ganjaments
Member
Is there any available data on how different (visible) light spectra affect THC Degradation (both pre and post harvest)? e.g. what is the best kind of light to use during and after harvest to minimize potency loss?
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Visible Light & THC Degredation?
- Thread starter ganjaments
- Start date
- As far as I am aware, both exposure to air (oxygen), light (heat), and time in general will degrade THC to CBN.
-More exposure to more factors will hasten the conversion process.
- Environmental factors like light color can influence THC and cannabinoid production either positively or negatively during growth, though not by enormous amounts.
- THC and cannabinoid content is largely genetically controlled.
- Realistically, amounts of loss (conversion of THC to CBN) over time will be negligible.
*Example;
- Smoking 2 of the same sample side by side, you will not notice a difference in effect unless doing a comparison of fresh product to something years and years old.
-I have seen work done on the rate of conversion and will try to post a reference.
-More exposure to more factors will hasten the conversion process.
- Environmental factors like light color can influence THC and cannabinoid production either positively or negatively during growth, though not by enormous amounts.
- THC and cannabinoid content is largely genetically controlled.
- Realistically, amounts of loss (conversion of THC to CBN) over time will be negligible.
*Example;
- Smoking 2 of the same sample side by side, you will not notice a difference in effect unless doing a comparison of fresh product to something years and years old.
-I have seen work done on the rate of conversion and will try to post a reference.
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.
Back to you question, UV light is the only type of light that i know of that will break down THC on living or chopped plants. Its pretty much always best to dry in the dark. dont worry about turning on the light in your drying room if its just a regular light bulb it wont mess anything up. Basically just dont dry your plants in sunlight or under a MH or anything crazy like that.
also the temp in your drying room should be between 65-75 degrees and the RH should be between 45-55%
ganjaments
Member
Do you have a link for this? It was my understanding that people harvest before lights on to obtain peak potency, before it has a chance to degrade from HID's?
So a UV-Free lamp would be the best to use during and after harvest?
Some people are pretty anal about light exposure (ever see a duct taped stash jar?), and having hard data on this would be quite helpful to quantify those concerns.
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. After I harvest I just have my regular house lights on (for hanging and later trimming). I always try to harvest right before the lights flip on or I flip the breaker on the subpanel to my room and leave it dark until i get around to harvesting. 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. but if duck tape on your jars makes a difference to you then maybe the extra darkness will make a difference to you as well. I notice a difference in harshness in my smoke when i harvest with the lights on, there may be a difference in potency as well but i have never noticed it.
I think I read about the starches and harshness thing and the UV thing in Jorge Cervantes's grow bible or one of the ask ed books. Unfortunately I dont have either with me right now (and wont until after x-mass) so i cant be sure of which book or give you any direct quotes.
ganjaments
Member
MrBlue2 - Please don't take this the wrong way, but I am looking for actual data not anecdotal evidence. Why do you use a green LED instead of a UV-Free LED? Why do you then switch to regular house lights? What benefits is the 24-48h dark period supposed to give in relation to post-harvest potency loss? Do you have any data whatsoever showing a detectable difference using a Green, Red, Blue, UV-Free or any other light?
I think the data your looking for doesn't exist. the question your asking is similar to, "how long does it take to get a sun burn?" I think if you do a little research on light you would find the answer your looking for. Green, Red, blue, and yellow light in there pure forms are all in the infrared spectrum. this means that they are all UV free. purple and violet light split the spectrum and have a little bit of UV light. the original meaning of ultra violet is beyond violet or everything darker then violet.
Prolonged exposure to HID lights, tanning bed lights, sun light, and UV lasers are the only sources of light that I know of that will degrade THC at a detectable rate. In other words, it makes no difference if you put duck tape on your jar, unless you leave your jar in a tanning bed or out in the sun for hours at a time.
I left out black lights from the list because they lack the intensity needed to cause damage in any reasonable amount of time.
If this answer isn't to your satisfaction, you could always do your own experiment. take five identical jars and put a gram of weed in each. Duck tape one and put it in a dark place as a control. Then put one of the remaining four jars in one of the following places. under an HID light, in direct sunlight, under a black light, and the last one should be placed in normal lighting conditions in your house. leave all of the jars in there places for the same amount of time (at least a couple of hours) then collect them all and put them in complete darkness until tested. If you want to be a little more accurate you could do twice as many jars and tape half to give you more controls and make sure other factors like heat aren't messing up your results.
also
as stated above a green LED is uv free. I use a green LED because the plants dont react to it and it will not interrupt their photo period.
and
I use house lights because those are the lights in my house. I think they are CFLs(the energy saver ones) or incandescents.
this too
You mentioned earlier that people harvest right before lights on because they want to chop before the HID lights begin to degrade the THC that has been forming overnight. This makes since to me. I was also under the impression that harvesting right before lights on will make your smoke less harsh. If one or both of these things are true then wouldn't it also make since to let the plants have a little extra darkness (24-48 hours), to let them make more THC and/or allow the starches to further evacuate the buds.
Peace, Mr. Blue
ganjaments
Member
Do you have a source for this, so that I may read more?
bendoslendo
Member
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: http://www.erowid.org/plants/cannabis/references/journal/cannabis_degradation1.shtml
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...
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
Thanks!!! I just posted them up there. Hopefully he'll have them soon.
ganjaments
Member
Thanks for posting in the other thread MrBlue2.. Hopefully spurr can help us out with some reading materials.
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
http://www.icmag.com/ic/showthread.php?p=4092817#post4092817
https://www.icmag.com/ic/showpost.ph...&postcount=169
http://www.icmag.com/ic/showthread.php?p=4092817#post4092817
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).
http://books.google.com/books?id=Az...ook_result&ct=result&resnum=4&ved=0CDYQ6AEwAw
By Geoffrey William Guy, Brian Anthony Whittle, Philip Robson
section "Harvest and Drying" (page 49).
http://books.google.com/books?id=Az...ook_result&ct=result&resnum=4&ved=0CDYQ6AEwAw
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.
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.
That would be great, looking forward to it.
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).
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.
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.
