Quote:

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I definitely wouldn't want to be around the UVB lights when they're on though.

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Ha, I was going to make a thread on this. I was doing a more comprehensive search on google to find some more info to help with the thread, and I found this on the second page. Of course after reading it, I remembered reading this before.

This definitely seems to be the way to go. THC has high capabilities of absorbing UV-B, protecting the plant from the radiation. The idea that the plant would produce more THC to protect it from its presence would seem reasonable. It should also be noted that HPS essentially provides no UV-B, which is most commonly used for indoor flowering. It would definitely seem that there would be a significant opportunity for THC production that is being lost without a source for UV-B.

The reptile lights would probably be the best source. You'd probably need a few unless you found one with a lot of watts (like this one). A tanning light would do it too, but would be pretty expensive I would assume.

I've heard that its best to not leave them on for more than four hours a day because UV-B is harmful to plants, but I would think this is something best determined through one's own experimentation. Simply turning them off when you're in the room, or having them on when one knows one won't be in the room, negates any threat to oneself.

 

Quote:

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coda said:
Also forgot to mention most people turn these lights off in the last few weeks of flowering to prevent the light from destroying any active alkaloids.

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Quote:

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coda said:
Apparently UV light in the early stages of flowering encourages heavy, and early, trichrome formation.

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Yes, but what is really important is the production of THC as well. Trichrome production doesn't necessarily equate into THC production.

Quote:

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Sirius said:
I've heard that its best to not leave them on for more than four hours a day because UV-B is harmful to plants, but I would think this is something best determined through one's own experimentation. Simply turning them off when you're in the room, or having them on when one knows one won't be in the room, negates any threat to oneself.

---

Quote:

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Yes, but what is really important is the production of THC as well. Trichrome production doesn't necessarily equate into THC production.

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Quote:

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The reptile lights would probably be the best source. You'd probably need a few unless you found one with a lot of watts (like this one). A tanning light would do it too, but would be pretty expensive I would assume.

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Quote:

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I hadn't read this before. Do you remember where you found anything about that?

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Quote:

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The round head of the trich magnifys the uvb in late flowering stages until they cloud up and turn amber because they stop acting as magnifiers. Pot TV did a show recently that shed much lite on this subject.

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Quote:

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Do you plan on experimenting with this, coda?

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Quote:

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Could you use a UVC bulb as a supplemental light at say a certain distance from your plants?

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coda said:
yes, i know this. I was just pointing out one of the benefits to the UV light. More trich's = more protection for your plants = healthier, happier, plants = more potent plants = ....etc

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I was just throwing it out there since it hadn't been mentioned yet.

Quote:

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It really depends on the size of your grow tho.  More plants and more sq ft = more uv lights needed.  The grows i have seen usually have at least two lights in there.  The lights themselves are relatively inexpensive so purchasing a couple won't put too big a dent in your pocket.  Make sure to get the 10% UV bulbs tho, they're more efficient then the 5% ones.

---

The cheap ones run at lower watts and can only penetrate a few inches. How many one would actually need, of course, just depends on the specifics of one's grow, like you said. I was just saying that one of the inexpensive bulbs alone probably isn't going to do it.

I also ran across an article on reptile lighting and pet supplies in general, regarding the lack of truth-in-advertising laws on the products. Here's an excerpt. There's also a list of ones that actually do produce UV-B.I don't know enough about any of this, but just tossing it out there as a grain of salt...

Quote:

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The problems with truth in advertising goes beyond the misleading use of the term "full-spectrum". When it comes to UVB-producing fluorescents, the percentages given are not particularly useful as the manufacturers rarely tell you what that is a percentage of. If you have a light producing, for example, 20% of its total wavelengths in the UV range, and of that 10% is in the needed UVB range, while another light produces 40% of its wavelengths in the UV range, with 6 percent of that in the UVB needed range, the product with 6% of the 40% is going to produce more UVB in the needed UVB range than the other product. The product with "10%" on the package may look like the better light than the one that says "6%", but it isn't if that "10%" isn't providing enough UVB for your reptile.

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Quote:

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UV light degrades THC, this is why you don't dry your weed in the sun.  When using UV lights in your grow there is a certain point where you want to stop using them because the trichromes aren't utilizing the light correctly.  This happens when the trichs start going from cloudy to amber (towards the end of the cycle).  At this point the actives are beginning to over mature anyways (amber trichs yadda yadda) so the extra UV light on them (IMO) just helps to further degrade the goodies in your plant.  Here's a slightly better explanation:

---

Quote:

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What you said about THC production is true, BUT, it's because of the increased trichrome production that your THC levels are increasing.

