Estimating wheat productivity for north western plain zone of India in relation to spatial-thermal variation

The study aimed at quantifying the interaction of exposure of wheat to high thermal stress for a specific duration during the reproductive stage with yield over north western plain zones of India. Thermal stress duration of at least of continuous five days, where average daily temperature positively depart by >= 2 degrees C above long term normal were correlated with annual wheat yield, for two phenological stages, viz, late vegetative and reproductive, under the most ideal location, i.e. Ludhiana, and were extended to estimate yield in other locations through introduction of a thermal response factor. In the reproductive stage a 10 per cent reduction from the average yield was expected in 10 days of thermal stress for Hisar, 13 days for Karnal and 15 days for Kanpur if exposed to average stress temperature departure of above normal (4.20, 3.63 and 3.54 degrees C, respectively). Findings suggested that the locations with relatively cooler thermal regimes experience proportionately higher yield loss compared to relatively warmer places for same amount of thermal stress exposure. Besides, achievable wheat production in India may be limited by 1.170 to 2.392 million tonnes every year, if climate change scenarios. are taken in to consideration. This simple procedure may be useful in estimating wheat yield in relation to spatially variable atmospheric thermal regime in spite of complexities and uncertainties involved in actual farm productions.