Evaluating bread wheat varietal responses to late-spring frost conditions

This study investigates the impact of late-spring Frost (LSF) stress on wheat (Triticum aestivum) during critical reproductive stages. A factorial experiment was conducted with three wheat genotypes ('Roshan', 'Falat', and 'Superhead'), three growth stages (pollen development, spike emergence, and pollination), and three stress levels (normal, one-day stress, and four-day stress) in a completely randomized design with nine replications. Analysis of variance and mean comparison (LSD method) showed that wheat varieties responded differently to growth stages and stress durations, with 'Roshan' being more sensitive and 'Superhead' more adaptable. Proline accumulation and increased photosynthetic pigment levels were identified as stress resistance mechanisms, though they did not fully prevent yield reductions. Principal Component Analysis (PCA) explained 75.42% of the variation, showing negative correlations between yield-related traits (grain number and grain weight) and the first component, while chlorophylls, carotenoids, and proline correlated positively. These results emphasize the importance of understanding varietal differences in LSF tolerance and the need for phenotyping and genetic improvements to develop cold-tolerant wheat varieties. The findings highlight the vulnerability of reproductive stages and the importance of targeted breeding strategies to enhance crop resilience and ensure yield stability in climates affected by LSFs.