Breakthroughs in maize breeding

B. Badu-Apraku, b.badu-apraku@cgiar.org, M. Oyekunle, and R.O. Akinwale

Extra-early maize inbreds and hybrids that are resistant to Striga, tolerant of low nitrogen (N) and drought at flowering and grain filling periods, and that combine tolerance for these three stresses are now available in sub-Saharan Africa as a result of the painstaking research under the Maize Improvement Program at IITA.

Maize is the most important cereal crop after rice in West and Central Africa. However, during the last two decades, its production and productivity have lagged behind population growth for several reasons. These include low soil fertility, little or no use of improved seeds, herbicides, and fertilizers, inadequate plant density, weed infestation, poor tillage practices, labor shortages, increased levels of biotic and abiotic constraints, and high costs of inputs. In addition, serious infrastructural and institutional constraints have limited the adoption of improved maize technologies. Climate change and its associated effects have also resulted in altered weather patterns leading to erratic and unreliable amounts and distribution of rainfall, resulting in drought. Presently, stresses from Striga infestation, drought, and low N are the most important biotic and abiotic factors that limit maize production in the region.

Four maturity groups are needed to satisfy the maize varietal requirements of the subregion for human consumption, poultry and livestock feed, and industrial use. These groups are the extra-early varieties (80-85 days to maturity), early (90-95 days to maturity), intermediate (100-110 days to maturity), and late (>120 days to maturity). Extra-early varieties play a unique role in filling the hunger gap in July in the Sudan savanna and the northern Guinea savanna zones after the long dry season. The extra-early varieties are also used for late planting when the rains are delayed, for intercropping with cassava, millet, and sorghum, and as “green maize” in the forest agroecology where they allow early access to the market for a premium price. The availability of early and extra-early varieties has significantly contributed to the expansion of maize to new frontiers in the savanna agroecology, replacing sorghum and millet.

A major strategy of IITA’s Maize Improvement Program is to breed cultivars that are Striga resistant and drought- and low-N tolerant to increase and stabilize maize yield production in the subregion. Two approaches have been adopted for drought tolerance. The first is to breed for extra-early maturing cultivars that are drought escaping. These cultivars are adapted to drought-prone environments in West and Central Africa; they mature and complete their life cycles before severe moisture deficit occurs or before the onset of terminal drought. The second strategy is to breed drought-tolerant cultivars with better adaptation to drought-prone environments under induced drought stress. This is achieved by introgressing or introducing into extra-early cultivars the genes for drought tolerance to enable them to withstand mid-season drought when it occurs during the flowering and grain-filling periods.

Breeding for adaptation to drought-prone environments
The goal of the IITA Maize Program is to develop open-pollinated and hybrid maize cultivars adapted to the different forms of climatic variation prevalent in West and Central Africa with emphasis on drought stress. The naturally available mechanisms for drought escape and drought tolerance in the germplasm and the prevailing production environments in West and Central Africa were exploited to develop cultivars with enhanced adaptation to stressful environments. Drought escape occurs when the plant completes critical physiological processes before drought sets in. This trait is quite desirable in cultivars to be released to farmers in areas where terminal drought is most prevalent. Adaptation to drought-prone environments, on the other hand, is under genetic control and indicates the presence of physiological mechanisms that minimize or withstand the adverse effects of drought if and when it occurs. Cultivars with enhanced adaptation to drought-prone environments are useful where drought occurs randomly and at any growth stage of the maize crop. This is quite relevant in West and Central Africa where drought occurrence is erratic, with varying timing and levels of intensity.

Using the two strategies, IITA has, during the last two decades, developed a wide range of high-yielding drought tolerant or drought-escaping extra-early Striga resistant populations (white and yellow endosperm), inbred lines, and cultivars to combat the threat posed by the weed Striga hermonthica and recurrent drought in the savannas of West and Central Africa. The extra-early populations from which the inbred lines and cultivars were derived were formed from crosses between local landraces, exotic, and introduced germplasm identified through extensive multilocation trials in West and Central Africa. They were selected based on high grain yield, earliness, and resistance to the maize streak virus (MSV), and above all on adaptation to the high temperatures and drought stress characteristic of the Sudan savanna in Burkina Faso, Mali, Mauritania, Ghana, Nigeria, and Niger.

