Leaf removal and cluster thinnings trials in "Aglianico" grapevine.

Research has been carried out in “Aglianico del Vulture” production area in Barile county (Potenza). In 2004 the following treatments have been compared: 1) leaf removal in the basal part of the shoot (from the first node to the one following the last cluster) carried out at veraison time (50 % of coloured berries); 2) cluster thinning: removal of 40% of the clusters at veraison time; 3) leaf removal and cluster thinning as previous described; 4) control (untouched plants). Cluster on the distal portion of the shoot has been usually removed as well as the ones with anomalies, bad shape and delay in development. Moreover, cluster on weak shoots as well as on laterals has been removed. Histoanatomical observations on berries collected from the different treatments at harvest have been carried out, as well as chemical analyses on grapes and wines obtained from separated microvinifications. Moreover, leaf gas exchange have been measured. Treatments slightly affected berry histoanatomical characteristics: from sections has been possible to observe anthocyanins and tannins accumulation in the skin external layers. Gas exchange parameters didn’t show large differences among the four treatments, nevertheless net assimilation rate and leaf water use efficiency increase when cluster thinning and leaf removal plus cluster thinning are applied to the crop. Maturation parameters didn’t show big differences among the various treatments, even if a slight increase in total and extractable anthocyanins has been observed with leaf removal.