Browsing by Subject "Biomass"

Now showing 1 - 20 of 20

Agricultural diversification of biogas crop cultivation
(2018) von Cossel, Moritz; Lewandowski, Iris
For all types of agricultural land-use, more diverse cropping systems are required, with respect to the maintenance of ecosystem values such as biodiversity conservation and climate change adaptation. This need for greater agricultural diversity is clearly illustrated by biogas crop cultivation. In Germany, maize currently dominates biogas crop cultivation due to its outstanding methane yield performance. However, the ecosystem value of maize cultivation decreases if good agricultural practices are ignored. Additionally, the poor aesthetical value of maize has led to biogas production gaining a negative reputation in society. To increase the diversity of biogas crop cultivation, alternative biogas crops such as amaranth and wild plant mixtures need to be investigated with respect to both yield performance and biogas substrate quality. The research objective of this study was the development of strategies for agricultural diversification of biogas crop cultivation. For this purpose, the following research questions were formulated: 1. How does amaranth perform as a biogas crop compared to maize and what are the major opportunities for and obstacles to the large-scale implementation of amaranth cultivation? 2. How does the spatial diversification ‘legume intercropping’ perform in amaranth compared to maize and what are the major opportunities for and obstacles to its practical implementation? 3. How do perennial wild plant mixtures perform in biomass production with respect to yield, quality and species diversity in the long term and what are the relevant agronomic factors? 4. How do available models perform in the prediction of specific methane yield of different crops based on their lignocellulosic biomass composition and how could they be improved? To address research questions 1 and 2, field trials with amaranth and maize were conducted in southwest Germany in the years 2014 and 2015. Amaranth established well in both years. Its dark red inflorescences attracted many insects such as honeybees, wild bees and bumble bees. Therefore, a systematic implementation of amaranth into biogas crop rotations could significantly improve their socio-ecological value in terms of biodiversity conservation and landscape beauty. However, amaranth showed significantly lower dry matter yields (DMY) and specific methane yields (SMY), together resulting in lower methane yields than maize in both years. Therefore, breeding and an optimization of agricultural practices such as sowing density, planting geometry and fertilization management are required to make amaranth more competitive in comparison to maize. To address research question 2, the amaranth field trials mentioned above also included treatments of legume intercropping with runner bean (RB, Phaseolus vulgaris L.) and white clover (WC, Trifolium repens, L.). The RB and WC developed equally well in amaranth and maize each year. For both amaranth and maize, the RB share of total DMY was low (5-10%) and did not significantly affect the total DMY. By contrast, WC had a significant negative effect on the DMY. Overall, the spatial diversification ‘legume intercropping’ could considerably improve the socio-ecological value of amaranth cultivation in terms of biodiversity conservation, greenhouse gas (GHG) mitigation and soil protection. For research question 3, two different wild plant mixtures (WPM) were cultivated on three sites in southwest Germany from the years 2011 to 2015. At each location, the WPM showed great potential for both biodiversity conservation and ecosystem resilience. Numerous insect species were observed in the WPM stands each year, indicating WPM as a relevant cropping system for habitat networking. Furthermore, the aesthetic appearance of the WPM stands over the years demonstrated the potential positive effect WPM cultivation could have on the public perception of biogas production. The DMY of the WPM varied strongly depending on (i) the initial composition of species sown, (ii) the establishment procedure, (iii) the environmental conditions, (iv) the pre-crop, and (v) the number of predominant species. WPM were found to have low demands for fertilization and crop protection. Thus, WPM appear a promising low-input cropping system for the promotion of biodiversity conservation, habitat networking, soil and water protection, GHG mitigation and climate change adaptation. However, high DMY gaps remain a challenge for the practical inclusion of WPM in existing biogas cropping systems. With respect to research question 4, a meta-analysis revealed that available models proved to be much less precise than expected. Although outperforming all available models, the correlation of the new models was still low (up to r = 0.66). It was also found that non-linear terms are of less importance than crop-specific regressors including the intercept. This indicates that across-crop models including crop-specific configurations could help to improve the identification of alternative crops and cropping systems for a more diverse biogas crop cultivation in the future.
Biomass production for bioenergy as an interface between yield optimisation, ecology and human nutrition : a question of resource efficiency
(2012) Gauder, Martin; Claupein, Wilhelm
In this thesis, specific questions dealing with sustainability of bioenergy were analysed on regional scales. One focus was put on food security and the connections to bioenergy production. Therefore a study, based on the comprehensive range of information available, was conducted for ethanol production in Brazil. The second focus laid on Europe and the potentials and environmental risks which come along with bioenergy production. A study on interannual yield performance of long-term Miscanthus plantations was conducted to evaluate potentials and genotype diversities of Miscanthus cropping in Southwest Germany. To identify the possible contribution of by-products from agriculture, a third study dealt with amount and distribution of surplus straw in Southwest Germany. Environmental aspects were addressed in a field trial, which monitored trace gas fluxes from soils under different energy plants also in Southwest Germany. The last study examined the potential of establishing large-scale poplar plantations in Romania and how this could contribute to the regional energy security.
Comparative performance of annual and perennial energy cropping systems under different management regimes
(2007) Böhmel, Ute Constanze; Claupein, Wilhelm
The theme of this thesis was chosen against the background of the necessary substitution of fossil fuels and the need to reduce greenhouse gas emissions. One major solution for these topics may be the energy generation from domestically produced biomass. The overall aim of this thesis was the identification of one or more efficient energy cropping systems for Central Europe. The target was set to supply high quality biomass for existent and currently developing modern conversion technologies. Renewable energy production is thought to be environmentally benign and socially acceptable. The existence of diverse production environments necessitates further diversification and the identification of several energy crops and the development of energy cropping systems suited to those diverse environments. This thesis starts with an introductory essay (chapter 1), which provides the background for renewable energy production, its features, demands and potentials, and the scientific basis of this thesis. Chapters 2 to 6 consist of five manuscripts to be published in reviewed journals (Papers I, II, IV and V) or in a multi-author book (Paper III). Subsequently, the results from all papers are discussed in a general setting (chapter 7), from which a general conclusion is formulated (chapter 8). The basis of the research formed four field experiments, which were conducted at the experimental sites Ihinger Hof, Oberer Lindenhof and Goldener Acker of the University of Hohenheim, in south-western Germany. Paper I addresses the overall objective of this thesis. Selected cropping systems for this experiment were short rotation willow, miscanthus, switchgrass, energy maize and two different crop rotation systems including winter oilseed rape, winter wheat and winter triticale with either conventional tillage or no-till. The systems were cultivated with three different nitrogen fertilizer applications. An energy balance was calculated to evaluate the biomass and energy yields of the different cropping systems. Results indicate that perennial lignocellulosic crops combine high biomass and net energy yields with low input and potential ecological impacts. Switchgrass, which produced low yields at the study site, may better perform on marginal sites. Switchgrass is an example of the need to grow site-adapted energy crops. The annual energy crop maize required the highest input, but at the same time yielded the most. The two crop rotation systems did not differ in yield and energy input, but the system with no-till may be more environmentally benign as it has the potential to sequester carbon. The objective of Paper II was the optimization of crop cultivation through the differentiation of input parameters to enhance the quality of the energy crop triticale, without influencing the biomass yield. The intention was to minimize the content of combustion-disturbing elements (potassium and chlorine) and the ash residue of both aboveground plant parts (grain and straw). It was done through different straw and potassium fertilizer treatments. It could be shown that the removal of straw from the previously cultivated crop and no additional potassium fertilizer could reduce the amount of combustion-disturbing elements. A high influence must also be expected from site and weather conditions. Papers III to V address the supply of different high quality biomasses, with the focus on maize for anaerobic digestion. The objective of Paper III was the assessment of the requirements of biogas plants and biomass for anaerobic digestion. It introduces potential energy crops, along with their advantages and disadvantages. Alongside maize, many other biomass types, which are preserved as silage and are high in carbohydrates and low in lignocelluloses, can be anaerobically digested. The development of potential site-specific crop rotation systems for biomass production are discussed. The objective of Papers IV and V was the identification of suitable biomass and production systems for the anaerobic digestion. The focus lay on the determination of (i) suitable energy maize varieties for Central Europe, (ii) optimal growth periods of energy crops, (iii) the influence of crop management on quality parameters and (iv) environmentally benign crop rotation systems. Differently maturing maize varieties were grown in six different crop rotation systems (continuous maize with and without an undersown grass, maize as a main crop partially preceded by different winter catch crops and followed by winter wheat) and tested at two sites. Additional factors were sowing and/or harvest dates. Maize and cumulative biomass yields of the crop rotation systems were compared. Specific methane yield measurements were carried out to evaluate the energy performance of the tested crops. Quality was assessed either by measurements of the dry matter content or by using the near infrared reflectance spectroscopy for the determination of chemical composition. Results indicate that an environmentally benign crop rotation system requires nearly year-round soil cover to minimize nitrogen leaching. This can be achieved through the cultivation of undersown or catch crops and additional main crops alongside maize, such as winter wheat. Late maturing maize varieties can be cultivated at a site where the maize can build adequate dry matter contents due to a long growth period (late harvest date). The energy generation in terms of methane production was primarily dependent on high biomass yields. It could be further shown that the specific methane yield of maize increased with increasing starch content, digestibility and decreasing fiber content. To conclude, selected site-specific energy crops and crop rotation systems, with suitable crop management, (fertilizer and soil tillage) can produce high quality biomass and the highest net energy return. Lignocellulosic biomass can be optimized for combustion. Wet biomass is an optimal substrate for anaerobic digestion. Profitable energy production is characterized by a high land and energy use efficiency and especially high net energy yields.
