Physiological Responses of Pak Choi to Exogenous Foliar Salicylic Acid Under Soil Se Stress

In plants, excess selenium causes general toxic symptoms. However, salicylic acid plays an important role in alleviating toxic effects of various stresses. This study aimed to clarify the role of exogenous foliar salicylic acid on alleviating selenium toxicity of pak choi exposed to moderately and highly Se-excessive soils (4 mg·kg−1 Se and 10 mg·kg−1 Se, respectively). The results showed that Se stress caused severe lipid peroxidation, desynchronization of the antioxidant enzymatic system, and significant decreases in the measures of photosynthetic activity and shoot biomass. Under Se stress conditions, exogenous foliar salicylic acid significantly increased measures of photosynthetic activity and shoot biomass, increased catalase activity, and decreased measures of oxidative stress. Moreover, exogenous salicylic acid significantly enhanced Se accumulation in shoots under Se stress conditions. We demonstrate here that foliar spraying with salicylic acid is an effective measure to alleviate the adverse effects of Se stress and enhance Se accumulation for optimizing crop Se biofortification in Se-excessive soil.