ICRISAT scientists in India are testing a new generation of pearl millet that could expand the horizons for this poor man's crop in Asia and Africa. It is hoped that evaluations starting in the 1996 rainy season will confirm the readiness of new hybrids that have more durable heterogeneous resistance and visual uniformity acceptable to both farmers and seed companies. If the trials are successful the new hybrids could reach farmers as early as l998, crowning 24 years of efforts to improve what is already a miracle performed under environmental extremes.
Pearl millet is the only cereal that reliably provides grain and fodder under dryland conditions, on shallow or sandy soils with low fertility and low water holding capacity. In drier parts of Africa and Asia, pearl millet is the staple food grain. In more hospitable areas, it is fed to bullocks, milch animals and poultry.
While pearl millet farmers have managed to feed their families under harsh conditions for centuries, population growth is outstripping their capacity to meet new demand with ancient practices and landraces. Scientists need to know more about the crop's tolerances in order to boost yields and expand the land under cultivation in harsh environments where other crops are unsustainable.
India, which produces more than half the world's pearl millet, has been the center of research efforts to meet this challenge since the 1960s when the availability of cytoplasmic-genic male-sterile lines brought a succession of hybrids. Before ICRISAT was founded in 1972, most of the research was done by the Indian Council of Agricultural Research (ICAR) and other Indian organizations which raised yields to new highs. Since the mid-1960s, when hybrid pearl millets were first introduced in India, average grain yields have nearly doubled despite a considerable shift to more marginal production environments.
However, downy mildew of epidemic proportions soon exposed the limitations of the hybrids. While landraces with inherent genetic diversity survived the epidemic, genetically uniform hybrids failed. One of them (HB3) had been adopted widely in India but was devastated by downy mildew and had to be withdrawn from cultivation. Downy mildew (Sclerospora graminicola) is a fungus that can persist in the soil from one season to the next and spread rapidly from one plant to another by means of asexual spores.
Tens of millions of poor people depend on pearl millet and ICRlSAT turned to west and central Africa, the primary source of genetic diversity, for reinforcement. Open-pollinated cultivars, including WC-C75 and ICTP 8203, provided new resistance to downy mildew, increased grain yields and gave scientists time to develop new materials with even better yields and quality. Ten years after their introduction the reinforced crops remain resistant. More recently new materials have been introduced that show grain and stover yields which are at least 10 percent higher than those of the first generation of ICRISAT-bred earl millets, often combined with even shorter growth season requirements.
At the same time the first open-pollinated ICRISAT cultivars were introduced, single-cross hybrid cultivars including ICMH 451, ICMH 423, and ICMH 356 were bred using at least one African parent. Many other materials of Indian origin were crossed with African germplasm. F3 and F4 materials were used to derive hybrid pollen parents and parents of synthetic varieties. Screening techniques were developed at the ICRISAT Asia Center and other hotspot locations. Among the products generated and released are ICMS 7703, ICMV 155 and ICMV 221. Indian farmers experienced two further downy mildew epidemics during the 1980s and ICRISAT-bred materials withstood both.
Consolidating these gains, ICRISAT scientists have identified:
Molecular mapping has also expanded knowledge of downy mildew resistance. It has shown that:
Two decades of focused research with national agricultural research systems have also yielded screening techniques and cultivars resistant to the pearl millet grain-replacement diseases, ergot (Claviceps fusiformis) and smut (Tolyposporium penicillariae).
Sharing New Materials
Another major accomplishment of ICRISAT's pearl millet team has been the global diffusion of new materials. Efforts to incorporate drought tolerance led ICRISAT to a west African landrace called Iniadi which matures in 70-85 days, is well adapted to low soil fertility, resists diseases, and is especially tolerant of drought. Yields range from 0.8 to 2.5 t ha.
At Kansas State University in the United States, Iniadi has become a principal exotic germplasm source because of its earliness even at latitude 39 degrees N. Two male-sterile lines developed from Iniadi materials---843A (ICMA 2) and 842A (ICMA 3)---were recommended by the Indian national program for general use as seed parents. Today, at least half of all hybrids marketed by India's private sector, are produced from these lines.
It has been conservatively estimated that the annual returns to India's farmers from pearl millet varieties developed by ICRISAT total $50 million---more than 12 times the cost of its investment in pearl millet research.
A virtuous cycle of collaboration has been completed which started in Burkina Faso in 1979, when Iniadi, a local landrace, was taken to India. Okashana 1, a variety based on Iniadi germplasm but not identical to the landrace from Burkina Faso, grown on a demonstration plot at the ICRISAT Asia Center, was selected for trials in Zimbabwe. From there it was taken to Namibia where it was released in 1990 and enthusiastically adopted by farmers. Okashana 1 is now the most popular variety in Namibia, the only non-Sahelian country where pearl millet is the cereal of choice for consumers. In 1991, Okashana 1 was introduced to Chad for trials and is likely to be planted on more than 100,000 ha within two years. It is also being widely grown in Mauritania and Benin.
ICRISAT's long range goal is to explore the potential of pearl millet in chronic drought-prone areas of southern Africa and non-traditional environments such as South America. Maize is preferred by consumers in both places, but in southern Africa in particular, the hardy pearl millet could dramatically improve farmers' prospects for food security.
(25 Years of Food and Agriculture Improvement. CGIAR 1971-1996)