Sensitivity of Crop Water Requirements to Elevated Temperatures in Arid Rajasthan

摘要

The impacts of elevated temperatures of 1 to 4°C on crop water requirements of major crops of arid Rajasthan have been studied. The seasonal crop water requirements were estimated by multiplying daily potential evapotranspiration (PET) with crop coefficients obtained from long-term lysimetric experiments conducted in the region. The daily PET was computed using modified Penman-Monteith equation with daily normal meteorological parameters. The spatial variation in daily PET in the region ranged from2 mm in winter to 12 mm in summer and the annual PET varied between 1502 mm at Nagaur to 2221 mm at Jaisalmer. Water requirement of different crops in the region varied from 308 to 411 mm for pearl millet, 244 to 332 mm for clusterbean, 217 to 296 mm forgreen gram, 189 to 260 mm for moth bean, 173 to 288 mm for wheat and 209 to 343 mm for mustard. Further, a rise of 4°C in air temperature owing to global warming, increases ET requirement of arid zone crops over that of present level by 12-13% for kharif and 17-19% for rabi crops.