Grow Lights Australia
Well-Known Member
The original High Light 420 spectrum is on the top, the Gen2 spectrum is below. Note the difference in UVA around 405nm.
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Latest UVA vs UVB cannabinoid test results
- Thread starter Grow Lights Australia
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Thank you for such a detailed description of your experiments. Perhaps the question is a little off topic, but could you somehow justify such a large percentage of Far Led chips in your lamps. Doesn't this lead to excessive stretching of the plants, or simply compensate for the suppression of growth from the short-wavelength part of the spectrum?
Your site also mentions the reduction of flowering time.
I would be grateful for any comments.
Your site also mentions the reduction of flowering time.
I would be grateful for any comments.
Kassiopeija
Well-Known Member
the plants under his lights from page 2 of this thread display no signs of any phytochrome-syndrome.
sunlight actually contains much more FR as well... more & more LED comp. put that into their racks but in my opinion none deserve the title "full spectrum" as much as the GLA boards...
As for the UVA that is rather in harmless regions very close to blue. This type of colour will be absorbed by chlorophyl-molecules specifically designed to take violet in, plus UVA can transmit a tad deeper into a leaf + induce chlorophyll fluorescence if the antenna/core is already light-saturated so having that on board is actually a step into the right direction IMO
You are of course right - there is a huge amount of Far Red in the sunlight, but
- in my opinion, no other lamps contain so much Far Red
- once I turned on this percentage in addition to stimulate the beginning of flowering (only without UV, which I turned on later) and my bushes stretched ugly.
I think that Grow Lights Australia knows well what he is doing and will explain it.
- in my opinion, no other lamps contain so much Far Red
- once I turned on this percentage in addition to stimulate the beginning of flowering (only without UV, which I turned on later) and my bushes stretched ugly.
I think that Grow Lights Australia knows well what he is doing and will explain it.
Kassiopeija
Well-Known Member
Yes indeed, very much so, but I thought your post made a statement, which I see basically everywhere, and where I am missing a discussion about it.
This:
I've seen this argument alot, but can you really proove that the FR is the sole reason for the stretch?
It is certainly based on a number of factors like plant age, genetics, temperature & overall light saturation.
I've examinated this phytochrome-syndrome on cannabis, even vegging under only Far Red light and these plants just looked entirely different than everything I see under both old or new GLA spec
and the topic is really interesting esp. for commercial growers because of the many positive effects far-red light has if one manages to keep the phytochrome-reaction in cheek. esp. under Co2/increased temps/long vegged plants
I'm surprised not many companies do that, or rather: do it wrong (like 780nm diode) or rather extremely lackluster (so there's almost no effect on photosystem I)
All I can say is that the typical standard white light diode spectrum, that will try to monger its umol numbers up by using 660nm monos, will create a huge potential danger to burn, stunt & bleach the tops because they just neglect very important light-colors... and then it is impossible to max ppfd for better yield
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Kassiopeija
Well-Known Member
end_of_the_tunnel
Well-Known Member
Test chamber #2.
That was an interesting test run comparing three tents/chambers run at different PPFD.
Of course, I have no rigorous scientific evidence. But all the factors you listed can be excluded because they were completely identical (except varieties 2 out of 4) in the previous and subsequent growing cycle, and the stretch was only at Fr.
(Given that the height of my box is 1 meter on your photo, I would definitely write "I don't like it!")
I can only offer a possible explanation.
As you know, living organisms can respond to external influences in terms of its absolute value and gradient. If Fr works from seed germination, then the effect will be one, and if you turn it on suddenly, then another, with the same amount of Fr.
Considering that the "shadow avoidance effect" itself is not a direct action (it depends on the R / Fr ratio), then most likely I had the second type of reaction.
It is quite possible that the same thing can happen with UV.
Discontinuous UV lighting has been discussed here before to optimize the ratio of THC synthesis/degradation. It is possible that such a regimen may be more productive in terms of stimulation of THC synthesis, even by itself. without considering degradation.
Kassiopeija
Well-Known Member
Another explanation would be that introduction of FR light would serve to excitate Photo System I more and do away with the electron-jam at the plastiquinone binding site where PSII connects to PSI - which is usually followed by the antenna of PSII partially relocating to support PSI with excitons (a moved antenna means less excitons for PSII, and unused potential/chlorophylls in PSI)
This is why the abscence of FR light will cause a diminished potential to assimilate light or overall Co2 fixation (among other reasons such as FR light being able to drive photosynthesis in deeper layers of your plant's structure...) ... the reversal of this throttle has been first observed by Emerson.
Also the cooling effect of FR light right at the PSI core helps to alleviate photo-damage of chlorophylls at high ppfd levels. So less repair necessary.
The result would be that the plant would having access to more photosynthates + all the other benefits from the processes that happen during lights on in the leaves. Like N or S processing. This does indeed lead to better overall growth, there are many scientific studies supporting this. But yes, the internodes may get longer as well as just an artifact of swifter overall growth.
