Phenotypic Screening for Drought Tolerance in Algerian Bread Wheat (Triticum aestivum L.) Genotypes under Semi-Arid Conditions

Bread wheat production in semi-arid regions is strongly constrained by environmental variability, particularly drought stress, which limits yield stability. This study evaluated the agro-morphological performance, yield components, and stress tolerance of 55 bread wheat genotypes in six different rainfed environments defined by three locations in northeastern Algeria over two cropping seasons (2021–2022 and 2022–2023), using an augmented block design. The combined analysis of variance showed highly significant effects of environment and genotype for all traits, while genotype × environment interactions were trait-dependent, being significant for spike length, thousand-kernel weight, and aboveground biomass. Environmental effects accounted for the largest share of total variation (38.76 to 81.80%). Substantial phenotypic variability was observed, with moderate to high broad-sense heritability (36.59 to 79.24%), indicating reasonable selection prospects despite pronounced environmental influence. Correlation analyses revealed that yield formation was predominantly driven by kernel number, spike density, and biomass under both conditions, while flag leaf area contributed more specifically under stress. Based on the Stress Tolerance Index, breeding line T22 followed by T2, and T23 combined high yield potential with strong stability, exhibiting the highest STI values (0.786, 0.485, and 0.463, respectively). Future breeding efforts should prioritize crossing these superior lines with locally adapted cultivars and expanding multi-environment trials across wider semi-arid agroecosystems to accelerate the development of climate-resilient wheat varieties.