Vegetative and Reproductive Growth Responses of Grapevine cv. Italia (Vitis vinifera L.) Grafted on Different Rootstocks to Contrasting Soil Water Status

Plant growth and reproductivity of grape cv. 'Italia' subjected to two different irrigation levels in controlled glasshouse were investigated over 2 years. Initially, two years old vines were grafted on 5 BB (V. berlandieri Planch.×V. riparia Michx.), 99 R (V. berlandieri Planch.×V. rupestris Scheele) rootstocks or on its own root system in 40 L pots. During the cultivation, half of the vines of each experimental group were Fully Irrigated (FI: 100% of field capacity) while the others were subjected to continuous Deficit Irrigation (DI: 40% of field capacity). During the study, significant negative effects of DI on plant vegetative development and physiology were observed. The lignified shoot length of vine on 5 BB rootstock decreased by 29.1% under DI as compared to growth under FI. On the other hand, the vine with 99 R rootstock decreased by 18.2% under DI as compared to lignified shoot growth under FI, while a 20.1% decrease occurred for own root (DI vs. FI). Also, DI regime resulted in slight decreases in P, K, and Ca status of leaves, while Zn and Cu concentrations were significantly higher in the vines subjected to DI. DI resulted in reduced cluster weight and vine yield in varying degrees with respect to rootstock usage. Under DI condition, the vines on 99 R yielded better than those on 5 BB, but vines on on 5 BB reacted adversely to DI. Considering the overall findings, grapevines cv. 'Italia' on 99 R exhibited higher drought tolerance than 5 BB. Rootstocks had slight impairing effects on physiological traits, yield, and mineral acquisition of grapevine cv. 'Italia' as compared to own-rooted.