From Vine to Wine: The Relationship Between Ecoclimatic Factors and Grape Yield in Italy

Viticulture is a key business for Italy, significantly contributing to the country's economy and cultural heritage. Italy is the largest world wine producer, with an estimated wine production of 41.0 mhL (2024 World Wine Production - OIV First Estimates). The relationship between climate variability and wine grape yield is a critical area of research, particularly considering ongoing climate change.

This study evaluates this relationship by employing ecoclimatic indices computed on key phenological periods that are crucial for grape development and specifically tailored to the life cycle of grapevines throughout the entire growing season. These periods have been identified using a validated phenological development model that accounts for various grape varieties. In addition to examining the effects of climate variability, this research also considers the risks posed by major cryptogamic diseases that can lead to significant crop losses.

To ensure the validity and relevance of the findings, the study actively engages with growers and obtains yield data from two prominent Italian wine consortia based in Lombardy and Tuscany. This localised approach allows the specific climatic and agronomic characteristics of each region to be considered, as well as the different grape varieties grown there.

The methodology developed correlates the ecoclimatic indices with the collected grape yield data through both single and multiple regression analyses, quantifying the proportion of total yield variability that can be explained by these predictors, both individually and in combination. The findings indicate that the ecoclimatic indices account for approximately 25% to 50% of the variance in grape yield.

By presenting a novel set of ecoclimatic indices derived from contemporary knowledge of climate impacts on grapevine development, this study contributes to filling a gap in the current research framework.