UVb an experiment - Cannabis Forums Message Boards - Medical Marijuana, Cannabis Club, Dispensary, News

oldmac · #1 (**permalink**) Jul-28-2009, 14:04

Quick background: I have been using UVb supplemental lighting for many years now and have always thought it added to the finished product in a couple of ways. I had never promoted it's use on these boards because I felt it was dangerous and had real potential to harm people. That changed a few months back on the other UVb thread, and I came out of the closet in strong support of it's use. Well some here who's opinion I respect (like Weezard) held the opposite view and those discussions led me to the fact I had not done any experiments in a long time trying to compare it's effects.

So I decided to do back to back runs, with and without and to try to see, observe and quantify the differences. I decided to use my personal grow to do this since it is well dialed in and consistent, and I have been using UVb as supplemental lighting. The other grow I'm involved in, I could not seperate some UVb in the bloom room cause of it being built into some lights, like the TI problooms.

Strain is WhiteRhino, grown as SOG size plants (finish @ abt 18" tall) in 4" RW delta blocks in a GI Grow rotating garden. The light source is a homemade LED/T5 hybred; the LEDs consist of 240 red (635nm) Cree's driven at 650ma giving 1.75w/ea for a total of 420 watts and 8 2700K 2' T5s overdriven to VHO levels of 40w/ea for a total of 320 watts. All together it's 740 watts of light, plus power supplies and fluro ballasts. All of this is mounted on a 4" octogon aluminum extrusion and mounted inside a 6" boroscilicate glass tube that is ducted for air cooling. There should be no UVb transmitted thru the glass, if there is any from the T5s.

I started this last run with out UVb on June 7th (full moon) and today marks the 7th week (lost 2 grow days to power outage) they have been in flower.

Early observation:

1) I have always claimed that UVb adds to trichome production, but I have not seen a difference w/o UVb. The WR packed on the tric's just like before, much like white strains do, tric's solid on buds and leaves, some trying to grow on top of each other, often thought it was UVb but it's not. Based on this, and something I've seen in the other grow I must admit trichome production is more a product of genetic predisposition then UVb light influence. My first sorta surprise.

2) Second surprise (big one) is the leaves of the plant in this run are paper thin in comparison to previous runs. W/ UVb the leaves are much fatter and tougher, a very noticable difference. I don't recall reading anything about this, but it looks like UVb adds to the overall plant mass.

3) At this point of 7wks, I would expect to see trichome's that where clear with maybe 25% turning cloudy. Tric's are currently all clear, did lose 2 days so maybe that's the difference, not sure at this time.

So that's where I'm at right now, everyone is welcome to hang out while I wait and see what happens over the last week or so and I get to final finish and a taste test.

Question or comments on or off topic are always welcomed even encouraged.

.

Dogznova · #2 (**permalink**) Jul-29-2009, 13:03

Oldmac you have noticed some very interesting info on uv-b that IMO should be talked about..
This should be a great tread.. I think I know why your plants are ripening a little slower without uv-b.. Give me a little wile and I will post my reasoning LOL.. Great tread..

Dogznova · #3 (**permalink**) Jul-29-2009, 16:46

Oldmac it's not the uv-b that is making your plants rippin faster it's the blue light associated with the uv bulb you are using. Let me explain.

Most of the cfl type of uv bulbs from (pet stores) omit in the low 300nm to about 400nm BLUE range. That low blue nm range has a fast Time Factor associated with it. So when you add let's say 3 hours of that fast blue nm light to your existing 12 hours of day light you are actually lowering your lights overall 12 hour Time Factor. If your current combined lights Time Factor was say at 4 (just an example) before you added the 3 hours of the fast 300nm to 400nm blue to the mix, now your lights overall 12 hour Time Factor will be around 3.8 ish or lower (just an example) but you get the point. The faster Time Factor day after day will speed up the flowering over time. The truth is.... Speed is one of the only good thing those bulbs offer and it's actually just the Blue 300nm to 400nm that has the speed. Also it's the blue spectrum that makes the leafs,stalks thicker not the uv-b. If you remove the uv from those bulbs and just use them as speed and a blue light source then they are ok. But if your using led's and T5's as your light source then chances are you don't want the thicker leaves because of light penetration issues. Light penetration issues will cause lower THC production by default. So the less blue the better if you don't want to produce thick leaves. IMO

Personally I get most of my speed from far red. Far red has the fastest Time Factor for plants but gives no useful bulk and will cause stretch in the early part of flowering. The strain I work with only likes the low fast Blue nm in the first two weeks of flowering and I like to use 420nm. Not much uv in these lights but good speed.. Any longer then two weeks and the added blue starts to make the flowers way too leafy for me.... But the blue helps keeps the early flowering stretch down and the speed up (red 630nm to 660nm will also keep strech down BUT the speed (time factor) is to slooooow for me)...

