Impact of deficit irrigation strategies on terpene concentration in Gewürztraminer grapes

For the first time, it was established that the timing of inoculation with LAB could significantly impact the concentration of many secondary metabolites leading to significant aromatic changes. From studied compounds, the most influenced were esters and diacetyl.

Grapevine yield is a key indicator to assess the impacts of climate change and the relevance of adaptation strategies in a vineyard landscape. At this scale, a yield model should use a number of parameters and input data in relation to the information available and be able to reproduce vineyard management decisions (e.g. soil and canopy management, irrigation). In this study, we used data from six experimental sites in Southern France (cv. Syrah) to calibrate a model of grapevine yield limited by water constraint (GraY). Each yield component (bud fertility, number of berries per bunch, berry weight) was calculated as a function of the soil water availability simulated by the WaLIS water balance model at critical phenological phases. The model was then evaluated in 10 grapegrowers’ plots, covering a diversity of biophysical and technical contexts (soil type, canopy size, irrigation, cover crop). We identified three critical periods for yield formation: after flowering on the previous year for the number of bunches and berries, around pre-veraison and post-veraison of the same year for mean berry weight. Yields were simulated with a model efficiency (EF) of 0.62 (NRMSE = 0.28). Bud fertility and number of berries per bunch were more accurately simulated (EF = 0.90 and 0.77, NRMSE = 0.06 and 0.10, respectively) than berry weight (EF = -0.31, NRMSE = 0.17). Model efficiency on the on-farm plots reached 0.71 (NRMSE = 0.37) simulating yields from 1 to 8 kg/plant. The GraY model is an original model estimating grapevine yield evolution on the basis of water availability under future climatic conditions.  It allows to evaluate the effects of various adaptation levers such as planting density, cover crop management, fruit/leaf ratio, shading and irrigation, in various production contexts.

Results indicated that cross-flow microfiltration removed similarly to fining treatments the most astringent tannins, but cross-flow microfiltration also removed up to 14 % more colour. RP-HPLC and spectrophotometric results showed that egg albumin is a softer fining treatment compared to gelatine and cross-flow microfiltration.

In recent years, consumer awareness for consuming healthy and environmental sustainability products has considerably increased [1]. In an ever-changing and highly competitive environment such as the wine sector, production of wines without sulfites, or biodynamic, organic or vegan wines, has experienced an important increase to meet the new needs of consumers [2,3]. Beyond these categories of regulated products, a new concept has emerged: natural wines (NW), for which there is not an established definition or legal regulation. Rather, producers have a personal idea of naturalness under the premise of applying minimal intervention from grape to wine production [4]. In this context, it is hypothesized that self-defined natural wines are different from conventional wines (CW) in their sensory and chemical profile. The predicament of natural wine is based on anecdotic declarations and assumes that minimal intervention guarantees the production of wines with organoleptic properties able to express the “terroir” and thus promote wine diversity, plurality and sensory typicity against the risk of standardization of CW.

Vineyard site selection and determination of adapted grape varieties for a site are the most fundamental factors contributing to vineyard success, but can be challenging to ascertain