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After watching someones grow produce trichromes by the end of the first week was enough to convince me to buy some, then, reading up on WHY it was so just made it concrete that i HAVE to have these in my next flowering cycle.

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Exactly! It seems as logical as applying nutrients really.

Quote:

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The cheap ones run at lower watts and can only penetrate a few inches. How many one would actually need, of course, just depends on the specifics of one's grow, like you said. I was just saying that one of the inexpensive bulbs alone probably isn't going to do it.

I also ran across an article on reptile lighting and pet supplies in general, regarding the lack of truth-in-advertising laws on the products. Here's an excerpt. There's also a list of ones that actually do produce UV-B.I don't know enough about any of this, but just tossing it out there as a grain of salt...

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Actually this is the point I was arguing against. THC itself is doing the absorption. Of course the trichrome production increases and this further increases the production of THC, but I would have to assume that THC production within individual trichromes increases as well. If the amount of trichromes stayed the same with the introduction of UV-B light, the THC production within the amount that is there would still increase. I think this is supported by the idea that the amount of trichromes in general doesn't equate into high levels of THC, even though it is reasonably safe to assume as much with varieties of cannabis used as drugs.

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Quote:

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coda said:
In that case having a light that isn't as strong would be a good thing. I can understand your concern with light penetration, but, considering how cheap these things are and how versatile they can be there's no reason not to add some to hit the lower portions of the plant.  In fact you could take the 4' tubes, put two on top, and buy two more to  place on opposite sides of the plants.  this way you have light coming from the top and the sides.

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I agree with you completely on all of these points. I was just saying that it wouldn't take just one of these bulbs, but possibly a few. My friend is planning on using the inexpensive reptile ones, anyhow.

Quote:

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hmm, i'll have to go back and read up on the biochemical process again, but it was to my understand that it was the trichromes that absorbed the UV light and the plant then used that absorption to increase the levels of THC.  I think we're thinking/saying the same things in just different words.

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I'll read up more on this as well soon, but from what I've been reading, its THC that absorbs the UV-B light, the trichrome simply collecting it and magnifying it to the disc cell or something like that.

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all known experiments that add artificial UV light in a controlled environment have proven that it does not make any difference."

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Jellyhashman said:

Quote:

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all known experiments that add artificial UV light in a controlled environment have proven that it does not make any difference."

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Well according to Edward Rosenthal it has been tested over and over and proven to increase trichome production. Its in Ask Ed and I'd believe Ed over Jorge.

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Jellyhashman said:
Its a book he sells Ed's book.

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stoney.69 said:
Dude I dont know if he is alive or dead.
But Quick Trading Company has a active Ask Ed forum running now.

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Dr. Penguin said:
So have any of you gone through with the experiment? I'm very curious to see first hand results. I have looked into this before but was discouraged by Jorge Cervantes. "UVB light is supposed to promote resin formation on buds. However, all known experiments that add artificial UV light in a controlled environment have proven that it does not make any difference."

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Quote:

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BC Growers Association
UV and It's Effects


Here are a few posts from friends on the net that I've collected.

Posted by oldtimer1 on December 25, 1998 at 03:30:21 PT:

In Reply to: Didn't mean to 'steal' your handle brother!!!!! posted by Old Timer (2) on December 23,
1998 at 16:51:47 PT:

Hi there Old Timer I have a couple of other thoughts on why the quality of the vars has slipped in
Holland I think the main one is the way they grow or should I say the type of lighting they use. Most
of the strains they have came from America and were either developed under real sun or under big
halides and both these sources have a big uv content. The Dutch are great gardeners and have had to
use supplementary lighting in their glass houses for years so they can grow all the year round. The
lights they developed were a highbay type such as Poots and Phillips fixed on grids 5 ft or so above the
finished plant canopy . And of course they chose the lamp that gave the most photoactive lumens per
w, the sodium lamp which has virtually no uv output. Of course when cannabis came to Holland the
farmers son who decided grow a bit of pot used the same system as in dads 2.5 acre glass house.
There is no doubt that all the most potent varieties of cannabis come from areas of the world where
the background uv is high to extreme and that the potency and complexity of high relates the almost
directly these uv levels. Cannabis is a highly adaptable and over a few generations change to new
conditions and this is what I think has been happening in Holland. I could go into more detail but this is
not the board to do this on but it does relate to your comments. It is interesting to notice that
Greenhouse seeds have mentioned uv for the first time I think this must have come from Nevils input
and if they are now taking this into account maybe things are turning to the better.
As far the var you were asking about I suspect D J Short would be the man to ask, from I can glean
he is a very private person. You could try writing to him care of Mark Emery sorry I cant help futher.

