Opinions needed

[Pam]

http://www.youtube.com/watch?v=IPcpt3Be28o

 

If you can manage to sit through the chemistry lesson Marijuana Man sounds somewhat convincing.

This was sent to me by one of my "Ask Granny" questioners. And I found it pretty interesting. Was wondering what all of you think?

[infotech1]

Sounds interesting, and is worth a shot.

Looks like you can get fluro tubes that will output uva and uvb from pet stores fairly cheap.

[pipeman]

Yeah he sounds convincing but I think the substance of his argument is very weak.

 

It is an 18 minute video and about the first 10 minutes is just the setup, a science lesson in the cellular makeup of trichomes. This is to impress you with his knowledge and give him credibility in your eyes. Then all of a sudden he makes a blanket statement that its UVB light that is the major catalyst for THC production. He never gives any reason or explanation for this, or even a hint at how he arrived at this conclusion.

 

He also made a number of other highly questionable statements. He said that high potency pot only came from regions of the world with high uvb levels. Of course it was the tropical region which had the highest UVB levels, but this region also has the highest light levels overall. What good reason does he have to think its the UVB specifically?

 

He gave no evidence of side by side comparison grows. The only example he gave was an uncontrolled comparison, where he said a grower took a clone and grew it in a different growroom (and a different grower) that had a uv light, and the bud that he grew was more potent than the original bud. There were many variables which changed when a clone is taken to a different grow room, to pick one variable and conclude that was the sole cause of the difference is very shoddy science. And the fact that this seems to be all that was needed to prove to "marijuana man" that uvb light is the key says something about his credibility doesn't it.

 

Towards the end of the video he makes a lot of random statements and almost becomes incoherent. I tend to think this guy is just trying to get his 15 minutes.

[Al B. Fuct]

Bang-on, pipeman. I've never seen anything credible which justifies adding UV light to an indoor grow.

 

I have researched, in some great detail, the spectral output of HPS lighting. While I've heard some particularly uninformed ppl say things like "HPS has no UV output," my findings are quite the opposite. HPS lamps DO produce UV, all the way up into the UVC region at 250nm, and they do so in similar proportions to UV in sunlight.

 

Now, as you say, whether plants derive any benefit from UV exposure at all, is highly questionable. Personally, I want to see the peer-reviewed paper from a uni with a good botanical science unit which has done a double-blind study proving UV has any effect at all on cannabis plants.

[Pam]

Thank you Pipeman and thank you Al! That's EXACTLY what I was trying to find out! I was more into biology than chemistry in school, and although I've read the book on Marijuana chemistry... it's still all Greek to me.

What struck me was that just as I was about to click him off he suddenly pops in with "UVB!" And so I continued to listen. My thoughts were that since I'm trying to reproduce the sun, the lack of UVB might be an issue.... but Al resolved all that. I had no idea that my HPS put out uvb as well as a and some c.

When I answered the question posed to me (before viewing the video since that came after my answer), I quoted Cervantes where he says there is no proof that UVB makes any difference at all and that he had seen a few comparison grows that also show no difference. After viewing it... well it did make me wonder, so I brought it here.

 

I also pondered the succulants and cacti that live in my daughters grass lizard tank. They seem to love the UVB light, and so perhaps there are some plants that might benefit but I don't think cannabis is one of them.

I do think I might put my some peyote and San Pedro in a tank (IF the seeds ever pop) with a "lizard light" just to see if there's any difference in that plants growth rate or potency.

 

Thanx again!

[SukonmiSkunk]

some one wrote a thread on the benefits of UVB light on here somewhere.. saying the same thing.. ive been growing indoors for nearly 20 years.. my first year of growing was done under MH lights.. they emit a fair bit of UV.. you can see that in the blueish colour they give off .. eveything i grew with them was very reasonable.. although they didnt completely fillout the bud, the end product was very smokable.. never had any complaints... since then ive been using HPS... and ive always thought the UV the HPS gives out was around the same amount.. but not as noticable because of the extra red and yellow spectrums... again.. since ive been using the HPS globes.. buds fill out a lot better... never had any complaints.. it still gets me shitfaced..

 

im not sure at all about the UVB light being the trigger for THC production... ive always gone with the notion that the % of THC is down to genetics .. in MJ botany he states the THC% is at its greatest when the plant has reach sexual maturity.. which is when the fibres are around 50/50.. from then the THC starts to diminish as the flower ripens... UV light is a major factor in the BREAK down of THC to CBD or CBN ... so i cant understand how the THC would "increase"... as the flower ripens..

 

all in all .. he does give a very good explanation on how the resin gland actually works.. i thought that was very interesting..

 

who really knows for sure he could be right on with his theory... just like Pman said.. he doesnt really detail how he came to this conclusion... taking a clone and growing it in another room by another grower doesnt prove anything to me... ive seen the same superskunk clones grown in various rooms.. all to be slightly different.. so thats not really a good enough method in my eyes to accurately test whether its the UVB that produces THC...

 

im still in the train of thought the THC potency of any given MJ plant is with in the genetics... and when its being harvested as opposed to what lights are used...

 

can you grow a plant under PURE UVB light??? i dont think so... im thinking it needs all spectrums to produce...

 

on the chart he provides.. Oz gets NO UVB... so again his theory is flawed cuz we grow some fuckin kick ass weed down here..

[Pam]

Now that you mention it, I do remember reading that light causes THC to break down... but I'm thinking that's during drying and curing, not positive. Regardless of when it negates the "can't hurt" idea. If it ain't broke, why is anybody trying to fix it? I'm thinking this idea might end up in a chapter of Al B's how NOT to grow!

[Al B. Fuct]

can you grow a plant under PURE UVB light??? i dont think so... im thinking it needs all spectrums to produce...

 

I'd bet you're right. It'd be a hard hypothesis to test- finding a light source that emits only the segment of UV you'd like to test would involve a trip to a university's optics lab. UV sources available to you & me emit a fair amt of visible blue, which unless filtered out, would skew your result.

 

This is a good read about chlorophyll & sunlight.

 

I'm thinking this idea might end up in a chapter of Al B's how NOT to grow!

 

heh, blacklights are already covered. See items 4-7 in HNTGD.

[Luke Skywalker]

I thought the the glass of the bulb casing removed most if not all uv output by HID lamps? Don't you need a special quartz glass tube to allow uv penetration?

 

And if anything, wouldn't higher altitudes in subtropical/temperate zones would have higher uv content as a proportion, although not necessarily higher in absolute terms, than those in tropical/equatorial sea level areas?

[Al B. Fuct]

Luke, here's a patent for borosilicate glass in 1mm thickness with 85% transmissibility down to 254nm (UVC/germicidal wavelength).

 

You're right, typical borosilicate is a bit lossy when the waves get real short, most lose about 50-60% below about 300nm (UVB area). It's still certainly there, though.

 

Seems reasonable that a tropical/equatorial mountaintop would get the highest UV exposure (not accounting for the odd ozone layer hole), both in proportion and preponderance if but for the closer to perpendicular average angle of of sunlight striking the planet in the tropics.