Improving the Drought Tolerance in Pistachio ( Pistacia vera ) Seedlings by Foliar Application of Salicylic Acid

Pistachio ( Pistacia vera L.) is an economically important nut crop that is prone to drought stress since it is mainly produced in arid and semi-arid regions. Considering the possible impact of salicylic acid (SA) on drought tolerance of pistachio, several physiological and biochemical responses of pistachio seedlings to foliar application of SA under progressive drought treatment were investigated. Application of SA increased the content of pigments, chlorophyll, and carotenoids, and improved the accumulation of osmolytes such as proline and total soluble carbohydrates leading to preserve photosynthetic apparatus and relative water content. Moreover, SA application reduced the drought-induced levels of H 2 O 2 and lipid peroxidation in pistachio seedlings by increasing the activity of antioxidant enzymes. According to our findings, ascorbate peroxidase and glutathione reductase play a major role in the antioxidative salicylic acid-induced defense against oxidative stress in pistachio. Taken together, our results show that the foliar application of SA could significantly enhance drought tolerance of pistachio seedlings through protecting photosynthetic apparatus, improving osmoregulation, and inducing the antioxidant defense system.