Screening of seedlings of durum wheat (TRITICUM DURUM DESF.) cultivars for tolerance to PEG-induced drought stress

The effect of drought stress on 11 durum wheat (Triticum durum Desf.) cultivars was determined at the germination stage. Cultivars were screened for drought tolerance. Six levels of osmotic stress (0, -0.47, -1.48, -3.02, -5.11 and -7.73 bars) were assessed by applying different concentrations of polyethylene glycol (PEG-8000). There were significant differences between treatments for all seedling characteristics (p<0.05, p<0.001), except mean daily germination (MDG). All seedling traits also differed significantly (p<0.001) among all cultivars. In general, osmotic stress decreased seed germination percentage, germination rate (GR), coleoptile length (CL), shoot length (SL), root length (RL), root/shoot (R/S) length ratio, and root number (RN). Averaged over all osmotic stress levels, Mahmoudi had high MDG (0.55), GR (1.88), CL (4.20 cm), SL (10.45 cm), and RL (9.93 cm), suggesting that this variety was highly tolerant to drought stress. There were high correlation coefficients between different characteristics: SL had a positive and significant (p<0.01) correlation with CL (r =0.83), RL (r = 0.74), and R/S length ratio (r = 0.67). This study showed that, based on morphological traits, preliminary screening at an early stage for drought stress using PEG-8000 may facilitate the choice of an adequate cultivar for growth under water stressed conditions. (author)