Geisenheim University

Geisenheim, Germany

Geisenheim University

Geisenheim, Germany
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Zinkernagela J.,Geisenheim University | Kahlen K.,Geisenheim University
Acta Horticulturae | Year: 2017

Irrigation plays a major role in the production of herbaceous crops, since they are highly sensitive to water shortage. Methods for irrigation scheduling using indirect measures of plant water demand (e.g., soil matric potential) result in wellknown disadvantages (e.g., imprecise since not based on the actual plant demand, high leachate risk in sandy soils), whereas irrigation scheduling using direct measures of plant water demand (e.g., predawn leaf water potential (ψPD)) might be more promising. Therefore, we aimed at developing a ψPD-based irrigation scheduling for asparagus as a model crop. First, we investigated the plants' responses to water stress and, second, identified stress thresholds related to ψPD. In a field trial in Geisenheim, Germany, 'Gijnlim' asparagus was grown in irrigated and non-irrigated plots (3 replications, randomized block design). Irrigated plots were watered, if soil tension was below -20 kPa. Parameters of gas exchange, plant growth, spear yield and osmotic adjustment (OA) were analysed with respect to the applied water amount and ψPD. As expected, lack of irrigation reduced shoot growth, yield and ψPD. Parameters of OA, turgor loss point, osmotic potential and modulus of elasticity, did not change. Thus, OA did not occur. However, stomatal conductivity and assimilation rate were significantly reduced for ψPD below -0.15 MPa, when ψPD-classes ranging from -0.10 to -0.15, -0.15 to -0.20 and <-0.2 MPa, respectively, were compared. This implies that ψPDthresholds of herbaceous species lie far above of those of woody species already used in practice. Thus, herbaceous crops may challenge the irrigation management using ψPD as irrigation signal.

Belaya V.,Thunen Institute | Hanf J.H.,Geisenheim University
Agricultural and Food Economics | Year: 2016

The importance of power is underlined by many scientists who view it as a key behavioral construct. Power distinguishes itself as an effective tool in coordinating and promoting harmonious relationships, solving conflicts, and enhancing performance. An important challenge is to determine what role power plays in managing business-to-business relationships with specific attention to coordination and cooperation. The aim of our work is to investigate the role of power in business-to-business relationships to work out a strategy that enables managers to select an effective mix of power mechanisms. We work out and test a theoretical model of the effects of power on cooperation and coordination in business-to-business relationships and discuss possible managerial implications. To verify our research hypotheses, we conduct expert interviews via telephone about relationships of international food processing companies with their suppliers in Russia. © 2016, The Author(s).

Schultz H.R.,Geisenheim University
Journal International des Sciences de la Vigne et du Vin | Year: 2017

The predicted developments in climate are region-specific and adaptation can only be successful considering the regional characteristics with its diverse technical, environmental, economic and social implications. Beyond some obvious adaptation strategies in response to emerging environmental constraints for example there are many more "basic" challenges below "the surface". One of the key concerns for many regions is the availability of water and how increasing temperature will drive the evaporative demand of the atmosphere. For this, individual regions need to be analysed to quantify possible associated risks. This paper will address differences in regional water relations of grape growing areas in different parts of the world as a basis to address the points listed above. © Université de Bordeaux (Bordeaux, France).

Rondot Y.,Geisenheim University | Reineke A.,Geisenheim University
Biocontrol Science and Technology | Year: 2017

Fungal entomopathogens are known as microbial pathogens of insects, colonising multiple habitats and ecosystems. Besides being an entomopathogen, the fungus Beauveria bassiana can also establish as an endophyte in plants. Limited knowledge is so far available on the ability of plant-associated B. bassiana to influence plant-feeding insects. Here, we assessed the capability of adult black vine weevils Otiorhynchus sulcatus to select grapevine as a host plant in the presence of plant-associated B. bassiana after foliar application of a commercially available mycoinsecticide (product Naturalis®) on young potted grapevine plants. Three pairwise comparisons of weevil behaviour were conducted when weevils were released in a two-choice olfactometer and were given the choice between (i) control plants and plants treated with Naturalis®, (ii) control plants and plants treated with the formulation of Naturalis® without fungal propagules, and (iii) plants treated with Naturalis® and plants treated with the formulation. Adult O. sulcatus were significantly deterred by plants treated with Naturalis® or the formulation in comparison to control plants. In a direct comparison between plants treated either with Naturalis® or the formulation weevils significantly preferred plants treated with the formulation and avoided Naturalis® treated plants, where B. bassiana putatively had established as an endophyte. These results suggest that adult black vine weevils are able to detect and subsequently avoid plants treated with B. bassiana and indicate a new mode of action of plant-associated entomopathogenic fungi when integrated in pest management programmes. © 2017 Informa UK Limited, trading as Taylor & Francis Group

