UV Light and Terpenoids

[indifferent]

From what you wrote, I assume you suspect that the UVA may have caused the damage to the exposed side of the bud. Another poster suggested that outdoor plants get plenty of UVA. This is true, natural sunlight has a ton of UVA and rolls off the UVB hard at around 300nm. The reptiglo bilb you used (26w CFL) uses aggressive UVB phospohors that do not emulate natural sunlight. Since you beamed that into the bud it is not surprising that there was tissue damage.

There are many other reptile lamps that do not use the aggressive phosphors. The repti glo tubes for example use the correct (human tanning) phosphors that roll off at 300nm just like sunlight.

I once read somewhere that back in the ol days (lol) suntan lotion was released that only blocked UVB but allowed UVA through. This caused some serious problems for tanners. Since the UVB was blocked, their skin could not develop the correct melanin and the UVA was allowed to penetrate the skin and go on the rampage (causing free radicals, tissue damage, even cancer).

Moral of the story is, when in doubt emulate the sun as naturally as possible. That's my 2 cents anyway, good luck!

Mean-As-Hell Australian sun:

Good info mate, I know they put carrots in a lot of suncreams, reason being carrot are high in carotenoids and the 6 carotenoids are a type of terpenoid and also found in cannabis and human eyes and skin.

I think UVA is useful in stimulating production of carotenoids, terpenoids and flavonoids, but too much is harmful to the plant, as we saw when I blasted that Oaxacan. I had the bulb too close imho as the other tops on the plant not so close to the bulb also showed the purple colouration indicating some change in the carotenoids etc but didn't have the same damaged trichomes I saw on the top nearest the bulb.

I now think reptile bulbs and tubes are a waste of time for UVB, they have so little. The intensity of UVB 15cm from a Reptiglo 5.0 tube was measured at only 15mw/cm2 whereas the same meter read 250mw/cm2 at 15cm from a Philips TL/12 20W tube.

By my calculations, the TL/12 is producing nearly 17 times the intensity of UVB without the UVA, violet, blue, green etc that the reptile tubes also produce.

This makes them a far more suitable source of UVB imho. UVA sources are cheap and readily available in the form of tanning or blacklight lamps/tubes.

I have researched the UVB intensities we need to emulate sunlight and found these figures that i am going to use as my guideline:

140mw/cm2 - UVB at sea level in California
250mw/cm2 - UVB at sea level at equator
375mw/cm2 - UVB at high altitude such as Himalayas, Kilimanjaro etc

So I am taking 140 as my minimum intensity needed and 375 as the maximum, however, in the distant past UVB levels were much higher so the higher order plant species (which includes cannabis) evolved in a high UVB environment and it has been shown that cannabis can be grown under extremely high UVB levels, demonstrating it's ability to adopt to intense UVB. Therefore there theoretically is no upper limit, but if we are trying to emulate nature today, then 375 is the highest you can get on the earth's surface unless you are stood in the Antarctic under the whole in the ozone layer.

I am aiming for an intensity of at least 250mw/cm2 of UVB as I am growing equatorial sativas and want to emulate their natural environment. This just isn't possible with reptile tubes and all the other UVB sources apart from the TL/12 have way more UVA than UVB so in order to reach the 250 figure with a lamp other than the TL/12 would mean you also had very high levels of UVA and I think that would be detrimental to the plants.

So unless someone knows of another pure UVB source, the TL/12 tube is the only option, it is a pure UVB source as it has no UVA or visible light.

Further reading last night tells me that all of the UVB spectrum from 280 to 320 is significant in THC production. 300 to 320 affects THC production directly and 280-300 affects the production of THC precursors. Therefore the TL/12 with it's broadband UVB spectrum centred on 311nm is the ideal lamp for stimulating THC production.

UVA doesn't have a role in THC production stimulation but is useful for stimulating production of other stuff.

