PSA: UV-B bullsh*t

[UV-B.bs]

UV-B has not shown any worthwhile benefit to cannabis from a handfull of recent studies. None.

So please help me spread the word: UV-B increasing THC is bullshit.

These data support recent literature and lead us to conclude that an elevated flux of UV photons is not an effective approach to increase cannabinoid concentration in high-cannabinoid cultivars.

Frontiers | Elevated UV photon fluxes minimally affected cannabinoid concentration in a high-CBD cultivar

Ultraviolet photons (UV) can damage critical biochemical processes. Plants synthesize photo-protective pigments that absorb UV to minimize damage. Cannabinoi...

www.frontiersin.org

 

[Creeperpark]

UV-B has not shown any worthwhile benefit to cannabis from a handfull of recent studies. None.

So please help me spread the word: UV-B increasing THC is bullshit.

Frontiers | Elevated UV photon fluxes minimally affected cannabinoid concentration in a high-CBD cultivar

Ultraviolet photons (UV) can damage critical biochemical processes. Plants synthesize photo-protective pigments that absorb UV to minimize damage. Cannabinoi...

www.frontiersin.org

Interesting. Thanks for the heads-up friend.

 

[Diggy_Soze]

You made a whole account to devote to the subject?…
okay…

Anyway.

THC has always been overhyped. Any and all plants hit with UV light, not just weed, have been shown to produce different compounds, or in different concentrations, in response to UV. We’ve just not put enough effort into finding out specifics because it’s not THC.

Nowadays, when you can get a kilo of THCA for a couple bucks, maybe we’ll start to see more research into the non-psychoactive compounds. The cuticular waxes, the saponins, the flavonoids, the acids and oils and all that.

It’s already been established that leaf trichomes have different ‘ingredients’ than flower trichomes, next step is to look outside of cannabinoids, and outside of smoking the flower. A whole plant extract, and I do mean whole plant, will produce an entirely different product than a 35% thc flower.

 

[UV-B.bs]

Interesting. Thanks for the heads-up friend.

You're welcome. There are other recent papers that came to same conclusion (lack of statistical significance) below. There is one application method for UV-B that may (although unlikely) yield beneficial results using intermittent UV flux. For example, every other day for a short period to reduce DNA damage and prevent the plant from synthesizing protective compounds to reduce UV absorbance. There is some research on going in that regard, but it's not especially promising.

Frontiers | Cannabis Inflorescence Yield and Cannabinoid Concentration Are Not Increased With Exposure to Short-Wavelength Ultraviolet-B Radiation

Before ultraviolet (UV) radiation can be used as a horticultural management tool in commercial Cannabis sativa (cannabis) production, the effects of UV on ca...

www.frontiersin.org

Frontiers | Indoor grown cannabis yield increased proportionally with light intensity, but ultraviolet radiation did not affect yield or cannabinoid content

Cannabis (Cannabis sativa) flourishes under high light intensities (LI); making it an expensive commodity to grow in controlled environments, despite its hig...

www.frontiersin.org

 

[UV-B.bs]

You made a whole account to devote to the subject?…
okay…

Yup because lots of people buy worse than useless UV lights, that UV damages their plants' DNA and reduces plant growth without benefit in most cases. Plus UV typically has a negative effect on terpenes and other secondary metabolites (what you call "ingredients") as the terpene profile of UV control plants is not simply increased across the board, many terps we want are reduced and some we don't want are increased.

And the rest of your message has nothing to do with the subject at hand.

 

[Diggy_Soze]

And the rest of your message has nothing to do with the subject at hand.

Why, because thc is the only compound in cannabis you’re concerned with? Lmfao…
You say without benefits, but you’re basing that entire premise on studies that measure the changes in yield. These are not quality measurements.

You’re pretending to be an authority on the subject but you’re suggesting that THC% is the be all end all of quality. It’s profoundly naive, considering we have an excess of dispensaries selling wack ass flower that tests at >30%.

Ultraviolet radiation changes plant color

Plant absorption of ultraviolet (UV) radiation can result in multiple deleterious effects to plant tissues. As a result, plants have evolved an array of strategies to protect themselves from UV radiation, particularly in the UV-B range (280–320 nm). ...

www.ncbi.nlm.nih.gov

“A major defense mechanism against UV-B radiation is the increased production of flavonoids, and other phenolic compounds in plant epidermal layers to provide UV-absorbing sunscreen”

Cannflavin A and B for example are just two molecules not yet found in any other plants, and you disregard it because it doesn’t get you high.

https://www.sciencedirect.com/science/article/pii/S0031942218303819

You can buy thc cheap, dude. Grow up. Cannabis is far more than just THC.

 

[mexcurandero420]

I miss the terpene section in this study and T5 light bulbs as a light source

 

[Dime]

THC claim is a great marketing tool that works on the same people who are impressed by how "frosty" their plants are.

