More THC testing – UVA vs UVB vs near-UV
- Thread starter Grow Lights Australia
- Start date
Rurumo
Well-Known Member
I don't trust much of what Solacure says, just because of the way their website looks like a multi level marketing scam and how they trash their competitors and try to justify it with dubious claims. Don't get me wrong, I think their bulbs are fine, I know a guy who uses them and I've seen them in action, but they don't seem much different than the agromax bulbs in terms of output. I like that they have the built in "reflector" though.
magnetik
Well-Known Member
regardless of what hoomans think.. nature doesn't work in absolutes. I'm pretty sure it doesn't work lik 286nm it's all good, no need for sunscreen.. 285nm.. ah shit, time to activate. There is some variability at play here. over and under. too much under and you're in UVC territory. 280nm is technically UVC fwiw.
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Prawn Connery
Well-Known Member
@Grow Lights Australia I think I'll answer this one, as this topic has been raised before.
This is the spectral absorption curve of UVR8. It's pretty impressive when you look at the peak around 285nm. It's even more impressive when you look at the inset graph that shows x10 detail of the UVR8 receptor tail.
What does it all mean? It means that yes, UVR8 is most sensitive to light around 285nm. And it has to be. Have a look at a typical sunlight spectral graph. I apologise for the smaller image, but it was the only one I could find that went down below 285nm.
The first thing you notice is how little UVB radiation below 300nm hits the earth – almost none! This is important, because it explains why the UVR8 photoreceptor is so sensitive to UVB light around 285nm – because in nature, there is hardly any light around that wavelength to begin with.
I'm sure we all understand that UVB radiation near the UVC range is VERY damaging to all DNA – including plants. So plants need to detect even small amounts of UVB in order to trigger the production of phenolic compounds to protect their cells against DNA damage.
The thing is, it's not just light around 285nm (short-wave UVB) that is damaging to DNA. All UVB and also UVA light are damaging to DNA. However, long-wave UVB (300+nm) and UVA (310+nm) are much more prevalent – therefore plants do not need to be as sensitive to this light, as there is more of it to trigger a phenolic (secondary metabolite) response.
Let's go back to that first graph now . . . have you noticed that the response curve has an inverse relationship to natural sunlight? That's no coincidence! The UVR8 receptor actually absorbs light as high as 420nm, which is in the violet range. So in fact, even though the absorption curve is most sensitive at around 285nm, the photoreceptor still abosorbs other light. It's just that there is more of that light, and therefore the receptor does not need to be as sensitive to detect it.
And that is why UVA light – even around 400nm – triggers a phenolic response in plants. Cannabis just happens to produce cannabinoids as part of its phenolic response (it also produces non-cannabinoid phenolics to protect itself from light damage).
I will finish this post by stating that you can do a lot of damage to plants by overexposing them to even small amounts of UVB – especially at lower wavelengths. So if you must use UVB, then use it sparingly. BTW, we believe that longer exposure to UVA has the same effect as shorter exposure to UVB – for all the reasons above.
^ This is not true. And I'm going to explain why.
This is the spectral absorption curve of UVR8. It's pretty impressive when you look at the peak around 285nm. It's even more impressive when you look at the inset graph that shows x10 detail of the UVR8 receptor tail.
What does it all mean? It means that yes, UVR8 is most sensitive to light around 285nm. And it has to be. Have a look at a typical sunlight spectral graph. I apologise for the smaller image, but it was the only one I could find that went down below 285nm.
The first thing you notice is how little UVB radiation below 300nm hits the earth – almost none! This is important, because it explains why the UVR8 photoreceptor is so sensitive to UVB light around 285nm – because in nature, there is hardly any light around that wavelength to begin with.
I'm sure we all understand that UVB radiation near the UVC range is VERY damaging to all DNA – including plants. So plants need to detect even small amounts of UVB in order to trigger the production of phenolic compounds to protect their cells against DNA damage.
The thing is, it's not just light around 285nm (short-wave UVB) that is damaging to DNA. All UVB and also UVA light are damaging to DNA. However, long-wave UVB (300+nm) and UVA (310+nm) are much more prevalent – therefore plants do not need to be as sensitive to this light, as there is more of it to trigger a phenolic (secondary metabolite) response.
