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Mutez Ali Ahmed: Angebotene Abschlussarbeiten



Angebotene Bachelorarbeiten
The impact of root exudates on the physical properties of soil and root water uptake

Introduction:

Global population is increasing and projected consumption is placing unprecedented demand on agriculture for food production. Securing food availability is a major challenge, since global water shortage and degradation are already limiting crop yield today and this limitation, will further intensify as agricultural activities expand to less fertile areas. The rhizosphere, the interface between plant roots and soil, is rich in provides a unique environment for large and diverse types of substances like microbes, including plant growth-promoting rhizobacteria (PGPR) and root exudates. Investigations on the mechanisms by which these substances mediate plant drought tolerance have largely focused on -root/plant interactions and related plant responses to bacteria types. Comparatively, much less is known about the role of root exudates in altering the physiochemical and hydrological properties of the rhizospheric soil that may affect plant drought stress tolerance.

Hypotheses:

This project is aiming on testing the following hypotheses:

1. Root exudates change the pore space of soils and improve the soil hydraulic properties (both wetting and drying), resulting in material that can hold more water and increase residents time of solutes in the rhizosphere

2. Root exudates may improve crop yields, especially in coarse (sandy) to medium (loamy) texture soils, due to either increase in available water in the rhizosphere, and/or due to prolonging the contact of roots with the soil matrix and consequently higher root water uptake and nutrient uptake.

Methods:

Laboratory work on the estimation of soil hydraulic properties for materials treated with different concentrations of root exudates for both wetting and drying processes. In case of a master thesis, the thesis will include quantification of the SHPS based on pore scale considerations or quantification of root water uptake with a numerical model. In both cases, model results will be compared against the lab measurements.



Ansprechpartner: Efstathios (Stathis) Diamantopoulos, Mutez Ali Ahmed


Angebotene Masterarbeiten
The impact of root exudates on the physical properties of soil and root water uptake

Introduction:

Global population is increasing and projected consumption is placing unprecedented demand on agriculture for food production. Securing food availability is a major challenge, since global water shortage and degradation are already limiting crop yield today and this limitation, will further intensify as agricultural activities expand to less fertile areas. The rhizosphere, the interface between plant roots and soil, is rich in provides a unique environment for large and diverse types of substances like microbes, including plant growth-promoting rhizobacteria (PGPR) and root exudates. Investigations on the mechanisms by which these substances mediate plant drought tolerance have largely focused on -root/plant interactions and related plant responses to bacteria types. Comparatively, much less is known about the role of root exudates in altering the physiochemical and hydrological properties of the rhizospheric soil that may affect plant drought stress tolerance.

Hypotheses:

This project is aiming on testing the following hypotheses:

1. Root exudates change the pore space of soils and improve the soil hydraulic properties (both wetting and drying), resulting in material that can hold more water and increase residents time of solutes in the rhizosphere

2. Root exudates may improve crop yields, especially in coarse (sandy) to medium (loamy) texture soils, due to either increase in available water in the rhizosphere, and/or due to prolonging the contact of roots with the soil matrix and consequently higher root water uptake and nutrient uptake.

Methods:

Laboratory work on the estimation of soil hydraulic properties for materials treated with different concentrations of root exudates for both wetting and drying processes. In case of a master thesis, the thesis will include quantification of the SHPS based on pore scale considerations or quantification of root water uptake with a numerical model. In both cases, model results will be compared against the lab measurements.



Ansprechpartner: Efstathios (Stathis) Diamantopoulos, Mutez Ali Ahmed
Die Rolle von arbuskulären Mykorrhizapilzen beim Wasserzustand der Pflanze

Einleitung: Die Wasserknappheit im Boden und in der Atmosphäre erhöht die Belastung auf die Vegetation und bedroht die künftige landwirtschaftliche Produktion und das Überleben der Wälder insbesondere angesichts des Klimawandels. Neuere Literatur dazu hat die Austrocknung der Böden als eine der Hauptursachen für die Verdunstung weltweit identifiziert. Daher ist eine detaillierte Kenntnis der Wasserflussprozesse, insbesondere unter der Erde, erforderlich, um das Pflanzenverhalten während Dürrezeiten und unter zukünftigen Klimabedingungen vollständig zu verstehen und vorherzusagen.

Obwohl davon ausgegangen wird, dass arbuskuläre Mykorrhizapilze (AMF) eine entscheidende Rolle bei der Reaktion der Pflanzen auf die Bodentrockenheit spielen, gibt es noch recht wenig Studien, die den Einfluss von AMF auf den Wasserstatus der Pflanze und die hydraulische Leitfähigkeit zwischen Boden und Pflanze untersuchen.

Hypothesen: Ziel dieses Projektes ist es, die folgenden Hypothesen zu überprüfen:

  1. AMF begrenzen die Verminderung im Matrixpotential in der gesamten Rhizosphäre, besonders während der Austrocknung des Bodens. Der zugrunde liegende Mechanismus besteht darin, dass AMF den effektiven Wurzelradius ausweiten und somit die Wasserdurchflussmenge an der Schnittstelle zwischen Wurzeln und Böden reduzieren.
  2. Die nachfolgende Hypothese besteht darin, dass AMF die hydraulische Leitfähigkeit zwischen Boden und Pflanze sowie den Wasserstatus der Pflanze während der Bodentrockenheit steigert.

Methoden: Messung der Verdunstung und des Blattwasserpotentiales von zwei Maisgenotypen während der Bodenaustrocknung; eine Mutante, die die AMF-Besiedelung und den entsprechenden Wildtyp unterdrückt. Die Pflanzen werden in einer begehbaren, klimatisierten Kammer gezüchtet und auf automatisierte drahtlose Waagen gelegt. Letztere zeichnen das Gewicht alle 10 Minuten auf, um eine gravimetrische Verdunstungsrate zu erhalten. Ergänzende Messungen werden durchgeführt, um die Bodentrockenheit nach der letzten Bewässerung zu beurteilen.



Ansprechpartner: Mohanned Abdalla Ali, Mutez Ali Ahmed, Efstathios (Stathis) Diamantopoulos
A hairy matter: The influence of root hairs on root water uptake

Root hairs play an important role in the uptake of immobile elements (e.g. phophorous) but our understanding of their role in root water uptake is still unsatisfying.

 

In the course of your master thesis, you will assist in supervising a field experiment at the experimental research station Bad Lauchstaedt by installing and maintaining different soil and plant sensors. The collected data, comprising of soil parameters like soil water potential as well as plant parameters e.g. leaf water potential and sap flow, will serve as a basis for your thesis. Comparing the data of two maize genotypes differing in the property of building root hairs, you will investigate the effect of root hairs on transpiration and leaf water potential over an entire cropping cycle.
Furthermore, maize plants will be grown in two different soil textures (sand and loam), which allows the investigation of the impact of these soil textures on the different genotypes.

 

The field experiment in Bad Lauchstaedt is part of a DFG-funded priority programme (SPP 2089) which aims at the identification of spatiotemporal patterns in the rhizosphere and at the explanation of the underlying processes. Our measurements started in 2019 and the period of your master thesis will cover the second growing season.

 

A driving license for reaching the field experiment is needed. All your travel costs to Bad Lauchstaedt and your corresponding expenses will be reimbursed by the Department of Soil Physics.



Ansprechpartner: Andrea Carminati, Mutez Ali Ahmed, Patrick Duddek
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