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A full-scale study on efficiency and emissions of an agricultural biogas plant
(2013) Nägele, Hans-Joachim; Jungbluth, Thomas
In this study we focused on process engineering for the conversion of biomass, and utilization of the gas obtained by fermentation. Several topics regarding efficiency and emissions have been addressed by conducting intensive and long-term measurements. In detail, our objectives were (1) to conduct long-term measurements of the electric energy consumption of the biogas plant and its individual components and examination of energy-saving potentials; (2) to develop a method to measure mixing quality in the digester and to examine the mixing quality by measuring nutrient distribution in the digester with different agitator setups; (3) measure the influence of maintenance strategies on efficiency and emissions at long-term operation in practical application; (4) examine the efficiency of an external biological desulfurization plant under practical conditions to enhance biogas fuel quality. The results of electric energy measurement over a period of two years showed that a percentage of 8.5% (in 2010) and 8.7% (in 2011) of the produced electric energy was required to operate the biogas plant. The consumer unit agitators with 4.3% (in 2010) and 4.0% (in 2011) and the CHP unit with 2.5% (in 2010 and 2011) accounted for the highest electrical power demand, in relation to the electric energy produced by the CHP unit. Calculations show that the agitators consumed 51% (in 2010) and 46% (in 2011) of the total electric energy demand. The results stress the need for further research in the fields of substrate homogenization in biogas plants in order to reduce the demand for electric energy. Based on the results of electric energy consumption, follow-up studies have been conducted on nutrient distribution, which depends on agitator type and agitator regime. The investigation showed that significant differences in local concentrations of organic acids, which are not correlated to DM content, are found in dependence on agitator type and agitation regime. Measurements on electric energy consumption of the different agitator types verified that, depending on the agitator type, the saving potential rises up to 70%. The results for emissions and efficiency of the CHP unit confirm the fact that after readjustment of the air-fuel ratio (Lambda value), the emission values for NOx decline while CO increases. However, the emission-optimized operation mode leads to lower engine efficiency. The permanent measurements proved their legitimacy showing various emission deviations from the limiting values prior and post maintenance. In addition, the results show that by monitoring the lubricating oil quality, the oil change intervals can be maximized, while ensuring that engine performance is not endangered. This allows the operator to reduce maintenance expenditures while minimizing wear. To increase engine efficiency, the reduction of the lambda value combined with exhaust gas scrubbing and exhaust gas power generation is a promising approach. However, that would presuppose a permanent and almost total removal of H2S from the biogas. The fourth part of the study examined the technical and economic feasibility of a Fixed Bed Trickling Bioreactor (FBTB) for external biological desulfurization of biogas. In contrast to well-established biological methods to oxidize H2S, the FBTB allows removal of these from the biogas process, thus ensuring a constant low H2S concentration in the biogas. The FBTB showed H2S removal efficiencies (RE) of 98% at temperatures between 30-40°C. A major decline in RE in a range of 21-45% was observed when temperature in the FBTB dropped to a range of 5-25°C. The results revealed that different pH values of the percolation fluid and air ratios have little effect on RE. The practical use of the investigated FBTB system is an interesting technological alternative as disadvantages of internal biological desulfurization methods are being avoided. Due to high expenditures for operation resources and maintenance for FBTB operation during the research, a technical optimization is necessary to ensure economical operation. The results presented in this thesis show that the scientific instrument ?research biogas plant? is the ideal supplement to methods such as laboratory scale research and measuring programs. Research at full scale offers an entirely new opportunity to determine the interaction of process technique and process biology and to conduct long-term studies of gas utilization. Compared to measuring programs at commercial biogas plants, the research biogas plant has the advantage of being significantly better equipped with measurement technologies and that economic success is not the overall goal.
Advancing soybean adaptation to Central European growth conditions with novel breeding tools
(2020) Jähne, Felix; Würschum, Tobias
According to the European Soy Monitor 2018 (European Soy Monitor, 2018), there is a wide discrepancy in the EU between market demands and general sustainability aims regarding soybean products. Europe needs to take action, if it wants to maintain its protein demands and at the same time requests a reduction in the destruction of globally important tropical and subtropical ecosystems. One step towards more sustainable soybean products lies in the increase of domestic production which has the potential to decrease soybean imports from areas of unsustainable cultivation. An augmented EU production of soybeans can be achieved for example by increasing the yield potential of soybeans in areas where successful cultivation already takes place or by expanding the cultivation area to more northern parts of Central Europe. Breeding for new, improved and adapted soybean cultivars that meet those terms, is a key activity towards that aim. This dissertation elucidates three different ways how the adaptation of soybeans to the climatic and photoperiodic conditions of Central Europe can be assisted and even accelerated: 1) By using off-season climate-controlled LED chambers to enable a speed breeding single seed descent approach. A 10 h light regime, rich in blue and deprived of far-red light emission is capable to significantly reduce and synchronise the generation time of soybeans. It was possible to shorten the life cycle for a panel of 8 soybean cultivars from different maturity groups to 77 days. This allows several generations of soybeans to be grown within one year. For the short day crops rice and amaranth on the other hand, different light quality parameters were favoured. In those crops mean flowering time was accelerated when far-red light was included in the light protocol. This underlines the importance of a crop-specific light regime in order to realise the full potential of LED-based speed breeding single seed descent. 2) By including experiments in climate-control chambers in combination with molecular tools (i.e. genomic prediction) to advance cold tolerance in soybeans. This quantitatively inherited key trait is necessary to adapt soybeans to colder regions and consequently extend growing areas of this crop to higher latitudes in Europe. In the biparental soybean population Merlin × Sigalia (103 recombinant inbred lines) three QTL for cold tolerance during pod onset were found on chromosomes 7, 11 and 13. The relatively small proportion of genotypic variance for this trait explained by these QTL underlines the quantitative nature of cold tolerance. Genomic prediction was shown to be a promising approach to select for cold stress tolerance. Scenarios with different test set sizes and prediction models were evaluated. In scenarios with smaller test set sizes prediction accuracies increased if known and confirmed QTL were included in the prediction model. 3) By incorporating citizen science into the breeding process. The citizen science project ‘1000 Gärten’ from 2016 approached this topic. Phenotypic data from soybean cultivars and breeding lines were collected by citizen scientists in 2492 gardens throughout Germany which generated a unique dataset. Among many other results this study was able to show that in 2016 and within the early maturity segment of soybeans the factor temperature influenced flowering and maturity to a higher degree than photoperiod although day length differed by over an hour between the north and the south of Germany during the time of flowering. It was shown that this admittedly challenging tool can realise a significant impact not only regarding the possibility of a highly multi-environmental screening of breeding material but also by connecting plant breeding, agriculture and potential future costumers in order to raise awareness and acceptance of a crop in larger parts of the society - a factor that may not be highlighted enough when a new crop is introduced to our agriculture. These approaches should not be seen as an alternative to classical plant breeding, but rather considered as valuable additional tools that can contribute to conventional breeding of soybeans, as well as other crops. If applied, the presented tools may assist plant breeding to pave Europe’s way towards a greener and more sustainable future that is urgently needed.
Anaerobic treatment of a biorefinery’s process-wastewater
(2024) Khan, Muhammad Tahir; Lemmer, Andreas
The phrase “one man's trash is another man’s treasure” perfectly embodies the concept of a circular bioeconomy, emphasizing the conversion of waste into valuable resources while embracing a zero-waste approach. In line with this perspective, the primary objective of the current research was to assess the suitability of a biorefinery’s process-wastewater as a potential feedstock for biogas plants by investigating its anaerobic biodegradability and exploring its biogas and methane production potentials. For such a specific purpose, the process-wastewater from a commercial-scale biorefinery specializing in 5-hydroxymethylfurfural (5-HMF) synthesis and refining was utilized. To fulfill the main objective, three independent sub-objectives were formulated. The initial investigation centered on assessing the biochemical methane potential (BMP) of the typical constituents present in process-wastewater, such as furans (5-HMF and furfural), phenols (syringaldehyde, vanillin, and phenol), and weak acids (levulinic and glycolic acid), as well as the full 5-HMF process-wastewater. The BMP assessments for each test substance were conducted separately at different concentrations (2, 4, 6, and 8 gCOD/L) and temperatures (37°C and 53°C) via the Hohenheim batch fermentation test. The model components at 2 gCOD/L, apart from phenol at 53°C, were efficaciously degraded, in most cases to such an extent, that supplementary methane generation was detected i.e. exceeding their maximum theoretical limits. However, increasing the concentrations of the test components in the assays resulted in diminishing methane conversion at both operating temperatures. Eventually, among the tested components, the 5-HMF process-wastewater was evaluated to be one of the most refractory substrates, following phenol, vanillin, and 5-HMF, when tested at its maximum load under mesophilic and thermophilic conditions. The subsequent investigation focused on examining the anaerobic decomposition of the 5-HMF process-wastewater and its main identified constituents, including 5-HMF, furfural, and levulinic acid in continuously operated anaerobic filters (AFs). The test substances were individually injected into the biofilm reactors operating at 43°C in a controlled manner with a randomized experimental design. This study yielded some unusual outcomes i.e., the test substrates exhibited satisfactory degradation, while at other instances, they hampered the process. Introducing butyric acid between the injected components revealed no signs of compromised consortia. The 5-HMF process-wastewater in this investigation emerged as the least favorable substrate for methane conversion. The culmination of the current research involved utilizing the 5-HMF process-wastewater as a sole feedstock for the fixed-bed reactors. Hence, necessary nutrients to support the existing microbial consortia in the AFs were added to the process-wastewater. Given its toxic nature, the substrate dosage was initiated from its reduced concentration of 10 gCOD/L and was gradually increased to 20, 30, 40, and 50 gCOD/L, with corresponding organic loading rates (OLRs) of 2, 4, 6, 8, and 10 gCOD/L.d, respectively, as the trial progressed. Despite meeting the nutrient requirements, the gas yields, in particular methane, were not remarkable. However, a noteworthy finding surfaced: as the gCOD/L of the fed substrate increased, so did the concentrations of the short-chained volatile fatty acids (SCVFAs) in the reactors. This observation led to the conclusion that the low methane yields were at the behest of the accumulation of SCVFAs in the AFs, at both mesophilic and thermophilic temperatures. Ultimately, the subpar performance of the process-wastewater as a substrate is considered to stem from its exceptionally high concentration of the pollutant 5-HMF, which significantly influences its overall characteristics, causing longer lag phases, especially at higher OLRs. This, in turn, triggers the inhibitory behavior, leading to reduced methane yields. Consequently, these factors render the 5-HMF process-wastewater a precarious choice for biogas plants in terms of efficient energy recovery. While AFs are well-suited technology for treating high-strength wastewaters, for the substrate such as 5-HMF process-wastewater, it might be beneficial to increase retention times by decreasing the OLRs. Additionally, reducing the strength via dilution combined with these adjusted process parameters could further enhance its decomposition. Anaerobic digestion (AD), traditionally used for energy recovery from (bio)wastes, has potential beyond biogas production in the bioeconomy. This research showed that the highly recalcitrant 5-HMF process-wastewater can be a viable source for producing SCVFAs through AD. Furthermore, the Muttenz biorefinery could utilize the filtration byproducts to produce levulinic acid, aligning with a cascading biorefinery approach.