My point is.... When everyone figures out that speed (300nm to 400nm) is the only thing good about these lights. The next step will be seeing that the good (speed) don't out way the bad (uv-b). There are much better ways of getting the plants clock moving faster IMO.

More to come soon.

crabbyback · #4 (**permalink**) Jul-29-2009, 18:15

This looks like fun. I'm in.

oldmac · #5 (**permalink**) Jul-29-2009, 19:17

Hey Dodznova,

I've seen you martain-nite growers, most recently SalMayo reference the time factor of various lights. I have not been able to find anything about it in the science literature dealing with it...but I'm still looking.

The T5's at 2700K have seemed to be about the same as the full spectrum T5s they replaced, they produce a fair amount of blue and it is the only source of blue present. I need to look at a spectrum graph to see what the T5s produce tho. Orignally this light was to be red leds and whites but the white LEDs I got did not output any usable blue and they failed. I backed into using T5s with just red LED and they worked great, and is why I've tried other Led/T5 combos. The current TI pro-blooms/T5 in my partnered grow have not been successfull, not enough mixing of the lights; center sees only LED outer rows just T5 and only some mixing in between. Plus the pro-blooms are pretty complete on thier own.

Interesting, look forward to further this discussion.

oldmac · #6 (**permalink**) Jul-29-2009, 19:27

Quote:

Originally Posted by crabbyback

This looks like fun. I'm in.

Always glad to see you Crabby. This is a fun experiment to me, falls into a "shit & giggles" type of thing, got nothing to really lose by trying it. (or not trying UVb)
It is going to push me back to light theory 101 and make me start to look at wavelenghts again, just what I need as I design another light.

Weezard · #7 (**permalink**) Jul-29-2009, 20:53

Quote:

Originally Posted by oldmac

Always glad to see you Crabby. This is a fun experiment to me, falls into a "shit & giggles" type of thing, got nothing to really lose by trying it. (or not trying UVb)
It is going to push me back to light theory 101 and make me start to look at wavelenghts again, just what I need as I design another light.

Beeg Mahalo fo' dis, OM.

1) I have always claimed that UVb adds to trichome production, but I have not seen a difference w/o UVb. The WR packed on the tric's just like before, much like white strains do, tric's solid on buds and leaves, some trying to grow on top of each other, often thought it was UVb but it's not. Based on this, and something I've seen in the other grow I must admit trichome production is more a product of genetic predisposition then UVb light influence. My first sorta surprise.

Surprised me too, at first. Then I got to thinking about it.

2) Second surprise (big one) is the leaves of the plant in this run are paper thin in comparison to previous runs. W/ UVb the leaves are much fatter and tougher, a very noticable difference. I don't recall reading anything about this, but it looks like UVb adds to the overall plant mass.

As for the thick leaves, I'll dig up the reference for ya, but basically the disk shaped cells that process light lay flat in low light to gather enough energy.

When overlit, or UV cooked, they turn edge-on to the light to present a lower surface area and that's what "thickens" the leaf.
Pretty neat actually.

Nudder week or two for da bake-off.
Unless UVb has a very positive catalytic effect on potency, I'm done with it, yah?

I'm bettin' that the dark spell did set you back about twice as long as it actually lasted.

Also, I found that my buds are ripe when mostly cloudy under leds.
Rusty trichs are few and far between without shortwave radiation damage.
My first led harvest got senile while I waited for the dang amber.

Mahalo again for helping us sort this out.

Weezard

oldmac · #8 (**permalink**) Aug-02-2009, 14:46

Yo' weezard, I ain't done with 'ya yet. This experiment is not concluded plus I might need your thoughts on light wavelenghts.

As to a two day set back, I believe that's all there is, they still got battery backup fluros (12v dc camping lights) plus my far red incandescent trigger lights. So thier schedule was not disrupted at all, just not enought light to grow for those two days.

I found some info on the leaf thickening, a result of UVb for sure. But in this case they are flowering in a rotating garden and the plant auxins are screwed up, so the plants don't know which way is up or which direction the light is so I don't think it's the leaves turning edgewise to the light.

As of last nite, trichomes are abt 20% cloudy the rest are clear. So at least that's heading in the right direction.

Weezard · #9 (**permalink**) Aug-04-2009, 05:43

Quote:

Originally Posted by oldmac

Yo' weezard, I ain't done with 'ya yet. This experiment is not concluded plus I might need your thoughts on light wavelenghts.

