Aspects concernant les relations entre quelques composantes de la biomasse viticole, en fonction de l’offre des ressources écologiques

A study of the physiological and agronomical behaviour of the vine (cv. Chasselas) was conducted between 2001 and 2003 by the Swiss Federal Research Station for Plant Production at Changins (Agroscope RAC Changins) on various wine-growing farms (terroirs) in the Canton of Vaud (Switzerland), as part of a study project on Vaudois

Excell laboratory has initiated the development of an analytical method based on electrochemistry to evaluate the ability of wines to undergo or resist to oxidative phenomena. Electrochemistry is a powerful tool to probe reactions involving electron transfers and offers possibility of real-time measurements. In that context, the laboratory has implemented electrochemical analysis to assess oxidation state of different wine matrices but also in order to evaluate oxidative or reduced character of leaf and soil. Initially, our laboratory focused on dosage of compounds involved in responses of plant stresses and we were also interested in microbiological activity of soils. These analyses were compared with the measurement of redox potential (Eh) and pH which are two fundamental variables involved in the modulation of plant metabolism. Indeed, the variation of redox states of the plant reflects its biological activity but also its capacity to absorb nutriments. The Eh-pH conditions mainly determine metabolic processes involved in soil and leaf and our goal is to determine if this combined analytical approach will be sufficiently precise to detect biological evolutions (plant health, parasitic attack…).

A soil management and vine irrigation trial was carried out for 4 consecutive years from 2020 to 2023 at agroscope’s experimental vineyard in leytron (Valais, Switzerland) with the Chasselas grape variety (clone 14-33/4, grafted on 5bb). Two types of soil maintenance (bare soil with chemical weeding and sown grass) coupled with two water regimes (with and without drip irrigation from flowering to veraison) were compared in a randomized design with four replicates of 10 vines each.

Volatile phenols namely 4-ethylphenol and 4-ethylguaiacol are formed by enzymatic decarboxylation of hydroxycinnamic acids by Brettanomyces yeasts to give vinylphenols and subsequent reduction of the vinyl group to form the correspondent ethylphenols. The presence of these compounds in wine affects negatively its aromatic quality, conferring unpleasant animal and phenolic odor when present in quantities above the olfactory detection threshold [1]. Several methods have been described to remove these undesirable compounds from wines, including the use laccase enzymes [2, 3]. Due to this, the aim of this work was to evaluate the effect of several natural redox mediators on the activity of Botrytis cinerea laccase against these volatile phenols.

Resilience and sustainability are two fundamental concepts in the sustainable development of the wine sector, being closely interconnected.