Analyzing resistance to ergot caused by Claviceps purpurea [Fr.] Tul. and alkaloid contamination in winter rye (Secale cereale L.)
(2022) Kodisch, Anna; Miedaner, Thomas
Ergot caused by Claviceps purpurea [Fr.] Tul. is one of the oldest well-known plant diseases leading already in medieval times to severe epidemic outbreaks. After the occurrence of honeydew, the characteristic ergot bodies called sclerotia are formed on the ear. These are containing toxic ergot alkaloids (EAs). Strict limits are set within the European Union. Rye (Secale cereale L.) as cross-pollinating crop is particularly vulnerable to ergot since the competitive situation of fungal spores and pollen during flowering. Nevertheless, even today the threat is real as agricultural practice is changing and screening studies revealed EAs in samples of the whole cereal value chain frequently. The aims were to establish a harmonized method to test ergot resistance and EA contamination in winter rye, to clarify major significant factors and their relevance and to reveal the suitability of one commercial ELISA test. Further, effort was paid to examine the covariation of ergot amount and EA content considering different factors because of prospective legislative changes. Genotypes showed significant variation for ergot severity and pollen-fertility restoration after natural infection as well as artificial inoculation whereas a high positive correlation could be found between both treatments. Additionally, variances of environment, general combining ability (GCA), specific combining ability (SCA), and interactions were significant. Although male pollen-fertility restoration was of utmost importance, the female component was also significant. This illustrates that apart from promising selection of high restoration ability the maternal restorability could be exploited in future breeding programs especially when a high pollen amount is already reached. A large-scale calibration study was performed to clarify the covariation of ergot severity, EA content (HPLC, ELISA) considering genotypes, locations, countries, years, and isolates. EA profile was rather stable across country-specific isolates although large differences regarding the EA content were detected. The moderate covariation between ergot severity and EA content (HPLC) indicates that a reliable prediction of the EA content based on ergot severity is not possible what can also not be explained by grouping effects of the factors. Further, EAs seem not to act as virulence factor in the infection process since EA content showed no relationship to disease severity. Additionally, the missing correlation of ELISA and HPLC leads to the conclusion that the ELISA is not an appropriate tool what can be used safely to screen samples regarding ergot in the daily life. The genetic variation of male-sterile CMS-single crosses was analysed in a special design without pollen in field and greenhouse to identify resistance mechanisms and to clarify whether ergot can be reduced in the female flower. At this, comparison of needle and spray inoculation revealed medium to high correlations illustrating that both methods were suitable for this research. Significant environment and genotype by environment interaction variances were detected. So, testing across several environments is necessary also without pollen. Further, small but significant genotypic variation and identification of one more ergot-resilient candidate revealed that selection of female lines could be promising to further reduce ergot. The EA content was lower for less susceptible genotypes. Thus, EA content can be considerably reduced by breeding. A strong positive correlation could be found for ergot severity and EA content when analysing 15 factorial single crosses. The male pollen-fertility restoration was also here the most relevant component but the female component contributed an obviously higher proportion for the EA content than for ergot severity. In conclusion, this thesis demonstrate that implementing of a high and environmental stable male fertility restoration ability via exotic Rf genes can effectively reduce ergot although also the female restorability enables great opportunities. The unpredictable covariation between ergot amount and EA content illustrates that both traits have to be assessed, in particular the EA content by a valid HPLC approach to guarantee food and feed safety.
Auslöser und Ausprägung des Varroa Sensitiven Hygiene (VSH) Verhaltens im Zusammenhang mit der Reproduktion der Varroamilbe Varroa destructor
(2024) Fölsch, Lina; Hasselmann, Martin
The ectoparasite Varroa destructor causes massive economic damages to the Western honey bee (Apis mellifera) and thus threatens the health of honey bee colonies worldwide. When left untreated, varroa populations can lead to high winter colony losses (Genersch et al. 2010; Traynor et al. 2020; Le Conte et al. 2010). Beekeepers must thus routinely treat against varroa to keep their colonies healthy. A sustainable solution to overcome the varroa problem is selection for varroa resistant honey bees. In addition to studies on natural selection against varroa, there is much interest in breeding varroa resistant honey bees. During varroa resistant selection the focus is often on different selection criteria, such as mite non-reproduction (MNR) and varroa sensitive hygiene (VSH). The selection criteria MNR describes the proportion of non-reproductive mites in a colony (Virag et al. 2022). VSH encompasses the specialized removal behavior of mite infested brood by worker bees (Dietemann et al. 2013; Harbo und Harris 2005). This brood removal interrupts varroa reproduction, which leads to reduced varroa infestation in honey bee colonies. The experiments in thesis were conducted as part of the SETBie project. The SETBie (Selection and Establishment of Varroa-tolerant Bee Colonies) project was a four-year selection project whose objectives included breeding a varroa-resistant honey bee in Baden-Württemberg, Germany. Several institutions and beekeeper organizations cooperated in this project. This dissertation focuses on the factors that trigger VSH behaviour, in addition to documenting the reproductive success of the mite (MNR) in selected colonies. Initial experiments investigated the relationship between VSH and the reproductive success of female Varroa (MNR). A widely held hypothesis was that the reproduction of the mite and the associated nymphal stages in the brood cells triggered the removal behaviour of the workers. However, this hypothesis was disproved by placing mites in capped brood cells and comparing the removal behaviour of reproducing mites with that of mites whose reproduction had been blocked by a special procedure (publication 1). Both groups of mites were removed at a rate of about 40% and did not differ significantly from each other. Therefore, reproduction of the mite could be excluded as a trigger for removal behavior of the workers. This result was supported by simultaneous analysis of VSH behaviour and the proportion of non-reproductive mites (MNR) in a large number of pre-selected colonies. It was also assumed that the increased number of non-reproductive mites (MNR) within a colony is directly connected to VSH behaviour, because the workers would primarily remove the reproductive mites, leaving only non-reproductive mites behind. In addition to providing evidence that mite reproduction is not the trigger of removal behaviour, our analysis of the data collected during the SETBie project showed no correlation between MNR and VSH values (publication 3). The MNR value of a colony therefore does not allow any conclusions to be drawn about the VSH value, which should be taken into account in recommendations for breeding practices. Furthermore, an experiment was conducted to rule out the possibility that removal behaviour effects the normal reproduction of the mite in the next cycle (publication 3). The need for other triggering factors for removal behaviour to occur was clearly demonstrated in this first set of experiments. Varroa mites manipulated to remove specific factors and inanimate objects were placed in capped brood cells to determine what influences removal behaviour. We found that an object (bead) alone does not induce removal behaviour (publication 2). Dead and odour-reduced mites were removed more frequently than the bead and control, but not anywhere near as frequently as live mites. We can thus assume that, in addition to the odour of the mite, the movement of the mite in particular has a signalling effect that triggers this removal behaviour. Other as yet unknown factors such as the reaction of the larvae to the parasitism are likely to play an important role in the removal behaviour of workers. The SETBie project took place over a period of four years, which allowed us to analyse colonies over several generations. Although MNR and VSH are in principle selectable traits, our analysis has shown that they are difficult to improve over multiple generations (publication 4). Colonies with low MNR values could often be improved by crossing them with a drone (artificial insemination) from a colony with a high MNR value. However, it also became clear that it is difficult to maintain high MNR values. Methodological difficulties in targeted selection of MNR/VSH also became noticeable during the collaborative project, which involved the cooperation of numerous breeders. Despite prior infestation of the selected colonies with 180 mites, it was often not possible to collect enough mites to make a valid statement about the reproductive capability of the mite. Even after opening many cells, the minimum number of 10 single infested cells could not be found, which means that MNR values could not be determined for about 63 % of the evaluated colonies due to the presence of too few mites. The selection and breeding work involved in this project is extremely labour-intensive and therefore expensive and requires a high level of expertise among the breeders. It was shown that MNR and VSH are in principle selectable and thus theoretically a Varroa-resistant honey bee line can be bred. However, for future projects, methodological problems need to be resolved or the evaluation methods of the MNR and VSH traits need to be simplified. An optimal solution would be the identification of molecular markers to support selection via genetic heritability. However, this requires further fundamental knowledge about the Varroa mite, the mechanisms that trigger the behaviour of the currently used selection traits, and more precise phenotypic definition of the resistant behaviours.
