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Importance of 460nm red LEDs?
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Originally Posted by thepaan
For the whole grow. Flowering is accomplished by changing the length of the night (long nights induce flowering in most cannabis strains).
I understand this, but are you saying the oft-quoted "more blue for veg; more red for flowering" is not correct?
Seems you have the 'metal halide for veg and HPS for flower' meme, and the latest 'one light (CMH or properly designed LED) for the whole grow.
Now, I am not sure how much the solar spectra changes (filtered through the atmosphere) from spring to fall - if in fact we are somewhat attempting to
mimic nature.
Just lots of conflicting 'information' floating around that I am seriously trying to grok.
Thanks for all your scientific references! :thumbsup:
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Importance of 460nm red LEDs?
"Now, I am not sure how much the solar spectra changes (filtered through the atmosphere) from spring to fall - if in fact we are somewhat attempting to
mimic nature."
Insolation changes very little at the equator and swings a bit wider from the tropics up to about 55 degrees latitude north or south. The only real change is the angle at which the sun hits our atmosphere which adjusts refraction and dispersion, and this happens due to Snell's law (going from vacuum of space to atmosphere) and our orbital position/axial tilt.
My panels are designed to emulate this effect in separate modules. Maybe another redesign will allow for adjustment to suit individual plant varieties but as far as general-purpose seasonal emulation goes I've probably got the best available.
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Importance of 460nm red LEDs?
Quote:
are you saying the oft-quoted "more blue for veg; more red for flowering" is not correct?
More or less, yes.
As khyberkitsune said, the spectral content of light leaving the sun doesn't change; only the portion making it through the atmosphere does. I never considered if that would affect growth since I have never seen any studies along those lines. If I had to guess, I'd say it doesn't matter but honestly, I'm not sure.
Back to the question. I don't know why so many people think they need to change the color of the light, though I suppose it works since so many people do it. This is my guess: The cause of flowering (from light) clearly has nothing to do with blue wavelengths because phytochrome simply does not react to blue light. We are left with red light as the causal factor. Since cannabis is a short-day plant (flowering when the days become short or, long-night) and the day length is determined by duration of red light, then exclusive blue light (suggested for vegging) would cause the plant to reach the flowering stage more quickly due to a phytochrome-perceived perpetual night (is this the desired result?). But even MH should have enough red light to cause the day to be perceived and thus to postpone flowering. This is why I can't figure out why people say to use blue light. You can keep the plant from flowering by just leaving the lights on longer. The only advantage I can think of would be to give the plant more light but make it think it has a short day but that is not what they are doing.
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Importance of 460nm red LEDs?
Quote:
Originally Posted by thepaan
More or less, yes.
As khyberkitsune said, the spectral content of light leaving the sun doesn't change; only the portion making it through the atmosphere does. I never considered if that would affect growth since I have never seen any studies along those lines. If I had to guess, I'd say it doesn't matter but honestly, I'm not sure.
Back to the question. I don't know why so many people think they need to change the color of the light, though I suppose it works since so many people do it. This is my guess: The cause of flowering (from light) clearly has nothing to do with blue wavelengths because phytochrome simply does not react to blue light. We are left with red light as the causal factor. Since cannabis is a short-day plant (flowering when the days become short or, long-night) and the day length is determined by duration of red light, then exclusive blue light (suggested for vegging) would cause the plant to reach the flowering stage more quickly due to a phytochrome-perceived perpetual night (is this the desired result?). But even MH should have enough red light to cause the day to be perceived and thus to postpone flowering. This is why I can't figure out why people say to use blue light. You can keep the plant from flowering by just leaving the lights on longer. The only advantage I can think of would be to give the plant more light but make it think it has a short day but that is not what they are doing.
The hormone that triggers flowering in cannabis has to build up - ANY light that triggers photosynthesis will destroy this hormone and interfere with the flowering process up until nearly the end of flowering (some clever people run their plants indoors for the first 6 weeks then finish them up outdoors in the summer sun because the hormone has built up so much that the plant cannot easily revert back into a vegetative stage.) Doesn't matter if it's blue light or red.
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Importance of 460nm red LEDs?
wow, very technical thread !
thanks to you guys who know this stuff so the rest of us can learn :thumbsup:
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Importance of 460nm red LEDs?
Ok so....
Ive read tons and tons since I started indoor growing. Ive always taken the blue light/mh/veg and red light/hps/flower comments as fact since ive read it so many places. Im now having problems finding the science behind that. I kept reading over what he was asking and I see where he is coming from. I looked at the charts on a page someone linked up above and it shows the peak absortion rates for Chloro A,B, and C. Like he said it shows the peak levels near the green and yellow. So why make these LEDs exact sectrums that are so low on the peak absortion chart?