All the best have a great Crimbo all. Ot1.

O.K., but does U.V. content change genetics?

Posted by Uncle Ben Dejo on December 25, 1998 at 18:35:34 PT:

In Reply to: Re: Didn't mean to 'steal' your handle brother!!!!! posted by oldtimer1 on December 25,
1998 at 03:30:21 PT:

Read in a Tom Flowers book on forced mj flowering, that MJ grown on higher elevations, ie, 10,000
ft. tested for higher THC content. I assume this is the plant's response to this particular environment.

I have always rotated my plants between sun vice HPS, security and weather conditions permitting,
and can't complain re potency and growth habits.

So.....are you proposing that genetics have been altered on a short term, or a long term basis, regarding
particular light setups by the Dutch?

Uncle Ben


Re:yes

Posted by oldtimer1 on December 26, 1998 at 04:57:24 PT:

In Reply to: O.K., but does U.V. content change genetics? posted by Uncle Ben Dejo on December 25,
1998 at 18:35:34 PT:

I think it is a problem that has been developing through the generations. Wernard of [Positronics] was
aware of it being a problem and now Greenhouse seem to be taking it on board. I haven't read Tom
Flowers but high elevation plants that have been there for generations are high in thc but more
importantly it is a lot more complex. On a short term basis a clone from a known variety Indica type
will have a slightly more up high with the addition of uv during flowering but Sativas seem to improve
a lot more with a much clearer up high. I would suggest that if breeding for seed indoors the addition
of uv a/b tubes as supplementary lighting would help to improve the stock a lot . Your plants getting
some real sun would probably allow them to express the potential of that generation. You can easily
test this If you make a number of cuttings from a mum and grow half with sodium only and
supplement the other half with sun when you can, I think you will find quite a difference between the
two stones the more sat in the var the bigger the difference. Ot1.

TOPIC - The net is too cool
DATE - Sat Jun 20 15:21:58 1998
FROM - Spliff

After a quick 'Altavista' search on UV and cannabis I came up with a few
items that pertain to this discussion. Here is the first:

Pate, D.W., 1994. Chemical ecology of Cannabis. Journal of the International
Hemp Association 2: 29, 32-37.

The production of cannabinoids and their associated terpenes in Cannabis is
subject to environmental influences as well as
hereditary determinants. Their biosynthesis occurs in specialized glands
populating the surface of all aerial structures of the plant.
These compounds apparently serve as defensive agents in a variety of
antidessication, antimicrobial, antifeedant and UV-B
pigmentation roles. In addition, the more intense ambient UV-B of the tropics,
in combination with the UV-B lability of cannabidiol,
may have influenced the evolution of an alternative biogenetic route from
cannabigerol to tetrahydrocannabinol in some varieties.

TOPIC - Bingo
DATE - Sat Jun 20 15:27:39 1998
FROM - Spliff

How about this one:

Another stress to which plants are subject results from their daily exposure
to sunlight. While necessary to sustain photosynthesis,
natural light contains biologically destructive ultraviolet radiation. This
selective pressure has apparently affected the evolution of
certain defenses, among them, a chemical screening functionally analogous
to the pigmentation of human skin. A preliminary
investigation (Pate 1983) indicated that, in areas of high ultraviolet radiation
exposure, the UV-B (280-315 nm) absorption
properties of THC may have conferred an evolutionary advantage to
Cannabis capable of greater production of this compound
from biogenetic precursor CBD. The extent to which this production is also
influenced by environmental UV-B induced stress has
been experimentally determined by Lydon et al. (1987). Their experiments
demonstrate that under conditions of high UV-B
exposure, drug-type Cannabis produces significantly greater quantities of
THC. They have also demonstrated the chemical lability
of CBD upon exposure to UV-B (Lydon and Teramura 1987), in contrast to
the stability of THC and CBC. However, studies by
Brenneisen (1984) have shown only a minor difference in UV-B absorption
between THC and CBD, and the absorptive
properties of CBC proved considerably greater than either. Perhaps the
relationship between the cannabinoids and UV-B is not so
direct as first supposed. Two other explanations must now be considered.
Even if CBD absorbs on par with THC, in areas of high
ambient UV-B, the former compound may be more rapidly degraded. This
could lower the availability of CBD present or render it
the less energetically efficient compound to produce by the plant.
Alternatively, the greater UV-B absorbency of CBC compared
to THC and the relative stability of CBC compared to CBD might nominate
this compound as the protective screening substance.
The presence of large amounts of THC would then have to be explained as
merely an accumulated storage compound at the end
of the enzyme-mediated cannabinoid pathway. However, further work is
required to resolve the fact that Lydon's (1985)
experiments did not show a commensurate increase in CBC production with
increased UV-B exposure.

