Effects of silicon application to increase salinity tolerance through reduction of oxidative stress in Festuca arundinacea

This study aimed to evaluate the ameliorating effects of silicon nutrition on Festuca arundinacea under salinity stress. A completely randomized design was used to study the effects of different levels of salinity including 0 and 100 mM NaCl and silicon nutrition including 0, 0.75 and 1.5 mM sodium silicate on the species performances. The plants cultivated in greenhouse in sand culture with Hoagland nutrient solution. The results showed that the plants growth was reduced in salinity treatment. The plants performances were improved using silicon nutrition (especially 0.75 mM). Salt treatment increased the Na+ and decreased K+, Ca2+ and Fe content in aerial parts of the species, however, silicon treatment led to reducing the Na+ and increasing Fe content. The activities of soluble and cell wall peroxidase and polyphenol oxidase enzymes were declined in the species under salinity. The application of 0.75 mM Si approved to be an effective way to recover the activities of these enzymes. Salinity imposed significant reduction in contents of chlorophylls, total carotenoids and xanthophylls and soluble proteins, however, the hydrogen peroxide rate as well as lipid peroxidation contents were increased. On the contrary, chlorophylls, total carotenoids and xanthophylls and soluble proteins contents were increased and hydrogen peroxide and lipid peroxidation were decreased in salt-treated plants following Si treatment (0.75 mM Si). Salinity caused significant increase in electrolyte leakage from plant membranes; however, silicon nutrition (0.75 mM Si treatment) reduced these parameters. The result indicated that silicon nutrition (especially 0.75 mM treatment), mitigates harmful effects of salinity through declined Na+ content and increased antioxidant enzymes activities that reduced oxidative stress as evidenced by decreased lipid peroxidation and electrolyte leakage. Consequently, Si application led to better growth of salt –affected plants.