The extra-early germplasm was expected to have adaptive traits for tolerance to these stresses in the environments where the cultivars had survived. Some of the extra-early inbred lines in the IITA Maize Program not only escaped drought stress but also seemed to possess drought tolerance genes. The inbreds, early, intermediate, and late-maturing, are also able to withstand the mid-season drought that occurs during the flowering and grain filling periods in the savannas of West and Central Africa.

Selection for tolerance for drought under managed drought stress
Selection for extra-earliness in the IITA Maize Program has been carried out in the savannas of the subregion. So far, several cultivars have been bred, some of which have been released to farmers after extensive testing in the different countries in the subregion.

Induced drought stress for selection for drought tolerance in extra-early maize is achieved by withdrawing irrigation water from 21 days after planting until maturity, with the plants relying on water stored in the soil for growth and development. Promising inbred lines selected for drought tolerance were used to develop extra-early maturing open-pollinated and hybrid cultivars with enhanced adaptation to drought-prone environments. The selected lines are also used as sources of tolerance genes for introgression into extra-early breeding populations that are undergoing recurrent selection. Using this strategy, several extra-early drought tolerant and Striga resistant cultivars with enhanced adaptation to drought-prone environments have been bred.

Selection for tolerance for low soil N
In most developing countries, maize production is carried out under conditions of low soil fertility which further compounds the problems of drought stress and Striga infestation on productivity. Estimated yield losses from N-stress alone can be as high as 50% (Wolfe et al. 1988). Therefore, the development and adoption of maize germplasm with tolerance for multiple stresses are crucial for increased productivity. Banziger et al. (1999) showed that improvement for drought tolerance also resulted in specific adaptation and improved performance under low-N conditions, suggesting that tolerance to either stress involves a common adaptive mechanism.

Identification of inbreds and hybrids with genes for tolerance for low soil N and drought
Three experiments were conducted between 2007 and 2010 in Nigeria to identify extra-early inbreds with tolerance for low N and/or drought stress at flowering and grain-filling periods, and to determine the potential of the inbreds for hybrid production and as a source of germplasm for improving breeding populations. In the first two experiments, 90 extra-early maturing maize inbred lines were evaluated in Nigeria at Ikenne (6º 53’N, 3º 42’E, 60 m altitude, 1200 mm annual rainfall) under managed drought stress and in well-watered environments during the dry seasons of 2007/2008 and 2008/2009. Similarly, the lines were evaluated in low-N (30 kg/ha) and high-N (90 kg/ha) studies at Mokwa (9º 18’N, 5º 4’E, 457 m altitude, 1100 mm annual rainfall) during the growing seasons of 2008 and 2009.

Results identified several stable and high-yielding hybrids ideal for drought environments and pinpointed the fact that the extra-early inbreds and hybrids are not only drought-escaping but also possess genes conferring drought and/or low-N tolerance. TZEEI 6, TZEEI 4, TZEEI 36, and TZEEI 38 were identified as ideal inbreds under drought. Under low N, TZEEI 19, TZEEI 96, and TZEEI 45 were top ranking with TZEEI 19 the ideal inbred. TZEEI 19, TZEEI 29, TZEEI 56, TZEEI 38, and TZEEI 79 were tolerant to both stresses. Eighteen of the 36 hybrids produced above-average yields across environments with four hybrids identified as very stable. TZEEI 29 × TZEEI 21 was the closest to the ideal genotype because it combined large mean performance with high yield stability.

Badu-Apraku et al. (2013) evaluated 17 of the 90 extra-early white maize inbreds tolerant to drought and low-N used in the earlier studies under drought, Striga, and in optimal environments at three locations in Nigeria for 2 years. Results indicated that the test environments were unique and that there were adequate genetic differences among the inbred lines to allow good progress from selection for improvements in the traits and to serve as sources of favorable alleles for improving breeding populations for drought tolerance at the flowering and grain-filling periods and Striga resistance and to serve as parents for developing superior hybrids.

