Silicon-induced alleviation of NaCl toxicity in okra (Abelmoschus esculentus) is associated with enhanced photosynthesis, osmoprotectants and antioxidant metabolism

In this investigation, two okra [(Abelmoschus esculentus (L). Moench)] genotypes were used, i.e., salt-sensitive Okra-7080 and salt-tolerant OH-713. Seedlings were subjected to salt stress (EC 6 dS m⁻¹) and supplemented with optimized concentration of silicon (150 mg L⁻¹) to evaluate the changes in physio-biochemical and enzymatic characteristics of okra genotypes. Physiological attributes included measurement of gas exchange parameters (photosynthesis rate, stomatal conductance, transpiration rate, number of stomata and stomatal size) and relative water contents; biochemical parameters included contents of various molecules (total chlorophyll, carotenoids, proline, glycine betaine, total free amino acids and total soluble sugars, total soluble protein, total phenolics and lipid peroxidation) and enzymatic activities (superoxide dismutase, peroxidase and catalase). The results demonstrated that silicon application under saline conditions resulted in significant differences in many traits and it was concluded that silicon was useful in alleviating salt-induced deleterious effects in okra at early growth stage. It was also suggested that enhanced salt tolerance in okra was highly linked with increased osmolyte accumulation and antioxidant activities, due to exogenously applied silicon.