Boron (B) is an essential microelement for plants. Despite the use of modern fertilization methods, B deficiency still causes losses in agricultural plant production. Even though many positive effects of B on plant growth and physiology have been reported, a large majority of B functions and the regulatory mechanisms controlling the B nutritional status remain unknown. The main objective of this project is to elucidate how the greatly B deficiency-sensitive Brassica crop plants process and regulate their B status during vegetative and reproductive growth. In this context, the project aims at identifying the mode of action of B in mechanisms regulating the B status itself and uncovering those mechanisms contributing to B efficiency in different genotypes. Plant species subjected to investigation will be the agronomically important oilseed and vegetable plant Brassica napus (rapeseed) and its close relative the genetic and molecular model plant Arabidopsis thaliana. Questions addressed within the scope of this project should lead to a detailed understanding of mechanisms controlling B uptake and allocation from the level of the whole plant down to the cellular level. B transport routes and rates will be determined in sink- and source tissues and in developmental periods with a particularly high B demand. A special focus will be on the identification of B transport bottlenecks and the analysis of B deficiency-sensitive transport processes to and within the highly B-demanding reproductive organs. Recent studies in Arabidopsis suggest that Nodulin26-like Intrinsic Proteins (NIPs), which belong to the aquaporin channel protein family, are essential for plant B uptake and distribution. The systematic focus on the molecular and physiological characterization of B. napus NIPs will clarify their role in B transport and will identify novel NIP-associated mechanisms playing key roles in the B response network.To further resolve the mostly unknown impact of the B nutritional status on gene regulation and metabolism, a transcript and metabolite profile of B-sufficient and B-deficient rapeseed plants will be generated. Additionally, an Arabidopsis transcription factor knockout collection (greater 300 lines) will be screened for abnormalities in responses to the B nutritional status. This will identify yet unknown B-responsive genes (transcription factors and their targets) and gene products (enzymes or metabolite variations) playing key roles in signalling pathways and mechanisms regulating the B homeostasis. Boron (in form of boric acid) and arsenite (As) share in all likelihood the same NIP-mediated transport pathways. To assess the consequences of this dual transport pathway the so far unstudied impact of the plants B nutritional status on the accumulation and distribution of As will be investigated in B. napus. Moreover, the current dimension of the As contamination of Brassica-based food products, to which consumers are exposed to, will be analyzed. usw.
Outbreaks of foodborne illness linked to consumptions of fresh, or partially processed, agricultural products are a growing concern in industrialized and developing countries. The incidence of human pathogens on fresh fruits and vegetables is often related to the use of recycled wastewaster in surface irrigation as well as high amounts of animal manure in agricultural management practice. Thereby the soil inhabiting fauna plays an important role in the transport and dissemination of microorganisms. The focus of the proposed project is on nematodes, well known vectors for bacteria and viruses in soil. The major goals are to: (1) survey human pathogens in soil and on/in free-living and plant parasitic nematodes in agriculture field sites irrigated with recycled wastewater or fertilized with fresh animal manure in Israel and the Palestinian Authority, (2) assess the function of nematodes as vectors in transmitting bacteria from microbial hot spots to plants, and (3) localize bacteria on and/or within the nematode and identify bacterial factors required for survival in the nematode host. Understanding the mechanisms involved in dissemination of human pathogens by nematodes will enhance the ability to develop practical means to minimize contamination of fresh produce and increase safety in food production.
Almond in California represents an agroecosystem pollinated solely by a single species, the European honey bee, a species that is becoming increasingly difficult and expensive to manage due to substantial, unpredictable mortality. Therefore, sustainable and high output production require a more integrated approach that diversifies sources of pollination. For this purpose, detailed data of our understanding how diversity can stabilize pollination are required. The project will identify alternative wild pollinator species and collect high quality data contributing to our understanding of how diversity (pollen and insects) can bolster honey bee pollination during stable and unstable climatic conditions. The research will be carried out on almond orchards in Northern California known to be either pollinator species rich (up to 30 species) or depauperate (honey bees only). The replicated extremes in pollinator diversity represent a unique opportunity to study the effects of diversity on pollination in real agroecosystems combined with laboratory and glasshouse experiments. The overall goal is to provide basic research that is essential for our general understanding of how insect diversity can affect high-quality pollination under land use and climate change.
Mikroplastik wird zwischen Land- und Wasseroberflächen und der Atmosphäre ausgetauscht und kann luftgetragen über weite Strecken transportiert werden, bevor die Mikroplastikpartikel wieder aus der Atmosphäre entfernt und abgelagert werden. Obwohl diese Transportprozesse für die Verteilung und die wirksamen Abbaumechanismen von Mikroplastik sehr wichtig sind, gibt es bislang keine systematischen Untersuchungen zum atmosphärischen Transport von Mikroplastik. Der luftgetragene Transport von Mikroplastik wird im vorliegenden Teilprojekt in einem Windkanal als idealisiertem Modellsystem experimentell untersucht und mit einem strömungsauflösenden Transportmodell numerisch simuliert, um die grundlegenden Prozesse verstehen und quantifizieren zu können.
