Application of DEXI PM Vigne sustainability tool to the assessment of alternative vineyard protection strategies

Contamination problems arising from the use of pesticides in viticulture have raised concerns. One of the alternatives to reduce contamination is the use of elicitors, molecules capable of stimulating the natural defences of plants, promoting the production of phenolic compounds (PC) that offer protection against biotic and abiotic stress. Previous studies on Cabernet-Sauvignon seedlings demonstrated that foliar application of elicitors methyl jasmonate (MeJ) and benzothiadiazole (BTH) increased proteins and PC involved in grapevine defence mechanisms. However, no trials had been conducted on Monastrell seedlings, a major winegrape variety in Spain.

Rootstocks were the first sustainable and environmentally friendly strategy to cope with a major threat for Vitis vinifera cultivation. In addition to providing Phylloxera resistance, they play an important role in protecting against other soil-borne pests, such as nematodes, and in adapting V. vinifera to limiting abiotic conditions. Today viticulture has to adapt to ongoing climate change whilst simultaneously reducing its environmental impact. In this context, rootstocks are a central element in the development of agro-ecological practices that increase adaptive potential with low external inputs. Despite the apparent diversity of the Vitis genus, only few rootstock varieties are used worldwide and most of them have a very narrow genetic background. This means that there is considerable scope to breed new, improved rootstocks to adapt viticulture for the future.

Volatile organic compounds (VOCs) constitute a diverse group of secondary metabolites key for the communication of plants with other organisms and for their adaptation to environmental and biotic stresses. The emission of these compounds through leaves is also affected by the interaction of plants with symbiotic microorganisms, arbuscular mycorrhizal fungi (AMF) among them [1]. Our objective was to know the concentration and profile of VOCs emitted by the leaves of two grapevine varieties (Tempranillo, T, and Cabernet Sauvignon, CS, grafted onto R110 rootstocks), inoculated or not with a consortium of five AMF (Rhizophagus irregularis, Funneliformis mosseae, Septoglomus deserticola, Claroideoglomus claroideum and C. etunicatum).

The production of most red wines that are sold involves an alcoholic fermentation carried out by yeasts of the Saccharomyces genus, and a subsequent fermentation carried out by lactic bacteria of the Oenococus oeni species after the first one is fully completed. However, the traditional process can face complications, which can be more likely in grape juices with high levels of sugar and pH. Because of climate change, these situations are more frequent in the wine industry. The main hazards in those scenarios are halts or delays in the alcoholic fermentation or the growth of unwanted bacteria while the alcoholic fermentation is not done yet and the wine still has residual sugars.

SO2 play a major role in wine stability and evolution during its aging and storage. Winemaking without SO2 is a big challenge for the winemakers since the lack of SO2 affects directly the wine chemical evolution such as the aromas compounds as well as the phenolic compounds. During the red wine aging, phenolic compounds such as anthocyanin, responsible of the red wine colour, and tannins, responsible of the mouthfeel organoleptic properties of wine, evolved quickly from the winemaking process to aging [1]. A lot of new interaction and molecules occurred lead by oxygen[2] thus the lack of SO2 will induce wine properties changes. Nowadays, the phenolic composition of the wine without added SO2 have not been clearly reported.