Continuous synthesis of 5‐hydroxymethylfurfural from biomass in on‐farm biorefinery
(2022) Świątek, Katarzyna; Olszewski, Maciej P.; Kruse, Andrea
5‐hydroxymethylfurfural (HMF) is the object of extensive research in recent times. The challenge in the industrial production of HMF is the choice of cheap, hexose feedstock. This study compares continuous HMF synthesis from hexoses—fructose and glucose, and biomass—Miscanthus × giganteus and chicory roots. The experiments were conducted in technical‐scale biorefinery (TRL 6/7). In the first stage, optimal conditions for the production of HMF from hexoses were selected using sulfuric acid as a catalyst in an aqueous medium. The following conditions were chosen for fructose: temperature of 200°C, the reaction time of 18 min, and pH = 2, and for glucose: 210°C, 18 min, and pH = 3. Under these conditions, the HMF yield was 56.5 mol% (39.6 wt.%) from fructose and 18.1 mol% (12.6 wt.%) from glucose. From the biomass, the HMF yields were 36.7 and 16.2 wt.% for miscanthus and chicory roots, respectively. Some results from the conversion of biomass solutions are unexpected and show a need for further investigations. This work has demonstrated the capacity to produce HMF from biomass as part of an environmentally friendly process in a biorefinery. Further research in this field and process optimization will be a step forward in the sustainable production of bioplastics.
Cover cropping in integrated weed management
(2018) Sturm, Dominic; Gerhards, Roland
Weed control constitutes a major challenge in the worldwide crop production. Beside chemical and mechanical weed control strategies, cover cropping provides an effective way of biological weed suppression. Five different field experiments were conducted at six locations from 2014-2016 to evaluate the weed control efficacy of different cover crops in mono and mixed cultivation combined with different fertilization strategies and sowing dates. Furthermore weed suppressing effects of cover crop mulches in spring and of living mulches in summer were investigated. Potential effects on sugar beet emergence, quality and quantity were also assessed. In three laboratory and two greenhouse experiments from 2015-2017, the proportional contribution of competitive and biochemical effects on the overall weed suppression and the identification of varying susceptibilities of different weeds against biochemical stresses were at the center of research. In field experiments, the weed suppressive effects of cover crops and living mulches in mono and mixed cultivation were tested. The experiments emphasized the importance of cover crop and living mulch mixtures compared to mono cropping due to a higher flexibility to biotic and abiotic stresses. This was followed by a more constant biomass production and more effective weed suppression. Moreover, the observed weed control was a result of competitive and biochemical effects, induced by cover crops. These were later on analyzed for active weed growth suppressing compounds. Altering cover crop sowing date and fertilization to optimize the weed control resulted in significant changes of cover crop and weed biomass. Early cover crop sowing five or three weeks before winter wheat harvest increased the weed control efficacy in one year, significantly. Due to contrary results over the two experimental years, we suggest that the cover crop biomass and consequently the weed suppressive ability depends on sufficient soil water for rapid cover crop germination and growth. The use of cover crop mulch in sugar beet crops provided a weed suppression of up to 83%. Especially mulch derived from cover crop mixtures reduced the weed density (56%) more effectively compared to mono cultivated cover crops (31%). The inclusion of cover crops, mulches and living mulches can lead to significant herbicide reductions in the main crop. However supplementary mechanical or chemical weed control strategies are still necessary, especially in crops with a low competitive ability like sugar beets. Nevertheless, novel mechanical weed control approaches and adequate herbicide application techniques, as band-spraying, can reduce the herbicide input in the long-term. Germination tests with aqueous cover crop extracts were conducted on weed seeds to evaluate differences in the inhibition of germination and root growth. Furthermore, different sensitivities of the weeds against the different cover crop extracts were revealed. Some cover crops as S. alba, F. esculentum, H. annuus, T. subterraneum and L. usitatissimum showed the most effective weed suppression. Moreover, the weed M. chamomilla showed the highest susceptibility against biochemical stresses in the germination tests. A strong positive correlation between the weed suppressive effects by the extracts and the field weed suppression was found. This indicated that biochemical effects play also an important role on the overall weed suppression in the field. To estimate the proportions of competitive and biochemical effects on the overall weed suppression by cover crops, greenhouse experiments with active carbon supplemented soil were conducted. These experiments revealed that biochemical effects, by the presence of active carbon in the soil, shifted the balance of competition between cover crops and weeds. In the course of the experiments, we also found species-specific effects on the donor as well as on the receiver side. The results of this thesis demonstrate the diverse use of cover crops, their mulches and living mulches in agricultural systems. This work aims on the optimization of biological weed control strategies and indicates approaches for future research. It is for example not yet clear how cover crops suppress specific weeds and if it is possible to design combinations of specific cover crops for the suppression of individual weed communities. Additionally, these results help to reduce long-term herbicide inputs in agricultural systems.
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.
