@Sativied posts this link even and what was sam's answer?
That was really in a different context (one of the hypothesis about the relation between high thc landraces and high uvb areas would be considered more plausible if uvb does increase thc levels, it not it doesn't make the hypothesis less likely). It's a bit of a shame it was taken out of context prematurely as it wasn't really about increasing thc with uv.
The 1987 research Is the "further research Pate mentioned in 1983:
"
The damaging effects of UV-B radiation have apparently affected the amounts of ultraviolet-absorbing secondary compounds in some plants. A similar role for Δ9 tetrahydrocannabinol may explain the high levels of this compound in Cannabis from areas of intense ambient UV-B. Further research is needed to determine whether UV-B radiation serves only as a selection pressure or if UV-B-induced stress may also directly stimulate production."
The tests from 1987 do not disprove the selection pressure (that was the context), but they don't disprove all possibilites for stimulating secondary metabolites production in cannabis either. Good attempt but should not be considered the definitive answer and should not stop others from experimenting 30 years later. As I have no doubt Sam would agree with. If you do a proper clean test he will surely be very interested. More and specifically better testing is necessary. Here was a half-decent start
https://www.icmag.com/ic/showthread.php?t=260046
and I think Sativied will even slightly agree here, that increased. Terp profiles have not been identified with isolation of UV light.
In a more nuanced context I would agree yes. An increase in terpenes in cannabis has to my knowledge not been indentified by uv treatments. It may very well even have negative effects depending on the specific terpene or uv treatment.
However, cut and paste from a private discussion:
Several studies show widely varying results per species and cultivar, and the response differs per the severity and the dynamics of [uv] stress exposure, as well as other environmental parameters.
From:
https://www.researchgate.net/publication/254218759_UV-B-Induced_Secondary_Plant_Metabolites_-_Potential_Benefits_for_Plant_and_Human_Health
Also several studies showing an increase of some of the for us well-known terpenes like limonene and pinene. As well as stimulating pathways like MEP.
Widely varying results from different methods and intensities. Acclimation with increasing levels, acute uvb stress, signaling with low intensities. Even differences depending on whether the plant received UVA prior or during the UVB treatment. Many if not all of the uvb tubes used in cannabis tests produce a lot more uva than uvb. Glass is often also transparent for uva opposed to uvb. Nowadays narrowband uvb is more accessible, like the
ones used for skin therapy.
A lack of differences in results likely says more about the methods used than what's possible with cannabis. It seems
extremely unlikely secondary metabolite production in cannabis happens to not be affected by uvb one way or the other. Besides testing for cannabinoids and preferably terpenes too, one would have to determine and try different amounts of uvb in mw/cm2 or mJ/cm2 to exclude the feasibility.
Let me repeat that is
extremely unlikely the plant species so rich in secondary metabolites production (flavonoids, cannabinoids, terpenes), cannabis, happens to be not affected, and as research for many species show, it can go either way largely depending on the type of uv treatment. Flavonoids are very likely affected, the rest needs to be tested, which is probably more about how and when they are affected than if they can be affected.
As you can see, the amount of cannabinoid may indirectly affect the influence on terpenes. Higher thc varieties could very well be less affected making it hard to compare results.
If it were easy to do, and boost the thc level with something like 2%, from 19-21, that 10% increase can make a lot of difference in a competive market some day, already does at some shops and dispensaries. For people making thc concentrates it would really be a no brainer. But then UV can reduce biomass, if it does that least in trichs but more in leaves, stems etc, the net result is a higher THC percentage but possibly the same or less THC in weight.
http://th-led.en.alibaba.com/product/60248983082-222450374/Psoriasis_Skin_Therapy_64_chip_UV_LED_COB_Module_308nm_310nm.html
Just a tad pricey...
Edit: and yes, I agree THC alone isn't everything. It's the cocktail that matters, which I do think can be influenced, but with so many varying results it may be hard to pinpoint exactly what's best.
