Does position matter? Exploring photosynthetic characteristics of different leaflets in tomato

It is a mystery which leaflet to use when measuring photosynthesis on a compound leaf, such as in tomato. Are the photosynthetic characteristics of all leaflets representative of the complete leaf? The applied research sector holds a strong opinion that measurements of photosynthesis should never be done on a terminal leaflet of a tomato leaf (the leaf that is furthest away from the stem), as this gives weird results on photosynthesis performance. In many publications in which photosynthesis measurements were done on tomato leaves, the measurements were done either on a terminal leaflet, or it was not specified which leaflet measurements were performed on. In theory, photosynthetic performance of different leaflets on the same and healthy leaf should mostly be relevant with the local environmental conditions that individual leaflets have developed in. Therefore, in case all leaflets experienced a similar environmental condition (e.g. fully exposure to sunlight), the position of individual leaflet on the same leaf should not matter. However, to the best of our knowledge this has never been explored. The aim of this project is to explore photosynthesis characteristics (both in steady state and dynamic aspects) of different leaflets in tomato, and thus to provide a guideline of choosing leaflets for photosynthesis measurements in tomato.

Used skills

  • Performing climate chamber or greenhouse experiments,
  • Using a chlorophyll a fluorescence imager (Fluorcam, PSI), and optionally a gas exchange system (LI‐6800 or LI-6400). Measurements can be both on both steady state (e.g. dark-adapted Fv/Fm, light response curves and CO2 response curves) and dynamic (e.g. photosynthetic induction curves and loss of induction) photosynthesis.
  • Potentially, leaf pigmentation can be measured, such as chlorophyll and carotenoid content.

Interested in doing a BSc or MSc thesis at HPP? Please contact the HPP student coordinator Katharina Hanika.