Contribution of Electrical Resistivity Tomography (ERT) measurements for characterizing hydrological behaviour of an experimental plot in relation to pedo-geological factors (AOC Gaillac, SW France)

Climate change has varied effects across French vineyards, with marked regional differences in temperature shifts. Fine-scale studies highlight significant local climate variability, emphasizing the need for precise regional characterization to adapt vineyard management at the regional scale.

Phenolic compounds are very importants in crop plants, which is why there have been the subject of a large number of studies

Global warming is accelerating grape ripening, leading to unbalanced wines from fruit with high sugar content but poor aroma and colour development. Reducing the size of the photosynthetic apparatus after veraison has been shown to delay technological ripeness in cool climates, but methods have not been tested in areas with high irradiance and temperature where fruit exposure could have disastrous effects on berry composition. In this Cabernet-Sauvignon trial, we compared the application of an antitranspirant (pinolene), to severe canopy topping and above bunch zone leaf removal, all performed at mid-ripening, with an untouched control. We monitored the vines weekly by measuring stem water potential, gas exchange, fruit zone light exposure. We sampled berries to measure berry weight, total soluble solids, pH, titratable acidity, and the anthocyanin profile. At harvest, we assessed yield components, measured carbon isotope discrimination, rated sunburn on clusters, and produced experimental wines. We submitted harvest samples to metabolomic profiling through PFP-Q Exactive MS/MS and wines to sensory analysis. Application of the antitranspirant significantly reduced stomatal conductance and assimilation rate but did not affect the stem water potential. Inversely, leaf removal and topping increased water potential but did not affect leaf gas exchange. The late topping was the only treatment able to decrease sugar content (up to 2Bx), increase titratable acidity and pH, and improve anthocyanin content because of lower degradation of di-hydroxylated forms. Late leaf removal above the bunch zone increased lightning conditions in the canopy and produced the most significant damage on fruits. Yield components were not affected. This work suggests that late-season canopy management can effectively control ripening speeds and improve grapes and wines. Still, the effect on grape exposure in a critical time must be well balanced to avoid problems with the appropriate technique.

Les préoccupations actuelles autour des paysages viticoles vont au-delà des clichés promotionnels développés par les stratégies marketing. En effet, les paysages sont aujourd’hui au cœur d’une demande sociale croissante qui se traduit par différentes lois (la loi paysage de 1993, le paysage reconnu comme patrimoine commun de la nation par la loi n°95-101, la création du Conseil national du paysage par arrêté du 8/12/2000).

Some wood substances such as ellagitannins (vescalagin, castalagin, grandinin, roburins (A, B, C, D, E)…) can be extracted during wine ageing in oak barrels. The level of these hydrolysable tannins in wine depends of the species and origin of oak wood as well as its treatment during barrel realization.