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#1
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LED red and blue spectrum / cfl concept?
My question is this....if plants only absorb certain spectrums of light such as red and blue (blue for growth and red for bloom) why don't we just use these colors like with LEDs ?
My real question is if red and blue leds grow plants as well as what I have been reading, then why wouldn't red and blue cfls work. A top of the line led light is in the ball park of. $2500 13 watt. Colored. cfl is $5 From what I have been reading leds have less lumens than cfls, and the reason that they work so well is by targeting the red and blue spectrum of light in theory a red and blue CFL should work as well or better than leds right? Just curious. |
#2
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But it isn't actually colors that plants are absorbing, the plants are actually absorbing wavelengths of radiation (energy). The radiation/energy is what fuels the process of photosynthesis in plants. Each color of the rainbow is a different wavelength of energy, colors are just a perception by the human eye. That's why when you use a MH bulb that's in the blue spectrum, you don't actually see blue light, and it doesn't make everything look blue. The blue is the wavelength of energy given off by the bulb. The reason that you see the blues and reds so deeply in led's is because they focus on a narrow band of this spectrum. Each LED bulb can only give off one wavelength of energy, unlike a bulb that can give off thousands of wavelengths. There was a simple experiment done on a show called "Head rush" (my the people who do Myth busters). They took 3 light tubes (glow sticks), one of each primary color (red, green, and blue), attached them to the spokes of a bicycle wheel. Then posed the question what color will you see when they spin the wheel and the colors all blur together. The actual color you see is white. It's not a coincidence that's the color you see from a MH bulb. All the colors (wavelength of energy) are mixed together. It is no coincidence that is the color of light you see given of by the sun (that contains all the colors in the rainbow perceived by the human eye), and contains each and every wavelength of energy/radiation. Primary color - Wikipedia, the free encyclopedia (scroll down to "Biological basis") Quote:
As for using Blue and Red colored cfl bulbs. As I said in answer to the first question it isn't about the color visible to the human eye ,it's about the wavelength of radiation/energy given off from the bulb. So you cant just color the bulb blue or red and expect it to work. But CFL's do come in blue and red spectrum's, but just like MH bulbs they contain all the other wavelength's also, so they look white to the human eye. It has been a while but if I remember correctly the lower "K" numbers are the red spectrum (like 2700K), and the higher "K" like 6500K are the blue. Color and Mood : ENERGY STAR. Here they mention that the lower numbers are more yellow to the human eye, But remember that yellow is shade of red (made from red and green primary colors). So the lower the number, the more in the red spectrum the bulb is. When talking blue and red spectrum's, they are not saying that they don't contain other wavelengths (colors,) just that they focus more in one area than another. Quote:
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Last edited by GpsFrontier; 03-11-2011 at 01:05 AM. |
#3
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I just thought I'd drop by and say that there are some HUGE misconceptions behind LED.
Disclaimer: I do this professionally across the globe. Not just lighting, but full crop production systems that feed small countries. This includes producing certain grass crops using ZERO LIGHT at all for livestock fodder. The majority of plants do not react along certain wavelengths, and this can be verified with a simple CO2/O2 exchangemeasurements or via protein fluorescence observations. In fact, a majority of non-woody plants will have adverse reactions to exposure to green light, such as stunted growth or hindered reproduction. Trees, on the other hand, need green light to fulfill their full reproductive cycle properly. Most simple vegetative crops, such as lettuces, basils, spinach, celery, do well with a mix of three or four wavelengths of light from the red and blue range. Most fruiting crops have shown similar results, like tomatoes and peppers, and strawberries. You can get similar results by buying true primary-color T5HO bulbs, they do make pure 460nm and 630/660nm tubes but they get expensive, almost as expensive as LED, although the price of LED is dropping rapidly. Don't be fooled by more bands = better results. That's simply unfounded. I have a tri-band 50w panel, and the same panel using quad band + 4500K white. The tri-band had the EXACT SAME PERFORMANCE as the quad-band when it came to the test crops of everbearing strawberries and spinach. I've seen dichromatic panels perform similarly. The fact is, in the visible range, there are four wavelengths that are the most active. Trying to stimulate phycocyanin and phycoerythrin is pointless as that is primarily found in marine flora, not land flora. Just recently, a bacterium with a chlorophyll that could directly power photosynthesis with IR light (which we previously thought impossible) was discovered, but