Hanf J.H.,Geisenheim University | Schweickert E.,Geisenheim University
Journal of Wine Research | Year: 2014

Wine cooperatives have a long tradition and still account for roughly a third of the German wine market. Based on cooperative values and seven cooperative principles, the legally manifested business goal of cooperatives is to patronize their members' business activities. As the members are grape growers, member-orientation leads to a business policy of production-orientation which stands in strong contrast to the customer orientation which is associated with saturated competitive markets. The aim of this article is to analyse this area of conflict. Based on the results of this analysis, we intend to shed some light on the relation between the wines produced by cooperatives and their origin as a means of marketing. © 2014 Taylor & Francis.

Reineke A.,Geisenheim University | Thiery D.,CNRS Agroecology Lab
Journal of Pest Science | Year: 2016

We review direct and indirect effects of climate change on both the grapevine plant as a host for phytophagous insects, as well as on grape insect pests, their natural enemies and corresponding future grape plant protection strategies. Phenology, voltinism and distribution ranges are well known traits of many arthropods influenced by temperature as the key abiotic factor and thus by current and future climate change scenarios. Case studies of grapevine pests based on data from three decades point to clear changes in phenology of grape berry moths, shifts in distribution ranges of leafhoppers as vectors of grapevine diseases and range expansion of grapevine mealybugs. These case studies also illustrate the need to include data on putatively changed tri-trophic interactions in vineyards when predicting impacts of climate change on grapevine pest insects. Hence, future pest management strategies should be based on a sound set of field data obtained for both pests and antagonists under changed abiotic conditions, which can also build the basis for refining and extending currently existing models for forecasting population levels of respective insect pests. © 2016 Springer-Verlag Berlin Heidelberg

Szolnoki G.,Geisenheim University
Journal of Cleaner Production | Year: 2013

This cross-national study investigates different aspects of sustainability from the wine producers' point of view. A qualitative study conducted with fifty-five wine producers in the USA, France, Spain, Italy, Germany, Hungary and Greece was undertaken to analyse the producers' definition, evaluation and practice of sustainability in the wine industry. Results show that the interviewed producers mainly associated the term sustainability solely with the environmental dimension; whereas some wineries applied a more complete approach of sustainability including not only the environmental, but also the economic as well as the social dimensions. Regarding the production management systems, there is some ambiguity since many of the interviewees confuse the terms organic, biodynamic and sustainable. The majority of the wineries participating in this study complain about the lack of information among relevant organizations, producers and consumers concerning sustainability. The barriers to this flow of information might be the great challenge the sustainable wine industry will face in future. All these findings indicate the necessity of closer cooperation of national organizations on an international level in order to provide the information needed by the wine producers and consumers. © 2013 Elsevier Ltd. All rights reserved.

Otto D.,Johannes Gutenberg University Mainz | Petersen R.,Johannes Gutenberg University Mainz | Brauksiepe B.,Geisenheim University | Braun P.,Geisenheim University | Schmidt E.R.,Johannes Gutenberg University Mainz
Molecular Breeding | Year: 2014

