Hochschule Geisenheim University

Geisenheim, Germany

Hochschule Geisenheim University

Geisenheim, Germany
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Obermeier W.A.,University of Marburg | Lehnert L.W.,University of Marburg | Kammann C.I.,Hochschule Geisenheim University | Muller C.,Justus Liebig University | And 8 more authors.
Nature Climate Change | Year: 2017

The increase in atmospheric greenhouse gas concentrations from anthropogenic activities is the major driver of recent global climate change. The stimulation of plant photosynthesis due to rising atmospheric carbon dioxide concentrations ([CO 2 ]) is widely assumed to increase the net primary productivity (NPP) of C3 plants - the CO 2 fertilization effect (CFE). However, the magnitude and persistence of the CFE under future climates, including more frequent weather extremes, are controversial. Here we use data from 16 years of temperate grassland grown under â € free-air carbon dioxide enrichment' conditions to show that the CFE on above-ground biomass is strongest under local average environmental conditions. The observed CFE was reduced or disappeared under wetter, drier and/or hotter conditions when the forcing variable exceeded its intermediate regime. This is in contrast to predictions of an increased CO 2 fertilization effect under drier and warmer conditions. Such extreme weather conditions are projected to occur more intensely and frequently under future climate scenarios. Consequently, current biogeochemical models might overestimate the future NPP sink capacity of temperate C3 grasslands and hence underestimate future atmospheric [CO 2 ] increase. © 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.

Kalili K.M.,Stellenbosch University | Vestner J.,Stellenbosch University | Vestner J.,Hochschule Geisenheim University | Stander M.A.,Stellenbosch University | De Villiers A.,Stellenbosch University
Analytical Chemistry | Year: 2013

Despite the significant importance of tannins in viticulture and enology, relatively little is known about the detailed chemical composition of these molecules. This is due to challenges associated with the accurate analytical determination of the highly structurally diverse proanthocyanidins which comprise tannins. In this contribution, we address this limitation by demonstrating how online comprehensive two-dimensional liquid chromatography (LC × LC) coupled to high resolution mass spectrometry (HR-MS) can be exploited as a powerful analytical approach for the detailed characterization of grape seed tannins. Hydrophilic interaction chromatography (HILIC) and reversed-phase liquid chromatography (RP-LC) were employed in the two dimensions to provide complementary information in terms of separation according to hydrophilicity and hydrophobicity, respectively. Online coupling of HILIC × RP-LC with fluorescence detection and electrospray ionization MS delivered high resolution analysis in a practical analysis time, while allowing selective detection and facilitating compound identification. Time-of-flight (TOF) MS provided high acquisition rates and sensitivity coupled to accurate mass information, which allowed detection of procyanidins up to a degree of polymerization (DP) of 16 and a degree of galloylation up to 8 in a red grape seed extract. This analytical methodology promises to shed new light on these important grape constituents and potentially on their evolution during wine production. © 2013 American Chemical Society.

Linck H.,Hochschule Geisenheim University | Kruger E.,Hochschule Geisenheim University | Reineke A.,Hochschule Geisenheim University
PLoS ONE | Year: 2017

Rubus stunt is an economically important disease in the production of raspberries, blackberries, and loganberries. A fast, sensitive, and reliable diagnosis of phytoplasmas, the causal agent of the disease, is of prime importance to stop its spread by vegetative propagation and by insect vectors. Therefore, multiplex qPCR assays using TaqMan probes with different kinds of fluorophores in one reaction were developed, allowing the detection of phytoplasmas in general as well as a more specific detection of phytoplasmas belonging to group 16SrV and host DNA (either plant or insect). This assay now provides a practical tool for the screening of motherplants and monitoring the presence and distribution of phytoplasmas in Rubus plants of different geographic origins, cultivars, and cultivation systems, as well as in putative insect vectors like leafhoppers. © 2017 Linck et al.

Rudiger J.,Hochschule Geisenheim University | Hanf J.H.,Hochschule Geisenheim University
Berichte uber Landwirtschaft | Year: 2017

Winegrowing in the German-speaking area is mainly characterised by businesses with small-scale structures. This often results in a lack of competitiveness of winegrowing businesses doing direct marketing. Wine tourism, which German winegrowers have discovered by now, offers the chance to further diversify sales opportunities. The objective of the study is to further examine wine tourism as an instrument of direct sales in the wine sector in order to gain further information for the terminological classification and integration of the term "wine tourism" into the marketing structures of winegrowing businesses. The study reveals that the trend of increasing wine tourism-related activities both of vineyards and winegrowers' co-operatives is seen in direct relation with the acquisition of new consumers and that wine tourism is an instrument of direct sales. This is supported by the channelling of the different definitional approaches of wine tourism. Based on this, a further development of the terminological classification and presentation of the concept of wine tourism could be introduced into direct sales.

Tarasov A.,Hochschule Geisenheim University | Rauhut D.,Hochschule Geisenheim University | Jung R.,Hochschule Geisenheim University
Talanta | Year: 2017

Analytical methods of haloanisoles and halophenols quantification in cork matrix are summarized in the current review. Sample-preparation and sample-treatment techniques have been compared and discussed from the perspective of their efficiency, time- and extractant-optimization, easiness of performance. Primary interest of these analyses usually addresses to 2,4,6-trichloroanisole (TCA), which is a major wine contaminant among haloanisoles. Two concepts of TCA determination are described in the review: releasable TCA and total TCA analyses. Chromatographic, bioanalytical and sensorial methods were compared according to their application in the cork industry and in scientific investigations. Finally, it was shown that modern analytical techniques are able to provide required sensitivity, selectivity and repeatability for haloanisoles and halophenols determination. © 2017 Elsevier B.V.