Let's go back to that first graph now . . . have you noticed that the response curve has an inverse relationship to natural sunlight? That's no coincidence! The UVR8 receptor actually absorbs light as high as 420nm, which is in the violet range. So in fact, even though the absorption curve is most sensitive at around 285nm, the photoreceptor still abosorbs other light. It's just that there is more of that light, and therefore the receptor does not need to be as sensitive to detect it.
And that is why UVA light – even around 400nm – triggers a phenolic response in plants. Cannabis just happens to produce cannabinoids as part of its phenolic response (it also produces non-cannabinoid phenolics to protect itself from light damage).
I will finish this post by stating that you can do a lot of damage to plants by overexposing them to even small amounts of UVB – especially at lower wavelengths. So if you must use UVB, then use it sparingly. BTW, we believe that longer exposure to UVA has the same effect as shorter exposure to UVB – for all the reasons above.
Prawn Connery
Well-Known Member
On the money again mate!
In simple terms, even a small amount of 285nm has the potential for serious DNA damage, so as soon as the plant absorbs even a small amount, it is going to produce a phenolic response.
It also makes sense that the plant can absorb more of the longer wavelengths to produce the same response, as they are less damaging in short bursts, but have the same potential for damage in longer bursts. Therefore, the UVR8 receptoer does not need to be as sensitive to these longer wavelengths.
The absorption curve actually shows us this.
Prawn Connery
Well-Known Member
Haha! I watched that video and thought the same thing! Then I saw your post. You'd better watch out mate – you don't want to get on Shane's bad side, LOL!
Of course he's wrong about UVA and Far Red, as we've proven, but there are probably a lot of people out there who don't want to read that.
jimihendrix1
Well-Known Member
UVR8 Chemical Profile Shaping in Cannabis
UVB+A light on a dynamic spectrum allows growers to develop lighting schedules that shape terpene profiles and increase other secondary metabolites. This allows them to take common genetics and develop proprietary expressions far beyond what genetics can achieve alone.
”Significant new understanding of UVB mediated processes in plants has been gained during the last decade. As a result of improved experimental design and methods, the view of UVB radiation as a damaging agent has given way to a view where UVB radiation is considered as a specific regulator of gene expression, metabolite profiles, and responses to climate change for plants growing in sunlight. Recent genetic studies have revealed the existence of UVB-specific signalling pathways in plants, and have identified several components including a photoreceptor (UVR
. The discovery of these UVB-specific signalling pathways has confirmed the contention that UVB irradiance is a specific regulatory factor in plant-environment relationships. Research on the molecular basis of UVB mediated regulatory process in plants is now yielding novel understanding of the mechanisms underlying growth and phenotypic plasticity, and consequences thereof for plant performance in crop and natural ecosystems.”
www.uv4plants.org publications/uv-and-plants
Research has proven that 285 nm UVB triggers the UVR8 pathway, which increases the production of secondary metabolites that mediate many aspects of the interaction of plants with their environment such as acting as feeding deterrents against herbivores, pollinator attractants, protective compounds against pathogens or various abiotic stresses, antioxidants, and signalling molecules.
Increased Production of Specific Secondary Metabolites in Cannabis:
View fullsize
385 nm light is on the boundary of UVA and visible light. It is proven to increase cell wall thickness and health, making the plant more resilient against intense UV, pests, mold, and mildew.
Experiments have shown that 385nm UVA light makes the UVR8 photon receptor more susceptible to the effects of 285 nm UVB which means less energy is required to effectively trigger the UVR8 pathway.
Plants exploit blue and UVA light to drive DNA repair processes. Researchers have shown that DNA damage due to UV is mostly repaired by subsequent exposure to light in the blue or UVA range of the spectrum (Ref. 12). Blue light and/or UVA exposure activate an enzyme (photolyase) that repairs damaged DNA sequences.
The advantage of this system is that when plants are exposed to UVR, there is always a lot of blue light present. The involvement of blue or UVA light in this process is known as photoreactivation. Photoreactivation is the major defence against UV-induced damage in plants.
UVB+A light on a dynamic spectrum allows growers to develop lighting schedules that shape terpene profiles and increase other secondary metabolites. This allows them to take common genetics and develop proprietary expressions far beyond what genetics can achieve alone.