Breeding for resistance to Fusarium ear diseases in maize and small-grain cereals using genomic tools
(2021) Gaikpa, David Sewordor; Miedaner, Thomas
The world’s human and livestock population is increasing and there is the need to increase quality food production to achieve the global sustainable development goal 3, zero hunger by year 2030 (United Nations, 2015). However, biotic stresses such as Fusarium ear infections pose serious threat to cereal crop production. Breeding for host plant resistance against toxigenic Fusarium spp. is a sustainable way to produce more and safer cereal crops such as maize and small-grain winter cereals. Many efforts have been made to improve maize and small-grain cereals for ear rot (ER) and Fusarium head blight (FHB) resistances, using conventional and genomic techniques. Among small-grain cereals, rye had the shortest maturity period followed by the descendant, hexaploid triticale while both wheat species had the longest maturity period. In addition, rye and triticale were more robust to Fusarium infection and deoxynivalenol accumulation, making them safer grain sources for human and animal consumption. However, a few resistant cultivars have been produced by prolonged conventional breeding efforts in durum wheat and bread wheat. High genetic variation was present within each crop species and can be exploited for resistance breeding. In this thesis, the genetic architecture of FHB resistance in rye was investigated for the first time, by means of genome-wide association study (GWAS) and genomic prediction (GP). GWAS detected 15 QTLs for Fusarium culmorum head blight severity, of which two had major effects. Both weighted and unweighted GP approaches yielded higher prediction abilities than marker-assisted selection (MAS) for FHB severity, heading stage and plant height. Genomics-assisted breeding can shorten the duration of breeding rye for FHB resistance. In the past decade, genetic mapping and omics were used to identify a multitude of QTLs and candidate genes for ear rot resistances and mycotoxin accumulation in maize. The polygenic nature of resistance traits, high genotype x environment interaction, and large-scale phenotyping remain major bottlenecks to increasing genetic gains for ear rots resistance in maize. Phenotypic and molecular analyses of DH lines originating from two European flint landraces (“Kemater Landmais Gelb”, KE, and “Petkuser Ferdinand Rot”, PE) revealed high variation for Gibberella ear rot (GER) severity and three agronomic traits viz. number of days to female flowering, plant height and proportion of kernels per cob. By employing multi-SNP GWAS method, we found four medium-effect QTLs and many small-effect (10) QTLs for GER severity in combined DH libraries (when PCs used as fixed effects), none co-localized with the QTLs detected for the three agronomic traits analyzed. However, one major QTL was detected within KE DH library for GER severity. Two prioritized SNPs detected for GER resistance were associated with 25 protein-coding genes placed in various functional categories, which further enhances scientific knowledge on the molecular mechanisms of GER resistance. Genome-based approaches seems promising for tapping GER resistance alleles from European maize landraces for applied breeding. After several cycles of backcrossing and sufficient selection for agronomic adaptation traits, the resistant lines identified in this thesis can be incorporated into existing maize breeding programs to improve immunity against F. graminearum ear infection. Breeding progress can be faster using KE landrace than PE. A successful validation of QTLs identified in this thesis can pave way for MAS in rye and marker-assisted backcrossing in maize. Effective implementation of genomic selection requires proper design of the training and validation sets, which should include part of the current breeding population.
Breeding winter durum wheat for Central Europe
assessment of frost tolerance and quality on a phenotypic and genotypic level
(2015) Sieber, Alisa-Naomi; Würschum, Tobias
Durum wheat (Triticum durum) is a tetraploid wheat that is used for pasta and other semolina products. Quality standards for semolina requested by the pasta industry are very high. Different characteristics should come with the cereal as raw material for an optimal end product. Vitreosity, the glassy and amber quality feature of durum wheat kernels, is an indicator for high semolina yield. The complex protein-starch matrix of glassy kernels breaks the grain into the typical semolina granulate instead of flour during milling. Humid conditions, like late summer rains in Central Europe, have a huge effect on this characteristic, changing this matrix irreversibly. Such processes in the kernel are less understood and challenge plant breeders to find genotypes with improved vitreosity. A set of F5 winter durum wheat lines (Chapter 2) was used to investigate the relationship between protein content and vitreosity as well as the impact of humidity on the stability of the trait. A method to evaluate the mealy part in kernels was improved and enabled to test for the influence of humidity on vitreosity. Furthermore, it was revealed that the vitreosity of a durum wheat kernel depends on the protein content up to a specific threshold as well as on the genotypic potential to form the complex endosperm matrix. The ability to maintain this kernel quality under humid conditions also highly depends on the genetics of a variety. In the Mediterranean region, durum wheat is grown as autumn-sown spring type. The mild winters as well as rain during spring allow the plants to develop well, and the dry summers enable an early harvest in June. Durum wheat production in Central Europe, on the other hand, is confronted with harsh winters and recurring severe frosts. The lack of a sufficient frost tolerance in combination with high quality, forces farmers to use the spring type with a spring sowing. Growing winter durum instead of spring durum wheat, would allow an autumn sowing. Using the winter type in this growing area, could have several advantages like an increased yield and stability due to a prolonged growing time. Further, the constant soil coverage would prevent soil erosion and the growth vigor of winter durum has advantages against weeds. The success of winter durum breeding depends on frost tolerance as a key factor for varieties with excellent winter survival. Discontinuous occurrence of frosts across years and protective snow coverage, however, limit the phenotypic selection for this trait under field conditions. Greenhouses or climate chambers could be used as alternative to test under the necessary conditions, but those fully-controlled tests are time consuming and labor-intensive. The ‘Weihenstephaner Auswinterungsanlage’ are wooden boxes with movable glass lids used as a semi-controlled test. Plants are exposed to all seasonal conditions, including frost stresses, in this test, but they can be protected from snow coverage. While this method is already successfully used to test for frost tolerance in bread wheat, the application in durum wheat has not been evaluated yet. The frost tolerance scorings of winter durum elite lines (F5 and F6) based on the ‘Weihenstephaner Auswinterungsanlage’ were compared to the field evaluation (Chapter 3). It was demonstrated that this semi-controlled test produces reliable and highly heritable (h2 = 0.83-0.86) frost tolerance data. The correlation of those results compared with the field data (r = 0.71) suggests this semi-controlled test as an indirect selection platform. Since it is now possible to test cost-efficient at early stages for frost tolerance, the next challenge was to determine whether the kernel quality or the grain yield suffers from an increased frost tolerance. In a survey with F5 winter durum elite lines, no negative association between frost tolerance and quality or other important agronomic traits could be found in European breeding material (Chapter 4). In order to support classical plant breeding, which relies predominantly on phenotypic data and parental information, molecular markers can be taken into account. Molecular markers can provide an in-depth look into the genetic architecture of traits, enable the determination of the relatedness of genotypes, identify the genetic variation in a population, or can assess the effect of geographic selection preferences. Furthermore, it is possible to assist knowledge-based selection. This improves plant breeding programs on a genetic level. The population structure in spring durum has already been examined with molecular methods in several studies. Winter durum, on the other hand, was only analyzed as a small group as part of spring durum studies or in groups of landraces. A highly diverse and unique panel of 170 winter durum and 14 spring durum lines was analyzed using a genotyping-by-sequencing (GBS) approach. A total of 30,611 markers, well distributed across the chromosomes, were obtained after filtering for marker quality. A principal coordinate analysis and a cluster analysis were applied. Together they revealed the absence of a major population structure (Chapter 5). The lines, however, grouped in a certain way, depending on their origin, associated with decreasing quality and increasing frost tolerance moving from South to Continental Europe. These groups allow breeders to conduct targeted crosses to further improve the frost tolerance in the Central European material. Another possibility is to build heterotic groups for hybrid breeding. The linkage disequilibrium (LD) decay was within 2-5 cM, indicating a high diversity in winter durum. The high marker density together with the extent of LD observed in this analysis allows to perform high-resolution association mapping in the present winter durum panel. The 30,611 markers and additional markers for candidate genes in frost tolerance were used to assess the genetic architecture of frost tolerance in durum wheat (Chapter 6). A major QTL was identified on chromosome 5A, likely being Frost Resistance-A2 (Fr-A2). Additional analysis of copy number variation (CNV) of CBF-A14 at Fr-A2 support this conclusion. CBF-A14 CNV explains about 90% of the proportion of genotypic variance. Two markers found in the QTL region were combined into a haploblock and enabled to capture the genetic variance of this QTL. Furthermore, the frequency of the QTL allele for frost tolerance shows a latitudinal gradient which is likely associated with winter conditions. In summary, the selection tools for vitreosity and frost tolerance provided in this study create a platform for winter durum breeding to select for high quality genotypes with excellent winter survival utilizing phenotypic as well as genotypic information.
