Securing the Harvest: Biotechnology, Breeding and Seed Systems for African Crops

Acknowledgements

This book grew out of a 2-year ‘exploration’ conducted by the Food Security theme of The Rockefeller Foundation focusing on the potential for crop genetic improvement to contribute to food security among rural populations in Africa. The exploration carried the authors to ten countries of sub-Saharan Africa and a number of related national, regional, and international meetings on several continents. Along the way, innumerable individuals – farmers, researchers, seed merchants, policy experts and others – contributed their views, comments and experiences related to crop improvement in African agriculture, and the authors are very grateful for their assistance. In particular, we would like to thank Foundation colleagues Gordon Conway, Bob Herdt, John Lynam, John O’Toole and Ruben Puentes for reading through the manuscript and sharing their views. David Jewell and Gebisa Ejeta also read early drafts and gave useful comments. In addition, we would like to express our gratitude to the following individuals who assisted with the study by sharing their views and providing information: Marianne Banziger, Jeffrey Bennetzen, Malcolm Blackie, Ronnie Coffman, Joel Cohen, Ken Dashiell, Alfred Dixon, Peter Ewell, John Hartmann, Tom Hash, Dave Hoisington, Lee House, Justice Imanyowa, Jane Ininda, Saleem Ismael, Monty Jones, Richard Jones, Bill Kiezzer, Laurie Kitch, Jenny Kling, Dennis Kyetere, Isaac Minde, Larry Murdoch, Patricia Ngwira, Hannington Obiero, Joseph Ochieng, Moses Onim, James Otieno, Yvonne Pinto, Kevin Pixley, Fred Rattunde, Darrell Rosenow, B.B. Singh, B.N. Singh, Elizabeth Sibale, Ida Sithole, Margaret Smith, Aboubacar Toure, Lamine Traore, Wilberforce Tushemereirwe, Eva Weltzien and John Whyte. Finally, we would like to express our sincere appreciation to Sarah Dioguardi and Mulemia Maina, who provided excellent care and technical assistance in preparing the manuscript. Inevitably, when attempting to address as broad a range of issues as biotechnology to seed production in a number of important crops, mistakes and discrepancies will occur, both in terms of the facts gathered and the assertions made. Although the authors have tried to avoid these, they apologize in advance for those that remain, and take full responsibility for them. ix

9

A4138:AMA:DeVries:First Revise:15-Oct-01

Prelims

Executive Summary

Food crops grown under low-input, rain-fed conditions in sub-Saharan Africa are affected by a wide range of biological and environmental constraints, but remain the best, if not the only, means of improving food security among the rural poor. To reach maturity and yield well, crop varieties must be able to resist or tolerate these stress factors. Due to wide variation in environmental conditions over space and time, the particular set of constraints which operate in any given area is continually changing. Moreover, local processing and consumption needs often exert additional quality requirements in order for improved crop varieties to be adopted by small-scale farmers. To be successful, breeding programmes for Africa must take into consideration this variation and relevant varietal preferences of farmers. By analysing these requirements, selecting appropriate parental materials, and making selections under relevant local conditions with regular farmer input, new varieties with the right combination of genetic resistances and tolerances can be produced. This kind of approach differs significantly from the methodology of selecting for high yield potential and broad adaptation which continues to give good results in more stable and more highly modified agricultural environments such as those in developed countries and the irrigated regions of developing countries. The major implication is a need for more localized, ‘agro-ecology-based’ breeding programmes, where the principal objective is to assemble a set of traits that reduce yield losses and thereby confer greater yield stability. Over time, yield-enhancing genes may still be added and make a significant contribution to overall performance, but the emphasis during the current phase of breeding programmes should be placed on critical resistance factors. The need to develop a range of improved varieties for Africa, each well adapted to local conditions, argues strongly for giving priority to well-funded and staffed crop breeding programmes at the national level. Country-level programmes have lower costs and are able to deploy larger numbers of teams which can operate in close proximity to the various agro-ecologies that need to be covered by any given programme.

xiii

13

A4138:AMA:DeVries:First Revise:15-Oct-01

Prelims

xiv

Executive Summary

International agricultural research centres (IARCs) have a major role to play in facilitating the development of fully capable national agricultural research systems (NARSs) able to produce the steady flow of new offerings required by farmers. In addition, international centres and advanced research institutes should devote significant resources and attention to the more difficult, ‘intractable’ constraints of crop production which affect the important crop species of Africa. Such intractable constraints are numerous and have not been solved despite considerable effort using conventional techniques. By combining their talent and resources, and drawing on the strengths of biotechnology, international centres and advanced research institutes may now be able to overcome many, if not most, of these difficult problems. Biotechnology remains a highly underdeveloped resource for improved food production in Africa, largely due to underinvestment by governments and international donors. Africa already has a number of scientists trained in biotechnology who are unable to utilize their knowledge owing to lack of facilities and operating funds. Since this situation may continue for some time to come, development of fully functional biotechnology capacity in all NARSs is not likely. However, those countries that can adequately staff both conventional and molecular breeding units should be encouraged to do so. Tissue culture of clonally propagated crops has already proved its value to agriculture in Africa. A second application of biotechnology which could prove cost-effective in the short to medium term is marker-aided selection for a range of traits, with the primary objective being to combine as many resistance traits as are required to maximize crop performance under low-input conditions. Finally, as national biosafety regulations and systems become operational, it will become more logical to invest in national expertise and facilities for crop genetic engineering, whereby critical resistance traits may be transferred directly into otherwise well-adapted varieties. Localized, agro-ecology-based crop improvement schemes need to be supported by similarly oriented seed enterprises. In Africa, investment in the seed sector has historically been very low, in part influenced by the poor success record of large seed companies on the continent. Large, monopolistic seed companies have perceived little advantage in pursuing the locally directed breeding programmes needed to develop a range of varieties adapted to the various niches created by environmental variation. Multinational seed companies that rely solely on their own offshore breeders and gene banks find it difficult to overcome the adaptation barriers of Africa; and their historical reluctance to commercialize germplasm under licensing agreements with the public sector further diminishes the attraction of operating in Africa. Conversely, smaller entities operating in a competitive environment that ally themselves to NARS breeding programmes for access to new varieties may perform well with respect to small farmers’ interests. Their most obvious limitations – size and lack of capital – can serve as an effective entry point for governments, private investors and donor agencies. Limited production of foundation seed is one bottleneck to the growth of this and related models for development of the seed industry. More harmonious regulatory structures across the region are also needed. Taken together, the combination of new science, new ways of working with farmers, new opportunities for private sector seed supply, and a greater appreciation of Africa’s diverse agro-ecologies represent a new era in crop genetic improvement for Africa. Old arguments for products already being ‘on the shelf’ lose their meaning in

14

A4138:AMA:DeVries:First Revise:15-Oct-01

Prelims

xv

Executive Summary

view of what scientists and farmers can achieve today, if the needed effort and resources are put forward. In this context, the importance of responsive, relevant public policy in the furtherance of a healthy, functional germplasm sector in Africa can hardly be overestimated. Public policy makers need to be committed to solving the problem of food insecurity on the continent, and to employing relevant, up-to-date policy that can strengthen the breeding and seed sectors. The worldwide biotechnology debate has provided the latest opportunity to put African agriculture in the spotlight and emphasize the need to move policy structures forward rapidly and responsibly. A major tenet of these changes must be to encourage private investment of all kinds in the seed sector. Another is the reinforcement of public sector capacity in crop improvement, using both conventional and molecular techniques. The establishment of an effective set of biosafety regulations is also critical to taking advantage of recent advancements in crop improvement. In spite of its potential, genetic improvement of crops will always face limitations with regard to what it can offer to farmers in regards to their levels of productivity. No matter what efficiencies genetic enhancement is able to build into crop plants, they will always draw their nutrition from external sources, and this places enormous importance on the investments that can be made in the soils of Africa. Overall improvements in agricultural productivity are likely to move in tandem with improvements made in the management of soil nutrients by African farmers. Shortfalls in the level of nutrient supply that are possible through the uses of organic methods must be complemented by making fertilizer broadly more accessible to small-scale farmers. Because of the need to demonstrate the potential of the combined effects of genetic improvement and improved soil fertility, crop improvement initiatives and soil fertility management programmes should operate in similar environments and test their results on the same or similar sites. These policy and technology innovations can combine well with the revolution in farmer participation in agricultural research. One very critical entry point for farmer participation is the need to understand better the various agro-ecologies that can be targeted by public breeding programmes. Farmers are the best source of information regarding the number and prioritization of production constraints, as well as the spatial distribution of differing agro-ecologies. In view of the importance and complexity of their preferences for processing, taste, growth habit, and multiple uses of crop plants, farmers also need to be made part of the process of varietal selection. While there is no set procedure for farmer participation in breeding schemes in Africa, it seems obvious that breeding programmes which operate in close proximity to farmers and their base of knowledge will have definite advantages over those which do not involve farmers. Within this rapidly evolving professional context, crop genetic improvement can be viewed as a highly underexploited resource for improving food security among Africa’s majority, rural populations. Indeed, with late-maturing, low-yielding crop varieties dominating the farming systems of much of Africa, crop genetic improvement still has the potential to play an important role in the development of more productive agricultural systems throughout the continent. A new paradigm for germplasm improvement in Africa, and indeed in other regions of the developing world, can be envisioned. It is a paradigm driven first and foremost by the urgent need for food security in Africa among a growing population of very poor, rural people who have been left behind by globalization and the interests of the private

15

A4138:AMA:DeVries:First Revise:15-Oct-01

Prelims

xvi

Executive Summary

sector. The impetus for understanding the details of their needs in terms of better, more resilient crops leads directly to the application of an enriched set of technologies for crop improvement, including conventional, field-based selection and laboratory-based modification and enhancement of the germplasm. Public sector technology development in this paradigm is linked directly to a broad interface of private initiative through non-governmental organizations (NGOs), farmers’ associations and private business. And, it is backed up by the commitment to serving the peoples’ needs through seed distribution by an efficient seed sector. Providing the crop varieties needed to improve food security across the vast continent of Africa is an enormous challenge. No donor or national government acting alone would be able to mobilize the commitment and resources necessary to make a major change in this area. Novertheless, there is very little likelihood that Africa will be food secure without an intensive, long-term programme of investment in crop improvement which takes advantage of the full range of approaches now available. While it would be going too far to declare that improved food security through higher-performing crops throughout Africa is readily ‘do-able’, it is at least possible to break down the process into conceivable steps as follows: 1. Constructing the breeding teams within NARSs supported by IARCs. 2. Delineating and classifying the agro-ecologies which merit targeting. 3. Determining farmer preferences for new varieties. 4. Employing appropriate parental materials and breeding methods aimed to produce new varieties within an acceptable time frame. 5. Getting seed to farmers via public and private means. Running concurrently with the process above, biotechnology studies aimed at developing solutions to intractable problems can be initiated at any time. Products of those studies feed into step 4. In view of the recent, negative trend in food availability and child nutrition in sub-Saharan Africa, food security in Africa is one of the most critical challenges facing humankind today. The record of private investment during the post-structural adjustment era does not present a convincing argument that growth in the private sector alone will lead Africa out of poverty and food insecurity. The public sector still plays an enormously important role in offering hope to the poor and excluded throughout the continent. And within this grouping, public sector capacity in the genetic improvement of food crops presents an exciting opportunity to make real progress.

16

A4138:AMA:DeVries:First Revise:15-Oct-01

Prelims

Foreword

One of the many outcomes of the global media debate on biotechnology has been a heightened level of awareness, and – one wants to believe – interest in how the food crops that provide our nutrition are developed, grown, and eventually end up on our tables. This is a positive outcome for several reasons. First, because agriculture in the developed world, although playing a huge role in the way we live, tends to remain out of sight and out of mind for nearly all of us except the 2 or 3% who are farmers and farm workers. Second, because it has reminded us that food security is never a resolved issue. One way or another, we have to keep on producing enough food for 6 billion people today and 8 billion by 2025, or there could be mass starvation. Finally, the debate on biotechnology has provided spokespersons of the agricultural community with the opportunity of explaining to the rest of the world just how dependent we already are, with or without biotechnology, on genetic improvement of food crops and on inputs such as fertilizer. As the one remaining major world region where agriculture has yet to be transformed from subsistence, low-yield systems dependent on shifting cultivation to efficient, modern systems capable of producing regular surpluses, the question of crop improvement is especially important to Africa. Africa is also the sole world region where many indices of food security have shown a serious decline in recent years. In the context of continued high population growth and an increased emphasis on keeping Africa’s unique natural environment intact, it is clear that crop yields must be substantially and sustainably increased. As they have in all other parts of the world, more efficient, better-performing crop varieties can play an important role in achieving this goal. This book came about as part of a major restructuring of The Rockefeller Foundation which has resulted in a renewed commitment to the poor and excluded of the world, who have largely been left behind by globalization and economic growth. The study’s Africa focus reflects a greater emphasis being placed by our Food Security Programme on that part of the world bypassed by the ‘Green Revolution’. Its attention to issues ranging from frontier research in biotechnology to participatory methods of

xi

11

A4138:AMA:DeVries:First Revise:19-Oct-01

Prelims

xii

Foreword

seed dissemination via farmers’ groups reflects a greater concern with the application of science to the needs of the poor that result in real, positive changes in their lives and livelihoods. The title of Part I of this book, Biotechnology, Breeding, and Seed Systems for African Crops: Re-thinking a 10,000-year-old Challenge, reflects what is an ambitious attempt by the authors to encapsulate in a brief format our current understanding of the nature of the task of extending better-performing crop varieties to Africa’s farmers. While it is clear that any one group can only focus on selected portions of this process, it is hoped that the opportunities identified can mobilize additional resources and generate new partnerships which cover the full scope of the challenge ahead. It has been of particular interest to me to note the important roles the authors foresee for gaining a greater understanding of agro-ecologies in Africa and for the application of participatory methods as well as biotechnology. By generating new crop varieties with greater yield stability, greater productivity and greater local acceptability, and by getting the new genetic resources into farmers’ hands through more responsive seed systems, they believe increased food security can be attained. Gordon Conway New York January 2001

12

A4138:AMA:DeVries:First Revise:15-Oct-01

Prelims

I

Biotechnology, Breeding, and Seed Systems for African Crops: Re-thinking a 10,000-year-old Challenge

1

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter I

1

Introduction and Summary

Introduction The final decades of the 20th century achieved the fastest growth of the global economy ever recorded over a similar period. Rapid scientific and technological innovation, coupled with the opening up of economies throughout the world, permitted more people to improve their well-being than had ever been possible before over such a relatively brief period of time. Globalization, as the phenomenon of capital mobility and global distribution of technology came to be called, brought employment and opportunity to innumerable groups of people who only one generation previously were unable to imagine such changes. For many of the world’s poor, the most immediate effect of global economic growth meant simply eating better and enjoying the many subtle but influential benefits of adequate nutrition and improved health. World food prices fell dramatically, while life expectancy rose sharply. As living standards rose, greater numbers of children were also able to attend school. At the century’s close, however, it became apparent that not all the world’s population was equally swept along in the positive trend. A significant portion of the world’s population had failed to benefit from globalization. Furthermore, the widespread rolling back of social services within the public sector, coupled with the widespread belief that in the new world order everyone’s needs would be adequately met through the marketplace, meant that many members of this group had less chances of escaping poverty than ever before. The inability of a large segment of the world’s population to benefit from the current socio-economic advances presents the world with intellectual and moral challenges that cannot be ignored. Africa, it is widely accepted, lies at the core of this challenge. While home to fewer total numbers of this ‘left-behind’ group than Asia, it also embodies fewer of the factors necessary for inclusion in the growth-led process of globalization. In Africa, large portions of the population do not have access to sufficient food. Economies are not growing at rates required to generate new opportunities for 3

3

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 1

4

Chapter 1

growing populations. The ensuing widespread frustration felt by local populations is proving a fertile ground for civil conflict and regional wars. With upwards of 70% of Africa’s workforce engaged in farming, agriculture represents an important channel for extending new opportunities for improving the well-being of hundreds of millions of people throughout the continent. Unfortunately, continued reliance on technologies and practices designed for a previous era means that agriculture has largely become a trap for Africa’s rural population, guaranteeing a life of poverty and isolation. It does not have to be this way. The arrival of the information age, combined with new biological technologies, and new ways of linking people to them, means that peoples’ lives can be improved in a relatively brief period of time. This book explores the ways to take advantage of the new capacity for global knowledge sharing and increased public and private capital gains from the past decades, and direct them at one important group of technologies – crop genetic resources – to broadly improve access to adequate food and enhance the well-being of Africa’s rural poor. This book is not intended as an analysis of all the activities ongoing in crop genetic improvement in Africa. Rather, it is intended as a collection of observations obtained from a wide range of geographical locations, as well as institutions involved in making crop genetic resources more valuable and more useful to African farmers. In making those observations, the authors also attempt to understand what has worked in Africa, what has not, and how the lessons learned might be grouped together to provide some guiding principles for crop genetic improvement (the term is used to imply all methods available, including biotechnology, conventional breeding, and seed dissemination) work in the future. Nevertheless, they are the first to recognize that much needs to be learned in Africa, and that the views of many qualified people must yet be sought. Improved food security, led by increased productivity among Africa’s many smallscale farmers, has been the aim of significant national and international effort in recent decades. However, the relatively underdeveloped, non-globalized state of African agriculture presents scientists, farmers and development agents with challenges at a number of levels. African agriculture at the close of the 20th century remains by and large an organic, living system, where biophysical signals within and between cropping systems still pulse and exert checks and balances on the levels of success that can be enjoyed by any single organism within the system. Strategies for increasing crop productivity which operate within this context must be significantly different from those applied in modernized, highly manipulated agricultural systems of developed regions of the world. They must also differ substantially from strategies applied in Asia, previously cited as a potential model for the challenge in Africa. This book attempts to show why this is the case, and take a new look at the potential role of crop genetic improvement in making sustainable improvements in the food security status of poor rural people in Africa. Improved varieties of African crops are destined for cultivation in soils that are very low in fertility and where attacks by pests and diseases and periodic drought often further reduce yields. These factors have led some to conclude that genetic improvement of African crops cannot result in major social benefits. Indeed, some popular arguments contend that increasing food production can do little to stave off hunger. But crop improvement within this context is not just about raising yield thresholds, just as efforts aimed at making food more abundant in chronically food

4

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 1

5

Introduction and Summary

insecure regions may have little impact on national food balances. Increasing the amounts of food produced among poor farmers is aimed at improving nutrition and maximizing options among people whose options are few. Better crop varieties for African farmers also involve increasing yield stability and safeguarding the meagre investments of some of the world’s most vulnerable people. This book argues that real gains in food availability for the poor and excluded of Africa are possible through publicly based, multi-tiered crop improvement strategies which are informed by farmers’ needs and attuned to the agro-ecologies in which the new varieties will be used. The argument put forward in this text does not contend that better varieties alone are the answer to food insecurity in Africa. Rather, more resilient, higher yielding varieties are viewed as an important component of a broadly improved and bettersupported African farming environment. Improved varieties will inevitably perform better on more fertile soils, just as farmers’ efforts at securing the harvest will go much further within national and international policy environments that support and value their livelihood. Nevertheless, this study does recognize and seek to capitalize on the advantages of seed and other planting materials in situations where, at present, little other assistance can be offered to farmers. Seeds are animate technologies that can be easily transported and transferred from one hand to another. Seed is also often the cheapest input available. Improved varieties, therefore, are frequently the only modernized input used by African farmers. They are the first step in securing the harvest. The frame of reference for this study is one which will be very familiar to many field researchers and development agents working in Africa. It is that of a single mother of several children whose primary means of income is a 1 ha plot of unimproved land on an eroded hillside. Depending on which part of the continent she is from, her principal crop may be maize, sorghum, cassava, millet, rice, or banana. Inevitably, her farm will contain other crops as well, such as cowpea, common bean, finger millet, groundnut, and if she is lucky, a few cash crops such as vegetables. From each harvest, she must provide for virtually all the needs of her family throughout the year, including clothing, health care, education costs and housing. Because she can afford few purchased inputs, the yield potential of her farm at the outset of the season is low – she can expect to harvest a maximum of perhaps 2000 kg of produce. Meagre though it may be, in most years, through a wise combination of sales, barter and home consumption, she may be able to cope at this low level of productivity. Figure 1.1a–d depicts hypothetically her farm’s productivity potential under different levels of intervention with adapted, accessible technologies, including better crop varieties and more fertile soils. During the course of any given season, innumerable threats to the crops appear on the scene (Fig. 1.1a). In the case of maize, the threats might be drought, maize streak virus, stem borers, and the parasitic weed, Striga. If she relies on cassava, the threats to her harvest may include African cassava mosaic virus, bacterial blight and green mites. Periodic drought during the season has a further, negative effect on yield. The impact of drought plus whatever combination of pests and diseases attacks the crop in a given year can often reduce the average harvest on her farm by perhaps 50–60%, to 1000 kg of harvestable produce. At this level of productivity, the family is on the edge of survival. If the losses are greater, or if disease enters the home, some members may not survive.

5

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 1

A4138

6

6

Strategies for securing the harvest in marginal farming zones of Africa.

Chapter 1

Fig. 1.1.

7

Introduction and Summary

The effect of crop varieties which resist and/or tolerate these constraints (Fig. 1.1b) can reduce such losses and raise her harvest above the theoretical survival line of 1000 kg. Meanwhile, improved soil fertility, shown separately in Fig. 1.1c, could allow her to raise her initial potential harvest to perhaps 3000 kg, but without better varieties the harvest is still reduced to some point at or near the survival line by the end of the season. Improved soil fertility and resilient crops combined (Fig. 1.1d), could provide her with the kind of productive potential and yield stability necessary to raise her harvest to perhaps 2000 kg, a major improvement. As uncomfortable as it may make us feel to contemplate the situation of this woman and her children, this is the reality of millions of farm families throughout Africa today. Certainly, they stand in need of development in the broadest sense. They need better roads, better schools, better health care, and more employment opportunities. But they also need better crop varieties, and in particular varieties which are resilient to drought, low nutrient soils, insect pests and the myriad of diseases which attack crops in Africa. Improving productivity – securing the harvest – in low-input systems where farmers cannot afford purchased inputs means delivering as many useful traits as possible within the seed. The end product of these efforts, moreover, must be usable and acceptable by rural households. On a continent where upwards of 70% of the total population are engaged in farming, better and more resilient crops which produce a larger and more dependable harvest can be an effective strategy for delivering more food and earning potential to those who need it most. Directing science and technology at the ground-level needs of poor farmers may not be the most effective way to increase food production on a national level. Better-off farmers in more favourable farming environments may be quicker to adopt new technologies and produce higher yields with them once they are in place. Nor are resilient crop varieties a new idea. But unlike in Asia, rain-fed, marginal farming conditions are not a secondary focus in Africa, to be targeted once the more favourable areas have been tapped. The difficult conditions and household scenarios like that faced by our ‘woman on the hill’ and her children are the only target whose solution will bring about meaningful change in the vast, rural areas of the continent. Recent observations of the revolution being brought about by globalization indicate they will not be delivered unless very practical, results-oriented programmes are implemented by agricultural research and development agencies within the public sector (Flavel, 1999; Persley and Doyle, 1999). It is an enormous challenge, made more difficult by the very limited resources currently being put forward to address it. Understanding how the challenge can be approached – ‘putting together the pieces’, if you will – of some very promising recent advances in the science and methods of working with the poor would seem a useful subject to explore.

Summary Recent years have seen vast improvements in our understanding of the genetic make-up of crop plants and the techniques available for enhancing them. It is now possible to do more for the ‘woman on the hill’ than ever before. Indeed, the failure of the Green Revolution to take root previously in Africa means that, in one form or another, most of this potential is yet to be realized. Nevertheless, accessing these advances and directing

7

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 1

8

Chapter 1

them toward the needs of the poor in an increasingly private sector-driven development agenda is a major challenge which requires support from many sides. Crop genetic resources are assets that the poor and excluded can own and further modify to meet their needs. Experience and observation have shown that African farmers are intensely interested in questions of crop variety performance. Most are already engaged in informal variety trials of their own design. Their expertise can be tapped in the search for resistance genes, in making selections, in growing out progeny and in adapting varieties to local conditions. Many of them can help deploy and disseminate the new varieties which result. African farmers are supported by a group of committed, well-trained scientists and technicians who understand well the tasks they face. Nevertheless, their numbers are as yet insufficient to ensure full success. Moreover, their lack of access to operating funds regularly reduces the rate and extent to which their knowledge can be applied. Additional training is needed, especially in the newer techniques for genetic improvement and in understanding better Africa’s diverse agro-ecologies; and additional financial support is required to allow them to put their strategies into action. Some of the solutions are close at hand. For example, introgressing resistance to maize streak virus in African maize populations should be a relatively simple task. If known resistance genes were transferred into locally well adapted genotypes, maize production across Africa might be increased by several million tonnes (see Plate 1). Achieving solutions to other constraints will require more complex, high-risk ventures. Downy mildew disease of millet is controlled by up to 17 genes (Hash et al., 1996), and the fungal pathogen can rapidly evolve new pathotypes. Resistance in cereal crops to the parasitic weed, Striga, is so ephemeral a trait that researchers are working at transferring in more durable resistance genes from wild relatives (Ejeta et al., 2000; Kling et al., 2000). This book attempts to consider both the broad context of the role of crop genetic improvement in improving food security in Africa and the more specific, scientific challenges inherent to improvement strategies within important crop species. As such, it is divided into two parts. This first part of the book looks at a range of human and environmental factors which condition efforts aimed at benefiting farmers through improved crop varieties, and then focuses on the discrete but interlinked roles of crop breeding, biotechnology, and seed systems in developing and delivering new products to farmers. The second part focuses on the challenges of genetic improvement and seed dissemination for seven crop species of broad importance to African agriculture.

8

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 1

2

2.1

The Challenge

Overview The exploration that gave rise to this book tried, to the extent possible, to take a ‘clean slate approach’ to understanding the role of crop genetic improvement in African agriculture, and recognize those factors which seemed most influential in how small scale farmers take advantage (or fail to take advantage) of improved crop varieties. An important sub-theme of this study was to understand why the Green Revolution of Asia and Latin America did not have a greater level of impact in Africa. Inevitably, the complexity inherent in the range of factors (farmer income, profitability, infrastructure, education, environmental factors, institutional factors, etc.) which affect crop improvement in Africa obliged the authors to group some of those factors which were perceived as less important tinto those which were believed to be of major, continent-wide importance. The result is a short list of interacting factors which includes: ● ● ● ● ●

the range and intensity of biophysical constraints to crop growth; large agro-ecological variation; the under-developed state of seed sectors in most countries; the absence of policies which encourage crop improvement; and, very low and declining soil fertility in much of Africa.

While depicted here as constraints, the chapter largely tries to communicate a message of optimism that previous barriers to raising agricultural productivity in Africa can be overcome through new knowledge, new science and better methods of working with farmers.

9

10

Chapter 2

2.2 A Myriad of Production Constraints The African continent south of the Sahara is dominated by agriculture. Approximately 70% of Africans live in rural areas and an estimated 50 million families derive their livelihood from farming. The vast majority of these farms cover an area of less than 5 ha and are hand-tilled. Crops are grown using a minimal amount of purchased inputs (i.e. seed, fertilizer, etc.) (Wiggins, 2000). Under these conditions, African crops are threatened by a daunting array of debilitating production constraints which farmers can do little to change. In this book, these constraints are loosely categorized as either ‘routine’ or ‘intractable’. ‘Routine’ constraints are those which may be more or less effectively controlled through plant breeding aimed at raising genetic resistance or tolerance levels through conventional crossing and selection methods. ‘Intractable’ constraints are those which are difficult or impossible to control through conventional crop improvement (see Plate 2). Categorization of a constraint as either intractable or routine is of course dependent upon the ability of the farmer to alter the growing environment. The very limited investment capacity of small-scale farmers in Africa means that many potentially routine production problems are, in fact, intractable. This increases the significance of genetic crop improvement as a strategy in their potential control. Likewise, the dominance of production constraints shifts the breeding strategy from one aimed at maximum yield potential under high input use to one aimed at limiting losses from identified constraints under low input use. The potential to manage production constraints through crop genetic improvement has increased steadily throughout the history of plant breeding, but has been greatly expanded through the emergence of biotechnology. Although the diverse applications of biotechnology may eventually make it a useful approach to the control of routine constraints to food production in Africa as well, for the purposes of this book, biotechnology is considered primarily applicable in the case of ‘intractable’ constraints. An incomplete, but illustrative short list of intractable constraints to production for seven crops in significant portions of Africa is given below (Table 2.1). While constraints to crop production exist throughout the world, they are more intense in the tropics. Wellman (1968) studied the incidence of diseases on a number of important food crops and noted far more in the tropics than in temperate areas. Dover and Talbot (1987) reported that preharvest losses due to pests and diseases are approximately 35–50% in some tropical areas (Table 2.2). Biophysical constraints in Africa pose a greater threat to increasing agricultural productivity than in other developing regions of the world. African farmers use vastly fewer off-farm inputs and largely continue to apply traditional methods of cultivation (Wiggins, 2000). In contrast, Latin American and Asian farmers have broadly modernized their cultivation methods over the past three decades (Table 2.3). Table 2.3 indicates the vastly contrasting pace of development in different regions in the developing world over the previous three decades. The agricultural sectors of Asia and Latin America, which began the period with higher levels of development in all categories (irrigation, fertilizer use and mechanization), have developed more rapidly than Africa’s. Latin America maintained a fourfold advantage in the percentage of irrigated agricultural land over Africa. Asia, which began the period with a massive, 24-fold

11

The Challenge

advantage in the percentage of irrigated land, continued to add irrigated land at a rapid pace, while Africa, continued to grow from a miniscule base. Significant variations in rates of growth are also noted in fertilizer use and mechanization. Asia and Latin America finished the three-decade period with more than fivefold and threefold increases in fertilizer application rates, respectively, while African Table 2.1. Examples of intractable constraints to production among small-scale farmers for seven important African food crops. Focus crop

Intractable traits

Maize Sorghum Millet Rice Cowpea Cassava Banana

Striga, stem borers, phosphorus uptake Striga, anthracnose, phosphorus uptake Striga, head miner, downy mildew Gall midge, rice yellow mottle virus Maruca pod borers, bruchids, thrips Root rots, green mite Banana weevil, nematodes, black sigatoka

Table 2.2.

Crop disease incidence in tropical compared with temperate zones. Number of diseases

Crop species

Temperate areas

Tropics

Sweet potato Rice Beans Potato Maize

15 54 52 91 85

187 500–600 253–280 175 125

Source: Dover and Talbot (1987) after Wellman (1968). Table 2.3. Rates of usage of irrigation, fertilizers and mechanical land preparation in Africa, Asia and Latin America. Irrigated area (% of total agricultural land)

Sub-Saharan Africa Asian developing countries Latin America and Caribbean

Fertilizer application (kg ha−1)a

No. of tractors in use (× 103)

1970

1997

1970

1997

1970

1997

0.4

0.6

1.2

2.9

84

159

9.6

13.4

9.0

52.5

488

4610

1.5

2.4

4.4

14.6

637

1589

Source: FAO (2000). aFigures vary. These were calculated by dividing FAO total fertilizer consumption by total cultivated area.

12

Chapter 2

farmers managed only an increase of between two- and threefold. African farmers now apply fertilizer at lower rates than Asian and Latin American farmers did three decades ago. Lower input use in Africa is probably substituted in part by added labour input, without which, yield levels would be lower. This translates to lower labour productivity, and an accompanying drag on management capacity within the household, with resultant negative impacts on factors such as sanitation, education and infant health. Even more striking differences were noted for mechanical land preparation. In 1998, Africa had one-third and one-quarter, respectively, the number of tractors in use as Asia and Latin America in 1970. All these factors – irrigation, fertilizer and mechanization – exert a homogenizing force on crop growth conditions when they are present. Irrigation (and drainage) makes water more uniformly available to the plant throughout the season, allowing for the plant leaf canopy to remain fully extended over the full growing cycle. Irrigation also significantly reduces risks associated with other forms of investment, such as fertilizers, which fail to provide a cost-effective response in the absence of water. Fertilizer application, in addition to supplying basic nutrition for the development of vegetative and reproductive structures, reduces variability of nutrient supply within the field, generally increasing the value of genetically uniform crop varieties. Tillage performed by tractors reaches deeper into the soil profile and, over time, reduces localized variation in the field’s topography. The effect of input use is both a whole-farm environment that is more favourable to crop growth than the surrounding, natural environment, and reduced within-farm variation. It is in part the reduction of this within-farm variation that makes possible the cultivation of highly uniform varieties of a single crop species possible throughout large areas of North America, Asia and Latin America. As we will attempt to demonstrate, the same is not true in Africa. The preponderance of production constraints among African staple crops calls for increased funding for research on crop genetic improvement to overcome those constraints. While biotechnology is not an automatic solution to these constraints, it should be viewed as a useful tool for improved food security in Africa. Tissue culture can assist in the rapid multiplication of pathogen-free and true-breeding lines. Genotypic analysis through marker-assisted breeding can be used to identify favourable individual plants with valuable, difficult-to-measure traits. Gene transfer through genetic engineering can overcome limited genetic variation within a given species. However, as emphasized throughout this book, biotechnology research should be linked from the beginning to viable field-based breeding programmes, and, ultimately, to seed dissemination strategies to prevent their results from remaining ‘on-the-shelf’.

2.3 Africa’s Diverse Cropping Landscape Africa’s cultivated area is of immense size and has great environmental variation. African farmers have developed complex cropping systems to fit environments ranging from the slopes of Mt Kenya to the fringes of the Sahara, each with its unique mix of biotic and abiotic constraints. For this reason, cropping patterns and dietary staples vary widely from one end of the continent to another. Moreover, observations of small- compared with medium- and large-scale farmers in Africa show that small-scale farmers tend to

The Challenge

13

cultivate a wider range of crop species, most likely as a strategy for maintaining household food security during a maximum portion of the year independent of household purchasing power. The need for diversification may drive farmers to cultivate a very wide range of crop and animal species (see Conway (1997) for an example from western Kenya). In isolated regions of the continent where species diversity is limited, intraspecies (or, varietal) variation may be substituted. Farmers in Sudan’s Bar el Gazahl region cultivate up to four varieties of sorghum whose morphological and growth habit differences rival those found among different crop species. Farmer crop deployment strategies extend to the species and subspecies level according to complex environmental and social norms. Rice farmers in northern Mali grow large plots of relatively high-yielding Asiatic (Oryza sativa) rice on upper-level terraces of their farms on the Niger flood plain for normal consumption during the year. In lower-lying parts of their farms, they grow preferred, African (O. glaberrima) varieties for use mainly during special occasions such as religious holidays, weddings, and baptisms. Farmers in the Bugusera region of Rwanda and Burundi grow different varieties of sorghum and bananas in the same fields for use in either beer-making or as weaning foods for infants. Farmers in a wide range of agro-ecologies of eastern and southern Africa grow small plots of sesame as a source of cooking oil, which otherwise represents a major household cash expenditure. The interaction of opportunities and constraints that farmers manage creates the resultant farming systems that embody the use of all available resources – human, ecological, genetic, and other – for achieving food security. Researchers have at various junctures attempted to understand this full picture of the farming system through extensive interaction with farmers prior to intervening through research initiatives (Hildebrand, 1981; Merrill-Sands, 1986). The complexity of farmers’ decision-making environments can be startling. Table 2.4 shows the agricultural calendar prepared by farmers and extension agents in Tete Province, Mozambique (Buhr, 1990). A tremendous amount of information can be inferred from the chart, which depicts, for example, what some agricultural economists have long asserted about African farming systems, namely, that labour is often a constraint in modifying existing cultivation practices (Barker and Cordova, 1978; Hildebrand and Poey, 1985). While labour shortages are obviously apt to exist during the September to November planting period, additional shortages can occur during much of the rest of the year, as well, including during the time of weeding and harvest, when certain ‘niche crops’ and second seasons (or ‘relay crops’) of main crops must be planted. These labour shortages often lead to late planting in large parts of Africa. This, combined with the existence of a recurrent ‘hunger period’ prior to the main harvest season, gives rise to the intense interest farmers in Mozambique and elsewhere have shown in earlier-maturing maize. Early-maturing varieties can also lead to the introduction of a second ‘relay’ crop, which can be grown on residual moisture, thus permitting a broad intensification of farming systems (Haugerud and Collinson, 1990). While such complexity can appear overwhelming to researchers attempting to make contributions through the transfer of improved technologies, experience suggests that it is just this level and type of information that is needed in targeting different agroecologies from a limited number of research sites, as in the case of plant breeding. These principals are explored in greater detail in Chapter 4.

14

pea

Chapter 2

The Challenge

pea Okra

15

16

Chapter 2

Because small-scale farmers in Africa cultivate largely unimproved (i.e. unterraced, non-irrigated, and undrained) fields, they have deployed a rich mix of crops, each bearing an adaptive advantage within some niche on the farm. The implication is that farmers of a given agro-ecology seeking to improve their overall productivity may be in need of improved, adapted cultivars of several crop species. Likewise, significantly improving any one crop may be of great benefit to one group of African farmers but of little importance to another (see Plate 3). While household economies and farm-level variability create crop deployment patterns at one level, large-scale environmental variation on the African continent creates crop deployment trends on a far wider scale. Understanding these trends can be of use in devising strategies for agricultural research at national and regional levels. Figure 2.1 shows the geographical distribution of production of staple crops within the major climatic zones of Africa. As would be expected, the distribution of crop species across differing geographical regions varies considerably. Within a region, however, priorities can be relatively easily identified. In order to significantly affect household food security status of rural populations, efforts focusing on a given region obviously must focus on a range of crops used extensively on farms within that region.

Fig. 2.1. Per capita production (in kg) of primary crops in sub-Saharan Africa. Ma, maize; R, rice; S, sorghum; Mi, millet; Ca, cassava; B, banana; Co, cowpea. Source: FAO (2000).

17

The Challenge ●

●

●

●

A major impact on food security in Africa’s semi-arid sahelian zone will require inclusion of drought-tolerant crops such as sorghum, millet and cowpea. For humid, lowland regions such as coastal West Africa and the Congo Basin, strategies should include a focus on cassava, with important, secondary efforts on maize and rice. Sorghum and millets, formerly major crops in eastern and southern Africa, are losing acreage and would appear to have decreasing importance in this region. Today, strategies for most rural populations of eastern and southern Africa need to focus primarily on maize, with important, secondary efforts on cassava, common bean and banana. Grain legumes remain important in the diets of people in all areas except the Congo Basin, although their inherently lower yield prevents them from competing with productivity levels of starchy crops. This translates to a focus on cowpea in lowland areas and common beans in mid-altitude and highland areas.

90 80 70 60 50 40 30 20 10 0

Fig. 2.2.

M ille t

m

e

rg hu

R

ic

So

at he

M ai

ze

Asia Africa

W

Crop consumption (kg person−1 year−1)

Dealing with environmental variation requires a strategy which encompasses the genetic challenge (namely, introgressing target traits useful to a range of crop species into a range of crop genetic backgrounds) (Buddenhagen and de Ponti, 1983) and the institutional challenge (working through structures which link differing national programmes facing similar crop improvement tasks). However, through better understanding of the prioritization given by farmers to different species and traits within those species, it should be possible to develop coherent, national strategies for improving the genetic basis for crop production for a range of species. Species selection by farmers across various subregions is reflected in consumption patterns for Africa as a whole. Figures 2.2 and 2.3 show figures for per capita consumption of the principal food crops in Asia and Africa during 1997. The data reveal the use of a wider range of food crops in Africa. Consumption of only two crops – rice and wheat – accounts for 70% of non-animal food consumption in Asia. Meanwhile, the consumption of Africa’s four most important crop-based food products – wheat, maize, banana/plantain and cassava – accounts for only 67% of its total, with much of the wheat being imported. The broad implications for crop improvement strategies in the two regions are obvious. Whereas Asia’s struggle largely hinged on the ability of researchers and farmers

Cereal crop consumption trends in Asia and Africa, 1997.

18

Chapter 2 80

Asia Africa

Crop consumption (kg person−1 year−1)

70 60 50 40 30 20 10

es ls

n ai nt la

/p

Pu

s m Ya na na Ba

Po Sw ta to ee tp ot at o

C as

sa

va

0

Fig. 2.3.

Consumption trends of selected non-cereal crops in Asia and Africa, 1997.

to devise more productive rice and wheat-based farming systems, in Africa, broad-based food security will require sustainable productivity increases within its respective agroecological systems based on maize, sorghum, cassava, millet, rice, pulses and bananas, among other crops. Consequently, this book focuses on seven priority food crops of sub-Saharan Africa. In Asia, the initial success of modern varieties of irrigated rice and wheat was followed by success in developing varieties for many rain-fed areas devoted to these and other crops. Most of Africa, however, is characterized by farming conditions that have reduced or delayed the impact of genetic improvement found in other parts of the world. While all the major regions of the world include areas with these sets of conditions, in Africa, they dominate. As indicated by Byerlee (1996), these include marginal crop production areas, areas with very poor infrastructure, and areas where quality traits outweigh the yield advantages of improved varieties, among others. An observational accounting of land use patterns among small-scale farmers in Africa’s little-modified agricultural landscape indicates that crops are employed largely according to their ecological niche. Issues such as temperature, natural drainage, rainfall patterns, soil fertility, and pest and disease occurrence, to a large extent, govern which crops can be used where. In the tropics, the temperature regime is mainly influenced by elevation. Most attempts at classifying cropping systems have focused on this factor. In the following, an attempt is made to offer descriptions of the trends in agricultural land use in differing environments in Africa. Lowlands. Valley bottoms of lowland humid environments are widely sown with rice. In off-seasons, raised beds often produce sweet potato. In sloping areas, cassava and upland rice are grown on highly leached soils. As rainfall decreases, soil phosphorus levels increase and maize can be grown. Semi-arid lowland zones are dominated by sorghum and millet cultivation. Cowpea is the most important pulse crop grown in all welldrained lowland environments. Few pulses grow well in poorly drained lowland environments, and diets often lack this element. Mid-altitude zones. Mid-altitude zones of Africa are dominated by maize. In higher rainfall areas, however, maize productivity is reduced by foliar and storage pests and diseases and reduced sunlight, and cassava and/or bananas are commonly grown.

The Challenge

19

Cassava is also substituted for maize in very high population zones and areas with very poor soils. In lower rainfall areas, moisture stress reduces yields and sorghum becomes the dominant crop. Poorly drained mid-altitude environments are planted to rice. Beans and pigeon pea are the most popular pulses in mid-altitude zones. Highlands. Areas above 2000 m except Ethiopia are planted to ‘English’ potato and highland bananas, with interspersed plantings of maize and wheat. In Ethiopia, highland areas are planted to teff. The dominant pulse of the African highlands is beans. In the Great Lakes regions, beans also supply a large percentage of carbohydrates. The result is a rich and resourceful utilization of crop genetic resources which contribute economic advantages, nutrition, and cultural significance to rural households across the continent. Moreover, this diversity, while presenting its own challenges to crop improvement, holds the promise that improvements made on crop species can be used in ecologically sustainable ways. As explored in greater depth later in this book, both the variety of crops and the importance of their adaptation, in turn, highlight the need for decentralized breeding operations and the continual involvement of farmers in identifying traits and selecting improved crop varieties for multiplication and commercialization. Regional crop improvement programmes have made some attempts at understanding the complexity of agro-ecologies in Africa in order to target better their breeding efforts and varietal testing programmes (see Plate 4). The International Center for Maize and Wheat Improvement (CIMMYT), for example, has recognized nine maize production ‘mega-environments’ in sub-Saharan Africa based on three different altitude ranges in three different ecologies: lowland tropics, subtropical, and highland tropics (CIMMYT, 1990). The International Center for Tropical Agriculture (CIAT) has recognized 14 ‘bean production environments’ in sub-Saharan Africa based on similar criteria (Wortmann, 1998). Such groupings of environmental variation into aggregated geographical units is critical for the targeting of crop genetic resources aimed at achieving continent-wide coverage. However, the level of resolution achieved by such efforts to date remains imprecise in comparison with its importance in hitting the target consistently, throughout Africa. Thus, crop-specific agro-ecological analysis remains a critical area of untapped potential for broadly improving the impact of crop genetic improvement. In most cases, this will be a task taken on by the national agricultural research systems (NARSs), at times reinforced by ecological and ‘geographic information systems’ (GIS) studies performed by international agricultural research centres’ (IARCs) outreach programmes. Progress has been made in several countries. As an example, the Kenya Agricultural Research Institute (KARI) recognizes five maize breeding agroecologies in Kenya which are used to focus breeding efforts, depicted in Fig. 2.4. Researchers in western Kenya have recognized additional subclassifications within the ‘moist mid-altitude zone’, which can be used to add further precision to crop improvement efforts (Amadou Niang, personal communication). Thus, even cursory inventory of maize agro-ecologies in Kenya may result in six or more broad ‘families’ of maize varieties. Kenya represents one of the most intensively studied countries in Africa, and, perhaps not coincidentally, one where crop genetic improvement has made significant impact (Gerhart, 1975). Wider and more intensive analysis of agroecologies needs to be conducted by crop improvement teams in all African countries.

20

Chapter 2

Fig. 2.4. Constraints to maize production in major agro-ecologies (Highlands, Mid-Altitude Moist, Mid-Altitude Intermediate Moist, Mid-Altitude Dry, Mid-Altitude Intermediate Dry, and Tropical Lowlands) of Kenya identified by KARI maize breeding teams. DTM, days to maturity.

Trying to make accurate determinations of varietal needs for numerous groups of African farmers living in widely varied agricultural agro-ecologies is a real challenge. Without it, however, the chances of success are slim. Experienced crop improvement specialists in Africa can cite the many new varieties which have been developed for

The Challenge

21

African farmers, but which have never been adopted. Former US Secretary of Agriculture, Clayton Yeutter, writing recently on the biotechnology revolution (ISAAA, 2000), stated: Newer genetic modifications, impressive as they may be in the laboratory and in the pages of professional journals, are of little real world relevance unless those desirable traits are transmitted through seeds with good yield characteristics. Otherwise, farmers in the U.S., Africa, or anywhere else, simply will not plant those crops.

Unlike Asia, new crop varieties for Africa cannot be developed based on the assumption that fertilizer will be subsidized and made available through government programmes. To be adopted in Africa, new varieties need to be well adapted to local conditions and provide yield advantages with few external inputs. Recent approaches to breeding focused on selection under low-input African conditions (Bänziger et al., 1997; Bahia and Lopes, 1998) have proved effective in identifying varieties with superior performance under drought and low soil nutrient status. Such adaptation to environmental stress needs to be combined with good levels of resistance to foliar diseases, insect pests and, in some cases, the ability to grow vigorously during early stages of development to ‘shade out’ weeds. While landraces will in most cases have reasonable levels of resistance to all these constraints, for reasons related to co-evolution and the relatively slow rate of genetic change via mass selection methods performed by farmers, it is unlikely these levels will match those possible through scientific breeding programmes. To develop varieties that poor farmers find useful, it is necessary to understand environmental variation in Africa and listen to farmers’ advice on issues of growing environments and household utilization, a topic explored more extensively in Chapter 4. In Africa, perhaps more than in any other part of the world, the science of genetic improvement must be paired with the art of understanding people and the environment. This will require additional investment in areas which serve to consolidate the presently diffuse, dispersed base of knowledge on agro-ecologies and crop ‘user systems’ in Africa. Recent initiatives such as the atlases on bean, cassava and maize are a good start in this direction (Carter et al., 1992; CIAT, 1998). Household preferences, as well, cannot be overlooked in breeding programmes and consideration should be given to the overall crop usage environment in which the adoption must take place. Some crop/user system combinations in developing countries constitute situations where yield advantages of improved varieties can easily be outweighed by the importance of quality traits (Herdt and Capule, 1983). Very poor farmers often cannot afford to pay for industrial milling services, and must carry out all processing tasks in the home. Thus, farmer preference for flint-textured maize varieties among resource-poor farmers in Malawi was key to identifying flint hybrids which achieved high levels of adoption in the early 1990s (Nhlane, 1990; Smale et al., 1993). Likewise, food scientists who have analysed sorghum quality characteristics have become increasingly capable of predicting the acceptability of improved varieties based on the quality of food products they produce. Studies conducted using sorghum flours from West, southern and East Africa revealed significant differences in flour texture and total water content of porridges consumed. Households preferred varieties with high amylose starch content and low flour lipids and proteins (Fliedel and Aboubacar, 1998). Few improved varieties have scored high in such tests. Nevertheless, breeders have often

22

Chapter 2

failed to take full advantage of the ability of food scientists or consumers to inform them of the probable success of their offerings at the household level. The need to link as much field-based information as possible to crop improvement programmes argues for a high degree of integration of disciplines and connectivity between breeders working at international, regional and national levels. Decisionmaking matrices that may seem very complicated to breeders may be a relatively simple matter for farmers who use crops in various forms everyday. Since many aspects of adaptation and farmer preference do not relate to expertise commonly embodied within crop research institutes, adequate linkages need to be established with agencies or individuals who do embody this expertise, including farmers and NGOs.

2.4 A Seed Sector ‘Dominated by Market Failure’ While the trend toward privatization and globalization of the germplasm sector has undoubtedly resulted in the distribution of better seed-based technologies to farmers in developed regions of the world, these policy changes will not function to the same extent in Africa in the short or medium terms. Private seed companies are constrained to operating in environments where they can make acceptable profits. In Africa, multinational seed companies may be motivated to popularize one or even several highyielding maize hybrids among better-off farmers in favourable areas, but it is less likely that they will find it profitable to devote significant resources to developing varieties with the very specific adaptation advantages required by small-scale, low-input farmers. Even if such varieties enabled resource-poor farmers to double their yields, this would often mean an increased harvest of only 1 t ha−1 or less. The share of increased profits a seed company might capture from such a modest increase is small in comparison with profits available in developed regions of the world (Tripp, 2000). Additionally, the degree of complexity involved in designing a full range of varieties required by different categories of farmers cultivating farms in very different agro-ecologies further limits potential profitability. Low effective demand and relatively small profits available from seed in much of Africa, in comparison with the rest of the world, have delayed the commercialization of the seed market. Low rates of economic growth forecast for much of Africa are not likely to attract large-scale investment from outside the continent of the type needed to achieve broad coverage of farmers’ needs for seed. Rather, indigenous seed companies that operate closer to local markets and on lower margins should be considered as a solution with wider potential. To date, however, little international or national assistance has been directed at this type of company. The strategy put forward in this book places high importance on the development of Africa’s private seed companies. Regardless of the strategy employed, given the economic realities in Africa and the difficulties seed companies face in attracting clientele, growth of the seed sector is likely to be slow and sporadic. The implication is that public sector-based strategies for seed dissemination will be critical to realizing the benefits of crop genetic improvement in Africa for some time to come. In fact, the absence of a sufficient effort by either private or public sector breeding interests has left an enormous gap in the seed supply offered to African farmers. While things can be done to encourage such investment, alternative strategies and continued experimentation are needed (see Chapter 6).

The Challenge

23

Finally, in the absence of investment by private seed companies, the rapid-fire, signal–response, product-refining process that is the great advantage of distribution systems conducted via private enterprise will not operate for seed in Africa. Feedback on performance and preference issues must be gathered through other means. This fact drastically increases the need for continual participation by farmers in variety refinement and seed dissemination. It also points to a critical role for research managers who oversee crop improvement initiatives and are ultimately responsible for ensuring that useful varieties emerge from such efforts. This challenge is discussed in greater detail below.

2.5 Policies and Institutions are Critical to the Success of Crop Improvement Policies that favour food security – like those which favour education and health – provide a foundation for development and the passing on of these basic human needs to successive generations (Sen, 1981). Of these three commonly cited priorities for development, however, the most basic and immediate is security against hunger. In Africa, where none of the three needs has as yet been broadly secured for society, equity arguments can be advanced that food security ranks as the most essential priority. Yet public and donor funding for agriculture has lagged far behind other priority sectors in Africa. A recent review of public spending in Uganda showed that agriculture accounted for just 4% of total expenditures from national and donor agencies’ sources, compared with 11 and 20%, respectively, for health and education (Uganda Ministry of Finance, 2000). Few African countries have prioritized food security through development of the agricultural sector. While speeches made by African leaders are invariably peppered with references to freedom from hunger and development of the economy through technological advance, public sector spending on agricultural research and extension in Africa declined from 1981 to 1991 (Pardey et al., 1997). African governments have received little real encouragement to develop their agricultural sectors from Western governments, several of which have de-emphasized the agricultural portfolios of their aid packages to Africa during the 1990s. The US government made payments to farmers of $7.3 billion in 1995 and 1996 (USDA, 1998). Meanwhile, the prevailing belief is that the agricultural sector in Africa should develop itself. Thus, a fifth challenge is situated within the institutional framework of crop genetic improvement: how individuals, groups, and institutions are organized to achieve results in relation to goals which require collaborative arrangements, resulting in a physical product which is usable by farmers. Overall institutional or departmental performance influences significantly the output of breeding teams and is generally unrelated to the academic preparation of the individuals involved. The area of public policies and institution performance attains greater importance in relation to the many regulatory issues and intellectual property rights attached to techniques and products of biotechnology. At a national level, there is a need for crop-based strategies for genetic improvement that make use of the full range of scientific capacity which can be applied. National breeding programmes are the front lines of public sector breeding in Africa. For many of the self-pollinated crops, and for open-pollinated varieties (OPVs) of cross-pollinated

24

Chapter 2

crops, national programme varieties are likely to continue to be the dominant means by which genetic improvements move out to small-scale farmers in Africa. The efficiency of this process is highly sensitive to the science policy of each institution and the regulatory framework governing plant varieties. National and international policy on intellectual property and plant variety protection is being debated in various corners of the globe, and outcomes are difficult to predict (Barton, 1998; Erbisch and Maredia, 1998; Koo and Wright, 1999). Indeed, confusion exists in many cases regarding what forms of biological property can be protected where and for what purpose. By some interpretations, the trend would seem to threaten access by developing countries to genetically engineered crops and, quite possibly, to other biotechnology applications as well, as donor agencies reduce support for all but conventional science applications. The widespread patenting of breeding materials by both private companies and public universities in the USA and Europe has inevitably reduced the flow of germplasm from those regions to Africa. However, even at this early stage, progress has been made towards sharing critical intellectual property that would seem to counter that argument (Mugo, 2000). What seems clear is that developing countries require advocates who work in the interest of broadening access by them to emerging technologies, and not simply the products of those technologies.

2.6 The Soil Fertility Problem Better varieties, of course, are only part of the challenge. Of equal or greater importance to realizing the full productive potential of crop plants is the supply of plant nutrition through healthy, fertile soil. Traditionally, major increases in productivity have mainly come about as a result of a combination of improved production systems (irrigation, drainage, improved cultural practices, introduction of fertilizers) and the introduction of more efficient varieties (Matlon and Adesina, 1991). The introduction of improved wheat and rice varieties in Asia, for example, coincided with wider availability of inorganic fertilizers and irrigation (Herdt and Capule, 1983). Cheap and widely available inorganic fertilizer in Nigeria facilitated rapid expansion and intensification of maize production following the introduction of improved, adapted varieties in the 1970s (IITA, 1995). More recently, improved maize varieties and increased fertilizer applications (encouraged by credit facilities) in Ethiopia during the period 1994 to 1996 produced a dramatic, 31% increase in average yield (Quinones et al., 1997) (see Plate 5). Fertilizer consumption in Africa has stagnated, even while land brought under cultivation has increased dramatically. From 1970 to 1982, there was a slight but steady increase in fertilizer consumption in Africa, but there has been no increase in total consumption since then (Fig. 2.5). Meanwhile, the continent has added 270 million persons. The reduced fertilizer use per capita has been made up through bringing new land into cultivation and by ‘mining’ soils of their nutrients through continual cultivation without replenishment of nutrients. As a result, net nutrient outflows per year in Africa are estimated at 63 kg ha−1 year−1 on average (Debrah, 2000). Lower input use in Africa is probably substituted in part by added labour input, without which, yield levels would most likely be even lower. Herein lies an enormous problem. Farmers in sub-Saharan Africa use by far the least amount of fertilizer in the world. In 1993, average application of total nutrients in Africa

The Challenge

25

Fig. 2.5. Total fertilizer consumption in Africa (excluding Egypt and Libya). Source: IFA (2000).

was 10 kg ha−1, compared with 83 kg ha−1 in other developing regions (Heisey and Mwangi, 1996). Moreover, subsidies which formerly encouraged the use of fertilizers were largely removed starting in the early 1980s, and have not been re-applied. The halt in increase of fertilizer applications in Africa shown in Fig. 2.5 coincides nearly exactly with the implementation of those policies. Studies conducted by Holden and Shanmugarathan (1994) and Bumb and Baanante (1996) both showed that higher fertilizer prices following the removal of subsidies led to reduced application of inorganic fertilizers in several African countries. Today, domestic fertilizer prices in Africa are far above world prices. While world urea prices in 2000 ranged between $80 and 100 t−1, urea prices in several African countries range from $400 to $842 t−1 (Debrah, 2000). At prevailing fertilizer costs and farm-gate prices for commodities, the economics of fertilizer use are not favourable. Extensive analysis of fertilizer responses, fertilizer prices and producer prices for maize in Malawi from 1994 to 1997 resulted in researchers recommending zero application of ferilizer on maize produced for market in 34 out of 41 agro-ecologies (Benson, 1997). In summary, therefore, at current fertilizer prices in Africa, there is little perspective for fertilizer application among African farmers to increase (Sanchez et al., 1997). Privatization of agricultural input markets has removed much of the flexibility governments formerly availed themselves of in encouraging the use of agricultural inputs, including fertilizers (Cromwell, 1996). To an increasing degree, therefore, poor farmers are left with fewer options. The response among soil fertility researchers to reduced applications of inorganic fertilizers has been to focus on the cycling of nutrients in low-input systems and the use of lower-cost methods of adding nutrients, such as legume rotations, green manures, and improved fallows (Sanchez et al., 1997). While significant amounts of nitrogen can be added to soils through the cultivation of green manure crops, the limitations of this method for maintaining soil fertility must not be overlooked. Crop recovery of nitrogen contributed by the leaves of leguminous plants is generally lower (10–30% recovered) than that contributed by inorganic fertilizers (20–50%) (Palm, 1995). More importantly, legume biomass contributes little of the phosphorus required to complement the nitrogen and potassium contributed by such additions. For example,

26

Chapter 2

cover crops of velvet bean (Mucuna pruriens) and Crotolaria ochroleuca contribute on average 35–42 kg nitrogen and 7–9 kg potassium per tonne of biomass, but only 1.6–2 kg of phosphorus (Palm et al., 1997). A substantial crop of either of these green manures of, say, 5 t ha−1 would thus yield a maximum of 10 kg P ha−1 – far below the minimum required for a 2 t ha−1 crop of maize. Humankind’s dependence on the Haber–Bosch process of synthesizing nitrogen for use in producing its food requirements has been extensively analysed by Smil (1991), who concluded that no alternatives to the use of inorganic nitrogen currently exist for densely populated developing countries. While many African countries have low absolute population:land ratios, Binswanger and Pingali (1989) revealed that in reality, due to highly uneven resource endowment in Africa, many countries have high effective population densities. Heisey and Mwangi (1996) have also described many African countries as land-scarce. These considerations, coupled with the recognized labour constraints many small-scale farmers operate under in Africa, argue for continued efforts aimed at making fertilizers broadly more accessible to small-scale farmers. In an analysis of the factors leading to low fertilizer usage among small-scale African farmers, Debrah (2000) identified as critical factors: high fertilizer cost, low farmer profitability, unequal access, low credit availability, and socio-economic factors related to farmers’ attitudes toward fertilizer use. The Sustainable Community-oriented Development Programme (SCODP) is an NGO aimed at improving access to fertilizer and seed among farmers in Siaya District of western Kenya. The organization promotes the use of these inputs and improved crop management practices through 11 small farm input shops located in rural market centres. By breaking large (50 kg) bags of fertilizer into units ranging from 100 g to 2 kg, the organization became the largest supplier of fertilizer in the district in only 4 years. Moreover, the organization was able to operate at a profit, and projected growth in sales of over 400% by 2002 (SCODP, 2000). Such initiatives – SCODP is supported by several donor agencies – may reveal how fertilizers can be supplied at more affordable prices than at present. Nevertheless, the scale of such activity remains very small. Only 10% of farmers in Siaya currently use fertilizer, and fertilizer application rates in the SCODP project area remain low. Even if SCODP were to achieve projected growth in sales, average fertilizer application rates in the District would remain at 6 kg ha−1. Finally, the case of broad provision of small quantities of fertilizer to African farmers deserves attention. Between 1999 and 2000 in Malawi, the ‘Starter-Pack’ programme distributed 2.86 million packages to 2.4 million farm households (indicating full coverage but some errors in distribution as well). Packs contained a range of crop species, depending on the agro-ecology in which they were targeted, but generally consisted of 2 kg of cereal crop seed, 2 kg of legume seed, and 10 kg of fertilizer. Average household harvest increased from 1087 kg ha−1 to 1904 kg ha−1, resulting in an average increase of 96 kg per household (Mann, 1999). Distribution of the packages boosted national maize production by 25% and extended household food sufficiency from 6.1 to 8.7 months (Levy et al., 2000). However, the sustainability of this programme is already being challenged. Projected low rates of economic growth coupled with population increases in sub-Saharan Africa during the coming decade (Conway, 1997) carry important implications for technology development and application among small-scale farmers. If, as projected, fertilizer applications in Africa are likely to remain low for the foreseeable future,

27

The Challenge

the primary contribution from plant breeding will come from efforts aimed at making crop plants more productive and dependable within low-input, limited-infrastructure production environments. Improved nutrient management based on accessible, practicable methods of returning nutrients to the soil can make land more productive, and more resilient crop plants can help produce better harvests; however, it is likely that Africa’s crop production environment will generally remain low in fertility. Low soil fertility and low fertilizer use, combined with a lack of irrigation, very low pesticide use, and low rates of tractor use in Africa, effectively mean that crop genetics and improved planting material remain as one of the most effective means by which African farmers can be assisted. The absence of these productivity-enhancing, agroecology-homogenizing factors of production makes the task of crop improvement more complex and more difficult in Africa than in other parts of the world. But low input use does not reduce the importance of crop genetic improvement in the lives of Africa’s rural poor, rather, it raises it.

2.7 What, Then, is Needed? Quite obviously, improving all crops for all possible traits in all agro-ecologies in Africa is not feasible in the short or medium terms. One obvious difficulty with agro-ecological approaches is in achieving the scientific and technical acuity at all the levels necessary broadly across the continent. Without making a detailed analysis of the number of breeders and other crop scientists currently employed at the national and international levels in Africa, it is safe to say that there are currently insufficient numbers to apply systematically agro-ecology-based strategies for crop improvement. However, if one accepts that the biophysical challenges in Africa are great, and that new science combined with new methods for understanding and deploying the varieties that farmers desire does create a new ‘realm of the possible’ in Africa, then a concerted, worldwide effort at improving overall agricultural productivity in Africa, including the genetic performance of Africa’s food crops, is justified. Moreover, simple calculations of the financial requirements for funding the national component of the challenge (shown in Chapter 4) reveal that making this effort is not necessarily prohibitively expensive. Making use of lessons learned over the past decade of working closer with farmers in Africa, and combining those lessons with breakthroughs made in genetics, the following steps can and should be taken. ●

●

●

Identify traits that genuinely reduce productivity at the small-scale farmer level in a wide range of environments in Africa and for which a (full or partial) genetic solution may be possible. Understand and conceptualize the various agro-ecologies within which new crop varieties need to be deployed, and determine the priority constraints, adaptation advantages, and user preferences which need to be targeted in developing new varieties. Identify individuals and institutions capable of making meaningful contributions to a genetic solution to each trait.