 

[amanda88]

you joined the worlds largest weed site just to slag a well known understanding
had this come from an established member then you may carry some weight, but you don't, shame on you
I and many here will stick with current common science rather than myth

Spoiler

1. 00:14 Apogee makes a couple different sensors to measure UV light.
2. 00:40 The electromagnetic spectrum and UV wavelengths – UV-A, UV-B, and UV-C.
3. 02:47 How much of these wavelengths are in sunlight? And how do those photons cause sunburn? 04:44 The erythemal response curve: one photon in UV-B is equal to 100 photons of UV-A.
4. 04:58 The glass in greenhouses filters out most UV-B and UV-C wavelengths.
5. 05:41 How does the erythemal response curve look for plants?
6. 06:27 Some beneficial effects of UV-A.
7. 07:09 The effects of UV-C, UV-B, and UV-A from Bruce’s research. It all depends on “dose.”
8. 07:47 A good rule of thumb is some UV is good for people – it’s just the right amount. And some UV is good for plants – it’s just the right amount.
9. 08:48 A more in-depth look at the sensors Apogee makes to measure UV light: UV-A (SU-200), spectroradiometer, and ePAR.
10. 10:20 With the correct dose of UV light, there is strong potential to improve plant quality.

thanks you for your understanding

 

[right]

I don't know. Back in the 80s or 90s? I added a mercury vapor lamp to my grow and it definitely increased the potency . Perhaps some of the data is missing.
But I can tell you from actual personal experience.
Perhaps it is only effective on equatorial sats. Because there is more uv in there natural environment.

 

[revegeta666]

THC claim is a great marketing tool that works on the same people who are impressed by how "frosty" their plants are.

Instagram people

 

[Rocket Soul]

That study has problems.
-They used uv treatment from start of flower on cbd rich plants, continued until end of flower 5 weeks later. Not really the same situation as most grows ive seen, how are you going predict about a 10 week grow with high thc plant based on an experiment done on 5week flowered cbd plants.
- They used a uv light with 55% uvb and 45% uva; most recommend higher uva than uvb; ive seen 3:1 been thrown around but dont know for sure the best amount, but what is clear is that theres much more uva than uvb in sunlight. Check out the spectrum:

If you add the 2 spectrums up you can see that coverage of blue and uv is minimal between 350 and 440nm. This is not a balanced spectrum, i think i recognize it as the "pure UVB" of whatever brand it was, i cant remember. Ive seen other tests where just basic UVA around 400nm beat this uvb tubes. From what i gather you need uva in order to harden the plants to take the uvb; you want it to slope downwards from more to less thru blue, uva and uvb, like nature.

- the study actually saw higher cannabinoid content with the uv treatment, 3-13%. Not sure whether this is total cannabinoid yield or concentration in flowers though. It was not statistically relevant results though, and the paper runs with that. But in their own results cannabinoids was higher when adding uv thru this application.
- somewhat less yield in the uv treatment. Which makes sense.

I havent read the whole study but there a few things that stand out to make me doubt that were seeing a full picture of whats going on in these results.

We are currently testing out uv in our grow, based on leds: 400/365/295nm, hoping to test the results. But the main take away when first giving uvb in very small dosis (5mins per hour x 4 at midday) was that the plants looked so much better almost immediately; very good plant stand with perfect plant stance. We accidentally left it on for 30mins; sader plants. Uvb definitely does something to the plant.
I know very well that "looked better" has very little scientific validity, just trying to share what were doing.

 

[Verdant Whisperer]

You made a whole account to devote to the subject?…
okay…

Anyway.

THC has always been overhyped. Any and all plants hit with UV light, not just weed, have been shown to produce different compounds, or in different concentrations, in response to UV. We’ve just not put enough effort into finding out specifics because it’s not THC.

Nowadays, when you can get a kilo of THCA for a couple bucks, maybe we’ll start to see more research into the non-psychoactive compounds. The cuticular waxes, the saponins, the flavonoids, the acids and oils and all that.

It’s already been established that leaf trichomes have different ‘ingredients’ than flower trichomes, next step is to look outside of cannabinoids, and outside of smoking the flower. A whole plant extract, and I do mean whole plant, will produce an entirely different product than a 35% thc flower.

I've looked into this and Limonene is increased in response to higher UV exposure to protect the plant like a natural suncreen. if you have more UV exposure theoretically it should increase the amount of limonene in that strain. I concluded this by comparing landraces from High UV locations to find common terpenes an flavors then looked into them and found that limonene is asscociated with protecting the cells from the uv damage, so i call it the plants sunscreen. In addition a study linked drought stress to higher levels of limonene as well as some other terpenes, but as the leaves become more brittle it makes sense they need more shielding from uv as well. so in theory additional uv and drought stressing your plants will increase limonene levels.

 

[Crooked8]

I saw bugbees video up there. I took his USU course and advanced course. They did a study on UV-A UV-B and UV-C and concluded that none of those nanometer wavelengths had any impact whatsoever on cannabinoids or terpenes. They showed all the data, it was very clear. Just figured id add this to the discussion as its only info you could learn from taking their course.

