Light Quality Affects Chloroplast Electron Transport Rates Estimated from Chl Fluorescence Measurements

Chl fluorescence has been used widely to calculate photosynthetic electron transport rates. Portable photosynthesis instruments allow for combined measurements of gas exchange and Chl fluorescence. We analyzed the influence of spectral quality of actinic light on Chl fluorescence and the calculated...

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Bibliographic Details
Published in:Plant and cell physiology 2017-10, Vol.58 (10), p.1652-1660
Main Authors: Evans, John R, Morgan, Patrick B, von Caemmerer, Susanne
Format: Article
Language:English
Subjects:
Carbon Dioxide - metabolism
Chlorophyll - metabolism
Chloroplasts - metabolism
Chloroplasts - radiation effects
Electron Transport - radiation effects
Fluorescence
Light
Models, Biological
Photochemical Processes - radiation effects
Photosynthesis - radiation effects
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Summary:Chl fluorescence has been used widely to calculate photosynthetic electron transport rates. Portable photosynthesis instruments allow for combined measurements of gas exchange and Chl fluorescence. We analyzed the influence of spectral quality of actinic light on Chl fluorescence and the calculated electron transport rate, and compared this with photosynthetic rates measured by gas exchange in the absence of photorespiration. In blue actinic light, the electron transport rate calculated from Chl fluorescence overestimated the true rate by nearly a factor of two, whereas there was closer agreement under red light. This was consistent with the prediction made with a multilayer leaf model using profiles of light absorption and photosynthetic capacity. Caution is needed when interpreting combined measurements of Chl fluorescence and gas exchange, such as the calculation of CO2 partial pressure in leaf chloroplasts.
ISSN:0032-0781
1471-9053
DOI:10.1093/pcp/pcx103