Refine
Document Type
- Doctoral Thesis (31)
Has Fulltext
- yes (31)
Is part of the Bibliography
- no (31)
Keywords
- Weinbau (2)
- Wine (2)
- water deficit (2)
- 4-ethylphenol (1)
- Aminosäuren (1)
- Außendarstellung und Profilierung (1)
- Behavioral economics (1)
- Behavioral strategy (1)
- Bewässerung (1)
- Black box (1)
Institute
- Wein- und Getränkewirtschaft (7)
- Allgemeiner und ökologischer Weinbau (5)
- Frischproduktlogistik (2)
- Landschaftsplanung und Naturschutz (2)
- Obstbau (2)
- Angewandte Ökologie (1)
- Bodenkunde und Pflanzenernährung (1)
- Getränkeforschung (1)
- Molekulare Pflanzenwissenschaften (1)
- Urbaner Gartenbau und Pflanzenverwendung (1)
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.