Selenium improves wheat antioxidant capacity, photosynthetic capacity, and growth under cadmium stress

Cadmium stress (CS) induced the peroxide damage and inhibited wheat photosynthetic capacity and growth. Compared to CS, selenium (Se) application plus CS bolstered chlorophyll and carotenoid contents, photosynthetic rate, the maximum photochemical efficiency of PSII, the quantum yield of PSII photochemistry, and photochemical quenching, superoxide dismutase, catalase, ascorbate peroxidase, glutathione reductase, L-galactono-1,4-lactone dehydrogenase, and gamma-glutamylcysteine synthetase activities, ascorbic acid and glutathione contents, AsA/dehydroascorbic acid and GSH/oxidized glutathione, and decreased nonphotochemical quenching (q_N), antioxidant biomarkers malondialdehyde and hydrogen peroxide contents, and electrolyte leakage (EL). At the same time, Se alone declined antioxidant biomarkers contents, q_N and EL, and augmented the rest of the aforementioned indexes. Our research implied that Se upregulated wheat's antioxidant capacity. In this way, Se improved wheat photosynthetic performance and growth, especially for 10 μM sodium selenite (Na₂SeO₃). Consequently, 10 μM Na₂SeO₃ may be considered a useful exogenous substance to reinforce wheat cadmium tolerance.