Exogenous silicon application alleviates salt stress in okra

Salt stress is known to adversely affect a variety of processes in plants, inhibiting growth and decreasing crop yield. Silicon (Si) protects plants against a variety of environmental stresses. In the present study, seedlings of two genotypes of okra (Abelmoschus esculentus L. Moench; salt-tolerant OH-713 and salt-sensitive Okra-7080) were subjected to four treatments; control (no NaCl or Si added), only Si (150 mg·L-1 Si), only salinity (6.0 dS·m-1 ), or salinity + Si, to observe their response at the morphological, physiological, and enzymatic level. The application of Si in stressed okra cultivars led to significant improvements, including increasing the leaf area and leaf area index, decreasing the leaf water potential and osmotic potential, and enhancing the turgor potential and relative water contents. It also increased the activity of the enzymatic antioxidants ascorbate peroxidase and guaiacol peroxidase, as well as increasing nitrate reductase levels and activity. The suppressed concentrations of calcium (Ca) and magnesium (Mg) ions under salt stress were alleviated by the application of Si. The results of the current investigation suggested that Si confers salt tolerance to okra, potentially by enhancing their water status, improving antioxidant activity, and enhancing nitrogen metabolism.