Get a harvest every 2 weeks - Page 97

We TaRdED · #**961** 03-25-2008, 01:55 PM

Quote:

Originally Posted by Al B. Fuct

No, I've never found anything credible to support the more UV = more resin/THC theory.

Wives' tale, sorry.

i watched something good from a guy named marijuana man explaining how uv's allegedly increase trichs.

let me do a little gophering.

We TaRdED · #**962** 03-25-2008, 01:56 PM

ahhhhh, ok here it is

YouTube - THC, UVB and Me

really good info whether you believe it or not. just thought i would share with your guys

Al B. Fuct · #**963** 03-25-2008, 02:02 PM

Yes, I've seen that character before. He gives no evidence whatsoever to support his claim that UV helps a plant make more resin or THC... he just says it like it's some sort of well-known fact. Just because some joker puts his claim in a vid on YouTube doesn't make it true!

We TaRdED · #**964** 03-25-2008, 02:12 PM

opps i posted twice.

peace and pot

We TaRdED · #**965** 03-25-2008, 02:15 PM

Quote:

Originally Posted by Al B. Fuct

Yes, I've seen that character before. He gives no evidence whatsoever to support his claim that UV helps a plant make more resin or THC... he just says it like it's some sort of well-known fact. Just because some joker puts his claim in a vid on YouTube doesn't make it true!

could just been propaganda, idk....

i wonder if people have done actually tests and studies on this.

al, maybe you should put a reptile light over one of your crops and see if there is a noticeable difference

i would myself, but im really broke........ lol

peace out

Al B. Fuct · #**966** 03-25-2008, 02:39 PM

Quote:

Originally Posted by We TaRdED

could just been propaganda, idk....

I'm not so sure it's propaganda as much as some clown just spewing off things he's heard or read elsewhere, with no supporting research or evidence.

Quote:

i wonder if people have done actually tests and studies on this.

Proper scholarly research and writing about growing cannabis is very hard to come by as most governments actively prohibit it.

Quote:

al, maybe you should put a reptile light over one of your crops and see if there is a noticeable difference

i would myself, but im really broke........ lol

I would myself, but I think it's a very improbable hypothesis and not really worth testing.

Maccabee · #**967** 03-25-2008, 03:47 PM

I've tried to look into this before. Seems like a lot of the same stuff seen in the youtube vid is from here:

MARIJUANA OPTICS: An elaboration on the process that makes THC

The same resource can be found here:

http://www.onlinepot.org/medical/opticsandthc9M.pdf

and quoted all over the place.

It seems like the papers to locate are Pate 1983 / 1994 and then Lyndon et al 1987.

Citations for those inclined to do so:

Pate D. W. 1994 Chemical ecology of Cannabis. Journal of the International Hemp Association 1: 29, 32-37

Lydon J. A. H. Teramura C. B. Coffman 1987 UV-B radiation effects on photosynthesis, growth and cannabinoid production of two Cannabis sativa chemotypes. Photochemistry and Photobiology 46: 201-206

Blackwell has the Lydon article's abstract publicly available:

Quote:

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.

[emphasis added]

So, a strong maybe is what I take from this; but nothing dramatic enough to make me want to run out and festoon my flowering chamber with reptile lights.

Stumbling around I found this, which helps to clear up some of the stuff marijuana Man was mumbling about in his vid:

A chemotaxonomic analysis of cannabinoid variation in Cannabis (Cannabaceae) -- Hillig and Mahlberg 91 (6): 966 -- American Journal of Botany

From the intro, with interesting bits highlighted:

Quote:

Cannabinoids are terpenophenolic compounds unique to Cannabis. They are produced by glandular trichomes that occur on most aerial surfaces of the plant (Dayanandan and Kaufman, 1976

; Turner et al., 1978

). Approximately 61 cannabinoids are known to exist, although some of these are breakdown products or artifacts (Schultes and Hofmann, 1980

