Grapevine and climate change: Response of two varieties of Tempranillo (red and white)

According to the intergovernmental panel for climate change (IPCC), an increase in the atmospheric carbon dioxide concentrations (CO2) (up to 700 ppm) is predicted for 2100 (IPCC, 2007a). Consequently, the average global temperature may increase between 1.8 and 4 degrees C in the next years (IPCC, 2007b). Also, plant water availability for crops could be reduced (IPCC, 2007a). These environmental factors may compromise grape ripening and must composition. In this regard, varietal and genetic diversity may be exploited to maintain grape and wine quality under future warm conditions. The scope of this thesis was to study the effects of climate change, elevated CO2, elevated temperature and drought (acting independently or in interaction) on grape yield and quality of two cultivars of grapevine (Vitis vinifera L.) cv. Tempranillo (red and white). In addition, the thesis aimed to investigate the effect of high temperature on grape yield and duality of six clones of Tempranillo. Two experiments with fruit-bearing cuttings were performed. In the first one, carried out in four temperature gradient greenhouses (TGGs), plants were exposed to ambient or elevated CO2 (ca. 700 ppm), combined with ambient temperature or elevated temperature (plus 4 degrees C) and two water regimes (well-watered or drought), from fruit set to maturity. In the second experiment, six clones of red Tempranillo were grown under two temperature regimes (24 degrees C-14 degrees C or 28 degrees C-1 8degrees C, day-night). Fruit yield, technologic and phenolic maturity parameters were measured at ripeness. The combination of elevated CO2, temperature and drought (climate change conditions) did not significantly modify grape yield and grape size in any of the cultivars studied. Regarding grape quality, climate change conditions reduced total polyphenol index (TPI) and malic acid concentration, decreased color density and did not modified the concentration of anthocyanins and total acidity in the red cultivar, when compared to current conditions. In white Tempranillo, tartaric acid was the only parameter that was modified under climate change conditions, although drought increased TP1 under ambient temperature, regardless of CO2 level. With regard to the six clones of Tempranillo, elevated temperature did not significantly reduced, in general, grape yield, except in done 1089. Clones 8, 260 and 843 were the most affected by temperature, showing a decrease in malic acid, TPI and anthocyanins, and increases in tartaric acid and tonality. On the contrary, clones 280 and 1089 were affected to a lesser extent by temperature. Results suggest that future climate change conditions can lead to significant changes on grape quality, especially in the case of red Tempranillo. Clones 280 and 1089 of red Tempranillo may be good candidates to maintain grape quality standards in a future warming.