Effects of soil physical conditions on the composition of Tannat wines

Abstract

A new viticulture has been developing in Uruguay in the last years, in order to improve the quality of the wines and to increase the typicity generated by the terroir. For this purpose, several vineyards were planted outside the traditional viticultural regions. Many of the new vineyards were installed on shallow soils with lower available water capacity, particularly in the eastern region of the Río de la Plata coast. In this context, this study assessed the relations between soil physical properties and wine composition, in order to characterize the production qualitative potential for different regions. The work was conducted from 2011 to 2013 in 4 non-irrigated Tannat commercial vineyards, located in Río de la Plata coast region. The grapes were harvested at technological maturity; then two vinifications at reduced scale for each vineyard were made. Basic wine composition was analyzed according to the classic methods proposed by OIV (2012). Color and polyphenolic composition were analyzed by spectrophotometry. Three soil texture classes over two types of parent rock were observed. The shallow, coarse-textured soils with lower water availability had higher concentration of compounds associated with wine quality, such as anthocyanins, proanthocyanidins and total polyphenols. The amount of available water potential in the root zone significantly affected the wine composition. According to edaphic conditions, it is possible to optimize quality wine production within the coastal region of Río de la Plata.