also, carotenoids ABSORB blue light. this light is used in photosynthesis, and carotenoids help protect chlorophyll from photodamage.
-shake
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also, carotenoids ABSORB blue light. this light is used in photosynthesis, and carotenoids help protect chlorophyll from photodamage.
-shake
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.
khyberkitsune, you rule too.
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.
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.Quote:
The hormone that triggers flowering in cannabis has to build up
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.
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.Quote:
Some nonsense about absorption spectra....
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).
Aloha ThePaan
Beautiful post brah.
Mahalo!:1baa:
Weezard
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?
...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 :)
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:Quote:
Originally Posted by thepaan
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?
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.
"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.