Characterisation of biogas digestate as raw material for fibre composites
(2022) Gebhardt, Marion; Lemmer, Andreas
Various synthetic fibres and natural fibres are used as reinforcing fibres in the fibre composite industry. Efforts towards sustainable products and the avoidance of land-use competition are increasingly driving the search for alternatives. Biorefineries are one possible solution. Biogas plants process structurally rich plant-based biomass. The resulting digestates have already been partially degraded. Natural reinforcement fibres are extracted chemically or biologically from plants, the use of digestates is obvious. This paper deals with the question whether biogas digestate can be used as a fibre raw material for composite materials. Digestates from four different commercially operated biogas plants in Germany are considered. Besides three biogas plants that utilize an average mix of animal excrement and plants one plant is operating solely plant-based. The solid portions of the fermentation residues were first examined regarding fibre quality. For this purpose, the fibre dimensions (fibre length and degree of slenderness) and the density of the fermentation residues were determined. Utilizing a feed analysis according to van Soest, the proportions of cell wall components were examined. The results of the investigations were compared with common fibres such as flax and wood. In addition to the properties, the possible fibre yield from the various fermentation residues was also considered. In this study, the influence of the starting substrates was considered in detail. For this purpose, the distribution of different size classes was first determined utilizing wet sieve analysis. These results were combined with the dry matter content. Digestates from a plant using exclusively plants as substrates, with a high proportion of hop vines, are considered separately. It is considered whether the additional washing of the fermentation residues brings an advantage for the fibre quality. To prove this thesis, the most common fibre properties are also examined and compared with wood fibres. These digestates from this biogas plant are used for the following investigations. Composite materials are often produced with a textile as reinforcement. Therefore, the digestate is first processed into a nonwoven. The wet laying technology is used, as it is suitable for various types of fibres. Only cellulose is used as a binding material so that the nonwoven is completely bio-based. The hot-press technology with a thermoset matrix is used to produce the composites. The matrix used is a partially bio-based epoxy resin system. The most suitable process parameters are determined with two test scenarios. In the first run, the proportion of added matrix is varied at constant pressure. In the second run, the pressure is varied at constant matrix content. Destructive and non-destructive material tests are carried out to check the material properties. To make a statement about a suitable application, the mechanical properties and the water absorption are of particular importance. In addition, the behaviour towards chemicals is examined to be able to assess the resistance of the material. For this purpose, the composite material is produced with the previously determined process parameters and immersed in various chemicals. Finally, the durability of the composite materials is examined. For this purpose, the composite material is also produced with the previously determined process parameters. An epoxy resin with a higher bio-based content is used as the matrix. The material is exposed to UV radiation and humid air for three months. Afterwards, the mechanical properties and water absorption are examined again. The main finding of the presented study is that the solid components of digestate can be processed into composite materials. The properties of the digestate fibres are similar to those of wood fibres. For the yield of digestate fibres, it is advantageous if only a small proportion of animal excrements is used as substrate in the biogas plant. Additional processing after fermentation leads to an increase in fibre quality. The hot-press-technology has proven to be a suitable process, as fully impregnated composites with reproducible properties can be produced. The process parameters determined are a pressure of at least 4:5MPa and a matrix addition of 60%, which corresponds to an excess of about 10%. The properties of the composites are comparable to Wood Plastic Composites. Therefore, they can be considered adequate. The durability is shown to be inadequate due to the strong reduction in mechanical properties after artificial weathering and chemical storage. The durability is mainly dependent on the matrix. Based on the results described, an application for the digestate composites as furniture material is recommended.
Charakterisierung der Qualität von Blütenpollen in unterschiedlichen Regionen Baden-Württembergs
(2022) Friedle, Carolin Gertrud Maria; Hasselmann, Martin
Honey bees (Apis mellifera) collect nectar and pollen from plants to feed their brood. Pollen provides a wide range of nutrients, such as proteins and lipids, but also carbohydrates, vitamins and enzymes. Because of these ingredients, pollen is also attractive to humans and is used as a dietary supplement. However, honey bees collect pollen not only from wild plants, but also from flowering crops grown in agriculture. Accordingly, contamination from plant protection products can be found in bee pollen and bee bread. In order to get a deeper insight into the occurrence and distribution of pesticide residues during an entire season, a total of 102 daily pollen samples were collected from April to July 2018 using pollen traps in an orchard in southern Germany. Almost 90% of the pollen samples showed detectable levels of pesticide residues. A total of 29 pesticides were detected in the samples, with more than half being fungicides, followed by insecticides and herbicides. Maximum concentrations of up to 4500 ng/g could be measured at the end of April. Samples collected in early May and late June also showed high levels of pesticides. A general risk management was performed to assess the risk of the detected pesticide concentrations for honey bees. The microbial quality of bee pollen is highly dependent on its botanical and geographic origin, as well as climatic conditions and post-harvest processing steps by the beekeeper. If no processing steps such as freezing or drying follow after harvest, the growth of microorganisms can be promoted and the pollen quality can be influenced by negative side effects such as fermentation or the production of mycotoxins. Bacterial and fungal colonies can be determined both by culture-dependent methods such as colony counting on plates and by culture-independent methods such as 16-rRNA amplicon sequencing. Following the hypothesis that storage conditions influence the composition of microorganisms in bee pollen, freshly harvested bee pollen was stored for seven days in June 2018 and 2019 under defined conditions (cold, room temperature, warm) and analyzed by sequencing 16S and 18S PCR amplicons. The bacterial community varied slightly between the sites studied and showed no significant difference between the storage conditions. The fungal community showed significant differences both between the studied sites and between the different storage conditions. The dominant fungal genera in the pollen samples were Cladosporium, Aspergillus and Zygosaccharomyces. While Cladosporium was most dominant in freshly collected pollen and the percentage decreased during storage, Aspergillus and Zygosaccharomyces showed a significant increase especially under warm storage conditions. Other contaminants naturally produced by plants can also have negative impacts on human health. Pyrrolizidine alkaloids belong to a group of phytochemicals, of which more than 600 structures are known in around 3% of all flowering plants worldwide. PA are known to be able to cause both acute poisoning and chronic damage or cancer in animals and humans. In July 2019, pollen was collected at 57 locations in Baden-Württemberg and analyzed for 42 different PAs and their N-oxides in order to expand knowledge about PA contamination in pollen and to be able to estimate the risk of the concentrations. A total of 22 different PAs were detected in over 90% of all samples examined. Only 5% of the PA were obtained as PA from plants of Senecio sp. identified, while 95% of PAs with a botanical background are from Echium sp. and Eupatorium sp. could be identified. The maximum total concentration of PA per sample was determined to be 48,400 ng/g. According to the risk values calculated by the BfR, however, 42% of the samples represented an increased risk to human health.
Deciphering the potential of large-scale proteomics to improve product quality and nutritional value in different wheat species
(2022) Afzal, Muhammad; Longin, Friedrich
Wheat (Triticum aestivum) is one of the most important staple crops globally, which provides on average ~20% of the dietary intake of protein, starch and further important ingredients like fiber, minerals, vitamins, and essential amino acids for humans. Besides common wheat, there exist further wheat species with global to only local importance, i.e., durum, spelt, emmer and einkorn. Common wheat and durum are relatively widely cultivated whereas the other three species are cultivated only in specific regions. Apart from other functions, wheat proteins largely influence the end-use quality of products such as bread and pasta quality. Furthermore, wheat proteins can induce inflammatory reactions in humans such as celiac disease, wheat allergy and non-celiac wheat sensitivity. Thus, proteome profiles of different wheat species and cultivars within these species are of high relevance for stakeholders along the wheat supply chain. Proteomic technology has made breakthrough advancements in the recent times capable of quantifying thousands of proteins in 1.5–2 hours. Also, the wheat reference genome has been published and extended recently. These developments are extremely helpful in studying the wheat proteome at a high resolution. However, the modern large-scale proteomics has yet neither been applied to perform comparative investigation of the proteomes of different wheat species nor to study the proteomes of different types of breads and flours nor to study its application in the context of plant breeding. Therefore, we utilized modern large-scale proteomics to fill these gaps within the framework of this PhD work. First of all, an optimized data analysis pipeline was designed to deal with big proteomics data. This was necessary to estimate a multitude of quantitative genetics parameters for each protein and perform a comparative investigation of the proteomes. Optimization included implementation of data filtering based on the quantification of a protein in a given proportion of the samples, cultivars and environments. Different tests such as test for normal distribution of each protein in the context of statistical modelling and test to check the equality of variance between groups to apply the appropriate t-test were incorporated into a semi-automated workflow. In parallel, we adjusted and improved the lab methodology to deal with hundreds of samples within a short time period. We introduced a novel hybrid liquid chromatography-mass spectrometry (LC-MS) approach that combines quantification concatamer (QconCAT) technology with short microflow LC gradients and data-independent acquisition (DIA). The proposed approach measures the proteome by label-free quantification (LFQ) while concurrently providing accurate QconCAT-based absolute quantification of the key amylase/trypsin inhibitors (ATIs). These methods were then applied to compare different wheat species based on dozens of cultivars grown at multiple locations. First, we compared common wheat and spelt and identified 3,050 proteins overall. Of total proteins, 1,555 proteins in spelt and 1,166 in common wheat were only detected in a subset of the field locations. There were 1,495 and 1,604 proteins in spelt and common wheat, respectively, which were consistently expressed across all test locations in at least one cultivar. Finally, there were 84 and 193 unique proteins for spelt and common wheat, respectively, as well as 396 joint proteins, which were significantly differentially expressed between the two species. Using potentially allergenic proteins – annotated as amylase/trypsin inhibitors, serpins, and wheat germ agglutinin – we calculated an equally weighted “allergen index” that largely varied across cultivars ranging from –13.32 to 10.88 indicating the potential to select for cultivars with favorable proteome profiles. Next, we examined the proteomes of six different flours (wholegrain and superfine flours) and 14 different bread types (yeast and sourdough fermented breads and common wheat breads plus/minus bread improver) from common wheat, spelt and rye. Proteins that could cause allergies were functionally classified and comparatively measured by LFQ in flours and breads. Our findings showed that allergenic proteins were more prevalent in common wheat and spelt than rye and were not specifically degraded during bread manufacturing. In terms of abundance of the allergenic proteins, there was almost no difference between spelt and common wheat and the type of grain is likely more important for allergenicity than milling or traditional fermentation techniques. In a further study, we generated the flour reference proteomes for five wheat species, identifying at least 2,540 proteins in each species. More than 50% of the proteins significantly differed between species. Particularly, einkorn expressed 5.4 and 7.2 times less allergens and amylase/trypsin inhibitors than common wheat, respectively, emerging as a potential alternative cereal crop for people with sensitivities to cereal allergens. Lastly, we studied the application of large-scale proteomics for plant breeding. We found a significant impact of the environmental factors on protein expression. Only a fraction of proteins was stably expressed in all environments in at least one cultivar. Environmental influence was observed not only in the form of absolute expression or suppression of a certain protein at one or more environments but also in the form of low heritability (H2). High coefficients of variation across wheat cultivars indicate that the protein profiles of different cultivars vary considerably. Although, heritability was low for many proteins, we were able to identify hundreds of proteins with H²>0.5 – including key proteins for baking quality and human health. It should be possible to specifically manipulate the expression of functionally important proteins with high heritability by selecting and breeding for superior wheat cultivars along the wheat supply chain. Nevertheless, a successful implementation in plant breeding programs needs an improvement in the speed of protein quantification methods and in the validation of protein functions and annotations. In a nutshell, high number of proteins can be quantified in cereal grains utilizing cutting-edge proteomics techniques, opening new avenues for their use in the wheat supply chain. We generated lists of intriguing candidate proteins for further investigations on wheat sensitivity, and proteins with high heritability and important biological functions. Current research work has significant implications for the scientific and business communities across multiple disciplines including breeding, agriculture, cereal technology, nutritional science, health, and medicine. Political decision-makers and stakeholders in the food supply chain can benefit from the findings of this PhD project.
