears only minute scales in place of leaves. Cuscuta hyalina Roth. has also been observed on lentil in India. Grey to reddish-brown seeds are produced in abundance and mature a few weeks after bloom. Seeds may germinate immediately after they fall to the ground, or may remain dormant until the following season. Dodderinfested areas appear as patches in the field and continue to enlarge during the growing season (Plate 5A). In late spring and early summer, dodder produces a massed cluster of white flowers. Infected host plants become weakened, decline in vigour and produce poor yields. Several patches might coalesce to form large areas that can be easily recognized by the yellowish colour of the parasite strands. © CAB International 2009. The Lentil: Botany, Production and Uses (eds W. Erskine et al.)

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21.3. Broomrapes Broomrapes are holoparasitic plants, completely dependent on the host due to the lack of chlorophyll. Once attached on the host roots, broomrapes are able to survive and develop, sucking carbohydrates from the phloem and water and minerals from the xylem of the host by means of a bridge to the host vascular tissues. Lentil can be parasitized mainly by two different species of broomrapes, namely crenate broomrape (Orobanche crenata Forsk.) (Plate 5D, E) and Egyptian broomrape (Orobanche aegyptiaca Pers., syn. Phelipanche aegyptiaca (Pers.) Pomel) (Plate 5F). Orobanche crenata has been known to threaten legume crops since antiquity. This parasitic weed is mainly restricted to the Mediterranean basin, southern Europe and the Middle East, and is an important pest in grain and forage legumes, as well as in some apiaceous crops such as carrot and celery. Sauerborn (1991) estimated that over 1 million ha of faba bean in the Mediterranean region and western Asia are infested or at risk from O. crenata. Dispersion of seeds is easy by machinery, wind, water or mixed with crop seeds, but populations of O. crenata will only establish in areas with a distinct precipitation seasonality, with a warm and dry period being followed by warm and wet conditions and when host crops are grown under this warm and wet period. Climatically suitable regions include all Mediterranean climate areas and part of the monsoon, savannah and winter-dry climate regions of Central America, Africa, Australia and South Asia (Grenz and Sauerborn, 2007). There is evidence that O. crenata is expanding to new areas (Rubiales et al., 2008). Losses up to 95% have been reported for lentil (Sauerborn, 1991) depending on the infestation level and the planting date. Orobanche crenata is characterized by large erect plants, branching only from their underground tubercle. The size of spikes is influenced by host plant vigour. Orobanche crenata plants infecting lentils are 10–40 cm tall, bearing many flowers of diverse pigmentation, from yellow, through white to pink and violet. The calyx is 13–18 mm, with segments free and bidentate. The corolla is 18–28 mm, glandular pubescent, the lips large and divergent, not ciliate but often with lilac veins. The anthers are brown, glabrous or subglabrous. The filaments insert 2–3 mm above the base of the corolla, and are hairy at the base with glandular hair at the apex (Pujadas-Salvá, 1999). Orobanche aegyptiaca parasitizes lentil and other legumes, but also many other crops such as tomato, potato, cabbage, sunflower, parsley or watermelon (Joel et al., 2007). It is widely distributed in eastern parts of the Mediterranean, in the Middle East and in parts of Asia. It is very similar to Orobanche ramosa L. (syn. Phelipanche ramosa (L.) Pomel) that is more common as a weed in Europe, parts of Africa and Asia, with some overlap with O. aegyptiaca in the northern parts of the Middle East. However, O. aegyptiaca is more aggressive and adapted to more arid regions. Both species have branched stems with flowers that may significantly differ in colour, from white to dark blue. A simple feature that allows field distinction is the hairiness of the stamens at the connective, which occurs only in O. aegyptiaca.

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The upper leaves and the corolla are hairy glandular and the lobes of the lower lip of corolla (20–35 mm) are rounded. Orobanche foetida is another broomrape species that can infect legume crops in Tunisia. Fortunately, it is not yet reported infecting lentil, and lentil germplasm is highly resistant (Fernández-Aparicio et al., 2008b). Broomrapes propagate via seeds. Broomrape seed germination occurs only in response to a chemical signal from the host root. Before germination, broomrape seeds must undergo conditioning under suitable temperature and moisture conditions. Optimum temperatures for conditioning and germination are different among broomrape species, being about 18°C for O. crenata and about 23°C for O. aegyptiaca, with substantial differences among populations within the species. Seeds are very small, approximately 0.20–0.35 mm long. During germination, only a radicle emerges out of the tiny seed (Plate 5G). The small storage reserves, mainly composed of lipids, are capable of supporting a few days of autonomous growth of the emerging radicle that can grow only to a limited extent (few millimetres). When a root host is reached the radicle tip develops into an attachment organ, and a haustorium is formed. Subsequently the parasite develops a tubercle (Plate 5H, I) that grows underground on the host root surface for several weeks or months. At maturity, the parasite develops flowering shoots (a single non-branching shoot in the case of O. crenata, branched in O. aegyptiaca) that emerge above the soil near host plants and set seeds (Plate 5E, J). In contrast to other broomrapes that are self-pollinating, both O. crenata and O. aegyptiaca are believed to be at least partially outcrossing being pollinated by insects, although they will self-pollinate if not visited by insects. The number of seeds produced by a healthy O. crenata or O. aegyptiaca plant can exceed 200,000. Large quantities of long-lived seeds assure the parasite genetic adaptability to changes in host resistance and cultural practices. The minute seeds may easily be transferred from one field to another by cultivation, and also by crop contaminated seeds, water, wind, animals, and especially by vehicles and farming machines. Broomrape seeds may remain viable in soil for decades. Harvesting parasite shoots in lentil straw and forage crops may also assist in spreading the seeds if used to feed animals, because their manure may then be contaminated with parasite seeds, which remain viable after passing through the alimentary system of animals.

21.4. Management Several strategies have been developed for the control of parasitic plants, from cultural practices to chemical control (Parker and Riches, 1993; Joel et al., 2007), but none with unequivocal success. Proposed methods were not feasible, uneconomical or resulted in incomplete protection. So far, the effectiveness of conventional control methods is limited because of the numerous factors involved, in particular the complex nature of the parasites, which reproduce by tiny and long-living seeds, and that, in the case of

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broomrapes, are difficult to diagnose until they irreversibly damage the crop. The intimate connection between host and parasite also hinders efficient control by herbicides. The efficient management of dodders starts with the use of dodder-free seed and the spraying of the first affected patches with a contact herbicide to prevent spread. Infested equipment should be cleaned before and after use, and the movement of domestic animals from infested to dodder-free areas should be limited. The application of pendimethalin at 0.7–1.0 kg active ingredient (a.i.)/ha pre-emergence or early post-emergence is effective against Cuscuta in lentil. The only way to cope with the broomrapes is through an integrated approach, employing a variety of measures in a concerted manner, starting with containment and sanitation, direct and indirect measures to prevent the damage caused by the parasites, and finally eradicating the parasite seedbank in soil. So far, a combination of sowing Orobanche-free lentil seeds and delaying the sowing date has been the only available strategy for controlling broomrape infection. Autumn-sown cultivars have a greater yield potential in dry areas than spring-sown cultivars, but early sowing is known to increase the incidence of O. crenata (Silim et al., 1991). An alternative strategy could be the use of very early maturing cultivars that could escape O. crenata damage due to early pod filling, such as in the lentil cultivars ‘Chaouia’ and ‘Abda’. Seedbank demise can efficiently be achieved only for the cultivated soil layer by fumigation or solarization, but once soil is disturbed by deep ploughing, deeply buried broomrape seeds will affect the roots when brought into the lentil root area. However, this is uneconomic in a low-value crop like lentil. Some biological control agents have shown promise, but the technology is not ready yet to provide acceptable control. Chemical control of broomrape is complicated as herbicides have been effective only as a prophylactic treatment, since in most cases the actual infestation level in the field is usually unknown. Also, if the herbicide is to be applied to the parasite through the host via its conductive tissues, then the host should show some tolerance to the herbicide’s phytotoxicity. Herbicide treatments have to be adapted to the broomrape life cycle that is very much affected by sowing dates and climatic factors. Application must be repeated in a time interval of 2–4 weeks, because Orobanche seeds may germinate throughout the season, and may therefore re-establish on newly developed host roots. This would also minimize lentil phytotoxicity by using only a few tolerated applications. It has been shown that good broomrape control can be achieved in faba bean by glyphosate at low rates. However, insufficient selectivity is found in lentil, although post-emergence treatments of 30–40 g a.i./ha can be tolerated by some cultivars but the herbicide still reduces yield. Lentil tolerates pre-emergence treatments of imazapyr (25 g a.i./ha) and imazethapyr (75 g a.i./ha) and post-emergence treatments of imazaquin (7.5 ml a.i./ha) (Arjona-Berral et al., 1988; Jurado-Expósito et al., 1997) and imazapic (3 g a.i./ha) (Bayaa et al., 2000). Two post-emergence applications of imazapic

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are recommended, with the first application recommended when lentil has between five and seven true leaves, which is when broomrape usually starts to develop attachments on lentil roots, followed by a second application 2–3 weeks later. Lentil may need a third application of 2 g a.i./ha when late rain comes and extends the growth period, or when lentil is supplementary irrigated (Bayaa et al., 2000). Phytotoxicity might be higher in the presence of water, low temperature and heat stresses and varies with the cultivar of lentil used (Hanson and Hill, 2001). An additional problem of these imidazolinone herbicides for broomrape control is that they are not registered in every country, and that doses and timing for application need to be adjusted case by case. Also, traditional imidazolinones are being replaced in some countries by imazamox that is less residual in the soil, so doses and timing of application need re-adjustment. An alternative to cultivars resistant to parasitic weeds is the development of cultivars resistant to herbicides. This can be achieved by genetic engineering or simply by induced mutation. This second option has been successful and a number of cultivars are being introduced to the market under the trademark ‘CLEARFIELD® lentils’ (BASF Agsolutions, 2008) that are not genetically modified and that tolerate higher doses of imidazolinone herbicides. Crop rotation is of little value because of the persistence of the seeds for extended periods and the broad host range. However, there is promise in a number of other strategies. For example suicidal germination by application of germination stimulants has shown some success under laboratory conditions, although so far there is no evidence of success in the field. Another strategy is the use of trap or catch crops, which have yet to be proven successful and economical. An alternative might be intercropping, which is widely recommended for use for Striga control on maize and sorghum in Africa, and has recently been shown to reduce O. crenata infection in legumes (Fernández-Aparicio et al., 2007). Resistance against parasitic weeds is difficult to access, scarce, of complex nature and of low heritability, making breeding for resistance a difficult task (Rubiales et al., 2006). In spite of these difficulties, significant success has been achieved in some other crops, such as sunflower against Orobanche cumana, or faba bean and vetch against O. crenata (Rubiales et al., 2006; Joel et al., 2007). However, no resistant lentil cultivars are available. Only very recently, sources of resistance against O. crenata have been reported in lentil germplasm (Fernández-Aparicio et al., 2008) and in wild Lens accessions (Fernández-Aparicio et al., 2009). Accessions have been identified that escape infection because of their lower root density (Sauerborn et al., 1987), that induce lower seed germination, or that hamper establishment of broomrape radicles in contact with host roots thus limiting development of established tubercles. In addition, necrosis of tubercles was observed in some accessions. This can be exploited in lentil breeding. Combining different resistance mechanisms into a single cultivar should provide a more durable outcome. This can be facilitated by the adoption of markerassisted selection techniques, together with the use of in vitro screening

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methods that allow dissecting parasitic weed resistance into highly heritable components.

References Arjona-Berral, A., Mesa-García, J. and García-Torres, L. (1988) Herbicide control of broomrapes in peas and lentils. Food and Agriculture Organization (FAO) Plant Protection Bulletin 36, 175–78. BASF Agsolutions (2008) Available at: http://www.agsolutions.ca/basf/agprocan/ agsolutions/WebASClearfield.nsf/mainLentils.htm (accessed 1 June 2008). Bayaa, B., El-Hossein, N. and Erskine, W. (2000) Attractive but deadly. ICARDA Caravan 12. Available at: http://www.icarda.cgiar.org/publications1/caravan/ caravan12/Car128.Html (accessed 1 June 2008). Fernández-Aparicio, M., Sillero, J.C. and Rubiales, D. (2007) Intercropping with cereals reduces infection by Orobanche crenata in legumes. Crop Protection 26, 1166– 1172. Fernández-Aparicio, M., Sillero, J.C., Pérez-de-Luque, A. and Rubiales, D. (2008) Identification of sources of resistance to crenate broomrape (Orobanche crenata) in Spanish lentil (Lens culinaris) germplasm. Weed Research 48, 85–94. Fernández-Aparicio, M., Sillero, J.C. and Rubiales, D. (2009) Resistance to broomrape in wild lentils (Lens spp.). Plant Breeding (in press). Grenz, J.H. and Sauerborn, J. (2007) Mechanisms limiting the geographical range of the parasitic weed Orobanche crenata. Agriculture, Ecosystems and Environment 122, 275–281. Hanson, B.D. and Hill, D.C. (2001) Effects of imazethapyr and pendimethalin on lentil (Lens culinaris), pea (Pisum sativum), and a subsequent winter wheat (Triticum aestivum) crop. Weed Technology 15, 190–194. Joel, D.M., Hershenhorn, Y., Eizenberg, H., Aly, R., Ejeta, G., Rich, P.J., Ransom, J.K., Sauerborn, J. and Rubiales, D. (2007) Biology and management of weedy root parasites. In: Janick, J. (ed.) Horticultural Reviews. Vol. 33. John Wiley and Sons, Hoboken, New Jersey, USA, pp. 267–350. Jurado-Expósito, M., García-Torres, L. and Castejón-Muñoz, M. (1997) Broad bean and lentil seed treatments with imidazolinones for the control of broomrape (Orobanche crenata). Journal of Agricultural Science 129, 307–314. Parker, C. and Riches, C.R. (1993) Parasitic Weeds of the World; Biology and Control. CAB International, Wallingford, Oxon, UK. Pujadas-Salvá, A.J. (1999) Species of the family Orobanchaceae parasitic of cultivated plants and its relatives growing on wild plants, in the South of the Iberian Peninsula. In: Cubero, J.I., Moreno, M.T., Rubiales, D. and Sillero, J.C. (eds) Resistance to Orobanche: the State of the Art. Publisher Junta de Andalucía, Sevilla, Spain, pp. 187–193. Rubiales, D., Pérez-de-Luque, A., Fernández-Aparicio, M., Sillero, J.C., Román, B., Kharrat, M., Khalil, S., Joel, D.M. and Riches, C. (2006) Screening techniques and sources of resistance against parasitic weeds in grain legumes. Euphytica 147, 187–199. Rubiales, D., Fernández-Aparicio, M. and Rodríguez, M.J. (2008) First report of crenate broomrape (Orobanche crenata) on lentil (Lens culinaris) and common vetch (Vicia sativa) in Salamanca province, Spain. Plant Disease 92, 1368. Sauerborn, J. (1991) Parasitic Flowering Plants: Ecology and Management. Verlag Josef Margraf, Weikersheim, Germany.

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Sauerborn, J., Masri, H., Saxena, M.C. and Erskine, W. (1987) A rapid test to screen lentil under laboratory conditions for susceptibility to Orobanche. LENS Newsletter 14, 15–16. Silim, S.N., Saxena M.C. and Erskine, W. (1991) Effect of sowing date on the growth and yield of lentil in a rainfed Mediterranean environment. Experimental Agriculture 27, 145–154.

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Seed Quality and Alternative Seed Delivery Systems

Zewdie Bishaw,1 Mohamed Makkawi2 and Abdoul Aziz Niane1 1International

Center for Agricultural Research in the Dry Areas (ICARDA), Aleppo, Syria; 2Dhaid Research Station, Ministry of Environment and Water, Dhaid, Sharjah, United Arab Emirates

22.1. Introduction Lentil has been traditionally cultivated in South and West Asia, North and East Africa since its domestication. It spread from the Near East to the Mediterranean and then to Africa, Asia, Europe, America and lately to Australia owing to its plasticity in adaptation. Lentil has been introduced to developed countries as part of crop diversification, where traditionally production is dominated by cereals. Although Australia and North America (Canada and the USA) are becoming major global players in production and export of lentil, Asia remains the major producer, consumer and importer of lentil, with India being the single most important country in terms of production and consumption. Modern varieties and seed technology have a significant role in the transformation of agriculture. The availability, access and use of quality seed of adaptable crop varieties are critical to realize the impacts of investments in agricultural research. Despite a well-functioning lentil seed sector in developed countries the situation falls far short of the desired level in many developing countries. Lack of access to seeds of improved varieties, mechanization problems, high production costs, etc. are some of the major constraints hindering the development of the lentil seed industry. In a nutshell, both the public and the private sectors do not pay sufficient attention to lentil seed provisions.

22.2. What is Seed Quality? Seed is a primary input in crop production and is a means for delivering crop-based innovations to farmers to realize the impacts of investments in agricultural research. Since seed is one of the main factors limiting crop production potential it should reach farmers in a good quality state. 350

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Seed quality is complex and determined by many factors (Fougereux, 2000), but four key attributes may be explicitly identified (Bishaw et al., 2007): 1. Genetic quality – the inherent genetic potential of the variety for higher yield, better grain quality and greater tolerance to biotic or abiotic stresses. 2. Physiological quality – the potential germination and vigour leading to subsequent seedling emergence and crop establishment in the ﬁeld. 3. Physical quality – free from contamination with other crop seeds, common, noxious or parasitic weed seeds, mechanical damage, discoloration, and with uniform seed size and seed weight. 4. Health quality – absence of infection/infestation with seed-borne pests (fungi, bacteria, viruses, nematodes, insects, etc.).

Genetic purity McNeil et al. (2007) reported that in the language of trade and commerce in the Western countries, two types of lentils can be identified based on the cotyledon and seedcoat colour: red lentil (orange cotyledon and pale grey to dark seedcoat) and green (yellow cotyledon with green to brown seedcoat). This terminology is not followed in the major lentil-growing region of Africa and Asia. Moreover, genotypes with pure green cotyledons (Emami and Sharma, 1996a, b; Sharma and Emami, 2002; Sharma, Chapter 7, this volume) and a range of seedcoat colours may become available for consumption and trade. The existing grouping into red and green lentils will then become totally redundant. Genetic or varietal purity is crucial for grain quality and uniformity of grain traded in bulk because of differences in consumer preferences. A mixture of lentil grain with different cotyledon colours will certainly lower grain quality and hence its market value. Since the crop stand in lentil is usually dense, plant canopy is short and cotyledons are concealed, the best practical procedure to maintain varietal purity is the use of seed with high genetic purity for sowing.

Physical purity Use of physically pure seed is always desirable for lentil production. Contaminated seed is a major vehicle for introducing and spreading parasitic weed such as Orobanche and Cuscuta into new areas and fields (see Rubiales et al., Chapter 21, this volume). These two weeds have attained great economic significance in the Middle East although they are not a major issue in the countries of the Orient. For this reason, Orobanche and Cuscuta are considered as quarantine pests and a reason for rejecting seed lots in most certification schemes. However, seed cleaning using dodder mill and magnetic separator machines can eliminate Cuscuta from infested seeds, but these procedures are less practicable for large-scale application in lentils.

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Germination Like most field crops, physically sound lentil seed germinates well under laboratory conditions. Moreover, lentil is among those crops in which laboratory germination is reliable for predicting field emergence (Makkawi et al., 1999). This indicates that if proper care is taken, germination may not be a major constraint in lentil production. Seed vigour Seed vigour is defined as the capacity of a seed lot to germinate and produce normal seedlings under various field conditions (i.e. the rate and uniformity of seedling emergence and stand establishment in the field). It is a quantitative character, controlled by several factors including mechanical injury to embryo or seedcoat, environment and nutrition of the mother plant, stage of maturity at harvest, seed size, senescence, and attack by pathogens. Seed health Seed health has a significant effect on germination and seedling establishment leading to low germination, reduced crop establishment, severe yield loss or total crop failures. Lentil Ascochyta blight, which is also seed-borne, anthracnose and Botrytis can cause seed death and result in seedlings with necrosis or seedling blight. The infected seedlings die soon after emergence and reduce the plant stand, with significant consequences on the crop yield. For example, Ascochyta lentis has been associated with low seedling emergence in lentil (Morrall and Sheppard, 1981). Lentil plants from Ascochytainfected seeds had fewer branches, smaller roots and shoots, reduced vigour and lower seed yields (Kaiser and Hannan, 1987).

22.3. Factors Affecting Seed Quality Lentil seed quality can be extensively affected by several factors such as the production environment, agronomic practices and handling operations during production. Apart from genetic factors, environmental conditions during crop growth, seed development and maturity (soil conditions, nutrient deficiency, water stress, extreme temperatures, biotic stresses), harvesting (time, maturity, moisture), mechanical damage (during harvesting, conveying, cleaning, treatment, packaging) and improper storage (insects, moisture content, temperature) have their effect on seed quality. Genetic factors Seed quality can be affected by genetic factors as differences exist among species and varieties. Lakhani et al. (1986) found genetic variability in seed

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vigour and hard seed among lentil genotypes. There is also evidence that seedcoat thickness has an effect on germination and emergence in lentil (Sarker et al., 1995). Differences were also detected among lentil varieties in their response to ageing treatments (Makkawi and van Gastel, 2006). The results showed that high-vigour varieties are capable of withstanding ageing treatments for longer duration compared to the low-vigour varieties. Therefore a vigour test could be used in breeding programmes to select high-vigour genotypes with greater potential for storability. The physical integrity of seed also determines seed quality. Hence, testa quality is one of the principal components of legume seed quality and is influenced by harvesting. Mechanical damage influences the conditions of testa. The degree of cracking from a given handling treatment depends on seed moisture content. Mechanical injury exposes the seed to insect infestation and increases water absorption during storage, resulting in poor germination, reduced vigour and poor seedling establishment. Physiological studies showed that lentil seeds are very sensitive to injury during imbibition, especially at high temperatures and high humidity (Makkawi et al., 2008). Production environments Climatic conditions during the pre-harvest period have greater influence on seed quality. Lentil produces good quality seed in semi-arid or drier areas. High humidity and high rainfall during the season encourage excessive vegetative growth and reduce yield and seed quality. Excessive drought and/or high temperatures during flowering and the pod-fill period cause flower drop and reduce yields. Lentil is sensitive to heat and drought stresses and exposure to these conditions during crop growth causes a considerable reduction in yield (Johansen et al., 1994). It was reported that high temperatures during seed development in the field can dramatically reduce seed quality (Hampton and Coolbear, 1990). Harvesting The time and method of harvesting also influence seed quality. Delaying harvest subjects the seed to more deteriorative field stress and causes greater loss of quality (increases physiological age). Moreover, delaying the harvest leaves the mature seeds under weathering conditions, which may reduce seed germination significantly. It was reported that delay in harvest by 1 week reduces germination by 20% in lentils (Ellis et al., 1987). Mechanical damage Mechanical damage is one of the primary causes for significant loss in seed quality. Mechanical damage can be caused during harvesting, cleaning and handling. Lentil seeds, due to their convex surface on both sides, are more

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vulnerable to mechanical damage than seeds with a rounded shape such as faba bean, pea or chickpea (Muehlbauer et al., 1985). The net result is broken or cracked embryos, split or chipped seed, and ultimately abnormal seedlings. The damage is greater when the moisture content at the time of mechanical constraint is low. Further investigation on the effect of moisture content showed that the breakage percentage increases with a decrease in moisture content below 14% and also when the moisture content is higher than 20% (Fougereux, 2000).

22.4. Lentil Seed Treatment for Better Field Performance Lentil is grown under harsh rainfed conditions such as drought, heavy clay soil, extreme temperature and variable soil moisture, hence field establishment is a key determinant for crop production. Rapid and uniform germination with subsequent seedling development and crop establishment are considered important factors influencing yield potential, since the plant has limited ability to compensate for low populations. Therefore, knowledge of seed vigour, how it is acquired during seed development and subsequently lost through deterioration, is relevant to plant breeding, seed production, quality control and marketing. Several seed treatment options are associated with a productive crop as described below. Seed priming Seed priming, an ancient practice of soaking the seed with water for a specific period of time prior to planting, has been shown to improve crop establishment and crop yields in dry areas. Seed priming, controlled hydration and dehydration of seed, pelleting, etc., are used extensively to increase the rate and uniformity of seedling establishment of commercial crops (Ali et al., 2005). Harris (2006) gave an excellent review of on-farm seed priming including improved nutrition from Asia and Africa for various crops such as cereals (wheat, barley, rice, millet, sorghum, maize), legumes (chickpea, lentil, mungbean), bambara groundnut and cotton. Neupane (2002) reported that soaking seeds for 12 h followed by drying in the shade for 2 h was the best combination for lentil. During 2-year (season) trials priming reduced the average emergence time to 50% (from 9.4 to 7.8 days) and increased average grain yield by 34%. Gupta and Bhowmick (2005) also reported that priming lentil seed increased plant stand and yield significantly. From Bangladesh, where lentil is almost totally cultivated as a rainfed crop, Ali et al. (2005) reported after 2 years of experimentation that seed priming (water soaking) for 8–10 h increased the crop stand (from 74 to 85 plants/m length), plant height (from 34.4 to 40 cm), branches per plant (from 3.47 to 4.91), pods per plant (from 61 to 75.5), 1000-grain weight (from 17.19 to 17.59 g) and yield per ha (from 1528 to 2098 kg/ha, i.e. by 37.3%) in the variety ‘Barimasur 2’. This variety gave a better response to seed priming than ‘Barimasur 4’. This suggests that response to priming is genetically controlled.

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Rhizobial seed treatment Lentil seed must be inoculated at planting time with specific rhizobium (Gan et al., 2005), particularly if they are planted in new lentil-growing areas. In India, under a maize-lentil cropping sequence, seed inoculation with rhizobium increased yield by 20.3% over uninoculated seed (Sardana et al., 2006). Huang and Erickson (2007) found that seed treatment with Rhizobium leguminosarum bv. viceae is effective in controlling Pythium damping-off disease.

Chemical seed treatment Lentil is affected by several seed-borne pests. Chemical seed treatment becomes a standard procedure for disease control in many crops. Lentil diseases and control measures have been reviewed by Taylor et al. (2007) and Kaiser et al. (2000). Seed treatment with benomyl, carbendazim, carabthiin, ipodion or thiabendazole showed varying levels of efficacy against various diseases. In Spain, seed treatments with imazapyr did not affect germination or crop growth but controlled 85–95% of broomrape (Orobanche crenata Forsk.) and increased crop biomass and seed yield (Expósito et al., 1997).

22.5. Requirements for Quality Seed Production In seed production, maintaining quality is essential if the variety is to meet the expectation of farmers and consumers. Special attention should be given to ensure the genetic, physical, physiological and health quality. Following a combination of key regulatory, administrative and technical control measures and procedures can ensure seed quality. The regulatory measures establish a framework for variety release, set up field and seed standards, and enforce the regulations and standards through an impartial quality assurance authority. The agency establishes administrative guidelines and technical procedures to implement robust quality assurance systems. Bishaw et al. (2007) summarized the key technical components for producing quality seed. They also gave a detailed account of lentil seed production from variety maintenance through to field production, cleaning, treatment, storage and quality assurance.

22.6. Status of the Lentil Seed Industry Yadav et al. (2007) reported that 20 countries accounted for almost 99% of world lentil production from 2001 to 2005. The top ten countries include Australia, Canada and the USA from developed countries and Bangladesh, China, India, Iran, Nepal, Syria and Turkey from developing countries. The second tier countries comprise Ethiopia (12th), Morocco (13th), Pakistan

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(14th) and Yemen (20th) from the dry areas of Central and West Asia and North Africa (CWANA) region. The top lentil producers remain India followed by Turkey from the developing countries and Canada followed by Australia from the developed countries. Several authors have provided detailed accounts of diverse lentil production systems (Materne and Reddy, 2007; Yadav et al., 2007). At least two contrasting lentil production systems exist in the developed and developing countries. Some of the key distinguishing features include the scale, degree and level of farm operation, mechanization, processing (value addition), commercialization and integration in the lentil seed industry. In developed countries (e.g. Australia, Canada and the USA) lentil is grown as a crop for export, characterized with high adoption of improved varieties and production technologies. In the traditional lentil-producing developing countries (e.g. India, Iran, Syria and Turkey) lentil is grown as a subsistence crop primarily for local consumption with limited use of improved varieties and technologies. The status of the lentil seed industry in the developed and developing countries is presented below.

Developed countries Australia, Canada and the USA are the major global players in production and export of lentil, overtaking traditional producers (and exporters) from developing countries such as India, Iran, Syria and Turkey. In the developed countries, lentil has been introduced as part of an agricultural diversification programme in a cereal-dominated production and export market. Bishaw et al. (2009) summarized key features that distinguish the legume seed industry in the developed and developing economies, which is equally applicable to lentils. First, in developed countries, lentils are produced on a large scale (>200 ha by individual farmers) and considered as an export commodity to diversify the product portfolio replacing cereal crops. Legume production is market oriented where farmers are willing to adopt technology and adjust production factors accordingly compared to subsistence production in the developing countries. Second, there is strong public-private partnership where both the government and the private sector are funding agricultural research and variety development (Gareau et al., 2000). Accordingly, farmers in Australia and Canada pay a levy on total production or the amount of grain marketed which is matched or supplemented by the government or the industry to support research and commercialization. A similar approach was initiated in Turkey (Küsmenogˇlu, 2003). Third, there is strong integration of agricultural research, seed production and seed use where the private seed companies and/or farmers play a key role in commercialization of released varieties. Fourth, although legumes are inherently low-profit crops, the availability of good infrastructure and socio-economic conditions ensure a reasonable profit, thus providing sufficient incentive to attract private sector investment. The presence of market-oriented and/or export-led commercial agriculture remains the major driving force for the development of a vertically

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organized and sustainable lentil seed industry. The net result is that agricultural research, variety development, seed production and marketing, and grain processing and marketing are well integrated across a wide spectrum of the legume industry (i.e. the government, farmer growers, industrial processors and exporters).

Developing countries Among the developing economies India, Iran, Nepal, Syria and Turkey are leading lentil producers. Lentil production is largely subsistence and produced by small-scale farmers (holding size <10 ha) with the primary objective of household consumption and a little surplus for market. Lentil production is characterized by a low level of mechanization, minimal use of technology-related inputs (e.g. seed, fertilizer, irrigation, rhizobial treatments and agrochemicals such as herbicides, etc.) and is mostly in dry rainfed environments. In most developing countries, in view of national food security the formal seed sector focuses on major food crops at the expense of low-priority legume crops (e.g. lentil). For example, in Ethiopia and Syria the seed industry for all food crops is handled by the public sector, but from the total amount of seed supplied, legumes, including lentil, account for less than 5% compared to a single major cereal crop like wheat which accounts for almost 70% of seed production (Bishaw, 2004). Farmers, particularly in dry areas, not only lack access to modern varieties and good quality seed, but may also not be able to afford to pay a higher price for seed, and therefore use their own seed or any seed, even commercial grain, purchased from local markets or traders for planting. In India, the leading global lentil producer, more than 95% of lentil seed comes from the informal sector (Materne and Reddy, 2007). Similarly in Turkey, a large proportion of seed for planting comes from the informal sector and a very small fraction from a formal sector with no or limited private sector involvement (Küsmenogˇlu, 2003). There is a missing link between public plant breeding and public seed delivery. As lentils are considered to be a low-profit crop by the private sector, organized seed production did not show a better record even in countries where privatization of the seed sector has made some progress (e.g. India, Morocco, Turkey). There are many policy, regulatory, institutional, organizational, technical and socio-economic constraints that affect the seed industry of legumes in general and lentil in particular in the developing countries.

