The Effects of Foliar Application of Salicylic Acid and Ascorbic Acid on Morpho-Physiological Traits of Pistachio Seedlings under Drought Stress

This study was carried out to investigate the effects of foliar spray of salicylic acid and ascorbic acid on some morpho-physiological traits of <em>Pistacia vera</em> cv. Badami-zarand under drought stress. The experiment was conducted during 2017-2018 in the greenhouse condition, in a factorial randomized complete block design with three replications on pot plants. The soil texture of experimental pots was sandy-loam. Moreover, the three factors were considered as follows: first factor, drought stress treatments at three levels; control (100% usable moisture content), moderate stress (60% usable moisture content), and severe stress (30% usable moisture content); second factor, salicylic acid, at three levels (0, 0.5mM, and 1mM); and ascorbic acid at three levels (0, 0.5mM, and 1mM). At the end of experiment related physiological, morphological, and biochemical traits related to 6-month-old seedlings were assessed including the fresh and dry weight of leaf, stem and root, number of leaves, leaf thickness, diameter and length of stem, length of root, relative water content, rate of electrolyte leakage, rate of proline accumulation, rate of glycine betaine accumulation, chlorophyll a content, chlorophyll b content, and total chlorophyll. Generally, the results indicated that the value of morphological traits showed a significant reduction in stress treatments. In this experiment, it was found that the application of salicylic acid and ascorbic acid can also reduce the adverse effects of moderate drought stress. Furthermore, it was identified that the response of plant to salicylic acid treatment is similar to ascorbic acid. In general, the application of salicylic acid with a concentration of 0.5mM and ascorbic acid with concentrations of 0.5mM and 1mM is recommended to improve the adaptation of pistachio seedlings under moderate stress.