Therefore my lighting system I'm building for my experiments is going to be using Actinic tubes for deep blue, violet and the higher part of the UVA spectrum; tanning tubes to cover all of the UVA spectrum with a tiny bit of the higher part of the UVB spectrum and TL/12 tubes for UVB.

I think what needs to be worked out is the ratios of UVB, UVA and blue needed. I've already explained the intensity level of UVB needed, but I'm not at all sure what intensity of UVA and blue are needed. Maybe the place to begin is emulating the UVA levels at the equator at noon as that is how I determined the UVB levels needed.

 

[titoon29]

Good find! Just wish I had the money to spend on such things! It's sad that the key study of this subject is almost a quarter of a century old

yes i agree on that... and that s a very important matter, as it could be really usefull for medical purposes (changing terpens/cannabinoids ratio)..
but as long as the medical world doesn t understand the diversity of cannabis, i doubt this will be a field much researched on.

Titoon, just a thought, but you're in a high UV location and I believe you have the possibility of growing some plants outside? You could be a very interesting UV test outdoors, take two cuttings of the same plant and grow them outdoors, but keep one under a sheet of plastic such as is used for greenhouses and is opaque to UV. This would show you what effects the UV in natural sunlight has on a plant.

There are records of UV levels for most places on the earth and most local weather services give UV levels, particularly in areas with high UV, so someone doing a UV experiment such as I suggest outdoors would have a full set of data available on the UV received by the plant that was not covered by plastic.

well mate you must be mistaking, weather is pretty lame here in the country, especially where i am! i m in the country of frog and snail eaters btw i ld like to know where you think i was, i ld be glad to be mistaken for an english speaking personn..
and also i m leaving for 6 months in nepal in a month, so any outdoor plan is pretty much dead for this year...

your tests will be pretty interesting, that's too bad you don t have access to gas chromatography like GHS to get the terpens quantity evaluated... a GC is my dream, but that is expensive and hard to use stuff...
It will be pretty hard to get without this stuff much clue on the particular effects of UVB, or it will need a lot of tests. but at least you ll see if it improves the herb!
At the moment i m using a mh bulb for my flowering, it has a few uvb in it. but i usually have tasty herb anyway i guess, so hard to tell the difference.

keep the great work !

oh and by the way the graphs of the australian sun are really impressive, yes the sun there is really crazy, hopefully it is so warm you don t go out and get that quantity of UVB.
I smoked some wally s c99 grown out there by the man himself, some of the best outdoor buds around. and the hash is sooo wonderfull,i don t know if the uvb play a major role, but it was really good !

 

[indifferent]

Ah, I realise my mistake now, I mixed you up with tiphoon who lives in Thailand!

Bonjour mon ami, votre Anglais est tres bon, mon francais est tres merde, pardonez moi!

Merci beaucoup pour l'information, c'est tres interessent!

J'aime les grenouilles, un gout de poulet!

I hope you enjoy Nepal, perhaps you can help me with my future experiments. If you are able to collect seeds from high altitude cultivars in Nepal and document with pictures the appearance and effects of the buds then share some seeds with me to grow in my experimental UV box, it would be quite valuable to compare imho, I could send you some of the bud I produced so you could assess how the taste and effect compared to what you experienced in Nepal perhaps?

Also, if you are able to take a UV meter with you and take some UV readings, i would very much value that information.

BTW, I didn't realise you aren't a native Anglais speaker!

Looking at the pic you posted, looks to me like Ecuador, Bolivia, Namibia, and NW Australia are the places with the most extreme UV, so I'd like to track down some seeds from those places. Namibia and NW Ozx are mostly desert, not sure if there is much if any Cannabis there, probably some in parts of Namibia. Ecuador and Bolivia definitely have Cannabis.

 

[titoon29]

well i found your publications for 30$, still too much...

