Effect of Partial Grapevine Defoliation (Vitis vinifera) on Wine Quality

The wine quality was determined for partially-defoliated grapevines grown in Villa de Leyva, Colombia at an elevation of 2,143 masl. The experimental design was totally randomized, with two treatments (50% defoliation and 0% defoliation) and three repetitions per treatment. The planting material consisted of five-year-old vines of Vitis vinifera cv. Chardonnay, trained to trellises, with a spacing of 2.1 m x 1 m. Every fifteen days, the plants in the defoliation treatment underwent the removal of half of the newly-emerged leaves. Before undertaking the micro-vinification process, the total soluble solids (TSS) were measured in the grape must, and after a fermentation of 100 days, wine quality parameters were measured, namely: residual sugars (TSS of the wine), pH, total titratable acid (TTA), and potential alcohol content of the wine. In the plants undergoing partial defoliation, the total soluble solids in the grape must increased, as well as the wine pH and potential alcohol content. At the same time, total titratable acid decreased in the wine of partially-defoliated plants. These results demonstrate that the wine quality was greatly improved by the reduction of leaf area in Chardonnay variety grape plants.