Effect of Proline and Glycine Betaine exogenous application on biochemical alterations in grapevine under drought stresss

Proline and glycine betaine are the most common compatible solutes that prevent plants from destructive effects of osmotic stresses by osmotic adjustment and protection of membranes, proteins and enzymes. It has been reported that exogenous application of these compounds, can increase plant resistance to drought stress. Therefore a factorial experiment based on randomized complete block design on four replications was performed on four grapevine cultivars (Khushnav, Peykani, Perlette, and Flame Seedless). Grapevines under drought stress were irrigated by 70% of the vine water requirement. Proline (10 mM) and Glycine Betaine (15 mM) sprayed on grapevines at four growth stage (before flowering, flowering, sour Cluster and veraison). Results showed that endogenous proline and glycine betaine amount, peroxidase and ascorbate peroxidase enzyme activity in treated vines were significantly higher than the control vines, in both proline and glycine betaine. Among the treated vines the most and the least amount of proline was evaluated in flame seedless and peykani respectively. Other measured characteristics in cultivars did not show significant difference. According to the role of these enzymes in eliminating of reactive oxygen spices (ROS) and also the role of proline and glycine betaine in antioxidants activating, with using of these two osmolyte will be able to increase the vines tolerance in drought stress conditions.