Effects of Irrigation on the Performance of Grapevine cv. Tempranillo in Requena, Spain

Abstract

The effects of moderate irrigation rates on vegetative growth, vine evapotranspiration, yield, and grape and wine composition were studied during six consecutive seasons in a mature vineyard planted with Vitis vinifera cv. Tempranillo in Requena, Spain. Vines were spur-pruned and trained to a bilateral cordon. Rain-fed vines received a yearly average rainfall of 368 mm, of which 169 mm occurred from April to harvest. Irrigated vines on average received 86 mm per year of additional water applications. Irrigation increased vegetative growth and vine evapotranspiration. As a result, yield was 31% higher in the irrigated vines. This increase in yield was primarily due to larger berry size and was correlated with vine evapotranspiration estimated by soil water balance. Irrigation did not alter the balance between the vine demand and the supply as indicated by the similar level of yield to pruning weight and leaf area to yield ratios observed in both irrigated and nonirrigated vines. On average over years irrigation had some minor negative effects on wine composition. It altered the balance between malic and tartaric acid, increasing the former and decreasing the latter. Irrigation also led to an increase in wine pH that together with a slight decrease in anthocyanin concentration reduced color intensity by 18%. However, the effects of irrigation on must and wine composition were largely different among years, probably because of the different rainfall amount and crop levels. Thus, under high crop level, irrigation tended to mitigate the negative effects of increasing yield on wine alcohol content.