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Yeasts belonging to the genus of Hanseniaspora are widespread in nature and are generally part of the microbiome of ripe fruits, such as apples, pears and grapes. Hanseniaspora spp. form 50-75% of the microorganisms found at the onset of grape must fermentations, H. uvarum often being the most abundant. H. uvarum is also a common isolate from other fruits, such as oranges, pineapples, mangoes, apples and pears. Since H. uvarum, known for producing high amounts of acetic acid and ethyl acetate, dominates the onset of spontaneous grape must fermentations, it greatly influences the aroma profile of wines. Besides its important role in fermentations, more biotechnological research has been reported in recent years, highlighting the universal value of H. uvarum beyond the beverage industry.
In this thesis, I characterized the aroma-production profile of seven different Hanseniaspora spp. in simultaneous co-fermentations with Saccharomyces cerevisiae. Significant differences could be detected between fermentations using Hanseniaspora spp. belonging to the fast-evolving lineage (FEL) and the slow-evolving lineage (SEL). Fermentations with yeasts of FEL showed increased amounts of ethyl acetate, whereas yeasts belonging to SEL revealed no meaningful difference compared to the pure S. cerevisiae fermentation. Furthermore, co-fermentations resulted in lactic acid depletion (H. osmophila), extremely high isoamyl acetate levels (H. guilliermondii), reduction in glycerol (H. occidentalis), increased terpenols (H. opuntiae) as well as esterified terpenes (H. guilliermondii and H. uvarum). This is the first study to investigate the use of H. nectarophila and H. meyerii in relation to wine, of which fermentations using H. nectarophila revealed high levels of acetate esters.
Nitrogen sources in form of amino acids have a major impact on the resulting aroma-production profile of yeasts as they serve as backbones for several volatile organic compounds. I explored amino acid uptake preferences of Hanseniaspora spp. of both lineages (H. uvarum = FEL; H. osmophila = SEL), S. cerevisiae (all glucophilic), as well as the fructophilic yeasts Starmerella bacillaris and Zygosaccharomyces rouxii in synthetic must, spiked with single amino acids. Among yeasts investigated, H. uvarum showed the most rapid amino acid uptake. Additional research on yeast fermentations with synthetic must supplemented with an amino acid mix resulted in amino acid-dependent synthesis of specific aroma compounds by the respective yeast. This study reveals similarities in both preferences in amino acid uptake and nitrogen source depending aroma compound synthesis of H. osmophila and S. cerevisiae.
I investigated the transcriptomic profile of H. uvarum and S. cerevisiae to gain insight into the different regulation mechanisms involved in the synthesis of aroma compounds. Furthermore, I explored the impact of different levels of nitrogen (nitrogen deficiency/ diammonium hydrogen phosphate (DAHP) supplemented must) within the grape must on the gene expression profile and therefore on the resulting aroma profile. Even though the different nitrogen regimes did not significantly affect transcriptional levels, a major impact on both fermentation kinetics and the aroma profile could be monitored. H. uvarum unravelled possessing additional genes including alcohol acetyltransferase activity leading to a rapid esterification of higher alcohols to acetate esters. In addition, the lack of genes involved in the synthesis of higher alcohols and ethyl esters, as well as an up-regulation of genes responsible for the synthesis of acetyl-coA and acetate esters favour the high acetate ester production.
In this study, I developed the first genetic modification tool for H. uvarum by constructing a synthetic marker gene encoding the hygromycin marker under the control of a H. uvarum promoter, flanked by ~1 000 bp homology region to the target locus, enabling the knock-out of one copy of the alcohol acetyltransferase 1 (ATF1) gene. By increasing the concentration of the antibiotic during selection, I could identify a knock-out of both ATF1 alleles in the diploid yeast, generating a homozygotic atf1 mutant. Fermentations resulted in a significant reduction of the acetate ester synthesis, proving the function of ATF1 as an important gene involved in the ester synthesis in H. uvarum.
Genetic modification of H. uvarum was optimized by establishing a rapid PCR-based gene targeting approach for one-step gene replacement. Generation of two novel synthetic antibiotic resistance genes (pFA-hygXL and pFA-clnXL) provided resistance against hygromycin and nourseothricin, respectively. Short flanking-homology regions of 56-80 bp added to these selection markers via PCR enabled gene targeting and the deletion of both the H. uvarum LEU2 and LYS2 genes via two rounds of consecutive transformations, generating a leucine auxotrophic leu2/leu2 mutant and a lysine auxotrophic lys2/lys2 mutant, respectively. The genetic modification approach of H. uvarum using PCR-based gene targeting was further validated by targeted complementation of the auxotrophic leu2/leu2 strain.
A substantial area of the terrestrial surface is used for agricultural production. In Europe, many farmland species and ecosystems have evolved with traditional agricultural practices and rely on extensive cultivation for their survival. Today, agrobiodiversity is threatened by the abandonment of traditional agricultural land use.
The cultivation of wine is one of the oldest forms of agriculture. On steep slopes, viticulture has shaped landscapes, cultural traditions, and unique ecosystems in many regions. In Germany, steep slope viticulture has been declining dramatically in recent decades due to insufficient profitability. The abandonment of these traditional cultural landscapes threatens the cultural heritage and the flora and fauna adapted to viticultural management. One solution to halt the decline of steep slope viticulture could be a change of cultivation system from vertically oriented rows to modern terraced vineyards. Here, the rows run parallel to the hillside, facilitating cultivation, and thus reducing production costs. At the same time, a large portion of terraced vineyard consists of uncultivated embankments, which can provide valuable habitats within the agricultural system. However, little is known about the effects of a cultivation system change and vineyard abandonment on biodiversity. In addition, information on how to sustainably revegetate terrace embankments is missing.
Within the framework of this dissertation, the overall aim was to evaluate the potential of terraced vineyards to promote biodiversity and investigate measures for sustainable revegetation of terrace embankments. In addition, the effects of distinct vineyard management (vertically oriented vs. terraced) and vineyard abandonment on biodiversity were assessed. The main part of this thesis is based on a field study comparing three vineyard types (vertically oriented vineyard, terraced vineyard, abandoned vineyard) that were arranged in 15 triplets along the Upper Middle Rhine Valley (UMRV) in Germany. The effects of vineyard types, local vineyard parameters, and landscape structure on biodiversity were evaluated using four species groups. Studied groups represented plants and arthropod species (grasshoppers, wild bees, spiders). In a second field study, three newly constructed terrace embankments were revegetated using different seeding techniques and seed mixtures. In addition, measures to support plant establishment were evaluated. Plant establishment was assessed for three consecutive years in permanent vegetation plots.
The first study on the three vineyard types revealed that there was no uniform positive effect of one vineyard type on all investigated groups. Instead, the responses were group and taxon-specific and driven by management-related disturbance intensities, local vegetation structures, soil and landscape structure. In total, the heterogeneous landscape and small-structured vineyard agroecosystem of the UMRV supported high species diversity, hosted high numbers of rare and threatened species, and diverse species communities across vineyard types. Plant species richness was enhanced by vineyard management and particularly benefited from terraced vineyards and rather nutrient-poor and extensively managed embankments. In comparison, plant communities of fallows were completely different with lower plant diversity. Grasshoppers were supported by vineyard management, and bare ground in vineyard inter-rows supported heat- and open-adapted species. Taller vegetation stands on terrace embankments enhanced grasshopper species richness while woody structures and vineyard abandonment reduced grasshopper diversity and abundance at the local and landscape scale. Wild bee species richness and abundance were strongly determined by their nesting needs. For ground-nesting bees, the suitability of soils for nesting was important, irrespective of vineyard management types whereas above-ground nesting bees were enhanced by woody structures of fallows at the local and landscape scale. Moreover, fallows further provided valuable floral and non-floral resources for both ground- and above-ground nesting bees. For spiders, there was no difference in species richness and abundance between vineyard types but many xerophilic species adapted to open habitat structures prevailed in terraced vineyards. Vineyard fallows supported highly distinct spider communities, including some late-successional species. In conclusion, the vineyard cultural landscape of the UMRV with both actively managed and abandoned vineyards led to a high diversity of plant and arthropod communities. Hence, for its preservation, a spatially heterogeneous landscape comprising both (semi) natural and viticultural-management elements is important.
Results from the second study showed that terraced vineyards and especially terrace embankments can contribute to promoting biodiversity, especially if they are revegetated with regional seed mixtures. Seeds of locally adapted populations and hydro-seeding provided higher vegetation cover which is needed to prevent severe erosion whilst non-locally adapted standard seed mixtures and manual seeding had a higher failure risk and were more prone to severe precipitation events. Taken together, vineyard terracing appears to be a win-win solution for both winegrowers and biodiversity and thus helps to maintain viticulture on steep slopes.
Großprojekte der Verkehrsinfrastruktur sind komplex und beeinflussen Schutzgüter in hohem Maße; sie besitzen somit in aller Regel eine starke Relevanz für Ziele des Naturschutzes. Die Komplexität hat zur Folge, dass planerische Entscheidungen unter hohen Risiken und nicht dergestalt abgewogen werden, wie dies u.a. gemäß dem Gesetz über die Umweltverträglichkeitsprüfung (UVPG) erforderlich ist. Die vorliegende Dissertation geht der Frage nach, wie mit dieser Komplexität umgegangen werden kann, um den Erfolg der Vorhaben zu optimieren.
