The impact of organic selenium on the growth and physiological traits of Salvia miltiorrhiza Bunge. seedlings

This study examined the impact of selenomethionine (SeMet) on the growth and physiological traits of <i>Salvia miltiorrhiza</i> seedlings. Application of SeMet significantly improved the photosynthetic performance by reducing stomatal limitation value (Ls) and increasing soil and plant analyser development (SPAD) value, net photosynthetic rate (P_n), transpiration rate (T_r), stomatal conductance (g_s) and water use efficiency (WUE), compared to the control. Furthermore, SeMet also improved the photosynthetic performance by reducing non-photochemical quenching (NPQ) and increasing the actual photochemical efficiency of photosystem II (Y(II)), photochemical quenching (qP), maximum photochemical efficiency of PSII (F_v/F_m) and apparent electron transport rate (ETR). Meanwhile, the findings indicated that SeMet was able to enhance the antioxidant capacity of <i>S. miltiorrhiza</i> seedlings by increasing the activities of antioxidant enzymes ascorbate peroxidase (APX), glutathione reductase (GR), peroxidase (POD), catalase (CAT) and superoxide dismutase (SOD), thereby reducing the contents of malondialdehyde (MDA) and hydrogen peroxide (H₂O₂). Besides, SeMet notably impacted plant growth by promoting plant height, basal diameter and biomass. Among different concentrations, 60 mg/L exhibited the most favourable impact on photosynthetic performance, antioxidant capacity and the growth of <i>S. miltiorrhiza</i> seedlings. In summary, the appropriate dosage of SeMet can stimulate the growth of <i>S. miltiorrhiza</i> by enhancing photosynthetic and antioxidant capacities. These findings can serve as a solid theoretical foundation for the application of SeMet in the cultivation and production of <i>S. miltiorrhiza</i>.