Evaluation of some physiological and biochemical characteristics of bread wheat (Triticum aestivum L.) genotypes under salinity stress

Since about 20% of the world's arable land and 50% of productions in the world are subject to salinity stress, it affects all stages of plant life from germination to seed production. The aim of this study was to investigate the effect of salinity stress on physiological and biochemical characteristics of some wheat cultivars. For this purpose, a factorial experiment was conducted in a completely randomized design with three replications. The first factor was salinity stress at three levels (control, 100 and 150 mM sodium chloride) and the second factor was wheat cultivars (Mihan, Heydari, Saisons and Gascogen). Plants were exposed to stress from two to four leaf stage and normal water was used for control treatment. Sampling was performed 14 days after stress application from treatet and the control samples. The results showed that among the studied cultivars, salinity stress decreased the concentration of chlorophyll a, chlorophyll b, carotenoids, total protein, and increased prolin, eantioxidant enzyme (peroxidase and polyphenol oxidase) activities and fresh weight of stems and leaves in Saison cultivar. Also, salinity stress did not have significant effect on the amino acids lysine and methionine. The activity of antioxidant enzymes is a very important defense mechanism and increasing the activity of peroxidase and polyphenol oxidase enzymes during salinity stress can reduce or prevent oxidative stress. In general, salinity affected wheat cultivars differently, because cultivars deal with salinity stress toxicity using different mechanisms.