Mitigation of Salinity Stress on Pomegranate (Punica granatum L. cv. Wonderful) Plant Using Salicylic Acid Foliar Spray

Abstract

Salt stress significantly impacts plant morphological structure and physiological processes, resulting in decreased plant growth. Salicylic acid (SA) is a key signal molecule that protects plants from the negative impacts of salinity. Under natural conditions, the pomegranate plant generally exhibits salt-tolerant characteristics. The objective of this study was to elucidate the salt-tolerance level of pomegranate (Punica granatum L. cv. Wonderful) and the effect of the regulating strategy of SA foliar spray on growth, morphological structure, and physiological processes. SA levels were 0, 0.25, 0.50, and 1 mM in the presence of salinity levels of 10, 35, and 70 mM NaCl, respectively. Vegetative growth indices, including stem cross-sectional area, leaf area, and total dry weight, were lowered by salinity treatments. However, SA applications greatly improved morphological characteristics and plant growth under salt stress. The effects of salinity were effectively reversed by SA treatment at 1 mM compared to control and other treatments. Interestingly, SA applications enhanced the chlorophyll, total phenolic, carbohydrate, and proline contents of leaves while decreasing electrolyte leakage (EL), Na, and Cl levels. Moreover, the foliar SA treatments enhanced the nutrient content in the leaves and increased the activities of peroxidase (POD) and catalase (CAT), with a decrease in malondialdehyde (MDA) content. This study suggests that the alleviation of the salinity stress by SA may be due to the activation of the antioxidant enzymatic mechanism and decrease in the lipid peroxidation of the pomegranate plant.