Preliminary results on the effect of different organic mulching on wine polyphenol content

The sustainability of vineyards is a major issue. The choices proposed to date have major flaws such as the lack of scientific bases or the use of dangerous products such as copper. GiESCO has published a charter of best practices for the environment and for people adapted to various environments. The use of sustainably resistant grape varieties that produce quality wines plays a central role here. Often innovative cultivation systems associated with new technologies and based on scientific bases, guarantee respect for people and the environment. These proposals are brought together in a charter which is part of a meta-ethical approach to seeking consensual measures to ensure the sustainability of vineyards.

Grape breeding for resistance to fungal diseases is today very dynamic throughout the world notably in France. New varieties are obtained by hybridization between susceptible varieties of the vitis vinifera species and resistant genotypes, with breeding programs generally lasting between 15 and 25 years and resulting in the registration of a few new varieties. Though these varieties can provide several benefits and can be planted by winegrowers, they are not always systematically adopted.

Nutrient availability – nitrogen, lipids, vitamins or oxygen – has a major impact on the kinetics of winemaking fermentations. Nitrogen is usually the growth-limiting nutrient and its availability determines the fermentation rate, and therefore the fermentation duration. In some cases, in particular in Champagne, grape musts have high nitrogen concentrations and are sometimes clarified with turbidity below 50 NTU. In these conditions, lipid deficiencies may occur and longer fermentations can be observed. To better understand this situation, a study was realized using a synthetic medium simulating the composition of a Champagne must : 180 g/L of sugar, 360 mg/L of assimilable nitrogen and a lipid content ranging from 1 to 8 mg/L of phytosterols (mainly β-sitosterol).

Vine water status was measured on 96 plots of three vines inside a vineyard block of 0.28 ha during three years: 2003, 2004 and 2005. Three physiological indicators were implemented: stem water potential, carbon isotope discrimination measured on grape sugars at ripeness (δ13C) and canopy temperature measured by high resolution remote sensing. For stem water potential, measurements were taken on every single vine of each plot.

Global warming and increased frequency and/or severity of drought events are among the most threatening consequences of climate change for agricultural crops. In response to drought, grapevine (as many other plants) exhibits osmotic adjustment through active accumulation of osmolytes which in turn shift the leaf turgor loss point (TLP) to more negative values, allowing to maintain stomata opened at lower water potentials1. We investigated the capacity of Pinot noir leaves to modulate their osmotic potential as a function of: (i) time (seasonal osmoregulation), (ii) growing temperatures, and (iii) drought events, to enhance comprehension of the resilience of grapevines in drought conditions. We performed trails under semi-controlled field conditions, and in two different greenhouse chambers (20/15 °C vs 25/20 °C day/night). For two consecutive vegetative seasons, grafted potted grapevines (Pinot noir/SO4) were subjected to two different water regimes for at least 30 days: well-watered (WW) and water deficit (WD).