Effects of woody plants and their residues on crop yield, weedsand soil carbon fractions in selected arable cropping systems
(2018) Xu, Jialu; Gruber, Sabine
Gehölze können auf Ackerflächen zu Produktionszwecken angebaut werden (z.B. Bäume zur Biomasseproduktion) oder dienen als Feldgrenzen (z.B. Hecken). Gehölzpflanzen auf Ackerflächen wirken sich dabei positiv auf die Biodiversität aus, verringern die Bodenerosion sowie die Nitratauswaschung und haben einen positiven Einfluss auf die Trinkwasserqualität. Des Weiteren tragen sie zu einer Zunahme der organischen Bodensubstanz und zur Kohlenstoffsequestrierung im Boden bei und leisten damit einen Beitrag zum Klimaschutz. Die Gehölzpflanzen selber und auch deren Rückstände wie z.B. Häckselgut von Hecken können aber auch ungewünschte Auswirkungen auf die Kulturpflanzen nach sich ziehen, die beispielsweise durch allelopathische Effekte oder durch die Konkurrenz um Ressourcen (z.B. Licht) hervorgerufen werden. In der Vergangenheit fielen Gehölzpflanzen auf Ackerflächen vermehrt der Intensivierung und Mechanisierung in der Landwirtschaft zum Opfer, während heutzutage Bestrebungen bestehen, deren Zahl zu erhalten, um Ökosystemleistungen zu sichern. Das Ziel dieser wissenschaftlichen Arbeit war, Wechselwirkungen zwischen Pflanze und Boden bei ausgewählten Gehölzen sowie deren Ernterückständen auf Ackerflächen zu untersuchen. Die vorgelegte Arbeit besteht aus vier Publikationen und umfasst Labor- und Feldexperimente, die sich zum einen mit den Effekten von Hackschnitzeln aus Heckenrückschnitt auf die landwirtschaftliche Produktion und zum anderen mit dem Vergleich einer Kurzumtriebsplantage mit anderen „Energiepflanzen“ in unterschiedlichen Anbausystemen beschäftigen. In den Untersuchungen werden relevante Aspekte zu Erträgen der Kulturpflanzen, Unkräutern und ausgewählten Bodenparametern herausgegriffen. Die erste Publikation (veröffentlicht im Agronomy Journal) beschreibt Langzeiteffekte der Ausbringung von Hackschnitzeln von Hecken (hauptsächlich Acer pseudoplatanus L., Prunus avium L., Prunus padus L., Salix caprea L., Ligustrum vulgare L., und Fraxinus excelsior L.) auf den Ertrag und den Unkrautbesatz auf einer ökologisch bewirtschafteten Ackerfläche. Hierfür wurden Daten eines 16-jährigen Versuchs auf der ökologisch bewirtschafteten Versuchsstation Kleinhohenheim in Südwestdeutschland gesammelt. Untersucht wurde der Effekt von Hackschnitzelmulch (HSM) auf eine typische Fruchtfolge (Getreide, Leguminosen und Ackerfutter). Die Hackschnitzel stammten vom Rückschnitt der Hecken des Betriebs und wurden jährlich in drei verschiedenen Mengen ausgebracht (0, 80 und 160 m3 ha-1). HSM führte zu einer Reduktion des Unkrautbesatzes um 9 % im Frühjahr, wobei höhere Ausbringungsmengen im Vergleich zu niedrigeren generell in geringerem Unkrautbesatz resultierten. Der Einfluss auf den Ertrag war statistisch nicht signifikant, jedoch wurden über die Versuchszeit tendenziell sinkende Erträge auf mit HSM behandelten Parzellen gegenüber der Kontrolle beobachtet. Die unkrautunterdrückende Wirkung des HSM könnte auf verschiedenen Effekten beruhen, nämlich der mechanischen Behinderung des Auflaufens von Unkräutern, einer geänderten Bodentemperatur, einer reduzierten Stickstoffverfügbarkeit durch die Gabe von Material mit vergleichsweise weitem C:N-Verhältnis sowie allelopathischen Effekten. Hackschnitzel können daher zwar zur Unkrautkontrolle auf Ackerflächen verwendet werden, es müssen jedoch potentiell ungewünschte Effekte auf die Kulturpflanzen berücksichtigt werden. Die zweite Publikation (eingereicht bei Seed Science Research) basiert direkt auf der ersten und beschäftigt sich mit möglichen allelopathischen Effekten von HSM und deren Einfluss auf die Samenkeimung unter Laborbedingungen. Getestet wurden die Auswirkungen wässriger Extrakte von Hackschnitzeln der Salweide (Salix caprea L.) und der Gewöhnlichen Traubenkirsche (Prunus padus L.) auf die Keimung von Raps (Brassica napus L.) und Weizen (Triticum aestivum L.). Ziel dieser Arbeit war die Entwicklung einer standardisierten Extraktionsmethode, wobei die Trocknung (Gefriertrocknung, Ofentrocknung mit 25, 60 oder 105 °C), das Mahlverfahren, das Holz-Wasser-Verhältnis bei der Extraktion (HWV; 1:10, 1:15 oder 1:20) und das Ausgangsmaterial (Rinde oder Kernholz) variiert wurden. Die Extrakte aus der Gefriertrocknung und die des ungetrockneten Holzes führten nach zwei Wochen zu der geringsten Keimrate (<6 %) bei beiden Kulturarten. Die ofengetrockneten Varianten besaßen eine höhere Keimrate von 12 bis 53 %. Die Keimrate von Raps lag bei einer hohen HWV (1:10) mit Extrakten aus gemahlenen Hackschnitzeln der Gewöhnlichen Traubenkirsche bei 26 % und damit signifikant niedriger als mit Extrakten aus ungemahlenem Material (49 % Keimung). Weizenkörner keimten unter diesen Bedingungen in geringerer Anzahl als Raps, aber die Keimung war mit Extrakten aus gemahlenem Material (1%) auch geringer als mit Extrakten aus ungemahlenem Material (19 %). Der Effekt der Keimungsunterdrückung stieg mit erhöhtem HWV bzw. höherer Konzentration der Extrakte. Die Keimraten betrugen durchschnittlich für HWV 1:20 86 %, für HWV 1:15 71 % und für HWV 1:10 35 % mit gemahlenen Hackschnitzeln. Aus der Rinde gewonnene Extrakte führten zu einer signifikant geringeren Keimrate (<4 %) als die des Kernholzes (<88 %). Die effektivste Methode zur Erhaltung offensichtlich allelopathisch wirksamer Verbindungen war die Kombination aus gemahlenen Hackschnitzeln aus Rindenholz, Gefriertrocknung (-50 °C) und einem hohen HWV. Diese hatte den größten Effekt auf die Unterdrückung der Keimung. Die Ergebnisse aus dieser Publikation können zur Untersuchung weiterer Gehölzarten angewandt werden und bieten eine Grundlage für die Auswahl geeigneter Substrate mit einem möglichst hohen allelopathischen Potential zur Unterdrückung von Unkraut. Die dritte Publikation (in Vorbereitung) beschäftigt sich mit der organischen Substanz (OS) beim Anbau mit Gehölzen zur energetischen Nutzung im Vergleich zum Anbau annueller Energiepflanzen auf Ackerland. Untersucht wurde ein 12-jähriger Dauerversuch auf der Versuchsstation Ihinger Hof in Südwestdeutschland mit einer Weiden-Kurzumtriebsplantage (Salix schwerinii E. Wolf x viminalis L.) und einer 12-jährigen Maismonokultur (Zea mays L.). In diesem Versuch wurden Bodenproben im Bereich 0 –10 cm und 10 – 20 cm gezogen. An jeder Probe wurden im Labor eine Dichtetrennung sowie eine Fraktionierung nach Korngröße durchgeführt, und der Kohlenstoffgehalt jeder Fraktion bestimmt. Die Dichtefraktionierung resultierte in einer leichten Fraktion (<1,8 g cm-3), die sich aus freier partikulärer und in Bodenaggregaten eingeschlossener OS „occluded- particulate