References: C.R.B. Joyce and S.H. Curry. 1970. The Botany and Chemistry of Cannabis. J. and A. Churchill: London. R.C. Clarke. 1981. Marijuana Botany. And/Or Press: Berkeley. E. Rosenthal. 2002. “Light Disagreement†Cannabis Culture (Nov.) http://www.cannabisculture.com/articles/2696.html E. Rosenthal. 2003. “Metal Halide for Flowering?†Cannabis Culture (Feb.) http://www.cannabisculture.com/articles/2833.html R.A. Nelson. 2000. Hemp Husbandry. Rex Research Archives: Jean (NV). D.W. Pate. 1979. The Phytochemical Ecology of Cannabis. Dissertation for Ph.D. at University of Missouri-St.Louis. J. Lydon. 1985. The Effects of Ultraviolet-B Radiation on the Growth, Physiology and Cannabinoid Production of Cannabis sativa L. Dissertation for Ph.D. at University of Maryland-College Park.
Sam the Skunkman, the original, was actually a constant poster in that thread and we both discussed it together for quite some length. He actually had a copy of an article about this topic that I could not even get from my library through inter-library-loan. It was another article done by Lydon in the journal Phytochemistry and Photobiology or something close to that, and he sent me a copy of it from Amsterdam after I had posted this, so none of the data from it are taken into account for the paper above. It was another very interseting read. What the discussion generally came down to is that whereas UV-B may not directly effect THC production, it does so indirectly. It possibly increased phenol production, which then combines with terpenes to create a terpephenol, which is then used to make carboxylic acid, which in turn is used to create THC. Why it does so is a completely different matter, and it gets into a very scientific discussion of the metabolic pathway to THC synthesis, the UV-B absorbsant properties of different cannabinoids along that pathway, and exactly what creates what which creates what. I haven't got a chance to read through this whole thread yet, and I'll read through it all later today when I get a chance, but everything is coming back to me after many years of dormancy, haha. Hope I can contribute to the discussion =D
Bobby Digital, thanks for that information, but please realize that we have already gone through those references (at least I have). Except for the Lydon study, those are mostly speculative and if you notice, they pepper their work with words like "possibly," "may have," "could be," etc. The biologists and many growers (including Ed Rosenthal) admit there has not been enough research to really determine what's going on. Bouquet and others have also noticed the increase of THC with arid climates. Others have noted that more light, in general, produces more yield and/or potency. UVB is a high energy electromagnetic wave and there hasn't been enough work done to determine if it is really the frequency or simply the added light that is giving the plants more energy. It is very difficult to determine what's going on because it requires controlled studies to determine what other causal agent might be causing (or not causing) an effect upon THC production. Dry climates and extra sun power along with UVB all correlate with each other. Research facilities have only so much money and time available to them so it always limits the number of controls that they use. This is why it is so important to do more than one study that covers the other controls. You can't just choose and pick references that sound encouraging and then say "it's the single most important environmental factor". That's simply an opinion. One could also pick and choose references about arid conditions, higher light levels etc. And say *they* are the most important factors. Those are opinions too. Of course genetics plays the most obvious choice for the most important factor simply because you can't get THC if you don't have the genes. And as we know, you don't need UVB to grow great cannabis. I look forward to your input.
olivetol. thats directly on point. just because youre unaware of it doesnt make it an imagined connection. it is an aromatic, a terpenophenolic to be exact. UV light is known to increase the production of terpenes. Terpenes are required for olivetol formation. When a precursor chemical is found in abundance, then the chemical processes that ensue are allowed to reach their potential, or at the least not be inhibited by a lack of precursor chemicals. Id rather go ahead and give it an abundance. ------ Why does cannabis grown indoors under HPS produce THC at all if it requires UV light? The answer probably lies in genetics. The presence of UV light has been ongoing for generations, and as such cannabis is coded to automatically protect itself. The process will degrade through generations in the absence of UV light. People who order a White Widow seed and keep it as a mother to clone from for years probably wont notice this genetic degradation. However, if they arent supplementing their light, they may not be fully realizing their genetic potential either. If you are breeding your plants however, it seems ridiculous to assume that plants void of UV light will remain as potent through future generations. ---- No, I dont claim to know more than biologists, do you? There are plenty who have concluded that UV light is responsible for cannabinoid production. Yet, you assume they didnt assume that those areas may have also had other things in common, such as low humidity and increased light amongst the total spectrum. Isnt it possible that the reason they include the 'possiblies' and 'maybes' is because they weren't able to set the proper parameters to rule out other variants, or it was a correlation noticed as a secondary result from a controlled experiement, and as such is less conclusive? Fact is, multiple studies, with degrees stacked everywhere, and loads of resources unavailable to either of us, have concluded that UV light plays a critical role, yet you assume that they didnt ask the questions obvious to a high schooler. Give their years of experience in the practice of science some credit. While studies may not have had the scope to fully realize the biosynthesis, they can certainly result on the end product.
