Evaluation of mannoprotein formation by different yeast strains by enzymatic analysis of mannose and tribological estimation of astringency

In vineyards, management and the surrounding landscape can have different effects on spiders. In temperate regions management (organic vs. conventional) may have less strong effects than for other crops.

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Climate is one of the main drivers of spatial and temporal variability in grapevine physiology and therefore a key determinant of grape composition and final wine value. The world has warmed 1.1 °C since pre-industrial times, and the latest IPCC report indicates an additional 0.5 to 1.3 °C of warming by mid-century with continental locations warming at a greater rate than the oceans.

As viticulture faces challenges such as climate change or vineyard dieback, the choice of the variety and rootstock becomes more and more crucial. To study rootstock levers in the Bordeaux region, a parcel of Cabernet Sauvignon (CS) was planted with four rootstocks in 2014. Twenty repetitions of each of the following four rootstocks were set up: 101-14 MGt, Nemadex AB, 420A MGt and Gravesac. The number of bunches, yields and pruning weights of the vine shoots were measured individually on 240 vines from 2017 to 2021. Since 2020, nitrogen status assessed by assimilable nitrogen level, hydric status assessed by δ13C and berry maturity were measured on 80 samples taken from 20 repetitions of the four rootstocks. A lower yield was measured for CS grafted onto Nemadex AB due to the lower number of bunches and the lower weight of berries. The differences between the other three rootstocks are small, but CS grafted onto 420A MGt was the most productive. The CS grafted onto Nemadex AB had the lowest pruning weight while 101-14 MGt had the highest. In 2020, δ13C showed a more moderate water stress with 101-14 MGt and 420A MGt than with Nemadex AB. Surprisingly, the Gravesac was under more stress than the 101-14 MGt. The nitrogen status in the berries was better for Nemadex AB but this was perhaps due to the significantly lower weight of the berries.Rootstock 101-14 MGt attained the highest accumulation of sugars in the berries while 420A MGt allows to preserve higher acidity. The parcel is still young which may explain some of the results. These measures must therefore be continued over the next several years to fully assess the effects of these rootstocks on the development of the vines and the quality of the production under new climatic conditions.

Eugenol has been identified as a quality marker in armagnac white spirits. In particular, those produced from the Baco blanc variety, the only hybrid variety authorised in a French PDO, bred since 1898 from noah (vitis labrusca x v.riparia) and folle blanche (v. Vinifera). The varietal compound of Baco blanc, eugenol has many original properties.