The effects of UV-B radiation on photosynthesis, growth and cannabinoid production of two greenhouse-grown C. sativa chemotypes (drug and fiber) were assessed. Terminal meristems of vegetative and reproductive tissues were irradiated for 40 days at a daily dose of 0, 6.7 or 13.4 kJ m-2 biologically effective UV-B radiation. Infrared gas analysis was used to measure the physiological response of mature leaves, whereas gas-liquid chromatography was used to determine the concentration of cannabinoids in leaf and floral tissue.

There were no significant physiological or morphological differences among UV-B treatments in either drug- or fiber-type plants. The concentration of Δ9-tetrahydrocannabinol (Δ9-THC), but not of other cannabinoids, in both leaf and floral tissues increased with UV-B dose in drug-type plants. None of the cannabinoids in fiber-type plants were affected by UV-B radiation.

The increased levels of Δ9-THC in leaves after irradiation may account for the physiological and morphological tolerance to UV-B radiation in the drug-type plants. However, fiber plants showed no comparable change in the level of cannabidiol (a cannabinoid with UV-B absorptive characteristics similar to Δ9 THC). Thus the contribution of cannabinoids as selective UV-B filters in C. sativa is equivocal.

 

[amoril]

ill come back later, with a more complete thought. thats why i edited this one away...

i feel like the rabbit, always eyeing his watch

 

[indifferent]

Wow titoon, some excellent digging you are doing. That abstract tells me a lot of important information.

By terminal meristems I think he means the growth tips, I guess this means he hung a UVB light source above the plants.

He says UVB increases THC production in drug type cannabis but doesn't affect production of the other cannabinoids, that would strongly suggest THC is produced as a protection against UVB.

Also, he says that drug type cannabis is not affected in growth or structure by UVB, more good news.

I found a thread on another forum where a Dutch guy grew two Afghan Kush (White Label) seeds under a 300W Osram Vitalux as an experiment to see what would happen. They grew fine, showed some burning on the leaves from the ultra high UV levels and weren't as nice as if they had been grown under fluoros or halide, but it does show that cannabis is able to adapt to a very high UV environment and can make effective use of UV to grow. The pics show his plants ar 26 and 28 days from seed.

PS. I wonder what Mr Lydon has been doing in the 25 years since he wrote that PHD thesis? I bet he's done some more cannabis research since, be great to read his work and talk to the guy.

 

[moonunit]

Fantastic thread and info. I cannot get sats to grow indoors as well as i can in the aussie long season outdoors( as far as the high is concerned), a new gen of grow lighting will bring a whole lot back indoors for sativa lovers especialy i think. Again great thread, great to see some real and useful info and discussion.
much respect
Moonunit

 

[indifferent]

Hey moonunit.

Perhaps you can try a simple experiment - grow two cuttings outdoors, keep one under some UV blocking plastic sheeting then compare the highs of the two plants, one will have had the UV from the sun, one won't. This will tell you what role UV has played in creating the effect.

Then you will have some info on how UV has affected your plant and can use this to design a supplemental UV lighting system indoors.

 

[razor ridge]

Well all of you are greatly advanced than me, however after I saw the MM vid about this I put one in my room. A 2 foot repti-glow. I have definetly noticed alot more crystallization and tricome production since the addition of the UV-B bulb. I'm not saying they taste better or are more potent, but here are a lot more glands than before. I have a partner that grows clones off my mother plant, in the same soil, FFOF, with comparable light strengths, and hid buds aren't nearly as crystallized as mine, so for me they defiantly make a difference......

 

[elmanito]

In my search for another document i found this document on the net from last year, so for the people who are interested, just follow the link.

http://www.elsevier.com/authored_subject_sections/L07/misc/Fitote_80_p207.pdf

Namaste

 

[Ghostwolf]

That is a very good document elmanito. Thanks for the link. I down loaded it to my UVB file.

 

[B. Friendly]

i don't know about change the terpenoids but it brings them out. I have used reptile lights and believe it makes a difference.

 

[hades]

Yo Amoril!

