[bendoslendo]

The stability of cannabis and its preparations on storage
Fairbairn JW, Liebmann JA, Rowan MG
J Pharm Pharmacol 1976 Jan;28(1):1-7

Abstract:
Solutions of pure cannabinoids, nine samples of herbal and two of resin cannabis (one freshly prepared) were stored in varying conditions for up to 2 years. Exposure to light (not direct sunlight) was shown to be the greatest single factos in loss of cannabinoids especially in solutions, which should therefore be protected from light during analytical and phytochemical operations. Previous claims that solutions in ethanol were stable have not been substantiated. The effect of temperature, up to 20 degrees, was insignificant but air oxidation did lead to significant losses. These could be reduced if care was taken to minimize damage to the glands which act as "well filled, well closed containers". Loss of tetrahydrocannabinol after exposure to light does not lead to an increase in cannabinol, but air oxidation in the dark does. It is concluded that carefully prepared herbal or resin cannabis or extracts are reasonably stable for 1 to 2 years if stored in the dark at room temperature.

Not answering your question about specific spectra, but at least showing it doesn't have to be direct sunlight. A bunch of old citations/abstracts concerning storage here: https://www.erowid.org/plants/cannabi...adation1.shtml

[ibjamming]

Originally Posted by El Toker

I harvest when it's convenient for me to do so. That varies so can occur during lights on, lights off etc. I've noticed no difference potency as a result of this, and most of the time I tend to grow cuttings from the same plant for multiple grows.

Pretty much what I've noticed in my limited experience too...no testing though. I harvest in batches...I take branches that are ready...leaving others to finish some more. I don't notice a difference in strength or taste or harshness depending on when I happen to take a branch be it first thing or at the end of the "day". I think it's another urban legend of growing. I mean REALLY...can it make THAT much difference what time of day you harvest? Kick ass weed IF harvested in the morning...hay if harvested in the afternoon? I don't think so Tim...

[MrBlue2]

Originally Posted by ganjaments

Do you have a source for this, so that I may read more?

Sure, here are three. I have never read any of them. You might be able to order them through amazon or something. I still think you should at least read the wiki pages on UV light, visible light, and THC. then draw your own conclusions. UV light contains radiation. UV radiation breaks down everything it comes in contact with. Visible light is not harsh at all. Its really a very simple concept.


^ Pate, D.W. (1983). "Possible role of ultraviolet radiation in evolution of Cannabis chemotypes". Economic Botany 37: 396–405. doi:10.1007/BF02904200.

^ Lydon, J; A.H. Teramura (1987). "Photochemical decomposition of cannabidiol in its resin base". Phytochemistry 26: 1216. doi:10.1016/S0031-9422(00)82388-2.

^ Lydon, J; A.H. Teramura, C.B. Coffman (1987). "UV-B radiation effects on photosynthesis, growth and cannabinoid production of two Cannabis sativa chemotypes". Photochem. Photobiol. A 46: 201. doi:10.1111/j.1751-1097.1987.tb04757.x.

[messn'n'gommin']

Originally Posted by MrBlue2

Sure, here are three. I have never read any of them. You might be able to order them through amazon or something. I still think you should at least read the wiki pages on UV light, visible light, and THC. then draw your own conclusions. UV light contains radiation. UV radiation breaks down everything it comes in contact with. Visible light is not harsh at all. Its really a very simple concept.


^ Pate, D.W. (1983). "Possible role of ultraviolet radiation in evolution of Cannabis chemotypes". Economic Botany 37: 396–405. doi:10.1007/BF02904200.

^ Lydon, J; A.H. Teramura (1987). "Photochemical decomposition of cannabidiol in its resin base". Phytochemistry 26: 1216. doi:10.1016/S0031-9422(00)82388-2.

^ Lydon, J; A.H. Teramura, C.B. Coffman (1987). "UV-B radiation effects on photosynthesis, growth and cannabinoid production of two Cannabis sativa chemotypes". Photochem. Photobiol. A 46: 201. doi:10.1111/j.1751-1097.1987.tb04757.x.

If you post these in Spurr's thread, he might be able to find them.

"Full text: post papers you want in full text..." by spurr
https://www.icmag.com/ic/showthread.php?t=196115

[MrBlue2]

Originally Posted by messn'n'gommin'

If you post these in Spurr's thread, he might be able to find them.

