Grapevine varietal diversity as mitigation tool for climate change: Agronomic and oenologic potential of 14 foreign varieties grown in Languedoc region (France)

Viticulture and wine production have a historical tradition in Istria. First written document of vine cultivation in this area date since antiquity. The most wide spread vine variety in Istria is Istrian Malvasia (white variety), and it capture about 60% of total vineyard surface in Istria today.

Climate change presents a significant challenge to grape growing worldwide as increased temperatures lead to wines with increased sugar and pH levels. Manipulation of the exposed leaf area is a powerful lever governing the assimilation and storage of non-structural carbohydrates in grapevines. Reducing the leaf-to-fruit ratio is now considered as a tool for adapting to hotter and dryer grape growing conditions.

Increasingly warm and dry climate conditions are challenging the viticulture and winemaking sector. Digital technologies and crop modelling bear the promise to provide practical answers to those challenges. As viticultural activities strongly depend on harvest date, its early prediction is particularly important, since the success of winemaking practices largely depends upon this key event, which should be based on an accurate and advanced plan of the annual cycle. Herein, we demonstrate the creation of modelling tools to assess grape ripeness, through sugar concentration monitoring. The study area, the Portuguese Côa valley wine region, represents an important terroir in the “Douro Superior” subregion. Two varieties (cv. Touriga Nacional and Touriga Franca) grown in five locations across the Côa Region were considered. Sugar accumulation in grapes, with concentrations between 170 and 230 g l-1, was used from 2014 to 2020 as an indicator of technological maturity conditioned by meteorological factors. The climatic time series were retrieved from the EU Copernicus Service, while sugar data were collected by a non-profit organization, ADVID, and by Sogrape, a leading wine company. The software for calibrating and validating this model framework was the Phenology Modeling Platform (PMP), version 5.5, using Sigmoid and growing degree-day (GDD) models for predictions. The performance was assessed through two metrics: Roots Mean Square Error (RMSE) and efficiency coefficient (EFF), while validation was undertaken using leave-one-out cross-validation. Our findings demonstrate that sugar content is mainly dependent on temperature and air humidity. The models achieved a performance of 0.65

Natural factors such as the environment in which the vine is grown play an important role in the quality of the wine. If you want to produce a good wine, it is indeed essential to produce quality grapes. To do this, we must enhance and optimize the terroir effect which, for the moment, plays a role that is not very well known. It is therefore essential, for example, to have scientifically established and well quantifiable relationships in order to have the system of areas of controlled origin accepted. R. Morlat (1989) and G. Seguin (1970) have already carried out studies on the role of certain soil factors on grape quality. In particular, they showed the importance of soil temperature and water content.

Phosphonic acid and especially potassium dihydrogen phosphonate are widely used to restrain the ubiquitous pressure of grapevine downy mildew in viticulture. Nevertheless, phosphonic acid and its derivatives have been banned in organic viticulture in October 2013, because they have been classified as plant protection products since then.