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 reduced stress. Hence, the aim of this study was to determine whether the Se application could alleviate salinity stress negative effects 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 enzyme activity such as superoxide dismutase and catalase. Compared with the 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 enhanced mineral uptake.