Investigation of Reducing Detrimantal Effects of Salt Stress on Morphological and Physiological Traits of (Thymus daenensis Celak.) through Salicylic Acid Application

Salicylic acid is one of the plant growth substances affecting growth and salinity tolerance in plants. In order to evaluate salicylic acid and salt stress effect on some morphological and physiological traits and antioxidant enzymes activity in Thymus daenensis Celak. the experiment was done using four levels of salicylic acid (0, 150, 300 and 450 ppm) and four levels of sodium chloride (0, 50, 100 and 150 mM), based on a completely randomized design in three replications. The results showed that different levels of salinity significantly increased proline content, carbohydrates concentrations, fresh weight and peroxidase and catalase enzyme activity and decreased the leaf area and protein concentration. Also the interaction results of salinity and salicylic acid treatment caused significant increase levels of proline, soluble sugars and protein concentration, ratio of root to stem, dry weight and increased catalase and peroxidase enzyme activity. Based on the results of these study, foliar spraying of salicylic acid by increasing the activity of antioxidant enzymes, proline and Soluble carbohydrates concentrations under salinity stress conditions, improved physiological traits of plants and enhanced plant resistance to salt.