Research Projects

funded by: DFG

in progress since: 2022

Persons involved:
Dr. Xudong Zhang
Prof. Dr. Christian Zörb

Brief Description:

The improvement of salt tolerance of crop plants represents a task of increasing relevance. Faba bean is sensitive to high salt, in particular to chloride, leading to severe growth reductions. In comparison, maize is moderately sensitive to NaCl and Cl-. We aim to analyse the interplay between tissue tolerance and stomata related processes contributing to salt tolerance under conditions of increased salt ion concentrations in leaves. Because stomatal function is a top-down regulator of many physiological processes, dysfunctions of stomata inevitably have severe detrimental effects on plant growth and development. Therefore, maintaining guard cell functionality and thereby control of the water status of plants will result in an improved performance under salinity. The stomatal complex of maize differs to that of faba bean, because monocot guard cells are surrounded by subsidiary cells, which function as a reservoir for inorganic ions. In faba bean, the cell wall, i.e. the apoplast fulfils the corresponding function. Because guard cells have poor selectivity for K+ over other monovalent cations such as Na+ and import Cl- in dependency of its concentrations in the cell walls, harmful accumulation of Na+ and Cl- ions in guard cells, might occur under conditions of NaCl exposure. This observation received only little attention to date but is potentially of tremendous significance for growth performance under stress because stomata are openings on leaf surfaces that regulate intake of CO2 for photosynthesis and water loss through transpiration. The reduction of stomatal aperture under salt induced (water) stress is an effective adjustment to salinity that must be necessarily maintained. Effects of ionic stress on guard cells are merely studied. Most studies are based on whole leaves and, thus, do not have the basis to provide new insights into guard cell stress responses and, in particular, upon effects of salt enrichment in the guard cell walls. Our recent pilot experiments on epidermal peels suggested that some of the Na+ and Cl- is taken up into guard cells under long term NaCl stress. When Na+ and Cl- are absorbed, guard cells react sensitively and can therefore have secondary effects on the entire metabolism. The accumulation of salt ions as well as the decrease in potassium, that is well known to be a side effect of Na+ accumulation, will certainly interfere with guard cells physiology because potassium is a crucial regulator for stomatal movements. Our analysis will be done on the basis of individual guard cells to increase the spatial information about the cell type-specific physiological responses. The use of the latest high-resolution methods (EDX, SIMS) enables an analysis of the ionic composition of the individual guard cells.

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funded by: DFG

in progress since: 2022

Persons involved:
M.Sc. Roman Hartwig
Dr. Monika Wimmer
Prof. Dr. Christian Zörb

Brief Description:

In Central Europe, transient drought spells are predicted to increase due to climate change. So-called “stress imprints” describe modifications in plants that occur after a stress event and improved responses to subsequent stresses. Such modifications are in the focus of this project. Root exudates are altered under drought stress to facilitate root growth into the drying soil, but it remains an open question (i) whether physiological drought stress imprints related to root exudation occur in the rhizophere, (ii) in which spatio-temporal pattern root exudation responds to stress severity, duration and stress onset type, and (iii) how metabolic re-organization of the root system in response to drought affects post-stress plant performance with respect to stress resilience and nutrient uptake.This project addresses four hypotheses: (1) physiological drought stress imprints occur in the rhizosphere and are mediated by altered root exudation; (2) the extent of these imprints depends on the speed of onset, severity and duration of the drought event and concomittant damage to the photosystem; (3) these imprints lead to spatio-temporal re-distribution of resources towards the root and (4) they affect post-stress plant performance with respect to water and nutrient uptake. In this project, plants are exposed to different drought stress types including different intensities, durations and speeds of progression. Exudate production is determined by collecting exudates and composition is assessed by LC-MS analyses. Photosynthesis-related processes are monitored during the progression of drought, and damage to the photosystem is assessed by chlorophyll fluorescence and biochemical stress markers. The persistence of the stress imprints is determined by time course analysis during re-watering. In a rhizobox setup, one half of the roots is exposed to a single, and one half to recurrent drought drought spells. Root exudates are collected from both root halves and metabolic reorganisation of the whole plant as well as metabolic crosstalk between the root halves is monitored using a proteomic approach. Post stress plant performance is analysed by assessing the recovery time for water relations in the plant and uptake of nutrients, complemented by expression studies of aquaporins and selected nutrient transporters. The pot experiments are complemented by similar analyses of exudates collected from root windows in the field.The outcomes of these studies will provide information on the spatio-temporal interplay between drought-induced changes in photosynthetic processes aboveground, and their lasting imprints on rhizosphere-based processes belowground, mediated by alterations in root exudates. They help to gain a mechanistic understanding of underlying metabolic responses of the system root/shoot which may lead to an improved post-stress performance under conditions of sub-optimum growth conditions after drought.

