Changes in thermal requirements, growth and yield of wheat under the elevated temperature

A field experiment was conducted inside a temperature gradient tunnel (TGT) at the ICAR-Indian Agricultural Research Institute, New Delhi during rabi 2014-15 to quantify the impacts of elevated temperature on thermal requirement, growth and yield of wheat crop. Wheat crop was subjected to five temperature treatments, i.e. +0ºC (representing ambient condition), +0.9ºC, +2.5ºC, +2.8ºC and +3.5ºC.Temperature elevation of 3.5°C increased accumulated growing degree days (GDD) and photo-thermal unit (PTU), thereby hastening maturity of the crop. Leaf area index (LAI) of the crop was affected most by the high temperature at the anthesis stage. Temperature elevation by 2.5°C and above significantly reduced the LAI of wheat. Grain weight decreased by 17.1%, while the straw weight reduced by 10.5% with temperature elevation of 3.5°C. Temperature elevation by 2.5°C and above significantly reduced the straw weight, but grain weight of wheat got significantly reduced even with 0.9°C elevated temperature. Reduced number of spikes per/m2 and number of grains/spike decreased grain yield. In fact, the increase in the spikelet sterility contributed towards the grain yield reduction. The information generated from this study will help in developing the appropriate management practices for production of wheat crop.