Effects of selenomethionine on the growth and physiological characteristics of Scrophularia ningpoensis seedlings

In order to provide a theoretical basis for the application of organic selenium (Se) in the production and cultivation of Scrophularia ningpoensis Hemsl. We investigated the effects of selenomethionine (SeMet) on the growth and physiological characteristics of S. ningpoensis seedlings. The results showed that SeMet significantly improved the antioxidant capacity by enhancing the activities of antioxidant enzymes such as superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) in the leaves of S. ningpoensis, which significantly reduced the content of malondialdehyde (MDA) and hydrogen peroxide (H2O2), as compared to the control. SeMet also significantly improved the water metabolism by increasing the transpiration rate, stomatal conductance, water use efficiency (WUE), relative water content, and water saturation deficit of S. ningpoensis leaves. Moreover, SeMet significantly enhanced photosynthetic performance by decreasing non-photochemical quenching (NPQ) and increasing the soil and plant analyser development (SPAD) value, net photosynthetic rate, PSII actual photochemical efficiency Y(II), photochemical quenching (qP), PSII photochemical effective quantum yield (Fv'/Fm') and apparent electron transport rate (ETR). Meanwhile, SeMet significantly improved the plant's height, basal diameter, root/shoot ratio and dry weight of shoots and roots in S. ningpoensis. Various SeMet 30 and 60 mg/L SeMet concentrations demonstrated better effects on the growth and physiological characteristics of S. ningpoensis. The above results indicate that appropriate concentrations of SeMet can enhance the growth of S. ningpoensis and can be improved by increasing its antioxidant capacity, water metabolism, and photosynthetic performance. This provides a theoretical foundation for using organic selenium in growing and producing S. ningpoensis.