Historically and under cooler climate conditions, steep slope vineyards yielded best quality wines and highest reputation, due to their distinctive light microclimate, especially pronounced at the end of the ripening period. Today, German steep slope viticulture is facing major challenges. The cultivation of steep vineyard sites is costly. Compared to fully-mechanized vineyards, steep slope vineyards are labour-intensive and strenuous to manage, they produce less yield and are at higher risk of the adverse effects of a changing climate.
The modern vineyard terracing may be a viable alternative to the current cultivation method of downslope planted grapevines. The terrace platforms lead along the contour line of the hill and allow a higher degree of vineyard mechanization. The flat terrace platforms reduce surface runoff and allow for greater infiltration of precipitation, thus reducing or preventing runoff of the fertile vineyard soil and enhance the retention of precipitation in the soil.
In the present work, the effects of the transformation of vineyards planted downslope to modern vineyard terraces on microclimatic parameters, soil water dynamics and, finally, on the vegetative and generative performance of the grapevine were investigated. The experimental sites, comprising a vineyard planted downslope and a modern terrace, were selected with regard to their spatial proximity to one another and the comparability of the planting material with each other and monitored over a period of two to four years.
The change in the radiation distribution and the heat balance became apparent due to the inherent row orientation change by vineyard terracing, leading to an alteration of distinctive fruit quality parameters. The concentrations of polyphenols and amino acids in the berries were highly related to the amount of received solar radiation. Vineyard terraces were able to mitigate weather extremes. However, younger vines planted at the outer end of the terrace platform showed high drought stress responses across all experimental years. However, this lessened as the vine age progressed.
The modern terracing of steep slope vineyards proved to be an appropriate tool for high-quality grape production. Additionally, the potential for promoting biodiversity through a sustainable management of the terrace embankments complements the overall positive findings of the present work. In the near future, the challenge to increase the competitiveness of young vines grown at steep slope vineyards to accompanying plants needs to be solved by means of viticultural, technical or breeding measures.
Brettanomyces infections represent one of the major red wine quality spoilers affecting the industry worldwide and will most likely continue to be so in the years to come. When attempting to correct or “cure” a Brettanomyces tainted wine, the most problematic metabolites to be removed are volatile phenols, particularly 4-ethylphenol.
Molecular imprinting represents one of the technologies which promise to bridge the gap between the precision and selectivity of chemical analytical methods for investigating liquid matrices, and that of industrial filtration and separation technologies currently in use.
In this work, the removal of 4-ethylphenol from wine with the aid of molecularly imprinted polymers was studied. Overall, the materials investigated in this work show promise when investigated in lab-scale conditions with model solutions. They can be effective in treating wine if the treatment conditions are appropriate and involve multiple regeneration steps.
In the context of climate change, crop adaptation is of major interest. Adaptation can be achieved by modifying cultural practices, field management, or plant material. In grafted plants, the plant material can be improved by the scion or the rootstock. The rootstock comprises the anchorage and the nutrient and water absorption as well as hormone signaling, which are closely involved in plant adaptation to its environment. Moreover, the interactions between the scion and the rootstock provides a broad range regarding adaptation strategies to different growing conditions and production aims. In vineyards, the most commonly rootstocks are hybrid breeds between American Vitis species (V. berlandieri, V. riparia, and V. rupestris) and sometimes V. vinifera. Despite recent findings revealing a large genetic diversity in these genetic backgrounds, rootstocks remain poorly studied, especially at the genetic level. The V. berlandieri hybrids have shown good performances in water deficit and limestone tolerance in vineyards.
A selection of 286 V. berlandieri genotypes were chosen from a field-grown population of plants obtained from seedlings at Hochschule Geisenheim University, Germany. The samples were analysed regarding their genetic structure, which revealed two subpopulations and an association between the climatic conditions of the sampling areas and their genetic variability. While an isolation by distance has been highlighted, it was not possible to detect the variability in the genetic burden of the two subpopulations.
This population was used for grafting of V. vinifera cv. Riesling (clone 24-209Gm), which was planted in pots and grown in the greenhouse fortwo consecutive years with no limiting conditions. A root phenotyping has been carried out after one year of growing, revealing a high variability at the phenotype and genetic level. The heritability was high for these traits which allowed to carry out a genome wide association study and to detect eleven genetic markers associated with root-related traits.
Each year, the population was planted in a field experiment in order to observe the variability of conferred traits induced by the rootstock to the scion. A medium to high variability has
been detected for the pruning weight and the δ13C as well as a medium to high heritability. A genome wide association study has allowed us to detect two significant markers for δ13C but no markers were highlighted for the pruning weight.
Correlations between root-related and scion conferred traits have been found. A comparison of the phenotypical performance of the V. berlandieri genotypes to commercial rootstocks, i.e. SO4, 110R, Börner and 5BB, resulted in interesting insights for the selection of futuregenotypes for rootstock breeding. This association study is the first carried out in a natural population of a wild Vitis monospecies and highlights new opportunities for grapevine rootstocks breeding.
Climate change cannot currently be ignored and impacts all fields of agriculture. IPCC reports forecast an increase of up to 700 ppm of atmospheric carbon dioxide concentration at the end of the 21st century. Parameters such as elevated global temperature, reduced precipitations in certain areas of the world and increase of atmospheric carbon dioxide concentration are modifying plants’ environment. Grapevine, which is a crop of economic and cultural importance, is very sensitive to climate modifications. The effects of temperature or water stress on grapevine has been widely investigated, and elevated carbon dioxide has been mainly studied in enclosed systems such as greenhouses. However, the impact of increased concentration of carbon dioxide on plants in open-field experiments remains scarcely studied because of the technical challenge that it represents. In this context, the aim of this PhD work was to investigate the impact of elevated carbon dioxide concentration using the set-up VineyardFACE located at Geisenheim University. This open field set-up enables to apply a moderate and gradual increase (+20%) of ambient carbon dioxide concentration on two grapevine cultivars, Riesling, and Cabernet Sauvignon. While knowing the impact of elevated carbon dioxide treatment on leaf physiology and vegetative growth from previous studies (Wohlfahrt et al., 2018), as well as on berry composition during the early years of fumigation, the goal of this study was to determine the effects of elevated carbon dioxide treatment on agronomical traits, primary metabolites (sugars, organic acids, amino acids) and secondary metabolites (anthocyanins, terpenes) on vines undergoing six years of fumigation, as well as monitoring berry development and following berry ripening for successive seasons. Intermediates from central metabolism were also studied for two years (2020 and 2021), and terpene analysis was realized on Riesling must 2021.
Our results showed that although photosynthesis was still enhanced, little effects were found of elevated carbon dioxide treatment on primary metabolites as well as on berry ripening rates, for successive seasons for both Riesling and Cabernet Sauvignon. However, a trend of reduced total anthocyanins concentration in Cabernet Sauvignon was demonstrated by elevated carbon dioxide treatment mainly in 2020, while anthocyanins composition remained fairly similar. Terpenes (both bound and free) composition in Riesling in 2021 was not impacted by elevated carbon dioxide treatment.
In this doctoral thesis, the effects of moderately reduced water supply and seasonal variations was studied regarding the chemical and nutritionally relevant composition of the edible harvest organs of three different vegetable crops, i.e. cucumber fruit (Cucumis sativus L.), radish roots (Raphanus sativus L. var. sativus), and spinach leaves (Spinacia oleracea L.). The study was conducted to demonstrate putative plant-physiological alterations in their chemical composition that may be evoked by moderate water deficits during cultivation under open field conditions. The vegetable crops were selected according to differing harvest organs (leaves, roots and fruit), being cultivated during three consecutive years under open field conditions and two different water supply treatments within a randomized block design with multiple sets of six plots each. Depending on the vegetable, the provided water amount of the moderately reduced water supply treatment varied between 80-97% of the well-watered control treatment. Chapter 1 dealt with the effects of moderate water reduction of 3-20% on radish. Including one cultivation set per year and an additional set in 2016, i.e. a total of four separate sets, a dry matter-based increase of myo-inositol was observed, whereas the levels of selected minerals and trace elements like iron and manganese as well as those of phenolic compounds and glucosinolates decreased or remained unchanged upon moderately reduced water supply. Only insignificant effects of reduced water supply were seen on the levels of acylated anthocyanins, which represent a highly important commercial quality trait due to their importance for the roots’ or hypocotyls’ color. In contrast, the levels of fresh matter-related analytes were mainly enhanced by reduced water supply due to higher contents of dry matter. Thus, the overall quality of radish tubers seemed to be only marginally affected by moderate water limitation.
Similar results were observed for spinach as presented in Chapter 2. Nevertheless, reducing the total water amount by only 4-10% during cultivation led to various significant alterations in the chemical composition of the leaves. Similar to radish, higher dry matter-based levels of myo-inositol were found in spinach grown under low water reduction. Moreover, increased contents of zinc and manganese were found, while the levels of malic acid, fumaric acid, phosphate and chloride decreased upon slight water reduction in spinach dry matter. In contrast, spinach fresh matter was expectedly characterized by significantly higher contents of polyols, ascorbic acid, potassium, nitrogen, phosphorous, zinc and manganese, as well as total flavonoids and carotenoids, including nutritionally highly relevant compounds like the provitamin A-active β-carotene and the macular pigment lutein. Noteworthy, strong seasonal variations have been observed for numerous minor phytochemicals, such as for example for a series of specific flavonoids, whose contents seemed to be dependent on the respective irradiation conditions of the cultivation set.
