RECENT interesting findings

[G.O. Joe]

Characterizing the Smell of Marijuana by Odor Impact of Volatile Compounds: An Application of Simultaneous Chemical and Sensory Analysis
Somchai Rice, Jacek A. Koziel
PLOS
Published: December 10, 2015
http://dx.doi.org/10.1371/journal.pone.0144160

Recent US legislation permitting recreational use of marijuana in certain states brings the use of marijuana odor as probable cause for search and seizure to the forefront of forensic science, once again. This study showed the use of solid-phase microextraction with multidimensional gas chromatography—mass spectrometry and simultaneous human olfaction to characterize the total aroma of marijuana. The application of odor activity analysis offers an explanation as to why high volatile chemical concentration does not equate to most potent odor impact of a certain compound. This suggests that more attention should be focused on highly odorous compounds typically present in low concentrations, such as nonanal, decanol, o-cymene, benzaldehyde, which have more potent odor impact than previously reported marijuana headspace volatiles.

Chemotyping and Determination of Antimicrobial, Insecticidal, and Cytotoxic Properties of Wild-Grown Cannabis sativa from Nepal
Prabodh Satyal, William N. Setzer
Journal of Medicinally Active Plants 3, (1):9-16 2014
http://dx.doi.org/10.7275/R58W3B8V

Cannabis sativa was collected from a wildgrowing population in Biratnagar, Nepal. The essential oil was obtained by hydrodistillation and analyzed by gas chromatography – mass spectrometry. A total of 107 constituents were identified in the oil accounting for 94.2% of the composition. This Nepalese chemotype is characterized by a predominance of sesquiterpenoids (68.1%) dominated by (E)-caryophyllene (20.4%), α-humulene (7.0%), and α-bisabolol (5.8%), but a paucity of monoterpene hydrocarbons (0.9%). In particular, neither myrcene nor terpinolene were detected. The oil in the Nepalese Cannabis plants did contain small amounts of cannabidiol (1.6%), cannabichromene (0.2%) and Δ9-tetrahydrocannabinol (0.4%). The essential oil from Nepalese Cannabis sativa was screened for antimicrobial, cytotoxic, larvicidal, and insecticidal activity, and it appears as though C. sativa is relatively non-toxic.

Optimisation and characterisation of marihuana extracts obtained by supercritical fluid extraction and focused ultrasound extraction and retention time locking GC-MS
Jone Omar, Maitane Olivares, Mikel Alzaga, Nestor Etxebarria
J. Sep. Sci. 2013, 36, 1397–1404
http://dx.doi.org/10.1002/jssc.201201103

The optimisation of focused ultrasound extraction and supercritical fluid extraction of volatile oils and cannabinoids from marihuana has been accomplished by experimental design approach. On the one hand, the focused ultrasound extraction method of volatile compounds and cannabinoids was studied based on the optimisation of cyclohexane and isopropanol solvent mixtures, and the instrumental variables. The optimal working conditions were finally fixed at isopropanol/cyclohexane 1:1 mixture, cycles (3 s−1), amplitude (80%) and sonication time (5 min). On the other hand, the supercritical fluid extraction method was optimised in order to obtain a deterpenation of the plant and a subsequent cannabinoid extraction. For this purpose, pressure, temperature, flow and co-solvent percentage were optimised and the optimal working conditions were set at 100 bar, 35C, 1 mL/min, no co-solvent for the terpenes and 20% of ethanol for the cannabinoids. Based on the retention time locking GC-MS analysis of the supercritical fluid extracts the classification of the samples according to the type of plant, the growing area and season was attained. Finally, three monoterpenes and three cannabinoids were quantified in the ranges of 0.006–6.2 g/g and 0.96–324 mg/g, respectively.

Separation of aroma compounds from industrial hemp inflorescences (Cannabis sativa L.) by supercritical CO2 extraction and on-line fractionation
Carla Da Porto, Deborha Decorti, Andrea Natolino
Industrial Crops and Products 58 (2014) 99–103
http://dx.doi.org/10.1016/j.indcrop.2014.03.042

The use of supercritical carbon dioxide (Sc-CO2) extraction at 10 and 14 MPa and 40◦C and on-line frac-tionation using two separators (Sep 1: 7 MPa/25◦C; Sep2: 5 MPa/15◦C) to recovery volatile compoundsfrom the inflorescences of fiber type Cannabis sativa L. was investigated by HS-SPME/GC–MS and direct GC–MS and compared with hydrodistillation. The best results were obtained by Sc-CO2extraction car-ried out at 10 MPa and 40◦C. Under these operating conditions, cuticular waxes covering the surface offlowers were collected in the first separator and volatile compounds (100%) in the second. The superiorquality of this last extract was proved by the perfect overlapping of its HS-SPME/GC–MS volatile profileto that of inflorescences. The recovery of fractions with different composition and biological properties,made the inflorescences of fiber type Cannabis sativa L suitable for cosmetic and/or food industry.

