Vegetative, Yield, and Berry Quality Response of Aglianico to Shoot-Trimming Applied at Three Stages of Berry Ripening

The rise in air temperature due to climate change is causing an increase in the sugar accumulation rate in grape berries, resulting in increased wine alcohol concentrations. Postveraison leaf area removal (defoliation, shoot-trimming) is a suitable canopy management strategy to slow carbohydrate accumulation in the berries. However, in late-ripening cultivars, the phenological stage between veraison onset and harvest can be very long. Therefore, it can be hypothesized that the specific timing when leaf area removal is applied during the phenological stage can affect carbohydrate accumulation in the berries and berry composition. A two-year experiment was designed to compare the responses of Aglianico grapevines, a late-maturing cultivar, to shoot-trimming applied at three different stages of berry ripening. The experimental design included: (a) three trimming treatments applied at total soluble solids of 6, 12, and 18 Brix, respectively; and (b) a control treatment (untrimmed vines). Independent of the application timing, shoot-trimming decreased berry total soluble solids at harvest below that of control vines, but the later the shoot-trimming was applied, the lower berry total soluble solids was at harvest. Shoot-trimming did not affect other berry parameters. These results confirm that, at least for late-maturing cultivars, the timing of application of late shoot-trimming plays a key role in modulating the intensity of the effects of this management practice on berry composition.