28

Chapter 2 ●

●

●

Provide opportunities for interaction between groups of scientists, aimed at identifying strategies for developing the available genetic resources into a farmerusable product. Implement strategies via vertically integrated crop improvement initiatives which incorporate biotechnology, breeding, and seed systems. Disseminate new technologies via farmer-focused, agro-ecologically informed initiatives which consider the full range of agronomic and genetic technologies which can benefit farmers.

Due to the complexity and size of the challenge implied, a long-term commitment is required. Only through successive research steps, each carried to the next stage, can progress remain on track and capable of delivering needed products. Because biotechnology, breeding, and seed systems form relatively discrete functions within the crop improvement process, they can, to a certain extent, be considered as separate activities, each with its own sectoral strategy. They are considered as such in Chapters 4, 5 and 6 of this book. First, however, it is worthwhile to document the level and the kind of food that Africa needs and to understand how improved farmer productivity might contribute to a solution. Chapter 3 presents a brief look at the nature of food scarcity in Africa.

3

The Roots of Hunger

Rural communities in Africa are under pressure on several fronts. Profits from farming at the current, low levels of productivity, are too small to allow farmers to reinvest in their land and maintain sustainable production systems (Eicher, 1990; Blackie, 1994). Meanwhile, continual increases in population have depleted the available resource base and eroded many social entitlements which hitherto provided for a state of equilibrium in rural areas of Africa (Lele, 1989). Finally, steady increases in agricultural productivity in developed regions of the world (increasingly facilitated by biotechnology), combined with persistent payments of massive subsidies to North American and European farmers, have continued to push world grain prices downward, making it increasingly difficult for marginal land farmers in developing countries around the world to operate profitably (FAO, 2000). Rural areas by definition offer a limited set of economic alternatives to agriculture, and Africa has attracted very little direct foreign investment to create new jobs, even in urban areas. As a result, economic growth in rural areas has been insufficient to offer alternative means of employment for the rural poor (Eicher, 1990; Oyejide, 1993), and agriculture remains their only real option for survival and income. Africa has the highest percentage agricultural population and the second highest cultivated area in the world (Table 3.1). However, average cereal yields are the world’s lowest, and less than half of Asia and Latin America. Another reason for rising hunger in Africa during the past few decades is high rates of population growth. In 1970, Asia, Latin America and Africa had similar rates of population growth (Fig. 3.1). Yet population growth in Asia began decreasing rapidly thereafter and by 1978 had decreased by 25%. Latin American population growth rates declined more slowly, but by 1995 fell by nearly 20%. In Africa, the rate of population growth rose sharply between 1970 and 1995. At present, the population growth rate in Africa is nearly double that of Asia. A high population growth rate is especially injurious in countries with low or negative economic growth, where the number of lives to support simply outstrips the rate of appearance of new opportunities for adding value within the household. In 29

29

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 3

30

Chapter 3

Table 3.1. Key agricultural indicators from agricultural sectors of selected regions of the world.

Africa Asia Latin America North America

Cultivated area (million ha)

Agricultural population (millions)

Percentage agricultural population

Cereal yields (kg ha−1)

1070 1604 747 494

416 1922 111 8

57.8 55.9 23.3 2.6

1107 2886 2545 4189

Source: FAO (1998).

Fig. 3.1. Comparative population growth rates in Asia, Latin America and Africa, 1970–1995. Source: FAO (2000).

sub-Saharan Africa between 1987 and 1997, the average annual percentage increase in gross national product per capita was −0.7% (World Bank, 1998). Meanwhile, per capita foreign direct investment in Latin America in 1998 was $126, while in Asia it was $35. Africa lagged far behind in attracting investment, at only $6.85 per capita (see Table 3.2). High levels of population growth, combined with low or negative economic growth, have led to reduced access to food among Africa’s inhabitants. Although Asia, with 70% of the developing world’s total population, has far greater numbers of people who are undernourished, sub-Saharan Africa has almost double the percentage (33% compared with 17% in Asia) of hungry people (FAO, 2000). Within Africa, eastern and southern Africa account for the greatest number of undernourished people. Per capita food consumption in these regions has decreased during the period 1980 to 1995 (Fig. 3.2). In eastern Africa there was a 5.5% decrease in consumption and in southern Africa a 9.3% decrease. Child nutrition and growth rate is an especially relevant indicator of socioeconomic development. A recent study by the United Nations and the International Food Policy Research Institute (IFPRI) revealed that 35.2% of children in sub-Saharan

30

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 3

31

The Roots of Hunger

Table 3.2.

Key economic indicators, developing regions and the world, 1998. Population (millions)

Region Africa East Asia and Pacific Latin America and Caribbean World

GDPa GDP per capita (billions of $) ($)

Foreign direct investment (billions of $)

6,642.3

36,332.7

,518

4.4

1,800.3

1,900.3

1,056

64.2

6,509.2 6,000.3

2,100.3 30,200.3

4,124 5,033

64.3 619

Source: The World Bank (2000). aGross domestic product.

Fig. 3.2. Africa: per capita consumption of cereals plus roots and tubers plus pulses, 1980–1995. Source: FAO (2000).

Africa suffered from stunted growth. The figure when considering all developing countries was 32.5% (UN/IFPRI, 2000). In East Africa, 48.1% of children exhibit stunted rates of growth, the highest in the world. High birth rates in Africa mean that the total number of children with stunted growth has increased rapidly over the past two decades. Africa is the only developing region in the world where the percentage of underweight children is increasing (Fig. 3.3). Global statistics do not adequately explain causes of hunger. Regional or subregional trends in production and imports often mask severe food shortfalls within a given country or areas of a given country. Table 3.3 shows the trend in production and imports of the primary staple, maize, in selected countries of eastern and southern Africa. Percentage consumption made up of imported grain tripled in Kenya between the 15-year period up to 1990 and the 5-year period following 1990. Malawi has since recorded surplus production of maize, thanks in large measure to a countrywide initiative for free distribution of agricultural inputs, but such subsidies are unpopular with donors and are likely to be terminated.

31

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 3

32

Chapter 3

Fig. 3.3. Prevalence of underweight children in Africa and Asia, 1980–2005. Source: UN/IFPRI (2000). Table 3.3. Average annual maize production and import trends in Kenya, Malawi and Zimbabwe during 1976–1990 and 1991–1995 Imports (1000 t year−1)

Production (1000 t year−1)

Import % of production

2107 1331 1613

3.2 2.7 1.7

2524 1387 1425

9.4 24.0 24.6

1976–1990 Kenya Malawi Zimbabwe

68 36 28 1991–1995

Kenya Malawi Zimbabwe

238 333 351

Source: FAO (2000).

Among the vast number of isolated, agriculturally based villages throughout Africa, hunger is often directly tied to subsistence farming systems and the attendant cycles of production, harvest and off-season activity. ‘Hunger periods’ in Africa – periods during which there is very little food left in the granaries or in the ground (in the case of tuber crops) – normally occur during the months prior to harvest of the main crop. During these periods, hunger can be abated by growing short-cycle annuals (often cowpea or common beans) or even earlier-maturing varieties of the main staple, such as maize (Chapman et al., 1997). Identifying the most appropriate alternative, however, requires plant introductions and extensive on-farm research. The impact of low technology adoption on productivity and land use has been immense. While agricultural productivity in Africa as measured by cereal yields has

32

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 3

33

The Roots of Hunger

Fig. 3.4. Cereal yield trends, Asia compared with Africa, 1970–1997. Source: FAO Internet Database.

increased by approximately 18%, area under cultivation (FAO, 2000, data not shown) has increased by 32%. During the same period, cereal yields in Asia increased by 45%, while area cultivated increased by only 11% (Fig. 3.4). Food aid is often cited as a logical, if partial, solution to food insecurity in Africa and other food-insecure regions of the world. In 1999, the USA provided approximately 58% of total food aid shipments worldwide. In that year, the USA shipped a total of 9.84 million Mt of food aid to other countries. Of this, 1.14 million Mt, approximately 11%, went to Africa (USAID, 1999). The total value of this food was approximately $467 million. Food aid shipments to Africa from the European Union during the same period were approximately 140,000 t (Walter Middleton, personal communication). Some food aid (especially emergency food aid, which accounts for a third of Africa’s total from US sources) represents a key component of food security because it is channelled into areas and population groups with crucial needs. Nevertheless, with an estimated, total cereal harvest in Africa during 1999 of 75.54 million Mt (FAO, 2000), and additional, estimated total harvest of cassava and pulses totalling 27 million Mt, total food aid shipments to Africa from the USA in 1999 accounted for only 1.1% of food consumption. Thus, food aid represents only a very partial solution to food insecurity in Africa, and cannot be depended on over the long term. Commercial importation of cereals plus pulses and root crops into sub-Saharan Africa in 1998 totalled approximately 16.1 Mt (FAO, 2000), equivalent to 15.7% of total consumption of these commodities. Taken together, grain imports and food aid in 1999 thus supplied approximately 16.7% of total food consumption. While both food aid shipments and commercial imports are subject to fluctuations, the likelihood that either will begin to supply the major portion of the food consumed in Africa is low. With harvests currently accounting for roughly 83% of consumption, overall food security in Africa remains solidly dependent upon local agricultural production.

33

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 3

34

Chapter 3

Several writers have chronicled Africa’s declining food security (Pingali et al., 1987; Conway, 1997; Ravaillion and Chen, 1997), and it is not the purpose of this study to present an extensive analysis of the current status of Africa’s food security. Moreover, while this book focuses on ways to increase food production, it is understood that achieving this goal will not solve the problems of hunger related to lack of access to land or to poverty in urban areas. Rather, the book focuses on one, perhaps significant component of a solution to low productivity among small-scale farmers in Africa, that of more productive and more resilient crops. Recently, several authors have argued that hunger among the poor is not a food production problem, but rather one resulting from a complex set of interrelated factors such as markets, roads, prices and information, among others (Moore Lappé et al., 1998; Altieri and Rosset, 1999). While all of these factors undoubtedly play a part in improving the earning potential and food security of the rural poor in Africa, observations and discussions with farmers reveal that there are also many millions of rural poor whose food intake and farm income is limited by the size of their harvest. Agriculture accounts for upwards of 80% of total employment in many countries of sub-Saharan Africa. Higher farm yields among these people, made possible in part by more productive and resilient crops, will inevitably mean healthier, more productive lives and greater hope for the future. However, if farmers are to improve their levels of productivity for the benefit of themselves and the rest of the continent, it is critical that improved seeds be provided.

34

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 3

4

Breeding – Between an Art and a Science

4.1 Overview Crop improvement through the continual selection of better food-producing plants is an activity as ancient as agriculture itself. Through several stages beginning with the mass selection practices begun by the world’s first farmers, through the breeding revolution made possible by the discovery of Mendelian genetics, to today, as the world begins to make use of the first products of biotechnology, the improvement of crop plants has remained one of humankind’s most engrossing vocations. One of the best-known results of the crop improvement process has been an increase in the upper threshold of productivity in harvested portion per unit of land area planted. Increasing the yield potential of food crops has been one of the most important factors in the steady reduction of food costs throughout the world and the freeing of human and financial capital for other endeavours. The dramatically increased yield made possible by re-structured, ‘Green Revolution’ crop varieties has benefited literally billions but has also proved to be a controversial outcome. Agricultural productivity increases in most regions of the world have resulted in lower food prices, making food more accessible to the poor and contributing to increased life expectancy and providing a platform for broader, economic development (Lipton and Longhurst, 1989; Renkow, 1993; David and Otsuka, 1994). The opportunity to profit from higher-yielding varieties initially prompted wealthier farmers on better lands to invest in more purchased inputs and irrigation, often leading to changes in the welfare of poorer farmers (Frankel, 1971; Griffin, 1974). It has also led to continuous cropping and the build-up of pests and diseases (Khush, 1990). People farming poorer lands faced a greater risk of crop failure, obtained smaller yield increases, and were more reluctant to make such investments (Lipton and Longhurst, 1989). Over time, however, higher-yielding varieties with greater resistance to pests, pathogens, and other stresses were developed and spread throughout much of Asia, benefiting farmers in marginal and prime areas as well as consumers, through lower

35

35

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 4

36

Chapter 4

prices. In Africa, there is essentially no irrigation and inputs are expensive, so more resilient crops will be needed on both good and marginal lands. Small-scale farmers who depend in part on their own produce for nutrition and livelihoods may profit more from crop improvement techniques which enhance and stabilize yields by limiting losses than from higher yield thresholds (Buddenhagen, 1983; Widawsky and O’Toole, 1990; Herdt, 1991). Yield stabilizing traits come in many types, but usually translate to an increased ability of plants to resist or tolerate biological and environmental stress factors such as pests, diseases, drought and low soil fertility. Because the farmers most in need of such technologies are those least able to pay for them, making crops more resilient to marginal conditions remains a neglected area, both for science and the crop improvement sector, broadly speaking. In part because of weak public breeding programmes and in part because of the transfer of priority for crop genetic improvement to the private sector, the potential of crop genetic improvement in mitigating against low productivity in Africa, where the private sector has not responded as expected, remains under-exploited. In this chapter, we attempt to build an argument for increased efforts at developing crop varieties for African farmers which perform better under the marginal, low-input farming conditions that prevail across much of the continent. Differing both in scope and methodology from breeding initiatives which resulted in the Green Revolution, the proposed approach would make use of advances both in biotechnology and in farmer-driven, participatory methods of plant breeding described below. The central theme, however, is that the first, critical step in making use of either of those – and other – innovations is the development of plant breeding capacity across the continent. As noted elsewhere in this study, improved, adapted crop varieties for African farmers are not being proposed as a substitute for the numerous, other components of improved, agricultural systems, but are rather intended to serve as one component of those systems.

4.2 Aims and Contributions of Plant Breeding Plant breeding is a process of identifying and managing the full range of plant traits (plant growth characters which are controlled by their genes) in order to produce better combinations of those traits in new and more valuable crop varieties. Breeders accomplish this mission by controlling pollination events and making specific combinations of cross-pollinations and self-pollinations. Although the selection strategies employed by breeding programmes are numerous and complex, most plant breeding is aimed at improving food crops in four basic ways. 1. Restructuring of the plant, often in conjunction with time to maturity, whereby an increased portion of assimilate is directed to usable plant structures such as seeds or fruits. 2. Altering the time to maturity, through management of crop responses to photoperiod.

36

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 4

37

Breeding – Between an Art and a Science

3. Introgression of resistance and/or tolerance genes which allow the plant to perform better in the presence of biotic (i.e. pests and diseases) or environmental (i.e. temperature, moisture, or nutrient availability) constraints. 4. Heterosis, which occurs when genetically diverse parent plants are combined to form more vigorous hybrids. Breeding programmes develop both open-pollinated varieties (OPVs) and hybrid varieties. The distinction between OPVs and hybrid varieties is an important one. OPVs are varieties resulting solely from the recombination and selection of plant traits within segregating populations (following cross-pollinations, plant genes segregate in random fashion during successive generations, making the final outcome of any given crosspollination difficult to predict, and forcing breeders to follow large numbers of segregating plant families). OPVs are the end-products of these segregating populations once the variety has stabilized. Hybrid varieties are very different. Hybrids are the generation of seed produced by crossing non-segregating (fixed through repeated self-pollinations) parental lines. For reasons that are not completely understood, the crossing of contrasting, fixed parental lines gives rise to a generation of seed that is more vigorous and higher yielding. Once a hybrid has been grown in the field for one season, however, the genes in the harvested seed are beginning to segregate, and the yield advantage is progressively lost. Therefore, while OPVs can be saved from year to year without loss of performance of the variety, the same is not true for hybrids. Examples of each of these aspects of crop improvement are evident in different periods of agricultural advancement in various parts of the world, beginning with the world’s first breeders, the first farmers (and most likely, women). As each plant cultivated by the early farmers contained a set of genes controlling a range of plant traits, certain traits linked to survival and productivity such as plant vigour, disease resistance, seed number and seed viability would naturally have been enhanced through successive generations of sowing and harvest. This process, sometimes referred to as ‘mass selection’, continues today wherever seeds from previous harvests are saved and replanted the following season. It is known that farmers of Assyria and Babylonia artificially pollinated date palms as early as 700 BC (Poehlman, 1979). The first recorded observation of sexual reproduction in plants, however, was made by Camerarius, a German, in 1694, and the first systematic studies of artificial plant hybridization were done by a fellow German, Joseph Kolreuter, from 1760 to 1766. During the 1800s, plant breeding evolved gradually through studies performed by such individuals as Thomas Andrew Knight, president of the Horticultural Society of London from 1811 to 1838, by Le Couteur and Shirreff in England, and by Louis Leveque de Vilmorin and his son in France in the middle and late 1800s. Gregor Mendel’s classic studies on inheritance of genetic traits in garden pea, first reported in 1866 but rediscovered by the scientific community in 1900, led to the establishment of the science of genetics. In the USA, commercial maize hybrids were first made available to American farmers in the 1930s (Crow, 1998). The development of high-yielding hard red winter wheat varieties in the USA is traced to the introduction into Kansas of a Turkish variety, ‘Turkey Red’, by Russian Mennonites in 1873. The hard red spring wheat variety ‘Marquis’ originated from a cross made by Dr C.E. Saunders in 1892. Much higher wheat yields were made possible by the introduction into the USA from Japan of the

37

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 4

38

Chapter 4

short, semi-dwarf variety of wheat, ‘Noren 10’, in 1948. Norman Borlaug combined the ‘Noren 10’ germplasm with Mexican wheat varieties that led to breakthroughs in Mexican wheat yields in the 1950s. Early phases of Asia’s Green Revolution of the 1960s and 1970s were based largely on the restructuring of rice and wheat plants through the use of dwarfing genes (House, 1996). Rapid increases in maize production and yields in West Africa during the 1980s came about as a result of the release of earlier-maturing varieties with higher levels of disease resistance (IITA, 1995). Thus, the history of plant breeding is highly international, marked by both chance, fortuitous introductions made by farmers and more deliberate transfers of traits involving teams of scientists. The history of crop improvement in Africa is much the same, with numerous examples of both types of advance. A ‘durra’ variety of sorghum cultivated by Touareg nomads in northern Mali is commonly believed to have been introduced by pilgrims returning from Mecca. Meanwhile, rice varieties recently developed by the West African Rice Development Association (WARDA) combine traits from two distinct species and required several applications of biotechnology. Neither of these types of advancement, however, can serve as an effective substitute in Africa for consistent, informed, crossing, selection, and recombination carried out by plant breeding teams that is the mainstay of crop improvement systems throughout the world. At present, with notable exceptions in a number of countries, it is this central, key component that is most lacking in Africa, and most in need of public sector support. While in the USA, Europe and parts of Asia and Latin America a major portion of this activity has transitioned to the private sector, in Africa the same is not true. Just as food security was first attained through publicly funded initiatives (including the Green Revolution) in other parts of the world, African governments and their collaborating institutions must make this commitment, whose goal will be the establishment of adequately supported, NARS crop improvement teams for all essential food crops throughout the continent. Of equal or greater importance to the productivity of crop plants is the stability and long-term sustainability of cropping systems, as a whole (Buddenhagen, 1996). The development of improved varieties has been described as essential to the creation of a sustainable farming system under situations of intensification (Fischer, 1993, cited in Byerlee, 1996; Hoffman et al., 1993). Although plant breeding contributions to the sustainability of cropping systems are less widely recognized, evidence has been presented for sustainability improvements emanating from releases of pest- and diseaseresistant rice varieties in Asia in the 1980s (Conway, 1997) and early-maturing flint maize varieties released in Malawi and Mozambique in the 1990s (Smale et al., 1993; Chapman et al., 1997). More recently, maize breeding in Kenya has resulted in maize varieties with greater resistance to foliar diseases. After only 2 years of breeding, experimental varieties tested during a season of high disease incidence yielded higher than commercial hybrids (Ininda and Ochieng, 2000). As applications of biotechnology become more routine, they are being increasingly integrated with breeding programmes to result in a very different sort of crop improvement programme. In Africa, however, the integration of such techniques across most of the continent is still some years away. Therefore, it is still necessary to consider the breeding subsector as a stand-alone pursuit, mainly conducted by teams of public sector field researchers and in critical need of support from national governments and international donor agencies, alike. This section deals with the major movements afoot in

38

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 4

39

Breeding – Between an Art and a Science

breeding programmes in Africa and attempts to identify priorities within and across these institutional boundaries. As noted above, farmers in Africa have been making plant selections for thousands of years. These selections have resulted in popular ‘landrace’ varieties of indigenous crops such as sorghum, millet and cowpea, which have recognized names within and even across different agro-ecological zones. Examples of these include the popular Striga-tolerant variety of sorghum in Mali, ‘Seguetana’; the high-yielding and pest- and disease-resistant cowpea in Mozambique, ‘Namuesse’; and the widely adapted millet landrace from Togo, ‘Iniadi’. Selections made from introduced crops such as maize and cassava have also resulted in landraces of these crops being distributed among large numbers of farmers. ‘Catete’ is a popular, early-maturing landrace of maize in Angola. ‘Fumo de Comboio’ is a disease-resistant, high-yielding variety of cassava in Mozambique. ‘Reep’ is a late-maturing, yellow maize variety used widely in southern Sudan. Useful demonstrations of the value of these selection methods occur when varieties of cereal crops are introduced directly, without modification, from North America or other regions of the world. In addition to photoperiod differences which frequently result in altered times of flowering and harvest, such introductions normally suffer from very high incidence of crop pests and diseases. Added, major differences in grain quality and plant type preferences preclude most temperate germplasm from being of direct use in Africa, although certain useful crop varietal traits have frequently been transferred to African ‘backgrounds’ via back-crossing and population improvement methods of breeding. Modern plant breeding began in Africa in the early 20th century, following its emergence in Europe and North America, via the influence of colonialist governments. French scientists began breeding rice in West Africa as early as the 1930s and millet in the 1950s. Research on hybrid maize was initiated in Rhodesia in 1932. The first hybrid variety to be released in Africa was the maize variety ‘SR-1’, released in 1949 (Mashingaidze, 1994). Breeding programmes aimed at developing varieties for smallscale farmers were generally neglected, however, until after the Green Revolution in Asia. Such programmes received a significant boost with the establishment of the International Institute for Tropical Agriculture (IITA) in Ibadan, Nigeria, in 1967. Today, IITA conducts breeding on cassava, yam, banana, cowpea, soybean and maize. Since then, several other centres of the Consultative Group on International Agricultural Research (CGIAR) have established breeding programmes in Africa. Several cases of yield increases in Africa led by the introduction of improved varieties clearly indicate the potential of crop improvement to alleviate hunger. ●

●

●

●

Cassava yields increased dramatically in Nigeria following the introduction of improved varieties in the mid-1980s (Nweke et al., 1994). Maize production in West Africa over the same period increased by an estimated average of 4.1% annually following the development of early-maturing, droughtresistant varieties (IITA, 1995; Smith et al., 1997). Rapid adoption of hybrid maize in western Kenya during the 1960s and 1970s led to dramatic increases in productivity (Gerhart, 1975). White and Sitch (1994) reported yield increases in sorghum, sweet potato, cowpea, and maize in Mozambique when improved, adapted varieties were introduced.

39

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 4

40

Chapter 4

Table 4.1.

Yield increases observed from the introduction of improved varieties.

Country

Crop species

% Increase in yield

Angola Mali Mozambique Mozambique Mozambique Senegal Sudan Congo (Dem. Rep.) Congo (Dem. Rep.)

Maize Sorghum Sweet potato Maize Sorghum Cowpea Maize Maize Cowpea

46 24 61 71 133 100 53 18 108

●

Reference Nankam et al., 1996 Dembele et al., 1997 White and Sitch, 1994 White and Sitch, 1994 White and Sitch, 1994 UC-Riverside, 1994 Janson and Kapukha, 1995 Asanzi and DeVries, 1995 Asanzi and DeVries, 1995

DeVries and Olufowote (1997) analysed results from intensive, NGO-managed campaigns to increase farmer productivity through testing and dissemination of improved, adapted varieties of staple food crops in six African countries. The results of on-farm measurements of yield increases are shown in Table 4.1.

Given the absence of extensive irrigated land and continued low use of external inputs, agro-ecologically based breeding, combined with full exploitation of heterosis in the formation of adapted hybrid varieties must substitute for a Green Revolution-style approach to breeding in Africa. These aims can be significantly assisted by breakthroughs in biotechnology. The results from this effort will not be as quick to appear or as dramatic as during the Green Revolution in Asia, but, taken together, they represent an effective, rational strategy against food scarcity throughout the continent.

4.3 Crop Improvement’s Counter Arguments In spite of diligent efforts by national and international scientists alike, it must be recognized that plant breeding for many important food crops in Africa has been plagued by low adoption rates among the majority, small-scale farmers. While in some cases this is simply a matter of input- (fertilizer- and pesticide-) responsive varieties not being adopted due to the absence of those inputs on African farms, the causes are often more complex. While there is some indication of greater gains in this area over the past decade (Maredia et al., 2000), in general, adoption rates continue to present a strong challenge to breeding as a strategy for improving food security among the rural poor. This phenomenon deserves careful analysis before the proposition can be made that increased efforts at crop improvement in Africa are justified, and efforts have been made to build such an analysis into all the major sections of this book. In spite of relatively large expenditures of funds and human resources on maize breeding in most of Africa over the past three decades, only an estimated 37% of farmers regularly plant improved varieties (Morris, 1998). Similarly for sorghum and millet, Ahmed et al. (2000), in citing adoption rates in seven countries where the highest level of impact from breeding had been achieved, found that the highest level of adoption of improved varieties outside of South Africa was 35%, while the average adoption rate for

40

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 4

41

Breeding – Between an Art and a Science

these countries was 29%. Surveys on adoption of improved cassava in Nigeria, the African country where cassava breeding has arguably had its greatest success to date, show that approximately 55% of farmers who have had access to improved varieties have adopted them (Nweke et al., 1993). A system-wide review of CGIAR impact on crop genetic improvement by CGIAR (2000) revealed that in Africa: ●

●

Traditional varieties represented 70% or higher usage for sorghum, millet, beans and cassava. Wheat ranked highest in adoption of modern varieties, with approximately 63%, followed by maize with roughly 48% adoption, and rice with 40% adoption.

The balance of farmers cultivating these crops continue to plant local landraces, often altered by chance cross-pollinations with improved varieties grown in the vicinity. The aim of crop improvement is not to replace these landraces systematically with improved varieties. In most cases, they embody traits which must be conserved if new offerings are to be successfully introduced (and, as this section points out, the final decision must be left up to farmers). However, the collected observations made by scientists and farmers over the years are that in many cases landraces do not represent the best that can be achieved today. The rate of evolution of these varieties through mass selections by farmers has not kept pace with the numerous, rapid changes that have taken place in the rural settings where they are grown. Chief among these changes, of course, has been population growth, constantly creating more pressure on the land and the crops grown on it. But other changes have resulted in new conditions, as well, including the introduction of new pests and diseases resulting from greater movement of people and goods, the more frequent incidence of drought, potentially arising from global warming, and the reduction of soil fertility and soil water-holding capacity (Ngwira, 1989). As a result, many landraces suffer from susceptibility to pests and diseases and environmental stresses (Rajaram et al., 1988; Kyetere et al., 1997; Ininda and Ochieng, 2000). Among the traits farmers commonly cite as advantages in improved varieties is reduced time to maturity. But significantly reducing the time to maturity, or increasing resistance to pests and diseases, cannot be achieved in the short or medium terms by mass selection. It requires the intervention of plant breeders.

4.4 Farmer Participation in Crop Improvement The factors that influence adoption rates of improved varieties are many and varied. Certainly, access to improved varieties, given the low coverage of Africa by seed companies, is an important one which is explored later in this book. But in a context where genes for desirable traits must be introgressed into genetic backgrounds which are also desirable, ecological adaptation and farmer preferences play a major role in adoption. For these reasons, one of the most important changes in breeding programmes for developing countries in recent times has not been based on genetics at all, but on the increased emphasis placed on the participation of farmers in the variety development and selection process. This innovation has proved most critical in areas where seed markets often do not operate efficiently and farmers are therefore less able to communicate their varietal preferences through the marketplace.

41

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 4

42

Chapter 4

Aspects of farmer varietal preference are, in fact, intricately intertwined with factors which confer varietal adaptation. However, whereas varietal adaptation can be evaluated by breeders on the basis of performance factors, aspects related to farmer preference can best be evaluated by end users of the varieties (Adesina and Baidu-Forson, 1995; DeVries and Fumo, 1995; Kitch et al., 1998). Such aspects of farmer preference commonly include time to harvest (with a widespread bias toward early maturity), quality of secondary harvested components (stalks, fodder production, edible leaves), grain quality (texture, taste), and processing qualities (ease of de-hulling, pounding or grinding). Taste characteristics, in particular, tend to be overlooked by relatively affluent outsiders who consume a wide variety of food products and have access to a variety of condiments. Simpler, monotonous diets rely primarily on the flavour and texture of the food product itself (Fliedel and Aboubacar, 1998). In fact, the rationale for involving farmers directly in breeding for marginal areas is simple: diverse agro-ecologies and farmer preferences common to small-scale farming contexts tend to complicate the decision-making tasks faced by breeders. Farmers, on the other hand, understand almost intuitively which offerings among a range of choices are best for them, given their various priorities for use of the crop. Moreover, because crop varieties are usually developed by non-users (few researchers are farmers), they require regular input from farmers to be able to structure their selection indices accurately. Participatory plant breeding methods have been described by De Boef et al. (1993), Okali et al. (1994), Sperling and Loevinsohn (1996), Witcombe et al. (2000), and Thro and Spillane (2000). The most commonly cited range of reasons for involving farmers in the selection process includes the following. 1. Gaining a better understanding of farmer preferences. Farmers who consume a portion of their crop within the household may insist on taste, texture, and processing requirements which are difficult to screen for by breeding teams. Simply allowing farmers to observe their growth and taste under local conditions can avoid years of time and effort trying to ‘push’ a variety that is not acceptable for these reasons. 2. Permitting more precise selection for individual environments. Creating testing stations in every agro-ecology is often cost-prohibitive. Likewise, counting on breeders to be able to line up all the agro-ecologies and resistance and tolerance traits and decide which variety is best in each area is often not a reasonable proposition. Testing varieties on-farm and letting farmers decide which perform best can simplify the process of agro-ecology-based breeding. 3. Empowering farmers vis-à-vis the decision-making process (Jones et al., 1999). Farmers who have not found ‘improved’ varieties useful in the past can become highly interested in contributing to crop improvement when consulted. In fact, permitting their voices to be heard on these issues can be viewed as part of the broader process of democratization, worldwide. The crop improvement process embodies several opportunities for meaningful interaction between farmers and researchers, beginning with a needed, intensive learning phase when researchers become aware of agro-ecological variation and the interactions of crops and user systems. Early inbred generations (three generations of controlled breeding or later) are stages when farmers can be consulted on issues of plant type, maturity, and grain quality (Butler et al., 1995). Nevertheless, a review of participatory plant breeding programmes worldwide performed by the CGIAR (Jones et al., 1999) found

42

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 4

43

Breeding – Between an Art and a Science

that in very few cases were farmers consulted prior to the genetic fixing of traits in candidate varieties. More common was the involvement of farmers in priority setting, for example via surveys conducted prior to setting selection indices. Important conditioning factors for success of farmer participation in such schemes were: (i) the willingness and interest of farmers to set aside time for the work; and (ii) the presence of clear points of view among farmers consulted regarding the traits required in the crop species. Generally speaking, ‘participatory breeding’ to date in Africa has been mainly confined to priority setting and variety selection. Participatory variety selection usually involves exposing farmers (through scheduled visits) to a wide range, or, a ‘basket’ of candidate varieties grown by researchers in a common planting (sometimes referred to as ‘mother’ trials) followed by farmer-conducted evaluation of a smaller number of selected varieties on a large number of farms (sometimes referred to as ‘baby’ trials). Box 4.1 below offers an example of an IARC breeding programme which makes extensive use of farmer expertise. As participatory methods become more established, it is hoped that farmers will be consulted more extensively prior to the fixing of traits. A second aspect of farmer participation in crop improvement aims at greater tapping of biodiversity and the large variation that exists within landraces of crops grown in Africa. For some time it has been known that resistance genes existed in low, but useful, frequencies in a number of African crops. What has been missing was a means of isolating them, in order to feed resistance sources back into breeding programmes. Recent proposals for using rural training facilities in teaching farmers how to

Box 4.1.

Participatory rice variety selection in West Africa

When the West Africa Rice Development Association (WARDA) experienced a breakthrough in the breeding of interspecific crosses between African rice (Oryza glaberimma) and Asian rice (O. sativa), it decided to involve farmers in making selections of varieties for release. Interspecific rice varieties represented an entirely new plant type with various combinations of traits contributed by each species. The African rice genome contributed vigorous early growth for reduced competition from weeds and resistance to a number of important pests and diseases. Asian rice characters that were expressed included branching tillers, which supported more grain. In order to determine which combinations of traits were of most importance to farmers, WARDA employed a 3-year, participatory process, gradually moving from a large number of varieties to a limited number which could be presented for release and multiplication through national research programmes. In year 1 of the WARDA process, 60 lines are introduced to farmers through trials grown in farmers’ fields. WARDA scientists make three visits during the growing season to discuss with farmers the performance of each variety at critical stages of growth. In year 2, the list is narrowed down to seven varieties. Farmers evaluate each variety for various characteristics, and evluations are recorded by the WARDA Economics Unit. In the final year of participatory selection, WARDA multiplies those varieties that have been selected by farmers and offers them for sale. Interspecific varieties have consistently been among those selected by farmers in tests that included both interspecifics and ‘normal’ rice varieties. Breeders at WARDA are continuing to search through screening trials of interspecific progeny for varieties that may offer new, valuable plant types and resistance to intractable problems of rice production in Africa.

43

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 4

44

Chapter 4

identify insects and diseases represent a new means of linking farmers to breeding programmes which may lead to a new form of ‘participatory gene discovery’ (FAO/ Zimbabwe MOA, 1998). The potential impact of increasing the participation of farmers in the crop improvement process in Africa should not be underestimated. Gradually, a methodology is emerging for ensuring that the crucial ingredient of farmer preferences is included in breeding improved crops for poor farmers. Nevertheless, the complexities in terms of taking timely decisions and maintaining the rhythm and steady progress necessary to get improved lines moved through a programme, likewise, should not be ignored. And the increasing dogma over farmer participation should not be allowed to interfere with those decisions that still need to be taken by breeders. The number and range of farmers that can be included in breeding and selection programmes carried out by a small number of scientists is very limited. Transport and other costs associated with including large numbers of farmers in selection processes in each agro-ecology could limit the overall effectiveness of breeding programmes. Neither should farmer input on breeding be viewed as a panacea. There is evidence that farmers generally underestimate the importance of disease resistance in increasing and stabilizing yields (Trutmann, 1996). Only one farmer out of 243 interviewed in Cameroon identified nematodes as a cause of lodging of bananas in an area where the problem is considered by researchers to be widespread (Hauser et al., 1998). This can be especially important in areas where disease incidence is sporadic, but subject to epidemics. In light of the lessons already learned, farmer participation and other means of obtaining information from the farmer level can be viewed as catalysts to the central responsibility, which should remain with breeders. However, the most salient feature of farmer participation in crop improvement remains simple: a critical knowledge base exists among farmers that needs to be accessed in order for crop improvement to be effective in developing varieties which perform better under local farming conditions. Gaining access to this knowledge base can be achieved through a wide range of means, but inevitably requires that breeders take the time to listen to farmers and understand the ways in which they use crop species and varieties to provide food security in their households.

4.5 Crop Improvements Ground Zero: National Breeding Programmes National breeding programmes are the front lines of public sector breeding in Africa. National programmes continue to be the primary place of employment of Africa’s best-trained scientists. For many self-pollinated food crops, national programme varieties are likely to continue to be the sole source of new varieties. Regional breeding networks, though often coordinated by international or regional entities, still depend on national programmes to propose and promote the release of promising materials. National programmes which maintain a strong focus on breeding of commercial crops such as maize can also serve as an important source of new varieties marketed by private seed companies, through licensing agreements. For these and other reasons, understanding the promise and limitations of plant breeding in Africa requires an analysis of factors influencing breeding capacity at the national level.

44

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 4

45

Breeding – Between an Art and a Science

The promise of public sector breeding programmes today lies essentially in their ability to develop improved varieties for farmers who are not targeted by private sector seed companies1. In Africa, this includes the vast majority of farmers of all crops. Therefore, public sector breeding programmes play a far more important role in developing countries than developed ones. While NARSs today embody a greater number of better-trained staff than at any time previously in Africa (Pardey et al., 1997), they also suffer from a number of critical weaknesses, including strategic and financial gaps.

Strategy gaps The organization of crop improvement programmes is driven by factors related to the size of programme to be implemented, the clients to be targeted, and the kind of products to be produced (House, 1985; Fehr, 1987). In the past in Africa, many such factors were influenced by the monopolistic control maintained by public sector entities over varietal development and seed distribution. National seed companies which faced no competition had little interest in marketing a broad array of varieties finely tuned to different agro-ecosystems. Emphasis was therefore placed on broadly adapted materials, and selections were based on performance across widely differing farming conditions, even though the limitations of such strategies for developing countries were called into question by several authors (Ceccarelli, 1989; Simmonds, 1991). At least part of this emphasis was reinforced by breeding strategies in the USA, which, at least in public institutions, was driven by the search for broad adaptation, as illustrated by the following excerpt from a widely used plant breeding text: Breeding populations for wider adaptation may result in fewer varieties or hybrids. The desirability of this is obvious. Most certainly, such development could be more deliberately planned and productive if factors associated with wide adaptation were better defined. (Smith, 1966).

Deregulation of the seed sector, with its attendant diversification of products and purveyors of new varieties, coupled with more participatory approaches which attempt to offer a ‘basket’ of new varieties, as opposed to a very limited number, are both having a major impact on the ways in which public breeding programmes in Africa need to be organized. Among NARSs, several trends have emerged which point to needs for strategy adjustments. For example, increased activity by private seed companies which focus on supplying maize farmers in high-potential areas with hybrid seed can be viewed as an opportunity for national maize breeding teams to concentrate on the development of OPVs with higher levels of adaptation to different agro-ecologies. Yet, in many cases, NARs continue to devote the majority of their breeding resources to hybrid maize development. As emphasized elsewhere in this book, better targeting of small-scale farmers’ needs will require combining numerous resistance and tolerance traits. This, in turn, will

1

The opportunities which exist for public breeding programmes to serve the needs of private sector seed companies are recognized and explored in some depth in the section on Seed Systems in this book. However, it is their role – as an agency focusing on non-commercial uses of breeding – which forms the primary concern of this section.

45

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 4

46

Chapter 4

require greater collaboration among scientists trained in various disciplines, including pathology, entomology, and physiology, who, due to continued, low-input (such as fungicides, insectides and herbicides) use in Africa, are generally only able to make an impact on farmers’ lives if their focus traits are embodied in the seed. In many cases, these scientists continue to operate on the periphery of crop improvement programmes, often to the detriment of the products eventually developed. Targeting small-scale farmers calls for a much greater level of interaction of scientists and technicians from a range of plant scientists central to crop performance at the farmer level. Indeed, in some circumstances, their greater attention to factors related to crop performance at the farmer level has led to their assuming leading roles on integrated breeding efforts in Africa and other developing regions. Chapters 8 to 14 of this book focus on traits of specific significance for seven important species of food crops in Africa. While numerous traits are identified for each crop, only a subset of these is critical to crop performance in each agro-ecology. Understanding the distribution and boundaries of the various agro-ecologies within each country, defining the set of traits important within each agro-ecology, and then selecting the best-adapted parents with the best combining abilities would appear to be a logical and straightforward approach to meeting the challenge of implementing a national breeding strategy. Because of the large land area to be covered and Africa’s constant ecological variation, national programmes will be the key to implementing these strategies. They can, however, receive critical support from IARCs, both in defining agro-ecologies and in the supply of parental breeding materials. In Kenya, Uganda and Malawi recent development of new national breeding strategies has helped to revitalize programmes and focus the attention of breeding teams on producing new products. Key components of such exercises were consultations with farmers and consideration of the various agro-ecologies to be covered by the strategy. Strategy building at the national level has also been furthered through sponsoring of regional meetings wherein such subjects as strategy development and management of public breeding programmes in the context of a deregulated seed industry form the primary focus of attention.

Financial gaps Strategy development at a national level will not result in major changes in output if trained personnel and operating funds are not available for implementing breeding strategies. Studies on the structural capacity of NARSs to conduct agricultural research indicate that good progress has been made in terms of ‘staffing up’, with the number of national scientists growing at an average annual rate of 5% between 1961 and 1991 (Pardey et al., 1997). Funding to carry out research, however, has become scarcer over this period (Byerlee, 1996). In many national programmes of sub-Saharan Africa, governments provide sufficient funding to cover staff salaries (albeit at very low levels), but not the necessary operating costs. Although national research programmes were at one time a popular area of expenditure for African governments, support to agricultural research began to decline in the 1980s. By 1991, expenditure per scientist was only 66% of the 1961 level (Pardey et al., 1997). The result has been both a reduction in overall activity and output and an increasing dependence upon donor agencies for

46

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 4

47

Breeding – Between an Art and a Science

operational costs. In recent studies, funds from international donor agencies were found to account for 45% of crop improvement research expenditure in Africa (Pardey et al., 1991). For biotechnology research, the figure rises to 65% (Cohen, 1998). As access to operating funds has decreased, the result has been gradually decreasing levels of activity among breeding teams, reflected in smaller breeding programme nurseries covering fewer breeding environments. At a certain point, minimal population sizes fail to embody sufficient genetic variation to warrant continued activity (Falconer, 1989). Appropriately targeted infusions of financial support to African NARSs, therefore, will be critical to taking advantage of recent breakthroughs in crop genetic improvement. Although increased levels of funding for agricultural research from African governments would be a welcome policy development, it is questionable whether this is likely, given the current financial crisis many African governments are facing. In view of competing priorities for national budget expenditure in the areas of education and health systems, the current formula, whereby governments generally cover researchers’ salaries and donor agencies cover a sizeable portion of operating costs, may not be the worst option. In order for such a formula to function effectively, however, some key principles must be observed. First, NARSs’ policy-makers must work from effective master plans in overseeing and approving the application of donor funds. This argues for more intensive coordination of donor resources by NARS headquarters. Second, donor institutions need to become more transparent and more cognisant of the application of each others’ resources, and plan accordingly. This is particularly important in the use of resources aimed at developing end-products, as in the case of breeding. At present, there are the beginnings of a loose-knit consortium of donors (including the Swedish-funded Bio-Earn initiative, the Gatsby Charitable Trust, and The Rockefeller Foundation) which contribute to breeding and biotechnology in Africa. Informal information shared among the managers of these programmes is increasing the complementarity of funding for crop genetic improvement. However, greater levels of coordination among a wider group of donor agencies are still needed. Several authors have questioned the rationale for increased funding to NARS, especially those focusing on marginal areas, sometimes even stating there was overinvestment in such institutions (Winkelmann, 1994; Byerlee, 1996; Evenson, 2000), and advocating for a reduction in the number of crop improvement programmes. Much of this analysis has focused on the case of rice and wheat in Asia, however, where yield thresholds have been challenged and NARSs have remained relatively well-staffed and financed over the past few decades. Observations from Africa point to a rather different picture. The impact of the AIDS epidemic has certainly created a need for added training of researchers to replace those who have died or become ill (Marianne Banziger, personal communication). Second, the greater overall complexity of Africa’s crop improvement challenge described in Chapter 2, combined with dilapidated or non-existent infrastructure, may mean that crop improvement gains come at a higher financial cost in Africa than Asia. Calculating the cost of Africa’s crop improvement budget with any precision is a difficult task. In particular, researchers’ salaries and costs of their administrative support, as well as infrastructure costs, are highly variable from country to country and such information is difficult to obtain. However, calculating the operating costs of such programmes is somewhat more feasible. Setting aside for the moment the cost of formal

47

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 4

48

Chapter 4

training, and using information from The Rockefeller Foundation’s annual grantmaking reports, an average annual cost per crop per country for breeding operations can be estimated at approximately $70,000. Based on the assumption that an average of seven food crops warrant such investments on an annual basis in each country of sub-Saharan Africa, and counting a total of 41 countries, $20 million could potentially cover the operating costs of breeding operations in sub-Saharan Africa. If operating costs account for half of total costs, then a total of $40 million could potentially cover the full budget, with the exception of the cost of formal training. Adding in the costs of formal training is an equally subjective exercise, but one that is still useful for purposes of gaining an order-of-magnitude estimate of the costs involved. Again, based on seven crops in 41 countries and an average of four crop scientists per crop (but assuming that all of these would work on at least two crops), and using an estimated cost of $150,000 for a PhD programme, the cost of a formal, postgraduate training programme for crop improvement in Africa is in the order of $4.3–5.7 million annually, depending on whether one assumes a 15- or 20-year average length of career. Even making generous concessions for the costs of administering such training programmes, the total cost of formal, postgraduate training for crop improvement in Africa should not reach beyond $10 million, annually. Therefore, while recognizing the error-prone nature of such calculations, and while not wishing to attach an overly great importance on identifying a discrete cost for what is inevitably and necessarily a very disjointed and variable effort, it can nevertheless be suggested that the overall, annual cost of a serious initiative on broadly improving the genetic performance of Africa’s food crops through conventionally based, national crop improvement programmes might be estimated at $50 million, $20 million of which (based on the current model) can be covered by African governments. By comparison, in 2000, the total value of the African food aid programme administered by one US-based NGO alone was over $100 million (Walter Middleton, personal communication).

4.6 Applied Science Powerhouses: International Agricultural Research Centres Crop mandates NARSs in Africa receive critical reinforcement in crop improvement efforts from IARCs, in particular from the member centres of the CGIAR. The work of the CGIAR is carried out by 16 research centres headquartered in various countries throughout the world. Six centres – CIAT, CIMMYT, CIP (International Potato Center), ICRISAT (International Crops Research Institute for the Semi-Arid Tropics), IITA and WARDA (West Africa Rice Development Association) – currently have scientists based in Africa working on crop genetic improvement. CGIAR centres have traditionally managed gene banks and developed broadly adapted ‘source’ populations and breeding lines for use by NARSs and seed companies in selecting adapted, improved varieties. They have also carried out both general and highly focused training programmes for crop improvement specialists working at the national level. More recently, IARCs have become active in the formulation and management of commodity-based, regional crop improvement networks. The CGIAR

48

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 4

49

Breeding – Between an Art and a Science

centre contribution to NARS productivity in breeding in developing countries, worldwide, has been estimated at 30% (Evenson, 2000). They also increasingly focus on crop management issues. International agricultural research centres have considerable presence in Africa. In 1997, Africa accounted for 40% of allocations for research expenditure by the CGIAR, representing the largest single region in the world (CGIAR, 1998). Table 4.2 lists the number of full-time internationally recruited scientists currently employed by the CGIAR in Africa. Table 4.3 lists the centres’ breeding activity within the context of regional crop improvement networks. Most IARCs have actively promoted the development of networks focused on improvement of their mandate crops. These networks have based their membership on the three main regional agricultural research coordination bodies, CORAF (West Africa), ASARECA (East Africa) and SACCAR (Southern Africa). International agricultural research centres continue to serve an important purpose in crop genetic improvement in Africa. They have broadly improved the genetic potential of germplasm adapted to Africa through the introgression of novel traits and increased yield potential. In the case of maize and, to a lesser extent, sorghum, they have also developed advanced, inbred lines for use in the formation of commercial, hybrid varieties adapted to all the major subregions. Finally, they have built up and maintained extensive African germplasm collections of all the major food crops, a task which, due to insecurity in a large number of countries, could not have been assured by NARSs or any other group. IARC breeding programmes have had a major positive impact on agricultural productivity in Africa. Their continued support is vital to achieving greater gains in the future. Still, adoption rates of improved varieties lag behind that which might be expected given IARCs’ extensive effort on crop improvement in Africa, and more effective approaches must be sought. There appears to be a gap between IARCs and NARSs, where NARSs have not employed IARC-bred ‘source’ materials in developing finished varieties or been able to use breeding methodologies promoted by IARCs. In many cases, NARSs have continued to rely primarily on their own, relatively narrow germplasm base. In other cases, they have failed to mount breeding programmes at all, in spite of possessing scientists trained to the same levels as IARCs. In the absence of this critical breeding linkage, source materials have sometimes been presented as adapted, ready-for-release varieties, and national ‘breeding’ programmes relegated to the role of testing IARC-bred material. Table 4.2.

IARC crop improvement scientists in Africa.

Institute

Scientists in crop improvement

CIAT CIMMYT CIP ICRISAT IITA WARDA Total

6 7 4 15 35 9 76

49

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 4

50

Chapter 4

Table 4.3. Centre

Scope of IARC crop improvement responsibilities in Africa. Mandate crops

Primary IARC breeding sites /regional focus

Banana/plantain Oné, Nigeria/West Africa Kampala, Uganda/East Africa Cassava Ibadan, Nigeria/West Africa Kampala, Uganda/East Africa Bvumbwe, Malawi Cowpea Kano, Nigeria/Africa Maize Ibadan, Nigeria/West, Central Africa Bouaké, Côte d’Ivoire/West, Central Africa CIAT Beans Kampala, Uganda/East Africa Lilongwe, Malawi CIMMYT Maize Harare, Zimbabwe/Southern Africa Addis Ababa, Ethiopia/ African Highlands Nairobi, Kenya/East Africa Wheat Testing only/Southern Africa Addis Ababa, Ethiopia CIP Potato Testing only/Africa Sweet potato Nairobi, Kenya/Africa ICRISAT Sorghum Bamako, Mali/West Africa Nairobi, Kenya/East Africa Bulawayo, Zimbabwe/Southern Africa Millets Bulawayo, Zimbabwe/Southern Africa Bamako, Mali/West Africa Pigeon pea Nairobi, Kenya/Africa Groundnut Lilongwe, Malawi/East and Southern Africa Bamako, Mali/West Africa WARDA Rice Bouaké, Côte d’Ivoire/West Africa (non-irrigated) St Louis, Senegal/West Africa (irrigated) Entebbe, Uganda IITA

Networks MUSACO BARNESA CEWARRNET EARRNET SARRNET RENACO WECAMAN

ECABRN SABRN MWIRNET, SADLF AHI ECAMAW MWIRNET ECAMAW PRAPACE PRAPACE WCASRN/ROC ARS ECARSAM SMINET SMINET WCAMRN/ ROCAFREMI

INGER ECSARRN

Lingering low yields among African farmers for crops such as maize and rice, where adoption of improved varieties has been appreciable, call into question the overall value of the improved germplasm to local farmers, and whether the public crop improvement ‘system’, including the combined efforts of both IARCs and NARSs, cannot be improved upon. While, for lack of better options, offered materials (both unfinished, IARC breeding lines and unenhanced, NARS varieties) may represent the best improved varieties available, they do not represent the full extent of what modern breeding could normally do for farmers. Their lack of key identifiable traits (drought tolerance, maturity, grain type, disease incidence, etc.) may reduce their acceptance by farmers and

50

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 4

51

Breeding – Between an Art and a Science

diminish the value of the crop improvement system, overall (Simmonds, 1991). An observation from the recent, system-wide review of the IARC contribution to varietal development (Evenson, 2000) perhaps captures the challenge most succinctly: Not all germplasm produced in an IARC program is of equal value to all NARS programs. The proportion of germplasm relevant to a given NARS program depends on the differences in soil and climate conditions in the NARS region and in the IARC location and on the efforts of IARC program to actually ‘target’ germplasm for the NARS program. (Evenson, 2000)

Increasing the interface between IARC and NARS breeding programmes is necessary to realize the full potential of plant breeding in Africa. There is no doubt that the provision of source breeding materials and technical backstopping by IARCs can improve the success of the national programme. The relationship between them needs to be broadened and strengthened so that NARSs recognize the value of IARC breeding materials and IARCs understand the agro-ecological and institutional constraints NARSs face. Weaknesses in NARS’ breeding capacity need to be eliminated so that investments in IARCs can pay off. Likewise, IARC perception and understanding of agro-ecologies and farmer preferences needs to be strengthened so that source materials reflect more closely the priorities identified by farmers and breeding programmes. Finally, IARCs serve a major need in mounting genetic improvement programmes aimed at overcoming intractable constraints to production which may be beyond the financial and scientific reach of national programmes. Thus, while IARCs account for a small portion of the total work force, they are a key component for crop improvement throughout the continent. This argues for an increase in the number of full-time IARC scientists engaged in breeding in Africa.

Capacity building In 1961, there were 2000 full-time agricultural researchers in Africa. By 1991 the number had risen to 9000. Approximately 65% of agricultural researchers in 1991 had attained postgraduate degrees, compared with 45% in 1961 (Pardey et al., 1997). As NARS scientific staff have gained higher levels of training, the central task of IARCs engaged in breeding in Africa has evolved. NARS scientists returning from training overseas have been equipped with strong theoretical backgrounds which can be put to use in developing new products for farmers. However, PhD programmes in the fastmoving field of genetics provide little background in methods of practical breeding. Moreover, many returning scientists have never managed full-scale breeding operations. Building practical breeding capacity – including the science policy tasks discussed above – is therefore an increasingly important mission for IARCs.

4.7 Breeding Linkages Within a Continuum of Crop Improvement Activities The possible integration of biotechnology research, breeding, and seed systems in developing and delivering new genetic technologies for small-scale farmers in Africa is

51

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 4

52

Chapter 4

Fig. 4.1.

Collaborative model for overcoming genetic constraints in African crops.

shown in Fig. 4.1. It proposes a process by which identified production problems can be addressed using a range of research methods. Examples of problems deemed ‘routine’ might include the appearance of a new disease, for example, the appearance of grey leaf spot disease of maize in eastern and southern Africa in the past few years, for which sources of resistance have been identified. Intractable problems arising in marginal environments most likely will require specialized research, such as that conducted by a different category of institution, herein referred to as ‘advanced research institutes’ (ARIs). Intractable problems might include drought tolerance, parasitism by Striga, or attack by insect pests. These are problems for which progress via conventional breeding techniques has proved difficult or very slow, and for which no reliable means of selection are available. Here, NARS’ work must be linked with that of IARCs and ARIs.

4.8 Managing the Complexity of Adaptation Chapter 2 explored some of the complexities of designing crop varieties with specific adaptation advantages in low-input farming systems. Managing this complexity will require a systematic approach to understanding the nature and boundaries of agroecologies. In most cases, this will be done in stages, and at varying levels of resolution. Table 4.4 lists some of the mega-environment characteristics for selected crops.

4.9 An Emerging Paradigm for Breeding in Africa During the 20-odd years following independence in most African countries, monopolistic, public seed companies were managed and mandated by government to serve the needs of all farmers. With a single outlet for seed of improved varieties, national breeding programme strategies were more or less set by the marketing interests of the

52

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 4

53

Breeding – Between an Art and a Science

Production ecologies of Africa for selected crops.

Table 4.4.

Predominant region

Crop

Agro-ecology

Maize (CIMMYT, 1990)

Lowland tropical, Northern Guinea Maize streak virus early savannah, Congo (MSV), southern Basin, southern leaf blight, stalk Mozambique rot, ear rot Lowland tropical, Southern Guinea MSV, southern intermediate savannah, Congo leaf blight, ear rot, Basin stalk rot Lowland tropical, West African MSV, polysora late forest zones rust, southern leaf blight, ear rot, stalk rot Mid-altitude, early Northern Turcicum leaf Mozambique blight, grey leaf spot (GLS), MSV, ear rot Mid-altitude, Zimbabwe, MSV, ear rot, intermediate Malawi, GLS, turcicum Mozambique leaf blight, common rust Mid-altitude, late Nigeria, Turcicum leaf Cameroon, blight, GLS, Zambia, eastern common rust, Angola, Tanzania, MSV, ear rot Uganda, Kenya, Ethiopia Highland, early/ Western Kenya, Turcicum leaf intermediate Great Lakes blight, GLS, common rust, MSV, ear rot Highland, late Ethiopia, Kenya, Turcicum leaf Great Lakes, blight, GLS, Tanzania common rust, ear rust, MSV, stalk rot Humid/ Côte d’Ivoire, Weeds, acidity, sub-humid zone Guinea, Sierra blast, drought, Leone nitrogen deficiency Rain-fed lowland Nigeria, Benin, Weeds, water Liberia, control, rice Mozambique, yellow mottle Tanzania virus (RYMV), nitrogen deficiency, drought

Rice (WARDA, 1998)

Constraints

53

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 4

% of total area 13

10

23

1

15

27

0

10

40

38

54

Chapter 4

Table 4.4. Crop

continued. Agro-ecology

Predominant region

Constraints

Irrigated

Cameroon, Nitrogen Nigeria, deficiency, Tanzania, Kenya weeds, RYMV, iron toxicity, nematodes, gall midge Sahel irrigated Senegal, Mali, Nitrogen Niger, Burkina deficiency, cold, Faso salinity, weeds, alkalinity Mangrove Coastal West Sulphate acidity, swamp Africa salinity, crabs Deep Northern Sahel Water control, low water/floating yielding varieties, low fertilizer use efficiency Sorghum Southern Guinea Nigeria, Ghana, Anthracnose, (ICRISAT, 1992; savannah Chad, Cameroon, sooty stripe, Fred Rattunde, (> 1000 mm) Sudan smut, Striga personal communication) Northern Guinea Northern Nigeria, Shoot fly, stem savannah northern Ghana, borers Chad, southern Burkina Faso Striga, downy Sahel zones Mali, Burkina mildew (< 1000 mm) Faso, Niger, Nigeria Eastern and Kenya, Tanzania, Stem borer, grain mould, midge, southern Africa Zambia, shoot fly, drought Zimbabwe, Mozambique, Botswana, Namibia Heat and drought, Millet (ICRISAT, Sahel zones Chad, Niger, head miners, 1992, and Fred Mali, Senegal Striga Rattunde, personal communication) Northern Guinea Nigeria, Burkina Downy mildew, savannah Faso, Chad, Mali, stem borers, drought, Striga semi-arid East Africa Downy mildew, Southern Guinea Ghana, Togo, drought savannah Nigeria

54

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 4

% of total area 5

7

4 6

30

30

20

20

40

20

15

55

Breeding – Between an Art and a Science

Table 4.4.

continued.

Crop

Agro-ecology

Cassava (Henry and Gottret, 1996)

Southern Africa, East African Highlands Lowland humid tropics

Predominant region

Constraints

Botswana, Namibia, Downy mildew, Zimbabwe, Ethiopia drought

West African forest Mosaic virus zones, Congo (ACMV), Basin, Mozambique bacterial blight, anthracnose Lowland ACMV, bacterial sub-humid blight, spider Tropics mite, drought, mealy bug Semi-arid Sahelian zones, Drought, tropics southern Africa anthracnose, bacterial blight, burrowing bug Mid-altitude East and southern ACMV, spider zones Africa, Cameroon mite, bacterial blight, burrowing bug, termites Sub-tropic South Africa Drought, bactezones rial blight, mealy Banana bug, spider mite (INIBAP, 1995) West African Guinea savannah, Black sigatoka, lowland transitional zones, weevils, bunchy Congo basin top virus East African Uganda, western Black sigatoka, Highland Kenya, Great Lakes nematodes, weevils, fusarium, banana streak virus Lowland Coastal east Africa Mid-altitude South Africa, Fusarium Cowpea commercial Zimbabwe (Laurie Kitch, Forest Zone Coastal West Africa Weeds, maruca personal and Guinea pod-borers, communication) savannah thrips, foliar disease Northern Guinea Coastal West Africa Bruchids, pod savannah bugs, thrips Sudan Nigeria, Ghana, Aphids, bacterial savannah Benin, Togo blight, mosaic viruses, bruchids Sahelian zones Senegal, Mali, Bacterial blight, Striga, aphids, Niger, Burkina Macrophomena, Faso, Chad bruchids

55

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 4

% of total area 15

35

36

8

10

10

36

57

6 1 5

10 40

30

56

Chapter 4

Table 4.4.

continued.

Crop

Agro-ecology

Cowpea (cont’d)

Mid-altitude, humid

Predominant region

Kenya, Tanzania, Uganda, northern Mozambique Mid-altitude, dry Kenya, Zimbabwe, Botswana

Constraints

% of total area

Thrips, pod bugs, viruses, bruchids

5

Thrips, pod bugs, viruses, bruchids

10

seed company. In the absence of competition from other suppliers, most seed companies did the logical thing: in order to keep marketing and operational costs at a minimum, they marketed a minimal number of improved varieties to as broad a grouping of farmers as possible. This restricted outlet for new varieties did little to encourage breeders to create the steady flow of increasingly well adapted varieties which is the norm in deregulated seed markets. Rate of release of new varieties stagnated, accounting for the fact that many food crop varieties in use in many African countries are well over 20 years old. Figure 4.2 shows the rate of release of new maize varieties in selected eastern and southern African countries during the period 1960 to 1995. Following deregulation of many seed sectors during the late 1980s and early 1990s, increasing numbers of seed companies were allowed to compete for the same market, with the result that the rate of release of new maize varieties increased sharply and has maintained itself during the late 1990s (data not shown). Increased competition among seed companies will continue to fuel greater levels of attention to farmers’ needs in Africa, with the net result being higher levels of activity in the area of breeding. Thus, the old emphasis on varieties with broad adaptation acceptable to a maximum number of farmers can be replaced with an approach that emphasizes increased adaptation within a given agro-ecology. In this kind of market, one plausible hypothesis is that breeding programmes (both those attached to seed companies and those attached to NARSs which license their varieties with seed

Fig. 4.2. Rate of maize variety releases in Kenya, Malawi, Tanzania and Zambia, 1961–1995. Source: Zambezi (1997).

56

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 4

57

Breeding – Between an Art and a Science

companies) which pay closer attention to environmental variation stand to experience increased demand for their products. If so, this would follow a trend among privatized seed markets such as that of the USA, where seed companies often test experimental varieties in over 1000 sites (Jensen, 1994). Multi-year, multi-location testing of varieties can generate considerable understanding among breeding teams related to the differences among agro-ecologies (Jensen, 1994). As agro-ecologies become better known, breeding strategies emerge which anticipate the needs of farmers, with information feeding back to the selection of parents. For a commercial crop with considerable potential seed sales such as maize, this may come about naturally as a result of competition among companies. For other, non-commercial crops, such strategies will need to be constructed within the public sector. The emerging new paradigm, then, is characterized by one wherein multidisciplinary crop improvement teams systematically begin to work backward from the farmers’ needs – dictated in turn by agro-ecological and end-use characteristics – to the formation of selection strategies and choice of parents for the formation of new breeding populations most likely to bear positive results in as brief a period as possible. Within such an approach, farmer participation is critical throughout the process.

4.10 Africa Breeding Challenges Summary With notable exceptions in very poor countries and in countries where protracted periods of instability have depleted public sector ranks, NARSs in Africa have achieved the needed capacity to perform most of the routine breeding work entailed in developing new varieties. Participatory techniques of breeding are progressively being incorporated into national breeding programmes, offering a potential solution to the perennial problem of incorporating farmer preferences into new offerings. The next phase of their challenge is in securing resources and instituting programme strategies that produce a steady stream of new varieties. At another level, the challenge is in developing functional relationships with private seed companies that result in mutually beneficial licensing agreements for commercializing new, public varieties. If breeding programmes can undertake these kinds of reforms and pursue them vigorously, there is genuine hope that public sector plant breeding can fulfill its potential in sparking increases in productivity among Africa’s millions of small-scale farmers. The challenges perceived by IARCs should closely resemble those being addressed by NARSs, namely, creating a steady stream of improved, adapted breeding materials. However, they should aim at playing a facilitative role rather than a lead role in achieving those aims. With few exceptions, national programmes in Africa have demonstrated their ability to develop new varieties using conventional breeding methods. Increasingly, these programmes are staffed by scientists with identical training to those employed by international research centres. Breeding well-adapted source materials for use in combination with local materials in boosting yield potential or resistance to pests, diseases, or environmental stress is a critical role for the IARCs. However, an equally important role exists in assisting the development and implementation of nationally based breeding strategies.