Fibre hemp inflorescences: From crop-residues to essential oil production
Alessandra Bertoli, Sabrina Tozzi, Luisa Pistelli, Luciana G. Angelini
Industrial Crops and Products 32 (2010) 329–337
http://dx.doi.org/10.1016/j.indcrop.2010.05.012

The volatile composition of ten fibre hemp (Cannabis sativa L.) varieties was investigated during two successive growing seasons under temperate climatic conditions in Central Italy.

The freshly plant inflorescences were hydrodistilled and the essential oils (EOs) were characterized by GC–MS. In addition, the composition of the aroma emitted spontaneously from the freshly plant inflorescences were analysed by SPME-GC–MS. The EO yields of eight dioecious (Carmagnola, C.S., Red Petiole, Pop 1, Pop 2, Pop 3, Pop 4, Pop 5) and two monoecious (Codimono and Felina 34) cultivars ranged from 0.11 to 0.25% (w/w) and showed a significant production of a-pinene (3–20%), b-pinene (1–8%), E-ocimene (1–10%), myrcene (8–45%) and terpinolene (0.12–22%).

The monoterpene composition was useful to distinguish the monoecious cultivars from the dioecious ones. b-Caryophyllene (7–28%), a-humulene (3–12%), and caryophyllene oxide (2–6%) were the main sesquiterpenes. Tetrahydrocannabinol (THC) was present in traces in the EOs of only two dioecious cultivars cultivated in 2005. Cannabinol (CBN) was not detected in the essential oils, while the no-hallucinogenous cannabidiol (CBD) was found as typical volatile constituent in several analysed cultivars. These findings were also confirmed by the headspace GC–MS analysis carried out on the same samples. The analysed EOs obtained from fibre hemp varieties cultivated in Central Italy were characterized by an interesting and specific terpene composition with a legal and safe cannabinoid content. They were obtained from freshly plant inflorescences, which usually represent a waste material from C. sativa L. fibre varieties. The present study strengths the hypothesis to grow hemp as a multi-use crop through a complete utilization of the plant material using inflorescences to produce essential oils as natural flavour and fragrance additives.

Headspace Solid Phase Microextraction (HS SPME) Gas Chromatography Mass Spectrometric Analysis of the Volatile Constituents of Cannabis sativa L. From Kashmir
Manzoor A. Rather, Bilal A. Dar, Shahnawaz N. Sofi, Tauheeda Hassan, Nasir Ali, Ashiq H. Lone, Abdul S. Shawl, Wajahat A. Shah, M. A. Qurishi and Poonam Prakash
Journal of Pharmacy Research 2011,4(8),2651-2653

Headspace Solid-phase micro extraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS) has been used to isolate and identify the volatile compounds from the leaves of Cannabis sativa growing in Kashmir. The analysis led to the identification of 17 volatile components constituting 94.8 % of the total identified components. The chemical composition of the SPME extract from the leaves of C. sativa comprised mainly of sesquiterpene hydrocarbons (64.3%), monoterpene hydrocarbons (18.4%) and alcohols (10.3%). The major components identified in the HS-SPME extract were trans-caryophyllene (36.9%), a-humulene (16.2%), a-pinene (10.7%), 3-hexen-1-ol-acetate (6.2%) and ß-pinene (4.2%). The current study is the first report involving rapid analysis of volatile components of C. sativa by HS-SPME.

Ultrasound-assisted extraction of volatile compounds from industrial Cannabis sativa L. inflorescences
Da Porto C, Decorti D, Natolino A
International Journal of Applied Research in Natural Products
2014 Vol. 7 (1), pp. 8-14
http://www.ijarnp.org/index.php/ijarnp/article/view/228

This study investigated the use of ultrasound-assisted extraction (UAE) to recovery volatile compounds from the inflorescences of a fiber type Cannabis sativa L. cultivar. The results show that ultrasonic treatment not longer than 5 min allows to obtain an enhanced concentration of terpenes in comparison with maceration. Instead, an ultrasonic treatment longer than 5 min increased the concentration of δ-9-tetraidrocannabinol (THC). A preliminary screening of cannabis inflorescences scent was performed by headspace solid-phase microextraction (HS-SPME) with gas chromatography-mass spectrometry (GC-MS) avoiding the chemical modification and artifact formation that can occur in conventional methods.

