Screening drought-tolerant durum wheat genotypes using morphophysiological traits

Drought stress is a critical factor that limits the growth, yield, and related traits of durum wheat (Triticum turgidum L. var. durum). Thus, to identify superior drought-tolerant genotypes, a comprehensive study was carried out through rainout shelter and field experiments during the 2020–2021 and 2022–2023 growing seasons. The goal was to select genotypes that exhibit enhanced drought resilience based on key morphophysiological traits. In the preliminary phase, 100 genotypes were exposed to two water regimes: drought-stressed and well-watered conditions. From this pool, 12 promising genotypes were shortlisted for further evaluation in both pot experiments and natural drought-prone environments. Various traits, including leaf water status, leaf gas exchange parameters, morphological characteristics, and agronomic performance, were measured. The results highlighted significant genetic variation among the genotypes for traits such as relative water content (RWC), excised leaf water loss (ELWL), and chlorophyll content. Significant differences were also observed from transpiration rate (E), photosynthetic rate, stomatal conductance (gsw), intercellular CO₂ concentration (Ci), boundary layer conductance, normalized difference vegetation index, leaf angle, and leaf rolling. Among the tested genotypes, DW183123 consistently outperformed others in both drought-stressed and well-watered conditions, demonstrating superior performance in pot and field trials. Under drought stress, it maintained higher RWC, Ci, E, and gsw, and low ELWL in drought stress conditions, which were identified as having a greater potential to maintain water balance in their leaves. Moreover, it displayed tighter inward leaf rolling with erect leaves compared to susceptible genotypes, which exhibited loose rolling. Therefore, these findings suggest that DW183123 is a promising candidate for future wheat breeding programs aimed at enhancing drought tolerance in durum wheat varieties.