Macrowine 2021
IVES 9 IVES Conference Series 9 Macrowine 9 Macrowine 2021 9 Grapevine diversity and viticultural practices for sustainable grape growing 9 First characterization of thiol precursors in colombard and gros manseng: comparison of two cultivation practices

First characterization of thiol precursors in colombard and gros manseng: comparison of two cultivation practices

Abstract

AIM: Organic production of wine in the past years has known an important augmentation. This type of cultivation practice switches synthetic phytosanitary product for copper-based protection as fungicide. While the effect of copper on soil and vine is understood, few data are published concerning its impact on wine aromas (Darriet et al. 2001) and even less concerning varietal thiol. The aim of this work was to characterize the thiol aromatic potential of Colombard and Gros Manseng grapes and to investigate the effect of copper on thiol precursor biogenesis. We selected 30 parcels (15 conventional and 15 organic) with sampling at harvest for 18 of them and 3 sampling dates during ripening for the other 12 parcels. Chemical analyses of thiol precursors were performed by adapting an UPLC-MS/MS method based upon Stable Isotope Dilution Assay (Bonnaffoux et al. 2017)

RESULTS: With this first characterization, we demonstrated that both varieties presented concentrations of glutathionylated (G3SH) and cysteinylated (Cys3SH) precursors of 3-sulfanylhexan-1-ol up to 454 µg/kg and 21 µg/kg respectively. No precursors of the 4-sulfanyl-4-methylpentan-2-one were detected. So, Colombard and Gros Manseng were ranked in the top of varietal thiol producers with Sauvignon and Pinot Gris grapes (Pena-Gallego et al. 2012). By comparing the copper protected parcels to the others, we identified a significant decrease (p-value = 0.01) of G3SH content in organic Gros Manseng grapes which was around 30%. This could represent a loss in 3SH of 1000 ng/kg in finished wines if a conversion rate of 3% between G3SH and 3SH was considered. On the opposite, Colombard grapes remained unaffected by the copper spraying with no effect on the precursors content at harvest. We also analyzed the accumulation kinetics of thiol precursors under the two protection methods (copper or not). No accumulation of thiol precursors between seven days prior and after the harvest was observed in Colombard grapes which was inconsistent with literature on other grape varieties such as Sauvignon B. or Melon B. (Roland et al. 2010). Gros Manseng grapes showed significant accumulation for conventional culture (161 µg/kg to 356 µg/kg) over the two last weeks of ripening. Furthermore, copper treated parcels of Gros Manseng have no accumulation through the two-week study. However, Pearson test did not show a direct correlation between copper content and G3SH suggesting a possible interaction of copper with thiol precursors making them not analyzable under our conditions or a modification of vine metabolism.

CONCLUSION:

We characterized for the first time two grapes varieties (Colombard and Gros Manseng) that have high potential towards varietal thiols such as Sauvignon. We identified a negative copper effect on Gros Manseng variety for both precursors content at harvest and accumulation kinetics while Colombard remained unaffected.

DOI:

Publication date: September 2, 2021

Issue: Macrowine 2021

Type: Article

Authors

Gabriel Dournes, Arnaud VERBAERE, Frédéric LOPEZ, Thierry DUFOURCQ, Jean-Roch MOURET, Aurélie ROLAND

SPO, Univ Montpellier, INRAE, Institut Agro, Montpellier, France, IFV Sud-Ouest, Château de Mons, 32100 Caussens, France

Contact the author

Keywords

copper, thiol precursors, colombard, gros manseng, wine

Citation

Related articles…

Modeling island and coastal vineyards potential in the context of climate change

Climate change impacts regional and local climates, which in turn affects the world’s wine regions. In the short term, these modifications rises issues about maintaining quality and style of wine, and in a longer term about the suitability of grape varieties and the sustainability of traditional wine regions. Thus, adaptation to climate change represents a major challenge for viticulture. In this context, island and coastal vineyards could become coveted areas due to their specific climatic conditions. In regions subject to warming, the proximity of the sea can moderate extremes temperatures, which could be an advantage for wine. However, coastal and island areas are particular prized spaces and subject to multiple pressures that make the establishment or extension of viticulture complex.
In this perspective, it seems relevant to assess the potentialities of coastal and island areas for viticulture. This contribution will present a spatial optimization model that tends to characterize most suitable agroclimatic patterns in historical or emerging vineyards according to different scenarios. Thanks to an in-depth bibliography a global inventory of coastal and insular vineyards on a worldwide scale has been realized. Relevant criteria have been identified to describe the specificities of these vineyards. They are used as input data in the optimization process, which will optimize some objectives and spatial aspects. According to a predefined scenario, the objectives are set in three main categories associated with climatic characteristics, vineyards characteristics and management strategies. At the end of this optimization process, a series of maps presents the different spatial configurations that maximize the scenario objectives.