 

[Sam_Skunkman]

G.O. Joe,
Interesting papers on Cannabis terpenes, I love terpenes!!!
-SamS

 

[Sam_Skunkman]

The Analytical Chemistry of Cannabis Quality Assessment, Assurance, and Regulation of Medicinal Marijuana and Cannabinoid Preparations
Brian F. Thomas, Mahmoud A. ElSohly
Emerging Issues in Analytical Chemistry 2016
ISBN 978-0-12-804646-3

Complete book Pdf:
http://www.osti.ca/SCFE/The Analytical Chemistry of Cannabis - Complete.pdf

This book is very interesting to say the least, check out the references....
-SamS

CHEMICAL CONSTITUENTS AND PHENOTYPES OF C. SATIVA L.
CBN was the first cannabinoid to be isolated and identified from C. sativa. The elucidation of CBN led to speculation that the
psychotropically active constituents of cannabis could be THCs. The nonpsychotropic compound CBD was subsequently isolated from Mexican marijuana and the structure was determined. Gaoni and Mechoulam, two pioneers of cannabis research, determined the structureof Δ9-THC after finally succeeding in isolating and purifying this elusive compound (see Mechoulam Close-up: How to Pamper an Idea). Since then, the number of cannabinoids and other compounds isolated from cannabis has increased continually, with 545 now reported. Of these, 104 are phytocannabinoids (Table 1.3). From the isolation and structural elucidation of Δ9-THC in 1964 until 1980, 61 phytocannabinoids were isolated and reported. Only nine new ones were characterized between 1981 and 2005, but 31 were reported between 2006 and 2010. The 13 chemical constituent type groups shown in Table 1.3 suggests the chemical complexity of the cannabis plant.
Table 1.3 Constituents of Cannabis sativa L.
No. Groups Number of Known Compounds
1 CBG type 17
2 CBC type 8
3 CBD type 8
4 Δ9-THC type 18
5 Δ8-THC type 2
6 CBL type 3
7 CBE type 5
8 CBN type 10
9 CBND type 2
10 CBT type 9
11 Miscellaneous 22
12 Total cannabinoids 104


13 Total noncannabinoids 441
Total 545

 

[G.O. Joe]

Mechoulam's story was interesting I wonder if he has more. So Israel isn't so informal and relaxed after all. The history of cannabis chemistry was supposed to look different and empty but, OK here have 5 kilos of hash, and everything changed. The book is more a slim up to date review of all things cannabis than it is analytical chemistry though.

The aroma articles are not the best quality and neither are the journals (this domain for sale) but they all have something interesting for the scientist. The first from PLOS was the most interesting. They found both sulfur compounds and pyrazines for instance. Unfortunately a lot of their peaks are misidentified due to the limitations of everything, and even the odor event peak identifications are unreliable. I hope someone got their odor tester some real piperonal to sniff at the end because it is not musty potato.

 

[led05]

Question for Sam RE UVB

Question for Sam RE UVB

Pate worked for me for 2 decades we ran several grow outs in my greenhouse he designed that tried to prove that UVB improved Cannabis in any way. We could not, We used 3 different clones one CBD and two drug varieties we had 4 examples of each each of the 3 clones they were set up so the first set of three were 1 meter from the UVB lights, the next set was 3 meters, the next set was 6 meters, and the last set was a control with no UVB. They were all in 10 liter pots the same size, about 3 feet when started, with the same soil and watering. The closest to the lights got badly fried, the second set was lightly fried, the third set, not really harmed and the 4th set just controls. We ran the lights first in veg then in flowering. We used GC-FID to measure the cannabinoids and terpenes and weighed the total biomass, and flowers and stems and leaf fraction of the dry plants after harvest.
RCC and I did organoleptic analysis on the two drug varieties Skunk #1 and a Thai?, the no UVB plants were the best. The closest row to the lights were much less weight and resin, the second row was lightly harmed in a similar way. None of the UVB plants had any more cannabinoids or terpenes or more weight. I did try.
-SamS

Sam, when you did these studies approx when was it and what type of bulbs did you use to produce the UVB, whatever details you can remember are greatly appreciated... I've seen you reference these studies a # of times over the years and always have wondered some of these details, finally I've asked..?