Constraints to the lentil seed industry Bishaw et al. (2009) summarized the constraints of the legume seed industry which also apply to lentils in the developing countries. Apart from policy and regulatory constraints there are technical constraints which hinder the

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lentil seed sector including the availability, access and use of varieties and seeds, agricultural mechanization, high disease pressure (diseases, pests, parasitic weeds), high seed production costs, etc.

Availability of quality seed Table 22.1 shows seed production and distribution from a few selected CWANA countries. For example Ethiopia, Iran, Morocco, Pakistan, Syria and Turkey are major lentil producers in their respective regions (see Erskine, Chapter 2, this volume). However, the amount of seed distributed by the formal sector remains insignificant compared to cereals. In almost all countries, lentil seed production accounts for less than 5% of the formal sector seed supply. Moreover, the amount of seed supplied compared to national demand is pitiable. In Ethiopia the amount of seed distributed by the formal sector met only 11.2% of demand for lentil seed in 2005, and this was because of specific government intervention which was otherwise nonexistent earlier (e.g. 0.7% in 2004). Similarly, in Morocco the formal sector on average provides 7% of seed for food legumes (1% each for faba bean, chickpea and lentil and 34% for peas). Lentil seed supply is not only low, but also fluctuates between years. For example in Syria lentil seed supply from the formal sector was 1.2 and 11.2% in 2003 and 2004, respectively. Low commercial seed supply was also reported in Morocco, Syria, Tunisia and Turkey (Oram and de Haan, 1995; Küsmenogˇlu and Kugbei,

Table 22.1. region.

Seed production and/or distribution (t) in selected countries of the CWANA

Lentil (%) Countrya

Totalb

Cereals

Legumes

CSFLc

Lentil

Total

Legumes

Ethiopia* Morocco* Pakistan* Syria* Turkey** Yemen** Total

13,656 67,620 191,043 104,137 263,105 1,643 641,204

11,929 64,900 188,582 102,364 260,688 1,643 630,106

1,628 2,460 1,011 1,768 66 – 6,933

1,380 2,460 572 1,768

729 60 – 818 5 – 1,612

5.3 0.1 – 0.8 0.002 – 0.3

44.8 2.4 – 46.3 7.6 – 23.3

aFigures

– 6,180

are from different years (*for 2005, **for 2004) and sources (from unpublished internal reports, documents, presentations and personal communications with seed sector institutions in the respective countries including: Ethiopian Seed Enterprise (ESE); Service du Controle des Semences et des Plantes (DPVCTRF), Morocco; Federal Seed Certiﬁcation and Registration Department (FSCRD), Pakistan; General Organization for Seed Multiplication (GOSM), Syria; and General Corporation for Seed Multiplication (GCSM), Yemen). bThe total includes cereal, legume and oilseed crops, whereas CSFL comprise faba bean, pea, chickpea and lentil seed only. cCSFL, cool season food legumes.

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2000). Materne and Reddy (2007) also cited over 95% seed supply from the informal sector as a major constraint for lentil production in India. There is no reliable information on lentil seed supply in some other major lentilproducing countries like Iran, Pakistan and Yemen.

Mechanization problems Lentil production has been mechanized in the developed countries. Despite the availability of mechanical operations elsewhere lentil is still under a traditional production system with little mechanization in the developing countries (Sarker and Erskine, 2002). Such technical constraints, for example, limited contractual lentil seed production with state farms in Ethiopia. Traditional planting and harvesting methods still continue to persist among small-scale farmers who lack the resources to adopt new technologies.

High production costs Legume production in general, and lentil in particular, requires regular sprays for diseases and parasitic weeds, need for special equipment for planting and harvesting, etc., which add to the cost of production of a crop which is already at a low level of profitability. Among production costs, harvesting alone contributes more than half of the total cost in some countries. It is reported that hand harvesting has led to a reduction in area under lentil due its high cost (Erskine et al., 1991). Oram and de Haan (1995) cited high seed cost as a disincentive against adoption of improved varieties. All these technical problems combined with price uncertainty exacerbate the problem of the lentil seed industry.

22.7. Alternatives for Lentil Seed Delivery Substantial increase in lentil production and productivity can be achieved only with the use of quality seed of improved varieties. A concerted effort is required to develop a strategy to achieve sustainable lentil production through conventional and participatory approaches in plant breeding and formal and farmer-based seed provisions. The demand for lentil seed is diverse because of diverging interests, production environments and differences between socio-economic conditions of commercial and subsistence farmers. Moreover, lentil is a high-volume, less profitable crop and neither the public sector nor the private sector is willing to invest in seed production and marketing, particularly in the developing countries. An innovative alternative approach needs to be designed to ensure sustainable lentil seed supply to farmers.

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Formal seed supply In the developed countries, the success of the cereal and legume seed industry has often resulted from integration of agricultural research, production technology, input supply, market support and extension information. According to Byerlee and White (2000), the success and rapid expansion in soybean production is attributed to investments in research, effective extension programmes, price support, encouragement to the processing industry, and facilitating export markets. They suggested that similar efforts are needed for legumes in developing countries.

Farmer-based seed supply In this chapter farmer-based seed production is used loosely and broadly to describe seed production and supply with or by farmers even when they differ greatly in scope and ownership among themselves. Several approaches are used by different stakeholders to involve farmers in local seed production, including genetic resource conservation, crop improvement, variety popularization and seed supply. In the context of seed delivery, farmerbased seed production and marketing implies farmers’ ownership and responsibility for operating independently an enterprise with commercial intent to ensure profitability and sustainability. It could be a small-scale enterprise owned and managed by one or a few persons who are engaged not only in production but in marketing of seed as well. At the community level, these may be individual farmers, a group of farmers, traders or merchants, cooperatives, or farmers’ associations (Kugbei and Bishaw, 2002).

Non-commercial seed supply Finding alternative strategies to enhance rapid dissemination of new crop varieties and seeds among farming communities are crucial to realize the impact of crop improvement research. Non-market intervention is one of the alternative strategies for seed distribution owing to the failure of public and private sectors in providing seed to small-scale farmers. Grisley (1993) suggested a non-commercial approach for crops not handled by the formal sector, where seed packets are distributed in small quantities to farmers to encourage informal varietal diffusion and adoption rather than regular seed production and supply for beans in sub-Saharan Africa. A follow-up study showed farmers continue growing the variety and exchange with other farmers after the initial supply of seeds. Jones et al. (2001) also reported successful dissemination of a modern pigeon pea variety from injection of seed in a single demonstration trial in Kenya. It was reported from Ethiopia that 211 farmers in ten districts produced 88 t of faba bean, pea, chickpea and lentil (4 t) seeds for informal diffusion (ICARDA, 2006) in the absence of seed supply from the formal sector.

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Village-based seed enterprises David (2004), drawing on experience from Uganda, reported on the role of farmer seed enterprises as a tool to ensure sustainable seed production and marketing of new crop varieties as well as a regular source of clean seed. Therefore, it is important to institutionalize local seed production and marketing by establishing a technically sound and economically viable seed business by mobilizing and ensuring the participation of farming communities. ICARDA is currently exploring alternative approaches for seed delivery for crops where neither the public nor the private sector is able to serve smallscale farmers. The objective is to establish village-based seed enterprises (VBSE) to produce and market quality seed in selected communities. The VBSEs are farmer-based seed production and marketing schemes operating at local level to ensure availability and access to varieties and seeds by farmers in less favourable environments and remote areas. The system works primarily by organizing volunteer farmers into local ‘seed production and marketing enterprises’. There are several advantages for organizing local seed production and marketing units as summarized below (Bishaw and van Gastel, 2008).

Key elements for the success of village-based seed enterprises There are a few prerequisites for establishing and successful operation of VBSEs: ●

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Regular seed demand – from farmers within community, neighbouring villages or districts. Reasonable seed price – seed should be affordable by farmers and proﬁtable for producers. Appropriate seed quality – seed should be consistently of higher quality than farm-saved or locally exchanged seed. Enterprise ownership – farmers should take responsibility for managing and operating the enterprises. Business plans – there should be appropriate training in developing tailor-made business plans based on demand analysis.

Establishing village-based seed enterprises The initiatives involving farmers is often top-down, based on presumptions of development agencies rather than on critical appraisal of situations on the ground. A number of steps to be followed for successful establishment of VBSEs are given below (Fig. 22.1). ●

Stakeholder’s consultation – convene multi-institutional multi-stakeholders consultation meeting to build consensus and solicit interest in and support for VBSEs, and determine their roles and responsibilities in supporting operations and implementations.

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Profitability Seed marketing

Performance analysis for profitability and sustainability

Pricing, market information, marketing linkages created

Quality control

Guidelines and procedures for quality control adopted

Seed production

Informal seed-production scheme developed and adopted

Enterprise management

Operational mechanism established and business plan developed

Establish farmer groups

VBSE formally constituted and trained (technical, financial, managerial)

Identify seed demand

Farmer participation in problem diagnosis and making decisions

Fig. 22.1. Steps in establishing village-based seed enterprises (VBSEs) (Source: Bishaw and van Gastel, 2009).

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Seed system analysis – conduct seed system analysis prior to establishing VBSEs to assess whether there is real seed demand in partnership with stakeholders identiﬁed during the consultative process. Identifying target areas and groups – VBSEs should target: (i) farmers lacking access to improved crop varieties and seeds from the formal sector; (ii) resource-poor small farmers with limited opportunities; (iii) remote and isolated areas with poor infrastructure; and (iv) less favourable areas with limited commercial crop production. Selecting farmers – the participating farmers must be interested in setting up a seed business as an alternative to grain production; and they should be selected based on criteria of high reputation in the community, experience in farming/seed production, relatively bigger/better land holdings, entrepreneurial skills and ﬁnancial resources. Forming seed-producer groups – farmer participation and empowerment are key elements of the VBSE programme. Farmers should take full responsibility and leadership and elect their own leaders, whereas partners facilitate, provide guidance and advice. Selecting seed-production sites – the land selected must be suitable for quality seed production: fertile soils, reliable rainfall (or irrigation), low

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incidence of diseases, pests and weeds, proximity and accessibility to main roads and other facilities. Preparing a business plan – the plan should consider all factors affecting the enterprise: strengths, weaknesses, risks, products, markets, costs, proﬁts, etc. It also includes ownership, management, legal structure, staff, equipment and budget. Producing and marketing seed – all seed-production and marketing operations are carried out by the VBSE members. Promotional efforts and marketing are required to ensure success. Conducting proﬁtability analysis – farmers’ commitment in ownership and proﬁtability of the business are the driving forces for long-term sustainability. This will help members in making informed decisions in planning and diversiﬁcation.

Linking and supporting village-based seed enterprises The strategy of involving stakeholders and encouraging them to work towards an annual business plan based on demand-led production is critical to develop financially profitable and sustainable seed production and marketing enterprises. Key aspects of partner support are described below: ●

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Sourcing seed and other inputs – partners help the VBSEs to source early generation seed of varieties most adapted to their areas from National Agricultural Research Systems (NARS) or the formal sector. Similarly, the partners assist the VBSEs to source inputs (fertilizers, pesticides) required for quality seed production. Producing seed – partners provide training, guidance and assistance, to ensure that VBSE members have the skills and knowledge necessary to produce seed that meets quality standards. Processing and storing seed – the VBSEs ensure that they are able to acquire simple low-cost mobile cleaner and treater prototypes which can be easily maintained and modiﬁed locally. The partners may also help building appropriate seed storage facilities. Controlling seed quality – partners train VBSE members to carry out ﬁeld inspections and simple seed quality tests or provide services through the formal sector. Marketing seed – promotional activities should be conducted through on-farm demonstrations of varieties, organizing ﬁeld days for neighbouring farmers and providing market information through ministries, extensions services or non-governmental organizations (NGOs). Accessing credit – the VBSEs need access to credit for purchasing farm machinery, inputs (e.g. source seed, fertilizers and pesticides) and seed handling equipment (for cleaning, treatment and packaging). Building capacity – training will be implemented to build, step-by-step, farmers’ technical (planting, harvesting, cleaning, treatment, testing, storage), ﬁnancial and management skills (daily operation of enterprises, record keeping, developing business plans).

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Evaluating and monitoring – establish procedures for regular reporting and identify key indicators against which the progress and performance of VBSEs are measured. Establishing a network of VBSEs – assist to establish a network of VBSEs to link with input providers and stakeholders to facilitate market information and sharing of experience. Linking with local agro-industries – create linkages between farmers and local agroprocessing enterprises to create a market for produces which will then stimulate use of better technology, creating a demand for seed among farming communities.

A detailed work plan and timetable should be developed for the implementation of the VBSEs. The commitment of all partners to the work plan and timetable ensures timely and successful execution of the planned activities.

22.8. Conclusion Although global lentil production has increased during the last few decades, its availability per capita has declined with increasing population, particularly in South Asia (McNeil et al., 2007). There is an increasing demand for lentil in the developing countries where it is a prominent part of the human diet. Developing improved varieties with a high and stable yield that is tolerant to biotic and abiotic stresses is a prerequisite for increasing lentil production. Apart from improved varieties, developing and transferring appropriate production technologies, reducing production risks and costs, ensuring markets and a well-defined pricing policy are the basic requirements for sustainable legume production (Byerlee and White, 2000). In the developing countries, lentil seed supply is primarily dominated by the informal sector, as is the case with India (Materne and Reddy, 2007). However, addressing policy, regulatory, technical, institutional, organizational and socio-economic constraints will encourage development of a robust seed industry involving both formal and informal sectors to serve the diverse seed users. The integration of research, seed supply, processing and marketing is the only viable option in this endeavour. The private sector initiative from Turkey could serve as a model for promoting the adoption and diffusion of new lentil varieties elsewhere in the face of public sector failures in delivery of improved varieties and seeds. While encouraging the formal private sector to increase the availability of seed, at present the establishment of technically feasible and economically viable farmer seed enterprises (David, 2004) is the best alternative option for lentils.

References Ali, M. Omar, Sarker, A., Rahman, M.M., Gahoonia, T.S. and Uddin, M.K. (2005) Improvement of lentil yield through seed priming in Bangladesh. Journal of Lentil Research 2, 54–59.

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Bishaw, Z. (2004) Wheat and barley seed systems in Ethiopia and Syria. PhD thesis, Wageningen University, Wageningen, The Netherlands. Bishaw, Z. and van Gastel, A.J.G. (2008) ICARDA’s approach in seed delivery for less favorable areas through village-based seed enterprises: conceptual and organizational issues. Journal of New Seeds 9(1), 68–88. Bishaw, Z., Niane, A.A. and Gan, Y. (2007) Quality seed production. In: Yadav, S.S., McNeil, D.L. and Stevenson, P.C. (eds) Lentil: an Ancient Crop for Modern Times. Springer, Dordrecht, The Netherlands, pp. 349–383. Bishaw, Z., van Gastel, A.J. and Gregg, B.R. (2009) Sustainable seed production of cool season food legumes in CWANA region. In: Kharkwal, M.C. (ed.) Proceedings of Fourth International Food Legumes Research Conference (IFLC-IV), 18–22 October 2005, New Delhi, India. Indian Society of Genetics and Plant Breeding, New Delhi, India. Byerlee, D. and White, R. (2000) Agricultural systems intensification and diversification through food legumes: technological and policy options. In: Knight, R. (ed.) Linking Research and Marketing Opportunities for Pulses in the 21st Century. Proceedings of the Third International Food Legumes Research Conference (IFLRC III), 22–26 September 1997, Adelaide, South Australia. Kluwer Academic Publishers, Dordrecht, The Netherlands, pp. 31–46. David, S. (2004) Farmer seed enteprises: a sustainable approach to seed delivery? Agriculture and Human Values 21, 387–397. Ellis, R.H., Hong, T.D. and Roberts, E.H. (1987) The development of desiccationtolerance and maximum seed quality during seed maturation in six grain legumes. Annals of Botany 59, 23–29. Emami, M.K. and Sharma, B. (1996a) Digenic control of cotyledon colour in lentil (Lens culinaris). Indian Journal of Genetics and Plant Breeding 56(3), 357–361. Emami, M.K. and Sharma, B. (1996b) Confirmation of digenic inheritance of cotyledon colour in lentil (Lens culinaris). Indian Journal of Genetics and Plant Breeding 56(4), 563–568. Erskine, W., Diekmann, J., Jegatheeswaran, P., Salkini, A.B., Saxena, M.C., Ghanaim, A. and El Ashkar, F. (1991) Evaluation of lentil harvest systems for different sowing methods and cultivars in Syria. Journal of Agricultural Science 117, 333–338. Expósito, M.J., Torres, L.G. and Muñoz, M.C. (1997) Broad bean and lentil seed treatments with imidazolinones for the control of broomrape (Orobanche crenata). Journal of Agricultural Science 129, 307–314. Fougereux, J. (2000) Germination quality and seed certification in grain legume. Special Report. Grain Legumes 27, 14–16. Gan, Y., Hanson, K.G., Zentner, R.P., Selles, F. and McDonald, C.L. (2005) Response of lentil to microbial inoculation and low rates of fertilization in semiarid Canadian prairies. Canadian Journal of Plant Science 85, 847–855. Gareau, R.M., Muel, F. and Lovett, J.V. (2000) Trends in support for research and development of cool season food legumes in the developed countries. In: Knight, R. (ed.) Linking Research and Marketing Opportunities for Pulses in the 21st Century. Proceedings of Third International Food Legumes Research Conference (IFLRC III), 22–26 September 1997, Adelaide, South Australia. Kluwer Academic Publishers, Dordrecht, The Netherlands, pp. 59–66. Grisley, W. (1993) Seed for bean production in Sub-Saharan Africa: issues, problems and possible solutions. Agricultural Systems 43, 19–33. Gupta, S. and Bhowmick, M.K. (2005) Scope of growing lathyrus and lentil in relay cropping systems after rice in West Bengal, India. Lathyrus Lathyrism Newsletter 4, 28–33.

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Z. Bishaw et al. Hampton, J.G. and Coolbear, P. (1990) Potential versus actual seed performance: can vigour testing provide an answer? Seed Science and Technology 18, 215–228. Harris, D. (2006) Development and testing of ‘on-farm’ seed priming. Advances in Agronomy 90, 129–178. Huang, H.C. and Erickson, R.S. (2007) Effect of seed treatment with Rhizobium leguminosarum on Pythium damping-off, seedling height, root nodulation, root biomass, shoot biomass, and seed yield of pea and lentil. Journal of Phytopathology 155(1), 31–37. International Center for Agricultural Research in the Dry Areas (ICARDA) (2006) Farmer participatory seed production of improved varieties of cool season food legumes and durum wheat. In: Technology Generation and Dissemination for Sustainable Production of Cereals and Cool Season Food Legumes: Progress Report, Third Season 2004–05. ICARDA, Aleppo, Syria, pp. 138–142. Johansen, C., Baldev, B., Brouwer, J.B., Erskine, W., Jermyn, W.A., Li-Juan, L., Malik, B.A., Miah, A.A. and Silim, S.N. (1994) Biotic and abiotic stresses constraining productivity of cool season food legumes in Asia, Africa and Oceania. In: Muehlbauer, F.J. and Kaiser, W.J. (eds) Expanding the Production and Use of Cool Season Food Legumes (IFLRC II). Kluwer Academic Publishers, Dordrecht, The Netherlands, pp. 175–194. Jones, R.B., Audi, P.A. and Tripp, R. (2001) The role of informal seed systems in disseminating modern varieties: the example of pigeon pea from a semi-arid area of Kenya. Experimental Agriculture 37, 539–548. Kaiser, W.J. and Hannan, R.M. (1987) Seed treatment fungicides for control of seed borne Ascochyta lentis on lentil. Plant Disease 71, 58–62. Kaiser, W.J., Ramsey, M.D., Makkouk, K.M., Bretag, T.W., Açikgöz, N.A., Kumar, J. and Nutter, F.W. Jr (2000) Foliar diseases of cool season food legumes and their control. In: Knight, R. (ed.) Linking Research and Marketing Opportunities for Pulses in the 21st Century. Proceedings of the Third International Food Legumes Research Conference (IFLRC III), 22–26 September 1997, Adelaide, South Australia. Kluwer Academic Publishers, Dordrecht, The Netherlands, pp. 437–455. Kugbei, S. and Bishaw, Z. (2002) Policy measures for stimulating indigenous seed enterprises. Journal of New Seeds 4, 47–63. Küsmenogˇlu, I. (2003) Participatory transfer of integrated technology: a promising approach to increase food legume production in Turkey. Seed Information 25, 14–17. Küsmenogˇlu, I. and Kugbei, S. (2000) Developing small-scale seed enterprises for food legumes in Turkey. In: Kugbei, S., Turner, M. and Witthaut, P. (eds) Finance and Management of Small-Scale Seed Enterprises. International Center for Agricultural Research in the Dry Areas (ICARDA), Aleppo, Syria, pp. 123–128. Lakhani, J.P., Holkas, S. and Mishra, R. (1986) Genetics of seedling vigour and hard seed in lentil. Lens 13(2), 781–784. Makkawi, M. and van Gastel, A.J.G. (2006) Effect of accelerated ageing on germination and vigor in lentil (Lens culinaris Medikus) seed. Journal of New Seeds 8(3), 87–98. Makkawi, M., El Balla, M., Bishaw, Z. and van Gastel, A.J.G. (1999) The relationship between seed vigor tests and field emergence in lentil (Lens culinaris Medikus). Seed Science and Technology 27, 657–668. Makkawi, M., El Balla, M., Bishaw, Z. and van Gastel, A.J.G. (2008) Electrical conductivity in lentil seed leachates using a single seed analyser. Journal of New Seeds 9(4), 267–283. Materne, M. and Reddy, A.A. (2007) Commercial cultivation and profitability. In: Yadav, S.S., McNeil, D.L. and Stevenson, P.C. (eds) Lentil: an Ancient Crop for Modern Times. Springer, Dordrecht, The Netherlands, pp. 173–186.

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McNeil, D.L., Hill, G.D., Materne, M. and McKenzie, B.A. (2007) Global production and world trade. In: Yadav, S.S., McNeil, D.L. and Stevenson, P.C. (eds) Lentil: an Ancient Crop for Modern Times. Springer, Dordrecht, The Netherlands, pp. 95–105. Morrall, R.A.A. and Sheppard, J.W. (1981) Ascochyta blight of lentils in western Canada. Canadian Plant Disease Survey 6, 7–13. Muehlbauer, F.J., Cubero, J.I. and Summerfield, R.J. (1985) Lentil (Lens culinaris Medic.). In: Summerfield, R.J. and Roberts, E.H. (eds) Grain Legume Crops. Collins, London, UK, pp. 266–311. Neupane, R.K. (2002) Effect of seed priming on growth and yield of lentil variety ‘Khajura Masuro 2’. In: Neupane, R.K., Yadav, N.K. and Darai, R. (eds) Proceedings of National Winter Crops Workshop, 12–14 September 2002, Bara, Nepal. Regional Agricultural Research Station, Parwanipur, Nepal, pp. 59–62. Oram, A. and de Haan, C. (1995) Technologies for Rainfed Agriculture in Mediterranean Climates: a Review of World Bank Experiences. World Bank Technical Paper 300. Washington, DC, USA, 168 pp. Sardana, V., Sheoran, P. and Singh, S. (2006) Effect of seed rate, row spacing, rhizobium and nutrient application on yield of lentil under dryland conditions. Indian Journal of Pulses Research 19(2), 216–218. Sarker, A. and Erskine, W. (2002) Lentil production in the traditional lentil world. In: Brouwer, J.B. (ed.) Proceedings of Lentil Focus 2002, Horsham, Victoria, Australia. Pulse Australia, Sydney, pp. 35–40. Sarker, A., Siddique, K.M.H. and Loss, S.P. (1995) Adaptation of Lentil in Western Australia: Germplasm Evaluation in 1994. Occasional Paper No. 9. Cooperative Research Center for Legumes in Mediterranean Agriculture (CLIMA), Perth, Australia. Sharma, B. and Emami, M.K. (2002) Discovery of a new gene causing dark green cotyledons and pathway of pigment synthesis in lentil (Lens culinaris Medik.). Euphytica 124(3), 349–353. Taylor, P., Lindbeck, K., Chen, W. and Ford, R. (2007) Lentil diseases. In: Yadav, S.S., McNeil, D.L. and Stevenson, P.C. (eds) Lentil: an Ancient Crop for Modern Times. Springer, Dordrecht, The Netherlands, pp. 291–313. Yadav, S.S., Rizvi, A.H., Manohar, M., Verma, A.K., Shrestha, R., Chen, C., Bejiga, G., Chen, W., Yadav, M. and Bahl, P.N. (2007) Lentil growers and production systems around the world. In: Yadav, S.S., McNeil, D.L. and Stevenson, P.C. (eds) Lentil: an Ancient Crop for Modern Times. Springer, Dordrecht, The Netherlands, pp. 415–442.

23

Nutritional and Health-beneficial Quality Michael A. Grusak

USDA/ARS Children’s Nutrition Research Center, Baylor College of Medicine, Houston, Texas, USA

23.1. Introduction Lentil (Lens culinaris subsp. culinaris Medik.) is an ancient, domesticated legume that has been nourishing humans for millennia (Erskine, 1997; Sandhu and Singh, 2007). As with most pulse seeds, lentil can provide several dietary nutrients; these include amino acids (in the form of protein), energy (primarily in the form of starch), most essential minerals and several vitamins. They also contain various compounds that are believed beneficial to the promotion of good health, as well as several anti-nutrients. In this chapter, we will review existing data on the types of nutrients and health-promoting phytochemicals reported for lentils, and will provide information on the general range of values measured in lentil seeds. We will discuss to what extent these levels might contribute to human dietary needs when lentils are consumed in normal serving sizes, taking into account possible anti-nutrients also contained in the seeds. Finally, we will discuss the influence of different processing methods on the nutritional value of lentil products. Additional information on some of these topics can be found in recent and earlier reviews (Abu-Shakra and Tannous, 1981; Hulse, 1994; Urbano et al., 2007).

23.2. Nutritional Composition The nutritional value of any given lentil variety will be dictated by its genetics, in combination with its ability to make use of various environmental resources (e.g. soil parameters, agronomic practices, temperature, rainfall, etc.) and/or its ability to cope with diverse environmental constraints (biotic and abiotic stress). In other words, the compositional phenotype of harvested lentil seeds is as dependent on genotype-by-environment interactions as are 368

© CAB International 2009. The Lentil: Botany, Production and Uses (eds W. Erskine et al.)

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Table 23.1. Proximate composition of whole, dry lentil seeds (per 100 g dry matter) (Source: see table footnotes). Component Energy (kJ) Protein (g) Carbohydrates (g) Fat (g) Total ﬁbre (g) Ash (g)

Range of published valuesa 1418–2010 15.9–31.4 43.4–74.9 0.3–3.5 5.1–26.6 2.2–6.4

Lentil (mean values)b 1638 28.3 67.1 2.5 12.2 2.2

a Values derived from the following references: Kylen and McCready (1975); El-Nahry et al. (1980); Souci et al. (1989); Jood et al. (1998); Solanki et al. (1999a, b); Sotomayor et al. (1999); Ereifej and Haddad (2000); Cai et al. (2002); Porres et al. (2002); El-Adawy et al. (2003); Wang and Daun (2004, 2006); de Almeida Costa et al. (2006); Iqbal et al. (2006); Amir et al. (2007); Ryan et al. (2007); USDA/ARS (2007). b Values derived from USDA/ARS (2007), Nutrient Database No. 16144, lentils, pink, raw.

other phenotypic traits, such as yield, disease resistance, time to flowering, etc. None the less, there are general tendencies that have been reported for the components of lentil seeds; these will be discussed in detail in the following sections. The gross proximate composition for lentil (range of values) is presented in Table 23.1, along with mean values for one lentil type.

Energy The energy value of a food provides a gross assessment of the potential energy stored within that food’s chemical bonds. This energy is critical for humans, as it is needed to sustain all the body’s functions, including protein synthesis, respiration, circulation, general metabolism and physical activity. Energy values for lentil range from 1418 to 2010 kJ/100 g dry matter (Table 23.1), which is equivalent to caloric values of 339–480 kcal/100 g dry matter. Most of the energy comes from starch, the primary component of lentil seeds, although non-starch carbohydrates, protein and lipids also contribute to the energy value. The energy range for lentil is similar to that of chickpea (Cicer arietinum L.) (Wood and Grusak, 2007), but is much lower than that of legumes such as soybean (Glycine max L.) or groundnut (Arachis hypogea L.), with their higher oil content (USDA/ARS, 2007).

Protein and amino acids Legume seeds are known for their high protein content, especially when compared to other plant foods such as cereal grains, most root crops, fruit and vegetables. Reported protein values for lentil range from 15.9 to 31.4 g/100 g dry matter (Table 23.1). Most of the seed protein is stored in the cotyledons, with the majority of the protein consisting of salt-soluble globulins (storage proteins) that are stored in protein bodies. The remainder

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belongs to the albumin fraction, which includes many housekeeping proteins, lectins and lipoxygenases (Bhatty and Christison, 1984; Bhatty, 1986; Wang et al., 2003). The nutritional value of lentil protein is determined by its amino acids, which are needed by humans to build and/or repair structural proteins, enzymes, peptides, antibodies, neurotransmitters and other important components (Reeds and Beckett, 1996). Lentil has a generally good amino acid pattern, in that it contains all the human essential amino acids, and with most of them occurring in proportions recommended for humans by the World Health Organization (WHO) (Table 23.2). The exceptions are the sulfurcontaining amino acids, methionine and cysteine, which (as with most legume seeds) are the most limiting of the amino acids. On the other hand, lentil has adequate to high levels of lysine. This is why lentil and other legumes are suggested as ideal complementary foods to cereals (rice, wheat, maize), which are low in lysine and generally better sources of the sulfur amino acids (Shewry and Halford, 2002). Table 23.2. Amino acid composition (g/16 g N) for whole, dry lentil seeds and Food and Agriculture Organization (FAO)/World Health Organization (WHO)/United Nations University (UNU) recommended proportional pattern for essential amino acids (g/16 g N) in children (Source: see table footnotes).

Amino acid Histidine (His) Isoleucine (Ile) Leucine (Leu) Lysine (Lys) Threonine (Thr) Tryptophan (Trp) Valine (Val) Tyrosine (Tyr) Phenylalanine (Phe) Methionine (Met) Cysteine (Cys) Alanine (Ala)e Arginine (Arg)e Aspartate (Asp)e Glutamate (Glu)e Glycine (Gly)e Proline (Pro)e Serine (Ser)e

Published range for lentila 1.3–3.4 2.6–5.5 5.7–8.7 4.0–8.2 2.5–4.9 0.6–2.6 3.3–6.1 1.1–3.6 3.6–5.8 0.8–1.3 0.7–1.5 2.4–5.0 3.9–11.1 9.3–15.9 12.8–18.5 3.3–5.6 1.2–7.2 2.9–6.4

Pattern for 1-year-old childb

Pattern for pre-school child (2–5 years old)b

2.6 4.6 9.3 6.6 4.3 1.7 5.5 7.2c

1.9 2.8 6.6 5.8 3.4 1.1 3.5 6.3c

4.2d

2.5d

– – – – – – –

– – – – – – –

a Values derived from the following references: Shekib et al. (1986); Combe et al. (1991); Kavas and Nehir (1992); Urbano et al. (1995); Carbonaro et al. (1997); Porres et al. (2002); Wang and Daun (2004, 2006). b Values from FAO/WHO/UNU (1985). c Combined recommended pattern for tyrosine plus phenylalanine. d Combined recommended pattern for methionine plus cysteine. e Non-essential amino acids.

