@phdthesis{Hendgen2021, author = {Hendgen, Maximilian}, title = {Beeinflussung der Seneszenz bei Weinreben als Anpassungsstrategie an den Klimawandel}, volume = {2021}, edition = {1. Auflage}, publisher = {Gesellschaft zur F{\"o}rderung der Hochschule Geisenheim}, address = {Geisenheim}, isbn = {13 978-3-934742-85-7}, url = {http://nbn-resolving.de/urn:nbn:de:hebis:2083-329}, school = {Hochschule Geisenheim University}, pages = {211}, year = {2021}, abstract = {Blattseneszenz stellt bei Pflanzen einen genetisch geregelten, komplexen Alterungsprozess dar. Sie wird durch die Kombination von Umwelt- und Altersfaktoren ausgel{\"o}st und dient dem Recycling von N{\"a}hrstoffen. Charakteristisch f{\"u}r die Blattseneszenz sind eine erh{\"o}hte Expression von Seneszenz-assoziierten Genen (SAGs), der Abbau von Chlorophyll und die R{\"u}ckverlagerung von N{\"a}hrstoffen, insbesondere von Stickstoff (N). Bei der Weinrebe Vitis vinifera dient N nicht nur dem pflanzlichen Wachstum, sondern auch der Hefeern{\"a}hrung w{\"a}hrend der alkoholischen G{\"a}rung des Mostes. Der Gehalt an hefeverf{\"u}gbarem N (YAN) in der Beere h{\"a}ngt sowohl von der N-Verf{\"u}gbarkeit des Standorts, als auch von der N-Einlagerung w{\"a}hrend der Reife ab. Durch den Klimawandel erfolgen Traubenreife und Blattseneszenz zunehmend zeitlich entkoppelt, wodurch im Most der in n{\"o}rdlichen Anbaugebieten sp{\"a}treifenden Rebsorte Vitis vinifera cv. Riesling der f{\"u}r eine gute Verg{\"a}rbarkeit empfohlene Zielwert von 150 mg/L YAN nicht erreicht wird und das Risiko von G{\"a}rproblemen steigt. Daher wurde in dieser Arbeit auf zwei Standorten mit unterschiedlicher N-Verf{\"u}gbarkeit und in zwei Jahren untersucht, ob durch eine Behandlung mit Ethephon oder UV-C vor der Lese Blattsenszenz induziert, und durch Umverlagerung des remobilisierten N in die Beere eine ausreichende Konzentration an YAN im Most erzielt werden kann. Die Ethephon-Behandlung induzierte Blattseneszenz zuverl{\"a}ssig und schnell, ihre N-Remobilisierung wie auch ihre Genexpression glichen der von nat{\"u}rlicher Seneszenz. Die UV-C-Behandlung erzeugte ebenfalls Seneszenz-Symptome, sie erreichte jedoch nicht die Effektivit{\"a}t der Ethephon-induzierten und der nat{\"u}rlichen Seneszenz. Auf dem Standort mit geringer N-Verf{\"u}gbarkeit konnte durch die Ethephon-Behandlung die YAN-Konzentration im Most gesteigert werden, durch die UV-C-Behandlung hingegen nicht. Auf dem Standort mit guter N-Verf{\"u}gbarkeit hatte keines der beiden Verfahren einen Effekt auf die Most-N-Versorgung. Die erreichten YAN-Steigerungen verbesserten die Verg{\"a}rbarkeit, obwohl der Zielwert von 150 mg/L in keinem Fall erreicht wurde. Die zur Sicherstellung einer guten G{\"a}rleistung empfohlene YAN-Konzentration im Most ist daher kritisch zu {\"u}berpr{\"u}fen.}, language = {de} } @phdthesis{Pabst2020, author = {Pabst, Evelyn}, title = {Effects of potential EU regulation on mandatory nutrition and ingredient labelling for wine}, volume = {2021}, edition = {1. Auflage}, publisher = {Hochschule Geisenheim}, url = {http://nbn-resolving.de/urn:nbn:de:hebis:2083-253}, school = {Hochschule Geisenheim University}, pages = {68}, year = {2020}, abstract = {With the exception of ingredients that may have an allergenic effect, alcoholic beverages with above 1.2\% alcohol by volume are currently exempt from mandatory nutrition and ingredient labelling. In 2017, however, the European Commission decided that, in order to protect consumer interests, further exemption from this special regulation could not be justified. Mandatory nutrition and ingredient labelling for wine will affect not only all European producers but also every international producer who exports wine to an EU member state. Many studies have investigated how consumers behave in relation to nutrition labelling and ingredient listings for food in general, but only a few have considered alcoholic beverages and wine specifically. Existing studies of wine are limited to quantitative approaches that focus on consumers' stated interests regarding ingredient and nutrition information, utilising the direct elicitation of stated preferences. These methods are prone to greatly overestimate the effect. There is a lack of more indirect observational studies in more realistic settings that analyse consumers' emotional and verbal reactions when confronted with ingredient and nutrition information on a bottle of wine as well as the implications that this information will have on their choice behaviour. Finally, there is a lack of empirical research on the consequences that mandatory nutrition and ingredient labelling will have for producers. In order to fill these gaps, the main objectives of this dissertation are the following: First, to analyse consumers' reactions to nutrition and ingredient labelling covering their emotional reactions and the effect on wine choice and demand as well as the influences of additional information, time and country. Second, to examine the consequences that producers are facing with regard to nutrition and ingredient labelling for wine by analysing producers' expectations of consumer reactions as well as the effects on production processes and competitive advantages. A multi-stage multi-method research design, which combined qualitative focus groups and a discrete choice experiment, was utilised to analyse consumers' reactions to nutrition and ingredient labelling for wine across several countries. In order to analyse the consequences that the potential new EU labelling law will have for wine producers, an exploratory online survey to ask producers directly was utilised. The results suggest that the wine industry will face considerable challenges once nutrition and ingredient labelling is mandatory. Consumers' emotional reactions, especially to the ingredients in wine, are rather negative, and they are becoming less likely to view wine as a very natural product. Average wine-involved consumers were shown to place a considerable amount of importance on nutrition information in a retail setting and prefer to receive complete information. Without additional guidance, consumers only place low importance on ingredient information, but this changes when they are negatively confronted with the topic. Negative information has the potential to affect how consumers choose wine by increasing the attention they pay to ingredients, at the cost of the attention directed at sensory descriptions, and by changing consumers' preferences to shorter ingredient lists. Some consumers in traditional wine markets are even