Proceedings of International Terroir Congress 1996

The influence of climatic conditions on the development of the vine and on the quality of the wines no longer needs to be demonstrated at the scale of the vineyard, by the regional climatic characteristics, determining on this scale the viticultural potentialities (Huglin, 1978; Branas, 1946; Riou et al ., 1994); but also on a local scale, at the level of the basic terroir unit (Morlat, 1989), by the landscape differentiation of the natural environment inducing climatic variability within the same vineyard, and partly explaining differences in functioning of the vine, in connection with the processes of maturation and the quality of the wine (Becker, 1977 and 1984; Morlat, 1989 and Lebon, 1993a). According to these authors, the climatic diversity in a wine region constitutes in addition to the edaphic component, an important component of characterization of the Basic Terroir Units (UTB).

On peut être surpris de l’existence d’un vignoble de vins liquoreux, le vignoble des Coteaux du Layon, dans une zone septentrionale à la limite Nord de la culture de qualité de la vigne et ce d’autant plus que le cépage de ce vignoble, le Chenin ou Pineau de la Loire, est un cépage semi tardif. La première explication est à rechercher au niveau des facteurs naturels (données climatiques et géopédologiques) permettant la réalisation de ce type de produit. Il est nécessaire de souligner ici l’importance de chaque paramètre du terroir pris dans im sens large (géopédologique et climatique) et que toute variation de l’un d’entre eux, même non perceptible en première analyse à l’homme, peut avoir des incidences déterminantes sur la qualité des vins.

Natural factors such as the environment in which the vine is grown play an important role in the quality of the wine. If you want to produce a good wine, it is indeed essential to produce quality grapes. To do this, we must enhance and optimize the terroir effect which, for the moment, plays a role that is not very well known. It is therefore essential, for example, to have scientifically established and well quantifiable relationships in order to have the system of areas of controlled origin accepted. R. Morlat (1989) and G. Seguin (1970) have already carried out studies on the role of certain soil factors on grape quality. In particular, they showed the importance of soil temperature and water content.

The viticulture of the Douro Delimited Region, one of the heirs of ancestral viticulture, traditionally empirical and of quality, while integrating modernity and contemporary tools, respects and has always present the principles on which it was developed.

The research carried out by the URVV of the INRA center in Angers aims to develop a methodology for the integrated characterization of the natural factors of viticultural terroirs, representative of the operating conditions of the vine and the sensory differences of the wines. In this context, the concept of Basic Terroir Unit (UTB) has been developed. The UTB represents a viticultural surface of variable geographical extension, defined as the association in a given place of a geological, pedological and landscape component, Morlat (1989), Riou et al. (1995).

The northern vineyards produce wines with a high aromatic richness. The wines of Alsace are appreciated for the diversity of their aromas, the typicality of which was for a long time judged mainly according to the grape variety of origin. Alsatian winegrowers have however widely sensed the importance of the environment of the vine on the quality of the wines. Efforts are made to try to harmonize in a reasoned way the interaction between the natural environment and the plant material with a view to developing the character of the grape variety through the fine expression of the terroir and making the quality and typicality even more inimitable. wines produced in Alsace.

The qualitative and quantitative distribution of the phenolic compounds in red wines depends on cultivars features, on grapes maturation state, on grapes processing technology including must obtention, as well as on maceration-fermentation method (Margheri, 1981). The last two factors are responsible for the different phenolic composition of the wines produced from the same cultivar.

The Appellation d'Origine Contrôlée of Bandol covers an area of ​​1365 ha, 83% of which are planted with vines, the annual production being around 40,000 hl. Among the wines produced, there are mainly reds which assert themselves over time, but also rosés characterized by their pale colour, generally orange; the whites represent a small part of the production. The main grape variety of this AOC is Mouvèdre, of Spanish origin, which is also found in Provence and Languedoc.

A set of Syrah plots covering a wide range of terroirs distributed in the vineyards of the Rhone Valley and the Mediterranean South is examined through their oenological and sensory characteristics. The multidimensional analysis of data leads to the following groupings: (1) A group of unstructured wines with a simple aromatic profile dominated by fruity-floral notes; they come from plots where the ripening conditions have been disturbed by unfavorable climatic conditions, or an excess harvest.

Dans le vignoble languedocien, les potentialités qualitatives des terroirs dépendent surtout de leurs caractéristiques édaphiques : la fertilité agronomique d’une part et sa nature géopédologique d’autre part.

L’utilisation de levures sélectionnées est généralement considérée comme le moyen d’éviter les problèmes fermentaires. Néanmoins de nombreux viticulteurs pensent que ces levures sont à l’origine d’une standardisation des vins et militent pour le respect d’une flore indigène (Bourguignon, 1992).

Le manque de connaissances concernant la physiologie de la maturation du raisin a longtemps interdit d’interpréter l’effet du terroir ou du millésime sur la qualité des vendanges en termes moléculaires. L’hypothèse selon laquelle c’est la perméabilité membranaire qui contrôlerait le sens comme l’intensité du stockage des acides est pourtant déjà ancienne (1). L’étude du transport des acides organiques et de son coût énergétique permet d’avancer certaines hypothèses concemant les sites potentiels de la régulation du contenu en sucres et acides du raisin sous l’effet de paramètres environnementaux.

During the 1985 harvest, I was able to notice in the taste perception a break in the harmony of the wine during even partial blends of grapes from different plots. At the same time, I noted a good reaction from customers for greater product customization. As a result, I was led to seek the objective limits of the terroir of a cuvée and by a constant and permanent refinement of the parameters specific to each of the terroirs.

The French viticultural appellation areas are the result of an empirical, historical and evolutionary selection which, generally, has consecrated a match between natural factors, grape varieties and viti-vinicultural practices. The notion of terroir is the main basis of the Appellation d'Origine Contrôlée in viticulture. It is based on the one hand on privileged natural factors and on the other hand on the know-how of the winegrowers; the whole allowing the production of a wine endowed with an authenticity and a sensory typicity. Wine-growing practices evolve according to progress in viticulture and oenology, while the natural factors of the terroir are much more stable, with the exception of the vintage. They therefore represent a fundamental pillar of the identity of an appellation vineyard.

In the Champagne vineyards, spring frosts are the cause of significant variations in the volume of the harvest which are very penalizing for the trade. This variability is reflected both in time (years without frost alternating with years with severe frosts) and in space. Certain sectors of the vineyard are in fact statistically more susceptible to frost than others, but each year no municipality can consider itself immune to this climatic accident. The objective of the study is precisely to analyze the spatial distribution of frost and to determine its main mechanisms, linked to the topography of the hillsides, their orientation but also to regional meteorological variables.