Under drought stress, the mean grain yield of the hybrids ranged from 1114 kg/ha for TZEEI 14 × TZEEI 13 to 2734 kg/ha for TZEEEI 29 × TZEEI 21. The top-ranking hybrid, TZEEI 29 × TZEEI 21, outyielded by 13% the best Striga resistant and drought tolerant early maturing open-pollinated variety, TZE-W DT STR C4. Under well-watered conditions, the top-yielding hybrid was TZEEI 3 × TZEEI 13 (5868 kg/ha) while the lowest was TZEEI 14 × TZEEI 13 (2749 kg/ha). Under artificial Striga infestation, TZEEI 29 × TZEEI 14 was the top ranking hybrid, outyielding by 22% the best Striga and drought tolerant early open pollinated check, TZE-W DT STR QPM.

A stability analysis of the top 20 and worst five single-cross hybrids and four early open pollinated check cultivars revealed TZEEI 29 × TZEEI 14 as the second highest yielding and most stable single-cross hybrid across research environments; the highest-yielding single-cross hybrid, TZEEI 6 × TZEEI 14, was the least stable.

Badu-Apraku and Oyekunle (2012) also conducted two more studies for 2 years at five locations in Nigeria. TZEEI 79 × TZEEI 76 turned out to be the highest yielding and most stable hybrid across environments. It was concluded that the available extra-early yellow maize inbred lines are not only drought-escaping but also possess genes for drought tolerance at flowering and grain-filling periods.

The availability of these Striga resistant, low N and drought-tolerant extra-early inbreds and hybrids should go a long way in reducing the instability of maize yields in sub-Saharan Africa, especially in the savannas and during the second season in the forest ecologies.

References
Badu-Apraku, B. and M. Oyekunle. 2012. Genetic analysis of grain yield and other traits of extra-early yellow maize inbreds and hybrid performance under contrasting environments. Field Crops Research 129: 99–110.
Badu-Apraku., B., M.A.B. Fakorede, M. Oyekunle, and R.O. Akinwale. 2011. Selection of extra-early maize inbreds under low N and drought at flowering and grain-filling for hybrid production. Maydica 56: 29-41.
Badu-Apraku, B., M. Oyekunle, R.O. Akinwale, and M. Aderounmu. 2013. Combining ability and genetic diversity of extra-early white maize inbreds under stress and non-stress environments. Crop Science 53: 9–26.
Badu-Apraku, B., M. Oyekunle, R.O. Akinwale, and A.F. Lum. 2011. Combining ability of early-maturing white maize inbreds under stress and nonstress environments. Agronomy Journal 103: 544-557.
Badu-Apraku, B., M.A.B. Fakorede, A. Menkir, A.Y. Kamara, and A. Adam. 2004. Effects of drought screening methodology on genetic variances and covariances in Pool 16 DT maize population. Journal of Agricultural Science 142: 445-452.
Betran, F.J., J.M. Ribaut, D. Beck, and De Leon D. Gonzalez. 2003. Genetic diversity, Specific combining ability, and heterosis in tropical maize under stress and nonstress environments. Crop Science 43: 797-806.
Bänziger, M., G.O. Edmeades, and H.R. Lafitte. 1999. Selection for drought tolerance increases maize yields across a range of nitrogen levels. Crop Science 39:1035-1040.
Wolfe, D.W., D.W. Henderson, T.C. Hsiao, and A. Alvio. 1988. Interactive water and nitrogen effects on maize. 11. Photosynthetic decline and longevity of individual leaves. Agronomy Journal 80: 865−870.
Yan, W. 2001. GGE Biplot- A windows application for graphical analysis of multi-environment trial data and other types of two-way data. Agronomy Journal 93: 1111-1118.
Yan, W. and J. Frégeau-Reid. 2008. Breeding line selection based on multiple traits. Crop Science 48: 417-423.

