Effect of leaf thinning on micronutrient uptake and redistribution in grapes and on wine content

Abstract

This study investigated the uptake and distribution in grape tissues of the micronutrients copper (Cu), zinc (Zn) and manganese (Mn), in a 16 year-old ‘Cabernet Sauvignon’ vineyard and their relationship with wine nutrient content. The analysis was carried out in two plots with differences in vigor, grown in a calcareous soil. Two different management treatments (with and without leaf thinning after bloom) were applied in each plot. Partitioning and distribution of micronutrients (Cu, Zn and Mn) in petiole, seeds and skin were evaluated from veraison to harvest, as well as the concentration of those elements found in wines elaborated with grapes grown under each plot and treatment in 2013. The relationship between micronutrients and grape parameters such as pH, total acidity and berry weight were also evaluated. The results showed that micronutrient concentrations varied in a different way between organs during ripening. Cu and Zn in petioles had higher concentration at veraison than at harvest, while for Mn the concentrations were higher at the end of the cycle. Some relationships between metal content in petiole and in seeds were found. Differences in concentration were found between the areas with differences in vigor. Cu and Mn concentrations in petiole, skins and seeds were higher in the leaf thinning treatment, but the results were opposite for Zn. However, Cu and Zn concentrations in wines were higher in the plots without treatment and no differences were found for Mn.