Humboldt-Universität zu Berlin - Albrecht Daniel Thaer-Institut für Agrar- und Gartenbauwissenschaften

Topics for Bachelor and Master Theses

Supervision Prof. Chen and colleagues

General notes:

-The following topics require statistical processing of the results. We use "R" for this. The following online-courses introduces R step by step:
-Please, check whether you have this knowledge already. You will be accompanied by our team when familiarising yourself with the programme and processing the results.

-Additional to the thesis a R-script with the raw data is to send to the reviewers as basis for checking the reliability of the caluculations. Moreover, the access to the data in the HU-box should be possible.


Topic: Avoiding breeding selection errors in the early generations (F2-F4) by taking into account competitiveness

Selection in the F2 to F4 generations is the most important step in the breeding process. The plant populations of these generations are heterogeneous. A theoretical study on maize (Chen et al., 2019, Journal of Experimental Botany) and an experimental work with winter wheat (Weiner et al., 2017, Ecology, 98:2261-2266) suggest that the competitive ability of a genotype in a heterogeneous plant population influences its yield performance. In this context, we will investigate which plant traits play a role in competitiveness (e.g. light uptake of shoots and nutrient uptake of roots) and how competitiveness can be quantified. Using the yield performance of a genotype from a heterogeneous stand and its competitive ability, the yield performance of this genotype in a homogeneous stand will also be predicted. (Crop: winter wheat).

Research project: DFG Emmy Noether Programme (2021-2026)

Subject area: Yield physiology, plant breeding

Start of work: immediately

Type: Experimental work


Topic: Nutrient uptake (N and P) and nutrient fluxes between production systems and harvesting organs in hydroponic vegetable production

Nitrogen and phosphorus requirements of vegetables are high. How fast and when nutrients can be taken up by plants is still unclear. In this work, N and P fluxes between nutrient solution and plant organs are to be investigated as a function of controllable production parameters in order to identify influencing variables with whose regulation the N and P fluxes can be controlled in this way. This should increase yield and nutritional value for the consumer as well as nutrient efficiency. (Crop: Pak Choi, cucumber or tomato)

Research project: BMBF CUBES Circle (2020-2024)

Subject area: Ecophysiology, plant nutrition

Start of work: immediately

Type: Experimental work


Topic: Plant breeding innovations - Is the storage capacity of nitrogen and carbohydrates important for yield stability?

Yields of wheat varieties have improved considerably over the last 50 years, but not yield stability. This paper tests the hypothesis that the vegetative organs of yield-stable wheat varieties have a higher storage capacity for nitrogen and carbohydrates, which can be translocated to the grains in the generative phase. (Crop: Winter wheat)

Research project: DFG Yield stability (2018-2022).

Subject area: Yield physiology, plant breeding

Start of work: immediately

Type: Experimental work or chemical analysis or data evaluation


Topic: Physiological basis for yield stability in winter wheat

Yield stability of winter wheat is an important varietal trait for German farmers. Our knowledge of the physiological mechanisms leading to yield stability is still very limited. The aim of this work is to take a new look at yield stability using a large-scale modelling approach in combination with phenomics. One hypothesis would be that wheat varieties that can develop their plant stand more stably during the vegetative phase are also more stable in yield, as nitrogen and water-soluble carbon can be stored in the vegetative organs for grain filling. (Crop: Winter wheat)

Research project: DFG Yield stability (2018-2022).

Subject area: Yield physiology, plant breeding

Start of work: immediately

Type: Experimental work or chemical analysis or data evaluation


Topic: Influences of the ploidy degree on morphological (leaf anatomy) and physiological (gas exchange and stress tolerance) properties of plants

Changing the degree of ploidy is a plant breeding possibility to improve crop plants. The morphological changes due to ploidy degree alteration also influence the physiological functions of plants, e.g. transpiration and CO2 uptake. In this work, the influences of ploidy level in Brassica spp. (Mason et al., 2014, New Phytologist) on morphological and physiological traits are investigated to clarify the relationship between genome size and trait expression. (Crop: Brassica spp.)

Subject area: Ecophysiology, plant breeding

Start of work: immediately

Type: Experimental work


Topic: Theoretical basis of photosynthetic efficiency at the stand level (canopy enhancement).
Photosynthetic efficiency at the canopy level is higher than that at the leaf level. What determines the magnitude of this photosynthetic efficiency enhancement remains elusive. In this paper, the phenomenon of canopy enhancement will be investigated through modelling and sensitivity analysis of the model. This analysis will provide insight into the enhancement of light use efficiency and the design of plant architecture.