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A more direct way to view the potential amino acid value of lentil is to compare its essential amino acid composition in an average serving size (100 g cooked, half a cup in the USA, for a young child; 200 g cooked, one cup in the USA, for a boy or adult) with the daily US Recommended Dietary Allowance (RDA) for these nutrients (Table 23.3). Again it can be seen that methionine and cysteine are the most limiting amino acids, providing only 19–20% of the RDA for a boy or an adult and 29% for a young child. These single servings provide roughly 30–60% of the RDA for most of the other essential amino acids, and effectively the full RDA for tryptophan. Note that tryptophan levels are low in lentil (Tables 23.2, 23.3), relative to most of the other amino acids; however, human dietary requirements are also lower for tryptophan.

Carbohydrates The principal nutritional component of lentil seeds is the carbohydrate fraction, which can range from 43.4 to 74.9 g/100 g dry matter (Table 23.1). Carbohydrates can be divided into four major classes: monosaccharides, disaccharides, oligosaccharides and polysaccharides. Monosaccharides and disaccharides Monosaccharides are single sugar moieties, such as glucose and fructose, while disaccharides contain two monosaccharides connected via a glycosidic bond (e.g. sucrose, made from glucose plus fructose). Free mono- and disaccharides are readily absorbed and/or metabolized in the human digestive tract, and thus are a quick source of energy. However, mature lentil seeds contain low levels of free soluble sugars (2.3–8.9 g/100 g dry matter), with fructose (0.01–0.30% dry matter) reported as the main monosaccharide and sucrose (1.1–3.0% dry matter) as the predominant disaccharide (Table 23.4). Free glucose has not been found or has been reported in only trace amounts in mature lentil seeds (0.04% of dry matter), whereas maltose (a disaccharide formed from two glucose subunits joined by an α(1→4) linkage) has been detected in higher amounts (up to 0.33% dry matter (Nutrient Database No. 16069), USDA/ARS, 2007). Oligosaccharides Oligosaccharides are short polymers that generally are composed of three to ten monosaccharides. Most oligosaccharides are not digested in the small intestine and thus move on to the large bowel where they are metabolized (fermented) by colonic bacteria. This activity releases gases (e.g. hydrogen, carbon dioxide, methane) that can promote flatulence. Lentils contain several raffinose-family oligosaccharides, including stachyose (up to 3.1% dry matter), raffinose and verbascose (Table 23.4). Lentils also contain the oligosaccharide ciceritol (up to 2% dry matter), whose name comes from chickpea (Cicer arietinum) where it was first identified. Ciceritol does not belong

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Table 23.3.

Contribution of lentil to human essential amino acid needs at different life stages (Source: see table footnotes).

Amino acid

g/16 g Na

mg/200 g cooked (one cup serving)b

His Ile Leu Lys Thr Trp Val Tyr + Phe Met + Cys

2.4 3.3 6.4 5.7 4.1 2.5 4.0 6.9 1.8

379 521 1010 900 646 394 632 1088 284

Child RDAb (mg) for 4–8 year old @ 22 kg 352 484 1078 1012 528 132 616 902 484

RDA (%) in 100 g cooked 54 54 47 44 61 149 51 60 29

Child RDAc (mg) for 9–13-yearold boy @ 37 kg

RDA (%) in 200 g cooked

629 814 1813 1702 888 222 1036 1517 814

60 64 56 53 72 177 61 72 35

Adult RDAc (mg) for 19+ year RDA (%) in 200 g old @ cooked 75 kg 1050 1425 3150 2850 1500 375 1800 2475 1425

36 36 32 32 42 105 35 44 20

Pregnant woman RDAc (mg) for all ages @ 60 kg

RDA (%) in 200 g cooked

1080 1500 3360 3060 1560 420 1860 2640 1500

35 35 30 29 41 94 34 41 19

a Mean

values from Wang and Daun (2004) for Canadian green lentils. calculated from previous column, using an average % protein = 26.3 (equivalent to % N = 4.21) (Wang and Daun, 2004), and assuming 70% water in the cooked lentil seeds. c Calculated from US Recommended Dietary Allowance (RDA) Tables for amino acids (Institute of Medicine, 2006). b Values

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Table 23.4. Carbohydrate composition of whole, dry lentil seeds (g/100 g dry matter) (Source: see table footnote). Carbohydrate Starch Total soluble sugars Sucrose Fructose Glucose Total α-galactosides Rafﬁnose Stachyose Verbascose Ciceritol Maltose

Reported rangea 34.7–65.0 2.3–8.9 1.1–3.0 0.01–0.30 0–0.04 1.8–6.8 0.16–1.49 1.1–3.1 0–1.35 0.24–1.99 0.05–0.33

a Values derived from the following references: Reddy et al. (1984); Souci et al. (1989); Vidal-Valverde et al. (1993a, b); Frías et al. (1994, 1995, 1996); Jood et al. (1998); Sotomayor et al. (1999); Fasina et al. (2001); Cai et al. (2002); Porres et al. (2002); El-Adawy et al. (2003); Wang and Daun (2004, 2006); Martín-Cabrejas et al. (2006); Amir et al. (2007); USDA/ARS (2007).

to the raffinose series of oligosaccharides, nor is it believed to contribute significantly to flatulence (Quemener and Brillouet, 1983). Additionally, lentil contains α-galactosides (galactose polymers joined by α(1→6) linkages) in amounts ranging from 1.8 to 6.8% dry matter, which can also lead to flatulence (Frías et al., 2003). Polysaccharides Starch is the predominant carbohydrate in lentil seeds, ranging from 34.7 to 65.0% of dry matter. It serves as the principal energy source from this food. Starch is composed of two types of polymer: amylose and amylopectin. Both types are built from glucose subunits, although the linkages vary. Amylose is an essentially linear polymer of glucose, built up from repeated α(1→4) linkages. Amylopectin has the same linkages, but also contains α(1→6) linkages every 24–30 glucose units; this gives amylopectin a highly branched structure. These two polymers occur together in starch granules, and the relative proportions of amylose and amylopectin give each starch granule its unique structure and crystallinity, as well as confer specific physical properties to the combined starch (e.g. swelling factor, gelatinization temperature) (Hoover and Ratnayake, 2002). Lentil starch can contain from 20 to 45.5% amylose (Urbano et al., 2007), which is similar to that found in chickpea (Wood and Grusak, 2007). Digestion of starch, via pancreatic α-amylase and the intestinal enzymes sucrase-isomaltase and maltase-glucoamylase (Nichols et al., 2003), yields glucose units that can be absorbed in the small intestine and utilized for energy. However, not all of the starch is digested, presumably because of

STARCH

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inhibitory components within the grain. This leads to the so-called ‘resistant starch’ fraction (Sajilata et al., 2006), which escapes the small intestine and passes to the large bowel (also leading to flatulence). De Almeida Costa et al. (2006) reported a resistant starch value of 3.7 g/100 g dry matter in lentil cultivar ‘Silvina’. Resistant starch and all other undigested carbohydrates, including non-starch polysaccharides and oligosaccharides, are classified as dietary fibre. Non-starch polysaccharides are components that are not starch, but which are polymerized carbohydrates. These include cell wall components such as cellulose, hemicelluloses, pectic substances and b-glucans (mixedlinkage (1→3), (1→4)-b-D-glucan). In total, these can range from 5.1–26.6% dry matter (Table 23.1). Specifically, cellulose comprises 4.1–5.7% and hemicelluloses 6–15.7% of dry matter (Reddy et al., 1984; Amir et al., 2007; Urbano et al., 2007), and b-glucans in lentil germplasm have been reported at 0.4–1.1% dry matter (Demirbas, 2005).

DIETARY FIBRE

Lipid and fatty acids Lentil has a low concentration of lipids (fats), ranging from 0.3–3.5 g/100 g dry matter (Table 23.1), which places it similar to other cool-season legumes (chickpea, pea (Pisum sativum L.)) and most cereals (rice, wheat) (USDA/ ARS, 2007). Although lipids are energy-dense compounds, the low concentration in lentil means that little of the energy content of lentil seeds comes from fat. Compositionally, lentil contains both of the human essential fatty acids: linoleic and linolenic acids (Table 23.5). Linoleic is by far the predominant fatty acid, comprising from 41 to 57% of oil in several cultivars, whereas linolenic acid ranges from 0.3 to 16% of oil. The monounsaturated oleic acid (C18:1) and the saturated palmitic acid (C16:0) account for most of the remainder of the fatty acid profile. Myristic, palmitoleic, stearic, arachidic, gadoleic, eicosadienoic, behenic, erucic and lignoceric acids have also been reported in lentil seeds, with most occurring at <1% of oil (Table 23.5).

Minerals Lentil seeds contain several mineral elements that are required by humans (i.e. essential), although not all are necessarily required by lentil itself. Plants are known to take up many mineral ions that they encounter in the soil environment (via root absorption), even if these elements are not needed for plant growth and development; many of these elements are subsequently partitioned to seeds (Grusak and DellaPenna, 1999; Grusak, 2002). In total, these elements constitute the ash fraction that is frequently reported in proximate analyses. The reported ash range for lentil seed is 2.2–6.4 g/100 g dry matter (Table 23.1).

Fatty acid composition of lentil (% fatty acid in oil) (Source: see table footnotes).

Fatty acid Myristic (C14:0) Palmitic (C16:0) Palmitoleic (C16:1) Stearic (C18:0) Oleic (C18:1) Linoleic (C18:2) Linolenic (C18:3) Arachidic (C20:0) Gadoleic (C20:1) Eicosadienoic (C20:2) Behenic (C22:0) Erucic (C22:1) Lignoceric (C24:0)

var. LB Meta NAc 18.3 0.3 2.5 22.1 55.7 0.3 0.6 NA NA NA NA NA

var. 81sa NA 24.5 0.6 2.0 21.6 47.8 1.9 1.2 NA NA NA NA NA

Canadian greenb

Canadian redb

Australianb

0.00–0.93 10.79–15.36 0.00–0.61 1.27–1.82 17.04–25.63 40.97–46.14 11.93–16.23 0.77–1.11 1.21–1.58 0.00–0.22 0.81–1.13 0.36–0.74 0.47–1.99

0.42–0.73 13.25–15.77 0.00–0.33 1.34–1.65 17.05–22.17 42.91–45.23 11.68–14.66 0.80–0.92 1.12–1.24 0.00–1.86 0.81–0.91 0.80–0.92 0.56–0.70

0.60–0.60 12.70–13.70 NA 1.80–2.10 22.70–28.00 41.90–57.14 11.60–12.70 NA 1.20–1.30 NA NA NA NA

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Table 23.5.

a Data

from Amir et al. (2007). from Wang and Daun (2004). c NA = not available. b Data

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With respect to human mineral needs, reported values are available for lentil seeds for 12 of the 17 human essential elements (Table 23.6). Data are not available for chloride, fluoride or iodine. Two other human essential elements not listed here are nitrogen and sulfur, because these are viewed as being acquired in the form of amino acids (Table 23.3). Additional elements, such as boron, nickel and cobalt, are reported here, due to availability of data in the literature; these elements are not deemed essential in humans, but have been suggested to provide various health benefits (Nielsen, 1996). In general, it is seen that mineral concentrations are quite variable, presumably because of both genotype and environmental influences. On a weight basis, potassium and phosphorus constitute the bulk of the mineral profile, although even these minerals can be relatively low in some cases (Table 23.6). The mineral profile for lentil can also be viewed in terms of its percentage contribution to human dietary needs. Table 23.7 provides values for the current maximum adult US Recommended Dietary Allowance (RDA) or Adequate Intake (AI) for several essential elements, and the amount of these elements in a single serving of cooked, whole lentil (200 g fresh weight; equivalent to one cup in the USA). Lentil is clearly a very good source of copper and phosphorus, providing about half of the RDA for these elements. A single serving can also provide roughly one-quarter to one-third of the RDA or AI for iron, zinc and manganese. Lentil is a poor source of

Table 23.6. Mineral concentrations of whole, dry lentil seeds (mg/100 g dry matter)a (Source: see table footnotes). Mineral

Concentration (mg/100 g dry matter) (Ca)b

Calcium Magnesium (Mg)b Phosphorus (P)b Potassium (K)b Iron (Fe)b Zinc (Zn)b Manganese (Mn)b Copper (Cu)b Sodium (Na)b Boron (B) Chromium (Cr)b Nickel (Ni) Cobalt (Co) Selenium (Se)b Molybdenum (Mo)b a Range

42–165 13–167 240–1287 38–1360 3.1–13.3 2.3–10.2 0.6–1.0 0.4–9.9 0.4–79 0.6–1.0 0.03 0.12–0.35 0.04 0.009–0.012 0.08–0.22

of values derived from the following references: Kylen and McCready (1975); Souci et al. (1989); Sika et al. (1995); Sharma et al. (1996); Solanki et al. (1999a); Ereifej and Haddad (2000); Koplík et al. (2002); El-Adawy et al. (2003); Wang and Daun (2004, 2006); Iqbal et al. (2006); USDA/ARS (2007). b Elements conﬁrmed as essential for humans (Grusak and DellaPenna, 1999).

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Table 23.7. Contribution of a 200 g serving of cooked lentils to the US RDA or Adequate Intake (AI) of various minerals for adults (Source: see table footnotes). Maximum adult US RDA or AI (mg)a Potassium Calcium Phosphorus Magnesium Iron Zinc Manganese Copper Selenium

4700 1200 700 420 18 11 2.3 0.9 0.055

Amount (mg) in 200 g of cooked lentilb 738 38 360 72 6.6 2.6 0.98 0.50 0.006

Contribution to adult RDA or AI (%) 16 3 51 17 37 24 43 56 11

a RDAs are the daily levels of intake of essential nutrients judged to be adequate to meet the known nutrient needs of practically all healthy persons. Values presented are the highest RDA either for male or female adults, excluding pregnant or lactating women. The values for potassium, calcium and manganese are the AI value, which is that amount believed to cover the needs of all individuals in a group, but lack of data prevent being able to specify with conﬁdence the percentage of individuals covered by this intake. All values are from Institute of Medicine (2006). b Values are from USDA/ARS (2007) for mature, cooked, boiled without salt lentil seeds (Nutrient Database No. 16070), which contain 70% water. Note that these are only a subset of the minerals that can be found in lentil seeds (see Table 23.6).

calcium, providing only 3% of the AI, and it is questionable how much of this is even available, because most of this calcium would probably be present as insoluble calcium oxalate crystals (Zindler-Frank, 1987; Franceschi and Nakata, 2005).

Vitamins Lentils contain many of the water-soluble and fat-soluble vitamins required by humans (Table 23.8), although they are devoid of vitamins B12 and D, which are not synthesized by plants. As with other seed components, the vitamin concentrations vary across cultivars, with ranges generally much larger for the water-soluble than fat-soluble vitamins. In fact, vitamin C and biotin were totally undetected in some sample surveys (Table 23.8). When the vitamin compositional quality of lentil is assessed in a single, cooked serving, relative to maximum US RDA or AI values for adults (not including pregnant or lactating women), it is clear that lentil is an excellent source of folate. In various regions of the world, processed foods are fortified with folate in order to ensure adequate intakes, especially for women of childbearing age (Buttriss, 2005). Folate deficiency can lead to neural tube defects in infants and may be linked to a higher incidence of certain types of cancer and heart disease (Selhub and Rosenburg, 1996). Other vitamins for which lentil provides good levels are pantothenic acid, pyridoxine and thiamin,

Vitamin Water-soluble: Vitamin C Niacin (vitamin B3) Pantothenic acid Pyridoxine (vitamin B6) Riboﬂavin (vitamin B2) Thiamin (vitamin B1) Folate Biotin Vitamin B12 Fat-soluble: Vitamin E (α-tocopherol) Vitamin E (γ-tocopherol) Choline Vitamin A Vitamin K Vitamin D

Units

Reported range (per 100 g dry matter)a

Maximum adult RDA or AIb

mg mg NEd mg mg mg mg μg μg μg

0.0–7.7 0.6–3.6 0.4–2.4 0.16–0.60 0.11–0.46 0.13–0.90 40–535 0–132 Not found in plants

90 16 5 1.7 1.3 1.2 400 30 2.4

mg α-TEf mg α-TE mg μg REh μg μg

0.36–1.60 0.31–0.64g 109 2.2–3.4 5.6 Not found in plants

15 550 900 120 15

Amount in 200 g cooked lentil seedc

378

Table 23.8. Vitamin composition of whole, dry lentil seeds, of cooked lentil seeds, and percentage contribution of a 200 g serving of cooked lentils to the US RDA or AI of several vitamins for adults (Source: see table footnotes). Contribution to adult RDA or AI (%)

3.0 2.12 1.28 0.36 0.15 0.34 362 106e 0

3 13 26 21 11 28 91 353 0

0.22 65.4 16 3.40 0

1 12 2 3 0

a

M.A. Grusak

Range of values derived from the following references: Kylen and McCready (1975); Savage (1988); Souci et al. (1989); Wang and Daun (2004, 2006); Ryan et al. (2007); USDA/ARS (2007). b See Table 23.7 for explanation of RDA and AI. All values in this column are from Institute of Medicine (2006). All values reﬂect the RDA, except for vitamins D, K, pantothenic acid, biotin and choline for which the AI is listed. c Values are from USDA/ARS (2007) for mature, cooked, boiled without salt lentil seeds (Nutrient Database No. 16070), which contain 70% water. d NE, niacin equivalent; 1 mg NE is equal to 1 mg of niacin or 60 mg of dietary tryptophan. e Value calculated from biotin concentration reported in Savage (1988). f α-TE, α-tocopherol equivalent; 1 mg a-TE is equal to 1 mg (R,R,R)-a-tocopherol. g Range calculated using a 10% conversion factor for g-tocopherol (i.e. 10 mg g-tocopherol = 1 mg α-TE). h RE, retinol equivalents. Preformed vitamin A is not found in plant foods. However, plants contain a number of provitamin A carotenoids (e.g. b-carotene) which can be metabolized to vitamin A. Vitamin A activity is expressed in RE; 1 μg RE is equal to 1 μg all-trans retinol, 6 μg all-trans β-carotene, or 12 μg of other provitamin A carotenoids.

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supplying 21–28% of the RDA or AI in a single 200 g serving. Lentil is not a particularly good source of fat-soluble vitamins, potentially providing only 12% of the AI for choline, and less than 3% of the RDA or AI for vitamins A, E or K. The low concentration of fat-soluble vitamins is probably a reflection, in part, of the low oil content of lentil (Table 23.1).

23.3. Non-nutrient Components Plant foods contain a myriad of secondary metabolites, peptides, enzymes and other components that have gained attention for their potential to reduce the incidence of disease and to promote good health in humans. These components are non-nutritive in nature, although some of them can be metabolized to release energy, or to generate nutritional compounds. They can serve as antioxidants, as prebiotics, as regulators of gene expression and modifiers of cell division, to name a few (Lila and Raskin, 2005; Weaver et al., 2008). Although much has still to be determined regarding the bioavailability of various phytochemicals, and thus the effective dose that one can gain from a given food (Holst and Williamson, 2008), researchers have none the less been quantifying the non-nutritive components of different seeds, fruit and vegetables, including lentil. In addition to the health-beneficial components, plants also contain anti-nutritional factors that can reduce the availability and/or utilization of various dietary nutrients. Several compounds have been identified in lentil that can interfere with the utilization of minerals, protein or carbohydrates. These are discussed below.

Fibre Several non-nutritive carbohydrates were mentioned in an earlier section, including raffinose-family oligosaccharides, α-galactosides, β-glucans and other polysaccharides, which along with resistant starch constitute the fibre fraction of lentil. Dietary fibre is important for general functioning of the gastrointestinal tract, as it assists faecal motility and helps maintain proper faecal water balance (Gallaher and Schneeman, 1996). Much of the fibre (especially the oligosaccharides) can be fermented in the large bowel, thereby providing energy and metabolites to the gut microflora. The population of ‘good’ microbes in the gut, referred to as probiotic bacteria, are proving important for their role in the suppression of unwanted pathogenic bacteria (Baumgart and Carding, 2007), stimulation of the immune system (Holzapfel and Schillinger, 2002) and the enhancement of calcium absorption and bone mineralization (Abrams et al., 2005). Thus, a diet containing lentils can serve as a prebiotic source that provides needed dietary fibre for the maintenance of a balanced gut ecosystem (Guillon and Champ, 2002; Blaut and Clavel, 2007).

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While fibre has many benefits, it also has some anti-nutritional aspects. Fibre has a high cation exchange capacity and thus can bind several minerals including calcium, iron and zinc. This can lead to reductions in the solubility and bioavailability of these minerals, from the fibre-containing food, or from other sources in the diet (Kelsay et al., 1988; Weber et al., 1993). It is interesting that fibre has both a positive (prebiotic) and a negative (binding capacity) effect on mineral absorption.

Phenolics Phenolics are a huge class of secondary compounds that play diverse roles in the physiology of the plant (e.g. growth, reproduction, pigmentation, pathogen resistance), but which also are proving important as dietary constituents due to their antioxidant properties and potential promotion of good health. Phenolics range from simple molecules, such as phenolic acids, to highly branched and polymerized compounds, such as tannins (Bravo, 1998). In legume seeds, the principal phenolics are phenolic acids, flavonoids and lignans. In lentil, most of the phenolics are localized to the seedcoat, which has a broader diversity of phenolic compounds as well as higher concentrations overall (Table 23.9). In general, although the cotyledons make up most of the seed mass, they provide very little in the way of total dietary phenolics. The health-beneficial significance of these compounds is derived from their antioxidant properties, which allows them to scavenge free radicals (Seifried et al., 2003). This activity presumably explains their role in the reduction of chronic diseases (Williamson and Manach, 2005). For instance, catechins and procyanidins (oligomeric catechins) have been shown in human Table 23.9. Phenolic composition of lentil seedcoat and cotyledons (mg/100 g dry matter) (Source: see table footnotea).

Total catechins Hydroxybenzoic acid Free hydroxycinnamic acid Combined hydroxycinnamic acid Dimer procyanidins Trimer procyanidins Tetramer procyanidins Galloylated procyanidins Prodelphinidins (dimers plus trimers) Flavone glycosides Flavonols trans-Resveratrol glycoside a Range b ND,

Seedcoat

Cotyledons

91.9–163.3 2.8–4.5 1.2–3.0 ND 61.9–112.2 44.1–49.8 1.9–6.0 6.9–12.3 36.9–72.5 3.3–18.6 1.0–24.1 0.6–0.9

0.02–0.03 0.18–0.22 0.3–0.6 0.1–1.4 NDb ND ND ND ND ND ND ND

of values derived from: Dueñas et al. (2002, 2003) and Dueñas (2003). not detected.

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intervention studies to increase plasma antioxidant activity (Nakagawa et al., 1999). In an in vitro comparison of antioxidant capacity of several food legumes (lentil, pea, chickpea, common bean (Phaseolus vulgaris L.) and soybean), lentil cultivars possessed the highest antioxidant activities (Xu et al., 2007). On the other hand, several phenolic compounds (especially the catechins) have the ability to chelate metals (Khokhar and Owusu Apenten, 2003; Andjelkovic´ et al., 2006). Foods high in phenolics have been shown to inhibit iron absorption in human subjects (Tuntawiroon et al., 1991), and may inhibit the absorption of other micronutrient metals (Le Nest et al., 2004; Viadel et al., 2006). Another group of polyphenolics is the condensed tannins, also known as proanthocyanidins, which are polymers of two to 50 (sometimes more) flavonoid units. Tannins have been identified in lentil, usually associated with the seedcoat fraction, and are found at concentrations of 0.02–1.01 g/100 g dry matter (Solanki et al., 1999a; Wang and Daun, 2006). As with the phenolic acids, tannins have the ability to chelate iron and other metals, thus they can reduce the bioavailability of metals in plant foods (Viadel et al., 2006). Tannins also interact with protein, starch and other carbohydrates, forming insoluble complexes that reduce the digestibility of these nutrients (Carbonaro et al., 1996; Muzquiz and Wood, 2007).

Phyto-oestrogens Plants contain several oestrogen-like compounds (referred to as phytooestrogens) that can induce oestrus in immature animals or interfere with normal reproductive processes (Kurzer and Xu, 1997). Phyto-oestrogens include the isoflavonoids: genistein, daidzein, biochanin A and formomonetin; the coumestan: coumestrol; and the lignans: secoisolariciresinol and matairesinol (Mazur et al., 1998). Although many plant groups contain phytooestrogens, members of the legume family exhibit the highest levels of phyto-oestrogens. For example, soybeans are rich in the isoflavonoids genistein and daidzein (Kurzer and Xu, 1997), and populations that consume high levels of soy products appear to have lower incidences of disease, including reductions in certain types of cancers and type 2 diabetes (Dixon and Ferreira, 2002; Villegas et al., 2008). In lentil, phyto-oestrogenic compounds have been identified, but their concentrations are quite low, relative to several common crop legumes. Daidzein (3.3–10.4 μg/100 g dry matter) and genistein (7.1–18.8 μg/100 g dry matter) are basically present in trace amounts, relative to soybean (values range from 10,500 to 56,000 μg/100 g dry matter for daidzein and 26,800–84,100 μg/100 g dry matter for genistein) (Mazur et al., 1998). Lentil also contains only minute amounts of the lignans, anhydrosecoisolariciresinol and secoisolariciresinol (combined range of 8.9– 12.3 μg/100 g dry matter) and trace to non-detectable amounts of matairesinol (Mazur et al., 1998). However, only a few lentil cultivars have been characterized and it would be interesting to quantify these compounds in additional germplasm, or in seeds of lentil plants subjected to various stress

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conditions during seed development (which may stimulate isoflavone synthesis).

Phytate Plants synthesize various myo-inositol phosphates, denoted IP1 through to IP6, which contain from one to six phosphate groups. A significant antinutrient from this group is myo-inositol(1,2,3,4,5,6)hexakisphosphate, (IP6, phytic acid, or phytate), which can complex with calcium, iron and zinc ions in the food matrix (Raboy, 2001). This complexation reduces the solubility of these minerals and inhibits their absorption in humans (BrinchPedersen et al., 2007; Hotz and Gibson, 2007). However, it should be noted that the metal scavenging ability of phytate (and some of the other inositol phosphates) may also reduce the free radical activity of bound transition metals, thereby simultaneously conferring health benefits and disease prevention attributes to phytate (Zhou and Erdman, 1995). Lentil seeds contain from 0.4–1.6 g phytate/100 g dry matter (Sharma et al., 1996; Wang and Daun, 2006). The inositol phosphates IP3, IP4 and IP5 have also been identified in lentil seeds, although at less than 10% the amount of IP6 (Kozlowska et al., 1996; IP1 and IP2 could not be resolved in this study).

Saponins Saponins are bioactive compounds that are composed of a steroidal or triterpene aglycone linked to one, two or three saccharide chains of variable size and complexity (Fenwick and Oakenfull, 1983). Saponins have traditionally been classified as anti-nutritional factors, due to their ability to form stable, soap-like foams that can interact with components of the digesta (Muzquiz and Wood, 2007); however, specific saponins are also being recognized for health benefits, such as hypocholesteraemic and anticancer properties, or stimulation of the immune system (Champ, 2002; Mathers, 2002). The saponin content of lentil seeds includes both soyasaponins I and VI, with concentrations ranging from 0.065 to 0.126 g/100 g dry matter (Ruiz et al., 1997).

Enzyme inhibitors Legume seeds contain two main classes of enzyme inhibitors: those that inhibit proteases (trypsin and chymotrypsin) and those that inhibit α-amylases (Muzquiz and Wood, 2007). The former disrupt protein digestion, thereby influencing the utilization of protein and amino acids from the seeds. The α-amylase inhibitors interfere with starch breakdown, and thus limit the available energy found within seeds. Lentil demonstrates trypsin inhibitor activities (TIA) of 21–55 TIA/mg protein, which places it in line with the activities found in pea, broad bean (Vicia faba L.) and mung bean (Phaseolus

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aureus L.), but much lower than that measured in chickpea, common bean or soybean (Guillamón et al., 2008).

Toxins Legume seeds contain lectins or haemagglutinins, which are glycoproteins that possess at least one non-catalytic domain and can bind to specific monosaccharides, oligosaccharides or other glycoproteins (Peumans and Van Damme, 1995). When bound to these components on the surface of cells lining the intestine, they can interfere with digestive processes and absorption. Lentil seeds do contain lectins, but their concentration is low and they provide only minimal reactivity in the erythrocyte agglutination test; thus, lentils have been deemed to have low lectin toxicity when compared to other highly reactive legumes such as common bean, Phaseolus coccineus L. or Phaseolus acutifolius L. (Grant et al., 1983). Allergens are another form of toxin in plant seeds, with some individuals reacting quite severely to specific proteins or peptide fragments after the ingestion of a food (Cordle, 2004). Lentil is frequently associated with IgEmediated hypersensitivity reactions, particularly in pediatric populations in Mediterranean countries where lentil is a common food (Kalogeromitros et al., 1996). A major allergen from the vicilin protein family, designated Len c 1.01, has been identified in lentil (López-Torrejón et al., 2003).

23.4. Processing Types and Effects on Nutritional Quality When lentils are prepared for human consumption, they are usually processed in some manner to enhance their palatability and to improve their overall nutritional value. Different processing methods can be employed, including decortication (seedcoat removal), soaking, germination, fermentation, sprouting, cooking, microwaving, enzyme treatment or irradiation (see Urbano et al. (2007) for a detailed discussion of these processes). In general, these treatments lead to a significant reduction or total elimination of anti-nutritional components, although losses of certain nutrients can also occur. For instance, decortication reduces the levels of phenolics and tannins (Dueñas et al., 2002), which might otherwise interfere with mineral or protein utilization; cooking inactivates enzyme inhibitors (Urbano et al., 1995), but may also cause thermal degradation of vitamins (FernandezOrozco et al., 2003). Soaking, germination, sprouting or fermentation processes lead to metabolic changes of the lentil seed components, which can result in enhanced availability of some compounds (e.g. protein, starch, some minerals and vitamins) (Urbano et al., 1995; Kuo et al., 2004; Ghavidel and Prakash, 2007), as well as reductions in the concentration of others (e.g. phytate, lectins, some phenolics) (Kozlowska et al., 1996; LópezAmorós et al., 2006).

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23.5. Acknowledgements This work was funded in part by funds from USDA/ARS under Agreement No. 58-6250-6-001 and from the Harvest Plus Project under Agreement No. 58-6250-4-F029. The contents of this publication do not necessarily reflect the views or policies of the US Department of Agriculture, nor does mention of trade names, commercial products or organizations imply endorsement by the US Government.

