Phenological characterization of major winegrape varieties in the Iberian Peninsula

The phenology of wine grapes has emerged as a crucial aspect for comprehending and forecasting the impacts of climate change on viticulture. This is due to phenology being essential in evaluating the suitability of grape varieties to future conditions. However, there is still a lack of quantitative characterization for key phenological stages in a majority of indigenous wine grape varieties from Spain and Portugal. Here we analyze the phenological responses to climate of predominant grape varieties in the Iberian Peninsula, including Tempranillo, Airen, Garnacha, Macabeo, and other varieties like Albariño, Godello, Pedro Ximenez, Fernão Pires (Portugal), which are extensively cultivated in specific regions. We compiled a comprehensive dataset from research centers and specialized organizations such as Origin Denominations across the Iberian Peninsula. The recorded field observations were then compared against well-established agroclimatic indices, such as Growing Degree Days (GDD), days with maximum temperature above 35°C, or days below 10ºC, amongst others. Even within our limited set of varieties, we observed surprising diversity in responses, supporting phenology-based varietal selection as an adaptive solution. This underscores the necessity to continue documenting phenology for many other locally understudied varieties. Our findings fill a knowledge gap, contributing to ongoing efforts in refining varietal selection strategies for adapting viticulture to climate change.