Helping smallholder farmers reap the most from drought tolerant maize

Florence Sipalla, f.sipalla@cgiar.org

At the first sign of the short rain season, farmers know that it is time to till the land and plant. In these harsh times, when rain is scarce, some farmers opt to plant before the rain comes to take advantage of every drop. James Mativo from Makaveti Village in Kyanzasu sublocation in Machakos County is one such farmer. He proudly http://iupatdc5.org displays a healthy crop to visitors, with green maize ready for plucking. “I planted just before the season began, to ensure that the crop would sprout when the rain came,” he explains.

For many farmers in the semi-arid Eastern Province in Kenya, preparing fields ahead of the rain is not enough to guarantee a good harvest. Having the right seeds is vital too. Mativo buys certified seeds, suited to the area’s climate, from Dryland Seed Company in Machakos town. “For these dryland varieties, the first rains are very important,” explains Peter Mutua, a Dryland agronomist. “It allows the farmers to take full advantage of this scarce resource from germination. This is particularly important as most farmers in Kenya grow maize under rainfed conditions, even in the semi-arid areas.”

Just as a relay race is a team effort, so is the process of delivering quality seeds to farmers. It takes many people, working together, to ensure that farmers get the best seeds suited to the climatic conditions in their locales. Take the case of drought tolerant maize varieties: the process starts with breeders who develop the germplasm and share it with research partners. They pass the baton to the seed companies who produce large quantities of the seeds which smaller-scale farmers buy from them. The companies cross-pollinate sources of desirable traits to develop maize varieties relevant to the farmers. Often they start with sources from public research organizations such as IITA and the International Maize and Wheat Improvement Center, known by its Spanish acronym CIMMYT.

“We try to improve the existing varieties and come up with more that are better than those in the market,” says Peter Setimela, a CIMMYT maize breeder. “With climate change, varieties developed 20 years ago are no longer suitable for the changing environment.” Breeders working under the Drought Tolerant Maize for Africa Initiative led by CIMMYT have developed varieties known as the Kenya Dryland Varieties (KDV) series. KDV 1–6 varieties were released to farmers by the Kenya Agricultural Research Institute (KARI), as well as Freschco and Dryland Seed Companies. The fourth variety of the series is the one now growing on Mativo’s quarter-hectare farm.

It is not only climate change that concerns breeders; they also want to develop varieties that are disease resistant and relevant to the farmers’ other needs – proper milling and cooking quality or flavor, for example. “This is why we have farm trials,” explains Peter Setimela. These trials are done in collaboration with the national research organizations, such as KARI in Kenya. “We look for those traits that farmers prefer. In Kenya, they like white maize for making ugali. In Zimbabwe, some people prefer ZM309 because it is sweet when roasted.”

The seed companies and KARI multiply seeds to furnish supplies adequate to the farmers’ demands, but they also depend on farmers they hire to produce those seeds. “We work with groups of farmers who each have at least 5 acres (2.5 ha),” says Ngila Kimotho, Managing Director of Dryland Seed Company. The seed company clusters the farmers by sublocation and trains them. This, according to Musa Juma, a contract farmer for Dryland in Kibwezi, Eastern Province, is “risk-free planting. This is because you are planting for a known market; as you plant, you don’t have to start worrying about where to sell the produce. An additional perk is that the company provides the seeds.”

Seed companies also use local demonstration farms to show the performance of various maize varieties, winning over farmers to the new varieties that outperform traditional ones. Dryland Seed Company also uses vernacular radio programs to disseminate information on the most productive varieties. “These are interactive shows. We have farmers calling in to find out the best variety to grow, when and where to obtain the seeds,” explains Kimotho. He said that farmers prefer open-pollinated varieties that are early-maturing and drought tolerant and thus better suited to planting in the short rains in the region.

