Effects of salicylic acid on some morpho-physiological and biochemical characteristics of walnut seedlings under salinity condition

Salinity of water irrigation and soil are of the major factors affecting plant growth and productivity worldwide. In this research the effects of salicylic acid on some morpho-physiological and biochemical characteristics of walnut (Juglans regia) seedlings under salinity stress condition were studied. The experiment was a two-factor factorial experiment arranged in completely randomized design with three replications. Two factors of the experiment were (or included) salicylic acid (0, 1, 2 and 3 mM) and NaCl (0, 50, 100 and 150 mM) that their affecting was evaluated when walnut seedlings were 60- day old. Analysis of variance has illustrated that a significant difference exists among treatments for most of studied traits. Increasing salinity levels resulted in reducing leaf number, leaf area, branch number and shoot length in walnut seedlings. While induced salinity significantly decreased chlorophyll pigments and leaf relative water content (RWC) but enhanced electrolyte leakage, malondialdehyde (MDA) and proline concentration. Pre-treatment seedlings with 1 mM salicylic acid provided protection against salinity stress in walnut seedling. The interaction between salinity and salicylic acid was significant for some measured characters such as carotenoids, leaf relative water content, electrolyte leakage, malondialdehyde and proline. Overral, the results from this experiment showed that applying salicylic acid at the concentration level of 1 mM, caused to reduction of tissue destruction during salinity stress and are suitable treatment for maintenance walnut seedling.