TOPIC - Differences
DATE - Sat Jun 20 15:54:02 1998
FROM - Spliff

UV A : 320 - 380nm Used for UV Curing, Non Destructive Testing &
Inspection.
UV B : 280 - 320nm Used for Suntanning.
UV C : 200 - 280nm Used in Dermatology.

TOPIC - Brief excerpt
DATE - Sat Jun 20 19:07:50 1998
FROM - Lady J

"The MV (mercury vapor) lamp produces more UV-A, violet and blue light
than any other type of lighting source commercially available. Cannabis
responds to the intense violets and blues of the murcury vapor lamp by
producing dark, almost bluish green leaves. Stalks grow strong but not
straight and sort of zigzag between short internodal lengths. Side-shoot
development is extensive, as is the formation ofresin glands on calyxes,
bracts and larger associated leaves. Poetency is very noticeably increased
when compared to clones grown under other hid lamps. Plants also
rejuvenate faster under mv lamps."

Just part of an excellent article by Owl(one of my fave growers).

Peace

TOPIC - uv=b
DATE - Sat Jun 20 19:27:55 1998
FROM - Lady J

here's a little info:

7. IMPACT OF UV-B ON PLANTS AND ANIMALS

UV-radiation has long been known to be damaging to life; indeed this quality
is being employed increasingly for the disinfection of water and for the
mutation of
microorganisms for laboratory experiments . UV-B affects plants and animals
by modifying both their biological and chemical environment. Damage may
occur in a
number of ways, including the direct destruction of the genetic material
DNA, deactivation of enzymes, disruption of membranes and other cell
structures and the
generation of highly reactive chemical agents known as "free radicals".

Although biological repair mechanisms exist, mutations may remain as errors
in
the repair processes. In addition, the repair mechanisms themselves may be
deactivated by high UV doses. The interaction of all these processes can
lead to a
variety of adverse effects on plants and animals. Many effects are sub-lethal,
may
interact with other factors and may, therefore, be very difficult to attribute to
UV-enhancement specifically.

Effects on plants in the sea, in freshwater and on land are of fundamental
importance because of their position at the base of all other food chains. By
nature,
plants have evolved to maximize the surface area they expose to sunlight, but
consequently their exposure to damaging UV-radiation is also increased.
Elevated
UV exposure can cause temporary or irreversible damage to photosynthetic
apparatus (including the bleaching of the pigments which trap the sun's
energy), to
processes of cell division and growth regulation, and to the composition and
replication of genetic material. Consequences include a reduction in growth
yield,
changes in levels and effects of plant hormones and alteration of periods of
dormancy, flowering, etc.
UV-B IMPACTS ON TERRESTRIAL ECOSYSTEMS

Increases in UV-B radiation:


Alter soil quality and the soil ecosystem;
Decompose soil litter;
Influence plant growth;
Influence plant life cycles including timing of flowering, leaf-drop,
dormancy and death;
Alter biogeochemical cycling of carbon, nitrogen, etc.;
Affect susceptibility of plants to disease, drought, temperature and
pollution;
Modify the distribution of species within an ecosystem;
Disrupt the terrestrial food chain;
Alter inter-species competition for food, light and space;
Damage eggs and larvae of terrestrial fauna.

TOPIC - ultraviolet
DATE - Sat Jun 20 20:06:13 1998
FROM - casamere

tom flowers has a bit to say re uv from his flower forcing book:

Marijuana is thought to be indigenous to foothill areas with elevations of
1500-2500 feet [where there's high uv levels]. Many experienced growers will
tell you pot grown at these elevations will be the most potent - up to 20%
more potent than the same variety grown at sea level.

Growers use two or more 20 minute UV light treatments during the day cycle.
Most [tanning] UV lights have timing units. [small face-tanning lights for
400w, full body tanning systems for 1000w areas. used tanning lights
supposedly available cheap]

If you have to be in the growing area wear sunglasses that filter out UV light
and a hat. The small amount of UV-b radiation these lights produce can do
heady things to your marijuana. Don't get carried away though, the object is
not to get the plants to glow in the dark.


