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IVES 9 IVES Conference Series 9 Influence de la nutrition potassique sur le manque d’acidité des vins issus du cépage Negrette

Influence de la nutrition potassique sur le manque d’acidité des vins issus du cépage Negrette

Abstract

Une baisse préoccupante de l’acidité des vins est observée dans beaucoup de régions viticoles, comme le Bordelais (Merlot), la Bourgogne (Pinot Noir), les Côtes-du-Rhône (Grenache) ou la Rioja (Tempranillo). Ce manque d’acidité est particulièrement marqué dans le vignoble Midi-Pyrénéen des Côtes du Frontonnais (Tournier, 1993). Or, l’acidité d’un vin est un des principaux facteurs de sa qualité, en effet, une faible acidité combinée à une structure tannique insuffisante entraîne une oxydation rapide des vins et les fait vieillir prématurément. De multiples travaux font état de la liaison étroite entre la faible acidité d’un moût ou d’un vin grande richesse en potassium (Boulton, 1980 ; Delas et al., 1989 ; Falcetti et al., 1993 ; Champagnol, 1988; Soyer et Molot, 1993).

D’autre part, la teneur en potassium des moûts est corrélée à celle des feuilles (Mattick, 1972 ; Champagnol, 1990) et une corrélation a été mise en évidence entre cette dernière et la fertilisation potassique (Morris et al., 1983 ; Champagnol, 1988, 1990 ; Soyer et Molot, 1993 ; Jourdan, 1993). Cependant, ces liaisons sont discutées par d’autres auteurs comme Dundon et al. (1984), Conradie et Saayman (1989) ou Matthews et al. (1993).
Pour contribuer à résoudre ce problème, nous avons choisi comme matériel d’étude la Négrette, cépage principal des Côtes du Frontonnais et cépage donnant des vins particulièrement peu acides.

Une double expérimentation a été mise en place. La première a été effectuée en culture hors-sol, sous serre. Elle a pour but de déterminer, grâce à l’application de solutions nutritives ayant des équilibres potassium-calcium différents, les relations existant entre les teneurs en potassium du milieu nutritif et celles des feuilles et des moûts, ainsi que leurs répercussions sur l’acidité des vins. La seconde est une expérimentation en champ qui a pour objectif d’étudier les interactions précédentes in situ. Le suivi de l’état nutritionnel de la vigne a été réalisé selon un protocole mis au point par Garcia et al. (1984) et Doux et al. (1985). La sélection des parcelles a été effectuée en s’inspirant de la méthode mise au point par Morlat et Asselin (1992).

DOI:

Publication date: March 25, 2022

Type: Poster

Issue: Terroir 1996

Authors

M. GARCIA (1), C. DAVEREDE (1), P. GALLEGO (1), D. VIGNES (2), J.L. FAVAREL (3), F. DEDIEU (4)

(1) Institut National Polytechnique-ENSAT, 145 av de Muret 31076 Toulouse
(2) CESBIO, 18 av Edouard Belin 31055 Toulouse
(3) Institut Technique de la Vigne et du vin-Gaillac, 52 Place Jean Moulin 81300 Gaillac
(4) Faculté de pharmacie, Chemin des Maraîchers 31062 Toulouse Cédex

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IVES Conference Series | Terroir 1996

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