Subject area: Yield physiology, ecophysiology
Start of work: immediately
Type: Mathematical modelling



Non-destructive methods to investigate stomata morphology and physiology

Stomata are essential players for gas exchange in photosynthesis and transpiration. So far rather different methods are applied to determine stomata size, density and gas exchange. On the one hand a static status of segments on leaf surface is generated while on the other hand, dynamic, integrative parameters that depend on the number, size and opening dynamics of stomata are measured. With the hand microscope ProScope5, stomata size and density the number of responding stomata and its pore size can be determined non-destructive (Liang et al., 2022. Plant Biotechnology 20:577–591,; Dunn et al, 2019, J Exp Bot 70: 4737–4747, 2019,; Wall et al., 2022, New Phytologist,

Using this device, the same leaf can be investigated in different environments. Due to the high throughput of the measurements, the time course of stomata opening could be determined and various leaf segments can be compared. This methodology can be used to:

  • compare wheat cultivars under standard growing conditions regarding adaxial und abaxial epidermis characteristics (genetic variability) or
  • compare epidermis characteristics of wheat cultivars grown under various light and temperature conditions (phenotypic plasticity) or
  • analyse reaction patterns of leaves in different developmental stages and different leaf segments respectively (intragenotypic variability) or
  • link epidermis characteristic with results of gas exchange measurements (LiCor) or
  • test the applicability of that methodology for other plant species than wheat.

Subject area: leaf morphology, stomata physiology, ecophysiology

Start of work:  immediately after contact with Prof. Tsu-Wei Chen

Type: Experimental work and data evaluation or mathematic modelling


What does “Speed Breeding” select?

The method of "speed breeding" is presented as a solution to address the slow improvement rate of crops due to their long generation times (Watson et al., 2018. Nature Plants 4:23-29 By using fully enclosed growth chambers with supplemental LED lighting, this technique allows for up to six generations per year for certain crops, such as wheat, barley, chickpea, and pea, instead of the usual 2-3 generations. This accelerated breeding method can greatly accelerate research programs and has the potential to be integrated with other modern crop breeding technologies, leading to a faster rate of crop improvement. Despite its benefits, there are concerns if results from speed breeding technique can are representative for field environment, since the plants are selected in artificial environments and it remains uncertain whether only the plant traits specifically adaptive to enhancing fitness under these controlled conditions are being selected. In a previous study (Voss-Fels et al., 2019. Nature Plants 5:706-714., we assessed the grain yield and straw biomass performance of a breeding panel consisting of 60 winter wheat genotypes with diverse phenotypes under field conditions. The primary objective of this study is to investigate whether the speed breeding conditions can effectively select, from the 60 genotypes, the desired genotypes that exhibit high performance under field environments. Furthermore, if the desired genotypes are not selected, we aim to explore whether the observed differences can be attributed to the phenotypic plasticity of these genotypes.


Subject area: plant breeding leaf morphology, stomata physiology, ecophysiology

Start of work:  immediately after contact with Prof. Tsu-Wei Chen

Type: Experimental work and data analyses or statistic modelling



Topis for Fruit growing:
Supervisor: Dr. S. Müller
- Mycorrhiza application in cultivated blueberries
- The commercialisation of fruit growing using the example of Karl's strawberry farm in Elstal
- Fruit as a food supplement

If you are interested, please contact


Topic: Evaluation of salt tolerance in a F2 strawberry model population

Salt tolerance is important in artificial plant cultivation systems. One reason is the possibility to feed plants in protected cultivation at their maximum to obtain high yields. For strawberry, substrate culture and even soilless cultivation is important and increasingly used worldwide.

Wild species in the genus Fragaria L. provide salt tolerance. One typical accession is a Fragaria chiloensis subsp. lucida USA , collected nearby the „Golden Gate" in San Fransisco. Due to their exposure to the ocean high salt tolerance evolutionary resulted for these accessions.

We want to use this characteristic for breeding new cultivars and need knowledge about the inheritance and the physiological behavior of this genetic background.

  • use of an existing model population (95 genotypes with 10 plants each and the parents of the pedigree), plants prepared already (more information: DOI:10.1101/2020.06.12.148015)
  • experiment in the greenhouse (Hansabred GmbH & Co.KG, Radeburger Landstr. 12, 01108 Dresden, Germany)
  • evaluation of the physiological reaction (chlorophyll content, necrosis of leaves, growth reduction, gas exchange)
  • data management and selection of highly salt tolerant genotypes

Subject area: salt tolerance, eco-physiology, strawberry breeding, genetic ressources

Start of work:  March 2023 (supervisors: Prof. Tsu-Wei Chen/ PD Dr. Klaus Olbricht)

Type: Experimental work in the greenhouse and data evaluation or mathematic modelling


Further topics for study projects and graduate theses can be arranged directly with the lecturers.