The Effect of Selenium Foliar Application on the Physiological Responses of Edamame under Different Water Treatments

Abstract

Drought has devastating effects on crops, posing enormous risks to food security. This study investigated the impact of foliar applied selenium [at four concentrations (25, 50 and 75 mg/L)] on the photosynthesis capacity, antioxidative enzyme activities [ascorbate peroxidase (APX) and guaiacol peroxidase (GPX)] and yield parameters of a drought susceptible edamame under optimal watering and drought-stressed conditions. The study was conducted in the greenhouse under controlled conditions with leaf sampling done at vegetative, flowering and pod filling stages. Treatment of drought-stressed plants with selenium selectively induced PIabs and chlorophyll content at the vegetative stage. Ascorbate peroxidase was the only parameter induced at the flowering stage by selenium under drought stress. Selenium had no effect on all parameters under drought stress at pod filling, suggesting that the efficacy of selenium declines with time. In addition, yield parameters were not substantially affected by selenium under drought stress. Although selenium was effective for selected parameters, the application should only be limited to edamame growing under drought stress because, under well-watered conditions, it had negative impacts. Future studies should explore the responses drought stressed edamame after secondary application of selenium (i.e., at vegetative, flowering and pod filling).