Effect of silicon supplies on biomass and antioxidase and osmolytes of tall fescue seedlings under different salt concentration conditions

In this study, a pot experiment was conducted to determine the response of biomass, antioxidant enzyme activities, and osmotic regulators to silicon in tall fescue seedlings under different salt stress condition. The results showed that with an increase in salt concentration, the biomass of tall fescue decreased gradually. When the salt concentration was less than 50 mmol·L-1 or greater than 250 mmol·L-1, silicon had no obvious effect on the biomass of tall fescue; when the salt concentration was between 50 and 250 mmol·L-1, the biomass of tall fescue increased significantly (P<0.05) with silicon. With an increase in salt concentration, CAT activity increased, and POD and SOD first increased and then decreased. Although the addition of silicon increased the activity of POD, SOD, and CAT, there are some differences in the salt concentrations when the different enzymes increased significantly. With an increase in salt concentration, MDA content increased, soluble sugar and soluble protein content first increased and then decreased, and when the salt concentration reached 200 and 250 mmol·L-1, soluble sugar and soluble protein contents reached their highest values. The addition of silicon reduced the contents of soluble sugar, soluble protein, and MDA in tall fescue. The above results showed that the effect of silicon on the salt tolerance of tall fescue varied under different salt stresses. When the salt concentration was too low or too high, the silicon had no significant effect on the adaptability of tall fescue, but when the salt concentration was in a middle range, the silicon enhanced the adaptability to salt stress of tall fescue by increasing the antioxidant enzyme activity in the plants, improving the osmotic adjustment process and reducing membrane oxidation.