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During the transition from darkness to light, the rate of hypocotyl elongation is determined from the integration of light signals sensed through the phototropin, cryptochrome, and phytochrome signalling pathways. In all light conditions studied, from UV to far-red, early hypocotyl growth is rapidly and robustly suppressed within minutes of illumination in a manner dependent upon light quality and quantity. In this study, it is shown that green light (GL) irradiation leads to a rapid increase in the growth rate of etiolated Arabidopsis seedlings. GL-mediated growth promotion was detected in response to constant irradiation or a short, single pulse of light with a similar time course. The response has a threshold between 10?1 and 100 ?mol m?2, is saturated before 102 ?mol m?2 and obeys reciprocity. Genetic analyses indicate that the cryptochrome or phototropin photoreceptors do not participate in the response. The major phytochrome receptors influence the normal amplitude and timing of the GL response, yet the GL response is normal in seedlings grown for hours under constant dim-red light. Therefore, phytochrome activation enhances, but is not required for, the GL response. Seedlings grown under green, red, and blue light together are longer than those grown under red and blue alone. These data indicate that a novel GL-activated light sensor promotes early stem elongation that antagonizes growth inhibition.[/b]
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Monochromatic green light (GL) has been shown to act as a signal in regulating specific facets of plant physiology, inhibiting seedling mass, plant cell culture growth, and light-induced gravitropic root elongating. Recently it has been shown that GL can reverse blue light-induced stomatal opening. The GL response is mediated through a yet-to-be-defined photosensor, and genetic analyses suggest the response to be zeaxanthin based. Plant responses to GL may be initiated through known light sensors. Phytochromes and cryptochromes absorb GL and possibly influence light-induced events. However, the action/response spectra for GL-induced responses exhibit a peak between 540 to 550 nm and thus are incongruous with the absorption spectra for phytochromes, cryptochromes, and phototropins and the action spectra for the responses they govern. GL signals may also be a consequence of low-level coactivation of multiple sensory systems that together guide atypical physiological outcomes.[/b]
The entire article is very long, but you can read it here: http://www.drskunk.com/GREENLds.htm
I remember reading about green light when I first started growing... I was reading about NASA and their use of LED's, and how green light negated certain ill effects of other spectrums (although the tests were done on lettuces). On the lettuces I believe they had purple discoloration and the green led's helped make them green again.
Even back then I think it made more sense to me that cannabis would benefit more from a fuller spectrum.