Morphophysiological reaction of bread wheat cultivars under the influence of drought environmental stress

The aim of this study was to evaluate and select bread wheat cultivars by assessing the yield, yield components and some physiological traits under drought stress conditions. Six cultivars were evaluated as sub-plots in 2018 to 2020 cropping seasons using a split plot design based on RCBD with three replicates. The Main plot covered the three irrigation regimes including normal irrigation (non-drought stress), terminal droght stress (irrigation up to boot- stage as moderate drought stress) and full drought stress (dryland). The results revealed that a significant reuction of the plant height (1.26 and 1.38%), fertile tillers number (1.38 and 2.81%), spike length (2.16 and 4.02%), seeds number per spike (1.25 and 3.74%), seed weight per spike (0.51 and 2.62), 1000-seed weight (12.97 and 29.90%) and grain yield (12.5 and 31%) were recorded under the moderate drought stress and full drought stress, respectively as compared to non-stress conditions. The physiological traits like soluble sugars, proline content, peroxidase and polyphenol oxidase enzyme activity were significantly influenced by the drought stress treatments. Moderate drought stress and full drought significantly increased the soluble sugar content (4 and 10%, respectively), proline content (26 and 45%, respectively), polyphenol oxidase (13 and 21%, respectively) and peroxidase enzyme activity (10 and 22%, respectively). The present study verified that the biochemical parameters need to be considered as better traits to select wheat cultivars for drought tolerance under water stress conditions. However, the wheat cultivars ‘Taktaz’ showed the highest yield potential followed by the Tirgan in both non-stress and moderate drought stress conditions. Rank sum analysis identified the most drought tolerant cultivars as ‘Taktaz’ and ‘Aftab’. The Ardabil (Moghan) cultivar is considered as the most useful wheat cultivar for future drought tolerance breeding programs or similar agro-ecologies.