Weather trend and impact on sugar accumulation in Montepulciano grapes in a viticultural area of central Italy

¹ Department of Agricultural, Food and Environmental Sciences, University of Perugia, Italy
² RegionalAgrometeorological Center, Abruzzo region, Scerni (Chieti), Italy

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Abstract

The increase in temperatures and frequency of drought summers is reshaping viticulture, favoring cooler and higher-altitude areas while challenging traditional wine-growing regions. This study examines the relationship between climatic variables and sugar accumulation in Montepulciano grapes in Villalfonsina (Abruzzo, Italy) over the period 1998-2022, using data from a cooperative winery and a regional weather station.Results show a significant rise in seasonal temperatures since 2010, with growing degree days (GGDs) increasing by 7.5%, from 1,988 (1998-2009) to 2,135 (2010-2022). High-temperature events (above 30°C and 35°C) doubled and quintupled, respectively, leading to photoinhibition, leaf necrosis and berry dehydration. The day-night temperature range also increased by 40%, negatively affecting metabolic processes such as sugar transport.Harvest dates were highly variable, with 50% of the grapes harvested between September 29 and October 16. Sugar concentrations ranged from 17.3°Babo (2014) to 20°Babo (2022), with recent vintages consistently exceeding 19°Babo, enabling wines with alcohol levels between 13.3% and 13.8%.This research emphasizes the importance of adapting vineyard practices and choosing harvest dates to reduce climate stress and maintain wine quality as the climate continues to change.