; Turner et al., 1980

). The cannabinoids discussed in this paper are biosynthesized in an acidic (carboxylated) form and are decarboxylated upon heating and drying of harvested plant material (Doorenbos et al., 1971 ). They are here referred to in their decarboxylated form. Cannabigerol (CBG) is the direct precursor of cannabichromene (CBC), cannabidiol (CBD), and 9-tetrahydrocannabinol (THC) (Taura et al., 1995 , 1996 ; Morimoto et al., 1997 ). A homologous series of compounds with propyl side-chains is biosynthesized from cannabigerovarin (CBGV), including cannabivarichromene (CBCV), cannabidivarin (CBDV), and 9-tetrahydrocannabivarin (THCV), respectively (Fig. 1A–D) (Schultes and Hofmann, 1980 ). THC and/or CBD are generally produced in greatest abundance. However, THCV and less commonly CBDV may exceed the levels of THC and/or CBD in some plants (Baker et al., 1980 ). THC and THCV are primarily responsible for the euphoric effects of marijuana and hashish (McPartland and Russo, 2001 ).

Chemotaxonomy has a long history of use in the delimitation of Cannabis taxa. Lamarck (1785)

emphasized the greater inebriant potential of C. indica Lam. when he differentiated it from C. sativa L. Names and descriptions of other putative species of Cannabis have been published (reviewed in Schultes et al., 1974

; Small and Cronquist, 1976

). Of these, only C. ruderalis Janisch. is commonly accepted. Small (1979a) considered the amount of THC produced by Cannabis to be an "extremely important" taxonomic character and used gas chromatography (GC) to differentiate indica strains from sativa strains on the basis of their THC content (Small and Beckstead, 1973a , b ; Small et al., 1975 ; Small and Cronquist, 1976 ). Small and Cronquist (1976) favored a monospecific concept and assigned these two taxa to subspecies of C. sativa.

Numerous biochemical studies of Cannabis plants grown from achenes ("seeds") of known geographic origin have been reported (Fetterman et al., 1971

; Fetterman and Turner, 1972

; Nordal and Braenden, 1973

; Small and Beckstead, 1973a

, b

; Turner et al., 1973

; Turner and Hadley, 1973a

, 1974

; Boucher et al., 1974

; Holley et al., 1975

; Small et al., 1975

; Rowan and Fairbairn, 1977

; Beutler and Der Marderosian, 1978

; Clark and Bohm, 1979

; Turner et al., 1979

; Fournier and Paris, 1980

; Hemphill et al., 1980

; Veszki et al., 1980

; de Meijer et al., 1992

). Forensic studies of Cannabis examined marijuana and hashish samples of known origin, grown in a range of environments (Jenkins and Patterson, 1973

; Poddar et al., 1973

; Baker et al., 1980

, 1982

; Barni-Comparini et al., 1984

; Brenneisen and ElSohly, 1988

). In studies that used packed columns for gas chromatographic separations, CBC may sometimes have been mistaken for CBD because of their close retention times (Small and Beckstead, 1973a

; Turner and Hadley, 1973b

). Most botanical and forensic studies of Cannabis lack voucher specimens for taxonomic identification. A notable exception is the systematic/forensic investigation by Small and coworkers that is referred to extensively herein (Small and Beckstead, 1973a

, b

; Small et al., 1975

; Small and Cronquist, 1976

; Small, 1979a

, b

).

The cannabinoid content of different strains of Cannabis is associated with their geographic origins. Extracts of Cannabis indica ("Indian hemp") were commonly used in Western medicine, while the common hemp of Europe was generally regarded as unsuitable for medicinal use (Winek, 1977 ). Small and Beckstead (1973a , b ) observed that most strains in their collection that produced high levels of THC originated from latitudes south of 30°N. They detected elevated levels of a cannabinoid presumed to be cannabigerol monomethylether (CBGM) in strains from northeast Asia. High levels of THCV were reported in Cannabis strains from southern Africa, India, Nepal, and eastern Asia (Merkus, 1971 ; Fetterman and Turner, 1972 ; Turner et al., 1973 ; Boucher et al., 1974 ; Baker et al., 1980 ).

