Vine nitrogen status and the terroir effect: a study on cv. Doral in the Vaud vineyard (Switzerland)

[English version below]

On a étudié durant deux saisons de croissance (2002/2003 et 2003/2004) l’effet de l’orientation vertical des rameaux sur les paramètres physiologiques, végétatifs et reproductifs dans la région de Stellenbosch dans un vignoble du cépage Merlot sur 99 R conduite à espalier et taillé a cordon coursonné. Les vignes étaient espacées 2.7 x 1.5 m. L’irrigation a été appliquée quand la baie avait la dimension d’un pois et a la véraison.

In the next years the territorial environmental certification could become realistic if the following conditions will be fully satisfied:
– the enhancement of the environmental awareness among the industries, the public administration, the authorization bodies, the living people of that territory as well as the tourists and visitors.

Grapevines are cultivated on 6 out of 7 continents, roughly between latitudes 4° and 56° in the Northern Hemisphere and between 6° and 42° in the Southern Hemisphere across a large diversity of climates (oceanic, warm oceanic, transition temperate, continental, cold continental, Mediterranean, subtropical, attenuated tropical, and arid climates).

Oxygen management in wine is one of the most significant challenging issues for winemakers.

Several classes of flavonoids, such as anthocyanins, flavonols, flavanols and flavones, undergo a slow H/D exchange on aromatic ring A, leading to full deuteration at positions C(6) and C(8). Within the flavanol class, H-C(6) and H-C(8) of catechin and epicatechin are slowly exchanged in D2O to the corresponding deuterated analogues; even quercetin, a relevant flavonol representative, shows the same behaviour in a D2O/DMSOd6 1:1 solution. Detailed kinetic measurements of these H/D scrambling processes are here reported by exploiting the time-dependent changes of their peak areas in the 1H-NMR spectra taken at different temperatures. A unifying reaction mechanism is also proposed based on our detailed kinetic observations, even taking into account pH and solvent effects. Molecular modelling and QM calculations were also carried out to shed more light on several molecular details of the proposed mechanism.