Examensarbeten

Title: Pollination in agricultural settings – with international field work!

Supervisor:
Carolina Diller, Researcher, Department of Plant Protection Biology, Campus Alnarp, SLU

carolina.diller@slu.se

http://carolinadiller.weebly.com/

Brief description: Interested in working in pollination or plant reproduction and collecting your data outside of Sweden?

Apply for SLU’s Global International fieldwork scholarships (Deadline 30 October): International fieldwork scholarships for your thesis | slu.se  and contact me.

We can design a project together in countries such as Thailand or South Africa, and maybe Argentina.*

Title: Enhancing pollination precision by honey bees to garden strawberry

Supervisors: Hanna Thosteman (hanna.thosteman@slu.se), Department of Plant Protection, SLU

Paul Egan, Department of Plant Protection, SLU

Brief description: Increasing pollination precision by honey bees to target crops is a major target for agricultural pollination research. Honey bees are generalist pollinators and may show low affinity for certain crops such as pear and strawberry. To mitigate this, farmers typically increase honey bee hive stocking densities, which can have adverse effects on the surrounding natural environment. Our goal is to find solutions where pollinations effectiveness is increased in relation to hive stocking density.

What you will be doing:

You will be working with western honey bees (Apis mellifera), garden strawberry (Fragaria x annanassa) and several strains of beneficial yeasts and yeast-like fungi in an experiment where we aim to increase the visitation rate to strawberry flowers by manipulating honey bee foraging behaviour. 

This project entails:

Maintenance of live honey bee hives (field)
Maintenance of yeast cultivations (laboratory)
Field experiments in Alnarp

Time frame:

The experimental period runs from early summer (May) and throughout the typical flowering period of strawberry (roughly end of June) in 2026. It’s beneficial to enter the project slightly before experiments start, but the exact arrangement is flexible and can be discussed. Suitable for bachelor and master projects. For master projects, we recommend >30 credit theses, but this is not a requirement.

Title: Genetic mapping and phenotypic characterization of Fragaria vesca (wild strawberry)

Supervisor:
Sebastián Arenas (sebastian.arenas@slu.se), ), Department of Plant Protection, Campus Alnarp, SLU
Carolina Diller, ), Department of Plant Protection, Campus Alnarp, SLU

Brief description: Understanding the genetic architecture of agronomic traits in Fragaria vesca is essential for advancing strawberry breeding programs. In this project, we will combine phenotyping of diverse plant material, statistics analysis with DNA extraction and preparation for downstream genetic analyses (e.g. GWAS and QTL mapping). By integrating phenotypic and genomic data, we aim to identify genetic variants underlying key adaptive and agronomic traits in this important model crop.

What you will be lerning:

• Bioinformatics
• Statistics (R-language)
• Laboratory work

What you will be doing:

• Phenotypic characterization of Fragaria vesca plants under controlled conditions. 
• Recording morphological and agronomic traits (e.g. flowering time, growth, yield-related traits).
• Laboratory work, including leaf sampling, DNA extraction and quality control. 
• Preparation of samples for sequencing and genotyping. 
• Data entry and organization to support genetic mapping analyses. 

Title: Reproductive health in light of climate change: heat tolerance in wild strawberry flowers

Supervisor:
Carolina Diller, Researcher, Department of Plant Protection Biology, Campus Alnarp, SLU

carolina.diller@slu.se

http://carolinadiller.weebly.com/

Brief description: Due to climate change, plants are increasingly exposed to heat waves when flowering. This is bad news for the temperature sensitive pollen grains, as high temperatures can lead to increased pollen sterility. 

Interested in being part of the solution?

What you will be doing: In this project, we will be screening for pollen heat tolerant genotypes in the strawberry wild crop relative, Fragaria vesca (smultron).

This project entails:

• biotron work
• working with flower traits
• the plan to expose 30 wild strawberry genotypes representing North-, Central- and Southern Europe to heat stress and measure pollen viability, petal size and fruit production.

Title: Pollinator attraction in wild strawberry flowers

Supervisor:
Carolina Diller, Researcher, Department of Plant Protection Biology, Campus Alnarp, SLU

carolina.diller@slu.se

http://carolinadiller.weebly.com/

Brief description: We have a collection of 200 genotypes of wild strawberries that have been collected across Europe. We would like to screen for pollinator attractive traits and measure pollinator visitation. 

What you will be doing: In this project we would like to screen for pollinator attractive traits and measure pollinator visitation. 

