Integrative analysis of yield and physiological responses of wheat genotypes under drought and heat stress across diverse environments

BACKGROUND: Drought and heat stress increasingly threaten global wheat (Triticum aestivum L.) production, posing major challenges to food security and sustainable agriculture. Identifying genotypes that combine high yield potential with physiological resilience across diverse environments is essential for developing climate-smart wheat cultivars. The objective of this study was to identify high-yielding and physiologically resilient wheat genotypes with stable performance across diverse environments under drought and heat stress using multivariate and multi-trait analytical approaches. METHODS: Forty-nine wheat genotypes comprising 43 promising breeding lines (G1-G43) and six released checks (G44-G49) were evaluated across eight locations representing distinct mega-environments during the 2022-23 Rabi season. Trials were conducted under normal (N), drought (D), and late-sown heat (H) conditions. Grain yield, biomass, and key physiological traits were analyzed using multivariate approaches and multi-trait indices to assess genotype performance, stability, and adaptability under drought and heat stress conditions. RESULTS: Highly significant (p ≤ 0.001) effects of genotype, environment, and genotype × environment (G×E) interaction were observed for all traits. Mean grain yield declined from 6.5 t ha⁻¹ under normal conditions to 4.5 t ha⁻¹ (-31%) under drought and 5.0 t ha⁻¹ (-23%) under heat stress. Genotypes G7 (6.23 t ha⁻¹), G13 (6.15 t ha⁻¹), G8 (5.93 t ha⁻¹), G9 (5.92 t ha⁻¹), G4 (5.91 t ha⁻¹), and G36 (5.88 t ha⁻¹) outperformed the best check G47 (5.80 t ha⁻¹) by 1.5-7.2%. Biomass ranged from 17.2 to 17.5 t ha⁻¹ under normal conditions, with reductions of 17-30% under stress. Physiological traits showed declines of 11-28% in Normalized Difference Vegetation Index (NDVI) and 8-12% in chlorophyll content, along with increases of 14-23% in canopy temperature. Genotype-specific advantages included higher chlorophyll content and grain number in G13, superior biomass and kernel weight in G7 and G8, and lower canopy temperature in G9. Multi-trait indices consistently ranked these genotypes among the most stable across environments. The Genotype + Genotype × Environment (GGE) biplot analysis identified three mega-environments, with E18 (Indore-H) being both highly discriminative and representative. CONCLUSIONS: The integration of multivariate and multi-trait analyses effectively enabled the identification of high-yielding and physiologically resilient wheat genotypes under drought and heat stress. Genotypes G7, G8, G9, and G13 demonstrated stable and superior performance across environments, making them promising candidates for developing climate-resilient wheat ideotypes. This integrative approach provides a robust framework for sustainable wheat improvement under future climate scenarios.