Any introduction of FR light additionally into your setup will just be "more light". You'd have to reduce the other PAR light to arrive at the very same ppfd (but then, it still may leave room open for critic because of the special nature of FR - that is just not that 1umol FR is 1umol PAR)
Secondly, the shady-avoidance effect requires certain thresholds to be triggered (there are 2 plateaus) but it can be differentiated from "just longer internodes" from the other effects it has on leaf-area, petiole length & angle etc. The presence of PAR, and esp. red light, will just revert that molecule. It is possible that deeper into the canopy the spectrum changes much more to green and esp. FR and that then, different ratios are met. Which, on sunplants causes the effect that these shadowed parts stretch out for direct light. That said, both the abscence light per se does also cause this, just in that case this shoot will grow lanky & erratic as it simply has even less energy to begin with.
Nice test!
Does the UVA and UVB help against mold and pests? I doubt it could kill an ongoing infestation, but could it prevent it?
If i had a lot of weed to afford testing and sacrificing a plant, i would run 2 clones in separate tents, one with UVA/UVB and one without, i would sprinkle a handful of mold spores on both and see which one gets infested more
Does the UVA and UVB help against mold and pests? I doubt it could kill an ongoing infestation, but could it prevent it?
If i had a lot of weed to afford testing and sacrificing a plant, i would run 2 clones in separate tents, one with UVA/UVB and one without, i would sprinkle a handful of mold spores on both and see which one gets infested more
Prawn Connery
Well-Known Member
Haha! My job this time around was to test the new propagation board, which I did by growing out some seedlings that came from almost 20-year-old seeds. After that, however, I put them outside as it is the outdoor season here in Australia. So I don't have a lot to show at the moment as I'm just sexing the plants outside before I cull the males and repot the females.
I had to stop indoor growing for a little while as we've had people working on the house and its also been bloody hot! The outdoor plants are easier to hide than pulling down a grow tent and having to put everything back up after the tradesmen leave. The propagation tent is small, so it's also easy to hide. I will start another indoor grow after summer, when it cools down a bit. We've had a record heatwave this year, and so I've already lost a couple of plants to the heat. It's not a good time to grow indoors without aircon, even under LED, and my usual grow space is in the roof so it gets super hot up there.
Sorry to disappoint
Prawn Connery
Well-Known Member
I can answer these questions because I designed the original High Lights and the new 420 boards. I've also grown extensively under them.
The Red:Far Red ratio of sunlight is around 1.3. Typical LED grow lights are anywhere from 20:1 down to 10:1. Our lights are 4 to 4.5:1 – still far less than sunlight.
Far red causes cell expansion, which can lead to Shade Avoidence. However, UV counters Shade Avoidence. So the extra far red still produces larger leaves, which accelerates photosynthesis, but not the long internodal length normally associated with Shade Avoidence. Far red also speeds up the flowering process – something that has been documented not just by us – but what we mainly see is similar yeilds, but in about 10% less time (which is effectively a 10% increase in yield over time).
The reason other companies do not use as much far red as we do is simple: they don't use UV at the other end of the spectrum (have a look at sunlight), they don't actively grow/test under different spectra like we do, and I think a lot of other companies are simply too scared to put that much far red in their lights because they perpetuate the far red "stetch" myth without understanding what is going on. In fact, I think most other companies just copy each other and are not interested in developing new spectra because it takes time and effort.
As always, @Kassiopeija is a font of knowledge and his explanations are correct.
Prawn Connery
Well-Known Member
I can't comment much on UVB as I don't grow under it, but UVA does not really protect against mold and pests (indeed, some pests are actively attracted to UVA), and from what I have seen, UVB only inhibits mold towards the shorter end of the spectrum, which can be potentially damaging to plants. What UV does do is it thickens the epidermis of plants, which can make them more resistant to mold and pests. So while UVA may not attack mold or pests directly, it can help plants withstand them.
Prawn Connery
Well-Known Member
Have you seen @Grow Lights Australia Insta page? There are lots of extreme sativas growing under our lights on that page and none of them are showing signs of stretch. The proof is in the pudding, so to speak. Have a look here if you can: https://www.instagram.com/growlightsaustralia/
I haven't got anything growing indoors at the moment, otherwise I would post some photos up showing the same.
grotbags
Well-Known Member
BINGO
Grow Lights Australia
Well-Known Member
I believe we have a few grows lined up with the new lights soon. Perhaps I can direct you to our Insta page in the mean time?
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Grow Lights Australia
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I think what @Prawn Connery and @PSUAGRO. said. UV light thickens the outer surfaces of the leaf that can improve its defences. Also UVC and deep UVB can kill pests, fungal spores and bacteria but that sort of radiation is harmful to plants. And we've seen mold in grows under UVB reptile bulbs so it may or may not have much of an effect.
So what exactly kills mold under sunlight? It's been long known that mold doesn't grow directly under the sunlight, they always look for a shade. And UVC is filtered by the ozone, so it's mostly UVA and UVB. Could it be the combination of IR/UVA/UVB together? Or a specific intensity and wavelength such as 280nm?