"Full text: post papers you want in full text..." by spurr
https://www.icmag.com/ic/showthread.php?t=196115

Thanks!!! I just posted them up there. Hopefully he'll have them soon.

[ganjaments]

Thanks for posting in the other thread MrBlue2.. Hopefully spurr can help us out with some reading materials.

[MrBlue2]

I dont know how to attach files and he posted the links in a few different places, so here they are. he also found one other on topic article. the first link is to a thread were he posted the first 2 articles. the second link is to his thread were he posted the remaining article and the additional article that he found.

https://www.icmag.com/ic/showpost.ph...&postcount=169

https://www.icmag.com/ic/showthread.p...17#post4092817

[spurr]

Originally Posted by Cannabologist

- As far as I am aware, both exposure to air (oxygen), light (heat), and time in general will degrade THC to CBN.

According to the following book, David Pate claims that harvesting and drying, and storage of cananbis (or extracts), if under light, is best done under yellow light to have the least deleterious effect upon cannabiniods (I assume that means conversion of THC into CBN, etc). That said, the effects of other spectrum of light in PAR range do not have a great effect upon THC > CBN conversion AFAIK.

"The medicinal uses of cannabis and cannabinoids"
By Geoffrey William Guy, Brian Anthony Whittle, Philip Robson
section "Harvest and Drying" (page 49).
https://books.google.com/books?id=Azn...ed=0CDYQ6AEwAw

Originally Posted by Cannabologist

- Environmental factors like light color can influence THC and cannabinoid production either positively or negatively during growth, though not by enormous amounts.

That is true if referring to various spectra within PAR range (ie. 400-700 nm), see the paper you and I both uploaded on that topic. However, in terms of light, UV-b has a strong effect upon increasing THC production in cannabis (see what I have posted in the UV-b thread).

Along with light, nutrients (i.e. nitrogen) and temperature have rather notable impacts upon THC accumulation.

Originally Posted by Cannabologist

- THC and cannabinoid content is largely genetically controlled.

Cannabinoid amounts (quantitative) is a phenotypic trait that is strongly affected by the growing environment, fertilizers, etc. And cannabinoid ratios to other cannabinoids (i.e. chemotype; normally qualitative) is a genotypic that is not strongly affected by the growing environment, fertilizers, etc.

Originally Posted by Cannabologist

-I have seen work done on the rate of conversion and will try to post a reference.

That would be great, looking forward to it.

[spurr]

Originally Posted by MrBlue2

Its best to harvest your plants in the dark. Most of the starches in your plant will be in the roots during the dark cycle. if you harvest with the lights on the starches will be in the buds and leafs aiding in photosynthesis. this will result in harsher smoke.

Not to my understanding, where do you find that info? AFIK, only < ~25% of the photosynthetic assimilate (e.g. carbohydrates/starches) produced by the plant is moved into the roots regardless of day or night. Light independent reactions of C3 plants entail various functions, such as conversion of photosynthetic reactions into starch (that happens in light and dark).

[spurr]

Originally Posted by MrBlue2

I use a green LED head lamp when i harvest. before i had a geen LED head lamp i just fumbled around in the dark.

FWIW, the claim that plants can't "see" green light is a total myth. In fact, green light drives rate of photosynthesis very well. Under high irradiance white light (e.g., intense light levels under an HID) green light has been found to drive rate of photosynthesis more than blue light and red light due to issues of green light's activity upon chloroplasts in lower section of leafs. I have written quite a lot about this topic, and the error of using the "chlorophyll A/B absorption spectra" curve. If you are interested do a search here with my nic "spurr" and "green light".

Under common sunlight irradiance levels (i.e. < ~1,000 PPFD), around 50% of green light is reflected, and the remainder is used (in part) for photosynthesis.

Originally Posted by MrBlue2

I know some growers who recommend 24 to 48 hours of uninterrupted darkness before harvest. I tried it and didn't think 48 hours of darkness was that much different then 10-14 hours of darkness.

Me too, that claim of long darkness is just silly in terms of increased cannabinoid content. The only thing I can think of that would make smoke less harsh from 48 hours of darkness is possible reductions in chlorophyll levels.