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24

Postharvest Processing and Value Addition Albert Vandenberg University of Saskatchewan, Saskatoon, Canada

24.1. Introduction Lentils are usually consumed as a natural food product in the form of whole seeds or decorticated seeds. In most countries they are used in traditional food preparations such as soups and stews which are served with other staple foods based on rice, wheat or other major cereal grains. As is the case with most pulse crops, consumer preferences for lentils are very specific in terms of seed size and shape, seedcoat appearance and colour, cotyledon colour and uniformity of appearance. Processing consists of a series of mechanical separations and milling operations that prepare lentils for direct consumption. The lentil processing industry has two major components. Primary processing consists of cleaning and delivery of whole seeds to consumers. The basic principle of primary processing is to use gravity to separate lentil seeds into desired quality classes defined by diameter, thickness, density and colour. Various screens and air-flow mechanisms are used to remove unwanted organic and inorganic materials and to sort the retained lentils. In regions where lentils have been grown as a traditional crop, simple seed separation systems based on sieves are used for small-scale primary processing. In regions where lentils are accumulated, stored and then processed for delivery to urban consumers, the primary processing may be done on a feefor-service basis, or may be done in-house by a lentil marketing company. The secondary processing component mostly involves decortication, splitting, sorting and polishing of the lentils. In some countries, secondary processing of whole lentils involves thermal processing into cans or jars. The tertiary level of processing, which involves using whole or decorticated lentils in further milling, grinding or fractionation for use in processed food products, is the least developed segment of the processing industry. © CAB International 2009. The Lentil: Botany, Production and Uses (eds W. Erskine et al.)

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Value addition through processing is essentially the economic concept of preparing lentils and lentil-based products in such a way as to convince consumers to pay more for the improved convenience or the perceived nutritional or culinary benefits. The simplest form of value addition is the cleaning of whole lentil seeds to acceptable culinary standards. Removal of the seedcoat reduces cooking time and is therefore the primary form of value addition for lentils. Value addition through processing also may be based on improving the value of the by-products of processing, for example, the seedcoats and small particles and broken bits of lentils that are cleaned out from the cleaning, decortication and splitting processes.

24.2. Primary Processing The principles of primary processing used for cleaning lentils are essentially the same as for cereal grains. Specific modifications used for processing lentils include changes to elevators, conveyors and storage systems to reduce damage to the seeds and the seedcoats and to maintain high visual quality. The components used in primary processing systems are very specific in terms of what type of equipment is economical and necessary in a given lentil production region For example, specific requirements for weed seed removal may determine what type of separation equipment is essential. Figure 24.1 presents a generalized scheme of the steps in primary processing beginning with storage and ending with bagging of cleaned lentils. The actual configuration in a processing facility is highly variable and flexible depending on the economics of meeting consumer demand according to a generally agreed level of quality based on providing lentils with specific diameter, thickness, colour, damage and admixture specifications that are agreed to by buyers and sellers.

Storage considerations After harvest, lentils are either stored in bins or other containers on farms or sold and delivered to a primary processing facility for storage and eventual cleaning. In regions where on-farm grain storage is not common, lentil growers deliver lentils to marketers immediately after harvest. In this case, the purchaser may have storage facilities where lentils are kept in bulk, in bags or in steel bins. Where on-farm grain storage is common, for example in Canada, lentils are normally stored on-farm in steel bins and delivered to primary processing facilities when required by sales contracts. The initial condition of the grain and the storage environment may have an impact on processing quality. In some cases, the lentils undergo rough cleaning before storage using stationary screens built into the conveying systems on combine harvesters or grain conveyer systems to remove large and small particles from the grain. Storage conditions prior to processing can affect the quality of the lentils and cause processors to accommodate the flow of product through the

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Comments

Stored lentils

Specific conditions are location specific, may differ depending on end use

Pre-cleaning

Removal of coarse and fine materials based on stationary screens

Air screening

Removal of material based on particle density, shape and size using gravity and air flow

Indent cleaning

Physical separation of lentils based on diameter

Gravity separation

Further separation of lentils based on density

Destoning

Additional separation of stones based on density

Sizing

Colour sorting

Packaging

Optional separation into diameter or thickness based on customer requirements Optional separation of lentils based on colour

Final product delivery into bags, totes, containers, bulk containers or rail cars for delivery

Fig. 24.1. General outline of the steps involved in primary processing of lentils.

cleaning process. For example, seedcoats of green lentils darken during storage, slowly changing from green to an oxidized brown colour. The rate of colour change is increased with increases in temperature, light or humidity. Cenkowski et al. (1989) and later Tang et al. (1994) studied the equilibrium moisture profiles of green lentils during storage and their effects on quality. The rate of darkening of green lentil seedcoats increased over time based on biochemical changes in the seedcoat. Desiccation of green lentils with diquat may also cause seedcoat colour to darken more rapidly in the field during the final stages of seed maturation, and possibly during storage (Davey, 2007). Similar research on storage conditions of red lentils with brown or grey seedcoats is currently underway in Canada (K. Agblor, 2008, Saskatoon, personal communication) to determine storage effects on subsequent dehulling and recovery percentage. In production regions where lentil is grown as a subtropical dry cool season (South Asia, for example) or as a winter crop in Mediterranean climatic zones (south-eastern Anatolia, Australia) the moisture content of the harvested lentils is generally below 12% and is often much lower because

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the crop is harvested during seasons with increasing temperature and decreasing humidity. Problems with seed damage during handling may occur if the lentils are too dry. Combine harvesting, augering and elevation of very dry lentils into storage may cause problems with seed breakage and with chipping of the seedcoat at the edge of the seed. This is more likely to be a problem with large-diameter lentils (usually large green types), particularly for varieties that produce seeds with a thin instead of a thick edge. In general, for lentil types that are sold as whole seeds to the consumers, storage moisture conditions must be managed so that the seedcoat remains intact. In temperate regions with summer production, like the prairie regions of North America, harvest progresses into cooler and more humid conditions. In some seasons it is necessary to reduce the moisture content of the lentils immediately after harvest using aeration fans in the bins for lentils that have been harvested at moisture content above 15%. The safe storage moisture level for lentils is considered to be below 15%, but storage moisture below 12% may lead to problems with handling damage. One particular problem in the North American prairies is damage caused by handling dry lentils at extremely cold temperatures during winter months. Some environmental condition experienced during the growing season may lead to development of brittle or wrinkled seedcoats in lentils, which in turn contributes to damage during storage and postharvest handling. Alternating wet and dry periods during late stages of maturity can cause wrinkling, colour loss and brittle seedcoats. Chemical desiccation of the crop prior to harvest may also be a factor in causing brittle seedcoats that chip and split more easily. For lentils that are destined for markets that prefer whole lentils with intact seedcoats, primary processing facilities are designed to minimize damage by using bristle-flighted augers and belts in the place of standard conveying equipment used for cereal grains. In most parts of the world, red lentils are produced for dehulling. Recent research from Canada indicated that the critical moisture content for maximizing the recovery of decorticated red lentils during milling is 12.5% (Wang, 2005). In some countries, delivery contracts specifically state the maximum allowable moisture content for delivered lentils. In Canada, recommended storage moisture for green lentil is 14% to help minimize seedcoat breakage, while the recommended storage moisture for red lentil is 13% to help maximize dehulling recovery.

Air screening The primary method of cleaning lentils is the air-screen separator. It uses a combination of air, gravity and screens to separate seed based on size, shape and density. Commercial machines can be equipped with two to eight vibrating screens. The lentils are fed into a hopper where they are evenly distributed by a feed roller and transferred through a controlled gate on the top sieve. The lentils are subjected to primary aspiration by the use of an air trunk which drains off chaff, straw, dust or deceased grains. Then the lentils

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are passed through the sieve layer for separation according to their width and thickness. After the separation, the graded material is subjected to an air sifter and aspiration chamber where remaining light particles are sucked off by a strong upward draught of air. The graded material and the impurities are automatically discharged in separate chutes.

Indent cleaning Indent cleaning machines are generally used for separating lentils by diameter into different sizes. After air screening, the lentils are fed into the indent cleaner through a conveyor into the centre of a rotating cylinder. The lentils of smaller diameter are lodged in the indents and are lifted by the cylinder until they fall out under gravitational force into the internal trough. The large particles remain in the trough for further separation. Due to the rotating speed and inclination of cylinder, the large lentils are separated and are discharged out while the small lentils and other crop seeds are removed separately with the help of an auger or a vibrating device fitted with a trough.

Gravity separation This type of grain cleaner is used for separating lentils that have the same size but differ in specific weight. A gravity separator can be used effectively to remove partially eaten (for example by storage insects), immature or broken seeds to ensure maximum quality of the final product. Gravity separators have a rectangular deck so that the product travels a longer distance, which results in effective separation of light and heavy particles. The product flows over the rectangular vibrating deck as pressurized air is forced through from underneath, causing the material to stratify according to its specific weight. The heavier particles travel to the higher level and the lighter particles travel to the lower level of the deck. In order to obtain efficient separation by specific weight, the pressurized air supply needs to be accurately adjusted to control the volume of air distribution at different areas of the vibrating deck. The table inclination, the speed of eccentric motion of vibration and the feed rate can be easily and precisely adjusted to maximize separation efficiency.

Destoning Destoning machines are used to separate heavier materials like stones, glass and metal from lentils. The operating principle is the stratification of the product into heavier and lighter fractions by introducing air through the bed of material. Pressure fans are located in the body of the machine, below the vibrating deck. The vibrating deck pushes the heavier material which is in contact with the deck upwards towards the stone discharge spout.

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The lighter material flows with air assistance down the inclined, vibrating deck and exits through the clean product spout. It is possible to individually adjust the inclination of the vibrating deck, speed of eccentric motion, feed rate and the air flow in order to achieve the optimum degree of separation.

Sizing Cleaned lentils may be sized after cleaning based on consumer demand for uniformity of specific diameter or thickness of seeds. Sizing adds cost to the final product and demand for sizing can be very specific. For example, premiums may exist for extra-large green lentils in Spain. In some parts of South Asia, for example in Bangladesh, premiums are paid for extra-small red lentils that are dehulled but not split. In most cases, the separations used prior to the destoning step will provide sufficient sizing to meet the general consumer demand.

Colour sorting Various types of electronic colour-sorting machines are available. They are used opportunistically to add value to lower grade lentils, or to ensure maximum quality for premium products. All colour-sorting machines used in the lentil industry were adapted from other industries, for example from the rice or coffee industries. The basic principle is to use computerized digital imaging to compare the colour of lentils passing by sensors that are adjusted to an acceptable predetermined colour range. Lentils with colours that lie outside the selected colour range are rejected by removing them from the product stream using air jets that change the trajectory of rejected lentils. Some sorting machines convey the lentils on horizontal belts with downward-facing air jets. Most colour sorters are designed to have downward flow of lentils combined with horizontal air jets. Colour sorters are used to add value to lentils by improving uniformity of colour for specific market classes, but only when it is economically feasible to do so. Typical situations where colour sorting of whole lentils may be used are situations where lentils that are discoloured as a result of weathering of seedcoats during wet harvests or discoloration due to frosts (both can occur in Canadian lentil production). Other situations where optional colour sorting may be economical could be removal of seeds that are stained by fungal disease like Ascochyta blight or admixtures of lentils with contrasting seedcoat colour. The decision as to whether or not colour sorting is economically feasible is determined by the differential in price between the sorted (value-added) lentils and the unsorted material, the operation and investment cost of the colour-sorting system, and the proportion of lentils required to be removed from the unsorted product. A requirement to remove too many or too few lentils reduces the economic efficiency of the sorting process and the potential added value.

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Packaging After whole lentils pass through the various types of cleaning and separation, they are packaged and shipped as demanded by local or export specifications. Various types of bagging, containerization and shipping methods can be used. Cleaned lentils may be shipped in bulk-hopper cars for delivery to bulk shipping vessels for export to bulk unloading facilities in port facilities for bagging. In Canada, some exporters may temporarily position a completely mobile grain-cleaning system beside the railway to fill hopper cars for bulk delivery to the port. For some customers, primary processors fill large polypropylene tote bags that are loaded into standard 20 or 40 t shipping containers. In some cases, polyethylene-lined shipping containers are filled with bulk-cleaned lentils. Bulk shipments are often received at facilities for re-cleaning and packaging in smaller consumer-ready packages under individual brand names. Typical consumer packages are polyethylene bags in 500 or 100 g portions. In regions with high lentil consumption, packages may be up to 15 kg, particularly for restaurant and institutional use. One of the most common forms of shipping-cleaned lentils is preprinted polypropylene bags or jute bags that are loaded into shipping containers or trucks, depending on the export origin and the destination. Bag size, bag quality and labelling information are predetermined by the purchaser. Typical size ranges from 25 to 100 kg. The bags may be loaded manually or mechanically into shipping containers, or bags may be piled and then shrink-wrapped on pallets, depending on customer preference. Based on changing consumer requirements and market trends, bagging systems are flexible. The packaging system for lentils is also highly influenced by packaging trends in the other crops such as rice. Screenings or dockage from the various cleaning processes are generally accumulated and then used to feed livestock. Each stream in the cleaning process may be kept separate, for example split lentils, damaged lentils and weed seeds may be stored together as they accumulate through the cleaning system. Products such as hulls, pods and chaff that are removed by air separation may accumulate separately. This material is generally sold to farmers with livestock or sold to feed-compounding companies. Screenings are passed through hammer mills, and then blended with other feed grain products and dietary supplements. Water is added and the mixture is then heated and pelleted for use as animal feed.

24.3. Secondary Processing The main form of secondary processing of lentils is decortication or dehulling, which is the removal of the seedcoat from the cotyledon. The dehulling process is usually followed by polishing or splitting or both before the lentils are consumed in soups or stews. The basic economic concepts that relate to milling of lentils are milling efficiency, dehulling efficiency and football recovery. The term milling efficiency in pulses may be defined in a variety

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of ways. Ehiwe and Reichert (1987) described dehulling efficiency in terms of the percentage of hull removal from the cotyledon and the yield of the dehulled grain obtained from this process. Wang (2005) defined milling efficiency as the sum of the percentage of whole dehulled seeds and split dehulled seeds recovered after decortication. Football recovery is defined as the proportion of dehulled unsplit seeds recovered after decortication. Football lentils are often sold at a premium to splits. Regardless of terminology, milling quality of the lentils influences economics because the by-products of milling (seedcoat, endosperm, broken pieces and flour) are of comparatively low value. A more precise definition of dehulling efficiency was provided recently (J. Bruce, 2008, unpublished results) as the percentage of the total split and unsplit cotyledons whose outer surface has more than 98% of the hull removed during the decortication process. Maximizing milling efficiency, dehulling efficiency and football recovery define the profitability of secondary processing of lentils. This form of secondary processing is known as dhal milling in South Asia, where it has been practised for millennia. An up-to-date review of the current status of dhal milling of the wide spectrum of pulses produced in India is provided by Ilyas and Goyal (2005). Removal of the seedcoat is an ancient process, originally practised at the household level with mortar and pestle or hand-driven rotating horizontal millstones. Removal of the seedcoat reduces cooking time for pulses, and generally increases the concentration of nutrients in the decorticated seeds because the seedcoat is mostly cellulosic material. Seedcoat thickness varies depending on the crop, from as low as 5% in some varieties of cowpea (Vigna unguiculata) to 30% in some lupine species (Kurien, 1984). The seedcoat of lentil tends to be thinner than that of most other legumes (Hughes and Swanson, 1986). It normally ranges between 6 and 7% of the seed weight (Singh et al., 1968; Erskine et al., 1991). Wang (2005) reported the seedcoat seed weight for Canadian red lentil as 7.3%. Largerseeded lentils tend to have lower percentage loss during decortication because the proportion of hull to seed mass is lower. Erskine et al. (1991) found that lentil seeds with a mean diameter of 4 mm lost about 8.2% of their weight during decortication, whereas losses from seeds sized 3 mm averaged 9.8%. The two countries with the greatest amount of lentil milling capacity are Turkey and India (Williams et al., 1993). Virtually all lentil milling is focused on red lentils, but there are some countries, for example the Aegean coast of Turkey, where dehulled yellow cotyledon lentils are consumed. Yellow cotyledon lentils are also milled to a very limited extent in Canada. Since India produces the largest volume of pulses and also of red lentils in the world, it also has the most dhal mills. Ilyas and Goyal (2005) stated that India has more than 7000 dhal mills, and that no standard process is followed because of the wide variety of pulse crops, varieties, environments and treatments. Turkey has a large red lentil milling industry for both domestic consumption and export. Most mills were originally located in the Gaziantep region of south-eastern Anatolia. More recently, larger mills were

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built or relocated primarily to the Mediterranean port city of Mersin. In the past 10 years, lentil milling capacity has expanded in both Sri Lanka and Egypt, two of the world’s largest importers of red lentils. Significant red lentil milling capacity also exists in Syria and the United Arab Emirates. With the expansion of red lentil production in Australia and Canada that started in the mid-1990s, milling capacity has also begun to expand. Rising costs for energy ultimately raised crop production and transportation costs. It is expected that milling capacity will continue to expand in exporting countries in order to reduce shipping costs. The decortication process for pulse seeds is influenced by the structure of the seedcoat and the extent to which it is bound to the cotyledon. Usually a gum (such as galactomannan) or lignin layer binds the cotyledons to the hull (Siegel and Fawcett, 1976). Muller (1967) demonstrated that among pulse species, variability in the depth and tackiness of this layer results in different binding ability between the hull and the cotyledons. He considered lentils to be in the category of pulses that are relatively easy to dehull compared to pigeon pea (Cajanus cajan), green gram (Vigna radiata) and black gram (Vigna mungo). The general process for abrasive dehulling of lentils is outlined in Fig. 24.2. The process begins with sized-cleaned lentils and proceeds through various necessary and optional steps. Similar to the scenarios of primary processing, the actual commercial setup of modern dehulling plants is highly variable depending on environment, production system, primary processing capability, economics, availability of red lentils, and the cost of purchase, maintenance and operation of machinery. No two dehulling plants will be set up the same way. Much of the equipment used in the process is borrowed from other industries that process other grain products, and in some cases the equipment is modified or manufactured exclusively for red lentil dehulling. The pitting, water addition, heating and cooling steps are designed to reduce the natural binding of the seedcoat to the cotyledon. The dehulling step produces both whole dehulled footballs, plus dehulled splits which can be separated by optional sieving or left mixed. If customers specify split lentil products, it is also possible to use a second set of horizontal millstones that can be adjusted to produce 100% split products from the dehulled lentils. Individual lots and varieties may dehull more or less easily, depending on environmental factors and interactions that affect final seedcoat and seedcoat development. One of the key factors in maintaining high milling efficiency is deciding how to handle specific lots of lentils to maximize return. Specific information on methods and techniques are usually held in strict commercial confidence. Through in-house design, modification and innovation, some steps in the general procedure outlined in Fig. 24.2 may be eliminated, modified to suit local conditions, or added as a means of reducing cost or improving quality of the final milled lentil products. Dehulling also has a seasonal influence. Many millers report that successful milling requires that the lentils be allowed to fully equilibrate and mature

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Comments

Cleaned and sized lentils Pitting

Abrasion allows moisture transfer

Re-cleaning

Removes fines (very small particles of broken grains) and brokens

Water mixing

Adjusts moisture content

Steeping

Equilibration

Heating

Separation of hull and cotyledon tissue

Cooling Dehulling Hulls Feed and waste

Removes seedcoat

Sieving

Fines Wholes

Separates splits and footballs Splits

Aspiration Colour sorting Polishing

Removes discoloured material Water or oil

Packaging

Fig. 24.2. General outline of steps in the manufacturing of whole and split dehulled lentils (Source: adapted from Matanhelia, 1980; cited in Ilyas and Goyal, 2005).

in storage for at least 6 weeks after harvest before milling can begin. The cold winter temperatures of Canada also pose specific problems for milling and handling of lentils. One of the key factors in successful dehulling is management of the moisture content differential between the seedcoat and the cotyledon. Modern mills have the ability to pit seedcoats and manage the moisture content before dehulling through a tempering process that involves water addition, heating and cooling. Approximately 80% of the world’s total lentil production is of the red cotyledon type. Most of these red lentils are consumed after secondary processing that removes the seedcoat by abrasive milling. When the seedcoat is removed, the cotyledons may remain intact (known as the ‘football’ type) and the product is sold to consumers specifically in the unsplit form. In many countries, the final product from splitting mills is the red split lentils. In general, there are very few published scientific investigations related specifically to the decortication and splitting process in lentil. Partly in response to the recent expansion of red lentil production and secondary processing facilities in Canada, Wang (2005) published a useful baseline

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laboratory method for assessing milling efficiency in lentil, based on conducting evaluations at 12.5% moisture using a Satake dehuller. This procedure can be easily used to assess the effects of various agronomic, environmental or genotypic effects on lentil milling efficiency. This protocol was recently used to assess the effect of the agronomic practice of chemical desiccation by diquat on milling efficiency (Bruce, 2008). Desiccation treatments were applied in four environments at early, recommended and late pod maturity stages for eight red lentil varieties. These were compared to similarly timed swathing treatments. Under ideal harvest conditions, differences due to treatments were minor. In environments that experienced harvest delay caused by wet weather conditions during the harvesting period, all three milling parameters (milling efficiency, dehulling efficiency and football recovery) were significantly reduced for all varieties by the early desiccation treatment compared to all other treatments. Split or football lentils are usually subjected to a polishing process to remove fine flour dust as a means of improving the visual quality of the product. Polishing with water is a common practice that is accomplished in some facilities by adding a small amount of water to the product stream as it passes in a horizontally mounted screw conveyor prior to bagging. Adding a small amount of vegetable oil (usually locally available products like sunflower or canola, for example) to the product stream is also used for red lentils destined for certain markets, especially in the Middle East. The oil penetrates the tissues of the dehulled seeds and deepens the colour of the red cotyledons. In some cases the lentils are double-oiled for specific markets. Oiling is also a traditional method of preparation of dehulled pulses in South Asia. The practice is commonly used in Africa and India at the household level to control grain storage insects such as Bruchus ervi Froel. (Coleoptera: Bruchidae – occurring in Europe, North Africa and South-west Asia) and Bruchus lentis Froel. (which occurs in the USA, Europe, North Africa and South-west Asia) and India (Periera, 1983). In some regions, lygus bugs such as Exolygus pratensis L., are a serious insect pest of lentil crops because feeding adults damage the seed, causing chalky spot syndrome (Özberk et al., 2006). Seeds with chalky spot have pitted, crater-like depressions in the seedcoat with or without a discoloured chalky appearance that reduces quality and in turn causes economic losses of 5–10 % to the producer. In Turkey, the value of dehulled lentils is maintained somewhat by ensuring a high recovery rate of lentils in the football form, specifically in red lentil where split cotyledons may display chalky spot on the inner surface of the cotyledon. By avoiding or minimizing the splitting process, the chalky spot problem is not as obvious and the economic losses are minimized. The colour-sorting process (Fig. 24.2) after dehulling or splitting can add considerable cost to the final product depending on the frequency and nature of the defects that are obvious after milling. Lentils with adhering hulls can be detected by electronic scanning devices; this is achieved based on colour comparisons of particles passing the scanning device. The machines can be adjusted to reject particles of a specified colour or colour contrast.

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Removal from the product stream occurs by using finely tuned compressed air jets to change the trajectory of the rejected lentils. The reject stream can be redirected to the dehulling process if the reason for rejection is failure to remove the seedcoat. Reduction in final product quality can be caused by variation in the cotyledons, for example, admixture of yellow cotyledons in red lentils, or vice versa. The specific problem of dark green immature cotyledons from normal-sized seeds can occur in some seasons or regions, for example in Mediterranean climates that experience the rapid onset of high temperatures prior to harvest. Extreme high temperature may cause rapid dehydration of the cotyledons, preventing normal colour development. The efficiency and cost of colour sorting of dehulled and split lentils is influenced by the colour contrast of the defect, the frequency of the defect and the initial and maintenance cost of the colour-sorting devices which are available from several manufacturers. Thermal processing in glass jars or cans is probably the second most common form of secondary processing of whole lentils, especially in regions where consumers purchase these products instead of dehulled lentils. European and North American consumers are generally more familiar with pulses in this form of consumer product. Thermal processing may alter the nutritional profile of the lentils, depending to some extent on the temperature used in the process and the chemical composition of the brine solution used in the canning procedure. Whole lentils with intact seedcoats may be added to other ingredients to make stews or soups in ready-to-eat form. In some countries, for example Spain, whole lentils in jars or cans, usually large green or Pardina types, are readily available for use as a quick side dish. Variations on the thermal process include packaging of prepared lentil dishes in foil or plastic envelopes or bags. Another form of secondary processing of lentils and other pulses is infrared drying (Cenkowski and Sosulski, 1997). Infrared treatments are applied to rehydrated whole lentils that are rehydrated to a moisture content of 19–39%. Using near infrared wavelengths of 1000–1500 nm, this process can quickly reduce moisture content and cause changes to cooking properties after dehydration. The process reduces cooking time and changes starch gelatinization and solubilization due to changes in porosity and water diffusivity (Scanlon et al., 2005). This process has been commercialized for whole lentils and other grain products (Infraready Products Ltd, 2008) to produce quick-cooking whole grains. For lentil, the cooking time is reduced to 15–20 min, similar to the cooking time for dehulled lentils. Lentils in dehulled or whole form may also be ground into flours for speciality applications in food processing. For example, dehulled green lentils may be used as an ingredient to make fortified pasta products (Barilla, 2008). Addition of lentils increases both the protein and the fibre content of the pasta. Whole or dehulled lentils may also be used as ingredients in extruded food products such as spiced snack mixes, which are especially common in South Asia. Other speciality uses of lentils include deep frying of soaked lentils for use in snack mixtures. In some parts of the world lentils are used as sprouts, much like mung bean, to increase

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the nutritional value. In North America and Europe, lentils in cooked form are used in salads with other vegetables. For most of these uses, lentils represent one of many similar ingredients. Most of the value addition for lentil is done at the level of street vendors, small restaurants or boutique food manufacturers. Over the past decade (1998–2008), food scientists have increased their efforts into studying the potential uses of lentil in tertiary food processing applications such as substitutes or enhancements for existing ingredients derived from other foods. In order to understand the potential for using lentils in food processing, it is necessary to understand the fundamental technical processing characteristics of the fibre and starch in lentils (see Grusak, Chapter 23, this volume). For example, processing properties of fibre include composition (amounts and types of cellulose, pectin, neutral polysaccharides, cellulose, lignin, oligosaccharides) and processing properties such as solubility, viscosity, gelling, swelling, fat binding, water binding and protein compatibility. This matrix of properties affects the potential application of using lentils in processes such as cooking, extrusion, air classification, germination, fermentation, and fractionization and separation. Recent scientific publications and patents focus on the possibility of using lentil for further food processing and inclusion of lentils in meat products, bakery products, dairy products, pasta products, speciality food products in dietetic applications (for example, gluten-free products for celiac diets) and snack foods (K. Ablor, 2008, Saskatoon, personal communication). Similarly, the specific properties of starches from lentils can be described in terms of concentration of amylose, amylopection, gelatinization temperature, enthalpy, retrogradation temperature, resistant starch content, starch digestibility, pasting temperature, viscosity and starch granule structure. Many gaps exist in global knowledge about food processing applications for lentils. Attributing processing properties to specific genotypes and environmental conditions is even more challenging, since many of the processing characteristics have not been fully described for even one genotype. Fundamentally, the question is one of economics. Most food characterization and processing techniques were developed for other major commodity grain crops such as maize, rice, wheat and among the food legumes, soybean and groundnut. Lentil is a relatively minor crop on a world scale. About 3.5 million t are produced on an annual basis, spread out over 48 countries (see Erskine, Chapter 2, this volume; FAO, 2008). In the 1997–2007 period, global lentil production increased from 2.7 to 3.5 million t. In comparison, during the same period, global soybean production increased from 123. 7 to 196.4 million t, an average annual increase of 7.3 million t equal to more than double the entire annual total world lentil production. The major crops are also the major focus of the food processing industry because of their relatively high availability and relatively low price in comparison to lentils. The major crops have higher returns on investment in value-added processing because they are often subsidized in the production systems because of their fundamental importance to national food supply.

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24.4. Future Trends in Processing and Value-added Activity Export-oriented pulse-crop industry associations and pulse-crop producer organizations in many parts of the world have begun to engage in research and development activity related to improving the consumer acceptance of pulses, including lentils. A major theme of these efforts is to raise the profile of pulse crops as an excellent source of nutrition in the human diet. One of the current trends in North America is a focus on health and wellness issues related to obesity, type 2 diabetes and other metabolic syndrome conditions. Increasing pulse consumption combined with significant changes in lifestyle (exercise) and diet could be one way to provide increased health and wellness benefits. However, this must be counterbalanced as a marketing strategy by the fact that every other plant food producers are pursuing a similar strategy. An accompanying trend in North America is a focus on using pulses as a food-processing ingredient. For reasons described above, the relatively high cost of lentils reduces their prospects as a source of ingredients, except for the lowest grade lentils that have reduced value as whole food. If consumers do respond to the use of pulses as ingredients, it is likely that the pulse-crop ingredient of choice will be field pea because of its higher yield which makes it cheaper. The underlying assumption is that consumer trends for increased convenience and improved nutrition will lead to expanded use of lentils and other pulses in value-added processing of new specific consumer products. Based on the above economic comparisons with other competing food grains, this may be a major challenge. A third trend in food marketing, is that of re-introduction or expansion of pulses in the diet as a traditional cultural food item as part of the return to the concept of eating wholefoods that are not highly processed. In North America and in Europe, lentils and other pulses can be re-positioned in the marketplace as part of a healthier diet with cultural origins in the Mediterranean, the same region where lentil was domesticated. In contrast, in most parts of Asia and the Middle East, lentils have never lost their traditional status as a healthy wholefood. The potential for value addition for lentils in the food industry anywhere in the world is ultimately dependent on the perceived nutritional and culinary value that lentils can provide. Similar to the macronutrient profile of many other pulses, lentils are approximately 25% protein, with the remainder providing carbohydrates and fibre, along with small amounts of micronutrients and vitamins. The carbohydrate profile is relatively high in resistant starches which digest more slowly, providing fibre-like nutritional benefits. If pulses are processed to add value on the basis of the economics of yield and unit cost of macronutrients, lentil will not be competitive even with higher yielding pulse crops such as pea. In comparison to the major cereal grains and food legumes, many of which are much higher yielding, the unit cost of macronutrients in lentils is simply not competitive. The concept of value-added processing is based on the premise that the ingredients are inexpensive. For food products that are already relatively

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high in value because of lower yield and lower availability, like lentils, the value-added potential is restricted to boutique food products. The availability of a wide variety of seedcoat colours and sizes and red, yellow and green cotyledons may help add value as lentil products are more closely tailored to specific consumer preferences. Alternatives to value-added processing include value-added marketing, a scenario in which lentils are marketed as a balanced and healthy wholefood alternative to highly processed foods which will increasingly be made from a much smaller group of global crops with high productivity and volume. One distinct advantage and highly competitive advantage of lentils, particularly in dehulled form, is the fact that they cook in about the same time as milled rice, providing both convenience and energy savings. Another avenue of current scientific investigation that could influence future value-added marketing concepts for lentils, is the role that lentils may play in providing sustainable metabolic energy for athletic performance (Little, 2007). This may lead to innovative marketing strategies that promote the perception of improved nutritional value for lentils. A third value-added marketing strategy is one that emphasizes some of the inherent nutritional benefits of lentils, more specifically their micronutrient and vitamin content. They are known to be excellent sources of Fe, Zn, other micronutrients and folate and may provide high levels of low-cost bioavailable nutrition. This is a wide-open area for future research that may help prevent the relative global decline in lentil consumption. Based on recent economic development trends in the Middle East and other regions where lentil milling was historically established, it is likely that many of the small dhal mills in South Asia will be replaced by less labour-intensive and larger modern mills in the major port regions of consuming countries. This has already occurred in Turkey, where many small lentil mills were replaced by more modern facilities at the port in Mersin, where exporting and importing could be accommodated more easily. A similar situation may develop in South Asia as labour rates and demand for higher milling efficiencies increase. Concurrent with this trend could be increased milling capacity in large and growing production regions like Canada and Australia. Rising energy costs that cause transportation costs to increase will probably make it more economical to ship dehulled lentils. As dehulling mills become larger it may be feasible to explore the potential for value addition from waste products like hulls that are now used only for animal feeding. The economic feasibility of phytochemical extraction for specific compounds such as antioxidants requires evaluation in future. At this point in time, the future of the global lentil industry may depend entirely on developments in the South Asian countries, where most lentil consumption occurs. If South Asian consumers, in particular in India, develop food habits that reduce lentil consumption in favour of other pulses and soybean, lentil production and consumption will decline globally. Although recent trends suggest that per capita consumption of all pulses is declining in South Asia, there is debate as to whether the decline is due to higher prices or changing consumer preferences. Some evidence (Kyi et al., 1997;

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Kumar, 1998) suggests that as incomes rise in South Asia, pulse consumption increases. If this is true, the future of value-added processing in lentil may be closely linked to the degree that lentils produced in other countries can successfully supplement the role that summer pulses such as pigeon pea, black gram and green gram play in traditional South Asian cuisine. A similar situation has occurred over the past 15 years with respect to the substitution of yellow pea dhal and flour for desi chickpea dhal and flour. Consumption of imported yellow pea in India has risen from almost nil to more than 1 million t in the past 15 years. The future of lentil consumption globally may also be related to the extent to which South Asian cuisine is popularized in the rest of the world. Food trends now move easily around the globe, and if consumers in developed countries develop greater acceptance of food products based on South Asian dishes, lentil consumption will also increase. Value-added processing will increasingly come under the influence of the cost of energy inputs into total food systems, from the production end right through the chain of value to the end consumer. This will affect all aspects of lentil production, including the scale of primary, secondary and tertiary processing.