Tramontini S.,Plant Health Unit PLH | Tramontini S.,University of Turin | Doring J.,Hochschule Geisenheim University | Vitali M.,University of Turin | And 3 more authors.
Functional Plant Biology | Year: 2014

Grapevine (Vitis vinifera L.) expresses different responses to water stress, depending not only on genotype, but also on the influence of vineyard growing conditions or seasonality. Our aim was to analyse the effects on drought response of two grapevine cultivars growing on two soils, one water draining (WD) containing sand 80% volume and the other water retaining (WR), with no sand. Under these two different water-holding capacities Syrah, displaying a near-anisohydric response to water stress, and Cabernet Sauvignon (on the contrary, near-isohydric) were submitted to water stress in a pot trial. Xylem embolism contributed to plant adaptation to soil water deprivation: in both cultivars during late phases of water stress, however, in Syrah, already at moderate early stress levels. By contrast, Syrah showed a less effective stomatal control of drought than Cabernet Sauvignon. The abscisic acid (ABA) influenced tightly the stomatal conductance of Cabernet Sauvignon on both pot soils. In the near-anisohydric variety Syrah an ABA-related stomatal closure was induced in WR soil to maintain high levels of water potential, showing that a soil-related hormonal root-to-shoot signal causing stomatal closure superimposes on the putatively variety-induced anisohydric response to water stress. © CSIRO 2014.

Galidevara S.,Andhra University | Reineke A.,Hochschule Geisenheim University | Koduru U.D.,Andhra University
Journal of Invertebrate Pathology | Year: 2016

The entomopathogenic fungus Beauveria bassiana (Bals.) Vuillemin is commercially available as a bio insecticide. The expression of three genes previously identified to have a role in pathogenicity in in vitro studies was validated in vivo in three lepidopteran insects infected with B. bassiana. Expression of all three genes was observed in all the tested insects starting from 48 or 72 h to 10 d post infection corroborating their role in pathogenicity. We suggest that it is essential to test the expression of putative pathogenicity genes both in vitro and in vivo to understand their role in different insect species. © 2016 Elsevier Inc.

Szolnoki G.,Hochschule Geisenheim University | Hoffmann D.,Forschungsanstalt Geisenheim University
International Journal of Wine Business Research | Year: 2014

Purpose: The purpose of this study is to test the segmentation based on the usage of sales channels and to compare the segments with each other in terms of socio-demographic and behavioural characteristics. Design/methodology/approach: This study was conducted using representative data collected in Germany through a face-to-face interview. 2,000 German consumers answered questions towards the usage of different sales channels when purchasing wine as well as socio-demographic and other behavioural questions. A hierarchical cluster analysis was run, to classify the respondents into segments. Findings: The results illustrate the usefulness of this kind of segmentation and show significant differences between the six consumer groups: discount-customers, food-retail-customers, supermarket-customers, cellar-door-customers, wine-store-customers and multichannel-customers. These segments differ in their socio-demographic as well as in their behavioural structure. Furthermore, the six segments could be split into two groups depending on their average purchase value: a basic group and a premium group. Practical implications: This segmentation provides an analysing tool for the German retailers, which is able to identify the loyal and potential consumers of the different sales channels. Originality/value: This segmentation was conducted using the purchase activity of German consumers in different sales channels. This segmentation approach has been never used to identify, describe and classify wine consumers. © Emerald Group Publishing Limited.

Schmidt D.,Hochschule Geisenheim University | Velten K.,Hochschule Geisenheim University
Food and Bioproducts Processing | Year: 2016

A detailed understanding of mixing and homogenization during food processing is essential for process control and optimization, but often hard to achieve on industrial scales. We used 3D CFD simulations to analyze bubble flow induced mixing of yeast nutrients in industrial scale wine fermentations for different vessel geometries. Employing boundary conditions resembling the common set-up of bubble column simulations, an Eulerian multiphase model was experimentally validated and then used to describe the gas–liquid flow. Mixing behavior was evaluated based on passive tracer distributions implied by three different dosage locations. Average homogenization times ranged between (71 ± 8) s and (100 ± 9) s for most active fermentations, with significant differences depending on tank geometry. Mixing times were approximately twice as long in early stages of fermentation. For the simulation scenarios investigated, CO2 bubble-induced flow during active fermentation is shown to effectively prevent unwanted nutrient inhomogeneities. © 2016 Institution of Chemical Engineers

Friedel M.,Hochschule Geisenheim University | Patz C.-D.,Hochschule Geisenheim University | Dietrich H.,Hochschule Geisenheim University
Food Chemistry | Year: 2013

For more than a decade, Fourier-transform infrared (FTIR) spectroscopy combined with partial least squares (PLS) regression has been used as a fast and reliable method for simultaneous estimation of multiple parameters in wine. In this study, different FTIR instruments (single bounce attenuated total reflection, transmission with variable and defined pathlength) and different variable selection techniques (full spectrum PLS, genetic algorithm PLS, interval PLS, principal variable PLS) were compared on an identical sample set of international wines and ten wine parameters. Results suggest that the single bounce attenuated total reflection technique is well suited for the analysis of ethanol, relative density and sugars, but less accurate in the analysis of organic acid content. The transmission instrument with variable pathlength shows good validation results for the analysis of organic acids, but less accurate results for the analysis of ethanol and relative density as compared to the other instruments. The transmission instrument with defined pathlength was well suited for the analysis for all parameters investigated in this study. Variable selection improved model robustness and calibration results, with genetic algorithm PLS being the most effective technique. © 2013 Elsevier Ltd. All rights reserved.

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