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Trichomes, THC and UVB light.....

Discussion in 'Advanced Marijuana Cultivation' started by tahoe58, Nov 26, 2007.


    tahoe58 Well-Known Member

    I have been encouraged to start another thread with the purpose of looking beyond the “purpose” of the trichome and under what condition and how the trichome evolves during the maturation process.

    The premise I would like to put forward is to look more in depth into the role the UV light plays. There is a significant body of evidence that has shown that the potency of your babies will be improved with UV light – a trade off with lumens, but an improvement of the concentration of THC – why? Because it is the UV light that breaks down the precursors in the trichomes to THC. This is a little out there so to speak because we have all be told that the HPS is the flowering light…when in fact….it produces NO favourable UV light. So while a MH bulb is lower on the lumens scale, it has an abundance of favourable UV light.

    This is a post that TheBigBad made on 05-21-07
    “ive read a bunch on how plants grown outside is stronger than the same strain grown indoors. and how UV rays are what cause this. UVB are mostly responsible as they are the stronger of the UVB rays. UVB is what you get sunburns/tans from. the plant makes resin to fight off the UV rays, so outside makes for stronger pot.
    assumeing all that is right, if you added a UVB light source to a grow room where it would just come on for alil while each day of the flowering phase you might be able to get stronger buds indoors. and if that did work whos to say by makeing the light stay on alil longer each day than the day before the plant wouldnt just go crazy and turn into a huge pile of THC??? lol
    anywhoo, what do ya’ll think? worth a shot or not?”

    That thread stalled and was last posted on in August.

    ……possibly the most authoritative piece that I have found so far is Pate, D.W., 1994. Chemical ecology of Cannabis. Journal of the International Hemp Association 2: 29, 32-37. This paper is widely referenced in future documentation…so just as I do in my professional work….I like to stick with what the ganja research fraternity takes as somewhat of an authoritative piece.

    As a little of an aside, this may be valuable in the discussion relating to the “purpose” of resin – in regards to this, it references anti-dessication (i.e., THC concentration higher in xeric conditions), antimicrobial, antifungal, antifeedant *i.e., chemical and physical deterrent) and UV-B pigmentation roles. But that’s another topic. I want to look at what factors might best guide us in further maximizing our resin production and thereby potentially, our potency.

    In this regard, I take from this paper (and the unavoidable tangential research….), the following:

    • cannabinoids are present in glands throughout the plant in two forms…stalked and not stalked;
    • the density of glands increases as you move up the plant (uncertain whether or not this is a function of maturity or structural difference – more study needed)
    • in one study, the THC generally increased as locations became less favorable for plant growth, suggesting increased plant stress enhanced delta-9-THC production
    • cannabinoids also may function in the role of UVB protection (another biological stress-inducer), which may be functionally analogous to human skin pigmentation (again more study needed to understand and resolve current information).
    • colour rendering Index (CRI) with a maximum value of 100 (i.e., that of outdoor daylight) – only comparable with lights on the same temperature (i.e., 2700K, or 6500K, etc.). For example it is un-instructive to compare identical wattage CRI (70 vs. 20) of MH (4500K) vs. HPS (2700K)
    • recent developments in LPS (Low pressure sodium) might provide some better solutions
    • Pate (1983) and Lydon et al (1987) both demonstrated that under conditions of high UV-B exposure, drug-type Cannabis produces significantly greater quantities of THC.
    The following are a couple of excerpts from a post entitled UV and it’s effects (BC Growers Association)….from 1999….. http://www.geocities.com/SunsetStrip/amphitheatre/5796/uv.htm

    “Growers use two or more 20 minute UV light treatments during the day cycle

    “Metal halide produce the best potent weed less lumens for the money but better smoke. After years of testing with some friends who did want to keep THEIR recipe (more hps) i foung there weed to be harsh, full of CBD, make me eat and sleep, only good to sell to someone else taht you dislike. The blue spectrum will give you a final product that have everything included :taste without curing, potency and yield, To be effective a ratio of 2 MH for 1 hps at the most.(hps) Hps alone can produce a cash crop but not a connaisseur crop.
    Et Voila..

    Q1. if UV in ionisers is used for odour control, will high UV light conditions (high altitudes) also influence odour – which has been postulated to have important functionality in the life cycle of cannabis?

    Q2. should/could we maybe consider the introduction of a “highly limited” level of exposure to UVB to enhance resin production while within the limited of phytological degradation?

    Q3. do we need to take a closer look at the true comparison of the growth potential/potency of using HPS vs. MH vs. MV lights? Have we been incurring a limitation to potency by using HPS lighting for flowering?
    PurpleHazeJohnny and Grimmister like this.

