Assessing the influence of climate change and clonal diversity on berry composition of Malbec

Abstract

Over the 21st century, the projected increases in regional temperatures and shifts in rainfall patterns and extreme weather events are expected to have important consequences on viticulture. They vary from short-term impacts on wine volume and quality, to long-term issues such as varietal or vineyard suitability to remain economically sustainability. With a focus on Malbec in France, this study aimed to assess the influence of climate change and clonal diversity on berry composition. The first part investigated the extent to which climate change has altered the berry composition of Malbec, cultivated in the Touraine sub-region of the Loire Valley. A long-term evaluation (1971-2020) was made concerning the modifications in sugar and total acidity content, including the ripening speed and specific heat requirements to reach different sugar levels. The second part evaluated the berry composition traits (sugar, total acidity, pH and berry weight) of 216 Malbec clones, prospected initially in Cahors and Touraine (France), including Mendoza (Argentina). These selected clones were then studied during 7 consecutive seasons (2014-2020) to understand the influence of the intra-varietal diversity of Malbec on berry composition. The results showed important modifications for berry composition and ripening speed, with significant higher sugar and lower total acidity contents over the past 50 years. Findings further revealed a strong intra-varietal diversity for the studied berry composition traits, highlighting the importance of gaining a deeper understanding of the intra-varietal spectrum and their adaptive potential to climate change.