Greenhouse crops are frequently grown under high [CO2] due to the application of supplementary CO2. Net photosynthesis rate typically increases with an increase of [CO2]. However, plants that have developed and acclimated to high [CO2] generally decrease leaf photosynthetic capacity, partly due to decreased leaf nitrogen content and lower stomatal conductance (gs). The drop of gs under high [CO2] is relevant with changes in stomatal anatomy in some species, i.e. decreases in stomatal density and/or stomatal size, but not in others. Despite many studies on the acclimation effects of high [CO2] on steady-state photosynthesis, little is known about the effect of high [CO2] acclimation on dynamic photosynthesis. High [CO2] acclimations in biochemistry (e.g. changes in Rubisco content) and stomatal anatomy (e.g. changes in stomatal density) could potentially affect photosynthetic induction and the post-illumination assimilation period.
The objective of this project is to investigate the effect both biochemical and stomatal acclimation on dynamic photosynthesis under high [CO2]. To this end, three commercially important horticultural species, i.e. tomato, cucumber and chrysanthemum, will be used. Furthermore, these species have a distinct difference in stomatal anatomy.
Performing climate chamber experiments using a gas exchange system (LI‐6800). Taking stomatal imprints and measuring stomatal size and density, as well as pore length and width. Optionally, measuring pore area opening kinetics using a custom-built microscope that can follow movement of single stomatal pores in real time. Measuring leaf chlorophyll content and carotenoids content.
Interested in doing a BSc or MSc thesis at HPP? Please contact the HPP student coordinator Katharina Hanika.