The challenge of adapting grapevine varieties to climate change

Climate change is expected to advance grapevine phenological stages. After the calibration and the validation of a degree-days model, we were able to accurately simulate dates of budbreak, flowering and véraison for Riesling and Gewurztraminer, 2 winegrape varieties grown in Alsace, France. Projected daily temperatures were calculated for the local meteorological station with the ARPEGE-Climat general circulation model using 3 distinct greenhouse gas emissions scenarios. Compared with its timing in 1976–2008, véraison is predicted to advance by up to 23 d and mean temperatures during the 35 d following véraison are projected to increase by more than 7°C by the end of the 21st century for both varieties. Such changes will likely have a significant impact on grape and wine quality. Using the same framework, the genetic variability of phenological parameters was explored with 120 genotypes of progeny from a Riesling × Gewurztraminer cross, along with 14 European varieties. In addition, we created a virtual late ripening genotype, derived from a cross between Riesling and Gewurztraminer. This modelled genotype was projected to undergo véraison 2 to 3 d before Muscat of Alexandria, one of the latest ripening varieties studied. Even with this virtual genotype, or with Muscat of Alexandria, grapes would ripen by the middle of the 21st century under higher temperatures than in the present years. This study highlights the important changes that viticulture will likely face in a future warmer climate and emphasises the need to create very late ripening genotypes or genotypes able to produce high quality wines under elevated temperatures.