Resumen de Priorat vineyard vulnerability and water stress assessment in the context of global climate change. Estimated priorat wine consumption in humans

Antoni Sánchez Ortiz

• The Grenache and Carignan varieties are widely spread in the wine-growing areas of the northwest of the province of Tarragona, especially in the Terra Alta, Montsant and Priorat Denominations of Origin, where they form the basis of the VQPRD. Global change is inducing significant variations in the phenology, production and quality of the vine, which strongly depend on the specific region, and which show the vulnerability of this crop and the final quality of the grape and wine in the face of sustained increases in temperature or significant reductions in water availability. Two important aspects are needed to assess: on the one hand, ecophysiological and genetic variability aspects related to water use efficiency and, on the other, the effects induced by mesoclimatic variations, and specifically of temperature and water availability. The knowledge acquired will make it possible to better assess the vulnerability of viticulture to global change and also identify ways to reduce its presumed impact.

  One of the elements of greatest interest is the effect of climate and soil in relation to the development of the vine, deepening the study of the effect of annual climate variability, as well as its interaction with the soil and its water reserve capacity. Although water stress favours the synthesis of phenols, the extreme weather conditions that occur in the Priorat region can have negative implications for the production and composition of the grape. To assess the water stress in grapevines together with a methodology for ABA determination allowed us to study in depth how the periods of little water availability and high temperatures can affect the synthesis of phenolic compounds that accumulate in fruits. Since some studies show that ABA is involved in the mechanism that controls the synthesis of anthocyanins and intervenes in the synthesis of tannins that accumulate in the skin, analysis of the phenolic composition by HPLC of the final wine may be essential for the establishment of the quality parameters in relation to water stress.

  Secondly, validating a small-scale methodology used in heterogenous vineyard studies is one of the objectives of this project. This research would indicate the pros and cons of employing different volumes of small-scale fermentation. Some phenols in wine are released more easily than others. When a sample is not large enough to undergo large-scale fermentation, the total phenols cannot be fully extracted from the wine. This gap would be filled by examining how different volumes could affect the composition of the resulting wines and which would be large enough to conclusively represent a specific winemaking procedure.

  Lastly, phenolic compounds of wine have also attracted much interest due to their potentially beneficial effects for human health. Based on the low bioavailability, it was estimated the efficacy intake of 5 mesoclimatic different Priorat wines. It was evaluated the beneficial effects of different ranges of recommended intake for wine depending on gender, age and activity factor.

  This thesis provides an added value that allows extrapolating the results in the plant and in wine at a commercial level, so that a link of superior knowledge can be reached to validate research studies in the field of vine physiology and micro-fermentations in studies of extraction of phenolic compounds in red wines. The determination of the relationships between ecophysiological parameters and grape composition will allow us to define with greater knowledge both the agronomic potential and the oenological potential of the varieties under study. All this focused on improving certain agronomic practices that guarantee the sustainability of the vine as a crop within the DOQ Priorat and also advise some oenological practices based on the changes in phenolic composition observed in the grapes.