Design and assessment of breeding strategies for hybrid wheat in Europe
(2018) Boeven, Philipp Hans Günter; Würschum, Tobias
Wheat is one of the top three global staple crops, possesses the largest global cultivation area, and plays a key role for the world’s future food security. However, its projected yield increase is insufficient to meet the future food and feed demand of an ever-growing world population. Consequently, the rate of breeding progress and productivity of wheat must be increased. Unfortunately, current wheat line breeding has a low return on investment mainly due to high levels of farm saved seeds, which makes wheat less attractive for the plant breeding industry and leads to lower investments and progress compared to other crops where the hybrid technology is established. Hybrid breeding is a worldwide success story in many crops but is not yet established in wheat. Hybrid wheat promises increased yield gain due to the exploitation of heterosis, higher yield stability and stabilized return on investments for breeding companies which warrants further investment and breeding progress in this important stable crop. The self-pollinating nature of wheat is a major bottleneck for hybrid seed production and efficient hybrid wheat breeding requires the redesign of the wheat floral architecture to enhance cross-pollination. Furthermore, the longterm success of hybrid wheat is crucially dependent on the establishment of heterotic groups, on the identification of a high yielding heterotic pattern, and finally, on the realized amount of heterosis and hybrid performance. Therefore, the main objectives of my thesis research were to: (i) analyze the genetic diversity and adaptation in a global winter wheat collection and evaluate how diversity trends could be used to support the development of heterotic groups in wheat; (ii) assess the relationship between heterosis and genetic distance under maximized diversity and evaluate the usefulness of exotic germplasm for hybrid wheat breeding; (iii) dissect the genetic architecture underlying male floral traits in wheat to enable genomics-assisted breeding approaches and investigate the trait seed set which is most crucial for an efficient hybrid seed production. The analyses of genetic diversity in a large worldwide panel of 1,110 winter wheat varieties released during the past decades showed no major population structure but revealed genetically distinct subgroups. Most of the global diversity trends could be explained by breeding history and were associated with geographical origin and long-term domestication. We found that the frequency of the copy number variants at the Photoperiod-B1 (Ppd-B1) and the Vernalization-A1 (Vrn-A1) loci reflect wheat adaptation to the environmental conditions of the different regions of origin. Thus, adaptation issues add an additional layer of complexity and hamper the direct introgression of genetic diversity to support the genetic divergence between heterotic pools. Based on all these analyses, we proposed HyBFrame, a unified framework illustrating how global wheat genetic diversity can be used to support and accelerate reciprocal recurrent selection for the development of genetically distinct heterotic groups in wheat. In a second experiment, we produced 2,046 wheat hybrids by crossing elite with elite lines as well as elite with exotic lines and performed multi-environmental field trials. Interestingly, we found an average midparent heterosis of about 10% in elite crosses as well as in exotic crosses and observed no evidence for a breakdown of heterosis under maximized genetic distance among the hybrid parents. Genetic distance based on genome-wide molecular markers revealed only a very weak association with midparent heterosis for grain yield. Here, we elaborated a functional Rogers’ distance giving weight to heterosis loci and observed a strong positive association between heterosis and this novel distance measure. Hence, considering the genetic architecture of heterosis revealed a more accurate picture of the relationship between heterosis and genetic distance. In addition, the genetic architecture of heterosis in wheat is crucially dependent on the genetic background. We found that a higher number of negative dominance and dominance-by-dominance epistatic effects can reduce the level of absolute heterosis in wide crosses between exotic lines and elite testers. Moreover, hybrid performance in wheat is mainly driven by parental per se performance. Thus, elite lines are favorable for hybrid breeding and should be employed as the starting material for heterotic grouping. Hybrid seed production is the major bottleneck for hybrid wheat breeding and explains the low market share of hybrid wheat varieties. Seed set on the female plants in crossing blocks is the most crucial trait for hybrid seed production in wheat. We tested 31 male lines and evaluated the hybrid seed set on two female tester lines in crossing blocks. Seed set showed a large genotypic variation and a high heritability suggesting that recurrent selection for increased seed set is feasible. The major problem is the synchronized flowering between male and female lines, making the evaluation of seed set in large panels very complex and difficult. Hence, indirect male floral traits with high correlation to the trait seed set would be promising to breed for improved hybrid seed production. We found a strong association between seed set and visual anther extrusion, underscoring that indirect male floral traits have a high potential for preliminary male screenings. We also dissected the genetic architecture underlying promising male floral traits and assessed the potential of genomics-assisted approaches for their improvement. We employed a panel of 209 diverse wheat lines and found a complex genetic architecture underlying all male floral traits. The Reduced height gene Rht-D1 was identified as the only major QTL, for which the commonly used height-reducing allele showed negative effects on male floral traits. This genetic architecture with many moderate- or small-effect QTL limits classical marker-assisted selection. In contrast, genomic prediction yielded moderate to high prediction abilities for anther extrusion. Finally, we proposed a breeding scheme to increase cross-pollination in wheat based on a combination of phenotypic and genomics-assisted selection. Taken together, hybrid breeding in wheat is a very promising approach and the next years will show if all of the current issues can be solved. This thesis research contributed to breeding strategies for hybrid wheat breeding and to the general understanding of heterosis in crops.
Development and assessment of a multi-sensor platform for precision phenotyping of small grain cereals under field conditions
(2014) Busemeyer, Lucas; Würschum, Tobias
The growing world population, changing food habits especially to increased meat consumption in newly industrialized countries, the growing demand for energy and the climate change pose major challenges for tomorrows agriculture. The agricultural output has to be increased by 70% by 2050 to achieve food and energy security for the future and 90% of this increase must be achieved by increasing yields on existing agricultural land. Achieving this increase in yield is one of the biggest challenges for the global agriculture and requires, among other things, an efficient breeding of new, higher-yielding varieties adapted to the predicted climate change. To achieve this goal, new methods need to be established in plant breeding which include efficient genotyping and phenotyping approaches of crops. Enormous progress has been achieved in the field of genotyping which enables to gain a better understanding of the molecular basis of complex traits. However, phenotyping must be considered as equally important as genomic approaches rely on high quality phenotypic data and as efficient phenotyping enables the identification of superior lines in breeding programs. In contrast to the rapid development of genotyping approaches, phenotyping methods in plant breeding have changed only little in recent decades which is also referred to as phenotyping bottleneck. Due to this discrepancy between available phenotypic and genotypic information a significant potential for crop improvement remains unexploited. The aim of this work was the development and evaluation of a precision phenotyping platform for the non-invasive measurement of crops under field conditions. The developed platform is assembled of a tractor with 80 cm ground clearance, a carrier trailer and a sensor module attached to the carrier trailer. The innovative sensors for plant phenotyping, consisting of several 3D Time-of-Flight cameras, laser distance sensors, light curtains and a spectral imaging camera in the near infrared reflectance (NIR) range, and the entire system technology for data acquisition were fully integrated into the sensor module. To operate the system, software with a graphical user interface has been developed that enables recording of sensor raw data with time- and location information which is the basis of a subsequent sensor and data fusion for trait determination. Data analysis software with a graphical user interface was developed under Matlab. This software applies all created sensor models and algorithms on sensor raw data for parameter extraction, enables the flexible integration of new algorithms into the data analysis pipeline, offers the opportunity to generate and calibrate new sensor fusion models and allows for trait determination. The developed platform facilitates the simultaneous measurement of several plant parameters with a throughput of over 2,000 plots per day. Based on data of the years 2011 and 2012, extensive calibrations were developed for the traits plant height, dry matter content and biomass yield employing triticale as a model species. For this purpose, 600 plots were grown each year and recorded twice with the platform followed by subsequent phenotyping with state-of-the-art methods for reference value generation. The experiments of each year were subdivided into three measurements at different time points to incorporate information of three different developmental stages of the plants into the calibrations. To validate the raw data quality and robustness of the data collection and reduction process, the technical repeatability for all developed data analysis algorithms was determined. In addition to these analyses, the accuracy of the generated calibrations was assessed as the correlations between determined and observed phenotypic values. The calibration of plant height based on light curtain data achieved a technical repeatability of 0.99 and a correlation coefficient of 0.97, the calibration of dry matter content based on spectral imaging data a of 0.98 and a of 0.97. The generation and analysis of dry biomass calibrations revealed that a significant improvement of measurement accuracy can be achieved by a fusion of different sensors and data evaluations. The calibration of dry biomass based on data of the light curtains, laser distance sensors, 3D Time-of-Flight cameras and spectral imaging achieved a of 0.99 and a of 0.92. The achieved excellent results illustrate the suitability of the developed platform, the integrated sensors and the data analysis software to non-invasively measure small grain cereals under field conditions. The high utility of the platform for plant breeding as well as for genomic studies was illustrated by the measurement of a large population with a total of 647 doubled haploid triticale lines derived from four families that were grown in four environments. The phenotypic data was determined based on platform measurements and showed a very high heritability for dry biomass yield. The combination of these phenotypic data with a genomic approach enabled the identification of quantitative trait loci (QTL), i.e., chromosomal regions affecting this trait. Furthermore, the repeated measurements revealed that the accumulation of biomass is controlled by temporal genetic regulation. Taken together, the very high robustness of the system, the excellent calibration results and the high heritability of the phenotypic data determined based on platform measurements demonstrate the utility of the precision phenotyping platform for plant breeding and its enormous potential to widen the phenotyping bottleneck.
