Impact of high night temperature stress on different growth stages of wheat

Abstract

Increasing temperature especially the High night temperature (HNT) is a major constriction for sustaining global food production under changing climate scenario. Recent climate change has resulted into events of abrupt night temperature rise either throughout the crop period or at specific growth stage. Historical temperature observations and model projections have predicted a more pronounced increase in night temperature [minimum temperature (Tmin.)] compared to that of day temperatures [maximum temperature (Tmax.)]. Hence, the present study was carried out to identify the most critical growth stage affected by HNT and their effects on physiological, growth and yield traits of wheat. A unique field-based movable temperature controlling system was designed to enhance the night temperature by 5 °C than ambient temperature. The three critical phenological stages of wheat i.e. at GS 15 (before tillering initiation), GS 45 (booting) and GS 75 (grain filling) of Zadok’s scale were separately subjected to HNT treatment. The results reveals that GS 75 (grain filling) was the most sensitive stage affected by HNT, which has recorded remarkable reduction in grain yield (GY), Harvest Index (HI), Thousand grain weight (TGW) and grain weight per spike (GWPS) compared to control treatment. Pearson correlation analysis showed that breeders can choose lines with higher TGW, GWPS and grain number per spike (GNPS) for obtaining better GY under HNT conditions and vegetative/booting stage HNT in field condition may not attribute for any significant yield loss.