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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
171

Functional genomics of plant chitinase-like genes

Johnston, David Morris 11 1900 (has links)
The Arabidopsis chitinase-like1 (Atctl1) mutant, pom1 is compromised in primary cell wall development, resulting in short roots when grown on high sucrose and shortened hypocotyls when grown in darkness. To better understand this phenotype and the evolution of AtCTL1 and its homologue, AtCTL2, we obtained a large number of CTL sequences and determined the phylogenetic relationships among them. Since microarray analysis had suggested a change in auxin response or homeostasis in pom1, I used the auxin reporter DR5::GUS in the pom1 background to assess changes in distribution. To assess whether the biochemical functions of AtCTL1 homologues in Arabidopsis and other plants are conserved, I transformed pom1 with AtCTL2 and CTLs from poplar (Populus trichocarpa x Populus deltoides clone H-11) and from Picea glauca (spruce) and assessed rescue of the pom1 phenotype. To further understand CTL expression and function, Arabidopsis and poplar CTL promoter::GUS fusions were also expressed in Arabidopsis, PopCTL1 overexpressed in Arabidopsis, and CTL expression down regulated in poplar by RNAi. Our results indicate that CTL genes represent an ancient family encoding proteins of conserved biochemical function. In dicots, represented by Arabidopsis and poplar) duplicated CTL genes are differentially expressed in conjunction with primary and secondary cell wall development, respectively. Mutation of these genes results in improperly formed primary walls in certain cell types in the case of AtCTL1, and an impairment in the differentiation of vascular bundles for AtCTL2. Overexpression of PopCTL1 in Arabidopsis seems to over stimulate the differentiation of vascular bundles, and our studies show that auxin distribution is altered in the Atctl1 mutant. Down regulation of PopCTL1 and PopCTL2 in poplar appears to phenocopy aspects of these mutations, resulting in secondary cell walls that appear to have less deposition of lignin and an accelerated production of secondary xylem respectively. While specific biochemical function(s) of CTL genes were not studied, potential functions are discussed.
172

Functional genomics of plant chitinase-like genes

Johnston, David Morris 11 1900 (has links)
The Arabidopsis chitinase-like1 (Atctl1) mutant, pom1 is compromised in primary cell wall development, resulting in short roots when grown on high sucrose and shortened hypocotyls when grown in darkness. To better understand this phenotype and the evolution of AtCTL1 and its homologue, AtCTL2, we obtained a large number of CTL sequences and determined the phylogenetic relationships among them. Since microarray analysis had suggested a change in auxin response or homeostasis in pom1, I used the auxin reporter DR5::GUS in the pom1 background to assess changes in distribution. To assess whether the biochemical functions of AtCTL1 homologues in Arabidopsis and other plants are conserved, I transformed pom1 with AtCTL2 and CTLs from poplar (Populus trichocarpa x Populus deltoides clone H-11) and from Picea glauca (spruce) and assessed rescue of the pom1 phenotype. To further understand CTL expression and function, Arabidopsis and poplar CTL promoter::GUS fusions were also expressed in Arabidopsis, PopCTL1 overexpressed in Arabidopsis, and CTL expression down regulated in poplar by RNAi. Our results indicate that CTL genes represent an ancient family encoding proteins of conserved biochemical function. In dicots, represented by Arabidopsis and poplar) duplicated CTL genes are differentially expressed in conjunction with primary and secondary cell wall development, respectively. Mutation of these genes results in improperly formed primary walls in certain cell types in the case of AtCTL1, and an impairment in the differentiation of vascular bundles for AtCTL2. Overexpression of PopCTL1 in Arabidopsis seems to over stimulate the differentiation of vascular bundles, and our studies show that auxin distribution is altered in the Atctl1 mutant. Down regulation of PopCTL1 and PopCTL2 in poplar appears to phenocopy aspects of these mutations, resulting in secondary cell walls that appear to have less deposition of lignin and an accelerated production of secondary xylem respectively. While specific biochemical function(s) of CTL genes were not studied, potential functions are discussed.
173

