Selenium foliar application alleviates salinity stress in sweet william (Dianthus barbatus L.) by enhancing growth and reducing oxidative damage

Salinity is considered as one of the most important environmental stresses in plant growth and productivity around the world by arid and semi-arid areas; therefore, the development of an efficient strategy against salt stress in crops is urgently needed. Application of Se thus appeared to be an efficient approach for the improvement of plant growth and productivity under saline condition. This study investigated the effects of salinity stress by applying different NaCl levels (0, 30, 60, and 90 mM) in combination with foliar application of Se at different levels (0, 5, 10, and 15 µM) on morpho-physiological and biochemical traits of Dianthus barbatus. Done in a factorial design and completely randomized layout with three replications, the findings showed that salinity caused significant reduction in growth, increased electrolyte leakage and malondialdehyde levels, and increased activities of antioxidant enzymes. At an increase in growth defects among the saline treatments, a positive level of 90 mM NaCl was recorded, whereas the imposition of Se improved some growth traits in most aspects: phenolic and flavonoid contents; antioxidant capacity was boosted in Se-stressed plants. Indeed, at 10µM application level in most of salinity treatments and controls, enhancing the salinity tolerance was reflected. These evidences show cell membrane stabilization of Se through maintaining compounds with various protective functions coupled with enhancing their antioxidant enzyme capacity at efficient low doses. In conclusion, Se application through foliage was an effective method to enhance the plant's tolerance capacity against salinity in sweet william and could turn out to be a sustained solution for agricultural production under salinity conditions.