Phenotypic characterization of specific adaptive physiological traits for heat tolerance in wheat

Phenotyping for high temperature stress tolerance in the field presents a challenge due to its interaction with other environmental factors. High temperature stress is one of the devastating abiotic stresses, which severely affect various physiological and biochemical processes. An experiment was conducted for phenotypic characterization of specific adaptive physiological traits for heat tolerance in ten wheat genotypes under normal (timely sown) and terminal high temperature (late sown) environments. The rate of photosynthesis was significantly higher in varieties HUW 234, HD 2932, HD 2864 and WH 1124 under timely sown condition, which also synchronized with yield. Higher net photosynthesis contributed in translocation of photo-assimilates to developing sink. Under late sown condition, relative water content, membrane stability index was lower compared to timely sown condition in all the genotypes due to high temperature induced injury. Canopy temperature depression at 15 days after anthesis had significant positive correlation with grain yield under timely sown condition compared to late sown conditions. The reproductive attributes were significantly higher under timely sown condition compared to late sown terminal high temperature environment in all the genotypes. However, the genotypic variation clearly appeared under both the growing conditions. The genotypes HD 2932, HD 2864, HD 3095, HI 8703 and HUW 234 exhibited greater heat tolerance efficiency and sustained higher yield under prevailing high temperature conditions particularly at grain filling and development stages. © 2016, Indian Society for Plant Physiology.