Posted by Frenchie on January 07, 1999 at 17:08:06



All these new strains are made with kick ass lightning, there are no seeds breedders that are using fluo lightning so
the plant after regenerating with so much light all his life tend to include this trend in his genetic pattern. They
don't breed seeds for low light level YET>
There are some older strain like NL that work well under low lightning.
POTENCY> Metal halide coated cooler than sunmaster warm but the blue spectrum does some tricks with
potency.
let's say we talk about ordinary Northen light strain.
I did always found a high level of CBD and CBN in NL when grown under to much red CRI. I think that since the
resin is there to keep the flower from drying (natural no) it must make sens to keep the leaves alive and feeling
well for a longer period so that the leaves can produce that thick enveloppe you need to keep those resin glands
from oxidysing ( ouf) The blue spectrum will work on the resin glands to produce THC . Forrest of dreams.......


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...



On Sat, 22 May 1999 16:25:56 Oldtimer1:


uvb, forget blacklight bulbs or uvc ozone types. The following was posted by nc a while back with some Phillips cat numbers. If you can't get that type add one or two tanning tubes to your cloning bench lighting.
++++++++++++++++++++++++++++++++++++++++++++++++

DATE - 09/27/98 10:49:09
FROM - ncga
TOPIC - UVB

Wow nice work guys buy you need a biy of help .. Below is the research I did two years ago


TITLE The positive or negative effect of UV-B light on flavanoid production or other aspects of plants.


OBJECTIVE

To identify if UV-B light has a positive effect on some plant life. To determine at what point there is a diminished return. There have been some reports as to the positive effects of UV-B light in the increasing of flavanoids. These articles have been very vague in there description of results with no mention of controls or approach.

APPROACH

A controlled camber will be used for observation. The observations will be conducted in the floral stage of
development. The plants will be grown under artificial lights. The lights used in this enclosed chamber are as follows. 1 400 watt metal halide, 1 90 watt low pressure sodium, and two 23 watt cool white flourescent bulbs. The chamber has a total area of 8.9 cu.ft. The chamber is enriched with CO2 every hour. The regulator is set at 12 CFH (this is only a visual reading on the gage with a +/-5%) and is injected every hour during the growth period. The chamber is vented for 10 minutes prior to the injection of CO2. The temperature is held to a maximum of 87 degrees during lights on and a minimum of 45 degrees
during the lights off. The UV bulb used is a Phillips F20T12/UVB73. The bulb will be placed in a Lights
of America 20 watt light strip. The bulb and cover were removed and a 20 watt bulb replaced with the UV-B bulb. The fixture was placed in the top, upper front of the chamber. This is the best location to prevent blocking of the 400 watt MH or the LPS lights. There is no reflector on this fixture. The plants have a distance of no more than 15 inches from the bulb. The plants will have an introduction to the UV-B gradually and at timed intervals during the light on periods. This will start with one to two minute on periods for a total of four days. This will be increased to 12 to 20 minutes on times for a total of 2 hours and 15 minutes. This will be divided into 8 total on cycles. The timing cycle is accomplished using an X10 computer control system. Limitations in the timing system is a min of 1 min on cycle. The other limitation is the increases are done in three stages with three separate timming programs to written. The nutrient level will be 28 CF (1800 ppm ) with two parts GH nutrient Bloom formula.


OBSERVATIONS

After 3 years of testing 4 crops with and 3 without UVB I have reached a conclusion. This conclusion is only based on my research and needs validation from other are needed to be definitive or conclusive.

The bulb should be replaced every year. There seamed to be some drop off in the results after the first year but the results were still better than without UVB. I noticed that some plants had a hard time acclimating to the UVB at first these low tolerance plant exhibited a lot of leaf "Curl or sunburn when introduced to the UVB however the younger leaves quickly adapt to the UVB light. It is important to introduce the plants at a young (short) age so a most of the plant is exposed over a long period of time . The results are not as prominent over the entire plant and is less noticeable. In other words a plant started with most of it exposed over its life to the UVB. The lower shoots if exposed when young will have more resin on them than those that were not exposed at a young age.

As to Flavanoids. The research that I did in 1994 about this hormone convinced me that it has no connection or very little influence on resin production or aroma. The closest correlating condition is that aroma has as much to do with nutrient level or even the nutrient used. This is reflected mainly in "original" or harvest odor. Resin production is not related to Flavanoids.

