Peer review

Over large wheat growing areas of India, a rise in minimum temperature (Tn) is occurring at a faster rate (@ 0.32 °C 10 yr−1) than maximum temperature (Tx) (@ 0.28 °C 10 yr−1). During February, coinciding with post-anthesis period of wheat, about 79.4% area showed significant warming in Tn (@ 0.37 °C 10 yr−1) for 1970–2012 period. Indian wheat yields were observed to be prone to continual heat stress and especially to short-term temperature extremes. Wheat yields appear to be becoming more sensitive to Tn, especially during post-anthesis period. Mean wheat yields for the period 1980–2011 declined by 7% (204 kg ha−1) for a 1 °C rise in Tn. Exposure to continual Tn exceeding 12 °C for 6 days and terminal heat stress with Tx exceeding 34 °C for 7 days during post-anthesis period are the other thermal constraints in achieving high productivity. Improved understanding from this study on the role of Tn during post-anthesis period may further reduce the uncertainties in anthropogenic climate change assessments on Indian wheat yields. There is a need to consider inclusion of early maturing, high yielding and heat tolerant wheat lines in the breeding program for Indian conditions. Thermally sensitive areas evolved from this study may guide the researchers to identify such wheat lines for their adaptability in to future climates.

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