Grapevine Phenology of White Cultivars in Rueda Designation of Origin (Spain) in Response to Weather Conditions and Potential Shifts under Warmer Climate

Grapevines are among the crops that could suffer stronger effects under climate change, although the effect can differ based on cultivars and location. The aim of this work was to analyse the phenological response of the Verdejo variety compared to other two white varieties (Viura and Sauvignon Blanc) cultivated in Rueda Designation of Origin (DO), Spain, under the present climate conditions, and their potential shifts under projected climate change scenarios. Phenological dates referring to budbreak, flowering, v&eacute:raison and harvest were analyzed for the period 2008&ndash:2021 in 13 plots, together with the weather conditions at daily time scale recorded during the same period. The chill and heat units were evaluated to determine the starting date for heat accumulation, as well as the base temperature to reach each phenological stage. The influence of temperature (maximum and minimum) and water availability averaged for different periods between phenological events were evaluated, and the information was used to project potential changes in phenology by 2050 and 2070 under two Representative Concentration Pathway (RCP) scenarios: RCP4.5 and RCP8.5. An advance of all phenological dates was projected, in particular for v&eacute:raison and ripening. Verdejo could suffer slightly higher advance than Sauvignon Blanc, and, in any case, ripening will happen under warmer conditions. By 2050, flowering could be advanced between seven and nine days, depending on the emission scenario. However, v&eacute:raison could be advanced about 13 or 14 days under the RCP4.5 scenario and between 16 and 19 days under the RCP8.5 scenario. Ripening could be reached by 2050 up to 20 days and 25 days earlier, respectively, under the RCP4.5 and the RCP8.5 emission scenarios, and up to 29 days earlier by 2070. These projections may imply further impacts on grapes and wines for the aforementioned cultivars associated to harvest under warmer conditions.