A blueprint for managing vine physiological balance at different spatial and temporal scales in Champagne

In Champagne, the vine adaptation to different climatic and technical changes during these last 20 years can be seen through physiological balance disruptions. These disruptions emphasize the general grapevine decline. Since the 2000s, among other nitrogen stress indicators, the must nitrogen has been decreasing. The combination of restricted mineral fertilizers and herbicide use, the growing variability of spring rainfall, the increasing thermal stress as well as the soil type heterogeneity are only a few underlying factors that trigger loss of physiological balance in the vineyards. It is important to weigh and quantify the impact of these factors on the vine. In order to do so, the Comité Champagne uses two key-tools: networking and modelization. The use of quantitative and harmonized ecophysiological indicators is necessary, especially in large spatial scales such as the Champagne appellation. A working group with different professional structures of Champagne has been launched by the Comité Champagne in order to create a common ecophysiology protocol and thus monitor the vine physiology, yearly, around 100 plots, with various cultural practices and types of soil. The use of crop modelling to follow the vine physiological balance within different pedoclimatic conditions enables to understand the present balance but also predict the possible disruptions to come in future climatic scenarios. The physiological references created each year through the working group, benefit the calibration of the STICS model used in Champagne. In return, the model delivers ecophysiology indicators, on a daily scale and can be used on very different types of soils. This study will present the bottom-up method used to give accurate information on the impacts of soil, climate and cultural practices on vine physiology.

Amino nitrogen content in grapes: the impact of crop limitation

As an essential element for grapevine development and yield, nitrogen is also involved in the winemaking process and largely affects wine composition. Grape must amino nitrogen deficiency affects the alcoholic fermentation kinetics and alters the development of wine aroma precursors. It is therefore essential to control and optimize nitrogen use efficiency by the plant to guarantee suitable grape nitrogen composition at harvest. Understanding the impact of environmental conditions and cultural practices on the plant nitrogen metabolism would allow us to better orientate our technical choices with the objective of quality and sustainability (less inputs, higher efficiency). This trial focuses on the impact of crop limitation – that is a common practice in European viticulture – on nitrogen distribution in the plant and particularly on grape nitrogen composition. A wide gradient of crop load was set up in a homogeneous plot of Chasselas (Vitis vinifera) in the experimental vineyard of Agroscope, Switzerland. Dry weight and nitrogen dynamics were monitored in the roots, trunk, canopy and grapes, during two consecutive years, using a 15N-labeling method. Grape amino nitrogen content was assessed in both years, at veraison and at harvest. The close relationship between fruits and roots in the maintenance of plant nitrogen balance was highlighted. Interestingly, grape nitrogen concentration remained unchanged regardless of crop load to the detriment of the growth and nitrogen content of the roots. Meanwhile, the size and the nitrogen concentration of the canopy were not affected. Leaf gas exchange rates were reduced in response to lower yield conditions, reducing carbon and nitrogen assimilation and increasing intrinsic water use efficiency. The must amino nitrogen profiles could be discriminated as a function of crop load. These findings demonstrate the impact of plant balance on grape nitrogen composition and contribute to the improvement of predictive models and sustainable cultural practices in perennial crops.

Biodiversity in the vineyard agroecosystem: exploring systemic approaches

Biodiversity conservation and restoration are essential for guarantee the provision of ecosystem services associated to vineyard agroecosystem such as climate regulation trough carbon sequestration and control of pests and diseases. Most of published research dealing with the complexity of the vineyard agroecosystems emphasizes the necessity of innovative approaches, including the integration of information at different temporal and spatial scales and development of systemic analysis based on modelling. A biodiversity survey was conducted in the Franciacorta wine-growing area (Lombardy, Italy), one of the most important Italian wine-growing regions for sparkling wine production, considering a portion of the territory of 112 ha. The area was divided into several Environmental Units (EUs), defined as a whole vineyard or portion of vineyard homogenous in terms of four agronomic characteristics: planting year, planting density, cultivar, and training system. In each EU a set of compartments was identified and characterised by specific variables. The compartments are meteorology, morphology (altitude, slope, aspect, row orientation, and solar irradiance), ecological infrastructures and management. The landscape surrounding EU was also characterised in terms of land-use in a buffer zone of 500 m. For each component a specific methodology was identified and applied. Different statistical approaches were used to evaluate the method to integrate the information related to different compartments within the EU and related to the buffer zone. These approaches were also preliminarily evaluated for their ability to describe the contribution of biodiversity and landscape components to ecosystem services. This methodological exploration provides useful indication for the development of a fully systemic approach to structural and functional biodiversity in vineyard agroecosystems, contributing to promote a multifunctional perspective for the all wine-growing sector.

Bioclimatic shifts and land use options for Viticulture in Portugal

Land use, plays a relevant role in the climatic system. It endows means for agriculture practices thus contributing to the food supply. Since climate and land are closely intertwined through multiple interface processes, climate change may lead to significant impacts in land use. In this study, 1-km observational gridded datasets are used to assess changes in the Köppen–Geiger and Worldwide Bioclimatic (WBCS)