likely to refrain from buying wine in the case of negative media coverage. While consumers will be strongly affected by nutrition and ingredient labelling in the short term, they are likely to adapt to this information in the mid to long term, which will reduce the effect of negative media coverage. In addition to the effects on consumer behaviour, mandatory nutrition and ingredient labelling will likely also change production processes and competitive advantages within the wine industry. In order to actively avoid declarable substances, some producers will change their oenological practices, which might lead to a deterioration in wine quality and higher wine prices. Providing correct nutrition and ingredient information for each batch will make the labelling process more difficult and more expensive. Although consumers highly value sensory information, this information is likely to be reduced or eliminated when nutrition and ingredient labelling is introduced as the competition for space on back labels will increase. The introduction of mandatory nutrition and ingredient labelling is also likely to affect competitive advantages between wine producers. Producers that are able to and willing to adapt will have the chance to gain competitive advantages. Overall, producers are advised to adapt their communication strategies to actively promote the reasons for the use of ingredients in wine production in order to reduce the effects of negative media coverage. The industry should also prepare in advance for changes in production processes and potential changes in consumer preferences because mandatory nutrition and ingredient labelling will likely be introduced within the next few years.}, language = {en} } @phdthesis{Brandt2021, author = {Brandt, Melanie}, title = {The influence of abiotic factors on the composition of berries, juice and wine in Vitis vinifera L. cv. Riesling}, volume = {2021}, edition = {1. Auflage}, publisher = {Hochschule Geisenheim}, address = {Geisenheim}, url = {http://nbn-resolving.de/urn:nbn:de:hebis:2083-260}, school = {Hochschule Geisenheim University}, pages = {269}, year = {2021}, abstract = {Grapevine physiology and berry composition are highly influenced by abiotic factors, and this, in turn, affects wine composition and aroma. Primary metabolites, like sugars and acids, and also secondary metabolites, like phenols and terpenes, are sensitive to climatic conditions. However, the developmental stage of the berries and the environmental conditions within the bunch zone play a crucial role determining the different pathways of the metabolites and hence its concentration. This study aimed to investigate the influence of abiotic factors on the composition of berries, juice and wine of Vitis vinifera L. cv. Riesling. Field experiments were carried out in an experimental site of Hochschule Geisenheim University [Eibinger Magdalenenkreuz, Germany (49° 59'20'' N; 7° 55'56'' E)] using Riesling [clone 198-25Gm; grafted on rootstock SO4 Gm47 (Vitis berlandieri x V. riparia)]. In a non-irrigated vineyard, planted in 2007, the vines were trained to a vertical shoot position canopy system. The impact of global warming and rising temperature was one of the main questions of this thesis, and was simulated by an open heating system (OHS) in the vineyard. The tent-like construction passively heated the bunch zone. The effect of higher sun exposure on berries was trialed by the defoliation of the bunch zone at different stages of berry development. The removal of leaves around bunches is commonly used in coolclimate viticulture to improve the health status of berries and influence the aroma profile. Due to the increasing numbers of sunshine hours as well as the rising temperatures caused by climate change, the question then arises if in future defoliation practices will be the method of choice. Additionally, and in contrast, some bunches were placed in light-excluding boxes to simulate full shading. On days with high radiation, the open heating system clearly elevated temperatures compared to the control and the defoliation treatments. In the bunch zone above the open heating system, the air temperature was 4 °C higher compared to the other treatments. Inside the open heating system, the temperature was up to 13 °C higher. On days with low radiation, there was a minimal temperature difference between the treatments. The porosity of the bunch zone was quantified by a novel approach using lightsensitive films which provide a simple and accurate method for characterizing light conditions and quantifying cumulative radiation within the canopy. Different lightsensitive film qualities allow the measurement over a short period (3-7 days) or a more extended period (1-3 weeks). One of the significant advantages of this method will be that simultaneous measurement of several points will be possible. The health status of the berries was improved by defoliation and the infection (incidence and severity) of Botrytis cinerea reduced compared to the control providing a faster drying of bunches after morning dew or rainfall. Similarly, the OHS promoted airflow inside the bunch zone, causing same effects. Higher temperatures significantly reduced the berry weight, with the effect more pronounced if higher temperatures occurred before v{\´e}raison. Berries grown under higher temperatures showed lower total soluble solids and the glucose to fructose ratio was impacted by lower glucose concentrations. A change in the glucose to fructose ratio will be of relevance for the fermentation since most yeasts prefer glucose over fructose. Defoliation treatment had no impact on the total soluble solids. In contrast, intense radiation or shading did not affect the berry size while extreme shading of the bunches reduced total soluble solids. Tartaric acid was not significantly influenced by higher temperatures or radiation, but malic acid concentrations strongly declined under warmer conditions. This decreased the total acidity in juice and wine, which is of particular importance for the wine profile of Riesling. The defoliation practices showed only little effect on the acid concentrations whilst the extreme shading treatments strongly increased the acidity. The analysis of phenols in berry skin was performed by high-performance liquid chromatography (HPLC) coupled to a photodiode array (PDA) detector and quantified with an external calibration. Flavonols, in particular, were influenced by higher sun exposure, with significantly higher flavonol concentrations found in the defoliation treatments. The