Anyway I can be of service, do not be shy.

As to a two day set back, I believe that's all there is, they still got battery backup fluros (12v dc camping lights) plus my far red incandescent trigger lights. So thier schedule was not disrupted at all, just not enought light to grow for those two days.

I found some info on the leaf thickening, a result of UVb for sure. But in this case they are flowering in a rotating garden and the plant auxins are screwed up, so the plants don't know which way is up or which direction the light is so I don't think it's the leaves turning edgewise to the light.

You missed me, my friend.

This effect has naught to do with the leaves themselves.

This "edging" happens on a cellular level.
The microscopic thingies that process light within the cells are shaped like disks, lots of them.
When light is weak, they lay flat to absorb more of it.
Then, the leaf feels thin.

When the light is too strong, or a danger, these disk shaped cells slide into a "rool-of-coins" shape that presents only the edge of the cells and protects them from damage, but this makes the leaves feel thicker.

I'm way too baked to even search for the original paper that details this effect.
When I'm able, I'll dig it up for you.
It's a fascinating read and one of the things that made me question the value of UVb for Cannabis.

As of last nite, trichomes are abt 20% cloudy the rest are clear. So at least that's heading in the right direction.

Added some snaps to my album that you might enjoy.
Couple led grown "droolers".

Aloha, OM

Weeze

Weezard · #10 (**permalink**) Aug-04-2009, 07:13

A Granum of Thylakoid disks is what I meant to say.

chloro1.jpg
See;

Photosynthesis 1

For more fun stuff.

Nonsense!
Least I could do!

Aloha,
Weeze

Rusty Trichome · #11 (**permalink**) Aug-04-2009, 08:49

I totally agree that the pore spacing is genetic, but am still not convinced the UV light is as damaging to plant growth and development as is stated in some responses. After all...for the past 10,000 years cannabis has been subjected to natural sunlight, which has what ammounts to dangerous levels of UV light.
I'm more inclined to believe that a plant has, after all of that time, found a way to either utilize the light to it's benefit, or has developed at the very least a (chemical) tollerance to it, and either way...the results are inside of the trichomes.

What are the trichomes for...?
Trichomes - the source of Magic
Trichomes and you

If indeed the trichomes are a defense against uv light, what does the uv light do to the interaction between the cbc, cbn, cbd and thc? What does lack of UV light do? What does early exposure to UV light do to the plant's metabolism and self-protection habits? (both immediate and long-term) What does restricted-exposure to UV, over many generations, do to the plant's genetics? Is this why some strains react to UV light in flower, and some don't?

A few weeks ago I had a visit from a neighbor's dispensary provider, (a No. Cal. grower) and he had a look at my set-up's. Mentioned I might want a little more ventilation in my flower shed, (was in the high 90's inside the room at the time) and that I should move my UV light from my flower room to my veg room, to accelerate my vegetative growth. He tried very hard to make clear that UV light is more beneficial in veg, than in flower. If it's good enough for a commercial grower with a final product as fine as his...I will be trying it out on my next run.

He was in a hurry, so I didn't get to really pick his brains in-depth. His GPP, TrainWreck and OG Kush are tasty and will make your legs stop working. Been hoping for seeds, but my neighbor has found none in her stock, and I've only seen the guy that one time.

This is evidence of nothing, but adds another dimension to the topic.

Rusty Trichome · #12 (**permalink**) Aug-04-2009, 09:33

Too late to edit this in, but a while back I came across this:
Chemical ecology of Cannabis

Ultraviolet radiation
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.

This CBC pigmentation hypothesis would imply the development of an alternative to the accepted biochemical pathway from CBG to THC via CBD. Until 1973 (Turner and Hadley 1973), separation of CBD and CBC by gas chromatography was difficult to accomplish, so that many peaks identified as CBD in the preceding literature may in fact have been CBC. Indeed, it has been noted (De Faubert Maunder 1970) and corroborated by GC/MS (Turner and Hadley 1973) that some tropical drug strains of Cannabis do not contain any CBD at all, yet have an abundance of THC. This phenomenon has not been observed for northern temperate varieties of Cannabis. Absence of CBD has led some authors (De Faubert Maunder 1970, Turner and Hadley 1973) to speculate that another biogenetic route to THC is involved. Facts scattered through the literature do indeed indicate a possible alternative. Holley et al. (1975) have shown that Mississippi-grown plants contain a considerable content of CBC, often in excess of the CBD present. In some examples, either CBD or CBC was absent, but in no case were plants devoid of both. Their analysis of material grown in Mexico and Costa Rica served to accentuate this trend. Only one example actually grown in their respective countries revealed the presence of any CBD, although appreciable quantities of CBC were found. The reverse seemed true as well. Seed from Mexican material devoid of CBD was planted in Mississippi and produced plants containing CBD.