Standortsökologische Aspekte und Anbaupotenziale von Kurzumtriebsplantagen in Sachsen

Petzold, Rainer 12 July 2013 (has links) (PDF)
Kurzumtriebsplantagen (KUP) besitzen das Potenzial, beträchtliche Mengen Biomasse für die Versorgung mit erneuerbaren Energien und nachwachsenden Rohstoffen bereitzustellen. Es ist bekannt, dass KUP auf landwirtschaftlichen Flächen mehr Ökosystemdienstleistungen hervorbringen können als üblicherweise angebaute einjährige Ackerfrüchte oder Energiepflanzen wie Raps und Mais. Trotzdem gibt es nur wenige Informationen über den Wasserverbrauch und die Transpiration von Pappelarten und ihren Hybriden unter den spezifischen Standortsbedingungen in Deutschland. Darüber hinaus bestehen Wissenslücken für die Abschätzung langfristiger Auswirkungen von KUP auf bodenökologische Aspekte. Um diese Defizite zu minimieren wurden auf einem Standort im mittelsächsischen Löss-Hügelland Felduntersuchungen durchgeführt. Für die Untersuchung der Effekte von KUP auf die Bodenwasserbilanz wurden Saftfluss- und Bodenfeuchte-Messungen in einer 10jährigen Hybrid-Pappelplantage durchgeführt. Darüber hinaus wurden Biomasseakkumulation, Nährelementverteilung und bodenökologische Parameter erforscht. Die Daten wurden genutzt, um ein prozess-orientiertes Wasserhaushaltsmodell zu parametrisieren und zu kalibrieren. Das validierte Modell wurde danach für die Untersuchung und Bewertung des Einflusses von Pappel-KUP und Winterweizen auf die Wasserbilanz verschiedener sächsischer Standorte genutzt. Schließlich wurden die standortsspezifischen Biomasseerträge von KUP hergeleitet. Diese Informationen wurden mithilfe eines Geografischen Informationssystems (GIS) mit den Flächen verschnitten, auf denen der Anbau von KUP zu Synergien bzw. potenzielle Risiken für den Bodenschutz sowie den Natur- und Landschaftsschutz führen kann. Die Ergebnisse zeigen, dass Hybrid-Pappelplantagen deutlich mehr Wasser als Ackerkulturen und einheimische Forstbaumarten verbrauchen. Es kann daraus abgeleitet werden, dass die Anlage von KUP auf Ackerflächen den wassergebundenen Nährstoffaustrag sowie den Austrag von Schadstoffen reduziert. Auch das Erosionsrisiko würde verringert. Andererseits kann eine im vergleich zum Einzugsgebiet großflächige Anlage von KUP in Regionen mit negativer klimatischer Wasserbilanz zu einer geringeren Grundwasserneubildung führen. Eine ausreichende Wasserversorgung ist unverzichtbar, um die Wuchspotenziale von Pappel-Hochleistungssorten voll auszuschöpfen. Pappel-KUP können weitgehend ohne zusätzliche Düngung bewirtschaftet werden. Ehemals intensiv genutzte Ackerböden enthalten ausreichend Nährstoffe und Elemententzüge über die geerntete Biomasse werden durch atmosphärische Depositionen ausgeglichen. Auf lange Sicht kann der KUP-Anbau jedoch zu einer Verringerung des pH-Wertes und der Kationen-Austauschkapazität im Boden führen. Für die Vermeidung negativer Folgen für die Bodenfruchtbarkeit und das Pflanzenwachstum wären dann angepasste Konzepte für die Kalkung und Düngung notwendig. Die GIS-basierte Analyse unterstreicht, dass in Sachsen beträchtliche Flächenpotenziale für die Anlage von KUP existieren. Auf einem großen Teil würde die Anlage von KUP auch andere Ökosystemdienstleistungen aus dem Bereich Boden- und Naturschutz verbessern. Auch künftig sollte bei der Anlage von KUP-Flächen eine ökologische Begleitforschung erfolgen. Es besteht unter anderem der Bedarf, die ökologischen Aspekte von anderen schnell wachsenden Baumarten im Kurzumtrieb, zum Beispiel Robinie zu bewerten. Ein weiteres ziel könnte die Verbesserung von Anlage- und Rückumwandlungstechnologien sein, um die Stabilität von