Sorghum Genetic Resources in Africa.

Sorghum is a major African cereal which has a wide range of utilizations including a staple food for millions of Africans. It is the dominant cereal in the Sahel and Ethiopian region where the re cent drought and crop failures have entailed massive famine. It is now well established that the crop was first domesticated in Africa. All of the cultivated and weedy races and varieties of the crop are found in the continent. Of all the regions of the world. Genetic diversity in the sorghums is greatest in the African continent. The threat of genetic erosion in sorghum in Africa as a result of expansion of new uniform cultivars and hybrids has not been as great as in the other major cereals. Cyclical droughts and crop failures have probably been the major causes of genetic erosion in sorghum in Africa. The major sorghum producing African countries save a few have been reasonably well collected ICRISAT is now t he major depository of he world sorghum collection. There are gaps, both taxonomically and geographically in the presently available world sorghum collection. Collections to fill these gaps must be undertaken now before t he available genetic resources in sorghum are further eroded. In the semi-and African context, sorghum (Sorghum bicolor(L.) Monench) is the leading food grain. It is the staple grain of millions of Africans from East to West and to a lesser extent from North to South The bulk of the grain is used in making different types of fermented and unfermented bread and also porridge. To a limited extent particularly in South Africa, the grain is also used as poultry and livestock feed. Another wide spread use of the sorghum grain in the continent is in making home brewed alcoholic drinks. In about the hard dough staged in some areas, the fresh whole grain is roasted and consumed by people. The leaves and stalks are commonly fed to livestock. In parts of the continent where tall and hefty stalked sorghums are grown, the stems are used for construction of houses and also for fuel. The green stalks of the juicy and sweet types are commonly chewed ike sugar cane. Of all the major cereals, sorghum is perhaps most deeply rooted in the cultures and tradition of the peoples of Africa. In much of Africa, the crop is under traditional and subsistence agricultural. It is associated with the drier and hotter parts of the continent where growing environments are marginal for other cereasl such as maize. It is the dominant cereal in the Sahel and Ethiopian region where the recent droughts and crop failures have entailed massive famine and claimed thousands of lives. It is now ell established t hat the crop was first domesticated in Africa. In different parts of the continent, all of the cultivated and weedy races and varieties of the crop are found. Doggett (4) concludes that the crop was fist domesticated in Vavilov's (11) Abyssinian center of origin of cultivated plants. This center roughly covers the north-east quadrant of Africa where both cultivated and wild sorghum are found in greatest variability. On the basis of detailed study of the extensive distribution of the wild relatives of cultivated sorghum in Africa, de Wet and Harlan (3) also conclude that the crop must have been first domesticated on this continent. Based on reported cultivation of sorghum in China at the beginning of the Christian Era, de Wet and Harlan suggest that the crop must have been domesticated at least 2000 years ago (3). The best archeological evidence on the antiquity of sorghum cultivation takes the crop to about the end of the second century A.D. Clark and Stemler (2) found sorghum grains in a storage pit used by the people of Central Sudan which carbon dated to about 200 A.D. Such a storage pit for sorghum is used widely throughout the north-east quadrant of Africa even today. Stemler et al (9) suggest that none of the cultivated r aces of sorghum was domesticated in present day Ethiopia. With particular reference to durra sorghums, on the basis of history of the Galla (correct designation is Oromo) People, according to them Ethiopians who grow durra sorghums, they concluded that durra sorghums were introduced from India to Ethiopia with the advent of the Islamic conquest (9). However, writing-off this region as the possible center of evolution of the durra race at least, just on the claim that it is associated with the Oromo people only in Ethiopia appears misleading. There appear to be more non-Oromo Ethiopians growing durra than Oromos. What is more, the early cultivators of cereals including durra sorghums in Ethiopia are the northerners who are entirely non-Oromos. It appears more likely that the Ethiopian durra moved from the northern part to the southern than from across the Red Sea and the Indian Ocean. Whatever the true geographical region for the domestication of each of the cultivated races of sorghum is,` the north-east quadrant of Africa contains perhaps the greatest genetic diversities of the crop.