In contrast to radish and spinach, cucumber from open field cultivation reacted differently to slightly reduced water supply, as summarized in Chapter 3. When cucumber fruits obtained from plants received 85-90% of the total water amount of the control treatment, they exhibited significantly higher levels of malic acid, calcium, and magnesium, while those of phosphate, phosphorous, nitrogen, and iron decreased based on dry matter. Fruit dry matter-content did not significantly change due to moderate water restriction, and, as a result, the concentration of most analytes tended to decrease in the cucumber fresh matter when grown under reduced water supply. The chemical analyses of single cucumber fruit compartments (exocarp, mesocarp and endocarp) from fruits grown under 60% of the full supply in a separate greenhouse experiment confirmed that malic acid, certain minerals and trace elements, as well as carotenoids like the most abundant lutein were relatively sensitive to moderate water reduction.
Altogether, a moderately reduced water supply was shown to significantly alter the chemical composition of the aforementioned vegetable crops. Considering the broad range of analytes from, e.g., minerals and anions to polyols and acids to micronutrients like provitamin A, it became clear that water supply reduction as studied herein did not lead to generalizable effects such as an undesired decrease or a desired enhancement of valuable compounds. For instance, the levels of selected health-promoting constituents in the fresh matter of radish and spinach were increased, while those of the same compounds contained in cucumber did not benefit at all. Generally, the overall quality of vegetables was clearly shown to be influenced not only by water supply, but also by the interaction with other abiotic factors, especially when cultivation took place in open field. Further study in the future should target interactions of moderately reduced water supply situations with changes in other abiotic factors, such as elevated CO2 concentrations.
Physiological storage disorders cause significant economic losses in a number of commercially important pome fruit varieties worldwide. Under the same storage conditions with the same cultivar, the incidence and frequency of disorders may vary in different years in a manner that must be explained by an interaction of pre-harvest and post-harvest factors. Major factors known to influence disorder incidence include annual weather pattern, management in the orchard, such as leaf-fruit ratio, calcium content of the fruit, harvest date and storage conditions. So far, the occurrence of the disorders cannot be predicted with certainty, and thus to adapt the management in the orchard or in the storage facility accordingly. Analysis of large amounts of data using Artificial Intelligence (AI) offers new opportunities to link large data sets into a meaningful context. The aim of the present work is the small-scale and non-destructive monitoring of fruit development in orchards under the above mentioned management practices. AI prediction models were created for the cultivar 'Braeburn'. 'Braeburn' is most susceptible to physiological storage disorders which cause browning in the fruit tissue below the skin. With tent-like constructions over the fruit trees, in which the temperature was controlled during two fruit physiologically important periods (petal drop to T-stage, three weeks before harvest), the temperature influence on disorder incidence was investigated. To the best of our knowledge, this was the first time that different temperature profiles could be generated in the orchard for mature 'Braeburn' trees. Thereby a positive influence on the reduction of internal browning caused by warm night temperatures (>10°C) before harvest was observed. Overall, each trial year showed different occurrences of physiological disorders. Orchard management and weather conditions resulted in significantly different fruit growth patterns and optical non-destructive point spectroscopy. The bi-weekly spectroscopy measurements on the same fruit and subsequent use in Partial Least Square Regression (PLSR) models were tested for their informative value. Additionally, the future fruit state was predicted in models based on weather data. The statistical evaluation of three years of data showed that the number of destructive soluble solids content (SSC) samples required to be collected each year for the {PLSR} models with an acceptable error rate was 100. These samples in particular needed to include the range of low and high SSC values. An unbalanced laboratory error of 0.1-1.0 °Brix had no influence on the modeled SSC values. Compared to destructive SSC determination in the laboratory, SSC could be non-destructively determined with an average deviation of 0.5 °Brix. Field measurements after a rain event had no influence on visible spectral indices. However, orchard covers such as rain protection over the fruit trees led to lower water absorption values at 975 nm. The separation of data on a tree-sector level in this work was performed manually, but initial steps were taken to display fruit growth and spectroscopy data via GPS signal location within a map. The acquisition of small-scale data at the tree-sector level revealed significant differences for SSC, chlorophyll and anthocyanin indices as well as significant differences in the incidence of physiological disorders. In future research and modeling approaches the tree sector information should be taken into account, even if this is not yet feasible to implement in a completely automated system under the given circumstances. The prediction models for the development of physiological disorders (core browning, cavities) were able to predict with two years of data the development of the disorders in the storage and the fruit flesh firmness at harvest 90 % correctly. Further research using non-destructive fruit measurements in orchards and the influence of weather conditions will provide further insights into apple quality improvement.
Im Rahmen dieser Arbeit wurde ein Modell zur Kosten- und Margenanalyse deutscher Weingüter entwickelt und angewendet, mit dem die Kosten- und Margenstrukturen deutscher Weingüter systematisch und umfassend sowie auf der Grundlage empirischer Betriebsdaten bis auf die Ebene der einzelnen Kostenträger (Weine) und Absatzsegmente (Kundengruppen) der Weingüter analysiert wurden. Aus der Sicht der Forschung schließt diese Arbeit eine Forschungslücke, denn die Kosten- und Margenstrukturen sowie die wesentlichen Kostentreiber deutscher Weingüter wurden in dieser Arbeit erstmals betriebsübergreifend auf der Ebene differenzierter Kostenträger (Weine) und Absatzsegmente (Kundengruppen) sowie auf der Grundlage empirischer Betriebsdaten mit wissenschaftlichen Methoden analysiert. Den untersuchten Weingütern wurden die Analysen auf einzelbetrieblicher Ebene zur Verfügung gestellt. Damit erhalten die Weingüter Informationen über die Höhe und die Zusammensetzung der Herstellungskosten ihrer einzelnen Weine, über die Vertriebskosten sowie über die Margen der Weine unter Berücksichtigung der verschiedenen Absatzsegmente. Für die Weingüter wird dadurch ersichtlich, welche Weine und welche Absatzsegmente zum betrieblichen Erfolg beitragen und in welchen Bereichen Handlungsbedarf besteht.
Basierend auf der Wertschöpfungskette der Weinproduktion und -vermarktung wurden dazu zunächst die Betriebsbereiche der Weingüter voneinander abgegrenzt und es wurden spezielle Anforderungen dieser Betriebsbereiche an die Entwicklung und Umsetzung des KMA-Modells für Weingüter definiert. Aufbauend auf diesen Anforderungen wurde ein Grundkonzept des standardisiert anwendbaren KMA-Modells entwickelt und vorgestellt.
Das KMA-Modell umfasst einerseits einen Input-Bereich, in den die betriebsspezifischen Aufwendungen der Gewinn- und Verlustrechnung sowie das betriebsspezifische Anlagevermögen der Weingüter übernommen werden. Darüber hinaus erforderliche Daten zur Kosten- und Margenanalyse werden über ein betriebsspezifisches Erhebungsblatt (eine MS Excel Tabelle) auf einzelbetrieblicher Ebene erfasst und in das KMA-Modell als Input überführt. Im Bereich der Berechnungen werden zunächst neutrale Aufwendungen abgegrenzt und die Kostenarten der Weingüter werden auf der Grundlage der Input-Daten ermittelt. Die Kostenarten werden dabei über mehrere Ebenen nach den Betriebsbereichen Weinbau, Kellerwirtschaft, Verwaltung, Vertrieb und Sonstiges untergliedert. Das Ergebnis der Kostenartenrechnung sind pagatorische (aufwandsgleiche) und wertmäßige (kalkulatorische) Kosten von Weingütern, denen spezifische Ressourcen zur verursachungsgerechten Kostenverrechnung zugeordnet werden.
