Effect of foliar application of salicylic acid on some morphological, physiological and biochemical traits in grapevine (Vitis vinifera L.cv Thompson seedless) grown under salt stress

Salt stress is one the major environmental stresses limiting quantitative and qualitative aspects of plant growth. One of the methods to overcoming the adverse effects of salinity is application of growth regulators. Salicylic acid is a plant growth regulator its positive effects in alleviating the adverse effects of stresses on plants have been reported. In order to study the effect of salicylic acid (SA) on some morphological, physiological and biochemical characteristics of grapevine, (Vitis vinifera cv. Thompson Seedless), a pot factorial experiment was conducted as randomized complete design, under salinity stress condition. Well-rooted grape cuttings were exposed to five levels of salinity 0 (control), 25, 50, 75 and 100 mM NaCl and four levels of SA, 0 (control), 100, 200 and 300 mg/l. The results indicated that with the increase in salinity levels, the morphological traits, and leaves relative water contents were reduced, leaves cells membrane leakage and the amount of tissues malondialdehyde increased. In salinity level of 100 mM, the length of stem and root was reduced 67.18 and 59 percent in compared to control. In salinity level of 100 mM, application of 300 mg/l salicylic acid, increased proline and soluble solids 4.11and 7.5 times respectively compared to control. It also increased guaiacol peroxidase, ascorbate peroxidase and catalase 3.15, 4.1 and 3.6 times respectively compared to control. Overall, the application of SA (200-300 mg/l) caused increase in growth efficiency, antioxidant enzymes activities and the amount of compatible osmolytes but reduced the ionic leakage.