akkumulierter organischer Bodensubstanz zu erhalten. Es wird geschlussfolgert, dass die künftige praktische Bedeutung von KUP eher von den sozioökonomischen Rahmenbedingungen und der regionalen Umsetzung der gemeinsamen Agrarpolitik der Europäischen Union abhängen wird als von unzureichenden Standortsbedingungen. / Short rotation plantations and short rotation coppice (SRC) have the potential to contribute significant amounts of biomass to the sectors of green energy and of renewable raw materials. It is generally accepted that SRC may provide more ecosystem services on agricultural land than common annual arable or even energy crops like oil seed rape or maize do. However, only sparse information exists about the water demand and transpiration of poplar species and their hybrids for site conditions in Germany. Furthermore, there is a lack of knowledge about the long-term impact of short rotation plantations on soil ecology. To overcome these shortcomings, field investigations were conducted at a site in the hilly loess region of Saxony. To study effects of SRC on the soil water balance, sap flow and soil moisture measurements were conducted in a 10 years old hybrid poplar plantation. Moreover biomass accumulation, nutrient allocation and soil ecological parameters were determined. The data were used to parameterize and calibrate a process-oriented hydrological model. The validated model was subsequently used to determine and assess the impact of short rotation poplar plantations and winter wheat on the water balance of different sites in Saxony Finally, site specific yields of SRC were determined and areas with synergies and potential risks for soil protection, nature conservation at the regional scale were identified using Geographical Information Systems. The results show that hybrid poplar plantations consume significantly more water than arable crops and native tree species. Thus, it can be expected that the establishment of short rotation coppice may reduce the export of nutrients and pollutants or lower the risk of soil erosion. On the other hand, the large-scale establishment of short rotation coppice at catchments with negative climatic water balance may lead to a decrease of groundwater recharge. A sufficient water supply is indispensable in order fully to exploit the growth potential of high yielding polar clones. Short rotation plantations with poplar on arable land may be extensively managed without fertilization. Former intensively used agricultural soils provide sufficient nutrients and element exports by harvested biomass may be balanced by atmospherical deposition. However, it might be that in the long run cation exchange capacity and pH of the soils will decrease. This would require appropriated concepts for liming and fertilization. The GIS based analysis shows that there exist a substantial potential of arable land for the cultivation of SRC in Saxony. There, the establishment of SRC may improve other ecosystem services as soil protection and nature conservation too. Future research should be included into the ecological evaluation of new SRC plots. There is a need to asses ecological aspects of other fast growing tree species in SRC, in particular Black Locust. Another task could be the improvement of conversion practices to ensure the stability of accumulated soil organic matter during establishment and reconversion of SRC sites. It can be concluded that the future practical relevance of SRC is rather dependant on socio-economic framework conditions and the regional implementation of the common agricultural policy within the European Union than on insufficient site condition.
174

