More THC testing – UVA vs UVB vs near-UV

wietefras said:

It could simply mean that the plants under light spectrum "A" needed a while longer to fully ripen.

Perhaps UV slows down ripening a tiny bit.

Click to expand...

It is possible. In the Or_Gro test three of the tents with supplemental UVB finished at the same time, but the High Light tent with no UVB finished a week earlier. Cannabinoid and terpene tests showed the High Lights with near-UV were up there with the other tents (second overall) and the yield was almost the same despite finishing a week earlier (11 weeks vs 12).

cobshopgrow said:

Cannbioid concentration can differ quite a bit over the plant.
i sadly cant find it anymore, but there was a research paper from israel comparing the impact of growth hormones and how it relates to the distribution of cannabioids in lower and upper buds.
if i remeber correct natural growen plants show a higher concentration in the upper parts.

Click to expand...

If UVA/B and near-UV play their part in photomorphogenic response then that's probably what you would expect, as shorter wavelengths don't penetrate the canopy as much. So perhaps it's a simple as that.

hybridway2 said:

I have read the uvb (even low levels) on all day causes the plant to build a resistance. Defeating the purpose. It probably does in the sun too.
That's one reason why growers use timers & blasts on their UVB.
Glad you guys are doing these tests.
I have often wondered the thc difference between my leds & hps. With the assumption my leds are producing higher levels then the hps by using my senses. I credditted the extra blue or 450+470nm.
Have never been a fan of experimenting much with UVB myself & have always wondered why scientists or grow light companies have always told us the uva is not going to change the thc or other cannabinoids? Why only UVB?
Meanwhile they are not even providing us 400-430, or UVA. And because of the "Scientific Studies" most growers/companies only focused on UVB as their extension to the spectrum at hand.
The tests you are doing shows us this is not true & we do not have to stress or guess our plants with uvb bulbs. Possibly using them wrong.
Many growlight companies are simply going to look past the 400-430 zone & go straight to UVA this yr. For some they are just getting around to n/ir.
But here's the problem with that. As we all know it takes a combo to create the Synergistic Emmerson Effect.
Lack of scientific studies does not explain the Synergistic effects of the other end of the spectrum. They do exist, I'm sure of it.
The whole thing is about balancing this Synergy to me.
You have opened a new realm here by providing test results & running combos.
I mean what other company would toss a cmh in the in the mix if they have the assumption it may outperform the thc #'s of the board alone. And share info.? Not many dude. Granted that is not this past test but you know what i mean.
Kudos to you & your team. That goes for you Prawn.
And thank you!

420 & uva are the only x2 things i wanted added to my existing system for a minute.

Took Balls to attempt & succeeded to make a competitive/efficiency board with Optisolis's.

Curious to the difference between the CMH vs the Highlight board alone. That should indicate whether the less efficient UVA diode is even worth it to some.
I have a feeling the broader spectrum alone might give you darn close to that of the regular white + uva hitting the mkt this yr.

I would be happy to run this test & return or purchase the boards after.
Hmu if interested?
Having other common HE units as well as HPS/MH, we could run tests in parallel. I could sacrifice at least x3, 4.5x4.5 areas to do the test with dividers in the name of science. Oh, we could also test to a light that has 385nm but nothing filling in to 450nm (this yrs new spectrum) That would be the x3 tests at once.
Nothing to do with endorsements of any product by me. I would even keep my opinions to myself n just record.
Simply studies with tests in equal parameters to gain knowledge.

Thanks again for openly sharing your findings repeatedly.

Click to expand...

We do have spectrographs of the CMH on its own and mixed with the High Red boards.

CMH (2x 315W)


CMH + High Red @ 5:2 ratio (630W of CMH, 240W of LED)


These CMH lamps have a very good spectrum already and are proven performers, but the High Lights do add a bit more red and also fill in the gaps. The grower says he has had better results since adding LED to his grows.

