Cascading effects of spring weather conditions into grape berry ripening

Abstract

The effects of climate change on viticulture are complex due to interactions among factors and cascading effects. As temperature rises phenological stages are shortened, pushing ripening towards the warmest part of the season. The aim of this study is to assess the impact of shifts in bud break date on berry ripening. An experiment was conducted with Tempranillo (TE) and Cabernet sauvignon (CS) potted plants with treatments consisting in ambient, cold and warm temperatures for 20 days during the forcing period (end February and beginning of March). Forcing period temperature (FPT) influenced bud break date on average 25 days for TE and 19.5 days for CS (warm vs cold). These differences in phenology tended to moderate when plants reached flowering (23 days TE and 15 days CS) but remained quite spread by veraison (29 days TE and 14 days CS). Remarkably, maturity (ca. 23oBrix) came 33 days apart among treatments for TE while CS plants fully synchronized among treatments. Different ripening speeds were somewhat explained by the crop loads being affected by FPT. However, FPT greatly affected the mean temperature during ripening 3.3oC for TE and 0.7oC for CS. Ultimately, the different temperature during ripening affected berry and wine composition, demonstrating the benefits of delayed phenology. These results help to assess the potential of strategies involving late veraison as an adaptation for climate change.