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funded by: DFG

in progress since: 2022

Persons involved:
Dr. Markus Dier
Prof. Dr. Christian Zörb

Brief Description:

Grain protein concentration is the most important quality characteristic for assessing the baking quality of wheat. To achieve high grain protein concentrations, high nitrogen (N) inputs are applied. However, this is often associated with high N losses to the environment with negative environmental impacts. In modern wheat cultivars, however, the baking volume could be more influenced by grain protein composition than by concentration. For instance, there are clear differences in baking volumes between cultivars at the same protein concentration. Moreover, some cultivars show a saturation curve between baking volume and protein concentration with a non-increase of baking volume from a concentration of about 12%, whereas others display a linear relationship.

This project investigates which changes in grain protein composition caused by N supply result in an increase or decrease of baking quality. In addition, the extent to which N fertilization can be reduced in cultivars that exhibit a saturation curve between baking volume and protein concentration without loss of baking volume is investigated. The questions are investigated in a field experiment with five N levels and nine cultivars that showed a saturation curve or a linear relationship between baking volume and protein concentration in previous studies.

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funded by: Bundesanstalt für Landwirtschaft und Ernährung (BLE)

in progress since: 2020

Persons involved:
Dr. Maria Luisa Romo Pérez
Prof. Dr. Christian Zörb

In cooperation with:
Dr. Christoph Weinert (MRI Karlsruhe)
Prof. Dr. Sabine Kulling (MRI Karlsruhe)

Partner:
Kleinhohenheim

Brief Description:

A diminishing variety of vegetables is the noticeable consequence of the increasing demand for some well-known hybrid varieties. As a result, landraces are becoming extinct. The Department of Safety and Quality of Fruit and Vegetables of the Max Rubner-Institut and the University of Hohenheim (Institute of Crop Science, Quality of Plant Products, Prof. C. Zörb) have recently performed a pilot study to investigate the suitability of onion landraces for the use in organic farming as well as the storability of organically produced onion bulbs [1-2]. The ZwiebÖL project aims to continue and broaden these preliminary investigations by means of sixth work packages (WP). Firstly, a survey of the current state of onion cultivation in Germany will be performed by registering the spectrum of onion varieties currently used in conventional and organic farming in different growing regions (WP1). Next, field trials in two consecutive years on two different growing sites will be performed with 4-6 landraces and hybrid cultivars under organic farming conditions to determine the agronomic and quality parameters as well as sensory attributes of the investigated varieties in a comparative manner (WP2). Storability of the bulbs under cold storage conditions will be investigated in WP3. Fresh as well as stored onion bulbs will then be analysed comprehensively to determine the profiles of volatile and non-volatile onion constituent in the fresh state and after cold storage and to describe thus differences between landraces and hybrids (WP4/5). In collaboration with actors like the Association German Onion and the organic farming associations, a knowledge transfer will be organised to put the acquired knowledge into practice (WP6).

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funded by: Bundesministerium für Bildung und Forschung; Forschungszentrum Jülich GmbH (FZJ), Projektträger Jülich (PTJ)

in progress since: 2021

Persons involved:
M.Sc. Azin Rekowski
Prof. Dr. Christian Zörb

In cooperation with:
Prof. Dr. Sylvia Schnell, Justus-Liebig-Universität Gießen
Dr. Stefan Rutering, Justus-Liebig-Universität Gießen
Santiago Andrés Quiroga Quisaguano, Justus-Liebig-Universität Gießen

Partner:
Kleinhohenheim, Heidfeldhof

Brief Description:

Wheat and barley production will be optimized under low energy input in organic farming at two experimental field stations of University Giessen and University Hohenheim. Effects of root densities (row distance), two nutrients fertilization regimes and seed inoculation of the plant growth promotion bacterium Hartmannibacter diazotrophicus strain E19 will be analyzed in wheat as an important winter crop and in the summer crop barley. Quality parameters of produced grains differ for the two crops. For baking wheat protein quality and quantity is important while for malting barley high starch content is required. The quality and quantity parameter of the grains will be related to their root system and rhizosphere microbiome under the different treatments. The root and rhizosphere bacterial and fungal community will be metabarcode sequenced and it is expected to be specific for the two crop plants and less affected by the two soil types and locations. We aim to analyze the implication of root competition, nutrient limitation and seed inoculation on the microbiome under field conditions. Root competition will be analyzed using two different row distances under a low and optimal nitrogen fertilization regime. Root architecture and biomass will be linked to microbiome analysis and grain quality and quantity. Our results will be used for identification of optimal parameter for sustainable wheat and barley production and will lead to a bioeconomic evaluation and a knowledge based possible transfer to practice.

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CP14: Quality of harvest products in NOcsPS cropping systems

funded by: Bundesministerium für Bildung und Forschung

in progress since: 2020

Persons involved:
Dr. Markus Dier
Prof. Dr. Christian Zörb

Project coordinators:
Dr. Ingrid Claß-Mahler
Dr. Nicole Schönleber

Brief Description:

Sufficient high-quality food and biomass supplies, increasingly produced environmentally friendly, is a high-priority sociopolitical concern. The use of chemical synthetic plant protection products (csPPP) is increasingly criticized for residues in food products and the environment as well as for endangering biodiversity.