Der Kern des KMA-Modells ist die verursachungsgerechte Kostenverrechnung der Teilbereiche Weinbau, Kellerwirtschaft, Verwaltung, Vertrieb und Sonstiges. In den Bereichen Weinbau und Kellerwirtschaft werden im Rahmen der Verrechnungen zunächst Kostenträger-Einzelkosten auf die Kostenträger (Weine) zugeordnet. Im Bereich Weinbau sind dies i.W. Pacht- und Pachtbewirtschaftungskosten für bestimmte Weinberge, Kapitalkosten für den Grund und Boden der Weinberge sowie Abschreibungen und Kapitalkosten für die Rebanlagen der Weinberge, welche nach verschiedenen Bewirtschaftungs- und Erziehungsformen differenziert verrechnet werden. Als kellerwirtschaftliche Kostenträger-Einzelkosten werden insb. Kosten für den Zukauf von Trauben, Most und/oder Fasswein, Kosten für die Flaschenausstattung (Kosten für die Flasche, den Verschluss, das Etikett, ggf. eine Zusatzausstattung und die Verpackung) sowie Kapitalkosten für das in den produzierten Weinen gebundene Kapital bis zum Verkauf der Weine verrechnet. Im darauffolgenden Schritt werden die Kostenträger-Gemeinkosten über ressourcenspezifische Kostentreiber aufgespalten und nach Prozessen sowie Aktivitäten verrechnet. Im Bereich Weinbau werden diese Verrechnungen nach Bewirtschaftungs- und Erziehungsformen und im Bereich Kellerwirtschaft nach Gebindearten und -größen während des Weinausbaus der Kostenträger (Weine) differenziert. Bei den Verrechnungen über die Prozesse und Aktivitäten wird eine Vielzahl an Kostentreibern angewendet, damit modellseitig eine möglichst verursachungsgerechte Kostenverrechnung sichergestellt wird. Im Bereich Weinbau sind dies bspw. die Arbeitskraftstunden je ha je Aktivität sowie die Maschinenstunden je ha je Aktivität in Abhängigkeit unterschiedlicher Bewirtschaftungs- und Erziehungsformen der Weinberge, die zur Erzeugung bestimmter Weine verwendet werden. Als Kostentreiber des Betriebsbereichs Kellerwirtschaft werden modellseitig i.W. die Kostentreiber Arbeitskraftstunden je 1.000 l je Aktivität sowie die benötigten Maschinenstunden je 1.000 l je Aktivität in Abhängigkeit unterschiedlicher Gebindearten und -größen während des Ausbaus der Weine angewendet. Bestimmte Kostenarten der Betriebsbereiche Weinbau und Kellerwirtschaft werden vereinfacht über sonstige Verrechnungen auf die Kostenträger (Weine) geschlüsselt. Auch für die Kostenverrechnungen des Betriebsbereichs Vertrieb werden ressourcenspezifische Kostentreiber zur verursachungsgerechten Schlüsselung der Vertriebskosten auf die Absatzsegmente des KMA-Modells angewendet. Dies sind u.a. erbrachte Arbeitskraftstunden der Arbeitskräfte je Absatzsegment zur Schlüsselung der Personalvertriebskosten, verschiedene Versandarten und -mengen zur Schlüsselung der Versandkosten sowie flächenmäßige Anteile der Nutzung von Gebäuden für vertriebliche Zwecke zur Schlüsselung von Gebäudekosten. Anschließend werden die Kosten der Absatzsegmente auf die Kostenträger (Weine) verrechnet, die über die jeweiligen Absatzsegmente verkauft werden. Die Kosten der Betriebsbereiche Verwaltung und Sonstiges werden vereinfacht über sonstige Verrechnungen auf die Kostenträger (Weine) geschlüsselt. Der letzte Berechnungsschritt des KMA-Modells ist die Margenkalkulation der Kostenträger (Weine) nach den Absatzsegmenten (Kundengruppen) des KMA-Modells. Dabei werden die Kostenträger-Selbststückkosten der Weine unter Berücksichtigung der Absatzsegmente von den Verkaufspreisen der Kostenträger (Weine) je Absatzsegment subtrahiert.
Die Anwendung des KMA-Modells in 22 deutschen Weingütern zeigt, dass Personalkosten (33 %), Materialkosten (23 %) und Kapitalkosten (20 %) in der Summe 76 % der Gesamtkosten im Mittel der untersuchten Weingüter ausmachen. Auf der Ebene der Betriebsbereiche (Kostenstellen) entfallen im Mittel der untersuchten Weingüter zwei Drittel der Gesamtkosten auf die Betriebsbereiche Weinbau (37 %) und Kellerwirtschaft (30 %). 20 % der Gesamtkosten entfallen auf weinbauliche Prozesse und Aktivitäten sowie 14 % der Gesamtkosten auf kellerwirtschaftliche Prozesse und Aktivitäten.
Die Höhe der Prozesskosten je ha im Betriebsbereich Weinbau hängt wesentlich von den unterschiedlichen Bewirtschaftungs- und Erziehungsformen ab, in denen die Weine erzeugt werden. Wesentliche Treiber für die Unterschiede der weinbaulichen Prozesskosten je ha zwischen den Bewirtschaftungs- und Erziehungsformen sind die Prozesse Rebschnitt, Pflanzenschutz, Begrünungsmanagement und Traubenlese. Je Liter betrachtet wirkt sich der Hektarertrag der Weine wesentlich auf die weinbaulichen Prozesskosten der Weine aus, denn die empirischen Untersuchungen dieser Arbeit ergeben, dass die weinbaulichen Prozesskosten der untersuchten Weine bei einer Steigerung des Hektarertrags um 1.000 l / ha um rd. 0,30 € / l abnehmen.
Kellerwirtschaftliche Prozesskosten entfallen im Mittel der untersuchten Weingüter größtenteils auf die Verarbeitungsstufe „Mostverarbeitung und Ausbau zum Jungwein“. Die empirischen Untersuchungen zeigen, dass die kellerwirtschaftlichen Prozesskosten der Weine, welche in Barriquefässern ausgebaut werden, um rd. 2,34 € / l signifikant höher ausfallen, als die kellerwirtschaftlichen Prozesskosten der Weine, welche in Edelstahltanks ausgebaut werden. Darüber hinaus hat die durchschnittliche Gebindegröße der Gebinde, in denen die Weine ausgebaut werden, einen signifikanten Einfluss auf die Höhe der kellerwirtschaftlichen Prozesskosten der Weine. Aus den Untersuchungen geht hervor, dass die kellerwirtschaftlichen Prozesskosten der untersuchten Weine bei einer Erhöhung der durchschnittlichen Gebindegröße während des Weinausbaus um 1.000 l je Gebinde um 0,10 € / l abnehmen.
Die Höhe und die Zusammensetzung der Vertriebskosten der untersuchten Weingüter hängt wesentlich von den Absatzsegmenten ab, über welche die Weine verkauft werden. Die Vertriebskosten der Absatzsegmente Privatkunden und Gastronomiekunden liegen im Mittel der Weingüter mit 1,67 € / Fl. bzw. 0,92 € / Fl. über den Vertriebskosten der übrigen Absatzsegmente. Die Unterschiede der Vertriebskosten zwischen den Absatzsegmenten ergeben sich i.W. aus dem variierenden Einsatz von Personal, Werbe- und Versandmaßnahmen sowie Gebäuden in Abhängigkeit der Absatzsegmente.
Im Rahmen der Arbeit wurden insgesamt 686 Kostenträger (Weine) mit dem KMA-Modell ausgewertet. Deskriptiv betrachtet zeigt sich dabei, dass relativ hochpreisige Weine im Vergleich zu relativ niedrigpreisigen Weinen im Mittel der untersuchten Weingüter i.d.R. höhere Herstellungs- und Selbstkosten aufweisen. Trotz der höheren Herstellungs- und Selbstkosten erzielen die relativ hochpreisigen Weine im Vergleich zu den relativ niedrigpreisigen Weinen in der Tendenz (deskriptiv betrachtet) allerdings höhere Margen je Liter sowie höhere prozentuale Margen auf Selbstkosten. Vor diesem Hintergrund wurden die Steigerungen der prozentualen Margen der Weine in Abhängigkeit der Verkaufspreise der Weine unter Berücksichtigung der unterschiedlichen Absatzsegmente detailliert in einem Regressionsmodell untersucht. Aus den Untersuchungen mit diesem Regressionsmodell geht hervor, dass die untersuchten Weine bei einem Verkauf über die Absatzsegmente Privatkunden und Gastronomiekunden mit einer Steigerung des Verkaufspreises um einen € je Liter um rd. 3,2 % höhere Margen erzielen. Etwas geringer fällt die Steigerung der Margen der Weine in Abhängigkeit der Verkaufspreise in den Absatzsegmenten Fachhandelskunden und Großhandelskunden aus, denn mit einer Steigerung des Verkaufspreises um einen € je Liter steigen die Margen der Weine im Vergleich zu den Absatzsegmenten Privatkunden und Gastronomiekunden nur um rd. 2,3 % bzw. 2,6 %. Die Margen der Weine mit einem Referenzpreis von 2 bis < 4 € / l liegen bei einem Verkauf über die Absatzsegmente Privat-, Gastronomie-, Fachhandels- und Großhandelskunden zwischen - 4 % und 2 %. Zusammenfassend und überbetrieblich bleibt deshalb festzuhalten, dass Weine der untersuchten Weingüter mit einem Referenzpreis von 2 bis < 4 € / l sowie darunter kaum vollkostendeckend sowie mit positiven Margen verkauft werden können.
Interpersonal ties influencing strategic decisions regarding inter-firm partnerships
The agri-food industries changed from vertically integrated supply chains towards vertical cooperating networks. In this context, inter-firm partnerships are seen as a possible tool to address changing markets and competition. Within strategic management, inter-firm partnerships are valued as a potential source of competitive advantage, which ascribes importance to the strategic management of partnerships. In the underlying classical cooperation theory, business cooperation decisions are assumed to be made rationally. Initial empirical studies show that managers have a personal influence on strategic decisions in business cooperation and that their decisions are not always in line with the common rationality assumptions in economics. Preliminary studies show initial "softer" or even "non-economic" interpersonal factors such as heuristics, biases, emotions, personality traits, or norms that can mitigate rationality and impact decisions in strategic collaborations made by managers. Human agents and their influence on strategic relationship management and intrafirm-, interfirm- and network-level outcomes are put into the research center of this study. Specifically, this thesis aims to explore whether managers (can) take an individual influence on strategic decision-making in B2B cooperation relations. Furthermore, it aims to analyze and identify which personal characteristics factors play a role during the decision-making process regarding inter-firm partnerships in the agri-food industry.
First empirical studies have evidenced that interaction – or in other words, the influence of managers – is a critical process in developing strategic buyer-seller relationships in B2B relations. I have argued that personal characteristics exist, and they influence decisions in inter-firm cooperation. An additional level, namely the personal-level, has to be explicitly included in the strategic chain management framework. Four general research expectations on which personal characteristics influence decision-making in inter-firm partnerships were derived.
