Archives of Current Research International

Wheat (Triticum aestivum L.) productivity is increasingly threatened by rising temperatures, particularly during the reproductive and grain-filling stages, posing a major challenge to global food security. Although heat tolerance is a critical breeding target, limited understanding of key morpho-physiological traits under thermal stress constrains the development of resilient genotypes. This study aimed to identify heat-tolerant wheat lines and determine the traits associated with yield stability across contrasting temperature regimes. Fifty wheat genotypes were evaluated during the 2019–2020 and 2020–2021 Rabi seasons at the Zonal Agricultural Research Station, Pawarkheda, Madhya Pradesh, under early (cool), normal (optimal), and late (terminal heat stress) sowing conditions using a randomized complete block design with three replications. Comprehensive data were recorded on phenological, physiological, and yield-related traits, including germination percentage, heading date, maturity duration, plant height, tillers per plant, grains per spike, spike length, canopy temperature, chlorophyll content, thousand-grain weight, and grain yield. Results showed highly significant (p < 0.01) genotypic differences across all environments for most traits, including germination percentage, heading and maturity duration, plant height, spike characteristics, thousand-grain weight, and grain yield, demonstrating substantial genetic variability. Pooled ANOVA confirmed significant effects of environments, genotypes, and genotype × environment interactions for nearly all traits, indicating differential adaptability and the impact of temperature regimes on trait expression. Analysis of variance revealed highly significant differences (p < 0.01) among genotypes and environments for most traits, with pronounced genotype × environment interactions, demonstrating substantial genetic variability and differential responses to temperature stress. Considerable variation in canopy temperature depression, chlorophyll retention, and key yield components identified several promising and stable genotypes under heat stress. These findings provide a strong foundation for future wheat improvement programs targeting heat-resilient cultivars adapted to warming climatic scenarios.