I think I already mentioned that we do not sell LED horticultural toplighting yet. Certainly not going to “spill my spectrum” before launch 
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lol I’ll include you guys of course 
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btw for those who do not dig deeper in scientific paper references:
UVB-RADIATION.pdf (536.5 KB)
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while we are at it…
Temperature response of photosynthesis.pdf (206.3 KB)
PhysiologyandMol.Biol.2008.pdf (545.9 KB)
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appropriate intermezzo
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Good stuff Theo. Thanks for all the info you’ve given us. I especially enjoyed the intermission tunes.
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Sunlight in San Diego in May
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You should probably read Terashima.
Please post a link.
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Where adequate (HIGH) levels of green are most important is in bright white light
…Because green light can penetrate further into the leaf than red or blue light, in strong white light, any additional green light absorbed by the lower chloroplasts would increase leaf photosynthesis to a greater extent than would additional red or blue light…for green light, loss in the efficiency of absorptance by the sieve effect is small [Seive Effect: the light which doesn’t continue to pass through the plants’ tissues because it has been absorbed], while gain in absorptance by the détour effect is large.[Detour Effect: light bouncing around on the inside of the space inside the leaves.] Consequently, green leaves absorb much green light…it has been clearly shown that the quantum yield of photosynthesis based on absorbed photosynthetically active photon flux density (PPFD), measured at low PPFDs, was comparable between green and red light…the quantum yield of green light is considerably greater than that of blue light…we have detailed so far, red or blue light is preferentially absorbed by the chloroplasts in the upper part of the leaf. Then, when PPFD is high, the energy of these wavelengths tends to be dissipated as heat by the upper chloroplasts, while green light drives photosynthesis in the lower chloroplasts that are not light saturated…
red light is more effective than green light in white light at low PPFDs, but as PPFD increases, light energy absorbed by the uppermost chloroplasts tends to be dissipated as heat, while penetrating green light increases photo-synthesis by exciting chloroplasts located deep in the mesophyll…
It goes beyond that green penetrates deeper into our plants’ leaves and deeper into their canopies. One of the problems with McCree or any study that is based on monochromatic light is that you do not discover how wavelengths behave synergistically. In the case of green this means missing out on important data.
It is not surprising that known photoreceptors can respond to green wavebands due to their broad absorption spectrum that tails into the green portion of the spectrum. Phytochrome can be converted to the far-red absorbing, biologically active form by green light. Green light establishes a phytochrome equilibrium favoring the active Pfr form , and green light is sufficient to activate phy responses like seed germination in Arabidopsis [citation omitted]. Other receptors change their absorption properties when activated by blue light, producing a green-absorbing state. Cryptochromes exist in a blue-absorbing native state. Upon excitation by blue light, the flavin chromophore is reduced to a semiquinone that now can absorb light from the green and yellow portions of the spectrum[citation omitted]. Illumination with green-yellow light (563 ± 10 nm) results in the inactivation of cryptochromes [citation omitted]. Green inactivation of blue-light mediated cry response has been reported [citation omitted]. The phot receptors, while unlikely receptors for pure green light [citation omitted], are profoundly sensitive, and minor blue light remnants of a green-enriched canopy are also likely highly informative [citation omitted]. There are green responses that cannot be accounted for genetically [citation omitted]. They persist in multiple null photoreceptor backgrounds and typically operate in the opposite direction to normal light responses. The identification of receptorless, antithetical responses leads to the hypothesis that a yet-to-be-defined green light sensor may mediate these responses…
Green light is a significant portion of the solar irradiation and emerging data indicate that green wavebands modulate light-induced plant responses. The coaction of green light and other light wavebands provides a strategy for a plant to precisely tune its morphology to adapt to changing light environments. Studies in the past 50 yr have shown that green light affects plant biomass [citations omitted]and reverses UV-B- and blue-light-mediated stomatal opening [citations omitted]. In the course of studying phytochrome responses, Tanada noted curious interactions between various qualities of far-red light and green light that have not been fully reconciled to date [citation omitted]. These cases are mentioned to provide a historical basis for green response and green–far-red interaction and have been detailed elsewhere [citations omitted]…seed dormancy release is stimulated by dark stratification. Germination of most dormant seeds cannot be stimulated by light unless they are treated with 20-d of dark stratification before the light exposure. Seeds stratified in far-red light have a germination rate close to dark-stratified seeds. However, seeds stratified in blue light maintain dormancy regardless of the presence or absence of far-red light. Interestingly, green light acts similarly to blue light to inhibit dormancy release in the absence of blue light [citation omitted]…
Green light can also greatly stimulate the flowering process in plants.
…plant species are affected differently by green light, sometimes by promoting flowering. The heading time of wheat does not seem to be affected by blue light (400–500 nm), but plants grown in high-fluence-rate green-yellow light (500–600 nm) require fewer days to reach 50% heading…Analysis of inductive wavebands showed that 540 nm imposed the strongest flowering stimulation effect
Hmmm, doesn’t HPS have a bunch of energy right there at 540 nm? So do well made LEDs.
1 : Green Light Drives Leaf Photosynthesis More Efficiently than Red Light in Strong White Light: Revisiting the Enigmatic Question of Why Leaves are Green;
Ichiro Terashima, Takashi Fujita, Takeshi Inoue, Wah Soon Chow and Riichi Oguchi
2 : Contributions of green light to plant growth and development
Yihai Wang and Kevin M. Folta
3 : Effect of Light Quality on Developmental Rate of Wheat under Continuous Light at a Constant Temperature
Shin-ya Kasajima, Naoto Inoue, Rezwanul Mahmud, Masakazu Kato
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Thank you for the link.
I am going to have to find my favorite visual demonstration of this phenomenon.
You make a soup of spinach leave dissolved in a solvent. Have to look up the solvent.
But you can see that the green light passes through the solution and that red light is reflected back.
You use the same method for separating out the pigments in the leaf. Besides be a cool project for high school biology classes.
We used it in a collage botany class to show you could measure the pigments in the plant.
I have used it three once for a high school student visit the university for careers in agricultural day. Once for a STEM enrichment program for high school students. And lastly for a cool science day at a boys summer camp.
Here is a link for the adventurous Extraction of Chlorophyll
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Very good!!
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You need a good broad spectrum during vegetative cycle. Green light waves are absorbed more and trigger more activity during the kalven cycle.
You need a strong shift to red to maximize flowering in cannabis as well as other horticulture crops not just a change in the day/night cycle. I don’t know if this has been documented in the recent past need to look at some journals. But, in the 1940 some work was done in hemp production. They documented massive increases in fiber production with the increase of red lighting during the flowering phase.
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I’d love a citation.
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Which do you want citations for green light absorption or red shift to promote flowering response?
I can give a journal article on hops production from Germany on red shift. How is your German. Otherwise I will have to give you journal articles from other horticulture crops.
Green light absorption I will have to see what’s free some of the best are from the journal of Plant Physiology they cost money.
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