Die Weidenblattkäfer an Weiden und Pappeln im Kurzumtrieb

Helbig, Christiane, Georgi, Richard, Müller, Michael 25 June 2013 (has links) (PDF)
Während der letzten Jahre ist die mit Kurzumtriebsplantagen bestockte Fläche in Deutschland deutlich angestiegen. Derzeit geht man von etwa 5 000 ha aus [1]. Der Hauptteil dieser Flächen ist mit Pappeln bestockt, während Weiden einen geringeren Anteil einnehmen. In anderen Ländern wie Großbritannien oder Schweden ist das Verhältnis dagegen umgekehrt und es finden sich große, zusammenhängende Weidenkulturen. Hier tritt der Blaue Weidenblattkäfer (Phratora vulgatissima) schon seit Jahren als Hauptschadinsekt auf und verursacht die Entlaubung ganzer Plantagen. Auch in Deutschland ist der Blaue Weidenblattkäfer die am häufigsten vorgefundene Schadinsektenart an Weiden im Kurzumtrieb.
175

Evaluación de la biomasa como recurso energético renovable en Cataluña

Martínez Lozano, Sergio 21 April 2009 (has links)
El objetivo principal es la evaluación de la biomasa como recurso energético renovable en Cataluña. Su alcance requiere el estudio de diversas temáticas, desarrolladas en los doce capítulos que componen el documento.El Capítulo 1 describe los objetivos de la tesis. El Capítulo 2 describe los motivos que justifican la valorización energética del recurso biomasa. El Capítulo 3 presenta la metodología general utilizada. El Capítulo 4 realiza un análisis multicriterio del aprovechamiento energético de biomasa forestal. El Capítulo 5 cuantifica la biomasa disponible para usos energéticos en Cataluña. Los Capítulos 6, 7, 8 y 9 analizan las tecnologías y la viabilidad de la producción de energía con colza y chopo. El Capítulo 10 caracteriza físico-químicamente la biomasa de colza como combustible complementario al actual uso del grano para biodiesel. El Capítulo 11 evalua el uso de cultivos para la producción de productos químicos. El Capítulo 12 resume las Conclusiones generales. / The main goal is the evaluation of biomass as renewable resource in Catalonia. Its scope requires the study of different subjects, developed in the twelve chapters that compose the document. The Chapter 1 describes the goals of the PhD thesis. The Chapter 2 describes the reasons that justify the energetic use of biomass. The Chapter 3 shows the general methodology used. The Chapter 4 carries out a multicriterion analysis of energetic valorisation of forestry biomass. The Chapter 5 quantifies the available biomass for energy production in Catalonia. The Chapters 6, 7, 8 and 9 analyze the technologies and the feasibility of power generation using rapeseed and poplar energy crops. The Chapter 10 characterizes physical-chemically the rapeseed biomass as complementary fuel to the current use of the grain for bio-diesel production. The Chapter 11 evaluates the potential use of other crops for chemicals production. The Chapter 12 summarizes the Main Conclusions.
176

Entwicklung eines Ertragsschätzers für Kurzumtriebsbestände aus Pappel / Construction of a yield estimation model for short rotation forestry with poplar

Hartmann, Kai-Uwe 20 December 2010 (has links) (PDF)
Bisherige Verfahren zur Ertragsbestimmung von schnellwachsenden Baumarten im Kurzumtrieb sind entweder mit einem hohen Zeit- und Arbeitsaufwand verbunden und/oder haben destruktiven Charakter. Die vorliegende Arbeit beschäftigt sich mit der Entwicklung eines leicht anwendbaren, zerstörungsfreien und übertragbaren Ertragsschätzers für Kurzumtriebsbestände aus Pappel. Grundlage bildet die Standardisierung von Biomassefunktionen auf deren Basis ein standort- und klonunabhängiges Modell hergeleitet wird, das eine hinreichend genaue Schätzung des Biomassevorrates gestattet. Die Untersuchungen zu Grundlagen der Modellentwicklung und der Test verschiedener Modellansätze erfolgen auf der Basis von Korrelations- und Regressionsanalysen, Signifikanztests und Varianzanalysen. Die Prüfung der Schätzgenauigkeit basiert auf fünf Evaluierungskenngrößen. Für die Anwendung des klonunabhängigen, für Alter ≥ 3 Jahre und Bestandesdichten ≤ 25000 N/ha einsetzbaren Ertragsschätzers sind lediglich drei einfach und schnell zu erhebenden Ertragsgrößen (hm, N, dg) notwendig. Innerhalb der Modellgrenzen betragen die relativen maximalen Abweichungen zwischen Real- und Schätzwerten höchstens +/- 40 % und lässt sich der Biomassevorrat mit einer durchschnittlichen Differenz (Bias) von 7,1 % schätzen.
177

