Die Akkumulation und Stabilität der organischen Bodensubstanz resultiert aus der Balance zwischen den zwei biologisch regulierten Prozessen der Humifizierung und der Mineralisation. Boden-Mikroorganismem sind in besonderem Umfang in diesen Prozessen involviert, wobei neben Bakterien Bodenpilze eine herausragende Rolle spielen. Die Enzymgruppe der Laccasen ist in der Lage organische Moleküle aus der Streu und aus dem Humus vollständig zu mineralisieren. Das laufende Projekt befasst sich mit der Analyse der räumlichen und saisonalen Variabilität von Diversitäts- und Expressionsprofilen der Laccasegene.
Fusarium species of the Gibberella fujikuroi species complex cause serious diseases on different crops such as rice, wheat and maize. An important group of plant pathogens is the Gibberella fujikuroi species complex (GFC) of closely related Fusarium species which are associated with specific hosts; F. verticillioides and F. proliferatum are particularly associated with maize where they can cause serious ear-, root-, and stalk rot diseases. Two other closely related species of the GFC, F. mangiferae and F. fujikuroi, which share about 90Prozent sequence identity with F. verticillioides, are pathogens on mango and rice, respectively. All of these species produce a broad spectrum of secondary metabolites such as phytohormones (gibberellins, auxins, and cytokinins), and harmful mycotoxins, such as fumonisin, fusarin C, or fusaric acid in large quantities. However, the spectrum of those mycotoxins might differ between closely related species suggesting that secondary metabolites might be determinants for host specificity. In this project, we will study the potential impact of secondary metabolites (i.e. phytohormones and certain mycotoxins) and some other species-specific factors (e.g. species-specific transcription factors) on host specificity. The recently sequenced genomes of F. mangiferae and F. fujikuroi by our groups and the planned sequencing of F. proliferatum will help to identify such determinants by genetic manipulation of the appropriate metabolic pathway(s).
Irrigation in the Yanqi Basin, Sinkiang, China has led to water table rise and soil salination. A model is used to assess management options. These include more irrigation with groundwater, water saving irrigation techniques and others. The model relies on input data from remote sensing.The Yanqi Basin is located in the north-western Chinese province of Xinjiang.This agriculturally highly productive region is heavily irrigated with water drawn from the Kaidu River. The Kaidu River itself is mainly fed by snow and glacier melt from the Tian Mountain surrounding the basin. A very poor drainage system and an overexploitation of surface water have lead to a series of environmental problems: 1. Seepage water under irrigated fields has raised the groundwater table during the last years, causing strongly increased groundwater evaporation. The salt dissolved in the groundwater accumulates at the soil surface as the groundwater evaporates. This soil salinization leads to degradation of vegetation as well as to a loss of arable farmland. 2. The runoff from the Bostan Lake to the downstream Corridor is limited since large amount of water is used for irrigation in the Yanqi Basin. Nowadays, the runoff is maintained by pumping water from the lake to the river. The environmental and ecological system is facing a serious threat.In order to improve the situation in the Yanqi Basin, a jointly funded cooperation has been set up by the Institute of Environmental Engineering, Swiss Federal Institute of Technology (ETH) , China Institute of Geological and Environmental Monitoring (CIGEM) and Xinjiang Agricultural University. The situation could in principle be improved by using groundwater for irrigation, thus lowering the groundwater table and saving unproductive evaporation. However, this is associated with higher cost as groundwater has to be pumped. The major decision variable to steer the system into a desirable state is thus the ratio of irrigation water pumped from the aquifer and irrigation water drawn from the river. The basis to evaluate the ideal ratio between river and groundwater - applied to irrigation - will be a groundwater model combined with models describing the processes of the unsaturated zone. The project will focus on the following aspects of research: (...)
The proposal addresses the potential of subsoil to contribute to K nutrition of crops. More specifically we will address the processes controlling release of K from interlayer of 2:1 clay minerals as this is expected to be the dominant K fraction in the subsoil. While it has been shown in the past that this so called 'non-exchangeable' K can be released due to root activity, there are controversial results concerning the role of soil solution K concentration in the rhizosphere required to trigger the process. Likewise little information is available about the concentration dynamics of other cations (NH4, Ca) in the rhizosphere and their impact on K release and vermiculitization supposed to be associated with this process. Model studies with substrate from the central field trial will be conducted in compartment systems equipped with micro suction cups. The measurement of dynamic changes of soil solution composition with increasing distance from the root surface will be combined with investigations of changes in mineralogy by XRD, TEM and SEM-EDX. Changes of mineralogy as a result of plant induced K release from interlayer will also be studied on bulk soil and rhizosphere samples collected within the central field and the central microcosm experiment and with mineral bags exposed in the field during a cropping cycle. Finally, X-ray CT will be used to access changes in soil texture, i.e. clay distribution around roots and the temporal spread of roots in biopores which is a prerequisite for K uptake from such structures.
