IMPACT OF CLIMATE CHANGE ON YIELDS OF MAJOR FOOD CROPS IN INDIA

摘要

The regional models of yield response to temperature (minimum, maximum and its diurnal range) and precipitation developed for meteorological (met) sub-divisions of India were used to study the impact of future climate change on major food crops viz. wheat, rice, potato and rapeseed-mustard. The area weighted averages of district-wise crop yield data were computed at met sub-division level for 1977-2007 for 9 major wheat (Triticum aestivum L.) producing met sub-divisions, 16 major rice (Oryza sativa L.) producing met subdivisions, 6 major potato (Solanum tuberosum L.) growing sub-divisions of and 8 major rapeseed-mustard (Brassica spp.) growing subdivisions. Fortnightly correlation weighted weather parameters like minimum and maximum temperature and precipitation for the respective met sub-division and periods of the crop season were used to develop the empirical relationships. A negative response of yields to increased minimum temperatures was observed for all the crops. In general, the reduction in crop yields upto 13.4 percent was observed with unit increase in minimum temperature. The crop yield also showed negative response to increased maximum temperature and its unit increase reduced the yields upto 10.3 percent and 5.3 percent for rice and wheat crop, respectively. The crops like potato and rapeseed-mustard showed positive response to increased maximum temperature, which might be due to their strong positive correlations with diurnal temperature range (DTR). The estimated impacts of diurnal temperature range (DTR) changes on yields were generally less (< 5percent change in yields) for wheat and rice crops while more upto 8.6 percent for potato and rapeseed-mustard crops. Based on A2 scenario of temperature and precipitation change, as derived from PRECIS (Providing Regional Climates for Impacts Studies) regional climate model, it was found that, during the period 2071-2100, the rice yields in irrigated regions would reduce upto 32 percent in Haryaana followed by 18 percent in Punjab while it may increase in rainfed regions upto 28 percent in Orissa followed by 18 percent in Madhya Pradesh. The reduction in wheat yields will be 21 percent in East Rajasthan followed by 18 percent in West Rajasthan and 14 percent in East Madhya Pradesh. The climate change scenario may lead up to 39 percent reduction in rapeseed-mustard and 19 percent reduction in potato yields. However, the yield change projection uncertainties were large due to the uncertainties associated with the yield model.