This project entails:

• working outside
• measuring flower traits and observing pollinator visitation

Title: Compost, Clay or Sand? Decoding Pythium oligandrum’s Behavior Across Soil Types

Supervision:
Laura Grenville-Briggs Didymus (laura.grenville.briggs@slu.se) and Natalia Ramírez (natalia.ramirez@slu.se), Department of Plant Protection Biology, SLU

Background:
Pythium oligandrumis a beneficial oomycete known for its plant growth-promoting and biocontrol capabilities. In a previous study, its bioactivity was observed to vary significantly across different soil types. Compost-rich soils showed the strongest bio-stimulatory effects, whereas sandy soils resulted in poor performance, and high-clay soils showed negligible effects. This suggests that specific soil properties and components may influence the efficacy of P. oligandrum.

Aim:
To investigate how different soil types (clay-rich, sand-rich, and compost-rich) and nutrient amendments (sucrose addition) affect the behavior and bioactivity of P. oligandrum in vitro and in planta.

Objectives:

1. Compare the colonization and bioactivity of P. oligandrum in clay, sand, and compost-rich soil media.
2. Evaluate if certain soils with and without a carbon source enhance or inhibit P. oligandrum activity.
3. Relate these results with a trial in planta.

Methodology:

• Soil Selection and Preparation: Characterize and prepare three types of soil and soil media (clay-dominant, sandy, and compost-rich).
• Inoculation and Monitoring: Inoculate potato plants with P. oligandrum and monitor, plant growth.
• Reisolation: Reisolate P. oligandrum from potato plants grown in different types of soil 

Expected Outcomes:

• Identification of soil types that promote or inhibit P. oligandrum activity.
• Insight into whether soil-inherent compounds or nutrient availability influence its bioactivity.
• A better understanding of the factors that optimize soil environments for further studies on effective use of P. oligandrum in sustainable agriculture.

Duration:
4 months (full-time)

We have multiple openings for master's thesis, both long (1 year) and short-term (3 - 6 months) projects. If this interests you, please contact me and we can chat further on the details of the project.

Where you will work: 

• Greenhouse and/or Control growth chambers for potato plant bio-stimulation trial in planta.
• Well-equipped labs for oomycete and in vitro work.

Location:
SLU Alnarp

Title: On the Leaf Front: Temporal Analysis of P. oligandrum Viability and Blight Suppression on Leaf Tissue

Background:
Pythium oligandrum is a beneficial oomycete known for its biocontrol properties, primarily used in soil applications to stimulate plant growth and suppress pathogens. However, its potential as a foliar treatment is less explored. The possible use of P. oligandrum through foliar application may offer an advantage, especially for inhibiting pathogens that inhabit the phyllosphere. This project aims to investigate whether P. oligandrum can survive and remain effective when applied directly to leaves, and how long it can offer protection against foliar pathogens, particularly Phytophthora infestans and Alternaria solani, the causal agent of late blight in solanaceous crops.

Supervision:
Laura Grenville-Briggs Didymus (laura.grenville.briggs@slu.se) and Natalia Ramírez (natalia.ramirez@slu.se), Department of Plant Protection Biology, SLU

Objectives:

1. To evaluate the survival of P. oligandrum on leaf surfaces over time.
2. To assess the effectiveness of foliar P. oligandrum applications in controlling P. infestans and A. solani infections.
3. To determine how long P. oligandrum remains active and protective on leaves under controlled (biotron) conditions.

Methodology:

• Plants will be grown in controlled biotron conditions.
• P. oligandrum will be applied to leaves at different time points.
• Leaf samples will be taken at intervals (e.g., 0, 1, 3, 5, 7 days post-application) to assess P. oligandrum survival using microscopy and qPCR.
• Leaves will be challenged with P. infestans and A. solani spores to test the protective effect over time.
• Disease severity will be scored to evaluate the effectiveness of the treatment.

Expected Outcomes:

• Insight into the persistence of P. oligandrum on foliage.
• Determination of the window of protection it can provide against P. infestans and A.solani.
• Potential for broadening the application strategies of P. oligandrum as a foliar biocontrol agent.

Skills Developed:

• Experimental design under controlled conditions
• Plant-microbe interaction analysis
• Molecular techniques (qPCR), microscopy, and disease assessment
• Data analysis and scientific writing

Where you will work: 

• Greenhouse and/or Control growth chambers for the biocontrol and bio-stimulation experiments in planta.
• Well-equipped labs for oomycete, molecular and in vitro work.

