Alleviating Salt-Induced Effects in Tomato via Simultaneous Application of Salicylic Acid and Potassium

Abstract: Soil salinity is a major abiotic stress causing severe damage to plants. Thus, proper management approaches need to be developed to lessen the detrimental effect of salinity on crop growth and productivity. The objective of this study was to investigate the potential role of exogenous salicylic acid (SA) and potassium (K+) in mitigating the adverse effects of salt stress on tomato. Salt-stressed tomato seedlings Solanum lycopersicum L. cv. Agata were exposed to 0.1 mM SA and 5 mM K+, applied individually or simultaneously for two weeks. Obtained results showed that salt stress resulted in reduced growth rate associated with accumulation of Na+ ions, reduced K+ levels, lower K+/Na+ ratio, increased oxidative damage, reduced total chlorophyll and carbohydrate contents as well as disturbed proline accumulation and disrupted antioxidant system. Nevertheless, after SA and K+ supplementation, total chlorophyll, K+, total proteins, total carbohydrates, and proline contents as well as K+/Na+ ratio were significantly increased. Additionally, exogenous SA and K+ treatments enhanced the non-enzymatic and enzymatic antioxidant system and ensured better oxidative stress tolerance, as indicated by reduced H2O2 production and membrane lipid peroxidation, resulting in an increased membrane stability index. These effects were further enhanced by the simultaneous application of SA and K+, resulting in a better growth of salt-stressed tomato seedlings compared to single applications of these two growth regulators. Taken together, the results of the current study provide evidence that SA and K+ may interact to counteract the adverse effects of salt stress on the growth of tomato seedlings by improving osmotic and ionic homeostasis and upregulating the antioxidant defense system. Therefore, the simultaneous application of SA and K+ may be suggested as a promising approach for beneficial tomato growth at the seedling stage under salt-affected soil conditions. © Pleiades Publishing, Ltd. 2025.