Genetic enhancement of pearl millet and sorghum for the semi-arid tropics of Asia and Africa

Abstract

Sorghum (Sorghum bicolor (L.) Moench) and pearl millet (Pennisetum glaucum (L.) R. Br.), ranking fifth and sixth in global cereal hectarage, respectively, are the most important coarse-grain cereals in the semi-arid tropical regions of Asia and Africa. Pearl millet displays better adaptation to and is grown in relatively more marginal environments than sorghum. Under subsistence farming conditions, both crops have low grain yields (0.5-0.7 t·ha-1 for pearl millet and 0.7-0.9 t·ha-1 for sorghum), although improved hybrid cultivars give 3-4 t·ha-1 of realizable grain yields in better-endowed environments. African germplasm, especially Zera Zera sorghums from the Sudan-Ethiopian border in eastern Africa and Iniari pearl millets from the Togo - Ghana - Benin - Burkina Faso region of western Africa, has proved most useful for the genetic improvement of these crops. The greatest impact of improved cultivars (mostly hybrids) has occurred in India, where the area under high-yielding varieties (HYVs) increased from 6% for pearl millet and 3% for sorghum in the triennium 1968-1970 to 53% for pearl millet and 54% for sorghum in the triennium 1992-1994. During the same period, productivity of both crops increased by 59%, which is attributable to both genetic improvement and management factors. HYVs have now started to be adopted in some of the African countries as well (e.g., Chad, Cameroon, Botswana, and Zimbabwe for sorghum; Chad, Namibia, Zambia, and Zimbabwe for pearl millet). The availability of vast untapped genetic resources and continuing yield gains indicate that there are good prospects for future genetic improvement in the productivity of these crops, which can be accelerated with the application of biotechnological tools. Sorghum and pearl millet will continue to be important food crops in their traditional semi-arid tropical areas. Sorghum is already an important feed crop in the developed world and pearl millet has the potential to become an even better feed crop, as it has higher protein content and a better amino acid profile than sorghum. The nutritional value of both crops for food and feed use can be further improved by breeding. Also, through genetic enhancement, there exist opportunities for the development of sorghum and pearl millet cultivars suitable for alternative uses in the bakery and beverage industries.Key words: sorghum, Sorghum bicolor, pearl millet, Pennisetum glaucum, genetic enhancement, semi-arid tropics, Asia, Africa, cultivars, impact.