Duration:
4 months (full-time)

Location:
SLU Alnarp

We have multiple openings for master's thesis, both long (1 year) and short-term (3 - 6 months) projects. If this interests you, please contact me and we can chat further on the details of the project.

Title: Fertilizer Levels and Their Impact on the Bioactivity of Pythium oligandrum in a 50:50 Sand–Compost Soil Mix

Supervision:
Laura Grenville-Briggs Didymus (laura.grenville.briggs@slu.se) and Natalia Ramírez (natalia.ramirez@slu.se), Department of Plant Protection Biology, SLU

Background:
Pythium oligandrum is a mycoparasitic oomycete known for its bioestimulant and biocontrol properties in agriculture. Previous studies have shown that soil composition influences its efficacy, with compost-rich soils enhancing its effect. However, we don’t know if this was because of some physical properties or due to the higher nutrient levels. how different levels of fertilizer interact with P. oligandrum in a controlled soil mix remains unexplored as well as the efficacy compare with mineral fertilizers.

 
Objectives:

1. To evaluate how different levels of fertilizer influence the biostimulant effect of P. oligandrum on plants.
2. To determine whether high fertilizer inputs suppress or enhance the beneficial effects of P. oligandrum.
3. To assess plant growth, tuber number and weight, and P. oligandrum presence after treatments.

4. To compare fertilizer application vs P. oligandrum on bio-stimulation effects.

Soil Conditions and Setup:

• Soil mixture: 50% sand + 50% compost
• Container setup: Pots 5L and soil weight grown in the biotron
• Plant species: Potato Desiree plant from in vitro

Timeline:

1st week propagating in vitro shoots 

3rd week transferring shoots to pots biotron

5th -9th week inoculating weekly from the 21st of July during a month (4 applications)

Measured Parameters:

• Plant Growth: Biomass (fresh/dry weight), height, number of shoots, number and weight of tubers
• P. oligandrum check: qPCR to verify colonization
   

Expected Outcomes:

• Identification of optimal fertilizer levels that improve P. oligandrum activity
• Understanding of whether nutrient excess suppresses biological stimulation
• Insights to refine biostimulant use in fertilized agricultural systems
• Future Applications

Findings may guide practical recommendations for combining fertilizers and biostimulants, helping farmers balance chemical inputs with biological tools for sustainable crop production.

Where you will work: 

• Greenhouse and/or Control growth chambers for the biocontrol and bio-stimulation experiments in planta.
• Well-equipped labs for oomycete, molecular and in vitro work.

Duration:
4 months (full-time)

Location:
SLU Alnarp

We have multiple openings for master's thesis, both long (1 year) and short-term (3 - 6 months) projects. If this interests you, please contact me and we can chat further on the details of the project.

Title: One Biostimulant, Many Responses: Assessing Potato Cultivar-Specific Reactions to Pythium oligandrum in a Hydroponic System

Supervision:

Laura Grenville-Briggs Didymus (laura.grenville.briggs@slu.se)
Natalia Ramírez (natalia.ramirez@slu.se)
Department of Plant Protection Biology, SLU

Background:
Plant biostimulants are increasingly used to improve crop growth, resilience, and nutrient use efficiency in sustainable agriculture. However, their effectiveness is often highly dependent on plant genotype. Potato (Solanum tuberosum L.) is a genetically diverse crop with a wide range of cultivars that may respond very differently to the same biostimulant treatment.

Pythium oligandrum is a beneficial oomycete known for its plant growth–promoting and biocontrol properties. While its biostimulatory effects have been demonstrated, how different potato cultivars respond to P. oligandrum under controlled conditions remains poorly understood.

Hydroponic systems provide a highly controlled environment that eliminates soil-related variability, allowing direct comparison of cultivar-specific responses. This project will use hydroponics to systematically evaluate how different potato cultivars respond to P. oligandrum under contrasting nutrient conditions.

Aim:

To determine how different potato cultivars respond to the biostimulant Pythium oligandrum under hydroponic conditions, with a focus on plant growth and root development.

Objectives:

1. Compare growth responses of selected potato cultivars treated with P. oligandrum.
2. Quantify cultivar-specific differences in shoot and root development.
3. Assess whether nutrient availability influences cultivar responsiveness to biostimulation.