“The basic need in the dry areas is food security,” says Kimotho, adding that farmers sell the surplus grain only when they have a rare bumper harvest. To cater for the diversified market, Dryland markets seeds in packets from 100 g to 1 kg, so there is an affordable option for every farmer. The 100 g package is popular with those who are keen to try out new varieties. “Even students buy it for their parents to try,” says Kimotho. Smallholder farmers, most of whom are women, also choose this option to ensure a subsistence maize crop for their families.

By the same token, farmers are reluctant to place all their trust in a single variety. On Mativo’s farm, he spreads the risk by planting hybrids alongside beans and cowpea. “When the rains are good, the hybrids do well and have high yields, but if the rains are not so good, I still have food from the KDV,” says Mativo. “It would be very sad for a farmer to lack food. When I have food, then my neighbors are also food secure.” Mativo uses ox-drawn plows on his farm, but he also occasionally employs a few manual laborers, some of whom he pays in kind with maize grain, at their request.

In the rare years that farmers get a bumper harvest, they need to sell the surplus. But when there is a plentiful supply, the price of maize is low, and storage becomes an even more vital component of the value chain: the grain requires a pest-free mechanism that also saves the http://dailykhabarnama.com/buy/ maize from fungal infections, some of which can produce deadly toxins.

Ultimately, every participant in this value chain, the relay race, is focused on one thing–food security. “Working with partners in the national agricultural systems and seed companies, the DTMA program aims to produce 70,000 t of seeds by 2016 with drought tolerant maize varieties in 13 African countries,” said Tsedeke Abate, the Program Leader based in Nairobi. He added that this is enough to plant about 2.8 million ha, an area equivalent to the farms of about 7 million smallholder households.

Dave Watson: Steering the MAIZE CGIAR Research Program

Dave Watson grew up on small family farm in northeast England. He has over 30 years of commercial farming experience. He has a BSc in Agricultural Botany from the University of Reading, UK, and an MSc and PhD in food system development from the University of Hull, UK. Throughout the 1990s, he taught courses on Sustainable Agriculture and Environment at the University of Hull. During the past 10 years, Dave has managed research-for-development partnerships in sub-Saharan Africa, first as program leader for innovative partnerships in the Innovation Systems Programme of the International Livestock Research Institute (ILRI) and more recently as Director for Project Development and Management at IITA. Major achievements include the adoption of innovation systems and value chain approaches in IITA. Key aims of his professional career include ensuring that agricultural research is demand driven and leads to significant development outcomes and impact.

The CGIAR Research Program on Maize (MAIZE) is a multi-center, multi-million dollar, multi-partner, and multidisciplinary program. Please describe your job as director of this program.
My responsibilities are to ensure the successful implementation of the program under the guidance of the MAIZE Management Committee and in coordination with partner institutions; contribute actively to developing effective research and development teams from diverse partner institutions; coordinate the development of impact-oriented, realistic workplans among project members and partners, and support their effective implementation, aligned with available resources and priorities; develop communication, M&E, and knowledge management strategies and facilitate their implementation in collaboration with other personnel; and coordinate partners’ assessment of research priorities to support resource allocation decisions and the development of effective research teams. I also ensure timely reporting required by the CGIAR Consortium and FUND Council; coordinate meetings; and execute agreements with major R&D partners and investors.

In which area do you see MAIZE making its biggest contribution?
I see MAIZE making its biggest contribution in three main areas:
Harnessing the comparative strengths of CIMMYT and IITA in the quest to ensure that MAIZE contributes as efficiently and effectively to human food security, nutrition and health, and the sustainable intensification of maize-based systems in target geographies across the developing world. This is the first attempt to create lasting synergies between CIMMYT and IITA across all areas of R4D.

Increasing collaboration between MAIZE and other key CGIAR Research Programs to ensure that investments in international agricultural R4D (IAR4D) are much better aligned and work collaboratively to address the needs of poor producers and consumers. This entails working more effectively in the same production geographies and value chains. Aside from the Challenge Programs (which were not as successful as envisaged), this is the first real attempt to foster synergies and reduce duplication of efforts across CGIAR. The key partnership that MAIZE is trying to forge is with the CGIAR Research Programs on Integrated Systems for the Humid Tropics (Humidtropics). Much discussion is under way to better align systems work under both programs.

