The Effect of Partial Defoliation on Quality Characteristics of Vitis vinifera L. cv. Cabernet Sauvignon Grapes. II. Skin Color, Skin Sugar, and Wine Quality

Abstract

The effect of partial defoliation (33% and 66%) from different developmental stages of Vitis vinifera L. cv. Cabernet Sauvignon on grape skin color and sugar content as well as on wine quality was studied. Anthocyanin concentrations tended to be higher following partial defoliation and tended to increase the later defoliation was applied, resulting in the highest concentration with defoliation from veraison. The anthocyanin content per berry was significantly higher for vines defoliated from veraison. Sugar levels in berry skins seemed to be associated with anthocyanin concentration. The phenolic content per berry was unaffected by partial defoliation. Berry volume generally decreased with defoliation. Berry volume of partially defoliated vines increased the later defoliation was commenced. In general, wine quality was significantly improved by partial defoliation, regardless the severity of defoliation or developmental stage defoliation was commenced. The effect of defoliation on wine quality should be judged in conjunction with results on sugar and acid content of berries and must pH. Partial defoliation had no marked effect on berry composition and volume; however, it generally improved wine quality.