organic matter“ (f-POM und o-POM) zusammensetzte sowie der schweren Fraktion, bestehend aus drei Klassen verschiedener Partikelgrößen: Sand (63-2000 μm), Lehm (2-63 μm) und Ton (<2 μm). Generell fanden sich höhere Gehalte an OS in der oberen Bodenschicht unter Weiden (1,39 %) als im Maisanbau (1,13 %). Im Boden unter Weiden war die leichte Fraktion (f-POM und o-POM) um 154 % höher als beim Maisanbau. Grund dafür war der kontinuierliche Zufluss von Streu und von Wurzelresten sowie die fehlende Bodenbearbeitung. Ebenso war das C:N Verhältnis der OS in den Sandfraktionen unter Weide (28, 24 und 16) höher als unter Mais (23, 18 und 9). Die Ergebnisse deuten auf einen langsamen Umsatz von OS und damit auf ein höheres Kohlenstoffsequestrierungspotential unter Weiden in Kurzumtriebsplantage als beim Maisanbau hin. Die vierte Publikation (veröffentlicht im Agronomy Journal) nutzt denselben 12-jährigen Feldversuch wie die dritten Publikation. Es erfolgte eine Bewertung des Biomasse- und des Bruttoenergieertrags von sechs annuellen und perennierenden Energiefruchtfolgen mit verschiedenen Stickstoffdüngungsstufen. Die annuellen Systeme bestanden aus Mais in Monokultur mit reduzierter Bodenbearbeitung; einer Fruchtfolge mit Raps (B. napus L. ssp. oleifera) – Weizen (Triticum aestivum L.) – Triticale (Triticale x triticosecale Wittmack) mit wendender bzw. keiner Bodenbearbeitung. Die perennierenden Systeme umfassten eine Kurzumtriebsplantage mit Weiden (S. schwerinii E. Wolf x viminalis L.), Miscanthus (Miscanthus x giganteus Greef et Deu.) und Ruthenhirse (Panicum virgatum L.). Für jedes Anbausystem wurden drei Stickstoffdüngungsstufen (0, 50 und 100 % der praxisüblichen Düngemenge) etabliert. In Mais wurde im Mittel der höchste jährliche Biomasseertrag festgestellt (18,5 Mg ha-1), gefolgt von Miscanthus (18,3 Mg ha-1) jeweils bei einem N-Düngeniveau von 100 %. Ohne Stickstoffdüngung lag der jährliche Biomasseertrag bei Miscanthus mit 13,6 Mg ha-1 am höchsten. Das hohe Ertragsniveau konnte bei beiden Kulturen über die 12-jährige Versuchslaufzeit nur mit der höchsten N-Düngerstufe gehalten werden. In den Fruchtfolgen und bei Rutenhirse sanken die Erträge über die Jahre auch mit hoher Stickstoffgabe. Je geringer die Stickstoffdüngung ausfiel, desto stärker war der Ertragsrückgang. Die Weiden in Kurzumtriebsplantage zeigten unabhängig von der Stickstoffdüngung und der Versuchslaufzeit im Mittel gleichbleibende Erträge von 11 Mg ha-1. Offenbar ist die Stickstoffdüngung für Weiden in Kurzumtriebsplantagen im Vergleich zu den anderen untersuchten Kulturen und Anbausystemen ein weniger wichtiger Produktionsfaktor. Das Ausbringen von Hackschnitzel von Hecken auf Ackerflächen und der Anbau von Gehölzpflanzen (Weide in Kurzumtriebsplantage) zeigten Effekte im oberirdischen Pflanzenaufwuchs und hatten Auswirkungen auf die Bodeneigenschaften. Gewünschte Auswirkungen der Managementmaßnahmen waren (i) die Verringerung des Unkrautbesatzes, (ii) der geringe Stickstoffinput für eine zufriedenstellende Produktivität von Weiden in Kurzumtriebsplantage, und (iii) und die Erhöhung der OS (Kohlenstoffsequestrierung). Unerwünschte Effekte äußerten sich in der tendenziellen Reduktion der Biomasseproduktion der Kulturpflanzen Wie die Studie zu Extrakten aus den Hackschnitzeln zeigt, scheinen tatsächlich allelopathische Effekte eine mögliche Ursache für die Unkrautunterdrückung bei der Hackschnitzelapplikation zu sein. Diese oder ähnliche Effekte könnten auch nach der Rodung von Kurzumtriebsplantagen auf die Nachfrüchte auftreten, z.B. aus Rückständen von Wurzeln und Stamm. Weiterhin könnte beim Erhalt von Heckenbiotopen auch mit einer Kohlenstoffsequenzierung gerechnet werden, ähnlich wie es bei den Weiden in Kurzumtriebsplantage gezeigt wurde. Die günstigen Effekte des Anbaus von Gehölzen könnten Landwirte motivieren, Gehölzpflanzen auf ihren Ackerflächen zu belassen bzw. zu etablieren und die Ökosystemleistungen auf dem Betrieb zu erhöhen. Weiterführende Forschung könnte darauf abzielen (i) technische Lösungen für eine praktikable Hackschnitzelausbringung zur Unkrautbekämpfung zu finden, (ii) die allelopathisch wirksamen Substanzen von Gehölzen zu identifizieren und zu isolieren und so gegebenenfalls Grundlage für eine neue Generation von Herbiziden zu schaffen, (iii) Langzeitfolgen von Ernterückständen nach dem Anbau von Kurzumtriebsplantagen auf die nachfolgenden Kulturen zu untersuchen, und (iv) Studien zur C-Sequestrierung unter naturnahen Hecken vorzunehmen.
Impacts of carbon dioxide enrichment on landrace and released Ethiopian barley (Hordeum vulgare L.) cultivars
(2021) Gardi, Mekides Woldegiorgis; Malik, Waqas Ahmed; Haussmann, Bettina I. G.
Barley (Hordeum vulgare L.) is an important food security crop due to its high-stress tolerance. This study explored the effects of CO2 enrichment (eCO2) on the growth, yield, and water-use efficiency of Ethiopian barley cultivars (15 landraces, 15 released). Cultivars were grown under two levels of CO2 concentration (400 and 550 ppm) in climate chambers, and each level was replicated three times. A significant positive effect of eCO2 enrichment was observed on plant height by 9.5 and 6.7%, vegetative biomass by 7.6 and 9.4%, and grain yield by 34.1 and 40.6% in landraces and released cultivars, respectively. The observed increment of grain yield mainly resulted from the significant positive effect of eCO2 on grain number per plant. The water-use efficiency of vegetative biomass and grain yield significantly increased by 7.9 and 33.3% in landraces, with 9.5 and 42.9% improvement in released cultivars, respectively. Pearson’s correlation analysis revealed positive relationships between grain yield and grain number (r = 0.95), harvest index (r = 0.86), and ear biomass (r = 0.85). The response of barley to eCO2 was cultivar dependent, i.e., the highest grain yield response to eCO2 was observed for Lan_15 (122.3%) and Rel_10 (140.2%). However, Lan_13, Land_14, and Rel_3 showed reduced grain yield by 16, 25, and 42%, respectively, in response to eCO2 enrichment. While the released cultivars benefited more from higher levels of CO2 in relative terms, some landraces displayed better actual values. Under future climate conditions, i.e., future CO2 concentrations, grain yield production could benefit from the promotion of landrace and released cultivars with higher grain numbers and higher levels of water-use efficiency of the grain. The superior cultivars that were identified in the present study represent valuable genetic resources for future barley breeding.
Integration of hyperspectral, genomic, and agronomic data for early prediction of biomass yield in hybrid rye (Secale cereale L.)
