Effect of Cluster Thinning on Berry Skin Anthocyanin Composition of Vitis vinifera cv. Nebbiolo

Abstract

Cluster thinning (removal of 50% of the cluster one month after bloom) was tested for three consecutive years in a vineyard located in southern Piedmont (Italy). At harvest, concentrations of total anthocyanins and flavonoids were assessed by spectrophotometry and concentrations of individual anthocyanins were determined by high-performance liquid chromatography. Berry weight and berry skin weight slightly increased following thinning. Soluble solids and berry skin anthocyanins and flavonoids were more concentrated in berries from cluster-thinned plants. Cluster thinning increased the concentrations of cyanidin-3-glucoside, peonidin-3-glucoside, and, to a lesser extent, petunidin-3-glucoside. Concentrations of malvidin-3-glucoside and of acylated anthocyanins were not affected by cluster thinning.