time point when defoliation was applied had only small effects on the final total flavonol concentration. On the other hand, when a sunny period occurred after v{\´e}raison flavanols revealed high concentrations after defoliation. Sunny periods before v{\´e}raison or a ripening period with low sunshine hours did not increase the flavanol concentration compared to the control. No impact of the defoliation on the group of hydroxycinnamic acids, non-flavanoids, was The sensory assessment with small scale-vinifications was diverse. Only in the younger vintage, the panellists were able to detect differences in wines, which were mainly based on total acidity. The influence of the treatments to the grapes, which were observed for primary and secondary metabolites in berries and juice, were found in wine as well. The only expectation was TDN. In wines, higher TDN concentrations were always detected for the late defoliation. The early defoliation contained higher TDN concentrations if a sunny period occurred before v{\´e}raison. Also, elevated temperatures caused higher TDN levels in wine. The prediction of the precise temperature and light conditions influencing TDN will require detailed investigations. A new approach was developed to analyse and quantify free and glycosidically bound monoterpenes and C13-norisoprenoids in berries, juice and wine. The sample volume was reduced by 90\% and free analytes were directly analysed from the matrix with only little sample preparation. This simplified the analysis, saved time and made the use of organic solvents and solid-phase extraction cartridges redundant. The method was validated and compared to other methods in literature. In juice and wine 15 monoterpenes and four C13-norisoprenoids could be analysed simultaneously and the typically concentration ranges of the samples were covered.}, language = {en} } @phdthesis{Laier2020, author = {Laier, Marcus}, title = {Analytical Characterisation and Properties of Innovative and Commercial Oenological Agents Based on Yeasts Marcus Laier}, volume = {2020}, edition = {1. Auflage}, publisher = {Gesellschaft zur F{\"o}rderung der Hochschule Geisenheim}, address = {Geisenheim}, isbn = {13 978-3-934742-81-9}, url = {http://nbn-resolving.de/urn:nbn:de:hebis:2083-292}, school = {Hochschule Geisenheim University}, pages = {194}, year = {2020}, abstract = {Produkte auf Basis von Hefen sind ein neuer Trend in der {\"o}nologischen Anwendung. Hefeprodukte (YDPs) werden in jeder Phase der Weinherstellung eingesetzt, vom Weinberg bis zum Wein. Die meisten Produkte sollen als N{\"a}hrstoffversorgung entweder die alkoholische oder die malolaktische G{\"a}rung unterst{\"u}tzen. YDPs k{\"o}nnen aber auch als Aromaverst{\"a}rker oder Sch{\"o}nungsmittel dienen. Die Anzahl der Produkte und Anwendungen nimmt st{\"a}ndig zu und somit wird die Nachfrage nach einem tieferen Einblick in dieses Thema immer wichtiger. Die vorliegende Dissertation dient als Basis f{\"u}r weitere Studien und Charakterisierungen der Hefederivate (YDPs). Des Weiteren zeigt sie, dass die Themen, die weiter verfolgt und an denen in Zukunft geforscht werden kann, vielf{\"a}ltig sind. Bereits existierende Methoden k{\"o}nnen angewandt werden, wobei fallweise Adaptionen notwendig sind. Standardverfahren (SOPs) f{\"u}r weitere reproduzierbare Analysen k{\"o}nnen bereitgestellt werden. F{\"u}r die meisten Parameter sind beachtliche Schwankungen zwischen den Proben zu verzeichnen. Nur Ammonium und die Tr{\"u}bung (NTU) bilden Ausnahmen. Der Parameter "wasserl{\"o}slicher Anteil" zeigt den gr{\"o}ßten Einfluss. Hochl{\"o}sliche Proben zeigen meist einen h{\"o}heren Gehalt an den gemessenen Parametern im Vergleich zu Proben mit geringerer L{\"o}slichkeit (und h{\"o}herem Anteil unl{\"o}slicher Masse). Dies f{\"u}hrt zur Schlussfolgerung, dass die YDPs aus zwei Gruppen - abh{\"a}ngig von der L{\"o}slichkeit - bestehen. Diese zwei Gruppen m{\"u}ssen bei der (multi-variaten) Datenauswertung und -interpretation, sowie bei der Kalibration spektroskopischer Methoden getrennt gehalten werden. Die multi-variate Datenexploration erweist sich als hoch effektiv und aufschlussreich. Ausreißer k{\"o}nnen detektiert und erkl{\"a}rt werden. Sowohl die FTIR-Messungen der Eluate und Suspensionen, als auch die UV-VIS/NIR-Messungen ergeben {\"a}hnliche Resultate. Spektroskopische Methoden sind starke Werkzeuge zur Analyse und Charakterisierung von Hefederivaten. Die Datenvorbereitung ist entscheidend und unabdingbar, aber L{\"o}sungen k{\"o}nnen aufgezeigt werden. Die Kalibrationen f{\"u}r die verschiedenen spektroskopischen Methoden sind vielversprechend. Dies beweist, dass es lohnt, auf diesem Feld weiterzuarbeiten. Einzig die ATR-FTIR zeigte zu viele Mankos. Die UV-VIS/NIR-Kalibrationen k{\"o}nnten verbessert werden, indem eine pr{\"a}zisere und f{\"u}r die Proben besser geeignetere Apparatur verwendet wird. Eine Gruppierung nach der L{\"o}slichkeit ist die einzige Gruppierung, die mit dem Datensatz dieser Studie vorgenommen werden kann. Weder die Gruppierung nach der Hauptanwendung, noch nach dem Hersteller zeigt ein Muster. Eine Trennung von oenologischen Produkten und Produkten aus der Lebensmittelindustrie zeigt sich nicht. Die Produkte der Lebensmittelindustrie sind hochl{\"o}slich und k{\"o}nnen von den weniger l{\"o}slichen oenologischen Produkten unterschieden werden. Allerdings k{\"o}nnen die l{\"o}slichen oenologischen Produkte (Hefeextrakte, Mannoproteine) nicht von den Produkten f{\"u}r die Lebensmittelindustrie unterschieden werden.}, language = {en} } @phdthesis{Zeng2021, author = {Zeng, Lishi}, title = {Drivers and inhibitors of consumer adoption to a new product category in emerging market: the case of wine in China}, volume = {2021}, edition = {1. Auflage}, publisher = {Hochschule Geisenheim}, address = {Geisenheim, Germany}, url = {http://nbn-resolving.de/urn:nbn:de:hebis:2083-203}, school = {Hochschule Geisenheim University}, pages = {151}, year = {2021}, abstract = {Past adoption research has focused on new ideas, services and consumer durable goods where the first purchase is sufficient to be regarded as the act of adoption. Adoption studies rarely expand its application on new consumer packaged goods (CPGs) where subsequent repeat purchases are in high demand. Every year, the CPG industry spends a large amount of budget on developing and launching new products into the market in order to generate competitiveness, hence yielding financial growth. Despite the fact that new products have been carefully designed and tested before launch, the majority of them still fail. Consumers may talk the talk in pre-market tests but walk the walk after product launch. Such a gap between stating an intention for the future and taking action in the proximal may come from a lack of understanding the dynamic nature of the adoption process. Consequently, this thesis investigates the process and antecedents of adopting new CPGs, which is also known as fast moving consumer goods (FMCGs). This thesis aims to unveil how the influence of adoption antecedents change along the process. Three research questions are raised: 1) What is the adoption process of new CPGs? 2) What are the key factors of adopting a specific product category in an emerging market? 