57

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 4

5

Biotechnology: Expanded Possibilities

5.1 Overview Plant biotechnology spans a broad and rapidly expanding range of research techniques aimed at direct control over the genetic make-up of crops through the manipulation of plant cell cultures and through the analysis and isolation of DNA. The most common applications of biotechnology to plant breeding can be separated into five broad categories: tissue culture, DNA marker technology, genetic engineering, genomics and bioinformatics. Tissue culture involves in vitro regeneration of whole, functioning plants from single cells or small portions of parent plants. Marker technology allows many of the loci, genes, and alleles that are important in crop improvement and already present in the gene pool available to breeders to be identified, located on the chromosomes, and more effectively transferred via conventional crossing. It enables interactions between genes to be determined and facilitates the identification and use of new favourable alleles from wild relatives. Its most useful form, marker-assisted selection (MAS) involves whole-plant selection based on DNA markers closely linked to genes of interest. Genetic engineering refers to the in vitro transfer of genes into plant cells followed by regeneration of whole plants containing these genes in the germline (Hoisington et al., 1998). As laboratories become more fluent with biotechnology methods of research, these three areas are increasingly being used in synergistic combination with each other. More recently, a new application of biotechnology, termed ‘genomics’, has evolved out of work in molecular genetics. Plant genomics can be described as identifying the function of all of a plant’s genes and how they work together to determine when, where, and why traits are expressed. Using gene chip (the plotting of thousands of gene segments on plates or ‘micro-arrays’) technology the interrelationships and interactions between genes and whole pathways can now be studied, and should help breeders to create varieties with more exact combinations of desired traits (Wang et al., 2000). Such aims have been facilitated in part by the development of methods for isolating ‘expressed

59

59

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 5

60

Chapter 5

sequence tags’ – short segments of gene transcripts, which have been sequenced and can be used to help identify the level of expression and function of the genes that generated them. Because gene-encoding sequences represent only 10% of most genomes, this method allows researchers to concentrate on the more informative portions of genomes. The international effort currently under way to sequence the entire rice genome as a model cereal genome should be completed in 2 to 3 years. It is already generating full sequence data and is providing a wealth of useful new information for genomics research. Because the genes that code for numerous plant traits and processes are quite similar across species, this knowledge can be applied to genetic research on other crops. It is widely believed that genomics will eventually replace the comparatively imprecise method of identifying genes through markers, which usually do not identify the gene itself. Stemming from the explosion of information on plant genomes, yet another new application, that of bioinformatics, has become of primary importance. Bioinformatics, as the term implies, is essentially the management of information on gene structure, position and function in ways that allow the data to be used to make broader interpretations related to the behaviour of whole organisms. Since cereal genomes are very similar in gene content and gene order, bioinformatics should facilitate comparisons and sharing of information across crop species. This, combined with the fact that bioinformatics requires powerful computational capabilities, sophisticated software, networking, and specialized human resources, argues in favour of having bioinformatics centres that work on several crops. Together, genomics and bioinformatics are aimed at eventually allowing researchers with access to the information to understand the functioning of whole genomes. While various methods of directly manipulating DNA and transferring it to plants have been in use for nearly two decades, the power of biotechnology to transform agriculture only became apparent following the release of several transgenic varieties of staple food and fibre crops – grains, legumes and cotton varieties resistant to insects and herbicides. The response of farmers was dramatic, and plantings of transgenic varieties increased rapidly in countries where they have been commercialized. While yields of some transgenic crops were higher, the major advantages to farmers were significant overall reductions in the cost of production and greater flexibility in rotating production with other crops. In fact, transgenic varieties looked set to cover most of developed country agriculture until controversy over their importation and testing broke out in Europe. Biotechnology is already contributing to smallholder agriculture in several ways. Tissue culture is facilitating the rapid propagation and dissemination of clean planting material of vegetatively propagated crops (e.g. banana, cassava, potato, sweet potato and yams). Anther culture and the creation of doubled haploid plants are speeding the process of producing genetically stable breeding lines (e.g. rice, wheat and barley). Anther culture also helps overcome sterility problems in progeny resulting from wide crosses made within species (e.g. Indica rice × Japonica rice) and between related species (e.g. Oryza sativa × Oryza glaberrima). Marker-assisted selection (MAS) is speeding the process of back-crossing desired genes into locally well adapted cultivars (e.g. resistance to streak virus in maize, yellow mottle virus in rice, and African mosaic virus in cassava). MAS is also leading to more durably resistant varieties by facilitating the pyramiding of different resistance genes in the same variety (e.g. more durable blast resistance and

60

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 5

61

Biotechnology: Expanded Possibilities

more durable gall midge resistance in rice). To date, however, the only transgenic crop being grown by numerous smallholder farmers is insect-resistant (Bacillus thuringiensis) Bt cotton in South Africa, Mexico and China. It has led to significant reductions in pesticide use and costs, and is much appreciated by these farmers. The technological gap which separates African agriculture and that of much of the rest of the world today is perhaps most starkly apparent in the status of biotechnology research. Nearly one-third of cropland in the USA in 1999 was planted to transgenic crops (James, 1999). A survey of seed companies in Europe in 1999 showed that one-third of all companies already employ genetic engineering in their crop improvement programmes and by 2002 80% of all seed companies will employ biotechnology (Arundel et al., 2000). In India, there are over 30 agricultural research teams making routine use of plant biotechnology (Dillé, 1997), and in the rest of Asia, even relatively underdeveloped countries such as Vietnam and Indonesia have burgeoning biotechnology laboratories making routine use of molecular mapping techniques, transformation technologies and other applications. Yet when this book was drafted, there were only three national-level research laboratories in sub-Saharan Africa (outside of South Africa) using molecular applications of biotechnology. The implications, in terms of Africa’s capacity to innovate and advance its food production systems in a way similar to the rest of the world, must be recognized. However, in spite of the delayed uptake of biotechnology in Africa, such comparisons give a rather distorted image of the current potential for biotechnology to affect the lives of the rural poor in Africa, for several reasons: ●

●

●

●

Many African scientists have received training in biotechnology research in advanced research facilities and are ready to apply the techniques on the crops they know; Several biotechnology products (including transgenic banana, cassava, maize and rice) aimed at African agriculture have been developed in outside laboratories and await only the appropriate regulatory approvals for importation; Available applications of plant biotechnology are highly suited to managing genetic traits of importance to tropical agriculture, such as resistance to insect pests, diseases, and environmental stress; Crop yields in Africa are so low, in part due to lack of technology, that even relatively modest improvements in technology can have significant local impact.

In view of Africa’s lagging status in the development and adoption among farmers of conventionally produced, modern, improved varieties, adding molecular methods of crop improvement may appear of lower priority at this time. However, it would be a mistake to delay the installation and application of biotechnology for plant breeding in Africa. Judging by the very rapid rates of adoption of transgenic varieties in countries where they have been introduced (James, 2000) and the increasingly routine use made of other biotechnology applications in breeding programmes in the developed world, farmers around the world can benefit from the use of biotechnology in crop improvement. To deny African farmers the benefit of these kinds of products would only put the continent further behind in terms of the access its farmers have to modern agricultural technology. The result would probably be continued low yields and higher food costs than those enjoyed by the rest of the world. Therefore, while research planners in Africa

61

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 5

62

Chapter 5

as elsewhere must strive to create a balance between investment in lower-cost, easier-to-use, conventional methods and more complex methods of crop improvement, there is significant value in gradually introducing biotechnology to African crop improvement programmes. One way or another, African governments will need to make decisions concerning agricultural biotechnology. To do so wisely there will need to be African scientists who understand and can use the technology when appropriate.

5.2 Areas of Plant Biotechnology Research While five areas of plant biotechnology are described above (tissue culture, markerassisted selection, genetic engineering, genomics and bioinformatics), the application of only three of these will be reviewed in relation to biotechnology in Africa. Although the latter two are of immense potential importance and undoubtedly can make significant contributions to African crop varieties, the authors believe that they fall into a category of upstream research which cannot be justified within the context of NARSs aimed at reducing hunger in Africa.

Tissue culture Tissue culture is based on the ability of some organisms to regenerate themselves from a single cell or small clumps of cells. This is possible because the information necessary for whole-organism growth, differentiation and regulation is present in each cell of the organism. Tissue culture has been most widely used in Africa as a means of generating disease-free propagules of vegetatively reproduced crops such as cassava, banana, potato, sweet potato and yam. Such micropropagation is the most commonly applied form of biotechnology in Africa (Cohen, 1998). Cost is usually the key factor in determining the utility of tissue culture in commercial agriculture. Methods of meristem culture can be adapted to local conditions such that facility expenses are low, yet field (post-flask) survival rates are high. Tissue culture is in routine usage in numerous laboratories in Africa, particularly in those countries where agriculture is based on cultivation of clonal crops, such as the humid regions of west and central Africa. In addition, Kenya has used tissue culture for rapid propagation of improved varieties of potato, pyrethrum and sugarcane since the mid-1970s (Odame and Kameri-Mbote, 2000). Advances in tissue culture techniques over the past decade have resulted in most crops being regenerated from undifferentiated cells in vitro. Tissue culture is an important tool in transformation methodologies discussed below. Tissue culture has been coupled with breeding programmes (as in the case of anther culture of rice) to speed up the regeneration, fixation and duplication of genotypes of interest. Examples of the use of tissue culture in crop improvement in Africa include: ●

A new rice plant type for West Africa resulting from embryo rescue of wide crosses made between Asian rice (Oryza sativa) and African rice (Oryza glaberrima) followed by anther culture of the hybrids to stabilize breeding lines (WARDA, 1998).

62

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 5

63

Biotechnology: Expanded Possibilities ●

●

Bananas propagated from apical meristem in Kenya have been shown to have increased vigour and suffer lower yield loss from weevils, nematodes and fungal diseases (ISAAA, 1997). Non-governmental organizations involved in supply of planting material of potatoes, sweet potatoes, cassava and banana to farmers affected by conflict in Burundi multiplied planting stock through contracts with public laboratories that used tissue culture to increase rapidly the number of clean seedlings available (DeVries, 1999) (see Plate 6).

Marker-assisted selection (MAS) The most common application of molecular genetics in plant breeding is markerassisted selection, which allows detection and localization within the plant genome of genes controlling traits of interest to researchers. MAS applications are based on two principal methods: (i) comparison of the differing products of reactions from DNAcleaving enzymes on DNA of alternative genotypes having differences in their base pair compositions that alter cleaving sites (RFLP technology); and (ii) comparison of patterns from the synthesis of repetitive sequences of DNA in alternative genotypes. The latter uses relatively quick and inexpensive polymerase chain reaction (PCR) technology and is preferable as a practical breeding tool for scoring numerous plants. Markerassisted selection was cited by CGIAR centres as the biotechnology application they expect to be most useful in the future (CGIAR, 2000). It is also currently the application on which the CGIAR is concentrating the greatest amount of resources (MAS accounts for 28% of CGIAR biotechnology expenditures, the largest single item, followed by genetic transformation, at 22%) (CGIAR, 2000). Positive identification of genes within single plants allows for more precise selection of the most favourable genotypes. Localization of genes along the chromosomes of plants permits the construction of gene maps. Isolation of genes via molecular genetics can permit their cloning in preparation for transfer using genetic engineering. However, it is important to note that all methods of genetic marker selection rely on accurate correlation being made between a given genotype’s laboratory results and field level performance. Thus, marker-assisted selection cannot succeed without an attached, highly functional plant breeding capability. MAS has a multitude of applications to crop improvement, but has proved most useful as a tool to speed back-crossing of qualitative traits (those controlled by a single gene or few genes) (Young, 1999). With marker-assisted back-crossing a desired introgression can be achieved in four to six generations rather than ten or more because the markers allow for more rapid elimination of undesired portions of the donor genome while facilitating retention of the desired segment. In order to maximize genetic variation for a given, quantitative trait (one controlled by multiple genes), individual genes controlling the trait, termed quantitative trait loci, or ‘QTLs’ must be present in their most favourable format. By mapping these loci and tracking their occurrence in large numbers of genotypes, it is possible to identify those individuals with the most favourable make-up. As several traits can often be traced using the same DNA, MAS holds the promise of more effective combining of valuable traits within a given crop variety. At present in sub-Saharan Africa, MAS

63

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 5

64

Chapter 5

laboratories are under development in Zimbabwe, Kenya, Côte d’Ivoire, Nigeria and South Africa. Marker-assisted selection should be considered as a breeding tool when the following criteria are met with regard to the trait of interest. ● ● ●

●

The trait is important. Phenotypic screening is reliable and accurate but difficult and/or expensive. There already exists a large plant population segregating for the trait, preferably with a simple pedigree. Numerous mapped markers covering the whole genome are readily available.

Mapping of QTLs governing quantitative (multi-gene) traits, followed by their selection based on detection of tightly linked molecular markers has been posited as a means of improving the management of quantitative traits in breeding programmes (Knapp, 1991; Dudley, 1993; Tanksley, 1993). While in principle this method could become of great use in transferring complex traits (such as Striga resistance) from source materials to improved varieties, in practice, this use of molecular markers has not as yet proved feasible (Young, 1999). In addition to the cost of developing the genetic maps, different QTLs have been detected for the same trait measured in different sites or in progeny from different parentage (CIMMYT, 2000). This is an area that deserves review and analysis, so that developing-country laboratories can decide whether QTL mapping should be a priority for them. One approach that has been suggested by researchers at CIMMYT (2000) is to analyse QTLs for complex traits in up to five different segregating populations and up to 20 different environments leading to the identification of consensus regions for all genotypes. Marker-assisted selection strategies could then be proposed which eliminated the need to construct new linkage maps for each new cross. If successful, this will represent a major step forward in the employment of MAS strategies for crop improvement. Examples of the ways in which MAS may be applied to assist poor farmers in Africa include: ●

●

●

Back-crossing the gene for resistance to maize streak virus (MSV) into well adapted local varieties. Excellent genetic resistance to MSV has been known for over 20 years but not widely deployed. The locus of the resistance has now been located on chromosome 1 and closely linked markers identified. Using markers it should be possible to introgress this resistance into numerous well adapted local varieties. This would be an excellent first use of molecular markers in national breeding programmes. Mapping of QTLs for resistance to weevils. Weevils are storage pests, which destroy large portions of the harvest among Africa’s poorest farmers who lack modern grain storage facilities. Natural resistance exists in several crops, however screening for weevil damage among a large number of varieties is very laborious. Being able to identify varieties with the genes for weevil resistance in the laboratory would represent a major advantage for breeders. Likewise, drought tolerance is a complex trait, controlled by many QTLs, that is difficult to measure in the field in many seasons, simply because rains occur and all stress symptoms disappear. Identifying molecular markers for this trait in a range of cereal crops could permit the development of a wide range of materials with the drought tolerance trait.

64

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 5

65

Biotechnology: Expanded Possibilities

Genetic engineering Genetic engineering (also called genetic transformation) involves the direct transfer of DNA between different varieties, species, genera and even between plants and animals. It is the more invasive of the three primary applications of plant biotechnology and therefore the one subject to the highest level of biosafety regulation. The two most common methods of gene transfer are the intentional infection of recipient plant tissue by Agrobacterium, nature’s own genetic engineer, and via bombardment of plant tissue with particles coated with foreign DNA. Agrobacterium cells carry plasmids and can cause a portion of the plasmid, called ‘the transfer’ or ‘tDNA’, to become incorporated into the plant genome the Agrobacterium infects. Through recombinant DNA technology, scientists can subtract deleterious genes from and add beneficial genes to the tDNA prior to infection. Agrobacterium-mediated transfer was originally developed as a technique for transforming dicotyledonous plants, but successful use of the technique has now been reported for most cereal crops. Its major advantage over particle bombardment is that it usually introduces just a single copy of the new genes to the plant genome. Genetic engineering is most commonly employed as a means of introducing a new trait or variation for a given trait when naturally occurring variation is absent or insufficient within the target crop species. A useful example is given by a number of crops, including cotton, maize, potatoes and rice, which lack effective host plant resistance to chewing insects. These crops have been transformed with gene constructs of a protein produced by the bacterium Bacillus thuringiensis (Bt) that interferes with the digestive systems of several genera of insect pests that chew and burrow inside the plant and are therefore difficult to control with pesticides. Progeny of transformants have shown significantly increased resistance to chewing insects (Barton et al., 1987; Ghareyazie et al., 1997). To date in sub-Saharan Africa genetic transformation of plants has been achieved only in South Africa and Nigeria. In South Africa smallholder farmers are reported to have adopted Bt cotton with great success (J.F. Kirsten, personal communication). Also, for some outbreeding species like banana and cassava, where back-crossing is problematic due to strong in-breeding depression, genetic transformation may be more effective than conventional crossing as a means of moving desired genes into numerous well adapted local varieties. Examples of the ways in which genetic engineering might be applied to crop improvement in Africa include: ●

●

Providing resistance to insect pests of cowpea. Cowpea is a highly nutritious crop that grows well in marginal areas of Africa providing protein and vitamins to some of the world’s poorest rural people. Its one serious constraint is susceptibility to chewing and sucking insects. No sources of resistance are known to exist within cultivated or wild cowpea genomes (Fatokun et al., 1997). Transferring a gene into cowpea which confers broad-based resistance against such insects would reduce losses to these pests for a large group of Africa’s poorest farmers. Making rice a new source of dietary pro-vitamin A. Rice is an important staple food in West Africa and its production is growing in other regions of the continent. European scientists have recently added genes to rice that enable it to synthesize

65

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 5

66

Chapter 5

nutritionally significant levels of pro-vitamin A (β-carotene) in the grain (Ye, 2000). Scientists at the West Africa Rice Development Association have produced a new rice plant type from crosses between African rice and Asian rice which combine desirable characteristics of both. These new rices are highly desired by farmers and are spreading rapidly. If genes for β-carotene production could be crossed into the new plant type, a powerful driving force would exist for disseminating a new source of pro-vitamin A to populations that need it.

5.3 The Interface Between Biotechnology and Breeding The descriptions above make apparent the wide differences between alteration of crops through plant breeding and the direct management of traits through biotechnology. What is less obvious is the myriad ways in which biotechnology and plant breeding interact. In fact, crop biotechnology is directly dependent upon plant breeding for its impact. To appreciate the extent of the relationship between the two it is necessary to explore the concept of the ‘phenotype’. A variety’s value to a given agricultural system is based on its phenotype. An organism’s phentoype is generally understood to arise from the combined forces of its genetic make-up (its genotype), its environment, and the interaction of the two. Because crop varieties are grown in different, relatively uncontrolled environments, knowing their genetic make-up is critical, but insufficient in determining whether any given individual will be of use in local farming systems. To make this determination, the variety must be evaluated in numerous growing environments. Often, this evaluation process involves making final selections, or ‘fine-tuning’, of the crop for final release as a commercial product. It is perhaps an unfair generalization to state that plant breeders manage the phenotype while biotechnologists manage the genotype when, in fact, plant breeders have referred to candidate genotypes based on carefully maintained pedigrees, knowledge of gene expression and quantitative genetics, and the use of morphological markers for nearly a century. However, plant breeders are primarily focused on the ways plants reconstruct themselves phenotypically following a cross between two known genotypes. Biotechnologists, on the other hand, are more focused on assembling genetic constructs which have the basis for a given type of performance. Molecular markers represent a virtually limitless set of loci for qualitative and quantitative genetic analysis in any organism and are neutral with respect to both phenotype and environment. However, initially to establish genetic linkage between DNA markers and the loci for important traits requires the ability to observe and measure reliably and accurately the phenotype in segregating populations under different environmental conditions. While identifying genetic markers and performing transformations are strictly laboratory based activities, identifying valuable phenotypes can only be done under field conditions. The interpretation of what is taking place, therefore, is almost always a combined effort, and offers ample justification for systematically creating linkages between programmes, without which much effort and expenditure can go to waste. It is for this reason that making use of biotechnology in Africa is initially dependent on establishing functional, active, field breeding programmes.

66

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 5

67

Biotechnology: Expanded Possibilities

5.4 Biotechnology in Africa While few are currently using advanced biotechnology methods, African institutions are making progress toward becoming active practitioners of the techniques. In surveys conducted by the International Service for National Agricultural Research (ISNAR) in 1998 (Cohen, 1998), 37 countries of Africa reported an average of six full-time scientific staff devoted to biotechnology research. The average annual expenditure on plant biotechnology research in African countries was approximately $121,000. Approximately 65% of this money came from international donor agencies. The most important area of biotechnology techniques applied was micropropagation of vegetatively propagated crops via tissue culture, which accounted for 52% of the total number of activities. In most cases, African biotechnology laboratories are an add-on to an existing crop improvement programme. This is a good strategy and helps to lower cost, but they are still primarily donor funded. In only three countries of sub-Saharan Africa (South Africa, Kenya and Zimbabwe) have national agencies been established to promote agricultural biotechnology as a strategy for national economic development. This is in sharp contrast to Asia and Latin America where governments have established new agencies, such as the China National Center for Biotechnology Development and the Indian Department of Biotechnology, that provide significant funding, over and above their traditional agricultural R&D budgets, to build national capacity and competitiveness in agricultural biotechnology. Even in Europe where opposition to genetically modified organisms (GMOs) is most vocal, governments and industry continue to invest significant new funds in development of agricultural biotechnology research centres. Most African countries are far from making this level of commitment and do need to strengthen their seed distribution and conventional breeding programmes before shifting significant resources to biotechnology. However, unless some greater investment is made in training Africans who can understand the benefits and risks of biotechnology and collaborate with researchers elsewhere, there is a real possibility the biotechnology revolution will pass Africa by much as the Green Revolution previously did. A necessary first step is the training of additional Africans in modern plant breeding, including the application of new molecular and bioinformatic tools for crop genetic improvement. Then, as they return from training, facilities would be needed where they could use their new skills at their home institutions. The Rockefeller Foundation’s experience in Asia suggests that an effective biotechnology capacity can be built into an existing breeding programme by adding three or four well trained scientists, about $100,000 worth of new facilities and equipment, plus $30,000–50,000 per year in operating funds. Expenditure on biotechnology applications by centres of the CGIAR involved in crop improvement in Africa totalled $10.33 million (CGIAR, 2000). The exact portion of that work directed at the needs of African farmers is unknown; however, if one assumes 100% of that performed by the Africa-based organizations, IITA and WARDA, and 40% (the CGIAR-wide portion of resources directed toward Africa) of that performed by other centres, the approximate figure would be $5.7 million. The Africa-related CGIAR centre with the largest biotechnology programme is CIMMYT, with $3.2 million, followed by IITA, with $2.0 million (CGIAR, 2000).

67

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 5

68

Chapter 5

According to the ISNAR survey, within IARCs carrying out biotechnology research in Africa, use of molecular markers was the leading technique applied, accounting for 75% of all activities. It should also be noted that several IARCs and several laboratories in South Africa have reported successful transformation of important crop species, including maize, cassava and cowpea. Viruses, insect pests and plant diseases ranked as the three most important production constraints being addressed, each with approximately 19% of the 94 total activities, followed by crop quality, with 12% of the activity. With regard to the crops reviewed in the ISNAR study, tissue culture methods have been applied at numerous sites managed by IARCs. IITA maintains large tissue culture facilities at its headquarters in Ibadan focusing on cassava, banana and yam. IITA is also engaged in identification of markers for genes controlling resistance to Striga and is actively pursuing genetic transformation of cowpea. WARDA employs anther culture in the development of interspecific varieties of rice and has recently established a laboratory for the use of molecular markers at its headquarters in Bouake, Côte d’Ivoire (see Plate 7). CIMMYT has applied MAS for several important traits of African maize, and is assisting in the creation of national biotechnology laboratories in Kenya and Zimbabwe. Several biotechnology projects are nearing implementation stages within African NARSs. However, the distribution of these projects is highly skewed in terms of the institutions and crops involved. 1. Marker-assisted selection (MAS) for maize streak virus resistance is scheduled for implementation in Kenya during 2001–2002 (KARI, 1998). 2. MAS will also be applied to drought and stem borer resistance in Kenya and Zimbabwe during the same period (CIMMYT, 1998). 3. KARI and CIMMYT have initiated a 5-year programme aimed at developing insect-resistant maize varieties using transgenic B.t. technology. 4. A six-country programme funded by the Swedish International Development Agency (SIDA) is aimed at enhancing and broadening capacity in biosafety and biotechnology in eastern Africa. 5. KARI has imported and begun multiplying transgenic sweet potato varieties resistant to feathery mottle virus. 6. The Ugandan government has agreed to fund a 5-year initiative implemented by INIBAP, the National Agricultural Research Organization of Uganda, and others to develop transgenic East African highland bananas with resistance to black sigatoka disease, nematodes and weevils (INIBAP, 2000). 7. Researchers at the University of Zimbabwe have used a gene construct for resistance to aphid-borne mosaic virus to achieve resistance in transgenic tobacco (Mlotshwa, 2000) and are now collaborating with Michigan State University to transform cowpea with the gene (Sithole-Niang, 2000). In conjunction with the projects listed above, and others, some countries have invested in biotechnology infrastructure. In addition to the many facilities in operation, which make use of tissue culture methods, the following are either already assembled or nearing completion.

68

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 5

69

Biotechnology: Expanded Possibilities

1. In Zimbabwe, a large research campus has been developed at the Scientific and Industrial Research and Development Center. One of the SIRDC institutes is dedicated to biotechnology research. Five full-time SIRDC scientists are currently working on a variety of topics, which range from wine making to fingerprinting of sweet potatoes, to marker-assisted selection of drought tolerance in maize. 2. Also in Zimbabwe, at the University of Zimbabwe, a small laboratory has been set up in the Crop Science Department for identifying QTLs for resistance to Striga in sorghum. 3. At the Centre Nationale de Recherche Agricole, in Abidjan, a dedicated biotechnology laboratory has been set up for performing mapping studies and genetic transformation of cassava and yams. 4. In Kenya, at the National Agricultural Research Laboratory, the Kenya Agricultural Research Institute is building a biotechnology laboratory suitable for a range of biotechnology applications. Also worthy of mention are: genetic transformation of tobacco has been achieved at the Tobacco Research Institute in Harare, Zimbabwe; and several laboratories in South Africa have confirmed routine capacity for genetic transformation of agronomic crops. However, the level of activity in biotechnology is a poor indication of the overall human capacity on the continent. In fact, a much larger number of scientists have acquired skills and knowledge, but they are often unable to use them due to lack of facilities and funding for research and they are seldom brought together to form the critical mass of talent necessary to make real research progress (Kezire et al., 2000; Odame and Kameri-Mbote, 2000). Unless the level of activity in biotechnology increases dramatically in the coming years, this capacity could begin to erode for lack of practice. One way of helping these scientists to make progress and keep up to date is to establish collaborative research linkages which enable them to spend time (at least 2–3 months per year) conducting research relevant to their home country at an advanced laboratory in Europe or North America where equipment, supplies, information, new methods, mentors and peers are all more readily available. The Rockefeller Foundation calls such arrangements ‘career fellowships’ and experience indicates that the fellows work long and hard, accomplish much, and make important contributions to the host laboratory as well as their home institution. Another threat to the application of existing capacity at present is the anti-GMO campaign being waged by a number of individuals and agencies primarily based outside Africa. Concerns raised by these groups have slowed the deployment of transgenic crops throughout the world (Paarlberg, 2000). Several IARCs are also unable to field-test transgenic varieties due to recently initiated national regulations on transgenics (CGIAR, 2000; Johanson and Ives, 2000). One positive sign that progress toward assessing such new technologies would not be completely stopped was the official importation in Kenya in March 2000 of transgenic sweet potato cuttings with resistance to feathery mottle virus (Daily Nation, 19 August 2000).

69

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 5

70

Chapter 5

5.5 Biotechnology for African Crop Challenges Summary This chapter has argued that because of limitations in the downstream areas of breeding and seed systems, programmes concerned with biotechnology applications for Africa should not be limited to biotechnology. In order for investments in biotechnology to have an impact in the lives of the poor, they must be made in tandem with targeted support to downstream, field-based activities. Yet there are numerous crop improvement challenges in Africa which will not respond to conventional efforts. Fortunately, a core group of African scientists have already received training and others will soon return who are ready to apply their new knowledge to priority constraints of the poor. Given the promise of the technology itself, and given the size of the challenge in attempting to make major differences in crop performance under marginal conditions in Africa, it seems clear that now is the time to begin developing and applying relevant biotechnology applications in Africa. Commercial biotechnology firms have shown limited interest in applying their capacity to resolving food security needs in developing countries (Persley, 1999). In the case of Africa, this trend is not expected to change in the near future. Therefore, if biotechnology is to have the anticipated impact on the lives of Africans, it will be due to investment in public sector capacity in biotechnology applications. Building on existing national commitment to biotechnology capacity, continued development and use of tissue culture techniques, where applicable, should pay early dividends to crop improvement programmes. Marker-assisted selection aimed at combining numerous resistance traits in a single crop variety is another example of a potential biotechnology application that is relevant and accessible for IARCs and national programmes to adopt. Its use in Africa should be expanded as NARSs gain capacity in molecular methods and the technology itself is improved. IARCs can play a critical role in backstopping the setting up of molecular laboratories and the integration of molecular selection techniques within African NARSs. While the development of transgenic crop varieties by NARSs in Africa is as yet some way off, preparations can proceed to assure biosafety measures are in place to permit their evaluation, introduction, and eventual development. According to Ndiritu (1999), South Africa, Kenya, Zimbabwe, Botswana, Malawi, Mauritius, Cameroon and Zambia either have or are in the process of adopting explicit biosafety regulations and guidelines, and are participating in the negotiations for an international biosafety protocol. The ability of national programmes to assess safely the value of transgenic crop varieties is dependent on containment facilities, which are currently lacking in most African countries. Increased testing and verification capacity of transgenic materials within NARSs is also essential to increasing access to products of biotechnology research based elsewhere.

5.6 The Potential of Apomixis With regard to crop varieties, what Africa really needs for all major food staples is a large number of locally well-adapted, improved cultivars that can increase both the quantity and stability of production, plus more effective mechanisms of distributing these cultivars to all farmers. Due to Africa’s many unique ecological and socio-economic

70

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 5

71

Biotechnology: Expanded Possibilities

niches and its limited markets and infrastructure, farmer participation in cultivar development, selection and dissemination will be essential in meeting these objectives. If apomixis could be introduced as a flexible new tool for breeding African crops, it would greatly facilitate farmer participatory breeding, lower the cost of producing new varieties, improve their performance under all growing conditions, and speed the process of seed delivery, including farmer-to-farmer trade. Apomixis (agamospermy) is a form of asexual reproduction through seed that occurs naturally in some plants. It is a genetically controlled process that bypasses female meiosis and fertilization to produce seeds genetically identical to the maternal parent. The seeds formed and the progeny plants they produce are true breeding genetic clones ready for immediate performance evaluation. In recent years there has been progress in identifying the genes controlling the components of apomictic seed development and in moving these genes into crop plants (Jefferson and Bicknell, 1996; Veille-Calzada et al., 1996; Grossniklaus et al., 1998; Ozias-Akins et al., 1998; Luo et al., 1999). While no new apomictic crop varieties have been released, several relevant patents have been issued, primarily to public sector research organizations. For use in Africa, apomixis would have the following advantages. ●

●

●

For essentially all crops, numerous genotypes that performed well under local conditions could be genetically fixed early in the selection cycle and developed directly into cultivars desired by farmers. Under such a scheme, variability would be generated through traditional hybridization with the population of resulting plants grown and evaluated by farmers under local conditions. The plants that performed best would be selected and crossed with an apomictic male parent. The resulting progeny plants would be apomictic and the best could be selected by farmers as true breeding, superior cultivars. Farmers would thus become key actors in the breeding of diverse cultivars for diverse environments. The number of true breeding, locally well-adapted, superior cultivars would be large enough to encourage the use of mixtures of cultivars, thus enhancing the genetic diversity of the crop both locally and regionally. Many of the cultivars selected by farmers and genetically fixed by apomixis would have hybrid vigour. Such hybrid cultivars not only have greater productivity under good conditions, but also have increased stability of production under adverse conditions. Apomixis would bring the benefits of hybrid vigour to numerous crops and to many smallholder farmers who never previously benefited from hybrid technology. Important African crops such as cassava, sweet potatoes, yams and potatoes which are traditionally propagated vegetatively could be converted to true-seed propagation. These are polyploid crops that are difficult to breed. Their seeds either segregate genetically or suffer from severe inbreeding depression when plants are selfed to make them true breeding. Consequently, elite cultivars are usually propagated via tissue segments that are genetic clones of the donor plant. However, the rate of vegetative multiplication is slow (roughly six offspring per parent plant), pathogens are often transmitted along with the tissue segments, and the costs of storage, shipping and planting are high. With apomixis, elite cultivars would produce seeds that are genetic clones of the parent plant and that are, for the most part, pathogen free due to the normal pathogen elimination mechanisms associated with

71

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 5

72

Chapter 5

seed development. African farmers could save, trade and disseminate seeds of their favourite elite cultivars much as Asian farmers saved and traded the seeds responsible for the Green Revolution. Apomixis as a flexible breeding tool has the potential to be one of the most important innovations in the history of agriculture, benefiting all farmers, including those who have benefited little from previous innovations. While considerable research is still needed to make this a reality, the power of recent advances in plant molecular biology and progress to date in understanding the biological mechanisms of apomixis make this a challenging but achievable goal. A mission-oriented international research collaboration designed to share results with everyone would enable all crop breeding programmes, including those serving farmers in Africa, to benefit fully from the technology.

5.7 Intellectual Property Rights The free exchange of materials and information has been a hallmark of the international agricultural research system. Such exchange has been key to past successes of the system and it will be key to future successes in Africa. The genetic improvement of plants is a derivative process, in which each enhancement is based directly on preceding generations, and the process of adding value requires access to the plant material itself. Most important food crops originated in developing countries, and much of the value in today’s seeds has been added over the centuries, as farmers have selected their best plants as a source of seed for their next crop. Traditionally, these landraces and the indigenous farmer knowledge associated with them were provided free of charge to the world community. In exchange, public sector research and breeding programmes added value and returned scientific knowledge and improved breeding lines as ‘global public goods’ to developing and developed countries. Now, however, the rules of the game are changing, even before Africa has had the opportunity to benefit much from such global public goods. Over the past decade, in industrial countries, applied crop-biotechnology research and the production of improved seeds have increasingly become functions of the ‘for-profit’ private sector. This has led to a significant increase in the total research effort committed to the plant sciences and crop improvement, but the results of such research, in both the public and private sectors, are now often protected as various forms of intellectual property, including patents, material transfer agreements, plant breeders’ rights and trade secrets. Furthermore, intellectual property rights (IPR) are globalizing. Industrial countries have made IPR an important component of international trade negotiations where they use IPR to exploit their competitive advantage in research and development. Larger developing countries seeking to join the World Trade Organization have been required by the Trade Related Aspects of Intellectual Property Rights (TRIPS) provisions to put in place IPR systems that include protection of crop varieties. The least developed countries, including most in Africa, have until 1 January 2006 to implement such IPR systems. However, since most African farmers cannot afford to purchase new seed for each planting, it is important that Africa’s new plant

72

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 5

73

Biotechnology: Expanded Possibilities

variety protection laws include provisions allowing farmer-saved seed and use of varieties as a resource for further breeding. This is in contrast to granting utility patents on plants which extend protection to the progeny and its seeds such that breeders cannot legally use protected varieties as breeding material. The International Undertaking on Plant Genetic Resources for Food and Agriculture needs to be approved and implemented as a means of ensuring the conservation, sustainable use, and free flow of seeds for the benefit of people in Africa and elsewhere. Protection of intellectual property is to be expected when dealing with for-profit companies. The major IPR change that is threatening the operations of the international agricultural research system has occurred within public sector plant research institutions. In the USA, the 1980 Bayh–Dole Act gave universities and other public-funded research institutions the right to obtain patents on and commercialize inventions made under government research grants. Similar arrangements are emerging in Europe, Japan, Australia, and most other industrialized countries. The result is that while the majority of the significant discoveries (e.g. pathogen-derived plant resistance to virus infection) and enabling technologies (e.g. biolistic transformation methods) are still generated with public funding in research institutions and agricultural universities, these discoveries are no longer being treated as ‘public goods’. Rather, they are being patented and licensed, often exclusively, to the for-profit sector. Such discoveries now primarily flow from the public sector to the for-profit sector and if they flow back out usually come under material transfer agreements (MTA) which significantly restrict their use, usually for research purposes only. Crop genetic improvement is a derivative process and each incremental improvement that involves biotechnology now comes with a number of IP constraints which accumulate with each transfer or further improvement. To deal with this predicament, the private sector is becoming greatly centralized into a global oligopoly dominated by five leading firms. They are the product mergers made in part to accumulate the IP portfolios necessary to produce biotechnology-derived finished crop varieties with ‘freedom to operate’. Such consolidation could lead to a loss of competition among purveyors of agricultural technology and make it excessively difficult for new firms to enter the industry, worldwide, and may constitute arguments for restricting the exercise of intellectual property rights (Barton, 1999). The publicly funded agricultural research community, however, has not followed suit. Leading academic researchers are primarily interested in research competitiveness. They readily sign research MTAs to keep competitive but are then restricted from further transferring their research products. Their universities now have ‘technology transfer offices’ where the incentives are to maximize IP royalty income, often by granting exclusive licences. The net result is that improved plant materials produced by academic scientist-inventors are highly IP-encumbered and commercially useful only to a big company having an IP portfolio large enough to cover most of the IP constraints. The international agricultural research system does not have such an IP portfolio and as a consequence the traditional flow of materials through the system is breaking down, particularly at the point where useful new technologies and improved plant materials flow from public sector researchers in developed countries to international centres and national crop improvement programmes in developing countries. Africa, in particular, is being short changed of the benefits of biotechnology because, unlike Asia and Latin America, it has little capacity to replicate research results patented elsewhere, for the

73

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 5

74

Chapter 5

benefit of poor farmers in countries where the IP is not protected. Africa is much more dependent on partnering with others, but publicly funded researchers in industrial countries are no longer partners who can freely share their most important discoveries. A new mechanism is needed, such as universities retaining the right to grant charitable licences, and then pooling such licences into an IP portfolio designed to facilitate use of research results to help food-insecure subsistence farmers in places like Africa. Such an IP portfolio could help reinvigorate the international agricultural research systems by re-establishing the flow of advanced scientific knowledge and research materials to and through the system for the benefit of smallholder farmers in Africa and other poor countries.

74

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 5

6

Seed Systems: Reaching the Poor in Numbers

6.1 Overview Seeds form the foundation of all agriculture. Without seed there is no next season’s crop. The genetic traits embodied within seeds reflect and determine, to a large extent, the nature of farming systems, themselves. In turn, the nature of ‘seed systems’ (the term is used herein to describe the prevailing methods for accessing, storing, and exchanging seeds and other planting material) determine in large measure who benefits from the advances made in plant breeding and biotechnology. Perhaps most important within the context of this book, seeds serve as a tangible representation of technologies developed for use and long-term ownership by poor farmers. Once seed is obtained, farmers can use it at will in directing their own advancement. Seed is consistently recognized as the most important and least expensive of cash inputs for farming (Venkatesan, 1994). The importance attributed to seed is most often described in terms of its role as the factor which sets the upper limits on productivity and yield stability (Morris, 1998; Srivastava and Jaffee, 1993), although at a far more basic level, the sheer availability of seed has often affected African farmers’ ability to sow a crop (Cromwell, 1996). The seed demand–supply relationship in a large portion of Africa’s smallholder farming systems appears to represent a situation of market failure: farmers in need of seed of particular qualities cannot afford to pay for them at rates which would make it attractive for suppliers to enter the market. The resulting, low effective demand for seed of varieties designed for the growing conditions of low-input farms effectively prevents their development. In agriculture’s sliding scale of efficiencies, moreover, the lack of this key, initial input may prevent farmers from moving upward to productivity levels where private sector exchanges operate more efficiently. As an example, yields of maize in the USA during the early 20th century had reached a plateau at approximately 1.5 t ha−1 prior to the introduction of hybrids in the mid-1930s (Chrispeels and Sadava, 1994). Subsequent phases of rapid yield increase (and rapid expansion of the seed industry)

75

76

Chapter 6

were brought on by the successive introductions of double-cross, three-way and single-cross hybrids to produce current average yields of over 7 t ha−1 (Norskog, 1995; Crow, 1998). Sustainable increases in yields in Africa are likely to be less than in the USA, however, there is little doubt that the current, unmet demand for improved, seed-based technologies represents a key factor in Africa’s declining per capita agricultural productivity. Several authors have pointed out that seed systems in Africa and other developing regions have received less attention in proportion to their importance than other sub-sectors, such as agricultural research and extension systems (Venkatesan, 1994). Perhaps because of perceptions that the potential of improved varieties of basic food crops in Africa did not duplicate or was less stable than results obtained in Asia, seed systems in Africa have received less attention than merited. Poor access to seed among small-scale farmers in Africa has been recognized as a major constraint to crop improvement by several authors, yet facilitating consistent, broad-based access to seed of improved crop varieties remains a complex issue with no simple solutions. In a recent review of seed systems in Kenya, Malawi, Zambia and Zimbabwe by Tripp (2000), several different types of seed demand are identified, including demand for improved varieties with higher yield, demand for re-supply of seed lost following disasters, demand resulting from poverty and chronically low yields, and demand for fresh seed of known varieties. This chapter will endeavour to explore these four types of demand and offer some practical suggestions toward meeting the different needs expressed by them. Beginning in the late 1980s and early 1990s, the seed sectors of most African countries were progressively liberalized. Many formerly monopolistic, parastatal seed companies were privatized and regulations were relaxed to allow the entry of wholly private firms (Cromwell, 1996). While over the long term this policy is likely to pay important benefits for farmers through gains in efficiency and competition, in the short term the change in policy has meant that government and donor agencies which previously supported seed supply via public institutions have lost much of their ability to do so, as public seed companies have been privatized and overall responsibility for seed distribution has been shifted to the private sector. As hybrid maize seed markets represent the primary incentive for private seed sales, countries where the primary food staple is other than maize (including all of West Africa) have suffered particularly low levels of seed sector investment. Responding to demand for seed of hybrid and commercial crops grown in Africa such as cotton and maize, appears to be a relatively straightforward matter of applying sound business and technical strategies common to private seed sector development anywhere, albeit one compounded in terms of complexity by Africa’s vast size, underdeveloped infrastructure, and very low farmer incomes. Responding to the low-level or intermittent demand for open-pollinated and non-commercial crops such as cowpea and cassava, however, has yet to be performed successfully by purely private companies, and thus implies continued involvement of public agencies, NGOs, and small, grass roots farmer associations (Sperling, 1994; David et al., 1997). Regardless of the type of agency involved, however, the size of the seed problem in Africa and its overwhelming importance in delivering the hope and promise of crop genetic advancements to farmers, merits close examination and broader adherence to strategies that work.

77

Seed Systems

6.2 Issues in Seed Supply Overview Total seed consumption worldwide is estimated at 120 million tonnes per year (Kelly and George, 1998). In developing countries, over 80% of seed of staple food crops is farmer-saved seed (Jaffee, 1991). As the vast majority of seed used in Africa is farmersaved seed, estimates of total consumption must be calculated using areas planted and common seeding rates, coupled with observed rates of variety replacement or renewal of seed stocks. Estimates of annual seed consumption for a number of species in Africa are presented in Table 6.1. These calculations show that total annual seed consumption of major crops in Africa is approximately 2 million tonnes. Using restocking rates for self-pollinated crops and non-hybrid seed of open-pollinated crops of once every 3 years, and restocking rates for hybrid maize of once per year point to a potential seed market of approximately 700,000 t per year.

Farmer-saved seed The vast majority of seed used on farms throughout the world is seed saved from season to season using a wide variety of techniques. The first step involved is selection of the portion of harvest to be kept as seed. Several reports suggest that farmers make their selections on the basis of plant quality characters in the field (Wright et al., 1995; Scowcroft and Polak Scowcroft, 1997). However, recent studies conducted in Ghana and Zambia found that less than 25% of farmers actually select seed in the field (Walker and Tripp, 1997). On-farm seed storage practices vary from region to region and crop to crop. Farmers in central Mozambique construct special silos of woven grass hoisted on poles. Farmers in southern Sudan store seed in racks placed above cooking fires where smoke acts as an insecticide. In Somalia, farmers store sorghum seed in underground pits covered with woven mats and soil. In general, such techniques appear adequate for Table 6.1. Estimates of annual seed consumption for principal cereal and pulse crops in Africa.

Groundnut Maize Rice (upland) Rice (lowland) Beans Cowpea Sorghum Millet Total

Area planted (million ha)

Seeding rate (kg ha−1)

Total (1000 t)

9.0 25.2 3.1 4.7 3.2 7.2 23.0 20.2 85.5

80 20 60 20 40 10 5 4

720 504 186 94 128 72 115 81 1900

78

Chapter 6

preserving cereal seed viability. Legume seed, which is more difficult to produce and store, presents added difficulties (Desai et al., 1997). Farmers in Mali, for example, often lack access to viable groundnut seed at planting time. With the exception of cowpea, germination rates of farm-stored seed of four grain crops exceeded the nationally accepted minimum germination rates in Ghana (Walker and Tripp, 1997). Cowpea also ranked lowest in germination rate of saved seed among six crops in a survey conducted in Mozambique (Sitch, 1996). With farmer-saved seed being such a common practice in Africa, the question must be asked whether introduced seed does, indeed, represent an advantage to small-scale farmers. The answer to this question is bound up in the complex, multipurpose decision-making environment of seed users who are at the same time homesteaders, commercial producers and members of small communities. One principle of varietal adoption (and thereby, out-sourcing of seed, at least once) which is becoming increasingly accepted is that farmers must first observe the new variety growing in their own farming environment for an entire cycle, during which they will evaluate its overall usefulness in the context of the various purposes they hold for that crop. Nevertheless, when benefits are perceived, in general, it can be stated that sentimental attachment to local varieties, while often present, will generally give way to more practical concerns over increasing the harvest (Muhhuku, 2000). In most cases, however, farmers will continue to cultivate old varieties alongside new ones for some time. Therefore, on-farm, farmer-managed trials of experimental varieties represent one of the most critical stages of crop improvement. Unfortunately, the rather unglamorous (and, relatively speaking, expensive) work of multiplying sufficient seed, transporting it to the field, and the laying out and planting of plots has often been neglected by breeding teams and donor agencies alike. The logistical complexities of multi-location varietal testing (often compounded by lack of efficient means of communication, bad roads, fuel shortages, etc.) are likely to hinder the effectiveness of crop improvement work, including biotechnology, for some time to come. Given the reality of the ways in which small-scale farmers in Africa make decisions on new varieties, however, it is logical to ask whether funding of upstream work on biotechnology and breeding is worthwhile if no one is willing to support and conduct the multi-location, participatory testing phase. Farmer-saved seed stock stored using local methods is intermittently subject to ruptures caused by drought, pest and disease outbreaks, and civil unrest. Renewal of depleted seed stocks caused by at least the former two occurrences would, in many rural economies, represent opportunities for seed companies. In Africa’s highly depressed economy, such demand has so far largely remained ‘ineffective’, that is, insufficiently backed by purchasing power to stimulate the creation of commercial supply networks. Nevertheless, recent studies have shown that even very poor farmers will purchase seed when it is sold via appropriate channels (David and Otsuka, 1994; David and Sperling, 1999; Rohrbach and Malusalila, 2000). Over the past decades, large amounts of donor and government funding in Africa have been dedicated to establishing seed supply systems serving rural areas. However, much of this funding was applied during a period when seed supply was controlled by the public sector. The experience gained under this regime is of little use in determining how best to apply new funding under liberalized market conditions, making seed systems one of the most experimental and open-ended working environments of the entire crop improvement process.

Seed Systems

79

Seed organizations When seed is not saved on-farm, African farmers procure new seed from a variety of sources. In the Mozambique survey cited above, 53% of farmers reported redistribution of their own seed stocks to other farmers. Sixty per cent of the recipients of this seed were family members, while 28% were neighbours. Seventy-four per cent of these transfers were done for free (Sitch, 1996). In Zambia, studies also revealed that most off-farm seed was procured from other farmers as a gift, while in Ghana, the majority was purchased (Walker and Tripp, 1997), either in the marketplace or from other farmers. While a large portion of seed used on African farms is likely to continue to be farmer-saved seed, seed dissemination capacity continues to be an important factor to the overall impact of crop improvement programmes. In order for advances in crop improvement to reach the farmer, someone must first supply the seed. Aside from farmers themselves, a number of entities are involved in seed supply in Africa. These are identified below, along with brief characterizations of their respective modes of operation. Multinational companies These are largely publicly traded companies represented in more than one country, often involving worldwide operations. Recent developments in biotechnology and intellectual property regimes have caused a rapid consolidation of the international seed industry, recently chronicled by James (1998) and James (2000), with DuPont (incorporating Pioneer Hi-Bred International), Syngenta (Novartis and Astra-Zeneca), Monsanto (Agracetus, Asgrow, Calgene, Dekalb, Holdens, among others), AgrEvo (Hoechst, PGS, Rhone-Poulenc, Sun Seeds) and Dow Elanco (Dow Chemical, Eli Lily and Co.) emerging as the largest actors. Private sector investment in research in developing countries has remained relatively small compared with their total budgets (Byerlee, 1996). While all of the companies listed above have at least some presence on the African continent, their presence in the seed markets of sub-Saharan Africa is relatively limited. In Africa, the group is represented by several joint ventures with the main focus on hybrid maize and cotton seed sales. To date, most of the investments made by multinational companies in sub-Saharan Africa have been concentrated in a few countries of eastern and southern Africa, including Kenya, Malawi, Zimbabwe and South Africa. Extensive earlier investments made by Pioneer Hi-Bred International in West Africa (Cameroon, Côte d’Ivoire, Nigeria) were written off in 1993 (Rusike and Eicher, 1997). Multinational seed companies often enter into multiple country seed markets via breeding and seed production operations based in one or two. Several companies have breeding operations in South Africa and Zimbabwe which are used to develop hybrids for additional markets outside those countries. They rely on the knowledge of their breeders plus extensive participation in national variety trials to produce varieties developed from proprietary parental materials already within their seed banks for release in distant ecologies. The principal advantage of multinational companies in gaining access to local markets is their size, which allows them to manage large collections of broadly adapted

80

Chapter 6

germplasm and make investments in seed markets, which may take several years to show a profit. A major disadvantage of the current mode of operation of multinational companies in Africa is their reluctance to set up individual breeding operations in each country, in part due to their high overheads in research and promotion of new varieties (Byerlee and Lopez-Pereira, 1994). Minimum investment levels were recently estimated by one large seed company at approximately $5 million. As such, their releases, although often bearing useful traits (such as early maturity or, in the case of maize, resistance to maize streak virus), lack genuine adaptation. Market share of multinational companies in the major hybrid maize markets of Africa has remained small (Tripp, 2000). Former national seed companies Former national seed companies are the surviving entities of privatized (partially or fully), parastatal companies. Few such companies still enjoy monopoly status, although low or ineffective competition in many countries means that they continue to function as oligopolies, with very large market shares (Tripp, 2000). In countries where there has been appreciable competition, they are operating alongside private companies, competing for the same market. Such companies have historically enjoyed direct, formalized relations with NARSs, with significant carry-over benefits during the liberalization process. As a result, they continue to embody significant advantages over newcomers via their ownership of adapted, improved varieties developed prior to market liberalization. This fact has allowed public companies to carry seed of a wide range of crop species at relatively little added cost. With deregulation, however, most NARSs are now free to supply new releases to the highest bidder, and relations with public seed companies have changed. Private, national companies Outside of a few countries (South Africa and Zimbabwe, and more recently Kenya and Malawi), seed markets in Africa have not experienced the proliferation of private, independent companies which deregulation of the seed industry should permit. However, in Kenya, where seed industry deregulation has been more or less complete, a significant number of small companies focusing on niche markets have been registered within the past few years (John Kedera, personal communication). Private, national companies may yet play an important role in seed distribution in Africa, as they have in India and Brazil (see Lopez-Pereira and Filippello, 1995). By sub-contracting most tasks, operating in areas they know well, and taking advantage of close contacts with national breeding programmes, private national companies can potentially attain the sort of efficiencies which would allow them to undersell multinationals. However, these arrangements have been cited as a constraint to growth by Tripp (2000), in part due to the lack of medium- and large-scale growers who can produce large quantities of seed on contract. Farmer associations Farmers’ organizations have often become involved with seed supply as a means of guaranteeing timely access to seed of acceptable quality for producing a crop. The Maize Seed Association of Zimbabwe and the Kenya Farmers Association are two large-scale

Seed Systems

81

examples of this type of group. Such groups have usually been dominated by the interests of large-scale farmers, and often have involved official state sponsorship or substantial support from donor agencies. Moreover, their focus on issues more related to marketing of produce than with the supply of seed will tend to reduce their competitiveness in the future, and large farmer associations are not projected to be a significant force in seed supply over the medium and longer terms. More recently, smaller associations which operate locally have been involved in seed multiplication and distribution, and proved a certain level of effectiveness (Mduruma, 1999). (See Box 6.1.) NGOs As regulations controlling use and distribution of seed have been relaxed, NGOs have become increasingly involved in issues of seed supply, especially in the context of emergency relief operations directed at rural populations whose farming activities have been disrupted by conflict, drought, or other environmental disasters (Cromwell, 1996; Osborn, 1996; Chapman et al., 1997; Tripp, 2000). Quantities of seed distributed by NGOs in the context of emergency relief programmes can be measured in the tens of thousand of tonnes, and are growing (Osborn, 1996). The seed-related activities of NGOs and donor agencies in the context of relief programmes have been well documented in separate studies conducted by the Overseas Development Institute (1996) and Osborn (1996), which estimated that $10 million were being spent annually in nine countries of eastern Africa. In 1994, a single organization (World Vision) distributed seed to over 300,000 farm families in Mozambique alone (see Box 6.2). Other major theatres for emergency seed distribution campaigns in Africa have been Kenya, Somalia, Liberia, Sierra Leone, Angola, Rwanda, Burundi and the former Zaire. Uganda was recently the focus of a major campaign aimed at distribution of cassava varieties resistant to African cassava mosaic virus (Otim-Nape et al., 1997). In such contexts, the dire need of farmers, coupled with the opportunity of obtaining finance from donor agencies, has led many NGOs with inadequate knowledge and experience in agriculture into the distribution of ‘seed’. This is problematic for a number of reasons. In many cases, opportunistic traders have sold such agencies ‘seed’ which was, in fact, grain. In other cases, NGOs have imported seed of varieties which were not adapted and which produced very poor yields. Nevertheless, a small number of more technically oriented NGOs have distinguished themselves in the area of seed relief and ‘agricultural recovery programmes’ through effective responses to seed shortages. In view of the large quantities of seed being distributed through relief programmes in Africa, it is now essential that these schemes become integrated with national and international crop variety development efforts. Distribution of inappropriate or poor quality seed by organizations who have little understanding of adaptation and variety performance issues needs to be curtailed. Donor agencies (who fund such activities) and NARSs (who should regulate them) are perhaps the most important levels of control in this area. Seed distributed through long-term development projects operated by NGOs is rarer and poorly documented. Because seed is a valued commodity, seed distribution under non-emergency conditions often blurs the lines between humanitarian and commercial operations, and distribution of free seed by NGOs has at times been criticized by private companies as a deterrent to market development. Meanwhile, the ease of supplying donor-funded, emergency seed programmes has often caused private

82

Chapter 6

Box 6.1.

Proving it can be done: Seed Co Ltd.

In searching for solutions to the problem of seed access among small-scale farmers of Africa, the debate often turns to the lack of investment in private seed networks and, eventually, questions over whether the sale of seed to small-scale farmers in Africa can be done profitably. Africa’s dispersed and underdeveloped markets, poor infrastructure, and low farmer incomes present obvious challenges to the expansion of private seed markets. Nevertheless, a response to the question may already be available in Zimbabwe’s Seed Co. The origins of Seed Co date to 1940, when the ‘Seed Maize Association’ was formed at the request of the government to multiply and market popular openpollinated maize varieties (McCarter, 2000). In 1957 a second association, the ‘Crop Seeds Association’, was formed to concentrate on seed production for selfpollinated crop species. In 1983 the two associations merged to form the Seed Co-operative Company of Zimbabwe Ltd. In 1996 the company was renamed Seed Co Ltd and was listed on the Zimbabwe Stock Exchange. Today, Seed Co markets 37 varieties covering seven crop species (Seed Co, 2000). The company is present in Mozambique, Zambia, Zimbabwe and Malawi and has annual regional sales of approximately 50,000 t. Equally important, an estimated 80% of its customers are small-scale farmers, who purchase certified seed of improved varieties in packs ranging in size from 0.5 to 50 kg. According to Seed Co: An important key in the development of the Zimbabwean seed industry was the signing of legal agreements between the Ministry of Agriculture and Seed Co that entitled the company to the exclusive right to multiply and market a range of Government bred products. In exchange, the company had to undertake to produce agreed volumes of seed, including 20–30% carryover, and to sell seed at agreed prices. These agreements have resulted in large volumes of quality seed being made available to Zimbabwean farmers at prices three times lower than those of South Africa and approximately one-ninth of the United States . . . Seed Co now employs nine breeders and owns two research stations (McCarter, 2000). In today’s environment of open competition among multiple companies, such collusion between government and a single company would not be permitted, and prior to becoming reorganized as a private company, the relationship between government and Seed Co often came under criticism. To date, for example, there are no sales of open-pollinated maize seed in Zimbabwe, a policy which was maintained in part with the support of Seed Co. Mozambican farmers, on the other hand, have been able to purchase good quality OPVs for nearly a decade. Moreover, it is possible that competition between Seed Co and more recent entries into the region (Pioneer, Monsanto and Pannar (South Africa) are now active in Zimbabwe and several other countries) will result in even lower prices and higher quality products. Nevertheless, in terms of creating a formula to deliver public goods effectively to needy users, Seed Co and its predecessors can be cited as one which has paid off.

83

Seed Systems

Box 6.2.

Seed sector development in Mozambique

In 1987, World Vision International initiated a programme of support to Mozambican farmers affected by the long-running civil war. Hundreds of thousands of rural families had been displaced by fighting. World Vision’s programme focused on supplying farming households with seed of maize, sorghum, millet, cowpea and groundnut to re-commence farming. Following several seasons of poor results using commercial offerings from Zimbabwean and South African suppliers, World Vision began a series of multilocation trials that included experimental varieties from IARCs, regional seed companies, and local landraces. Beginning in 1990, results of trials were passed on to the national research institute and Semoc, the national seed company. The figure below summarizes the results of 4 years of NGO-supervised on-farm trials (as all research stations were located in war-affected areas, all research was conducted on-farm). World Vision backed up trial information with extensive data sets constructed from farmer interviews, observations from field visits, and surveys. The programme developed collaborative relations with the national university by hosting senior thesis projects and collaborated with CIMMYT, ICRISAT and CIP in facilitating in-country testing and training sessions focused on specific crops.

Due to the war, Semoc breeders and seedsmen were unable to travel outside the capital city, and were therefore eager to receive information from others regarding the performance of candidate materials, especially data from farmers’ fields. The programme’s first breakthrough came in the form of an early maturing, openpollinated, flint maize variety (DMR-EMSRW-1) developed at IITA which carried resistance to maize streak virus and downy mildew. The variety was renamed ‘Matuba’ (a later selection was released as ‘Semoc-1’) and multiplied by Semoc. Between 1993 and 1997, 15,000 tonnes of ‘Matuba’ and ‘Semoc-1’ were sold by Semoc. Another early outcome was the identification of ‘Namuesse’ cowpea. Although many improved cowpea varieties were tested, none out-performed ‘Namuesse’, a local variety with good yield, intermediate growth habit, and

84

Chapter 6

Box 6.2.

Continued

resistance to thrips. ‘Macia’ sorghum is a pure line variety developed by ICRISAT with good yield, intermediate height, and excellent palatability and preparation characteristics. Both ‘Namuesse’ and ‘Macia’ have since become popular commercial varieties for Semoc. As vegetatively propagated crops, distribution of stock of the best-performing sweet potato and cassava varieties presented greater challenges. The CIPdeveloped sweet potato variety, ‘15 Dias’ became highly sought after. Numerous women’s associations began multiplication and local vending of vines. The most popular cassava variety, ‘Fernando Po’, was also a local variety. It has been multiplied in numerous field stations run by World Vision and provincial services of the Mozambican Ministry of Agriculture. Through international seed tenders, Semoc has gone on to supply seed of ‘Semoc-1’, ‘Macia’, and ‘Namuesse’ cowpea to Angola and Malawi. In July 1998, Semoc was purchased by Seed Coop of Zimbabwe. Seed Coop cited its interest in gaining rights to lowland tropical germplasm as one of its principal reasons for purchasing Semoc.

companies to eschew working on increasing their market share in non-emergency markets. Several Ugandan agencies which have distributed seed while operating as NGOs are converting to private, for-profit seed companies (Laker-Ojok, 2000). Community-based seed production schemes As seed multiplication initiatives have moved downstream and more development groups have become involved, ‘community-based seed production’ has gained increasing popularity. In these projects, improved seed and technical assistance is focused on targeted, ‘pilot’ villages in order to train farmers in seed production, storage, and distribution. While the concept may be attractive, this model is faced with several serious challenges, mostly related to the sustainability of such initiatives (Shumba and Mwale, 1999; Tripp, 2000). Scaling-up from or even replicating the village level is often very difficult. So-termed ‘pilot schemes’ in a very limited number of villages often consume a sizeable portion of the resources available for the whole country.

Seed products Transgenic varieties Because of the high intellectual property (IP) density of transgenic varieties, it is likely that most (though not all) offerings of these products will be undertaken by multinational companies seeking to establish new markets in Africa. An early example is insect-resistant Bt cotton, which has already been released in South Africa and fieldtested in Zimbabwe. Bt cotton is a likely candidate because of the presence of several large companies that can unite the seed demands of large numbers of producers and because the technology significantly reduces production costs in a crop where African production is competitive.

Seed Systems

85

An alternative scenario for the distribution of transgenic varieties in Africa is partnerships between private corporations and public sector breeding programmes, which would also help to strengthen the capacity of NARSs to oversee and utilize new molecular technologies. Several examples of such partnerships already exist in Africa, with the potential for others to be initiated. Hybrid varieties Because of their cost – an average of $40 per season for most small-scale farmers, which may represent as much as 10% of total yearly income – hybrid varieties are likely to continue to be marketed primarily to semi-commercial farmers, who farm upwards of 5 ha or more of land. Moreover, the production and marketing of hybrid seed is not well suited to community-based operations. The start-up costs involved in establishing seed operations in this sector, including long lead times for registration of new varieties, seed cleaning equipment, storage and transport costs, coupled with the small number of clients, indicate that activity in this area is likely to depend on access to capital in the form of loans, venture capital and grants. The provision of such capital would significantly increase the possibility for development of a ‘start-up company’ sector in areas of currently ineffective demand for seed. This is explored in more detail, below. Open-pollinated varieties Open-pollinated varieties are often considered more suitable for small-scale farmers because they can be recycled without a loss of yield potential. For this same reason, they have proved of little interest to private seed companies throughout the world1. Because OPVs offer a low-risk entry point for developing seed markets among non-commercial farmers, their distribution should not be limited to public sector agencies. Public agencies which have developed productive, adaptated OPVs should be encouraged to engage with private seed companies regarding test marketing of such products. Improved OPVs could provide a stepping stone towards the use of other yieldenhancing technologies.

Seed prices Demand for seed among small-scale farmers embodies most of the components of demand in other markets. Quantities demanded tend to increase with decreasing prices. Demand elasticities at both high and low price levels, however, are influenced by consumer knowledge and product quality (Morris, 1998). Several impinging factors prevent the comparison of price–quantity relations across Africa; however, in two countries with similar seed industries, price does appear to influence quantities sold. Table 6.2 shows examples of the price of maize seed in African countries.

