Climate, grapes, and wine: structure and suitability in a variable and changing climate

Climate change is a major challenge in wine production. The IPCC (2014) projected that by the end of the 21st century average temperatures will increase by 1-3.7°C. Consequently, harvest dates could advance by approximately 30 days. A general observed trend is the increase in berry sugar content and decrease in organic acids, posing challenges for winegrowers. Variability among cultivars is a precious resource to adapt viticulture to a changing environment.

Knowledge of the nitrogen nutrition status of grapevines is essential for the sustainable management of their nutrition for the production of quality grapes. The measurement of the chlorophyll index is a rapid, non-destructive and relatively inexpensive method that provides a good approximation of the nitrogen nutrition status of the vine during the season. Interpretation thresholds are currently insufficient or non-existent for some chlorophyll meters. Ideally, they should be available for each variety and each phenological stage. In order to popularize the use of chlorophyll-meters, measurements were carried out at Agroscope in Switzerland to establish the correlation between the indices obtained by the devices N-tester and SPAD 502.

Although several studies investigated the impact of crop size or fruit zone microclimate on aromatic or phenolic composition of wines, the effects of these two practices were not assessed and compared in the same study through a technological experiment within the same vineyard. Therefore, their relative effectiveness is hard to compare, which in turn is essential for providing producers with valuable information as a basis to choose adequate approach in yield and canopy management. The aim of the study was to investigate the effects of two crop sizes and two different fruit zone microclimate conditions obtained by leaf removal in a two-factorial experiment, in order to assess and compare their relative impact on Istrian Malvasia (Vitis vinifera L.) white wine aroma and phenolic composition.

Current changes of ecoclimatic indicators may cause significant variation in grapevine phenology and grape ripening. Climate change modifies several abiotic factors (e.g. temperature, sunlight radiation, water availability) during the grapevine growth cycle, having a direct impact on the phenological stages of the grapevine, modulating the metabolic profile of berries and activating the synthesis and accumulation of diverse compounds in the skin of berries, with consequences on the composition of the grapes.
The influence exerted by different meteorological conditions, during three consecutive years (2020-2022) on secondary metabolites such as the polyphenolic profile of Grignolino grapes was investigated. The samples were collected from three vineyards characterized by different microclimatic conditions mainly related to the vineyard aspect and to a different age of the plants.

Sustainable viticulture and winemaking continue to represent huge challenges, where a better knowledge about the functional role of biodiversity in the vineyard ecosystems is required.