Could CBC be involved in an alternate biogenetic route to THC? Yagen and Mechoulam (1969) have synthesized THC (albeit in low yield) directly from CBC. The method used was similar to the acid catalyzed cyclization of CBD to THC (Gaoni and Mechoulam 1966). Reaction by-products included cannabicyclol, delta-8-THC and delta-4,8-iso-THC, all products which have been found in analyses of Cannabis (e.g., Novotny et al. 1976). Finally, radioisotope tracer studies (Shoyama et al. 1975) have uncovered the intriguing fact that radiolabeled CBG fed to a very low THC-producing strain of Cannabis is found as CBD, but when fed to high THC-producing plants, appeared only as CBC and THC. Labeled CBD fed to a Mexican example of these latter plants likewise appeared as THC. Unfortunately, radiolabeled CBC was not fed to their plants, apparently in the belief that CBC branched off the biogenetic pathway at CBD and dead ended. Their research indicated that incorporation of labeled CBG into CBD or CBC was age dependent. Vogelman et al. (1988) likewise report that the developmental stage of seedlings, as well as their exposure to light, affects the occurrence of CBG, CBC or THC in Mexican Cannabis. No CBD was reported.

Weezard · #13 (**permalink**) Aug-04-2009, 20:11

Good to see ya R.T.

2 great post in a row!
Mahalo nui!
I owe ya one brah.
Dis bud's for you.

Aloha,
Weezard

headshake · #14 (**permalink**) Aug-04-2009, 20:16

subscribed! now i have to go back through and read it all!

-shake

Dutch Pimp · #15 (**permalink**) Aug-05-2009, 09:26

when y'all reach a conclusion...call me...

oldmac · #16 (**permalink**) Aug-05-2009, 10:01

Hey Weezard,

Thanks for clearing up the confusion I had about the leaf CELLS turning on edge. I really thought you where trying to tell me the leaf edges were turning thier edges to the light, and I really did not see how that was possible. The thykaloid disk packs makes sooo much more sense now. Thanks for that.

I found reference in a Rutgers' paper to an increase in "green leafy plant material" due in part to high levels of light activivity or "increases of UVb light", mentioned in a paper dealing with CO2 utilization.

Yo Rusty,

Big thanks for the posts, there is little doubt in my mind that trichomes are where the magic happens and are not designed as plant defense mechanisms, but are in fact designed to collect and condense light (specifically UVb) and act as cellular factories to produce THC.

Your friends idea of using UVb during veggative growth is most interesting of all from a usefullness angle. It makes sense that since the cannabiniods or at least thier percursors all start off during the veggative stage, UVb may play a role earlier in the plants developement then I had thought. I need to do some more reading (right here even to start) and digest this some more.

oldmac · #17 (**permalink**) Aug-05-2009, 10:13

Quote:

Originally Posted by headshake

subscribed! now i have to go back through and read it all!

-shake

Hey Shake,

This isn't so bad to read thru, at least this thread is young enough that I haven't gotten the chance to go too off topic.....yet.
Opens up the interesting area of internal reactions of the plant, at a cellular level.

Hello Pimp,

We will certianly let you know the out come when we reach some sort of conclusion.

Rusty Trichome · #18 (**permalink**) Aug-05-2009, 10:46

I've got some clones rooting, so hopefully I'll be able to do a sort-of side by side. (top and bottom) Will have to remove some bulbs from bottom (late veg) space to make 'em even-stephen, but if Farmer Bob's advice is correct, I might not miss the missing lumens.

Kinda off-topic...but this is my latest veg closet. Half clothes, half growroom.

The drip trays are lined with aquarium gravel, so I don't need drainage rocks taking up room in the pots, and makes transplanting a breeze. Clone tray cover is a sheet of plexiglass. Holds 12 clones. The plastic tray and bulb bases (outdoor security lights) are both from WalMart, UV light is in the bottom section. The shade cloth keeps the light from glaring off my computer screen. (and no signs of the bulbs melting it at all) Has an unlighted upper level (not shown) for a tub of just-planted seeds. (versatility)

Anyway, I guess we'll see how it goes.

SauceeMcGee · #19 (**permalink**) Aug-05-2009, 10:54

I find this fascinating. LED and advanced light technology have always come off to me as an intimidating read. I feel like I wouldn't know where to start reading to understand it all. Perhaps Weezard can point me in the right direction of a thread or something that would be a friendly read for an LED noob. I'm obviously not a plant idioit, as it is my major of study, I just have not had the light experience...