again, it's only in that bacterium - expect everyone to start unfoundedly saying "Stimulates Chlorophyll F!" with their sudden addition of IR to their panels. In fact there still isn't any real solid published Emerson Effect evidence. Ther's a bunch of conjecture and speculation, but not one single double-blind experiment conducted. Colored CFLs aren't going to work well. You're losing light output with a filter instead of converting all possible energy into the wavelength desired, and you can't even guaranteed that colored filter is allowing the desired wavelengths through. To address one statement made: "But the light intensity from even these High intensity LED's are no match whatsoever to the light intensity of MH and HPS." I'm bleaching plants from 18 inches away with a 300w panel using true 3w diodes. 2,000umol+ intensity (that's sunlight intensity) from a foot away, unlensed, smashing the outputs of a 400w CMH. If you want to go by the latest, Cree's about to drop a 200+ lux/w white diode out. Currently, we've got 150+ (but that doesn't matter, photon flux density in certain wavelengths matters.) Also, most LED panels are using research from the 90s, and specifications from the 90s. that 7:1:1 (or similar) ratio is just GARBAGE. It's fine for vegetative plants but for producing fruits and flowers you MUST have more blue for bulk mass production, as it's the higher-energy blue photons responsible for the majority of biomass production. All that red does nothing without the right balance of blue to match! http://i.imgur.com/j9GP1.jpg That's a pic of me in the UK research facility. Loose Leaf lettuce, 8 days from seed, testing various ranges/combos of reds and blues. Oh, for fun, I can also produce certain crop types without light at all (not talking white asparagus or endive, we're talking green grass for livestock.) http://i.imgur.com/woDrp.jpg Like that. |
#4
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I just ran across these today, and thought it might be of interest.
Ask Erik, LED grow lights Next Generation of LEDs: The Diodes Strike Back Last edited by GpsFrontier; 03-11-2011 at 03:28 PM. |
#5
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I would also love to see the creditable research results of the side by side comparisons of different plant types, that supports the claims of achieving the exact same results. I'm not talking about white LED light bulbs. I'm talking about individual wavelength LED bulbs, covering all the individual wavelengths (covering the full spectrum of natural light), where as a whole will put out a white light. As well as the side by side comparisons of LED's, and high density discharge lights, and for various plant types. Without that, and from creditable sources as I mentioned, there is no legitimate comparison, and just unfounded clams (likely from product manufactures). Quote:
By the time you add up all the wattage from all the LED light panels needed to grow a decent amount of plants using LED's (because of the extra panels you will need for good coverage), it's not nearly as cheep as the light manufactures say. They will say a particular LED panel is equal to say a 400 watt MH bulb, but that wont be true when you go to use it as a replacement for it, and you will need more lighting to make up the difference (weather it be LED or otherwise). At least if you don't want to sacrifice growth results, don't expect that to be true. That's just a sales tactic to sell you a LED light based on cost (electricity) savings. But they wouldn't sell nearly as many if they told you you needed the much more expensive models for that kind of coverage. And again that's just comparing coverage (intensity), and not plant growth and/or health. A watt is a watt, and it cost the same amount of money power a watt of LED's as it does to power a watt of HID. If you add it all up, there will probably be some cost savings in electricity used with LED's, even when needing multiple LED's, though that's strictly talking cost saving in total amount of electricity used here, and nothing else. That's not comparing plant growth between HID and LED's, and/or the amount of wattage needed from the LED's in order to have acceptable growth results, much less in comparing it to the growth of HID lighting. But regardless of what the manufactures say, you will need many multiple expensive LED panels to do the same job as MH and HPS lights, and/or very expensive large models. Now your grow just got way more expensive as a result. And who wants to wait ten years for the difference in electrical cost to finally make up for, and start paying off after the much higher initial cost. P.S. Don't get me wrong, I think LED's have a place in hydroponics, and perhaps may even someday be the preferred lighting choice. But they still have a long way to go before they can match MH and HPS, regardless of what the LED manufactures try to sell you on. I'm also hoping to see the costs come down to where they would be cost effective to buy, even if only as supplemental lighting. But I'm not going to shell out $300-$400 for a light to grow a small amount of lettuce based on less electricity, when I can build a florescent lighting system to do the same job (if not better) for about $50. |
#6
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"I would like to see the research that supports the statement that plants don't respond to wavelengths of green light."
