Measuring active and passive chlorophyll fluorescence on leaves
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Measuring active and passive chlorophyll fluorescence on leaves

Measuring active and passive chlorophyll fluorescence on leaves

Future climate change will depend to a large extend on the ability of plants to increase photosynthesis (Gross Primary Productivity, GPP) with rising CO2. GPP is unfortunately not measurable directly on scales greater than a single plant. The lack of predictability of future GPP is hence one of the largest uncertainties in climate projections.

Chlorophyll Fluorescence (ChlF) is one of the pathways how photons are used when light is absorbed by leaves and hence tightly linked to photosynthesis. It is measured on leaf-scale with active techniques such as Pulse-Amplitude Modulation (PAM) fluorimetry. Remote sensing techniques to passively detect ChlF, so-called Solar-Induced chlorophyll Fluorescence (SIF), promise to study the link between ChlF and photosynthesis on larger scales up to the planetary scale with satellites. SIF should simply be proportional to the product of PAM derived measurements and absorbed Photosynthetically Active Radiation (aPAR), which turns out not to be the case. To use SIF to determine GPP, one will need to understand first SIF at the leaf-scale. We have a gas exchange system Li-6800 with a Multiphase Flash Fluorometer (PAM) for measuring photosynthesis and active chlorophyll fluorescence ChlF. We acquired a high-resolution VIS-NIR spectrometer together with an optical fibre to assemble an instrument that can measure active and passive CHlF on the same leaf at the same time. The objective of the master thesis is:

  • to help assemble the instrument to measure passive and active chlorophyll fluorescence;
  • calibrate and test the instrument on plants in the greenhouse;
  • perform first observations at different heights in the canopy of a beech forest.

We are seeking a motivated candidate who wants to work at the interface of instrument development, ecophysiology, and process modelling. This internship has the potential to be continued in a PhD thesis.


Supervisors: Matthias Cuntz, Didier Le Thiec, Emilie Joetzjer
Where: UMR Silva, INRAE Centre Grand Est – Nancy, Champenoux
When: 6 months in spring 2025
Application: send your CV and a motivation letter to matthias.cuntz(at) inrae.fr, didier.lethiec(at) inrae.fr and emilie.joetzjer(at) inrae.fr

Modification date: 13 November 2024 | Publication date: 13 November 2024 | By: Corinne MARTIN