References Barilla (2008) Barilla® PLUS® is a Good Source of Protein. Available at: http://www. barillaus.com/Home/Pages/Barilla_Plus__Protein.aspx (accessed 8 July 2008). Bruce, J.L. (2008) The effects of preharvest treatments on the milling efficiency of red lentil. MSc thesis, University of Saskatchewan, Saskatoon, Canada. Cenkowski, S. and Sosulski, F.W. (1997) Physical and cooking properties of micronized lentils. Journal of Food Process Engineering 20, 249. Cenkowski, S., Sokhansanj, S. and Sosulski, F.W. (1989) Equilibrium moisture content of lentils. Canadian Agricultural Engineering 31(2), 159–162. Davey, B.F. (2007) Green seed coat colour retention in lentil (Lens culinaris). MSc thesis, University of Saskatchewan, Saskatoon, Canada. Ehiwe, A.O.F. and Reichert, R.D. (1987) Variability in dehulling quality of cowpea, pigeon pea and mung bean cultivars determined with the tangential abrasive dehulling device. Cereal Chemistry 64(2), 86–90. Erskine, W., Williams, P.C. and Nakkoul, N. (1991) Splitting and dehulling lentil: effects of seed size and different pretreatments. Journal of the Science of Food and Agriculture 57, 85–92. Food and Agriculture Organization (FAO) (2008) FAOSTAT Statistical Database of the United Nations Food and Agriculture Organization (FAO), Rome. Available at: http://faostat.fao.org/ (accessed 8 July 2008). Hughes, J.S. and Swanson, B.G. (1986) Microstructure of lentil seeds. Food Microstructure 5, 241–246. Ilyas, S.M. and Goyal, R.K. (2005) Advances in pulse processing. In: Singh, K., Sekhon, H.S. and Kolar, J.S. (eds) Pulses. Agrotech Publishing Academy, Udaipur, India, pp. 533–566. Infraready Products Ltd (2008) Products. Available at: www.infrareadyproducts.com/ aboutus.html (accessed 8 July 2008).

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Kumar, P. (1998) Food Demand and Supply Projections for India. Agricultural Economics Policy Paper 98–01. Indian Agricultural Research Institute, New Delhi, 141 pp. Kurien, P.P. (1984) Dehulling technology of pulses. Research and Industry 29(3), 207–214. Kyi, H., Mruthunjaya, Khan, N.A., Liyanapathirana, R., and Bottema, J.W.T. (1997) Market Prospects for Pulses in South Asia: International and Domestic Trade. Working Paper 27. The Coarse Grains, Pulses, Roots and Tubers (CGPRT) Centre, Bogor, Indonesia, 101 pp. Little, J.P. (2007) The effects of low and high glycemic index meals on metabolism and performance during soccer-specific intermittent exercise. MSc thesis, University of Saskatchewan, Saskatoon, Canada. Muller, F.M. (1967) Cooking quality of pulses. Journal of the Science of Food and Agriculture 18, 292–295. Özberk, I., Atli, A., Özberk, F. and Yücel, A. (2006) The effect of lygus bugs (Exolygus pratensis L.) on marketing price of red lentil in Anatolia, Turkey. Crop Protection 25(12), 1227–1230. Periera, J. (1983) Effectiveness of six vegetable oils as protectants of cowpeas and bambara groundnuts against infestation by Callosobruchus maculates (F.) (Coleoptera: Bruchidae). Journal of Stored Product Research 19, 57–62. Scanlon, M.G., Cenkowski, S., Segall, K.I. and Arntfield, S.D. (2005) The physical properties of micronized lentils as a function of tempering moisture. Biosystems Engineering 92, 247–254. Siegel, A. and Fawcett, B. (1976) Food Legume Processing and Utilization (with Special Emphasis on Application in Developing Countries). International Development Research Centre, Ottawa, Canada, 88 pp. Singh, S., Singh, H.D. and Sikka, K.C. (1968) Distribution of nutrients in the anatomical parts of common Indian pulses. Cereal Chemistry 45, 13–18. Tang, J., Sokhansanj, S. and Sosulski, S. (1994) Moisture absorption characteristics and hard seed development in Laird lentils. Cereal Chemistry 71(5), 423–428. Wang, N. (2005) Optimization of a laboratory dehulling process for lentil (Lens culinaris). Cereal Chemistry 82(6), 671–676. Williams, P.C., Erskine, W. and Singh, U. (1993) Lentil processing. LENS Newsletter 20(1), 313.

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Food Preparation and Use Rita S. Raghuvanshi and D.P. Singh

G.B. Pant University of Agriculture and Technology, Pantnagar, India

25.1. Introduction Cereal grains and grain legumes are the major source of calories and proteins for a large proportion of the world’s population. Legumes are a rich source of proteins and the essential amino acid, lysine, but are usually deficient in the sulfur-containing amino acids, methionine and cystine. On the other hand, cereal grains contain lower concentrations of proteins that are deficient in lysine but have adequate amounts of sulfur-rich amino acids (Eggum and Beame, 1983). It is therefore emphasized that legumes are the natural supplement to cereals in ensuring essential amino acid balance. Also, it is being increasingly recognized that legumes are good source of vitamins and minerals. In countries where non-vegetarian food is expensive and its consumption restricted for cultural reasons, the protein-rich lentil provides a cheap substitute. Lentils are lower than most pulses in antinutritional factors such as haemagglutinin, oligosaccharides and flavogens. They contain tannins in the seedcoat but not in cotyledons (Vaillancourt et al., 1986). In small-seeded lentil (microsperma) with red cotyledons even this is not important as the testa is frequently removed before use in culinary preparations. The macrosperma (large-seeded) lentils also contain tannins, which can cause digestive disorders. Lentils are a major component of food in the Mediterranean region and the Middle East. In the Indian subcontinent lentil is mostly eaten as porridge or thick soup called dal.

25.2. Physio-chemical Properties and Cooking Quality of Lentil The chemical composition of lentil seeds indicates that lentils can be the ‘perfect diet’ as they contain little fat (~1–2%) and large concentrations of 408

© CAB International 2009. The Lentil: Botany, Production and Uses (eds W. Erskine et al.)

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proteins with an energy value of 24–32% and minerals (iron, cobalt and iodine) (Kowieska and Petkov, 2003). Savage (1988) reported that lentils by virtue of their high protein content could be processed to produce many products similar to those produced from soybeans. Leucine was the major essential amino acid in lentil flour. Lentil is rich in lysine and arginine, and can fulfill the essential amino acid requirement except for the sulfur-containing amino acids and tryptophan (El-Zoghbi, 1998). Pasantes and Flares (1991) reported taurine content of lentil as 25 nmol/g, 50% of which is leached out during soaking, while the cooking procedures in the absence of presoaking did not affect the same. Sanchez et al. (1994) reported that lentil contained higher concentrations of nonstarch polysaccharides than cereals and a greater portion was in the form of soluble non-starch polysaccharide. Paliwal et al. (1987) reported that lentil chuni (groats), a by-product from the lentil processing industry produced during dal manufacturing, contains 23.3% crude protein, 1.6% ether extract, 21.6% crude fibre, 48.2% nitrogen-free extract and 5.2% total ash. Candella et al. (1997) reported that cooking decreases the mineral content of lentils whereas warm holding practices resulted in decreased isoleucine, valine and leucine and significant increase in lysine, phenylalanine and tyrosine. The analysis of seven cultivars of lentil for cooking time revealed that the least amount of time required for cooking was 40 min and was positively correlated to total ash (r = 0.24), fibre content (r = 0.18) and seed size (r = 0.12), and negatively correlated with protein content (r = 0.19) (Raghuvanshi et al., 1994). Even though lentils are considered to be highly nutritious, they contain antinutritional factors such as trypsin inhibitors, haemagglutinins and oligosaccharides that cause flatulence. These problems can be greatly reduced by heating and germination. Estevez et al. (1991) found that heat treatment reduced activity of trypsin inhibitors and significantly increased digestibility of seed proteins. Germination of lentil for 6 days at 20°C followed by cooking resulted in breakdown of disaccharides and destruction of phytic acid thus improving digestibility and availability of calcium, magnesium, iron and zinc (Garcia, 1991). In another study, Camacho et al. (1992) found that germination of overnight-soaked lentil at 25°C and 85% relative humidity (RH) for 3 days in a solution of sodium hypochlorite resulted in an increase in crude protein content with an increase in almost all amino acids; however, the concentrations of ash, ether extract and phytates decreased.

25.3. Food Uses Lentil is the most desired legume in many lentil-producing regions because of its high average protein content and fast cooking characteristics (Fig. 25.1). It can be used as a starter, main dish, side dish or in salads. Seeds can be fried and seasoned for consumption as snacks. Flour is used to make soups, stews and purées, and mixed with cereals to make bread and cakes, and as a food for infants. Young, green, fresh lentil pods are eaten raw or steamed

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Food uses

Green pods

Whole grain

Vegetable Curry Salad Salad Soup Dal Namkeen (salty and spicy snacks) Snack sprouts Lentil fritters Lentil sprout spread Lentil burgers Canned food mix

Decorticated/split

Flour

Medicinal uses

Fodder uses

Soup Dal Khichri Kebab Dosa Soup Papad Vermicelli Infant food Lentil loaf

Therapeutic diet Paste for surface application Lentil water for external washes Broken stem Branches Pod walls Leaflets

Fig. 25.1. Uses of lentil.

like green peas, while lentil sprouts are added to salads, soups, breads and savoury dishes.

25.4. Methods Used in Lentil Preparations There are several methods used in lentil preparation, which provide different texture and nutritional quality to the final products. The methods are detailed with their effects on nutritional quality.

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Soaking Washing/cleaning of lentil is done before soaking, which helps to remove chemicals and other unwanted matter. However, water-soluble nutrients are lost during the process. This can be reduced by quick thorough washing. Soaking is done in fresh or saline water with sodium chloride or sodium bicarbonate. It hastens the process of cooking. Prodanov et al. (2004) found that soaking lentil in different solutions (citric acid solution, pH 4.96 ± 0.02; distilled water, pH 7.00 ± 0.02; and sodium bicarbonate solution, pH 7.85 ± 0.02) caused losses of 5–10% thiamin and 26–42% available niacin while riboflavin increased up to 98%. The losses were greater with soaking in alkaline solution. An appreciable increase in hemicelluloses and neutral detergent fibre was seen when lentils were soaked in 0.1% citric acid solution and 0.07% sodium bicarbonate solution (Vidal et al., 1992). Boiling Boiling is probably the most frequently used method for cooking lentils. It may be open-pan boiling or pressure cooking. In open-pan boiling, lentils are cooked by immersing them in boiling water until tender. While using openpan boiling for cooking, the heat is turned down when the contents start boiling as violent boiling throughout may result in breakage and disintegration of grains. Continued vigorous boiling only results in excessive evaporation of water, as a result the lentils may be burnt at the bottom. If excess water is used for cooking and the water is discarded, 30–70% of the water-soluble nutrients may be lost. Over-boiling of lentil may make it mushy. Pressure cooking raises the temperature above 100°C and reduces cooking time. The losses of fats and carbohydrates in lentil are more or less similar for open-pan boiling and pressure cooking, but more proteins are retained in pressure cooking (Pratibha et al., 1999). The in vitro protein digestibility of proteins (81.0%) was greater in pressure-cooked lentil as compared to openpan boiling (Naveeda and Jamuna, 2006). Pressure cooking caused 23.5% loss of tryptophan against 32.9% in open-vessel cooking (Parihar et al., 1996). Although boiling results in the loss of nutrients, it simultaneously reduces concentrations of antinutritional factors and improves the nutritional value of lentil. Heating lentils at 120°C at 1 atmospheric pressure for 30 min decreased trypsin inhibitor activity, phytates and tannin content by 76%, 8% and 12%, respectively (Porres et al., 2003). Warm holding is a widely used technique in catering services. Candella et al. (1997) studied the effect of warm holding on the total composition and amino acid content of kidney bean, chickpea and lentil, of which lentil was found to be most affected. Sprouting/germination Lentil seeds are easy to sprout. To have good home-made sprouted lentils, seeds are soaked in water overnight and the free water is drained in the

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morning. The grains are washed two to three times without rubbing. The soaked seeds are covered and kept in a warm dark place. One more washing is done at night and all the water is drained and the seeds are kept again as before. Sprouts of about 2.0 cm length are ready by the next morning. Porous containers like an earthen pot or humidity chamber should be used for best results. The presence or absence of light during germination had no significant effect on the thiamin and riboflavin content in germinated lentils while niacin content was higher when germination took place under light. The increased number of rinses during the germination process had no significant effect on the thiamin content while riboflavin and available niacin increased significantly. However, no effect was seen on riboflavin when seeds were germinated for 6 days and on niacin when germination was carried out for 3 days in the dark. A longer germination time led to recovery of thiamin content and a significant increase in riboflavin and niacin content (Prodanov et al., 1997). Hulled seeds should not be used for sprouting, as they may split and the embryos be injured. Soaking lentil seeds for 12 h and then sprouting for 3–4 days has been found to completely remove all haemagglutinin and amylase inhibitor. A marked increase in moisture content and reduction in protein, fat, fibre and ash content was observed in sprouted lentil; however, the protein content of sprouts increased on a dry weight basis (Vanderstoep, 1981). Germination resulted in total elimination of a-galactosides and reduction in total starch content and trypsin inhibitor activity (Urbano et al., 1995). The vitamin content, that is thiamin and niacin (Urbano et al., 1995), riboflavin and biotin (Hozova, 1994) and ascorbic acid (Hsu et al., 1980), also increased in sprouted lentils.

Fermentation Fermentation is the process of breaking down complex compounds into simpler ones with the help of enzymes and bacteria. Fermented foods are more nutritious than their unfermented counterparts because of improved protein quality, increased vitamin B synthesis and reduced antinutritional factors. Fermentation of lentil for 4 days resulted in a slight increase in crude protein content and significant increase in in vitro protein digestibility (Shekib, 1994), whereas fermentation for 2 days reduced total galactosides and trypsin inhibitor activity by 26% and 50%, respectively (El-Rahman et al., 1998). Lentils can also be processed by extrusion cooking. However, application of lactic acid fermentation as a pretreatment was suggested by El-Rahman et al. (1998) to increase the consistency coefficient, yield stress and thixotropy values of lentil slurries during the first 24 h of fermentation.

Frying The various products prepared from lentil using the frying technique are papad, cutlets, dosa, pancakes, etc. Frying may involve deep-oil frying,

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shallow frying and sautéing. Cooking is rapidly completed in deep-oil frying as the temperature is 180–220°C. Deep frying of food increases the calorific value due to absorption of oil. In shallow frying, the food is cooked in a larger volume of oil than sautéing but not enough to cover it. Heat is transferred to the food partially by conduction (i.e. by contact with the heated pan) and partially by the convection current of the foods, for example cutlets and patties. Sautéing involves cooking in just enough oil to cover the base of the pan (greasing the pan), for example dosa and pancakes. The food is tossed or turned over occasionally with a spatula to enable all the parts to come in contact with the oil and get cooked evenly.

Dry-heat methods When food is cooked uncovered in a metallic frying pan, the method is known as pan broiling or roasting. The advantage of the method is that it reduces the moisture content of the food and thus improves its keeping quality; however, losses of nutrients such as amino acids can occur if the food becomes brown. Urbano et al. (1995) found that roasting resulted in reduced starch content and trypsin inhibitor activity in lentils. Microwave cooking does not require any medium of transfer of heat in the cooking process as heat is generated inside the food, whereas in conventional cooking methods the heat is transferred to the exterior of the food by conduction, convection or radiation. Both methods are equally effective in destroying the antinutritional factor in lentil (i.e. trypsin inhibitor) without any adverse effect on the protein efficiency ratio (PER) of raw seeds (Hernandez et al., 1998). The nutrient composition of microwave-cooked lentil was also more or less similar to that in pressure-cooked lentil except for thiamin, which was lost to a significant extent in microwave cooking. The in vitro digestibility of proteins in microwave-cooked samples was 75.2% (Naveeda and Jamuna, 2006). Baking is a dry-heat method of cooking but the action of dry heat is combined with that of steam, which is generated while the food is being cooked. The baking properties of lentil flour were evaluated by incorporating 5, 10 and 15% flour of germinated or dry lentils with wheat flour before baking and it was found that mixing of up to 15% lentil flour with wheat flour had no adverse effect on loaf volume (Hsu et al., 1980).

25.5. Preparations and Recipes Usually, lentils are boiled to a stew-like consistency with or without vegetables and then seasoned with a mixture of spices to make many side dishes such as sambhar, rasam and dal, which are usually served over rice and sometimes with roti (unleavened bread).

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Salad A salad is a dish that usually (but not always) takes off from a green leafy base, usually piquant in flavour, mostly served cold with a cold dressing made of oil, vinegar and special flavourings. The word salad comes from a Latin word meaning ‘salted’. A simple recipe to prepare lentil salad at home requires about 225 g whole lentils, salt (two tablespoons; tbsp), plain flour (one tbsp), freshly ground black pepper, olive oil (four tbsp) and one small finely chopped onion. The method involves soaking the lentils overnight in lukewarm water with cooking salt and flour. The following day the lentils are removed from the water and the water is brought to a boil and then cooled. The rinsed lentils are then added to this water and brought to the boil and then simmered gently for 30 min. They are then strained, the water discarded and the lentils put into a large saucepan with plenty of fresh, lightly salted, boiling water, covered and cooked until tender and then well drained. While the lentils are still warm, they are seasoned to taste with salt and pepper and olive oil and finely sliced onion is stirred into them (Russell, 1974).

Soup Lentils are used to prepare an inexpensive and nutritious soup all over Europe and North and South America, sometimes combined with some form of pork or chicken meat. Soup can be prepared from mature whole seeds, dehulled lentil flour or splits. To prepare lentil soup, onion and celery are fried lightly for 10 min in 25 g melted butter in a large saucepan, and 150 g lentils and 1.1 l of stock with spices (quarter of a teaspoon of ground cloves and quarter of a teaspoon of ground allspice) are added to the saucepan and brought up to the boil. The heat is turned down when it starts boiling and the lentils are allowed to simmer gently for 30–35 min or until they are soft. Then it is transferred to a liquidizer or food processor and processed until smooth. The soup is reheated gently and seasoned to taste with salt and black pepper (Good Housekeeping Institute, 1966). Some of the typical ingredients added into a lentil-vegetable soup may include green beans, lentils, carrots, celery, tomatoes, spinach, potatoes, garlic and various seasonings. The soup is made from a water base and as it cooks, a thick sauce-like consistency develops that enhances the flavours of all other ingredients. In Morocco, a similar process is used to prepare lentil with vegetables and the recipe is known as lentil tagine. The method of preparation involves boiling 450 g lentil, 1.1 l of fresh vegetable stock and four cloves of garlic in a saucepan and then simmering for 20 min. Sweet potatoes (675 g), tomatoes (550 g), capsicum (325 g), onions (325 g), ginger (one tbsp), cumin (one teaspoon), cayenne pepper (one teaspoon) and salt (to taste) are added to this and cooked for another 30 min or until the sweet potato is soft. The soup is garnished with chopped coriander while serving. Use of lentil in dehydrated form for preparation of lentil soup can offer a unique opportunity for its consumption, providing value addition apart

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415 Lentil seeds

Cleaning impurities

Dehulling

Frying onions (15 g) with olive oil (20 g) for 2 min

Adding lentil splits (200 g), NaCl (8 g) and deionized water (500 ml)

Cooking for 45 min Moulding into aluminum frames (1 × 1 × 0.05 cm) Drying at 75°C using air-forced oven

Removal from frames

Dehydrated traditional lentil cubes

Fig. 25.2. Process flow chart for producing dehydrated lentil soup cubes (Source: Ereifej, 1995).

from protecting it from insect damage (lentil seeds are prone to insect damage but dehydrated lentil soup cubes are packaged and not exposed to environmental factors leading to infestation). A process for the preparation of acceptable and nutritious traditional lentil soup cubes has been developed in Jordan by Ereifej (1995). Whole and sound seeds of ‘Balady’ landrace and three newly developed lentil cultivars (‘Jor-1’, ‘Jor-2’ and ‘Jor-3’) were used. The process consisted of cleaning, dehulling, frying cut onion with olive oil, addition of salt, lentil splits and water, cooking, moulding and drying (Fig. 25.2). The soups prepared from all lentil cultivars had similar appearance and flavour and produced acceptable soup cubes, however, the commercial soup scored higher for appearance and flavour. The cultivar ‘Jor-1’ was superior to commercial soup with respect to protein content and energy value.

Dal Lentil is predominantly eaten in South Asia as boiled or fried dal from whole seed (from macrosperma) or split (microsperma) as lentil (masur) dal. For preparing dal, whole grains are soaked in water overnight, drained and then boiled in fresh water for 30–40 min. It is consumed after salt and spices

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are added. The split grains with or without husk are cooked by boiling in water for 30–40 min. Salt and spices are added to taste and the cooked mashed dal is consumed along with a cereal preparation. The preparation appears as a thick soup and is eaten with unleavened bread roti (chapatis) made from cereals such as wheat or maize, etc. Boiled rice is also eaten with lentil dal. To remove the seedcoats, the seeds are moistened with oil and water, dried in shade and passed through a mill two or three times. To give an attractive appearance, the dal is polished with magnetite powder and gritty powder. To prepare lentil dal, approximately five cups of water are used for one cup of lentil. Water is added to the saucepan and lentil is added when the water begins to boil. It is boiled for 2–3 min and then the heat is reduced to simmering and dal is cooked until tender. Flavourings such as garlic and onion can be added if desired; however salt should be added at the end otherwise lentil tends to be tough. Different cultivars require different cooking times. Green and brown lentils are cooked for approximately 45 min and red (dehusked) lentils for 25 min. People in Hyderabad (South India) make a preparation called khatti dal which is seasoned with tamarind juice and ginger garlic paste during cooking. Mildly sweet, pungent and tart, the khatti dal dazzles the taste buds and tastes great on its own or with rice and chapatis (Indira Singari, 2008). In Assam (north-east India), lentil dal is prepared with several variations such as cooking with bamboo shoots, Colocasia leaves (Colocasia anti-quorum) or ferns. Lentil dal with bamboo shoots is prepared by pressure cooking 50 g lentil dal in 600 ml water with salt (10 g), green chilli (5 g) and turmeric (5 g), and then seasoned with grated bamboo shoot (30 g) and fenugreek seeds (5 g). The nutrients provided by this amount of dal are 21.1 g protein, 12.9 g fat, 5.0 g minerals, 20.5 g fibre, 4.8 g carbohydrate, 427.5 kcal energy, 97.8 mg calcium and 7.2 mg iron. To prepare lentil dal with Colocasia leaves, 50 g lentil is cooked with chopped Colocasia leaves, 10 g salt and 10 g sugar in 800 ml water and then seasoned with 15 g garlic and 10 g black pepper powder using 15 g mustard oil. It has a higher amount of calcium (415.4 mg) and iron (12.3 mg). Lentil dal with fern is prepared by pressure cooking 100 g lentil with 40 g tomatoes, 50 g ferns, 5 g green chilli, 5 g turmeric, 10 g salt and 10 g sugar in 650 ml water. The seasoning is done with 5 g mustard seeds in 15 ml mustard oil with 15 ml lemon juice added while serving. It gives about two servings and the nutrients available are 20.9 g protein, 10.8 g fat, 4.2 g minerals, 1.1 g fibre, 62.6 g, carbohydrate, 432 kcal energy, 250 mg calcium and 8 mg iron. The conventional method of cooking resulted in about a 2% increase in lentil protein. Diets containing cooked lentil and supplemented with different types of meat (10% poultry, 15% mutton and 20% beef) significantly improved PER (from 1.45 to 1.65), true digestibility (from 76 to 87%) and net protein utilization (NPU) (from 43 to 51%) over non-supplemented diets (Bhatty et al., 2000).

Khichri A combination of cereals and legumes cooked together is called khichri. It is made from a mixture of dry masur dal and cooked wheat mixed in the ratio of

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3:7 or a mixture of split/dehulled lentil with rice. The mixture is cooked to a soft consistency, salted and served as a staple (Nezamuddin, 1970). In West Asia and North Africa the macrosperma lentils are used in mjeddarah made of whole lentil and immature wheat seed. Mjeddarah, a Lebanese staple is also a khichri-like product but the difference is that here lentil is combined with brown rice and it is seasoned with onion, pepper and a few more spices with vegetables added as optional ingredients. To add variety to mjeddarah, Parmesan cheese is sprinkled as a garnish (Wikimedia Foundation Inc., 2008a, b). Another similar dish of mjeddarah is a basic component of Palestinian cuisine with lentil and wheat. Sometimes rice is used in place of wheat with the same procedure and the recipe is gluten free (Wikimedia Foundation Inc., 2008a, b). Lentils are frequently combined with rice, which has a similar cooking time and is known by the name of khichri, pulav or koshary. Because of time constraints, various kinds of ready-to-eat, heat-eat and instant mixes are available in the market. Shekib et al. (1986a) prepared an instant koshary (a lentil-rice blend) using decorticated lentil and rice which has a shelf life of 21 days at 37°C (moist atmosphere) and 60 days at 25°C with a high nutritive value as compared to rice and lentil alone. The methionine content was 0.94, 2.62 and 2.01, cystine 0.96, 1.92 and 1.54 and lysine 7.09, 3.41 and 4.70 g/16 g nitrogen in lentil, rice, and the lentil-rice mixture in 1:2 ratio in koshary, respectively. Their respective in vitro protein digestibility values were 63.9, 73.5 and 75.6% compared to 98.9% of casein (Shekib et al., 1986b). Khichri, mjeddarah, lentil pulav or khoshary are all lentil-rice blends in different proportions. These preparations make the main dish of a meal. In Gujarat (western India), khichri is very popular, particularly for dinner. The process involves soaking one teacup each of rice and lentils in plain water for 10–15 min and then pressure cooking with 5–6 cups of water with salt and other spices added. Heat is reduced after the first whistle and the khichri is cooked for an additional 4–5 min. Hot khichri is served with ghee (clarified butter) or curd. Sweet pongal is another form of khichri made with one part rice (100 g), one part dehusked split lentil (100 g), two parts jaggery (200 g), grated coconut (20 g), raisins and cashew nuts (5.0 g), refined oil (15 g) and ghee (30 g). The rice and lentil are slightly roasted in oil and then cooked in boiling water. When the rice is about 75% cooked, jaggery, coconut and raisins are added and cooked till soft but grainy in texture. It is served with ghee to give the distinct flavour. The dish is part of the main meal; however, it is served towards the end in South Indian cuisine. Sweet pongal is a protein-energy rich product, 100 g having around 4.5 g protein, 4.4 g fat, 31 g carbohydrates and 185 kcal energy.

Vegetable The hulled green seeds of macrosperma lentils are used as green vegetable. The green pods of lentil are shelled and washed. One cup of shelled lentil is boiled in water with salt. In a saucepan 20 g butter is melted. Cut garlic (one teaspoon) and cubed ginger (one teaspoon) are put in hot butter. When slightly pinkish, one cup of carrot cubes, half a cup of capsicum and half a

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cup of boiled maize are added to the saucepan. It is kept on a medium heat for 5 min then the boiled lentil is added to the mixture. It is sautéed for a while. Salt and black pepper are added to the mixture. It is again cooked for a few minutes. The vegetable is garnished with chopped tomatoes, green chilli and coriander leaves. It is usually a side dish with the meal. Having green lentil as the main ingredient, the preparation has good quality protein along with vitamins and minerals. Masur curry is prepared using 100 g lentil, 80 g tomatoes, 40 g spring onion, 30 g oil, 60 g onion, two cloves of garlic, half a teaspoon of cumin seed, a 2.5 cm length of ginger (diced), half a teaspoon of chilli powder, two teaspoons of coriander powder, half a teaspoon of turmeric and salt to taste. The lentil is cleaned, washed and soaked overnight. It is pressure cooked with 400 ml water, turmeric and salt for 10–12 min. In a separate vessel, the seasoning is prepared by heating the oil and tempering it with cumin seeds. Thereafter, garlic, ginger and onion are added. When the onion becomes pinkish to brown, the chilli powder, coriander powder and tomatoes are added and cooked for 2–3 min. The seasoning is put in the cooked dal. The preparation will be around 300 ml of semi-solid consistency. One serving of this curry (approximately 150 ml) has 8 g protein, 5 g fat, 12 g crude fibre, 78 kcal energy, 37 mg calcium and 2.89 mg iron.

25.6. Lentil Snacks A fried and crispy salty snack prepared from legumes is called namkeen. In the Indian subcontinent whole lentil grains are soaked, dried and deep fried. The salt and spices are added and the finished product is eaten as a snack. The fried lentil namkeen is made up of 16.6% protein, 20.5% fat, 0.59% ash, 1.95% crude fibre, and provides 465 kcal energy, 45.9 mg/100 g calcium and 7.5 mg/100 g iron (Verma and Raghuvanshi, 2002). To prepare salty ‘snack sprouts’, a half cup of lentils are soaked in water for 8–12 h, drained and sprouted for 3–5 days until the length of shoots equal the seed length, with two or three rinses daily. To these sprouted grains, onion powder (two tbsp), garlic (one teaspoon), tamarind (two tbsp) and pepper (a pinch) are added and baked at 120°C until brittle and crispy, which takes approximately 1 h and the tasty ‘snack sprouts’ are ready. These snacks can be stored in an airtight container which will keep them dry and crisp. Lentil fritters are prepared by blending one cup of sprouted lentils in a processor and combining with grated cheese (one cup), half a teaspoon of soy sauce, salt, pepper, half a cup of finely chopped onion, half a cup of beef stock and one cup of fresh breadcrumbs. The mixture is then made into balls and put into an oiled frying pan and shallow fried. Kebabs are small balls (2.5 cm in diameter) made with dal paste that has been dried over a low heat and these can be used dry or in soup like dumplings. To prepare lentil kebabs, one cup of red lentils (washed and soaked overnight) are ground in a mortar and the mixture is whipped into a paste.

