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

The cultivated area of table grapes worldwide has experienced a paramount increase over the last two decades. In this current scenario, traditional varieties are being replaced by new cultivars that prioritize a profitable and sustainable agriculture, while satisfying consumer demands. It is widely recognized that wine varieties, especially those with red berry flesh, are renowned for their high antioxidant capacity and phenolic compounds, which promote health. Recently, this topic has also gained significance in table grape breeding programs.

Context and purpose of the study. Climate changes pose the need to develop new grapevine varieties and rootstocks that are more tolerant to stress and diseases.

AIM: To investigate chemical and sensory drivers of regional typicity of Cabernet Sauvignon from different geographical regions of Australia.

Cultivar and rootstock selection are two well-known strategies for adapting vine production in challenging environments. Despite the vast diversity of rootstocks and cultivars, their effective contribution to grapevine sustainable development and acclimation to changing growing conditions remains an open question. The use of robust and prompt monitoring tools can allow a powerful screening of the water status of the vineyard before considering a further detailed characterization. This study leveraged new tools to monitor the stomatal conductance (gs), transpiration rate (E), and quantum efficiency of photosystem II (ᶲPSII) throughout a season, from pre-veraison to after-harvest.

Following anecdotal evidence of unwanted ‘tropical’ character in red wines resulting from vineyard interventions and a subsequent yeast trial observing higher ‘red fruit’ character correlated with higher thiol concentrations, the role of polyfunctional thiols in commercial Australian red wines was investigated.
First, trials into the known tropical thiol modulation technique of foliar applications of sulfur and urea were conducted in parallel on Chardonnay and Shiraz.1 The Chardonnay wines showed expected results with elevated concentrations of 3-sulfanylhexanol (3-SH) and 3-sulfanylhexyl acetate (3-SHA), whereas the Shiraz wines lacked 3-SHA. Furthermore, the Shiraz wines were described as ‘drain’ (known as ‘reductive’ aroma character) during sensory evaluation although they did not contain thiols traditionally associated with ‘reductive’ thiols (H2S, methanethiol etc.).