On the subject of further tests, we do have those areas covered – but thanks for offering. The grower above has just bought four High Light UV boards with heatsinks and two 320 drivers to run in another tent, so it should be a fairly even test if we can get him to run just 630W of CMH and 640W of LED. We will definitely be able to see the difference between CMH and near-UV grown under the same conditions. That will be the real acid test for us, as CMH seems to be the industry standard when it comes to cannabinoid and terpene production. That's what the CMH guys keep telling us

Have you done any cannabinoid testing in your grows? If so, have you seen much of a difference in your grows since using LED?

I've been following your work with great interest and commend you on all your efforts. I have my main lighting set up satisfactorily, but wondered if you have considered producing a UV only lamp (like HLG's offering). I have 100 sq ft of canopy so theirs is a bit pricey! I have an unopened box of 8 Solacures I'll install in a few weeks (in the middle of harvest now) so I'll see what they do.
Here's an interesting read from a lighting company I hadn't heard of, discussing the uvr8 pathway and the synergy of uva and uvb.

Grow Lights Australia said:

If UVA/B and near-UV play their part in photomorphogenic response then that's probably what you would expect, as shorter wavelengths don't penetrate the canopy as much. So perhaps it's a simple as that.

Click to expand...

can be, another point is that plants expect the bees at their tops and therefore spend the most energy in there.
the study i refering to (someone know it also and have the link?) was likely outdoor in israel.
beside what the light have as effect they studied the influence of a hormone and the overall thc amount of the plant.
the overall thc amount stayed almost the same but with added hormones the distrivution in the plant where more equal.

this doesnt help us much here, its just sad that not all probes where top buds to take out some guesswork.
great test otherwise!

nDanger said:

I've been following your work with great interest and commend you on all your efforts. I have my main lighting set up satisfactorily, but wondered if you have considered producing a UV only lamp (like HLG's offering). I have 100 sq ft of canopy so theirs is a bit pricey! I have an unopened box of 8 Solacures I'll install in a few weeks (in the middle of harvest now) so I'll see what they do.
Here's an interesting read from a lighting company I hadn't heard of, discussing the uvr8 pathway and the synergy of uva and uvb.

The MetaRail™ UVB+A Lighting Instrument — AgricUltra™ Advancements

The MetaRail is designed to deliver the industry’s most advanced UV spectrum and power density in the optimal ratio of UVA:UVB wavelengths to optimize plant attributes—such as improving flavour in strawberries and increasing THC levels in Cannabis plants.

www.agricultra.com

Click to expand...

We have been reading up on UVR8 and while I would never profess to be an expert, the main issues we see with it are that 280-290nm is very strong and has the potential to do much DNA plant damage in a very short amount of time – as well as being dangerous to humans – and that UVB LED sources are expensive and have very short lifespans (I am surprised to see that link claiming 20,000 hours for 285nm LED L70 lifespan). There is also the question of how much photomorphogenic response there is compared to running UVA or near-UV throughout the cycle. That is partly what we are trying to resolve with these tests.

Almost no 285nm light reaches earth, which is possibly why UVR8 receptors are so sensitive. In fact, we have noticed an interesting trend that many of the most sensitive photoreceptors in plants coincide with pronounced dips in natural sunlight spectra: 400nm, 430nm, 680nm, 720nm etc (this is probably a subject that needs a thread of its own).



We have no plans to produce a UVA/B strip, but Cutter at @welight can build them to order if you are interested and LED Teknik will be coming out with a near-UV (400 + 420nm) "Buddies" LED at some point. But he won't be making UVA Buddies as far as I know (he might if there is demand).

cobshopgrow said:

can be, another point is that plants expect the bees at their tops and therefore spend the most energy in there.
the study i refering to (someone know it also and have the link?) was likely outdoor in israel.
beside what the light have as effect they studied the influence of a hormone and the overall thc amount of the plant.
the overall thc amount stayed almost the same but with added hormones the distrivution in the plant where more equal.

this doesnt help us much here, its just sad that not all probes where top buds to take out some guesswork.
great test otherwise!

Click to expand...