(2021) Galán, Rodrigo José; Miedaner, Thomas
Currently, the combination of a growing bioenergy demand and the need to diversify the dominant cultivation of energy maize opens a highly attractive scenario for alternative biomass crops. Rye (Secale cereale L.) stands out for its vigorous growth and increased tolerance to abiotic and biotic stressors. In Germany, less than a quarter of the total harvest is used for food production. Consequently, rye arises as a source of renewables with a reduced bioenergy-food tradeoff, emerging biomass as a new breeding objective. However, rye breeding is mainly driven by grain yield while biomass is destructively evaluated in later selection stages by expensive and time-consuming methods. The overall motivation of this research was to investigate the prospects of combining hyperspectral, genomic, and agronomic data for unlocking the potential of hybrid rye as a dual-purpose crop to meet the increasing demand for renewable sources of energy affordably. A specific aim was to predict the biomass yield as precisely as possible at an early selection stage. For this, a panel of 404 elite rye lines was genotyped and evaluated as testcrosses for grain yield and a subset of 274 genotypes additionally for biomass. Field trials were conducted at four locations in Germany in two years (eight environments). Hyperspectral fingerprints consisted of 400 discrete narrow bands (from 410 to 993 nm) and were collected in two points of time after heading for all hybrids in each site by an uncrewed aerial vehicle. In a first study, population parameters were estimated for different agronomic traits and a total of 23 vegetation indices. Dry matter yield showed significant genetic variation and was stronger correlated with plant height (r_g=0.86) than with grain yield (r_g=0.64) and individual vegetation indices (r_g: =<|0.35|). A multiple linear regression model based on plant height, grain yield, and a subset of vegetation indices surpassed the prediction ability for dry matter yield of models based only on agronomic traits by about 6 %. In a second study, whole-spectrum data was used to indirectly estimate dry matter yield. For this, single-kernel models based on hyperspectral reflectance-derived (HBLUP) and genomic (GBLUP) relationship matrices, a multi-kernel model combining both matrices, and a bivariate model fitted also with plant height as a secondary trait, were considered. HBLUP yielded superior predictive power than the models based on vegetation indices previously tested. The phenotypic correlations between individual wavelengths and dry matter yield were generally significant (p < 0.05) but low (r_p: =< |0.29|). Across environments and training set sizes, the bivariate model yielded the highest prediction abilities (0.56 – 0.75). All models profited from larger training populations. However, if larger training sets cannot be afforded, HBLUP emerged as a promising approach given its higher prediction power on reduced calibration populations compared to the well-established GBLUP. Before its incorporation into prediction models, filtering the hyperspectral data available by the least absolute shrinkage and selection operator (Lasso) was worthwhile to deal with data dimensionally. In a third study, the effects of trait heritability, as well as genetic and environmental relatedness on the prediction ability of GBLUP and HBLUP for biomass-related traits were compared. While the prediction ability of GBLUP (0.14 - 0.28) was largely affected by genetic relatedness and trait heritability, HBLUP was significantly more accurate (0.41 - 0.61) across weakly connected datasets. In this context, dry matter yield could be better predicted (up to 20 %) by a bivariate model. Nevertheless, due to environmental variances, genomic and reflectance-enabled predictions were strongly dependant on a sufficient environmental relationship between data used for model training and validation. In summary, to affordably breed rye as a double-purpose crop to meet the increasing bioenergy demands, the early prediction of biomass across selection cycles is crucial. Hyperspectral imaging has proven to be a suitable tool to select high-yielding biomass genotypes across weakly linked populations. Due to the synergetic effect of combining hyperspectral, genomic, and agronomic traits, higher prediction abilities can be obtained by integrating these data sources into bivariate models.
Management of excess standing biomass in Argentinean grasslands to increase grass and livestock productivity
(2016) Kurtz, Ditmar Bernardo; Asch, Folkard
Grasslands are the main source of feed for cattle in Argentina. Standing dead biomass (SDB) accumulation threatens efficient resource use. To reduce dead biomass pools in Northern Argentinean rangelands, high impact grazing (HIG) was proposed as an alternative to both, mechanical elimination and the use of fire. However, the effects of HIG on grasslands’ biomass accumulation, diversity and forage quality are unknown. The effect and timing of HIG by cattle was therefore studied in grasslands of North Eastern Argentina. We introduced HIG monthly, on adjacent paddocks over the course of the year and its effects were studied for 12 months following the treatment. Dynamics of biomass re-growth, accumulation of green and standing dead biomass were studied. Additionally, the effects of HIG on plant species composition and the forage quality parameters were monitored and evaluated. The immediate effect of HIG was the reduction of the standing biomass by more than 95%. HIG generally improved the green to total biomass ratio and reduced the overall biomass in the paddocks. All sub-plots subjected to HIG showed a growth pattern anti-cyclic to control, with an active growth phase during autumn when the biomass in the control sub-plots decreased. Best results in terms of SDB reduction and dead to green biomass ratios were achieved after HIG in winter. HIG in autumn, however, reduced fodder availability and reduced from then on, grasslands productivity. Irrespective of the season HIG was applied, the grassland recovered completely with regard to species richness and diversity, the Shannon-Wiener diversity index (H) and the Shannon’s equitability index (E) did not reveal any difference within 12-month period after HIG. Our results suggest that HIG is not shifting plant species composition to a more ruderal strategy based plant community, but instead promotes previously established rather competitive and higher value fodder species. Our results indicate that HIG improves the nutritive value of the green biomass due to increased crude protein (CP), digestible organic matter (DOM), and (metabolizable energy) ME, but if applied in summer it has no evident positive effect. On an area basis, grassland subjected to HIG provided enough monthly ME and CP to meet the requirements of the current stocking density in Corrientes. HIG could be an alternative management practice, to fire and other mechanical SDB elimination, towards sustainable intensification. However, we are aware that long-term observations with repeated HIG should be analysed to detect possible delayed effects and interactions especially with seasonal variability.