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One tablespoon of oil is heated in a heavy pan and the above paste is cooked over a low heat until the mixture thickens and changes colour. Salt and a mixture of black pepper, coriander, cloves, cumin seeds, cinnamon sticks and nutmeg are added and the paste is allowed to cool. This dough is made into balls of 2.5 cm in diameter and shallow fried until golden brown. Dosa is a thin, crisp, fried pancake-like staple food of South India, considered mainly a breakfast food but has become popular as a snack food throughout India. Black gram with rice is generally used as the starting substrate for production of a variety of fermented products like dosa, idli, adai, etc. Different cookbooks use the ratio of 1:3 to 3:1 of pulse and rice. Black gram is at times replaced with lentil to make an easily digestible and less flatulent product. It is prepared by soaking three parts of rice and one part of black gram or lentil dal in water for 4–6 h at ambient temperature, grinding to a fine paste by adding 2.0–2.5 parts (w/w) water and mixing the two together to make a free running batter. The batter is mixed with 1% salt and allowed to ferment for 12–24 h by natural microflora or by inoculating with the fermented batter of the previous batch. On a hot and greased griddle about 60–80 ml of the batter is thinly spread for a few minutes where it assumes a thin, crisp pancake. It is then soaked and served with coconut chutney (pungent sauce) and sambhar (thin pigeon pea dal cooked with a heavy dose of spices and vegetables, tamarind and curry leaves). As per recorded history, idli have been used in India since 1100 ad. It is a small, white, acid-leavened steamed cake made from fermented thick batter of carefully washed, soaked rice and dal (black gram or lentil). These are soft and spongy with a mildly sour flavour and eaten with sambhar, coconut chutney, pickles or dry chutney powder. Normally the proportion of dal with rice used is 1:3. The amount of water required to prepare the batter to be of a desirable and uniform consistency varies around 1:5 times on a dry weight basis of the ingredients. In this case, rice is coarsely ground in comparison to the dosa batter. The coarsely ground batter with 1% salt is fermented for 18–30 h with natural microflora. The fermented batter is then poured with a ladle on to greased round-shaped perforated moulds and steam cooked for 10–20 min to give a fine-textured idli ready to eat. The soaking of rice and dal brings about the rapid disappearance of common aerobic contaminants. Leuconostoc mosenteoids and Streptococcus faecalis develop concomitantly during soaking and continue to multiply after grinding and play a significant role in fermentation. More than a dozen bacteria and yeast have been identified in the fermented idli and dosa batter. Proteins are partially converted to amino acids in the fermented products; dosa usually has 15–20% protein, 15–25% fat and around 400 kcal energy. Water-soluble group B vitamins, namely thiamin, riboflavin, niacin and cyanocobalamin, increase significantly as the batter fermentation progresses (Soni and Arora, 2000). Sprouted lentil can be used to prepare a variety of food items such as spread (lentil sprout spread), cutlets (lentil fritters), dal and other snacks. Lentil sprout spread can be prepared by sprouting half a cup each of lentil (for 3–4 days) and sesame seeds (for 1–2 days). Then they are put in a processor

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to which ripe avocado, ground spices and fresh herbs are added and blended until smooth. This spread is used on bread or savoury biscuits. Easy to prepare no-meat burgers are useful on their own or in buns. They require half a cup of sliced almonds, one teaspoon of salt, half a cup of carrots, one onion, five green chillies, finely chopped cilantro (or other herbs of preference such as celery or thyme) and two teaspoons of lemon juice. To prepare the burgers, the lentils are pressure cooked with a little water or cooked in water until tender; the water is then drained. Meanwhile, one teaspoon of oil is heated on a griddle and carrot, onions, chillies, cilantro and almonds are added. They are sautéed until the almonds are light brown and then cooled. The mixture is then transferred to a food processor, and the cooked lentils and salt added. The mixture is stirred several times, scraping the sides, until the mixture is coarsely ground. The mixture is then put in a bowl and lemon juice is added and mixed thoroughly. The lentil mixture is then formed into round patties. One teaspoon of oil or butter is then heated on a cast-iron griddle and the patties are added, cooked for 3–4 min on a medium low heat until light brown. The patties are delicate, so a large flat spatula is required to turn them. They are served hot between sliced buns with shredded cabbage, onion, tomato slices along with tomato ketchup and shredded cheese.

25.7. Processed Lentil Modern processing technology has allowed lentil to be used in a range of foods including bakery products, snacks, ready-mixes and ready-to-eat foods. Lentil being rich in protein is important to vegetarians and those allergic to dairy products (or on diets specifying reduction of dairy products) as an alternative source of protein. Papad, also known as appalam, is a popular snack item of India. It is consumed either as such after frying or roasting or as adjunct along with vegetable soups and curries. Papads are made from a blend of cereal flour, edible starch and pulse flour with common salt, spices, edible oil, alkaline and mucilaginous additives. The main varieties of papads are those made from spiced/un-spiced black gram, green gram, sago and potato. In northern India, papads are mainly prepared from black gram dal, blends of green gram and black gram dals and starch. Saxena et al. (1989) explored the possibility of preparing papads from blends of different dal (dehusked split pulses) flours with or without the addition of black gram dal. Blends of dal flours comprising black gram and chickpea (70:30), black gram + mung bean + lentil (60:25:15) and black gram with lentil (80:20) yielded papads with acceptable physio-chemical and organoleptic attributes. The papads prepared from the blend of black gram–mung bean–lentil (60:25:15) showed better colour, aroma, taste and texture. Vermicelli is prepared from refined wheat flours, lentil and pea flour made into a tough dough which is pressed through a vermicelli mould and dried. Singh et al. (2003) prepared vermicelli fortified with 20% malted lentil and 25% pea flour. The protein content increased to 14–16.7% as compared

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to the traditional vermicelli (11.5% protein). The author reported that incorporation of 25% malted lentil showed higher nutritional value with respect to vitamins and minerals. Lentil was used to develop low-cost food supplements for infant feeding along with other ingredients such as soybean, rice, wheat, chickpea and semolina and the formulation was found to be a very rich source of protein with high amounts of essential amino acids (Hegazy et al., 1989). A canned vegetable-mushroom mix was developed. The main ingredients of the product were grass pea (Lathyrus sativus) and lentil seeds, which were mixed with white button mushrooms (Agaricus bisporus) and oyster mushrooms (Pleurotus ostreatus). High temperature ensured the required seed softness and degradation of the non-nutritional substances. The canned food thus manufactured exhibited highly positive sensory properties, and was rated as 4.1–4.8 points on a five-point scale. The dry matter content of the canned food ranged between 20.6 and 25.5%, and the average protein, total carbohydrates, nutrient cellulose and ash contents were 5.8, 2.6, 1.8 and 1.3%, respectively (Kalbarczyk, 2003). Lentil loaf features a crunchy breadcrumb topping and is served with a savoury vegetarian gravy, mashed potatoes and peas. To prepare lentil loaf, two cups of lentils are cooked in boiling water until tender, which may take about 40 min. This cooked lentil is then combined with six small pieces of sliced white bread, two eggs, one cup of vegetable broth, two tbsp tomato paste, half a teaspoon of dried basil, quarter of a teaspoon of garlic powder, half a teaspoon of ground black pepper, one teaspoon of dried parsley, one tbsp of olive oil and a packet of dry vegetable soup mix. The mixture is then spread into a greased and preheated 25 × 15 cm loaf pan and baked at 205°C for 40 min. The dry breadcrumbs are then sprinkled over the loaf and baking is continued for another 10 min. This lentil bread has high contents of protein (15.4 g) and dietary fibre (12.2 g) as compared to wholewheat flour or refined flour bread.

25.8. Medicinal Uses of Lentil Lentil is also known to have medicinal value with complex carbohydrates that regulate the body’s metabolic system, help stop diarrhoea and are useful in treatment of constipation and other intestinal afflictions. The seeds are mucilaginous, rich in dietary fibre and laxative. They are easy to digest and help in formation of stools. Made into paste, lentils are useful as a cleansing application in foul and indolent ulcers. In India, lentil paste is poulticed on to the ulcers that follow smallpox, measles, chicken pox, rashes, boils and other slow-healing sores. In the Ayurveda system of medicine, the human system is divided into three components, that is humour of phlegm (khaff), bile (pitta) and wind (vayu), and it is believed that a balance of the three makes the person healthy. Lentil is believed to retain stools, is light for the digestive system and causes the formation of wind humour (flatulence) in the body. It eliminates the

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excessive humour of phlegm and bile from the body. It also cures fever. Roasted lentil seeds are ground to make flour and dissolved in fresh pomegranate juice. This solution stops vomiting caused by the above three humours in the body. Lentil is being used in beauty-care products. The water in which lentils are washed is rich in minerals and it is used as a face wash or hair rinse. Lentil paste is applied to pimples for an early cure and to remove pimple marks.

References Bhatty, N., Gilani, A.H. and Nagra, S.A. (2000) Nutritional improvement of Masor (Lens esculenta) by supplementation with different kinds of meat. Nutritional Sciences 3, 66–70. Camacho, L., Sierra, C., Campos, R.R., Guzman, C.E. and Marcus, W.D. (1992) Nutritional changes caused by germination of staple Chilean legumes. Archivos Latino Americanos de Nutricion 42, 283–290. Candella, M., Astiasaran, I. and Bello, J. (1997) Cooking and warm-holding: effect on general composition and amino acids of kidney beans (Phaseolus vulgaris), chickpeas (Cicer arietinum) and lentils (Lens culinaris). Journal of Agricultural and Food Chemistry 45, 4763–4767. Eggum, B.O. and Beame, R.M. (1983) The nutritive value of seed proteins. In: Gottschalk, W. and Muller, P.H. (eds) Seed Proteins – Biochemistry Genetics and Nutritive Value. J.W. Junk Publishers, The Hague, pp. 499–531. El-Rahman, H.A.A., Heikal, Y.A., Rasmy, N.M. and Idris, A.M. (1998) Influence of lactic acid fermentation on selected physiochemical characteristics of some legumes. Proceedings of Seventh Conference of Agricultural Development Research, Cairo, Egypt, 15–17 December 1998. Volume 3. Annals of Agricultural Science, Cairo Special Issue 3, 771–792. El-Zoghbi, M. (1998) Nutritional quality of some protein sources. Annals of Agricultural Science 36, 2329–2339. Ereifej, K.I. (1995) Preparation of acceptable traditional dehydrated lentil soup at small scale. Journal of Food Science and Technology 32, 486–488. Estevez, A.M., Castillo, E., Figuerola, F. and Yanez, E. (1991) Effect of processing on some chemical and nutritional characteristics of pre-cooked and dehydrated legumes. Plant Foods for Human Nutrition 41, 193–201. Garcia, B.J.L. (1991) Nutritional improvement of digosaccharides in lentils. Alimentaria 221, 71–75. Good Housekeeping Institute (1966) Good Housekeeping’s New Basic Cookery in Pictures. Lord. Ebury, London, 176 pp. Hegazy, S.M., Hussein, M.M. and Bressani, R. (1989) Nutritional quality of low-cost supplements for infant feeding. Egyptian Journal of Food Science 17, 1–13. Hernandez, I.M., Sausa, V., Montalvo, I. and Tena, E. (1998) Impact of microwave heating on hemagglutinins, tryspin inhibitors and protein quality of selected legume seed plant. Foods for Human Nutrition 52, 199–208. Hozova, B., Danisova, C. and Holotnakova, H. (1994) Group B vitamins is macrobiotic food. Potravinarske Vedy 12, 197–201. Hsu, D., Leung, H.K., Finney, P.L. and Morad, M. (1980) Effect of germination on nutritive value and baking properties of dry peas, lentils and faba beans. Journal of Food Science 45, 87–92.

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Indira Singari (2008) Available at: http://www.nandyala.org/mahandi/archieves/category/ lentils-andlegumes/masoor-dalT (accessed 17 December 2008). Kalbarczyk, J.W. (2003) Developing a recipe for a canned food mix of grass pea, lentil and mushrooms. Zywnosc 10, 72–81. Kowieska, A. and Petkov, K. (2003) Lentils (Lens culinaris Medic.). Estimation based on macro and microelements content. Zywienie Czowieka i Metabolism 3(3/4), 1012–1014. Naveeda, K. and Jamuna, P. (2006) Nutritive value and sensory profile of microwave and pressure cooked decorticated legumes (dals). Journal of Food Processing and Preservation 30, 299–313. Nezamuddin, S. (1970) Miscellaneous – Masur, Lens culinaris Medic. In: Kachroo, P. (ed.) Pulse Crops of India. Indian Council of Agricultural Research, New Delhi, India, pp. 306–313. Paliwal, V.K., Yadav, K.R. and Khirwar, S.S. (1987) Nutritive value of lentil (Lens esculenta Moench) chuni for cattle. Indian Journal of Animal Sciences 57, 1023–1025. Parihar, P., Mishra, A., Gupta, O.P. and Singh, A. (1996) Effect of cooking on limiting amino acid content of common pulses. Advances in Plant Sciences 9, 165–169. Pasantes, M.H. and Flares, R. (1991) Taurine content of Mexican beans. Journal of Food Composition and Analysis 4, 322–328. Porres, J.M., Lopez, J.M., Aranda, P. and Urbano, G. (2003) Effect of heat treatment and mineral and vitamin supplementation on the nutritive use of protein and calcium from lentils (Lens culinaris M.) in growing rats. Nutrition 19, 451–456. Pratibha, P., Mishra, A., Gupta, O.P., Rajput, L.P.S., Singh, A., Parihar, P. and Singh, A. (1999) Effect of cooking processes on nutritional quality of some common pulses. Advances in Plant Sciences 12, 15–20. Prodanov, M., Sierra, I. and Vidal, V.C. (1997) Effect of germination on the thiamine, riboflavin and niacin contents in legumes. Zeitschriff fuer Lebensittel Untersuchung und Forschung 205, 48–52. Prodanov, M., Sierra, I. and Vidal, V.C. (2004) Influence of soaking and cooking on the thiamin, riboflavin and niacin contents of legumes. Food Chemistry 84, 271–277. Raghuvanshi, R.S., Shukla, P. and Sharma, S. (1994) Nutritive quality and cooking time tests of lentil. Indian Journal of Pulses Research 7, 203–205. Russell, S. (1974) Cooking for Two. Octopus, London, 127 pp. Sanchez, C.C.P., Dewey, P.J.S., Solano, M. de L., Tucker, M. and James, W.P.T. (1994) The non-starch polysaccharides in Mexican pulses and cereal products. Journal of Food Composition and Analysis 7, 260–281. Savage, G.P. (1988) The composition and nutritive value of lentils (Lens culinaris). Nutrition Abstracts and Reviews 58, 319–343. Saxena, A.K., Kulkarni, S.G., Manan, J.K. and Berry, S.K. (1989) Studies on the blends of different pulses (Bengal gram, green gram, lentils and arhar) in the preparation of North Indian spiced papads. Journal of Food Science and Technology 26, 133–136. Shekib, L.A. (1994) Nutritional improvement of lentils, chickpea, rice and wheat by natural fermentation. Plant Foods for Human Nutrition 46, 201–205. Shekib, L.A., Zeoueil, M.E., Youssef, M.M. and Mohamed, M.S. (1986a) Formulation and properties of instant lentils rice blend (koshary). Alexandria Journal of Agricultural Research 31, 207–217. Shekib, L.A., Zeoueil, M.E., Youssef, M.M. and Mohamed, M.S. (1986b) Amino acid composition and in-vitro digestibility of lentil and rice proteins and their mixture (koshary). Food Chemistry 20, 61–67. Singh, A., Pandey, K., Vaidya, M. and Pandey, S. (2003) Quality attributes of vermicelli fortified with malted pulse flours. JNKVV Research Journal (India) 37, 35–39.

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26

The Impact of Improvement Research: the Case of Bangladesh and Ethiopia

Aden A. Aw-Hassan,1 Senait Regassa,2 Q.M. Shafiqul Islam3 and Ashutosh Sarker1 1International

Center for Agricultural Research in the Dry Areas (ICARDA), Aleppo, Syria; 2Oxfam America-Horn of Africa Regional Office, Addis Ababa, Ethiopia; 3Bangladesh Agricultural Research Institute, Joydebpur, Bangladesh

26.1. Introduction Global studies on the impact of lentil research have revealed the advances of lentil improvement research in developing countries (Aw-Hassan and Shideed, 2003a, b) and the spillover effect in developed countries such as Australia (Brennan et al., 2002). The first study covered seven developing countries (Bangladesh, China, Egypt, Iraq, Jordan, Pakistan and Syria) and showed that the diffusion of improved lentil cultivars was at its early stage, but steadily increasing. The authors estimated combined annual gross research benefits of US$7.7 million for 1997, with Bangladesh, Syria and Pakistan getting the highest gains in that order because of their large cultivated areas. The estimated overall adoption rate was 17%. The slow down in improved varietal diffusion to larger areas was attributed to external factors. These factors include: (i) the difficult nature of the production environment; (ii) high climate and soil variability, which limits the likelihood of a single cultivar to dominate large areas; and (iii) the inability of seed systems to get high quality seed to small farmers in marginal environments. The authors suggested that decentralized breeding with the strategy of adapting germplasm to the specific agroecological conditions of different subregions as one way to achieve higher varietal diffusion. Increased diffusion of improved cultivars of lentil also requires innovative ways to involve extension and seed systems in the technology development and transfer process. The second study examined the global impact of lentil research and specifically identified anticipated spillover benefits of lentil improvement research at the International Center for Agricultural Research in the Dry Areas (ICARDA) in terms of cost reduction for lentil growers in Australia. Such cost reductions are expected to result from yield increases attributable to germplasm development at ICARDA or acquired by ICARDA’s germplasm improvement programme and incorporated into genotypes that will be grown © CAB International 2009. The Lentil: Botany, Production and Uses (eds W. Erskine et al.)

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in Australia, or from particular resistances in the germplasm (Brennan et al., 2002). Overall, Australia was estimated to receive an average of A$4.9 (US$2.5) million annually from ICARDA’s research over 20 years. The same study estimated global annual average discounted benefits of A$17.5 (US$9.1) million from ICARDA’s germplasm improvement over 20 years, 2001–2021. But these studies mainly relied on secondary data and projected adoption levels, and lacked field-based adoption data. As a result the analyses were mostly ex ante providing estimates of potential impacts. These global studies also do not explain why adoption levels of new cultivars are low in less developed countries. In this chapter we present field-based evidence of adoption of improved lentil cultivars from two cases: Bangladesh and Ethiopia. Bangladesh and Ethiopia are low-income countries with high population density and incidence of rural poverty (41% of the population in Bangladesh and 23% in Ethiopia are living below US$1/day), the majority of whom depend on agriculture for their livelihoods. New crop cultivars and good management practices are required to increase productivity and income, and to improve the welfare of many rural households in these countries. Lentil is an important crop for the small-scale farmers of both countries. Bangladesh grows about 148,000 ha of lentils annually and Ethiopia approximately 82,000 ha. The people of both countries have strong traditions of food legume consumption, which is the main source of dietary protein. But yields are low with averages of 0.81 t/ha in Bangladesh and 0.66 t/ha in Ethiopia over the 2001–2006 period (FAO, 2008a), hence the potential for increasing productivity and farm incomes is substantial. The aim of this chapter is to determine the state of adoption of improved lentil cultivars in these two countries using survey data, analyse the factors constraining the diffusion of new lentil cultivars and estimate ex post economic impacts based on the adoption that has already taken place. We also aim to highlight the costs of the time lag in new lentil cultivar adoption. The chapter is organized in eight sections. The first section provides the background to lentil research and development, the second section introduces the study areas and the third section describes the household surveys. The fourth section provides estimates of the profitability of new lentil technologies and the fifth section documents the adoption of new lentil cultivars, which is followed by an analysis of the factors influencing adoption of new lentil varieties in the sixth section. The economic impacts of lentil improvement research as well as the methods used in estimation are discussed in the seventh section. Finally a discussion of results, their implications or lessons for research and extension are presented in the eighth section.

26.2. Research and Development Bangladesh The Bangladesh Agricultural Research Institute (BARI) has been engaged in lentil improvement since the 1980s. The development of high-yielding lentil

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cultivars with a short production cycle was adopted as a breeding strategy through the introduction of new germplasm from ICARDA. The early maturing germplasm of ICARDA was supplied through the International Nursery Network. These included segregating populations specifically created for Bangladesh using its elite landraces and parents of diverse origin (Sarker et al., 2004). This was a result of changes in ICARDA’s international lentil breeding programme to better serve the needs of the national programmes (Erskine et al., 1998). The change was towards a decentralized breeding approach where ICARDA develops segregating populations using parents from national programmes and incorporates improved agronomic traits. The targeted segregating populations were sent to Bangladesh for selections to be made under local agroclimatic conditions. The result of that effort was the release of high-yielding cultivars with high resistance to rust (Table 26.1). The research programme simultaneously included capacity building in the national lentil improvement programme through short- and long-term training and visits to international research centres. This research and capacity building programme was supported by the International Development Research Center (IDRC) and the Canadian International Development Agency (CIDA) of Canada and the Australian Centre for International Agricultural Research (ACIAR). The Food and Agriculture Organization (FAO) also provided technical support to BARI. The research programme covered a wide range of agronomic practices including on-farm seed priming, relay cropping, mixed and intercropping and disease management (Sarker et al., 2004). The lentil improvement programme in Bangladesh owes its success to its strong outreach strategy. The demonstration and dissemination of lentil technology including new cultivars, agronomic practices and disease management were conducted by extension staff (Afzal et al., 1999). This programme was implemented under a technology transfer programme called the Lentil, Black gram and Mungbean Development Pilot Project (LBMDP) launched in the 1996/97 cropping season and funded by the Government of Bangladesh from its own resources (Sarker et al., 2004). The programme coordinated a wide range of technology transfer activities including foundation seed production of new lentil cultivars, large-scale demonstration plots, assessment of varietal performance with farmer participation, free Table 26.1. The origins, characteristics and yield of new lentil cultivars in Bangladesh (Source: Sarker et al., 2004).

Cultivar ‘Uthfala’ (‘Barimasur-1’) ‘Barimasur-2’ ‘Barimasur-3’ ‘Barimasur-4’

Year of release 1991 1993 1996 1996

Origin Local selection ICARDA Local crosses ICARDA

Maturity (days)

100-Seed weight (g)

Yield (t/ha)

110 110 115 116

1.6 1.5 2.5 1.7

1.3–1.5 1.8 2.0 2.3

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distribution of seeds, fertilizers and other inputs, farmer training, organization of mobile workshops for researchers, extension staff and non-governmental organization (NGO) staff, field days, awards to the best farmers and extension workers, procurement of seed from farmers for next season’s distribution and popularization of technologies through national media, technical bulletins, leaflets, booklets and posters. This programme was carried out in collaboration with five major institutions led by BARI. These were the Bangladesh Institute of Nuclear Agriculture (BINA), the Directorate of Agricultural Extension (DAE), Bangladesh Shaik Mujibur Rahman Agricultural University (BSMRAU), Bangladesh Agricultural Development Cooperation (BADC) and local NGOs (World Vision, Ghoroni). As a result, from 1997 to 2003 the programme trained about 5740 farmers, over 2000 research and extension staff and conducted 49 field days with over 5000 farmers participating. It also conducted over 1100 field demonstrations covering 1548 ha in 12,400 farmers’ fields, and distributed about 4 t of certified seeds of the four new Barimasur cultivars (Sarker et al., 2004).

Ethiopia The Debre Zeit Agricultural Research Center initiated a lentil improvement programme in the early 1970s, with the focus on increasing yields, development of disease resistance and improvement of management practices. In recent years, quality aspects, particularly export-quality lentils, were added. In 1976, the Center took the responsibility of coordinating lentil research at the national level. Currently, research on lentil is being undertaken at Debre Zeit, Adet, Holetta, Sinana, Debre Berihan and Sirinka Agricultural Research Centers (Regassa et al., 2006). Since the 1970s the lentil research programme has collaborated with ICARDA’s Lentil Improvement Program. The national programme has benefited from the collaboration in human resources development, information exchange and acquisition of new germplasm and advanced materials for the breeding programme. This collaboration has so far led to the release of one regional and nine nationwide cultivars with their full management packages (Table 26.2). Among these cultivars are ‘Chekol’, ‘Chalew’, ‘Gudo’, ‘Adaa’, ‘Alemaya’, ‘Alemtena’ and ‘Teshale’. EL-142 was released through selection of germplasm from Ethiopia. In addition, the Ethiopian lentil improvement programme progressively improved non-yield attributes of lentil cultivars. For example, the seed size has increased from 1.5–2 g/100 seeds of the local cultivars to 4–5 g/100 seeds of the new cultivars. Productivity at the research farm has increased three- to fourfold (i.e. from 0.5–0.6 to 3–3.5 t/ha). Besides higher yields and rust resistance, some of these new cultivars also have other important attributes such as high efficiency of zinc accumulation. Since the late 1990s, the Debre Zeit Agricultural Research Center’s outreach and on-farm technology popularization programme has conducted on-farm trials and demonstrations of improved lentil production packages (improved cultivars and management practices) in lentil producing areas

Origin, characteristics and yield of new lentil cultivars and their recommended agroecological areas in Ethiopia. Adaptation zone Days to maturity

Variety

Source

Year of release

EL-142 R-186 NEL158 (‘Chalew’) NEL2704 (‘Chekol’) FLIP 84-78L (‘Gudo’)

Ethiopia ALADª ICARDA ICARDA ICARDA

1980 1980 1985 1994 1995

85–103 122–143 111–128 84–91 86–151

FLIP 86-41L (‘Adaa’) FLIP 89-63L (‘Alemaya’)

ICARDA ICARDA

1995 1997

86–157 81–136

FLIP 96-49L (‘Alemtena’) ICARDA FLIP 96-46L (‘Teshale’) ICARDA

2003 2003

81–115 97–129

Seed colour Brown Green Yellow Brown Reddish brown Grey Reddish yellow Grey Grey

Altitude (m above sea level)

Rainfall (mm)

Seed yield (kg/ha) Farmers’ ﬁelds

Research trials

Change (%)

1650–2000 1800–2400 1850–2450 1600–2200 1850–2450

400–600 500–1200 500–1200 400–600 500–1900

9–12 14–16 14–18 14–16 14–18

14–20 17–25 19–26 15–22 18–25

56–67 21–56 36–44 7–38 29–39

1850–2450 1650–2600

500–1100 450–1200

16–24 18–24

19–26 20–30

19–8 11–25

1600–2400 1800–2400

400–600 400–800

14–18 16–26

17–23 18–31

21–28 13–19

The Impact of Improvement Research: Case Studies

Table 26.2.

ªALAD, Arid Land Agricultural Development.

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particularly in Ada-Liban, Akaki, Gimbichu and Alam-Gena districts in east and south-west Shewa zones to promote technology adoption. The technologies were also promoted through the establishment of Farmer Research Groups (FRGs) in the Gimbichu, Ada-Liban and Alam-Gena districts who have taken part in evaluation and dissemination of seeds of released lentil cultivars. Seeds of improved cultivars have been distributed to FRG members so that these farmers help in further diffusion of seeds to their neighbours. This mechanism increased farmers’ access to information and evaluation of new cultivars. As a result, some farmers visited research centres and requested new seeds. In addition, the technologies have been demonstrated to farmers through extension activities of the regional agricultural bureaus. The on-farm research programme facilitated farmer-based seed multiplication and farmer-to-farmer exchange of new cultivars on a commercial basis. In this process researchers and the Ethiopian Seed Enterprise (ESE) experts provided technical support to ensure quality seed is produced by farmers, which led to the production of a significant amount of improved seeds. Gimbichu district is now considered as a major source of improved lentil seeds for growers in other parts of the country. After realizing the potential of new cultivars and the potential for expanding areas, pioneer farmers started producing seeds for sale to other farmers, because the formal seed system has no major involvement in lentil seed production. In 2004, one farmer produced 10 t of the cultivar ‘Alemaya’ and sold it to the ESE at Birr 4900/t1 and over the 3 years (2003–2006) more than 100 t of lentil seed was produced and sold either to ESE, agricultural offices or directly to farmers (Regassa et al., 2006). Data from field demonstrations in Ada-Liban, Lume and Akaki districts have shown that the adoption of the improved lentil package (cultivar and agronomic practices) increased lentil yields by about 60% (DZARC, 1995). The lentil demonstrations conducted in Ada-Liban, Akaki, Gimbichu, Enewary, Minjar and Tulu Bolo areas at different farmers’ fields showed that the improved lentil package performed better than the traditional practice in most of the cases by about 68% (Fasil and Kiflu, 2003).

26.3. Study Areas In Bangladesh, lentil is traditionally grown in the north, north-western and south-western parts of the country. The study was conducted in the lentil growing areas in the Gangetic floodplain. The districts of Jhinaidah, Chawadanga, Kustia, Meherpur, Magura, Jessore and Norail were included in the north-western part. In the south-western part, the districts of Rajbari, Faridpur and Madaripur were covered. In the northern region, which includes Pabna and Natore, lentil is intensively grown in multiple cropping systems. These are the traditional areas of lentil cultivation. The Comilla district, which is a non-traditional area for lentil, was also brought under lentil as a new crop in the production system.

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Lentil in Bangladesh is grown as a rainfed crop, but it is occasionally subject to waterlogging in low-lying areas if there is heavy winter rain. Lentil is usually grown as a sole crop, but also as an intercrop and in mixed cropping with mustard, linseed, sugarcane and wheat. In Ethiopia the study was conducted in the four districts of Akaki, Alam-Gena, Ada-Liban and Gimbichu in the central part of the country, which constitute the main lentil producing areas (Regassa et al., 2006). Lentil is the third most important crop among pulses after faba bean and chickpea in the area under study. The Ada-Liban district (woreda) is located in mid-highland with the mean elevation of 1900 m, annual precipitation over 800 mm, and has mainly vertisol (60%) and clay-loam (24%) soils. Lentil is in the fourth place in cultivated area after faba beans, field peas and chickpea. The Akaki district in the south-east of Addis Ababa is a highly urbanized district situated at an average altitude of about 2000 m and is dominated by vertisol soils (90%). Lentil is considered as a cash crop because growers have better access to markets. The Alam-Gena district at about 2100 m altitude is mainly covered with vertisol and alluvial soils. Lentil, grown on the residual moisture and in the Awash River floodplain when the water recedes at the end of rainy seasons, is the most important pulse crop. The Gimbichu district is located at an elevation of 2400 m. More than 50% of this area is classified as highlands with average annual rainfall of about 900 mm. Most soils (75%) are vertisols. Lentil is one of the important pulse crops grown in the district.

