The effect of postveraison water deficit on the phenolic composition and concentration of the Kékfrankos (Vitis vinifera L.) berry

• Water deficit had a beneficial effect on grape berry phenolic concentration and composition.
• Moderate water stress resulted in more favorable phenolic concentration than severe water stress, however it can be modified by the changes in berry skin/flash ratio on the whole berry mass.

The effect of moderate and severe water deficit was examined on berry skin phenolic concentration and composition of the Kékfrankos variety (Vitis vinifera L.). Moderate water stress induced higher concentration of anthocyanin derivatives compared to the non-stressed plants with, the exception of Cya-3-g. Concentrations of some anthocyanin derivatives (Mal-3-g and Peo-3-g) were also higher in the severely stressed berry skins than in the control berries. No differences were found between the stressed and the non-stressed plants in the case of Cya-3-g. Similarly, concentration of some phenolic components (ie. protocatechuic acid, gallic acid, vanillic acid, trans-resveratrol etc.) increased as a result of water deficit. On the other hand, others such as quercetin-3-glucuronide decreased as the water deficit increased. In general, water deficit had a beneficial effect on grape phenolic concentration; however it can be modified by the changes in berry skin/flash ratio.