    Harkin Well-Known Member

    Wow amazing read mate, I've heard that ratio of 2MH for 1HPS is ideal, sure I've heard that on here before from someone but can't remember who..

    tahoe58 Well-Known Member

    thanks...man...I did a search for references to UVB and I continue my search....I am so stoked on what we can find out.....even if I am following a trail of balderdash....! :blsmoke::blsmoke:

    fdd2blk Well-Known Member

    why not just plug in the MH? question answered. i don't have one or i would.

    Harkin Well-Known Member

    Can't wait to see what you find. Im too lazy at the moment to do that much research, I know when I'm smoking my first bud I will probably spend hours reading up on the matter. I'm sorry for this stupid question but here goes: I was thinking of getting a 250w Envirolite CFL, in the blue spectrum. So would this be considered UVB light or is that something different? I think a mixture of HPS and Blue Spectrum CFL should produce some potent bud, Hopefully with my next grow(same white widow seeds) I can tell the difference. Sorry if it's off topic:peace:

    tahoe58 Well-Known Member


    skunkushybrid New Member

    Great post... probably take me a couple of reads to digest properly.

    Loved the marijuana man vid on you tube. It'd be great to have him on site now. Interesting though, in his vid he placed cbd before thc...

    Also, he mentions something else... he said that 24/0 will not keep a plant out of flower. Great video. He got any more?

    skunkushybrid New Member

    You should already know the answer. Are your outdoor plants more potent, or the indoor ones?

    tahoe58 Well-Known Member

    thanks man.....POT-TV Network .... :blsmoke:

    Harkin Well-Known Member

    Nevermind Tahoe, after watching MM I know it's a lizard light, or a light you can get from a pet store that has UVB. Got to try this abd see what happens:hump:

    tahoe58 Well-Known Member

    I have been delving deeper into this...and it does not seem to be quite that clear cut....at least from the "anecdotal evidence" presented by fellow growers...? :blsmoke:

    skunkushybrid New Member

    Also there are UV A, and UV C... how come these are ignored?

    tahoe58 Well-Known Member

    I believe it is because it is a very narrow range of UV light that has trhe influence over the conversion process. (i.e., 280-315 nm)

    skunkushybrid New Member

    Then what happens to the A and C? We know red (far) light is bounced off, and green is reflected too. So this means all other light would be absorbed into the trich' at the same time... likewise magnified.

    Could the chemicals, like MM said, be created to divert the different spectrums? Hence the varying cannabinoids in the first place?

    Also the chemical responsible for smell, he makes no mention of that... Ed Rosenthal, put the chemical as THCV... the plants with high levels of this chemical are usually the most potent strains. Could it in fact be the THCV that is created by by one of the UV ranges? THC created by another, and CBD created by the other one?

    Hence the reason for the two sets of cells in the trich'.

    Also, why would cbd be derived from THC? Maybe THC is derived from THCV, and CBD is derived from CBN. The reason for the two sets of cells, could be to process light from both extremes of the spectrum. The cell responsible for smell (i forget the names now, and scrolling down doesn't reveal enough, sorry) reacts to blue, and the part responsible for cbn reacts to red?

    Hope that makes sense.

    USD Active Member

    Like you have mentioned, the ultraviolet region of the magnetic spectrum is divided into three different regions, UVA, UVB, and UVC. These three sub-divisions are rather arbitrary, however, as it seems that most disciplines originally defined them differently and have their own definition of what wavelengths fit in which division. Environmental photobiologists (who I tend to trust because they know plants) tend to define the wavelength regions as: UVA= 400-320nm, UVB= 320-290nm and UVC= 290-200nm. 290nm was chosen as the distinction between UVB and UVC because UVR in the shorter wavelengths are unlikely to be present on Earth's surface, other than at high altitudes . The division between UVA and UVB does seem to be rather arbitrary however, as I have yet to read a definitive explanation. More recently what does seem to becoming clear now, however, is that electromagnetic radiation occurring at wavelengths shorter than 320nm are thought to be generally more active photobiologically than longer wavelength UVR.
    montanamike1 likes this.

    tahoe58 Well-Known Member

    thanks man....for adding this....a good deal of insight to the technical specific here....preciate you pipining in! :blsmoke:

    stonedroach Active Member

    ReptileUV.com is soon to be releasing a metal halide uvb bulb with loads of uvb

    bKonz Active Member

    I found this link in a quick search. There is some good info in there on what lights produce specific spectrums of UV light.

    Reptile Lighting

    tastyaces Well-Known Member

    ive also been looking into this. But where would you put uv light just seems small to cover 10 plants. and where would u put it??? but great thread been lookin for some info and this pretty much says it all...

    tahoe58 Well-Known Member

    thanks tasty aces......the penetration of UVB should be pretty good considering the wavelength...but that is a good question...something more to look into for sure....in my case....I will never have more than 5-6 plants...so its not as much of an issue

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