Vineyard adaptation to climate change is one of the biggest challenges for viticulture. Wine quality suggests matching wine typicality, agro-climatic conditions and growing practices. Logically the increasing temperature and the change in rainfall pattern, expected in the next decades, should bring changes in wine-making practices. In the Mediterranean region, this is even more problematic as the climate conditions already lead to more concentrated wine with high alcohol content, compromising the production objectives. Mechanistic modelling enables to better assess the impact of climate change on wine production and proposes innovative ways of vineyard adaptation.
As an example, the itk Company, specialized in the development of decision support tool, carries out a study in a representative vineyard located in Costières de Nîmes. This study is based on simulations carried out with Vintel software developed within a collaborative project involving INRA, CIRAD, IRSTEA, Languedoc wine-growers’ cooperatives, the regional department of agriculture (chambre d’agriculture) and the climate association of Hérault. It investigates the evolution of water deficit over 6 decades (1955-2014) and its effect on water management in the vineyard. Results show that the management type was optimal, in the 1955/1974 period, for the production of quality red wine without irrigation (Figure1). Climate shift from 1975 to 1994 then led to an increasing water deficit that progressively gets worse until 2014. Results confirm that the traditional management mode was well adapted to climate condition in the 1955/1974 period. However, it gradually becomes obsolete due to the steady increase of water deficit that compromised the production objectives. Irrigation offers an alternative to counter this evolution, but remains controversial due to the conflict of use of water resources. In this context, Vintel proposes to estimate vine water needs at daily time step in order to better control water consumption whilst complying with the specifications obligations. According to Vintel, irrigation can be manage through two strategies; “optimal irrigation” and “minimal irrigation”, so as to keep vine water status within the optimal range or on the borderline of the water stress threshold. The threshold chosen for irrigation triggering has a significant influence on cumulative amounts of water need (52%, Figure.2). Taking into account the vine training method, Vintel also enable to investigate strategies that help reducing water requirements, while preserving yield and quality objectives. Thus, an increase of inter-row spacing, 2.5 m instead of 2 m and compensated by an increase in canopy size, reduces water need by 24% in this study.
Results show that mechanistic model enable to assess innovative ways of vineyard adaptation to tackle the effect of climate change on wine quality. Vintel is a relevant tool to quantify such interaction, waiting for the long-term solution of the Laccave project (INRA, IFV).
Marek DUPUTEL & Philippe STOOP
Predict and Decide