26.4. Household Surveys In Bangladesh a random sample of 125 lentil growers who participated in the demonstration blocks and 125 non-participants from the main lentil growing region of the country covering 13 pulse-growing districts (Madaripur, Rajbari, Faridpur, Magura, Jhinaidah, Chawadanga, Norail, Jessore, Kustia, Pabna, Meherpur, Natore and Comilla) was analysed in the 2003/04 cropping season to determine the adoption of new lentil cultivars. They were typical smallholder producers with average landholding of 1.4–1.5 ha, with 26–30% illiteracy rate (Table 26.3). The data collected included basic household asset data (land holding, education, etc.), adoption of new lentil cultivars, the area planted with new and traditional cultivars, yields, costs and their perceptions of the performance of the new cultivars. Farmers also indicated how they spent the additional income, if any, from adopting the new cultivar. In Ethiopia, a sample of 289 lentil growers was drawn by multi-stage random sampling from four main lentil-growing districts: Ada-Liban, Gimbichu district from East Shewa zone, Alam-Gena district from southwest Shewa, and Akaki district from Addis Ababa administration in the 2002/03 cropping season. Secondary data were also collected from Ministry of Agriculture, district offices of agriculture, the cooperative union and seed suppliers.

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A.A. Aw-Hassan et al. Table 26.3.

Sample farmers’ land holding and education levels in Bangladesh.

Item Land holding (ha)

Education (%)

Own land Rented in land Rented out land Mortgaged in land Mortgaged out land Total Illiterate or signature Primary Secondary SSCª and above

Adopters

Non-adopters

1.40 0.11 0.04 0.11 0.03 1.68 26 23 25 26

1.34 0.16 0.09 0.05 0.03 1.67 31 16 29 24

ªSSC, Secondary School Certiﬁcate

Table 26.4.

Landing and crop mix of sampled farmers in selected districts, Ethiopia. Crops (% area)

Study area Ada-Liban Akaki Gimbichu Alam-Gena All districts

Mean Sample holding size (ha) 50 47 99 93 289

1.5 3.01 1.7 3.04 2.31

SD

Barley

Tef

Wheat

Faba bean

0.50 1.22 1.05 1.04 1.23

0 1 1 1 1

28 46 18 50 41

42 22 49 13 26

5 0 4 1 2

Chickpea Lentil 13 17 11 17 15

9 5 14 10 10

Grass pea

Field peas

3 8 4 7 6

1 0 1 1 6

The surveyed farmers practise a mixed crop-livestock system with most households having at least one or more livestock species. The interdependence of crop production and animal husbandry is critical for livelihood in this mixed farming system. The average family size was about eight persons. Overall 38% of household heads were illiterate. This was higher in Ada-Liban (52%) and Akaki (43%) districts than in the other two districts, Alam-Gena (36%) and Gimbichu (19%). The study areas are typical of smallholder farming with overall average holding size of 2.31 ha, with AlamGena and Akaki farmers holding almost double the holding area of the other two districts (Table 26.4). As shown in Table 26.4, the main staple traditional food crop (tef) and wheat were given the highest priority in land allocation (over 40% and 26%, respectively) ensuring household-level food security. Chickpea was the second most important crop in the study area and lentil the third most important crop in terms of cultivated areas with 10% of the cropped area. The livestock in the mixed farming system are cattle, sheep, goats, donkeys, horses, mules and poultry. On the average, each family owned three or more oxen, which are an important power source for tillage. Livestock ownership was estimated at 7.36 tropical livestock units (TLU) in Ada-Liban,

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11.4 in Akaki, 8.1 in Gimbichu and 9.6 in Alam-Gena. The differences were significant.

26.5. Profitability of New Lentil Technology In Bangladesh, crop enterprise budget analysis shows that the surveyed growers adopting new lentil cultivars had increased their gross margins of return on land, labour and management by 120%, receiving Taka 15,576/ ha, compared to Taka 7096/ha by the non-adopters.2 The high financial benefits are a result of low additional costs typical of new crop cultivar adoption. These lentil growers reported that they mostly spent the extra income on clothing (68% farmers), food (62%), cultivation costs of other crops (62%), education (58%) and medicare (58%) (Table 26.5). They also spent extra income on rebuilding houses, and purchases of land and farm equipment. In the Ethiopian case, the gross margin per hectare for the cultivar ‘Alemaya’ was estimated at Birr 8238/ha,3 while the gross margin for the local cultivar was estimated at Birr 2881/ha, increasing lentil profitability by 186%. These estimates are based on data from demonstration farms which are monitored by extension staff and have applied recommended agronomic practices. Normally increase in farm profitability by new technologies would be lower than these figures as farmers generally do not apply optimal management practices, thus reducing their yields or increasing their costs of production, hence reducing their profits. Although national-level economic impacts are important, these farmlevel financial impacts of new crop cultivars have direct and immediate impact on the welfare of rural households that grow lentils. These immediate impacts on the livelihoods of rural households and the long-term effect on human development such as education and health and capital asset building, and the self-esteem gained and satisfaction from the sense of

Table 26.5. Utilization of additional income accrued from new lentil cultivars, Bangladesh. Items of expenditure Clothes Food Cultivation costs Education Medical Loan servicing Land, cattle or thresher House improvement Marriage of daughter Small business

Frequency

Farmers (%)

86 78 77 73 73 9 14 6 1 1

68.8 62.4 61.6 58.4 58.4 7.2 11.2 4.8 0.8 0.8

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achievement are, perhaps, the most important impacts of agricultural research that builds the foundation for sustainable livelihoods in the long term. The long-term outcomes of these intangible impacts are harder to assess.

26.6. Adoption of New Cultivars Bangladesh The total lentil area and areas of new lentil cultivars and number of growers participating in the demonstration programme and non-participants are shown in Table 26.6. The number of non-participating farmers growing new lentil cultivars increased from 0 to 47 during the period 1999–2002, giving an adoption rate of 38%. Clearly, these farmers adopted new cultivars after becoming aware of the new technology from other farmers who had participated in the demonstration programmes. Informal farmer-to-farmer exchange is the main source of new seeds and information in developing countries, and is key to the diffusion of crop cultivars (Aw-Hassan et al., 2008). The area of new cultivars increased from 191 ha in the 1998/99 cropping season to 10,908 ha in 2002. This is an impressive 24-fold increase. The adoption of Barimasur cultivars was accelerated by the technology transfer programme described above. The adoption rate (given as percentage of area cultivated) of modern Barimasur cultivars and local cultivars for 1998/99–2001/02 is presented in Table 26.7. The survey data show that the proportion of the area cultivated with new cultivars grew faster among farmers who participated in the demonstration blocks, increasing from 6% in 1998/99 to 63% in 2001/02 cropping season, compared to a rise from 0 to 24% for non-participants during the same period. This result shows the impact of the technology dissemination

Table 26.6. Total area cultivated in Bangladesh with modern lentil cultivars (Barimasur) by farmers participating in demonstrations and non-participants.

Cultivar category Modern cultivars

Local cultivars

Demonstration farmers Year 1999 2000 2001 2002 1999 2000 2001 2002

Number 4 42 118 106 37 92 68 61

Area (ha) 191 2,484 7,516 8,344 3,132 8,506 5,964 4,846

Non-demonstration farmers Number – 4 16 47 38 103 109 100

All farmers

Area (ha)

Number

– 183 855 2,564 3,359 9,055 9,783 8,074

4 46 134 153 75 195 177 161

Area (ha) 191 2,667 8,371 10,908 6,491 17,561 15,747 12,920

Cropping seasons 1998/1999 1999/2000 2000/2001 2001/2002 1998/1999 1999/2000 2000/2001 2001/2002 1998/1999 1999/2000 2000/2001 2001/2002 a MV,

Lentil cultivars Farmer group Demonstration participants

Non-participant farmers

All farmers

‘Barimasur-4’ ‘Barimasur-3’ ‘Barimasur-2’ ‘Barimasur-1’ 2 16 36 40 0 2 7 18 1 9 22 29

4 6 15 16 0 0 1 6 2 3 8 11

0 1 2 3 0 0 0 0 0 0.5 1 2

0 0 4 6 0 0 0 0 0 0 2 3

All MVa 6 23 56 63 0 2 8 24 3 13 32 44

Local cultivars 94 77 44 37 100 98 92 76 97 88 68 57

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Table 26.7. Area cultivated (%) with lentil cultivars among farmers participating in demonstration blocks and non-participants, in selected Bangladesh sites, 1998/99–2001/02.

Modern varieties.

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and extension programme. Clearly, ‘Barimasur-4’ which accounted for 67% of that adoption rate was the most favourite cultivar, followed by ‘Barimasur-3’ which claimed a quarter of the adoption rate. By 2002, all the surveyed farmers cultivated 44% of their lentil area with improved lentil cultivars. This rapid diffusion rate is a result of the success of the ICARDA–BARI collaboration in lentil breeding and developing new cultivars with clear productivity advantages, disease tolerance and other agronomic traits, and the effective multi-institutional technology transfer programme coordinated by BARI. Farmers’ reasons for preferring the Barimasur cultivars over the local cultivar are given in Table 26.8. The farmers who experienced these new cultivars are convinced of their advantages in terms of yield, seed colour, disease tolerance, grain size and straw yield, in that order. Farmers also used other indicators given in the table. Other studies have shown that farmers take several plantings to assess new germplasm in comparison with their own germplasm before they are convinced of the superiority of the new material (Aw-Hassan et al., 2008).

Ethiopia The overall adoption rate of new lentil cultivars among the surveyed farmers was 19%, with higher adoption rates in Ada-Liban and Gimbichu districts (Table 26.9). The most adopted was the cultivar ‘Alemaya’. After this survey was completed, a rapid increase in the area under ‘Alemaya’ was reported, particularly in Gimbichu district from 156 ha in 2003–2004 to 2460 ha in 2005 because of the high profitability of this technology (Regassa et al., 2006). However, most of this adoption is localized to a small part of the lentil growing areas. In fact, it is estimated that cultivar ‘Alemaya’ is the dominant cultivar in Gimbichu district covering 24% of the lentil area in 2004. The success of the Gimbichu district, none the less, was not repeated in other lentil growing areas and as a result, these estimates corresponded to only a 2.6% adoption rate nationwide in 2005.

Table 26.8. Bangladeshi farmers’ reasons for preferring Barimasur cultivars of lentil. Traits High grain yield Preferred seed colour Disease resistant Large grain size High straw yield Drought tolerant Good taste High price Short duration

Frequency

Percentage

121 114 114 112 73 32 18 9 6

99 93 93 92 60 26 15 7 5

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Table 26.9. Adoption rate of improved new lentil cultivars in different districts of Ethiopia, 2003. District Ada-Liban Number of farmers Adopters (%) Non-adopters (%) Total (%)a aThe

50 30 70 100

Akaki 47 11 89 100

Gimbichu 99 35 65 100

Alam-Gena 93 0 100 100

Total 289 19 83 100

small differences between Total (%) and percentage adoption is due to rounding error.

These low adoption rates are not surprising given that farmers have been largely unaware of the cultivars and extension services do not reach the majority of farmers. The extension services were weak as only 43% of the farmers reported they had contact with extension services at least twice in every 3 months, about 25% had no contact with extension services at all and the remaining had contact but over longer intervals. The farmers involved in demonstrations, on-farm trials and farmer research groups and training comprise only 6% of the sample. The inadequate extension services were reflected in the level of farmers’ knowledge about new lentil cultivars. Farmers who knew at least one of the improved lentil cultivars were estimated at 59% in Gimbichu, 49% in Ada-Liban, 36% in Akaki and 7% in Alam Gena. Almost all participants of extension activities were fully aware of the new cultivars, but the majority of the sample (94%) comprised nonparticipants and only about one-third (33%) of those were aware of the new cultivars. The most popular cultivars across all districts were ‘Alemaya’ (11.4%) and ‘Ada’ (4.8%). Other cultivars were not known to farmers. Farmers’ knowledge and evaluation of new cultivars through formal extension systems or through farmer-to-farmer exchange of seeds and information is the first critical step in the technology diffusion process. The outreach of extension services is essential to improve the level of farmer awareness of new cultivars.

26.7. Factors Influencing Adoption of New Lentil Cultivars Adoption of new crop cultivars mainly depends on their performance, profitability and feasibility within the farming system. Adoption also depends on both internal household factors and external factors. Internal factors include age, gender, education level, exposure to extension and research activities, and the level of entrepreneurship. Further, adoption of new crop cultivars is influenced by household-level resources (human, natural and physical assets) and social assets. These personal characteristics make an individual more or less conservative to new ideas, shape the person’s willingness to take risk and seek information making the person more or less knowledgeable of new farming technologies. External factors influencing

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technology adoption are institutions, services and markets that facilitate the flow of information, seeds and capital to farmers. Effective extension services and markets greatly influence the uptake of new crop cultivars and impact the well-being of producers and consumers. Analysis of how these factors influence adoption provides useful information that can strengthen knowledge transfer programmes and increase the likelihood of technology adoption, ultimately leading to improved food security, reduced poverty and improved rural livelihoods. This also increases the economic and social returns to public investment in research and extension. In Ethiopia the adoption analysis using the logit model showed that the gender of the head of the household, access to seeds of improved cultivars, participation in extension activities such as demonstration, verification trials, training and membership of a farmers’ research group significantly affected adoption of improved lentil cultivars (Table 26.10). Livestock ownership was also significant. Besides livestock ownership, all other variables had the expected direction of relationship with the dependent variable. The analysis indicated that male farmers had a higher probability of adopting improved lentil cultivars than female farmers. This is because men have better access to resources and information. Although education was hypothesized to positively affect adoption, no significant relationship was found between education and the adoption of improved cultivars. The other variables, which had a significant positive relationship with cultivar adoption were access to extension services and improved seeds. The households participating in verification and demonstration trials and training courses were members of the Farmers’ Research Group (FRG) and they had a higher probability of adoption. This indicates the crucial role that agricultural extension plays in promotion and popularization of technologies. The percentage of correct prediction by the model was 85%. Wider coverage of the extension service, mass popularization of the new cultivars and seed distribution are needed if the adoption rates are to be increased from these low levels. The major reasons these farmers do not use newly introduced cultivars are lack of information about the cultivars (42%) and source of seed (38%). Lack of information about the cultivars, seed sources and shortage of seeds were mentioned as causes of non-adoption by 86% of non-adopters. Table 26.10. Logit model coefﬁcients of factors affecting the adoption of improved lentil cultivars in selected sites in Ethiopia. Factor

Coefﬁcient

Standard error

t-ratioa

Gender of head of household Education Access to improved seed Access to extension services Livestock ownership

–1.56429 0.00077 0.00190 2.37721 –0.00100

0.18870 0.00156 0.00063 0.56547 0.00058

–8.299** 0.4942 3.0162** 4.2039** –1.7183*

aPercentage

of correct prediction = 85%,; *P<0.1; **P<0.05.

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26.8. Economic Impacts The economic impact of the adoption of new crop cultivars can be estimated with the economic surplus (ES) model (Alston et al., 1995). The model allows computing annual flows of research benefits and costs. The procedure requires data on yield advantage of new cultivars, adoption rates, change in cost of production due to the adoption of new cultivars, producer prices, and the demand and supply elasticities (price in response to supply and demand changes). The small open economy formulation of the ES model can be represented as: ΔES = PtQtKt(1 + 0.5Kte); Kt = [g/e - c/(1 + g)].At where Pt = prices in year t, Qt = production in year t, Kt = the supply shift down in year t as a proportion of the initial price, e = supply price elasticity, g = percentage yield increment of the new variety over traditional variety, c = proportion of production cost increase due to technology adoption, and At = adoption rate in proportion of areas under improved cultivars. Both Bangladesh and Ethiopia are considered as small economies since they are not globally dominant producers of lentils. The small open economy representation implies that international prices will not be affected by increased supply and domestic prices directly in relation to the international prices. In that formulation demand elasticities are not needed. The estimates and assumptions of the parameters in the above model are described next.

Production (Qt) and prices (Pt) In this study, we used the FAO production data for 1999–2006 (FAO, 2008a) and average production of the preceding 5 years for the period 2006–2013 (working on the basis that future production would be a similar average). Similarly, the cost, insurance, freight (c.i.f.) prices were taken from the FAO trade data FAOSTAT (FAO, 2008a) for the period 1999–2005 and the average prices of the preceding 5 years were used for the period 2005–2013.

Yields gains (g) In the Bangladesh case, average yields of new lentil cultivars and local cultivars in the fields of the farmers participating in demonstrations and the nonparticipants show a yield increase of 51% (non-participants) to 92% (participants) (Table 26.11). Under controlled conditions researchers reported a yield advantage of 20% for ‘Barimasur-2’ and 53% for ‘Barimasur-4’. A higher yield advantage of 77% of ‘Barimasur-4’, at 2.3 t/ha, over the improved local cultivar ‘Uthfala’ (1.3 t/ha) was also reported (Sarker et al., 1999). An average yield gain of 61% was estimated from the 5-years’ yield data (1998/99–2001/02) from the survey of farmers participating in extension demonstrations and non-participants (Table 26.11). In this analysis we used a

440

A.A. Aw-Hassan et al. Table 26.11. Average yields (kg/ha) of modern and local lentil cultivars for demonstration plots and non-demonstration farmers’ ﬁelds in Bangladesh, 1999–2002.

Variables Modern cultivars Local cultivars Difference (%)

Participant farmers

Non-participant farmers

All farmers

1097 572 92

967 641 51

1050 651 61

conservative estimate of half that yield gain (30%) of new Barimasur cultivars over the local lentil cultivar. The lower yield increase is assumed to account for average farmer practices that may not employ all the necessary agronomic practices and hence may not achieve the expected technical efficiency. In Ethiopia, average yields of 1.6–2.4 t/ha were reported for the ‘Alemaya’ cultivar compared to 0.6 t/ha for the local cultivar (Dadi and Bekele, 2003; also see Table 26.2). This very high yield advantage of over 100% is because the high rust resistance of ‘Alemaya’ allows it to be sown early in the rainy season taking full advantage of the rainfall, while the local cultivar has to be planted later in the season to escape rust infection but faces moisture stress, reducing yield significantly (Geletu Bejiga, personal communication). However, a yield advantage of 37% was estimated from the 2003/04 survey. We therefore used this conservative yield advantage in order to account for the non-optimal agronomic practices under farmers’ conditions.

Production cost changes (c) Any technological change involves change in production costs. Generally, improved agricultural technologies reduce production costs, but in some instances cost of production may increase due to additional inputs or operations needed to achieve full technology potential. In Bangladesh, the total variable cost per hectare increased by only 6% but average cost per tonne of output decreased by 13%. So no cost change was assumed for the Bangladesh case. This is a conservative approach and will in effect underestimate the research benefits. Similarly, in the Ethiopian case, the cost per hectare increased by 42% which was due to additional weeding cost, as mentioned earlier. But this amounted only to 6% increase in the cost of production per unit, which was used in the Ethiopian case.

Adoption rate (A) National level estimation of the research and extension impacts requires national level adoption data over time. Such data are seldom available. In Bangladesh, cultivar adoption rates were estimated from the 2003 farm

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survey. Since those estimates do not represent national level adoption rates we used four adoption scenarios (Table 26.12). In the first scenario, we used national level adoption estimates of 9% for the year 2003/04 and increased it to 10% annually until 2013. The 9% nationwide adoption rate is based on the estimates of agricultural offices for selected lentil growing areas. In the second scenario, we used the adoption rate of 25% which is close to the actual estimates of the 2003 survey for the non-participant farmers of the extension demonstration programme (24%) and projected forward until it reaches a 30% adoption ceiling. This scenario assumes a reasonably wellfunctioning extension programme facilitating information and material flow to farmers. This estimate is lower than the 60,000 ha (38%) estimated to be under new lentil cultivars in 2004 (Sarker et al., 2004). The third scenario is the same as the second except that a lag of 5 years in reaching the 25% adoption rate was introduced. In the fourth scenario we used the adoption rate of 45% which is close to the estimates from the 2003 survey for the whole sample (pooled average of the participants and non-participants 44%) and projected up to an adoption ceiling of 60%. This scenario assumes excellent extension and seed systems similar to the one implemented by BARI and partners, and explained previously in this chapter, which provide effective services to small-scale farmers. The adoption ceilings of less than 100% implies that the current cultivars may not fit in all the conditions of the lentil growing regions, or factors such as lack of seed and access to markets may limit the potential adoption of these cultivars. Again, this is a conservative approach. The four scenarios represent different intensity and effectiveness of technology transfer which results in different diffusion rates over time, and time lag in actual and potential technology adoption (ceiling) Table 26.12. Gross annual research beneﬁts for different scenarios of farmers’ access to seeds and extension services (average over 1999–2013), Bangladesh.

Scenario description 1. National level adoption estimates based on secondary data 2. Assumes modest nationwide extension programme similar to one BARI and partners implemented 3. Same as scenario 2 except the 25% adoption has a 5-year lag 4. Assumes effective nationwide extension programme

Adoption Adoption Year (%) ceiling ceiling 2003/04 (%) reached

Annual gross research beneﬁts (million US$) under three supply elasticity scenarios e = 0.5 e = 1.0 e = 1.5

9

21

2013

5.6

2.8

1.9

25

30

2007

11.5

5.7

3.8

9

30

2010

7.3

3.7

2.4

45

60

2008

21.9

10.9

7.3

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because of the manner in which the extension and seed systems reach out to small-scale farmers. In Ethiopia, as mentioned earlier, nationwide adoption estimates are not available. The adoption data available are localized to small parts of the country, making it difficult to extrapolate over the whole lentil growing area. Therefore, we used two scenarios; a low adoption rate scenario which is 3% of the lentil areas, and the second one which is higher with a modest rate of 25% to compute the forgone economic impacts or losses due to slow technology diffusion (Table 26.13). We limited the Ethiopian case to these two scenarios because of the limited adoption data. These two scenarios also represent different levels of extension activities and farmers access to information and seeds.

Supply elasticities Price supply elasticities for most agricultural commodities are expected to be greater in the medium- and long-term (Alston et al., 1995). To see effects of elasticity assumptions on the estimates of gross annual research benefits we considered three supply elasticity levels: 0.5, 1.0 and 1.5. These supply elasticities are within the range of generally reported commodity supply elasticities.

Estimates of economic impacts In the absence of accurate estimates of research costs we computed only gross research benefits. Zero increase in cost of production was assumed throughout the analysis because the new lentil cultivars do not require additional inputs to achieve the yield advantage used in the analysis. A 5% discount rate was used to compute the present value of research benefits and the estimates were deflated to maintain 2008 constant US dollars for all periods using the FAO price index (FAO, 2008b). In the Bangladeshi case, with low price supply elasticity scenario (e = 0.5), the gross annual economic impact of new (Barimasur) lentil cultivars was estimated at around US$5.6 million. This amounts to about US$84 million for the 15-year period of 1999–2013. In the second scenario assuming a relatively well-functioning nationwide extension programme with higher adoption rates of 25% (2004), the economic impact is estimated at about US$11.5 million annually. In the third scenario where the adoption was lagged for 5 years the impact of research benefits were estimated at US$7.3 million annually; and in the fourth scenario with a more optimistic nationwide adoption rate of 45%, which represents a situation with a highly effective nationwide extension programme, the economic impact of lentil technology is estimated at US$21.9 million annually. These results show the economic impacts of lentil technology and how those impacts can be affected by the effectiveness of technology transfer programmes.

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In the Ethiopian case, under the low price supply elasticities (e = 0.5), the gross annual research benefits for 2005 was estimated at US$0.33 million when the low adoption rate of 3% was used and these annual benefits increased to US$2.29 million annually with the higher adoption of 25%. This is a potential annual flow of research benefits (gross annual research benefits) since adoption still remained lower at national level. The results show an unrealized economic benefit of approximately US$2.0 million annually from research that has already generated profitable technologies which has been verified by extension work with farmers, but is not spreading rapidly enough. As shown in Tables 26.12 and 26.13, the estimates of the research benefits were sensitive to the price supply elasticities. These estimates, however, provide useful information for research administrators and policy makers to consider in allocating resources for research and extension.

26.9. Discussion and Lessons We have presented two cases (Bangladesh and Ethiopia) where poor smallscale farmers in developing countries have benefited from improved lentil cultivars using farm survey data. We selected these two cases among the poorest countries to highlight the importance of international and national public research for small-scale farmers in the less developed countries. Bangladesh and Ethiopia are both developing countries with a high concentration of small farmers and rural poverty. In both cases the new lentil cultivars, originating from ICARDA-developed germplasm, have proved to be superior to the local germplasm under farmers’ conditions in yield, disease resistance and other traits such as plant structure, seed size and colour. In both cases the technology has significantly increased the profitability of lentil production. The gross margins have consistently increased over 100% when the new package (modern cultivars and agronomic practices) was used. These results are based on demonstration plots and surveys of a sample of adopters and non-adopters of technology. Table 26.13. Gross research beneﬁts from lentil improvement in year 2005 for two adoption scenarios, Ethiopia.

Scenario Adoption estimates from 2003/04 survey and secondary sources Higher projected adoption assuming greater farmers’ access to information and seeds through more effective extension

Adoption area (%)

Gross annual research beneﬁt for year 2005 for three supply elasticity scenarios e = 0.5

e = 1.0

e = 1.5

3

0.33

0.15

0.09

25

2.29

1.07

0.66

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Similarly, in both cases the research programmes had clear outreach activities that initiate popularization of new lentil technology, albeit at different intensities and with varying performance. The Bangladeshi case had a more systematic outreach programme, which involved a number of institutions that participated in technology transfer, farmer workshops, demonstrations, farmer training, and seed production and distribution. There was much greater national commitment in technology promotion through the formal programme of the LBMDP launched in 1996/97. The programme was successful in increasing farmers’ awareness of technology and increased the area under new lentil cultivars by participants, non-participants and all farmers to 66%, 24% and 44%, respectively, in 4 years. The Ethiopian case had also an outreach programme, which was carried out by the Debre Zeit Agricultural Research Center’s Outreach and On-Farm Technology Popularization Program, involved FRGs and the ESE in several districts. The result was a significant increase in farmers’ awareness and adoption of the new technologies among farmers who were able to access information about the technology and seed through this programme. In this case, farmers who realized the benefits of the technology actively sought the new seed, and a local seed market of the cultivar ‘Alemaya’ started developing. However, the adoption rate of new lentil cultivars among the surveyed farmers remained low (19%) in 2004. None the less, a high adoption rate (24% of the lentil area) was reported but remained localized in small areas such as Gimbichu district. A number of important lessons can be learnt from these two cases. First, the outreach programmes were effective in increasing farmers’ awareness and adoption rates of technology. Without such efforts technology adoption will not occur. The importance of extension work was supported by the analysis of the constraints in technology adoption discussed previously in this chapter. It was demonstrated, using logit model analysis, that both access to information about the technology and seeds had significant effects on technology adoption. They were more important than farmers’ personal characteristics such as education, age and gender in influencing technology adoption. Second, the coverage of these farmers by participatory extension and research programmes was limited and, as a result, although adoption was high at the local level, it was still low at the national level. In both cases modest adoption rates of 24% (in area coverage) were estimated for the areas where the farmer outreach programmes were implemented, excluding the farmers who participated in the demonstrations. The coverage was much wider in Bangladesh where the programme had better resources. The strength of the Bangladeshi farmer participatory extension programme had almost doubled the adoption of the new cultivars (44%) taking the participants and non-participants together compared to the localized adoption rate in the Ethiopian example. Third, the economic impacts generated from these technologies both at the farm level and at the national level can be substantial, given the high acceptance by farmers of these technologies in both countries to the tune of

The Impact of Improvement Research: Case Studies

445

about US$11.5 million for Bangladesh and nearly US$2.3 million for Ethiopia annually using modest adoption rates of 25% in the both countries. However, there is a long time lag in lentil technology adoption. The three most popular cultivars, ‘Barimasur-4’ and ‘Barimasur-3’ in Bangladesh (1996) and ‘Alemaya’ in Ethiopia (1997), were released over 10 years ago. This time lag in adoption is largely due to the lack of an effective farmer participatory extension programme that can out-scale the local success of technology adoption. National institutions already have the capacity to implement such programmes as demonstrated in the two cases presented here. The policy commitment to support and implement such programmes as part of agricultural research and development is lacking. These policy and institutional failures have significant costs. The cost of the lag in lentil technology adoption could reach up to US$2.0 million annually in Ethiopia even using modest adoption targets of 25%, and in Bangladesh the adoption lag of 5 years at the same modest adoption rate could cost just over US$4.0 million annually (at the lower supply elasticity). Policy makers should consider these economic costs while supporting farmer-oriented extension programmes. Finally, the results presented above show that the ICARDA lentil improvement programme had yielded superior germplasm for Bangladesh and Ethiopia; the National Agricultural Research Systems (NARS) of the two countries have tested and adapted these germplasm to local conditions, leading to the release of new lentil cultivars in both countries. The full impact of this technology, however, requires vigorous farmer participatory extension programmes that can out-scale the adoption of such technologies without delay. Moreover, adequate monitoring of technology adoption is required both for evaluating the overall impacts of agricultural research and extension more accurately and for timely assessment of the effectiveness of extension programmes. The current global food price crisis is a clear warning that without adequate investment in such programmes that are so vital to modernize small-scale farming and to bridge the persistent yield gaps, the growth in food supply may not keep pace with demand, which could have serious social, economic and humanitarian consequences.

Notes 1. US$1 = 8.5 Birr in 2004, 9.09 Birr in 2008. 2. US$1 = 68 Taka (May 2008). 3. US$1 = 9.09 Ethiopian Birr.

References Afzal, M.A., Bakr, M.A. and Rahman, M.L. (1999) Lentil Cultivation in Bangladesh. Lentil Blackgram and Mungbean Development Pilot Project. Pulses Research Station, Bangladesh Agricultural Research Institute (BARI) Publication No. 18. BARI, Gazipur 1701, Bangladesh, 64 pp.