Building partnerships between MAIZE and other partners to ensure that IAR4D directly meets the needs of beneficiaries, and to better align program outputs and strategies to achieve intermediate development outcomes (IDOs) through co-development of and facilitation of robust impact pathways.

This program involves more than 350 partners from the public and private sector. What would make the partnerships more effective?
About 85% of MAIZE is constituted by bilateral projects. These projects have their own partners who manage these partnerships to achieve project goals. Most of the 350 partners are involved in one or more of these bilateral projects.

Only 15% of funds are allocated through Windows 1&2 funding. These funds are being used to foster new and more strategic partnerships under MAIZE. Examples of strategic partnerships include work with (a) Royal Tropical Institute and Wageningen University on better harnessing Agricultural Innovation Systems thinking and improving performance of innovation platforms under MAIZE; (b) CGIAR Research Program on Agriculture for Nutrition and Health (A4NH) on aflatoxin mitigation in Asia; (c) University of Barcelona and Chinese Academy of Agricultural Sciences on developing low-cost phenotyping systems for developing country partners; (d) International Plant Nutrition Institute (IPNI) to develop decision support tools for maize cropping systems; and (e) small and medium enterprise seed companies to commercialize maize varieties produced by MAIZE.

To make partnerships more effective, it is important to develop shared goals and approaches to achieve these goals. This should be possible through the elaboration of impact pathways and the co-facilitation of IDOs. The second round of CGIAR Research Program proposals will necessitate the development of robust partnerships around achievement of IDOs.

What are your plans for disseminating and promoting knowledge generated through the program and ensuring the adoption of research results?MAIZE co-funds a senior knowledge management expert and a small team of knowledge management specialists in CIMMYT. I hope to work with the knowledge management specialists in CIMMYT and IITA to develop a knowledge management strategy and implementation plan. This strategy/plan will focus on innovative approaches to co-develop, disseminate, and promote knowledge. Greater adoption of research results will be achieved through the development of more robust impact pathways and associated theories of change and through more strategic partnerships.

What are some of the opportunities that MAIZE faces?
Opportunities include (a) Greater opportunities for creating synergies between CGIAR Research Programs and CGIAR centers; (b) Less duplication and uncoordinated overlap of efforts between CGIAR centers; (c) Greater opportunities for alignment of CGIAR center R4D objectives with those of national partners (public and private) in developing countries and with advanced research institutions; (d) Strengthening the relationship between CIMMYT and IITA; (e) Support for farming-systems focused innovation platforms; (f) Improved coordination of maize breeding efforts (including breeding for heat tolerance and doubled haploid technology); (g) Institutionalization of gender-sensitive approaches to maize R4D and more gender transformative research; (h) Enhanced capacity for rapid responses. For example the recent response to Maize Lethal Necrotic Virus in Eastern Africa facilitated with Windows 1&2 funds; (i) The MAIZE Management Committee (MMC) functions reasonably well; (j) The MAIZE Stakeholder Advisory Committee is established; (k) project administrators of MAIZE and WHEAT (CGIAR Research Program on wheat) are fully operational; (l) Competitive Partner Grant process & standard subgrant agreements (for all MAIZE partners); (m) Close to getting a timely program overview: Reporting 2012 templates & Traffic Light Progress Overview developed, Research Management System in CIMMYT is starting to work.

What are some of the challenges in coordinating and managing MAIZE?
Challenges include (a) lack of strong Strategic Initiative leadership; (b) lack of structured info/data/methods exchange across projects (Research Management System); (c) limited information on real time progress and insufficient time available to keep up with projects on the ground; (d) inadequate understanding of how MAIZE technologies lead to outcomes and impact; (e) communication and interaction downstream, among strategic initiatives, disciplines, and with partners; (f) MAIZE communication efforts are slow to get off the ground; (g) the MAIZE Partner Priority Survey has received only 30 responses to date; (h) how to involve partners earlier (program strategy review, strategic fundraising); (i) MAIZE is the 6th lowest funded program of 15. Investments need to be made to increase Windows 1&2 funding for MAIZE. Program Reporting template for 2012 (and 2013) only agreed with donors in March 2013; (k) communication of MMC members via Skype and e-mail is not always working and efficient.

