Effects of sodium selenite on the antioxidant capacity and the fruit yield and quality of strawberry under cadmium stress

This study investigated the effects of sodium selenite (Na2SeO3) on the antioxidant capacity and the fruit yield and quality of cadmium-stressed strawberry. The results showed that cadmium (Cd) stress notably decreased the activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT) and glutathione synthetic enzyme gamma-glutamylcysteine synthetase (γ-ECS), plant height and plant biomass, and fruit yield and quality, improved the activities of ascorbate oxidase (AO), glutathione reductase (GR) and ascorbate synthetic enzyme L-galactono-1,4-lactone dehydrogenase (GalLDH), the ratios of AsA/DHA and GSH/GSSG and the contents of malondialdehyde (MDA), hydrogen peroxide (H2O2) and Cd, compared with control. Compared with Cd stress alone, 5 and 10 μM Na2SeO3 notably improved the activities of above enzymes except AO, the ratios of AsA/DHA and GSH/GSSG, plant height and biomass, Se contents in leaves and fruits, average fruit weight and the contents of Vc, soluble sugar and total soluble solid in fruits. 15 μM Na2SeO3 notably improved the activities of above enzymes except AO, the ratio of GSH/GSSG, plant height, Se contents in leaves and fruits, average fruit weight and Vc content in fruits. 20 μM Na2SeO3 only notably improved Se contents in leaves and fruits, average fruit weight and Vc content in fruits. Meanwhile, 5, 10 and 15 μM Na2SeO3 significantly reduced Cd stress-induced the contents of MDA, H2O2 and Cd, 20 μM Na2SeO3 only significantly reduced Cd stress-induced the contents of Cd in leaves and fruits, compared with Cd stress alone. Our findings indicated that only low concentrations of Se were effective in conferring Cd tolerance in strawberry plants by up-regulating their antioxidant capacity and reducing Cd accumulation, which further improved the fruit yield and quality of strawberry.