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A.A. Aw-Hassan et al. Alston, J.M., Norton, G.W. and Pardey, P.G. (1995) Science under Scarcity: Principles and Practice for Agricultural Research Evaluation and Priority Setting. CAB International, Wallingford, Oxon, UK. Aw-Hassan, A., Shideed, K., Sarker, A., Tutwiler, R. and Erskine, W. (2003a) The impact of international and national investment in barley germplasm improvement in the developing countries. In: Evenson, R.E. and Gollin, D. (eds) Crop Variety Improvement and Its Effect on Productivity: the Impact of International Agricultural Research. CAB International, Wallingford, Oxon, UK, pp. 241–256. Aw-Hassan, A., Shideed, K., Sarker, A., Tutwiler, R. and Erskine, W. (2003b) Economic impact of international and national lentil improvement research in developing countries. In: Evenson, R.E. and Gollin, D. (eds) Crop Variety Improvement and Its Effect on Productivity: the Impact of International Agricultural Research. CAB International, Wallingford, Oxon, UK, pp. 275–291. Aw-Hassan, A., Mazid, A. and Salahieh, H. (2008) The role of informal farmer-tofarmer seed distribution in diffusion of new barley varieties in Syria. Experimental Agriculture 44, 413–431. Brennan, J.P., Aw-Hassan, A., Quade, K.J. and Nordblom, T.L. (2002) Impact of ICARDA Research on Australian Agriculture. Economic Research Report No. 11. New South Wales Agriculture, Wagga Wagga, New South Wales, Australia. Dadi, L. and Bekele, A. (2003) Review of adoption and impact of improved food legume production technologies in Ethiopia. In: Food and Forage Legumes of Ethiopia: Progress and Prospects. Proceedings of Workshop on Food and Forage Legumes, 22–26 September 2003, Addis Ababa, Ethiopia. International Center for Agricultural Research in the Dry Areas (ICARDA), Aleppo, Syria. Debre Zeit Agricultural Research Center (DZARC) (1995) Forty Years of Research Experience: Debre Zeit Agricultural Research Center. DZARC, Alemaya University of Agriculture, Debre Zeit, Ethiopia. Erskine, W., Chandra, S., Chaudhury, M., Malik, I.A., Sarker, A., Sharma, B., Tufail, M. and Tyagi, M.C. (1998) A bottleneck in lentil: widening the genetic base in South Asia. Euphytica 101, 207–211. Fasil, K. and Kiflu, B. (2003) Agricultural technology transfer Ethiopia: the case of highland food legumes. Paper presented at the Second National Review Workshop on Food and Forage Legumes, 22–26 September 2003, Addis Ababa, Ethiopia. http://www.fao.org/worldfoodsituation/FoodPricesIndex/en (accessed 15 May 2008) Food and Agriculture Organization (FAO) (2008a) FAOSTAT Statistical Database of the United Nations Food and Agriculture Organization, Rome. Available at: http:// faostat.fao.org/site/567 (accessed 31 May 2008). Food and Agriculture Organization (FAO) (2008b) World Food Situation: High Food Prices. FAO Food Price Index. May 2008. Available at: http://www.fao.org/ worldfoodsituation/FoodPricesIndex/en/ (accessed 31 May 2008). Regassa, S., Dadi, L., Mitiku, D., Fikre, A. and Aw-Hassan, A. (2006) Impact of Research and Technologies in Selected Lentil Growing Areas of Ethiopia. Ethiopian Institute of Agricultural Research, Research Report No. 67. Ethipian Institute of Agricultural Research, Addis Ababa, Ethiopia. Sarker, A., Erskine, W., Hassan, M.S., Afzal, M.A. and Murshed, A.N.M.M. (1999) Registration of ‘Barimasur-4’ Lentil. Crop Science 39, 876. Sarker, A., Erskine, W., Abu Baker, M., Rahman, M., Afzal, M.A. and Saxena, M.C. (2004) Lentil Improvement in Bangladesh. A Success Story of Fruitful Partnership between the Bangladesh Agricultural Research Institute and International Center for Agricultural Research in the Dry Areas. APAARI publication: 2004/1. Asia-Pacific Association of Agricultural Research Institutions, 38 pp.

Index

Page numbers in bold type refer to figures and tables. Acidity, soil 201–202, 232–234 Acyrthosiphon pisum (pea aphid) 284, 290, 294, 314 Adaptations, for crop environments 44–45, 48–49, 58–59 Adoption rates, cultivar 105, 425, 434–438, 440–442 Agrotis ipsilon (cutworm) 282, 284, 295 Air screening 394–395 ‘Alemaya’ 430, 433, 436, 440 Alkalinity 54, 201, 203–204 Allergens 383 Allozyme 91 Alternaria alternate (Alternaria bight) 277 Altica coerulea 287 Amino acids composition, in lentil protein 370, 370 essential, human 370–371, 372, 408, 409 Alfalfa mosaic virus (AMV) 307, 308, 314, 315, 316, 318 Anatomy, lentil plant 43–44 Anthracnose disease 91, 268–269 Anti-nutrients 379, 380, 381, 382–383, 409 Antioxidants 380–381, 405

Aphanomyces euteiches (Aphanomyces root rot) 277 Aphids infestation 288, 290 insecticides 294, 297, 298, 319 natural enemies 294 pest species 283, 284 plant resistance to 292, 293 virus vectors 288–289, 314, 315 Aphis craccivora (cowpea aphid) 284, 288, 292, 294, 297 Apion sp. 283, 286, 288, 289 Archaeology, lentil distribution data 25, 27, 28, 29–30 Artichoke latent virus (ArLV) 307 Autographa gamma 282, 285 Ascochyta lentis (blight pathogen) 157, 263–264, 352 Aulacophora foveicollis 287

Backcross breeding 146 Bacterial diseases of lentil 277 Bagging, crop 259, 397 Balclutha sp. 284 Bangladesh cropping systems 430–431 cultivars 427, 434, 434–436, 435, 436 farmers 431, 432, 433 447

448

Index Bangladesh Agricultural Research Institute (BARI) 124, 271, 426–428, 436 ‘Barimasur’ cultivars 354, 427, 434–436, 436, 439–440 Bean common mosaic virus (BCMV) 307, 308 Bean leafroll virus (BLRV) 307, 308, 309, 314, 315 Bean pod mottle virus (BPMV) 307 Bean yellow mosaic virus (BYMV) 289, 307, 308, 310–311 Beet western yellows virus (BWYV) 306, 307, 308, 309, 315 Beetles (Coleoptera) 286–287, 311, 315 see also Bruchids; Sitona crinitus (pest weevil) Bemisia sp. 284 Biological control pests 294–296, 296, 299 weeds 331 Blight diseases Ascochyta 90–91, 263–264, 352 Stemphylium 91, 269–271 Boiling 411 Boron 53, 110–111, 198, 204 Botrytis spp. (grey mould pathogen) 56, 266–267 Branching pattern (of stems) 39–40, 40, 44–45 Breeding programmes aims 104, 107, 137–138 disease resistance 89–91, 111, 125, 148, 318–319 environmental tolerances 58–59, 104, 109–111, 149 food value enhancement 112, 113, 150–151 high seed vigour 353 mechanization, adapting to 111–112, 148 parasitic weed resistance 347–348 pest resistance 291–294, 298–299 short season crops 125–126 future prospects 116–117, 131–132, 147 genebank use 70–72, 104, 115–116, 139 methods 106, 108, 126–128, 131, 142–147 national 112, 114, 124, 151, 427

see also Improvement programmes, lentil Broad bean mottle virus (BBMV) 307, 308, 314, 315 Broad bean stain virus (BBSV) 289, 307, 308, 311, 315 316, 318 Broad bean true mosaic virus (BBTMV) 307, 315 Broad bean wilt virus-1 (BBWV-1) 307, 308, 314, 315 Broomrapes (Orobanche spp.) 344–345, 346–348, 355 Bruchids 282, 283, 286, 288, 292, 401 Bruchus lentis (seed weevil) 282, 283, 286, 295, 297 Bruchus ervi (seed weevil) 283, 286 Callosobruchus spp. 282, 283, 286 Brumoides suturalis 287 Bulk population breeding 106, 108, 128, 143–145

Calcium oxalate 44, 377 Camnula sp. 284 Canning 402, 421 Carbohydrates 371, 373, 373–374 Cercospora lensii (Cercospora leaf spot) 277 Chalky spot syndrome 283, 288, 401 Chickpea chlorotic dwarf virus (CpCDV) 307, 309–310, 315 Chickpea chlorotic stunt virus (CpCSV) 307, 308, 314, 320 Chickpea filiform virus (CpFV) 307 Chino del tomate virus (CdTV) 307 Chromatomyia horticola 282, 285 Chromosomes, structure 23, 92–93, 166 Cladosporium herbarum (leaf yellowing) 277 Cletus signatus 284 Climate effect on seed quality 353 for successful lentil growth 47–48, 216–217, 219–220 variability 49, 50, 182 Collections, lentil 64–68, 124–125, 139, 140 composite 67–68, 70, 159 Colletotrichum truncatum (anthracnose pathogen) 91, 268–269

Index

449 Colours flower 81 foliage 40–41, 77–78 seed 9, 43, 82–84, 86–87, 393 sorting machinery 396, 401–402 Combine harvesting 249, 258–259, 392 Conservation reserves 68 Consumption of lentils 10–12, 11 current trends 149–150, 404–406 traditional preferences 121, 139, 391, 396 see also Marketing Contarinia spp. 286 Cooking time 392, 402, 409, 416 Core collections see Collections, lentil Cotyledons 43, 44, 83, 86–87 Cover crops 241 Cropping systems 213–216, 430–431 double cropping 122, 215 integrated management strategies 176–180, 207, 298 intercropping 45, 122, 215–216, 240–241, 291 mixed cropping 215 monocropping 214 relay cropping 122, 216, 218, 220, 221 see also Rotation, crop; Summer crops; Winter crops Cross breeding as source of cultivars 36, 106, 115, 115–116 techniques 141–142 see also Recombination breeding Cucumber mosaic virus (CMV) 289, 307, 308, 311–312 Cultivars adoption rate 105, 425, 434–438, 440–442 disease-resistant (named) 89–91, 269, 271, 317–318 herbicide-resistant 57, 146, 158–159, 338, 347 micronutrient-dense 112, 113, 150–151 sources 48–49, 106, 115, 115–116, 128 types 138–139 variation in yield 217, 439–440, 440 see also ‘Alemaya’; ‘Barimasur’ cultivars; ‘Precoz’

Cuscuta spp. (dodder) 343, 346, 351 Cutter bars 255–257, 256, 257 Cutworms 282, 295 Cylindrosporium sp. (Cylindrosporium leaf spot) 277 Cyst nematodes 275–276

Dal 2, 102, 415–416, 419 Debre Zeit Agricultural Research Centre (DZARC) 428–430, 444 Decortication see Dehulling Deficiencies, soil mineral 53, 54–55, 198, 201–204, 234 Dehiscence, pod 35, 82 Dehulling 150, 383, 397–401, 405 Desiccation, chemical 57, 337, 393, 401 Destoning machines 395–396 Dhal mills 398–399, 405 Dietary allowances, recommended (RDAs) amino acids 371, 372 minerals 376, 377 vitamins 377–379, 378 Dietary fibre see Fibre, dietary Digestibility 381, 409, 411, 412 Diseases of lentil control methods 55, 56, 148, 317–320 effect on N-fixation 236 foliar 263–272, 277, 306–314 locally important 277, 314, 320 resistance 89–91, 111, 157, 166–167 seed-borne 263–264, 272–273, 316, 316 soil-borne 272–276 Distribution, geographical in archaeological remains 25, 27, 29–30 of L. culinaris varieties 26, 28–31 lentil pests 283, 284–287 of wild Lens spp. 22, 28–29, 68 Ditylenchus dipsaci (stem nematode) 275–276 Diversity, genetic 36, 67, 68, 159 Dodders (Cuscuta spp.) 343, 346, 351 Domestication of lentils 27, 28–31, 86, 103 Dormancy, seed 43, 86, 333, 335 Dosas 413, 419 Double cropping 122, 215

450

Index Drought tolerance 88, 110, 180–186 dehydration resistance 186 escape, by rapid growth 50–51, 181–182 morphological mechanisms 36, 182–183 physiological mechanisms 183–186 Dry-heat cooking 413 Dry matter accumulation 39, 172–173, 174–175 Drying, of harvested seed 224, 259, 394

Economic surplus (ES) model 439–442 Elasticities, supply 442 ELISA (enzyme-linked immunosorbent assay) 316–317 Emergence, crop 251, 352, 354 weed competition 326–328, 327, 328, 335 Empoasca sp. 284 Energy value 369, 374 Enzyme inhibitors 293, 382–383 Epilachna sp. 287 Erysiphe spp. (powdery mildew pathogens) 271–272 Ethiopia cropping conditions 431 cultivars 429, 436–438, 437, 438, 444–445 farmers 432, 432–433 lentil improvement programme 428–430 Ethiopian Seed Enterprise (ESE) 430, 444 Etiella zinckenella (pod-borer) 285, 290, 292, 295, 298 Eusarcocoris ventralis 284 Evapotranspiration (ET) 176–177, 214 Evolution 16, 30–31 Exports of lentil 9, 9, 138–139, 150 delivery systems 397 production systems for 356–357 Expressed sequence tag (EST) markers 157, 160, 162

Faba bean necrotic yellows virus (FBNYV) 307, 308, 310 FAO (Food and Agriculture Organization) 4, 427

Farmers access to seed services 438, 438, 441 income 426, 433–434 land holdings 356, 357, 431–432, 432 Research Groups (FRGs) 430, 438, 444 Fasciation 80 Fatty acids 374, 375 Fermentation 412, 419 Fertilizers application methods 205 cost/benefits analysis 55, 206–207, 221 and nitrogen fixation 195–196, 229, 234 recommended types 196, 197, 200 Fibre, dietary 374, 379–380, 403, 421 Fields, preparation 217–218, 249–251 Flatulence 371, 373, 374, 409 Flours, lentil 402, 420–421 Flowers 41–42, 81–82, 141, 173 flowering time 49–50, 123–124, 147–148, 181 genetic control 80–81, 108–109 Football lentils 150, 398, 401 Frankliniella spp. 287 Frost damage 48, 49, 52, 88, 396 Frying 412–413 Fusarium solani (Black root rot) 277 Fungal pathogens 263–275, 277 Fungicides 264, 267, 269, 273 Fusarium oxysporum (wilt pathogen) 272–273

Genebanks collection sources 64, 67–68 locations 64, 66, 67, 140 management 66–67, 68–69, 318 trait evaluation 69–70 uses of germplasm 70–72, 104, 115–116, 139 Genome sequencing 93, 157, 160–167 Germination 35, 43, 86, 352 advanced by seed priming 221 see also Sprouting Globe mutant 80 Graptostethus servus 284 Grasshoppers (Orthoptera) 283, 284, 294–295

Index

451 Gravity separation 395 Green manures 241–242 Greges 25, 26, 28 Grey mould disease 56, 266–267 Growth habit 34, 35, 39–40, 40, 77 adaptation to cropping conditions 44–45 and water deficit 127, 172, 184, 257 and weed competition 57, 334 Gypsum application 202, 203

Harvest area, world 5, 7–8 costs 111–112 handling damage 394 index 175, 176, 180 interference by weeds 327 machinery 255–257, 257, 258 importance of cleaning 332 methods 57, 223, 249, 253–260, 254 timing of 353, 401 Height, plant 38–39, 79, 148 Helicoverpa armigera (pod-borer) 285, 290, 291, 295–296, 297 Helminthosporium sp. (Helminthosporium leaf spot) 277 Herbicides pre-harvest application 337, 393, 401 resistance in weeds 332–333, 337, 338 resistant lentil cultivars 57, 146, 158–159, 338, 347 weed control 57, 250, 336–337, 346–347 Heterodera ciceri (cyst nematode) 275–276 History, lentil cultivation 1, 13–14, 29–30, 47, 103 Hoeing, hand 253, 334–335 Hybridization barriers 21–24, 294 Hypera postica 287, 293

ICARDA (International Centre for Agricultural Research in Dry Areas) collaborative links 114, 115–116, 151 collection sources, lentil 64–66, 65

genetic diversity analysis 159 lentil improvement programme 103–104, 105–106, 445 supply of genetic resources 67, 112, 149, 425–426, 427 wild Lens spp. collected 64–66, 66 Immunoassays, for virus detection 316–317 Imports of lentil 10, 10–11 Improvement programmes, lentil developed countries 142 Ethiopia 428–430 ICARDA 103–104, 105–106, 445 South Asia 108–109, 124, 131, 427–428 Indent cleaning 395 Infrared drying 402 Inoculants, rhizobial 205, 206, 235, 236–239, 355 Insect pests see Pests, insect Insecticides 294, 296–298, 299, 319 Intercropping 45, 122, 215–216, 240–241, 291 International Centre for Agricultural Research in Dry Areas see ICARDA Iron content, in lentil cultivars 112, 113, 150–151 deficiency, soil 54–55, 198, 203–204 Irrigation effect on crops 45, 51, 179, 222–223 as weed source 332

Karyotypes, Lens spp. 21, 23, 92–93 Khichri 103, 416–417

Labour costs 56, 57, 248–249, 255 Landraces 30, 49–50 preservation 67–68, 70 as source of cultivars 115, 115, 128 Laphygma exiqua 285 Laspreyresia (pod borer) 285 Leaf miners 283, 286, 291, 295, 297 Leafhoppers 308, 310, 315 Leaflets 41, 78 Leaves 40–41, 44, 77–78, 182 diseases of 263–272, 277, 306–314 pest damage 283, 288, 295

452

Index Lectins 293, 383 Lens culinaris, regional varieties (greges) 25, 26, 28 Lentil, Black Gram and Mungbean Development Pilot Project (LBMDP) 427–428, 444 Lentil yellows disease 289, 309 Leveillula taurica (powdery mildew pathogen) 271–272 Liming, effects on soil 201–202, 202 Limiting factors, to lentil growth 2, 104, 122–123 Linkage mapping 132, 151, 162, 162–163, 164 disease resistance 90, 91, 145 see also Markers, genetic Liriomyza sp. (see Leaf miners) 286, 295 Livestock, uses of lentil for 13, 138, 397 Lodging 57, 148, 248 Lygus bugs 283, 284, 288, 290, 297, 401

Macrophomina phaseolina (dry root rot) 277 Macrosiphum creelii 284 Malnutrition 11–12, 377 Manures farmyard 200, 273 green 241–242 weed seed elimination 331–332 Markers, genetic molecular 88, 159–163, 165, 299 expressed sequence tag (EST) 157, 160, 162 SSR (microsatellite) 70, 132, 159–160, 161 morphological 163–164 in taxonomy 18–21 use in selection 165–166, 167 Marketing in developed countries 356, 404–406 enhanced cultivars 112 farmer involvement 360, 363–364 lentil type classes 138–139, 351 see also Consumption of lentils Masur (lentil) 415, 416, 418 Maturity, time to 34, 48–49, 116, 181–182 Mechanization field preparation 249–251

harvesting 57, 111–112, 249, 255–260, 257 processing 398–400 seed cleaning 351, 392, 394–396 seeding 251–252 weed control 252–253, 253, 334–336 worldwide extent 248, 356, 357, 359 Medicine, uses of lentil in 13, 421–422 Mediterranean environments 50, 52, 176–177 Melanoplus sp. 283, 284 Meloidogyne spp. (root-knot nematodes) 275–276 Microarrays, in gene expression study 156–157, 157–159 Microbes, soil 236, 241, 273 Micronutrients, soil 197–198, 199, 234 Micropropagation 158 Microsatellite markers see Simple sequence repeat (SSR) markers Mildew, powdery 91, 271–272 Milling effiency 398, 401 Minerals, essential (in diet) 374, 376, 376–377, 377 Mixed cropping 215 Mjeddarah (mujaddarah) 2, 103, 417 Moisture content, seed 353, 354, 393–394, 400 Molybdenum 198, 201 Monocropping 214 Morphological characteristics of Lens spp. 15–16, 17, 34–35 Mujaddarah (mjeddarah) 2, 103, 417 Mutations, induced 76–77, 80 for breeding 108, 131, 145–146, 294, 347 Mycorrhizas, arbuscular (AM) 204, 206, 236 Myzus persicae 284, 289, 298

Nematode pathogens 275–276, 277 Nezara viridula 284 Nitrogen fixation 175, 184, 229–234, 231, 242 requirements 195–196, 199 see also Rhizobia, symbiosis with lentil No-till systems 218, 239–240, 249, 250, 336 Nodules, root 37, 38, 175, 235–236, 239

Index

453 Non-governmental organizations (NGOs) 363, 428 Nucleic acid-based assays, for virus detection 317 Nutritional value of lentils (human) 10, 12, 369, 404–405 after food preparation 409, 410–413 carbohydrates 371, 373, 373–374 dietary fibre 374, 379–380, 403, 421 energy 369, 374 fats (lipids) 374, 375 minerals 112, 374, 376, 376–377, 377 proteins 87–88, 369–371, 370, 372, 408 vitamins 377–379, 378, 412

Oligosaccharides 371, 373, 374, 379 Ophiomyia phaseoli 286 Origins, of cultivated lentil 25–31 Orobanche spp. (broomrapes) 344–345, 346–348, 355 Osmotic adjustment (OA) 184–185, 185 Outreach programmes 427–428, 436, 437, 444–445

Packaging 397, 402 Parasites, lentil bacteria 277 fungi 263–275, 277 nematodes 275–276, 277 viruses 306–314, 307, 308 weed plants 253, 329, 333, 343–348, 351 Parasitoids 294–296, 296 Partitioning, of assimilate to seeds 44, 184 PCR (polymerase chain reaction) 317 Pea aphid (Acyrthosiphon pisum) 290, 294, 314 Pea enation mosaic virus-1 (PEMV-1) 306, 307, 308, 312–313, 314, 315 Pea seed-borne mosaic virus (PSbMV) 91, 289, 306, 307, 308, 313, 315 Pea streak virus (PeSV) 306, 307, 308, 313–314, 315 Peanut stunt virus (PSV) 307 Pedigree selection 145 Peronospora lentis (downy mildew) 277 Pesticides see Insecticides

Pests, insect biological control 294–296, 296, 299 chemical control 294, 296–298, 299, 319 effect on N-fixation 236 host resistance 291–294, 298–299 monitoring methods 290 species 282–288, 284–287 as virus vectors 288–289, 307, 314, 315, 319 Phenolics 380, 380–381, 383 Phoma medicaginis (Phoma leaf spot) 277 Phosphates deficiency, and nitrogen fixation 199, 234 fertilizers 195, 196–197, 204–205 Photoperiod, flowering response 49–50, 123, 181 Photosynthesis, rate of 183–184 Phyllotreata chotanica 287 Phytate 382, 409 Phyto-oestrogens 381–382 Piezodorus rubsofasciatus 284 Pod borers 283, 284, 288, 291, 298 see also Etiella zinckenella; Helicoverpa armigera Pods 36, 42, 44, 77–78, 82 dehiscence 35, 82 effect of water availability 173, 173 Polishing 401, 416 Pollination 41–42, 141 Polysaccharides 373–374, 409 Potassium 197, 203, 206 Powdery mildew disease 91, 271–272 Pratylenchus spp. (root-lesion nematodes) 275–276 ‘Precoz’ 39–40, 49, 89, 108–109, 131 Priming, seed 221, 354 Processing, lentil by-products 397, 405, 409 for consumption 383, 391, 420–421 post-harvest 224, 392 primary 391, 392–397, 393 secondary 391, 397–403, 400 tertiary 391, 403 Production of lentil costs 205–207, 248, 260, 359, 440 geographical distribution 5–8, 6, 7–8, 350, 355–356 global amounts 4, 5, 103, 121–122, 403

454

Index Production of lentil continued integrated management practices 223, 263–264, 265, 267, 319–320 see also Cropping systems Productivity see Yield, lentil crop Profitability, lentil crop 59, 356–357, 398, 403, 433–434 Proteins 87–88, 369–371 see also Amino acids Pseudomonas radiciperda (Bacterial root rot) 277 Pubescence 16, 38, 41, 79 Pulses, global production 4, 5, 9, 404 Pure line selection 106, 128, 142 Pythium ultitmum (Pythium root and seedling rot) 277

Quail pea mosaic virus (QPMV) 307 Quality control, seed 350–354, 355 Quantitative trait loci (QTL) 70, 132, 162, 164, 167

Rabi crops see Winter crops Rainfall 50–51, 176–177 Raised bed planting 220–221, 222 Recipes, lentil 413–420 Recombination breeding 128, 131 Red clover vein mosaic virus (RCVMV) 307 Relay cropping 122, 216, 218, 220, 221 Research benefits 425–426, 439, 442–443, 443 funding sources 152, 356 Residues, crop 200–201, 240 Rhizobia, symbiosis with lentil 55, 229, 233, 235–239 Rhizoctonia solani (wet root rot) 277 Rice, cropping patterns with lentil 214, 215, 216, 218 Rolling 251–252 Root-knot nematodes 275–276 Root-lesion nematodes 275–276 Roots anatomy 43 diseases of 272–273, 275–276, 277 growth patterns 36–37, 37, 182–183 induction 158 nodulation 37, 38, 175, 235–236, 239

parasitic weed infection 344–345, 347 Rotation, crop disease control 269, 276 soil nitrogen benefit 241–242 and weed growth 333, 334 Rotylenchulus reniformis (reniform nematode) 277 Row spacing, lentil crop and mechnical weed control 334–335 optimum 215–216, 221 Rust disease 89, 264–266, 440

Salad, lentil 403, 414 Salinity, soil 53–54, 110, 202–203, 232 Saponins 382 Sclerotinia sclerotiorum (stem rot pathogen) 273–275 Sclerotium rolfsii (collar rot) 277 Screening, field (of genotypes) 90, 111, 126, 144, 147 Seedbed preparation 217–218, 239, 249–251 Seedcoat chemical composition 84–85, 380 colour 9, 43, 82–84 compared to cotyledons 408 hardness 86, 353 pattern (spotting) 85, 139 physical damage to 353, 394 thickness/structure 44, 398, 399 see also Dehulling Seeding see Sowing Seedlings, diseases of 266–267, 275–276, 277, 352 Seeds 36 chemical treatment 355 cleaning 391, 392–396 disease transmission 263–264, 272–273, 316, 316 effect of water availability 173, 173–175, 174 inoculation with rhizobia 202, 203, 237–239, 355 moisture content 353, 354, 393–394, 400 non-nutritive components 379–383 nutritional composition 368–379, 369

Index

455 of parasitic weeds 333, 345, 346 pest damage 224, 283, 288, 395, 401 priming 221, 354 quality 350–354, 355 genotype purity 351, 352–353 health 351, 352 vigour 351, 352, 353, 354 weed seed contamination 327, 331, 351 sizes, variation in 35, 42–43, 85–86, 187 supply 358 farmer-based 360, 361–364, 362, 430, 434 formal/commercial 152, 356, 358, 360 informal/non-commercial 360 see also Cotyledons; Seedcoat Selection, marker-assisted (MAS) 165– 166, 167 Simple sequence repeat (SSR) markers 70, 132, 159–160, 161 Single seed descent (SSD) 145 Sitona sp. (weevil) 116, 282, 283, 287, 288, 289, 292, 293, 296 nodule damage 37, 236 Sizing, seed 395, 396 Smynthurodes betae (root aphid) 284 Snacks, lentil 402, 418–420 Soaking (pre-cooking) 409, 411 Sodicity, soil 54, 203–204 Soil diseases carried by 272–276 evaporation 176, 177 health, contribution of lentils to 214, 232–242, 233 inoculation with rhizobia 234, 235, 236–239 nitrogen content 230–234, 241–242 nutrients availability, and pH 201–202, 202, 217 deficiencies 53, 54–55, 198, 201–204, 234 removal by seed crop 195, 197 status improvement 198–201, 204–206, 214 toxicities 52–54, 110–111, 201–204, 232 types 36–37, 52–55, 88–89, 217 Soup, lentil 2, 13, 414–415, 415

South Asia cropping systems 122, 213–214, 215–216 pilosae landrace 108, 121 recent cultivars released 129–130 yield constraints 122–123 see also Bangladesh Sowing depth 221, 334 equipment 251 rates 178, 220, 251, 334 row spacing 42, 215–216, 221, 334 timing of 56, 123–124, 177, 218–220 to avoid infestations 291, 333 see also Seedbed preparation Soybean dwarf virus (SbDV) 307, 308, 314, 315, 318 Species of Lens geographical distribution 22, 28–29, 68 in ICARDA collections 64–66, 66 taxonomic status 16–24, 19–20 Splitting 399, 400, 401 Spodoptera sp. 280, 285 Sprouting 409, 411–412, 418, 419–420 Starch 44, 369, 373–374, 403 Stem nematodes 275–276 Stem rot disease, Sclerotinia 273–275 Stemphylium botryosum (blight pathogen) 269–271 Stems 38–40, 44, 80 branching pattern 39–40, 40, 44–45 diseases of 263–264, 268–269, 273–275, 277 height 38–39, 79, 148 see also Growth habit Stipules 24, 40, 80 Stomata 44, 183, 270 Storage conditions 66–67, 392–394 pests 224, 283, 395, 401 Straw, lentil 248, 255, 259 Stubble burning 335 standing, protective function 149, 336 Subsistence crop, lentil as 195, 356, 357 Subspecies of Lens culinaris geographical distribution 26, 28–29 taxonomic status 24–25

456

Index Subterranean clover stunt virus (SCSV) 307 Sugars 371 Summer crops 48, 219 Swathing 257–258, 337, 401

Tagine, lentil 414 Tannins 85, 381, 408 Taxonomy 15–25 Technology transfer see Outreach programmes Temperature effects on seed yield 51–52 flowering response 49–50, 124, 181 Tendrils 31, 40, 78–79 Testa see Seedcoat Thielaviopsis basicola (black streak root rot) 277 Threshing 255, 259, 260 Thrips 41, 282, 283, 287 Thysanoplusia oricholcea 285 Tillage choice of techniques 218, 249–250 effect on weeds 335, 336 effects on soil health 239–240 Tobacco streak virus (TSV) 307 Tomato black ring virus (TBRV) 307 Tomato spotted wilt virus (TSWV) 307, 308, 314 Tomato yellow leaf curl virus (TYLCV) 307 Toxins, seed 383 Traits for agroecological regions 44–45, 107 correlation with yield 126–127 evaluation, for genebank database 70–72 selection, in breeding programmes 114, 143–144, 147–151 Transformation, genetic 116–117, 157–159 Transpiration 176, 181, 185–186 Trichoplusia ni 285 Turnip mosaic virus (TuMV) 307 Tychius quinquepunctatus 287, 288

Uromyces viciae-fabae (rust pathogen) 264–266

Uses of lentil 1–2, 213, 410 animal feed 2, 13, 138, 397 food (human) 102–103, 402–403, 409–410, 413–421 medicinal 13, 421–422 processing by-products 397, 405, 409 Utera cropping see Relay cropping

Variation environmental 38–39, 40–41, 58 genetic 69–70, 121, 125, 127 quantitative 86, 88, 162 see also Diversity, genetic Varieties, historical records 13–14 Vectors, of virus diseases 288–289, 307, 314, 315, 319 Vegetable, lentil as 417–418 Vicieae, genera 14–16, 68 Village-based seed enterprises (VBSEs) 361–364, 362 Viruses, lentil control 317–320 detection 316–317 disease transmission 288–289, 314–316, 315, 316 geographical distribution 308 species 306–314, 307, 320 Vitamins 377–379, 378, 412

Water availability deficit effects 127, 172–175, 173, 174, 180–186 management of 222–223 see also Irrigation; Rainfall Water use efficiency (WUE) 50–51, 176–180, 178, 179 Waterlogging 51, 54, 217 Weeds control methods 253 biological 331 chemical 57, 250, 336–337, 346–347 cultural 56–57, 333–334 integrated 337–338, 346 mechanical 252–253, 334–336 preventive 331–333 effect on N-fixation 236 effect on yield 223, 326–328, 327, 328, 329

Index

457 as pest hosts 291 seed viability 331, 333, 335, 336 sources 331–333 species 328–329, 330, 343–345 Weevils see Sitona crinitus (pest weevil) Wild Lens taxa 16–24, 64–66, 68, 82 Wilt disease, Fusarium 90, 272–273 Winter crops post-monsoon 47–48, 116, 214–216 temperate zone 34, 47, 109–110 Winter hardiness 52, 88, 109–110, 116

effect of weeds 223, 326–328, 327, 328, 329 global and regional 6, 6–8, 7–8 limiting factors 2, 104, 122–123

new and local cultivars compared 439–440, 440 pest infestation losses 283, 288 and soil nutrient status 54, 195, 197 stability 58, 123 and water use efficiency 50–51, 176–178, 178, 180

Xanthomonas sp. (Bacterial leaf spot) 277

Yield, lentil crop effect of inoculation 237 effect of seed priming 221, 354 effect of sowing time 218–219

Zero tillage see No-till systems Zinc content, in lentil cultivars 112, 113, 150–151 deficiency, soil 55, 198, 203