Response of tempranillo (vitis vinifera l.) clones to climate change-related factors (elevated temperature, high CO2 and water deficit)Plant performance and berry composition

Résumé

SUMMARY Climate change is expected to modify future environmental conditions, therefore affecting agriculture. Tempranillo, a largely cultivated worldwide grapevine (Vitis vinifera L.) red variety, will be affected by the increase of global mean temperature and atmospheric CO2 levels and the decrease of water availability in its cultivation area. The use of the intra-varietal diversity has been proposed as a strategy for keeping wine typicity and regional varieties cultivation under future growing conditions by shifting the ripening phase to more favourable environmental conditions. The aim of the thesis was to determine the response of different clones of Tempranillo to simulated 2100 environmental conditions, focusing on plant growth and development, as well as on berry composition. Fruit-bearing cuttings of Tempranillo clones, which differed in the length of their reproductive cycle, were exposed from fruit set to maturity to different scenarios of climate change in temperature gradient greenhouses (TGG) and growth chamber greenhouses (GCG). The impact of elevated temperature (+4 °C), elevated CO2 (700 ppm) and water deficit, both in combination or independently, were evaluated. The results show an increment of vegetative growth and a reduction of yield due to high temperatures. Elevated CO2 concentration also increased vegetative growth and photosynthetic activity, even though an acclimation process was observed, being stronger when combined with high temperature. Water deficit reduced severely the photosynthetic activity and vegetative growth, overshadowing the temperature and CO2 effects. Elevated temperature, both individually and combined with high CO2 levels, hastened sugar accumulation and advanced maturity, but these effects were mitigated by water deficit. Malic acid degradation was also enhanced by high temperature, especially when combined with elevated CO2 and water deficit. Amino acid concentration and profile were affected by high temperature, elevated atmospheric CO2 and, especially, water deficit. Elevated CO2 reduced the effect of temperature decoupling the anthocyanin and TSS accumulation; however, the combination of elevated temperature, high CO2 and water deficit led to the imbalance between these two grape components. Anthocyanin profile was modified by climate change, high temperature increasing the relative abundance of acylated forms and both elevated CO2 and drought favouring the relative content of malvidin and acylated, methylated and tri-hydroxylated forms. The clones studied showed differences in their phenological development, vegetative and reproductive growth, as well as in their grape composition. In addition, the results reveal the existence of a differential response of Tempranillo clones to the environmental conditions projected for 2100 in relation to plant performance and grape composition. In general, RJ43 was the most affected by the future growing conditions (high temperature, elevated CO2 and water deficit) among the clones studied in terms of phenology and anthocyanin concentration and profile. Conversely, VN31 maintained the highest anthocyanin and anthoycianin:TSS ratio, whereas 1084 had the lowest sugar, malic acid and anthocyanin levels. The differences observed in the response of the clones to climate change not always depended on their reproductive cycle length. Keywords: Climate change; Grapevine; Tempranillo; Clones; Intra-varietal diversity; Vegetative development; Grape composition; Anthocyanin profile.