As a consequence of the currently limited literature base I conducted two exploratory and qualitative studies in the form of expert interviews to first identify and prioritize the most critical driving personal influences on mangers in the German wine industry. Together, these two studies served as the basis for developing the research expectations and the main study in the form of factorial surveys. The study's statistical population size includes all companies that engage in grape-buying relationships (in Germany) to produce wine commercially (roughly 9,000 firms). The sample size based on the number of respondents is 203, but based on the judgments, the sample size is 602 judgments, as each respondent judged several items. After a descriptive statistical analysis, the Partial Least Squares (PLS) technique, in particular the multi-group analysis was used to evaluate the results.
The most important finding is that managers’ personal characteristics influence strategic decisions in chain management, particularly on mechanisms to manage cooperation. Furthermore, in this study, the characteristics of fairness, escalation of commitment, overconfidence, and representation heuristic significantly impacted some of the power and trust statements. Thus, focal firms have to consider and develop appropriate mechanisms to address and manage personal influences. Secondly, it was shown that various personal characteristics influence chain management decisions simultaneously and with different intensities in a positive or negative manner.
The present dissertation addresses logistics challenges in grocery retailing considered in an omni-channel context. Omni-channel retailing gains in importance as online grocery retailing is continuously growing. Besides pure online retailers, traditional bricks-and-mortar retailers are entering the online market. The development of existing structures towards an omni-channel retailing represents a complex challenge. The first contribution of the dissertation analyzes omni-channel distribution concepts for traditional bricks-and-mortar grocery retailers. A multiple-case study with European grocery retailers serves as the basis for the analysis. Since different concepts dominate in the countries, their respective advantages and differences are elaborated. The focus of this research are the central components of a distribution network design, which are the assortment range, the picking system and the last-mile delivery, in terms of delivery mode and time.
In addition to the growing online business, controlling of logistics processes due to volatile demand is a complex task in grocery retailing. Public holidays are a recurring issue in grocery logistics, which is discussed in the second contribution. The ban on working on holidays in Germany means that grocery retailers have less time to perform the logistics processes. In addition, there is usually a higher weekly volume to manage than in standard weeks. Although holiday weeks are prepared in detail, many challenges have to be met on an ad hoc basis. Consequently, the focus of the analysis of holiday issues is on the operational planning areas of demand planning and disposition, warehouse management and transport management. The results of the second contribution provide potential measures for efficiently and effectively controlling the planning areas considered around public holidays.
The third issue considers the challenge of the Covid-19 pandemic for the German grocery retailing. In contrast to the public holiday challenge, the outbreak of the pandemic led to unexpected demand peaks and uncertainties. Using an exploratory research approach, the impact of the Covid-19 pandemic on the planning and execution areas of demand planning and order dispatching, store management, transport management, warehouse management and procurement is highlighted. Based on a two year review, trends for the German grocery retailing are identified. The findings show in which direction logistics processes might be further developed in order to meet the potential future requirements.
The cumulative dissertation includes the three studies described, which contribute to the qualitative research of omni-channel retail logistics. Current challenges of the grocery retail industry are examined from a European, especially a German perspective. The exploratively generated results provide courses of action for volatile and disruptive times as well as possible development directions for grocery retailers.
In wettbewerbsintensiven Branchen ist eine strategisch wirksame Außendarstellung ein unverzichtbarer Teil der Unternehmenskommunikation geworden. Architektur hat sich bereits als Instrument der Unternehmenskommunikation etabliert. Landschaftsarchitektur scheint hingegen unterrepräsentiert zu sein. Die vorliegende Studie untersucht deshalb die Einbindung von Landschaftsarchitektur und Gebäudebegrünung als Element der Unternehmenskommunikation in der Weinbranche. Erarbeitet wurden mögliche Beiträge für eine identitätsgerechte Außendarstellung auf der Basis einer strategischen Unternehmenskommunikation, in der die „Landschaftsarchitektur“ als Teil der Corporate Identity verortet wurde. Die für die Arbeit erforderlichen Freiräume am Unternehmensstandort wurden definiert. Erkenntnisse aus der Umweltpsychologie im Hinblick auf eine relevante Mensch-Umwelt-Beziehung flossen ein. Vor diesem Hintergrund wurde die Landschaftsarchitektur als ein mögliches strategisches Kommunikationsinstrument identifiziert. Im Rahmen der Direktvermarktung wurde die Bedeutung einer entsprechenden Gestaltung der Weingüter aufgezeigt, die ein unverzichtbarer Teil der Außendarstellung ist. Drei Hypothesen wurden aufgestellt: (1) Von Weingütern in Deutschland, die Architektur als Instrument der externen Kommunikation einsetzen, nutzt nur ein kleiner Anteil Landschaftsarchitektur und Gebäudebegrünung als Instrument der externen Kommunikation. (2) Für Weingüter haben die Landschaftsarchitektur/Gebäudebegrünung und ihre Intensität Einfluss auf die von Weinkonsumenten wahrgenommene Attraktivität. (3) Die Ausgestaltung der Landschaftsarchitektur/Gebäudebegrünung hat Einfluss auf Assoziationen hinsichtlich strategischer Merkmale von Weingütern. Entwickelt wurde eine Methodik, die es erlaubte, die aktuelle Rolle von landschaftsarchitektonischer Gestaltung bei Weingütern und deren Einbindung in die Unternehmenskommunikation zu analysieren. Auf Basis dieser Ergebnisse wurde ein Modell „Weingut mit Innenhof“ und „Umfeld“ entwickelt, das die Grundlage für eine Konsumentenbefragung bildete. 598 Probanden wurden in einem strukturierten Interview befragt und ihre Präferenzen und Assoziationen in Bezug auf Begrünungstypen und -intensitäten analysiert. Ein Zusammenhang zwischen Begrünung und strategischen Ausrichtungen wie Kundenfreundlichkeit, hohem Preisniveau, hoher Qualität, ökologischer Produktion und Handwerklichkeit wurde untersucht. Die Ergebnisse zeigen, dass eine landschaftsarchitektonische Gestaltung insbesondere in Hinblick auf die Begrünung bei der Außendarstellung deutscher Weingüter unterrepräsentiert ist. Die Einbindung von Landschaftsarchitektur und Gebäudebegrünung kann wesentlich zu einer attraktiveren Außendarstellung beitragen, insbesondere im Hinblick auf das Nachhaltigkeitsprofil. Die Begrünungsintensität spielt dabei eine maßgebende Rolle.
Fresh fruit and vegetable branding: Investigating consumer behavior with visual and mixed methods
(2022)
This dissertation addresses two different but connected aspects of consumer research in the horticultural sector: the first pertains to the empirical level regarding consumer behavior toward branded fresh fruit and vegetables and the second to the methodological level regarding the visual method of using photos in the research process, which aids in studying the visual side of consumer behavior toward branded fresh produce.
Branding is a key tool for marketing food products that benefits both producers and consumers. Moreover, brands play a crucial role in the purchase process of processed food. However, fresh fruit and vegetables are mostly sold without branding. This affects consumer behavior, as do the horticultural market structure (which is marked by strong competition), interchangeability of products, and sensitive and low prices. Many studies have investigated consumer behavior toward branded processed food. However, it is unclear whether their findings can be applied to the purchase process of fresh fruit and vegetables. Studies concerned with the effect of fresh fruit and vegetable branding on consumer behavior and that apply methods to investigate the rather implicit aspects of the effect of such branding on consumer behavior are lacking.
The visual aspect of food is a central feature to which consumers react, and branding has a visual and implicit effect on consumer behavior. Therefore, visual methods are well-suited to investigating consumers’ food behavior. One possible visual method involves the integration of photos into the research process. Photos have been employed in consumer research; however, their content has not usually been analyzed. The use of photos in qualitative consumer research has been mostly limited to supporting other research methods (e.g., stimuli for interviews) and, in quantitative research, to use for mere descriptive-level analysis. There is a lack of studies concerned with how to use photo analysis in consumer research and methodological reflections on how to integrate (combine) quantitative and qualitative photo analyses.
To fill these gaps, this dissertation conducted two primary investigations. The first examined consumers’ reactions to fresh fruit and vegetable branding with regard to their choice (process), thoughts, visual perceptions, and recall, as well as to identify and characterize relevant consumer segments by employing various methods to observe unconscious consumer behavior under research conditions that are as realistic as possible. The second aimed to identify challenges of using photos in consumer research and to develop a mixed methods framework for integrating quantitative and qualitative photo analyses.
In order to achieve these aims, visual and mixed methods approaches were applied to both aspects. Eye tracking, standardized questionnaires, qualitative interviews, a choice-based conjoint experiment, and think aloud protocols were used.
With regard to the empirical level of consumer behavior toward branded fresh fruit and vegetables, the results showed that consumers neither paid much visual attention nor gave much thought to fresh produce branding when making choices. Instead, consumers mainly used the visual features of the fresh produce itself as cues for decision-making. However, it was discovered that this low level of (visual) attention to branding in supermarket fruit displays may be diminished further by deficits in the presentation of branded fresh produce since manipulated and saliently displayed branding were found to improve visual capture, the decision-making process, and brand recall. Furthermore, the results revealed that some consumer groups might be of special interest to the marketing and branding efforts of fresh fruit and vegetables: 1) brand-oriented consumers especially benefited from salient branding by exhibiting shorter decision times; and 2) consumer segments that preferred branded fresh produce shared a higher level of the personality trait “food and beverage need for uniqueness”.
