Atmospheric drivers of grapevine water dynamics in Mediterranean terroirs

Abstract

Grapevine (Vitis vinifera L.) performance in Mediterranean wine regions is strongly influenced by atmospheric variables that shape the soil-plant-atmosphere continuum and ultimately contribute to biophysical terroir expression. Elevated vapour pressure deficit (VPD), driven by high air temperatures and intense solar radiation, frequently coincides with progressive soil water depletion during summer, intensifying plant water stress and constraining physiological activity. This study evaluates the influence of atmospheric demand on grapevine water dynamics in commercial vineyards of the Douro Demarcated Region (Portugal) through continuous automated and non-destructive plant-based monitoring techniques, namely sap flow measurements at trunk and root level and trunk diameter fluctuations, integrated with weather variables and soil moisture observations across several growing seasons. The combined analysis allowed the characterization of short-term physiological responses under contrasting evaporative demand scenarios. Results indicate a strong dependence of vine water dynamics on atmospheric forcing, particularly VPD, with reduced sap flow rates and attenuation of trunk diameter oscillations under severe conditions, especially during maturation. A marked midday depression of sap flow was frequently observed under elevated VPD and high reference evapotranspiration, reflecting partial stomatal closure and limited nocturnal rehydration capacity. In several periods, physiological regulation was primarily driven by atmospheric demand even when soil water availability remained within non-limiting ranges, highlighting the predominance of short-term atmospheric control over vine responses. Plant-based indicators proved to be effective tools for detecting early water stress signals and for improving the understanding of vine-atmosphere interactions. The integration of atmospheric drivers, soil water availability and physiological indicators contributes to a deeper understanding of terroir functioning under current and future climate conditions, supporting adaptive vineyard management strategies in warm and dry wine-growing regions.

References

Dinis, L. T., Bernardo, S., Yang, C., Fraga, H., Malheiro, A. C., Moutinho-Pereira, J., & Santos, J. A. (2022). Mediterranean viticulture in the context of climate change. Ciência e Técnica Vitivinícola, 37(2), 139–158. https://doi.org/10.1051/ctv/ctv20223702139

Malheiro, A. C., Pires, M., Conceição, N., Claro, A. M., Dinis, L. T., & Moutinho-Pereira, J. (2020). Linking sap flow and trunk diameter measurements to assess water dynamics of Touriga-Nacional grapevines trained in cordon and Guyot systems. Agriculture, 10(8), 315. https://doi.org/10.3390/agriculture10080315