I'm aware that all the samples were taken from SCROG style grows, so I'd imagine that even if one came from the lower canopy, we're not talking about tall plants with a large difference in canopy exposure. But I would have to ask @Prawn Connery about this. It is certainly possible that there does not need to be a large difference in canopy exposure to produce different results, as UVB does not penetrate deep into the canopy. But we will take note of all this for the next round of tests.

Grow Lights Australia said:

We do have spectrographs of the CMH on its own and mixed with the High Red boards.

CMH (2x 315W)
View attachment 4530265

CMH + High Red @ 5:2 ratio (630W of CMH, 240W of LED)
View attachment 4530267

These CMH lamps have a very good spectrum already and are proven performers, but the High Lights do add a bit more red and also fill in the gaps. The grower says he has had better results since adding LED to his grows.

On the subject of further tests, we do have those areas covered – but thanks for offering. The grower above has just bought four High Light UV boards with heatsinks and two 320 drivers to run in another tent, so it should be a fairly even test if we can get him to run just 630W of CMH and 640W of LED. We will definitely be able to see the difference between CMH and near-UV grown under the same conditions. That will be the real acid test for us, as CMH seems to be the industry standard when it comes to cannabinoid and terpene production. That's what the CMH guys keep telling us

Have you done any cannabinoid testing in your grows? If so, have you seen much of a difference in your grows since using LED?

Click to expand...

I have seen it, smelled it, tasted it & am told by all patients. But to answer your question, no, i have yet to get testing done. Never seam to hold long enough. Lol!
Do intend to this following run with x2 SBS's. One comparing x2 lights & one comparing the same light using x2 plants. One organic & one using Jacks. Will organic growing have a higher thc or cannabinoid content i. Curious.
Yeah, the 5:1 mix looks sweet.
My next purchase will be a spectrometer or passport as well as a 3-4' ppfd bar. Have the MQ-620 Now, getting ready for the new led spectrums to hit this yr.
My biggest curiosity rn is the difference between a HighLight board (s) vs that of new led spectrums like this that are still lacking under 440 & 470nm but have the 385nm + 730.
That is Hortrilux's new led bar light. 16% outside the normal Par region. Lil excessive IMO & not the spectrum ill be using but close enough to understand my point here.
How will the broad range HighLights compare in testing as well as growth traits.
IF one can accomplish a near 20% increase using both of these spectrums.
The next move is combining them HighLight + 385nm to see the results & how they line up against the Cmh or +HighRed boads combo.
Cool! Im sure there's a line of growers who are willing to pay & test. Can't beat that!
I do believe this series of testing is worth considering & will benifitt us immensly, whomever is doing it.
Testing beyond the Horticultural led basics scientists are beginning to study now.
Will be interesting to see equal wattage comparison. Highlight Will outyeild x2, 315's, but you'll also get to check the cannabinoids/thc's.
Staying tuned!
Good Work!

Something to consider.
I know you spaced your diodes & may or may not be having the issues other QB style lights teand have on many plants.
But here's something my own current findings found to be dead true.
We think multiple lil diodes are diffusing enough but they are just lil laser beams that hurt.


Take what you want from it but i found this to be Very True. Even reduced growth & yellowing down to low par #'s vs a covered les with much higher par #'s. Same plant in sections. 5x5 plant. 96 Elite used for accidental test. Plenty more to back that in my room to.
But also several articles in relation.
Its not all about the par#'s/efficiency, but thats what sells lights over results to this day.
EDITTED:
If The small light loss grows more & healthier plant then is it really a light loss Said one tree to another in the forest.

Grow Lights Australia said:

400nm, 430nm, 680nm, 720nm etc (this is probably a subject that needs a thread of its own).

Click to expand...

yes yes - interesting! there's also peaks around 365nm 380nm and alot of secondairy plant metabolites reacto to basically all blue light. Then there are some strong peaks in the red spectrum and as good as nothing in the green spectrum - which is the spectrum which isn't absorb by chlorophyl that much and can therefore surpass a leaf more easy.
So if we just look at that entire platter is seems like plants have mainly receptors for both ends of the PAR bandwidth with even a further dive down along each raod with 730nm and 365nm & 380nm - so the plant can anticipate better on when a day begins or ends.