1

One notable exception is the case of EMBRAPA’s collaboration with private, start-up seed companies in the cerrados region of Brazil. Based on careful tagging and continual release of new cycles of selection of the popular maize OPV, ‘B-201’, private companies have been able to create a continuous source of demand.

86

Chapter 6

Table 6.2. 1999. Country Ghana Zimbabwe Uganda Kenya Malawi Tanzania Nigeria Ethiopia Zambia

Mean maize seed prices in nine countries of sub-Saharan Africa in OPV ($)

Hybrids ($)

1.00 — 0.92 1.62 — — 0.73 0.13 —

3.00 0.30 1.69 1.62 1.29 0.90 1.75 0.84 1.10

Seed prices vary throughout the world, and are generally analysed by calculating prevailing seed:grain price ratios in each local system, although comparative, absolute prices have been listed as well (Lopez-Pereira and Filippello, 1995). Again, using maize as an indicator, seed tends to be far cheaper in developing countries and Africa in particular, than in industrial countries. The average price of hybrid maize seed in the USA in 1994 was $3.72 kg−1 compared with $0.75 kg−1 in all developing countries (Lopez-Pereira and Filippello, 1995). Average price of maize seed in Africa is 6.6 times the average price of grain (CIMMYT, 1994). At these costs, farmers producing between 1.0 and 1.5 t ha−1 in Africa would require yield increases of 20% to compensate for the additional cost of seed. The data gathered to date suggest that low effective demand for seed in Africa acts as a hindrance to growth and diversification of the industry. Accordingly, much of the development assistance applied to seed systems in Africa should be directed toward reducing the high transaction costs associated with exposing farmers to improved seed. Seed is a commodity whose quality cannot be judged prior to purchase and whose overall performance will not be known for several months afterwards (Cromwell, 1996). The implications for improved seed sectors include the need for extensive on-farm testing and intensive information campaigns whenever new varieties are disseminated.

6.3 Sustainable Supply of Seed in Africa Development of sustainable seed supply would serve three needs in Africa: (i) provide a source of planting material to farmers who for whatever reason have been unable to conserve seeds from previous seasons; (ii) provide a channel for the deployment of genetic improvements made possible by conventional plant breeding; and (iii) provide a means for the future deployment of advances made through biotechnology. It is generally accepted that private, unrestrained seed markets offer the most sustainable means of supply of seed to farmers. Yet in Africa, despite an estimated annual seed market of 700,000 t, coverage by private seed companies is limited. Private seed companies are constrained to operating in environments where they can make acceptable profits. Seed companies, at best, can expect to capture about one-third of the increase in profits farmers obtain from using their improved varieties. While a doubling

Seed Systems

87

of yields from 1 to 2 t ha−1 may represent significantly increased profits for small-scale farmers, the opportunity to capture one-third of the profits generated by what is still only a 1 t ha−1 increase may well not be attractive to large commercial seed companies. Acceptable profits are a function of a company’s cost structure, market share, and opportunity costs, and are difficult to analyse from outside any given firm, making critical analysis of seed industry trends in Africa a very difficult task. Empirical observations, however, would suggest that levels of demand and profits in much of Africa are generally not sufficient to support extensive interest from an exclusively industrialized seed market, and both public and private seed distribution is needed. Seed industry development has shown an uneven pattern of development in Africa, with hybrid maize seed sales accounting for a large portion of the private companies in operation. Accordingly, as of 1998, West Africa, with the lowest per capita consumption of maize in Africa, had the lowest ratio of private seed companies per country, with approximately 0.4 companies per country, or less than one company operating per two countries. The ratio in East Africa was 1.5:1 and in southern Africa it was 1.2:1. The country with the highest number of private seed companies in operation was Zimbabwe, with five. Although the seed industry is in a phase of evolution which may bring about changes in this regard, at present the area where large, multinational companies and large national companies can operate profitably can be assumed to be relatively small. Meanwhile, problems associated with their cost and issues of performance have greatly reduced the level of influence exerted by public seed companies (Morris, 1998). Thus, the question naturally arises as to who is available to supply seed in areas where large companies cannot operate efficiently. Yet the alternatives are limited. In view of the recognized limitations of private seed companies, some authors have called into question the adequacy of the private sector response in relation to the diversity of farmers’ seed needs (Cromwell, 1996). Public companies which formerly handled seed of a wide variety of crop species are in some cases being replaced by private enterprises interested solely in seed sales of one or a limited number of highly profitable crops. Lack of coverage by seed companies has led to a series of community-based seed initiatives, which promote seed production and distribution by local farmers (see Plate 8). This work should continue, with greater emphasis placed on lower-cost replication of models in order to reach a larger number of farmers. Another area of future potential may be represented by small, start-up firms, which begin by operating locally, and grow with time. Thus far, the growth of this group has been slow, however, in part due to rigid regulatory structures, which are explored below.

6.4 Seed Policy and Seed Regulatory Structures As seed policies have been changed to favour private sector activity, procedures for registration and release of new varieties have come under increased scrutiny. Tripp and Louwaars (1997) performed a study of seed regulatory structures in Africa and concluded that there was a need to reorganize variety registration and performance testing within systems so that seed regulatory agencies see themselves as allies rather than opponents of regulatory reform.

88

Chapter 6

A pilot project on ‘Harmonization of Seed Policies and Regulations in Eastern Africa’ was initiated in Kenya, Tanzania and Uganda in 1999. As a result of a series of meetings, officials have agreed to a range of changes in seed policy and regulations governing the release of new varieties. Chief among these is the abandonment of the mandatory, 3 years of testing of new varieties (Anonymous, 2000). Phytosanitary restrictions imposed on ten crops were also reduced from 33 to 3. In Kenya, formal release of new varieties until recently required 2 years of testing in ‘Area Yield Trials’ followed by 2 years of testing in ‘National Performance Trials’, following which a candidate variety is submitted for release by two separate ‘Varietal Release Committees’. Many observers have criticized this type of system as being too slow and formalized. More recent guidelines call for two seasons of testing, followed by approval from a single committee (John Kedera, personal communication). As seed systems have become more competition-based, it has been necessary to de-link research institutes from management and control of release mechanisms. In their place, new structures have been created, often under the auspices of national plant health inspection services. It is assumed that these structures will be able to deal with seed companies, NARSs, and other purveyors of new varieties on a more equitable basis. Varietal release structures are key to efficient flow of improved germplasm to farmers. Assisting these groups in putting together transparent, cost-effective, selfsupporting mechanisms for evaluation and release of new varieties should be viewed as a potential area of support by donor agencies interested in seed issues. Decreasing the level of formality will undoubtedly be a key to the success of such reforms, and will probably grow out of participatory breeding methods, which by their nature break down the barriers between farmers and the final, varietal offerings, and in some cases put significant quantities of improved seed into circulation prior to official release by the government (Tripp and Rohrbach, 2000). Seed certification is another key area of concern to those whose aim is reform of the seed sector in Africa (Venkatesan, 1994). Sales of seed to commercial farmers may need to be subject to relatively strict certification procedures in order to protect consumer confidence and provide for legal recourse in cases of large transactions. However, formal seed certification and labelling is viewed as a major constraint to seed market development among non-commercial farmers. In fact, what is sought is an acceptable means of assessment of candidate varieties that places primary emphasis on the responses of farmers, and allows the free flow of improved germplasm toward small-scale farmers through a variety of channels. Achieving this kind of seed regulatory environment among non-commercial farmers, however, will require the involvement of those who determine the process which pertains to formal sale of seed to commercial farmers. As deregulation proceeds, it should be borne in mind that in several active seed sectors, for example in the USA and India, formalized release of varieties is done on a voluntary basis, with informal industry standards being relied upon to provide quality control. Analysis of the constraints to the development of sustainable seed supply among small-scale farmers in Africa indicates four broad areas which provide points of entry for a range of actors from both public and private sectors: breeding, farmer access, seed markets, and regulation.

Seed Systems

89

Breeding As discussed elsewhere in this report, varietal performance is inevitably the principal factor in creating sustainable, effective demand for seed of improved varieties. Participatory variety selection provides a new framework for identifying varieties farmers value most and provides guidance to breeders in further crop improvement efforts. In seed sectors which have recently undergone liberalization, the rate of development and release of new varieties may limit the progress new seed entities can make in establishing a client base. Crop improvement, whether through conventional breeding or molecular breeding, remains by and large a long-term, expensive undertaking. This clearly limits the number of seed companies that are likely to establish their own breeding programmes in Africa over the medium term. The programme size and budgets of public breeding sectors of African countries also limit the speed with which they can develop new offerings. Both public and private breeding efforts continue to be limited by availability of qualified personnel.

Farmer access Overall availability of seed, either through private stockists or publicly based dissemination programmes, continues to limit both the development of viable seed markets and the overall impact of crop improvement. Private dealers must strive to establish a maximum number of distribution points in the major farming areas. Likewise, public breeding efforts need to assist in building farmer awareness of the advantages of new products through multilocation testing initiatives. While it has been amply demonstrated that African farmers are willing to pay for seed when it is of clear benefit to them, seed prices will continue to be a factor in levels of demand for some time to come. Farm gate (producer) prices will play an important role in determining what is an affordable seed price. Recent experience seems to indicate that demand for hybrid seed of grain crops will fall off when seed prices exceed four to five times the price of grain. Seed:grain price ratios for open-pollinated crops may face a limit of only 2 or 3:1. Packaging of seed in small quantities has emerged as an important means of reaching small-scale farmers. Packages of 2–5 kg are common. In some cases, for some grain crops, packages of 1 kg or even less may be appropriate. A recent project aimed at testing the demand for seed of non-traditional seed products (open-pollinated sorghum, millet and groundnut) in Zimbabwe found that, contrary to previous belief, farmers will purchase seed of these crops when it is offered in accessible, sensible ways. They found that 500 g packages were the most popular among small-scale farmers (Rohrbach and Malusalila, 2000). Seed suppliers in western Kenya have proposed that gearing packaging to cash amounts that farmers can reasonably part with (from $0.75 to 1.50) at any given time may be a means of increasing sales. Packaging of seed in transparent, plastic bags has also been cited as a means of assuring farmers they are buying a product of acceptable quality.

90

Chapter 6

Seed markets Related to the issue of building farmer awareness, seed market development requires ample, accurate information on the characteristics of new varieties. Farmers are very reluctant to pay for new varieties they have never seen before. Participatory multilocation testing and demonstration projects are required to overcome this barrier to adoption. Moreover, it is almost certain they will not purchase varieties if the seller cannot provide them with clear information regarding their growth characteristics, including those which may represent an improvement on what is currently being grown. Profit sharing among different entities within the seed distribution chain may be important in establishing seed markets as well. In at least one case, recommendations have been made for margins to be highest where volume of sales is lowest, to encourage more vigorous and extensive distribution (Mark Wood, personal communication). Moreover, because seed sales are seasonal and unpredictable in the early stages of introducing new varieties, providing stockists with credit guarantees may be an effective means of building seed markets. As seed has become an increasingly popular focus of development agencies, free seed distribution has become a factor in the establishment of private seed markets. While emergency, (free) seed distribution following a major rupture in crop production cycles is certainly an effective means of assisting in recovery, it seems clear that free seed distribution needs to be managed in a way that does not stifle demand among farmers who would otherwise purchase seed (Tripp and Rohrbach, 2000). Generally speaking, governmental coordination of seed distribution activities should provide the means of preventing seed distribution from constraining the establishment of viable seed markets.

Regulation Clearly, seed sector liberalization should not be synonymous with allowing seed sectors to operate in a free-for-all. Quality issues are extremely important in providing farmers with a fair return for their seed purchases; however, overall product quality can only be judged several months after the purchase. Seed sector liberalization in several African countries has been accompanied with increasing cases of seed fraud, where unscrupulous ‘seed dealers’ have taken advantage of demand for seed by packaging ordinary grain as seed and selling it to farmers as certified seed. As community-based seed production activities have increased, seed certification has become an increasingly important issue for seed regulators. Following liberalization, seed regulatory units in Africa have experienced serious difficulties in responding to the demands for inspection of increasing numbers of formal-sector seed growers and the many far-flung, farmer-grown seed initiatives. This may involve new categories of seed certification and new categories of seed certifiers, for example, trained NGO employees or government extension agents. Overly bureaucratic variety release procedures have previously been cited as a constraint to seed sector development in Africa. While countries in other regions of the world have eliminated formal variety release requirements or instituted voluntary release structures, there appears to be little support for such an approach in Africa, in the short

91

Seed Systems

term. Recently, seed regulatory bodies have been pressured to accept as little as a single season’s data (presumably from more than a single site), which may be submitted following tests conducted by the variety’s developer or other recognized agency, provided that recognized, accepted commercial check varieties have been included for comparison.

6.5 African Seed Systems Challenges Summary The public sector challenge Table 6.3 summarizes the priority areas of focus for strategies aimed at more sustainable seed supply among small-scale farmers in Africa. For many self-pollinated crops – rice, beans, cowpea and sorghum – dissemination of improved varieties in Africa will continue to rely at least in part on public sector-based programmes aimed at targeted groups of farmers and involving NARSs, NGOs, community-based organizations and, to some extent, small, private companies. Likewise, distribution of clonally propagated crops (sweet potato, yam, banana and cassava) which target needs of small-scale farmers will be best approached via the public sector. Participatory methods of research, including dissemination of small quantities of seed directly to farmers for testing from research teams, goes some way in circumventing Table 6.3.

Principal activities related to diffusion of improved varieties.

Activity

Description

On-farm testing

Multilocation testing under farmer conditions serves to verify that the candidate varieties satisfy adaptation and farmer varietal preferences, and serves to inform farmers of the pending availability on a wider scale of a new variety Crop improvement networks that carry out extensive on-farm testing are in a position to involve farmers in the selection of varieties for release and multiplication Seed multiplication of both foundation (by national breeding programmes or private sector) and certified seed (by NGOs, contract farmers, community-based organizations and private sector) National programmes are increasingly entering into agreements with private companies for licensing of new releases. Marketing/dissemination by public agencies is often carried out via distribution campaigns

Participatory selection process

Multiplication

Marketing/dissemination

92

Chapter 6

the laborious, official release process. Numerous studies have shown that farmers will share seed with family members and acquaintances, and that some dissemination can be achieved in this context, although other studies have shown that seed sharing is not automatic, and may be quite limited (David and Sperling, 1999). In these cases, the involvement of researchers or extension agents in the establishment of informal agreements with farmers may speed dissemination and widen the area of impact (B.B. Singh, personal communication). The aim of such initiatives would not be comprehensive distribution of seed to every farmer in a given area, but achieving sufficient rates of diffusion to ensure that valuable offerings can move via farmer-to-farmer exchange. Participatory breeding methods which aim at exposing farmers to crop varieties while they are still under development should encourage seed dissemination initiatives of this type, and may force major changes in the varietal release process, at least as far as it concerns non-commercial farmers. Needless to say, the above-mentioned process is dependent upon public sector funding provided by national governments and donor agencies. Clearly, in cases where a useful public good (a new variety) can be effectively distributed to needy consumers via a public-sector, campaign-type distribution programme, participants should not hesitate to do so. The underdeveloped state of the economy in Africa, coupled with the continued occurrence of hunger, is ample evidence that the private sector cannot be relied upon to fill all gaps. Thus, one inescapable reality is that crop improvement aimed at benefiting the majority of farmers in Africa will require continued support from the public sector. Over the long term, however, the establishment of a viable and sustainable private sector seed exchange needs to be encouraged. How this is likely to develop in Africa is difficult to predict, in part because the actors are highly differentiated by make-up, size, and access to emerging genetic technologies. Because the market is segmented, products of rather different origin are likely to be a key factor, and a diversity of seed distribution entities is indicated.

The private sector challenge Small, start-up seed companies which focus on niche markets for new varieties and are able to operate on the basis of smaller markets may offer the best chance of sustainable seed supply in marginal areas and for crops of less commercial importance. Finding innovative ways of easing their start-up and entry into operation could ultimately render important benefits to farmers. The general scarcity of venture capital in Africa almost always ensures that there are simpler, more immediate opportunities for return on investment available to local entrepreneurs than the development of a seed company. Providing capital, in-kind support, technical assistance, and other forms of encouragement is likely to be necessary for the creation of the type of seed industry capable of responding to small-scale farmers’ needs over the longer term. There is a growing list of positive experiences related to supporting small-scale seed commerce in Africa (SCODP, 1999; Laker-Ojok, 2000; Muhhuku, 2000; Rohrbach and Malusalila, 2000). In addition, support to public sector breeding programmes which take on the expensive, long-term task of developing new varieties will encourage the operations of small, private companies by offering varieties which respond to the needs of small-scale

Seed Systems

93

farmers in less favourable growing environments. NARSs in Africa continue to embody resources which can be used to develop varieties that can be licensed to seed companies. Finally, it must be recognized that the vast, informal seed market and system of exchange in Africa is poorly understood. Additional study is required to understand more fully how to make use of this resource in improving access by poor farmers to better genetic resources.

7

Conclusions

The first six chapters of this book have tried to call attention to a set of urgent problems faced by farmers trying to secure harvests on hills and savannah plains and in highlands and valleys across Africa. It has tried to identify and describe briefly scientific resources and methods for using them, some of which the authors believe are likely to produce useful, sustainable results. Ultimately, however, achieving food security among Africa’s rapidly growing population of rural poor is not a scientific or even an economic goal, but a humanitarian one. In the end, it is not science that will prevail, but African farmers exerting their will to succeed and conquer hunger, farm by farm, harvest by harvest. Therefore, perhaps the most important observation regarding African agriculture is that African farmers do not wish to be left behind the rest of the world in achieving food security. Following an analysis of the resources and approaches now available for developing more productive and more resilient varieties of food crops in Africa, several broad conclusions and recommendations can be made. ●

●

●

Farmers in Africa cultivate a wide range of crops adapted to a diverse physical environment. Low initial yield potential on these farms is further reduced by losses of yield to both routine and intractable production constraints, contributing to widespread food insecurity and reducing opportunities for economic growth. Crop-specific assessments of problems encountered by small-scale farmers reveal a wide range of traits where genetic improvement could significantly reduce losses among farmers unable to purchase inputs or labour needed to combat these threats by other means. Higher productive potential available through modern plant types could make additional contributions. Many of these aims can be realized through effective plant breeding programmes conducted by national programmes. Because improved varieties in Africa must fit into highly varied, marginal farming conditions, and because farmers consume a significant portion of their harvests, local adaptation and farmer varietal preferences play major roles in determining the overall adoption rate of improved varieties. The added complexity of breeding 95

95

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 7

96

Chapter 7

●

●

●

●

●

●

for these needs presents a strong case for applying a more participatory, agroecology-based approach to crop improvement which takes account of the particular mix of constraints to production that exist in any given zone. Engaging farmers in the decision-making processes related to varietal development makes good sense and may increase adoption rates. Development of national breeding programme strategies involving identification of agro-ecologies, relevant breeding priorities, optimal source germplasm, more efficient use of human resources, and identification of on-going needs for capacity building will be critical to making any investments in plant breeding and biotechnology pay off. International agricultural research centres can assist national teams in developing effective strategies for crop improvement and provide key backstopping roles in the implementation of these strategies. The existence of both routine and intractable biological constraints to crop production among small-scale farmers argues for strong roles for both conventional breeding and biotechnology and for collaboration between national and international research groups. There has been a significant increase in the numbers of qualified plant scientists within Africa’s national agricultural research system, and they are ready to assume an increased role in plant breeding at the national and regional levels. However, strengthening Africa’s biotechnology research capacity will require further investment and assistance from international agricultural research centres and advanced research institutes. In the case of crops for which routine methods for application of molecular breeding or genetic transformation have not yet been developed, there are obvious needs for increased efforts on development of basic biotechnology research tools. In most cases, this will require the capabilities and commitment of advanced laboratories. Moving the products of crop improvement beyond the laboratory or field plot and into farmers’ hands is a complex undertaking. On the one hand, deregulation of seed industries in Africa means better prospects for getting new products to farmers via a more active private and NGO seed sector. However, decreased support to public institutions broadly speaking means they will be in a weaker position to fill gaps left by private sector activity at the outset. An as-yet unknown factor in this regard is the likelihood of growth within the small-scale or ‘local’ seed business sector, and whether public assistance can help in getting this sector moving. Increased support for both types of undertaking will be necessary to make investments in crop genetic improvement pay off. In order to fulfil their stated aims of improving food security in Africa, crop genetic improvement initiatives must be tied directly to seed dissemination schemes of one kind or another. Failure to appreciate the complexity and costs associated with broad dissemination of improved varieties has left many valuable products ‘on the shelf’ and left many farmers without alternatives for improving their production systems. Finally, the powerful combination of biotechnology, agro-ecological approaches to research, and participatory methods of plant breeding represent a new era for crop genetic improvement in Africa. This opportunity to secure Africa’s harvest should not pass without receiving the effort and commitment it merits.

96

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 7

8

Maize

8.1 Brief History of Maize Cultivation and Utilization in Africa Maize was introduced into Africa by the Portuguese at the beginning of the 16th century (Reader, 1998). It has since become Africa’s second most important food crop, behind cassava, and is grown in a wide range of environments ranging from Niger’s northern Sahel to Ethiopia’s highlands to converted forest lands of Sierra Leone. The popularity of maize among African farmers grew slowly until the early part of the 20th century. During World War I, the colonial government in Kenya encouraged (and provided seed for) farmers to plant maize as part of the war effort. Maize cultivation in southern Africa was initially linked to the spread of commercial mining, as maize required less labour to grow and process than the traditional grain crops, millet and sorghum (Byerlee and Heisey, 1997). Although its palatability is often cited as a reason for maize’s continued popularity among rural populations of eastern and southern Africa, higher productivity and lower labour demands can probably be assumed to be at least as important. Sorghum and millet yields in eastern and southern Africa since 1980 have averaged 765 and 729 kg ha−1, respectively, compared with yields of maize over the same period of 1.19 t ha−1 (FAO, 1998). While a portion of these differences can be attributed to the different environments in which the crops are grown, even when grown under identical conditions in semi-arid southern Africa, maize was shown to yield higher (Waddington and Karigwindi, 1995). Comparatively low labour requirements appear to be a second factor in the popularity of maize among small-scale farmers in Africa. Increased school attendance among children who formerly performed bird-scaring chores is cited as an important factor in the shift of land out of sorghum and millet toward maize in semi-arid regions of southern Africa (Rohrbach, 1994). Per capita consumption of maize in Africa is highest in eastern and southern Africa. Maize consumption in Kenya, Tanzania, Malawi, Zimbabwe, Zambia and Swaziland averages over 100 kg per year (CIMMYT, 1990), giving maize a similar position in terms of dietary importance in those countries to rice in Asia. 99

99

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 8

100

Chapter 8

Maize is mainly consumed in African households as a thick porridge, produced by hand pounding (usually preceded by soaking) or grinding in a hammer mill, followed by boiling. Households that depend on hand pounding generally prefer harder, flint-type varieties whose endosperm and embryo can be milled as an integral, whole grain (Nhlane, 1990; Smale et al., 1994). Households that mill their grain generally prefer dent varieties. Eastern and southern Africa almost exclusively grow white maize, with small pockets of yellow landraces in coastal regions and southern Sudan. West and central African households use both white and yellow maize. Seasonally throughout Africa, a considerable amount of maize is consumed fresh, both on and off the cob, either roasted or boiled, as a snack food. Ninety-five per cent of maize produced in Africa is grown by small- and mediumscale farmers who cultivate 10 ha or less. Yields on these farms are usually low, averaging 1.2 t ha−1 (Byerlee and Heisey, 1997). Meanwhile, the productivity range of maize farmers in Africa is perhaps wider than for any other crop. While subsistence farmers of coastal West Africa struggle to produce 700–800 kg ha−1 on farms as small as half of a hectare, large scale, commercial farmers of Zimbabwe harvest some of the highest cereal crop yields in the world, regularly topping 10 t ha−1 on farms larger than 1000 ha.

8.2 Maize Production Levels and Trends in Africa Maize production trends in sub-Saharan Africa and its subregions are shown in Fig. 8.1. The graph depicts eastern and southern Africa as the dominant maize-growing regions of Africa until approximately 1985. Beginning from a relatively small production base in the early 1980s, maize production in West Africa rose above eastern and southern Africa by the early 1990s. This was fuelled by phenomenal increases in maize cultivation in Africa’s most populous country, Nigeria, facilitated in large part by the development at

Fig. 8.1.

Maize production trends in Africa, 1978–1999. Source: FAO (2000).

100

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 8

101

Maize

IITA of earlier-maturing, disease-resistant maize varieties which could be grown in the favourable Sudan savannah ecologies (IITA, 1995). Following generally good rates of production increase during the 1980s, rates of growth of maize production throughout Africa appear to have declined during the 1990s (see Table 8.1). This was influenced by several drought years in southern Africa and more generally by increases in the price of fertilizer following removal of subsidies (Blackie, 1994); in some areas this caused farmers to revert to crops such as cassava and sorghum, which generally grow better on poor soils. The trend in east Africa is particularly worrying. Although the population has grown by 20% during the period 1989 to 1998, annual maize harvests for the subregion have actually declined. Per capita annual maize production in sub-Saharan Africa since 1975 as a whole has varied between 25 and 40 kg (data not shown). Increasing production in West Africa led to rapid increases during 1985 to 1989, but poor harvests during the early 1990s reduced levels considerably. Per capita annual production since 1995 appears to have stabilized at roughly 35 kg. Over the same period, sorghum production per capita has ranged between 20 and 28 kg per person per year.

8.3 Maize Production Constraints Higher maize yields in Africa relative to sorghum and millet are aided in part by farmers’ tendencies to cultivate maize on well-watered and more fertile land. Compared with traditional crops, however, maize is relatively susceptible to moisture and nutrient stress. Drought and low soil fertility are ubiquitous production constraints on small-scale farmers’ fields in Africa (Edmeades et al., 1994). Waddington et al. (1994) estimated average annual losses of maize production due to moisture stress in eastern and southern Africa of 13% of total production, or 1.8 million tonnes per year. Recent estimates of yield reductions due to environmental stresses such as drought (see Plate 9) and low soil fertility have been aided by satellite imaging and geographical information system modelling (Hodson et al., 1999). Modelling losses due to biotic stresses is more difficult. Outbreaks of important pests and diseases of maize are related to complex egg-laying and sporulation responses which are in turn dependent upon difficult-to-predict global environmental factors (moisture and temperature regimes) and human activity (management of crop residues, crop rotations, intercropping) (see Plate 10). Nevertheless, using estimates of incidence and average yield losses per plant, estimates of production losses can be made. Table 8.1. Rate of growth (%) of maize production in Africa and subregions, 1970–1997. Region West Africa East Africa Southern Africa Africa

1970–1979

1980–1989

1990–1997

−2.2 5.9 4.1 2.4

15.4 0.0 7.2 7.3

2.3 −1.6 3.9 0.5

Source: FAO (1998).

101

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 8

102

Chapter 8

Priority biotic constraints of maize in Africa include insect pests (stem borers, grain borers, and weevils), foliar diseases, ear rots and the parasitic weed, Striga. The ranking of these pests in terms of economic losses varies significantly across agro-ecosystems. Table 8.2 shows the estimated area affected by the main pests and diseases of maize in Africa. At an estimated 60% of total area affected, maize streak virus (MSV) ranks as the most widespread biotic constraint to maize production in Africa. However, attempting to estimate production losses due to MSV provides an example of how difficult such a task can be, even on a single plant basis. Ampong-Nyarko et al. (1998) found that grain yield loss in maize due to MSV attack was related to the growth stage at which attack occurred. Plants attacked at early stages of growth (up to seven-leaf stage) suffered 80% or higher loss of yield, while plants attacked shortly thereafter (at the nine-leaf stage) suffered only 20% yield loss.

Table 8.2. Distribution of principal maize production constraints across agroecologies of Africa. Lowland tropical Sub-tropical Drought Striga Leaf blight E. turcicum H. maydis Rust P. sorghi P. polysora Maize streak virus Stalk rot Not specified Fusarium Diplodia Ear rot Not specified Fusarium Diplodia Stem borers Not specified Chilo Buseola Pink stem borer Storage pests Weevils Larger grain borer Termites

Highland

% Area

36 30

21 20

0 1

21 56

35 1

100 0

40 28

2 26 73

42 3 37

58 0 7

28 23 60

37 9 0

1 0 0

0 0 16

18 5 2

29 28 15

25 10 10

0 19 36

33 20 20

35 19 7 15

7 8 69 22

19 0 76 0

33 10 37 33

20

41

38

20

12

15

0

19

23 21a

Source: adapted from CIMMYT (1988). aEstimates based on observations in ten maize-producing countries of sub-Saharan Africa.

102

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 8

103

Maize

Jeffers and Chapman (1994) found that the most important diseases of maize across the mid-altitude, transition, and highland zones of eastern and southern Africa are turcicum leaf blight (Exserohilum turcicum) and common rust (Puccinia sorghi). Average reduction in yield due to foliar and stem diseases across three ecological zones in three seasons in Cameroon averaged 10–12 g per plant. At a conservative estimate of 25,000 plants ha−1 on farmers’ fields, this would represent a loss of approximately 330 kg ha−1 (Cardwell et al., 1997). Applying these losses across 11.7 million ha of maize production in humid lowland and mid-altitude environments in Africa (CIMMYT, 1990) translates to losses of 3.8 million tonnes per annum. Similar methods can be applied to other important pests and diseases of maize in Africa as shown in Table 8.3. While such estimates are prone to high levels of error, if accurate, the calculations would indicate that upwards of 75% of Africa’s maize harvest is lost to pests and diseases prior to harvest. In 1989, subsequent to the CIMMYT study cited above, downy mildew disease of maize (Peronosclerospora sorghi) reached epidemic proportions in parts of Nigeria and began to spread. Downy mildew continues to be a serious disease of maize in seven states of West Africa, the Democratic Republic of Congo, and Mozambique. Recent studies have shown that oospores of downy mildew can transmit the disease through transport of market grain and crop debris (Adenle et al., 1998). Downy mildew-resistant varieties (‘DMRESR-W’ and ‘DMRESR-Y’) have been developed at IITA. Even more recently, maize yields in eastern and southern Africa have been reduced by infection from grey leaf spot (Cercospora zea-maydis), which was first reported in Uganda in 1994 (George Bigirwa, personal communication) and has subsequently become an important disease of maize throughout most of eastern and southern Africa (Pixley, 1997). Grey leaf spot disease increased dramatically between 1991 and 1997 in Malawi (Ngwira, 1998). Postharvest insect pests, maize weevil (Sitopholus zeamais) and larger grain borer (Prostephanus truncatus), account for serious losses of harvest in household maize storage facilities in large areas of Africa. Host plant resistance for both storage pests has been documented in a range of genotypes (Meikle and Markham, 1998) and especially in the Tanzanian landrace ‘Kilima’ (Derera et al., 2000); however, both traits are multigenic in Table 8.3.

Estimates of production losses due to pests and diseases in Africa.

Pest/disease

Striga Blights Rusts MSV Stem borers Total

Area affected (million ha)

Estimated yield loss (%)

4.33 14.0 10.5 12.36 16.48

40a 20b 35c 37d 20e

Estimate of total annual loss of production (million t) 2.07 3.36 4.41 5.48 3.9 19.22

aAuthor’s

estimate. and Chapman (1994). cKim and Brewbaker (1977). dAmpong-Nyarko et al. (1998). eBosque-Perez and Mareck (1991). bJeffers

103

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 8

104

Chapter 8

nature and represent difficult challenges for breeding. Molecular methods may prove useful in screening for resistance for these traits, provided markers can be identified for their quantitative trait loci (QTL).

8.4 Maize Improvement Through Breeding and Biotechnology Maize breeding advances in Africa Maize is one of the most highly bred crops in the world. Maize improvement up to the early 1900s was limited to recurrent selection methods. Population improvement through a series of recurrent selection procedures is aimed at maximizing percentages of favourable alleles at each locus of importance to crop performance in a given environment. Population improvement remains the primary means of improving levels of performance in base populations from which inbred lines are developed. In 1908 George Shull, a researcher at Cold Spring Harbor Laboratory in New York, published a paper which described the basic techniques by which vigour in an experimental variety of maize had been significantly increased through hybridization. This marked the beginning of the use of heterosis in plant breeding. In 1924 the first sale of hybrid maize seed occurred. By 1939, over 90% of maize grown in the state of Iowa was of hybrid varieties (Crow, 1998). These original hybrids sparked a yield gain of approximately 15%, or 300 kg ha−1 (Griliches, 1957). Subsequent breeding, focused more on local adaptation factors, has added approximately 50 kg ha−1 year−1 (Duvick, 1992). By contrast, 60 years later in Africa, only 20% of the maize area planted is of hybrid seed (Morris, 1998). Many African countries where maize is produced still do not have commercial hybrid varieties. An estimated 63% of maize grown in Africa is of unimproved, or landrace, varieties (Morris, 1998) (see Plate 11). Undoubtedly, a major factor in the low usage of hybrid maize in Africa is related to poorly developed seed industries, which are in turn reflective of relatively poorly developed economies as a whole. In the absence of seed sectors capable of organizing large-scale production of hybrid seed, breeders at both international and national levels have concentrated primarily on population improvement, through recurrent selection methods of breeding. Although population improvement has proved effective in the development of open-pollinated varieties (OPVs) which can be cheaply produced and released, these products have seldom been taken up by private companies (Heisey et al., 1998), and their distribution through other means has been constrained by a lack of public sector capacity and funds to promote them. In response to investments in breeding and seed industry development, farmers in Kenya and Zimbabwe were early and enthusiastic adopters of hybrid maize (Gerhart, 1975; Rattray, 1969). Gerhart (1975) calculated that rates of adoption of hybrid maize varieties in western Kenya during the 1960s and 1970s were higher than those of US farmers during the 1930s and 1940s. Adoption rates among farmers in Zimbabwe were no less impressive. In 1960, breeders in Zimbabwe released the single-cross hybrid ‘SR52’, the first commercial use of a single-cross hybrid in the world. ‘SR52’ was reported to increase maize yields among its users by an average of 46% (Weinmann, 1975). Within 8 years, ‘SR52’ was in use in over two-thirds of the maize area planted by

104

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 8

105

Maize

commercial farmers (Rattray, 1969). Today in Zimbabwe, seed companies market over 40 different hybrid maize varieties (Zambezi, 1997). Although hybrids have had the advantage of being promoted by private companies, recurrent selection methods of breeding have also made important contributions to maize productivity in Africa. Although the yield components responsible for the advantages of improved, open-pollinated maize in Africa can be difficult to identify, increased harvest index, increased vigour, and resistance to foliar diseases all appear to have made contributions. It is important to note that even in countries with relatively low adoption rates of identified, improved varieties, the effects of periodic seed purchases by farmers, free distribution of improved varieties, chance out-crossing of landraces with neighbouring plots of improved maize, and farmer selection of seed have inevitably resulted in a broad-based rise in maize yield potential in Africa. On-station yield differences between improved, open-pollinated maize and local varieties are remarkable. In trials of 34 early-maturing OPVs grown at 18 sites in southern Africa in 1996, improved varieties averaged 31% higher yield than local varieties (Pixley, 1996). The improved commercial OPV ‘Manica’ evaluated in 30 on-farm trials without fertilizer or other inputs in Mozambique in 1994 yielded 24% higher than the local (unimproved) variety. A three-way hybrid evaluated in the same study yielded 13% and 34% higher than ‘Manica’ and the local variety, respectively (White and Sitch, 1994). Other countries where OPVs have been widely cultivated include Nigeria, where ‘TZ-B’ and ‘TZPB’ achieved high rates of adoption in the late 1970s, and Ghana, where adoption of the high-lyseine variety, ‘Obatanpa’, and other improved maize varieties, averages 54% (Tripp and Louwaars, 1997). These results point to the kind of broadbased improvements in food security that can be achieved through conventional plant breeding programmes in Africa.

Advances in maize biotechnology Molecular genetics Applications of molecular genetics in maize have progressed rapidly throughout the 1990s. Molecular marker maps have been generated for maize using RFLPs, RAPDs, AFLPs and microsatellites. Molecular mapping techniques have been applied to a variety of traits of importance in maize including turcicum blight resistance (Schechert, 1997), anthesis-silking interval (Ribaut et al., 1996), grey leaf spot disease resistance (Bubeck et al., 1993) (see Plate 12) and resistance to common rust (Coe et al., 1988). Studies of the efficiency of marker-assisted selection (MAS) techniques compared with phenotypic evaluations have been conducted for a variety of traits in maize (Eathington et al., 1997; Lubberstedt et al., 1998). Quantitative trait loci (QTLs) identified using RFLP markers produced correlation values with grain yield of 0.86 compared with phenotypic correlation values of 0.36 (Eathington et al., 1997), implying higher gains from selection for markers correlated with field performance than from selections based on field testing alone. The ability to select the best lines was significantly improved through the combined use of phenotypic and marker information in both high-yielding and low-yielding environments, but the usefulness of markers was higher in the high-yielding environments. However, analysis of four independent maize

105

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 8

106

Chapter 8

populations for six traits using QTLs identified by RFLP markers showed inconsistent results. The authors concluded that employing MAS in this case would necessitate separate QTL mapping for each population (Lubberstedt et al. 1998). Results from CIMMYT’s Applied Biotechnology Center laboratory suggest that the use of genetic markers for aid in selection schemes is so far applicable in the more simply inherited traits where QTLs can be identified that described 40% or more of phenotypic variation. The possibility of using markers in such cases opens up genuine opportunities for incorporation of multiple resistance traits in a single selection programme, whereby field-based evaluations for adaptation can be augmented by differing marker analyses for difficult-to-screen resistance traits. Studies with QTLs for complex traits where markers describe less than 40% of phenotypic variation encountered difficulties with respect to consistency of marker identification (Dave Hoisington, personal communication). Until 2000, the biotechnology centre at IITA was the sole laboratory in subSaharan Africa (excluding South Africa) engaged in marker identification and markerassisted selection in maize. During 2000, new national molecular laboratories were launched in Kenya and Zimbabwe, focusing on marker selection for drought tolerance and resistance to stem borers. MAS schemes which involve collaborations between laboratories sited outside of Africa and Africa-based testing facilities are on-going in Kenya, Zimbabwe and Malawi. Genetic engineering The first maize plant was regenerated from plant cells in the 1970s (Phillips et al., 1988). Since then, a variety of regeneration techniques have been developed using callus tissue, cell suspensions, excised plant parts, and immature embryos. Immature embryos have proved the most useful tissue in maize transformation techniques (Hoisington et al., 1998). The first commercially released transgenic maize variety was developed using the gene gun (Gordon-Kamm et al., 1990). Nevertheless, transformation efficiency to date using the particle gun remains relatively low, at around 1% (Hoisington et al., 1998). Agrobacterium-mediated transfer of DNA into maize was first reported in 1996 (Ishida et al., 1996). Since then, Agrobacterium has been used with increasing frequency due to its ability to transfer larger DNA segments in lower copy numbers (Hoisington et al., 1998). Although transformation of maize for a variety of traits has become routine in many laboratories, no group has as yet reported ‘genotype-independent’ transformation methods, an important benchmark in genetic engineering of specific crop species (Paul Christou, personal communication). As such, applied genetic engineering work on maize is often based on initial transformation of one of several genotypes of known transformability, following which the trait is back-crossed into target germplasm. Transgenic maize accounted for 11.1 million ha of production in 1999, placing it second behind soybean (21.6 million ha) in area planted to transgenic crops (James, 2000). All commercial transgenic maize plantings to 1999 carried either insect resistance (Bt proteins) or herbicide tolerance traits. All transgenic maize in commercial use to date has been marketed by private companies, however an initiative begun in 2000 between KARI, CIMMYT and the Novartis Foundation aims to develop insect-resistant maize for Kenya using Bt genes.

106

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 8

107

Maize

8.5 Principal Challenges for Maize Improvement in Africa Investments made in building the capacity of national maize breeding programmes during the 1980s and 1990s mean that practical strategies for improvement can now move forward relatively rapidly. However, as maize remains both a commercial crop and an essential component of household food security, it is essential that all initiatives begin and end with farmers. Thus, as with other cereal crops, careful attention must be paid to issues of farmer preferences and utilization. Effective seed dissemination will be key to achieving high levels of impact from investments made in breeding and biotechnology. Faltering maize production and productivity levels in all sub-regions of Africa are matters of concern. Maize is the dominant supplier of carbohydrate in the diets of most African households in eastern and southern Africa. However, the very rapid rate of growth in maize production in West Africa during the 1970s and 1980s is evidence of its potential to improve food security and opportunities for rural economic growth in that part of Africa as well. The principal weaknesses of maize in the African context are its susceptibility to abiotic stress, especially drought, and a number of damaging pests and diseases. In view of continued low applications of fertilizer, irrigation, and other inputs, it is likely that pressures from these constraints will increase during the coming decade. Thus, strategies which focus on increasing the yield stability of maize through better combinations of resistance and tolerance traits would appear to be the most appropriate strategy for most small-scale maize farming systems. Continual maize plantings in bimodal production systems of eastern Africa are likely to increase pressures from pests and diseases. The outbreak of grey leaf spot during the 1998 season has been identified as a major cause of food shortages in Tanzania. Losses due to maize streak virus and turcicum leaf blight in Kenya during the same season were especially high. The spread and increased level of infestation by Striga in areas of low soil fertility has been well documented in both Kenya and Malawi (Frost, 1995; Ngwira et al., 1998). These events may indicate a trend which could intensify in coming years. In view of the potential for increased pressure from pests and diseases and drought, an expanded emphasis on these constraints through a progressive, iterative, and participatory process is recommended. Guiding principles for such an approach would include: ●

●

●

Reinforcing the product development strategies and overall capacity of key national breeding programmes so that a pipeline of resilient, public sector varieties (both open-pollinated and hybrid) is developed in each sub-region of Africa. Promoting closer, fuller partnerships between national programmes and the Africa-based IARCs involved in maize improvement so that more effective, product-oriented breeding strategies can be implemented at national level. Identification of important, intractable pests and diseases and abiotic stresses for intensified upstream research involving biotechnology and breeding.

107

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 8

108

Chapter 8

8.6 Maize Seed Systems Maize forms the primary basis of most commercial seed markets in Africa. While some commerce has been developed around open-pollinated varieties, over the past decade there has been a clear move toward hybrid varieties, especially in eastern and southern Africa. The results of this study have shown that considerations of the cost this move implies to farmers should be balanced with the urgent need for development of sustainable seed systems in a competitive, privatized market. In most cases, the benefits carried to farmers through healthy, adapted, vigorous, hybrid seed do cover the price paid. Nevertheless, extensive on-farm testing and demonstration is required to persuade farmers of the benefit of planting improved, purchased seed. Ensuring African maize seed systems are fully competitive will, however, require input from donor agencies. The deregulation of seed sectors in Africa combined with Africa’s diverse agro-ecologies create opportunities for new private operators in Africa. Small, private seed companies of African origin could fill a niche in Africa’s seed markets by helping to commercialize a larger number of varieties with better adaptation to specific agro-ecologies. Small companies of this kind can work with national programmes through licensing agreements that bring in royalty payments to help defray the cost of public breeding programmes. However, this process may require start-up technical and financial support of several kinds. A programme focused on resilient crops will inevitably target some areas where margins cannot support private supply of seed. In these areas, public seed production will need to be developed for deployment of improved genetic material embodied in open-pollinated varieties. Multilocation on-farm testing can bring experimental varieties to small groups of farmers earlier than via official release mechanisms. Multiplication initiatives coordinated by researchers and NGOs, combined with seed sharing among farmers, will distribute seed more widely. Pilot, community-based seed schemes in various countries are currently underway which will provide needed information regarding factors correlated with replicability, sustainability, and cost-effectiveness of such schemes.

8.7 Review of Priority Areas of Research and Development To produce new maize varieties for Africa, a balanced programme approach is needed which takes advantage of potential for improvement from both conventional breeding and biotechnology approaches. Some recent advances in African maize research and production help to illustrate the type of opportunities which exist. 1. Drought resistance – Rain-fed farming systems across Africa are subject to intermittent periods of drought which significantly reduce maize yields. Yield losses due to drought in non-temperate zones of the world are estimated at 19 million tonnes annually. Heisey and Edmeades (1999) estimated that 21% of the maize area in Africa is often affected by drought stress. Drought stress has been exacerbated in recent decades of declining soil fertility, which is often associated with reduced soil water-holding capacity. Research at CIMMYT on the effects of drought stress on maize over a 25-year period resulted in the identification of several screening methods capable of identifying

108

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 8

109

Maize

genotypes which tolerate to some degree the effects of moisture stress. Of these, reduced anthesis-silking interval (ASI) trait has been selected as a relatively straightforward, easily-measured trait which correlates well with yield under stressed conditions. By reducing the interval between pollen shed and silking in maize, better synchronization is achieved within these two plant processes critical to fertilization. Shortened ASI is now being used as an evaluation criterion in ten countries of southern Africa through the Southern Africa Drought and Low Fertility Network. Additional upstream research on drought resistance using molecular markers and genomics is also warranted. 2. Nutrient use efficiency – Resistance to low soil nitrogen has been observed to be associated with drought tolerance in maize. More recent work on phosphorus acquisition efficiency in maize appears to show improved performance for this trait through increased resistance to soil acidity, related to better-developed root hairs and exudation of organic acids by some maize varieties. In view of the general sensitivity of maize to low nitrogen and phosphorus availability and of the variation expressed in some genotypes, both these mechanisms appear to merit further research. 3. Multiple resistance to foliar diseases and ear rots – Reduced maize grain production due to pathogen-caused loss of photosynthetic area and phytotoxic effects is a preventable type of loss which affects small-scale farmers most directly. Making maize more resilient to multiple foliar pathogens and ear rots is becoming increasingly possible by the identification of molecular markers for resistance genes. Efforts in this area would include marker identification work taken on primarily by international centres, followed by marker-assisted selection programmes conducted in Africa by national breeding programmes. ● The identification of a stable molecular marker for MSV resistance on chromosome 1 of maize (Hoisington, personal communication) means that back-crossing of this gene into well adapted local varieties can be accelerated in national programmes. It also means that cloning and transfer of this gene can now proceed, facilitating its movement into a wide variety of otherwise unmodified sources. ● Clearly, a concerted emphasis on breeding for grey leaf spot resistance is required for eastern and southern Africa. Molecular markers have been identified that are linked to genes for resistance to grey leaf spot. ● Ear rots which produce compounds toxic to humans have been a focus of research conducted in Kenya and parts of West Africa. Improved methods of selection for resistance to these pathogens may yield added benefits to human health. ● Turcicum leaf blight is a major cause of yield loss. Resistance levels to the disease in improved maize varieties are variable. Efforts to improve levels of resistance through deployment of the four known resistance genes should continue. 4. Stem borers – A considerable amount of work has already been invested in stem borer resistance, including identification of markers for resistance to multiple species of borers, screening methodologies and identification of potential donor lines. Further work can proceed through both conventional and marker-assisted selection methods. However, in view of the success of ‘Bt maize’ in controlling stem borers in other regions, the development of ‘Bt maize’ for Africa should be given priority. CIMMYT is now producing transgenic lines of African maize with Bt genes for borer resistance. 5. Postharvest insect pests – CIMMYT Harare has initiated research on a limited number of maize lines adapted to southern Africa which showed resistance to weevils. Breeding work should now be undertaken to confirm the usefulness of this resistance

109

A4138:AMA:DeVries:First Revise:19-Oct-01

Chapter 8

110

Chapter 8

within breeding programmes. Due to the difficulty of screening for resistance, however, identification of molecular markers is likely to speed introgression of resistance genes into African-adapted populations. Meanwhile, transgenic maize has been produced with avidin glycoprotein from chicken egg white, which has been found to prevent development of insects that damage pests in storage (Kramer et al., 2000). 6. Striga – Research on Striga-resistant maize has yielded promising avenues for continued work involving gene doning in Tripsacum, gene cloning via mutator transposons, and assembly of technology packages utilizing herbicide-resistant maize. 7. Ecosystem development factors – In addition, IARCs and NARSs are pursuing ecosystem development strategies in underexploited environments such as West Africa’s southern guinea savannah and humid forest zones and eastern and southern Africa’s semi-arid regions. As the agro-ecologies of these areas become better understood, this should also lead to the identification and prioritization of needed traits and may require the development of new base populations for breeding purposes.

110

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 8

9

Sorghum

9.1 Brief History of Sorghum Cultivation and Utilization in Africa Sorghum, together with millet, represents Africa’s most important contribution to the world food supply (see Plate 13). Sorghum was domesticated in Ethiopia and parts of Congo, with secondary centres of origin in India, Sudan and Nigeria (Fredricksen, 1986; Mukuru, 1993). Harlan and de Wet (1972) described five races of cultivated sorghum which have come into common usage among sorghum breeders. They are: durra, kafir, guinea, bicolour and caudatum. All five major races of sorghum originated and continue to be cultivated in Africa, with several races often being used for differing purposes within the same agro-ecosystem. Guinea sorghum varieties are cultivated primarily in West and central Africa, with some landraces spreading as far south as Mozambique. Kaffir types originated in eastern and southern Africa. Durra sorghums developed primarily in Ethiopia and the Horn, but are also spread across a wide section of Nigeria and savannah areas of West Africa. Caudatum varieties were developed in Kenya and Ethiopia. Bicolour, the least important of cultivated races, is sparsely distributed through East Africa (de Wet et al., 1970). Although sorghum cultivation has become an important component of agriculture in a few industrial countries, it remains largely a developing country crop. Ninety per cent of the world’s area cultivated to sorghum is in developing countries, mainly in Africa and Asia. In Africa, 74% of sorghum produced is consumed in the home (FAO/ICRISAT, 1996), primarily as thick or thin porridges, or as traditional beer. Other African foods prepared from sorghum include green ears, flat breads and rice-like dishes prepared using boiled sorghum (NAS, 1996). Sorghum stover is an important source of animal feed in mixed farming situations. Sorghum has a nutritional profile roughly similar to that of maize. Most varieties register approximately 9% protein, generally 1–2% higher than maize; however, sorghum is generally lower in fat content by a similar amount. Both grains are low in lysine, and the crude protein digestibility of sorghum is severely reduced by high 111

111

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 9

112

Chapter 9

percentages of prolamine and tannins, necessitating additional processing of grain in the home. It is probably due to the grain’s prolamine content that sorghum is often fermented prior to consumption (NAS, 1996). Tannins (present to discourage bird damage) are removed in the de-hulling process.

9.2 Sorghum Production Levels and Trends in Africa In 1995, world production of sorghum was 53 million tonnes, or 4% of total cereal production, making sorghum the world’s fourth most important grain crop (House, 1996). Due to its excellent adaptation to semi-arid and arid climates, the proportion of total grain production represented by sorghum in semi-arid countries of Africa is very high (see Table 9.1). The rate of growth of sorghum production in Africa during the period 1985 to 1994 was 1.7%, however, the growth rate of area planted to sorghum was 2.9%, indicating faltering yields of sorghum in some areas. Although maize is generally considered to be more sensitive to low soil fertility, reductions in soil fertility levels throughout Africa have affected sorghum yields as well, reducing growth rate of sorghum yields during 1985 to 1994 to −1.2%. Partially due to the harsh conditions in which the crop is normally grown and partially due to low harvest indices of most popular cultivars, sorghum is relatively low-yielding. Average sorghum yields in Africa are 780 t ha−1 (FAO/ICRISAT, 1996). Figure 9.1 shows sorghum production trends in sub-Saharan Africa as a whole and in the sub-regions. The graph plainly shows the bulk of African sorghum production to be centred in West Africa. West Africa is responsible for 60% of total sorghum production in Africa and roughly 25% of all sorghum grown in developing countries (FAO/ICRISAT, 1996). In some farming systems, maize has replaced sorghum as the principal cereal crop (Rohrbach, 1994). However, the trend over the past 35 years shows sorghum holding a relatively constant position. In southern Africa, for example, total sorghum production was 15% that of maize production in 1961. By 1997, that figure had decreased only slightly, to 12%.

Table 9.1. Importance of sorghum production in selected countries of sub-Saharan Africa. Country

Sorghum production (% of total cereals)

Burkina Faso Cameroon Chad Mali Rwanda Sudan Africa

53 40 41 38 52 72 18

Source: House et al. (1997) and FAO/ICRISAT (1996).

112

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 9

113

Sorghum

Fig. 9.1.

Sorghum production trends in Africa, 1975–1998. Source: FAO (1998).

9.3 Sorghum Production Constraints Sorghum crops suffer from attack by 16 major diseases, among which grain mould (Curvularia sp. and Fusarium moniliforme) (see Plate 14), long smut (Ustilago sp.), anthracnose (Colletotrichum graminicola), grey leaf spot (Cercospora zeae-maydis), sooty stripe (Ramulispora sorghi) and head smut (Sphacelotheca reiliana) are of major importance in Africa (Thakur et al., 1997). Sorghum is also attacked by a variety of panicle- and stover-feeding insects. The panicle pest of greatest importance in African sorghum is probably sorghum midge (Stenodiplosis sorghicola), followed by African sorghum head bug (Eurystylus oldi) (Henzell et al., 1997), although landraces of sorghum often have resistance to the latter pest. Insects which attack the foliage and stems of sorghum include green bug (Schizaphis graminum), shoot fly (Atherigona soccata) and spotted stem borer (Chilo partellus). Stem borers are an especially important pest of sorghum in eastern and southern Africa, with few or no sources of host-plant resistance having been discovered (van den Berg, 2000). A crop-loss compared with crop-improvement benefit analysis of sorghum production constraints performed by ICRISAT in 1992 (ICRISAT, 1992) provided a ranking of pest and disease importance in sorghum for Africa and Asia combined (Table 9.2). Among the other major constraints to sorghum production in Africa, day-length sensitivity has received considerable attention. Large areas of sorghum cultivation in Africa are devoted to photoperiod-sensitive varieties which commence reproductive stages of growth when days shorten to a critical period, regardless of their time of planting. Fixed timing of grain filling regardless of overall plant maturity can reduce yield significantly. However, the primary function of photoperiod sensitivity is to ensure that the grain matures under dry conditions, as sorghum grain (and home-stored seed) deteriorates rapidly when stored wet. As such, elimination of photoperiod sensitivity in

113

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 9

114

Chapter 9

Table 9.2. Yield loss estimates and return to crop improvement for sorghum in Africa and Asia. Identified constraint

Yield loss ($ million)

Potential gain via crop improvement ($ million)

1744 334 129 274 153 102 77 198 21

143 124 121 102 83 67 43 38 15

Drought Stem borer Grain mould Shoot fly Striga Anthracnose Leaf blight Head bug Smut

sorghum varieties for use by small-scale farmers is limited by rainfall patterns and farmers’ flexibility in postharvest management of the crop (Gomez and Chantereau, 1997). Sorghum and millet are the most important grain crops of the semi-arid regions of Africa and Asia. Both crops display impressive abilities to withstand low soil moisture status and high air and soil temperatures. Drought tolerance in sorghum is still poorly understood, but has been attributed to several mechanisms, including leaf rolling under water stress, osmotic adjustment and the stay-green character (for post-flowering drought) present in some varieties (Rosenow et al., 1997). However, there is disagreement among sorghum breeders regarding the usefulness of the stay-green trait under severe drought conditions. At high levels of moisture stress, leaf senescence may be advantageous in reducing transpiration to a sustainable level (Fred Rattunde, personal communication). Researchers gathered to discuss options for improving drought tolerance in sorghum in 1999 cited stay-green, lodging resistance, resistance to charcoal rot, seed filling and stem reserves as potential selection criteria (CIMMYT, 2000).

9.4 Sorghum Improvement Through Breeding and Biotechnology Sorghum breeding advances in Africa Breeding methods Sorghum is considered to have high levels of untapped diversity. The largest collection of sorghum germplasm is the US sorghum collection (held at the National Seed Storage Laboratory in Fort Collins, Colorado, and the USDA-ARS Plant Genetic Resources Conservation Unit in Griffin, Georgia), containing over 40,000 accessions. Less than 3% of these have been used in crop improvement (Dahlberg et al., 1996). Sorghum is a mostly self-pollinated crop with a variable percentage of out-crossing existing in most cultivars, ranging from 5–15%. The most common methods of selection are based on pedigree techniques developed for self-pollinated crops such as rice and wheat. However, breeding teams at Purdue University, University of Nebraska,

114

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 9

115

Sorghum

Kansas State University, and ICRISAT-Asia Center have applied population improvement techniques (including reciprocal recurrent selection) on sorghum based on quantitative genetics theories of increasing favourable alleles within base populations (Rattunde et al., 1997). Gains from selection from such programmes tend to be quite high, in the order of 150–400 kg ha−1 (Rattunde et al., 1997). However, a long-term population improvement programme conducted in Mali during 1970 to 1988 has since been discontinued for lack of sufficient progress. Following widespread success of caudatum races of sorghum in India, international sorghum improvement programmes in Africa have based much of their efforts on caudatum germplasm. Caudatum releases grown under medium-to-high input levels in Africa have consistently shown yield advantages over guinea varieties, in part due to higher planting densities made possible by shorter plant types. Although caudatum varieties have performed well and achieved a high level of acceptance among local farmers in southern Africa (Obilana et al., 1997; Rohrbach and Makhwaje, 1999), in West Africa adoption rates have remained low (Touré et al., 1998). Recently, more emphasis has been placed on guinea–caudatum crosses and guinea crosses with other races, and several groups have begun development of guinea hybrids and guinea synthetics (Fred Rattunde, personal communication). At the same time, some farmers have demonstrated increasing interest in caudatum varieties based on ease of harvest, higher yield potential and better quality of forage. Guinea sorghum stalks, although often used in house construction, are indigestible by cattle. As housing materials improve, therefore, farmers may become more open to use of caudatum varieties. Recent breeding efforts by several groups have emphasized the use of ‘tan plant’ mutants, which are reported to carry higher yield potential and white grains which do not discolour on contact with pigmented glumes (Rosenow, 1997). However, there is not complete agreement regarding the potential of tan plant types for African agriculture, where yield is often reduced by biotic and abiotic stresses and few markets reward farmers for producing a higher quality product. Studies of isolines of tan and non-tan plants have shown adaptation advantages in non-tan lines in West Africa (Rattunde, personal communication). Problems of low adoption Improved sorghums have achieved moderate levels of adoption in parts of southern Africa (Obilana et al., 1997), Cameroon, and Chad (Yapi et al., 1999). In other areas, adoption rates of improved sorghum among small-scale farmers have been low (Ibrahim et al., 1995; Ahmed et al., 2000). Low rates of adoption of improved varieties are probably influenced by poorly developed commercial and/or public seed systems and low usage of fertilizers and other inputs in areas where sorghum is grown (Ahmed et al., 2000). However, a review of on-farm trial data showing higher yields but low acceptability among farmers points to other factors, as well (White and Chapman, 1996). These trends point to the need for more farmer-focused, participatory methods of improvement which identify constraints and varietal preferences prioritized by local farmers. These issues are explored in greater detail below. Persistently low rates of adoption of improved varieties in West and central Africa point to a potential need for modification in approaches employed in the improvement of the crop. Some basic principles for a new approach might include:

115

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 9

116

Chapter 9 ●

●

●

As an indigenous crop consumed primarily in the home, acceptable grain quality for food processing and preparation is a sine qua non to widescale adoption among small-scale farmers. Better understanding of traits which confer acceptable grain quality may allow greater efficiency in transferring both routine and intractable resistance and tolerance traits to farmers via higher adoption rates. Because of the complexity of quality-related issues, success in this area will most likely depend upon direct collaboration among breeders, plant scientists, food scientists and farmers. As such, deployment of resistance genes for priority pests and diseases will be limited by breeders’ ability to deliver these improvements within a package which is acceptable to local consumers.

The success of any new approach would appear to depend upon farmer participation both in priority setting for breeding programmes and in selection of varieties, and a greater understanding of the importance of grain quality in marketing of harvests destined for urban markets. In fact, farmer and consumer participation in sorghum improvement in West Africa may represent one of the best opportunities yet for demonstration of the power of wider participation in crop improvement initiatives (Ejeta, personal communication). Grain quality issues Herdt and Capule (1983) previously analysed the persistent use of traditional varieties of rice in Thailand in spite of the availability of improved varieties. They determined that in some areas the price discount for improved varieties effectively offset the advantages they represented in yield. When improved varieties began to be introduced with quality characteristics preferred by farmers, they were adopted rapidly. Likewise, food scientists who have analysed sorghum quality characteristics have become increasingly capable of predicting the acceptability of improved varieties based on the quality of food products they produce (Fliedel and Aboubacar, 1998). Studies conducted using sorghum flours from West, southern and east Africa revealed significant differences in flour texture and total water content of porridges consumed. Households preferred varieties with high amylose starch content and low flour lipids and proteins. Few improved varieties have scored high in such tests; nevertheless, breeding teams have failed to take full advantage of food scientists’ ability to inform them of the probable success of their offerings at the household level. Research conducted in parallel to this by economists at Michigan State University and ICRISAT (Rohrbach and Makhwaje, 1999) has revealed that sorghum grain market development suffers from a host of quality-related issues beginning at the farm gate and extending to the level of confectioners hoping to make usable products from these grains. This relates to problems of cleaning, grading, and differentiating of sorghum grain according to colour, grain size and overall preparation characteristics. Out of this impasse has formed a small but growing contingent of sorghum specialists calling for a new, more participatory and more integrated approach to sorghum improvement which would build in marketing and quality aspects. The integration of breeders with food scientists and economists working on utilization issues would represent a radical shift from current, production-factor-led initiatives, and, due to its complexity, would involve certain risks of its own. However, it is important to note

116

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 9

117

Sorghum

the growing belief that sorghum’s integral position within the dietary and household management traditions of Africa may require a different approach to that employed in other grain crops such as maize and rice.

Advances in sorghum biotechnology Molecular genetics RFLP linkage maps have been developed for sorghum and several are highly saturated (Chittenden et al., 1994; Pereira et al., 1994; Tao et al., 1996); however, few important genes have been placed on these maps, and they have thus proved of little practical use for purposes of genetic improvement. Development of sorghum linkage maps has been greatly assisted by the high level of conservation of genomes between sorghum and maize (Binelli et al., 1992; Berhan et al., 1993) and by the relatively small size of its genome (three times smaller than maize). A sorghum bacterial artificial chromosome (BAC) library has been constructed at Texas A&M University (Woo et al., 1994), and the same programme currently aims to develop a high-resolution molecular map of sorghum in order to facilitate marker-assisted selection (Johanson and Ives, 2000). Sorghum breeders concluded in mid-2000 that development of a saturated simplesequence repeat (SSR) map of sorghum is still a priority for furthering sorghum improvement through molecular breeding (CIMMYT, 2000). Meanwhile, Bhattramakki et al. (2000) have published an integrated RFLP and SSR linkage map composed of 147 SSR and 323 RFLP loci. Several studies are currently underway aimed at employing MAS for the improvement of sorghum. Researchers at Texas Tech University are involved in identification of markers for the stay-green trait (Nguyen et al., 1996). A second team at Texas Tech has initiated a project on marker identification for osmotic adjustment (drought tolerance trait) in sorghum. Researchers at Texas A&M are working on marker identification for various disease resistance traits, including downy mildew, anthracnose, leaf blight, head smut and grain moulds (Magill et al., 1997). Genetic engineering Once considered recalcitrant to regeneration in vitro, methods have now been developed for cell culture regeneration using immature embryos, young leaf bases, shoot apex, and immature inflorescences (Bhaskaran and Smith, 1990). Successful anther culture has also been reported from six varieties of sorghum (Kumaravadivel and Rangasamy, 1994). Useful cultivars have also been developed from somaclonal variation methods (Smith et al., 1997). Sorghum has been transformed and stable expression of genes obtained using microprojectile bombardment of immature embryos (Casas et al., 1995; Rathus et al., 1996) and more recently via Agrobacterium-mediated transfer by scientists at Texas A&M (Nguyen et al., 1996). Pioneer Hi-Bred of the USA has successfully transformed sorghum with a high lysine gene, but have not commercialized this genotype (Johanson and Ives, 2000). Transformation of sorghum via Agrobacterium, however, has so far reportedly been less efficient than for rice and maize (Nguyen et al., 1996). CSIR

117

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 9

118

Chapter 9

Bio/Chemtek of South Africa have reported only chimeric (non-stable) transformation of sorghum (Johanson and Ives, 2000). Thus, whereas significant academic research has been invested in sorghum biotechnology, the application of this new knowledge to genetic improvement of sorghum for Africa has lagged considerably. In view of the important role the public sector is destined to play in this low-value, high-volume African crop, the stage appears set for a donor or group of donor agencies and African NARSs to enter into collaborations aimed at extending the benefits of this research to farmers, possibly focusing on resistance to stem borers, via Bacillus thuringiensis.

