Rootstock induced changes in enzymes activity and biochemical constituents during budbreak in ‘Thompson Seedless’ grapevine

The process of budbreak was monitored in own rooted and grafted vines of 'Thompson Seedless' (Vitis vinifera L.). Vines grafted on 110R rootstock and own rooted vines took a shorter time to achieve maximum percentage of budbreak as compared to those grafted on Dogridge rootstock. The higher starch degradation with corresponding increase in α-amylase activity was observed in buds of own rooted and 110R grafted vines till 9th day after pruning, while the α-amylase activity was least on Dogridge rootstock. In own rooted and 110R grafted vines, activity of peroxidase and polyphenol oxidase enzymes showed drastic reduction from 0-9th day after pruning. The highest phenolic concentration was observed in the buds of vines grafted on Dogridge rootstock from 0-9th day after pruning. Significant and positive correlation was observed for α-amylase activity and percent budbreak while it was negatively correlated with starch concentration in both buds and canes.