With regard to the methodological level of how the visual method of using photos was addressed, the applicability, utility, and challenges of using photos in qualitative interviews were analyzed and discussed. A number of practical challenges in conducting a photo-based qualitative interview were identified, as well as the challenge of analyzing numerous photos (quantitative) while not neglecting the detailed analysis of single photos (qualitative). This novel methodological challenge of photo analysis for mixed methods research was addressed by investigating the principles of different methods of analyzing photos from different scientific fields. In light of this investigation, a procedural mixed methods framework for analyzing photographic material was developed and illustrated with an example from consumer research. The framework developed allows the integration of different quantitative and qualitative photo analyses. It was shown that photos can be integrated by means of data transformation, which is also the starting point for integration with other types of quantitative/qualitative data (numbers, text).
This dissertation provides insights into the reaction of consumers toward branded fresh fruit and vegetables and, based on the findings, into how to improve the (visual) marketing of such. Furthermore, it supports the application of quantitative and qualitative photo analysis by developing a procedural framework for extending the integration in mixed methods through the use of photographic material.
Growing vines in sloping terrain is an integral part of the European viticultural heritage. In recent decades, however, a significant decrease in vineyard acreage on steep slopes has occurred, particularly in Germany. The elevated labour demand at these sites together with stronger international competition and the overall diminished profitability of the sites for wine estates have been implicated as drivers behind this decrease. However, a sound cost assessment of different vineyard setups in terms of general growing conditions and corresponding mechanisation options has thus far not been performed.
This doctoral thesis contributes to explaining the abandonment of steep slope vineyard sites from an economic perspective using the example of Germany. To compare production costs for different growing conditions, working time records based on a transpaent framework of vineyard site types were collected at five management-led wine estates in Germany over three years for 30 reference sites, resulting in 82 observations and over 3,400 single records for labour and machine hours. After valuing the working time records with appropriate cost rates, the cost dataset was analysed using analysis of variance (ANOVA) with fixed and random effects to estimate the influence of different external factors on the structure of viticultural costs.
The analysis revealed that the cost differences between the vineyard site types are attributable to differences in mechanisation intensity and the types of machines used. Flat terrain allows the mechanisation of most viticultural processes with very efficient machinery. Sites with limited mechanisation require specialised machinery to overcome the gradient. The more mechanisation is limited, the higher the demand for manual labour will be. The sites with the most difficult conditions inhibit the mechanisation of single or all processes. In addition to this, specialised steep slope machinery usually entails higher capital costs and operates more slowly, mostly due to additional securing by rope, necessitating the double passing of every row.
The results of the research discussed in this thesis indicate that there are substantial cost disadvantages at vineyard sites that are impeding full mechanisation with standard machinery. Viticultural costs at the most disadvantaged manual sites are more than 1.6 times those at fully mechanised flat terrain sites. In addition to these per hectare disadvantages, vineyards planted on slopes are more often affected by water scarcity, which has intensified in recent years and is expected to further intensify due to the impacts of climate change. Water scarcity causes drought issues that lead, among other negative effects, to below-average yield levels, thereby exacerbating the cost disadvantage of steep slope sites on a per litre level. These cost disadvantages usually cannot be covered by price premiums, thus leaving a gap between elevated costs and stable prices.
These findings raise serious concerns about the future of steep slope viticulture, especially given the prospects of adverse environmental impacts driven by climate change. Worse, most consumers are not willing to pay higher prices for steep slope wines. As such, additional costs cannot be expected to be offset by price premiums. The only possibility for the sustained cultivation of steep slope sites lies in financial support by the public sector. To justify public support, the overall value of steep slope viticulture created by the additional ecosystem services (ES) they provide under certain conditions and with respect to potential social costs must be assessed.
Wine from Vitis vinifera cv. Riesling grapes is one of the most internationally
renowned white wine styles worldwide. There are several aroma compounds that are fundamental to the sensory properties of Riesling wines. Two such classes of compounds are monoterpenes and C13-norisoprenoids, both of which can be influenced in the vineyard, the winery and in the bottle. The overall objective of this study was to investigate the role of certain vineyard and winemaking practices on the development of sensorial important flavour compounds in Riesling, with particular emphasis on 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN).
Chapter 2 investigates the effect of a manipulated light environment during grape ripening on Australian Riesling over two consecutive vintages. The application of coloured shade cloth was used to alter not only the quantity of light but also the quality of light reaching grape leaves and berries. Changes in both grape and wine composition were observed. A reduction solely in the quantity of light resulted in a significant reduction in free and total TDN concentrations. However, sensory descriptive analysis of finalised wines demonstrated a conflicting result, as increased ‘kerosene-like’ aroma (a common descriptor for TDN) was not always linked to higher TDN concentrations.
The starting point of TDN formation is the availability of its precursors;
carotenoids and their subsequent glycosylated breakdown products. Chapter 3 comprises the analysis of major grape carotenoids present in grapes under various light conditions. While several complex mechanisms involved in photosynthesis and notably the photoprotection triggered by different light qualities during the ripening period were observed, the reduction in concentration of carotenoids was significantly higher in sun-exposed samples compared to other treatments during grape ripening.
The degree of carotenoid degradation could be a useful marker for the decision
regarding TDN management in wine during winemaking or storage. Furthermore, Chapter 3 provides results from the analysis of C13-norisoprenoid glycosides in wines made from grapes grown under different shade cloth in correlation to their corresponding TDN concentrations. For this experiment two approaches were considered, firstly the untargeted profiling and then targeted analysis of the glycosides in wine. Glycosides related to TDN evolution in wine were tentatively identified.
While trials conducted in Australia evaluated the effect of shading on the evolution of important grape and wine components in Riesling, Chapter 4 describes
the significance of increased solar exposure (leaf removal) on Riesling grape and wine
compositional behaviour in combination with different row orientations (East-West,
Northeast-Southwest, North-South) under German field conditions.
Microclimatically, East-West orientated rows maintained the lowest interior canopy
light interception, Northeast-Southwest and North-South orientations lead to the
highest light exposure values, peaking in the morning and afternoon, respectively.
Pronounced differences in secondary metabolites were found between the different
exposure levels introduced by leaf removal. Highly exposed grapes showed significantly higher bound and free TDN concentrations, however, no direct correlation was observed between elevated free TDN levels and the perception of ‘kerosene-like’ aroma in the wines.
Finally, Chapter 5 comprises a comparative analysis of oenological practices of grape pressing and yeast selection including enzyme (β-glycosidase) addition on the extraction of TDN and related C13-norisoprenoids in finished wines. Insignificant differences were observed between the effect of whole-bunch and crushed/destemmed fruit pressings. While the choice of yeast during alcoholic fermentation did not affect TDN formation, the addition of glycosidases to musts resulted in an approximately 15% to 25% increases in free TDN concentrations after the wines were submitted to accelerated ageing. However, these changes were negligible when compared to the consequence of viticultural management practices.
This thesis represents a valuable contribution to the understanding of the formation, management and sensory contribution of TDN in Riesling. Furthermore, this study investigated for the first time the effect of different light regimes (shade cloth) on TDN evolution which can be used to advance the management of Riesling grape production, especially during hotter summers.
Die vorliegende Arbeit befasst sich mit der Herstellung von Würzen und Bieren mittels eines neuartigen Sudprozesses aufgrund einer integrierten, dynamischen Läutertechnologie und dem qualitativen Vergleich zu herkömmlichen Systemen. Das Sudhaussystem OMNIUM by Ziemann® mit dem darin implementierten neuartigen Maischefiltrationsverfahren NESSIE by Ziemann® produziert Würzen, deren Zusammensetzung sich von herkömmlichen Würzen unterscheidet. Erhöhte und erniedrigte Konzentrationen bestimmter Inhaltsstoffe im Vergleich zur herkömmlichen Würzebeschaffenheit verändern die Hefeversorgung und konsequenterweise das fertige Bier. Ziel der vorliegenden Arbeit ist es, den Einfluss auf die Würzezusammensetzung sowie das Herauslösen bestimmter Inhaltsstoffe durch die konventionelle und neuartige Sudhaustechnologie zu bilanzieren, zu vergleichen und die Auswirkungen auf den gesamten Brauprozess zu untersuchen.
Hierzu werden ober- und untergärige Biere mittels eines konventionellen und neuartigen Sudwerks im 30 l-Maßstab hergestellt. Die entstehenden ungekochten und gekochten Würzen und die hieraus produzierten Biere werden umfassend analysiert. Hierbei werden neben den Prozessparametern wie Extrakt und pH-Wert, Kohlenhydrate, Gerbstoffe, Eiweißfraktionen, Fettsäuren sowie Mineralstoffe und der photometrische Jodwert erhoben. Die anfallenden Treber werden ebenfalls untersucht. Die Schaumstabilität des fertigen Bieres wird untersucht und das Bier mittels einer Flavournetzverkostung bewertet. Die Ergebnisse dieser Sude bilden den Basisvergleich der Sudhäuser und die Grundlage der weiterführenden Vertiefung.