CONCLUSION

In a controlled environment the addition of UVB light at the rate of 20 watts per 9 sq ft would seam to be the amount need to duplicate these results. Also of note the plants can outproduce the outdoor plants in overall resin production . This is based on one out door test site.


QUESTIONS

UV Light research

Re: Fact sheet about calculations and specs

15 watt UV 17 * inches long requires standard 15 watt flourescent ballast

Coverage area 300 liters

30 watt light is good for 500 liters

Conversion cubic inches (divided by) 1728 X 18321 (divided by) = liters

20 & 40 watt bulb is the only ones that work mostly in the UVB range they also use a standard ballast. Have a spectrum of 295 to 320 cost of 20 watt bulb is $40.00 (min. Order is $50.00).


Source for bulb Universal Light Source PO Box 426200, San Francisco, CA 9412

What type of material is transparent to UVB light? - Only Quarts base material and very few synthetics

How broad is spectrum compared to FS 40 bulb? - The spectrum is the same.

ncga







TOPIC -
DATE - 19:53:41 9/10/99
FROM - cedartop

vic, this might be a dumb one, but why did you put your group under the uv light?


TOPIC -
DATE - 04:54:47 9/11/99
FROM - oldtimer1

cedartop There is a lot of evidence that the development of the psychoactive substances produced by cannabis are
directly related to exposure over generations to uv radiation. Thc is one of the most effective uv filters known to man,
what better way to protect the seed embryo! Historically it is well known that the plant looses the complexity of thc
production over several generations when grown under less extreme conditions. ie if you take seed from the Himalayas
to England and grow under glass it only has a 1/5 of its original potency after 4/5 generations, the glass filtering out
most of the little uv we get here. So a few breeders are working with uv to try and reverse some of the degradation to
seed stocks that has happened with breeders using just sodium lights. Also I suppose to prove if the suppositions are
true! it is going to take several generations to see big changes and prove it one way or the other, but from my
preliminary dabblingís Iím pretty convinced, we will see.

Vic yes they came from sag they were made autumn / winter 97 / 98!

Budm If you are out there give us a sign please!!!!!!!!!!

All the best Ot1.


TOPIC - Evolutionary Time Frames, UV Light & THC
DATE - 07:12:19 9/11/99
FROM - Soul

Oldtimer1_~ High mate, don't get me wrong, but I want to challenge this idea of yours. Your hypothesis that cannabis
evolved to produce greater THC levels as a defensive reaction to greater levels of UV light exposure seems sound to
me. It's the conclusion you're drawing that bothers me:

You've observed the plants decline in potency over 4/5 generations. But is this occurring while the original generation's
clones continue to maintain their potency? Even if so, that cannot be definitively linked to their UV exposure ALONE
and it's much more likely to simply be due to breeding.

Have you considered the length of time evolution takes? It seems to me, the degree of evolution of species to an
environmental variable cannot be detected in so short a period as 4/5 generations. The particular example you're
interested in is the correlation of THC production to exposure to UV light...that takes thousands, or millions of years.

Your suggestion that the UV exposure is responsible for THC levels in cannabis grown indoors dropping over the course
of a few generations shocks me. I would put the blame for the decline in THC on the UV exposure itself - not the effects
of "evolution" over a few generations. Do you see what I mean? The plants are far more likely to be responding to the
ACTUAL UV exposure during their own lifetime, than the lifetimes of their forefathers.

I submit that THC production is simply directly proportional to UV exposure while growing...with a genetic maximum
level specific to each strain.

The test of this theory would compare the THC production of first generation Himalayan cannabis grown outdoors, to
clones of the same plants grown indoors under typical MH & HPS lamps, and a third group grown indoors with
additional UV.

I believe that increased UV exposure during flowering would raise resin production (easily observed) at the very least,
but testing for increases in specific cannabinoids would be more complicated, albeit more FUN

Gentlemen - I yield the floor.



TOPIC - UV
DATE - 09:21:14 9/11/99
FROM - Vic High

Soul, please email me sometime, I lost your email addy.

Thanks for the challange, it gives me reason to take the time to explain further Basically, under non selective
pressures I agree with your point 100%. However, artificial selective pressures are at play here. Also, I agree, simply
creating your seeds under high UV conditions will have little effect on future generations, you will just get more potent
seedy buds. You need to use the UV in your selection process, this is where change can occur. My argument will
make a few assumptions that are open for challange though, hehe.