Calcium supply in tropical soils is variable and frequently low. In spite of the heterogeneous Ca supply, some plant species, such as figs, maintain high Ca concentrations in their tissues. Figs are keystone species with more than proportional importance for the functioning of a tropical rain forest. High Ca concentrations in fig fruits may render them particularly attractive for frugivorous vertebrates. We propose to study the whole Ca cycling from soil through a selected fig species, Ficus insipida Willd. and frugivorous bats, their main dispersers, back to soil. The study will be conducted in Panama on sites differing in soil Ca status to assess the importance of soil Ca availability for fig fruit content and bat reproduction. We will quantify aboveground Ca fluxes for 16 trees along a gradient of Ca availability in soil. We will determine (1) Ca concentrations in soils, figs and leaves, (2) nutritional quality of fig and other bat-dispersed fruits and their importance for Ca balance in relation to reproduction of fruit-eating bats, (3) Ca fluxes with litterfall, throughfall, stemflow, bat pellets and faeces, (4) the importance of the contribution of bats to the Ca cycle of individual fig trees, and (5) the effect of fig trees on soil Ca concentrations.
Introduction: In Malaysia, excessive nutrients from livestock waste management systems are currently released to the environment. Particularly, large amounts of manure from intensive pig production areas are being excreted daily and are not being fully utilised. Alternatively, the excess manure can be applied as an organic fertiliser source in neighbouring cropping systems on the small landholdings of the pig farms to improve soil fertility so that its nutrients will be available for crop uptake instead of being discharged into water streams. Thus, there is a need for better tools to analyse the present situation, to evaluate and monitor alternative livestock production systems and manure management scenarios, and to support farmers in the proper management of manure and fertiliser application. Such tools are essential to quantify, and assess nutrient fluxes, manure quality and content, manure storage and application rate to the land as well as its environmental effects. Several computer models of animal waste management systems to assist producers and authorities are now available. However, it is felt that more development is needed to adopt such models to the humid tropics and conditions of Malaysia and other developing countries in the region. Objectives: The aim is to develop a novel model to evaluate nutrient emission scenarios and the impact of livestock waste at the landscape or regional level in humid tropics. The study will link and improve existing models to evaluate emission of N to the atmosphere, and leaching of nutrients to groundwater and surface water. The simulation outputs of the models will be integrated with a GIS spatial analysis to model the distribution of nutrient emission, leaching and appropriate manure application on neighbouring crop lands and as an information and decision support tool for the relevant users.
Cydia pomonella granulovirus (CpGV, Baculoviridae) is one of the most important agents for the control of codling moth (CM, Cydia pomonella, L.) in both biological and integrated pest management. The rapid emergence of resistance against CpGV-M, which was observed in about 40 European CM field populations from 2003 on, could be traced back to a single, dominant, sex-linked gene. Since then, resistance management has been based on mixtures of new CpGV isolates (CpGV-I12, -S), which are able to overcome this resistance. Recently, resistance even to these novel isolates was observed in CM field populations. This resistance does not follow the described dominant, sex-linked inheritance trait. At the same time, another isolate CpGV-V15 was identified showing high virulence against these resistant populations. To elucidate this novel resistance mechanism and to identify the resistance gene(s) involved, we propose a comprehensive analysis of this resistance on the cellular and genomic level of codling moth. Because of the lack of previous knowledge of the molecular mechanisms of virus resistance in insects, several different and complementary approaches will be pursued. This study will not only give an in-depth insight into the genetic possibilities for development of baculovirus resistance in CM field populations and how the virus overcomes it, but can also serve as an important model for other baculovirus-host interaction systems.
Especially during the last decades, the natural forests of Ethiopia have been heavily disturbed by human activities. Some forests have been totally cleared and converted into fields for agricultural use, other suffered from different influences, such as heavy grazing and selective logging. The ongoing research in the Shashemane-Munessa-study area (Gu 406/8-1,2) showed clearly that, in spite of interdiction and control, forests continue to be cleared and degraded. However, it is not yet sufficiently known, how and why these processes are still going on. Growing population pressure and economic constraints for the people living in and around the forests contribute to the actual situation but allow no final answers to the complex situation. Concerning a sustainable management of the forests there is to no solid basis for recommendations from the socioeconomic and socio-cultural view. Therefore, a comprehensive analysis of the traditional needs and forms of forest use, including all forest products, is necessary. The objective of this project is, to achieve this basis by carrying out intensive field observations, the consultation of aerial photographs, satellite imagery and above all semi-structured interviews with the population in the study area in order to contribute to the recommendations for a sustainable use of the Munessa Shasemane forests.