The columnar growth habit of apple trees (Malus × domestica Borkh.) is a unique plant architecture phenotype that arose as a bud sport mutation of a McIntosh tree in the 1960s. The mutation ("Co gene") led to trees (McIntosh Wijcik) with thick, upright main stems and short internodes that generate short fruit spurs instead of long lateral branches. Although Co has been localized to chromosome 10, in a region approximately between 18.5 and 19 Mb, its molecular nature is unknown. In a classical positional cloning approach in combination with the analysis of NGS data, we cloned and analyzed the Co region. Our results show that the insertion of a Ty3/Gypsy retrotransposon into a non-coding region at position 18.8 Mb is the only detectable genomic difference between McIntosh and McIntosh Wijcik and is found in all columnar cultivars. The genetic effect of the insertion is unclear; however, Illumina® RNA-seq data of McIntosh and McIntosh Wijcik suggest that the columnar growth habit is associated with differential expression of the retrotransposon transcript, causing changes in the expression levels of many protein coding genes. The mechanism by which the Gypsy retrotransposon is involved in generating the columnar habit is not yet clear; our findings form the basis for tackling this question. © 2013 Springer Science+Business Media Dordrecht.

Bonisch F.,TU Munich | Frotscher J.,Geisenheim University | Stanitzek S.,University of Bonn | Ruhl E.,Geisenheim University | And 3 more authors.
Plant Physiology | Year: 2014

Terpenoids represent one of the major classes of natural products and serve different biological functions. In grape (Vitis vinifera), a large fraction of these compounds is present as nonvolatile terpene glycosides. We have extracted putative glycosyltransferase (GT) sequences from the grape genome database that show similarity to Arabidopsis (Arabidopsis thaliana) GTs whose encoded proteins glucosylate a diversity of terpenes. Spatial and temporal expression levels of the potential VvGT genes were determined in five different grapevine varieties. Heterologous expression and biochemical assays of candidate genes led to the identification of a UDP-glucose: monoterpenol b-D-glucosyltransferase (VvGT7). The VvGT7 gene was expressed in various tissues in accordance with monoterpenyl glucoside accumulation in grape cultivars. Twelve allelic VvGT7 genes were isolated from five cultivars, and their encoded proteins were biochemically analyzed. They varied in substrate preference and catalytic activity. Three amino acids, which corresponded to none of the determinants previously identified for other plant GTs, were found to be important for enzymatic catalysis. Site-specific mutagenesis along with the analysis of allelic proteins also revealed amino acids that impact catalytic activity and substrate tolerance. These results demonstrate that VvGT7 may contribute to the production of geranyl and neryl glucoside during grape ripening. © 2014 American Society of Plant Biologists. All Rights Reserved.

Bonisch F.,TU Munich | Frotscher J.,Geisenheim University | Stanitzek S.,University of Bonn | Ruhl E.,Geisenheim University | And 3 more authors.
Plant Physiology | Year: 2014

Monoterpenols serve various biological functions and accumulate in grape (Vitis vinifera), where a major fraction occurs as nonvolatile glycosides. We have screened the grape genome for sequences with similarity to terpene URIDINE DIPHOSPHATE GLYCOSYLTRANSFERASES (UGTs) from Arabidopsis (Arabidopsis thaliana). A ripening-related expression pattern was shown for three candidates by spatial and temporal expression analyses in five grape cultivars. Transcript accumulation correlated with the production of monoterpenyl β-D-glucosides in grape exocarp during ripening and was low in vegetative tissue. Targeted functional screening of the recombinant UGTs for their biological substrates was performed by activity-based metabolite profiling (ABMP) employing a physiologic library of aglycones built from glycosides isolated from grape. This approach led to the identification of two UDP-glucose:monoterpenol β-D-glucosyltransferases. Whereas VvGT14a glucosylated geraniol, R,S-citronellol, and nerol with similar efficiency, the three allelic forms VvGT15a, VvGT15b, and VvGT15c preferred geraniol over nerol. Kinetic resolution of R,S-citronellol and R,S-linalool was shown for VvGT15a and VvGT14a, respectively. ABMP revealed geraniol as the major biological substrate but also disclosed that these UGTs may add to the production of further glycoconjugates in planta. ABMP of aglycone libraries provides a versatile tool to uncover novel biologically relevant substrates of small-molecule glycosyltransferases that often show broad sugar acceptor promiscuity. © 2014 American Society of Plant Biologists. All Rights Reserved.

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