9.5 Principal Challenges for Sorghum Improvement in Africa West Africa focus Given its predominance as a crop and dietary component in the region, this document focuses primarily on challenges of sorghum improvement in West Africa. Sorghum accounts for a far greater percentage of total cereal production (55%) in West Africa than in either eastern (10%) or southern Africa (less than 5%). Furthermore, the impact to date of sorghum improvement, as measured by uptake of released varieties, has been greater in eastern and southern Africa than in West Africa (improved sorghum varieties currently cover approximately 26% of total area in each of Botswana and Zambia and 40% of total area in Zimbabwe (Obilana et al., 1997), compared with 20% in Mali (Ahmed et al., 2000)), implying that some of the gains available through sorghum improvement may have already been achieved in eastern and southern Africa. Moreover, advances made in developing and disseminating drought tolerant maize in southern Africa may contribute to past trends of replacing sorghum with maize in that region. It is unlikely, however, that maize can be made sufficiently drought tolerant to replace sorghum in extensive areas of West Africa which receive less than 600 mm of rainfall annually.

Focus on adaptation and accessibility As an almost purely locally-consumed commodity, the need for an emphasis on end-user acceptance in West Africa is understood. To the extent possible, therefore, biotechnology and breeding efforts must be applied to locally adapted and accepted germplasm. In addition, in view of the region’s marginal production conditions and the small resource base of the vast majority of farmers, sorghum improvement focusing on West Africa should aim at developing products which are within the reach of small-scale producers. Based on recent economic indicators and analysis from West Africa, it would appear that to treat the region’s sorghum farmers as a homogeneous unit of producers and consumers would be a mistake (Coulibaly et al., 1998). Therefore, increased analysis of agro-ecological diversity in sorghum-based farming systems of West Africa may lead to more precise targeting of breeding efforts. Devaluation of the West African franc in the early 1990s has led to an upsurge in agricultural production in some sorghum-producing countries, most notably Mali and Burkina Faso. Meanwhile, major

118

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 9

119

Sorghum

increases in cotton production have improved liquidity among small-scale producers. Large increases in local prices of rice and wheat (the two major imported food commodities) have led to substitution of those products in the diets of many urban consumers. Increased demand for the locally produced cereals, sorghum and millet, have created incentives for farmers to intensify production of those crops. Of late, farmers have shown increasing interest in caudatum varieties in Mali such as ICRISAT cultivars ‘ICSV 901’ and ‘ICSV 1079’ (Dale Hess, personal communication). Overall, the scenario created by economic reforms in West Africa appears to favour moves toward higher-productivity production systems. Major changes to be anticipated among farmers would include increased rates of usage of inorganic fertilizers and higher-yielding varieties. Within this context, the potential for adoption of hybrid sorghums may be higher than in the past. The opportunity also exists, therefore, for science to support such improvements through the development of new technologies, including adapted hybrid varieties.

Dual track approach Promoting food security, equity, and economic growth among sorghum producers in West Africa during the coming decade may lend itself to a ‘dual track approach’, which pursues differing strategies for resource-poor and better-off farmers. Breeding strategies and objectives emanating from this approach are explored in greater detail below. A brief description of the principals guiding science and breeding in each environment is given by a ranking of the principal thrusts within each improvement initiative, as follows. Medium/high input environments:

1. Adaptation 2. Yield 3. Quality1 4. Resistance

Low input environments:

1. Quality 2. Resistance 3. Yield 4. Adaptation

9.6 Sorghum Seed Systems Sorghum seed delivery is underdeveloped in most parts of Africa, and in its current state should be considered a major constraint to the distribution of the fruits of research. In spite of its importance to crop improvement at the farmer level, little study has been dedicated to understanding how sorghum seed delivery in Africa can be made more sustainable, although studies of traditional seed collection and conservation have been conducted (World Vision International, 1995; INTSORMIL/INRAN, 1998). Seed companies in eastern and southern Africa have been reluctant to transfer seed

1

Including aspects of both plant type and grain quality.

119

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 9

120

Chapter 9

production and marketing capacity from maize to sorghum, primarily out of concern for sorghum’s low profitability and erratic seed demand (Ahmed et al., 2000). In Niger, farmers who purchase improved varieties do so primarily following a drought year, because improved varieties are earlier maturing than local varieties (Salifou, 1998). Farmers who purchased improved seed in Niger were primarily farmers who had some link to a producers’ association where credit and other purchasing assistance is available. In contrast, hybrid sorghum seed sales in Sudan and South Africa have been largely profitable (Ahmed et al., 2000; Ejeta, 1998). Experience with hybrids in these countries and India have prompted some researchers to propose a shift toward hybrid sorghum in West Africa as well, most notably in Niger, where a conference was recently held on the subject of hybrid sorghum and millet (INTSORMIL/INRAN, 1998). The perceived potential for hybrid sorghum varieties in West Africa is based largely on experience from elsewhere in the developing world. Hybrid sorghum varieties were first released in the USA in 1956 and in India in 1964. Sorghum seed markets in India and Sudan developed largely on the basis of breeders’ enhanced ability to package yield potential and stress tolerance within hybrid varieties and seed companies’ ability to realize an acceptable profit margin from dependable sales of hybrid seed. The first hybrid sorghum in Africa, ‘Hajeen Dura-1’ was released in Sudan in 1983. Hybrid sorghum varieties have been available in Zimbabwe for some time and have recently been introduced in Zambia and Botswana. Until recently, however, no hybrids had been commercialized in West Africa. Hybrid varieties of sorghum have demonstrated high levels of heterosis. The average level of heterosis in released hybrids in Africa to date is 45% (House, 1996). The US figure is only 36%. Unlike in maize, where hybrid varieties have often been perceived (often mistakenly) as having less advantages in marginal conditions, hybrid sorghums are generally accepted as having both high yield (hybrids in Niger, for example, generally yield twice as much as local varieties under similar management) and greater resistance to environmental stress, plus increased seedling vigour and earlier maturity. The importance of these traits in semi-arid environments lend increased value to hybrid sorghums in most of the areas where sorghum is an important crop. Breeders of long experience with sorghum seed systems further state that commercial supply of sorghum seed has rarely developed without hybrids. At present in Niger there is no public seed production/distribution entity and only a single, small, private seed company, which in 1997 produced 200 t of seed of various crop species. Previous production of seed in Niger (3511 t in 1985 – 92% of total needs) focused primarily on millet and was heavily subsidized by the government. The CMDT (Malian cotton parastatal) is reported to have developed hybrid varieties and is testing them on-farm this season. In Mali, as well, seed distribution capacity is very low. Government projects in both Mali and Niger distribute seed of improved cultivars locally in small quantities. There is no private cereal seed company in Mali. In the absence of other means, NGOs have increasingly taken up the task of sorghum seed distribution, with some level of success (Rosenow, 1997). In view of the lack of responsiveness of the private sector to seed distribution opportunities, researchers have consistently called for the development of the informal seed system. To date, however, no clear plan has been advanced for non-commercial distribution of sorghum seed.

120

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 9

121

Sorghum

9.7 Review of Priority Areas of Research and Development In prioritizing upstream research for the various constraints to production of sorghum, several options exist. 1. Striga. The most important biotic constraint to production of sorghum in sub-Saharan Africa is probably Striga hermonthica. Breeding initiatives at ICRISAT and Purdue University have developed sorghum varieties with moderate levels of resistance. More recently, wide crosses to wild sorghum have shown promise (Gebisa Ejeta, personal communication). 2. Resistance to anthracnose. Anthracnose is perhaps the most damaging disease of sorghum in a large area of West Africa, and both landraces and introduced varieties are affected. Developing adequate levels of resistance has proved extremely difficult, due to low heritability of the trait. 3. Resistance to downy mildew. As adoption of more uniform, improved varieties increases, downy mildew incidence is likely to rise. Management of downy mildew via host-plant resistance is difficult, but may yet present a more accessible possibility than use of fungicides among small-scale farmers. 4. Insect resistance. Resistance to panicle pests in sorghum may form another priority area of research. Sorghum midge is reportedly the most ubiquitous and damaging insect species of sorghum, worldwide. Resistance is controlled by an unknown number of recessive to partially dominant genes (Aggrawal et al., 1988). It is a polygenic trait which has been suggested as an ideal candidate for improved control through markerassisted selection (Henzell et al., 1996). Stem borer-resistant sorghum would be of undisputable value to sorghum farmers of southern Africa. The possibility of developing transgenic ‘Bt sorghum’ has been mentioned by several authors, but thus far no strategies have been advanced. Its development should be considered a priority. 5. Sorghum grain mould. Sorghum grain mould is a major problem on improved cultivars in most of West and central Africa. High levels of resistance to grain mould is one reason farmers of the region remain attached to traditional, guinea varieties. Guinea varieties produce a loose, branching head which dries quickly following rains. Most improved varieties have more compact, non-branching heads. Breeding initiatives have discovered various sources of resistance, including waxes, glume pigmentation, polyphenols and corneous grain texture (Stenhouse et al., 1996). Marker identification studies are also underway. Antifungal proteins have also been proposed as a means of resistance. Their use will require genetic transformation methods. 6. Heterosis in adapted materials. Several researchers have advanced plans for the development of guinea hybrid sorghum varieties for West Africa. Given high potential levels of heterosis in such varieties, yields could be significantly increased, provided the new varieties were well adapted and seed was available at affordable prices. 7. Pest/disease complexes of localized importance. Beyond these intractable problems, there exist a number of pests and diseases of perhaps lesser individual importance that combine to form complexes which reduce yields considerably in farmers’ fields. Like head bugs and grain moulds, they may create barriers to adoption of improved, higher yielding cultivars. Resistance to downy mildew, anthracnose and charcoal rot could form the focus of molecular studies, and also form the focus of downstream support to national breeding programme efforts.

121

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 9

122

Chapter 9

8. Phosphorus acquisition efficiency. Sorghum varieties with differing levels of phosphorus uptake efficiency have been identified in Brazil (Schaffert et al., 1999). These genotypes, which are adapted to Brazil’s cerrado region, should be tested for performance in low phosphorus soils of Africa. In the event a mechanism for increased uptake efficiency can be identified, breeding strategies could be advanced to enhance expression of this trait in adapted germplasm. 9. Sorghum seed systems. In view of the above discussion, seed systems must represent a focus of any crop improvement programme aimed at sorghum. The scope of the present study has been too brief to gather information needed to make recommendations on the improvement of sorghum seed supply. In order to gather more information, it will be necessary to sponsor a study and/or a workshop focused on sustainable supply of pure line varieties.

122

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 9

10

Pearl Millet

10.1 Brief History of Millet Cultivation and Utilization in Africa Pearl millet (subsequently referred to as ‘millet’) is a crop of vital importance to millions of African families living in semi-arid regions of the continent (see Plate 15). Millet is one of the world’s most resilient crops. In many areas where millet is the staple food, nothing else will grow. Several phrases from a recent publication by ICRISAT (1996) perhaps sum it up best: We are talking about a crop that is virtually unimprovable – a crop that grows where not even weeds can survive. A crop that has been improved by farmers and through natural selection for thousands of years. A crop that produces nourishment from the poorest soils in the driest regions in the hottest climates. A crop that grows straight out of sand dunes. A crop that survives sand storms and flash floods.

Millet is descended from wild grasses native to the central Saharan plateau region of Niger. From there it spread to East Africa and India, where millet ranks as the fourth most important cereal. In West Africa millet is consumed primarily as a thick porridge, or toh, but it is also milled into flour to prepare breads and cakes. Millet is the mostpreferred cereal grain grown in Sahelian countries, Senegal, Mali, Niger and Burkina Faso, and is consumed in preference to sorghum. In northern Nigeria, millet flour is used in making a popular fried cake known as ‘masa’. Roasted young ears are a popular food for children. While sorghum is perhaps a better-known crop in most of the world, most inhabitants of the Sahel actually prefer to consume millet, a fact which should encourage greater investments in its improvement. Feeding trials conducted in India have shown that millet is nutritionally superior for human growth to maize and rice (NAS, 1966). It has slightly higher protein content (average of 16%) than maize and roughly twice the fat content (5–7%) of most maize varieties, and is particularly high in calcium and iron. It has lower levels of fibre and most vitamins, although its pro-vitamin A content is relatively high. One important problem for households which rely on millet as a food staple is its tendency to spoil 123

123

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 10

124

Chapter 10

rapidly (as a result of the fat content) following preparation. As constraints to labour increase in Africa, this constraint is likely to increase in importance, giving rise to the need for alternatives.

10.2 Millet Production Levels and Trends in Africa Table 10.1 shows the importance of millet production in selected countries of subSaharan Africa. Five countries in West Africa (Nigeria, Niger, Mali, Burkina Faso and Senegal) produce 85% of the continent’s total millet crop. Sudan accounts for 50% of millet production in eastern and southern Africa. Figure 10.1 shows the relative importance of millet production in West Africa compared with the other two regions. West Africa is also the only region where millet production has significantly increased over time. However, all of this growth is due to increased area cultivated, and not increased

Table 10.1. Africa.

Importance of millet production in selected countries of sub-Saharan

Country Burkina Faso Chad Mali Niger Nigeria Senegal Sudan Africa

Millet production (1000 t)

Millet production (% of total cereals)

734 228 815 1,769, 4,952, 667 385 11,740,

32 31 38 91 26 75 13 10

Source: House et al. (1997) and FAO/ICRISAT (1996).

Fig. 10.1.

Millet production trends in Africa, 1975–1998. Source: FAO (1999).

124

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 10

125

Pearl Millet

yields. Growth rate of millet yields in sub-Saharan Africa during 1985 to 1994 was −2.3%. Nevertheless, graphs are of little use in capturing the importance of millet in the overall food security of Africa. Statistics are reported for countries, and not ecologies. Along with sorghum, millet is the most important crop of semi-arid zones of Africa, and, of the two, millet is the better adapted to marginal conditions. Millet is able to grow and produce reasonable yields on 300 mm of rainfall per season, while sorghum requires 400 mm and the lower limit for maize is 500–600 mm (ICRISAT, 1996). As such, like sorghum, until higher-yielding grain crops such as maize or rice can be made highly drought-tolerant, millet has a guaranteed place in the farming systems and diets of a large and widely dispersed range of semi-arid regions in Africa.

10.3 Millet Production Constraints Even by African standards, millet is a very low yielding crop under most small-scale farming practices. A detailed survey of farming systems of the Sudan savannah ecology of West Africa carried out by IITA showed that farmers generally harvest less than 500 kg ha−1 of millet grain from cowpea/millet intercrops or cowpea/millet/sorghum intercrops (Singh and Mohammed, 1998). While millet may be ideally suited to cultivation in dry areas, it is far from immune to production constraints. Millet’s principal defect is its tendency toward low harvest indices. While farmers make use of stover as well as grain, their selection efforts have had to contend with tight linkages between panicle size and maturity and reverse-phase linkages between tillering and seed and panicle size (Rai et al., 1997). As a result, landraces of millet have harvest indices as low as 14%, compared with 40% in hybrid millets (Kassam and Kowal, 1975). Incidence of major diseases on landraces appears to be higher than on improved varieties (Rai et al., 1997). Surveys of farmers’ fields conducted to obtain estimates of losses from different categories of pests in Senegal, Chad, Mali and the Gambia by Dively and Coop (1993) produced the data summarized in Table 10.2. The data from West Africa produce a rough ranking of panicle pests of: (1) birds, (2) head miners and smut, (3) downy mildew and grasshoppers. In all, millet is reported to suffer attack from some 111 different pathogens, of which four – downy mildew (Sclerospora graminicola), smut (Tolyposporium penicillariae), ergot (Claviceps fusiformis) and rust (Puccinia substriata) – are of major importance in Asia and Africa (Singh et al., 1993). Of these, downy mildew is by far the most widespread and damaging. Screening methods, selection techniques, source germplasm and inheritance patterns have been developed for all four of these diseases and have been summarized by Hash et al. (1997). Smut resistance is readily available and inheritance of the trait is additive, making it a relatively simple disease to breed for (Hash et al., 1997). Ergot resistance is controlled by multiple recessive genes, and therefore has proved quite difficult to transfer into new varieties. Downy mildew is able to evolve new virulent pathotypes rapidly in response to control measures, including host plant resistance. Thus, although many sources of resistance have been identified, all of these tend to vary in terms of their stability across sites and years. Moreover, although gene action responsible for resistance to downy

125

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 10

126

Chapter 10

Table 10.2. Quantifying and ranking of millet pests and diseases in four West African countries (after Dively and Coop, 1993). Yield

Loss

%

Rank 1–4

Senegal

800

200

25

Mali

556

264

47

1083

131

21

172

97

56

1. Head miners 2. Downy mildew 3. Birds 4. Smut 1. Grasshoppers 2. Meloid beetles 3. Pachnoda beetles 4. Birds 1. Downy mildew 2. Birds 3. Head miners 4. Smut 1. Head miners 2. Grasshoppers 3. Birds 4. Smut

The Gambia

Chad

mildew is dominant, a number of genes are involved and inheritance is primarily non-additive in nature, making transfer more difficult (Talukdar et al., 1994). Millet panicles can be heavily damaged by millet head miners (Heliocheilus albipunctella) (Henzell et al., 1997), a group of insects comprising a complex of approximately a dozen damaging caterpillar species. Yield losses from head miner have been described as 13–85% in Senegal, 50% in Mali, and 6% in Niger (Toure and Yehouenou, 1995). They reported no resistance or tolerance had been observed to date for this pest. Progress in breeding for resistance to head miner was until recently reduced by difficulties associated with development of a satisfactory screening method. Screening methods have now been developed which can be broadly applied. Millet does not normally suffer important losses due to foliar- and stem-feeding insects in West Africa. The major insect pest of pearl millet in southern Africa is the armoured bush cricket (Acanthoplus spp.) (Minja, 2000). In large areas of southern Africa, stored millet is damaged by the rice weevil, Sitophilus oryzea; however, significant differences have been noted among genotypes tested for resistance (Leuschner et al., 2000). Millet suffers important losses to the postharvest insects Tribolium castaneum and Cryptolestes ferrugineus in humid zones of the Sahel (Lale and Yusuf, 2000). The most important biotic constraint to millet in many parts of West Africa is the parastic weed, Striga hermonthica. In some seasons, infestation of fields is devastating, with each host supporting the growth of 50–100 Striga plants. To date, no resistance has been documented in millet, although little research has focused on screening for this trait. Bird damage has probably been associated with open-panicle crop species in Africa since the time of their domestication. Scaring birds from fields has, therefore, been a traditional chore of children during the time of grain maturity, for just as long. As

126

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 10

127

Pearl Millet

education has been extended to rural areas of Africa, labour to scare birds has become scarce, increasing the need for bird-resistant varieties. In the marginal environs in which millet is usually cultivated, water and nutrient stress is a constant limitation to growth and productivity. Research on improving drought and low nutrient tolerance in millet is covered in a separate study. Specific mention is made here only of the priority placed on tolerance to low phosphorus soils, which has been recommended for selection through marker-assisted selection techniques (C.T. Hash, personal communication).

10.4 Millet Improvement Through Biotechnology and Breeding Millet breeding advances in Africa Millet is a cross-pollinated crop bred using techniques similar to maize, namely, by hybridizing parents with complementary traits and extracting varieties or lines from segregating generations. Various methods of recurrent selection are used to improve populations. The impact of work focusing on traits found within local varieties presents an interesting case in millet. Selections from a local landrace originating in Togo, ‘Iniadi’, have become the most widespread millet breeding material in the world (Andrews and Anand Kumar, 1996). Iniadi’s success as a breeding material appears to be related to its high general combining ability, earliness, high yield and grain quality. Fully 50% of ICRISAT’s varieties and breeding lines contain Iniadi germplasm in their pedigrees, and half of all commercial hybrids are produced using male sterile lines from Iniadi. Iniadi materials also went into the development of ‘Okashana1’. ‘Okashani1’ is grown on almost 50% of farms in Namibia (Rohrbach et al., 1999). Whereas improved millet varieties have been widely accepted by farmers in southern Africa, adoption rates in West Africa, similar to the case of sorghum, have remained low. Virtually all millet production in Niger is based on cultivation of local landraces, despite several concerted attempts at distributing seed of improved varieties through national seed campaigns during the 1980s. One possibility – that breeders have not fully understood what it is farmers desire in their millet varieties – could potentially benefit from the participatory breeding methods described earlier in this book, beginning with a more full appreciation of the interactions between agro-ecologically based traits and requirements within the user system. High levels of heterosis have been demonstrated in millet. Hybrid millets have been popular in the USA and India since the late 1960s, although hybrid use in India is confined to areas of relatively high potential. Hybrids in India have 15–20% higher yields than improved OPVs (Rai et al., 1997); however, widespread use of single-cross hybrid millet varieties in India has led to high levels of infection from downy mildew. Hybrids have also proved to be more susceptible to smut, ergot and rust. In view of low millet yields in Africa, researchers have proposed top-cross and varietal-cross hybrids, which would include sufficient variation to avoid risk of epidemics. The development of top-cross hybrids has been limited by lack of male sterile lines within landraces, however limited tests of top-cross hybrids have shown much promise (John Whitcombe, personal communication). Yields of hybrid millet varieties

127

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 10

128

Chapter 10

in Africa have shown 40–50% yield increase over landraces (ICRISAT, 1992). Interpopulation hybrids using local landraces have also shown significantly increased yields over improved OPVs (Lambert, 1983). Nevertheless, to date there is no hybrid millet available for farmers in sub-Saharan Africa, a deficiency that merits concerted attention. Male-sterile pearl millet populations with dwarfing traits have been developed for use as seed parents in the development of hybrid millet for Nigeria (Rai et al., 2000), but no hybrid varieties have as yet been released. Methods of millet breeding are divided between recurrent selection (within populations formed with the incorporation of various desirable traits in mind) and pedigree selection techniques aimed at developing fixed lines for use in hybrid formation. Increasingly, combinations of fixed lines are being used to form synthetic varieties. Rai et al. (1997) recommended the use of composite varieties (mixtures of genotypes maintained in bulk), as they can be used in or derived from hybrid breeding methods.

Advances in millet biotechnology Tissue culture has been used to generate somaclonal variants of potential use in breeding programmes (Vasil and Vasil, 1980; Prasad et al., 1984). Methods have also been established for the development in vitro of multiple shoots from shoot apical meristems (Devi et al., 2000). Bui-Dang-Ha and Pernes (1982) and, more recently, Shigemune and Yoshida (2000) have reported regenerating fertile plants from anthers and microspores. However, use of these techniques is not yet widespread, and transgenic pearl millet varieties are not at present in use in any breeding programme. In Africa, South Africa’s Council for Scientific and Industrial Research (CSIR-Biotek) is carrying out research aimed at genetic transformation of millet. An RFLP map has been generated for pearl millet (Liu et al., 1994; Devos et al., 1995). The map has been employed to identify 16 putative markers for race-specific resistance to downy mildew (Hash et al., 1997), and appears poised for use in a variety of other aims, should markers be identified. Markers linked to quantitative trait loci have been identified for high harvest index, grain filling, and yield under terminal drought stress (Yadav et al., 1999). Among the candidate traits for selection through markers are head miner resistance, Striga resistance, drought tolerance and tolerance to low phosphorus soils (Hash, personal communication). Molecular marker techniques are also being applied to the task of characterizing pathogens of pearl millet (Sastray et al., 1995).

10.5 Principal Challenges for Millet Improvement in Africa As a relatively under-researched crop, little information is available on the millet varietal preferences of farmers and the factors involved in the adoption of new varieties. Recent results from farmer participatory breeding work carried out by ICRISAT in Mali suggest a preference for large seeds, bold grain and earlier maturing varieties (Rai et al., 1997). Grain quality issues, which have proved so important in the acceptance of sorghum cultivars, may also be of importance in adoption of improved millets. Farmers also distinguish between varieties which tolerate heat stress (especially at seedling stage), and

128

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 10

129

Pearl Millet

those which do not. Exchange of varieties among farmers is known to occur, but is also poorly understood. Additional information is needed on farmer varietal preferences and how these relate to adaptation within different millet agro-ecologies. The status of understanding of agro-ecologies for both sorghum and millet is at a rudimentary stage, and requires additional research. Finally, as a preferred food crop among large populations, and one with distinct adaptation advantages in large areas of Africa, there are prospects for increasing yields based on demand-driven strategies. One plausible strategy is the development of hybrid millet varieties, targeted at countries where economies are relatively strong and millet is an important crop, such as Senegal, Mali and northern Nigeria.

10.6 Millet Seed Systems Millet seed systems are essentially the same as for sorghum, discussed in Chapter 9.

10.7 Review of Priority Areas of Research and Development Among the traits which have been shown to reduce millet production and productivity, a number can be identified for priority attention for programmes focused on millet improvement. Although, as in the case of sorghum, a West Africa focus appears logical for millet improvement in Africa, most of the traits listed below are of importance in eastern and southern Africa, as well. 1. Resistance to head miners. Head miner damage is a major problem throughout Africa and one for which no resistance has been deployed to date. Several reports indicate the problem may have worsened over recent years. A gap appears to exist between the level of understanding among laboratory-based scientists and breeders, whose narrowing could result in rapid progress toward extending solutions to farmers. Moreover, as head miners preferentially attack early-maturing millet varieties, susceptibility to this pest has reduced the application of earliness traits in new varieties. As a classic, difficult-toscreen-for trait, marker-assisted selection techniques could probably benefit this area of research. 2. Striga resistance. This is viewed as a long-term undertaking, but one which could pay major benefits to farmers of West Africa, where Striga incidence on millet is a devastating problem. Very likely, development of the trait will require a biotechnology approach, as resistance has not as yet been documented in cultivated or wild-relative germplasm. Transformation of millet using genes cloned from species with resistance (cowpea, rice) may eventually prove a valid approach. 3. Bird resistance. Quelea birds can ravage unprotected crops of millet. Bird-scaring as a means of protection is becoming more difficult to provide as increasing numbers of children go to school. Bristled panicles have been shown to offer good levels of resistance, and the trait can be manipulated through conventional breeding tactics. Some groups of farmers have indicated they would accept bristled pannicles, provided they offered adequate protection from this devastating problem. Exploratory research into the effectiveness of the trait and its acceptance among farmers may prove useful.

129

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 10

130

Chapter 10

4. Resistance to low-phosphorus soils. One of the critical weaknesses of improved pearl millet varieties in on-farm evaluations in West Africa over the past 15 years has been their lack of adaptation to the low levels of available phosphorus in soils outside the well-managed research stations where they were bred. Marker-assisted back-crossing would provide the most efficient method for transferring improved ability to take up soil phosphorus from one or more landraces to more agronomically elite, disease-resistant, improved cultivars having acceptable grain quality and high grain yield potential. However, before this can be done, the major loci contributing to improved phosphorus uptake ability will have to be mapped, and tightly linked flanking markers for them identified. Strategies for developing improved phosphorus use efficiency in sorghum should be linked to similar efforts in millet. 5. Study of farmer varietal preferences. As described above, there has been very little research aimed at elucidating genuine, small-scale farmers’ varietal preferences for pearl millet in West Africa. All of the above traits will need to be combined into varieties which satisfy farmers’ and consumers’ needs in terms of grain quality, plant type, and maturity, etc. This can only be obtained through extensive interviews with local producers and consumers. Therefore, a series of surveys, to be conducted within each major agro-ecosystem of West Africa, is recommended. 6. Development of non-traditional hybrids. Given high levels of heterosis in stress environments exhibited in millet hybrids of varying types, and millet’s popularity in areas of West Africa, applied research targeted toward the testing of top-cross and varietal-cross hybrids needs to be explored. Sustained, commercial seed supply for this open-pollinated crop is – as in the case of maize – likely to follow on the development of some form of hybrid. To date, very little research has been applied to hybrid millet for Africa. 7. Resistance to downy mildew. High levels of loss to downy mildew are generally associated with the use of single-cross hybrids, however, extensive observations have also been made of incidence in landraces grown in West Africa. Durable resistance has proved a difficult trait to select for, and thus, could benefit from added support via MAS.

130

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 10

11

Rice

11.1 Brief History of Rice Cultivation and Utilization in Africa Africa is the centre of origin of one cultivated species of rice, Oryza glaberrima, which was domesticated in the northern Niger valley by Africa’s first farmers. Oryza sativa was introduced by European explorers beginning in the 16th century and from Indonesia, via Madagascar. It has become the dominant species, although pockets of glaberrima production continue to exist in various parts of West Africa. Rice ranks as Africa’s fourth most important grain crop, behind maize, sorghum and millet, and is the primary source of carbohydrates of farmers in parts of Liberia, Sierra Leone, Guinea, Nigeria and Mali. For many farmers in East and southern Africa rice is an important secondary crop relied on as both a source of income, as a niche crop in low-lying areas of small farms, and for consumption on special occasions. Because of its wide popularity as a food item, rice is among the most liquid of all crop assets in Africa. Rice consumption in Africa has a high income elasticity, and increases in its projected demand in Africa are tightly linked to increased urbanization and economic growth, in part due to its ease of preparation among smaller, labourlimited households. These patterns are most evident in West Africa, where several pockets of rapid economic growth have fuelled growth in demand for rice. Demand for rice has increased at an annual rate of 5.6% since 1962 (WARDA, 1997). In spite of its status as a cash crop, rice is still very important as a source of income or food for very poor farmers of West Africa, especially in the inland valley swamp ecologies of the savannah zones. In high rainfall areas of West Africa, rice and cassava are relied on as the best extractor of phosphorus on highly leached soils (Sahrawat et al., 1999). Among traditional rice farmers of West Africa and Madagascar, rice is consumed in a wide variety of forms, including porridge and as cakes. Among most consumers, however, rice is eaten in the conventional way, boiled or parboiled, and served with a relish containing fish or other animal protein. Highest per capita rice consumption in Africa is in Guinea Bissau (112 kg per person year−1), followed by Sierra Leone 131

131

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 11

132

Chapter 11

(88.6 kg per person year−1), Guinea (73 kg per person year−1), and Gabon (72 kg per person year−1).

11.2 Rice Production Trends in Africa The annual rice production in selected countries in sub-Saharan Africa is shown in Table 11.1. Figure 11.1 reveals the predominance of West Africa in total African rice production. Production levels in southern Africa are highly influenced by Madagascar. Likewise, those for East Africa are primarily accounted for by Tanzania, which contributes 80% of rice production in the region.

Table 11.1. Annual rice production in selected countries of sub-Saharan Africa. Country

tonnes

Côte d’Ivoire Guinea Mali Nigeria Sierra Leone Congo, Democratic Republic Madagascar Mozambique Tanzania

1,222,650 763,955 589,048 3,275,000 411,300 365,000 2,447,000 191,000 810,800

Source: FAO Internet database.

Fig. 11.1.

Rice production trends in Africa, 1975–1999. Source: FAO (1999).

132

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 11

133

Rice

11.3 Rice Production Constraints Management practices, especially water management, are of primary importance in production limitations in Africa. ‘Total control’ type of irrigation systems account for only 12% of the total rice area in Africa, and water availability can be assumed to limit rice growth at one or several stages of development in all other production systems (see Plate 16). Nitrogen and phosphorus limit rice production on a wide range of soils in West Africa and Madagascar. Biotic factors are also of high importance in rice productivity in Africa. The particular mix of biological pressures which affects crop production is often grouped by production ecology. WARDA has described the range of priority constraints by production ecology (WARDA, 1997), and the information is reproduced in Table 11.2. Selected constraints cited in Table 11.2 are considered below. Drought Rice production is affected by drought stress in a variety of water-limited environments of Africa. Upland rice, normally grown in high rainfall areas, may still suffer from moisture stress at various periods during the season. Recent releases of early-maturing rice offer the chance for farmers to avoid the effects of drought through earlier flowering

Table 11.2.

Priority rice constraints by rice production ecology (WARDA, 1997).

Rice ecology

Share of regional Yields (t ha−1) rice area (%) Current Potential Priority constraints

Humid/ sub-humid zone

40

1

2.5–4.5

Rainfed lowland

38

1.4

3.0–5.5

Irrigated

5

2.8

5.0–7.0

Sahel irrigated

7

3.5

5.0–8.5

Mangrove swamp

4

2

2.5–6.0

Deep water/ floating

6

1.2

1.5–3.0

Weeds, acidity, blast, drought, nitrogen deficiency Weeds, water control, rice yellow mottle virus (RYMV), nitrogen deficiency, drought Nitrogen deficiency, weeds, RYMV, iron toxicity, nematodes, gall midge Nitrogen deficiency, cold, salinity, weeds, RYMV, alkalinity Sulphate acidity, salinity, crabs Water control, low yielding varieties, low fertilizer use efficiency

133

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 11

134

Chapter 11

and more determinant growth habits of rice varieties. Additional progress may be possible through selecting for more extensive root systems. Weeds Weeds are a major problem in upland rice cultivation, where numerous grass species of similar structure and adaptation as rice compete with the crop for light, water and nutrients. Because rice is a relatively small plant (as compared with maize, sorghum and millet) and slow to establish a full canopy, it suffers greater damage from competition from medium-sized weeds (see Plate 17). Insects African rice gall midge (Orseolia oryzae) is predominantly a problem in irrigated and lowland rice systems. Resistance to gall midge has been detected both in O. glaberrima and in interspecific varieties. A moist environment is necessary for egg survival. Stem borer is a lesser problem, also most serious in irrigated areas. Resistance to stem borers is low in the rice genome, making rice a potential candidate for transformation using Bt. Rice yellow mottle virus RYMV is endemic to Africa, and primarily affects lowland rice ecologies. Although its incidence is irregular, the effects of the disease can be devastating when it occurs. Ghesquiere et al. (1997) developed varietal resistance to RYMV in doubled haploid populations developed from crosses of upland japonica and lowland indica rice varieties. Pinto et al. (1999) transformed African rice with RYMV transgenes. Resistance to RYMV has been detected in both O. glaberrima and O. sativa varieties, and has recently been successfully mapped to chromosome 4 (Ndjioniop et al., 1999). Blast (Magnaporthe grisea) Blast fungus is the most serious fungal disease of rice in Africa. It occurs throughout the continent wherever large areas are cultivated to rice. Blast resistance has been noted in recently developed interspecific rice varieties. Genetic studies of resistance have been complicated by variability of the pathogen and lack of rice genotypes with single resistance genes. One study has identified sites of major gene resistance at four different loci (Mackill and Bonman, 1992). Iron toxicity This constraint occurs in the very high-rainfall zones of West Africa where excessive leaching of other cations has left toxic concentrations of iron and aluminum in the soil. It is most pronounced in lowland soils, but can occur in upland environments, as well. WARDA invested heavily in breeding for iron toxicity tolerance in Liberia during the 1980s, leading to development of ‘Suakoko 8’, an iron-tolerant, intermediate variety which has been adopted by some farmers in the region.

134

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 11

135

Rice

11.4 Rice Improvement Through Biotechnology and Breeding Rice breeding advances in Africa The French research organization, Institut de Recherche de l’Agronomie Tropicale (IRAT) performed much of the early breeding on rice for West African conditions. Several of the more popular varieties developed by this programme during the 1950s and 1960s are still cultivated by small-scale farmers. Until the early 1990s IITA also maintained a programme on rice improvement in Nigeria, which eventually was transferred to Côte d’Ivoire and merged with the West Africa Rice Development Association (WARDA), founded in 1971. WARDA divides its rice improvement programme into three sections: upland, lowland, and irrigated, with the two former programmes based in Bouake, Côte d’Ivoire, and the latter based in St Louis, Senegal. At present, only the national programmes in Nigeria, Sierra Leone, Senegal, Burkina Faso and Togo are involved in rice breeding. All others rely on evaluation of lines developed by WARDA or other national programmes. All 17 WARDA member countries are linked via a rice breeding task force which meets periodically to discuss results of trials, set priorities, and obtain new materials. The WARDA programme has made significant advances during recent years through a breakthrough in breeding interspecific varieties selected from fertile progeny of crosses between O. glaberrima and O. sativa lines (Jones et al., 1999). Previous attempts at crossing the two species had proved fruitless, owing to high levels of sterility in the progeny. One component of the breakthrough came through the use of anther culture, which overcomes sterility by fixing lines in homozygous state directly from first (BC1, F1) and second (BC2, F1) backcross generations. Interspecific lines have successfully combined some of the most favourable aspects of each species. Traits contributed by O. glaberrima include increased weed competition through greater leafiness in lower parts of the plant, resistance to RYMV, African rice gall midge and blast, drought tolerance and tolerance of iron toxicity. Traits contributed by O. sativa include better response to increased fertility, higher yield through branched tillers, and resistance to shattering (WARDA, 1999). Using participatory methods of rice varietal selection, interspecific varieties have become popular in several countries, including the major rice producers Côte d’Ivoire, Guinea and Nigeria.

Advances in rice biotechnology Due to its high importance as a food crop and its small genome size, rice has become a model plant for genetic mapping and genome analysis. The rice genome project is an international effort led by Japan aimed at complete sequencing of the rice genome. Various countries and laboratories have agreed to take responsibility for sequencing portions of the genome. Biotechnology applications for rice improvement were given a major boost at both international and national levels through implementation of a 15-year, $100 million ‘International Program on Rice Biotechnology’, sponsored by The Rockefeller Foundation during the period 1985 to 2000. As a result, numerous new varieties with new traits such as increased synthesis of vitamin A precursor, increased resistance to

135

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 11

136

Chapter 11

bacterial blight, blast, nematodes, gall midge and tungro virus are at various stages of testing and release throughout Asia. Prospects for applications of biotechnology in rice were reviewed by Khush and Toenniessen (1991). The status of rice biotechnology has more recently been reviewed by Tyagi et al. (1999). Rice has been reliably transformed via four methods: direct transfer of DNA into protoplasts, electroporation of intact cells, DNA delivery via particle gun bombardment, and Agrobacterium-mediated transformation. The first genotype-independent system for rice transformation was developed by Christou et al. (1991) using the particle gun. More recently, drawbacks related to transgene integration patterns have led to greater use of Agrobacterium-mediated methods. Lectin genes from snow-drop plants for insect resistance via lectin genes (Fujimoto et al., 1993), increased synthesis of vitamin A precursor (Ye et al., 2000), rice tungro virus resistance (Fauquet et al., 1997) and rice stripe virus resistance (Hayakawa et al., 1992) have all been transferred into rice via genetic transformation. Transgenic rice with resistance to rice yellow mottle virus has been developed via gene silencing, but has so far not been field tested in Africa (Pinto et al., 1999). Molecular genetics applications are perhaps more advanced in rice than for any other food crop. RFLP and PCR-based markers are now available for a wide range of important genes, including resistance to fungal diseases and viruses. In Asia, a large number of public research facilities now have the capacity to select for these traits using molecular techniques, creating broad scope for rice improvement in the region far into the future. Moreover, new efforts are now being directed at detection of QTLs for tolerance to moisture stress (John O’Toole, personal communication). Saturated rice genetic linkage maps (McCouch et al., 1997; Cho et al., 1998) have permitted identification of QTLs for many useful agronomic traits. Marker-assisted breeding can now be applied to enhance the efficiency of conventional breeding methods. RFLP markers were used to reduce the number of back-cross generations required to incorporate three genes controlling blast resistance in rice (Hittalmani et al., 1999). In an attempt at improving efficiency of selection for drought tolerance in upland rice, Sarail et al. (1999) identified two QTLs associated with root thickness and root penetration.

11.5 Principal Challenges for Rice Improvement in Africa The low level of breeding capacity in national programmes of sub-Saharan Africa represents a major structural challenge to the improvement of rice in the region. Although WARDA and the breeding task force now operating in West Africa can facilitate access to improved lines, the likelihood of adaptation of these genotypes to local environments is inevitably left somewhat to chance. Moreover, integration of molecular techniques in a manner similar to that achieved in recent years in Asia is impossible unless there is widespread capacity in conventional breeding. Therefore, there appears to be ample justification for a broad-based initiative aimed at increasing breeding capacity. Once established, this more decentralized breeding strategy will be able to take ample advantage of the advances made by WARDA through its interspecific breeding programme, including utilization of the technique for lowland and irrigated

136

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 11

137

Rice

environments. Once again, trait-based strategies which aim at reducing losses due to pests and diseases would appear to be a relevant, general thrust. Prioritization of these traits at a national and sub-national level is a priority for future years. Identification of such priorities will require the mobilization of breeding teams to interact extensively with farmers regarding the incidence of biological and environmental constraints and rice varietal preferences among local farmers. The existence of task forces which give priority to vigorous, continual participation of a large number of national programmes represents a major resource in the future implementation of regional strategies constructed along these lines. In the interim, rice improvement strategies can be focused on rapid deployment of new traits and fixed lines made possible by breeding performed by WARDA. This aim can be advanced by systematic distribution of segregating breeding families and lines and the provision of support to national programmes for effective, multilocation testing of these materials. Drought is the most frequently cited source of yield loss among rice farmers throughout the world. Likewise, in Africa, both lowland and upland (but most severely, upland) rice production is regularly constrained by the incidence of periodic droughts in the region (WARDA, 1997) (see Plate 18). Strategies for improving drought tolerance in rice have recently been reviewed by Ito et al. (1999). Molecular tools for detecting QTLs have been developed at Texas Tech University, Cornell University and at IRRI (Nguyen et al., 1996) and now make possible the selection for drought tolerance based on specific traits. Additionally, several landraces of rice grown in the northern Sahel regions of West Africa have been observed by the author to display tolerance to drought. Prospecting for genes in these landraces using molecular genetics may be considered a secondary component of strategies on drought tolerance for rice in Africa.

11.6 Rice Seed Systems The development of sustainable rice seed systems is challenged by two factors inherent to the crop itself, namely, its self-pollinating habit and high requirement for seed per unit of cultivated area. The result of these two factors is a low level of interest among private seed dealers in stocking rice seed (because of few repeat sales among farmers who save seed from season to season) and the high cost (mainly transport costs) of rapid substitution of old varieties for new. For this reason, the broad-based improvement of rice seed systems is more amenable to methods that rely on gradual diffusion of small quantities through highly decentralized seed networks. A logical alternative to this method is that of the seed distribution campaigns which rely on the public and NGO sectors. This, in turn, is dependent on well-informed testing and evaluation methods typified by the ‘Participatory Variety Selection’ (PVS) methods discussed in Chapter 4. Collective learning from PVS methods in Guinea recently led to major investments by the government in large-scale multiplication and dissemination of improved, interspecific rice varieties (Spencer and Edwin, 1999). Follow-on strategies of this type may be relevant in other rice-growing countries where interspecific and other improved rice varieties have been widely tested, including Côte d’Ivoire, Nigeria and Burkina Faso.

137

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 11

138

Chapter 11

11.7 Review of Priority Areas of Research and Development 1. Drought tolerance. Upland rice systems in Africa are subject to frequent periods of drought stress, especially during vegetative phases of growth. To date, little research has been aimed at improving the productivity of rice farmers faced with this constraint. Nevertheless, recent reports of interspecific varieties with higher drought tolerance may indicate potential for broad improvement for this trait. Researchers who have studied the effects of moisture stress on rice have increasingly focused on insufficient root penetration of the soil profile as a cause of the crop’s susceptibility to drought. Longer roots which reach deeper into the soil profile are able to maintain growth further into a drying period and may result in higher yields at the end of the season. Assaying for rooting is a difficult and time-consuming task that may be assisted by the identification of molecular markers for this trait which can be used to select quickly for longer roots. 2. Increase national breeding capacity. Only five of the 12 West African countries with major rice-growing areas actively breed new rice varieties. Extended breeding capacity should be employed in breeding rice for a wider range of agro-ecologies, based on combining resistance and tolerance traits for the major constraints in each area. A well-developed network of national programmes is available to test and disseminate improved varieties which come from such efforts. 3. Increased understanding of rice agro-ecologies. As previously discussed, breeding teams can increase the efficiency of their targeting of new varieties and selection of parents for new crosses through a better understanding of the character and boundaries of rice agro-ecologies in Africa. At present, this type of study is confined to inner-valley continuum ecologies, and generally does not involve breeding teams. Broadening the focus of agro-ecological study to other areas and including breeders and other plant scientists may make it more applicable to varietal development. 4. Rapid deployment of fixed and segregating lines with resistance to major pests and diseases. This can be facilitated by continued fixing of new lines by the WARDA interspecific breeding programme, and can be carried out in close conjunction with the PVS method of selection and multiplication. Participatory variety selection needs to be intensified to reach larger numbers of testing sites. 5. Increased capacity in molecular breeding at WARDA and selected national programmes. Molecular reference maps for African rice are still being developed (Marie-Noelle Ndjiondiop, personal communication), following which localization of the newly-developed marker for RYMV and other important traits can be performed. The point at which integrating molecular breeding with conventional selection methods becomes appropriate in NARS breeding programmes will depend on progress made in identifying useful markers, analysis of the cost-effectiveness of the methods, and the pace of capacity building at national level.

138

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 11

II

1

Exploring New Strategies for Improving Africa’s Food Crops1

The following seven chapters are not intended as presentations of all the challenges facing crop improvement specialists who work with these seven crops. Indeed, the same agro-ecological diversity which this document has attempted to emphasize ensures that no single summary can adequately capture all the issues which are of importance to breeders and farmers throughout Africa. Rather, the chapters attempt to characterize the major challenges ahead in attempting broadly to improve the performance of these crops when grown under marginal, low-input conditions common to small-scale farmers in much of Africa. Therefore, rather than serving as detailed guides for priority setting among breeders, it is hoped that this part will serve as a stimulus for further discussion and, eventually, increased support and efforts aimed at addressing the identified challenges.

97

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter II

12

Cowpea

12.1 Brief History of Cowpea Cultivation and Utilization in Africa Cowpea is a tropical legume crop of African origin. Most recent speculation on the crop’s centre of origin focuses on a band of diversity of wild cowpea stretching across southern Africa from Namibia to Mozambique, with a centre of speciation in the Transvaal region of South Africa (Padulosi and Ng, 1997). Nevertheless, the centre of greatest diversity of cultivated cowpea is in the northern Guinea savannah regions of West Africa (Ng, 1995). In many fields, almost continuous variation exists between the more elite, large-seeded varieties of cultivated cowpea, the small-seeded, more weedy varieties, and true wild species of cowpea (Rawal, 1975). Cultivated cowpea has been shown to cross regularly with wild cowpea growing on the periphery of fields in East Africa (Remy Pasquet, personal communication). Cowpea plant remains dating to 1500 BC have been discovered in a cave dwelling in Ghana (Flight, 1976). Cowpea is an extremely resilient crop, and is cultivated under some of the most extreme agricultural conditions in the world (see Plate 19). Cowpea varieties grown in the Sahel and on the fringes of the Sahara are drought and heat tolerant. Other cultivars are tolerant to acid soils, extremely poor soil fertility, and shading from other crops (Singh, 1998). Cowpea’s highly diverse plant architecture has allowed farmers to develop varieties which fill a wide range of unique niches: highly determinate cowpea varieties are grown for grain in monoculture situations, while spreading types are grown as a dual-purpose (grain/fodder) crop interplanted with cereals, and as a relay crop using residual moisture. Cowpea is cultivated for its leaves, green pods, grain, and stover. While all parts of the plant are used to some degree in each region of the continent, in West Africa cowpea is primarily grown for its grain and stover (cowpea haulms contain 20% protein and are highly sought after as cattle feed), while in eastern and southern Africa it is cultivated primarily for its leaves. Cowpea grain is consumed directly following boiling, as a component of meals which also include porridge made from cereals or root crops. Cowpea grain cakes (made from mashed and fried seed) are also sold as a fast food along 139

139

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 12

140

Chapter 12

roadsides in Nigeria. In eastern and southern Africa, cowpea leaves are commonly added to sauces and served with porridge, or boiled and consumed in a manner similar to spinach.

12.2 Cowpea Production Levels and Trends in Africa Data in Fig. 12.1 should be used only as an indication of the major cowpea producing areas of Africa. Figures on cowpea production are imprecise, and for several important producers (Mozambique, Zimbabwe), no recent data are available. Current estimates place annual world cowpea grain production at 3 million tonnes (Singh et al., 1997). Approximately 64% of this is grown in West and central Africa, which accounts for 80% of total production in Africa. Nigeria, in turn, accounts for upwards of 75% of production in West and central Africa (FAO, 1999). However, it is also an important crop in marginal areas of eastern and southern Africa in Sudan, Somalia, Mozambique and southern Zimbabwe. Most cowpea is grown as an intercrop with cereals, and little of the harvest reaches regional markets. The sole important export market for cowpea is believed to be from Niger to Nigeria, which is the world’s largest consumer of cowpea. Surveys have shown negative income elasticity for cowpea consumption, indicating cowpea is a crop of the poor. Cowpea thrives on poor soils and in semi-arid regions, making it a common intercrop with sorghum and millet-based farming systems of the Sahelian countries. In many areas, cowpea is a crop cultivated by women, and is often used as a weaning food.

Fig. 12.1.

Cowpea production trends in Africa, 1975–1999.

140

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 12

141

Cowpea

12.3 Cowpea Production Constraints Cowpea is attacked by over 35 diseases caused by viruses, bacteria, fungi and nematodes (Singh et al., 1997), some of which cause significant reduction of yield. These are grouped by pathogen, below. Cowpea viral diseases The most damaging viral diseases of cowpea are the seed-borne diseases (Hampton et al., 1997). Their symptoms generally appear most strongly on the leaves, where they cause stunting and deformation. Among these, several are of importance in Africa, including cowpea yellow mosaic virus, cowpea aphid-borne mosaic virus and cowpea severe mosaic virus. The genetics of resistance to cowpea viruses has been extensively studied (Provvidenti, 1993; Scully and Federer, 1993), and numerous sources of resistance to cowpea viruses have been identified. Cowpea bacterial diseases Bacterial blight caused by Xanthomonas campestris and bacterial pustule (Xanthomonas sp.) are the two most important bacterial diseases of cowpea in Africa (Emechebe and Florini, 1997). Bacterial blight is the most devastating disease of cowpea in dry regions of West and central Africa (Wydra and Singh, 1998). Pathogens of both diseases are transmitted via seed, and spread of the diseases is often caused by planting infested seed; however, good sources of resistance have been identified for both diseases (Emechebe and Shoyinka, 1985). Genes for resistance are available for most bacterial diseases, but, their area specificity and frequent, sudden appearance in new areas illustrate the need for decentralized breeding schemes for cowpea improvement. Cowpea fungal diseases Eleven major fungal diseases of cowpea have been identified among which anthracnose (Colletotrichum gloeosporioides), Ascochyta blight (Ascochyta phaseolorum), brown blotch (Colletotrichum capsici) and brown rust (Uromyces sp.) are considered to be of greatest importance in Africa (Emechebe and Florini, 1997). In addition, Septoria leaf spots and scab (Elsinoe phaseoli) are important constraints in more humid regions. Cowpea insect pests Insect pests represent the most serious constraint to cowpea production throughout Africa. In many areas, losses due to insect pests are so high that yields seldom rise above 100–150 kg ha−1 (Kitch et al., 1997). The most important insect pests in cowpea production systems in Africa are probably aphids (Aphis craccivora), pod borers (Maruca vitrata), thrips (Megalurothrips sjostedti) and the pod-sucking bug Clavigralla tomentosicollis. Aphids are most damaging in the Sahel in areas of less than 300 mm rainfall, while maruca is most important in higher rainfall areas (IITA, 1998). Unfortunately, cultivated cowpea genome appears to offer few useful sources of durable resistance to the major insects. Although several wild species are known to be resistant to maruca pod borers and the pod-sucking complex, and wide crosses made to wild relatives V. oblongifolia and V. lutea have produced fertile progeny using embryo rescue,

141

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 12

142

Chapter 12

the results have been mixed (Fatokun et al., 1997). Cowpea bruchids (Callosobruchus maculatus and Bruchidius atrolineatus) cause extensive damage to cowpea grain in storage, but actually infest the green pods while still in the field (Murdock et al., 1997). Much effort has been made to devise and popularize appropriate methods of protecting against damage to cowpea grain in storage, sometimes with positive results (Murdock et al., 1997). Nevertheless, bruchids continue to destroy much of the crop throughout Africa. Striga Striga is an important constraint to cowpea production in much of West Africa. Varieties have been developed which show high levels of resistance to Striga populations of Nigeria, Burkina Faso, Cameroon and Mali, but which are susceptible to populations in Benin. Other varieties are resistant to the Benin populations but susceptible to others. Work is on-going to develop varieties which have broad resistance against all known Striga populations (IITA, 1998).

12.4 Cowpea Improvement Through Biotechnology and Breeding Cowpea breeding advances in Africa The large number of biological constraints encountered in cowpea cultivation in Africa, coupled with wide natural diversity within the cowpea genome, offer many channels for improvement of the crop. However, because cowpea is used primarily as a ‘niche’ crop by small-scale farmers, successful breeding requires extensive knowledge of local farming systems. Kitch et al. (1998) analysed varietal preferences among men and women farmers in Cameroon and identified 26 different criteria used in making selections, of which less than half were related to yield. The need for this type of detailed knowledge argues for decentralized breeding initiatives based on increased analysis of agro-ecological variation and farmer preferences, as the rate of usage of varieties bred internationally and regionally is very low (Ndiaga Cisse, personal communication). Nevertheless, national breeding efforts can be effectively reinforced by efforts among international breeding centres which focus on intractable constraints to production and longer-term population improvement for yield potential. IITA has the worldwide mandate for cowpea breeding, and maintains a breeding centre in Kano, Nigeria. The USAID-funded Bean/Cowpea Collaborative Research Support Programme is also active in breeding cowpea varieties for northern Sahel and savannah ecologies focusing on resistance to important pests and diseases (Ehlers and Hall, 1997). Unfortunately, only a few national programmes (Burkina Faso, Mali, Ghana, Nigeria and Senegal) have employed cowpea breeders who perform their own crosses. In some cases, cowpea breeders have been drawn into administrative positions, and in others, there is a lack of funding channelled to their programmes from either national or international sources to permit planting a fully functional nursery on a regular basis. This deficiency will need to be corrected if crop improvement in cowpea is to have serious impact among small-scale farmers. Cowpea varieties are not, as a rule, broadly adapted and the value of even highly prized plant genetic traits can be masked by

142

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 12

143

Cowpea

lack of adaptation or farmer preferences if those traits are not effectively introgressed into the appropriate background. The IITA programme has developed varieties for use under two major categories: time-to-maturity (early, 60–70 day; medium, 75–90 day; late, 85–120 day) and photoperiod sensitivity (non-sensitive and sensitive). In addition, they have developed speciality varieties with high grain quality, high foliage production and tolerance of environmental stresses (Singh et al., 1997). These varieties vary with respect to the farming systems they are adapted to (intercropping compared with mono-cropping). With increasing time to maturity, plant growth habit also changes from highly determinate, bush types to indeterminate, vine types. A separate effort has been directed at transferring useful traits such as early maturity and resistance to thrips, aphids, viruses and bruchids into popular landraces of West and central Africa (IITA, 1998) Another major focus has been the development of varieties with multiple virus resistance and multiple bacterial disease resistance. At present, a series of varieties has resistance to five major cowpea viruses. Varieties ‘IT96D-660’ and ‘IT96D794’ are resistant to cowpea aphid-borne mosaic virus, blackeye cowpea mosaic virus and cowpea mosaic virus (Hughes and Singh, 1998). Sources of resistance are also available for fungal disease pathogens, including anthracnose, Cercospora phytophtera, brown blotch and leaf smut. Varieties are also available with resistance to root knot nematodes. Extensive efforts have also been made to develop resistance to insects, with encouraging results for some insect pests (Singh et al., 1997) (see Table 12.1). Resistance has now been reported to be available against attack by thrips, bruchids and aphids (Adjadi et al., 1985; Singh, 1993). As has been previously stated, however, adequate resistance to maruca and pod-sucking bugs has not been achieved, despite exhaustive screening of the cultivated cowpea genome. Drought and heat tolerant cowpea varieties, named ‘Mouride’ and ‘Melakh’, have been developed for water-limited environments of the Sahel (Cisse et al., 1995, 1997) through collaborative research between US universities and NARS in Africa (Hall et al., 1997). These extra-early varieties proved highly popular among Senegalese cowpea farmers who commercialized their harvest.

Table 12.1. Sources of resistance to major pests and diseases of cowpea developed by IITA (after Singh et al., 1997)

Striga

Variety IT90K-277-2 IT89KD-374-57 IT90K-261-3 IT89KD-457 TVX 3236 IT90K-76 IT90K-59 IT82D-889 IT83S-818

Five virus diseases

Bacterial diseases

Bruchids Aphids R R

R/MR MR/R R/R

R R R R

143

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 12

MR R R

Thrips R MR MR

144

Chapter 12

Striga and Alectra both attack cowpea throughout Africa. Sources of resistance have been identified and the genetics of resistance has been studied (Aggarwal, 1984; Singh and Emechebe, 1990). Varieties with resistance to Striga have been distributed to numerous African countries. Cowpea could prove to be an important source of resistance to Striga for other crop species, through genetic transformation. Some of the most recently developed, improved cowpea varieties combining resistance to major diseases, insect pests, and Striga gesnerioides have shown over 50% higher yield potential than existing improved varieties, with 1.5 t ha−1 grain and 3 t ha−1 of fodder in Sahelian ecologies and 3 t ha−1 grain and 5 t ha−1 fodder in Sudan savannah ecologies. Screening for drought tolerance and root characteristics revealed that four varieties, ‘IT96D-604’, ‘IT95K-222-3’, IT90K-222-5’ and ‘IT95K-1115-10’ were most drought tolerant (IITA, 1998).

Advances in cowpea biotechnology Biotechnology may hold significant promise for cowpea improvement. Cowpea yields are so highly affected by insect pests that five- to seven-fold increases are experienced with one or two applications of insecticide. Maruca pod borers and the pod-sucking complex of insects are two pests for which no adequate source of genetic resistance has yet been discovered. Cowpea weevil is another for which known resistance sources offer only slight improvements. Several researchers in the USA have worked on transformation systems for cowpea, using both Agrobacterium and the gene gun methods. IITA, as well, has worked on cowpea transformation via electroporation of pollen grains, microparticle bombardment of pollen grains and Agrobacterium transformation of immature flower buds (Thotapilly et al., 1998). Plants were regenerated from tissue which tested positive for reporter genes, but which lost expression in the T2 generation. To date, cowpea transformation has not become a routine procedure. At the time of writing of this book, researchers were planning to convene a meeting on cowpea biotechnology aimed at establishing a global strategy for biotechnology applications in Africa. ‘Bt cowpea’ has been proposed as a means of achieving resistance to cowpea pod borers, as well as via transformation using protease inhibitors, α-amylase inhibitors and lectins (Monti et al., 1997). At the time of publication of this book, researchers from a number of institutes in Africa, the USA and Australia were planning to embark on an ambitious plan to transform African cowpea using gene constructs encoding Bt and α-amylase inhibitor proteins, which are expected to offer protection against maruca pod borers and cowpea bruchids, respectively. A separate initiative was also underway to transfer a gene construct for resistance to cowpea aphid-borne mosaic virus into cowpea using novel transformation methods (Sithole-Niang, 2000). IITA has also made progress on development of an RFLP map of cowpea using a cross between cowpea and a wild relative. At the last report, the cowpea map had 92 markers distributed among 85 loci (Fatokun et al., 1997). Average genomic distance between markers is approximately 10 cM. These markers are distributed into ten linkage groups; however, cowpea has 11 chromosomes. Since probes used for cowpea mapping were the same as those used for mapping mung bean, synteny studies have been possible between cowpea and other legumes. A high degree of conservation was observed, with

144

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 12

145

Cowpea

90% of markers hybridizing in similar positions in the two crops. Useful traits for which putative QTLs have been identified include seed weight, pod number, pod length, plant height, days to flowering, and days to maturity (Fatokun et al., 1997), while current efforts are focused on identifying markers for resistance or tolerance to bruchids and thrips. Timko (2001, unpublished) has since reported identifying 413 RAPD markers on the cowpea genome, distributed among 11 linkage groups.

12.5 Cowpea Seed Systems Very little commercial seed of cowpea is marketed in Africa, although seed companies in Mozambique, Zimbabwe and Ghana do market registered varieties. Most seed is obtained through informal exchange between farmers, with some seed being purchased in local markets (Walker and Tripp, 1997). As a self-pollinated, non-commercial crop, cowpea seed dissemination is suited to public sector-led campaigns which may focus on increasing access among farmers to a single variety or group of selected varieties. Significant impact may be possible through NARS/NGO collaborations which focus on broad testing and dissemination of farmer-selected varieties focusing on the drought-resistant and pest- and disease-resistant varieties indicated in the above section on breeding. Recently, a seed distribution initiative was undertaken in northern Nigeria which appears to show promise for other areas, as well. Thirty-six experienced cowpea growers were given 3 kg of breeder seed to grow simultaneously as foundation seed and as a demonstration plot. They in turn sold seed on to 262 farmers who showed interest in the varieties. This group produced some 12 t of seed for sale to hundreds more farmers (Singh and Olufano, 1998).

12.6 Review of Priority Areas of Research and Development 1. National cowpea breeding programmes. Since cowpea varieties must conform to localized, low-input farming systems in order to be adopted, wide adaptation is not common. All valuable genetic traits identified and rendered manageable through biotechnology or breeding will inevitably have to be introgressed into adapted populations at the national level. With only five NARSs currently active in this work, the prospects for broad improvement of cowpea in Africa are poor. 2. Insect resistance. Insect pests (thrips, bruchids, pod-sucking insects) constitute the greatest constraint to cowpea production in Africa. Little or no usable resistance has as yet been detected in cultivated or wild genomes. Strategies have been advanced to transform African cowpea with gene constructs encoding production of Bt and αamylase inhibitor proteins. Recently, research conducted at IITA showed that orchid and snowdrop lectins were found to be insecticidal to Maruca vitrata and hence may be used to control this pest through transgenic approaches. In addition, affinity-purified lectins from African yam beans (Sphenostylis stenocarpa) were tested against pod-sucking bugs and cowpea weevils using an artificial seed system, and were demonstrated to be lethal to both pests.

145

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 12

146

Chapter 12

3. Transformation and gene expression systems. Rates of success with genetic transformation of cowpea to date (if achieved at all) are far below levels of efficiency needed to plan an improvement strategy. Cowpea transformation is being pursued at IITA, Michigan State University, the University of Arkansas, in China, and India. Researchers at the University of California at San Diego have discovered a promoter which constitutively expresses in legume seeds. This could be useful in the enhancing expression of resistance genes to weevils, thrips and maruca pod borers. 4. Identification of resistance genes. Little usable resistance has been found against maruca pod-boring or pod-sucking insects. Cowpea bruchid resistance has also been extremely difficult to isolate and manage. A systematic procedure has been developed at Purdue University for identification of resistance genes (Larry Murdoch, personal communication). Genes have already been isolated from common beans for α-amylase inhibitor for bruchid resistance. 5. Improved nutritional character. Although cowpea is already a good source of protein and carbohydrate, food quality analysis of some 52 cowpea varieties at IITA recently indicated significant genetic variability for protein, fat, and iron content. The top four improved varieties had 17% higher protein and 12% higher iron content than the mean of four popular local varieties (IITA, 1998). 6. Gene flow studies. Because cowpea is an indigenous crop to Africa, there is a high probability that transgenic resistance genes could flow to wild relatives growing in the borders of fields. As a measure of biosafety, studies need to be undertaken to measure the likelihood and degree of risk involved. 7. Virus resistance. Gene constructs have been developed for resistance to a number of viruses (Mlotshwa, 2000). At present, several of these have been shown to be effective in model systems, using tobacco (Ida Sithole, personal communication). These could prove useful in a cowpea transformation system.

