SIMULATING THE IMPACT OF WITHIN SEASON VARIABILITY IN TEMPERATURE ON GRAIN YIELD OF WHEAT

Within season variability in temperature is a major bottleneck in wheat productivity. This simulation study aimed to evaluate the effects of temperature variability on grain yield of two cultivars of wheat (cv PBW 621 and HD 3086) sown under different dates (early, mid and late) using two dynamic crop simulation models (CERES-Wheat and INFOCROP model) for two locations (Amritsar and Ludhiana). The temperature was increased and decreased by 1.0 to 2.0oC for Amritsar and 1.0 to 3.0oC for Ludhiana from normal during three growing periods, i.e., the whole season, vegetative phase, and reproductive phase. In Amritsar the CERES-Wheat and INFOCROP model predicted that with the increase in temperature by 1.0 to 2.0oC from normal during the vegetative phase, the grain yield may decrease by 0.36-15.23 % and 3.61-19.54 % respectively, during the reproductive phase the grain yield may decrease by 0.67–8.64 % and 3.18-26.76 % respectively and during the whole season the grain yield may decrease by 1.52-27.10 % and 1.91-24.10 % respectively.  Among the two cultivars of wheat, cv HD 3086 at both locations performed better under thermal stress environments as compared to cvPBW 621. However, the InfoCrop model predicted that cv PBW 621 performed well in comparison to cv HD 3086 at Ludhiana conditions with an increase in temperature up to 3°C. The simulation results showed that mid November sowing of wheat was better able to counteract the negative impacts of an increase in temperature on wheat as compared to early (October) or late (December) sowing dates