3) How do the effect sizes of these adoption factors change along the process? The wine category in China is selected to be the research context. The exploratory sequential mixed-method approach is designed in two phases. In Study 1, twenty-six face-to-face, in depth interviews with both wine adopters and non-adopters were conducted in two Chinese cities to outline the adoption process and refine the key adoption antecedents. Then the key adoption antecedents were further discussed and subjected to a hypothetical model. In Study 2, an online survey was launched to collect data from 1,567 alcohol consumers nationwide. Structural equation modelling was applied in testing the effect sizes of the adoption antecedents and corresponding process dynamic effects. The results indicate three major discoveries. 1) The adoption of new CPGs is a long process concerning repeat purchases or consumptions after the first trial. Unlike Rogers' process model (Rogers 2003), there are not many cognitive considerations before adoption behaviour occurs. The subsequent repeat purchases after the first trial are more decisive on how far a consumer can reach along the adoption journey. After the first trial, two milestone intermediate stages were identified: increasing exposure and reinforcement. Consumers start to build up the association between products and consumption occasions at the increasing exposure stage. Later into the reinforcement stage, these associations expand to more frequent consumption occasions. This empirical finding highlights the importance of understanding post-trial repeat purchases for the CPG industry and research, not just the first purchase. 2) Adoption intention is different to adoption behaviour. Different adoption outcomes have been used interchangeably in adoption research and in pre- market tests, especially adoption intention and behaviour. This study finds that adoption intention associates weakly with adoption behaviour. These two different adoption outcomes are influenced by different antecedents. Personal traits are more influential on adoption intention; while consumption behaviour and relative advantages of the new product drive adoption behaviour. This discovery suggests that adoption variables from different time points of the process should not be used interchangeably or utilise one to predict the other one. Furthermore, adoption variables should be selected carefully according to the antecedents of interest. 3) The influence of past consumption behaviour on adoption behaviour is dynamic along the adoption process. This discovery adds one more empirical evidence that adoption antecedents exhibit different influence on adoption at different behavioural stages. It sheds light on the process dynamic effect of adoption antecedents and responses to the call of process-oriented studies by adoption researchers.}, language = {en} } @phdthesis{Tafel2021, author = {Tafel, Maximilian Carl}, title = {Investigating the Characteristics and the Economic Impact of Tourism in German Wine Regions}, volume = {2021}, edition = {1. Auflage}, publisher = {Hochschule Geisenheim}, address = {Geisenheim}, url = {http://nbn-resolving.de/urn:nbn:de:hebis:2083-188}, school = {Hochschule Geisenheim University}, pages = {124}, year = {2021}, abstract = {Wine tourism is a growing niche market around the world. Germany seems to offer an ideal platform for this promising market. However, there is very limited knowledge about the economic significance of wine tourism in Germany and about understanding visitors' needs and expectations. By proposing a framework for three different studies across all 13 German wine regions, including both the travelers' and the wineries' perspective, this thesis aims to alter the understanding of wine tourism in Germany. The three main research questions derived from a survey of the literature (see Chapter 1) are: 1. What differentiates wine tourists in Germany from other tourist segments? 2. How large is the economic impact of wine tourism in Germany? 3. How relevant is wine tourism in Germany from a winery operators' perspective? In order to separate wine tourists from other tourist segments, a quantitative study with 4,478 visitors to wine regions was carried out. By interviewing visitors at "wine-neutral" locations such as city centers or cultural sites, this approach differed from previous research. After segmentation, travelers were divided into wine tourists and other tourist segments. Then, a modified multiplier model was developed that allows measuring the economic impact of wine tourism. Finally, to include the wineries' perspective, 199 qualitative in-depth interviews and 703 quantitative online questionnaires were collected and analyzed. It is the aim of the winery surveys to reveal the relevance and main challenges of wine tourism in Germany. Results show that 7.2 million wine tourists, of whom 89\% are Germans, visit the country's wine regions each year. For them, tasting wine, enjoying nature and combining food and wine experiences are the main motivating factors for visiting a wine region. Wine tourism has a disproportionately large economic impact of EUR 5.0 billion annually, contributing to the income of 71,846 people. From an average winery operator's perspective, wine tourism accounts for 24\% of company sales. Despite an increasing demand in wine-touristic activities, the number of wineries, as well as restaurants, is declining which reduces the attractiveness for culinary-focused wine tourists. To successfully develop wine tourism in Germany, there is a clear need for collaboration among stakeholders. Furthermore, the preservation of cultural landscapes plays an important role in attracting visitors. This thesis advances the understanding of wine tourism in Germany from a visitor's as well as a winery's point of view. The approaches developed for segmenting wine tourists and for assessing the economic impact of wine tourism can be applied in any wine region of the world. They can also be transferred to other forms of special-interest tourism (e.g. alpine tourism and culinary tourism). The findings and discussions can be used for teaching students and training stakeholders at the regional, entrepreneurial and personal level. Wine tourism could help to balance inequalities between rural and urban areas in terms of income and employment levels. This, combined with the preservation of natural resources and cultural landscapes, could lead to sustainable regional development in the German wine regions.