146

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 12

13

Cassava

13.1 Brief History of Cassava Cultivation and Utilization in Africa Although still a subject of some debate, the centre of origin of cassava is generally believed to be the southern border of the Amazon basin (Olsen and Schaal, 1999). Cassava was introduced in Africa in the Congo River delta by the Portuguese in the 15th century (Jones, 1959), and spread rapidly to many agro-ecologies (Hahn et al., 1979). Cassava is today grown in most agro-ecologies of the continent; however, cassava is most important in farming systems of the humid forest regions, where the productivity of grain crops is reduced by low sunlight, foliar pests and diseases, and grain storage is more difficult. Cassava has very high yield potential, making it a viable alternative to grain crops where population pressures have led to tradeoffs between food quality and quantity. Commercial cassava yields as high as 20 t ha−1 have been registered under experimental conditions. However, because of high labour requirements at planting and harvest, cassava production throughout the world continues to be dominated by smallscale, non-mechanized systems. Cassava is well known for being able to grow and produce food even in very poor soils. For that reason, it is often grown at the margins of farms while the better land is reserved for the production of grain crops. In addition, once established, cassava is relatively drought tolerant, and when mature can survive up to 6 months without rains. Cassava’s ability to produce food under marginal conditions has made it a popular crop of Africa’s poor farmers who are unable to invest in fertilizer or pesticides to protect the crop against environmental stresses and biotic constraints. This fact, coupled with asexual propagation of the crop, has created a major role for crop improvement – not only are there few other alternatives to building in the performance traits needed by farmers, but, once finished, there is a very good chance the crop will stably express those traits (see Plate 20). Cassava is widely consumed as a porridge, which is prepared from dried and pounded roots, but is eaten in a very wide range of forms in different parts of the continent. Cassava is reported to be consumed in 28 different forms in Cameroon, alone 147

147

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 13

148

Chapter 13

(Jim Whyte, personal communication). In urban areas of West Africa, widespread development of cassava-processing methods (consisting of pounding, soaking and drying to produce a fermented flake known as ‘gari’) have resulted in cassava becoming an important commercial commodity. Such processing capacity does not exist in east and southern Africa, and cassava has remained a traditional, rural starchy staple in those regions. Cassava is also consumed as a snack food in various parts of the continent. Varieties used as snack food are ‘sweet’ types, low in cyanic acid, which can be boiled and eaten or even consumed raw. Rapidly increasing cassava cultivation in Sahelian countries over the past decade has been primarily based on the use of these types (Tshiunza et al., 1999). Cassava is also widely grown for its leaves, which are used in making sauces. Once again, leaves from varieties with high cyanic acid content must be properly processed to remove the toxic compounds. Cassava flour is also sometimes used in making bread for local consumption. Recently, initiatives in West Africa have aimed at developing the export market potential for production of dried cassava chips used as animal feed in Europe. This market is currently supplied by Asian production. Cassava’s combined abilities to produce high yields under poor conditions and store its harvestable portion underground until needed make it a classic ‘food security crop’. In recent years, this has proved of critical importance to many people in Africa caught up in civil conflicts and unable to cultivate the normal range of annual crops. Displaced groups of people in Mozambique during that country’s 16-year war often survived on abandoned cassava fields. Because it is a vegetatively propagated crop, such plantings can also serve as a ready supply of planting material during rehabilitation following conflict or drought. It is a notable fact that cassava processing and marketing are often controlled by women. Thus, resources from cassava production are often targeted toward the needs of women and children. As implied above, however, cassava’s productive capacity in low-input conditions comes at a certain cost in terms of carbohydrate quality and protein concentration.

13.2 Cassava Production Levels and Trends in Africa While aggregate production statistics on cassava are subject to large degrees of error, the figures in Table 13.1 give a general idea of the trend in cassava production in Africa. According to figures from the FAO (1999), the rate of increase of cassava production has been higher than any other crop in Africa over the past 15 years. Since 1990, this increase has been fuelled by rapid increases in productivity following the release of improved varieties in Nigeria (Nweke et al., 1994), and more recently, in the Sahel (Tshiunza et al., 1999). Rapid increases in cassava production occurred in West Africa (primarily Nigeria) following the release of high-yielding, early-bulking varieties and the establishment of small-scale processing facilities (Fig. 13.1).

13.3 Cassava Production Constraints At the time of cassava’s introduction, few major pests or diseases hindered its production. With time, however, a number of important biological constraints to production have been introduced. Thus, while cassava may tolerate well extensive farm

148

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 13

149

Cassava

Table 13.1. Annual cassava production in major African cassava-producing countries.a Production (t year−1)

Country Benin Côte d’Ivoire Ghana Guinea Nigeria Kenya Madagascar Uganda Angola Congo, Democratic Republic of Mozambique

2,377,339 1,700,000 7,226,900 811,869 32,695,000 910,000 2,404,000 3,400,000 3,210,570 17,100,000 5,639,000

aIn comparing cassava production figures with those of grain crops it should be borne in mind that cassava production figures are reported at 70% moisture content, while most grain crops are reported at approximately 15% moisture content. Source: FAO (1999).

Fig. 13.1.

Cassava production trends in Africa, 1975–1999.

management practices commonly used in its production in Africa, cassava yields are severely affected by pests and diseases (IITA, 1998). Chief among these are the two insect pests, cassava green mite (CGM) (Mononychellus tanajoa) and cassava mealy bug (Phenacoccus manihoti), and two foliar diseases, cassava mosaic disease (also known as African cassava mosaic virus) (ACMV) and cassava bacterial blight (CBB) (Xanthomonas campestris). At present, a heavy incidence of cassava brown streak disease has also been reported in Mozambique (Alfred Dixon, personal communication).

149

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 13

150

Chapter 13

ACMV and its East African variant EACMV are caused by virus strains which can be transmitted both mechanically, through handling of planting stock, and via an insect vector, the white fly (Bemisia tabaci) (Storey and Nichols, 1938). Recently, an especially virulent form of cassava mosaic disease (now being referred to as Ugandan variant, or UgV) spread through Uganda, western Kenya, southern Sudan and northern Tanzania (Legg, 1999). ACMV is endemic in Africa. Cassava bacterial blight was probably introduced to Africa from South America by accident. It has now been reported throughout Africa. Root rots, caused by Botryodiplodia theobromae, Fusarium spp. and Phytophtora sp. have recently been reported to be increasing in Nigeria (Wydra and Singh, 1998). Among the insect pests of cassava in Africa, cassava mealy bug and green mite are considered to be the most important. Both of these were introduced to Africa through importation of vegetative planting material (Hahn et al., 1979). While cassava mealy bug infestations have been successfully controlled by distribution of its natural enemy from South America, the green mite remains a serious constraint to production in parts of Africa, especially during dry periods, although African landraces have been identified which carry resistance (see Plate 21). IITA is also pursuing an extensive campaign on biological control of cassava green mite using an exotic phytoseiid predator, Typhlodromalus aripo.

13.4 Cassava Improvement Through Biotechnology and Breeding Cassava breeding advances in Africa Because of the limited diversity among the introductions made by the Portuguese and because of infrequent sexual reproduction of the plant in most African environments, the African cassava gene pool has remained relatively narrow. This lack of genetic diversity, however, appears to be a constraint within the whole of the cultivated cassava genome. Olsen et al. (1999) discovered that cultivated cassava contained only 25% of the diversity of its wild progenitors, compared with 75% for maize. Cassava is a cross-pollinated crop. However, breeding has historically been limited by the plant’s erratic flowering habit. Breeding of cassava in Africa achieved a major advance with the discovery in 1989 of a site in Ubiaja, Edo State, Nigeria where a broad base of cassava accessions produced flowers and could be used in making crosses (Ekanayake, 1996). The development of this facility has led to a drastic increase in the number and diversity of genetic backgrounds that can be incorporated into new varieties, both from African landraces and from breeding stock from Latin America (via CIAT) and other parts of the world. IITA breeders have now developed many new breeding populations, with their progeny being sent out both as seed and as micropropagated plantlets to many national programmes. Because of long time-to-flower and severe inbreeding depression in cassava, breeders commonly rely on screening very large F1 populations, in the hope of finding genotypes which combine a favourable mix of target traits. More recently, however, inbreeding methods have met with more success, and fifth-generation inbreds have been developed (Alfred Dixon, personal communication).

150

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 13

151

Cassava

Resistance to both ACMV and CBB were discovered in a wild relative of cultivated cassava, Manihot glaziovii, and successfully transferred into cultivated cassava via wide crosses (Nichols, 1947). This led to the development of a donor parent, ‘clone 58308’, which was later recognized as stably resistant to disease and widely used as a source of resistance to both diseases in the cassava breeding programme at IITA. Since then, breakthroughs in breeding have permitted the development of resistant varieties such as ‘TMS 30372’. Indeed, perhaps the most impressive results of cassava improvement, Africa-wide, have occurred in the rate of development of ACMV-resistant varieties, whose number increased from 29 in 1989 to 106 in 1993 and 334 in 1997. Similarly, the number of ACMV-resistant plantlets distributed to collaborating programmes, Africa-wide, has risen from 3007 in 1993 to 16,864 in 1997. Recently, African landraces have been identified which carry high levels of resistance to ACMV (Dixon, 1999). In spite of such advances, cassava breeding remains a highly centralized activity, with nearly all breeding being conducted at a single site, and other cassava improvement programmes being relegated to testing. In view of continued low adoption rates of improved cassava, more decentralized agro-ecology-based breeding activity is viewed as a priority. Cassava breeding methodology is based on crossing devised to combine traits of various parents, followed by clonal selection based on performance for various target traits. A current priority for breeding in East Africa, for example, is combining high levels of resistance to ACMV and CGM in several adapted clones as these two constraints seem to result in especially heavy losses when found in combination (Legg et al., 1998). The IITA methodology begins with crossing performed at Ubiaja, followed by preliminary evaluations for ACMV, CBB and green mite resistance in Ibadan. Breeding at IITA has led to the development of a wider range of disease- and insect-resistant varieties with desirable agronomic (early bulking, high yield, low branching, among others) and culinary traits (easy processing and desired cyanic acid content) with adaptation to most of the cassava-producing agro-ecologies in Africa (Dixon, 1999). This was followed with the massive dissemination of seeds and tissue-cultured plantlets for further selection for adaptation by NARSs. A total of 38,811 in vitro plantlets were distributed to 39 African countries between 1994 and 1997. In addition, almost 2.4 million sexual seeds were distributed to various African countries during the same period (Lynam, 1998). During the 1990s the cassava breeding programme at IITA has also imported large numbers of accessions from Latin America, aimed at broadening the gene pool. Two networks organized around breeding for root crops have been created in East (EARNET) and southern Africa (SARNET). No such network exists at present for West and central Africa.

Advances in cassava biotechnology By far the most commonly employed application of biotechnology in cassava has been micropropagation via in vitro meristem culture. Perfection of these techniques at IITA and several national programmes has facilitated wider distribution of disease-free germplasm of a greater range of diversity across Africa than could have been achieved through distribution of cuttings. Micropropagation has been extensively employed in the

151

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 13

152

Chapter 13

distribution of cassava cuttings in Burundi following disruption of farming systems during the conflict there (DeVries, 1999). Genetic engineering of cassava has been constrained by the lack of a reproducible system for generating transgenic plants. Recently, however, regeneration of plants from undifferentiated callus tissue has been achieved using suspension culture techniques (Taylor et al., 1996). These cultures were then used in regenerating transgenic cassava plants via microparticle bombardment of the culture medium (Schopke et al., 1996). Hong-Qing Li et al. (1996) have also reported the development of transgenic plants via transformation using Agrobacterium. Stable expression of agronomic genes in transformed plants, however, has proved difficult to achieve. Genetic modification of cassava for modified starch composition has been achieved by researchers at Wageningen, Netherlands, and field testing is expected to begin soon (Johanson and Ives, 2000). Researchers at Ohio State University have also developed transgenic cassava with reduced cyanide toxicity (Johanson and Ives, 2000). Biotechnology applications for cassava have been delayed in large part by the overall lack of information on cassava genetics, caused by the low level of investment and the biological barriers to genetic dissection mentioned above. In addition, cassava is believed to be an allopolyploid, with 36 somatic chromosomes. For this reason, it has long been difficult to distinguish between true heterozygosity and duplicated genes in various parts of the genome (Lefevre and Charrier, 1993). In spite of these complexities, cassava has a relatively small genome, and this has facilitated the development of genetic maps using molecular markers. A genetic linkage map for cassava has been constructed using 132 RFLP markers, 30 RAPDs, three microsatellite markers, and three isoenzyme markers (Fregene et al., 1996). This map is based on an F1 population from a cross between elite varieties from Nigeria and Columbia. In addition, Chavariagga-Aguirre et al. (1998) have identified 32 microsatellite markers, for which 22 primers have been developed. Since 1997, CIAT has been developing PCR-based markers for the cassava genome. Over 1000 putative simple sequence repeats (SSRs) have been identified, and primers have been developed for over 60 of these markers. The aim of the project is to identify several hundred SSR markers in order to saturate the genome map. The same group has developed expressed sequence tags (ESTs) from approximately 250 polymorphic cDNA sequences. QTLs have been identified for useful traits such as early bulking, postharvest deterioration, starch quality and content, and morphological traits (CIAT, 1998). Since 1996, researchers at CIAT and IITA have collaborated on the mapping of genes for resistance to ACMV (CIAT/IITA, 1999). Two F1 mapping populations with different sources of resistance to the disease were analysed using 186 SSR markers. Using bulk segregant analysis, a single gene, believed to be from a chromosomal segment of glaziovii origin, was identified as ‘CSY1’. Future phases of the project are focusing on map-based cloning of the resistance gene, molecular characterization of virus strains, and markerassisted introgression of the resistance gene into Latin American cassava populations.

13.5 Principal Challenges for Cassava Improvement in Africa One of the most significant challenges associated with cassava improvement is its high level of genotype × environment interactions. Breeding programmes, therefore, must

152

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 13

153

Cassava

continually develop large numbers of new genotypes for testing in a wide range of environments (Dixon et al., 1996). This constraint also carries obvious implications favouring the decentralization of breeding programmes. However, although the two crops are of similar importance in Africa, the number of NARSs with breeding programmes for cassava is roughly one-fifth the number of those with maize breeding programmes. While the difficulties associated with cassava breeding would naturally tend to set limits on the number of institutes actively engaged in breeding, it seems clear that more countries should have such programmes, and that decentralization of the regional breeding programme carried out by IITA is a priority challenge for the future. In fact, national programme scientist involvement in breeding has been part of the IITA programme in Uganda since 1991; however, developing improved varieties with specific adaptation to mid-altitude ecologies will require that a greater number of NARSs become involved. While population development for West Africa is at far more advanced stages within the IITA programme, decentralization and greater involvement of national scientists and farmers in the breeding and selection process is relevant in this region, as well. Cassava is an ideal crop for participatory approaches to crop improvement in that significant variability can be maintained at early evaluation stages and yet lines are fixed clonally after the cross. Such approaches are best developed at the level of the national programmes, since local farmer preferences can be introduced into the evaluation process. However, systematic methods need to be developed and evaluated before integrating participatory approaches into network and NARSs activities. The IITA cassava breeding programme for West and central Africa has been quite successful in developing populations for the different ecologies of that region. Cassava varieties for mid-altitude zones of East and central Africa have been drawn largely from these populations, in spite of important differences which exist between the ecologies. Meanwhile, it has been postulated that Latin American cassava populations adapted to higher altitude zones of that continent may have significant adaptation advantages in East and southern Africa. Therefore, development of new populations in east and southern Africa is viewed as a major future challenge. In a more general sense, cassava’s status as a ‘standby’, food security crop in much of eastern Africa would appear to have reduced adoption rates of improved varieties with higher productivity potential (see Plate 22). Areas of Africa where adoption of improved varieties have been highest (generally thought to be Nigeria and Ghana) are those where processing technology is also most developed and widespread. Improvement programmes, therefore, may do well to pay close attention to opportunities for commercialization and processing of the crop.

13.6 Cassava Seed Systems Cassava germplasm is not disseminated via commercial channels in Africa. This constraint, coupled with slow and very laborious methods of multiplication via cuttings have severely constrained diffusion of improved germplasm in many parts of the continent.

153

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 13

154

Chapter 13

Cassava dissemination has often depended on ‘campaign approaches’ which aim at distributing large quantities of improved planting stock via specially funded initiatives. This approach has been employed as a response to the disruption of agricultural systems as a result of conflict in Mozambique, Angola, Liberia, Sudan, Burundi and various other countries. In Uganda and western Kenya, large-scale multiplication initiatives have recently been implemented in response to the outbreak of new-variant ACMV in those areas. In the case of Angola, tissue-cultured plantlets of over 500 accessions of improved cassava were transferred directly from the IITA laboratory to improvised hardening-off facilities in production areas before being transferred to multiplication beds. The impact of these projects is primarily related to the rapid transfer of varieties with disease resistance in areas which had not previously been reached. Using rapid multiplication techniques, these projects have increased the rate at which farmers can now receive improved germplasm. In western Kenya, ratios (in area terms) of seed field:planting field of 1:10 have been employed, with primary and secondary seed fields designated for production of initial increases and production of planting stock for farmers, respectively (Onim, 1998). In this case, primary multiplication sites were located on research stations, while secondary sites were located on rented land or farmers’ fields. Recently, national programmes have been very instrumental in large-scale multiplication and distribution of improved germplasm. Three high-yielding varieties have been released in Ghana and are being multiplied by the Crops Research Institute, MOA, and various NGOs. In response to the recent new-variant ACMV epidemic, the national programme in Uganda has released four IITA-breed varieties which are already being grown on 80,000 ha. As of late 1998, a total of 1.3 million seedlings were in multiplication in Serere and Namulonge, Uganda and Mtwapa, Kenya. Multiplication and distribution of ACMV-resistant varieties is underway in Nigeria, Sierra Leone, Angola, Malawi, Mozambique, Namibia, Tanzania, Zambia, Zimbabwe, Swaziland, Lesotho, Togo, Benin, Guinea and the Gambia, and in most EARNET countries, including Kenya, Uganda, Rwanda and Madagascar. One of the more difficult challenges facing cassava improvement programmes in Africa is the development of effective methods of multiplication and distribution of clean planting material. Since cassava planting material is bulky and the rate of multiplication is slow, innovative methods for seed multiplication and distribution need to be developed. The development of a sustainable seed system will need to be built around a steady flow of new varieties, a primary multiplication point, and a distributed set of secondary and tertiary multiplication points. Significant progress has been made in in vitro multiplication techniques and post-flask management of plantlets, but there is still a need to improve further plant establishment under different agro-ecological conditions, especially in more harsh environments, and to reduce the costs involved. Tissue culture capacity in Africa is both limited and often inefficient in handling large-scale multiplication. Existing capacity is primarily devoted to quarantine and research activities, and has limited experience in larger scales of operation. The role of tissue culture in cassava multiplication in Africa remains questionable, requiring some evaluation of organization and economic costs. If tissue culture is not the primary multiplication point for planting material, then cost-effective alternatives need to be developed.

154

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 13

155

Cassava

13.7 Review of Priority Areas of Research and Development A review of the overall strategy for development of cassava in Africa reveals two principal elements, namely, reinforcing cassava’s role as a food security crop in existing rural production and consumption systems and developing cassava’s market and income generation potential in areas where markets exist. Likewise, the review points toward two key elements to the development of a cassava improvement strategy for Africa. First is that the target is uniquely smallholder systems. Second, a research strategy to expand cassava markets and develop the crop’s commercial potential should at the same time reinforce cassava’s role as a food security crop. Increased productivity, linked to more efficient processing methods, could increase farmers’ incomes at the same time as improving the security of the subsistence food base. Breeding targets are both a function of genotypic adaptation to biotic and abiotic stresses–amalgamated in the concept of agro-ecology – and a function of root and leaf quality characteristics, determined by end use and product markets. Breeding is structured in terms of agro-ecologies, but overall targets are an overlay of agro-ecologies and product markets, as the two are not congruent. 1. Broad introduction of early-bulking, stress-resistant varieties. An estimated 80% of Africa’s cassava harvest continues to come from late-bulking, unimproved landraces. Therefore, a major challenge remains in the area of breeding and participatory variety selection programmes to increase exposure of farmers to improved varieties with higher productivity potential and other, yield-stabilizing traits such as resistance to ACMV and CBB. 2. Improved nutritional characteristics. Given cassava’s relatively poor quality carbohydrate and low protein contents, coupled with its increasing popularity among very poor farmers of marginal zones in Africa, it is clear that an emphasis should be placed on key aspects of its nutritional profile. Increased iron, zinc, and vitamin A precursor have been cited as potential targets for micronutrient enhancement (Alfred Dixon, personal communication). 3. Characterization and targeting of cassava breeding environments. Little has been done to understand better the factors which contribute to good adaptation. Yet the potential impact of improved cassava is often hampered by low uptake by farmers. The best approach to take in regard to priority is to describe common areas where cassava is – or is rapidly becoming – an important crop, and study the major constraints and characteristics of its growth and utilization. 4. Decentralization of cassava breeding programmes. At present, virtually all crossing is being done at a single site in Nigeria, while cassava improvement at a national level is relegated to screening large numbers of F1 seed. Enabling national programmes to perform their own crosses – based on information gathered on agro-ecologies and knowledge of the combining ability of parental clones – may unlock new opportunities for uptake of cassava at a local level. Linked to this, uptake of improved varieties may also be improved by involving farmers in selection processes at an earlier stage in their development. Participatory selection methods should therefore accompany this initiative. 5. Pest and disease resistance. Linked to the above, a determined focus on reducing losses from important pests and diseases is a clear priority. ACMV, cassava green mite,

155

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 13

156

Chapter 13

and CBB are observed to cause damage to the harvest in large areas of Africa. Of critical importance at this time is responding to the serious outbreak of the UgV variant of ACMV in east Africa (through rapid dissemination of adapted, resistant clones) and the outbreak of cassava brown streak disease in northern Mozambique. 6. Population improvement for mid-altitude agro-ecologies. Cassava is an increasingly important crop in mid-altitude environments of eastern and southern Africa. Yet the range of improved materials adapted to these ecologies is still limited. 7. Improved root quality characteristics. As industrial-level cassava processing becomes more common, demand for speciality varieties with high starch, longer preservation, or high soluble sugars is expected to rise. Recent evidence suggests that marker-assisted selection may be effective in selecting for these traits. Meanwhile, root rot, associated with poor soil fertility, is reported to be an increasing problem in parts of Nigeria.

156

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 13

14

Banana

14.1 Brief History of Banana Cultivation and Utilization in Africa Plantain and bananas serve as important food crops in much of Africa. Together they provide more than 25% of carbohydrate needs of over 70 million people on the continent (IITA, 1998). Cultivated bananas are derived from two species of the genus Musa, M. acuminata and M. balbisiana (Stover and Simmonds, 1987). M. acuminata originates in Malaysia, while M. balbisiana originates in India (Simmonds, 1966). Bananas cultivated in Africa are diploid and triploid genetic combinations of ‘A’ and ‘B’ genomes contributed by one or both of these species. African bananas are grouped into three categories, including East African (mainly dessert) bananas (AA, AAA, ABB, and AB), the African plantain bananas (AAB) grown mainly in central and West Africa, and the East African Highland banana (AAA), used for cooking and in beer preparation (Karamura, 1998). Although not of African origin, African bananas have evolved into an important zone of secondary genetic diversity. In particular, the lowland regions of West Africa contain the world’s largest range of genetic diversity in plantain, while the highlands of East Africa are an important centre of diversity of cooking bananas (Ortiz and Vuylsteke, 1994). Banana is a clonally propagated plant. Triploid genotypes are virtually or completely sterile and develop their fruit through vegetative parthenocarpy. Diploid landraces and tetraploid cultivars (mostly artificial hybrids) are also cultivated. Commercial production of banana and plantain is characterized by the use of a very limited number of varieties. ‘Cavendish’, for example, is currently the most widely cultivated variety of dessert banana, and is grown throughout the world, while ‘Cuerno’ (Horn) is a widely cultivated variety of plantain. Bananas and plantains are consumed in a wide variety of manners in Africa. Dessert bananas are consumed raw as snacks and desserts. Plantains are fried in various ways and eaten as side dishes and fast foods. Cooking bananas and highland bananas are pounded into thick porridges (‘fufu’ and ‘matooke’). Beer bananas are fermented and consumed

157

157

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 14

158

Chapter 14

as traditional wine in the Great Lakes regions of Uganda, Democratic Republic of Congo, Rwanda and Burundi.

14.2 Banana Production Trends in Africa Sub-Saharan Africa produces about 35% of the world’s bananas and plantains (Table 14.1). Banana and plantains have been estimated to supply more than 25% of the carbohydrates of approximately 70 million people in Africa’s humid forest and midaltitude regions (Vuylsteke et al., 1992). Banana production increases have been slow, and generally not kept pace with population growth (Fig. 14.1). This is due mainly to decreasing yields in the East African Highlands, caused in part by increasing incidence of weevils, black Sigatoka disease and nematodes. In West Africa, as well, plantain production has been seriously affected by high levels of incidence of black Sigatoka. East Africa (most notably the Great Lakes region covering portions of Rwanda, Burundi, Tanzania, Kenya and Congo) is the largest producer and consumer region for bananas in Africa. The Great Lakes region is estimated to produce 15 million tonnes of bananas per year, and per capita consumption is the highest in the world (INIBAP,

Table 14.1.

Production of bananas and plantains in Africa. Production (1000 t year −1)

Region West and Central Africa Angola Cameroon Dem. Rep. of Congo Rep. of Congo Côte d’Ivoire Gabon Ghana Guinea Liberia Nigeria East Africa Burundi Kenya Madagascar Malawi Rwanda South Africa Tanzania Uganda Others Total

Per capita consumption (kg)

318 1274 1831 80 1194 159 637 318 159 1990

24 85 69 46 98 142 64 46 44 25

1506 452 301 151 2108 151 1656 8432 301 23,018

88 34 17 9 5 180 43 222

Source: FAO (1999).

158

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 14

159

Banana

2000). However, increases in production have not kept pace with population growth, indicating stagnating banana production in these principal areas. The decline in productivity of banana plantings in Uganda has been extensively studied and documented (Frison et al., 1999; Karamura, 1999) (Fig. 14.2). Causes of this trend have been blamed on increasing incidence of pests and diseases, most notably nematodes, weevils (associated with declining soil fertility), black Sigatoka and Fusarium (associated with the increased incidence of these diseases, worldwide) (see Plate 23). The small number of pests and diseases, coupled with the wide exchange of information regarding their causal agents among a relatively small number of researchers, makes it difficult, if not impossible, to consider Africa-based research on pests and

Fig. 14.1. (1999).

Banana and plantain production in Africa, 1975–1999. Source: FAO

Fig. 14.2.

Declining banana yields in Rwanda and Uganda, 1970–1997.

159

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 14

160

Chapter 14

pathogens in isolation from the rest of the world. Therefore, in contrast to sections on pests and pathogens of other crops in this book, those affecting banana and plantain in Africa will be considered in relation to their incidence, worldwide.

14.3 Banana Production Constraints Bananas throughout the world suffer from a relatively small number of pests and diseases, which however can be highly devastating to yield and production. Moreover, a number of the most important pests and diseases in Africa have been increasing in recent years (Wilson, 1988), often associated with the widespread phenomenon of reduced fallow periods (IITA, 1998). Among the most serious pests and diseases are: banana weevil (Cosmopolites sordidus), a complex of nematodes (Pratylenchus goodeyi, Helicotylenchus multicinctus and Radopholus similis), black streak/black Sigatoka (Mycosphaerella figiensis), yellow Sigatoka (M. musicola), Fusarium wilt (Fusarium oxysporum), banana bunchy top virus and banana streak virus. Of these, black streak/black Sigatoka is considered to be the most serious biotic constraint to banana and plantain production in Africa (Swennen et al., 1989; Ortiz and Vuylsteke, 1994). Black streak/black Sigatoka disease was accidentally introduced in central Africa in the 1980s (Wilson and Buddenhagen, 1986). All plantains and East African highland bananas are susceptible to black streak/black Sigatoka. Worldwide, banana bunchy top virus is perhaps the most important virus affecting Musa (Dale, 1987). In Africa, it has been most widely observed in central Africa (Diekmann and Putter, 1996), however, it is not believed to cause heavy losses. Banana streak virus (BSV) was first described on banana plantings in Côte d’Ivoire by Lassoudiere in 1974 and first isolated by Lockhart in 1986. BSV is a badnavirus which occurs throughout banana-producing areas of the world. Whereas numerous recent studies have shown that badnavirus is present in many plantings, significant loss of production caused by the disease has been limited to a small number of locations. In nature, BSV is believed to be vectored by the mealy bug. BSV sequences are incorporated into the host genome. It is believed that tissue culture triggers transcription of the virus, leading to symptom expression. De novo generation of BSV infection of ‘clean’ germplasm has occurred in a number of progeny reproduced through tissue culture, especially among the recently produced tetraploid hybrid varieties (Hughes and Tenkouano, 1998). Based on detection of integrated BSV sequences in banana chromosomal DNA isolated from asymptomatic plants, there is speculation that activation of the virus may occur as a result of tissue culture or other stresses. Episomal BSV appeared in tissue-cultured plants which shared more than 99% sequence homology with integrated BSV from parent plants (Lockhart et al., 1998). The disease causes mild symptoms which include chlorotic and necrotic streaks on leaf tissues, and severe symptoms which can include distorted bunches, heart rot, and plant death. Yield reductions from these symptoms range from 7 to 90% (Frison and Sharrock, 1998). The most important insect pest of banana and plantain in Africa is the banana weevil (Cosmopolitus sordidus). Banana weevils enter the plant through the soil and bore through the base of the pseudostem, thus weakening the plant. Both highland bananas and plantains are susceptible to weevils (Vuylsteke et al., 1993).

160

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 14

161

Banana

A less well understood but nevertheless well-documented problem of plantain production in West and central Africa is commonly known as ‘yield decline’. Yield decline is usually associated with medium-sized plantings among smallholder producers who grow bananas in open fields (Ortiz and Vuysteke, 1994). This disease may be the result of a complex of production-related constraints such as declining soil fertility, including micronutrient deficiencies, weevils and nematodes. Nematodes are recognized as important pests of bananas and plantains in most producing areas. Average annual losses worldwide are believed to be in the order of 20% (Sasser and Freckman, 1987). The most damaging species of nematodes on bananas are the burrowing nematode (Radopholus similis), root-lesion nematodes (Pratylenchus coffeae and P. goodeyi), and spiral nematodes (Helicotylenchus multicinctus) (Speijer and De Waele, 1997). Above-ground symptoms of nematode damage include plant lodging, stunting, chlorosis and reduction of bunch weight. The threat to banana production posed by Fusarium wilt is greatest in plantation situations. The pathogen proliferates in the vascular system of plants, causing symptoms of terminal wilt, yellowing of leaves, and loss of yield. Chemical control measures are not effective at controlling the disease. Soils which have been infested with the pathogen cannot be cultivated with susceptible varieties of banana for up to 30 years. Fusarium wilt was first discovered in Australia by Bancroft in 1876. By the 1960s it had spread to most of the major banana and plantain producing regions of the world. The susceptibility of the dessert varieties ‘Gros Michel’ and ‘Ladyfinger’ to Fusarium wilt led to their virtual elimination from use worldwide. They were eventually replaced by the variety ‘Cavendish’, which now accounts for nearly all of the worldwide export market for dessert bananas. Although ‘Cavendish’ is immune to Race 1 of Fusarium wilt, it has proven to be susceptible to Race 4. In East Africa, Race 1 of Fusarium wilt has been known to occur on introduced varieties since the 1950s (Jameson, 1953; Ploetz, 1990). It has been reported on East African highland bananas since the 1980s; however, incidence in infected plantings has been estimated at less than 5% of plants (Ploetz, 1994). Race 4 of Fusarium wilt is an important disease on plantations of ‘Cavendish’ bananas in South Africa.

14.4 Banana Improvement Through Biotechnology and Breeding Banana breeding advances in Africa Banana improvement wordwide is characterized by the extremely small number of teams actively involved in breeding. Important centres for banana and plantain improvement are located in: Honduras, at the Fundacion Hondurena de Investigacion Agricola (FHIA); in Onne, Nigeria, at the International Institute for Tropical Agriculture (IITA); in Brazil, at the Empresa Brasileira de Pesquisa Agropecuaria (EMBRAPA); in Montpelier, France at the Centre International de Rescherche Agricole pour le Developpement (CIRAD-FLHOR); in Cameroon, at the Centre de Recherche sur la Banane et Plantain (CRBP); at the Agricultural Research Centre in South Africa; and at the Banana Board of Jamaica (Frison et al., 1997). Breeding of banana and plantain has achieved a major breakthrough in recent years with the development of a hybridization technique advanced by FHIA (Rowe and

161

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 14

162

Chapter 14

Rosales, 1994). In this method, male fertile diploid bananas are used to pollinate popular triploid varieties to produce tetraploid hybrids. In most cases, fertile diploids are sought which can contribute important traits not found in cultivated triploid species. The result is a hybrid tetraploid which expresses traits of both parents. Following identification of improved, adapted tetraploids, breeders make additional crosses to produce sterile triploids. Following a long-term effort employing this approach, FHIA recently began distributing a series of tetraploid hybrid bananas with novel traits and good general agronomic characteristics for various uses. However, adoption rates of these hybrids in East Africa have remained low, due to poor cooking quality (INIBAP, 2000). These varieties have been tested and released by farmers in several important banana-growing regions of Africa. Subsequently, IITA breeders in Uganda began employing similar methods aimed at improving East African Highland bananas (Ortiz and Vuylsteke, 1994). Adoption of improved varieties developed by this method, however, have also been reported to be limited by low yield potential and poor cooking quality (INIBAP, 2000). Unfortunately, progeny of tissue-cultured tetraploid hybrids have been diagnosed with high percentage infection of banana streak virus, and have been quarantined in some parts of the world. Because there is no reason to believe that these varieties should have higher susceptibility to BSV, many questions have been posed, with few definitive answers. It has been postulated that tissue culture may have led to the expression of BSV, which is an integrated DNA virus (Frison and Sharrock, 1998). Breeding for resistance to black streak/black Sigatoka disease and other biological constraints at IITA represents another recent, significant breakthrough in banana/ plantain breeding in Africa. Beginning in 1987, IITA screened Musa accessions for resistance to black streak/black Sigatoka and found 30 sources of resistance, most of which were fertile diploid types (Swennen and Vuylsteke, 1991). Following the breeding technique developed by Rowe, researchers crossed male-fertile, resistant diploid accessions to female-fertile, tripoid cultivated varieties to obtain resistant, tetraploid hybrids. Additional diploid accessions produced through this process have since been crossed to tetraploid hybrids to obtain male-sterile, secondary triploids (Ortiz and Vuylsteke, 1994). IITA has developed five hybrid cultivars (‘PITA-2’, ‘PITA-3’, ‘PITA-8’, ‘PITA-14’ and ‘PITA-17’) with resistance to black Sigatoka. These are being tested on-farm in Uganda. In addition, IITA’s ‘PITA-16’ has been shown to be black Sigatoka, lodging, nematode and (moderately) weevil resistant (Vuylsteke et al., 1998). ‘PITA-3’ has been identified for release and distribution in Côte d’Ivoire. Nematode resistance has been detected in bananas, with ‘Yangambi Km5’ (AAA) and ‘Pisang Jari Buaya’ (AA) having been classified as highly and completely resistant to R. similis, respectively (Speijer and De Waele, 1997). Banana improvement for resistance to nematodes is constrained by lack of an efficient screen, making the trait a candidate for eventual selection via molecular marker. Recently, researchers in Uganda have produced convincing evidence of a genetic factor in the control of weevils in East African Highland banana (Gold et al., 1998). Data from liquid chromatograph analyses indicated that several compounds could be identified in resistant varieties which were absent in susceptible varieties. Ongoing research is aimed at identifying the compounds responsible and, eventually, developing an efficient laboratory screen for this trait.

162

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 14

163

Banana

Advances in banana biotechnology A review of biotechnology applications for banana was published in 1998 by Crouch et al. Tissue culture of bananas via multiple shoot tip culture based on the addition of cytokinins to standard media has become a widespread method of propagating selected, clean clones for cultivation in field and plantation (Vuylsteke et al., 1997). In Kenya, selected farmers have adopted the cultivation of tissue-cultured banana on both large and small scale (ISAAA, 1997). Tissue-cultured banana plants exhibit significantly increased vigour and yield, and earlier maturity. However, broader use of tissue-cultured bananas depends on scaling up both the culturing and dissemination systems. Strategies aimed at commercial-scale dissemination of tissue-cultured bananas have been advanced for support of donors and African governments. Propagation of banana via cell suspension has been achieved in various laboratories (Novak et al., 1989; Dhed’a et al., 1991); however, the technique has not become routine (see Plate 24). Molecular genetics studies of banana have focused primarily on identification of genetic variation and useful genes using PCR-based markers (Crouch et al., 1998). A molecular linkage map has been developed for banana using a range of marker systems (Fauré et al., 1993), and several hundred SSR markers have been identified by various research teams (Jarret et al., 1994; Lagoda et al., 1995; Kaemmer et al., 1997). High levels of polymorphism have been detected, and strategies have been advanced for utilization of RAPD markers to analyse genetic variation in East African Highland bananas (Patrick Rubahaiyo, personal communication). More recently, AFLP markers have been identified and advanced as effective systems for genetic analysis and improvement in banana (Crouch et al., 1998). Due to the significant barriers inherent in conventional breeding of bananas, molecular breeding has been viewed as an advancement of significant potential benefit for the crop. Banana improvement programmes with molecular genetics capacity have proposed numerous applications of molecular methods, including the cloning of microsatellites, analysis of breeding systems (especially, the enhancement of tetraploid generation methods), disease diagnostics, and marker-assisted selection. To date, however, no clear strategy has been formulated for genetic improvement of banana or plantain in principal areas of production that integrates the two methodologies. Tragically, an airline crash in Abidjan, Côte d’Ivoire, in early 2000 robbed the banana improvement community in Africa of three very dedicated and critical sources of expertise on this subject area. Dessert banana and plantain have been successfully transformed using electroporation of protoplasts (Sagi et al., 1994), particle bombardment of embryogenic cells (Sagi et al., 1995), and Agrobacterium (May et al., 1995). To date, Agrobacteriummediated methods have proved the most successful (Crouch et al., 1998). Enhanced in vitro resistance to Fusarium wilt and black Sigatoka has been reported in transgenic bananas developed at the Catholic University of Leuven (Remy et al., 1998). Researchers at the University of Leeds and the University of Wales, UK, are developing a gene construct aimed at conferring resistance to weevils (Johanson and Ives, 2000). However, no transgenic bananas are currently in cultivation, due in part to the lack of opportunities to field-test them. In addition, East African Highland bananas have not as yet been transformed. In their review of genetic transformation possibilities, Crouch

163

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 14

164

Chapter 14

et al. (1998) identified resistance to the viral diseases, banana streak virus and banana bunchy top virus as the two top priorities. In 2000, the Ugandan government committed $500,000 toward the development of transgenic banana with resistance to black sigatoka, weevils and nematodes.

14.5 Principal Challenges for Banana Improvement in Africa A worldwide banana improvement strategy advanced by the World Bank in 1998 proposed the following allocation of priorities for genetic research: black Sigatoka resistance (especially in Cavendish-type banana) – 50%; nematode resistance – 25%; Fusarium wilt resistance – 15%; and virus diseases – 10%. In the absence of more agro-ecologically focused prioritization, these can be assumed to be at least partially relevant for Africa, as well. Fusarium wilt and black Sigatoka-resistant bananas for highland areas of East Africa represent a major challenge for banana breeders, not least because farmers in this region have not taken enthusiastically to previous offerings. East African Highland bananas have physical and chemical properties that distinguish them from other subgroups (Hartman et al., 1998). Recent analyses of these characteristics seemed to indicate that percentage dry matter correlates well with taste preferences. Two additional areas of focus are more decentralized breeding systems and multilocation testing. Banana breeding remains a technically difficult undertaking. Banana flowers exhibit low fertility, plants take 1 year to mature and 2 years to produce seed, and each plant requires upwards of 6 m2 of research land. Methods devised by FHIA and IITA for banana improvement represent innovations that could be extended to national level in countries where banana production is important (Hartman and Vuylsteke, 1998). Multilocation testing of the materials which have already been developed through these techniques could contribute to higher adoption rates as well as more accurate priority setting for future breeding efforts. Molecular breeding of banana could replace laborious, time-consuming screens in the field (some which may require up to 1 year) by developing tightly linked markers for major traits. However, providing sufficiently large segregating populations for screening is dependent on further improvements in seed production and more systematic methods for converting hybrid tetraploids into sterile triploids.

14.6 Banana Seed Systems As relatively long-lived crops, substitution of improved cultivars for traditional ones should be viewed as a long-term goal. Indeed, few initiatives have aimed at systematic transfer of improved banana varieties to small-scale farmers, and therefore little information is available regarding farmers’ common sources of planting stock. A recent survey performed by IITA in Cameroon provides some insight. Among 243 banana farmers interviewed, 89.3% of farmers procured their planting material from preceding plantings, 13.3% were purchased off-farm, and 5.8% were obtained through trades with neighbours (Hauser et al., 1998). Recently, dissemination of improved planting material

164

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 14

165

Banana

of banana throughout Africa has been seriously constrained by quarantine regulations associated with the incidence of banana streak virus in tissue-cultured germplasm (Vuylsteke et al., 1998). Due to the high costs (transport, labour) related to such substitutions, farmers will probably only be persuaded to do so if there are significant, easily recognized advantages in the new varieties. Incremental yield increases are not viewed as a likely motivating factor for small farmers. Significantly higher resistance to diseases or pests, however, could well serve as a sufficiently strong persuasion factor, since farmers who lose a crop to pests and diseases may lose a 6–12 month investment. Dissemination of improved dessert banana for commercial, semi-commercial, and export markets can be a relatively straightforward exercise. Because of the bulkiness of the planting material, however, the opportunities for small-scale seed enterprises to engage in broad-based dissemination of improved banana are probably limited. Commercial growers and small-scale producers of banana are likely to follow very different decision-making processes regarding improved cultivars. Dissemination of improved banana for small-scale producers is likely to always require public resources, even if the major operations are subcontracted to private sector groups. In the case of tissue-cultured bananas, this could come in the form of culturing and hardening off of plantlets in soil, prior to sale at subsidized prices to stockists in the target areas. For non-tissue-cultured bananas, this may come in the form of maintaining large planting stock nurseries in the project area for direct sale to farmers and wholesaling to stockists. The latter activity could be taken on by local NGOs supported by donor agencies and governments.

14.7 Review of Priority Areas of Research and Development 1. Development of Sigatoka and Fusarium-resistant East African Highland banana. This is perhaps the single, highest potential impact objective for Africa, due to the high dependence on banana among farmers of the Great Lakes region. Major difficulties stem from issues related to farmer preferences in varieties used for traditional dishes. Transgenic varieties of plantain with reported high levels of resistance to Sigatoka disease are currently blocked from entry into areas where they could have a major impact due to lack of necessary biosafety protocols covering transgenic crops. 2. Identification of useful markers for breeding applications. This work would be aimed at eliminating the need for time-consuming screens for resistance traits. Candidate traits for marker identification would be resistances to nematodes, weevils, viruses, and major foliar diseases. Putative resistance to weevils has been noted in some varieties of East African Highland banana. 3. Multilocation testing of improved varieties. Because banana improvement will always be a task carried out by only a few research groups, broad-based testing is critical to inform these teams of the potential for adoption of improved varieties. At present, testing of improved bananas is carried out only on a very limited scale. 4. Further research on banana streak virus. Although BSV is a relatively low-level threat to production in most of Africa, it can reach epidemic levels in certain cases, as in the

165

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 14

166

Chapter 14

recent outbreak in Rakai and surrounding districts of Uganda. More critically, poor understanding of BSV infection and expression has led regulators to operate with extreme caution in the dissemination of improved, but possibly BSV-infected, varieties.

166

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter 14

References

Abadasi, J.A., Singh, B.B., Ladeinde, T.A.O., Soyinka, S.A. and Emechebe, A.M. (1987) Inheritance of resistance to brown blotch. Septoria leaf spot and scab in cowpea. India Journal of Genetics 47, 299–303. Adenle, V., Cardwell, K.F., Ayinde, O., Onukwu, D. and Ogbe, G. (1998) Studies on the penetration and establishment of downy mildew in maize seeds and correlation with seed transmission. In: Project 5: Integrated Management of Maize Pests and Diseases. Annual Report 1998. International Institute of Tropical Agriculture, Ibadan, Nigeria, pp. 4. Adesina, A.A. and Baidu-Forson, J. (1995) Farmers’ Perceptions and Adoption of New Agricultural Technology: Evidence from Analysis in Burkina Faso and Guinea, West Africa. Elsevier, 1986–Oct. 1995. Amsterdam, Netherlands. Adjadi, O., Singh, B.B. and Singh, S.R. (1985) Inheritance of bruchid resistance in cowpea. Crop Science 25, 740–742. Aggrawal, B.L. and House, L.R. (1982) Breeding for pest resistance in sorghum. In: Proceedings of the International Symposium on Sorghum in the Eighties, 2–7 Nov, 1981. ICRISAT, Andra Pradesh, India, pp. 435–446. Aggrawal, B.L., Abraham, C.V. and House, L.R. (1988) Inheritance of resistance to midge in sorghum. Insect Science Applications 9, 43–45. Ahmed, M.M., Sanders, J.H. and Nell, W.T. (2000) New sorghum and millet cultivar introduction in sub-Saharan Africa: impacts and research agenda. Agricultural Systems, 1–11. Altieri, M.A. and Rosset, P. (1999) Ten reasons why biotechnology will not ensure food security, protect the environment and reduce poverty in the developing world. AgBioForum 2(3&4), 155–162. Retrieved 1 January, 2000 from the World-wide Web: http://www. agbioforum.org. Ampong-Nyarko, K., Odindo, M.O., Khan, Z.R. and Overholt, W.A. (1998) Maize Streak Virus in Eastern and Southern Africa – Vector Epidemiology. International Center for Insect Physiology and Ecology project report, Nairobi, Kenya. Andrews, D.J. and Anand Kumar, K. (1996) Use of the West African pearl millet land race Iniadi in cultivar development. Plant Genetic Resources Newsletter 105, 15–22.

171

171

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter

172

References

Andrews, D.J., King, S.B., Whitcombe, J.R., Singh, S.D., Rai, K.N., Thakur, R.P., Talukdaar, B.S., Chavan, S.B. and Singh, P. (1985) Breeding for disease resistance and yield in pearl millet. Field Crops Research 11, 241–258. Anonymous (2000) Harmonization of Seed Policies and Regulations in Eastern Africa: Agreements, Recommendations and Way, 16 pp. Arnanson, J., de Beyssac, B. Conilh, Philogene, B.J.R., Bergvinson, D., Serratos, J.A. and Hamilton, R.I. (1994) Mechanisms of resistance in maize grain to maize weevil and larger grain borer. In: Mihm, J.A. (ed.) Insect Resistant Maize. Proceedings of an International Symposium, 27 Nov.–3 Dec. 1994. CIMMYT, D.F., Mexico, pp. 91–95. Arundel, A., Hocke M. and Tait J. (2000) How important is genetic engineering to European seed firms? Nature Biotechnology 18(6), 578. Asanzi, C. and DeVries, J.D. (1995) End of Season Report: Zaire Agricultural Recovery Program. WV International, Lubumbashi, Zaire, 16 pp. Atokple, I.D.K., Singh, B.B. and Emechebe, A.M. (1995) Genetics of resistance to Striga and Alectra in cowpea. Journal of Heredity 86, 45–49. Bahia, A.F.C. and Lopes, M.A. (1998) State of the art – developing grain cultivars for acid savannas of Brazil. In: Schaffert, R.E. (ed.) Proceedings of a Workshop to Develop a Strategy for Collaborative Research and Dissemination of Technology in Sustainable Crop Production in Acid Savannas and other Problem Soils of the World. Purdue University and EMBRAPA, pp. 27–45. Bancroft, J. (1876) Report of the board appointed to enquire into the cause of disease affecting livestock and plant, Queensland. Notes and Proceedings. Bangarwa, K.S., Lodhi, G.P. and Grewal, R.P.S. (1987) Inheritance of resistance to red leaf spot disease in sorghum. Indian Journal of Genetics and Plant Breeding 47, 351–352. Bänziger, M., Betrán, F.J. and Lafitte, H.R. (1997) Efficiency of high-nitrogen selection environments for improving maize for low-nitrogen target environments. Crop Science 37, 1103–1109. Barker, R. and Cordova, V.G. (1978) Labor utilization in rice production. In: IRRI. Economic Consequences of the New Rice Technology. International Rice Research Institute, Los Baños, Philippines. Barton, J.H. (1998) International intellectual property and genetic resource issues affecting agricultural biotechnology. In: Ives, C.L. and Bedford, B.M. (eds) Agricultural Biotechnology in International Development. CAB International, Wallingford, UK, pp. 273–283. Barton, J.H. (1999) Biotechnology for Developing-Country Agriculture: Problems and Opportunities. Intellectual Property Management. Focus 2. Brief 7 of 10. October 1999. International Food Policy Research Institute (IFPRI), Washington, DC. Barton, K.A., Whitely, H. and Yang, N. (1987) Bacillus thuringiensis endotoxin in transgenic tobacco provides resistance to lepidopteran insects. Plant Physiology 85, 1103–1109. Bata, H.D., Singh, B.B., Singh, S.R. and Ladeinde, T.A.O. (1987) Inheritance of resistance to aphid in cowpea. Crop Science 27, 892–894. Bateman, K.S., Hinch, J.M., Ralton, J.E., Clark, A.E., McKenzie, J.A., Imrie, B.C. and Howlett, B.J. (1989) Inheritance of resistance in cowpea to Phytophthora vignae in whole plants cuttings and stem callus cultures. Australian Journal of Botany 37, 511–517. Bennetzen, J.L. (1996) The potential of biotechnology for the improvement of sorghum and pearl millet. In: INTSORMIL, ICRISAT. Proceedings of the International Conference on Genetic Improvement of Sorghum and Pearl Millet, held on September 22–27, 1996 at Holiday Inn Plaza, Lubbock, Texas. Benson, T.D. (1997) Annotated Bibliography of the Work on Area-Specific Fertiliser Recommendations for Maize in Malawi. Maize Commodity Team Annual Report for the Year 1995/96. Chetidze Agricultural Research Station, Malawi. van den Berg, J. (2000) Evaluation of SMIP-developed sorghum cultivars for resistance to stem borer (Chilo partellus) and the aphid (Melanaphis sacchari). In: Minja, E.M. and van den

172

A4138:AMA:DeVries:First Revise:19-Oct-01

Chapter

173

References

Berg, J. (eds) Proceedings of the Workshop on Management of Sorghum and Pearl Millet Pests in the SADC Region, 10–13 February 1998, Matopos Research Station, Zimbabwe. ICRISAT, Bulawayo, Zimbabwe. Berhan, A.M., Hulbert, S.H., Butler, L.G. and Bennetzen, J.L. (1993) Structural and evolution of the genomes of sorghum and maize. Theoretical and Applied Genetics 86, 598–604. Bhaskaran, S. and Smith, R.H. (1990) Regeneration in cereal tissue culture: a review. Crop Science 30, 1328–1336. Bhattramakki, D., Dong, J., Chhabra, A.K. and Hart, G.E. (2000) An integrated SSR and RFLP linkage map of Sorghum bicolor (L.) Moench. Genome 43, 988–1002. Binelli, G., Gianfranceschi, L., Pe, M.E., Taramino, G., Busso, C., Stenhouse, J. and Ottaviano, E. (1992) Similarity of maize and sorghum genomes as revealed by maize RFLP probes. Theoretical and Applied Genetics 84, 10–16. Binswanger, H.P. and Pingali, P. (1989) Technological priorities for farming in sub-Saharan Africa. Journal of International Development, 1, 46–65. Blackie, M.J. (1994) Maize productivity for the 21st century: the African challenge. In: Jewell, D.C., Waddington, S.R., Ransom, J.K. and Pixley, K.V. (eds) Maize Research for Stress Environments. Proceedings of the Fourth Eastern and Southern Africa Regional Maize Conference, held at Harare, Zimbabwe, 28 March–1 April 1994. CIMMYT, Mexico DF, Mexico, pp. xi–xxiii. Bosque-Perez, N.A. and Mareck, J.H. (1990) Distribution and species composition of lepidopterous maize borers in southern Nigeria. Bulletin of Entomological Research 80, 363–368. Bubeck, D.M., Goodman, M.M., Beavis, W.D. and Grant, D. (1993) Quantitative trait loci controlling resistance to gray leaf spot in maize. Crop Science 33, 838–847. Buddenhagen, I.W. (1983) Breeding strategies for stress and disease resistance in developing countries. Annual Review of Phytopathology 21, 385–409. Buddenhagen, I.W. (1996) Modern plant breeding: an overview. In: Persley, G.J. (ed.) Biotechnology and Integrated Pest Management. CAB International, Wallingford, UK. Buddenhagen, I.W. and de Ponti, O.M.B. (1983) Crop improvement to minimize future losses to diseases and pests in the tropics. FAO Plant Protection Bulletin 31, 11–30. Bui-Dang-Ha and Pernes, J. (1982) Androgenesis in pearl millet. I. Analysis of plants obtained from microspore culture. Zeitshrift für Pflanzenzuchtung 108, 317–327. Bumb, B.L. and Baanante, C.A. (1996) The role of fertilizer in sustaining food security and protecting the environment to 2020. Food, Agriculture and the Environment Discussion Paper 17. IFPRI, Washington, DC. Butler, L.M., Myers, J., Nchimbi-Msolla, S., Massangye, E., Mduruma, Z., Mollel, N. and Dimosa, P. (1995) Farmer evaluation of early generation bean lines in Tanzania: comparisons of farmers’ and scientists’ trait preferences. Southern Africa Development Community (SADC) Regional Bean Research Workshop, 2–4 Oct. 1995, Oil and protein Seed Center. Potchefstroom, South Africa, 20pp. Byerlee, D. (1996) Modern varieties, productivity, and sustainability: recent experience and emerging challenges. World Development 24 Nos. 1–4. The World Bank, Washington, DC. Byerlee, D. and Eicher, C.K. (1997) Africa’s Emerging Maize Revolution. Lynne Rienner Publishers, Boulder, Colorado. Byerlee D. and Heisey, P.W. (1997) Evolution of the African maize economy. In: Byerlee, D. and Eicher, C.K. (eds) Africa’s Emerging Maize Revolution. Lynne Rienner Publishers, Boulder, Colorado. Byerlee, D. and Lopez-Pereira, M. (1994) Technical Change in Maize: a Global Perspective. Economics Working Paper No. 94–02. CIMMYT, Mexico DF. Cardwell, K.F., Schulthess, F., Ndemah, R. and Ngoko, Z. (1997) A systems approach to assess crop health and maize yield losses from pests and diseases in Cameroon. Agriculture, Ecosystems and Environment.

173

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter

174

References

Carson, M.L. (1995) A new gene in maize conferring the ‘chlorotic halo’ reaction to infection by Exserohilum turcicum. Plant Disease 79, 717–720. Carter S.E., Fresco, L.O. and Jones, P.G. with Fairbairn, J.N. (1992) An Atlas of Cassava in Africa: Historical, Agro-ecological and Demographic Aspects of Crop Distribution. CIAT, Cali, Colombia. Casas, A.M., Kononowicz, A.K., Bressan, R.A. and Hasegawa, P.M. (1995) Cereal transformation through particle bombardment. Plant Breeding Rev 13, 235–264. Ceccarelli, S. (1989) Wide adaptation: how wide? Euphytica 40, 197–205. CGIAR (1998) CGIAR 1997 Financial Report. CGIAR, Washington, DC, 33 pp. CGIAR (1998) Report of the 13th Meeting of the CGIAR Finance Committee. CGIAR Secretariat, Washington, DC, 34 pp. CGIAR (2000) CGIAR Systemwide Program on Participatory Research and Gender Analysis for Technology Development and Institutional Innovation. Biotechnology-assisted Participatory Plant Breeding: Complement or Contradiction? Working Document No. 4. CIAT, Cali, Colombia. CGIAR (2000) Systemwide Review of Plant Breeding Methodologies in the CGIAR. CGIAR Secretariat, Washington, DC. CGIAR (2000) Charting the CGIAR’s Future – Reshaping the CGIAR’s Organization. International Centers Week 2000. Washington, DC. CGIAR (2000) Charting the CGIAR’s Future – A New Vision for 2010. IAEG Study: CGIARs Impact on Germplasm Improvement. Washington, DC. Chang, R.Y. and Peterson, P.A. (1995) Genetic control of resistance to Bipolaris maydis: one gene or two genes. Journal of Heredity 86, 94–97. Chapman, J. and White, J.C.N. (1997) World Vision’s experience with seed supply during emergency and resettlement programs in Mozambique and Angola; Implications for the future. Invited paper, presented at: Enhancing research impact through improved seed supply: Options for strengthening national and regional seed supply systems, 10–14 March 1997. Workshop sponsored by ICRISAT, ICARDA, IITA and GTZ. ICRISAT, Bulawayo, Zimbabwe. Chapman, J., White, J. and Nankam, C. (1997) World Vision’s experience with seed supply during emergency and resettlement programs in Mozambique and Angola: implications for the future. In: Enhancing research impact through improved seed quality: options for strengthening national and regional seed supply systems. Proceedings of a workshop sponsored by ICRISAT, ICARDA, IITA and GTZ in Harare, Zimbabwe, March 10–14, 1997. Chavarriaga-Aguirre, P., Maya, M.M., Thoeme, J., Duque, M.C., Iglesias, C.I., Bonierbale, M.W., Kresovich, S. and Kochert, G. (1998) Using microsatellites, isozymes and AFLPs to evaluate genetic diversity and redundancy in the cassava core collection and to assess the usefulness of DNA-based markers to maintain germplasm collections. Molecular Breeding 5, 263–273. Chittenden, L.M., Schertz, K.F., Lin, Y.R., Wing, R.A. and Paterson, A.H. (1994) Detailed RFLP map of Sorghum bicolour × S. propinquum, suitable for high-density mapping, suggests ancestral duplication of sorghum chromosomes or chromosomal segments. Theoretical and Applied Genetics 87, 925–933. Cho, Y.G., McCouch, S.R., Kuiper, M., Kang, M.R., Pot, J., Groenen, J.T.M. and Eun, M.Y. (1998) Integrated map of AFLP, SSLP and RFLP markers using a recombinant inbred population of rice (Oryza sativa L.). Theoretical and Applied Genetics 97, 370–380. Chrispeels, M.J. and Sadava, D.E. (1994) Plants, Genes and Agriculture. Jones & Barlett, London, 478 pp. Christou, P., Ford, T.L. and Kofron, M. (1991) Production of transgenic rice (Oryza sativa L.) plants from agronomically important indica and japonica varieties via electric discharge particle acceleration of exogenous DNA into immature zygotic embryos. Bio/technology 9, 957–962.

174

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter

175

References

CIAT (1998) Saturation of the genetic map of cassava with PCR-based markers and the use of the genetic map in the improvement of cassava. Progress report to the Rockefeller Foundation. CIAT, Cali, Colombia. CIAT/IITA (1999) Mapping of genes for resistance to ACMV in cassava. Progress report to the Rockefeller Foundation. CIAT/IITA, Cali, Colombia, and Ibadan, Nigeria. CIMMYT (1988) Maize Production Regions in the Developing Countries. CIMMYT, El Batan, Mexico. CIMMYT (1990) 1989/90 CIMMYT World Maize Facts and Trends: Realizing the Potential of Maize in Sub-Saharan Africa. CIMMYT, Mexico, DF. CIMMYT (1994) CIMMYT in 1993: Helping the poor through innovative agricultural research. CIMMYT, Mexico, DF. CIMMYT (1994) Maize Research for Stress Environments: Proceedings of the Fourth Eastern and Southern Africa Regional Maize Conference, held at Harare, Zimbabwe, 28 March – 1 April 1994, CIMMYT, Mexico DF. CIMMYT (1996) Annual Research Report of CIMMYT-Zimbabwe: November 1994 to October 1995. CIMMYT-Zimbabwe, 100 pp. CIMMYT (1998) Change for the Better: CIMMYT 1998 Annual Report. CIMMYT, Mexico DF, 28 pp. CIMMYT (1999) CIMMYT 1997/98 World Maize Facts and Trends; Maize Production in DroughtStressed Environments: Technical Options and Research Resource Allocation, Heisey, P.W. and Edmeades, G.O. CIMMYT, Mexico D.F., 68 pp. CIMMYT (2000) Innovative and Integrated Approaches to Improve the Tolerance of Maize to Water-Limited Environments. Proposal Document. The International Maize and Wheat Improvement Center (CIMMYT), Mexico DF, 28 pp. CIMMYT (2000) Proceedings of an international workshop on molecular approaches for the genetic improvement of cereals for stable production in water-limited environments. CIMMYT, Mexico, DF. In press. Cisse, N., Ndiaye, M., Thiaw, S. and Hall, A.E. (1995) Registration of ‘Mouride’ cowpea. Crop Science 35, 1215–1216. Cisse, N., Ndiaye, M., Thiaw, S. and Hall, A.E. (1997) Registration of ‘Melakh’ cowpea. Crop Science 37, 1978. Coe, E.H., Neuffer, M.G. and Hoisington, D.A. (1988) The genetics of corn. In: Sprague, G.F. and Dudley, J.A. (eds) Corn and Corn Improvement. Madison, Wisconsin, pp. 81–258. Cohen, J. (1998) Biotechnology for African Crops. Study Commissioned by the Rockefeller Foundation, ISNAR, The Hague. Collier, P., Elbadawi, I. and Sambanis, N. (2000) Why are there so many civil wars in Africa? Prevention of future conflicts and promotion of inter-group cooperation. Paper prepared for the UNECA Ad Hoc Experts Group Meeting on ‘The Economics of Civil Conflicts in Africa’, Addis Ababa, Ethiopia, April 7–8, 2000. World Bank. Conway, G. (1997) The Doubly Green Revolution. Penguin Books, London. Coulibaly, O., Vitale, J.D. and Sander, J.H. (1998) Expected effects of devaluation on cereal production in the Sudanian region of Mali. Systems 57, 489–503. Council on Scientific and Industrial Research (1966) The Wealth of India, Vol. 8. Publications and Information Directorate, CSIR, New Delhi. Craig, J. and Odvody, G.N. (1992) Current status of sorghum downy mildew control. In: Milliano, W.A.J. et al. (eds) Sorghum and Millet Diseases. ICRISAT, Andra Pradesh, India, pp. 213–219. Cromwell, E. (1996) Governments, Farmers and Seed in a Changing Africa. CAB International, Wallingford, UK.