Maybe im missing something....
Ive also read on some peoples logs that running MH or HPS the whole way makes no difference in their grows. I realize that people just typed out half a science textbook worth of info but I didnt see anywhere explaining why 400nm and 660nm are so important if they are so low on the absortion chart.
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Importance of 460nm red LEDs?
Quote:
Originally Posted by GetThisOrDie
Ok so....
Ive read tons and tons since I started indoor growing. Ive always taken the blue light/mh/veg and red light/hps/flower comments as fact since ive read it so many places. Im now having problems finding the science behind that. I kept reading over what he was asking and I see where he is coming from. I looked at the charts on a page someone linked up above and it shows the peak absortion rates for Chloro A,B, and C. Like he said it shows the peak levels near the green and yellow. So why make these LEDs exact sectrums that are so low on the peak absortion chart?
Maybe im missing something....
Ive also read on some peoples logs that running MH or HPS the whole way makes no difference in their grows. I realize that people just typed out half a science textbook worth of info but I didnt see anywhere explaining why 400nm and 660nm are so important if they are so low on the absortion chart.
That absorption chart posted likely came from a study of Algae which have the extra side-structure that processes green light. In fact almost every one of those charts is derived from an algae study, as algae is inexpensive to produce and easy to create large quantities with a bare minimum of energy, this makes it a perfect sample test plant, but sadly, the results are useful only for under-water lighting.
Note you rarely see green plants underwater as often as you do above/on the surface of water - most seaweeds and kelps are brownish/yellow color, not green. They absorb more green, reflect more yellow and just barely use any of the sparse red/blue that manages to filter through the water.
Start taking terrestrial plants that are exposed to full sunlight, and that chart will almost universally reverse itself peak-wise.
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Importance of 460nm red LEDs?
Whats up, Thepaan start some science threads. All your posts are really informative. I would rep you but I already did a while back. Seems like other people have. Every time you leave a post somewhere you get a new green dot.
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Importance of 460nm red LEDs?
Thanks for the info! That would make sense... unfortunately I saw the graphs in some online cannabis grower book thing... let me try to find the link. Bahhhh..
Anyways that would make sense. So maybe the guy who started the post saw the same graphs I did??
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Importance of 460nm red LEDs?
i haven't read through this whole thread yet, but i'll go ahead and give my $.02. chlorophyll a peaks both at 430nm AND just slightly less at 662nm. chlorophll b at 453nm and then slightly less at 652nm. LEDs usually only push two wavelengths, the two major ones for chlorophyll aborbtion, which push ATP and NADPH. white light runs the entire spectrum. there are other wavelengths that are needed by plants, such as beta carotene, phycoerythin and phycocyanin. plants need more than two wavelengths to complete all of their business....not that it can't be done by two, obviously.
part of the problem is that unscrupulous vendors jumped on the LED bandwagon and pushed inferior products with specific wavelengths (these emitters are cheaper than white) in a rush to get their products to market. while they do work, see Str8's log, but they aren't quite there yet. once the white emitters are more common and your plants can get the entire spectrum, LEDs will kick ass.
-shake
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Importance of 460nm red LEDs?
also, carotenoids ABSORB blue light. this light is used in photosynthesis, and carotenoids help protect chlorophyll from photodamage.
-shake
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Importance of 460nm red LEDs?
phycoerythin and phycocyanin are found in aquatic plants/algae and cyanobacteria mostly. There are not many terrestrial plants with such structures - Lichens are one of the rare examples I can think of that do have these, and even then they rarely use it directly as it's contained by the bacteria which thrive with the fungus, the bacteria use it more and the fungus benefits on the side. It's a very strange symbiotic relationship the lichen has with itself.
Also, phycocyanin theoretically cannot exist within the same structure if it has a carotenoid. This is why you won't find it in most terrestrial plants, as most terrestrial plants have carotenoids, which absorb aqua light around 510nm at the highest quantum response peak and 530 at the second-highest.
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Importance of 460nm red LEDs?
khyberkitsune, you rule too.
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Importance of 460nm red LEDs?
First, it's great to know I'm appreciated. I did a lot of reading to learn what I think I know and I'm glad some other people can put that to good use. But this is as much for me as for you because I learn as much as I share here.