also, the reason i dont want to discuss dessication is not because I am trying to avoid the subject, nor because I am denying the connection. If you read carefully, I said that it was a correlation I was previously unaware of, and may in fact have some merit. but do me a favor. Look at the top of your page. See the thread title? what does it say? if it said "how do I increase THC production?" then we could be talking about all sorts of things, including UV light AND dessication. This thread is meant to discuss whether or not UVB light plays a role in cannabis. If you want to discuss dessication, start a thread about it. I promise Ill talk over there too, although I think we may be on similar sides of the fence. However, unless you can establish that the sole factor in THC production is dessication, and as such levels of UVB light are irrelevant, then its not on-topic, and is just lengthening the discussion. Like I said, its worthy of mention, just not here.
Oh but forming an idea without knowing is, indeed, a form of imagination. It is called a hypothesis. That's quite a stretch of imagination to say that just because UV light affects one chemical that it also affects another. I remain unconvinced. Oh, but you ARE making assertions that other biologists are not. If you read carefully, the scientists are not making conclusions, they are making either a hypothesis or a guess. They do this to form a direction for further research. The only people I see making conclusions are those who are not scientists, usually laymen and growers, like yourself, who's aim is to make more THC in their plants. There is already an inherent bias built in their minds. There really isn't that much research on THC. But to cull their work and isolate specific sentences that only agree with your "conclusion" and then call this "lots of evidence," is hardly convincing.
Very good. Perhaps we are making some progress. Now that you are aware of it, shouldn't you now take into consideration that it might be dessication (or another correlative agent) that *might* be causing THC production? The aim should be to do controlled studies to determine which (if any) of these correlative agents have a causal relationship to THC. Doesn't it make sense to find out these things before forming conclusions? See what I mean?
well, the theory that dessication may also contribute at some stage doesnt mean that UVB light is not a factor in THC production. I remain convinced. for example, light isnt the only component of photosynthesis. there is most likely more than one stimulus for inducing capitate stalked glandular production in cannabis, and probably more to enhance the production of THC. Im not claiming that UV light is the *only* factor, and as such, admitting that dessication could also have a role doesnt change my stance.
what a great post!!!! both proteus and amoril obviously know their stuff.... thumbs up to both of you for this extremely challenging/captivating/depthful discussion!!! as far as UVB, i must say im a NON-believer. the marijuana man video brings forth no evidence whatsoever (amoril has stated his case in a much better and more convincing way than the self-proclaimed guru on the video!!!) As with UVB, a similar case could be made for countless other factors.... temps, humidity, even UVA light...... maybe all of these concur into producing THC, rather than UVB light alone... who knows... what makes me very skeptical about this thoery is that, as proteus pointed out, resin and thc is produced towards the end of the plant's life when UVB emissions are rapidly declining! Surely if thc served to methabolyze and protect the plant from these harmful rays, it would be present much earlier in the plant's life, when UVB emisisons are at their peak.... but it is not so. i dont know guys.... ill stay tuned for the further evidenc that IM SURE you two are gonna bring to this discussion... in the meantime, take care y'all! PS this is one of my first posts, so hi to everyone. im slanaxe, from italy..... see ya around!!
Sanaxe, thanks for joining. I can't say that I am a believer or a non-believer, I just don't know. (On second thought, not knowing makes me a non-believer doesn't it?) The only thing that can convince me is when I see convincing evidence. Many of these "theories" are extraordinarily wild and off the wall with little or no evidence supporting them. As Carl Sagan once said, "Extraordinary claims require extraordinary evidence." I agree with you, there are too many other factors that correlate with UVB to make a determination. We already discussed low humidity, stress, and increased light output due to adding a UVB bulb. There is another: pest control. It has long been recognized that UVB radiation kills microbes and even insects. In fact germicidal lamps (that are used for this purpose) are nothing more than UV lights. Without viruses, bacteria, or other pests, this would produce a healthier plant thus giving it more chance for higher yield and more THC. There are many studies showing how UV light affects pests. I'll give a few examples below: "Interestingly, one of the few studies that included more than one trophic level has shown that direct damaging effects of solar UV radiation on phytophagous insect larvae can counterbalance the negative impact of UV on algal photosynthesis and result in increased biomass accumulation of the primary producers in experimental freshwater ecosystems." --http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=15336 "In both seasons, filtering out solar UVB resulted in a 3- to 5-fold increase in the density of the thrips populations that invaded our field crops." --http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=15336 Although those studies do not address cannabis directly, thrips are a pest to cannabis also: "Another common herbivore is thrips. They are small, fast-moving insects with wings. They rasp, or grate the leaves open, and then suck the sap out. THRIPS PREFER BLOOM TOPS, AND FRESH, YOUNG LEAVES. [caps, mine] --Marijuana Diseases Pests and Plagues Of course using UVB for pest control goes against the interest of the UVB bulb user. If pest control is the causal agent, then you don't need a UVB light in your grow room for the simple reason that these pests don't occur there (if your grow room is designed properly). So now we have at least 4 factors that correlate with UVB exposure, and there may be more.