Die weiterführenden Untersuchungen befassen sich mit dem aufschließbaren Extrakt der Treber des Drehscheibenfilters, dem photometrischen Jodwert und der Enzymaktivität von Würzen, einer möglichen Reduktion der Trubfracht der neuartig hergestellten Würzen, der chemisch-physikalischen Stabilität sowie der Geschmacksstabilität der hergestellten Biere, den Gerbstofffraktionen und deren Einfluss auf die Fermentation und der Verarbeitung verschiedener Rohstoffe und Rohstoffqualitäten mittels des Drehscheibenfilters. Abschließend wird eine theoretische Modellierung der Maischefiltration mittels eines Drehscheibenfilters erstellt und ein Scale-Up der gewonnenen Daten auf Industriegröße durchgeführt. Für die untergärige Fermentation der neuartig hergestellten Würzen wird ein Leitfaden zur Anpassung der Gärungsparameter erstellt.
Die Auswertung der Ergebnisse zeigt, dass sich durch den Drehscheibenfilter im neuartigen Sudhaus im Vergleich zum konventionellen Sudhaus eine Erhöhung des Mineralstoff- und des Fettsäurespektrums und eine Verringerung des Gerbstoffzusammensetzung ergeben. Die stickstoffhaltigen Verbindungen sowie das Zuckerspektrum bleiben unverändert. Die neuartige Würzebeschaffenheit ermöglicht eine um zwei Tage zügigere und intensivere Fermentation. Durch die gesteigerte Hefevermehrung wird mehr Maltose und Maltotriose sowie Zink und Kalium aufgenommen. Dies bewirkt einen höheren Endvergärungsgrad der Biere. Die gute Versorgung der Hefe führt zu einem tendenziell niedrigeren Gärungsnebenproduktespektrum, was durch ein angepasstes Gärverfahren korrigiert werden kann. Die Deckung der Verkostungsergebnisse zeigt, dass die Herstellung geschmacklich gleicher Biere mit den unterschiedlichen Sudhäusern möglich ist. Durch das signifikant niedrigere Gerbstoffspektrum im Bier wird deutlich, dass eine gerbstoffseitige Stabilisierung im neuartig hergestellten Bier zu überdenken ist. Ein Einfluss der Gerbstoffe auf den Hefemetabolismus konnte ausgeschlossen werden. Insgesamt ist die chemisch-physikalische Stabilität und Geschmacksstabilität der neuartig hergestellten Biere als sehr gut zu bewerten. Die Schaumstabilität unterscheidet sich nicht zu konventionell hergestellten Bieren. Die signifikant höhere Würzetrübung ist im Bier nach der Sedimentation mit der Hefe während der Gärung nicht wieder zu finden. Zusätzlich kann großtechnisch die Trubfracht ohne Beeinträchtigung der Inhaltsstoffe mittels einer Zentrifuge verringert werden. Es zeigt sich, dass der photometrische Jodwert unabhängig des Einsatzes eines heißen Malzauszuges über die Fermentation hinweg absinkt. Ein direkter Zusammenhang mit der enzymatischen Aktivität des heißen Malzauszuges konnte nicht nachgewiesen werden. Prinzipiell ermöglicht die dynamische Siebfiltration mit der angeschlossenen diskontinuierlichen Extraktion die Verarbeitung verschiedener Rohstoffe und verschiedener Rohstoffqualitäten. Die Ergebnisse sind auf den industriellen Maßstab übertragbar.
SUMMARY
Lager yeasts are hybrid organisms that originated by cell-fusion of two species of the genus Saccharomyces, S. cerevisiae and S. eubayanus. Post-hybridization events such as copy number variations (CNV), chromosome loss, reciprocal translocations or inter-chromosomal rearrangements can affect genome size, ploidy or sporulation efficiency. In polyploidy hybrids, the presence of multiple alleles of one gene complicates functional studies that rely on genome manipulation, e.g. gene deletions. Most yeast genetic engineering methods are based on the yeast homologous recombination (HR) machinery, which works excellently in S. cerevisiae but has a low efficiency in lager yeasts.
In this thesis, I developed a strategy to improve the HR efficiency of lager yeast allowing short-flank (sf) PCR-based gene targeting. HR efficiency was successfully improved by overexpressing RAD51, which encodes a key regulator of the HR pathway that performs the search for complementary DNA strands during recombination. The successful improvement of sf PCR-based gene targeting in lager yeast was demonstrated by targeting the S. cerevisiae-derived loci of ADE2 and HSP104 in the allotetraploid lager yeast Weihenstephan 34/70. This technology can now be used to facilitate genetic engineering in lager yeast, e.g. by altering the expression of specific genes involved in wort fermentation and flavor production.
Other mechanisms of genome evolution are by uptake of DNA through horizontal gene transfer or introgression. These were studied in more detail in a cider yeast strain. Genome sequencing revealed that the strain represents a particular Saccharomyces uvarum isolate. Interestingly, in this strain we identified the acquisition of ~100 kb of S. eubayanus DNA harboring 54 gene ORFs at chromosome XIV. An analysis based on DNA polymorphisms suggests that a lager yeast strain is likely parental donor of this DNA rather than a S. eubayanus strain. An additional DNA insertion with high identity to Torulaspora microellipsoides was found at chromosome XII. The introgression of this specific DNA region was previously observed in several wine yeast strains. It harbors 19 wine – related genes such as FOT1/FOT2, encoding the fungal oligopeptide transporter Fot, which confers advantages in nitrogen utilization. Strikingly, the S. uvarum cider isolate outcompetes in standard and cold fermentation regimes, S. cerevisiae EC1118, which is considered a workhorse of the wine industry.
Beer and wine yeasts are characterized by their flocculation properties at the end of fermentation. Flocculation is the ability to produce cell-flocs, a critical trait for industrial yeast, which enables facile separation of cells from the green beer. To implement non-conventional yeast (NCY) in an existing brewing process, these yeasts need to be adaptable to the current brewing technology. Therefore, in this thesis, the flocculation properties of a NCY, Saccharomycopsis fermentans, were characterized. I could show that flocculation of S. fermentans is Ca2+- dependent like in S. cerevisiae. By PacBio genome sequencing, based on the similarity to the FLO1/5/9 genes of S. cerevisiae and the ALS gene family of Candida albicans, 34 flocculation genes were identified in S. fermentans, and termed FAS (for FLO/ALS-like sequences). Moreover, FAS genes are found to be located at sub telomeric and telomeric regions as are the S. cerevisiae flocculation genes. “Telologs” – orthologous or paralogous genes located at telomers – was a novel term introduced to identify genes which share an evolutionary conserved genomic location.
Wildunfälle stellen deutschlandweit und insbesondere in waldreichen Bundesländern wie Hessen zeitweise bis zu einem Drittel der Gesamtunfälle dar. Im Mittelpunkt der vorliegenden Dissertation steht die folgende Forschungsfrage:
Welche Parameter bestimmen die raum-zeitliche Verteilung von Wildunfällen und wie können Entscheidungsträger aus Politik, Wirtschaft und Verbänden aktuell und angesichts der technologischen Entwicklung eine bestmögliche Senkung der Unfallzahlen herbeiführen?
In einem zweiteiligen Ansatz wird zunächst eine Analyse der seitens der hessischen Polizei aufgenommenen Unfalldaten der Jahre 2006 bis 2016 durchgeführt, um Hypothesen zu den Einflussfaktoren zu beantworten. Aufbauend auf einem Forschungsprojekt der Bundesanstalt für Straßenwesen (BASt) werden die zehn gravierendsten hessischen Schwerpunktstrecken ermittelt und für diese eine Umfeldanalyse mit behördlichen GIS-Daten durchgeführt. Die Ergebnisse werden mit den Werten von zufallsbasiert gewählten, unfallunauffälligen Abschnitten verglichen. Weiterhin werden die o. g. über 170.000 Unfallreporte ausgewertet. Die Resultate der Analysen werden anhand der Fachliteratur mit dem aktuellen Stand der Forschung verglichen. Im zweiten Schritt wird die in die Unfallpräventionsarbeit involvierte Akteurslandschaft mittels Szenariotechniken zur Strategieentwicklung untersucht. Anhand der gewonnenen Erkenntnisse über die Dynamiken und Potenziale wird ein Handlungskonzept erarbeitet und mit Vertretern der Stakeholder diskutiert. Abschließend werden auf der Grundlage des in den beiden Arbeitsschritten gewonnenen Wissens Entscheidungsgrundlagen und Handlungsempfehlungen für die beteiligten Akteure erarbeitet.
Den deutlichsten Einfluss auf das Unfallrisiko hat der Faktor Dämmerung, während der sich je nach Tierart bis zu zwanzigmal so viele Kollisionen als über vergleichbare Zeitspannen bei Tageslicht ereignen. In der Analyse der jahreszeitlichen Verteilung zeigen sich zudem deutliche Schwerpunkte während der Paarungszeiten und Revierkämpfe. Hinsichtlich der Landschaftsmatrix führen erhöhte Anteile von Landwirtschafts- und Waldflächen nicht zwingend zu der Entstehung von Unfallschwerpunktstrecken, vielmehr muss die individuelle Komposition der Örtlichkeit untersucht werden. Die Nähe von großen Fließgewässern und Seen hingegen bewirkt einen steigernden Einfluss auf die Unfallzahlen. Dichteunterschiede der Wildunfallhäufigkeit je nach Tierart zeigen sich meist nur im größeren Maßstab; im Westen Hessens dominieren Reh-, im Süden Schwarzwildunfälle. Die Unfälle geschehen zu 70 % männlichen Fahrern, insbesondere in den Altersgruppen 20-24 sowie 45-50 Jahren.