}, language = {en} } @phdthesis{Uzman2020, author = {Uzman, Deniz}, title = {Effects of landscape structure and farming type on biodiversity and ecosystem functions in vineyard ecosystems}, volume = {2020}, edition = {1. Auflage}, publisher = {Hochschule Geisenheim}, address = {Geisenheim}, url = {http://nbn-resolving.de/urn:nbn:de:hebis:2083-148}, school = {Hochschule Geisenheim University}, pages = {182}, year = {2020}, abstract = {Almost 40\% of the world's terrestrial surface is covered by agriculture. Thus, agricultural land is of particular importance for the conservation of biodiversity. At the same time, the intensification of management practices and the concomitant homogenization of landscapes are main drivers for a severe loss of biodiversity. The protection of arthropods in agricultural landscapes has gained increased attention facing the current biodiversity crisis. In agricultural landscapes, grapevine is a particularly intensively managed crop, which is characterised by frequent application of fungicides. On the other hand, vineyards and especially the inter-rows between vines with their permanent character can serve as habitats for many organisms. Additional nesting and feeding resources for beneficial arthropods can be provided. Measures to enhance biodiversity in viticulture mainly encompass organic management and the management of inter-row vegetation cove, for example by tillage regime or the use of seed mixtures. Little is known about the effectiveness of these measures for the diversity of different species groups, especially in interaction with the surrounding landscape context. Within the framework of the presented dissertation, various measures to enhance biodiversity were investigated using different organism groups in vineyards. The main part of this work is based on a field study in which organic and conventional management were compared. For this purpose, 15 pairs of organically and conventionally managed vineyards along a gradient of landscape complexity in Rhinehessen were chosen. The effects of management system, landscape context and inter-row vegetation structure on different species groups within vineyards were compared. Studied groups included entomopathogenic fungi in the soil, soil-dwelling spiders and carabid beetles as well as flying, cavity-nesting solitary bees and wasps. In an additional experiment, four different soil treatments and their effects on carabid beetles and their weed predation potential were compared in two consecutive years. Therefore, four experimental plots each were installed in nine additional vineyards in Rhinehessen. For these vineyards, landscape structure and inter-row vegetation cover was also characterised. Overall, each of the investigated species groups benefited from different measures and landscape or vegetation structure. Organically managed vineyards did not show a general increase in biodiversity, even though their soils had higher organic matter contents on average and their vegetation cover offered more floral resources. Entomopathogenic fungi were found to be particularly well adapted to increased copper levels in the soil. Soil copper contents tended to be higher under organic management. Solitary bees and soil-dwelling spiders profited from organic farming. Enhanced landscape complexity, i.e. the connectivity of semi-natural habitat elements and the area covered by them was particularly beneficial for solitary bees and spiders. An increasing proportion of area covered by annual crops in the vicinity of vineyards had a negative effect on carabid beetles and solitary wasps. While the wasps benefited from dense inter-row vegetation cover, carabid beetles preferred sparse vegetation cover. Similarly, more intensive tillage regimes did not have a negative effect on them. It should be emphasized that all the sampled vineyards - whether organically or conventionally managed - hosted species of conservation concern from all investigated groups. With a diverse mixture of landscape structures as well as a variation of management strategies and soil and vegetation covers within fields, viticultural landscapes can contribute significantly to the protection of agrobiodiversity.}, language = {en} } @phdthesis{Neumann2020, author = {Neumann, Lena}, title = {Improving the apple carbon balance model MaluSim by integrating and testing water deficit and fruit drop effects}, volume = {2020}, edition = {1. Auflage}, publisher = {Hochschule Geisenheim}, address = {Geisenheim}, url = {http://nbn-resolving.de/urn:nbn:de:hebis:2083-139}, school = {Hochschule Geisenheim University}, pages = {162}, year = {2020}, abstract = {Apple (Malus x domestica Borkh.) is the major tree fruit in Germany, but there still exist major uncertainties in commercial apple production. Thinning has been practiced for many years and is an essential part for successful apple production, but is still an unpredictable part with large variations from year to year and even within years. Another uncertainty for apple growers is the need of apple trees for adequate water supply. Due to the advancing climate change apple growers are uncertain whether additional irrigation will be necessary during the establishment phase of young apple trees. Therefore, to facilitate these decisions in future, the motivation of this study was to acquire a universal apple model to be used in Germany and Central-Europe. The apple carbon-balance model MaluSim which has been developed in the USA was chosen as a basis. At first, the model has been parameterized for German growing conditions and first simulation runs were conducted. In comparison to the original model, the seasonal assimilate production for German standard trees was about half of the one for standard trees in the USA, while standard trees in Germany were only about one third of the size of US ones. Subsequently, the previously untested fruit growth and abscission submodel