More than 250 PhD students receive their PhDs at WUR every year. It is impossible to describe and summarize all these theses. In the column ‘PhD theses in a nutshell’ the selection of our science editors is briefly presented.
Sweet tooth
If you eat sweet things a lot, you get used to the taste and will be more likely to prefer consuming sugary products and therefore have a higher calorie intake and gain weight. Right? Eva Marija Čad got her test subjects eating hardly any sweet products, a moderate amount or lots for six months, after which she looked at how their preferences for sweet food had changed. Participants who had eaten a lot of sweet food were no more keen on sweet products at the end, while participants who had eaten hardly any such products were just as fond of sweet flavours as before. So you can’t just kick the sweet habit.
Sweet Tooth: Nature or Nurture? Assessing the Role of Dietary Sweetness Exposure on Sweet Taste Liking.
Eva Marija Čad. Supervisor Kees De Graaf
Combating plastics
Louise Schreyers’ doctoral thesis shows that our rivers are full of macroplastics — and not just the rivers that flow into the sea. She obtained a picture of how, what, where and why. Pieces of plastic get caught in plants, infrastructure, river banks and floodplains, and end up buried in sediment layers. Floods can increase the discharge of plastics by a factor of two to three. That makes clearing up after a flood a very effective measure, but more is needed to clean polluted rivers. The planned United Nations Plastics Treaty, which will be legally binding, could help reduce the influx of plastics at the source.
Lost in Transportation. Macroplastic Retention in Rivers.
Louise Schreyers. Supervisor Martine van der Ploeg
Cannabis in colour
The active substances in medicinal cannabis are mainly found in the plant’s female flowers. Mexximiliaan Holweg studied how to maximize the efficiency of plant growth — in terms of flower yield and cannabinoid concentrations — by altering the light intensity and fine-tuning the colour composition of the light. He found that the plant grows well in white light containing two different wavelengths of red, for example. The plant doesn’t like to get too hot either.
Photobiology of Medicinal Cannabis. Pharmaceutical Compounds and Crop Morphology.
Mexximiliaan Holweg. Supervisor Leo Marcelis
