Macrowine 2021
IVES 9 IVES Conference Series 9 An excessive leaf-fruit ratio reduces the yeast assimilable nitrogen in the must

An excessive leaf-fruit ratio reduces the yeast assimilable nitrogen in the must

Abstract

Yeast assimilable nitrogen (YAN) in the grape must is a key variable for wine quality as a source of aroma precursors. In a situation of YAN deficiency, a foliar urea application upon the vine at veraison enhances YAN concentration and facilitates must fermentation. In 2013, Agroscope investigated the impact of leaf-fruit ratio on the nitrogen (N) assimilation and partitioning in grapevine Vitis vinifera cv. Chasselas following foliar-urea application with the aim of improving its efficiency on the YAN concentration. Two factors, canopy height with two levels (90 and 140 cm), and crop load with two levels (§§5 and 10 clusters per vine), were combined in a split plot trial (5 vines per treatment). All treatments received 20 kg/ha of 15N-labelled foliar urea (10 atom% 15N) at veraison. An extra 5-vine control treatment (150-cm canopy and 5 bunches per vine) received no foliar urea. As a result, the leaf-fruit ratio had a strong impact on the grape maturity at harvest and on the labelled-N partitioning after urea application. The YAN varied from 143 ± 17 mg/L when the leaf-fruit ratio was 1.6 m2/kg (light-exposed leaf area / fruit quantity), up to 230 ± 25 mg/L when the leaf-fruit ratio was 0.4 m2/kg. The grapes were the strongest sink of all the vine organs, with more than 20 % of their total organic N originating from the urea treatment. Whereas a too small leaf-fruit ratio affected the grape maturity and the accumulation of labelled N in the reserve organs, a large canopy induced a diminution of the total N concentration (% dry weight) in all organs comparable to a “dilution” in the plant. Thus a balanced leaf-fruit ratio – between 1 and 1.5 m2/kg – should be maintained in order to guarantee the grape maturity, the accumulation of YAN in the must and the storage of N in the reserve organs. This study fosters further research at the isotopic molecular level to unravel other mechanisms controlling the source-sink relationship and the specific N partitioning between grapevine organs.

Publication date: April 4, 2024

Issue: Macrowine 2016

Type: Poster

Authors

Thibaut Verdenal* 

*Agroscope

Contact the author

Tags

IVES Conference Series | Macrowine | Macrowine 2016

Citation

Related articles…

Sensory definition of green aroma concept in red French wines. Evidence for the contribution of novel volatile markers

The aromatic complexity of a wine results from the perception of the association of volatile molecules and each aroma can be categorized into different families. The “green” aromas family in red wines has retained our attention by its close link with the fruity perception. In that study, the “green” olfactory concept of red wines was considered through a strategy combining both sensory analysis and hyphenated chromatographic techniques including HPLC and MDGC (Multidimensional Gas Chromatography). The aromatic space of this concept was specified by lexical generation through a free association task on 22 selected wines by a panel of wine experts. Then, 70 French red wines were scored on the basis of the intensity of their “green” and “fruity” attributes.

Development of a new sustainable filtering media for wine and beer clarification and sterilisation

Different separation techniques are frequently used during vinification process. Nowadays, clarification and microbiological stabilization of wine or beer can be done using precoat filters or crossflow filters to remove yeast and bacteria. Kieselguhr powders are the most used filter aids for precoat filtration. Their crystalline structure and their pulverulent nature induce ecotoxicological risks when used. Moreover, regeneration and reuse of these filter aids is not efficient and the filtration waste requires cost effective retreatment.

The influence of soil management practices on functional traits and biodiversity of weed communities in Swiss vineyards

Green cover in vine rows provides many ecological services, but can also negatively impact the crop, depending on the weed species. The composition of a vineyard weed community is influenced by many parameters. Ensuring an evolution of the vine row flora into a desired direction is therefore very complex. A key step towards this goal is to know which factors influence the establishment of the weed community and which types of communities are best suited for vineyards. In this study, we analysed the weed communities of several vineyards in the Lake Geneva region (379 botanical surveys on 117 plots), with the aim to highlight the links between soil management practices (chemical and mechanical weeding, mowing, mulching roll) and phytosociological profiles, biodiversity and selected functional traits (growth forms, life strategies, root depth). T

How do different oak treatment affect the sensory composition of Chenin blanc wines over time?

Wooden barrels have been the preferred method for oak maturation for wines, but the use of alternative oak products, such as staves and oak chips have increased in South Africa due to lower production costs. This study investigated the effect of different oak products used during fermentation and ageing on the sensory profile, degree of liking and perceived quality of a South African Chenin blanc wine. The different wine treatments included an unoaked tank control wine, wines matured in 5th fill barrels, wines matured in new barrels from three different cooperages, and wines matured in 5th fill barrels with stave inserts from two different cooperages.

On the losses of dissolved CO2 from laser-etched champagne glasses under standard tasting conditions

Under standard champagne tasting conditions, the complex interplay between the level of dissolved CO2 found in champagne, its temperature, the glass shape, and the bubbling rate, definitely impacts champagne tasting by modifying the neuro-physico-chemical mechanisms responsible for aroma release and flavor perception. Based on theoretical principles combining heterogeneous bubble nucleation, ascending bubble dynamics and mass transfer equations, a global model is proposed (depending on various parameters of both the wine and the glass itself), which quantitatively provides the progressive losses of dissolved CO2 from laser-etched champagne glasses.