The terroir of Carnuntum: investigation of the physiogeographic characteristics and interdisciplinary study of viticultural functions of the Carnuntum wine district, Austria

Water and nutrient availability significantly impact crop yield, thus the application of sustainable strategies towards efficient water use and nutrient absorption by plants is needed.

The spine grapes (Vitis davidii Foëx.) are wild grape species that grow in southern China, and can be used for table grapes, juicing and winemaking. To systematically investigate the flavor profiles of spine grapes, flavonoids and volatile compounds were detected in five spine grape varieties (Seputao, Ziqiu, Miputao, Tianputao and Baiputao) using HPLC-QqQ-MS/MS and GC-MS. The content of these compounds highly depended on the variety, such as the total concentrations of anthocyanins (91.43-328.85 mg/kg FW) and free norisprenoids (2.60 to 11.46 μg/kg FW).

In response to changes in their environment, grapevines regulate transpiration using various physiological mechanisms that alter conductance of water through the soil-plant-atmosphere continuum. Expressed as bulk stomatal conductance at the canopy scale, it varies diurnally in response to changes in vapor pressure deficit and net radiation, and over the season to changes in soil water deficits and hydraulic conductivity of both soil and plant. It is necessary to characterize the response of conductance to these variables to better model how vine transpiration also responds to these variables. Furthermore, to be relevant for vineyard-scale modeling, conductance is best characterized using data collected in a vineyard setting. Applying a crop canopy energy flux model developed by Shuttleworth and Wallace, bulk stomatal conductance was estimated using measurements of individual vine sap flow, temperature and humidity within the vine canopy, and estimates of net radiation absorbed by the vine canopy. These measurements were taken on several vines in a non-irrigated vineyard in Bordeaux France, using equipment that did not interfere with ongoing vineyard operations. An inverted Penman-Monteith equation was then used to calculate bulk stomatal conductance on 15-minute intervals from July to mid-September 2020. Time-series plots show significant diurnal variation and seasonal decreases in conductance, with overall values similar to those in the literature. Global sensitivity analysis using non-parametric regression found transpiration flux and vapor pressure deficit to be the most important input variables to the calculation of bulk stomatal conductance, with absorbed net radiation and bulk boundary layer conductance being much less important. Conversely, bulk stomatal conductance was one of the most important inputs when calculating vine transpiration, further emphasizing the need for characterizing its response to environmental changes for use in vineyard water use modeling.

Vineyards harbor a myriad of microorganisms that interact with each other and with the grapevines. Some microorganisms are plant pathogens, such as the oomycete Plasmopara viticola that causes grapevine downy mildew. Others, such as plant growth promoting bacteria and disease biocontrol agents, have a positive influence on vine health. The present study aims to (1) investigate whether vine-based culture media increase the cultivability of the grapevine microbiota, in comparison to standard culture media and (2) identify and isolate bacterial taxa naturally present in grapevine leaves and significantly more abundant in plots showing low susceptibility to downy mildew.

Melatonin is a bioactive compound with antioxidant properties, that has been found in many fermented beverages, such as beer and wine [1]. Indeed, it has been shown that yeast can synthesize melatonin during alcoholic fermentation, although its role inside the cell, as well as the metabolic pathway involved in its synthesis, is still unclear [1]. Recent studies showed that during fermentation, melatonin interacts with different proteins of the glycolytic pathway in both Saccharomyces and non-Saccharomyces yeast, for instance glyceraldehyde 3-phosphate dehydrogenase, pyruvate kinase or enolase [2].