Terroir effects on the response of Tempranillo grapevines to irrigation in four locations of Spain: grape and must composition

This work discusses the effects of soil and weather conditions on the grape composition of cv. Tempranillo in four different locations of Spain, during the 2008-2011 seasons. In all locations vines were pruned to a bilateral cordon, trained to VSP and under similar cultural practices. In three locations (Requena-east, Badajoz-west and Valladolid-northwest) a pre-veraison deficit irrigation strategy (DIP, where irrigation was withheld until a certain level of vine water stress was reached, and afterwards was irrigated at full ETc) was compared to rain-fed vines; while in the fourth location (Albacete-central), DIP was compared to a sustained deficit irrigation (SDI, irrigated at 33% ETc season long). In all locations, except in Valladolid, irrigation at full ETc season long was also studied. Using common analytical procedures, total soluble solids (ºBrix), malic and tartaric acids, pH, total acidity, total phenolics compounds (TPC), anthocyanins and tannins were determined, and the ratios Ant/ºBrix, TPC/ºBrix and Tan/ºBrix calculated in order to compare the phenolics accumulation as function of berry sugars concentration.

Compared to Rainfed, DIP increased ºBrix in all locations and reduced the Ant/Brix ratio, except in Albacete. The effects on the other compositional parameters varied largely depending on location. Irrigation at full ETc compared to Rainfed increased TA in all sites, but practically unaffected ºBrix nor the Ant/Brix ratio, especially in Albacete and Badajoz. However, in Requena full irrigation slightly decreased ºBrix and produced the highest reduction of the Ant/Brix ratio. Thus, our results show that the effects of irrigation on the accumulation of secondary metabolites of grape composition are in large part determined by the vineyard-to-vineyard terroir characteristics.