Ökonomische Bewertung der „Doppelernte“ von Getreidekörnern mit den Reststoffen Spreu und Stroh
(2021) Ortmaier, Jörg; Köller, Karlheinz
Objective of this work is an economic evaluation of new harvesting methods, so-called “dual- harvesting” methods for common harvesting of grains and their residual biomass. In detail, the aim is on the one hand to evaluate the predicted higher quality and quantity per hectare of har-vestable residual biomass such as chaff and straw that can be realized with dual-harvesting technologies, but on the other hand especially their additional income contrasted to the pro-cess costs by proceeding dual-harvesting. For this purpose, combine harvesting with additional chaff or straw harvesting is compared to some dual-harvesting methods, both in terms of process technology and in monetary terms. Dual-harvesting methods are simulated with self-propelled forage harvester threshing, forage wagon windrow harvesting, compact harvesting and harvesting with a tractor mounted stripper header. The comparison includes the required logistic-chains and crop aftertreatment, i.e. sta-tionary separation of grain and biomass for each method. As basis for calculations is done specific modeling, e.g. for chaff yields and crop volumes as a function of grain yield. Parame-ters such as area size are included and also field distance, loss times, e.g. for turning opera-tions in the field, working speeds and road transport speeds. A calculation model developed for this purpose calculates time required for harvesting of one field for all processes with the greatest possible comparability. Based on machine costs stored in databases, e.g. for depreci-ation or wear and repair, which are automatically transferred to their desired process calcula-tion via selection lists, the costs per operating hour and, including area per hour and area size, costs per hectare can be determined for each harvesting process. Since all processes have different levels of grain and biomass losses, the process-specific, total revenues for grain and biomass are calculated accordingly and process costs calculated in each case are deducted from them. The resulting harvest cost free outputs (HCFO) are used as a comparative value. Without taking into account costs of reproducing soil organic matter as long term result, the following HCFO result for the individual methods according to the assumptions are calculated: combine threshing with bale harvesting 1309.93 €/ha; compact harvesting 1285.66 to 1529.53 €/ha depending on the amount of straw harvested; forage harvester threshing 1421.04 €/ha; forage wagon swath harvesting 1429.40 €/ha; tractor-mounted stripper header 1279.58 €/ha. The compact harvesting method thus has an advantage of up to 219.60 €/ha over the estab-lished combine and bale technology with same given assumptions. The other methods are in between or slightly below the combine harvesting. If costs for nutrient removal and soil organic matter reproduction are included for long term perspective, the advantage of compact harvest-ing is up to 143.44 €/ha. Based on literature research and model calculations, it can be assumed with a high degree of probability that dual-harvesting methods actually make residual materials usable in greater quantities with higher quality than it is possible with widely used combine harvesting. Concerns expressed by Buchmann (1961) and Garmasch (1960) regarding the suitability of combine harvesting for an efficient provision of chaff and straw are substantiated when calculation re-sults are taken into account. In addition, agronomic effects of dual-harvesting methods are positive compared to combine harvesting, which was not able to be evaluated in monetary terms and therefore represents a great need for future research. The positive assessment is due to improved field hygiene by removing weed seeds and plant pathogens from the field during dual-harvest. This could re-duce the need for chemical pesticides. Use of cereal residues not only improves resource effi-ciency and "saves" land for cultivation of renewable raw materials, but the carbon contained in chaff and straw remains bound in sustainable products to a greater extent, such as in biochar. Dual-harvesting is an essential tool for cost-effective provision of plant residues required for that purpose and at the same time offers great potential for more environmentally friendly field management and benefits for biodiversity, e.g. through possibility of regular cultivation of plant mixtures instead of individual crops. Digital development up to autonomous field management can be made more rational in dual-harvesting methods through simplified processes in the field, which can be expected to lead to further increases in efficiency of grain and residue har-vesting in the future.
Phenotypic and molecular analyses of grain and biomass productivity under irrigated and rainfed conditions in hybrid rye
(2014) Gottwald, Marlen; Miedaner, Thomas
Rye (Secale cereale L.) is a small grain cereal used for bread making, livestock feeding and as renewable energy source. These types of usages are leading to different breeding goals. Rye growing regions are affected by climate change and consequently by drought. Germany is touched by rainless periods in spring and early summer in the last years. Again, in spring 2012 farmers in Brandenburg and Lower Saxony were affected by drought periods. Yield losses in those regions, especially in combination with sandy soils are expected. Therefore much attention is paid for breeding of drought resistant germplasm. Briefly, our objectives of this study were to (1) estimate the biomass and biogas potential of different plant materials, their quantitative genetic parameters and biogas-related traits, (2) analyze two recombinant inbred lines and differences in their yield potential between irrigated and rainfed regime, as well as the relative efficiency for indirect selection for drought resistance in irrigated regime, and (3) investigate the phenotypic performance for ten agronomic and quality traits across multiple environments and estimated the number and effects underlying QTL. For the biomass-/ biogas analyses a wide range of plant material was analysed. Germplasm resources, full-sib families selected for grain and forage use were tested for their per se and testcross performance and experimental hybrids selected for grain use and population cultivars selected for grain and forage use were analyzed. Dry matter yields varying across environments from 106 to 177 dt/ha for per se and testcross performance, respectively. For testcross performance, germplasm resources showed similar values to forage rye. The later the maturity stage, the more dry matter yield on the whole plant level was achieved. Estimates of genotypic variances for biomass yield were significant for all rye materials, whereas the variances per se and for testcrosses were for germplasm resources exorbitant higher than for forage and grain rye. Typical cumulative methane production curves were obtained for the whole plant material from the Hohenheim biogas yield test. Methane yield showed large differences between second and third harvest date for individual plant fractions. Differences between genotypes were not substantial for methane yield although significant in some instances. At EC77/83 hybrids and forage rye reached similar methane yield of about 5000 m3/ha. A high correlation between dry matter yield and methane yield was observed (r=0.95). Concerning high cost and time consuming analysis of biogas tests, for breeders the main breeding goal should be maximum dry matter yield. Direct selection on dry matter yield should indirect improve methane yield. Two biparental populations were used for the analysis of drought tolerance. The analysis was performed in duplicate. Both populations were grown under irrigated and rainfed regimes. Striking less rainfall compared to long-term precipitation occurred between April and July, during critical phases of plant development. Grain yield reduction between irrigated and non-irrigated regime ranged from 2% to 29.6% for population A and 2% to 40% for population B, whereas differences between both regimes were significant (P<0.05) for five and four environments, respectively. Genotypic variances of grain yield were significant in all instances, whereas genotype by irrigation interaction variance between both regimes being significant only in three and four environments for population A and B, respectively. Analysis across those environments revealed significant difference for genotype by irrigation interaction variance and the three-way interaction variance in both populations. Heritability estimates were higher for the irrigated than for the rainfed regime. High interaction variance with environment and no clustering of the two regimes in a multi-dimensional analysis were found. This illustrates the different soil and whether conditions between locations and additionally every location suffered from a different drought stress. The correlation between both regimes was significant but moderate, but genotypic coefficients considerably higher (Pop-A: 0.86, Pop-B: 0.84), which could be substantiated that testcrosses differed not substantially in drought-resistance. Indirect selection for drought in the irrigated regime was predicted to be equally or more efficient than direct selection in the non-irrigated regime. Phenotypic and genotypic analysis was done across ten environments for both biparental populations for the general improvement of agronomic and quality traits in rye. Population A were genotyped with a Rye5K SNP array and for population B DArT genotyping was done with a 3K rye array. Additionally both populations were genotyped with about 150 SSRs. The genetic linkage maps comprised 1,819 and 1,265 markers for population A and B, respectively and were used for the QTL analysis for ten agronomic and quality traits. Phenotyping revealed large genetic variation for ten agronomic and quality traits. Intensive phenotyping at up to ten environments led to moderate to high heritabilities. Across environments explained genotypic variance of the individual QTL ranged from 5 to 55%. For 1000-kernel weight, test weight, falling number, and starch content, several QTL with high effects and a frequency of recovery of about 90% were identified in both population. Rye suffered from drought stress in the last decade. Focusing on general improvement of rye regarding yield and quality, as well as improving rye regarding drought-resistance is important. Future research should be done in fine mapping and validation of the detected QTLs, for exploiting their potential in marker assisted breeding.
Phenotypic, genetic, and genomic assessment of triticale lines and hybrids
(2017) Losert, Dominik; Würschum, Tobias
Triticale (×Triticosecale Wittmack) is a small grain cereal used for livestock feeding and as renewable energy source. These diverse types of usage lead to different breeding strategies, ideally resulting in continued increase of both, grain and biomass yield. Briefly, the objectives of this thesis were to explore aspects with relevance for line and hybrid breeding in triticale by phenotypic, genetic and genomic assessment of important traits. More specifically, the objectives of this study were to (i) evaluate agronomic traits, assess trait correlations, and investigate the amount of heterosis in triticale hybrids, (ii) examine the potential of line and hybrid cultivars for production of biomass, (iii) assess the phenotypic and genotypic variability in triticale germplasm, (iv) investigate long-term phenotypic trends based on cultivars registered in the past three decades, and (v) identify QTL for agronomical relevant traits. In conclusion, hybrids of triticale possess an increased biomass yield potential compared with their mid-parent values as well as compared with commercial reference cultivars. The findings on triticale germplasm and its breeding history provide important information for breeding programs. Furthermore, based on the obtained results, genomic approaches like marker-assisted or genomic selection appear promising to assist triticale breeding in the future.