Spectroscopic data and multivariate analysis : tools to study genetic perturbations in poplar trees

Wiklund, Susanne January 2007 (has links)
In our society in the 21st century one of the greatest challenges is to provide raw materials to the industry in a sustainable way. This requires increased use of renewable raw materials such as wood. Wood is widely used in pulp, paper and textile industries and ongoing research efforts aim to extend the use of wood in e.g. liquid biofuels and green chemicals. At Umeå Plant Science Center (UPSC) poplar trees are used as model systems to study wood formation. The objective is to understand the function of the genes underlying the wood forming process. This knowledge could result in improved chemical and physical wood properties suitable for different industrial processes. This will in turn meet the demands for a sustainable development. This thesis presents tools and strategies to unravel information regarding genetic perturbations in poplar trees by the use of nuclear magnetic resonance (NMR) spectroscopy and multivariate analysis (MVA). Furthermore, gas chromatography/mass spectrometry (GC/MS) is briefly discussed in this context. Multivariate methods to find patterns and trends in NMR data have been used for more than 30 years. In the beginning MVA was applied in pattern recognition studies in order to characterize chemical structures with different ligands and in different solvents. Today, the multivariate methods have developed and the research have changed focus towards the study of biofluids from plant extracts, urine, blood plasma, saliva etc. NMR spectra of biofluids can contain thousands of resonances, originating from hundreds of different compounds. This type of complex data can be hard to summarize and interpret without appropriate tools and require sophisticated strategies for data evaluation. Related fields of research are rapidly growing and are here referred to as metabolomics. Five different research projects are presented which includes analysis of poplar samples where macromolecules such as pectin and also small molecules such as metabolites were analysed by high resolution magic angle spinning (HR/MAS) NMR spectroscopy, 1H-13C HSQC NMR and GC/MS. The discussion topics include modelling of metabolomic time dependencies in combination with genetic variation, validation of orthogonal projections to latent structures (OPLS) models, selection of putative biomarkers related to genetic modification from OPLS-discriminant analysis (DA) models, measuring one of the main components found in the primary cell-walls of poplar i.e. pectin, the use of Fourier transformed two-dimensional (2D) NMR data in OPLS modelling and model complexity in a PLS model.
178

Vergleich unterschiedlicher Anbaumethoden von Energieholzplantagen / Comparison of different cultivation methods of short rotation plantations

Stoll, Bettina 19 December 2011 (has links)
No description available.
179

Adaptation of trembling aspen and hybrid poplars to frost and drought: implications for selection and movement of planting stock in western Canada

Schreiber, Stefan Georg Unknown Date
No description available.
180

Dialogue, displacement and return - contexts of a journey on a two-way road: Anishinaabek responses to all-weather roads through Waabanong Nakaygum: memory and continuity on the eastern shores of Lake Winnipeg and beyond

Weinberg, Alon David 15 January 2014 (has links)
East of Lake Winnipeg is what conservationists call the ‘east shore wilderness’ / ‘heart of the boreal.’ The largest contiguous tract of unindustrialized boreal forest on Earth, this area has been the focus of 15 years of discussion and planning in Manitoba. The area is also designated Waabanong Nakaygum, a homeland to the Anishinaabek of this bush-meets-lake region. Waabanong has seen limited access during the industrial period of personal mechanized mobility due to a lack of constructed all-weather roads. However, an older pattern of travel and mobility does exist across the land, for centuries constituting traditional Anishinaabek patterns of land use and trade. As all-weather roads are being constructed along Lake Winnipeg, oral interviews will examine the question: will the older trails remain in the collective culture of the people or shall the north-south cultural and economic flows replace the east-west bush history traced by the rivers that wind through?

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