Development and evaluation of methods for assessing the efficiency of biogas plants
(2022) Hülsemann, Benedikt Werner; Müller, Joachim
Biogas is a renewable energy source with main advantages compared to other renewable energy sources. The advantages include the use of organic waste as a substrate, local power and heat production, rural job creation, the possibility of a flexible gas production and a product which can easily stored and transported in a gas grid or on the roof of a digester. However, the development of the biogas sector is highly dependent on the costs of producing gas, electricity and heat. The production costs are higher than the costs for other energy sources. Growth of the biogas sector is therefore only possible if there is political promotion for biogas as there was in Germany through the EEG. Nowadays, due to the reduction of bonus payments in the EEG 2017 and EEG 2021 in Germany as well as the lack of policy promotion in several other countries, lower production costs based on a higher efficiency are essential to help the biogas sector grow further. In order to achieve higher efficiency and to tap the full potential of biogas, the efficiency has to be determined, which is done in this thesis. The input methane potential is determined using 6 different methods. These methods are compared on the basis of an investigation of 33 German agricultural BPs as well as one German and one US BP using food waste as feedstock. The four methods based on the batch test show a high sensitivity. Unfortunately, they also show efficiencies greater than 100% for most BPs, clearly indicating an underestimation of the degradable potential. Only for the US BP can an efficiency less than 70% be reported. This result is probably based on the lack of heating system corresponding to the lack of promotion of heat recovery in the US. The CE according to the BMP method also reveals an average efficiency of 95% for the German BPs. The values of the two gross calorific value-based methods show efficiencies below 100%, but with low sensitivity. The results of these methods can be used to determine the further potential of a bioeconomic process and to compare the biogas process with other industrial processes. There are several impact factors that affect the accuracy of the efficiency measurements. The installed meters are not frequently calibrated at most BPs. Also, some meters are almost completely missing, as only few BPs in Germany have a gas flow meter. Thus, assumptions and calculations are required to determine the efficiency. In the developed method, the gas flow must be calculated from the amount of the power production, the calorific value, the gas quality, the CHP unit efficiency and the conversion loss at the transformer. The last two values must be assumed, even if the database is small. Another important parameter is the feeding mass. It is measured by the German BPs, but in some cases, the data quality is low. For example, different crops are mixed in the silos and measurement of each substrate is not possible. This leads to measurement errors shown by the organic dry matter mass balance, which has a residual value of up to 24%, while only 11% can be occur based on water incorporation into the ODM. Another factor having an impact is the sampling. The results of a monthly sampling throughout the year show a fluctuation in the DM/ODM values. To investigate the accuracy of the methods used to determine the SMP of the substrate, the biochemical methane potential test is examined in detail. The BMP consists of the used inoculum, the substrate, the digestion system and the calculation. The impact of the used inoculum and the digestion system is investigated by using different inocula in one digestion system as well as by using the same inoculum in multiple digestion systems. The inocula used in this thesis are well-known and have been used in interlaboratory tests for several years. Thus, outliners were excluded. A CV of 4.8% can be reported between the different inocula, which is lower than reported in most other publications before. The use of different digestion systems shows a higher CV of up to 12.8%. For the inoculum and the digestion system, the deviation varies strongly and no clear correlation can be identified. Therefore, a correction of this effect is not possible. The biological yield efficiency of 21 of the investigated BPs is in the range of 100 ± 12.8%. This reveals the need of stricter rules for the digestion system. All digestion systems used in this thesis are described in the German guideline VDI 4630. The calculations were also done according to the German guideline VDI 4630. An influence can be neglected. However, if the results of a measurement with already dried gas are compared with the results of a calculation according to VDI 4630, which is based on the measurement with wet gas, a discrepancy can be found. Although, the CV using only one digestion system and one inoculum is only 1-7%. A comparison of the efficiency of different BPs by using the same inoculum and digestion system is hence recommended.
Differences in yield performance and yield stability between hybrids and inbred lines of wheat, barley, and triticale
(2015) Mühleisen, Jonathan; Reif, Jochen Christoph
Hybrids of wheat, barley, and triticale are expected to possess higher yield performance and yield stability compared to inbred lines. Assessment of yield performance as well as yield stability requires the evaluation of genotypes in plot-based yield trials across multiple environments. Evaluation of genotypes under stress conditions can be associated with increased field heterogeneity, which may result in imprecise estimates of genotypic values. The assessment of yield stability requires intensive testing in many environments, and it would be interesting to know how many test environments are required to reliably estimate yield stability. The key objectives of the present thesis were to (1) investigate optimal strategies to analyze field trials with high error variance due to spatially varying drought stress, (2) identify the required number of test environments to precisely estimate yield stability of individual barley genotypes, and (3) examine yield performance and yield stability of wheat, barley, and triticale hybrids and lines. Drought stress at two locations of a winter triticale trial caused increased field heterogeneity, resulting in lower heritabilities compared to the four non-stress locations. It was found that heritability could be increased by modeling incomplete block and row effects, by using visual scorings of drought stress intensity as covariates in an analysis of covariance, and by modeling a spatial covariance between adjacent plots. The most suitable model can be identified using the Akaike Information Criterion. In addition, it has to be ensured that the covariate is independent from genotypic effects and that it is linearly related with the response variable. Dynamic yield stability of genotypes was frequently found to depend strongly on the specific set of test environments. When the genotypes were evaluated in different environments, e.g. in the following year, the ranking in yield stability could be different. This would result in a low heritability. Theoretical assumptions and empirical studies showed that heritability can be increased when the number of test environments is increased. Five series of barley registration trials with a reduced number of 16 to 27 genotypes evaluated in 39 to 45 environments were used to investigate the relationship between magnitude of heritability of yield stability and number of test environments. Based on a cross-validation approach, it was found, that at least 40 test environments should be used to obtain a heritability of 0.5. Magnitude of heritability, however, varied strongly within and between series. Therefore, depending on the respective set of environments and genotypes, more or less test environments can be needed. Yield performance of wheat hybrids produced using chemical hybridizing agents (CHA) or cytoplasmic male sterility (CMS) was well investigated in other studies reporting around 10% midparent heterosis for grain yield. In the present thesis, CMS-based barley hybrids were compared with parental inbred lines and unrelated commercial inbred lines in breeding and registration trials. Midparent heterosis was around 10%. The comparison with commercial inbred lines in the registration trials revealed that hybrids could compete with and partially surpass outstanding inbred lines. Triticale hybrids, produced using CMS, were evaluated for grain yield at up to 20 environments with their parents and commercial inbred lines. Midparent heterosis amounted to 3% and no hybrid outyielded the best inbred line. The low yield performance of triticale hybrids is probably associated with CMS-system, since CHA-based triticale hybrids showed a midparent heterosis around 10% in early studies, which is comparable to the midparent heterosis found in wheat and barley. Yield stability of CHA-based wheat as well as CMS-based hybrids of barley and triticale was compared with yield stability of parental and commercial inbred lines on group level. The wheat and barley hybrids showed on average significantly higher dynamic yield stability compared to inbred lines, but the triticale hybrids did not. In the barley registration trials, hybrids had the highest dynamic yield stability on average. The CMS-based triticale hybrids, however, showed on average significantly lower dynamic yield stability as their female parents and the commercial inbred lines across 20 environments. In conclusion, hybrids of wheat and barley possessed an increased yield potential as well as an enhanced dynamic yield stability. In contrast, the CMS-based triticale hybrids showed only marginal yield advantages coupled with low dynamic yield stability. Further research is required to increase economical competitiveness of hybrids in all three crops, to identify and eliminate the reasons for poor performance of CMS-based triticale hybrids and to investigate the suitability of dynamic yield stability measures to identify vigorous and stress tolerant genotypes.