Quote:
The hormone that triggers flowering in cannabis has to build up
I think it is OK to think about it this way but the truth is actually more complicated. For a short-day plant, like cannabis and rice, long-day conditions cause a hormone to be produced which delays flowering by supressing the hormone which causes it. When the long-day conditions expire the flowering hormone is no longer supressed and is free to express itself due to the diminished existence of the other hormone.
Reference
I don't have many references for this next bit as I usually do because I'm tired and it is late. I can find some later if anyone makes the request.
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Some nonsense about absorption spectra....
I think a lot of people have huge misconceptions about what the different pigments in plants are for. Lets say there are two classes of pigments: primary pigments and accessory pigments. For land plants, the two primary pigments are chlorophyll a and b. Everything else, which includes carotenoids, xanthophylls, phycocyanin etc., serves some other function in support of the primary pigments so that they can operate at peak efficiency. For example, carotenoids can act as antenna pigments to supply the photosystem cores extra energy in low-light conditions. At the same time, carotenoids can absorb excess energy from photosystem II when it outpaces photosystem I in unbalanced or high-light conditions. You may see other pigments in an absorption spectra for a number of reasons (including, as khyberkitsune said, because they are talking about algae) but what you need to know is that they are irrelevant. For a perfect light source there is no need to stimulate anything other than chlorophylls a and b unless (and this is the only caveat) we wish to evoke a specific response. This caveat has an example in cucumbers - no one has identified a pigment in the green range but cucumbers will simply not grow without some greenish light.
I'm going to assume that any spectra you have seen are wrong. Most of the ones floating around the intaerweb are absorption in vitro (in the glass). We want action in vivo (in the living). To illustrate the difference between absorption and action I want to talk about how we get a sunburn. The UV light from the sun is absorbed by our skin and kills the cells there then we have a burn. We know that it is UV light because if it were any other light then we would be getting sunburns inside from artificial light. Our skin absorbs more than just UV light because if we reflected all light then we would be perfectly white but most people are at least a little off-white and some of us are dark as night. So we have an absorption spectra for our skin which is much broader than the action spectra which causes sunburns.
For plants we are interested in only the action spectra - that is the spectrum of light for chlorophylls a and b which cause a plant to produce oxygen (or, as it is actually measured, to consume carbon dioxide). Action spectra always show the red peak (around 660 nm) higher than the blue peak (around 450 nm). Most spectra will show the blue peak almost as high as the red peak but others will show the red peak extremely higher than the blue peak. This difference comes from the different ways which light can be measured. From our basic physics class we learned that light is both a particle and a wave. Most scientific experiments measure light by counting the particles, or number of moles. Light also has energy. The longer wavelengths (660 nm, or red) have less energy than the shorter wavelengths (450 nm, or blue). Because of this, measuring in moles tends to favor more energetic light because for the same number of particles, blue light will have significantly more energy than red light - yet action spectra still show red wavlengths to have greater effect using this measurement. If we convert this action per photon to action per unit energy then most plants in blue light alone (450 nm) are performing photosynthesis at only ~60% the rate of those same plants in red light alone (660 nm).
Proper Action Spectra
This brings us back to why we are using LEDs. In order to stimulate a plant to grow most efficiently we must use deep red light (around 660-ish nm). This will allow us to use the least amount of energy in to get the maximum amount of growth out. Still, this is not quite enough. Certain other responses are only realized in other wavelengths of light. Fortunately, most of these for most plants happen to be in the blue with broad response ranges so that 10-20% of your red output added again as blue (around 450-ish nm) will be enough to take care of these. This has been found to be the minimum requirement for growing most plants and indeed applies to our favorite plant. LEDs fit the bill for specific wavelengths and given their other benefits seem the best choice for this application at the moment. But, that doesn't mean we can't minimize even further if another technology comes along (I'm still waiting for these induction lights to get more attention).
Anyway, I hope I have not bored anyone. For exactly how much light per unit area per day, look into Daily Light Integral (DLI).
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Importance of 460nm red LEDs?
Aloha ThePaan
Beautiful post brah.
Mahalo!:1baa:
Weezard
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Importance of 460nm red LEDs?
Thanks for an in-depth response. :thumbsup:
While 660nm is the most efficient, it appears that 620-630nm is like 85-90% as efficient at 1/2 to 1/3 the initial cost, so as a hobbyist I will probably stick to red instead of deep red unless I am missing something.
As to the red/blue ratio, that sounds great in theory, but I have yet to see any test results of different ratios. Do you know of any actual studies? I will try to find it, but as I mentioned elsewhere, on another cannabis website, the experts (theoreticians not just growers) claimed the best blue to red was like 1.2 to 1.5 to 1 in favor of blue.
