%Pfr = Pfr / (Pfr+Pr)
Think of %Pfr like plants' color vision. Pfr and Pr are like 2 cones in plant vision. The difference in "cone" absorbances gives the plant a gradient to tell how high the "quality" of the light is.
Certain wavelenths like 660nm will make %Pfr very high. Pure 660n light will put %Pfr at around 85%. This is because Pfr and Pr both absorb at 660nm, so you can't ever get %Pfr to 100%.
You can get %Pfr to 0% though, because Pr doesn't absorb at 730nm but Pfr does. This means 730nm will cause %Pfr to go all the way to 0%. (all Pfr converted to Pr).
If you were to shine just 500nm at the plant, from this chart, %Pfr would converge at around 50%, since Pr and Pfr absorb equally there. (assuming that chart is correct)
The chart also shows that light between 340nm and 390nm will raise %Pfr above 50% while light between 390 and 460nm will lower it below 50%. Not exactly relevant to this particular question, but maybe interesting to people who haven't thought about that yet.
Right now,I'm making a spreadsheet tool (it all started from 'decoding' CXA3070's rel.power graph ...LOL),
specially for
analysing a LED/COB 's output light ...
In plant biology terms and units ,not just Volts,Watts,Lumens(!) , Amperes,etc ...
-It already features analytical "25 nm band" ,measurements of quantum flux for the range of 380-780 nm ..
-A Cannabis Sativa L. species dedicated ,
leaf Lamina Adaxial Reflection & Abaxial Transimission of quanta,
estimation/ calculation
-Thus the
cannabis leaf Absorptance is estimated ,
as part of a new Rel.Quantum Yield .
Cannabis species dedicated !
(It incorporates also the McCree,1972 RQE in it's functions... )
-
Daily light Integral figures for 12 /16 /18 and 20 hour irradiation regimes " per dia "
(The plant's "day cycle" = dia =latin for day ...Carpe
Diem !)
-Photosynthetically Active Weighted spectral plot and info of output light ...
-I'm thinking about adding a "SSL Photoinhibitory Efficiency " ..
Although kida tricky this one ...
(have to combine more than few photoreceptor pigment's action spectra ,with
aΦ generallized photoinhibition efficiency spectrum ..)
And right now I'm working on phytochrome ...
(wiil have the feature of two separate plots of light output ,one for Pfr ,one for the Pr ...
A combined -convolved one ...LED's -Cob's Pfr / Pr ratio and the
PPE/PPtostationary state value of the led/cob ..(Pfr / Phy total )
(phytochrome photo equilibrium aka phytochrome photo stationary state ...)
I got also a good plot to digitize ...
And something about the % of Pfr / Pr ...
"
D. Efficiency of photoconversion
Phytochrome acts like a weird light switch that only turns off/on a portion of the lights. In other words, red light treatment of Pr results in about
85% Pfr + 15% Pr; far red light treatment of Pfr results in
97% Pr + 3% Pfr. Thus, at photo-equilibrium not all the phytochrome is interconverted. The reason for this is because the absorption spectra for the two pigments overlap and they are essentially competing reactions.
A measure of the efficiency conversion is the ratio of the Pfr to the total which is expressed as follows:
efficiency = Pfr/(Pr+Pfr = phytochrome total)
In red light = 0.85; far red 720 nm = 0.03; this varies with the environment (see text and overhead)
http://employees.csbsju.edu/ssaupe/biol327/Lecture/phytochrome.htm
http://cpl.usu.edu/files/publications/poster/pub__6740181.pdf
Analysing the led's/COB's biological (plant growth ) abilities and capabilities to deepest possible ....
All it takes is a digitizer a calc/spreadsheet ,some time & plenty of love for the art/science of it ...
Everything else (data,research papers,plots,pics ,etc ) are a piece of cake ,to be found ...
(Ok ,in fact I'm doing some 'smart-ass ' math work ,using other's reseaches and results ..
Information and data ,already available... )
Cheers.
..._