First, lets consider THC's role and effects on a plant's overall health. It can be good or bad for a plant depending on it's
location, for example, a low THC plant growing in a high THC environment is going to spend alot of energy repairing
tissues damaged by UV. Therefore, it won't be able to be as vigorous as other plants with high THC. However, a high
THC plant growing in a low UV environment will waste alot of energy producing THC, energy that could have gone to
faster growth. Therefore, vigour could represent opposite traits depending on the environment.

And the most vigourous tend to be what we and nature selects for. In our case, our selection pressure are much more
extreme because we work with much smaller population sizes. What would take nature hundreds of generations, we
could do in half a dozen or less. Cannabis has enough genetic variation to allow this. Take haze for instance, how
many are the bomb, and how many are dogs? By purely selecting the bombs each round (males included), it shouldn't
take long to clean up the line and make it predominately bombs, less than six generations is my guess. However, we
like to select for more than potency, hence complicating the issue, hehe. But how do we select the male's that are the
most potent? Especially with our small population sizes?

Well first lets talk about the effects of population size and selective pressures and how they work together. It's common
thinking that to improve a seedline from generation to generation, you need to reserve only the top 10% of the
population for breeding. For faster results, make that the top 1%, the smaller the number, the faster the results.
However, the size of your breeding population is also important to maintain vigour. The smaller the breeding population,
the more likely you may end up pairing up lethal recessive alleles. So you end up trying to strike a balance between
keeping your breeding population a decent and healthy size and placing as much selective pressure on selecting your
breeding population. A larger population size would have solved DJ Short's blueberry problems, it's lack of vigour and
deformed growth. IMO, of course, hehe, only DJ knows the truth, hehe.

Space is usually our limiting factor, you can only select from so many. This is where my UV ideas come into play, to
allow me to select from a larger population. Two flats of seedlings can take up as much space as one or two adult
plants. My flats hold between 48 and 72 seedlings, depending on cube size. My assumption is that if I can grow the
seedlings under high UV, those seedlings with the most THC should be the most vigorous. And to top it off, the biggest
plants put themselves at a bigger risk by growing closer to the UV source! So now, when you move from the seedling
flats to the 5" pots, you save only the best "looking" 10%, hard to select based on anything else at this point. You
should be able to further your selection in the 5" to 6" pots based on other selection criteria such as powdery mildew
resistance, for example and reduce your population by another 50% before moving to the final growing medium. Take
back up clones of each and then flower them out, steadily removing any undesireables and doing taste tests, hehe. By
about halfway through flowering you should be down to your top 1% of the population. All the while, exposing the plants
to high UV, giving those with the most THC a selective advantage.

It would be fun to back up these ideas with GLC data, but my connections are not that great, and I haven't found the
equipement that I could buy for my persoanl Lab, haha. Anyway, I left lots of holes in my idea for further discussion or
challanges if anyone wishes