has been modified and tested. Simulated final fruit numbers were compared to counted fruit numbers of unthinned trials in Zornheim (GER), Jork (GER), Lindau (CH), G{\"u}ttingen (CH) and W{\"a}denswil (CH). The modification 'G4-4' showed good simulation results with very low deviations to actual fruit numbers. Average deviation to fruit numbers was only 3.7 \%. Results indicate that the model is able to very adequately calculate final fruit numbers of natural fruit drop of Central-European apple trees and that it could be a tool used for thinning advices. Based on published data, a new water submodel has been included into the MaluSim framework to additionally improve the model. Midday stem water potential has been used as an indicator for water status of the tree. A water stress effect on long shoot growth, respiration, and photosynthesis based on midday stem water potential was used in the water submodel. First simulation runs using the new water submodel indicate that general behavior is realistic. Modeling results generally corresponded to findings of published experimental results. The submodel is able to simulate variable intensities of water deficit effects at variable times. To study the effects of additional irrigation and water deficits on young apple orchards a field experiment was conducted during 2012 and 2013 in Geisenheim, Germany. Trees of the cultivars 'Fresco' ('Wellant®'), 'Jugala', and 'AW 106' ('Sapora®') were planted in autumn 2011 in a randomized plot design. In 2012, three irrigation treatments, CT (control treatment, only rain fed), NT (normal treatment, irrigated with 2 L/tree/day), and ET (evapotranspiration treatment, irrigation based on calculated water balance), were applied and effects on tree growth and physiology were recorded in 2012 and 2013. Besides soil moisture, water status of the trees has been recorded using predawn and midday stem water potential measurements. In both years, amounts of precipitation were higher than the 30-year average for the site, with 2013 being wetter than 2012. Between treatments, statistically significant differences developed in both seasons, but were less profound in 2013. In 2012, vegetative growth recorded in NT and ET was statistically significantly higher than in CT for all cultivars. In the wetter season 2013, similar tendencies evolved. But only in 'Jugala' and 'Fresco' long shoot growth and wood surface area was significantly higher, while for 'AW 106' differences in long shoot growth were not statistically significant. Similar results were obtained for the first harvest in 2013. Light interception and calculated leaf area, measured in 'Fresco', was significantly lower in CT trees (2012: 17.4 \%; 2013: 24.9 \%) compared to ET (2012: 26.3 \%; 2013: 42.1 \%) and NT (2012: 24.2 \%; 2013: 38.3 \%), in both years. Additionally, differences between CT and the two irrigated treatments were found for leaf gas exchange rates during the seasons. A relationship between midday stem water potential and leaf gas exchange has been confirmed. Grouping of photosynthesis measurements according to midday stem water potentials led to statistically significant differences between groups. Photosynthesis started to decrease between -1 and -1.5 MPa. In conclusion, the results show that although both years have even been wetter than usual, the additional irrigation was highly beneficial for tree growth and had a positive effect on orchard establishment. This effect is supposed to be considerably higher in drier years.}, language = {en} } @phdthesis{Doerr2020, author = {D{\"o}rr, Oliver Sebastian}, title = {Influence of artificial sunlight from a microwave plasma lamp on morphology and secondary metabolism of horticultural plants}, volume = {2020}, edition = {1. Auflage}, publisher = {Hochschule Geisenheim}, address = {Geisenheim}, url = {http://nbn-resolving.de/urn:nbn:de:hebis:2083-122}, school = {Hochschule Geisenheim University}, pages = {158}, year = {2020}, abstract = {Light is one of the most important abiotic factors for plant physiological processes. In addition to light intensity, the spectral quality of light can also influence the plant morphology and the content of secondary metabolites. In the horticultural industry, artificial light is used in to enable year-round production of herbs, ornamental plants and vegetables in winter terms. Until today, discharge lamps like high-pressure sodium (HPS) lamps, emitting predominantly orange and red light and high amounts of infrared radiation, are the most common lamp systems in greenhouses. In the last decades, light-emitting diodes (LEDs) emerged as an efficient alternative light source. LEDs have the advantage of distinct adjustments to the light spectrum. For a usage in horticultural industry LEDs are often too expensive. Furthermore, reduced plant growth can occur due to incorrectly adjusted light spectra and lower leaf temperatures caused by the lack of infrared radiation. In a research project (LOEWE, funding no. 487/15-29) funded by the Hessen State Ministry of Higher Education, Research and Arts, Microwave plasma lamps (MPL) were tested as new light sources for horticultural industry and plant research. The electrodeless lamp systems emit light in similar properties like sun light. The aim of the study was to determine the influence of artificial sunlight of the MPL on the accumulation of secondary metabolites, plant architecture and plant physiology of three different species (coleus, basil and potted roses). The MPL was compared with other light systems such as commercial HPS lamps, LEDs or ceramic metal halide lamps (CDM). In addition to morphological parameters such as plant height, internode length or fresh and dry weight, the phenolic content of leaves grown under the respective light sources were examined. Overall an increased far-red light content in the emission spectra of the MPL showed high influence on the plant architecture which was observed in all three plant species. Artificial sunlight from MPL induced stem elongation in coleus and basil plants, compared to the other tested light sources. In potted roses a reduced branching degree was observed under MPL light compared to HPS grown plants. In addition to the impact of far-red light also the blue light content of the emission spectra was found to be a strong influencing factor for plant physiological processes. A positive correlation between blue light content and leaf thickness was determined in coleus cultivated under MPL, LED, HPS and CDM lamps. Low blue light content in HPS emission spectra resulted