Effect of Water Stress and Sodium Silicate on Antioxidative Response in Different Grapevine (Vitis vinifera L.) Cultivars

Drought is still accounted as a serious agronomic problem and also one of the most important factors contributing to crop yield loss. The effect of sodium silicate (Na2SiO3, abbreviated as Si) was investigated on the four major antioxidant enzyme activities and five other relevant components in two different grapevine cultivars (Vitis vinifera L., cvs Mish Pestan and Sahebi, as tolerant and sensitive cultivars) under drought stress. The experiment was performed in a completely randomized design including three treatments i. e. the control, drought with no Si, and Si-drought (0.004M sodium silicate kg(-1) soil), with three replications in a greenhouse. The results indicated that Si partially offset the negative impacts of drought stress by increasing the tolerance of grapevine by rising antioxidant enzyme activities and soluble protein content. Si treatment significantly affected the enzyme activities in both cultivars. Water stress induced a decrease in total Chlorophyll (Chl) and total protein contents, which was much larger in no-Si stress than in Si treatment. The results indicated that sodium silicate might decrease drought stress damages by raising the antioxidant enzymes activity.