Salinity reduces the productivity of cucumber (Cucumis sativus L.) through osmotic and ionic effects. For given atmospheric conditions we hypothesize the existence of an optimal canopy structure at which water use efficiency is maximal and salt accumulation per unit of dry matter production is minimal. This canopy structure optimum can be predicted by integrating physiological processes over the canopy using a functional-structural plant model (FSPM). This model needs to represent the influence of osmotic stress on plant morphology and stomatal conductance, the accumulation of toxic ions and their dynamics in the different compartments of the system, and their toxic effects in the leaf. Experiments will be conducted to parameterize an extended cucumber FSPM. In in-silico experiments with the FSPM we attempt to identify which canopy structure could lead to maximum long-term water use efficiency with minimum ionic stress. The results from in-silico experiments will be evaluated by comparing different canopy structures in greenhouses. Finally, the FSPM will be used to investigate to which extent the improvement of individual mechanisms of salt tolerance like reduced sensitivity of stomatal conductance or leaf expansion can contribute to whole-plant salt tolerance.
Farm structures are often characterized by regional heterogeneity, agglomeration effects, sub-optimal farm sizes and income disparities. The main objective of this study is to analyze whether this is a result of path dependent structural change, what the determinants of path dependence are, and how it may be overcome. The focus is on the German dairy sector which has been highly regulated and subsidized in the past and faces severe structural deficits. The future of this sector in the process of an ongoing liberalization will be analyzed by applying theoretical concepts of path dependence and path breaking. In these regards, key issues are the actual situation, technological and market trends as well as agricultural policies. The methodology will be based on a participative use of the agent-based model AgriPoliS and participatory laboratory experiments. On the one hand, AgriPoliS will be tested as a tool for stakeholder oriented analysis of mechanisms, trends and policy effects. This part aims to analyze whether and how path dependence of structural change can be overcome on a sector level. In a second part, AgriPoliS will be extended such that human players (farmers, students) can take over the role of agents in the model. This part aims to compare human agents with computer agents in order to overcome single farm path dependence.
Most soils develop distinct soil architecture during pedogenesis and soil organic carbon (SOC) is sequestered within a hierarchical system of mineral-organic associations and aggregates. Permafrost soils store large amounts of carbon due to their permanently frozen subsoil and a lack of oxygen in the active layer, but they lack complex soil structure. With permafrost thaw more oxidative conditions and increasing soil temperature presumably enhance the build-up of more complex units of soil architecture and may counterbalance, at least partly, SOC mineralization. We aim to explore the development of mineral-organic associations and aggregates under different permafrost impact with respect to SOC stabilization. This information will be linked to environmental control factors relevant for SOC turnover at the pedon and stand scale to bridge processes occurring at the aggregate scale to larger spatial dimensions. We will combine in situ spectroscopic techniques with fractionation approaches and identify mechanisms relevant for SOC turnover at different scales by multivariate statistics and variogram analyses. From this we expect a deeper knowledge about soil architecture formation in the transition of permafrost soils to terrestrial soils and a scale-spanning mechanistic understanding of SOC cycling in permafrost regions.
Recent discussions on the path eco-hydromorphic research has followed in the past decades highlight the need for greater ecological input into this field. Traditional approaches have been criticized for being largely correlation-based (Vaughan et al., 2009) ecological black boxes (Leclerc, 2005) and strongly relying on weak, disproven and/or outdated assumptions about the dynamics of stream biota (Lancaster & Downes, 2010). In recognition of this, process-oriented research aiming at elucidating and quantifying causal mechanisms has been proposed as a promising approach, though challenging, to study the relations between flow, morphodynamics and biological populations in running waters. In terms of levels of biological organization, it has been recognized that processes determining the response of aquatic biota to hydromorphological alteration occur mainly at the population level. In this sense, relating demographic rates to flow and morphology seems to offer great potential for progress (Lancaster & Downes, 2010). Thus, tapping into existing ecological knowledge (e.g., key patch approach for habitat networks, Verboom et al. 2001; metapopulation theory, Levins 1970; Hanski & Gaggiotti 2004, landscape-scale estimations of habitat suitability and carrying capacity, Reijnen et al. 1995; Duel et al. 1995 2003; population-level viability estimations; Akçakaya 2001; resource utilization scales, ONeill et al. 1988; habitat-use patterns, Milne et al. 1989) in order to link ecology to hydromorphology at a more fundamental level constitutes an important path towards better science and management.