in shade-adapted leaves with low photosynthetic capacity and susceptibility to high irradiances. Blue light was assumed to increase phenolic metabolites in basil and rose leaves. Furthermore, the different light treatments resulted in an alteration of the composition of essential oils of basil. Experiments with coleus plants demonstrated that besides light color also the infrared radiation, had an influence on secondary metabolites by causing different leaf temperatures. Coleus plants grown with MPL showed the lowest content of phenolic compounds such as rosmarinic acid per dry weight. Infrared radiation resulted in a faster plant development indicated by increased biomass production and higher leaf formation rate as observed in coleus and basil plants. The results obtained in this study show that the influence of leaf temperature should always be considered when comparing different lamp systems. Especially when LEDs are compared to discharge lamps an overestimation of light color can be a consequence since also infrared radiation influences the content of phenolic compounds and plant growth.}, language = {en} } @phdthesis{Hessdoerfer2015, author = {Heßd{\"o}rfer, Daniel}, title = {Untersuchungen zur kontinuierlichen Wasserpotentialmessung sowei des Einflusses verschiedener Tropfbew{\"a}sserungssysteme auf die generative und vegetative Wuchsleistung von Vitis vinifera (cv. Silvaner)}, volume = {2015}, edition = {1. Auflage}, url = {http://nbn-resolving.de/urn:nbn:de:hebis:2083-117}, school = {Hochschule Geisenheim University}, pages = {XV, 144 S.}, year = {2015}, abstract = {In den Jahren 2011 und 2012 wurde im Versuchsfeld am „Th{\"u}ngersheimer Scharlachberg" des Sachgebietes Weinbaumanagement der Bayerischen Landesanstalt f{\"u}r Weinbau und Gartenbau bei der Rebsorte Silvaner kontinuierlich das Wasserpotential mittels temperaturkorrigierter In-situ-Psychrometer gemessen. Ziel der durchgef{\"u}hrten Arbeiten war es, die Wasserpotentialdynamik von Reben an ihrem nat{\"u}rlichen Standort und die Pflanzenreaktion auf wechselnde Witterungseinfl{\"u}sse zu untersuchen. Zus{\"a}tzlich wurde die Ver{\"a}nderung der hydraulischen Leitf{\"a}higkeit der Gesamtpflanze bei unterschiedlichem Evaporationsanspruch und Bodenwasserstatus betrachtet. Die kontinuierliche Wasserpotentialmessung an Reben wurde in den Versuchsjahren am Rebstamm und an traubentragenden einj{\"a}hrigen Trieben durchgef{\"u}hrt. Dabei konnte festgestellt werden, dass sich das Messgewebe des Triebes besser eignet, um das Wasserpotential {\"u}ber einen l{\"a}ngeren Zeitraum kontinuierlich mittels In-situ-Psychrometer an Reben zu ermitteln. Anhand der Tagesg{\"a}nge ließen sich deutliche Beziehungen zwischen der Wasserpotentialdynamik und den verschiedenen Witterungsfaktoren feststellen. So hatten die beiden Faktoren VPD und Temperatur den gr{\"o}ßten Einfluss auf das Stammwasserpotential der Reben. Dementgegen wurde zwischen der Globalstrahlung und dem Stammwasserpotential kein Zusammenhang ermittelt. Der engste kurvilineare Zusammenhang wurde jedoch zwischen dem VPD und dem Wasserpotentialgradienten, der treibenden Kraft f{\"u}r den Transpirationsstrom der Pflanze, ermittelt. Der Einfluss des Bodenwasserstatus auf die Stammwasserpotentialdynamik der Reben war relativ gering. Große Unterschiede im Wasserpotentialverlauf des Tages wurden durch eine Rebenbew{\"a}sserung induziert. Demnach f{\"u}hrte der verbesserte Wasserstatus zu einem reduzierten Potentialgradienten der bew{\"a}sserten Reben zur Aufrechterhaltung der Transpiration im Vergleich zu den nicht bew{\"a}sserten Reben. In den Jahren 2011 bis 2013 wurde Exaktversuch zur Pr{\"u}fung der Auswirkungen einer Rebenbew{\"a}sserung mit bestimmten Bew{\"a}sserungsschwellenwerten durchgef{\"u}hrt. Ziel dieses Feldversuchs war es, den Einfluss verschiedener Bew{\"a}sserungsmethoden und Bew{\"a}sserungsintensit{\"a}ten auf die generative und vegetative Wuchsleistung der Rebsorte Silvaner zu untersuchen. Das versuchstechnisch vorgegebene Bew{\"a}sserungsmanagement der Varianten moderate {\"U}berflurbew{\"a}sserung, intensive {\"U}berflurbew{\"a}sserung, moderate Unterflurbew{\"a}sserung und intensive Unterflurbew{\"a}sserung wurde mittels des fr{\"u}hmorgendlichen Wasserpotentials exakt gesteuert. Gleichzeitig wurde innerhalb des Versuchsfeldes der Verlauf der Bodenfeuchtigkeit innerhalb der Kontrollvariante mittels der FDR-Technologie gemessen. Zus{\"a}tzlich wurde nach der Lese von jeder Variante das C12 / C13 Stabilisotopenverh{\"a}ltnis, der δ13C-Wert, im Mostzucker ermittelt. Um den Einfluss der verschiedenen Bew{\"a}sserungsintensit{\"a}ten und -methoden auf die generative und vegetative Wuchsleistung zu untersuchen, wurden die erzielten Traubenertr{\"a}ge, Mostgewichte (°Oe), Mosts{\"a}uren und Schnittholzertr{\"a}ge bestimmt. Der Bew{\"a}sserungsversuch zeigte auf, dass eine Zusatzbew{\"a}sserung bei der Rebsorte Silvaner einen starken Einfluss auf das vegetative Wachstum aus{\"u}bte und kein signifikanter Einfluss auf die erzielten Traubenertr{\"a}ge festzustellen war.}, language = {de} } @phdthesis{Linck2019, author = {Linck, Holger}, title = {Diagnosis, Transmission, and Management of Phytoplasmas Infecting Rubus Species}, volume = {2019}, publisher = {Hochschule Geisenheim}, address = {Geisenheim}, url = {http://nbn-resolving.de/urn:nbn:de:hebis:2083-102}, school = {Hochschule Geisenheim University}, pages = {XII, 122}, year = {2019}, abstract = {Phytoplasmas ('Candidatus Phytoplasma') are plant-pathogenic bacteria that colonize the phloem of their host plants and can cause diseases in more than 700 plant species world-wide, including many economically important crops, ornamentals, and forest trees. They are spread by phloem-feeding insect vectors, vegetative propagation (grafting or production of cuttings), or plant parasitic dodder species of the genus Cuscuta. In Rubus species, phytoplasmas are associated with a disease referred to as Rubus stunt. Symptoms include stunting, witches' broom, small leaves, short internodes, enlarged sepals, phyllody, flower proliferation, and fruit malformations. As Rubus species are usually propagated vegetatively and the period of latency can be up to one year, the commercial production of planting material in plant nurseries can play a major role in the spread of Rubus stunt in addition to its only known insect vector, the leafhopper Macropsis fuscula. Furthermore, phytoplasmas usually occur in Rubus plants at concentrations too low for regular PCR to detect their DNA in plants and nested PCR is too time consuming for