 

[JKD]

On this forum and RIU there was member named Phaeton who did some fairly extensive trials with and without UVb and also varying the UVb intensity etc. Regarding effect, his main finding was UVb inducing a creeper effect in both sativa and indica. At his preferred intensity it would also stunt growth, but not increase trichome production. IIRC the stunted growth results in increased trichome density. After 12 months of trials he added UVb to his main grow area. He was ahead of his time and a loss to this forum when he stopped posting.

 

[Verdant Whisperer]

I saw bugbees video up there. I took his USU course and advanced course. They did a study on UV-A UV-B and UV-C and concluded that none of those nanometer wavelengths had any impact whatsoever on cannabinoids or terpenes. They showed all the data, it was very clear. Just figured id add this to the discussion as its only info you could learn from taking their course.

I would like to see this study, I disagree with it, uv is going to encourage a stress response in the plant and the plant is going to make compounds to protect it, if the plant is not exposed to uv, nature is smart it is going to be as efficient as possible, no need to make additional terpenes associated with the plant. a lot of indoor strains are back crossed and really bred for a specific terpene profile and may have high amount regardless, but i bet if you took a clone of a strain know for a lemon flavor in a high uv location outdoors, and grew the same clone in a different environment with lower uv its going to have way different limonene levels, and how does the level of uv used in Comparision to the uv in the sun in a high uv environment if its 1% of the suns uv intensity than no results will be observed, a lot of experiments are done with an objective in mind and are very bias, no disrespect but i'm calling bs on their experiment.

 

[Verdant Whisperer]

On this forum and RIU there was member named Phaeton who did some fairly extensive trials with and without UVb and also varying the UVb intensity etc. Regarding effect, his main finding was UVb inducing a creeper effect in both sativa and indica. At his preferred intensity it would also stunt growth, but not increase trichome production. IIRC the stunted growth results in increased trichome density. After 12 months of trials he added UVb to his main grow area. He was ahead of his time and a loss to this forum when he stopped posting.

This is because the way grow lights and the sun work are differently the plants grow away from stressors it Doesn't want to get too close to the uv source so by knowing the bigger and taller it gets the more uv stress it diverts its energy into a denser and more compact structure resulting in more concentrated structure. as well as tighter and more concentrated bud and trichome structure as they use same hormones that dictate plant height. auxins, gibberellins, and cytokinin's.

 

[JKD]

~20% reduction in yield for flower from his preferred intensity. A big ask if not growing for headstash. He also side lit UVb rather than top lit as in nature it is equal strength in all directions. He applied ~130uW for the full 12 hour lights on.

I wish cannabis studies would also include qualitative findings rather than only quantitative, though I will continue to pick through those without.

 

[Crooked8]

I would like to see this study, I disagree with it, uv is going to encourage a stress response in the plant and the plant is going to make compounds to protect it, if the plant is not exposed to uv, nature is smart it is going to be as efficient as possible, no need to make additional terpenes associated with the plant. a lot of indoor strains are back crossed and really bred for a specific terpene profile and may have high amount regardless, but i bet if you took a clone of a strain know for a lemon flavor in a high uv location outdoors, and grew the same clone in a different environment with lower uv its going to have way different limonene levels, and how does the level of uv used in Comparision to the uv in the sun in a high uv environment if its 1% of the suns uv intensity than no results will be observed, a lot of experiments are done with an objective in mind and are very bias, no disrespect but i'm calling bs on their experiment.

No offense taken here friend im just relaying what i learned from their research. Not my research! I will say they spared no expense with this study. If they ever open up the class for a third run ill take photos of their data. Unfortunately, when its closed none of their info is accessible.

 

[Verdant Whisperer]

In addition to limonene, tannins and anthocyanins are responisble for uv protection in plants.. "Tannins are polyphenolic compounds found in various plants, including cannabis. They are known for their astringent properties, which can impart a dry, puckering sensation when consumed. Tannins serve various functions in plants, from defense against herbivores to protection against UV radiation." https://greenqueengenetics.blogspot.com/2023/09/tannins-in-cannabis-exploring.html and Anthocyanins:

Definition: Anthocyanins are water-soluble pigments found in plants, responsible for vibrant red, purple, and blue colors in various fruits, flowers, and leaves.

Functions:

• UV Protection: Act as a natural sunscreen, shielding plant tissues from damage caused by ultraviolet (UV) radiation.
• Antioxidant Properties: Protect against oxidative stress, helping to maintain the health of plant cells.
• Signaling: Play a role in cellular signaling within plants.
• Defense Mechanism: Deter certain herbivores, providing a layer of protection for the plant.
• Environmental Response: Anthocyanin production is highly responsive to environmental cues, including light intensity, temperature, and nutrient availability. They are produced in response to strong sunlight and UV rays.
• Water Absorption and Humidity Sensitivity: Since anthocyanins are more water-soluble, strains higher in them will be more susceptible to absorbing humidity in the leaves, which can affect the overall growth and health of the plant.
• Competition for Light Absorption: Anthocyanins absorb light primarily in the blue and red regions of the spectrum, which can overlap with the absorption spectrum of chlorophyll. In areas of overlap, there may be competition for available photons.
• https://greenqueengenetics.blogspot.com/2023/09/harnessing-carotenoids-and-anthocyanins.html