Quantitative-trait loci (QTL) mapping of important agronomical traits of the grain and biomass production in winter rye (Secale cereale L.)
(2015) Haffke, Stefan; Miedaner, Thomas
Rye is an important crop in Northern and Eastern Europe and mainly used for food and feed and became most recently important for biogas production. Hybrid rye varieties dominate the cultivated area, which is mainly on light and sandy soils, because rye has a relatively high tolerance to biotic and abiotic stress factors. Climate change will also affect Central Europe, causing higher temperatures and less precipitation in spring and summer. Rye will be influenced more by these effects than other cereals because it is mainly grown on marginal environments. Rye has a high potential for being used as a biogas substrate, but detailed information on improving this trait in hybrid rye is missing. Until now, no study that analyzed phenotypic and genotypic agronomic traits for using rye for biogas production exists. Further, there is only one study, which dealt with the influence of periodic drought stress in rye cultivated areas. Beside this, we analyzed yield stability over a wide range of environments in consideration of drought stress in Central Europe. We analyzed an interpool hybrid population (Pop-D) in 2011 and 2012 at seven environments in Germany for the biomass yield and grain yield (Publication I). This study showed low correlations between grain yield and dry matter yield (r = 0.33). Higher correlations were obtained with two plant height measurements (at heading time, r = 0.64; before harvest, r = 0.52) and dry matter yield. The indirect selection via plant height was superior in contrast to the direct selection of dry matter yield by factor 1.24. Genotypic results confirmed phenotypic results as no overlapping QTL for grain yield and dry matter yield were detected (Publication II). However, we identified common gene regions for plant height and dry matter yield due to the high correlation between both. Plant height is a promising trait for indirectly selecting high biomass yielding varieties. The paradigm shift from shorter plants with high grain yield to taller hybrids as a resource for biogas substrate needs additional breeding efforts for lodging resistance. In Publication III we analyzed two intrapool populations (Pop-A and -B) and one interpool population (Pop-C) at 16 – 18 environments (location x year combinations) under irrigated and rainfed conditions in Germany and Poland. Yield stability was high over a wide range of environments, even when drought stress environments were included. This illustrates the adaption of rye to marginal and drought stress environments. The analyzed populations showed no differences within yield stability, but yield differences between inter- (Pop-C) and intra-pool (Pop-A and -B) crosses were visible. Selection for yield stability is possible due to the genetic variance for this trait within all three populations. Therefore, it is important to select genotypes with low genotype x environment interaction. All three populations showed high yield stability on a high yield level and were already well adapted to extreme weather events caused by climate change. It is recommended to use highly diverse environments with irrigated and rainfed conditions to select on yield stability and high yielding varieties under optimum and drought conditions
Soil moisture dynamics in integrated crop - livestock - forestry systems in the Cerrado Biome in Central - West Brazil
(2021) Glatzle, Sarah; Asch, Folkard
The Cerrado biome in Brazil covers about 200 million ha and is a global biodiversity hotspot. Over the last decades, the Cerrado biome underwent and is still undergoing an excessive expansion in agriculture. Deforestation and replacement of the natural Savannah vegetation by cropland and pasture contributes to serious environmental problems, including soil degradation and altered water cycles. The integrated crop-livestock-forestry (ICLF) system is currently promoted as a measure for sustainable intensification. It improves the use of cultivated areas, recovers previously degraded land, and could be a strategy for adapting agriculture to climate change. Despite being considered a key indicator of how integrated systems affect ecological processes, soil moisture (SM) dynamics in literature have not been consistently analyzed, and continuous observation of seasonal SM dynamics are mostly unaddressed. Since SM of complex ecosystems is influenced by numerous factors, several additional parameters need to be considered to create a comprehensive understanding of the interlinked processes, such as radiation, rainfall, and biomass. The objective of this cumulative PhD thesis was to investigate SM dynamics and aboveground grass biomass under different land use systems in the Cerrado biome of Central West Brazil. In the first study, photosynthetically active radiation (PAR) received at grass canopy level, SM, AGBM between the tree rows, and seasons in a mature ICLF system were investigated. Across the seasons, a distinct gradient was observed with SM being lower close to the tree rows than in the space between them. During winter, SM in the topsoil decreased to critical values, and dropped to the permanent wilting point next to the tree rows. During spring and summer, incident PAR was lower close to the trees than at the center point, while during autumn and winter, when PAR is generally lower, it was more evenly distributed between the tree rows. Aboveground grass biomass (AGBM) showed a distinct distribution within the ICLF system with maximum values in the center and about 50% of the biomass close to the tree rows. The results suggest that, restrictions in AGBM accumulation shifted among seasons between water limitations in winter and light limitations during summer. In the second study, the seasonal and spatial variability of SM of Cerrado soils under four different land use systems was investigated under consideration of soil physical characteristics and grass biomass. In rainy and dry season, SM in the upper 100 cm of the soil was highest in the integrated crop-livestock (ICL) system, followed by the continuous pasture (COP), and lowest in the land use systems including trees, ICLF and Cerrado. Whereas in COP and in ICL, water was mainly taken up from the upper 30 cm, in ICLF, the strongest soil moisture depletion was observed between a soil depth of 40 and 100 cm. Although in the Cerrado SM in the topsoil was lower than in the other land use types, water was conserved below 60 cm depth. Both integrated systems improved soil properties, such as bulk density and soil organic carbon compared to COP, and increased biomass productivity was observed, demonstrating the benefits of the integrated systems over the traditional grazing system. The results suggest that ICLF systems show increased evapotranspiration compared to conventional pasture and other integrated systems without trees. In the third study, the effects of the presence of eucalyptus trees on the seasonal pasture and animal performance in ICLF systems 8 years after establishment were investigated. Forage morphology, production, and nutritive value plus performance of Nellore heifers in two ICLF systems with varying in trees density, were evaluated and compared with a grass-only pasture. In both ICLF systems, the forage nutritive values were improved compared with a grass-only pasture. Nevertheless, grass biomass and accumulation rate were higher in the grass-only pasture. By the 8th year, the ICLF systems were unable to support both forage and animal production equivalent to a grass-only pasture, due to the high impact of the Eucalyptus trees on radiation received at the grass canopy and on soil moisture. Improved soil characteristics and forage nutritive values compared to grass-only pastures, and the potential restoration of natural ecosystem functions regarding water recycling into the atmosphere, demonstrated the benefits of ICLF systems and highlight their potential to contribute to sustainable agricultural intensification. However, high water consumption by trees poses a risk to grass productivity during the dry season and thus, the system may consequently not be used for grazing all year round. Therefore, research on management options mitigating the impact of drought on grass productivity is needed. As the impact of the trees on the system is highly dependent on their age, these studies should consider the entire life cycle of the system.
Sustainable bioenergy cropping concepts : optimizing biomass provision for different conversion routes
(2014) Mast, Benjamin; Claupein, Wilhelm
Today energy from biomass already contributes to a considerable share to the global energy consumption. In particular, certain modern bioenergy streams like biogas, biofuels for transportation etc., are of increasing relevance. However, several of the beneficial aspects, which were initially attributed to the utilization of today’s bioenergy, had to be relativized and the controversies regarding environmental and socio-economic drawbacks have, in the meanwhile, been on the rise. Alongside a shift to advanced conversion technologies, the improvement of bioenergy cropping systems towards a sustainable biomass provision is a key element of future bioenergy production. Against this background, the present thesis assessed various aspects in terms of biomass production, biomass provision and biomass conversion mainly addressing the two bioenergy streams – 2nd generation biofuels and biogas. For biogas, the thesis addresses aspects regarding the development of alternative cropping systems, the evaluation of novel crops for biogas purpose, and the assessment of regional biogas potentials using a crop growth model. The second focus of the thesis was set on biofuels while special attention was given to the production of microbial biodiesel, and the characterization and evaluation of potential feedstocks for this purpose.