”Significant new understanding of UVB mediated processes in plants has been gained during the last decade. As a result of improved experimental design and methods, the view of UVB radiation as a damaging agent has given way to a view where UVB radiation is considered as a specific regulator of gene expression, metabolite profiles, and responses to climate change for plants growing in sunlight. Recent genetic studies have revealed the existence of UVB-specific signalling pathways in plants, and have identified several components including a photoreceptor (UVR
. The discovery of these UVB-specific signalling pathways has confirmed the contention that UVB irradiance is a specific regulatory factor in plant-environment relationships. Research on the molecular basis of UVB mediated regulatory process in plants is now yielding novel understanding of the mechanisms underlying growth and phenotypic plasticity, and consequences thereof for plant performance in crop and natural ecosystems.”www.uv4plants.org publications/uv-and-plants
Research has proven that 285 nm UVB triggers the UVR8 pathway, which increases the production of secondary metabolites that mediate many aspects of the interaction of plants with their environment such as acting as feeding deterrents against herbivores, pollinator attractants, protective compounds against pathogens or various abiotic stresses, antioxidants, and signalling molecules.
Increased Production of Specific Secondary Metabolites in Cannabis:
- Cannabinoids
- Terpenoids
- Flavonoids
- Stilbenoids
- Alkaloids
- Lignans
View fullsize
385 nm light is on the boundary of UVA and visible light. It is proven to increase cell wall thickness and health, making the plant more resilient against intense UV, pests, mold, and mildew.
Experiments have shown that 385nm UVA light makes the UVR8 photon receptor more susceptible to the effects of 285 nm UVB which means less energy is required to effectively trigger the UVR8 pathway.
Plants exploit blue and UVA light to drive DNA repair processes. Researchers have shown that DNA damage due to UV is mostly repaired by subsequent exposure to light in the blue or UVA range of the spectrum (Ref. 12). Blue light and/or UVA exposure activate an enzyme (photolyase) that repairs damaged DNA sequences.
The advantage of this system is that when plants are exposed to UVR, there is always a lot of blue light present. The involvement of blue or UVA light in this process is known as photoreactivation. Photoreactivation is the major defence against UV-induced damage in plants.
Prawn Connery
Well-Known Member
The response may be strongest ~285nm (and/or in synergy with ~365nm), but ALL light in the absorption spectra create pathways. This is perhaps what some people are missing. You only need a small amount of UVB around 285nm to trigger production of phenolics, but you can expose the plant to larger amounts of longer wavelengths (up to 420nm) to elicit the same response. That is what the curve is telling us.
If the UVR8 receptor was only triggered by 285nm, then there would be no absorption curve – there would be a spike right at 285nm.
Prawn Connery
Well-Known Member
Let's put this into human terms. If you are pale-skinned and stand outside at noon on a summer's day in outback Australia you will burn in 5 minutes. If you stand in the same place at 4pm you may burn in 30 minutes.
The result is you will burn.
The UV Index is not static and so high-intensity UVB radiation – whilst potentially damaging – only shines for a limited time. Lower intensity UVA radiation shines longer and so has the same or more potential to damage DNA, as it also penetrates cells more than UVB.
The result is you will burn.
The UV Index is not static and so high-intensity UVB radiation – whilst potentially damaging – only shines for a limited time. Lower intensity UVA radiation shines longer and so has the same or more potential to damage DNA, as it also penetrates cells more than UVB.
jimihendrix1
Well-Known Member
But you end up using less electricity, and bulb life is longer, if you dont have to run the bulbs as long. Thus you save money.
Also the whole idea is to stress the plant, and make it respond to the UVA/B.
NASA also did an experiment with weed on Skylab, that was in High Times around 73-74 using Xenon lamps. They used intense flashes of Xenon, that would slightly burn the plant, and they determined they could change the chemical profile of the plant by stressing it.
They flashed the plants 2x buring the budding cycle. I believe it was a Million, or more lumens.
What is the wavelength of xenon?
Xenon lamp provides high energy light source, and it can reach a steady state in a short time period. Its light covers the entire UV and visible wavelength range, from 190nm to 1100nm.
izakscientific.com
·
Nov 22, 2020
UV Grow Lights for Plants to grow: why and how it works?
