Influência da desfolha na qualidade de uvas merlot produzida na região da campanha do Rio Grande do Sul, Brasil

Abstract

The Campanha Gaúcha region has been consolidated as a great wine-producing region, it’s responsible for over 20% of wines from Vitis vinifera grapes production on Brazil.Their grapes are already known feedstock for the production of great wine with aging potential and better structured in relation to the amount of alcohol, phenolic compounds and aromatic compounds. Although the region is thriving in the sector it is necessary to research new varieties and management methods that increase the quality of the grapes that are already in production. In case of this study, the grape variety in focus is ‘Merlot’, which has excellent productivity, good maturity, but below the desired color.Thus, this study aimed an effective method to promote the concentration of phenolic compounds in Merlot wines produced from grapes of Bagé, Rio Grande do Sul state, Brazil. Defoliation is an effective method to increase the solar radiation in bunches, which provides an increase in the production of phenolic compounds, among which the color.For this purpose were tested six defoliation treatments with variations in the production stage of the vine and their solar position.Therefore the following treatments were installed: defoliation at the beginning of growth ("chumbinho") on the east side, morning sun (DGL); defoliation in “chumbinho” grain stadium to the west side, the afternoon sun (DGO); defoliation in the beggining of growth grain stage on both sides (DGLO); defoliation at the color change phenological state east side (DML); defoliation at the color change phenological state west side (DMO); defoliation at the color change phenological both sides (DMLO); and a control treatment without defoliation (T). The experiment was carried in property from municipality of Bagé, during harvesting 2013/14 on vines 12 years, Merlot grape variety, R8 clone, grafted on Paulsen 1103. For each treatment were made three replicates on field, with five plants each. The grapes were harvested at end of February 2014 and they’re sent to experimental winery UNIPAMPA Campus Dom Pedrito. Upon arriving at the winery each unit berries samples were collected and after the extraction of must were made physicochemical analysis by Fourier transform infrared spectrometry (FTIR), on Laboratory located at the Federal University of Pampa Dom Each of the twentyone treatments were vinified in bottles of 20 liters Pedrito Campus, during the vinification.. The results demonstrated that defoliation promoted significant differences in physicochemical composition in must and wine. On must is observed that DGO presented lower amount of total soluble solid including in relation to treatment T, and for this the highest value parameter was found in DML treatment. DML had the highest total acidity, T had the lowest result. The

highest values concerning the total polyphenols and color intensity were observed in DML treatment and in same parameters were noted lowest values on T. It’s concluded that defoliation influences importantly the polyphenolic matrix having DML the largest positive difference.