Sorghum, Sorghum bicolor (L.) Moench, is known under a variety of names: great millet and guinea corn in West Africa, kafir corn in South Africa, dura in Sudan, mtama in eastern Africa, jowar in India and kaoliang in China (Purseglove, 1972). In the United States it is usually referred to as milo or milo-maize (Table 1). Sorghum belongs to the tribe Andropogonae of the grass family Poaceae. Sugar cane, Saceharum officinarum, is a member of this tribe and a close relative of sorghum. The genus Sorghum is characterized by spikelets borne in pairs. Sorghum is treated as an annual, although it is a perennial grass and in the tropics it can be harvested many times.
Sorghum is the fifth most important cereal crop in the world in terms of production and harvested area. This drought-tolerant crop is grown on 45 million hectares, with 75% of the area concentrated in ten countries: Sudan, India, Nigeria, Niger, USA, Mexico, Ethiopia, Burkina Faso, Mali and Chad. Sorghum is a staple crop in Asia and Africa, and is grown for both food and industrial purposes.
Sorghum cultivation emerged with cattle herding as an adaptation to the dry conditions of the Sahel. The earliest archeological evidence of the use of sorghum by humans is dated at about 9000 BP, and was found in the border between Egypt and Sudan. Sorghum has been used as a model to study the influence of cultural factors in shaping the genetic composition and the geographical distribution of crops. This is particularly relevant to understand how traditional seed-exchange systems work, and therefore to find efficient ways to diffuse improved varieties.
The global strategy for the ex situ conservation of sorghum identifies three major germplasm collections based on their sampling of crop diversity, availability of characterization and evaluation data, and accessibility and availability of material and related information: ICRISAT, USDA-ARS and the National Bureau of Plant Genetic Resources in India. Genesys maintains information on almost 100,000 accessions, including those held at the USDA-ARS genebanksand ICRISAT.