Genotypic variation and yield stability of bread wheat under induced field heat stress during grain-filling for climate resilience in arid regions

Climate change causes frequent periods of heat stress that threaten global wheat production and food security. High temperatures, particularly during grain-filling stage, shorten filling duration and reduce grain yield. Therefore, this study aimed to evaluate the performance, heat stress tolerance, and yield stability of 35 bread wheat genotypes under normal and heat stress conditions during two consecutive growing seasons. Field experiments were conducted under six environments created by varying heat stress duration using plastic tunnel covers (two and four weeks) compared to control plots. Yield components, including number of grains per spike, 1000-grain weight, grain weight per spike, and grain yield, were measured. Heat stress significantly reduced all yield traits, with the greatest relative losses occurring for grain yield and grain weight per spike. Substantial genotypic variability was observed, and genotype-by-environment interaction effects were highly significant. Advanced statistical models, including AMMI1, AMMI2, GGE dendrogram, and hierarchical clustering, were employed to dissect genotype performance and stability across heat treatments and seasons, revealing significant variations in tolerance and adaptation. Dendrogram, heatmaps, and stability analyses identified genotypes with broad adaptability and yield stability under thermal stress. The advanced lines G11, G13, G15, G16, G29, and G25, and G32 exhibited superior heat tolerance and stable high yields. Significant positive correlations among grain yield traits were observed under normal and short-term heat stress. However, prolonged heat stress disrupted these relationships, weakening the association among yield components, which indicates detrimental impact of extended thermal stress on wheat yield formation. The results of this study provide valuable insights into wheat genotypic responses to heat stress and identify promising genotypes for breeding, aiming to improve wheat productivity and sustainability under increasing temperature pressures in arid agroecological zones.