Selenium enhances nutrient uptake and rosmarinic acid biosynthesis in Melissa officinalis L. under salinity stress

Salt stress is a serious problem facing plant growth and development. Selenium (Se) could improve plant growth and reduce stress. Hence, the aim of this study was to determine whether Se application could alleviate negative effects of salinity stress on Melissa officinalis L. Different salinity levels in this research were control (0), 50, 100, and 200 mM. Simultaneously, sodium selenate (Se) (0 and 50 mg L-1) was applied. Salinity showed adverse effects on different plant growth parameters as well as pigment content. Se at 50 mg L-1 increased the vegetative growth of M. officinalis plants under different salinity levels. Salt induced oxidative stress conditions by increasing malondialdehyde and proline content, and Se foliar spraying enhanced antioxidative enzymes activity such as superoxide dismutase and catalase. Compared with control group, selenium accumulation in shoot and root significantly increased with Se levels increment. Selenium application increased N, Ca, K, and Mn accumulation. The foliar spray of Se increased rosmarinic acid compared to salt and non-salt treated plants. It is concluded that the application of Se can mitigate salt stress damages on M. officinalis plants and enhance mineral uptake.