Effects of non-adapted quantitative trait loci (QTL) for Fusarium head blight resistance on European winter wheat and Fusarium isolates
(2010) Ohe, Christiane von der; Miedaner, Thomas
Fusarium head blight (FHB), caused by Fusarium graminearum and F. culmorum, is a devastating disease responsible for tremendous damage in wheat fields and contamination of grain with mycotoxins deoxynivalenol (DON) and nivalenol (NIV), rendering the harvest unsafe for human and animal consumption. The variability of Fusarium populations is high and changes in aggressiveness, chemotypes or species within and among Fusarium populations are known. Stable FHB resistance combined with high yield is one main target in wheat breeding programs. Mapping studies detected several quantitative trait loci (QTL) for FHB resistance in non-adapted sources, such as Sumai3 from China. The two most important and commonly used major QTL are located on chromosome 3BS (Fhb1) und 5A (Qfhs.ifa-5A). However, negative side effects of non-adapted resistance sources introgressed in elite winter wheat material are feared in Europe. Furthermore, the stability of the QTL effect against changing Fusarium populations is unknown. The objectives of this research were to analyze whether (1) the QTL Fhb1 and Qfhs.ifa-5A introgressed from a non-adapted resistance source into two winter wheat varieties have possible side effects on agronomic and quality performance, (2) 3-ADON and 15-ADON chemotypes are significantly different in their aggressiveness and DON production, (3) competition among Fusarium isolates in mixtures exists, and if so, how the resistant host will influence this competition. In conclusion, both resistance QTL are effective and stable in elite spring and winter wheat backgrounds. For improvement of FHB resistance both QTL are valuable, but Qfhs.ifa-5A would suffice for European breeding programs. Due to chemotype shifts, 3-ADON isolates could pose a greater risk to food safety than 15-ADON but breeding and use of highly resistant lines can reduce the risks associated with DON in wheat. Accordingly, resistant spring wheat lines were less affected by the tested Fusarium isolates and mixtures and, therefore, confirmed a high stability of these QTL. Directed selection of highly aggressive isolates due to the resistance QTL seems to be unlikely in the short term.
Der Einfluss von Wirtsfaktoren der Honigbiene (Apis mellifera L.) auf den Reproduktionserfolg der parasitischen Milbe Varroa destructor (Anderson & Trueman) auf die Auswirkungen einer horizontalen Verbreitung des Parasiten auf den Befall der Bienenvölker
(2014) Frey, Eva; Bessei, Werner
The honey bee colony is faced with a huge number of pathogens, including bee viruses, bacteria, fungi and mites. Among these pathogens, the ectoparasitic mite Varroa destructor is considered the most important parasite of the honey bee worldwide. This mite was discovered at the beginning of the last century in South East Asia within colonies of the original host, the Eastern honey bee Apis cerana. From the middle of the last century the mite has been spread worldwide by transports of infested A. mellifera colonies with dramatic consequences for both, feral and managed honey bee colonies. In the meantime this parasite has become the most serious economic problem for global beekeeping. In temperate climates nearly all honey bee colonies are infested and without yearly Varroa treatments these colonies would collapse within a few years. This confirms that a stable host parasite relationship has not been established yet. Therefore the control of V. destructor still represents the main challenge for beekeeping. The main reason for host damages is the dramatic increase of the Varroa population during the season. Our honey bee colonies are obviously unable to control this population dynamic of the parasite. The increase of the mite population is influenced by the reproductive rate of Varroa females within individual brood cells, by host-parasite-interactions on the colony level and by interactions among honey bee colonies on the population level. The dissertation at hand presents experimental approaches and results at all three levels. On the individual level we were able to demonstrate that age-dependent signals of the honey bee larvae not only activate the oogenesis of the Varroa females but even trigger the further course of mite reproduction. Our studies on the activation of the Varroa reproduction revealed that exclusively larvae within 18 h (worker) and 36 h (drones), respectively, after cell capping were able to stimulate the mite’s oogenesis. Furthermore, we were able to confirm for the first time the presence of a signal in the host larvae allowing the reproducing mites to adjust their own reproductive cycle to the ontogenetic development of the host. Under certain conditions such host signals can even stop an oogenesis of the female mite that has already been started. From an adaptive point of view that sort of a stop signal enables the female mite to save resources for a next reproductive cycle if the own egg development is not sufficiently synchronized with the development of the host. My results indicate that age specific volatiles of the larval cuticle are involved in the regulation of mite reproduction. According to preliminary quantitative GC–MS analysis we suggest certain fatty acid ethyl esters as candidate compounds. These host signals – either involved in the activation or in the interruption of the Varroa reproduction – offer possibilities to influence the reproductive success of Varroa females and might therefore be used for biological control in the future. Within an EU cooperation project we could additionally demonstrate that the so called temporary infertility of Varroa females is significantly correlated with three QTL of the host larvae. This confirms a genetic basis for host resistance factors that inhibit the mite reproduction. For this study we made use of the fact that we had access to a honey bee population at the island of Gotland, Sweden that has survived mite infestation without any treatment for more than 10 years. We crossed a queen from this tolerant population with drones from susceptible colonies to rear hybrid queens and produced a mapping population of haploid drones from these hybrids. Because honey bees have a haplodiploid sex determination, the haploid drones provide an extremely simple and highly efficient model system for genetic studies. Subsequently, we mapped three candidate target regions on chromosomes 4, 7, and 9. Although the individual effect of these three QTL was found to be relatively small, the set of all three had significant impact on the suppression of V. destructor reproduction by epistasis. The detection of this epistatic interaction was only possible because we used the simple genetic make-up of haploid drones. For studies on Varroa resistance on the colony level and for selection programs the interactions among the colonies of the local honey bee population have to be considered. In two experimental approaches I was able to prove that the invasion of Varroa mites from neighboring colonies – often called “reinvasion” – significantly influences the population dynamic of the parasite within the colony. First, we quantified the number of mites invading individual colonies in relation to the invasion pressure (= number and distance of infested colonies). For this approach we made use of an isolated military training area near Münsingen at the Swabian Alb not accessible to other beekeepers. We established ten “mite receiver colonies” continuously treated against V. destructor and placed them at distances of 1m to 1.5 km from four heavily infested “mite donor colonies”. In the donor colonies, we estimated the population of bees, brood, and V. destructor at three week intervals. The invasion of mites into the receiver colonies was recorded every 7-12 days. During the measurement period of about two months, between 85 and 444 mites per colony were introduced into the receiver colonies. Surprisingly, there were no significant differences in the invasion rates in relation to the distance between donor and receiver colonies. The second approach was performed under more realistic field conditions of two experimental apiaries established in regions with high and low bee densities, respectively. Additionally, in this experiment we analyzed the multiplication of the invaded mites. Thereby we confirmed that horizontal transmission plus the reproduction of the invaded Varroa mites can cause an exponential increase of the mite population that may exceed the damage threshold within three months. We were further able to show that the invasion rates – and therefore the final infestation – differ significantly according to the number of honey bee colonies in the neighborhood of the apiary: At the site with a high bee density, the average invasion rate per colony over the entire three and a half months period was 462 mites per colony compared to only 126 mites per colony at the site with a low bee density. As a consequence, the colonies of the apiary at the high bee density site revealed an average final infestation in November of 2,082 mites per colony compared to 340 mites per colony at the low bee density site. The highly infested colonies lost about three times more bees compared to the lower infested colonies – obviously a result of Virus infections transmitted by Varroa mites. With my different approaches I was able to add further elements of knowledge for a better understanding of how host factors and ambient conditions influence the Varroa reproduction within individual brood cells and the population dynamic within a honey bee colony. A better knowledge of these host parasite interactions is essential for the selection of mite resistant colonies and further more important for the development of concepts for an effective Varroa treatment.
Einsatz von Spurenelementen bei der Vergärung von nachwachsenden Rohstoffen in Biogasanlagen
(2014) Vintiloiu, Anca; Jungbluth, Thomas
The operational agricultural biogas plants in Germany are fed mainly with renewable raw materials. During substrate addition, several micro and macro elements enter the digester. These elements are essential nutrients for the methanogens. If their concentration is too low, the production of biogas can be disrupted. A large number of agricultural biogas plants use therefore commercially available trace element solutions to optimize the process and to achieve higher methane yields. When the fermentation is complete, the digestate containing these trace elements (mostly heavy metals) is spread on fields as fertilizer. The amounts added to the biogas process should be kept as low as possible in order to minimize the environmental damage. The purpose of this study was to investigate the cause of trace elements deficiency in renewable raw materials fed biogas plants. It was also tested whether the chelation of the nutrients could increase their bioavailability for microorganisms and thus lead to a reduction of the amounts needed for the stabilization of the fermentation process. The effect of the complexing agent ethylenediaminetetraacetic acid (EDTA) on the bioavailability of metal ions was tested. The sole addition of EDTA to an undersupplied substrate increased the methane yield by up to 32 %. When trace elements were also added, their amounts could be reduced by up to 75 % with no negative consequences for the fermentation process. EDTA is a persistent chelating agent and so it was further tested, whether readily biodegradable chelating agents (ethylenediaminedisuccinic acid (EDDS) and iminodisuccinic acid (IDS)) could have the same effect. During the investigation, IDS had a high statistically significant positive effect on the bioavailability of the metal ions, which exceeded the effect of EDTA. IDS represents therefore a good alternative to EDTA. The bioavailability of the metal ions in the digester was increased by the use of complexing agents, which made the reduction of the trace elements amounts needed to compensate for substrate-related deficiency symptoms possible. This reduces the pollution on the agricultural land on which the digestate is used as fertilizer.