With Agriculture 4.0 this production could follow biological principles using state-of-the-art cross-linked technologies while abandoning csPPP. At the same time, the use of mineral fertilizers should ensure soil fertility for assuring the (required) high biomass yields. This approach represents a complete reorientation in agricultural production and requires diligent research from all perspectives and at all scales.

This approach represents a complete reorientation in agricultural production and requires diligent research from all perspectives and at all scales.

The aim of the joint research project involving the University of Hohenheim (UHOH), the Georg-August-University Goettingen (UGOE) and the Julius Kühn-Institute (JKI) is to develop an innovative agricultural system and to analyze opportunities and effects of this change on individual regions as well as on field, farm and regional level.

CP14: Quality of harvest products in NOcsPS cropping systems

In a nutshell

What?

We compare the quality of wheat and soybean between NOcsPS, conventional and organic farming systems.

Why?

Before NOcsPS can be widely used, it must be guaranteed that this farming system can consistently yield high product quality capable of competing with conventional and organic farming.

How?

We conduct two field trials to collect important quality data such as grain protein content and composition, baking quality, fungal toxins, and pesticide residues. In addition, because the harmful fungi, including Fusarium, Septoria, and yellow rust, presumably occur more often in the NOcsPS farming, their effect on wheat quality will be studied in container trials.

CP28: Quality of harvest products (selected special crops) in NOcsPS cropping systems

Persons involved:
Melissa Kleb
Prof. Dr. Christian Zörb

More information will be available soon.

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funded by: Bundesministerium für Ernährung und Landwirtschaft

in progress since: 2019

Persons involved:
M.Sc. Alex Kröper
Prof. Dr. Christian Zörb

Project Coordinators:
Dr. Annegret Pflugfelder
Dr. Sabine Zikeli
Dr. Sabine Gruber †

Brief Description:

The overall goal of the “LinSel” project is to provide farmers with lentil genotypes that are well adapted to Central European growing conditions. This should increase yields, yield security and quality, and as a result expand the range of lentil cultivation. As part of the project, genotypes are identified, selected and further developed and tested in order to achieve an optimal fit for cultivation systems in Germany, thereby establishing lentils as a “new” old legume crop. Cultivation of lentils is also sought beyond the traditional range. The results of the project can expand the product portfolio of breeders, farmers and consumers with a leguminous cash crop ideally suited for resource-conserving mixed cultivation and in organic farming. Project coordination lies with the Center for Organic Agriculture at the University of Hohenheim. Project partners are the Institute for Crop Science at the University of Hohenheim, focusing on general crop production and quality of crop production, the Genbank Department of the Leibniz Institute for Plant Genetics and Crop Plant Research, the Keyserlink Institute, and the Department of Section of Organic Plant Breeding and Agrobiodiversity of the University of Kassel.

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in progress since: 2019

Persons involved:
M.Sc. Markus Kränzlein
M. Sc. Patrick Lehr
Prof. Dr. Christian Zörb
Dr. Monika Wimmer

In cooperation with:
Prof. S. Schmöckel, University of Hohenheim (340k)
Prof. Dr. Waltraud Schulze, University of Hohenheim (190)

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in progress since: 2014

Persons involved:
Dr. Xudong Zhang
Dr. Monika Wimmer
Prof. Dr. Christian Zörb

Brief Description:
Stress physiological processes under salt stress in maize, especially chloride effects.

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funded by: BLE-Bundesanstalt für Landwirtschaft und Ernährung

in progress since: 2018

Persons involved:
M.Sc. Melissa Kleb
Dr. sc. agr. Nikolaus Merkt
Prof. Dr. Christian Zörb

Participating institutions:
Institut für Agrartechnik, FG Tropen und Subtropen (440e)
GEOsens GmbH LVWO Weinsberg Felsengartenkellerei Besigheim e.G.

Brief Description:

In viticulture, prediction systems for grapevine diseases represent an important component in plant protection and disease control. "FungiSens" is mainly concerned with the pathogen Plasmopara viticola (downy mildew). The main objective of this project is to improve the spatial and temporal resolution of the forecasting systems. This will be done by recording the microclimate in the vineyard and incorporating thermal, multi-spectral and hyperspectral information at the plot level.

Once high-resolution disease detection is secured, measures can be taken to reduce the use of pesticides, machinery, and labor time. This enables a temporally and spatially precise application that is superior to current professional practice in terms of cost and efficiency. This includes the reduction of pesticides while reducing machine hours and maintaining efficacy, which directly reduces chemical pollution, fuel consumption, soil contamination and greenhouse gas emissions.

Furthermore, the likelihood of pests developing resistance to common active ingredients is significantly reduced because they are applied at much lower rates. 

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