Will climate change affect the Tempranillo Blanco grape variety in a similar way as Tempranillo in the Rioja Designation of Origin?

The aim of this study was to analyse the potential changes in phenology and grape composition of ‘Tempranillo Blanco’ compared to those for ‘Tempranillo’ in La Rioja. Phenologi cal dates referred to bloom, veraison and maturity and grape composition during ripening were evaluated for the period 2014-2023 and related to climatic variables in two climato logically different zones (Rioja Alta and Rioja Oriental) and for the projected changes in temperature and precipitation under different emission scenarios (SSP2-4.5 and SSP5-8.5). An advance in phenology is projected under climate change for both varieties, in agreement with that observed in years with different weather conditions. Bloom, veraison and maturity could be advanced 4, 6 and 11 days and 5, 6 and 12 days, respectively for ‘Tempranillo Blanco’ and ‘Tempranillo’ by 2050 under the SSP2-4.5 scenario. The advance could be up to 1.6 times higher under the SSP5-8.5 scenario. Similar decrease in titratable acidity and malic acid is observed for both varieties with increasing minimum temperature during ripening (0.11 and 0.13 g.L-1 for 1°C increase, respectively for t itratable acidity and malic acid), which may be enhanced with increasing water deficits, not only during ripening (0.15 and 0.12 g.L-1 per a decrease of 10 mm in the availa ble soil water) but also during the bloom-veraison period (0.06 g.L-1 and 0.05 g.L-1, respectively for the white and red variety). Thus, under the projected increase in temperature and decrease in precipitation, both varieties will suffer a decrease in acidity, which would have more negative implica t ions for ‘Tempranillo’ than for ‘Tempranillo Blanco’.