Abstract
This study investigated the effect of late-spring frost (LSF) stress on wheat (Triticum aestivum) through critical reproductive stages. A factorial experiment was conducted with three wheat genotypes (Roshan, Falat, and Superhead), at three growth stages (pollen development, spike emergence, and anthesis), and with three frost stress durations (control, 1 day of stress, and 4 days of stress) in a completely randomised design with nine replications. Analysis of variance and mean comparison using the l.s.d. method showed that wheat varieties responded differently to growth stages and stress durations, with genotype Roshan being more sensitive and genotype Superhead being more adaptable. Proline accumulation and increased photosynthetic pigment levels were identified as potential mechanisms of stress tolerance, although these responses did not fully prevent yield losses. Principal component analysis explained 75.42% of the total variation, revealing negative correlations between yield-related traits, including grain number, and grain weight. In contrast, chlorophyll, carotenoid, and proline contents were positively correlated with the first principal component. These results highlighted the importance of understanding genotype differences in the LSF tolerance. The genotype- and stage-dependent physiological adjustments drive contrasting yield responses, thereby supporting targeted selection for improved cold resilience under late spring frost conditions.