Spatial variability of temperature and grape berry composition at terroir scale in Uruguay

Abstract

The knowledge of wine region diversity requires fine scale assessment of climate, soil and management conditions. Climate conditions of coastal wine regions vary according to the distance to the sea and topography. These different terroir conditions play an important role in the grapevine behaviour as well as in the composition of grape berry and wine. The aim of this work was to study spatial temperature variability in relation to the grape berry composition of Tannat at harvest, in southern Uruguay. Temperature sensors were installed in commercial vineyards of Tannat in the most important wine region of the country. Different distances to the La Plata River estuary, soils diversity and topography were taken into account. Temperature data obtained from ten plots in summer 2012 was analyzed and related to grape berry composition (sugar concentration, titratable acidity, pH, total and extractable anthocyanins potentials and phenolic richness). Results showed significant differences in spatial temperature highlighting the moderating effect of the estuary on temperature. Daily thermal amplitude increased with distance from the river. Plots situated in valleys had similar behavior than those situated away from the river, due to faster heat gain and loss. In the other hand, plots near the river showed lower differences in temperature, during the season and during the day. Grape berry composition showed a significant variablity that could be associated with the plot location. Adjacent plots situated in valleys showed significant differences in sugar concentration and titratable acidity, while their secondary metabolites were similar. It suggests for this year of study, that topography conditions could have had greater effects on sugar and acid than on polyphenol levels. The increasing knowledge of temperature spatial variability and its relation with grape berry composition contributes to improving canopy management during ripening period.