Vineyard soil mapping to optimise wine quality: from ‘terroir’ characterisation to vineyard management

Crop Water Stress Index (CWSI) has long been a ratio to quantify relative plant water status in several crop and woody plants. Given its rather well relationship to either leaf or stem water potential and the feasibility to sample big vineyard areas as well as to collect quite a huge quantity of data with airborne cameras and image processing applications, it is being studied as a tool for irrigation monitoring in commercial vineyards. The objective of this paper was to know if CWSI estimated by measuring leaf temperature with an infrared hand held camera could be used to substitute the measure of stem water potential (SWP) without losing accuracy of plant water status measure.

In Alentejo, south of Portugal there is a traditional way of fermenting wines in clay vessels, known as “Vinhos de Talha”. Clay vessels were traditionally impermeabilized using pine pitch, creating a barrier between the fermenting must and the clay. Due to this unusual production technology that uses of clay vessels, instead of inox or wood vessels, “Vinhos de Talha” present unique characteristics increasingly appreciated by national and international consumers when compared with wine obtained by the said traditional methods of winemaking. Although the positive consumers feedback, there is little literature about the physical-chemical characteristics of these wines (Martins et al, 2018; Cabrita et al, 2018). This work aims to characterize the volatile composition of white wines produced in clay vessels with different coatings and to contribute to the knowledge and preservation of these wines that are a unique cultural heritage. Wine samples were produced during 2019 vintage from white grapes, using the traditional technology associated to these wines.

Terroir is not only a geographical site, but it is a more complex concept able to express the “collective knowledge of the interactions” between the environment and the vines mediated through human action and “providing distinctive characteristics” to the final product (OIV 2010). It is often treated and accepted as a “black box”, in which the relationships between wine and its origin have not been clearly explained. Nevertheless, it is well known that terroir expression is strongly dependent on the physical environment, and in particular on the interaction between soil-plant and atmosphere system, which influences the grapevine responses, grapes composition and wine quality. The Terroir studying and mapping are based on viticultural zoning procedures, obtained with different levels of know-how, at different spatial and temporal scales, empiricism and complexity in the description of involved bio-physical processes, and integrating or not the multidisciplinary nature of the terroir. The scientific understanding of the mechanisms ruling both the vineyard variability and the quality of grapes is one of the most important scientific focuses of terroir research. In fact, this know-how is crucial for supporting the analysis of climate change impacts on terroir resilience, identifying new promised lands for viticulture, and driving vineyard management toward a target oenological goal. In this contribution, an overview of the last findings in terroir studies and approaches will be shown with special attention to the terroir resilience analysis to climate change, facing the use and abuse of terroir concept and new technology able to support it and identifying the terroir zones.

Downy mildew, caused by the oomycete Plasmopara viticola (Berk. & M.A. Curtis) Berl. & De Toni, is one of the most destructive grapevine diseases mostly affecting Vitis vinifera L. and impacting on viticulture. The pathogen invasion can induce in grapevine multiple defense reactions, first PAMP-Triggered Immunity and secondly Effector-Triggered Immunity. Plasmopara viticola can overcome these defense mechanisms through the secretion of effectors, such as RxLR, into the plant cells, making it easier for the oomycete to infect grapevines. Currently, the use of chemical pesticides remains the most effective way to control the pathogen with severe negative side effects on the environment and animal health.

The communication of the aims of a viticulture under the premise of terroir is presently discussed in a lot of wine-growing regions around the world. To encourage this discussion the differences in knowledge, understanding, and preference concerning wine and landscape should be regarded more closely: the wine should be perceived as a representative of its region and one of the most characteristic features of a region is the landscape.