Unraveling the association of physiological traits controlling grain yield under moisture stress and diversity analysis in durum wheat germplasam using Principal component analysis

Drought stress is a major abiotic constraint affecting the productivity of durum wheat ( Triticum turgidum subsp. durum ), particularly in arid and semi-arid regions. Our study evaluated core collection of two hundred and twenty durum wheat germplasm lines, with five standard check varities during Rabi 2024 and 2025. Contrasting moisture regimes was maintained in the experimental site for comparative analysis stress vs. non-stress conditions to dissect physiological, morphological, and seedling traits associated with moisture stress. Pooled analysis showed significant variability for physiological traits, including chlorophyll content (SPAD), membrane stability index (MSI), canopy temperature (CT), root-to-shoot ratio (RSR), and grain yield under moisture stress. Moisture stress during reproductive stage (45–60 days after sowing) led to pronounced reductions in grain yield (26.8%), seedling vigor (up to 57.3%), and membrane stability (24.8%), while increasing canopy temperature and RSR. Correlation analysis revealed strong positive associations between grain yield and SPAD, MSI, and seedling vigor under stress, while PCA partitioned and identified the important traits contributing for drought adaptation. Hierarchical clustering and principal component analysis enabled the identification of divergent genotypic groups and high-performing lines, notably UASDWG_246, UASDWG_216 and UASDWG_299, which consistently exhibited superior grain yield performance across both seedling and reproductive stage moisture stress. These results highlight the value of integrating multistage phenotyping and multivariate analyses for improving selection strategy of parents and utilizing them in pre breeding and drought resilience breeding program.