TOPIC -
DATE - 13:40:47 9/11/99
FROM - oldtimer1

Hi Soul a lot of what you say I agree with but as our government learned in the past cannabis adapts to its environment
very quickly indeed and it cost them a lot of money. When we were a sailing nation hemp had been grown on a large
field scale in Norfolk for the admiralty for several hundred years. In their wisdom they decided labour being 1/100 in the
middle east they moved production to one of our protectorates. There was no other cannabis cultivated within the area
and the first year crops were the normal single whip 12 to 15 ft long bast fibre plants of home within 4 years the plants
had adapted to a short branched 5 to 6 ft plants were already producing quite a lot of resin which clogged the
machinery and the fibre quality was inferior for making sail cloth or rope also the fibre yield dropped considerably. They
had to produce seed here and send it out and that worked out satisfactory but costly and eventually abandoned hemp
production round the med. As I have mentioned before JW Fairburn did light/potency research in the UK in the 60/70ís
and to go with your theory found that Thai grown from seed taken from samples of impounded weed produced little thc
under glass. But when given supplementary uv produced about 3.6% against .02% without. Now while this is quite
reasonable considering they were leaf samples as Thai would never flower properly here. That goes along with your
supposition that if it is in the genetic make up uv will help the plant produce more complex forms of thc. I had not
meant to go into detail as we have been through a lot of this on this page before. But the experiment have been done
many times before both here and even more so in the states! We should learn from what has gone from before not keep
trying to reinvent the wheel. Your own government did loads of research via university grants in the past and the change
period from a high thc low cbd to low thc, high cbd is about 4 to 5 years taking a southern variety and growing it in the
northern areas! We are not talking about any selection here just grown field scale. Interestingly when taken back to the
original environment they revert to the high thc low cbd form over a similar period. Where as a type 3 fibre plant as i
stated above while adapting in form rapidly and while producing a lot of resin only adapts its thc production upwards
very slowly indeed. Most of the varieties grown by us now are a mix of type 1 and type 2 plants mostly looking like type
2 [high resin hash production]. They were originally made in the states! It gave plants that would finish early enough in
the southern states. As people in the northern states found they could grow them just as well under HIDís newer more
compact varieties were developed and I believe they were very potent from the samples i tried at the time, things like
northern lights, bigbud and skunk#1. They were drawn from genetics grown in the south where there is real sun! Now
this is a supposition, but all these earlier breeders used big metal halides and they do give off useful amounts of uv! I
suspect these early varieties had a good proportion of thc in relation to cbd. In Holland at this time they had been using
supplementary lighting under glass to grow tomatoes and flowers for a while using the lately developed son t plus type
of sodium lamps! All the wonderful varieties were taken from the states and the seed industry started to develop in
Holland and of course they took on board the local growing methods lots of small highbay sodium lamps but in rooms
instead of under glass. In my opinion the quality has been going down ever since! I have tried nearly every thing grown
in Holland, I have grown some of both yours and Vicks varieties and believe me they stand above any thing you can
buy in the dam! I suspect this is because both of you use a mix of halide and sodium which doesn't happen in Holland.
By the way this doesn't mean they cant be improved hehe.
I donít know what Vic is doing but If I was him I would be subjecting my seedlings and breeding stock to uv the
survivors having the most adapted genes, a fast track back to the high thc combinations. It is unlikely that there will be
any type 3 genes in the mix and given a few generations hopefully he may have some killer combinations, but only time
will answer this I look forward to seeing the results! Soul Iím no scientist nor geneticist, a gardener yes! I just like this
plant a lot, Iíve grown it for over 30 years, Iím appalled at what has been happening in Holland breeding wise. To me it is
down to you boutique growers to take it to another level! DP say in their catalogue that blueberry has been tested at
19.5% thc, well that is all bullshit to me, do you know that the strongest Colombian ever seized by your government
tested 9.7% thc. Iíve smoked both and to me the bb wouldn't be in the running!

All the best Ot1.


purchased UV tubes are:

Philips (Made in Holland)
TL40W/12 RS UV-B Medical



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A preliminary investigation (Pate 1983) indicated that, in areas of high ultraviolet radiation exposure, the UV-B (280-315 nm) absorption properties of THC may have conferred an evolutionary advantage to Cannabis capable of greater production of this compound from biogenetic precursor CBD. The extent to which this production is also influenced by environmental UV-B induced stress has been experimentally determined by Lydon et al. (1987). Their experiments demonstrate that under conditions of high UV-B exposure, drug-type Cannabis produces significantly greater quantities of THC.

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Dr. Penguin said:
UV-B RADIATION EFFECTS ON PHOTOSYNTHESIS, GROWTH and CANNABINOID PRODUCTION OF TWO Cannabis sativa CHEMOTYPES

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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.

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coda said:


I've been pretty intrigued by this theory.  Apparently UV light in the early stages of flowering encourages heavy, and early, trichrome formation.  I've seen a few side by side grows and the results are pretty interesting.  There is definitely a difference between using a UV and not.  However there isn't too much info on using UV light in flowering, i do know it's detrimental to your grow when drying your buds.  Also UV light is nasty stuff to work around, you need to turn the lights off when working in the room and you can't look directly at them (unless you want to go blind).

A big upside to this theory is that the lights are cheap and easily found at pet stores and online.  Also they don't require massive amounts of power to run so your electricity bill is not really affected by running them.  They're also small and versatile so you can fit them in a lot of spaces if your grow room is getting cramped.  Once i get setup in my new place i'll be adding one or two of these lights to my setup to see how well they perform.

Also, FYI, MH lights put out some UV rays so if you have a MH ballast and bulb you can achieve similar results by running it alongside your HPS.

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Sirius said:
I happened upon some more discussion about UV-B on another site and I thought I'd post here for our collective another more expensive bulb, complete with ballast ($75). Its more expensive than the common pet shop UV bulbs, but it claims to produce similar amounts of UV-B light as the sun, when its at the right distance, and there is actual data on the UV-B output. They also assert it produces very little heat. My friend doesn't have any intention of trying it out, at least anytime soon, but I thought I'd throw it out there since it seems more capable of producing UV-B light at levels resembling natural sunlight (from which location on the planet I'm not sure though ). I'll keep an eye on the posts of the guy who is planning on using it on a mover and see what kind of results he gets.

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