What makes MAIZE different from the other CGIAR Research Programs dealing with commodities?
In many respects, MAIZE is very similar to the other CGIAR Research Programs that have a strong commodity focus. Indeed, to a large extent, building on these similarities was the purpose of the CGIAR reform. While recently working together in Cali, Columbia, many CGIAR Research Programs recognized resounding similarities between the IDOs that each program had worked on in relative isolation. Indeed, 15 programs were able to agree on 10 common IDOs. There is even greater scope for further collaboration between all CGIAR Research Programs.

Any advice to our scientists and specialists working on maize improvement and development?
Yes, we have some great scientists working on maize-based systems from both CIMMYT and IITA. We can achieve so much more working together than we can ever hope to achieve working independently.

Maize genetic improvement for enhanced productivity gains

Abebe Menkir (a.menkir@cgiar.org), Baffour Badu-Apraku, and Sam Ajala
Maize Breeders, IITA, Ibadan, Nigeria

Maize streak virus disease causes severe stunting and extreme yield reduction in maize. Creating Maize streak virus-resistant varieties is one of the major successes of IITA's maize breeding program. Source: L. Kumar.
Maize streak virus disease causes severe stunting and extreme yield reduction in maize. Creating Maize streak virus-resistant varieties is one of the major successes of IITA's maize breeding program. Source: L. Kumar.
Maize is an important food security and income-generating crop for millions of people in West and Central Africa (WCA). Maize breeding at IITA was initiated around 1970. Using as base materials two composites created from diverse sources in Nigeria under a West African project supported by the Scientific and Technical Research Committee of the Organization for African Unity, breeders at IITA formed several broad-based populations and improved them through recurrent selection. The main research focus at that time was the development of open-pollinated maize varieties (OPVs) with resistance to diseases, and adapted to the humid forest and moist savannas of WCA. The products generated from this research were channelled to research and development partners for further testing, multiplication, and dissemination in various countries in the subregion.

The widespread outbreak of the maize streak virus (MSV) disease in the late 1970s prompted IITA to develop two resistant populations. These were crossed to high-yielding and broad-based germplasm from the International Maize and Wheat Improvement Center, eastern and southern Africa, the temperate zone, central and south America, Thailand, DECALB, and other sources to create populations and varieties resistant to MSV. IITA has supplied MSV-resistant inbred lines, OPVs, hybrids, and populations to partners within and outside WCA through diverse delivery pathways for more than 25 years. Direct use of MSV-resistant maize germplasm that also had resistance to southern leaf rust, southern leaf blight, downy mildew, and leaf spot has been recorded in several countries in Africa.

The significant breakthrough in the development and release of high-yielding extra-early, early, intermediate, and late-maturing varieties with resistance to leaf rust, leaf blight, and leaf spot has caused a phenomenal increase in maize production in WCA, notably in Bénin, Burkina Faso, Cameroon, Chad, The Gambia, Guinea, Ghana, Mali, Nigeria, Senegal, and Togo. Further expansion in production has also occurred in many countries in this subregion because of the adoption of extra-early maturing improved varieties identified from regional trials coordinated by the Semi-Arid Food Grain Research and Development (SAFGRAD) and the West and Central frica Collaborative Maize Research Network (WECAMAN).

IITA maize breeders in action, maize breeding program. Source: L. Kumar.
IITA maize breeders in action, maize breeding program. Source: L. Kumar.
The development of extra-early maturing varieties enabled production to expand into new areas, especially to the Sudan savannas where the short rainy season hitherto had precluded maize cultivation. The highest growth in maize area, yield, and production in sub-Saharan Africa since 1961 occurred in WCA. These productivity gains, achieved through farmers’ adoption of improved varieties in the 1980s, were driven by the suitability of the cultivars to the major production environments, the availability of inexpensive fertilizer and extension services, as well as favorable government policies that encouraged the use of these technologies.

