Building LED lights from facts, no theories

You can find details of photosynthetic perfomance of cannabis at varying irradiance, temperature and CO2 levels in the study "Photosynthetic response of Cannabis sativa L. to variations in photosynthetic photon flux densities, temperature and CO2 conditions", by Suman Chandra, Hemant Lata, Ikhlas A. Khan and Mahmoud A. Elsohly. Its a very complete study, again with the limitation of studying responses on the short term, and not on after long term acclimatation.

The study reveals that cannabis can handle very efficiently up to 500-600 uE/m2 at ambient CO2, with optimal day temperature near 30ºC (but strongly dropping over it!), and the best range being 25-30ºC. There is no clear photoinhibition point, with photosynthesis still increasing (although little) at 1500 uE/m2 (not at low temps), so that point at optimal temps and ambient CO2 is over that figure

You must take into account than that 7% of margin error refers to white lights sources, broad band ones with limits on the saturation of a given waveband.

On the LED growing research, we are working with relative narrow wavebands strongly saturated, in the look for the highest photosynthesis but accomplishing the most positive sinergies, trying to achieve way highest photosynthetic efficacies than a white light can do.

We are actually getting very nice enhancements on the spectral efficacy (yield/mol of photons PAR) using this approach when refered to white light sources, of near 200%. So its possible to go way ahead. Its not exactly photosynthetic response, but how carbon efficiently fixation is used, that is related to more factors. But the difference is so huge that sure that a significant part is achieved by enhanced photosynthetic response.

A group of grower are performing experiments with standarized measurements in order to find the optimal spectrums (different according to irradiance used?) for cannabis. If you want to join us, you are welcome. Stadistical analysis of experiments may strongly fasten the research, so sharing our results benefits all.

I was thinking about and experiment for photosynthetic spectral analysis for a given plant. Since some of the wavelengths are codependent, you could not just examine them one by one. You would need to have all of them on at once, and reduce the amount of just one until the O2 output of the plant decreased. Then you would know you'd gone below the max. If you had the right equipment, this would be extremely simple. Though, you'd need an O2 meter to quantify photosynthesis, and you'd need exact amounts of light for every wavelength running simultaneously.

Do you have 200 lasers we could calibrate? :D



Maybe trial and error would be a better way to go...

Hmmmm...but its a very good idea, at the end. Equipment that measures instant O2 flux from a leave is not so expensive....

It would be needed to use a dark period of 30min between each light quality, but using large steps, like 20% for each waveband, we may identify the bext mixes in a rough way and then work in fine tuning it.

Using the same irradiances of differnt SPD needs some work, but its doable. A single testing array with 1 or 2 LEDs of each color and current adjustement for each color is all we need.

I think its a very good idea. At least in order to identify the best photosynthetic respones. Long term (whole grow under a given quality and irradiance) would be still needed to study which matter at the end, the carbon fixation, morphology traits, to understand the final relation between light and yield. But it would be experimenting in far narrower settings.

So, what's that gizmo that instantly measures O2 flux called? :wtf:

CID Bio-Science, Inc.: Portable Photosynthesis, Plant Canopy, Root and Leaf Measurement and Analysis: CI-340

Qubit Systems: Photosynthesis and Transpiration

:wtf: Only $4,000... Maybe I can barrow one. I'll see if my university has one. Might have to test tomatoes instead. that could be as close as I can get. Think it's similar? Would tomato results be remotely useful?

I wish I understood this.......:( I wanna build my own LED so badly:D

Let me start off by saying... I appreciate the interesting reading and feel free to remove or bash this post at will, it's probably deserving.

By comparison, this question will be elementary at best, maybe even ridiculous, but since I know nothing about LED's I'm just gonna throw this out there.

Has anyone ever heard of, or is it even possible to use a large flat panel t.v. to grow marijuana? With the new LED and/or Laser t.v.'s I was just curious as to whether or not it's even possible. Is there similar technology involved that may potentially crossover?

I realize the cost, both initially and while in operation, would be impractical, among any number of other things, I just thought it would be interesting to try. I assume the major problem would be, that I'm confusing color with spectrum or lumens.? Hell, I don't know, you're the smart ones.

Anyone got $10,000 they can loan me for a test.

Peace

Quote:

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Originally Posted by mrmarbles

Let me start off by saying... I appreciate the interesting reading and feel free to remove or bash this post at will, it's probably deserving.

By comparison, this question will be elementary at best, maybe even ridiculous, but since I know nothing about LED's I'm just gonna throw this out there.

Has anyone ever heard of, or is it even possible to use a large flat panel t.v. to grow marijuana? With the new LED and/or Laser t.v.'s I was just curious as to whether or not it's even possible. Is there similar technology involved that may potentially crossover?

I realize the cost, both initially and while in operation, would be impractical, among any number of other things, I just thought it would be interesting to try. I assume the major problem would be, that I'm confusing color with spectrum or lumens.? Hell, I don't know, you're the smart ones.

Anyone got $10,000 they can loan me for a test.

Peace

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There are LEDs designed to be viewed, and LEDs designed to give light.

Of course those designed to be viewed gives light too, but its way less than required for plant's growing. Plants requires a lot of light, and the only practical way to give it with LEDs is using high power ones.

Think that HID growers uses in 1 sq meter (11 sq ft) what streetlights uses for 50X times that area. That is a lot of light.

I was walking next to a po-po car the other day and was thinking that its lights would be awesome to grow with. The new LED ones are the 7mm(i think, they are def big) and they are bright as balls, I bet you could get some sort of harvst from using popo lights. Just another thought triggered by the post above.