Kassiopeija
Well-Known Member
Hello,
does anyone know a link to a professional read about how the industry performs these tests (to find out the ppfd of their products...)?
As far as I read from various sources on the net it seems like they test umols between the classic PAR range of 400-700nm.
Doesn't this distort the potential value of this info? Is 400-700nm even rightly so the correct PAR? Because UVA, UVB, FR & IR photons aren't counted - although they are precious for plant growing.
Here in this video Bugbee explains how Far Red-photons (~730nm) are taken in by the photosynthetic Reaction Center I in order to built plant biomass. And that the McCree curve is false - because back then when McCree made his tests, he didn't know that there were 2 RCs present - so his tests were flawed from the very beginning.
(note: "Far Red photons ABOVE 700nm)
So if a lamp (like a HPS) emanates light from (701-780nm) it's not counted in to the umols although this light could be used for photosynthesis as well. That means if one would compare the official umols/ppfd datasheets from the almost monochromatic LED spectrum to a HPS spectrum then that comparison is greatly skewed because 20% (grossly estimated) of photons are simply "forgotten" in the case of the HPS - rendering the comparison uneven (thus: false)
The above pic illustrates how much FR & IR is being converted by a HPS from electrons into photons. It's actually more than what's needed, like, perhaps 100% more.... still, the traditional PAR reading doesn't factor them in... although they are needed:
Most LED growers have leaves freezing at a temp of below 25°C.... (leaf surface temps) and would actually have to heat up their room to come to even terms with CMH or HPS... ofc it's highly dependant on where you're located.... but plants need heat, it's temperature that drives metabolism & the speed of enzymes.
At 30°C ambient Cannabis grows better than at 25°C, at all senseful ppfd settings....
The same argument could be made for CMH or MH lamps - their Near-UV, UVA & UVB output isn't calculated in - although this is valueable radiation, where alot of LED growers are looking for a substitute... I also wonder why plants can't do photosynthesis with light <400nm? Because that doesn't make much sense to me at all, given the fact that the chlorophyls & various antenna complexes can absorb UV radiation.
So how is the true PAR-range? 365-780nm? 310-850nm? 280-940nm? How far can it get?
I wonder what would happen if one would try to mimic a dual-arcs HID output (MH + HPS combined) with LEDs (white CRI + UVB + various UVA + FR + IR) how efficient such an output would be in terms of ppfd? Because, as I see it now, the LED umols are distorted in their favour because of this falsely placed cutoff-range:
vs:
^^ not even complete^, but you get the idea of what an CMH lamp does bring to the table ^^
I also think that a wide open & mixed spectrum is much better for plants because an almost monochromatic light bears a heavy toll on the plant tissue where it's absorbed - different wavelengths are encaptured at different antenna-complexes or chloroplasts/leaves.... now if one only uses the same 660nm all over the place ofc a leaf is going to heat up extremely at the very same spot:
almost monochromatic photonic bombardement: (LED)
(Sylvania Grolux linear - almost no cyan, no UV, no IR)
(Phytomax2 - almost no FR, no IR)
And this is what plants are actually used to:
(since this is at oceanic levels the UV part is lower than it should be, at least, for the natural surrounding grounds at which Cannabis developed evolutionairy (Tibet, Afghanistan - high altitude)
does anyone know a link to a professional read about how the industry performs these tests (to find out the ppfd of their products...)?
As far as I read from various sources on the net it seems like they test umols between the classic PAR range of 400-700nm.
Doesn't this distort the potential value of this info? Is 400-700nm even rightly so the correct PAR? Because UVA, UVB, FR & IR photons aren't counted - although they are precious for plant growing.
Here in this video Bugbee explains how Far Red-photons (~730nm) are taken in by the photosynthetic Reaction Center I in order to built plant biomass. And that the McCree curve is false - because back then when McCree made his tests, he didn't know that there were 2 RCs present - so his tests were flawed from the very beginning.
(note: "Far Red photons ABOVE 700nm)
So if a lamp (like a HPS) emanates light from (701-780nm) it's not counted in to the umols although this light could be used for photosynthesis as well. That means if one would compare the official umols/ppfd datasheets from the almost monochromatic LED spectrum to a HPS spectrum then that comparison is greatly skewed because 20% (grossly estimated) of photons are simply "forgotten" in the case of the HPS - rendering the comparison uneven (thus: false)
The above pic illustrates how much FR & IR is being converted by a HPS from electrons into photons. It's actually more than what's needed, like, perhaps 100% more.... still, the traditional PAR reading doesn't factor them in... although they are needed:
Most LED growers have leaves freezing at a temp of below 25°C.... (leaf surface temps) and would actually have to heat up their room to come to even terms with CMH or HPS... ofc it's highly dependant on where you're located.... but plants need heat, it's temperature that drives metabolism & the speed of enzymes.
At 30°C ambient Cannabis grows better than at 25°C, at all senseful ppfd settings....
The same argument could be made for CMH or MH lamps - their Near-UV, UVA & UVB output isn't calculated in - although this is valueable radiation, where alot of LED growers are looking for a substitute... I also wonder why plants can't do photosynthesis with light <400nm? Because that doesn't make much sense to me at all, given the fact that the chlorophyls & various antenna complexes can absorb UV radiation.
So how is the true PAR-range? 365-780nm? 310-850nm? 280-940nm? How far can it get?
I wonder what would happen if one would try to mimic a dual-arcs HID output (MH + HPS combined) with LEDs (white CRI + UVB + various UVA + FR + IR) how efficient such an output would be in terms of ppfd? Because, as I see it now, the LED umols are distorted in their favour because of this falsely placed cutoff-range:
vs:
^^ not even complete^, but you get the idea of what an CMH lamp does bring to the table ^^
I also think that a wide open & mixed spectrum is much better for plants because an almost monochromatic light bears a heavy toll on the plant tissue where it's absorbed - different wavelengths are encaptured at different antenna-complexes or chloroplasts/leaves.... now if one only uses the same 660nm all over the place ofc a leaf is going to heat up extremely at the very same spot:
almost monochromatic photonic bombardement: (LED)
(Sylvania Grolux linear - almost no cyan, no UV, no IR)
(Phytomax2 - almost no FR, no IR)
And this is what plants are actually used to:
(since this is at oceanic levels the UV part is lower than it should be, at least, for the natural surrounding grounds at which Cannabis developed evolutionairy (Tibet, Afghanistan - high altitude)
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