Methodology:

• Plant Material: Potato plants will be obtained from in vitro cultures to ensure uniform and healthy starting material before transfer to hydroponic systems.
• Cultivar Selection: A collection of 96 potato cultivars is available. The final number of cultivars included will be defined together with the student, based on project duration and workload. Cultivars will be carefully and strategically selected to ensure meaningful and manageable comparisons.
• Hydroponic Experiment: Plants will be grown under controlled environmental conditions using two nutrient regimes: a standard nutrient solution and a nutrient-limited (scarce) medium, allowing evaluation of responses under both optimal and suboptimal conditions.
• Biostimulant Treatment: All selected cultivars will be exposed to the same biostimulant, Pythium oligandrum, alongside appropriate untreated control plants.
• Phenotyping: Plant performance will be assessed through measurements of shoot height, root length, biomass, and overall plant vigor.
• Data Analysis: Results will be statistically analyzed to identify cultivar-specific responses and interactions between nutrient availability and biostimulation.

Expected Outcomes:

• Identification of potato cultivars that respond strongly, moderately, or weakly to P. oligandrum.
• Improved understanding of genotype-dependent biostimulant effects.
• Foundational knowledge to support targeted and more reliable use of biostimulants in potato production and future soil-based studies.

Where you will work:

• Controlled growth chambers and hydroponic facilities for potato biostimulation experiments.
• Well-equipped oomycete laboratories, in vitro laboratories, and growth chambers for plant cultivation, phenotyping, and data analysis.

Duration:
4 months (full-time)

Location:
SLU Alnarp

We have multiple openings for master’s thesis projects, including long-term (1 year) and short-term (3–6 months) projects. If this project interests you, please contact us and we can discuss the scope, cultivar selection, and experimental design in more detail.

Title: Two Ways, One Biostimulant: Comparing Potato Responses to Pythium oligandrum Tubers Inoculation vs. Drench Application

Supervision:
Laura Grenville-Briggs Didymus (laura.grenville.briggs@slu.se)
Natalia Ramírez (natalia.ramirez@slu.se)
Department of Plant Protection Biology, SLU

Background:
Plant biostimulants are increasingly used in sustainable agriculture to enhance crop growth, stress resilience, and nutrient use efficiency. Pythium oligandrum is a beneficial oomycete known for both biocontrol and plant growth–promoting effects. However, the efficacy of biostimulant treatments often depends on the method of application.

In potato (Solanum tuberosum L.), biostimulants can be applied either directly to the tuber surface before planting or as a drench to the root zone of young plants. The comparative effectiveness of these two methods is not well understood, particularly regarding early growth, root establishment, and overall plant vigor.

This project will experimentally test how Desirée potatoes respond to P. oligandrum when applied to tubers versus drench applications under greenhouse conditions, providing insight into the most effective delivery method for biostimulant treatments in soil-grown plants.

Aim:
To compare the effects of Pythium oligandrum applied to Desirée potato tubers before planting versus drench application on plant growth and root development under greenhouse conditions.

Objectives:

• Compare growth responses of Desirée potato plants treated with P. oligandrum via tuber inoculation or drench application.
• Quantify differences in root and shoot development between the two application methods.
• Assess overall plant vigor and early establishment under both treatments.

Methodology:

• Plant Material: Potato tubers of the cultivar Desirée will be sourced from uniform, disease-free stock.

• Greenhouse Setup: Tubers will be planted in pots containing standard potting soil and grown in controlled greenhouse conditions (light, temperature, and humidity monitored).

• Biostimulant Treatments:

Tuber Inoculation: Tubers will be coated with a P. oligandrum suspension prior to planting.
Drench Application: An equivalent dose of P. oligandrum will be applied as a root-zone drench to young plants after emergence.
Control: Untreated Desirée plants will serve as negative controls.

• Phenotyping: Plant performance will be assessed through shoot height, leaf number, root length, root biomass, total biomass, and overall vigor at multiple time points.
• Data Analysis: Statistical analyses (ANOVA, post-hoc tests) will determine differences between application methods, with assessment of effect size and significance.

Expected Outcomes:

• Identification of the more effective P. oligandrum application method for Desirée potatoes under greenhouse conditions.
• Quantitative understanding of early plant growth and root development responses to tuber inoculation versus drench application.
• Practical recommendations for growers and researchers regarding biostimulant application strategies in potatoes.

Where You Will Work:

• Greenhouse facilities for potato cultivation and biostimulant experiments.
• Well-equipped oomycete laboratories and in vitro laboratories for preparation of P. oligandrum inoculum.
• Growth chambers and labs for plant phenotyping and data analysis.

Duration:
4 months (full-time)

Location:
SLU Alnarp

Multiple openings are available for master’s thesis projects, including long-term (1 year) and short-term (3–6 months) projects. If this project interests you, the scope and experimental design can be discussed in detail with the supervisors.