Fluorescence decrease ratio (RFd)

Technical Support and Questions

It is possible to make, a calculation of fluorescence decrease ratio (RFd) in protocol? Thanks!

Thumb 012409 pbi 160 low low res headshot

Greg Austic

Feb 2016

Hmm... I'm not familiar with that - can you provide the calculation?

In article "How to correctly determine the different chlorophyll fluorescence parameters and the chlorophyll fluorescence decrease ratio RFd of leaves with the PAM fluorometer - H.K. LICHTENTHALER*, C. BUSCHMANN, and M. KNAPP"


"The Chl fluorescence decrease ratio RFd, defined as ratio Fd/Fs, when measured at saturation irradiance, correlates with the potential CO2 fixation rate PN of leaves as shown for several plants as well as sun and shade leaves. The ratio RFd can be expressed either by Fd/Fs or by (Fm/Fs) – 1. The ‘state 1’ of the dark-adapted photosynthetic apparatus, where Fm is reached after a few hundred ms of irradiation, is in the light gradually turned into the functional ‘state 2’ of the light-adapted photosynthetic apparatus."

Thumb 012409 pbi 160 low low res headshot

Greg Austic

Feb 2016

Ok - sure. If RFd = (Fm/Fs) - 1 I can definitely calculate that. Actually, I just did it :) That's the nice thing about the platform we've built, I can retroactively add calculations and they should auto-update across the entire platform. Check your project now, it should now include RFd (I added it for The One v2 and The One v3). If you ever want to create your own protocol in the future, you could also do that!

Do the values seem to make sense? Let me know.


Hi. There are concept of Kautsky effect curve and Kautsky. Some fluorometers can draw this curve. It is a point (OJIP-kinetics). PAM fluorometer do not draw of Kautsky curves . Do I understand correctly? Now. How I will find and identify on PAM curves of Fo, Fm, Fs, F for visualization of change. Thanks!

Default avatar

Kelvin Kamfwa

Mar 2016

The question is a bit vague, but I will try to answer. Simply put, MultispeQ can be set up to measure all of these, including PAM parameters (F0, FM, Fs, FM', F0', F0'', FM''...), fluorescence transients (including OJIP), Kautsky curves...FRR, LIFT, you name it. But, one would have to develop the protocols to make the measurements and the processing analytics to interpret the results.

So far, we have focused on the parameters that give readily interpretable results. We have avoided signals like OJIP, the interpretation of which remains highly controversial.

Having said that, it is the intent of the platform that others can generate their own protocols and we would be very interested to see what other groups do with these types of signals.

Hope that helps.