Abstract
The objective of the research was to evaluate the effect of climatic extremes on the response of Tempranillo compared to the average recorded over 20 years in the Ribera del Duero DO, and to assess the main variables driving the changes and differences at different elevations. To achieve these objectives, phenological dates and grape composition were evaluated in 12 plots distributed within the DO at elevations between 725 and 915 m above sea level. Variations were related to climatic variables analysed in weather stations located in the vicinity of the plots studied. All phenological stages were advanced in the extreme hot conditions, with maturity and flowering advancing by up to 15 and 8 days, respectively. High temperatures and water deficit caused a decrease in berry weight. Grape acidity and malic acid were significantly reduced by the high temperatures during ripening (up to 8 and 30%, respectively). Phenolic composition was also affected under high temperatures, with reductions in total anthocyanins > 20%, and up to 8% in the extractable fraction, particularly at the lowest elevation, resulting in a decoupling between sugar and phenolic composition. In contrast, under extreme wet and cold conditions, acidity and total and extractable anthocyanins increased significantly (up to 18%, 20% and 2.9%, respectively). All these changes were associated with differences in maximum and minimum temperatures and water availability not only during ripening, but also during previous periods. The results allowed quantifying the effects of climatic extremes on this cultivar and give an idea of the expected effects if warmer scenarios are imposed.