I too believe UVB does something like the other poster in here.. Perhaps it's about targeting UVB and not so much of the other UV range... Bulbs today, like dermatological ones are very precise, not sure what you had access to back then.

Could this have made a difference, did you just use Mercury Vapor or something not enclosed?

Thank you much

 

[Sam_Skunkman]

Pate picked out the bulbs they were long tube fluorescent UVB and Pate said they were similar to high in the mountain UVB sun. I still have them and will try and remember to look at them next chance I get, to tell you the model and who made them, I suspect Philips. But I am sure they did test for what we looked for, we had a UVA, UVB & another UVC light meter we used.
The work was done in the early 90's, we tried several methods to find any increase in potency, cannabinoids, terpenes, weight, resin. UVB did not help in our tests.
-SamS

 

[led05]

Pate picked out the bulbs they were long tube fluorescent UVB and Pate said they were similar to high in the mountain UVB sun. I still have them and will try and remember to look at them next chance I get, to tell you the model and who made them, I suspect Philips. But I am sure they did test for what we looked for, we had a UVA, UVB & another UVC light meter we used.
The work was done in the early 90's, we tried several methods to find any increase in potency, cannabinoids, terpenes, weight, resin. UVB did not help in our tests.
-SamS

thanks for quick reply and answer. If/when you find those bulbs if you stumble across what the % or mJ/Cm2 readings were for the A, B & C UV ranges, respectively that would be extremely appreciated, if they even exist...

Anecdotal evidence, on so many occasions and via other folks as well seems to say UVB, does something positive, the negative sides seem to be much better understood, perhaps there are no positives and we're just hoping but my experience says otherwise...

Thank you again

 

[Cannabologist]

Many of the bulbs and LED lights being sold (supposedly) put out UV light, and depending on the bulb, a more "complete" spectrum as close to the sun as possible.... And growers are noting improvements, though again this is all anecdotal....

This again runs in contrary to your tests Sam.. Which is weird, but something you may want to think about testing again..

I can attest that many people report increases, while I have not tested this myself, I have seen the plants and results of using lighting supposedly putting out such light spectra, and they are something extraordinary, even in terms of just the growth.

 

[Gr33nSanta]

I own some 3000k, 3500k and 4000k, I like to mix em all, I also have a few old blurples in the mix. It is said that the red increase yield while the blue to some extent increase resin production.

Since I am trying to grow resin I never even tried growing with the 3000k alone. I get great results from the 3500k by themselves or mixing the 3000k and the 4000k. I have also seen great results mixing 4000k and 5000k in flowering but more testing is required.

most leds I use are cxb3590, vero 29 and also I have some other older and newer tech. I mix em all, 100% LEDs in flower, since 2011

 

[led05]

Many of the bulbs and LED lights being sold (supposedly) put out UV light, and depending on the bulb, a more "complete" spectrum as close to the sun as possible.... And growers are noting improvements, though again this is all anecdotal....

This again runs in contrary to your tests Sam.. Which is weird, but something you may want to think about testing again..

I can attest that many people report increases, while I have not tested this myself, I have seen the plants and results of using lighting supposedly putting out such light spectra, and they are something extraordinary, even in terms of just the growth.

Ive tested many of those bulbs (MH up to 10k, the new agrosun I think it's called puts out a little, its fluorescent) and they all put out negligible or such little UVB that they aren't really useful... no, they weren't run in enclosed fixtures but pretty sure the USA has certain limitations on what bulbs can put out as far as uvb, what the inner & outer jackets must block etc....medical grade ones don't fall under this.

UVB LED's as they are now are prohibitively expensive, the benefits I've seen with LED's are just more complete spectrum, I've tested way too many LED to note, I believe models you're talking about accomplice this via fluros added into the led or supplemented right? I've yet to ever test and LED diode putting out any UV, zero

Now, a tiny little 15w dermatological lamp will throw off the equivalent of 10+ uv index 3-4 + feet away and it fills that out in all directions.... look for psoriasis bulbs focused on uvb if there's an interest, USHIO makes a cheap and dope mid range UVB BULB if you can find them, common reptile light fixtures hold & reflect these bulbs well

If you stand close to these bulbs, within a foot UV index is above 50, yes 50 so be careful, burns occur quickly, eye protection a must

These are the bulbs I referenced, the USHIO mid range UVB 306nm, middle of page link - they are the best and cheapest I was able to find a few years back when looking into all of this http://www.ushio.com/products/uv/uv-illumination/low-pressure-mercury-arc-blacklight.php

I think the potential positive UV effects on this plant, all plants is a terribly misunderstood area of focus and more studies need to be done, I wish I had the correct resources, a lab and time to do so, someday someone will and hopefully prove what we've all seen anecdotally

 

[Cannabologist]

Nope they aren't within T5 fixtures, they are LED ballasts only and all the light is put out via diodes.. I'm blanking on the names of these 2 particular brands, I'll find out again in a few days. Both of these use differently colored diodes of varying wavelengths of light.