Grow Lights Australia said:

View attachment 4530463

Click to expand...

hmmm what exactly is the reason that bandwidth around 460nm acts so untouched by the environment? the way everything aligns at 100 makes it looking like a statistical error of some sort... (?)

PS:
I think the buddies waterproof caps make it impossible to let UV through?

near UV and some UVA will pass with no problem.

Kassiopeija said:

hmmm what exactly is the reason that bandwidth around 460nm acts so untouched by the environment? the way everything aligns at 100 makes it looking like a statistical error of some sort... (?)

PS:
I think the buddies waterproof caps make it impossible to let UV through?

Click to expand...

It is effected, they have just used it as the zero point for that graph. To compare all the peaks and troughs in those graphs, you have to divide them by their area under the curve. The more area under the curve, the weaker the peak. So 460nm would be weaker in the afternoon light as it has the same 100 peak, but there is more area under the curve.

As to why they used 460nm, it could because it's the blue sky spectrum (450-485nm), or perhaps because it's also the most sensitive area of the human eye (which evolved under the "blue sky spectrum").

Grow Lights Australia said:

I'm aware that all the samples were taken from SCROG style grows, so I'd imagine that even if one came from the lower canopy, we're not talking about tall plants with a large difference in canopy exposure. But I would have to ask @Prawn Connery about this. It is certainly possible that there does not need to be a large difference in canopy exposure to produce different results, as UVB does not penetrate deep into the canopy. But we will take note of all this for the next round of tests.

Click to expand...

I can't remember which parts of the plant I took my samples from, but you're right that all of them were pretty short, squat plants. I really can't offer any explanation for why the UVB sample was so high in CBG and so low in THC.

Prawn Connery said:

I can't remember which parts of the plant I took my samples from, but you're right that all of them were pretty short, squat plants. I really can't offer any explanation for why the UVB sample was so high in CBG and so low in THC.

Click to expand...

Is cbg created in relation to the breakdown of thc from being sensitive to uvb maybe?
I dunno.

What are your thoughts on UV 365nm..?? - STELTHY

hybridway2 said:

Is cbg created in relation to the breakdown of thc from being sensitive to uvb maybe?
I dunno.

Click to expand...

No, as @wietefras said CBG is the precursor to CBGa (the acidised form) which is the precursor to other cannabinoids such as THC and CBD.

FADING-SILHOUETTE said:

What are your thoughts on UV 365nm..?? - STELTHY

Click to expand...

There is a good amount of easy-to-read information here: https://darkgreensingularity.com/cannabis-production-science-research/

And here: http://biology.mcgill.ca/Phytotron/LightWkshp1994/3.3 Hashimoto/Hashimoto text.htm

The TLDR version is that 365nm is a sub-peak of <450nm spectral peaks including cryptochrome and phototropin, as well as phytochrome red (Pr), so it is believed to either have a synergistic effect when combined with those primary peaks, or may replace them in their absence (read below).

An example of this is in the second link above which details an experiment where spinach was grown with and without UV(A/B) light. Broad-spectrum UVA/B was found to inhibit growth, whilst the addition of 365nm (with no other UV) promoted growth. UV has been proven to counter shade-avoidence, which is controlled predominantly by the Red:Far Red ratio. This would make sense if the 365nm absorbance peak has a synergistic effect to convert higher amounts of Pr to increase the R:FR ratio in plants. But it has also been shown to inhibit growth and yields.