Die Asian Tropopause Aerosol Layer (ATAL), eine Schicht mit erhöhtem Aerosolgehalt, tritt jedes Jahr von Juni bis September in 14-18 km Höhe in einem Gebiet auf, das sich vom Mittelmeer bis zum westlichen Pazifik erstreckt. Hinsichtlich der Zusammensetzung der Partikel, sowie ihrer Bedeutung für die Strahlungsbilanz in dieser klimasensitiven Höhenregion bestehen große Unsicherheiten. Die bisher einzigen Flugzeugmessungen aus dem Zentrum der ATAL wurden 2017 im Rahmen der StratoClim Kampagne von Kathmandu aus gewonnen. Dabei entdeckten wir mit Hilfe des Infrarotspektrometers GLORIA auf dem Forschungsflugzeug Geophysica, dass feste Ammoniumnitrat (AN) â€Ì Partikel einen beträchtlichen Teil der Aerosolmasse ausmachen. Diese zählen zu den effizientesten Eiskeimen in der Atmosphäre. Zudem zeigte die gleichzeitige Messung von Ammoniakgas (NH3) durch GLORIA, dass dieses Vorläufergas durch starke Konvektion in die obere Troposphäre verfrachtet wird. Im Rahmen der PHILEAS-Kampagne schlagen wir eine gemeinsamen Betrachtung von atmosphärischen Modellsimulationen und Messungen vor, um die Zusammensetzung, Ursprung, Auswirkungen und Verbleib der ATAL-Partikel zu untersuchen â€Ì insbesondere im Hinblick auf ihre Prozessierung sowie ihren Einfluss auf die obere Troposphäre und die untere Stratosphäre der nördlichen Hemisphäre. Messungen von monsunbeeinflussten Luftmassen über dem östlichen Mittelmeer sowie über dem nördlichen Pazifik werden es uns erlauben, Luft mit gealtertem Aerosol- und Spurengasgehalt zu analysieren und damit die StratoClim-Beobachtungen aus dem Inneren des Monsuns zu komplementieren. Um dabei die wahrscheinlich geringeren Konzentrationen an Aerosol und Spurengasen zu quantifizieren, schlagen wir vor, die GLORIA-Datenerfassung von NH3 und AN u.a. durch die Verwendung neuartiger spektroskopischer Daten zu verbessern. Ferner werden wir die Analyse der GLORIA-Spektren auf Sulfataerosole sowie deren Vorläufergas SO2 auszudehnen. Auf der Modellseite werden wir das globale Wetter- und Klimamodellsystem ICON-ART weiterentwickeln, um die ATAL unter Einbeziehung verschiedener Aerosoltypen (Nitrat, Ammonium, Sulfat, organische Partikel, Staub) zu simulieren â€Ì unter Berücksichtigung der hohen Eiskeimfähigkeit von festem AN. Modellläufe werden durchgeführt, um einerseits einen globalen Überblick über die Entwicklung der ATAL 2023 zu gewinnen und zudem detaillierte, auf die relevanten Kampagnenperioden zugeschnittene, wolkenauflösende Informationen über die Aerosol-Wolken-Strahlungs-Wechselwirkungen zu erhalten. Über die direkte Analyse der PHILEAS-Kampagne hinausgehend wird diese Arbeit die Grundlage für eine verbesserte Analyse von Aerosolparametern aus GLORIA-Beobachtungen früherer und zukünftiger HALO-Kampagnen sowie aus Satellitenbeobachtungen legen. Darüber hinaus wird sie ICON-ART, einem der zentralen Klimamodellsysteme in Deutschland die Simulation von Aerosolprozessen sowie Aerosol/Wolken-Wechselwirkungen im Zusammenhang mit der ATAL ermöglichen.
In the Earth, the dynamo action is strongly linked to core freezing. There is a solid inner core, the growth of which provides a buoyancy flux that drives the dynamo. The buoyancy in this case derives from a difference in composition between the solid inner core and the fluid outer core. In planetary bodies smaller than the Earth, however, this core differentiation process may differ - Fe may precipitate at the core-mantle boundary (CMB) rather than in the center and may fall as iron snow and initially remelt with greater depth. A chemical stable sedimentation zone develops that comprises with time the entire core - at that time a solid inner core starts to grow. The dynamics of this system is not well understood and also whether it can generate a magnetic field or not. The Jovian moon Ganymede, which shows a present-day magnetic dipole field, is a candidate for which such a scenario has been suggested. We plan to study this Fe-snow regime with both a numerical and experimental approach. In the numerical study, we use a 2D/3D thermo-chemical convection model that considers crystallization and sinking of iron crystals together with the dynamics of the liquid core phase (for the 3D case the influence of the rotation of the Fe snow process is further studied).The numerical calculations will be complemented by two series of experiments: (1) investigations in metal alloys by means of X-ray radioscopy, and (2) measurements in transparent analogues by optical techniques. The experiments will examine typical features of the iron snow regime. On the one hand they will serve as a tool to validate the numerical approach and on the other hand they will yield important insight into sub-processes of the iron snow regime, which cannot be accessed within the numerical approach due to their complexity.