Practically every cannabis forum out there can tell you this, along with multiple non-woody bonsai growers (myself being one.) I didn't say ALL plants, but a fair majority do not respond in any favorable fashion to green light. This applies to primarily terrestrial plants. Marine flora have far different response ranges and also additional helper chloroplasts. "That's basically saying that 1/3 of the suns energy (light) is useless to plants." Plants only use about 5% of any energy they're irradiated with at any given time. The conversion from photons to energy is highly inefficient to boot. The truth is a HUGE majority of light is practically useless, as the plant simply can't use it because it's already fully charged - think of chlorophyll as capacitors/batteries with built-in converters. In any energy system, you take in too much energy, you risk burning out. Chlorophyll does this constantly in natural sunlight. It degrades due to such high energy irradiation. That which does not get used (primarily green) is either reflected back to us or just generates heat off the surface of the plant tissues, the latter effect being goverend by thermodynamics. "Again here I would love to see the creditable research that supports the statement that less wavelengths of light is better." Read any number of research that uses a control light source and then supplements with monochromatic sources. I believe you'll find the ones performed on wheat, barley grass, and wheatgrass to be quite informative due to easy repetition of the experiments and easy creation of double-blind testing across huge swaths of crops. In fact, I simply grow fodder grass using practically zero light (quantum meter effectively reads zero,) and it's as healthy as typical grown fodder grasses with about half of the root hormone content that upsets multiple ruminants. In multiple crops, less is far superior, depending upon purpose. You're limiting yourself to inside the box thinking. "I would also love to see the creditable research results of the side by side comparisons of different plant types, that supports the claims of achieving the exact same results. I'm not talking about white LED light bulbs. I'm talking about individual wavelength LED bulbs, covering all the individual wavelengths (covering the full spectrum of natural light), where as a whole will put out a white light." Thousands upon thousands on Springerlink, Wiley Acience Archive, and independent research done by everyone from home gardeners to University professors like John Lydon, all acros the web. You should be quite able to find them, just start by picking your crop. I'd recommend Dutch sources as they tend to be a bit more detailed, especially concerning yields in terms of yield per kilowatt-hour and nutritional content, much moreso than most US-based scientists. They also have better hydroponics systems overall. "Sounds like this statment is right out of the pages of a product manufactures web-page. Where is the creditable research that supports this. I know that LED technology is improving, and even slowly coming down in price. But I want to see the creditable research that shows/supports the same growth rates, plant structure, overall foliage and fruiting (in both quantity and quality) is the same or better than with MH and HPS. As well as for various plants, including large plants like indeterminate varieties of peppers, tomato's, and/or large vine plants like melons, peas, cucumbers, squash etc. is the same or better using LED's than MH and HPS." I've done it across various other forums, I'll be more than happy to do it here. In fact, doing it across forums is what got me my research director position in the first place. So sit back, enjoy the show. Wait for me to get my seeds. BTW, remember that lettuce picture in my post above? That was eight days. The crop typically takes seven weeks under natural sunlight in an NFT system. http://i.imgur.com/MCRg8.jpg Done in twenty-eight days. We're waiting for nutritional analysis to be able to make final judgments against sunlit greenhouse lettuce of the same seed stock batch, but the weight is perfect for market and the color is excellent. Sorry I can't give you day-by-day from our research facilities but that's absolutely not allowed by my NDA. Nothing in my NDA prevents me from doing the same thing at home and showing it off, so here I am. |
#7
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I like seeing pictures, but pictures are not what I consider creditable documentation and/or a complete study, nor does that show comparisons. For instance you mention comparing days of artificial light and natural sunlight, but there are a whole lot of variables that will affect the results. That's what a creditable study would be looking at and comparing in their experiments. That's also what makes the difference between a creditable study, and a home gardeners version of a study. No offense, but I don't just look at a picture that someone posts in a forum and consider it creditable information. Without the particulars of a controlled and well documented experiment, and including a control of each variable to base the results against, it's simply just a picture of a plant. And thus nothing to suggest the creditable information I have seen is incorrect. But it's always nice to see what other people are doing, and how they are doing it. |
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