Terroir and vine water relation effects on grape ripening and wine quality of Syrah/R99

Following the acquired awareness of the presence of ochratoxin A in grape derivatives, actions were undertaken to contain this contamination, and attempts were made to evaluate the presence of any other molecule belonging to this class.

La présente étude de zonage viticole a été faite dans la région de la vallée Central de Tarija(VCT), dans la ville de Tarija, au Sud de la Bolivie; une région avec plus de 400 années de tradition qui présente une vitiviniculture de haute qualité. La Vallée possède une surface total de 332 milles ha.; existant des vignobles entre 1660 y 2300 m.s.n.m. et dans ce rang d’altitude il existe 91 mille ha.

Soil is a reservoir of microorganisms playing important roles in biogeochemical cycles and interacting with plants whether in the rhizosphere or in the root endosphere. Through rhizodeposition, plants regulate their associated microbiome composition depending on the environment and plant factors, including genotypes. Since the phylloxera crisis, Vitis vinifera cultivars are mainly grafted onto American Vitis hybrids. Rootstocks play a pivotal role in the grapevine development, as the interface between the scion and the soil.

Context and Purpose. Management of plant-parasitic nematodes in perennial cropping systems such as wines grapes is challenging.

In the last decades the growers of the Portuguese Dão winegrowing region (center of Portugal) are experiencing changes in climate that are influencing either grape phenology berry health and ripening. Aiming to study the relationships between climate indices (CI), seasonal weather and grapevine phenology, in this work long-term climate and phenological data collected at the experimental vineyard of the Portuguese Dão research centre between 1958 and 2019 (61 years) for the red variety Touriga Nacional, was analyzed. The trends over time for the classical temperature-based indices (Growing Season Temperature – GST -, Growing Degree Days – GDD, Huglin Index – HI and Cool Night Index – CI) presented a significantly positive slope while the Dryness Index (DI) showed a negative trend over the last 61 years. Regarding grapevine phenology, an average advance of 4.5 days per decade in the harvest day was observed throughout the last 61 years. Consequently, the weather conditions during the ripening period have changed, showing an increasing trend over time in the average temperature (higher magnitude in the maximum than in the minimum temperature) and a decrease in the accumulated rainfall. A regression analysis showed that ~50% of harvest date variability over years was explained by the temperature-based indices variability. These observed effects of climate change on bioclimatic indices and corresponding anticipation of harvest date can still be considered advantageous for the Dão terroir as it allows to achieve an optimal berry ripening before the common equinox rains and, therefore, avoid the potential negative impacts of the rainfall on berry health and composition.