Effects of foliar application of different concentrations of lysine-chelated selenite on physiological characteristics of wheat

Understanding how chelated selenium (Se) regulates plant stress tolerance is critical for optimising field applications. We investigated dose-dependent effects of foliar-applied lysine-chelated selenite (0, 15, 30, 45, and 60 g/ha selenite) on antioxidant capacity and Se distribution in wheat (Triticum aestivum L.) under field conditions. The results indicated that the optimal application dose (30 g/ha) most effectively suppressed O2- and H2O2 accumulation by 47.8% and 47.2%, respectively, and reduced MDA concentration by 74.0%. This effect was attributed to enhanced activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX), as well as increased concentrations of glutathione and ascorbate. Simultaneously, this treatment inhibited the degradation of photosynthetic pigments and increased the concentrations of soluble sugar, soluble protein, and free amino acids, while reducing proline levels. With increasing application dose, Se concentrations increased and followed the order: roots > leaves > stems > glumes > grains. Our findings demonstrate that lysine-chelated selenite at 30 g/ha was most effective in enhancing antioxidant capacity. This study provides a mechanistic basis for the precise application of chelated Se to simultaneously enhance stress resilience and Se biofortification efficiency.