Pearl millet is a coarse grain cereal annually grown on the Indian subcontinent and in Africa, primarily for its grain and secondarily for its stover that is variously used as fuel, fencing and roofing material (Rachie and Majmudar 1980). In the USA, Australia and South Africa it is grown as a warm-season forage crop.
India accounts for 10.5 million ha out of the total area of 11.2 million ha annually planted to pearl millet on the Indian subcontinent. In western Africa, 17 countries grow pearl millet on 10.8 million ha, but the five major countries accounting for 90% of the total area are Niger (3.5 million ha), Nigeria (3.2 million ha), Burkina Faso (1.1 million ha), Mali (1.0 million ha) and Senegal (0.9 million ha).
BOTANY AND DISTRIBUTION
Pennisetum, the largest genera in the tribe Paniceae, consists of more than 140 species (Clayton 1972) and is divided into five sections: Gymnothrix, Eu-Pennisetum, Penicillaria, Heterostachya and Brevivalvula. The genus includes both annuals and perennials, sexual and asexual reproduction, and apomictic species. Species have large variation in chromosome number, 2n=10 to 2n=72, in multiples of 5, 7, 8 and 9 (Table 17.1). The lowest chromosome number (2n=2x=10) occurs in P. ramosum (Hochst.) Schmeinf. Those with x=7 chromosomes include cultivated pearl millet, its wild and weedy subspecies, P. schweinfurthii Pilger (2n=2x=l4) and P. purpureum Schumach. (2n=4x=28). Pennisetum massaicum Stapf (2n=16 and 32) is the only known species with x=8. All other species have x=9. Pearl millet belongs to the section Penicillaria.