Insbesondere der Herbst bietet sich für Warnaktionen an, beispielsweise durch temporär aktivierte LED-Schilder. Bezüglich der effektivsten klassischen Gegenmaßnahme, dem Wildschutzzaun, besteht die Notwendigkeit zu einer besseren Datenhaltung der Behörden sowie einer Novellierung der Richtlinie zu den Einsatzkriterien für und der Konstruktion der Zaunsysteme. Die Prozesslandschaft zeichnet sich dadurch aus, dass die meisten Akteure nur wenig Initiative zeigen und gleichzeitig lediglich geringem Handlungsdruck unterliegen. Es bestehen keine Interessenskonflikte, sondern eher zeigt sich Synergiepotenzial. Zentral ist zuallererst, die hauptsächlich organisatorischen Aufgabenstellungen wie ein übergeordnetes Großprojekt zu starten und eine zentrale Open-Data Meldeplattform einzurichten. Hier sind die Politik und Einrichtungen wie die Bundesanstalt für Straßenwesen gefordert. Nur mit ihrer Initiative können klassische Maßnahmen optimiert, innovative Lösungen in Kooperation mit der Automobilindustrie und IT-Dienstleistern eingeführt und das volle Potenzial der sich aktuell weiterentwickelnden Technologie zur Unfallprävention ausgeschöpft werden.
Blattseneszenz stellt bei Pflanzen einen genetisch geregelten, komplexen Alterungsprozess dar. Sie wird durch die Kombination von Umwelt- und Altersfaktoren ausgelöst und dient dem Recycling von Nährstoffen. Charakteristisch für die Blattseneszenz sind eine erhöhte Expression von Seneszenz-assoziierten Genen (SAGs), der Abbau von Chlorophyll und die Rückverlagerung von Nährstoffen, insbesondere von Stickstoff (N). Bei der Weinrebe Vitis vinifera dient N nicht nur dem pflanzlichen Wachstum, sondern auch der Hefeernährung während der alkoholischen Gärung des Mostes. Der Gehalt an hefeverfügbarem N (YAN) in der Beere hängt sowohl von der N-Verfügbarkeit des Standorts, als auch von der N-Einlagerung während der Reife ab. Durch den Klimawandel erfolgen Traubenreife und Blattseneszenz zunehmend zeitlich entkoppelt, wodurch im Most der in nördlichen Anbaugebieten spätreifenden Rebsorte Vitis vinifera cv. Riesling der für eine gute Vergärbarkeit empfohlene Zielwert von 150 mg/L YAN nicht erreicht wird und das Risiko von Gärproblemen steigt. Daher wurde in dieser Arbeit auf zwei Standorten mit unterschiedlicher N-Verfügbarkeit 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 zuverlässig und schnell, ihre N-Remobilisierung wie auch ihre Genexpression glichen der von natürlicher Seneszenz. Die UV-C-Behandlung erzeugte ebenfalls Seneszenz-Symptome, sie erreichte jedoch nicht die Effektivität der Ethephon-induzierten und der natürlichen Seneszenz. Auf dem Standort mit geringer N-Verfügbarkeit 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-Verfügbarkeit hatte keines der beiden Verfahren einen Effekt auf die Most-N-Versorgung. Die erreichten YAN-Steigerungen verbesserten die Vergärbarkeit, obwohl der Zielwert von 150 mg/L in keinem Fall erreicht wurde. Die zur Sicherstellung einer guten Gärleistung empfohlene YAN-Konzentration im Most ist daher kritisch zu überprüfen.
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.
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 véraison. 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 véraison flavanols revealed high concentrations after defoliation. Sunny periods before véraison 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 véraison. 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.
Products based on yeasts are a new trend in oenological application. Yeast derived
products (YDPs) are used in any stage of wine making, from the vineyard to the
wine. Most products shall support either the alcoholic or the malolactic fermentation
as nutrient supply. YDPs can also serve as aroma enhancers or fining agents. The
amount of products and applications is permanently increasing and therefore the
demand of a deeper insight into this topic is getting more important. This dissertation
serves as basis for following studies on and characterisation of yeast derived
products. It proves, that the topics to be followed and investigated in the future are
manifold and worth working on.
Already existing analytical methods can be used, sometimes with adoptions.
Standard operation procedures (SOPs) are worked out for future reproducible
analyses. For the most parameters, there are remarkable deviations between the
samples. Only ammonia and the turbidity (NTU) are exceptions. The parameter
“water soluble fraction” has the most important influence. Samples with a high
solubility do show higher contents in most of the parameters compared to samples
with lower solubility (and higher content of soluble matter). This leads to the
conclusion, that there are two groups within the YDPs, depending on their solubility.
These two groups should be kept separately in future data evaluation, interpretation
and calibration of spectroscopic methods. Multi-variate date exploration is highly
effective and revelatory. Outliers can be detected and explained.
The FTIR measurements of the eluates, suspensions and the UV-VIS/NIR
measurement give similar results, supporting, that spectroscopic methods are
powerful tools for YDPs analyses and characterisations. The data pre-treatment of
the spectra is crucial and mandatory, but solutions can be presented.
The calibrations for the different spectroscopic methods are promising. This proves,
that it is worth to keep on working on this field. Only the ATR-FTIR in the set-up of the
apparatus used in this project, shows too many drawbacks. The UV-VIS/NIR
calibrations could be improved by using a device more precise and suitable for the
nature of the samples.
A grouping according to the solubility is the only grouping, that can be done with the
data set of this study. Neither the grouping according the main application, nor the
supplier show a pattern. A separation of oenological and food industry products does not take place. The samples from food industry are highly soluble and can be
separated from the less soluble oenological products. But the soluble oenological
products (yeast extracts, mannoproteins) cannot be separated from food industry
products.
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.
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.
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.
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), Güttingen (CH) and Wädenswil (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.
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.
In den Jahren 2011 und 2012 wurde im Versuchsfeld am „Thüngersheimer Scharlachberg“
des Sachgebietes Weinbaumanagement der Bayerischen Landesanstalt für Weinbau und
Gartenbau bei der Rebsorte Silvaner kontinuierlich das Wasserpotential mittels
temperaturkorrigierter In-situ-Psychrometer gemessen. Ziel der durchgeführten Arbeiten war
es, die Wasserpotentialdynamik von Reben an ihrem natürlichen Standort und die
Pflanzenreaktion auf wechselnde Witterungseinflüsse zu untersuchen. Zusätzlich wurde die
Veränderung der hydraulischen Leitfähigkeit der Gesamtpflanze bei unterschiedlichem
Evaporationsanspruch und Bodenwasserstatus betrachtet. Die kontinuierliche
Wasserpotentialmessung an Reben wurde in den Versuchsjahren am Rebstamm und an
traubentragenden einjährigen Trieben durchgeführt. Dabei konnte festgestellt werden, dass
sich das Messgewebe des Triebes besser eignet, um das Wasserpotential über einen längeren
Zeitraum kontinuierlich mittels In-situ-Psychrometer an Reben zu ermitteln. Anhand der
Tagesgänge ließen sich deutliche Beziehungen zwischen der Wasserpotentialdynamik und
den verschiedenen Witterungsfaktoren feststellen. So hatten die beiden Faktoren VPD und
Temperatur den größten 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 für 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 Rebenbewässerung induziert. Demnach führte der verbesserte Wasserstatus zu
einem reduzierten Potentialgradienten der bewässerten Reben zur Aufrechterhaltung der
Transpiration im Vergleich zu den nicht bewässerten Reben.
In den Jahren 2011 bis 2013 wurde Exaktversuch zur Prüfung der Auswirkungen einer
Rebenbewässerung mit bestimmten Bewässerungsschwellenwerten durchgeführt. Ziel dieses
Feldversuchs war es, den Einfluss verschiedener Bewässerungsmethoden und
Bewässerungsintensitäten auf die generative und vegetative Wuchsleistung der Rebsorte
Silvaner zu untersuchen. Das versuchstechnisch vorgegebene Bewässerungsmanagement der
Varianten moderate Überflurbewässerung, intensive Überflurbewässerung, moderate
Unterflurbewässerung und intensive Unterflurbewässerung wurde mittels des
frühmorgendlichen Wasserpotentials exakt gesteuert. Gleichzeitig wurde innerhalb des
Versuchsfeldes der Verlauf der Bodenfeuchtigkeit innerhalb der Kontrollvariante mittels der FDR-Technologie gemessen. Zusätzlich wurde nach der Lese von jeder Variante das C12 / C13
Stabilisotopenverhältnis, der δ13C-Wert, im Mostzucker ermittelt. Um den Einfluss der
verschiedenen Bewässerungsintensitäten und -methoden auf die generative und vegetative
Wuchsleistung zu untersuchen, wurden die erzielten Traubenerträge, Mostgewichte (°Oe),
Mostsäuren und Schnittholzerträge bestimmt. Der Bewässerungsversuch zeigte auf, dass eine
Zusatzbewässerung bei der Rebsorte Silvaner einen starken Einfluss auf das vegetative
Wachstum ausübte und kein signifikanter Einfluss auf die erzielten Traubenerträge
festzustellen war.
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.
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.