In a recent impact assessment study conducted in nine countries, the number of varieties annually released in WCA had increased from fewer than one in 1970s to 12 in the late 1990s. The availability of such high-yielding and adapted varieties resulted in a 2% annual increase in land area planted to maize and a 3.5% annual increase in grain yield from 1971 to 2005. Among the varieties released from 1998 to 2005 in the nine countries, 67% were derived from IITA’s maize germplasm. Of the 4 million ha planted to improved maize in these countries, about 43% of the area was planted to varieties derived from IITA’s germplasm. The joint IITA-NARS investment in maize research in the nine countries had lifted an average of 1.6 million people out of poverty annually from 1980 to 2004.

While working with diverse partners to promote the dissemination of maize varieties in the various countries, IITA realized that the major constraint to the adoption of improved varieties in WCA was the absence of an effective seed production and delivery system. To promote the establishment of indigenous private seed companies, IITA embarked on the development of hybrids in 1979 with financial support from the Federal Government of Nigeria and the active participation of Nigerian scientists. This led to the release of the first generation of hybrids in 1983, with a spill-over effect of the establishment of seed companies in Nigeria for marketing hybrid maize seeds. The official announcement of IITA’s maize OPVs and hybrids in the catalogs of indigenous seed companies in Nigeria provide further evidence of the adoption, deployment, and commercialization of IITA-bred varieties and hybrids.

In recent years, IITA has also made significant progress in the development of a large number of maize inbred lines, OPVs and hybrids with resistance to Striga hermonthica, stem borers, and aflatoxin contamination, with tolerance to drought, efficient nitrogen use, and enhanced contents of lysine, tryptophan, and pro-vitamin A. We have the first generation of extra-early, early, intermediate, and late-maturing OPVs and hybrids that combine drought tolerance with resistance to S. hermonthica developed under the Drought Tolerant Maize for Africa Project and supplied to partners for testing through regional trials. The number of drought-tolerant OPVs identified from these trials and released for production since 2007 were 7 in Bénin Republic, 5 in Ghana, 3 in Mali, and 13 in Nigeria.

On the other hand, only one drought-tolerant hybrid selected in Mali and six drought-tolerant hybrids selected in Nigeria were released for production. Furthermore, three varieties with high lysine and tryptophan content, two varieties resistant to S. hermonthica, two varieties that are nitrogen use efficient, a stem borer-resistant variety, two yellow and two white hybrids were released from 2008 to 2011 in Nigeria.

Maize production in Saminaka area in Kaduna State, Nigeria. Photo. by A. Menkir.
Maize production in Saminaka area in Kaduna State, Nigeria. Photo. by A. Menkir.
To accelerate the release and commercialization of hybrids with different maturity classes, high yield potential, combining resistance to Striga and drought tolerance, and other desirable traits in different countries in WCA, IITA has supplied parental lines of promising hybrids to private seed companies for further testing, production, and commercialization. The institute has also trained technical and management staff of seed companies to strengthen their human capacity to produce and market hybrid maize.

In addition, IITA has promoted community-based seed production schemes through its work with WECAMAN and more recently with diverse partners to make improved seeds available to farmers in countries where the private sector is less developed and in areas with limited access to markets.
Despite the impressive strides that have been made so far, continued investment in maize productivity research still remains critical to sustain agricultural growth, food security, improved nutritional quality, and safe harvests. Considering the predominance of the crop in diverse farming systems, heterogeneous landscapes, and the diets of millions of people in WCA, enhanced yield gains have the potential to further expand production in WCA, thus contributing to bridging the gap between food supply and demand in the region, because research has led to and will continue to deliver excellent results.

Increased investment not only in research but also in strengthening the private seed sector will still be needed to promote the rapid turnover of maize hybrids on farmers’ fields that help to achieve higher yield gains to support improved farming in WCA.