The effect of enzyme additives on the anaerobic digestion of energy crops
(2014) Brulé, Mathieu; Jungbluth, Thomas
The mechanisms governing the efficiency of commercial fiber-degrading enzyme additives at improving the anaerobic digestion of energy crops were investigated. Standard batch digestion trials (BMP-assays) were performed using the Hohenheim Biogas Test (HBT) on maize straw, maize corn, and rye silage with different inocula. These BMP-assays showed no significant effect of enzyme additives (including commercial cellulase, xylanase, pectinase, laccase) on the methane production rate. However, batch digestion trials performed on grass silage under suboptimal conditions with inoculum of weak bacterial activity revealed significant increases of methane production up to 40%. In another experiment semi continuous acidogenic fermentation was performed in laboratory digesters with maize silage and water added for dilution at OLR 4 kg VS/(m3 × d), HRT 5 days, with the medium kept in the pH range 5 5.5 through quicklime addition. Enzyme additives at a dosage of 10 g/kg substrate VS significantly increased VFA release (+10%) as well as gas production, including H2 production (+20%). The results show that the efficiency of enzyme additives in anaerobic digestion depends on substrate (fibre length and composition) and process parameters (retention time, loading rate, pH, efficiency of bacterial substrate degradation).
The role of institutions and networks in developing the bioeconomy : case studies from Ghana and Brazil
(2019) Scheiterle, Lilli; Birner, Regina
An increasing number of countries have begun putting focus on developing a bioeconomy strategy. The bioeconomy provides a new concept with the aim to design a sustainable economy, which is knowledge-based and based on the use of biological resources. This entails on the one hand higher production of biomass and on the other tighter networks of traditional, national and international institutions. Institutional networks are pivotal for the sustainable production and use of biological resources, as well for the development of innovative biological processes and principles to exploit the potential of biomass. This thesis explores three pivotal aspects needed to take advantage of the considerable untapped potential of the bioeconomy. The first case study aims to identify the determinants of the persisting low maize yields in northern Ghana, despite the introduction of a fertilizer subsidy program. The policy is largely regarded as an instrument to increase crop productivity and contribute to food security. The second empirical study explores the role of female-led market institutions in Ghana. Marketing is central to the development of the bioeconomy and as such, trader organizations have a key role to play the value chain. The third case study investigates, taking sugarcane as a case study example, how well Brazil, the world’s leader in sugarcane production, is positioned to realize the shift from a fossil-based to a bio-based economy (bioeconomy). The two case study countries Ghana and Brazil were chosen because of their comparable net primary productivity and pedo-climatic conditions, and because of their different stages in the realization of the bioeconomy. Two components are pivotal to the success of the bioeconomy: biomass and knowledge. Based on two case studies in Ghana, this thesis investigates first the efforts to increase maize productivity in the Guinea savanna and secondly explores the role of collective action groups as central actors to address the sustainability dimension of the bioeconomy. Brazil has successfully implemented pivotal aspects of the bioeconomy, especially in the sugarcane sector. For this reason it lends itself well to analyze the role of institutions and networks in the development of new processes and products. This study adopts a mixed methods approach to address three key aspects of the development of the bioeconomy: production, marketing, and the overall innovation system. Data collection and analysis included qualitative and quantitative methods from various disciplines. The findings are presented in three papers, which this cumulative thesis is composed of. The first paper adopts a multidisciplinary approach. A household survey, in-depth interviews, and focus group discussions served to gather data on the socio-economic challenges of maize production in the Guinea savanna. Additionally, soil and fertilizer samples were analyzed to identify natural constraints and potential governance challenges. The results from this paper show that both socio-economic and biophysical parameters contribute to an improved understanding of site-specific challenges, resulting in low maize productivity in the Guinea savanna of Ghana. The second paper explores the role of female-led market associations across regions, ethnicities, and market typologies throughout Ghana. For this study a qualitative approach was chosen with participant observation and in-depth open-ended interviews conducted with traders, both in and out of leadership positions. The results could not empirically confirm the prevailing discourse on the monopolizing power of female-led market associations. The study rather finds that traders’ collective action provides vital safety-net measures for asset-poor women engaging in risky market activity. However, the public perception is challenging female trader agencies. The third paper analyzes the role of institutions and focuses on the innovation networks in the sugarcane sector in Brazil. The study combines the novel concept of ‘biomass value-webs’ with the established National Innovation System concept. For data collection, in-depth interviews and Net-Maps as a participatory tool were applied. The results illustrate the importance of innovation networks for Brazil to become a front-runner in the future bioeconomy. In particular, it emphasizes the importance of integrating national and international private sector organizations, and the need for incentives to foster collaboration with knowledge institutions. Based on these findings, one can conclude that strengthening the efforts to tailor site-specific solutions that consider the inter-disciplinary nature of crop production, marketing and development of processes is crucial to the bioeconomy. Overall, more attention to innovation networks is required to master the challenges of the bioeconomy and take full advantage of its opportunities.
Translocation and storage of chloride in chlorine-stressed maize (Zea mays L.)
(2020) Zhang, Xudong; Zörb, Christian
Maize (Zea mays L.) is a moderately salt-sensitive species, its sensitivity to NaCl being mainly associated with the accretion of toxic sodium in shoots for example leading to the sodium-induced damage of leaf chloroplasts. However, less attention has been paid to the effects of chloride (Cl-). The work described in this dissertation therefore aims at elucidating the physiological adaptations of maize plants to Cl- salinity. It involves four research questions: 1) how do sensitive maize plants respond to Cl- salinity with regard to crop yield and plant performance; 2) how are the translocation and tissue storage patterns of Cl- correlated with tolerance to Cl- salinity; 3) how do osmotic stress and Cl- stress impact biomass, chlorophyll content, and nitrate reductase activity (NRA); 4) does sensitivity to Cl- salinity differ between maize and faba bean plants? Soil pot experiments and hydroponic culture experiments in the greenhouse have shown that maize is able to withstand Cl- salinity by being a shoot excluder. The relevant genotypic difference is believed to be based on its ability to undertake Cl- root-to-shoot translocation. The resistance mechanism of the genotype ES-metronom, which is a more Cl- -tolerant variety, has been attributed to its more efficient shoot exclusion of Cl-,whereas that of the genotype P8589, which is a more Cl- -sensitive variety has been ascribed to the preferable sequestration of Cl- away from the young photosynthetic tissues, such as into old leaf blades, and Cl- movement in roots possibly to achieve Cl- dilution. In the mildly tolerant genotype LG30215, osmotic stress does not interfere with NRA but slows down mass flow, which probably reduces NO3- transport to leaf tissues, whereas excess Cl- indirectly inhibits NRA through the antagonistic limitation of NO3- uptake. In comparison with maize, faba bean plants are more sensitive to Cl- salinity rather than to sodium toxicity.
Verbesserung der Energie-, Stoff- und Emissionsbilanzen bei der Bioethanolproduktion aus nachwachsenden Rohstoffen
(2010) Fleischer, Sven; Senn, Thomas
In this thesis, a process was realized that uses starchy raw material (triticale) as well as lignocellulosic biomass (corn silage) in one ethanol production process. In contrast to other so called 2nd generation ethanol processes, which only use lignocellulosic material, the problem of the very low potential ethanol concentration (