Also, my seedlings and early veg seem to do better with more blue. Is that just a misconception/expectation error?
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Importance of 460nm red LEDs?
...but it seems that plants need a coupla spikes in the spectrae... for the red, around 630nm as well as 660nm, and the blue around 450nm as well as 470nm. Trying to remember where I heard it, but for flowering, apparently far red around 720nm is also needed. I'm sure that there are other bits of the spectrum that should be represented, hence most LED manuf's adding some type of white and / or 'amber' at around 610nm...
khyberkitsune and Weezard have mega-experience running and building these things, something I hope to be doing as well before too long :)
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Importance of 460nm red LEDs?
Quote:
Originally Posted by thepaan
I don't have many references for this next bit as I usually do because I'm tired and it is late. I can find some later if anyone makes the request.
For a perfect light source there is no need to stimulate anything other than chlorophylls a and b unless (and this is the only caveat) we wish to evoke a specific response. This caveat has an example in cucumbers - no one has identified a pigment in the green range but cucumbers will simply not grow without some greenish light.
Many of the comercially viable led lights out there are currently going threw an evolution. That evolution is moving from 2 band(460nm and 630nm or 660nm) to 4,5,6 and even more bands of light. This is in direct contrast to your statement. Lets use the 90watt ufo just as a discussion point (even thou we all know there quiet lacking in quality). The led ufo has 5 version I am aware of they are as follows:
First Generation: 8:1 or 7:2 for Red (630nm) & Blue (470nm)
Second Generation: 8:1 or 7:2 for Red (660nm) & Blue (470nm)
Third Generation: 7:1:1 for Red (660nm)70pcs & Blue (470nm) 10pcs& Warm White (2700K)10pcs
Fourth Generation: 7:1:1 for Red (660nm) 70pcs& Blue (470nm)10pcs & Orange (610nm)10pcs
Fifth Generation: Red (660nm)40pcs & Red (630nm) 20pcs& Blue (470nm)10pcs&orange(610)10pcs & Blue (440nm)5pcs & Violet (410nm)2pcs &Infrared (740nm)3pcs
As you can see they reached "your version" of the perfect light on the second generation. Why produce 3 more versions? if they got it right on the second try? I just can't believe that 2 wavelengths of light are really all the plant needs. I need more proof.
To that end I am planing on using white leds instead of blue leds. White leds as some of you know start life as a blue led and than add phosphorous(that flores and creates the other colors you see as white).
http://www.ecse.rpi.edu/Homepages/sc...%20P%20LED.jpg
Your thoughts? And your rebuttal in defense of 2 color light?
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Importance of 460nm red LEDs?
Now in understand that these china made lights are not the best on the market but they are far from the only example of lights being redesigned with more and more colors of light. Would you suggest that this is only for marketing reasons? Customers demand more colors so they put them there to sell lights?
(addition talk on the white led) This will give me a much broader spectrum of light. Now I will still have a large amount of 660nm light with a smaller portion of 630nm light. In addition to that I plan on a second stage for my light consisting of UVa and 605-620nm and some deep red. Most likely 30-40 worth total(4watt(uv)30watts(610nm)6-10watts(730ish) that can be switched on around flowering time.
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Importance of 460nm red LEDs?
"As you can see they reached "your version" of the perfect light on the second generation. Why produce 3 more versions? if they got it right on the second try?"
It's called marketing. Look at the men's razor marketing, and you will understand, most people making LED panels are following the exact same methodology. In reality, they have NO CLUE which wavelengths are the most efficient so they're just throwing out random mixes. I've seen 11-band panels, and I laugh. Quad-band with trace is all you need for terrestrial plants, and you need hex-band for aquatic plants.
"Customers demand more colors so they put them there to sell lights?"
No, the customers generally don't have a clue so they're led to believe "more is better" when the purpose of LED lighting is to target only what's needed for the most efficient growth and production.
Few makers of panels will EVER be straightforward with the customer, it's all about making the sale to them.
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Importance of 460nm red LEDs?
Quote:
Originally Posted by Greenmain
Now in understand that these china made lights are not the best on the market but they are far from the only example of lights being redesigned with more and more colors of light. Would you suggest that this is only for marketing reasons? Customers demand more colors so they put them there to sell lights?
(addition talk on the white led) This will give me a much broader spectrum of light. Now I will still have a large amount of 660nm light with a smaller portion of 630nm light. In addition to that I plan on a second stage for my light consisting of UVa and 605-620nm and some deep red. Most likely 30-40 worth total(4watt(uv)30watts(610nm)6-10watts(730ish) that can be switched on around flowering time.