Xenon Lit Plant Growth Chamber | Conviron
www.conviron.com/products/custom/xenon-lit-plant-growth-chamber/
Also the whole idea is to stress the plant, and make it respond to the UVA/B.
NASA also did an experiment with weed on Skylab, that was in High Times around 73-74 using Xenon lamps. They used intense flashes of Xenon, that would slightly burn the plant, and they determined they could change the chemical profile of the plant by stressing it.
They flashed the plants 2x buring the budding cycle. I believe it was a Million, or more lumens.
What is the wavelength of xenon?
Xenon lamp provides high energy light source, and it can reach a steady state in a short time period. Its light covers the entire UV and visible wavelength range, from 190nm to 1100nm.
izakscientific.com
·
Nov 22, 2020
UV Grow Lights for Plants to grow: why and how it works?
- Estimated Reading Time: 4 mins
Xenon Lit Plant Growth Chamber | Conviron
www.conviron.com/products/custom/xenon-lit-plant-growth-chamber/
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Speedtriplebbc
Well-Known Member
I did say a while ago I read about a synergy between these wavelengths, I saw this same picture in the article.UVR8 Chemical Profile Shaping in Cannabis
Experiments have shown that 385nm UVA light makes the UVR8 photon receptor more susceptible to the effects of 285 nm UVB which means less energy is required to effectively trigger the UVR8 pathway.
Plants exploit blue and UVA light to drive DNA repair processes. Researchers have shown that DNA damage due to UV is mostly repaired by subsequent exposure to light in the blue or UVA range of the spectrum (Ref. 12). Blue light and/or UVA exposure activate an enzyme (photolyase) that repairs damaged DNA sequences.
The advantage of this system is that when plants are exposed to UVR, there is always a lot of blue light present. The involvement of blue or UVA light in this process is known as photoreactivation. Photoreactivation is the major defence against UV-induced damage in plants.
Speedtriplebbc
Well-Known Member
To be honest, if I’d read all this before buying the uvb lights, I would have stuck with uva led wavelengths instead. But with a growing wealth of information on this thread I’m utilising my investment a little more wisely and sticking to minimal exposure.
Thanks for the work so far and everyone’s opinions, finding’s and input.
Speedtriplebbc
Well-Known Member
Just screenshot this off the Migro website, had to double check the bottom of the chart figures as it looks deceiving.
jimihendrix1
Well-Known Member
IMHO the Migro bulb is highly overrated.
Its only an 18w bulb, and says its good for a 4 x 4 area? Solacure is arguably one of the most powerful emiters of UVA/B made, and they say it takes 2 of them to cover a 4 x 4 area, and are 32w. 64w total.
The Migro peaks at 310nm, and the Solacure is most powerful at 280nm-300nm in the UVB range.
The Migro is also a T8, as the Solacure is a T12, and the T12 has much more mass. Solacure said they experimented with both T5, and T8 bulbs, and they were insufficient for their demands.
Migro also uses an aluminum reflector, and its well know UVA/B does not reflect very well, thuse why Solacure has a built in reflector
Im not impressed by the Migro at all, and I think thy overrate the bulb.
You can see even at 20w the Solacure is way more powerful than the Migro. And the Solacure is capable of running up to 80w.
At 40w the Solacure is 1400mw
4 foot Flower Power F40
40w, measured dead to lamp: 1400mw/cm2
20w, measured dead to lamp: 800MW/cm2 (normal F32 fixture)
1mw = 1000 uw
Migro is only 93uw/cm2
Its only an 18w bulb, and says its good for a 4 x 4 area? Solacure is arguably one of the most powerful emiters of UVA/B made, and they say it takes 2 of them to cover a 4 x 4 area, and are 32w. 64w total.
The Migro peaks at 310nm, and the Solacure is most powerful at 280nm-300nm in the UVB range.
The Migro is also a T8, as the Solacure is a T12, and the T12 has much more mass. Solacure said they experimented with both T5, and T8 bulbs, and they were insufficient for their demands.
Migro also uses an aluminum reflector, and its well know UVA/B does not reflect very well, thuse why Solacure has a built in reflector
Im not impressed by the Migro at all, and I think thy overrate the bulb.