175

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter

176

References

Crouch, J.H., Vuylsteke, D. and Ortiz, R. (1998) Perspectives on the application of biotechnology to assist the genetic enhancement of plantain and banana (Musa spp.). Electronic J. Biotech. April 15, 1998. http://ejb.ucv.cl/content/vol1/issue1/full/2/index.html#90 Crow, J.F. (1998) Anecdotal, historical and critical commentaries on genetics. Genetics 148, 923–928. Dahlberg, J.A., Hash, C.T., Kresovich, S., Maunder, B. and Gilbert, M. (1996) Sorghum and pearl millet genetic resources utilization. Proceedings of the International Conference on Genetic Improvement of Sorghum and Pearl Millet. Meeting held in Lubbock, Texas, September 22–27 1997. INTSORMIL/ICRISAT, pp. 42–54. Daily Nation (2000) KARI Launches first GM Crop. Article by staff reporter Zipporah Mussah, p. 4, August 19, 2000. Daily Nation, Nairobi, Kenya. Dale, J.L. (1987) Banana bunchy top: an economically important tropical plant virus disease. Advances in Virus Research 33, 301–325. David C. and Otsuka, K. (1994) Modern Rice Technology and Income Distribution in Asia. Lynn Riener, Boulder, Colorado. David, S. and Sperling, L. (1999) Improving technology delivery mechanisms: lessons from research in eastern and central Africa. Agricultural and Human Values 16, 381–388. David, S., Kasozi, S. and Wortmann, C. (1997) An Investigation of Alternative Bean Seed Marketing Channels in Uganda. Occasional Publications Series, No. 19. CIAT, Cali, Colombia, 16 pp. De Boef, W., Amanor, K., Wellard, K. and Bebbington, A. (1993) Cultivating Knowledge: Genetic Diversity, Farmer Experimentation and Crop Research. Intermediate Technology Publications, London, 206 pp. De Leon, C. and Pandey, S. (1989) Improvement of resistance to ear and stalk rots and agronomic traits in tropical maize gene pools. Crop Science 29, 12–17. Debrah, S.K. (2000) African fertilizer situation and outlook: challenges, opportunities and implications. Paper presented at the 6th Annual International Conference of the Arab Fertilizer Association, 31 January to 2 February 2000, Cairo, Egypt. Dembele, P., Sogoba, J. and Darra, J. (1997) Rapport sur resultats tests sorgho resistant au striga. WV International, 7 pp. Denic, M. (1996) Simultaneous selection for earliness and resistance to downy mildew and streak virus in maize. pp. 219–225. In: Ransom et al. (eds) Maize Productivity Gains through Research and Technology Dissemination. Proceedings of the 5th Eastern and Southern Africa Regional Maize Conference 3–7 June. CIMMYT, Harare, Zimbabwe. Derera, J., Giga, D.P. and Pixley, K.V. (2000) Inheritance of maize weevil resistance in maize hybrids among maize lines from southern Africa, Mexico and CIMMYT-Zimbabwe. In: Maize Production Technologies for the Future: Challenges and Opportunties. Proceedings of the 6th Eastern and Southern Africa Regional Maize Conference held in Addis Ababa, Ethiopia, 21–25 September, 1998. CIMMYT, Harare, Zimbabwe. Desai, B.B., Kotecha, P.M. and Salunkhe, D.K. (1997) Seed Handbook. Marcel Dekker, New York, 627 pp. Devi, P., Zhong, H. and Sticklen, M.B. (2000) In vitro morphogenesis of pearl millet (Pennisetum glaucum (L.) R.Br.): efficient production of multiple shoots and inflorescences from shoot apices. Plant Cell Reports 19, 546–550. Devos, K.M., Tittaway, T.S., Busso, C.S., Gale, M.D., Whitcombe, J.R. and Hash, C.T. (1995) Molecular tools for the pearl millet nuclear genome. In: Sorghum and Millets Newsletter 36, 64–66. DeVries, J.D. (1997) NGOs, scientists and the poor: competitors, combatants or collaborators. Australian Development Studies Network. Development Bulletin 44, 68–70. DeVries, J.D. (1999) Evaluation report of the World Vision Burundi Agricultural Recovery Program. World Vision, Bujumbura, 26 pp.

176

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter

177

References

DeVries, J.D. and Chapman, J. (1996) Striga-resistant sorghum initiative. Interim report no. 1 to USAID. World Vision International, Washington, DC. 15 pp. DeVries, J.D. and Fumo, E. (1995) Maize varietal preferences and constraints to production in central Mozambique. In: Jewell, D.C., Waddington, S.R., Ransom, J.K. and Pixley, K.V. (eds) Maize Research for Stress Environments. Proceedings of the Fourth Eastern and Southern Africa Regional Maize Conference held at Harare, Zimbabwe, 28 March – 1 April, 1994. CIMMYT, Harare, p. 306. DeVries, J.D. and Ochieng, J.A.W. (eds) (1998) Advances in Striga Research in Kenya: Proceedings of a Workshop held in Kisumu on 4–5 December 1997. KARI, Nairobi, Kenya, 141 pp. DeVries, J.D. and Olufowote, J. (1997) The role of NGOs in crop improvement and seed multiplication. In: Enhancing Research Impact through Improved Seed Quality: Options of Strengthening National and Regional Seed Supply Systems. Proceedings of a workshop sponsored by ICRISAT, ICARDA, IITA and GTZ in Harare, Zimbabwe, March 10–14, 1997. De Wet, J.M.J., Harlan, J.R. and Price, E.G. (1970) Origin of variability in the Spontanea complex of Sorghum bicolor. American Journal of Botany 57, 704–707. Dhed’a, D., Dumortier, F., Panis, B., Vuylsteke, D. and Langhe, E. De (1991) Plant regeneration in cell suspension cultures of the cooking banana cv. ‘Bluggoe’ (Musa spp, ABB group). Fruits 46, 125–135. Diekmann, M. and Putter, C.A.J. (1996) FAO/IPGRI Technical Guidelines for the Safe Movement of Germplasm. No. 15. Musa. 2nd edn. FAO, Rome, Italy; IPGRI, Rome, Italy. Dillé, J. (1997) World Wide List of Rice Biotechnology Projects. A publication of the Rice Biotechnology Quarterly, Dept. of Biology, Winthrop University, Rock Hill, South Carolina. Dively, G.P. and Coop, L. (1993) Millet Loss Assessment Project, Mali. 190. USAID, Washington, DC, 29 pp. Dixon, A.G.O. (1999) IITA Working Paper: Cassava Germplasm Development in Africa: Past, Present and Future. IITA, Ibadan, Nigeria. Dixon, A., Asiedu, R., Wendt, J. and Mahungu, N. (1996) Development and improvement of broad-based populations. In: Cassava Productivity in the Lowlands and Mid-altitude Agroecologies of Sub-Saharan Africa. Annual Report. IITA, Ibadan, Nigeria, pp. 6–9. Dover, M.J. and Talbot, L.M. (1987) To Feed the Earth: Agro-ecology for Sustainable Development. World Resources Institute, Washington, DC. Dudley, J.W. (1993) Molecular markers in plant improvement: manipulation of genes affecting quantitative trait. Crop Science 33, 660–668. Duvick, D.N. (1992) Genetic contributions to advances in yield of US maize. Maydica 37, 69–79. Eastwell, K.C., Keifer, M.C. and Bruening, G. (1983) Immunity of cowpeas to cowpea mosaic virus. In: Goldberg, R.B. (ed.) Plant Mol. Biol. UCLA Symposia on Molecular and Cell Biology Alan R. Liss, New York, pp. 201–211. Eathington, S.R., Dudley, J.W. and Rufener II, G.K. (1997) Marker effects estimated from testcrosses of early and late generations of inbreeding in maize. Crop Science 37, 1679–1685. Edmeades, G.O., Chapman, S.C., Bolanos, J., Banziger, M. and Lafitte, H.R. (1994) Recent evaluations of progress in selection for drought tolerance in tropical maize. In: Jewell, D.C., Waddington, S.R., Ransom, J.K. and Pixley, K.V. (eds) Maize Research for Stress Environments. Proceedings of the Fourth Eastern and Southern Africa Regional Maize Conference, Harare, Zimbabwe, 28 March – 1 April, 1994, pp. 94–100. Ehlers, J.D. and Hall, A.E. (1997) Cowpea (Vigna unguiculata L. Walp.). Field Crops Research 53, 187–204. Eicher, C.K. (1990) Africa’s Food Battles. In: Eicher, C.K. and Staatz, J.M. (eds) Agricultural Development in the Third World. Johns Hopkins University Press, Baltimore, Maryland, pp. 503–530.

177

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter

178

References

Ejeta, G. (1998) Hybrid seed experience in Sudan. Paper presented at Regional Hybrid Sorghum and Pearl Millet Seed Workshop, held in Niamey, Niger, September 28 – October 2, 1998. Ejeta, G., Mohammed, A., Rich, P., Melake-Berhan, A., Housley, T.L. and Hess, D.E. (2000) Selection for specific mechanisms of resistance to Striga in sorghum. In: Haussman, B.I.G., Hess, D.E., Koyama, M.L., Grivet, L., Rattunde, H.F.W. and Geiger, H.H. (eds) Breeding for Striga Resistance in Cereals. Proceedings of a Workshop held at IITA, Ibadan, Nigeria, from 18–20 August 1999. Margraf Verlag, Weikersheim, Germany, pp. 29–37. Ekanayake, I. (1996) Investigations on the induction of flowering in cassava. In: Cassava productivity in the lowlands and mid-altitude agroecologies of sub-Saharan Africa. Annual Report, IITA, Ibadan, Nigeria, p. 32. Elwinger, G.F., Johnson, M.W., Hill, R.R. and Ayers, J.E. (1990) Inheritance of resistance to Gray Leaf Spot in Corn. Crop Science 30, 350–358. Emechebe, A.M. and Florini, D.A. (1997) Shoot and pod diseases of cowpea induced by fungi and bacteria. In: Singh, B.B., Mohan Raj, D.R., Dashiell, K.E. and Jackai, L.E.N. (eds) Advances in Cowpea Research. Copublication of International Institute of Tropical Agriculture (IITA) and Japan International Research Center for Agricultural Sciences (JIRCAS). IITA, Ibadan, Nigeria, pp. 176–192. Emechebe, A.M. and Shoyinka, S.A. (1985) Fungal and bacterial diseases of cowpeas in Africa. In: Singh, S.R. and Rachie, K.O. (eds) Cowpea Research, Production and Utilization. John Wiley & Sons, Chichester, UK, pp. 173–192. Erbisch, F.H. and Maredia, K.M. (1998) Intellectual Property Rights in Agricultural Biotechnology. Biotechnology in Agriculture Series, No. 20. CAB International, Wallingford, UK. Falconer, D.S. (1989) Introduction to Quantitative Genetics. Longman Group, London, UK, pp. 54–61. FAO (1998) FAO agricultural statistics page on the World-wide Web: www.fao.org FAO (1998–2000) www.fao.org. FAOSTAT Database. Internet database. http://apps.fao.org/ lim500 FAO (1999) www.fao.org. Internet Database. FAO (2000) www.fao.org. Internet Database. FAO/ICRISAT (1996) The World Sorghum and Millet Economies. FAO/ICRISAT, 68 pp. FAO/Zimbabwe MOA (1998) African Regional Workshop on Farmer Field Schools for IPM. Meeting Report. FAO/Zimbabwe MOA, Harare, 35 pp. Fatokun, C.A., Perrino, P. and Ng, N.Q. (1997) Wide crossing in African Vigna species. In: Singh, B.B., Mohan Raj, D.R., Dashiell, K.E. and Jackai, L.E.N. (eds) Advances in Cowpea Research. Copublication of International Institute of Tropical Agriculture (IITA) and Japan International Research Center for Agricultural Sciences (JIRCAS). IITA, Ibadan, Nigeria. pp. 50–57. Fauquet, C.M., Huet, H., Ong, C.A., Sivamani, E., Chen, L., Viegas, P., Marmey, V.P., Wang, P., Daud, M., de Kochko, A. and Beachy, R.N. (1997) Control of the rice tungro disease by genetic engineering is now a reality! In: Abstracts, General Meeting of the International Programme of Rice Biotechnology, Malacca, p. 59. Fauré, S., Noyer, J.L., Horry, J.P., Bakry, F., Lanaud, C. and González de León, D. (1993) A molecular marker-based linkage map of diploid bananas (Musa acuminata). Theoretical and Applied Genetics 87, 517–526. Fehr, W.R. (1987) Principles of Cultivar Development. McGraw-Hill, New York, pp. 120–134. Fischer, R.A. (1993) The sustainability debate and wheat science in Australia, developing countries and CIMMYT. Paper presented to the 8th Regional Wheat Workshop for Eastern, Central and Southern Africa, Kampala, Uganda, June 6–10, 1993. Flavel, R. (1999) Biotechnology for Developing-Country Agriculture: Problems and Opportunities. Biotechnology and Food and Nutrition Needs. Focus 2. Brief 2 of 10. October 1999. International Food Policy Research Institute (IFPRI), Washington, DC.

178

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter

179

References

Fliedel, G. and Aboubacar, A. (1998) Overview of sorghum and millet food uses. Paper presented at Regional Hybrid Sorghum and Pearl Millet Seed Workshop, held in Niamey, Niger, September 28 – October 2 1998. Flight, C. (1976) The Kintamp culture and its place in the economic prehistory of West Africa. In: Harlan, J.R., de Wet, J.M.J. and Stemler, A.B.L. (eds) Origins of African Plant Domestication. Mouton, The Hague, Netherlands, pp. 212–221. Frankel, F.R. (1971) India’s Green Revolution: Economic Gains and Political Costs. Princeton University Press, Princeton, New Jersey. Fredricksen, R.A. (1986) Compendium of Sorghum Diseases. The American Phytopathological Society, St Paul, Minnesota. Fregene, M., Akano, A., Gedil, M. and Guitierrez, J. (1996) Final Progress Report to the Rockefeller Foundation on the Molecular Mapping of Genes Conferring Resistance to the Cassava Mosaic Disease (CMD) in African Cassava Germplasm. IITA/CIAT, Ibadan, Nigeria. Frison, E.A. and Sharrock, S.L. (1998) Banana Streak Virus: a Unique Virus–Musa Interaction? Proceedings of a workshop of the PROMusa virology working group held in Montpellier, France, 19–21 January, 1998. IPGRI, Rome, Italy; INIBAP, Montpellier, France. Frison, E.A., Orjeda, G. and Sharrock, S.L. (eds) (1997) PROMUSA: a Global Programme for Musa Improvement. Proceedings of a meeting held in Gosier, Guadeloupe, March 5 and 9, 1997. International Network for the Improvement of Banana and Plantain, Montpellier, France, and The World Bank, Washington, DC, USA. Frison, E.A., Gold, C.S., Karamura, E.B. and Sikora, R.A. (eds) (1999) Mobilizing IPM for Sustainable Banana Production in Africa. Proceedings of a workshop on banana IPM held in Nelspruit, South Africa, 23–28 November 1998. INIBAP, Montpellier, France. Frost, H.M. (1995) Striga Research and Survey in Kenya. National Agricultural Research Project, KARI/ODA Crop Protection Project. Final report. Nairobi, Kenya, 61 pp. Fujimoto, H., Itoh, K., Yamamoto, M., Kyozuka, J. and Shimamoto, K. (1993) Insect resistant rice generated by introduction of a modified δ-endotoxin gene of Bacillus thuringiensis. Bio/Technology 11, 1151–1155. Galiba, M. (1983) Inheritance of resistance to sooty stripe disease. Sorghum Newsletter 26, 120. Gerhart, J. (1975) The Diffusion of Hybrid Maize in Western Kenya. CIMMYT, Mexico, DF. Ghareyazie, B., Alinia, F., Menguito, C.A., Rubia, L.G., De Palma, J.M., Liwanag, E.A., Cohen, M.B., Khush, G.S. and Bennett, J. (1997) Enhanced resistance to two stem borers in an aromatic rice containing a synthetic CryIA(b) gene. Molecular Breeding 3, 401–404. Ghesquiere, A., Albar, L., Lorieux, M., Ahmadi, N., Fargette, D., Huang, N., McCouch, S.R. and Nottenghem, J.L. (1997) A major QTL for RYMV maps to a cluster of blast resistance genes on chromosome 12. Phytopathology 87, 1243–1256. Gold, C., Vuylsteke, D. and Kaggundu, A. (1998) Screening of East African highland banana for weevil response. In: Project 7: Improving Plantain- and Banana-based Systems. Annual Report 1998. International Institute of Tropical Agriculture, Ibadan, Nigeria, p. 45. Gomez, F. and Chantereau, J. (1997) Breeding photoperiod sensitive sorghums. In: INTSORMIL/ICRISAT, 1997. Proceedings of the International Conference on Genetic Improvement of Sorghum and Pearl Millet. Meeting held in Lubbock, Texas, September 22–27 1997. INTSORMIL/ICRISAT, pp. 66–71. Gordon-Kamm, W.J., Spencer, T.M., Magnano, M.L., Adams, T.R., Daines, R.J., Start, W.G., Obrien, J.V., Chambers, S.A., Adams, W.R. and Willets, N.G. (1990) Transformation of maize cells and regeneration of fertile transgenic plants. Plant Cell 2, 603–618. Griffin, K. (1974) The Political Economy of Agrarian Change: An Essay on the Green Revolution. Harvard University Press, Cambridge. Griliches, Z. (1957) Hybrid corn: an exploration in the economics of technological change. Econometrica 25, 501–522.

179

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter

180

References

Grimanelli, C. (1998) Ensuring equity in the access to hybrid vigor: introducing apomixis in maize and other crops. In: Proceedings of the Sixth Eastern and Southern Africa Regional Maize Conference, held in Addis Ababa, 21–25 September, 1998. EARO, Ethiopia and CIMMYT. Grossniklaus U., Koltunow, A.M., van Lookeren, M. and Campagne, M.M. (1998) A bright future for apomixis. Trends in Plant Science 3, 415–416. Hahn, S.K., Terry, E.R., Leuschner, K., Akobundu, I.O., Okali, C. and Lal, R. (1979) Cassava Improvement in Africa. Reprint from Field Crops Research 2, 193–226. Hahn, S.K., Howland, A.K. and Terry, E.R. (1980) Correlated resistance of cassava to mosaic and bacterial blight diseases. Euphytica 29, 305–311. Hall, A.E., Singh, B.B. and Ehlers, J.D. (1997) Cowpea breeding. Plant Breeding Reviews 15, 21–274. Hampton, R.O., Thottappily, G. and Rossel, H.W. (1997) Viral diseases of cowpea and their control by resistance-conferring genes. In: Singh, B.B., Mohan Raj, D.R., Dashiell, K.E. and Jackai, L.E.N. (eds) Advances in Cowpea Research. Copublication of International Institute of Tropical Agriculture (IITA) and Japan International Research Center for Agricultural Sciences (JIRCAS). IITA, Ibadan, Nigeria, pp. 159–175. Hanna, W.W. (1992) Utilization of germplasm from wild species. In: Desertified Grasslands. Academic Press, London, pp. 251–257. Harlan, J.R. and de Wet, J.M.J. (1972) A simplified classification of cultivated sorghum. Crop Science 12, 172–176. Hartman, J., Vuylsteke, D., Kangire, A. and Makumbi, D. (1998) Evaluation and genetic analysis of Fusarium wilt resistance. In: Project 7: Improving Plantain- and Banana-based Systems. Annual Report 1998. International Institute of Tropical Agriculture, Ibadan, Nigeria, p. 44. Hartman, J., Vuylsteke, D., Talengera, D. and Makumbi, D. (1998) Breeding at ESARC (Uganda). In: Project 7: Improving Plantain- and Banana-based Systems. Annual Report 1998. International Institute of Tropical Agriculture, Ibadan, Nigeria, p. 48. Hartman, J., Vuylsteke, D., Ferris, S. and Makumbi, D. (1998) A survey of farmers practices in preparing plantain planting material in southern Cameroon. In: Project 7: Improving Plantain- and Banana-based Systems. Annual Report 1998. International Institute of Tropical Agriculture, Ibadan, Nigeria, p. 42. Hash, C.T., Witcombe, J.R., Thakur, R.P., Bhatnagar, S.K., Singh, S.D. and Wilson, J.P. (1997) Breeding for pearl millet disease resistance. In: INTSORMIL/ICRISAT. Proceedings of the International Conference on Genetic Improvement of Sorghum and Pearl Millet. Meeting held in Lubbock, Texas, September 22–27 1997, pp. 337–373. Hassan, R.M. (1998) Maize Technology Development and Transfer. A GIS Application for Research Planning in Kenya. CIMMYT/KARI/CAB International, University Press, Cambridge. Haugerud, A. and Collinson, M.P. (1990) Plants, genes and people: improving the relevance of plant breeding in Africa. Experimental Agriculture 26, 341–362. Hauser, S., Tschienkoua, M., Madong, B., Nyobe, T. and Dibog, L. (1998) A survey of farmers practices in preparing plantain planting material in southern Cameroon. In: Project 7: Improving Plantain- and Banana-based Systems. Annual Report 1998. International Institute of Tropical Agriculture, Ibadan, Nigeria, p. 4. Haussmann, B.I.G., Hess, D.E., Gunter Welz, H. and Geiger, H.H. (2000) Improved methodologies for breeding Striga-resistant sorghums. Field Crops Research 66, 195–211. Hayakawa, T., Zhu, Y., Itoh, K., Kimura, Y., Izawa, T., Shimamoto, K. and Toriyama, S. (1992) Genetically engineered rice resistant to rice stripe virus, an insect-transmitted virus. Proceedings of the National Academy of Sciences USA 89, 9865–9869. Heisey, P.W. and Mwangi, W. (1996) Fertilizer Use and Maize Production in Sub-Saharan Africa. CIMMYT Economics Working Paper No. 96-01. CIMMYT, Mexico DF, 34 pp.

180

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter

181

References

Heisey, P.W., Morris, M.L., Byerlee, D. and Lopez-Pereira, M.A. (1998) Economics of hybrid maize adoption. In: Morris, M.L. (ed.) Maize Seed Industries in Developing Countries. Lynne Rienner Publishers, Boulder, Colorado, pp. 143–158. Henry, G. and Gottret, V. (1996) Global Cassava Trends: Reassessing the Crop’s Future. Working Document No. 157. CIAT, Cali, Columbia. Henzell, R.G. and Hare, B.W. (1996) Sorghum breeding in Australia: Public and private endeavours. In: Proceedings of the Third Australian Conference, 20–22 February 1996, Tamworth, NSW. Australian Institute of Agricultural Science, Melbourne, Occasional Publication No. 93, pp. 159–171. Henzell, R.G., Peterson, G.C., Teetes, G.L., Franzmann, B.A., Sharma, H.C., Youm, O., Ratnadass, A., Toure, A., Raab, J. and Ajayi, O. (1997) Breeding for resistance to panicle pests of sorghum and pearl millet. In: INTSORMIL/ICRSAT, 1997. Proceedings of the International Conference on Genetic Improvement of Sorghum and Pearl Millet. Meeting held in Lubbock, Texas, September 22–27 1997, pp. 255–280. Herdt, R.W. (1991) Research priorities for rice biotechnology. In: Khush, G.S. and Toenniessen, G.H. (eds) Rice Biotechnology. CAB International, Wallingford, UK, pp. 19–54. Herdt, R.W. and Capule, C. (1983) Adoption, Spread, and Production Impact of Modern Rice Varieties in Asia. IRRI, Los Baños, Philippines. Hildebrand, P.E. (1981) Combining disciplines in rapid appraisal: the sondeo approach. Agricultural Administration 8, 423–432. Hildebrand, P.E. and Poey, F. (1985) On-farm Agronomic Trials in Farming Systems Research and Extension. Lynne Rienner Publishers, Boulder, Colorado. Hittalmani, S., Kumar, G.K., Kulkarni, N. and Shashidhar, H.E. (1999) DNA markers assist in reducing the number of generations of backcrosses in breeding for blast resistance in rice. Paper presented at the General meeting of the International Program on Rice Biotechnology, held on September 20–24, 1999 in Phuket, Thailand. Meeting sponsored by the Rockefeller Foundation, New York. Hodson, D.P., Rodriguez, A., White, J.W., Corbett, J.D. and Banziger, M. (1999) Africa Maize Research Atlas (v. 2.0). CIMMYT. Mexico, DF., CD-ROM. Hoffman, M.P., Thurston, H.D. and Smith, M.E. (1993) Breeding for resistance to insects and plant nutrients. In: Callaway, M.B. and Francis, C.A. (eds) Crop Improvement for Sustainable Agriculture. University of Nebraska, Lincoln. Hoisington, D., Listman, G.M. and Morris, M.L. (1998) Varietal development: applied biotechnology. In: Morris, M.L. (ed.) Maize Seed Industries in Developing Countries. Lynne Rienner, London, pp. 13–35/77–102. Hoisington, D., Khairallah, M., Reeves, T., Ribaut, J.M., Skovmand, B., Taba, S. and Warburton, M. (1999) Plant genetic resources: what can they contribute toward increased crop productivity? Proceedings of the National Academy of Sciences USA 96, 5937–5943. Holden, S.T. and Shanmugarathan, N. (1994) Structural Adjustment, Production Subsidies and Sustainable Land Use. Dis. Pap. D-11/1994. Department of Economics and Social Sciences, Agricultural University of Norway. House, L.R. (1985) A Guide to Sorghum Breeding. ICRISAT, Patacheru, India. House, L.R. (1996) Inaugural Address. In: Proceedings of the International Conference on Genetic Improvement of Sorghum and Pearl Millet. September 23–27, 1996. Lubbock, Texas. House, L.R., Verma, B.N., Ejeta, G., Rana, B.S., Kapran, I., Obilana, A.B. and Reddy, B.V.S. (1997) Developing countries and potential of hybrid sorghum. In: INTSORMIL/ICRISAT, 1997. Proceedings of the International Conference on Genetic Improvement of Sorghum and Pearl Millet. Meeting held in Lubbock, Texas, September 22–27 1997. INTSORMIL/ICRISAT, pp. 84–96. Hughes, J.A. and Singh, B.B. (1998) Screening cowpea lines for multiple resistance. In: Integrated Management of Legume Pests and Diseases. IITA Annual Report, 1998.

181

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter

182

References

Hughes, J. and Tenkouano, A. (1998) BSV occurrence, epidemiology, and cultivar interactions. In: Improving Plantain and Banana-based Systems. IITA Annual Report, 1998. Ibrahim, O.E., Ahmed, A.T., Omer, M.E., Hamdoun, A.M., Babiker, A.E. and Boreng, P. (1995) Status of sorghum production, technology generation, transfer and adoption by farmers in the Sudan. In: Mukuru, S.Z., Ejeta, G. and Ibrahim, N. (eds) Sorghum and Millets Research in Eastern and Central Africa: Proceedings of a workshop organized to reestablish a sorghum and millets network in the region, 6–9 November 1995, Kampala, Uganda, pp. 157–167. ICRISAT (1992) Medium Term Plan, 1992. Monitoring and Evaluation. Pantancheru, India, pp. 75–80. ICRISAT (1992) International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) West African programs annual report 1991. B.P. 12404, Niamey, Niger. ICRISAT (1996) Improving the Unimprovable: Succeeding with Pearl Millet. ICRISAT, Patancheru, Andhra Pradesh. Idachaba, F.S. (1985) Priorities for Nigerian agriculture in the fifth national development plan, 1986–1990. Nigerian Institute of Social and Economic Research, Ibadan, Nigeria. IITA (1972) Annual Report of Root and Tuber Improvement Program. IITA, Ibadan, Nigeria. IITA (1994) Annual Report. IITA, Ibadan, Nigeria, p. 64. IITA (1995) Annual Report. IITA, Ibadan, Nigeria, p. 55. IITA (1998) Project 11: Cowpea–Cereals systems: Improvement in the Dry Savannas. Annual Report 1998. International Institute of Tropical Agriculture, Ibadan, Nigeria. Imanywoha, J. (1998) Improvement of maize variety 1p 16 in resistance to diseases and tolerance to low nitrogen. Project proposal, Dec. 1998. INIBAP (1993) Bananas, Plantains and INIBAP. Annual Report 1993 of The International Network for the Improvement of Banana and Plantain. Montpellier, France. INIBAP (1995) Annual Report of The International Network for the Improvement of Banana and Plantain. Montpellier, France. INIBAP (2000) Novel approaches to the improvement of banana production in Eastern Africa – the application of biotechnological methodologies. Project Proposal Document. INIBAP, Rome, Italy, 14 pp. Ininda, J. and Ochieng, J. (2000) Coordinated Ecosystem Breeding Project. 1st year Report. Kenya Agricultural Research Institute, Nairobi, Kenya. INTSORMIL/INRAN (1998) Traditional Seed Selection and Conservation Methods of Cereals and Legumes in Niger: Implications for an Informal Seed System. (B. Ouendeba., T. Abdoulaye, G. Ibro and K. Anand Kumar) Niamey, Niger. ISAAA (1997) Annual Report, 1996. Advancing Altruism in Africa. ISAAA, Ithaca, New York. ISAAA (2000) New Partnerships for Prosperity: Building Public/private Agri-biotech Networks for Resource Poor Farmers in Southeast Asia and Africa. Biennial Report 1997–1999. Washington, DC. Ishida, Y., Saito, H., Ohta, S., Hieie, Y., Komari, T. and Kumashiro, T. (1996) High efficiency transformation of maize mediated by Agrobacterium tumefaciens. Nature Biotechnology 14, 745–749. ISNAR (1998) Biotechnology of African Crops. Study Commissioned by the Rockefeller Foundation. ISNAR, IITA. Ito, O., O’Toole, J.C. and Hardy, B. (1999) Genetic improvement of Rice for Water-Limited Environments. Proceedings of a Workshop on Genetic Improvement of Rice for Water-Limited Environments, 1–3 December, 1998. International Rice Research Institute, Los Baños, Philippines. Jaffee, J. (1991) The Balance between Public and Private Sector Activities in Seed Supply Systems. The World Bank, Washington, DC. James, C. (1997a) Progressing public-private sector partnerships in international agricultural research and development. ISAAA Briefs No. 4. ISAAA, Ithaca, New York, 31 pp.

182

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter

183

References

James, C. (1997b) Global Status of Transgenic Crops in 1997. ISAAA Briefs No. 5. New York, 30 pp. James, C. (2000a) Global Status of Commercialized Transgenic Crops: 1999. ISAAA Briefs No. 17. ISAAA, Ithaca, New York, 65 pp. James, C. (2000b) Global review of transgenic crops in 1999. ISAAA, Briefs No. 5. ISAAA, Ithaca, New York, 31 pp. Jameson, J.D. (1953) Outbreaks and new records. Uganda. FAO Plant Protection Bulletin 1, 62. Janson, G. and Kapukha, P. (1995) Southern Sudan Agricultural Recovery Program Annual Report. Jarret, R.L., Bhat, K.V., Cregan, P., Ortiz, R. and Vuylsteke, D. (1994) Isolation of microsatellite DNA markers in Musa. InfoMusa 3, 3–4. Jeffers, D.P. and Chapman, S.C. (1994) Yield losses associated with Exserohilum turcicum and Puccinia sorghi in high disease incidence environments. In: Jewell, D.C., Waddington, S.R., Ransom, J.K. and Pixley, K.V. (eds) Maize Research for Stress Environments. Proceedings of the Fourth Eastern and Southern Africa Regional Maize Conference, Harare, Zimbabwe, 28 March – 1 April, 1994, pp. 157–159. Jefferson, R.A. and Bicknell, R. (1996) The potential impacts of apomixis: a molecular genetic approach. In: Sobra, B.W.S. (ed.) The Impact of Plant Molecular Genetics. Birkhäuser, Boston, pp. 87–101. Jensen, S. (1994) Genetic improvement of maize for drought tolerance. In: Jewell, D.C., Waddington, S.R., Ransom, J.K. and Pixley, K.V. (eds) Maize Research for Stress Environments. Proceedings of the Fourth Eastern and Southern Africa Regional Maize Conference, Harare, Zimbabwe, 28 March – 1 April, 1994, pp. 67–75. Johanson, A. and Ives, C. (2000) An Inventory of Agricultural Biotechnology for the Eastern and Central Africa Region. Institute of International Agriculture, Michigan, 59 pp. Jones. A.L. (ed.), Weltzein, E., Smith, M.E., Meitzner, L.S. and Sperling, L. (1999) Technical and Institutional Issues in Participatory Plant Breeding – from the Perspective of Formal Plant Breeding. A Global Analysis of Issues, Results, and Current Experience. CGIAR. Jones, W.O. (1959) Manioc in Africa. Standard University Press, Stanford, California, 315 pp. Kaemmer, D., Fischer, D., Jarret, R.L., Baurens, F.C., Grapin, A., Dambier, D., Noyer, J.L., Lanaud, C., Kahl, G. and Lagoda, P.J.L. (1997) Molecular breeding in the genus Musa: a strong case for STMS marker technology. Euphytica 96, 49–63. Kanampiu, F.K. (1998) Herbicide-resistant maize to control Striga infestations. In: DeVries, J.D. and Ochieng, J.A.W. (eds) Advances in Striga Research in Kenya. Proceedings of a workshop held in Kisumu, Kenya, 4–5 December 1995, 141 pp. Karamura, D.A. (1999) Numerical Taxonomic Studies of the East African Highland Bananas (Musa AAA-East Africa) in Uganda. PhD thesis, Department of Agricultural Botany, University of Reading. IPGRI, Reading. KARI (1998) Understanding the mechanisms of maize streak virus resistance of maize lines from Kenya and from eastern and southern Africa. Project proposal by the Kenya Agricultural Research Institute. KARI, Nairobi, Kenya, 46 pp. Kassam, A.H. and Kowal, J.M. (1975) Water use, energy balance and growth of gero millet at Samaru, Northern Nigeria. Agricultural Methods 15, 333–342. Kelly, A.F. and George, R.A.T. (1998) Encyclopaedia of Seed Production of World Crops. John Wiley & Sons, Chichester. Kezire, B.B., Asiimwe, P. and Kyetere, D. (2000) Agricultural biotechnology assessment in sub-Saharan Africa: Country-specific study – Uganda. Paper presented at the Regional Workshop on Building National Biotechnology Innovation Systems held in Mombasa, Kenya, December 6–8, 2000. Africa Centre for Technology Studies (ACTS), Nairobi, Kenya, 23 pp. Khush, A.G.S. (1990) Rice breeding: accomplishments and challenges. Plant Breeding Ab. 60, 461–469. Khush, G.S. and Toenniessen, G.H. (1991) Rice Biotechnology. CAB International, Wallingford, UK, 313 pp.

183

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter

184

References

Kim, S.K. (1994) Genetics of maize tolerance to Striga hermonthica. Crop Science 34, 900–907. Kim, S.K. and Brewbaker, J.L. (1976) Effect of Puccinia sorghi on yield and several agronomic traits of maize in Hawaii. Crop Science 16, 874–877. Kitch, L.W., Shade, R.E. and Murdock, L.L. (1991) Resistance to the cowpea weevil (Callosobruchus maculatus) larva in pods of cowpea (Vigna unguiculata). Entomologia Experimentalis Applicata 60, 183–192. Kitch, L.W., Bottenberg, H. and Wolfson, J.L. (1997) Indigenous knowledge and cowpea pest management in sub-Saharan Africa. In: Singh, B.B., Mohan Raj, D.R., Dashiell, K.E. and Jackai, L.E.N. (eds) Advances in Cowpea Research. Copublication of International Institute of Tropical Agriculture (IITA) and Japan International Research Center for Agricultural Sciences (JIRCAS). IITA, Ibadan, Nigeria, pp. 292–301. Kitch, L.W., Boukar, O., Endondo, C. and Murdock, L.L. (1998) Farmer Acceptability Criteria in Breeding Cowpea. Cambridge University Press, UK. Kling, J.G., Fajemisin, J.M., Badu-Apraki, B., Diallo, A., Menkir, A. and Melake-Berhan, A. (2000) Striga resistance breeding in maize. In: Haussman, B.I.G., Hess, D.E., Koyama, M.L., Grivet, L., Rattunde, H.F.W. and Geiger, H.H. (eds) Breeding for Striga Resistance in Cereals. Proceedings of a Workshop held at IITA, Ibadan, Nigeria, from 18–20 August 1999. Margraf Verlag, Weikersheim, Germany, pp. 103–118. Knapp, S.J. (1991) Using molecular markers to map multiple quantitative trait loci: models for backcross, recombinant inbred, and doubled haploid progeny. Theoretical Applications of Genetics 81, 333–338. Koo, B. and Wright, B.D. University of California. (1999) EPTD Discussion Paper No. 51. Dynamic Implications of Patenting for Crop Genetic Resources. Environment and Production Technology Division, International Food Policy Research Institute, Washington, DC. Kramer, K.J., Morgan, T.D., Throne, J.E., Dowell F.E., Bailey, M. and Howard, J.A. (2000) Transgenic avidin maize is resistant to storage insect pests. Nature Biotechnology 18, 670–674. Kumar, H. (1994) Field resistance in maize cultivars to stem borer Chilo partellus. Annals of Applied Biology 124, 333–339. Kumaravadivel, N. and Sree Rangasamy, S.R. (1994) Plant regeneration from sorghum anther cultures and field evaluation of progeny. Plant Cell Reports 13, 286–290. Kyetere, D.T., Kikafunda-Twine, J., Imanywoha, J.B. and Bigirwa, G. (1997) Cereals Programme, Annual Report, 1997 A & B. NARO, Kampala, Uganda. Lagoda, P.J.L., Noyer, J.L., Dambier, D., Baurens, F.C. and Lanaud, C. (1995) Abundance and distribution of SSR (simple sequence repeats) in the Musaceae family: Microsatellite markers to map the banana genome. In: Proceedings of the FAO/IAEA International Symposium on Induced Mutations and Molecular Techniques for Crop Improvement, Vienna, FAO/IAEA, pp. 287–295. Laker-Ojok, R. (2000) AT(Uganda)’s role in input distribution. Paper presented at a workshop on Development of Sustainable Seed Systems for Small-scale Farmers, held at Colline Hotel, Mukono, Uganda, 22–23 May, 2000. Lale, N.E.S. and Yusuf, B.A. (2000) Insect pests infesting stored pearl millet Pennisetum glaucum (L.) R.Br. in northeastern Nigeria and their damage potential. Cereal Research Communications 28, 181–186. Lambert, C. (1983) L’IRAT et amelioration du mil. Agronomie Tropicale 28, 78–88. Lassoudiere, A. (1974) La mopsaique dite ‘a tirets’ du bananier Poyo en Côte d’Ivoire. Fruits 29, 349–357. Lefevre, F. and Charrier, A. (1993) Heredity of seventeen isozyme loci in cassava (Manihot esculenta Crantz). Euphytica 66, 171–178. Legg, J.P. (1999) Emergence, spread and strategies for controlling the pandemic of cassava mosaic virus disease in east and central Africa. Crop Protection 18, 627–637.

184

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter

185

References

Legg, J.P., Whyte, J., Khizzah, B. and Ogwang, J. (1998) CGM/CMD interaction studies. In: Project 6. Integrated Management of Cassava Pests and Diseases. 1998 Annual Project Report. International Institute of Tropical Agriculture, Ibadan, Nigeria, pp. 8–9 Lele, U.J. (1989) Managing agricultural development in Africa. In: Eischer, C.K. and Staatz, J.M. (eds) Agricultural Development in the Third World, 2nd edn. Johns Hopkins University Press, London, pp. 531–539. Leuschner, K., Monyo, E.S., Chinhema, E., Tembo, E. and Martin, D. (2000) Pearl millet grain size and hardness in relation to resistance to Sitophilus oryzea (L.) (Coleoptera Curculionidae). African Crop Science Journal 8, 77–83. Li, H.Q., Sautter, C., Potrykus, I. and Puonti-Kaerlas, J. (1996) Genetic transformation of cassava (Manihot esculenta Crantz). Nature Biotechnology 14, 736–744. Lipton, M. and Longhurst, R. (1989) New Seeds and Poor People. Johns Hopkins University Press, Baltimore, Maryland. Liu, C.J., Whitcombe, J.R., Pittaway, T.S., Nash, M., Hash, C.T., Busso, C.S. and Gale, M.D. (1994) An RFLP-based genetic map of pearl millet. Theoret. Applied Genetics 89, 481–487. Lockhart, B.E.L. (1986) Purification and serology for a bacilliform virus associated with banana streak virus disease. Phytopathology 76, 995–999. Lockhart, B.E.L., Ndowora, T.C., Olszewski, N.E. and Dahal, G. (1998) Studies on integration of banana streak badnavirus sequences in Musa: Identification of episomally-expressible badnaviral integrants in genotypes. In: Frison, E.A. and Sharrock, S.L. (eds) Banana Streak Virus: a Unique Virus-Musa Interaction? Proceedings of a workshop of the PROMUSA Virology working group held in Montpellier, France, January 19–21, 1998. International Plant Genetic Resources Institute, Rome, Italy; International Network for the Improvement of Banana and Plantain, Montpellier, France, pp. 42–47. Lopez-Pereira, M.A. and Filippello, M.P. (1995) Emerging Roles of the Public and Private Sectors of Maize Seed Industries in the Developing World. CIMMYT Economics Program Working Paper 95–01. CIMMYT, Mexico, DF., 84 pp. Lubberstedt, T., Melchinger, A.E., Fahr, S.F., Klein, D., Dally, A. and Westhoff, P. (1998) QTL mapping in testcrosses of flint lines of Maize: III. Comparison across populations for forage traits. Crop Science 38, 1278–1289. Luo, M., Bilodeau, P., Koltunow, A., Dennis, E.S., Peacock, W.J. and Chaudbury, A.M. (1999) Genes controlling fertilization-independent seed development in Arabidopsis thaliana. Proceedings of the National Academy of Sciences USA 96, 296–301. Lynam, J. (1998) Evaluation Findings. Part 1. Crop-based Production System Projects. Cassava Evaluation Report. IITA, Ibadan, Nigeria. Mackill, D.J. and Bonman, J.M. (1992) Inheritance of blast resistance in near-isogenic lines of rice. Philippines. Magill, C.W., Boora, K., Sunitha Kumari, R., Osorio, J., Oh, B.J., Gowda, B., Chui, Y. and Fredricksen, R. (1997) Tagging sorghum genes for disease resistance: expectations and reality. In: INTSORMIL/CRISAT. Proceedings of the International Conference on Genetic Improvement of Sorghum and Pearl Millet. Meeting held in Lubbock, Texas, September 22–27 1997. INTSORMIL/ICRISAT, pp. 316–325. Malawi Government (1999) Ministry of Agriculture and Irrigation, Department of Agriculture Research and Technical Services. Rebuilding the Malawi Maize Pathology Project and Development of a Research Action Plan. Final Report, June 1999. Lilongwe, 47 pp. Mann, C. (1999) Starter Pack Scheme Assessment Report. Project evaluation document prepared for The Rockefeller Foundation, New York, 36pp. Mann, C.G. (1999) Kenya: biotechnology in Africa: why the controversy? In: Persley, G.J. and Lantin, M.M. (eds) Agricultural Biotechnology and the Poor. Proceedings of an International Conference. Washington, DC, 21–22 October 1999, pp. 109–114.

185

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter

186

References

Maredia M.K., Byerlee, D. and Pee, P. (2000) Impacts of food crop improvement research: evidence from sub-Saharan Africa. Food Policy 25, 531–559. Mashingaidze, K. (1994) Maize research and development. In: Rukini, M. and Eicher, C.K. (eds) Zimbabwe’s Agricultural Revolution. University of Zimbabwe Publications, Harare. Matlon, P. and Adesina, A. (1991) Prospects for sustainable growth in sorghum and millet productivity in West Africa. In: Vosti, S.A., Reardon, T., von Urff, W. and Witcover, J. (eds) Agricultural Sustainability, Growth and Poverty Alleviation: Issues and Policies. Proceedings of the Conference held from 23 to 27 September, 1991 in Feldafing, Germany, pp. 363–387. May, G., Afza, R., Mason, H., Wiecko, A., Novak, F. and Arntzen, C. (1995) Generation of transgenic banana (Musa acuminata) plants via Agrobacterium-mediated transformation. Bio/Technology 13, 486–492. McCarter, B. (2000) Can Biotechnology Bridge the Gap for Resource Poor Farmers? Occasional paper. Seed Co Ltd, Harare, Zimbabwe. McCouch, S.R., Chen XiuLi, Panaud, P., Temnykh, S., Xu YunBi, Cho YongGu, Huang Ning, Ishii, T. and Blair, M. (1997) Microsatellite marker development, mapping and applications in rice genetics and breeding. Plant Molecular Biology 35, 89–99. Mduruma, Z.O. (1999) Lessons, experiences and future challenges of community-based seed production in Tanzania. In: Maize Production Technology for the Future: Challenges and Opportunities: Proceedings of the sixth eastern and southern Africa regional maize conference, 21–25 September, 1998, Addis Ababa, Ethiopia. CIMMYT and EARO, pp. 150–154. Meikle, W.G. and Markham, R.H. (1998) Evaluating postharvest resistance to maize pests. In: Project 5: Integrated Management of Maize Pests and Diseases. Annual Report 1998. International Institute of Tropical Agriculture, Ibadan, Nigeria, p. 13. Melton, A., Ogle, W.L., Barnett, O.W. and Caldwell, J.D. (1987) Inheritance of resistance to viruses in cowpea. Phytopathology 77, 642. Merril-Sands, D. (1986) Farming systems research: Clarification of terms and concepts. Experimental Agriculture 22, 87–104. Miflin, B.J. (2000) Crop biotechnology. Where Now? Meeting report. Plant Physiology 123, 17–27. Minja, E.M. (2000) Management of the armoured bush cricket in Namibia and Zambia: Farmers’ methods. In: Minja, E.M. and van den Berg, J. (eds) Proceedings of the Workshop on Management of Sorghum and Pearl Millet Pests in the SADC Region, 10–13 February 1998, Matopos Research Station, Zimbabwe. ICRISAT, Bulawayo, Zimbabwe. Mlotshwa, S. (2000) The helper component-proteinase of cowpea aphid-borne mosaic virus. PhD dissertation, University of Zimbabwe, 111 pp. Mloza-Banda, H.R., Kapondamgaga, P.H. and Kaotcha, R.M. (1999) Interim Research Report of the Striga Research Project. Bunda College of Agriculture, Lilongwe, Malawi, 24 pp. Monti, L.M., Murdock, L.L. and Thottappilly, G. (1997) Opportunities for biotechnology in cowpea. In: Singh, B.B., Mohan Raj, D.R., Dashiell, K.E. and Jackai, L.E.N. (eds) Advances in Cowpea Research. Copublication of International Institute of Tropical Agriculture (IITA) and Japan International Research Center for Agricultural Sciences (JIRCAS). IITA, Ibadan, Nigeria, pp. 341–351. Moore Lappé, F., Collins, J. and Rosset, P. (1998) World Hunger: 12 Myths, 2nd edn. Grove Press/Earthscan. Morris, M.L. (1998a) Overview of the world maize economy. In: Morris, M.L. (ed.) Maize Seed Industries in Developing Countries. Lynne Rienner, London, pp. 13–35. Morris, M.L. (1998b) Maize in the developing world: waiting for a green revolution. In: Morris, M.L. (ed.) Maize Seed Industries in Developing Countries. Lynne Rienner, London. Mugo, S. (2000) Presentation of IRMA Project goals, objectives, and activities. In: Mugo, S., Poland, D., DeGroote, H. and Hoisington, D. (eds) Proceedings of the Stakeholders Meeting held at Panafric Hotel, Nairobi, Kenya. March 3 2000. IRMA Project Document No. 2.

186

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter

187

References

Muhhuku, F. (2000) Farmer Demand for Seed of Improved Varieties: Workshop on the development of sustainable seed systems for small-scale farmers. NARO, Mukono, Uganda, 22–23 May, 2000. Mukuru, S.Z. (1992) Breeding for grain mold resistance. In: de Milliano, W.A.J., Fredricksen, R.A. and Bengston, G.D. (eds) Sorghum and Millet Diseases: A Second World Review. ICRISAT, Patancheru, India, pp. 273–285 Mukuru, S.Z. (1993) Sorghum and millet in eastern Africa. In: Byth, D.E. (ed.) Sorghum and Millets Commodity and Research Environments. ICRISAT, Patancheru, Andhra Pradesh, India. Murdock, L.L., Shade, R.E., Kitch, L.W., Ntoukam, G., Lowenberg-DeBoer, J., Huesing, J.E., Moar, W., Chambliss, O.L., Endondo, C. and Wolfson, J.L. (1997) Postharvest storage of cowpea in sub-Saharan Africa. In: Singh, B.B., Mohan Rah, D.R., Dashiell, K.E. and Jackai, L.E.N. (eds) Advances in Cowpea Research. Copublication of International Institute of Tropical Agriculturee (IITA) and Japan International Research Center for Agricultural Sciences (JIRCAS). IITA, Ibadan, Nigeria, pp. 302–312. Mwangi, W. (1996) The Economics of Commercial Maize Seed Supply. Module 9 in CIMMYT Seed Manual. CIMMYT, Mexico, DF. Nankam, C., Sallah, A. and Nhunga, M. (1996) WV Angola Agricultural Recovery Program Technical Report of Activities (First Season, 1995–1996). World Vision International, Luanda, Angola. NAS (National Academy of Sciences) (1996) Lost Crops of Africa. Vol. 1, Grains. National Academy Press, Washington, DC. Ndiritu, C.G. (1999) Kenya: biotechnology in Africa: why the controversy? In: Persley, G.J. and Lantin, M.M. (eds) Agricultural Biotechnology and the Poor. Proceedings of an International Conference. Washington, DC, 21–22 October 1999, pp. 109–114. Ndjiondiop, M.N., Albar, L., Fargette, D., Fauquet, C. and Ghesquiere, A. (1999) The genetic basis of high resistance to rice yellow mottle virus (RYMV) in cultivars of two cultivated rice species. Plant Disease (in press). Ng, N.Q. (1995) Cowpea. In: Smartt, J. and Simmonds, N.W. (eds) Evolution of Crop Plants, 2nd edn. Longman, Harlow, UK, pp. 326–332. Nguyen, H.T., Xu, W., Rosenow, D.T., Mullet, J.E. and McIntyre, L. (1996) Use of biotechnology in sorghum breeding. In: Proceedings of the International Conference on Genetic Improvement of Sorghum and Pearl Millet. Meeting held in Lubbock, Texas, September 22–27 1997. INTSORMIL/ICRISAT, pp. 412–424. Ngwira, P. (1989) The status of maize diseases in Malawi. In: Gebrekidan, B. (ed.) Maize Improvement, Production and Protection in Eastern and Southern Africa. Proceedings of the Third Eastern and Southern Africa Regional Maize Workshop. Govt. of Kenya and CIMMYT, Nairobi and Kitale, Kenya, September 18–22, 1989, pp. 230–238. Ngwira, P.N., Pixley, K.P., DeVries, J.D. and Kanaventi, C.M. (1998) Major maize disease problems and farmer’s varietal preferences in Malawi. In: Proceedings of the Sixth Eastern and Southern Africa Regional Maize Conference, held in Addis Ababa, 21–25 Sept., 1998. Nhlane, W.G. (1990) Breeding flint maize hybrids (hard endosperm grain) in Malawi in response to smallholder processing needs. In: Gebrekidan, B. (ed.) Maize improvement, production and protection in Eastern and Southern Africa: Proceedings of the third eastern and southern Africa regional maize workshop. Nairobi, Kenya. Nichols, R.F.W. (1947) Breeding cassava for virus resistance. East African Agriculture Journal 12, 184–194. Nkama, I. and Malleshi, N.G. (1998) Production and nutritional quality of traditional Nigerian masa from mixtures of rice, pearl millet, cowpea and groundnut. Food and Nutrition Bulletin 19, 366–373.

187

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter

188

References

Norskog, C. (1995) Hybrid Seed Corn Enterprises: a Brief History, 1st edn. Maracom Corp., Willmar, Minnesota. Novak, F.J., Afza, R., van Duren, M., Perea-Dallos, M., Conger, B.V. and Xiaolang, T. (1989) Somatic embryogenesis and plant regeneration in suspension cultures of dessert (AA and AAA) and cooking (ABB) bananas (Musa spp.). Bio/Technology 7, 154–159. Nweke, F.I., Ugwu, B.O. and Dixon, A.G.O. (1992) The Spread and Performance of Improved Cassava Varieties in Nigeria: An assessment of Adoption. Collaborative Study of Cassava in Africa. Working paper no. 15. First Draft. Nweke, F.I., Poulson, R. and Strauss, J. (1994) Cassava production trends in Africa. In: Ofori, F. and Hahn, S.K. (eds) Tropical Roots Crops in a Developing Economy. Proceedings of the 9th Symposium of the International Society for Tropical Roots Crops, 20–26 October, 1991, Accra, Ghana. Govt of Ghana, pp. 311–321. Obilana, A.B., Monyo, E.S. and Gupta, S.C. (1996) Impact of genetic improvement in sorghum and pearl millet: developing country experiences. In: Proceedings of the International Conference on Genetic Improvement of Sorghum and Pearl Millet. Meeting held in Lubbock, Texas, September 22–27 1997. INTSORMIL/ICRISAT, pp. 119–141. Odame, H. and Kameri-Mbote, P. (2000) Agricultural biotechnology assessment in sub-Saharan Africa. Country specific study – Kenya. Paper prepared for the Regional Workshop on Building National Biotechnology Innovation Systems: New Forms of Institutional Arrangements and Financial Mechanisms. African Centre for Technology Studies, Nairobi, Kenya. ODI (1996) Good Practice Review 4: Seed Provision During and After Emergencies. Overseas Development Institute, London, 137 pp. Oh, B.J., Frederiksen, R.A. and Magill, C.W. (1996) Identification of RFLP markers linked to a gene for downy mildew resistance (Sdm) in sorghum. Canadian Journal of Botany 74, 315. Okali, C., Sumberg, J. and Farrington, J. (1994) Farmer Participatory Research: Rhetoric and Reality. Intermediate Technology, London, 159 pp. Olsen, K.M. and Schaal, B.A. (1999) Evidence on the origin of cassava: phylogeography of Manihot esculenta. Proceedings of the National Academy of Sciences USA 96, 5586–5591. Onim, M. (1998) Multi-location multiplication of ACMV-resistant cassava varieties in western Kenya. Report to the KARI/IITA Cassava Steering Committee. Lagrotech Consultants, Kisumu, Kenya, 22 pp. Ortiz, R. and Vuylsteke, D. (1994) Plantain breeding at IITA. In: Jones (ed.) The Improvement and Testing of Musa: A Global Partnership. Proceedings of the first global conference of the International Musa Testing Program held at FHIA, Honduras, 27–30 April, 1994. INIBAP, Montpellier, France, pp. 63–76. Osborn, T. (1996) Seeds for Disaster Mitigation and Recovering in the Greater Horn of Africa. USAID Office of Foreign Disaster Assistance (OFDA), Washington, DC, 137 pp. Otim-Nape, G.W., Bua, A. and Thresh, J.M. (1997) Progress in cassava technology transfer in Uganda. In: Proceedings of the National Workshop on Cassava Multiplication, Masindi, Uganda, January, 1996. NARO/NRI Publication, 139 pp. Ou, S.H. (1985) Rice Diseases. Kew Institute, London, 368 pp. Oyejide, T.A. (1993) Effects of trade and macroeconomic policies on African Agriculture. In: Bautista, R.M. and Valdes, A. (eds) The Bias Against Agriculture: Trade and Macroeconomic Policies in Developing Countries. International Center for Economic Growth, San Francisco, California, pp. 241–262. Ozias-Akins, P.E., Lubbers, L., Hanna, W.W. and McNay, J.W. (1993) Transmission of the apomictic mode of reproduction in Penniserum: co-inheritance of the trait and molecular markers. Theoretical and Applied Genetics 85, 632–638. Paarlberg, R.L. (2000) 2020 Vision Discussion Paper 33 – Governing the GM crop revolution: Policy choices for developing countries. IFPRI, Washington, DC.

188

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter

189

References

Padulosi, S. and Ng, N.Q. (1997) Origin, taxonomy and morphology of Vigna unguiculata (L.) Walp. In: Singh, B.B., Mohan Raj, D.R., Dashiell, K.E. and Jackai, L.E.N. (eds) Advances in Cowpea Research. Co-publication of IITA and Japan International Research Center for Agricultural Sciences. IITA, Ibadan, Nigeria. Palm, C.A. (1995) Contribution of agroforestry trees to nutrient requirements of intercropped plants. Agroforestry Systems 30, 105–124. Palm, C.A., Myers, R.J.K. and Nandwa, S.M. (1997) Combined use of organic and inorganic nutrient sources for soil fertility maintenance and replenishment. In: Replenishing Soil Fertility in Africa. SSSA Special Publication Number 51. Proceedings of an international symposium cosponsored by Divisions A-6 (International Agronomy) and S-4 (Soil Fertility and Plant Nutrition), and the International Center for Research in Agroforestry, held at the 88th Annual Meetings of the American Society of Agronomy and the Soil Science Society of America, Indianapolis, Indiana, 6 November 1996. Soil Science Society of America. Madison, Wisconsin, USA, pp. 193–217. Pardey, P.G., Roseboom, J. and Anderson, J.R. (1991) Topical perspectives on national agricultural research. In: Pardey, P.G., Roseboom, J. and Anderson, J.R. (eds) Agricultural Research Policy: International Quantitative Perspectives. Cambridge University Press, Cambridge, pp. 265–308. Pardey, P.G., Roseboom, J. and Beintema, N.M. (1997) Investments in African agricultural research. World Development 25, 409–423. Patel, P.N. and Hall, A.E. (1988) Inheritance of heat-induced brown discoloration in seed coats of cowpea. Crop Science 28, 929–932. Pereira, M.G., Lee, M., Bramel-Cox, P., Woodman, W., Doebley, J. and Whitkus, R. (1994) Construction of an RFLP map in sorghum and comparative mapping in maize. Genome 37, 236–243. Persley, G.P. (1999) Biotechnology for Developing-Country Agriculture: Problems and Opportunities. Letter to a Minister. Focus 2. Brief 1 of 10. October 1999. International Food Policy Research Institute (IFPRI), Washington, DC. Persley, G.P. and Doyle, J.J. (1999) Biotechnology for developing-country agriculture: Problems and opportunities. IFPRI Focus 2. Brief 1. IFPRI: Washington, DC. Phillips, R.L., Somers, D.A. and Hibberd, K.A. (1988) Cell/tissue culture and in vitro manipulation. In: Sprague, G.F. and Dudley, J.W. (eds) Corn and Corn Improvement, 3rd edn. Agronomy Monograph No. 18. American Agronomy Association, Crop Science Society of America, and Soil Science Society of America, Madison, Wisconsin. Pingali, P., Bigot, Y. and Binswanger, H.P. (1987) Agricultural Mechanization and the Evolution of Farming Systems in Sub-Saharan Africa. Johns Hopkins University Press, Baltimore, Maryland. Pinto, Y.M., Kok, R.A. and Baulcombe, D.C. (1999) Resistance to rice yellow mottle virus (RYMV) in cultivated African rice varieties containing RYMV transgenes. Nature Biotech., 17, 702–707. Pixley, K.V. (1996) CIMMYT mid-altitude maize breeding program – Report of activities during 1995/96. CIMMYT-Harare Annual Report, 1995–96. CIMMYT, Harare, Zimbabwe. Pixley, K.V. (1997) CIMMYT mid-altitude maize breeding programme. In: Jewell, D.C., Pixley, K.V., Banziger, M., Waddington, S.R., Varughese, G., Zambezi, B.T. and Mekuria, M. (eds) CIMMYT-Harare Annual Report, 1996–97. CIMMYT, Harare, Zimbabwe. Pixley K.V. and Zambezi, B.T. (1996) Maize Germplasm Available from CIMMYT – Zimbabwe. CIMMYT, Harare, 30 pp. Ploetz, R.C. (1990) Population biology of Fusarium oxysporum f. sp. Cubense. In: Ploetz, R.C. (ed.) Fusarium Wilt of Banana. American Pathology Society Press, St Paul, Minnesota, pp. 63–76.

189

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter

190

References

Ploetz, R.C. (1994) Fusarium wilt and IMTP Phase II. In: The Improvement and Testing of Musa: a Global Partnership. Proceedings of the first global conference of the International Musa Testing Program held at FHIA, Honduras, 27–30 April, 1994. INIBAP, Montpellier, France, pp. 57–69. Poehlman, J.M. (1979) Breeding Field Crops, 2nd edn. AVI Publishing Company, Inc., Westport, Connecticut. Prakash, C.S. and Shivashankar, G. (1984) Inheritance of resistance to bacterial blight in cowpea. Genetica Agraria 38, 1–10. Prasad, B., Prabhu, M.S. and Shantamma, C. (1984) Regeneration of downy mildew resistant plants from infected tissues of pearl millet cultured in vitro. Current Science 53, 816–817. Provvidenti, R. (1993) Genetics of resistance to viral diseases of bean. In: Kyle, M.M. (ed.) Resistance to Viral Diseases of Vegetables: Genetics and Breeding. Timber Press, Portland, Oregon, pp. 112–152. Quinones, M.A., Borlaug, N.E. and Dowswell, C.R. (1997) A fertilizer-based green revolution for Africa. In: Replenishing Soil Fertility in Africa. Soil Science Society of America, Madison, Wisconsin, pp. 81–95. Rabobank (1994) The World Seed Market. Report by the Rabobank Nederland, Netherlands. Rachie, K.O. and Anand Kumar, K. (1994) Pearl millet improvement at ICRISAT – An update. Int. Sorghum Millet Newsletter 35, 1–29. Rachie, K.O. and Majmudar, J.V. (1980) Pearl Millet. Pennsylvania State University Press, University Park. Rai, K.N., Anand Kumar, K., Andrews, D.J., Gupta, S.C. and Ouendeba, B. (1997) Breeding pearl millet for grain yield and stability. In: Proceedings of the International Conference on Genetic Improvement of Sorghum and Pearl Millet. Meeting held in Lubbock, Texas, September 22–27 1997. INTSORMIL/ICRISAT, pp. 71–83. Rai, K.N., Andrews, D.J. and Rao, A.S. (2000) Feasibility of breeding male-sterile populations for use in developing inter-population hybrids of pearl millet. Plant Breeding 119, 335–339. Rajaram, S., Singh, R.P. and Torres, E. (1998) CIMMYT approaches in breeding wheat for rust resistance. In: Simmonds, N.W. and Rajaram, S. (eds) Breeding Strategies for Resistance to the Rusts of Wheat. CIMMYT, Mexico DF. Rathus, C., Adkins, A.L., Henry, R.J., Adkins, S.W. and Godwin, I.D. (1996) Progress towards transgenic sorghum. In: Foale, M.A., Henzell, R.G. and Kneipp, J. (eds) Proceedings of the 3rd Australian Sorghum Conference, 20–22 Feb 1996, Tamworth. Australian Institute of Agricultural Science, Melbourne, Australia. Occasional Publication No. 93, pp. 409–412. Ratnadass, A. and Ajayi, O. (1995) Panicle insects pests in sorghum in West Africa. In: Nwanze, N.F. and Youm, O. (eds) Panicle insect pests of sorghum and pearl millet. Proc. Int. Consult. Workshop, 4–7 Oct. 1993. Niamey, Niger. ICRISAT, Andra Pradesh, India, pp. 29–38. Rattray, A.G.H. (1969) Advances and achievements in crop research. In: Proceedings of the Conference on Research and the Farmer, Salisbury, Rhodesia, Sept. 18–19, 1969. Dept of Research and Specialist Services, Harare. Rattunde, H.F.W., Weltzien, E., Bramel-Cox, P., Kofoid, K., Hash, C.T., Schipprack, W., Stenhouse, J.W. and Presterl, T. (1997) Population improvement of pearl millet and sorghum: current research impact and issues for implementation. In: Proceedings of the International Conference on Genetic Improvement of Sorghum and Pearl Millet. Meeting held in Lubbock, Texas, September 22–27 1997. INTSORMIL/ICRISAT, pp. 188–212. Ravallion, M. and Chen, S. (1997) What Can New Survey Data Tell Us about Recent Changes in (Income) Distribution and Poverty. World Bank Economic Review. Rawal, K.M. (1975) Natural hybridisation among weedy and cultivated Vigna unguiculata (L.) Walp. Euphytica 24, 699–707. Reader, J. (1997) Africa: a biography of the continent. Hamish Hamilton, London.

