Service crop effects on grapevine water and nitrogen status and yield under Mediterranean climate

Entre 1988 et 1995, dans la région Emilia-Romagna, deux zonages viticoles ont été complétés en zones assez differentes, soit géographiquement, soit par les conditions pedo-climatiques, soit par l’encépagement.

Gum arabic is composed of a polysaccharide rich in galactose and arabinose along with a small protein fraction [1, 2], which gives its stabilizing power with respect to the coloring substances or tartaric precipitation of bottled wine. It is a gummy exudation from Acacia trees; the products used in enology have two possible botanical origins, i.e. Acacia seyal and Acacia senegal, with different chemical-physical features and consequently different technological effects on wines. The aim of this work is to evaluate the feasibility of discrimination of commercial gums Arabic between their two different sources, on the basis of the absorption of the Fourier Transform Infrared (FT-IR) spectra of their aqueous solutions, in order to propose an extremely rapid and cost-saving method for quality control laboratories.

Cabernet Sauvignon is the top red wine cultivar in CA, however, the hot climate in Fresno is not ideal for Cabernet Sauvignon, particularly for berry color development. Fruit-zone leaf removal and irrigation were studied previously to have the significant effect on grape yield performance and berry quality. But the timing of leaf removal and the timing of irrigation are still inconclusive. Also, mechanical fruit-zone leaf removal is relatively new in CA. Our study aims to identify the interactive effect of mechanical fruit-zone leaf removal and irrigation on Cabernet Sauvignon’s yield performance and fruit quality and find the ideal timing of leaf removal and irrigation to maximize the berry color while maintaining the sustainable yield level.

This study explored the responses of Chardonnay and Sauvignon blanc grapevine cultivars to water deficit across four years, uncovering their shared patterns and distinctive coping mechanisms. The research was conducted in a commercial vineyard located in Isla de Maipo, Chile. Various characterization approaches were employed including plant water potentials (), gas exchange measurements, shoot vulnerability curves, productivity assessments, and leaf cell water relations. Linear mixed models and sensitivity analyses were performed using various statistical methods to evaluate cultivar responses to water deficit. As the water deficit progressed, both cultivars displayed a parallel reduction in stomatal conductance, leaf turgor, and increased shoot embolism.

Tannins are a heterogenous class of polymeric phenolics found in grapes, oak barrels and wine. In red wine tannins are primarily responsible for astringency, though they also have an important role in reacting with and stabilizing pigments. There are numerous sub-classes of tannins found in wine but they all share structural heterogeneity within each sub-class, with varied polymer composition, configuration and length.

Numerous methodologies exist for the quantification of tannins, however, protein precipitation using bovine serum albumin has proved itself useful due to its strong correlation to the sensory perception of astringency and the basic instruments required for the method. Though the method can yield valuable insights into tannin composition, it cannot be automated easily and necessitates well-trained personnel.