My day-job is a PhD candidate in Wageningen University, the Netherlands. I got my BSc and MSc in plant breeding, after which I landed at this current PhD position in horticulture.

Here are some works I have published.

Blue and red LED lighting effects on plant biomass, stomatal conductance, and metabolite content in nine tomato genotypes

T. Ouzounis, E. Heuvelink, Y. Ji, H.J. Schouten, R.G.F. Visser, L.F.M. Marcelis

A collection of nine tomato genotypes was chosen based on their diversity, phylogeny, availability of genome information, and agronomic traits. The objective of the study was to characterize the effect of red and blue LED (light-emitting diode) lighting on physiological, morphological, developmental, and chemical parameters. Two LED light treatments were imposed: (1): 100% red and (2): 88% red/12% blue (peak emission at 662 and 456 nm for red and blue light, respectively). The combination of blue and red LED lighting increased total dry matter in seven of the nine genotypes compared to red. Upward or downward leaf curling was observed in all genotypes in the 100% red treatment. Stomatal conductance was not affected much by additional blue light, but blue light increased chlorophyll and flavonol contents in three genotypes. The exposure of tomato plants to a combination of red and blue LEDs alleviated leaf morphological abnormalities and enhanced plant biomass, and variably affected stomatal conductance and secondary metabolism compared to red light alone.

https://www.actahort.org/books/1134/1134_34.htm

Perspectives for breeding for nitrogen efficiency in head cabbage: Literature review (in Dutch).

A Hospers-Brands, Y Ji, PC Struik, ET Lammerts van Bueren

Cabbage is an important crop in the Netherlands. Brassica species require high levels of nitrogen (ca. 300 kg N/ha) for a good crop growth, often more than can be delivered in an organic rotation within the current regulations for organic agriculture. Nitrogen increases the yield but at high levels of nitrogen the yield reaches a ceiling. In the past much research has been conducted to optimise fertiliser application. To further advance sustainable crop management an important question is which cultivars are robust enough to produce an economically acceptable and stable yield under low nitrogen input levels and under variable weather and growing conditions. It is also relevant to assess which plant traits are associated with nitrogen efficiency. Through literature research, expert consultations and farmer field visits, the perspectives are explored to breed for improved nitrogen efficiency in Brassica types, especially head cabbage. Nitrogen efficiency is the resultant of two component traits: nitrogen uptake efficiency and nitrogen utilisation efficiency. These traits should always be considered in relation to each other as genotypes can combine different strategies to cope with low availability of nitrogen. Most research on nitrogen efficiency in Brassica has been conducted for oil seed rape, Chinese cabbage and cauliflower. However, in our research we found interesting clues to improve nitrogen efficiency in head cabbage. For the uptake capacity a good rooting system is a prerequisite. Apparently, cabbage is able to root until great depth and is capable of capturing nitrogen efficiently from the soil. However, no research is available on genetic variation in rooting characteristics (depth, density, and plasticity) in cabbage under low nitrogen availability. As in organic fertility management nitrogen is less available through mineralisation under cold stress, it is important to include early cultivars in the research. It also became clear from the literature review that in order to properly explore genetic variation in root systems diverse locations should be included as genetic variation is not always expressed at all sites. From the literature we learned that for cabbage most benefits are to be expected from improved nitrogen utilisation efficiency. It appears to be important that the outer leaves remain active until harvest to enhance nitrogen uptake. Also the redistribution from older outer leaves to the young inner leaves forming the head and photosynthetically inactive is relevant. These physiological aspects of utilisation, the ratio between outer and inner leaves (head), and related processes can differ among early, mid-early, and late cultivars. Future research should explore the most ideal ratio between outer leaves and head (harvest index) in relation to nitrogen efficiency, and to what extent leaf attitude and leaf canopy development play a role. In addition it will be interesting to assess whether also other selection criteria can be applied, e.g. leaf area index, specific leaf area index, nitrate reductase activity and / or chlorophyll content or fluorescence.

http://www.louisbolk.org/nl/publicaties/publicatie/?pubID=2896