Effects of Irrigation and Pruning of Shiraz Grapevines on Subsequent Red Wine Pigments

Abstract

The effect of irrigation and pruning on wine pigments was studied in experimental wines made from <i>Vitis vinifera</i> cv. Shiraz grown in the hot, arid climate of Griffith, N.S.W., Australia for four years from 1975 through 1978. Irrigation reduced wine color, the amount of pigments and the proportion of anthocyanins in the colored form. The reduced proportion of pigments in the colored form was due to the increase in wine pH. The reduction in wine color was correlated with an increase in berry size with the irrigated treatment compared to the nonirrigated treatment. In two of the four years severe pruning reduced wine color, in one year pruning had no effect, and in the other years severe pruning increased wine color. Thus, water stress will consistently increase wine color, but severe pruning had no consistent effect and often reduced wine color.