The amounts of CBD and THC in an individual Cannabis plant can be characterized both qualitatively and quantitatively (Hemphill et al., 1980

; Hillig, 2002

; Mandolino et al., 2003

). Qualitative characterization involves determining a plant's THC/CBD ratio (the inverse ratio is sometimes used) and assigning it to a discrete chemical phenotype (chemotype). Fetterman et al. (1971) recognized two chemotypes: a THC/CBD ratio >1.0 characteristic of "drug-type" plants, and a THC/ CBD ratio <1.0 characteristic of "fiber-type" plants. Small and Beckstead (1973a , b ) also recognized an intermediate chemotype. According to their system of classification (that is used herein), chemotype I plants have a high THC/CBD ratio (>>1.0), chemotype II plants have an intermediate ratio (close to 1.0), and chemotype III plants have a low THC/CBD ratio (<<1.0). The THC/CBD chemotype of a plant is determined at a young age and is stable beyond the seedling stage throughout the life of the plant (Barni-Comparini et al., 1984 ; Vogelmann et al., 1988 ).

In addition to the qualitative determination of THC/CBD chemotype, a plant can be characterized by the quantitative levels of cannabinoids within its tissues. These levels are likely determined by the interaction of several genes with a plant's environment. Numerous biotic and abiotic factors affect cannabinoid production including the sex and maturity of the plant (Doorenbos et al.,1971

; Fetterman et al., 1971

; Small et al., 1975

), daylight length (Valle et al., 1978

), ambient temperature (Bazzaz et al., 1975

), nutrient availability (Coffman and Gentner, 1977

; Bócsa et al., 1997

), and ultraviolet light intensity (Lydon et al., 1987

; Pate, 1994

). Quantitative levels of cannabinoids also vary among different tissues within a plant (Fetterman et al., 1971

; Hemphill et al., 1980

). The amount of CBD or THC in the mature inflorescence of a pistillate plant (Cannabis is dioecious) may exceed 10.0% of its dry weight (d.w.), while the amount of these cannabinoids in the primary leaves is often <1.0% (Baker et al., 1982

; Barni-Comparini et al., 1984

).

So the whole UVB and D-9-THC production questions is complicated by issues of strain--and without citing a pile of other research, it should be noted that there is not consensus on which cannabinoids are responsible for producing different kinds of highs. UVB might be really important for equatorial sativas, for instance, but not so much for indicas. Also, it may be that in the abscence of normal outdoor UVB input, some other mechanism kicks in. After all, I've long associated expertly grown indoor dope with the highest levels of quality as I think many others do and that would not be the case if indoor growing under lights left so much to be desired in comparison to outdoor crops in terms of the production of psychoactive compounds.

This is getting kinda far afield from the subject of the thread.....probably best to make a discussion in advance growing techniques if people really want to hash out the UVB thing again.

daddychrisg · #**968** 03-25-2008, 03:49 PM

AL, I have searched out the least expensive H2o2 in my area...Where could it be? Beauty Supply! they have 30% H2o2 for around $2.50 a quart. The only thing that I don't know is if they put any type of stabilizers or additives. Have any experience with this option?
If I was going to purchase food grade H2o2 over the net to be delivered to me, it would cost me almost twice what it would cost me down at the local hydro shop..Man on a lighter note, the first time I added 35% H2O2 to my res,and control unit, it about over flowed with bubbles....I guess there was alittle growth in there! Anyhow be well..DCG

Enigma · #**969** 03-25-2008, 03:50 PM

Do research on UV light and plants in general. That should bring up some much needed R&D!

My bet is that UV will kill em!

Al B. Fuct · #**970** 03-25-2008, 03:54 PM

While I'm thinking of it, beware the claim that HPS 'doesn't have any UV.' This is something I researched while looking at cooltubes.

HPS absolutely does emit UV, all the way to the UVC region at 253nm, and in amounts proportional to sunlight. Borosilicate (pyrex) glass used in cooltubes is available in a high UV transmissibility optical type where about 15% of UVC is lost, but UVA & B are passed at about 90%. However, even the bakeware grade passes UV pretty well, up to the high end of UVC, where there's about a 30% rolloff in transmission.

UVC germicidal lamps use quartz envelopes as it has almost no attenuation of UVC, but quartz envelopes are VERY exxy. I recently paid $90 for a 14" quartz UVC lamp tube for one of my ozonators.

If one were to use a proper UV lamp in testing the UV/THC theory, it should be in a closed circuit cooltube so the ozone it produces is blown out of the room. Too much O3 will burn plants and if the UV lamp has to run all the time for such an investigation, O3 burn is certain if not ducted out.

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