190

A4138:AMA:DeVries:First Revise:19-Oct-01

Chapter

191

References

Redden, R.J., Dobie, P. and Gatehouse, A.M.R. (1983) The inheritance of seed resistance to bruchids in cowpea. Australian Journal of Agricultural Research 34, 681–695. Remy, S., Francois, I., Schoofs, H., Panis, B., Cammue, B., Swennen, R. and Sagi, L. (1998) Genetic transformation as a technology to create disease resistance in banana. Acta Horticulturae, in press. RenKow, M. (1993) Differential technology adoption and income distribution in Pakistan: Implications for research resource allocation. American Journal of Agricultural Economics 75, 33–43. Ribaut, J.M., Hoisington, D.A., Deutsch, J.A., Jiang, C. and Gonzalez de Leon, D. (1996) Identification of quantitative trait loci under drought conditions in tropical maize. 1. Flowering parameters and the anthesis-silking interval. Theoretical and Applied Genetics 92, 905–914. Rohrbach, D.D. (1994) Improving farmer wellbeing in semi-arid areas. In: Jewell, D.C., Waddington, S.R., Ranson, J.R. and Pixley, K.V. (eds) Maize Research for Stress Environments. Proceedings of the Fourth Eastern and Southern Africa Regional Maize Conference, held at Harare, Zimbabwe, 28 March–1 April 1994, pp. 296–303. Rohrbach, D.D. and Makhwaje, E. (1999) Adoption and impact of new sorghum varieties in Botswana. Southern African Development Community (SADC)/International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Sorghum and Millet Improvement Program (SMIP). Bulawayo, Zimbabwe. (Semiformal publication). Rohrbach, D. and Malusalila, P. (2000) Developing rural retail trade of seed through small packs. Paper presented at the Zimbabwe Seed Sector Stakeholders Meeting, 25 June 1999, Matopos Research Station, Zimbabwe. Rohrbach, D.D., Lechner, W.R., Ipinge, S.A. and Monyo, E.S. (1999) Impact from Investments in Crop Breeding: the Case of Okashana 1 in Namibia. Impact Series no. 4. Patancheru 502 324, Andra Pradesh, India, International Crops Research Institute for the Semi-Arid Tropics, 48 pp. Rosenow, D.T. (1997) Host country program enhancement in Mali. In: INTSORMIL Annual Report, 1997. Rosenow, D.T., Ejeta, G., Clark, L.E., Gilbert, M.L., Henzell, T.G., Borrel, A.K. and Muchow, R.C. (1997) Breeding for pre- and post-flowering drought stress resistance in sorghum. In: Proceedings of the International Conference on Genetic Improvement of Sorghum and Pearl Millet. Meeting held in Lubbock, Texas, September 22–27 1997. INTSORMIL/ICRISAT, pp. 400–411. Rowe, P. and Rosales, F. (1994) Musa breeding at FHIA. In: Jones (ed.) The Improvement and Testing of Musa: a Global Partnership. Proceedings of the first global conference of the international Musa testing program held in FHIA, Honduras, 27–30 April 1994. INIBAP, Montpellier, France, pp. 117–129. Rowe, P. and Rosales, F.E. (1996) Bananas and plantains. In: Janick, J. and Moore, J. (eds) Fruit Breeding, Vol. 1, Tree and Tropical Fruits. John Wiley & Sons, New York, pp. 167–211. Rusike, J. and Eicher, C.K. (1997) Institutional innovations in the maize seed industry. In: Byerlee, D. and Eicher, C.K. (eds) Africa’s Emerging Maize Revolution. Lynne Rienner, London. Sagi, L., Remy, S., Panis, B., Swennen, R. and Volckaert, G. (1994) Transient gene expression in electroporated banana (Musa spp., cv. ‘Bluggoe’, ABB group) protoplasts isolated from regenerable embryogenic cell suspensions. Plant Cell Reports 13, 262–266. Sagi, L., Panis, B., Remy, S., Schoofs, H., De Smet, K., Swennen, R. and Cammue, B. (1995) Genetic transformation of banana (Musa spp.) via particle bombardment. Bio/Technology 13, 481–485. Sahrawat, K.L., Jones, M.P. and Diatta, S. (1999) The role of tolerant genotypes and plant nutrients in the management of acid soil infertility in upland rice. Paper presented at the

191

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter

192

References

consultants’ meeting on the use of nuclear techniques to develop management practices for increasing crop production and soil fertility in acid soils, March 1–3, 1999, FAO, Rome, Italy; IAEA Division of Nuclear Techniques in Food and Agriculture, International Atomic Energy Agency, Vienna, Austria. Salifou, E.M. (1998) Experience and economics of seed production in Niger. Paper presented at regional hybrid sorghum and pearl millet seed workshop, held in Niamey, Niger, September 28 – October 2 1998. Sanchez, P.A., Shepherd, K.D., Soule, M.J., Place, F.M., Buresh, R.J. and Izac, A.N. (1997) Soil fertility replenishment in Africa: an investment in natural resource capital. In: Replenishing Soil Fertility in Africa. Soil Science Society of America, Madison, Wisconsin, pp. 1–46. Sarail, A.K. and Singh, V.P. (1999) Seed set potential and seed yield of A × R combinations in rice (Oryza sativa L.). Seed Research 27, 140–145. Sasser, J.N. and Freckman, D.W. (1987) A world perspective on nematology: the role of the Society. In: Veech, J.A. and Dickson, D.W. (eds) Vistas on Nematology. Society of Nematologists, Hyattsville, USA, pp. 7–14. Sastray, J.G., Ramakrishna, W., Sivaramkrishnan, S., Thakur, R.P., Gupta, V.S. and Ranjekar, P.K. (1995) DNA fingerprinting detects genetic variability in the pearl millet downy mildew pathogen. Theoretical and Applied Genetics 91, 856–861. Schaffert, R.E., Alves, V.M.C., Bahia, A.F.C., Pitta, G.V.E., Santos, F.G. and de Oliveira, C.A. (1999) Sorghum genetic resources with contrasting phosphorus efficiency. In: Workshop on improving phosphorus acquisition efficiency in marginal soils, held on October 17–22, 1999 in Sete Lagoas, MG, Brazil. EMBRAPA, pp. XI: 1–13. Schechert, A.W. (1997) Quantitative genetic and marker-based studies on the importance of resistance of maize to Setosphaeria turcica in Kenya. PhD Thesis, University of Hohenheim. Schopke, C., Chavarriaga, P., Fauquet, C.M. and Beachy, R.N. (1995) Cassava tissue culture and transformation: improvement of culture media and the effect of different antibiotics on leaf tissues. In: Roca, W.M. and Thro, A.M. (eds) Proceedings of the First International Scientific Meeting of the Cassava Biotechnology Network. CIAT working document 123, pp. 140–145. Schopke, C., Taylor, N., Carcamo, R., Konan, N.K., Marmey, P., Henshaw, G., Beachy, R.N. and Fauquet, C. (1996) Regeneration of transgenic cassava plants (Manihot esculenta Crantz) from microbombarded embryogenic suspension cultures. Nature Biotechnology 14, 731–735. Scowcroft, W.R. (1996) Seeds of Hope Project Completion Report. CIAT, Cali, Colombia, 42 pp. Scowcroft, W.R. and Polak Scowcroft, C.E. (1997) Seed Security: Disaster Response and Strategic Planning. Australian Centre for Oil Seed Research, and Agriculture Australia Consultants, Horsham, Victoria, Australia. Scully, B.T. and Federer, W.T. (1993) Application of genetic theory in breeding for multiple viral resistance. In: Kyle, M.M. (ed.) Resistance to Viral Diseases of Vegetables: Genetics and Breeding. Timber Press, Portland, Oregon, pp. 167–195. Seed Co (2000) Seed Co Seed Manual 2000–2001. Seed Co Ltd, Harare, Zimbabwe, 28 pp. Sen, A. (1981) Poverty and Famines. Clarendon Press, Oxford. Serratos, J.A., Arnason, J.T., Blanco-Labra, A. and Mihm, J.A. (1994) Genetics of maize grain resistance to maize weevil. In: Mihm, J.A. (ed.) Insect Resistant Maize. Proceedings of an International Symposium, 27 Nov–3 Dec., 1994. CIMMYT, Mexico DF, pp. 132–138. Shigemune, A. and Yoshida, T. (2000) Methods of anther culture of pearl millet and ploidy level of regenerated plants. Japanese Journal of Crop Science 69, 224–228. Shull, G.H. (1908) The composition of a field of maize. American Breeders Association Reports 4, 296–301. Simmonds, N.W. (1962) The Evolution of the Bananas. Longman, London, 170 pp. Simmonds, N.W. (1966) Bananas, 2nd edn. Longmans, London.

192

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter

193

References

Simmonds, N.W. (1991) Selection for local adaptation in a plant breeding programme. Theoretical and Applied Genetics 82, 363–367. Singh, B.B. (1993) Cowpea breeding. In: Archival Report (1988–1992) of Grain Legume Improvement Program. IITA, Ibadan, Nigeria, pp. 10–53. Singh, B.B. and Mohammed, S.G. (1998) Quantitative characterization of cropping systems in the Sahel. In: Project 11: Cowpea–Cereals Systems Improvement in the Dry Savannas. Annual Report 1998. International Institute of Tropical Agriculture, Ibadan, Nigeria, 8 pp. Singh, B.B. and Olufano, O. (1998) Farmer for farmer diffusion of improved cowpea seeds. In: Project 11: Cowpea–Cereals Systems Improvement in the Dry Savannas. Annual Report 1998. International Institute of Tropical Agriculture, Ibadan, Nigeria, p. 36. Singh, B.B., Emechebe, A.M. and Atokple, I.D.K. (1993) Inheritance of Alectra resistance in cowpea genotype B 301. Crop Science 33, 70–72. Singh, B.B., Chambliss, O.L. and Sharma, B. (1996) Recent advances in cowpea breeding. In: Singh, B.B., Mohan Raj, D.R., Dashiell, K.E. and Jackai, L.E.N. (eds) Advances in Cowpea Research. Co-publication of IITA and Japan International Research Center for Agricultural Sciences, IITA, Ibadan, Nigeria. Singh, B.B., Mohan Raj, D.R., Dashiell, K.E. and Jackai, L.E.N. (eds) (1997) Advances in Cowpea Research. Copublication of International Institute of Tropical Agriculture (IITA) and Japan International Research Center for Agricultural Sciences (JIRCAS). IITA, Ibadan, Nigeria. Singh, S.D., Lal, S. and Pande, S. (1993) The changing scenario of maize, sorghum and pearl millet diseases. In: Sharma, H.C. and Veerabhadra, M. (eds) Pests and Pest Management in India – The Changing Scenario. Plant Protection Association of India, Rajendragar, Hyderabad, Andhra Pradesh 500030, India, pp. 130–139. Sitch, L. (1996) Fate of seed/planting material of farmer selected varieties distributed through World Vision’s extension program. Monograph. World Vision of Mozambique, Maputo, Mozambique. Sithole-Niang, I. (2000) Cowpea improvement through genetic engineering. Project Proposal. University of Zimbabwe, Harare. Smale, M. and Heisey, P.W. (1997) Maize technology and productivity in Malawi. In: Byerlee, D. and Eicher, C.K. (eds) Africa’s Emerging Maize Revolution. Lynne Rienner Publishers, Boulder, Colorado. Smale, M., Kaunda, Z.H.W., Makina, H.L., Mkandawire, M.M.M.K., Msowoya, M.N.S., Mwale, D.J.E.K. and Heisey, P.W. (1991) ‘Chimanga Cha Makolo’, in hybrids and composites: An analysis of farmers’ adoption of maize technology in Malawi, 1989–1991. CIMMYT Economics Working Paper 91/04. International Maize and Wheat Improvement Center (CIMMYT), Mexico DF. Smale, M., Kaunda, Z.H.W., Makina, H.L. and Mkandawire, M.M.M.K. (1993) Farmers’ evaluation of newly released maize cultivars in Malawi: a comparison of local maize, semi-flint and dent hybrids. International Maize and Wheat Improvement Center (CIMMYT), Lilongwe and Harare. Smale, M., Kaunda, H.W., Makina, H.L. and Mkandawire, M.M.M.K. (1994) Farmers’ evaluation of newly released maize cultivars in Malawi: a comparison of local maize, semi-flint and dent hybrids. CIMMYT, Mexico, DF. Smil, V. (1991) Population growths and nitrogen: an exploration of a critical existential link. Population and Development Review 17, 569–601. Smith, D.C. (1966) Plant breeding – development and success. In: Frey, K.J. (ed.) Plant Breeding. Iowa State University Press, Ames, Iowa, p. 32. Smith, J. (1993) Targetting hybrid maize to appropriate agricultural systems in the northern guinea savannah of West Africa. Unpublished paper. IITA, Ibadan, Nigeria.

193

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter

194

References

Smith, J., Weber, G., Manyong, M.V. and Fakorede, M.A.B. (1997) Fostering sustainable increases in maize productivity in Nigeria. In: Byerlee, D. and Eicher, C.K. (eds) Africa’s Emerging Maize Revolution. Lynne Rienner, Boulder, Colorado, pp. 107–126. Song, W.Y., Wang, G.L., Chen, L.L., Kim, H.S., Pi, L.Y., Holsten, T., Gardner, J., Wang, B., Zhai, W.X., Zhu, L.H., Fauquet, C. and Ronald, P. (1995) A receptor kinase-like protein encoded by the rice disease resistance gene, Xa21. Science 270, 1804–1806. Speijer, P.R. and De Waele, D. (1997) Screening of Musa germplasm for resistance and tolerance to nematodes. INIBAP Technical Guidelines 1. IPGRI, Rome, Italy; INIBAP, Montpellier, France. Spencer, D. (1986) Agricultural research: lessons of the past, strategies for the future. In: Berg, R.J. and Whitaker, J. (eds) Strategies for African Development. University of California Press, Berkeley, pp. 182–214. Spencer, D.S.C. and Edwin, J. (1999) Assessment of the Prospects of the WARDA Interspecific Rice Varieties in West Africa. Consultancy report compiled for The Rockefeller Foundation, New York, 32 pp. Sperling, L. (1994) Analysis of Bean Seed Channels in the Great Lakes Region: South Kivu, Zaire, Southern Rwanda, and Select Bean-Growing Areas of Burundi. Occasional Publications Series, No. 13. CIAT/RESAPAC, Butare, Rwanda. Sperling, L. and Loevinsohn, M. (1996) Using Diversity: Enhancing and Maintaining Genetic Resources On-farm. IDRC, New Delhi, India. Srivastava, J.P. and Jaffee, S. (1993) Best Practices for Moving Seed Technology: New Approaches to Doing Business. World Bank Technical Paper No. 176. World Bank, Washington, DC, 36 pp. Stenhouse, J.W., Bandyopadhyay, R., Singh, S.D. and Subramanian, V. (1996) Breeding for grain mold resistance in sorghum. In: Proceedings of the International Conference on Genetic Improvement of Sorghum and Pearl Millet. Meeting held in Lubbock, Texas, September 22–27 1997. INTSORMIL/ICRISAT, pp. 326–336. Stevens, R.D. and Jabara, C.L. (1988) Agricultural Development Principles. Johns Hopkins University Press, Baltimore, Maryland, 477 pp. Sthapit, B.R., Joshi, K.D. and Witcombe, J.R. (1995) Farmer participatory high altitude rice breeding in Nepal: providing choice and utilizing farmers’ expertise. In: Sperling L. and Loevinsohn, M. (eds) Using Diversity – Enhancing and Maintaining Genetic Resources On-farm. International Development Research Centre (IDRC), New Delhi, India, pp. 186–205. Storey, H.H. and Nichols, R.F.W. (1938) Studies of the mosaic diseases of cassava. Annals of Applied Biology 25, 790–806. Stover, R.H. and Simmonds, N.W. (1987) Bananas. 3rd edn. Longmans, London. Stuber, C.W. (1991) Biochemical and molecular markers in plant breeding. Plant Breeding Reviews 9, 37–61. Sustainable Community-oriented Development Programme (SCODP) (1999) News Brief, June 1999. SCODP’s Seed Mini-pack: a tool to improve small farmers access to improved seeds in Kenya. In: SCODP, Phase 2. Further development of SCODP’s farm input supply business in Western Kenya: Promotion of the use of fertilizer and seed amongst small farmers in Kenya. Project Proposal. Sega, Kenya. Swennen, R. and Vuylsteke, D. (1991) Bananas in Africa: diversity, uses and prospects for improvement. In: Ng, N.Q., Perrino, P., Attere, F. and Zedan, H. (eds) Crop Genetics Resources of Africa: Proceedings of an International Conference held in Ibadan, Nigeria, 17–20 Oct. 1988. IITA/IBPGR/UNEP/CNR, Ibadan, Nigeria. Swennen R., Vuylsteke, D. and Hahn, S.K. (1989) Combating the black Sigatoka threat to plantains. IITA Research Briefs 9(2), 2–4. Ibadan, Nigeria.

194

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter

195

References

Talukdar, B.S. and Singh, S.D. (1993) Stability and heritability for downy mildew resistance in two pearl millet pollinators. In: Annual Report 1992. Cereals Program ICRISAT, Patancheru, India, pp. 70–71. Talukdar, B.S., Singh, S.D. and Hash, C.T. (1994) Breeding for resistance to diseases in pearl millet. In: Singh, H.G., Mishra, S.N., Singh, T.B., Hari Har Ram and Singh, D.P. (eds) Crop Breeding in India. International Book Distributing Company, Lucknow, India, pp. 176–185. Taneja, S.L. and Leuschner, K. (1984) Resistance screening and mechanisms of resisitance in sorghum to shoot fly. In: Proceedings of the International Sorghum Entomology Workshop, 15–21 July, 1984. Texas A & M University College Station, Texas, pp. 115–129. Tanksley, S.D. (1993) Mapping polygenes. Annual Review of Genetics 27, 205–234. Tanksley, S.D., Young, N.D., Paterson, A.H. and Bonierbale, M.W. (1989) RFLP mapping in plant breeding: New tools for an old science. Bio/Technology 7, 257–264. Tao, Y.Z., McIntyre, C.L. and Henzell, R.G. (1996) Applications of molecular markers to Australian sorghum breeding programs. Proceedings of the Third Australian Sorghum Conference. Taylor, N.J., Edwards, M., Kiernan, R.J., Davey, C.D.M., Blakesly, D. and Hesnshaw, G.G. (1996) Development of friable embryogenic callus and embryogenic suspension culture systems in cassava (Manihot esculenta Crantz). Nature Biotechnology 14, 726–730. Tenkouano, A., Miller, F.R., Fredricksen, R.A. and Rosenow, D.T. (1993) A single locus with multiple alleles as the genetic basis of anthracnose resistance in sorghum. Theoretical and Applied Genetics 85, 644–648. Thakur, R.P. and Chahal, S.S. (1987) Problems and strategies in the control of ergot and smut in pearl millet. In: Whitcombe, J.R. and Beckerman, S.R. (eds) Proceedings of the International Pearl Millet Workshop, 7–11 April, 1986, ICRISAT, Andra Pradesh, India, pp. 147–160. Thakur, R.P., Talukdar, B.S. and Rao, V.P. (1983) Genetic of ergot resistance. In: Abstracts of contributed papers of the XV International Congress of Genetics, 12–21 Dec., 1983. New Delhi, p. 737. Thakur, R.P., Frederiksen, R.A., Murty, D.S., Reddy, B.V.S., Bandyopadhyay, R., Giorda, L.M., Odvody, G.N. and Claflin, L.E. (1997) Breeding for disease resistance in sorghum. In: Proceedings of the International Conference on genetic Improvement of Sorghum and Pearl Millet. Meeting held in Lubbock, Texas, September 22–27 1997. INTSORMIL/ICRSAT, pp. 303–336. Thotapilly, G., Mignouna, J., Ilori, C.O. and Fowale, I. (1998) Pollen electrotransformation in cowpea (Vigna unguiculata [L]Walp). In: Project 15: Molecular and Cellular Biotechnology for Crop Improvement. Annual Report 1998. International Institute of Tropical Agriculture, Ibadan, Nigeria, pp. 8–9. Thro, A.M. and Spillane, C. (2000) Biotechnology-assisted Participatory Plant Breeding: Complement or Contradiction? Working Document No. 4. CGIAR Systemwide Program on Participatory Research and Gender Analysis for Technology Development and Institutional Innovation. Timko, M. (2001) The cowpea genetic map and tools for breeders. Paper presented at a symposium on the genetic improvement of cowpea, January 8–12, 2001, Dakar, Senegal. Toenniessen, G.H. (1995) Plant biotechnology and developing countries. Tibtech 13, 404–409. Toenniessen, G.H. (1998) Plant biotechnology: potential for sustainable development. Paper presented at 4th Asia-Pacific Conference on Agricultural Biotechnology. Darwin, Australia, July 13–16, 1998. Toure, K. and Yehouenou, A. (1995) Les insectes de l’epi de mil en Afrique de l’ouest. In: Nwanze, K.F. and Youm, O. (eds) Panicle Pests of Sorghum and Pearl Millet: Proceedings of an International Consultative Workshop, 4–7 Oct., 1993, ICRISAT sahelian Center, Niamey, Niger. ICRISAT, Patancheru 502 324, Andra Pradesh, India, 320 pp. Touré, A., Rattunde, H.F.W. and Akintayo, I. (1998) Sorghum hybrids in West Africa. Conference Paper presented at Regional Hybrid Sorghum and Pearl Millet Seed Workshop, Niamey, Niger, Sept. 28–Oct 2 1998.

195

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter

196

References

Tripp, R. (2000) Strategies for Seed System Development in Sub-Saharan Africa: A study of Kenya, Malawi, Zambia, and Zimbabwe. Working Paper Series no. 2. Socioeconomic and Policy Program, International Crops Research Institute for the Semi-Arid Tropics. Bulawayo, Zimbabwe, 50 pp. Tripp, R. and Louwaars, N. (1997) Seed regulation: choices on the road to reform. Food Policy 22, 433–446. Tripp, R. and Rohrbach, D. (2000) Policies for African Seed Enterprise Development. (Unpublished). Trutmann, P. (1996) Participatory diagnosis as an essential part of participatory breeding: A plant protection perspective. In: Eyzaguirre, P. and Iwanaga, M. (eds) Participatory Plant Breeding. IPGRI, Rome. Tshiunza, M., Okechukwu, R.U. and Dixon, A.G.O. (1999) Status of cassava in semiarid zones of Central and West Africa. COSCASA Working Paper No. 1. Collaborative study of cassava in the semiarid zone of Africa. International Institute of Tropical Agriculture, Ibadan, Nigeria. Tyagi, A.K., Mohanty, A., Bajaj, S., Chaudhury, A. and Maheshwari, S.C. (1999) Transgenic rice: A valuable monocot system for crop improvement and gene research. Centre for Plant Molecular Biology and Department of Plant Molecular Biology, University of Delhi, New Delhi, India. Uganda, Ministry of Finance, Planning and Economic Development (2000) Uganda’s Poverty Eradication Action Plan: Summary and Main Objectives. Poverty reduction strategy paper. Kampala, Uganda, 67 pp. UN/IFPRI (2000) Chapter 1: Nutrition throughout the life cycle. In: Fourth Report on the World Nutrition Situation. Geneva, Switzerland: United Nations Administrative Committee on Coordination/Sub-Committee on Nutrition and the International Food Policy Research Institute, Geneva and Washington, DC. UPWARD (1996) Into Action Research: Partnerships in Asian Rootcrop Research and Development. UPWARD, Los Baños, Philippines. University of California, Riverside (1994) 1993 Executive Summary: A program to develop improved cowpea cultivars, management methods, and storage practices for semi-arid zones, 15 pp. USAID (1996) Seeds for Disaster Mitigation and Recovery in the Greater Horn of Africa. Report prepared by Chemonics International and USDA Famine Mitigation Activity, 135 pp. USAID (2000) United States International Food Assistance: Report for 1999. USAID, Washington, DC, 77 pp. USDA (1998) Agriculture Fact Book 1998. Washington, DC. Van Rensburg, J.J. and Gevers, H. (1993) Inheritance of antibiosis to the maize stalk borer, Buseola fusca. South African Journal of Plant and Soil 10, 35–40. Vasil, V. and Vasil, K. (1980) Isolation and culture of cereal protoplasts. II. Embryogenesis and plantlet formation form protoplasts of pearl millet. Theoretical and Applied Genetics 56–100. Veille Calzada, J.P., Crane, C.F. and Stelly, D.M. (1996) Apomixis: the asexual revolution. Science 274, 1322–1323. Veldhuizen, L. et al. (1997) Farmers Research in Practice: Lessons from the Field. Intermediate Technology, London. Venkatesan, V. (1994) Seed Systems in Sub-Saharan Africa: Issues and Options. World Bank Discussion Paper No 266. World Bank, Washington, DC, 112 pp. Verdiaer, V., Boher, B., Maraite, H. and Geiger, J.P. (1994) Pathological and molecular characterization of Xanthomonas campestris strains causing diseases of cassava. Applied Environmental Microbiology 60, 4478–4486.

196

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter

197

References

Vuylsteke, D., Ortiz, R. and Swennen, R. (1992) Plantains and bananas. In: Sustainable Food Production in Sub-Saharan Africa. IITA, Ibadan, Nigeria, pp. 86–91. Vuylsteke, D., Ortiz, R., Pasberg-Gauhl, C., Gold, C., Ferris, S. and Speijer, P. (1993) Plantation and banana research at the International Institute of Tropical Agriculture. HortScience 28, 873–874. Vuylsteke, D., Swennen, R. and De Langhe, E. (1996) Field performance of somaclonal variants of plantain (Musa spp., AAB group). Journal of the American Society of Horticultural Science 121, 42–46. Vuylsteke, D., Ortiz, R., Ferris, S. and Crouch, J. (1997) Plantain improvement. Plant Breeding Reviews 14, 267–320. Vuylsteke, D., Hartman, J., Tenkouano, A., Van de hauwe, I. and INIBAP (1998) International dissemination of improved hybrids. In: Project 7: Improving Plantain- and Banana-based Systems. Annual Report 1998. International Institute of Tropical Agriculture, Ibadan, Nigeria, pp. 53–54. Waddington, S.R. and Karigwindi, J. (1995) CIMMYT maize agronomy in southern Africa. In: Annual Research Report. November 1993 to October 1994. CIMMYT-Zimbabwe, Harare, 80 pp. Waddington, S.R., Edmeades, G.O., Chapman, S.C. and Barreto, H.J. (1994) Where to with agricultural research for drought-prone environments? In: Jewell, D.C., Waddington, S.R., Ransom, J.K. and Pixley, K.V. (eds) Maize Research for Stress Environments. Proceedings of the Fourth Eastern and Southern Africa Regional Maize Conference, Harare, Zimbabwe, 28 March – 1 April, 1994, pp. 129–151. Walker, D.J. and Tripp, R. (1997) Seed management by small-scale farmers in Ghana and Zambia. In: FAO Seed Conference held in Rome, Italy, 1997. FAO, Rome, Italy. Wang, R., Guegler, K., LaBrie, S.T. and Crawford, N.M. (2000) Genomic analysis of a nutrient response in Arabidopsis reveals diverse expression patterns and novel metabolic and potential regulatory genes induced by nitrate. Plant Cell 12, 1491–1510. WARDA (1997) Medium Term Plan 1998–2000: For Presentation to the Technical Advisory Committee, Consultative Group on International Agricultural Research, Rome, Italy. WARDA, Bouaké, Côte d’Ivoire WARDA (1998) Annual Report. West Africa Rice Development Association, Bouake, Côte d’Ivoire. WARDA (1999) Rice Interspecific Hybridization Project: Research Highlights 1999. WARDA, Bouaké, Côte d’Ivoire WARDA (1999) The Spark that Lit the Flame. West African Rice Development Association, Bouake, Côte d’Ivoire. Weinmann, H. (1975) Agricultural Research and Development in Southern Rhodesia: 1924–1950. Series in Science, No. 2. University of Rhodesia, Salisbury. Wellman, F.L. (1968) More diseases on crops in the tropics than in the temperate zone. Ceiba 14, 17–28. Welz, H.G., Schechert, A., Pernet, A., Pixley, K.V. and Geiger, H.H. (1998) A gene for resistance to the maize streak virus in CIMMYT maize inbred line CML 202. Molecular Breeding 4, 147–154. White, J. and Sitch, L. (1994) 1993/94 Yield Trials: Tete, Zambezi, Sofala and Nampula Provinces. World Vision International and Instituto Nacional de Investigacao Agronomica, Maputo, Mozambique, 63 pp. Widawsky, D.A. and O’Toole, J.C. (1990) Prioritizing the Rice Biotechnology Research Agenda for Eastern India. The Rockefeller Foundation, New York, 86 pp. Wiggins, S. (2000) Interpreting changes from the 1970s to the 1990s in African agriculture through village studies. In: Streeten, P.P. and Craswell, J. (eds) World Development 28, 631–662.

197

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter

198

References

Wilson, G.F. (1988) Plantain in Western Africa: report of a mission organized by INIBAP and sponsored by IFAD, IITA and CIRAD. Montpellier, France: INIBAP, 68 pp. Wilson, G.F. and Buddenhagen, I.W. (1986) The black Sigatoka threat to plantain and banana in West Africa. IITA Research Briefs 7, 3. Winkelmann, D. (1994) Quintessential internationalism in agricultural research. In: Anderson, J.R. (ed.) Agricultural Technology: Policy Issues for the International Community. CAB International, Wallingford, UK. Witcombe, J.R. (2000) The impact of participatory plant breeding and other breeding strategies on the genetic base of crops. In: Cooper, H.D., Hodgkin, T. and Spillane, C. (eds) Broadening the Genetic Base of Crop Production. CAB International, Wallingford, UK. Witcombe, J.R. and Hash, C.T. (2000) Resistance gene deployment strategies in cereal hybrids using marker-assisted selection: gene pyramiding, three-way hybrids, and synthetic parent populations. Euphytica 112, 175–186. Woo, S.S., Jiang, J., Gill, B.S., Paterson, A.H. and Wing, R.A. (1994) Construction and characterization of a bacterial artificial chromosome library for sorghum. Nucleic Acids Research 22, 4922–4931. World Bank (1998) www.worldbank.org World Vision International (1995) Southern Sudan Agricultural Recovery Program. 1995 Annual Report, Janson, G. and Kapukha, P. (eds). Nairobi, Kenya. Wortmann, C.S. (1998) In: Wortmann, C.S., Kirkby, R.A., Eledu, C.A. and Allen, D.J. (eds) Atlas of Common Bean (Phaseolus vulgaris L.) Production in Africa. CIAT, Cali, Columbia. Wright, M., Donaldson, T., Cromwell, E. and New, J. (1994) The Retention and Care of Seeds by Small-scale Farmers. NRI Report No. R2103. Wright, M., Delimini, L., Luhanga, J., Mushi, C. and Tsini, H. (1995) The Quality of Farmer Saved Seed in Ghana, Malawi and Tanzania, NRI Research Report. Wydra K. and Singh, B.B. (1998) Project 11: Cowpea–Cereals Systems Improvement in the Dry Savannas. Annual Report 1998. International Institute of Tropical Agriculture, Ibadan, Nigeria. Yadav, R.S., Hash, C.T., Bidinger, F.R. and Howarth, C.J. (1999a) QTL analysis and markerassisted breeding of traits associated with drought tolerance in pearl millet. In: Ito, O., O’Toole, J. and Hardy, B. (eds) Genetic Improvement of Rice for Water-limited Environments, pp. 211–223. Yadav, R.S., Hash, C.T., Bidinger, F.R., Dhanoa, M.S. and Howarth, C.J. (1999) Identification and Utilization of Quantitative Trait Loci (QTLs) to Improve Drought Tolerance in Pearl Millet (Pennisetum glaucum (L.) R.Br.) CIMMYT, El Batan, Mexico. Yadav, O.P., Weltzien-Rattunde, E., Bindinger, F.R. and Mahalakshmi, V. (2000) Heterosis in landrace-based topcross hybrids of pearl millet across arid environments. Euphytica 112, 285–295. Yapi, A.M., Debrah, S.K., Dehala, G. and Njomaha, C. (1999) Impact of Germplasm Research Spillovers: the Case of Sorghum Variety S 35 in Chad and Cameroon. Impact Series no. 3. ICRISAT, Patancheru 502 324, Andra Pradesh, India. Ye, Xudong (2000) Engineering the provitamin A (β-carotene) biosynthetic pathway into (Carotenoid-free) rice endosperm. Science 287, 303–305. Youm, O. and Kumar, K.A. (1995) Screening and breeding for resistance to millet head miner. P. 201–109. In: Nwanze, N.F. and Youm, O. (eds) Panicle Insect Pests of Sorghum and Pearl Millet. Proc. Int. Consult. Workshop. 4–7 Oct., 1993. Niamey, Niger. ICRISAT, Andra Pradesh, India, pp. 20. Young, N.D. (1999) A cautiously optimistic vision for marker-assisted breeding. Mini-review. Molecular Breeding 5, 505–510. Zambezi, B.T. (1997) Characteristics of Maize Cultivars Released in Selected Countries of the Southern African Development Community. International Maize and Wheat Improvement Center (CIMMYT), Maize Programme, Harare, Zimbabwe, 41 pp.

198

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter

Appendix A: Production (1000 t) of principal food crops in sub-Saharan Africa, 1997

Population Maize (million) West Africa Benin Burkina Faso Cameroon Central African Rep. Chad Côte d’Ivoire Gambia Ghana Guinea Guinea-Bissau Mali Nigeria Niger Togo Senegal Sierra Leone East Africa Burundi Eritrea Ethiopia Kenya Rwanda Somalia Sudan Tanzania Uganda

Rice

Sorghum

Millet

Bean/ Cassava cowpea

240.4 5.7 11.1 13.9

9797.7 714.4 366.5 600.0

7237.9 10,864.7 10,146.0 11,527.1 481.5 26.8 120.2 28.0 0.5 89.5 942.9 603.9 375.0 55.0 400.0 71.0

3.4

82.0 99.1 576.0 8.5 1093.0 80.5 9.0 289.8 5354.0 3.0 452.2 60.3 9.4 7629.0 162.0 11.0 2137.0 2214.0 78.0 128.0 52.0 2107.0 740.0

17.0 112.3 1287.0 16.7 227.0 696.6 135.0 614.0 3268.0 67.0 41.0 173.7 411.3 714.6 38.0 — — 55.3 4.3 2.0 2.0 533.0 80.0

6.7 14.3 1.2 18.3 7.6 1.1 11.5 118.4 9.8 4.3 8.7 4.4 194.6 6.4 3.4 60.1 28.4 5.9 10.2 27.9 31.5 20.8

38.0 426.6 19.4 12.9 316.9 5.0 19.0 540.3 7297.0 435.0 151.8 118.2 21.5 5944.5 85.0 59.0 1226.0 130.0 130.0 153.0 3369.0 498.5 294.0

12.0

144.7

248.4 65.4 66.1 153.8 8.0 29.0 738.9 5902.0 1713.0 58.3 426.5 21.7 1850.0 15.0 19.0 270.0 55.0 1.0 — 641.0 347.0 502.0

62.5 424.8 1.5 1781.8 173.4 2.5 184.7 7602.3 56.3 148.9 9.3 77.4 2431.8 130.0 — — 225.0 62.5 13.0 2.5 1426.0 572.8

2487.7 73.7 10.0 91.0 — 23.9 — — — — — 139.3 1650.0 420.0 46.7 33.1 — 1357.0 270.0 3.0 400.0 — 120.0 13.0 11.0 271.0 269.0

167

167

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter

168

Appendix A: Production of Food Crops

Appendix A.

Continued. Population Maize (million)

Southern Africa Angola Botswana Congo, Dem. Rep. Congo, Rep. Lesotho Madagascar Malawi Mozambique Namibia Swaziland Zambia Zimbabwe Total Africa

132.8 11.6 1.5 48.0 2.7 2.1 15.8 10.1 18.3 1.6 0.9 8.5 11.7 567.8

7299.7 369.5 11.6

Rice 3189.5 25.0 —

Sorghum 544.9 0.0 16.8

Millet 429.6 61.9 2.0

Bean/ Cassava cowpea 6542.5 581.6 —

2955.0 66.3 —

1000.0 347.0 50.0 38.0 4200.0 143.0 20.0 0.3 — — 195.1 6.0 142.1 — 29.1 — — 14.2 178.0 2558.0 1.0 — — 2421.7 1226.5 65.7 39.5 — 4.1 253.0 1042.0 180.2 262.5 44.2 1334.2 — 49.4 — 9.5 107.5 — — 108.2 0.4 0.7 — — 5.8 960.2 12.5 30.8 61.0 187.5 — 2192.2 0.4 105.0 115.0 40.0 45.0 24,726.4 11,142.0 17,354.1 12,425.6 20,501.4 6,799.7

Source: FAO, FAOSTAT Database, 1999.

168

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter

Appendix B: Per capita production (kg per person) of principal food crops in sub-Saharan Africa, 1997

Population (million) Maize West Africa Benin Burkina Faso Cameroon Central African Rep. Chad Côte d’Ivoire Gambia Ghana Guinea Guinea-Bissau Mali Nigeria Niger Togo Senegal Sierra Leone East Africa Burundi Eritrea Ethiopia Kenya Rwanda Somalia Sudan Tanzania Uganda

Rice

Sorghum

Millet

Bean/ Cassava cowpea

240.4 5.7 11.1 13.9

40.9 125.3 33.0 43.2

30.8 4.7 8.1 4.0

45.4 21.1 84.9 28.8

42.2 4.9 54.4 5.1

48.2 84.5 0.0 27.0

11.3 12.9 0.9 6.5

3.4 6.7 14.3 1.2 18.3 7.6 1.1 11.5 118.4 9.8 4.3 8.7 4.4 194.6 6.4 3.4 60.1 28.4 5.9 10.2 27.9 31.5 20.8

24.1 14.8 40.3 7.1 59.7 10.6 8.2 25.2 45.2 0.3 105.2 6.9 2.1 39.3 25.3 3.2 35.6 78.0 13.2 12.5 1.9 66.9 35.6

5.0 16.8 90.0 13.9 12.4 91.7 122.7 53.4 27.6 6.8 9.5 20.0 93.5 3.7 5.9 — — 1.9 0.7 0.2 0.1 16.9 3.8

11.2 63.7 1.4 10.8 17.3 0.7 17.3 47.0 61.6 44.4 35.3 13.6 4.9 30.5 13.3 17.4 20.4 4.6 22.0 15.0 120.8 15.8 14.1

3.5 37.1 4.6 55.1 8.4 1.1 26.4 64.2 49.8 174.8 13.6 49.0 4.9 9.5 2.3 5.6 4.5 1.9 0.2 0.0 23.0 11.0 24.1

42.6 9.3 29.7 1.3 97.4 22.8 2.3 16.1 64.2 5.7 34.6 1.1 17.6 12.5 20.3 — — 7.9 10.6 1.3 0.1 45.3 27.5

— 3.6 — — — — — 12.1 13.9 42.9 10.9 3.8 — 7.0 42.2 0.9 6.7 — 20.3 1.3 0.4 8.6 12.9 169

169

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter

170

Appendix B: Per Capita Production of Food Crops

Appendix B.

Continued. Population (million) Maize

Southern Africa Angola Botswana Congo, Dem. Rep. Congo, Rep. Lesotho Madagascar Malawi Mozambique Namibia Swaziland Zambia Zimbabwe Total Africa

Rice

Sorghum

Millet

Bean/ Cassava cowpea

132.8 11.6 1.5

38.5 31.9 7.7

24.1 2.2 —

3.3 — 11.2

2.4 5.3 1.3

49.1 50.1 —

21.9 5.7 —

48.0 2.7 2.1 15.8 10.1 18.3 1.6 0.9 8.5 11.7 567.8

20.8 7.4 67.6 11.3 121.4 56.9 30.9 120.2 113.0 187.4 43.7

7.2 0.1 — 161.9 6.5 9.8 — 0.5 1.5 — 19.9

1.0 — 13.8 0.1 3.9 14.3 5.9 0.8 3.6 9.0 30.6

0.8 — — — — 2.4 67.2 0.0 7.2 9.8 21.9

87.5 — — — 0.4 72.9 — — 22.1 3.4 37.2

3.0 2.2 6.8 153.3 25.0 — — 6.4 — 3.8 7.5

Source: FAO, FAOSTAT Database, 1999.

170

A4138:AMA:DeVries:First Revise:15-Oct-01

Chapter

Index

advanced research institutes (ARIs), 52 African agriculture compared with other regions, 3, 4, 7, 9, 10–11, 11, 29, 30 consumption patterns, 17–18 and political support, 9 agricultural indicator comparisons, 30, 31 agro-ecologies, 19–20, 95–96 adaptation by cassava, 155, 156 analysis and crop improvements, 27, 28 analysis for maize improvement, 110 analysis for rice improvement, 138 and crop design, 42, 44, 57 crop diversity, 12–22 regional production constraints, 53–56 seed company adjustment to, 45 and sorghum adaptation, 119 Agrobacterium-mediated gene transfer, 65 and bananas, 163–164 and cassava, 152 and cowpea, 144 and maize, 106 and rice, 136 and sorghum, 117–118 AIDS, impact on research, 47 Angola banana production trends, 158 cassava production, 149, 154 ‘Catete’ maize, 39 crop yield increases, 40 NGOs seed supply, 81

apomixis, 70–72

bananas, 13, 16, 17, 18, 39 breeding research centres, 161 genetic engineering and pest resistance, 65 history and utilization, 157–158 hybrid varieties, 161–162 improvement challenges, 164 improvement techniques, 161–164 intractable traits, 11 pests and diseases, 160–161, 162, 163–164 production constraints, 55, 160–161 production trends, 158–160 research and development priorities, 165–166 seed systems, 164–165 tissue culture propagation, 63 transgenic research, 68 transgenic varieties, 61 Bean/Cowpea Collaborative Research Support Programme, 142 beans, 19 pests and diseases, 11 Benin cassava production, 149, 154 bioinformatics, 59, 60 biosafety and biotechnology, 68, 70 biotechnology, 59–74, 117 banana improvement, 163–164 199

199

A4138:AMA:DeVries:First Revise:19-Oct-01

Index

200

Index

biotechnology continued cassava improvement, 151–152 cowpea breeding, 144–145 and farmer involvement, 78 and intellectual property rights, 72–74 maize improvement, 104–106, 105–106 millet breeding programmes, 128 and production constraints, 10 research challenges, 70 research constraints, 96 rice improvement, 135–136 transformation and gene expression, 146 bird damage to crops, 112, 125, 126–127, 129 Botswana, hybrid sorghum sales, 120 Burkina Faso cowpea breeding, 142 millet production levels, 124 rice breeding, 135 sorghum production, 112, 119 Burundi banana production trends, 158 NGO seed supply, 81 sorghum and banana varieties, 13

Cameroon banana production trends, 158 sorghum production, 112 cassava, 16, 17, 18, 19, 39 decentralized production, 155 genetic engineering and pest resistance, 65 genome, 152 history and utilization, 147–148 improvement challenges, 152–153 improvement techniques, 150–151 intractable traits, 11 nutritional improvement programme, 155 pests and diseases resistance, 155–156 production constraints, 55, 148–150 production trends, 148, 149 research and development priorities, 155–156 seed systems, 153–154 transgenic varieties, 61 cereal yield trends, 33 CGIAR see Consultative Group on International Agricultural Research (CGIAR)

Chad millet pests and diseases, 126 millet production levels, 124 sorghum production, 112 child nutrition, 30–31, 32, 140 CIAT see International Center for Tropical Agriculture (CIAT) CIMMYT see International Center for Maize and Wheat Improvement (CIMMYT) CIP see International Potato Center (CIP) civil unrest, 4 and agricultural disruption, 154 and seed supply, 78, 83 common bean, 17 and hunger periods, 32 community-based seed supply, 87, 90, 91, 108 Congo, banana production trends, 158 Congo (Dem. Rep.) cassava production, 149 crop yield increases, 40 rice production, 132 Consultative Group on International Agricultural Research (CGIAR), 39, 41, 42–43 biotechnology expenditure, 67 using marker-assisted selection, 63 consumption patterns, 17–18 and crop improvements, 21 Côte d’Ivoire banana production trends, 158 biotechnology research, 69 cassava production, 149 IARC crop improvement research, 50 rice production, 132 cotton Bt variety, 84 transgenic Bt variety, 61, 65 cowpea, 16, 18 drought-tolerant species, 17 early maturity, 143 genetic engineering and pest resistance, 65 history and utilization, 139–140 and hunger periods, 32 improvement techniques, 142–145 intractable traits, 11 landrace varieties, 39 low germination, 78 nutritional improvement goal, 146

200

A4138:AMA:DeVries:First Revise:19-Oct-01

Index

201

Index

pest-resistant varieties, 83–84 production constraints, 55–56, 141–142 production levels, 140 research and development priorities, 145–146 seed systems, 145 crop diversity, 5 crop improvement, 5, 27–28 and farmer acceptance, 20–21, 40–41, 115–116, 155 farmer involvement, 41–44 history, 37–38 national breeding programmes, 44–48 on-farm trials, 78 reducing crop losses, 95 research model, 52 variety improvements during war, 83 and yield potential, 35–36 crop research programmes, and local preference information, 21–22 crop varieties for improved yield, 5, 7 for low-input farming, 52 performance as selection factor, 8 Crops Research Institute, 154 Crotolaria ochroleuca, 25–26

DNA marker technology see marker-assisted selection (MAS) drought, 5 and maize production, 101, 107 resistance, 64 resistant cassava, 17, 147 resistant cowpea, 17, 143 resistant maize, 108–109 resistant rice, 137, 138 and rice production, 133–134 and sorghum production, 114, 118, 120 dwarfing genes, 38

East Africa banana production trends, 158, 159 cassava production trends, 149 cowpea production levels, 140 maize production trends, 100, 101 sorghum production trends, 113 environmental variation and crop choice, 16

Ethiopia fertilizer availability, 24 IARC crop improvement research, 50

fallows improvement, 25 farmers acceptance of new varieties, 20–21, 40 access to seed, 76, 88, 89 associations and seed purchase, 80–81 distributing seed to neighbours, 77, 78, 79, 92, 108 involvement in breeding programmes, 41–44, 78, 89 low adoption of improved sorghum, 115–116 millet varietal preferences, 127 poverty as factor in improvements, 36 seed saving, 77–79 and transgenic crops, 60 underestimating diseases, 44 fertilizers application, 10 availability and crop improvement, 24–27 lack of subsidies, 21 Starter Pack programme, 26 usage, 11, 12 food aid, 33 food crops per capita production tables, 169–170 production tables, 167–168 food importation, 31, 32, 33 food security, 4, 23, 33–34, 95 and cassava, 148, 153 and population growth, 29–30 and sorghum production, 119

Gabon banana production trends, 158 Gambia, The improved cassava distribution, 154 millet pests and diseases, 126 gene banks, 48 genetic engineering, 12, 59, 65–66, 117–118 maize, 106 genetic improvements and seed market, 96 genetically modified organisms (GMOs), opposition to, 67, 69 genomics, 59–60 geographic information systems (GIS), 19

201

A4138:AMA:DeVries:First Revise:19-Oct-01

Index

202

Index

Ghana banana production trends, 158 cassava improved varieties adoption, 153, 154 cassava production, 149 cowpea breeding, 142 cowpea seed systems, 145 open-pollinated varieties of maize, 105 green manures, 25, 26 Green Revolution, 7, 9, 35, 39, 40 groundnuts, seed availability, 78 Guinea banana production trends, 158 cassava production, 149 governmental improved rice distribution, 137 improved cassava distribution, 154 rice production, 132

heat stress in millet, 128–129 heat tolerant cowpea, 143 highlands, crop choice, 17, 19 hunger, 29, 30, 34 and crop improvement, 92 period, 13, 15, 32 hybrid crop varieties, 37, 75–76, 85 of bananas, 161–162 millet, 127–128, 130 of sorghum, 120

IARC see International Agricultural Research Centers (IARC) ICRISAT see International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) IITA see International Institute for Tropical Agriculture (IITA) infrastructure affecting hunger, 34 INIBAP see National Agricultural Research Organization of Uganda (INIBAP) intellectual property rights, 24, 72–74 and transgenic varieties, 84 International Agricultural Research Centers (IARC), 19, 46, 48–49, 50, 51, 57 and biotechnology, 70 and maize improvement programmes, 107

International Center for Maize and Wheat Improvement (CIMMYT), 19, 48, 49, 50 biotechnology expenditure, 67 and biotechnology research, 68 transgenic millet research, 106 International Center for Tropical Agriculture (CIAT), 19, 48, 49, 50 cassava genetic research, 152 International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), 48, 49, 50 International Institute for Tropical Agriculture (IITA), 39, 48, 49, 50 banana improvement, 161, 162 biotechnology expenditure, 67 and biotechnology research, 68 cassava improvement programme, 150, 151, 153, 154 cowpea breeding programme, 142–143, 144–145, 146 crop improvements, 83 International Potato Center (CIP), 48, 49, 50 iron toxicity in rice, 134 irrigation, 10, 11, 12, 36

KARI see Kenya, Agricultural Research Institute (KARI) Kenya Agricultural Research Institute (KARI), 19, 68, 106 banana production trends, 158 and biotechnology, 67 cassava production, 149, 154 grain imports, 31, 32 hybrid maize adoption, 39 hybrid maize production, 104 IARC crop improvement research, 50 maize breeding, 38 national breeding stategies, 46 NGO seed supply, 81 seed policy and regulation, 88 Sustainable Community-oriented Development Programme (SCODP), 26 tissue culture propagation, 62 transgenic research, 68, 106 transgenic sweet potato importation, 69

202

A4138:AMA:DeVries:First Revise:19-Oct-01

Index

203

Index

labour supply, 13, 95, 147 land scarcity, 26 land use and low technology impact, 32–33 patterns, 16, 18–19 landrace varieties, 39, 41, 72 of cassava, 150–151 of millet, 127, 128 resistance genes, 43–44 legume rotation, 25 Lesotho, improved cassava distribution, 154 Liberia banana production trends, 158 NGO seed supply, 81 low-input farming, 26, 27, 46, 95 crop design, 52 and maize production, 107 and seed availability, 75–76 and sorghum production, 119 lowlands, crop choice, 17, 18

Madagascar banana production trends, 158 cassava production, 149, 154 rice production, 132 maize, 16, 17, 18 Agrobacterium-mediated transgenic, 106 anthesis-silking interval trait, 109 Bacillus thuringiensis and pest resistance, 65, 68 and fertilizer application, 24 flint-textured, 21, 38, 83 history and utilization, 99 hybrid development by NARs, 45 hybrid varieties, 104–105 improvement challenges, 107 intractable traits, 11 Kenya agro-ecologies, 19 landrace varieties, 39 maturation time, 32 new varieties release rate, 56 nutrient use efficiency, 109 open-pollinated varieties, 105 pest- and disease-resistant, 109–110 pests and diseases, 11 production constraints, 19–20, 53, 101–104, 107 production levels, 100–101 research and development priorities, 108–110

resistance genes, 8, 64, 68 seed prices, 86 seed systems, 108 surplus production in Malawi, 31 transgenic varieties, 61 Malawi banana production trends, 158 early-maturing flint maize, 38 fertilizer prices, 25 flint-textured maize, 21 IARC crop improvement research, 50 maize surpluses, 31, 32 national breeding stategies, 46 Mali cowpea breeding, 142 crop yield increases, 40 IARC crop improvement research, 50 lack of seed companies, 120 millet pests and diseases, 126 millet production levels, 124 rice production, 132 rice varieties, 13 seed storage, 78 sorghum production, 112, 119 sorghum varieties, 38 Striga-tolerant sorghum, 39 marginal land improvement strategies, 6 marker-assisted selection (MAS), 12, 59, 60, 63–64, 68, 70, 105–106 and banana improvement, 165 and cassava, 156 sorghum improvement, 117 material transfer agreements (MTA), 73 maturation time, 36, 38, 41 mechanization, 10, 11, 12 micropropagation, 67 of cassava, 151–152 mid-altitude regions, crop choice, 17, 18–19 millet, 16, 18 crop improvement, 127–128 drought-tolerant species, 17 farmer varietal preferences, 127, 130 history and utilization, 123–124 hybrid varieties, 127–128, 130 improvement challenges, 128–129 intractable traits, 11 landrace varieties, 39 production constraints, 54–55, 125–127 production levels, 124–125 research and development priorities, 129–130

203

A4138:AMA:DeVries:First Revise:19-Oct-01

Index

204

Index

milling, 21 molecular genetics see biotechnology Mozambique cassava production, 149, 154 cowpea seed systems, 145 decision-making environment, 13, 14–15 early-maturing flint maize, 38 ‘Fumo de Comboio’ cassava, 39 NGO seed supply, 81 open-pollinated varieties of maize, 105 rice production, 132 seed storage, 77 ‘Seguetana’ cowpea, 39 yield increases with new varieties, 39, 40 multinational seed companies, 83, 87

Namibia, improved cassava distribution, 154 NARS see national agricultural research systems (NARSs) National Agricultural Research Organization of Uganda (INIBAP), 68 national agricultural research systems (NARSs), 19, 38, 45, 46–52, 49, 50, 52 and biotechnology, 70 and cassava breeding programmes, 153 interface with IARC, 51 relationship with seed companies, 80 seed dissemination, 56–57, 91 staffing and finance, 46–48 national breeding programmes, 44–48, 96 for cowpea, 145 national seed companies, 87 Niger millet production levels, 124 sorghum seed purchasing, 120 Nigeria banana production trends, 158 cassava distribution, 154 cassava improved varieties adoption, 153 cassava production trends, 148, 149 cassava yield increases, 39 cowpea breeding, 142 cowpea seed systems, 145 fertilizer availability and maize production, 24 IARC crop improvement research, 50 millet production levels, 124 open-pollinated varieties of maize, 105

rice breeding, 135 rice production, 132 nitrogen, 25, 26 non-governmental organizations (NGOs), 40 and banana variety dissemination, 165 cassava breeding, 154 maize seed distribution, 108 seed dissemination, 81, 84, 91, 96, 120, 137 supplying OPVs, 76 supplying plant material, 63

open-pollinated varieties (OPVs), 23, 37, 82, 83, 85 maize, 45, 104, 105 millet, 128 seed dealers lack of interest, 76

Participatory Variety Selection, 137 pearl millet see millet pests and diseases, 5 of bananas, 160–161, 162, 163–164 of cassava, 149–150, 151 of cowpea, 141–142, 143–144 of maize, 8, 101–104, 107 of millet, 125–126 and new crop varieties, 83 as production constraints, 53–56 resistance and quantitative trait loci (QTLs), 64 resistance and tissue culture, 63 resistant bananas, 165–166 resistant cassava, 155–156 resistant cowpea, 145, 146 resistant millet, 129 resistant rice, 138 resistant sorghum, 121 of rice, 133, 134, 135–136, 137 of sorghum, 113 suffered by landrace varieties, 41 underestimated by farmers, 44 phenotypes, 66, 105, 106 phosphorus, 25, 127, 130 phytosanitary restrictions, 88 pigeon pea, 19 plant biotechnology, expenditure, 67 plant breeding, 51–57 aims, 36–40

204

A4138:AMA:DeVries:First Revise:19-Oct-01

Index

205

Index

biotechnology training for researchers, 67, 69 challenges, 57 decentralized cassava production, 155 farmer involvement, 41–44, 89 history, 37–39 maize improvement, 104–106 multiplication of cassava, 154 NARSs and seed market, 56–57 national, 23–24, 44–48 on-farm testing, 78, 91, 154 and phenotypes, 66 rice, 135–137 sorghum improvement, 114–115 plant restructuring, 36, 38 plant variety protection, 24 planting decisions, 13 political strategies and agriculture, 9, 23–24 pollination, 23–24 hybrid varieties 37 open-pollinated varieties (OPVs) see open-pollinated varieties (OPVs) polymerase chain reaction (PCR), 63 banana improvement, 163 cassava improvement, 152 rice improvement, 136 polyploid crops, and apomixis, 71 population growth, 26, 29–30, 41 and maize production, 101 post-harvest pests and diseases in maize, 102, 103–104, 109–119 potassium, 25 potatoes, 19 Bacillus thuringiensis and pest resistance, 65 pests and diseases, 11 research institutes, 48, 49, 50 primary crop production per capita, 16 production constraints, 9, 12, 53–56, 95, 96 bananas, 160–161 cassava, 148–150 maize, 20, 101–104, 107 millet, 125–127 rice, 133–134 routine or intractable, 10 sorghum, 113–114 pulses, 18

QTLs see quantitative trait loci (QTLs) qualitative trait loci, 63, 66

quality importance, 21 quantitative trait loci (QTLs), 63, 64, 66 and cassava improvement, 152 and cowpea improvement, 144–145 and maize improvement, 104, 105–106 and rice improvement, 136

research programmes biotechnology, 59–74 financial constraints, 45, 46–48 resources, 8 scientist training, 51, 67, 69, 70 resistance genes, 8, 37, 43–44, 45, 52, 60–61, 64, 68, 83–84 cassava, 151 cowpea, 143, 146 maize, 105 millet, 125–126 rice, 136 sorghum, 119 restriction fragment length polymorphism (RFLP), 63, 105, 106 cassava improvement, 152 cowpea linkage map, 144–145 millet linkage map, 128 rice improvement, 136 sorghum linkage maps, 117 rice, 16, 17, 18 Bacillus thuringiensis and pest resistance, 65 crop improvement, 135–136 crossbreeding programme, 43 genome project, 60, 135 history and utilization, 131–132 improvement challenges, 136–137 intractable traits, 11 Oryza glaberrima, 13, 43, 131, 134, 135 Oryza sativa, 13, 43, 131, 134, 135 pests and diseases, 11 pro-vitamin A incorporation, 65–66 production constraints, 53–54, 133–134 research and development priorities, 138 research institutes, 48, 49, 50 seed systems, 137 sterility between crosses, 60 tissue culture propagation, 62 transgenic varieties, 38, 61, 66 Rockefeller Foundation career fellowships, 69 rice biotechnology, 135–136

205

A4138:AMA:DeVries:First Revise:19-Oct-01

Index

206

Index

Rwanda banana production trends, 158, 159 improved cassava distribution, 154 NGO seed supply, 81 sorghum and banana varieties, 13 sorghum production, 112

Sahel cassava production trends, 148 SCODP see Sustainable Community-oriented Development Programme (SCODP) seed certification, 88, 90 seed consumption estimates, 77 seed market, 9 constraints of small-scale production, 22–23, 45, 52, 56–57, 75, 87 deregulation, 56, 57, 76, 81, 90, 96 and intellectual property rights, 72–74 lack of African companies, 86–87 multinational companies, 79–80 national seed companies, 80 private sector seed companies, 92–93, 105 public sector companies, 92–93 trade volume, 77 variety development and marketing, 90, 91 seed policy and regulation, 87–88, 90–91 seed prices, 85–86 seed systems of bananas, 164–165 of cassava, 153–154 comunity-based production, 84 cowpea, 145 definition, 75 disasters and supplies, 78, 83 farmer-saved seed, 77, 78, 79, 92, 108 government funding, 78 government involvement, 90, 92 hybrid varieties, 85 maize, 108 millet, 129 multiplication of supply, 91 open-pollinated varieties, 85 purchases by farmer associations, 80–81 sorghum, 119–120 storage, 77–78 supply fraud, 81 sustainable supply, 86–87, 91, 120, 122 transgenic crops, 84

self-pollinated varieties dissemination by public sector, 91 semi-arid land and crop improvement, 17 Senegal cowpea breeding, 142 cowpea yield increases, 40 IARC crop improvement research, 50 millet pests and diseases, 126 millet production levels, 124 rice breeding, 135 sesame crops for oil, 13 Sierra Leone improved cassava distribution, 154 NGO seed supply, 81 rice breeding, 135 rice production, 132 soil fertility, 4, 24–27 decline, 9 Somalia NGO seed supply, 81 seed storage, 77 sorghum, 16, 18 biotechnology and improvement, 117–118 day-length sensitivity, 113–114 drought-tolerant species, 17 ‘durra’ varieties, 38 flour quality preferences, 21 grain quality issues, 116–117, 119 history and utilization, 111–112 hybrid varieties, 120, 121 improved strains adoption by farmers, 115–116 improvement challenges, 118–119 improvement techniques, 114–117 intractable traits, 11 landrace varieties, 39 pest-resistant varieties, 84, 121 phosphorus acquisition efficiency, 122 production constraints, 54, 113–114 production levels and trends, 112 research and development priorities, 121–122 seed systems, 119–120 varieties in Bugusera region, 13 varieties in Sudan, 13 South Africa banana production trends, 158 and biotechnology, 67 hybrid sorghum sales, 120

206

A4138:AMA:DeVries:First Revise:19-Oct-01

Index

207

Index

Southern Africa, 50 banana production trends, 159 cassava production trends, 149 cowpea production trends, 140 maize production trends, 100, 101 sorghum production trends, 112, 113 soybean, 39 sterility in plant breeding, 60, 127, 128, 162 storage pests in maize, 102, 103–104 stress tolerance, 36, 37 Striga infestation of cowpea, 142, 144 of maize, 102, 103, 107, 110 of millet, 126 and sorghum production, 114, 121 Striga resistance, 8, 39, 52, 64, 128, 129 in maize, 110 Sudan hybrid sorghum sales, 120 maize yield increases, 40 millet production levels, 124 ‘Reep’ maize, 39 seed storage, 77 sorghum production, 112 sorghum varieties, 13 Sustainable Community-oriented Development Programme (SCODP), 26 sustainable farming and intensification, 38 Swaziland, improved cassava distribution, 154 sweet potatoes, 18 pests and diseases, 11 transgenic varieties, 68

Tanzania banana production trends, 158 improved cassava distribution, 154 rice production, 132 seed policy and regulation, 88 teff, 19 temperate vs. tropical zone disease, 11 tissue culture, 12, 59, 60, 62–63, 67, 128 of bananas, 163, 165 of cassava, 154 national research centres, 68–69 tobacco transgenic research, 68, 69 Togo improved cassava distribution, 154 ‘Indiana’ millet, 39 rice breeding, 135

training see research programmes, scientist training transgenic crop varieties, 38, 60–61, 66 and biosafety, 70 and intellectual property rights, 84 maize, 106 tropical vs. temperate zone disease, 11

Uganda banana improvement research, 162 banana production trends, 158, 159 cassava production, 149, 154 IARC crop improvement research, 50 national breeding stategies, 46 NGO seed supply, 81 seed policy and regulation, 88 transgenic banana development, 68, 164

velvet bean, Mucuna pruriens, 25–26

WARDA see West Africa Rice Development Association (WARDA) West Africa banana production trends, 158, 159 cassava production trends, 148, 149 cowpea production trends, 140 IARC crop improvement research, 50 maize production increases, 39 maize production trends, 100, 101 sorghum production trends, 113, 118–119, 120 West Africa Rice Development Association (WARDA), 38, 43, 48, 49, 50, 50 biotechnology expenditure, 67 and biotechnology research, 68 rice breeding programme, 135, 136–137, 138 wheat, 17, 19 ‘woman on a hill’ concept, 5, 7

yam, 39 yield decline of bananas, 161 yield increases with new varieties, 39, 40 yield potential, 35 yield stabilizing traits, 36

207

A4138:AMA:DeVries:First Revise:19-Oct-01

Index

208

Index

Zaire NGO seed supply, 81 Zambia improved cassava distribution, 154 seed gifts, 79 Zimbabwe and biotechnology, 67 biotechnology research, 68, 69 cowpea seed systems, 145

government support for seed supply, 82–84 hybrid maize production, 104 hybrid sorghum sales, 120 IARC crop improvement research, 50 improved cassava distribution, 154 maize imports, 32

208

A4138:AMA:DeVries:First Revise:19-Oct-01

Index