Exogenous Melatonin Enhances Salt-Stress Tolerance in Festuca elata via Growth and Physiological Improvements

Salt stress is a major abiotic factor that inhibits plant growth. Melatonin (MT), an important plant growth regulator, can effectively enhance plant stress resistance. Festuca elata, a turfgrass species widely used in urban landscaping, was selected for this study to evaluate the regulatory effects of exogenous MT at different concentrations on its growth and development under salt stress. Indoor pot experiments were conducted using Festuca elata as the plant material. The experiment included a 250 mM NaCl salt-stress treatment and foliar application of five MT concentrations (0 μM, 50 μM, 150 μM, 250 μM, and 350 μM) to assess their effects under salt stress. The results showed that salt stress severely inhibited the growth of Festuca elata, while all tested MT concentrations significantly alleviated the damage. MT treatments improved leaf area and plant height and increased relative water content, soluble protein, proline, chlorophyll, and carotenoid contents. Additionally, MT reduced malondialdehyde accumulation and enhanced superoxide dismutase and peroxidase activities. Among the tested concentrations, 150 μM MT showed the most effective alleviation of salt stress, indicating its strong potential for promoting Festuca elata cultivation in saline environments.