Like that "official " chlorophyll absorption charts are more or less useless ,
Back in seventh grade I was introduced to the Spectronic 20, or “Spec 20” for short. For those readers that are unfamiliar, it is essentially a tan breadbox with two dials, an analog meter, a dial to determine the wavelength transmitted, and a chamber for introducing a sample in a test tube. The device was originally made by Bausch & Lomb back in 1954, and even modern iterations reflect the basic, industrial, sturdy simplicity of the original model.
Back in 1980 we were given the charge to determine which wavelengths chlorophyll absorbed best. I don’t remember how we purified our sample, I just know that I zeroed the machine using a blank filled with water using the dial on the left, lowered the sample into the chamber, closed the lid, and then recorded the values for light absorption as we marched across the dial—from the UV to past the red wavelengths. From these readings we’d build a graph that would reflect an absorption spectrum for chlorophyll, absorbing light in the blue and red most efficiently, while offering little tono absorption in the green, yellow, orange and far-red regions of the spectrum.
Some basic hypotheses could have been constructed from these findings. Certainly the qualities of light that excite chlorophyll must provide information to the plant as well. In my third year of college I learned that this was so. I learned that red and blue light would trigger photomophogenic development. We discussed effects in a variety of plants, from peas to mung beans, to tobacco, to Lemnaas well as studies of chloroplast orientation in the green alga Mougeotia. There were even studies in a strange plant called Arabidopsis thaliana. All showed developmental effects of light, but mostly blue and red wavelengths. The correlation between the wavelengths that stimulated development and drove light-regulated metabolism was no surprise. Some wavelengths impart valuable information to the plant that promotes growth, development and photosynthetic capacity. Other wavelengths, like far-red and green, are not so important for metabolism but they are not benign- they shape plant processes in other ways that optimize light capture and adaptation. - Dr. Kevin Folta, The Guiding Force of Photons
I do not know if you know anything about Folta. He is considered one of those that know more about photosynthesis than anyone else on this planet. So I have been told by a few that should know if it is true or not.
http://www.hos.ufl.edu/faculty/kmfolta Notice this March 2000- November 2002: Postdoctoral Research Associate, University of Wisconsin, Madison, WI. Where and when was it discovered that blue inhibits elongation when added to red?
Maybe it is taught differently in other parts of the world. In the US it is taught that 500nm-600nm is a "green hole".
Even the latest textbooks like this authoritative 2014 graduate level text shows an absorbance and action curve previously posted . It is explained a little bit in topic 7.1 on this web page:
http://6e.plantphys.net/ch07.html
I do understand there is other opinions on the topic but I find the text is very carefully worded. I did once upon a time read the NASA study. But I think this recent one I attached "Green Light Drives Leaf Photosynthesis More Efficiently than Red Light in Strong White Light" is more detailed.
It says:
It is also known that green light, once absorbed by the leaves, drives photosynthesis with high efficiency.
The key phrase being " once absorbed".
It also says:
On an absorbed quantum basis, the efficiency or photosynthetic quantum yield of green light is comparable with that of red light, and greater than that of blue light.
The key phrase being "On an absorbed quantum basis"
It also says:
...many spectra of absorptance (the absolute value of light absorption) measured with integrating spheres have shown clearly that ordinary, green leaves of land plants absorb a substantial fraction of green light ( McCree 1972...
But does it?
Also the "spectra of absorptance" does not refer to photosynthesis, but rather absorption like that of any material like that used in the studies to identify cannabis fields by air photography by the reflected spectrum analysis.
The above quotes are highlighted in the attached study on pages 1 and 2 for context.
I have also attached the McCree Study. On page 210 there is a table of the Absorptance. These are absolute values. Absorption drop 10% between 500 and 525nm another 7% at 555nm\ then slowly makes it back to 90% absorption at 650nm. That's not too bad. But then on Page 208 the RELATIVE Action table. Relative meaning after the 10-15% loss in absorption the action losses are added relative to the absorption loss. Then further loss, Quantum Yield, relative to the combined absorption and action loss is added on Page 206
At 525nm is , the action is 81%, relative to absorption action is 55%, and quantum yield adds another 26% loss at 74%
action 81% + 55% absorption = 44%, + 74% from QY = 32% or a total of 67% loss
At 625nm is , the action is 88%, relative to absorption action is 95%, and quantum yield is 100%
action 88% + 95% absorption = 83.6%, or a total of 67% loss of 16.4%
Green loss = 67% Red loss = 16%.
That is why I have my doubts about green vs. red regarding photosynthesis.