You can see even at 20w the Solacure is way more powerful than the Migro. And the Solacure is capable of running up to 80w.
At 40w the Solacure is 1400mw
4 foot Flower Power F40
40w, measured dead to lamp: 1400mw/cm2
20w, measured dead to lamp: 800MW/cm2 (normal F32 fixture)
1mw = 1000 uw
Migro is only 93uw/cm2
Grow Lights Australia
Well-Known Member
Sorry I missed this earlier. Yes the Nichia UVs are very powerful but perhaps not as expensive as you think. We get good prices on Nichia diodes because we use them a lot. We are not competing in the same space for Samsung diodes like everyone else so we can also request and receive top Nichia flux bins which are better than Samsung anyway.
This is a comparison of the new (orange) and current (blue) versions of the High Light 420 flowering spectrum. Remember that when you average the graphs for area under the curve the orange peaks are a bit lower, so there are similar amounts of blue and surprisingly a very similar amount of red and green. Both spectra are 3000K but the new one is CRI94 vs CRI89 and there is slightly more far red and significantly more UVA and violet.
Here is the new spectrum on its own.
Grow Lights Australia
Well-Known Member
OK I take your point. I couldn't help myself. He didn't respond but I wasn't looking for an argument I just wanted to point out that UVA and far red do make a difference through both morphogenics and the Emerson Effect. There is a lot of dated information out there like the belief that high kelvin temperatures with more blue are best for veg when we've seen the complete opposite. Red grows faster and a small amount of violet/UVA prevents stretch and facilitates root growth and branching.Haha! I watched that video and thought the same thing! Then I saw your post. You'd better watch out mate – you don't want to get on Shane's bad side, LOL!
Of course he's wrong about UVA and Far Red, as we've proven, but there are probably a lot of people out there who don't want to read that.
I know you've seen this graph but for everyone else we have also been working on a propagation spectrum that is 3500K and does have a little bit more blue in it but that is to stimulate root growth at the expense of slightly faster growth. We are also going to test this spectrum to see if the extra blue increases cannabinoid production. We suspect it will but we also think that is because dry yields will be slightly lower which will increase cannabinoids as a percentage. This could be a good medicinal cannabis spectrum. We made this spectrum for a commercial indoor cloning propagator. There are subtle differences between this one and the one I posted above.
ttystikk
Well-Known Member
Please PM me. I have a project in mind and I'd like your input.
ttystikk
Well-Known Member
This is as well as I've ever seen it explained. Thank you.
jimihendrix1
Well-Known Member
There was a study done in Jerusalem 25 or more years ago where they infused Red into the glass of 1 greenhouse, and just used the normal glass on the other. They used tissue cultured flowers, and the flowers on the red infused side grew twice as fast as the non red side.
I myself both veg, and flower with a 1000w Hortilux HS, and have used them for at least 20 years. I used to use metal halide until Hortilux came out with an HPS buld that had a bit of Blue added. Ive always had good, tight internode spacing.
Most of the food Isralis eat, are grown in their greenhouses. They are one of the leaders in Greenhouse technology.
I myself both veg, and flower with a 1000w Hortilux HS, and have used them for at least 20 years. I used to use metal halide until Hortilux came out with an HPS buld that had a bit of Blue added. Ive always had good, tight internode spacing.
Most of the food Isralis eat, are grown in their greenhouses. They are one of the leaders in Greenhouse technology.
Grow Lights Australia
Well-Known Member
I would agree that you use less electricity and have longer bulb life but UVB bulbs do not last long and LEDs are much more efficient so perhaps it is a false economy to think that a UVB fluorescent is better than an UVA LED if they achieve the same result? What I see @Prawn Connery saying is that there are many ways to skin a cat. UVA diodes will last much longer than fluroro bulbs and are less dangerous to work under. UVA and violet in the 390-420 range also coincide with other absorption peaks such as Chlorophyll A and crytochromes, phototropins and carotenoids that are also excited by UVA/B.
We have done some UVB vs UVA testing and every time UVA wins. We suspect the reason has to do with the amount of UVB exposure during each 12/12 cycle but we are also having good results with UVA and violet compared to typical white phosphor blue pump LEDs thast have no violet or light below 440nm.
