The screening of drought resistance in winter wheat in semi-arid rainfed regions based on an integrated evaluation system of stomatal traits

Climate change has intensified the risk of drought stress in winter wheat production across semi-arid rainfed regions, underscoring the need to establish an efficient and accurate evaluation system for drought resistance to ensure regional food security. This study aimed to elucidate the regulatory mechanisms by which flag-leaf stomatal traits influence water use efficiency and yield formation, and to construct an integrated drought-resistance evaluation framework based on stomatal characteristics. Using multi-genotype winter wheat materials, stomatal density, stomatal morphology, and related photosynthetic physiological parameters were systematically measured through multi-season field experiments. Variance analysis, correlation analysis, principal component analysis, and the membership function method were employed to determine the effects of genotype, environment, and their interactions on stomatal trait variation and to identify core phenotypic indicators driving drought adaptation. The results showed significant differentiation among genotypes in stomatal configuration, photosynthetic capacity, and agronomic traits, with stomatal traits exhibiting a clear pattern of coordinated variation; the “small-and-dense” stomatal configuration was strongly associated with higher water use efficiency and stable yield performance. The integrated evaluation system effectively distinguished genotypic differences in drought adaptability and identified superior drought-resistant cultivars. Overall, the proposed stomatal-trait-based evaluation framework provides a practical technical approach for drought-resistant breeding in semi-arid rainfed regions and offers a theoretical basis for future crop phenotypic improvement and germplasm screening under increasing drought stress.