Thread: LED Grow Light
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Old 04-17-2018, 10:26 AM   #49 (permalink)
aruzinsky
 
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Default Re: LED Grow Light
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Originally Posted by speakeasy View Post
I use software on my computer to gradually change the color temperature on my screen for this reason. https://justgetflux.com/

I grow in the vegetative phase with 4000K lights which are pretty neutral (I also have some 2700K lights). But I make sure they're off at 7pm. And I agree with you, the problem with violet at 400nm is that's where chlorophyll absorption rates start to drop off.
The backlighting in LCD monitors and TVs (and, maybe, smartphones?) is currently the same as the light emitted from typical household lighting bulbs, either fluorescent or LED. Possibly, the manufacturers of those monitors will switch to the violet rich LED lighting and then you can keep the color temperature on your screen high.

I aesthetically prefer 8000K household lighting and use Sylvania Sky White fluorescent, when I can. Blue is my favorite color.

https://www.youtube.com/watch?v=gKrlRCH_M00


Another reason that I like Sylvania Sky White is that they emit no yellow wavelengths near 590nm, which improves the appearance of Caucasian skin by deaccentuating yellow blotches. Maybe, that explains the popularity of GE Reveal Incandescent bulbs which also emit no light near 590nm.

There is some evidence that wavelengths near 590nm are bad for plants.

https://www.ncbi.nlm.nih.gov/pubmed/16660793

https://jxb.oxfordjournals.org/conte.../3099.full.pdf

In this paper, all light between 500 nm and 600 nm, is called "green" and some of the bad effects attributed to "green" are actually attributable to yellow near 590nm. Note:

"Dougher and Bugbee (2001). The study compared the growth of lettuce (Lactuca sativa) seedlings under metal halide and high pressure sodium lamps. When conditions were compared, appreciable differences in dry mass, leaf area, and chlorophyll content were noted. However, the light conditions were identical in terms of calculated phytochrome photoequilibrium, blue light, red light, far-red light, and relative ratios between them. The only difference was a significant component between 580–600 nm. The authors conclude that this band of wavelengths generates negative effects on plant growth, in agreement with the green light data presented in Went (1957) and Klein et al. (1965). These reports present a common theme of a negative role for 500–600 nm light in plant growth."
Last edited by aruzinsky : 04-17-2018 at 10:28 AM.
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