Reflective Mylar

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techhead420

Well-Known Member
alka said:
LOL, bonz.... if wood absorbed light it would be ..... well .. black...

here's something simple.. the brighter the wood appears, the more light it is reflecting. I wasn't saying the wood has anything to do with my yields, but the only reason we see anything is because light is being reflected from is surface. (thats why plants are green... they do not absorb the wavelength from green light and therefore reflect it, so you see a plant as green.

wood is the same, if you are looking at a piece of wood that is light colored or tan, it is reflecting that wavelength of light... not absorbing it.

Sorry to be the first to tell you this in 20 years.
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Plants do in fact absorb green light. They're green because they do not absorb AS MUCH green light as other wavelengths. Green light is important in photomorphogensis studies due to the auxin (a plant hormone) boost that green light will give. The chart below will vary for different leaves and should be taken as ballpark numbers.



Here's what various lights give off (sorry it's so big!):

 
bonz

bonz

Well-Known Member
plants dont see the same light and colours as us. i will try to find the info for ya
i looked at the link, thats the same thing i do painting cars. mix colours to make others basicaly or to block others if i mix to much in.
 
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alka

Active Member
ok, ok... it might absorb a little but a very very small amount... and it doesn't need it for photosynthesis. you can run a green light during a plants dark phase and not disrupt the hormone changes associated with the shortened day.

My point was that the light that we see from any object is the light that does not get absorbed (unless its emitting light). So if we are running a hps bulb, a white reflective surface would be just as effective as a yellowish hpsodiumish color. and under the hps light both would look the same. Its weird, under a small hps and some warm cfl's the wood "looks" like it could be white. if i stick a piece of white paper in front it also becomes yellow, just like the pine.

As for auxins.... green light is supposed to do what exactly?... Please explain what green light does for the plants hormone levels.
 
bonz

bonz

Well-Known Member
ok then try this one.
i understand your thinking but you are losing lumens when it hits the wood. so in that sense it is not good
 
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techhead420

Well-Known Member
alka said:
ok, ok... it might absorb a little but a very very small amount... and it doesn't need it for photosynthesis. you can run a green light during a plants dark phase and not disrupt the hormone changes associated with the shortened day.

My point was that the light that we see from any object is the light that does not get absorbed (unless its emitting light). So if we are running a hps bulb, a white reflective surface would be just as effective as a yellowish hpsodiumish color. and under the hps light both would look the same. Its weird, under a small hps and some warm cfl's the wood "looks" like it could be white. if i stick a piece of white paper in front it also becomes yellow, just like the pine.

As for auxins.... green light is supposed to do what exactly?... Please explain what green light does for the plants hormone levels.
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Plants don't absorb "very, very small" amounts of green light. Look at that chart above and you can see roughly what the numbers actually are. Some plants, such as purple basil, can absorb green light better than other plants, such as sweet basil. Any photon in the PAR (about 400-700nm) range can be used for photosynthesis

White paper can look white under HPS due to chromatic adaptions in our eyes:

Adaptation | Chromatic Adaptation | Light Adaptation | Dark Adaptation | Transient Adaptation | Transient Adaptation Factor | Adaptive Color Shift

Green light can be used as a safe light because it's the red-far red ratios that cover photoperiod, not green. This is controlled by a molecule called phytochrome:

Phytochrome - Wikipedia, the free encyclopedia

Green light will boost a chemical called indole-3-acetic acid which is an auxin. Indole-3-acetic acid works by loosening the cell walls allowing them to stretch (blue has the opposite affect, that's why we want more blue light in veging, excess green will cause elongation). The is an artifact from evolution, lower leaves will have a larger green-blue ratio of light because more green light is being filtered through the leaves. In response to this they stretch to get to the light.

Auxins are important in the biosynthesis of another hormone called ethylene. Ethylene controls ripening and is why plants grown under LEDs tend to take longer to ripen compared to HPS (no green light in red/blue LED grow lights).

I really need to write an article on this forum dealing with photobiology so that I can just link to it.

Auxin - Wikipedia, the free encyclopedia
Indole-3-acetic acid - Wikipedia, the free encyclopedia
 
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alka

Active Member
ok techhead thanks for the links i will check it out.. don't get me wrong i am not claiming to be an expert i was merely responding (poorly) to the statement that wood does not absorb light.

I should have left it as the only reason we see plants as "green" is because that wavelength is being reflected back at us... some...
 
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