Effect of irrigation regime on anthocyanin content and antioxidant activity of Vitis vinifera L. cv. Syrah grapes under semiarid conditions.

Abstract

Irrigation management is a powerful technique to control grape and wine colour. However, water deficit effects on anthocyanins are often contrasting, depending on the severity of water restriction. In addition, the effect of irrigation on the antiradical capacity of grapes has not been extensively studied. In this work the effect of water availability on anthocyanin profile and content as well as the antioxidant activity of Syrah grapes was investigated in an irrigation trial under semiarid climate conditions. Three irrigation treatments were applied in a 15-year-old Vitis vinifera cv. Syrah vineyard, starting at berry set through harvest of 2011 and 2012: full irrigation (FI) at 100% of crop evapotranspiration (ETc), deficit irrigation (DI) at 50% of ETc and non-irrigated (NI). NI grapes were characterized by increased individual anthocyanin content. However, differences among irrigation treatments were significant only around 18-24 days after veraison, when anthocyanin accumulation was maximum. The antioxidant activity of the skin extracts was not affected by irrigation. Irrigation proved to be an effective technique to control anthocyanin content in Syrah grapes under semiarid conditions. However, anthocyanin accumulation pattern should be considered by winemakers to appropriately select harvest time for improved wine colour.