Pilze sind eine der am diversesten, jedoch am wenigsten untersuchten mikrobiellen Gruppen in marinen Gewässern. Eine Untergruppe der Pilze, kurz als Chytridien bekannt, umfasst häufig auftretende Parasiten auf Phytoplankton, welche eine starke Belastung für das Phytoplanktonwachstum, die Entwicklung von Algenblüten und deren Populationsdynamiken darstellen. Parasitäre Chytridien befallen alle Hauptgruppen von Phytoplankton und treten bevorzugt in Küstenregionen mit hoher Phytoplanktonbiomasse und Produktivität auf. Die Auswirkungen von parasitären Pilzen auf Stoffkreisläufe und die Funktion von Ökosystemen sind jedoch kaum bekannt bzw. quantifiziert. Die Emmy Noether-Nachwuchsgruppe wird die funktionelle und quantitative Rolle parasitärer Pilze für die Phytoplanktonproduktivität und den Stoffkreislauf in Brack- und Meerwasser untersuchen. Unsere Ziele sind (1) Betrachtung der Wechselwirkungen zwischen Phytoplankton und Chytridien auf Einzelzell-Ebene, (2) Untersuchungen der integrativen Rolle von Chytridien in aquatischen Nahrungsnetzen und (3) Aufklärung der Auswirkungen von parasitären Pilzen auf Remineralisierungs- und Sedimentationsprozesse. Unser umfassender Ansatz beinhaltet experimentelle Studien mit Phytoplanktonâ€ÌPilz Co-Kulturen sowie mit natürlichen Planktongemeinschaften, mittels Analysen auf Zell- und Mikoskalen-Ebene bis hin zu mesoskaligen Stoffflüssen entlang der Wassersäule. Im Wesentlichen werden wir den Transfer von Kohlenstoff und Stickstoff vom Phytoplankton durch das pelagische Nahrungsnetz innerhalb der photischen Zone bis hin zum Absinken als Detritus in die Tiefe verfolgen. Das Projektergebnis soll ein ganzheitliches Verständnis der Rolle von Chytridien an der Basis aquatischer Nahrungsnetze und Produktivität fördern, einschließlich der zugrunde liegenden Mechanismen und Größenordnungen. Angesichts der potenziellen Signifikanz parasitärer Pilze für die Abschwächung von Produktivität, Sinkstoffflüssen aber auch von toxischen Algenblüten in Küstengebieten, sollen die gewonnenen Daten mit lokalen und globalen Stoffkreisläufen verknüpft und in zukünftige Entscheidungen zum Küstenmanagement implementiert werden.
Peroxyradikale sind kurzlebige Spezies, die an den meisten Oxidationsprozessen in der Atmosphäre beteiligt sind, die zur Bildung von langlebigeren und chemisch oder toxikologisch wichtigen Schadstoffen wie Ozon führen. Insbesondere in Gebieten, die von komplexen Emissionsquellen betroffen sind, sind Peroxyradikal-Messmethoden mit ausreichender Genauigkeit, Reproduzierbarkeit und Empfindlichkeit erforderlich, um die chemische Umwandlung der städtischen Umweltverschmutzung zu verstehen. In dieser Hinsicht ermöglichen Vergleiche von state-of-the-art Sensoren in chemischen Reaktorkammern deren Charakterisierung unter kontrollierten Bedingungen und verbessern das Vertrauen in die Messung von Peroxyradikalen.SPRUCE strebt ein besseres Verständnis der Rolle der Peroxyradikale bei atmosphärischen chemischen Umwandlungen an, die aus der Wechselwirkung zwischen urbanen anthropogenen und ländlichen biogenen Emissionen resultieren. Im Rahmen der vorgeschlagenen Arbeit wird das vorhandene PeRCEAS-Instrument (Peroxy Radical Chemical Enhancement and Absorption Spectrometer) an der Messkampagne des internationalen Projekts ACROSS (Atmospheric ChemistRy Of the Suburban Forest) zur Untersuchung des Schadstoffausflusses von Paris über ein Waldgebiet, und in der internationalen Vergleichsstudie ROxCOMP22 für wissenschaftliche Instrumente, die atmosphärische Peroxyradikale teilnehmen. Diese beiden Messkampagnen befassen sich mit zwei Hauptaspekten von SPRUCE. Sie bieten eine einzigartige Gelegenheit für a) die Messung von Peroxyradikalen in der spezifischen Umgebung von Interesse und in Verbindung mit einer umfangreichen Reihe von Beobachtungen, die für die Interpretation der Radikalchemie von wesentlicher Bedeutung sind, und b) die Bewertung der Datenqualität und Leistungsfähigkeit von PeRCEAS, insbesondere die Überprüfung der Sensitivität und Effizienz für die Speziation der Radikale unter kontrollierten Bedingungen.Ein Schwerpunkt der Studie wird auf der Untersuchung von Oxidationsreaktionen und Ozonausbeuten in Luftmassen mit unterschiedlicher anthropogener/biogener Signatur in Abhängigkeit von der Menge und Zusammensetzung von Peroxyradikalen liegen. Numerische Berechnungen und Modelle werden durch die Beobachtungen von Vorläuferspezies eingeschränkt, um die Budgets von Peroxyradikalen abzuschätzen. Der Vergleich mit den PeRCEAS-Messungen wird verwendet, um das Verständnis der Oxidationsmechanismen in urbanen Plumes gemischt mit biogenen Emissionen zu testen. Es wird erwartet, dass die Analyse des resultierenden Datensatzes das aktuelle Wissen über die chemische Transformation von Megacity-Emissionen während des atmosphärischen Transports ergänzt.
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