Influenza di trattamenti di diradamento dei grappoli e di defogliazione sul profilo antocianico di acini di Vitis vinifera cv Nebbiolo.

Removal of 50 % leaves and thinning of 50 % clusters were tested for respectively three and for two consecutive years in two vineyards located in southern Piedmont (Italy), where the Nebbiolo variety is grown. Leaf removal was done one month after full bloom and cluster thinning was done at veraison; leaf removal was repeated later on new growth. Leaves at every other node on primary shoots and lateral shoots were removed. Berry weight, sugar content, total anthocyanins were assessed at harvest. Anthocyanins were fractionated with a HPLC-based method. Sugar content and total anthocyanins increased in the cluster thinning treatment, while they were little affected by leaf removal. Changes in concentrations were not due to alterations of the skin/berry weight ratio. Cluster thinning induced significant increases in cyanidin 3-glucoside and peonidin 3-glucoside concentrations. On the contrary the contents of delfinidin, petunidin and malvidin 3-glucoside were not affected by the treatment.