I'm glad you are still around fighting the good fight. I found this thread when researching UV-B and cannabis again. I posted up my research paper over on MNS because leMarcel was using UV-B lamps and I asked him why, and he asked to read it (he actually translated it into French, bless his heart!). I lost the images for it and found this thread when looking for the dissertations again, although it looks like I will end up having to pay for them again. I haven't had a chance to read through this thread, yet, but I plan on doing so tonight, and I am interested in what you have found lately.

Get this, though. David Pate's dissertation in 1979 was about this topic, and was titled "The Phytochemical Ecology of Cannabis". It had a very nice graph showing how just about every 'drug-type' variety came from areas within 35 degrees latitude of the equator, and the opposite was true for 'fiber-type'. He also wrote a chapter in the book Advances in Hemp Research, published in 1999, titled "The Phytochemistry of Cananbis: Its Ecological and Evolutionary Implications", in which one of the sub-chapters is about the effects of Ultraviolet-B Radiation. He quotes the 87' Lydon paper when citing a reference for stating that it 'produces significantly greater quantities of THC'.

What is so weird about this? In the big debate on OG after publishing my paper, Sam Skunkman posted a lot stating that UV-B has no positive effects on Cannabis. He said that David Pate was a close associate of his, and that they performed an experiment that showed no difference in the level of THC under UV-B exposure. I just found out that David Pate actually works for Hortapharm!

Something weird is going on there........

The '87 Lydon article was really hard to find back then, and Sam Skunkman was kind enough to send me a copy of his. It was really the most conclusive experiment done, although Lydon also did his Ph.D. dissertation on the same subject.

Wow titoon, some excellent digging you are doing. That abstract tells me a lot of important information.

He says UVB increases THC production in drug type cannabis but doesn't affect production of the other cannabinoids, that would strongly suggest THC is produced as a protection against UVB.

Actually, the very last line of the abstract states that his research showed THC (or CBD for fiber-type) as a UV-B filter (or sunscreen per se) as equivocal, meaning it did not show it, but it didn't exactly disprove it, either. This is a little misleading, though, I believe, because there has been a lot of research to get Cannabis split into two distinct species, indica ('drug-type') and sativa ('fiber-type'), and if they really are two distinct species, then it would be perfectly plausible if one used it's resin as a UV-B filter, and the other didn't, especially if one was from the tropics and the other from the north.

PS. I wonder what Mr Lydon has been doing in the 25 years since he wrote that PHD thesis? I bet he's done some more cannabis research since, be great to read his work and talk to the guy.

When researching this in 2004 on Overgrow, I was able to track him down and he spoke with me briefly about his work. He basically said his work was inconclusive, and that there needed to be more research done along these lines to study the relationship further.

I'll read through this thread and hopefully I can contribute a little. I'm glad that I have some people to discuss this with.

 

[hades]

Aye, that Joe Knuc article is a joke.

Sam did indeed say that he was unable to find any benefit to UV light, he used UV fluoro tubes in a greenhouse.

Two great points Sam made that folks need to bear in mind:

1. If UV was truly important in the production of resin and potency, then all indoor grown bud would lack resin and potency as fluoros and HIDs don't produce UV.

This is always the main argument against UV-B's effects, understandably. Although, if a plant were bred indoors for THC, would it not make sense that it can produce THC indoors? I can not say conclusively that UV-B will produce better smoke for every strain, but then again, I'm certain you can't say conclusively that it doesn't.

2. A high altitude cultivar such as a Highland Nepalese will have the same high if grown at sea-level with a lower UV level, the nature of the high and potency being genetically pre-determined.

This is just straight up false. There is a lot of research to back this up. Environmental pressures effect the growth of Cannabis in many ways. I have personally grown the same clone in two different environments, and have had two noticeably different final products. And if someone wants to say that nature of the high and potency are predetermined genetically, I can understand that, but to say that you know for a fact you have grown that plant to it's genetically set ceiling for potency and brought out it's best high is hard to prove. You have to basically be able to say, "I couldn't grow this plant any better, ever."

has anyone ever published any proper scientific work on this subject?

