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

Abstract

Drought is still accounted as a serious agronomic p roblem and also one of the most important factors contributing to crop yield loss. The effect of sodium silicate (Na 2 SiO 3 , abbreviated as Si) was investigated on the four maj or antioxidant enzyme activities and five other relevant components in two different gra pevine cultivars ( Vitis vinifera L., cvs Mish Pestan and Sahebi, as tolerant and sensitive c ultivars) 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-drough t (0.004M sodium silicate kg -1 soil), with three replications in a greenhouse. The results ind icated that Si partially offset the negative impacts of drought stress by increasing th e tolerance of grapevine by rising antioxidant enzyme activities and soluble protein c ontent. Si treatment significantly affected the enzyme activities in both cultivars. W ater 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 . Keywords : Antioxidant enzymes, Drought stress, Grapevine, S ilicon.