Certain bulbs are also supposedly a more complete spectrum, including UV, such as ceramic metal halide and the Hortilux Blue bulbs, and as you state with all of these, eye protection is recommended, and they can cause sunburn if you are close enough and your skin is exposed long enough under them.

So.. Yeah Idk. Even being around traditional HPS without enough eye protection I know I've probably hurt my eyes some so always with anything personal safety is recommended first and foremost.. Ie pesticides, inhalation of powdered nutes, wear gloves as much as possible, protect your skin, air ways, and eyes, etc.... Not only do so many of us always skimp on these things, we straight up say fuck it!... Eh.. We really shouldn't.

 

[led05]

Nope they aren't within T5 fixtures, they are LED ballasts only and all the light is put out via diodes.. I'm blanking on the names of these 2 particular brands, I'll find out again in a few days. Both of these use differently colored diodes of varying wavelengths of light.

Certain bulbs are also supposedly a more complete spectrum, including UV, such as ceramic metal halide and the Hortilux Blue bulbs, and as you state with all of these, eye protection is recommended, and they can cause sunburn if you are close enough and your skin is exposed long enough under them.

So.. Yeah Idk. Even being around traditional HPS without enough eye protection I know I've probably hurt my eyes some so always with anything personal safety is recommended first and foremost.. Ie pesticides, inhalation of powdered nutes, wear gloves as much as possible, protect your skin, air ways, and eyes, etc.... Not only do so many of us always skimp on these things, we straight up say fuck it!... Eh.. We really shouldn't.

None of the MH bulbs I've ever tested marketed as a plant bulb has had any actual useful amounts of uva/b including the hortilux .. fluros are really the only legitimate option on the market for uvb and really only medical grade or bulbs for industrial uses, again fluros, if someone is making lights w actual uvb diodes, I would be extremely surprised and curious as to whom, uvb diodes are prohibitively expensive, id like to test the ones claiming as such, hopefully you can recall

 

[Cannabologist]

Ceramic metal halides are (apparently) quite different from traditional metal halides, which is why I made the distinction.

I'll get you the brands in particular soon... I know people have had amazing growth with them, and I've seen the results.

The claims of the manufacturers are that the bulbs (such as the Hortilux Blue MH bulbs) are that they are putting out usable UV light. There are cautions on the box warning to use protection due to the UV exposure, ESPECIALLY if the bulb is damaged or broken.

People seems to state that there is more than just the typical light bleaching from too much light with lamps if you leave them too close, you get "other kinds" of stress burning that is atypical of light bleaching... So.. Again... All these anecdotal reports.. And anecdotal tests lol...

Leaves the imagination wondering. I still gotta screw in this new bulb and see how it goes! Hope I don't burn my eyes out when I stare at it's glory lol

 

[G.O. Joe]

Cannabis Domestication, Breeding History, Present-day Genetic Diversity, and Future Prospects
Robert C. Clarke & Mark D. Merlin
Critical Reviews in Plant Sciences
Pages 1-35 | Published online: 02 Mar 2017
http://dx.doi.org/10.1080/07352689.2016.1267498

Humans and the Cannabis plant share an intimate history spanning millennia. Humans spread Cannabis from its Eurasian homelands throughout much of the world, and, in concert with local climatic and human cultural parameters, created traditional landrace varieties (cultivars resulting from a combination of natural and farmer selection) with few apparent signs of domestication. Cannabis breeders combined populations from widely divergent geographical regions and gene pools to develop economically valuable fiber, seed, and drug cultivars, and several approaches were used with varying results. The widespread use of single plant selections in cultivar breeding, inbreeding, and the adoption of asexual reproduction for commercial drug production, reduced genetic diversity and made many present-day cultivars susceptible to pathogens and pests. The great majority of drug Cannabis cultivars are now completely domesticated, and thus are entirely dependent on humans for their survival. Future ramifications remain to be realized.