May contribute? Many growers know that cannabis just doesn't grow well in extreme humid climates, especially like the humidity found in tropical lowlands where gets up to 85-95%. The leaves can't transpire as well and the yields are lower. Cannabis likes a humidity at about 50-60%. Some growers go down to the 40s at late flowering. And, no, it doesn't mean that UVB light is not a factor, but it also doesn't mean that it is. It requires more study. For you to write, "Ultraviolet-B type radiation is the single most important environmental factor for developing varieties with highly narcotic properties" is simply not warranted. The fact that you remain convinced shows that you don't need convincing evidence. After all, you were convinced from the very beginning before you did further reading. Remember that it was from "just one study, and loads of anecodotal evidence" that convinced you that UV-light promotes resin gland production. That's all it took for you to consider it a fact. Good scientists don't accept anecodotal or hearsay as evidence. You think? Other correlative factors (increased light output, pest control) would likely disguise any belief that UVB directly promotes THC. It needs more study. There are at least 4 factors that correlate with UVB light, and I think that humidity, stress, and added light power (due to UVB) correlates better to THC production than does UVB alone. I could provide extractions from pages and pages of studies that are far more extensive than for UVB alone and it would swamp your "evidence," but I'm told not to do so because this forum is about UVB lights. So be it.
i do find it interesting that you keep addressing the same issues with UV light, as opposed to looking into the terpene / olivetol / precursor chemicals idea. I never claimed to know it all, and it turns out that I may have been right, but for all the wrong reasons (not understanding thc synthesis, i still dont, but at least I do more ) ---- and dude, I said it once, and ill say it again since you keep bringin it up without doing it. start a new thread, and we will discuss the ins and outs of everything we can think of relating to THC prod. didnt carl sagan also say that he would be surprised if we were alone in the universe? While I agree with that sentiment, wheres the evidence? (i bring it up since im assuming the 'cosmos'naut is your idol or something lmao)
A Note About THC Levels The aim here is to grow cannabis with high levels of THC in it, but what does that mean? High levels of total THC (yield)? Or do we mean potency (THC per mass)? They are really two different things. Some "experts" think that THC yield and THC potency occurs in cannabis as an inverse variant to potency and yield. That is, as THC yields increase (by more resin production) then potency declines, and vise versa: as potency increases (THC per mass), yields decrease. I don't know if this is true but this inverse property seems to occur in other crops like tomatoes, fruits, and especially in wine vineyards. For reasons that wine experts understand, the greatest wines are usually grown in small vineyards. Small vineyards don't yield that much but the grapevines they choose are superior for making quality wine. Inversely, the mass producers generally choose grapevines that produce the most yield. More yield, more profits. But these wines are rarely rated above 90. There are exceptions of course, but you get the idea. This may be what we are seeing in our grows. Are we fooling ourselves by thinking that more trichomes or the stickiest leaves produce the best quality? I don't know. I know that I've enjoyed the high from cannabis that had few trichomes (even with seeds) and I've enjoyed highs from plants with lots of trichomes. If the grower is selling his product and wants to make the biggest profit, perhaps he (or she) should aim for highest yield (in total grams, ounces, pounds, etc.). If the grower is only interested in knockout highs, perhaps aiming for the highest THC per trichome (THC per mass) is the best way to go. For the grower interested in quality, perhaps it is a combination of the two. Personally, I'm not that interested in yield. I'm not growing for profit; I only grow for myself. I don't even know anybody around me who smokes marijuana and I only grow 2 or 3 plants at a time, only once a year or longer. I prefer to harvest earlier rather than later. I only have so many THC receptors in my brain, and when I think I've maxed out the limit, I don't like it. I prefer a milder quality high instead of a knockout couch-lock high. I can affectively achieve potency by other means, such as hypoventilation (the opposite of hyperventilation) and make the pot last twice or thrice as long as without hypoventilating. What has been discussed here pertains to the hypothetical benefits of using UVB bulbs to increase THC content. Some of the arguments claim that UVB bulbs cause more trichome production, thus increasing yield. Other arguments favor the idea that UVB causes more growth in the trichome head, thus higher THC per mass (but possibly lower yield). I would suggest to those who believe that UVB