Aloha Greenmain
2 points, for enthusiasm.:thumbsup:
Love to see folks trying things for themselves.
And about multi-band lights?
There seems no need with Cannabis. 2 colors are quite adequate.
Then why hawk 5 band, new, and improved, "super" lights?
It's a crowded market, and most sheeple can be fooled most of the time.
So, if ONE blade gives a clean shave, 5 blade razors must be 5 times mo' betta' Ya?:(:D
Same marketing folks that sell us "better" eggs.
(I don't wish to know where they stuff the "extra" vitamins an' minerals so da eggs come out mo' betta.):wtf:
Any road, the fact that 2 colors will grow great bud, is the main advantage of LED growing.
Not gotta pay for generating colors that the plant does not use as efficiently.
(We pay 5X what mainlanders do for electricity.:()
So, I no gonna "blind you wit science", no can.
I dunno too much science.
But I do know good buds.:jointsmile::stoned:
A little ~460nm. a bunch of 660nm. and healthy roots will grow buds like the sun. At least fo' me it does.:cool:
Can't guarantee your milage, of course, but I could not be happier with my well focussed dichroics.:thumbsup:
Please start a multiband thread and run a side by side with a multi and dichroic. I'll be watching with great interest.
Yer welcome, brah.
Them 2 pennies was burnin' a hole in me jeans anyway.;)
Aloha Y'all
Weezard
Add: Oops, Sorry Khyber. Posted before I read your last post making the same point.:stoned:
GMTA? Seems obvious, actually.:)
W.
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Importance of 460nm red LEDs?
GMTA, indeed :)
I'm actually doing a dichroic right now, Weezard, 12/12 from clone, 2:1 460:660, 30w. Link is in my sig. :)
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Importance of 460nm red LEDs?
Quote:
Originally Posted by khyberkitsune
Quad-band with trace is all you need for terrestrial plants, and you need hex-band for aquatic plants.
What's your currently preferred bands & ratios?
(I'm guessing from your current 2:1 experiment that you're still trying to find a better mix)
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Importance of 460nm red LEDs?
You can use 630nm rather than 660nm and it works no problem. Actually it works better because currently 630nm are available on more efficient chips than the 660s. Once we get our hands on the new high efficiency 660s we will experiment to find the most efficient ratio of 630s:660s.
As far as blue/red ratio, it very much affects stretch. So we use more blue during veg and also the first few weeks of flowering if you are trying to control a sativa dom. Red photons are more efficient at driving photosynthesis and they require significantly less power from the emitters per photon so it is beneficial to use as much red as you can get away with while still controlling stretch.
White light can help some strains ripen on time. White LEDs also have a convenient blue peak at 440-450nm. As an earlier poster mentioned, plants use photons from all the visible wavelengths for photosynthesis, including green. I expect that the small amount of these wavelengths contributed by the white LED is used very efficiently.
Plants may go through some period of adjustment when they are suddenly presented with a light of very different wavelengths. Therefore it may be useful to provide some white even during vegging. Since the white LED provides quite a nice peak of blue, it seems possible that a simple combination of white and red could be very effective. Another bonus would be a more even spread of wavelengths reaching each leaf. I will put that theory to the test as soon as I get the new 660s.
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Importance of 460nm red LEDs?
Quote:
Originally Posted by khyberkitsune
GMTA, indeed :)
I'm actually doing a dichroic right now, Weezard, 12/12 from clone, 2:1 460:660, 30w. Link is in my sig. :)
Aloha Khyber,
I'm subscribed to that thread and follow it closely.
Don't usually poke my nose in unless I have something to add or see a question that I actually KNOW the answer to.
You do jus' fine without unsolicited advice. :greenthumb:
Jus keep pokin'.:weedpoke:
Weeze
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Importance of 460nm red LEDs?
Aloha, Supe
That's why I haunt this board.
Got mo' fact, and less fnord
Got choke folks like you
Tryin' stuff I no can do.
No got the resources to humor my curiosity.:(
When I started growing, it was about affordable meds.
Now, it's gone from hungry lung to voracious mind.
I jus' have to know how it all works.
The meds are now what limits my quest.
Exceeding 3 Zs per person can turn patients into inmates round here.:wtf:
So, please keep :weedpoke: it and postin' it.
The wilder, the better.
There are no "failures" 'cause it's all information.:cool:
Mahalo nui fo' da data.
Weezard