Entwicklung und Erprobung eines Online-Messsystems für Biogasanlagen auf Basis der Nah-Infrarot-Reflexionsspektroskopie (NIRS)
(2013) Stockl, Andrea; Jungbluth, Thomas
Due to the EU?s and Germany?s political goals of expanding the use of renewable energy sources, the utilization of biomass for energy supply is expected to continue growing in the coming years. Consequently, the efficiency of biogas plants will have to be improved further. This applies both to raising the energy yield from the input materials and exploiting the full potential of the technical installations. During the four phases of the anaerobic digestion (AD) process, volatile fatty acids such as acetic and propionic acids are produced as intermediates. These compounds can be used as indicators of the function and stability of the digestion process. So far, volatile fatty acids have to be determined by sampling the digester content and analyzing the sample in the laboratory (e.g., by gas chromatography). It is thought that by using near-infrared-reflection spectroscopy (NIRS) for online measuring, the management and control of biogas plants could be facilitated, considerably. This was to be investigated in a project funded by the Baden-Württemberg Ministry of Rural Areas and Consumer Protection within the ?research platform on bioenergy? Baden-Württemberg?. In this study, a NIR-measurement system was calibrated for determining the concentration of volatile fatty acids in two semi-continuously operated, bench-scale digesters at mesophilic and thermophilic temperature level. For each of the two digesters, one NIR-sensor was calibrated for acetic and propionic acid, and a second one for total acid equivalents. The experimental studies were divided into three stages. The chapters of this research work consist of three peer-reviewed papers that describe these experiments.
Experimentelle Entwicklung einer modellbasierten prädiktiven Regelung für den flexiblen Betrieb von Biogasanlagen
(2023) Dittmer, Celina; Lemmer, Andreas
The transformation of the energy system requires controllable producers due to increasingly decentralised, fluctuating electricity generation from wind turbines and photovoltaics. Biogas plants can make a substantial contribution here by making plant operation more flexible and thus providing electricity as needed. Technical adjustments, such as the expansion of gas storage capacities and CHP output, can compensate for short-term fluctuations. However, in order to be able to shift the potential of electricity generation over longer periods of time, an adapted feed-in strategy is essential. The control of biogas production poses several challenges in practical implementation. First, the conversion of biomass into biogas is a complex process and must be considered individually for each biogas plant. Models developed so far use parameters for all characteristic process phases and influencing variables in order to be able to model anaerobic digestion. In contrast, biogas plants are often only rudimentarily equipped with measurement technology, so that corresponding parameters are not available. In this work, a model-predictive control of biogas plant operation was developed to enable demand-driven electricity generation. The aim was to develop models that are particularly well suited for practical use. Thus, for the first time, a successful application on almost all biogas plants could be possible without or with only minor adaptations to the existing measurement technology. All studies carried out in this thesis are based on a real-world laboratory, the "Unterer Lindenhof". This includes a practical biogas plant as well as an electrical consumption corresponding to that of a village with about 125 inhabitants. In a first step, forecasting models were evaluated to predict the electricity demand of the real-world laboratory over 48 hours in advance. Four models from the field of time series analysis were examined, one TBATS and three different ARIMA models. In an evaluation of 366 forecasts each, all four models performed sufficiently well to provide a set point for biogas plant operation, with average MAPE values of 13-16 %. Further investigations showed that forecasts can also be carried out over a period of up to 14 days without significant losses in forecast quality. In a further step, a model was developed to simulate biogas production. This is also based on time series analysis, or more precisely on a regression model. Thus, it differs significantly from previous developments in this field, which are mostly based on the complex ADM1. It turns out to be very advantageous that the developed simulation model uses as input parameters only historical data of the last four weeks of biogas production and the amount of solid substrates fed in, without considering their composition. The simulation of biogas production over 48 hours in advance is based on correlations resulting from these two data sets. An evaluation of the model over 366 simulations resulted in an average MAPE of 14-18 %. Data from both digesters of the biogas plant were used, which can be considered as independent systems, demonstrating the adaptability of the model. In a third step, the feeding schedule was developed for demand-based biogas production. For each 48 hours in advance, 1500 randomised feeding schedules were calculated. Some constraints were imposed, such as the maximum amount of substrate that is technically possible in the biogas plant. The biogas production expected from the feeding schedules could be calculated using the simulation model. By comparing the simulation with the desired biogas demand profile, the simulation with the least deviations could be determined and the appropriate feeding plan selected and implemented. The entire model predictive control system was used and thoroughly tested in a field trial at the real-world laboratory "Unterer Lindenhof". Over a period of 36 days, an average MAPE of less than 20 % was achieved in comparison between the real biogas production and the desired biogas demand. During the test period, the biogas demand was derived from the predicted electricity demand of the real-world laboratory. The investigations carried out show that the model-predictive control system developed enables demand-oriented electricity generation on full-scale and that, due to the models being very close to practice for the first time, adaptation to almost all biogas plants is possible.
Genetic architecture of quality traits in wheat
(2021) Rapp, Matthias; Longin, Friedrich
Quality traits in wheat are of great importance, as they are required for the production of a wide range of food products. In Europe, bread wheat (Triticum aestivum ssp. aestivum) for human consumption is primarily used in pastries. For durum wheat (Triticum turgidum ssp. durum) that is used almost exclusively for pasta production, quality traits are at least as important as in bread wheat. In Central Europe, the bread wheat subspecies spelt (Triticum aestivum ssp. spelta) is characterized by a different quality compared to bread wheat. In addition, it is produced for a niche market with a particular focus on the final product quality. The high number of demanded quality traits of a wheat variety represents a great challenge for wheat breeders. Thus, knowledge about the genetic architecture and interrelation of quality traits is of high value for wheat breeding. Due to the long list of quality traits in wheat, we focused on currently important quality traits in each of the three wheat species. In durum wheat, I was interested in traits with a high importance for durum millers and pasta producers. The protein content and the sedimentation volume are of high importance for pasta producers as they influence the firmness of cooked pasta, better known as “al dente”. A low falling number may lead to brown instead of light yellow pasta, which goes back to an increased maillard reaction during pasta production and drying. The vitreousity, representing the glassy appearance of durum grains, and the thousand kernel mass influence the semolina yield and are therefore of great interest for durum millers. In the genome-wide association mapping, I identified several putative QTL for these quality traits. For the sedimentation volume, a genomic region on chromosome 1B appeared to be important. A BLAST search against the reference genomes of emmer and bread wheat revealed the Glu-B3 gene as a likely candidate. For vitreousity, genomic regions on chromosome 7A explained a larger proportion of the genotypic variance. One of these QTL, possibly related to the Pinb-2 locus, also slightly influenced the protein content. Thus, this genomic region might be a genomic reason for the positive correlation between vitreousity and protein content. For TKM we detected a putative QTL, which explained a large proportion of the genetic variance, but could not be attributed to a known gene. Besides a good performance for quality traits, a modern durum wheat variety should be complemented by a good agronomic performance, in particular a high grain yield. This poses a great challenge for plant breeders, since grain yield and protein content are negatively correlated. With regard to simultaneously improving grain yield and protein content, the protein yield or the grain protein deviation (GPD) were proposed. We evaluated those and further selection indices for their potential to be utilized for the simultaneous improvement of grain yield and protein content. Our results indicated that a simultaneous improvement of the two traits grain yield and protein content by means of an index seems possible. However, its efficiency largely depends on the weighting of the single traits. The selection for a high GPD would mainly increase the protein content whereas a selection based on protein yield would mainly improve the grain yield. Nevertheless, a combination of different indices allows balancing this selection. Compared to the primary traits grain yield and protein content, the selection indices did not essentially differ in the complexity of their genetic architecture. In bread wheat, we focused on the acrylamide precursor asparagine. Acrylamide is formed in potentially harmful concentrations when cereals are treated with high temperatures over a long period during the processing to food products. A promising strategy to reduce the acrylamide formation would be to decrease the precursors in the raw material. The wide range of variation for asparagine content showed that variety selection might have a large influence on the occurrence of acrylamide in the final product. In addition, the moderately high heritability suggested that successful breeding for lower asparagine content is possible. This conclusion is supported by the observation of no strong negative correlations between asparagine content and a number of other important traits. The genome-wide association mapping resulted in the detection of eight putative QTL, which jointly explained 78.5% of the genetic variance. A putative QTL on chromosome 7B explained with, 18.4%, the highest proportion of the genetic variance for a single marker. For spelt wheat, we assessed a high number of quality traits but placed a special emphasis on the flavor and odor of bread produced from 30 different varieties. Interestingly, we observed a significant genetic variation for bread flavor and a heritability estimate of moderate magnitude. This suggests that even for bread flavor a successful selection appears possible. Taken together, for most traits the genome-wide association mapping resulted in the detection of a high number of putative QTL. This indicates a complex genetic architecture, typical for predominantly quantitatively inherited traits. However, few of the putative QTL explained a large proportion of the genetic variance, so that they might have the potential to be used in marker-assisted selection. In order to examine the potential of genomic selection, I performed a five-fold cross validation for the different quality traits. I could confirm previous findings that the integration of QTL information as fixed effects in the genomic prediction model increased the prediction abilities considerably. The average prediction abilities for most traits suggested a high potential for genomic selection in breeding programs. In conclusion or results form a good basis for further research but more importantly already deliver valuable knowledge that can be used as guideline to advance wheat breeding programs for improved quality.

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