bulbs increases THC content, that you should consider the purpose of your aim. You may not be getting what you think you're getting. No one knows for sure if UVB lights actually increase THC content, let alone which *kind* of THC content they might produce! The only way to find out is by actually measuring THC levels. There has been only two studies (that I know of) that has tried to measure THC levels from using UVB lights and the results are conflicting. The Lydon study showed increase in one grow and no increase in another, and the best results were within the polymorphism (variability) of cannabis. The London study didn't observe any difference by using an indoor UVB light. This to me looks like a no-sum-gain. The rest is mostly speculation. We know the damaging effects of UVB and some of the benefits. If UVB kills anaerobic harmful bacteria then it probably kills beneficial aerobic bacteria too. In a controlled grow-room we can eliminate harmful bacteria without requiring UVB bulbs and without destroying the beneficial kind. Without the ability to measure THC levels we don't really know what we are risking. Unfortunately we growers don't have access to gas-liquid chromatography instruments or spectrum analyzers, but we do have other ways of measuring the growing effects upon cannabis. We have pH meters, TDS meters. We have accurate thermometers that measure in Min. - Max. ranges. We have humidity meters, CO2 meters, barometers. We can measure dry mass yields by measuring with a scale. We can measure light output with light meters, watts, etc. We can measure the height and width of a plant and count the number of leaves and the thickness of stems. We can obtain these measuring devices at relatively low cost. We can share this information with each other and we can duplicate the methods we use because we've measured them and can pass this information to others. If growers have discovered that using 1200 ppm of CO2 will increase yield by so much, we can use those numbers in our grows to see if we get similar results. We have to be able to measure yields on our end too. If we discover that total yield has dropped by using a certain technique but we still get an enjoyable high (notice I did not say higher THC) then we can report that too. I think it would benefit the cannabis community to try to find out answers with the instruments we have instead of wasting valuable time with unproven techniques, especially without our ability to measure what we are trying to achieve or to understand what we mean by "increased THC." It's interesting to speculate but to make claims without being able to measure what we are talking about can lead us astray more often than it can help. I don't know much about anything let alone about our most valuable crop. Cannabis is an amazing plant. It is arguably the most valuable plant per mass of any other crop. I don't want to risk damage to this wonderful plant without further knowledge, and we do know the DNA damaging effects of UVB. But I do know a few things. I know if I over water or under water, I can kill the plant. If I use the wrong nutes or the wrong quantities, I can damage or kill the plant. If I use too much or too little light, it can kill the plant. Between all these extremes, I am, somehow, able to get this plant into harvest. I get my information from others who have supplied me with their measurements. I want convincing evidence. I don't want beliefs, I want knowledge, and this takes good observation, hypothesis, and the ability to measure things accurately. I'm sorry I ranted too long. THC does strange things to my experience of time, ha-ha.
THese are some extensive posts I don't even want to go read them all but I think Proteus is mistaken about the THC protecting the plant it does absorb it and allows for more efficient production of THC. They aren't really sure what chemical reactions are occuring but they seem to be driven by UVB and more of the blue specttrum. MH and CMH always pack the resin and trichomes on. HPS does pretty well too especially if you have a grow specific bulb with more blue spectrum and it does great in the density arena. I definitely have seen the light so to speak and have found that sativas seem to grow equally as well under HPS as it does under CMH if not better because the intensity is alot better.
RichardDean, if you read the posts you will understand why I see no convincing evidence for UVB and THC production. Correlations do not prove cause. If there is any special effect using MH or CMH bulbs, how do you know it isn't due to the blue spectrum alone? I do know that you don't need UVB bulbs to get quality cannabis. Peace.
outdoor growers beware! your plants are in danger... i advise you to bring them indoors before UV-B destroys your crop! only use non-uv-b emitting bulbs please, i urge of you! if you want quality... don't use UV-B.
Ha, ha, that sounds like good advice to me, although I don't think UVB will destroy the crop (although it may damage DNA and produce lower yields).
That's funny, I slather marijuana resin all over my body when I go to the beach. I hear it makes a good sunscreen