ABSTRACT
India ranks fi rst in terms of area (27.8 mha) under wheat cultivation and second after China in terms of production (93.9 mt), which is approximately 12% of the total world’s wheat production (AICRP Progress report, Crop Improvement, DWR, 2011-12). During last 50 years, signifi cant improvement in wheat production and productivity was achieved through exploitation of major genes for traits like dwarfness, photoperiod insensitivity and resistance to biotic stresses (Reynolds and Borlaug 2006). However, it is estimated that to maintain self-suffi ciency for wheat in India, annual production of wheat and rice together should increase by 2 mt every year (Bhalla et al. 1999). The demand of wheat in 2020 is estimated to be ~87.5 mt (Chatrath et al. 2006; Joshi et al. 2007) to ~109 MT (Sharma et al. 2002; Nagarajan 2005). The abiotic stresses, particularly drought, contribute signifi cantly to the poor productivity of wheat in India. Nearly 80% wheat in India is cultivated under irrigated conditions and the remaining 20% is grown under rainfed environments (Reynolds et al. 1999). Even under irrigated conditions, 66% wheat receives only partial (1-2) irrigations (Joshi et al. 2007), subjecting the wheat crop to water stress leading to reduction in grain yield. It is recognised that globally, almost 50% of the wheat cultivated in the developing world (50 million ha) is sown under rainfed systems that receive less than 600 mm of rain per annum, the rainfall being less than 350 mm per annum in areas inhabited by the poorest and most disadvantaged farmers of the developing countries (CIMMYT 2005). Approximately 70% of the area sown to wheat in developed countries and half in developing countries suffer from periodic drought, which can occur at any time during the cropping cycle in all the rainfed environments (Trethowan and Pfeiffer 1999). Besides lower yields in rainfed cultivation due to inadequate soil moisture, availability of inadequate water for irrigation as a result of receding water table (Rodell et al. 2009) is also negatively impacting wheat production in India.
