Qtl Analysis For Shoot Fly Resistance In Sorghum [ Sorghum Bicolor (L.) Moench]

Sorghum [Sorghum bicolor (L.) Moench] is the fifth most important cereal crop worldwide (FAO, 2004) and, together with maize and pearl millet, it constitutes the most important cereal crop for the semi-arid tropics (SAT). Sorghum grain is produced annually as the dietary staple for millions of people in semi-arid areas of Asia (mainly India and China) and Africa where drought stress causes frequent failure of other crops. India is major producer of sorghum, with the crop occupying an area of 9.90 million hectares with an annual production of 8.00 million metric tones during 2003 - 2004 (FAS, 2005). The genetic manipulation of the sorghum crop since the 1960's has lead to development of several high yielding varieties and hybrids. Faced with occurrence of biotic and abiotic stresses, the realization of the increased yield potential is low. One of the most important biotic constraints to sorghum production in India is shoot fly (Atherigona soccata Rond.). This insect attacks the sorghum at seedling stage (18 - 30 days after emergence). Infestation rates are higher in late-sown kharif (rainy season) and early sown rabi (post-rainy season) sorghum crops. The levels of infestation even may go up to 90 - 100 per cent (Usman, 1972). The losses due to this pest have been estimated to reach as high as 85.9 per cent of grain and 44.9 per cent of fodder yield (Sukhani and Jotwani, 1980). The annual losses in sorghum production due to shoot fly in India have been estimated at nearly US $200 million (ICRISAT, 1992).