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  1. #1
    Australian Medical Marijuana Educator Smokin Moose's Avatar

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    Default Effect of Electrical Lighting Power and Irradiance on Indoor-Grown Cannabis Potency

    J Forensic Sci. 2011 Dec 28. doi: 10.1111/j.1556-4029.2011.02024.x. [Epub ahead of print]

    The Effect of Electrical Lighting Power and Irradiance on Indoor-Grown Cannabis Potency and Yield.

    Potter DJ, Duncombe P.

    Source

    GW Pharmaceuticals Ltd., Porton Down Science Park, Salisbury, Wiltshire, SP4 0JQ, U.K.

    Abstract

      The floral development and potencies [Δ(9) -tetrahydrocannabinol (THC) contents] of cannabis plants were compared when grown indoors under high-pressure sodium lamps consuming electrical power at three densities (270, 400, and 600 W/m(2) ). After a 3-week vegetative phase, plants were grown for 8 weeks, with lamps maintaining an artificial day length of 12 h. Foliar and floral yields were measured. Gas chromatography was used to measure the content of the psychoactive cannabinoid THC. Mean yields per unit of electrical power in each lighting regime ranged from 0.9 to 1.6 g/W, the highest being achieved in the lowest irradiance regime. The individual potencies of the separated leaf and flower materials were not affected by increasing irradiance. However, there was a corresponding increase in the overall potency of the aerial plant tissue. This was because of the plants in brighter conditions producing a higher proportion of floral material.

    © 2011 American Academy of Forensic Sciences.

    PMID:
    22211717
    [PubMed - as supplied by publisher]

    Source: The Effect of Electrical Lighting Power and I... [J Forensic Sci. 2011] - PubMed - NCBI
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  2. #2
    Seedling

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    It's funny that they went so low on their wattage that it skewed their g/w to the highest yield per watt being attributed to the least power.

    But it sounds like they discovered the bud is more favorable than the leaf, so maybe that treebark + roots that the government pre mulches is due for an improvement.

    They need to leave these experiments up to the botanists that know what they're doing and unlike the pharmaceutical companies dont' adhere to flawed methods and irrelevant conclusions, or they risk polluting the existing body of knowledge which is already many decades beyond this.
    Last edited by chillzpls; 01-11-2012 at 02:50 PM.

  3. #3
    Vegetative Member paddyk's Avatar

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    I don't believe a fucking word from that industry. G.W. is the worst of the lot imo.
    Legalize it already

  4. #4
    Flowering Member Guy_In_Pain's Avatar

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    Quote Originally Posted by paddyk View Post
    I don't believe a fucking word from that industry. G.W. is the worst of the lot imo.
    Legalize it already
    100% agree GW is evil.
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  5. #5
    Shadbot 4.20 Shadimar's Avatar

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    I'd like to mention too, that proper LEDs will cause a profuse exaggeration of resin glands. They appear to grow long and intertwine like strands of woven plastic. Altering HID intensity will not reproduce this as it's possibly due to something that will eventually be regarded as a defect in early LEDs. The effect on potency on the other hand.. well, bigger glands can hold more resin.

    Anyway, just trying to toss my own personal monkeywrench into their results for moral reasons

    It would appear, on careful reading, that they are stating that low light grows more leaf. I'd imagine this is where the extra yield per watt comes from.

    Aside from that though, they found that more light means more flowers and that lower light levels can still grow decent bud. Two things they could have discovered for free using any forum search engine.

    Maybe I should start filing for patents on my posts
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  6. #6
    Seedling

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    Yeh, except low light doesn't produce. It just skewed their g/w by being sooo low in light, that having any bud produced at all led to their highest g/w ratio. Doesn't mean they got more than a gram.

    I would say their conclusion:

    " This was because of the plants in brighter conditions producing a higher proportion of floral material."

    Is very typical of "medical science", because it's erroneous and irrelevant conclusion, untested and unproven, aka, pulled from ass. At best it would serve as another hypothesis for further experimentation... and further research money? It's like they're saying well, you've got more to smoke, so you'll get higher.... so we'll call that more potent. Doesn't work that way at all.

    But we already know the flower tops are the most potent... most flowering hormons concentration, as well as improved light quality. Light quality, what they ignored completely.

    "Altering HID intensity will not reproduce this as it's possibly due to something that will eventually be regarded as a defect in early LEDs. The effect on potency on the other hand.. well, bigger glands can hold more resin"

    Altering intensity could have "some" small effect because the light spectral distribution is obviously not going to be 1:1 between different bulbs, even if they're of the same type. At some point that might become significant, especially if they're using something like an HPS, (did they say?), which for certain power levels could be completely starved of spectral distribution where it matters, and maybe the next power level has just a little bit.

    There's really no isolation of variables here and with so much fucking complex interractions going on, they're just swinging in the dark and drawing fallacious conclusions.

    Seriously you should look up some REAL botanist experiments on plant/light reactions and you'll see this bullshit is no more advanced than your typical "will the beans grow in the dark" high school experiment. It's that laughable.

    More trichomes makes it more potent than having none, and more intense blue light in the spectral distribution produces more trichomes, just like the uv-b = potency discussion. But it also produces different trichomes as well, since blue light controls the production of terpenes and flavenoids.

    That's why a regular HPS grows some boring ass weed... good yield but not connoisseur, no complexity, not particularly potent. That's why we like a full spectrum any way that we can get it. "dual spectrum" HID lights, "corrected spectrum" HPS light (often they're not), using a mix of colour temps for fluorescent, LED where we can make the spectrum what we want if we know what's up.. and cheap chinese production lights are as informed as GW on that issue. It's also why I'm using CMH lights.

    Also, giving the plants the right kind of light to produce that kind of quality tends to be less efficient or at greatly increased initial expense and I don't see that changing for awhile. So in terms of commercial production, you're always going to get shit, but maybe a lot of it. They are profit driven, not quality driven, and not purpose driven. So are they at all qualified to grow your medicine for you? You need look no further than this fucking joke of a paper to answer that, and even if they could, the profit incentive will get in the way, as would being protected from free market competition.

    'scuse the crappyness of my post I really need to find some coffee to chew on
    Last edited by chillzpls; 01-27-2012 at 08:19 AM.

  7. #7
    Flowering Member MidnightToker's Avatar

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