Assessment of Early Drought Tolerance of Algerian Durum Wheat Reveals Superiority of Landraces

VIGOROUS seedling growth is important for good crop establishment, particularly under drought conditions. Our study was set out to identify useful traits and genotypes to enhance early drought tolerance of durum wheat. Two experiments were carried out. In the first one, thirty-five genotypes (Landrace and improved) were tested in a phytotron at germination and early seedling stages, subjected to three osmotic stress levels induced by polyethylene glycol PEG 6000 (0, -3, -6 bar). The second experiment was conducted in the field, with 27 out of the 35 genotypes. Root and shoot traits were measured at seedling stage in both experiments. High PEG 6000 treatment decreased final germination percentage (FGP) by 2.7% and delayed the time to reach 50% germination (t50) by 2.9h. Shoot length was the trait most affected by drought (40% reduction) as compared with other root traits, which even increased under drought, like root to shoot length ratio, root to shoot weight ratio, root dry weight and root number. Coleoptile length (CL) showed a contrasting relationship with other traits, it was negatively correlated in general under no stress, but with positive correlations under stress. Based on drought susceptibility index (DSI), Algerian wheat landraces were the most tolerant compared to modern genotypes. Correlations between traits measured in field and controlled conditions were low. CL could be a potential trait for screening drought tolerant genotypes. Algerian wheat landraces presented a clearly distinct ability for early drought tolerance, and could be a good resource for breeding programs.