Unravelling the combined abiotic stress responses of wheat under heat and drought conditions

Abstract

Most of the wheat (Triticum aestivum L.) growing areas of the world experience environmental stresses including drought (moisture stress) and high temperature (heat stress) that adversely affect crop growth, development and yield. Water-deficit often combined with high temperature stress is the main abiotic factor limiting crop growth and development. The present investigation was performed to study the effect on yield and physiological and biochemical traits of different wheat genotypes under individual heat stress (HS) and drought stress (DS) and combined stress (HS + DS) conditions. Distinct from prior studies which predominantly utilised pot experiments, this investigation offers valuable insights derived from field conditions, thereby providing a more accurate assessment of crop performance under HS + DS. The field experiment conducted in plant phenotyping facility, a total of 60 experimental plots was maintained, comprising 5 genotypes, 4 treatments and 3 replications. Grain yield declined by 31.9 % under HS, 61.6 % under DS and 66.6 % under HS + DS relative to the control. Both individual and (HS + DS) stresses also impaired physiological functioning. The HS + DS treatment induced more pronounced damaging effects on root architecture as well than either stress alone, with reductions of 42.8 % in root volume, 27.8 % in root surface area and 32 % in total root length compared with the control. Overall, HS + DS was more damaging than the individual stress, however, the interaction effect might be due to cross adaptation effect. The genotype DBW-14 exhibited a high grain yield (270 g plot-1) under HS, DS and HS + DS conditions, indicating robust cross-adaptation mechanisms. Although genotype 11 HPYT433 demonstrated superior tolerance based on root parameters and relative water content (RWC), DBW-14 significantly outperformed all other evaluated genotypes in grain yield and overall physiological stability under the    HS + DS treatment. Consequently, DBW-14 serves as a promising donor line for breeding climate-resilient cultivars.