Thanks to all, I'll be keeping up with this one

SMG

Weezard · #20 (**permalink**) Aug-05-2009, 22:39

Kind of on topic.

Got some new snaps of led grown buds.
ledzard.JPG

ledbuds 2.jpg

led front sun backJPG.jpg

All UVb free from birth.
First taste indicates presence of active ingredient.

Aloha,
Weeze.

Horsemanrocks · #21 (**permalink**) Aug-06-2009, 00:12

Emmylou Harris does a song “Too far gone”.
OM, Weeze, Dogznova……I’ll never hear that song again without thinking of the three of you.
A caution to other viewers: An intervention would only provoke them…..just wait….In time, this too shall pass!

Y’all are too far gone,
Horsemanrocks….out!

Weezard · #22 (**permalink**) Aug-06-2009, 05:35

Quote:

Originally Posted by Horsemanrocks

Emmylou Harris does a song “Too far gone”.
OM, Weeze, Dogznova……I’ll never hear that song again without thinking of the three of you.
A caution to other viewers: An intervention would only provoke them…..just wait….In time, this too shall pass!

It shan't I tells ya!

Y’all are too far gone,
Horsemanrocks….out!

An' it's a one way ticket.

"I am not Granola" - Milhouse

Weeze,
Far-gone N. D.

oldmac · #23 (**permalink**) Aug-06-2009, 10:35

Hey Weez',

Your pot porn pics look good, finished product sounds quite tastey, you should taste the diamond I mined out of the 10 shivas skunks we grew out, got one dats goin' to be a killer. I also saw your updated albums, who says a square peg don't go into a round hole (bucket).

And Horse,

You just starting to see da boys put thier heads together here, to a few hardcore growers the science of light wavelenghts and there effects on plant growth can become a relegious experience of sorts.

.

oldmac · #24 (**permalink**) Aug-06-2009, 10:46

Quote:

Originally Posted by SauceeMcGee

I find this fascinating. LED and advanced light technology have always come off to me as an intimidating read. I feel like I wouldn't know where to start reading to understand it all. Perhaps Weezard can point me in the right direction of a thread or something that would be a friendly read for an LED noob. I'm obviously not a plant idioit, as it is my major of study, I just have not had the light experience...

Thanks to all, I'll be keeping up with this one

SMG

Maybe Weezard has a good source for this info, not sure. I got interested in it about 3 yrs ago after taking a horticulture course(s) at a community college. I was surprised that 660nm red light was heavily discussed and mentioned in the text books, plus the importance of 770nm far red. That's where I started and then searching for scientific papers that delt with the subject. A whole lot of research has been done, alot is not available tho cause it is directly related to proprietery interests by sponsoring companies.
NASAs LED stuff made me start to build (5mm diodes), use and experimernt, and I'm always still looking for more science.

oldmac · #25 (**permalink**) Aug-06-2009, 11:13

Quote:

Originally Posted by Rusty Trichome

I've got some clones rooting, so hopefully I'll be able to do a sort-of side by side. (top and bottom) Will have to remove some bulbs from bottom (late veg) space to make 'em even-stephen, but if Farmer Bob's advice is correct, I might not miss the missing lumens.

Kinda off-topic...but this is my latest veg closet. Half clothes, half growroom.

The drip trays are lined with aquarium gravel, so I don't need drainage rocks taking up room in the pots, and makes transplanting a breeze. Clone tray cover is a sheet of plexiglass. Holds 12 clones. The plastic tray and bulb bases (outdoor security lights) are both from WalMart, UV light is in the bottom section. The shade cloth keeps the light from glaring off my computer screen. (and no signs of the bulbs melting it at all) Has an unlighted upper level (not shown) for a tub of just-planted seeds. (versatility)

Anyway, I guess we'll see how it goes.

Nice setup Rusty, I always like to see shelves with multi use areas as they are the most space effiecent for indoor home growers.

Look forward to some more experiments and I think yours could be a good one. I know that Dogznova peaked my interest with the "fast blue" concept. I may try to do a run substituting UVb bulbs with some actinic whites. I realized in the one grow I use a super actinic white (435nm peak) for clones and seedlings 'cause it really helps with root production, and if we veg under the combo of 6500K fluros and that actinic the young plantlets stay short and compact. Plus another experiment I want to try is using some UVb during the vegative growth to see if there is an improvement. Only problem with that here in my personal grow, since I grow SOG, they are only vegged for 2-3 weeks, the time it takes to transplant the clone plugs and establish them into the delta blocks.

BTW, since I started this thread in the OP I clearly state on or off topic is ok by me.

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