 

[Cannabologist]

None of the MH bulbs I've ever tested marketed as a plant bulb has had any actual useful amounts of uva/b including the hortilux .. fluros are really the only legitimate option on the market for uvb and really only medical grade or bulbs for industrial uses, again fluros, if someone is making lights w actual uvb diodes, I would be extremely surprised and curious as to whom, uvb diodes are prohibitively expensive, id like to test the ones claiming as such, hopefully you can recall

Yep! I got it! it's the Kind LED, and also the Titan LED... Well, I'm not too sure on the Titan, I believe it puts out UV, but the Kind certainly is supposed to... Supposed to.. It seems to given what it does (need to wear eye protection, can burn plants, etc)..

 

[led05]

Yep! I got it! it's the Kind LED, and also the Titan LED... Well, I'm not too sure on the Titan, I believe it puts out UV, but the Kind certainly is supposed to... Supposed to.. It seems to given what it does (need to wear eye protection, can burn plants, etc)..

Thanks...

I measured Kind with this meter, it registered either 0 or .1 UV index, every LED I have ever tested measures nothing, including all the Cree CXB, Vero etc, NO UV, they are all BS making those claims (Cree and Vero of course don't make those claims, BC they're not true) - The cost of an actual UVB diode just isn't worth it when you can add it easy / cheap with Fluros and the light permeates the room, it's not like a 6-12" fluro thing for regular spectrum, it goes easily 4+ feet at UVB > 10 Index with right reflector.....

https://www.solarmeter.com/model65....t=6.5UVIndex&gclid=CPHIldf0v9ICFRGHswode7YAYg

The UV Index actually represents very closely the exact range UVB is beneficial to plants, reptiles etc - which is why I bought this meter... Someone running a full spectrometer would be nice on all these LED's but I already know what it would show RE UV, interesting how none of the ones have graphs that show actual UVB (280-315nm - the mid range Ushio bulb I linked peaks at 306nm) for their lights....

here's a spectral graph of Cree for example, note where the NM stop, hard.... Page 10 http://www.cree.com/~/media/Files/C...Modules/XLamp/Data-and-Binning/ds-CXB3590.pdf


Enough on this matter though, I'm done clogging up this thread.... hopefully it'll bug Sam enough to run tests again with modern bulbs and all his cool testing equipment I wish I had access too......

 

[Cannabologist]

Huuumm. That's interesting for sure. I saw another test on the kind vs a meter and it wasn't producing any, but I don't really buy the test they were doing and something seemed fishy how they were doing it...

Suffice to say it puts out.. Likely not much to no UV. The website and other claims seem to state it puts out, well, at least a little...

https://www.kindledgrowlights.com/pages/indoor-grow-light-spectrum-and-par-reading

Verrry little.. Like, from mayyybe 250 nm on up, but you don't start getting much "usable" light until 400nm... So yeah.. Hmmm hm hm hm... hmmm hmm. Yeah it's likely more close to nothing. Or at least you'd have to get so close to the bulbs to get the effect you're torching em anyway. hmm
hhmmm
hm
hmm hmm hmm

Yeah that Cree's doing nothing.

Have to see about the slight investment in a UV meter meow...

What other brand recommendations would you have for UV and other meters (par, spectrometer, etc?).

What actual bulbs would you recommend this all being the case, if any, for UV?

 

[neverforget4/20]

http://www.htgsupply.com/products/agromax-pure-uv-t5-bulb-4-foot
In my experience this tube cranks out uvb

 

[Sam_Skunkman]

Guys please make a thread for UVB....
-SamS

 

[Sam_Skunkman]

x

Cannabis Domestication, Breeding History, Present-day Genetic Diversity, and Future Prospects
Robert C. Clarke & Mark D. Merlin
Critical Reviews in Plant Sciences
Pages 1-35 | Published online: 02 Mar 2017
Doi: 10.1080/07352689.2016.1267498

Humans and the Cannabis plant share an intimate history spanning millennia. Humans spread Cannabis from its Eurasian homelands throughout much of the world, and, in concert with local climatic and human cultural parameters, created traditional landrace varieties (cultivars resulting from a combination of natural and farmer selection) with few apparent signs of domestication. Cannabis breeders combined populations from widely divergent geographical regions and gene pools to develop economically valuable fiber, seed, and drug cultivars, and several approaches were used with varying results. The widespread use of single plant selections in cultivar breeding, inbreeding, and the adoption of asexual reproduction for commercial drug production, reduced genetic diversity and made many present-day cultivars susceptible to pathogens and pests. The great majority of drug Cannabis cultivars are now completely domesticated, and thus are entirely dependent on humans for their survival. Future ramifications remain to be realized.