Looking at the graph below you can see cryptochrome peaks at 405nm, whilst there is a secondary phytochrome Far Red peak also at 405nm. So it seems UVA (365nm) works best in combination with blue light <450nm. Also, if the desire is to increase the Emerson Effect (synergistic relationship between Pr and Pfr), then perhaps the same can be achieved with the addition of 405nm, as LEDs usually have a very high R:FR ratio anyway. In which case you may not want the synergistic effect of 365nm that would otherwise increase the R:FR ratio. Sunlight has a ratio of about 1:0.7 R:Fr (it changes through the day and seasons), whilst typical 450nm peak "blue pump" LEDs have a ratio closer to 6 or 7:1 – which is very high when you think about it. And probably why plants grow a lot shorter and denser under LED than other forms of light.

As to THC and other cannabinoids, there are test results here showing a combination of 285nm (UVR8 ) and 365nm increases THC: https://www.agricultra.com/uvr8-chemical-profile-shaping-in-cannabis

However, the results appear marginal (2-11% increase) and the most interesting thing about those tests is it appears there was no near-UV or deep blue light in the overall spectrum <450nm – so would it perform better with the addition of near-UV, or would near-UV alone be sufficient? The Or_Grow test (and other scientific tests such as this one: https://www.karger.com/Article/Fulltext/489030) showed that the addition of <450nm light increased cannabinoids by at least 20%, whilst further testing is starting to show the same results: that near-UV can have as much effect (or more) on cannabinoid production as the addition of UVA and UVB and possibly without impacting yields. (I say "possibly" as we haven't really proven it, even though the near-UV tests also outyielded the UVA/B tests.)

There's a lot going on between 400nm and 450nm and very few LEDs cover this range. So if results with 365nm do show an improvement in growth, cannabinoid or terpene levels, then how do we know that 365nm is not simply making up for the lack of 400-450nm in typical leds in the first place? Perhaps the real test is to add 365nm as well as 400-450nm.

Put the led wavelength add ins to be both in the 400-430 nm and 730. Forget the 365, the sun spectrum has so little that the best bang for your buck would be 400-430 and 740 in the same intensity ratio as the sun. Put both those in and run the test. Without fr and ir plants remain short, without uva plants stretch, together you get a balance in plant morphological response and acts synergistically.

Prawn Connery said:

I can't remember which parts of the plant I took my samples from, but you're right that all of them were pretty short, squat plants. I really can't offer any explanation for why the UVB sample was so high in CBG and so low in THC.

Click to expand...

Could it be that the plant gets more uvb in early to mid flower in nature but you added it thru all flower stages? The precursor to thc, cbg is generated with a higher cct. So too much uvb which put the plant into early to mid flower while your timeline for 12/12 was more mid to late flower. Meaning your timeline for flower didnt match the plants timeline for maturing and converting cbg to thc.

Grow Lights Australia said:

There's a lot going on between 400nm and 450nm and very few LEDs cover this range. So if results with 365nm do show an improvement in growth, cannabinoid or terpene levels, then how do we know that 365nm is not simply making up for the lack of 400-450nm in typical leds in the first place? Perhaps the real test is to add 365nm as well as 400-450nm.

Click to expand...

exactly and therefore it may seem a good idea to instead go for the blue bandwith as youll be delivering PAR instead of UV heat, but Im afraid your trading weight for quality, in fruits even greater health potential. The secondairy plant metabolites do also affect taste & scent.

I wonder why green 550nm isnt such an attractiv wavelength to outfit boards. Since its more penetrating, it will reach deeper into the plants and cause less top heat. Not that I know much about available chips on the market...

btw the graphic is broken

Bignutes said:

Put the led wavelength add ins to be both in the 400-430 nm and 730. Forget the 365, the sun spectrum has so little that the best bang for your buck would be 400-430 and 740 in the same intensity ratio as the sun. Put both those in and run the test. Without fr and ir plants remain short, without uva plants stretch, together you get a balance in plant morphological response and acts synergistically.

Click to expand...

It's true. And this is what makes me wonder about 285nm, as there is almost none in natural sunlight and even then only the most minute part in high UV areas, such as the equator (admittedly where cannabis evolved). I'm sure you wouldn't need much of it to see an effect. But I'm not sure how much effect is to be had and the risks vs rewards are would need to be weighed. I'm not about to rule something out tat we haven't tried ourselves.