Exogenous application of salicylic acid mitigates salt stress in rice seedlings by regulating plant water status and preventing oxidative damage

Salicylic acid (SA) is a hormone participating in the acclimation of plants to biotic and abiotic stresses, including salinity. We investigated the possible underlying mechanism of mitigating salt stress by SA using NaCl-treated rice plants sprayed twice with exogenous SA at different concentrations. SA application resulted in increased growth, relative water content, proline accumulation, the quantum efficiency of photosynthesis and activity of superoxide dismutase in NaCl-treated plants. Application of SA decreased Na+ concentration and increased K+ concentration, thus increasing the K+/Na+ ratio. The application of SA mitigated the effect of NaCl by improving plant water status, ion homeostasis and decreased oxidative damage. Foliar application of 0.5 mM SA was more effective in mitigating the salt stress while 2 mM SA was inhibitory, and the second spray of SA showed no significantly enhanced ameliorating effect over the first spray.