routine screening and prone to carry-over contamination. Hence, a fast, sensitive, and reliable molecular detection method for phytoplasmas in Rubus species is of major importance to stop the spread of this disease. Therefore, a multiplex TaqMan qPCR assay for the detection of Rubus stunt phytoplasmas was developed in this thesis, which provides an efficient tool for the screening of Rubus mother plants. This qPCR assay was subsequently used in a screening of putative insect vectors of Rubus stunt phytoplasmas in raspberry plantations in southern and northern Germany. A total of 4868 hemipteran insects were sorted, identified to family, genus, or species level and 597 DNA extracts, including pooled samples representing all identified insects, sampling locations, and sampling dates, were analyzed for phytoplasma DNA. With only seven sampled individuals of M. fuscula the occurrence of the only known vector for Rubus stunt phytoplasmas was low. DNA extracts from 18 samples were positive for phytoplasma DNA, among them species from the genera Euscelidius, Macrosteles, Euscelis, Anaceratagallia, and Psammotettix. Furthermore, the susceptibility of four raspberry cultivars to Rubus stunt after artificial graft inoculation was investigated. While graft inoculation was verified to be a practical tool for artificial phytoplasma inoculation in raspberries, assessing the disease severity of Rubus stunt proved to be difficult. All four raspberry cultivars used in this experiment ('Autumn Bliss', 'Glen Ample', 'Polka', and 'Tulameen') were successfully colonized by phytoplasmas. The efficacy of heat therapy with subsequent tissue culture to eliminate phytoplasmas from infected raspberry and blackberry plants was also evaluated. All previously infected raspberry and blackberry plants were tested negative for the presence of phytoplasma DNA after this procedure. Therefore, this method is suitable as an important step during the production of healthy mother plants and nuclear stock material in order to secure the production of healthy planting material. In conclusion, a fast and reliable molecular detection assay for routine diagnostics of phytoplasmas in Rubus species was developed and applied in experiments investigating putative insect vectors of Rubus stunt phytoplasmas, the susceptibility of different raspberry cultivars, and the efficacy of heat therapy coupled with tissue culture. The results of these trials can now be incorporated into disease management strategies for Rubus stunt.}, language = {en} } @phdthesis{BouNader2018, author = {Bou Nader, Khalil}, title = {Grapevine Age: Impact on Physiology and Berry and Wine Quality}, url = {http://nbn-resolving.de/urn:nbn:de:hebis:2083-88}, school = {Hochschule Geisenheim University}, year = {2018}, abstract = {Vine age and its relation to the quality of the wine are topics of recurring interest, both scientific and economic. Consumers and actors in the wine sector seem to agree on the ability of old vines to produce wines of superior character. Despite ongoing research, the validity of this point of view remains debated and questions about the mechanisms through which old vines would end up with superior quality wines remain numerous. To try to answer them, the impact vine age on physiology, tolerance to water stress, and berry and wine quality were studied in an experimental vineyard planted with Vitis vinifera L. cv. of identical genetic material (Riesling Gm 239 grafted on 5C Teleki) but planted in different years. In 2014 and 2015, the vines planted in 2012 had not yet reached their full potential and had a significantly lower vegetative productivity and yield than the vines planted in 1995 and 1971. Moreover, the vines planted in 2012 were not subjected to the same grass treatment as older vines during this period to prevent excessive competition during establishment. The lower capacity of these vines and the absence of cover crop led to greater exposure of clusters to light and greater nitrogen accumulation, which resulted in a higher concentration of amino acids, monoterpenes, norisoprenoids, and flavonols in 2014 and 2015. In the following years (2016 and 2017), the yield and pruning weight of these vines, as well as their berry composition, were comparable to those of the older vines. The parameters of technological maturity (° Brix, total acidity and must pH) were not significantly affected by vine age. Vines planted in 1995 and 1971 showed similar physiological characteristics throughout the study with the exception of a higher incidence of esca syndrome in the older group. This disease was responsible for the decline in the total yield of vines planted in 1971, but individual yield per vine was equivalent for both groups. Sensory and chemical analyzes were conducted in 2017 on wines from previous vintages. The wines of the youngest vines were associated with aromas of ripe fruit and the kerosene aroma that is typical of Riesling. These wines were also identified by higher concentrations of potential monoterpenes and norisoprenoids and volatile sulfur compounds in 2014 and 2015 only. The sensory and chemical profiles of wines from vineyards planted in 1995 and 1971 were dependent on the vintage but not on the age of the vines. The wine profiles produced in 2016 were overlapping for the three age groups. The works described in this thesis manuscript are unique, particularly because the vineyard in which they were conducted was designed specifically to study the effect of the age of the vine under comparable environmental conditions. Once the youngest vines reached their fruiting potential and were conducted in the same way as the older vines, their productivity, the composition of their berries and the quality of the wines they produce converged with those of the two other groups. More interestingly, vines aged 19 and 43 years behaved similarly throughout the study and resulted in wines comparable in terms of sensory analysis, which goes against the an idea that the older vines produce wines of a different profile. Previous studies have shown that the productivity of the vines, whatever their age, could be explained by the wood reserves and the size of the trunk. To have a better idea of differences linked to reserves, the structure-from-motion with multi-view stereo-photogrammetry (SfM-MVS) method was tested to measure trunk thickness and volume. The technique, which allows the creation of scaled, georeferenced 3D models based on photographs, was able to produce accurate models of field-grown grapevine trunks.}, language = {en} }