Abstract Salinity is one of the most important factors limiting crop production all over the world including Iran, which is important to deal with. Accordingly,a pot experiment was conducted outdoors at collage of agriculure of Isfahan University of Technology in order to eva‎luate the effects of foliar application of two concentrations of salicylic acid (100 and 200 mg/l), ascorbic acid (100 and 200 mg/l) and putricin (50 and 100 mg/l) on the growth and physiological characteristics of two salinity tolerant (Tabasi) and sensitive (Sepahan) wheat cultivars under three levels of salinity (0, 60 and 120 mM NaCl in irrigation water). Treatments were arranged as factorial based on a completely randomized design with four replications. Salinity decreased the contents of potassium, chlorophyll and carotenoid, potassium/ sodium ratio and shoot dry weight while increased the concentrations of sodium, proline, MDA and H2O2 and the activities of antioxidant enzymes catalase, peroxidase and ascorbate peroxidase. The extent of decreases in potassium and photosynthetic pigments contents and plant dry weight and the degree of increases in sodium and lipid peroxidation due to salinity were smaller in Tabasi than in Sepahan cultivar, indicating Tabasi to be more salinity tolerant. Besides, the increases in the activities of antioxidant enzymes under saline conditions were greater in Tabasi. In both cultivar, the highest increase in enzyme activity under low level of salinity was obtained for ascorbate peroxidase but under high salinity level it was attained for peroxidase. The application of salicylic acid, ascorbic acid and putricin increased the contents of potassium, chlorophyll, carotenoid and proline, potassium/ sodium ratio, the activities of antioxidant enzymes and shoot dry weight while decreased the concentrations of sodium, MDA and H2O2 under both saline and none-soline conditons. Among three studied antioxidant enzymes, catalase had more contribution in induction of salinity tolerance and reinforcement of the enzymic antioxidant system by foliar application. Regardless of cultivar, the highest increase in plant dry weight due to foliar spraying was achieved by the application of 200 mg/l ascorbic acid under none-saline treatment and 60 mM NaCl (16 and 20%, respectively) but it was obtained by 200 mg/l ascorbic acid application under 120 mM NaCl (14%). In most cases, the more positive effects of foliar spraying on growth characteristics were attained under higher concentration (200 mg/l) of salicylic acid and ascorbic acid but for the case of putricin it was evident under lower concentration (50 mg/l). The results of this investigation indicated that the application of salicylic acid, ascorbic acid and putricin in addition to improve plant growth can also mitigate the negative effects of salinity, dependant on salinity level and the concentration of sprayed compounds.

مرتضي زاهدي

محمد حسين اهتمام ،حميدرضا عشقي زاده

حسن كريم مجني ، مريم حقيقي