Actually, there is a lot of scientific work on the subject, but not really Cannabis in particular, although there are some good ones in that category, too. David Pate and John Lydon both published two works about it, as well as references of its effects are spread out through a lot of different sources.

 

[Ghostwolf]

 

[Ghostwolf]

I have a question for anyone who may know the answer to this. I'm doing a couple of pc mid tower case grows. And wanted to know what intensity of a CFL Reptile Glow bulb could I use in them, and how differently would I run it from the other lights, time wise. Or is this even possible to do in a pc case? This knowledge would be greatly appreciated. Thank you

 

[intel2000]

Indifferent - what ever happened to your experiment? What was the difference in how the 2 different parts of that plant smoked?

 

[3rdEye]

Excellent thread. Thanks for the digging Hades. I'm inclined to think that a wider spectrum, including UV parts of the spectrum, would provide a more balanced view of what a plant can produce under "natural" conditions. It must be kept in mind that natural conditions vary radically from locale to locale, so even attempting to narrowly define what natural means is subject to opinion.

Are we looking to maximize all or only some cannabinoid generation? Might we also want to look for more endogenous or exogenous naturally occurring compounds that could be added to the soil or perhaps applied via foliar feeding to either complement or amplify any effect we could get from lights?

Why are people interested in this? Not just the .. hey i want to get higher argument either. Although that's perfectly acceptable too.

 

[BlueberryLovr]

Indifferent - what ever happened to your experiment? What was the difference in how the 2 different parts of that plant smoked?

Wondering about this too! Been following your posts for a long time now. Always something new to learn from ya.

 

[spurr]

@ all,

I have many studies on the topic of UV-b irradiation of cananbis, and higher plants in general. All of which on cannabis show a great increase in THC, but not CBD, if proper daily dosage (irradiance) of UV-b is applied (ex. leaf THC increases of > 30% and flower increases of > 20%). I can post up many refs in the days to come, I'm too busy now.

I have used comparative Thin Layer Chromatography to prove, in my gardens, that UV-b irradiated plants have higher THC than non-UV-b irradiated plants. I plan to use HPTLC (High Performance TLC) and GC (Gas Chromatography), along with tighter environmental controls, in the future, to re-test the affects of UV-b on many varieties and races of cananbis. Right now my testing thus far isn't sound enough for publication, but soon, by early next year, I will have sufficient controls and measured of various environ variables to publish a paper.

Also, UV-b doesn't increase terpenoids AFAIK, but it does increase flavonoids because flavonoids are UV-b screening agents.

One important point is that UV-b is deleterious to plant tissue in lower irradiance gardens (lower light levels within PAR rage, i.e. PPFD). With higher PPFD (Photosynthetic Photon Flux Density) UV-b is less deleterious to plants.

Also, UV-b helps plants grow in a few regards due to "cryptochrome" (blue light photoreceptor cells) responses, such as leaf development, stomatal conductance (openness of stoma), etc.

I have done the math to convert an ideal daily (diurnal) dosage of Uv-b found at 9,000 ft up a mountain in Brazil in summer into microwatts/cm^2. Using uw/cm^2 as a quantification we can use UV-b light meters, such as one from "solar-tech" to measure, and change, the Uv-b irradiance over the whole day. I provide the same level (daily "dose") of UV-b as found 9,000 ft up a mountain in Brazil near the equator. I use 300watt mercy vapor UV-b lamps often used in professional reptile culture. Most of the UV-b lamps from pet stores usually do not provide enough irradiance to provide ideal Uv-b dosage over a whole day for highest THC content in cannabis. I use 3 hours of irradiation per day to equal the same daily dosage of Uv-b found at 9,000 ft near the equator.

Until later, happy growing!