MichiganMedGrower
Well-Known Member
The Hortilux Super HPS and others have a much better spectrum than the one in the comment.
Bad News About LED vs HPS
- Thread starter BobCajun
- Start date
The Hortilux Super HPS and others have a much better spectrum than the one in the comment.
MichiganMedGrower
Well-Known Member
I have not read that it has anything to do with closing stomata.
Here is some info from the university of Michigan.
http://msue.anr.msu.edu/news/green_light_is_it_important_for_plant_growth
ANC
Well-Known Member
....The closure of stomata with reduced normalized expression and number might be also the reason for the reduction of transpiration rate and stomatal conductance in lettuce which were grown under green LEDs more so than those grown under blue LEDs.....
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3975419/
It is a natural defence system, Leaves in the shade of other leaves receive green light.
This allows the plant to transpire more in parts exposed to direct light, as there is only one source for water to transpire with, namely the roots.
This, in turn, keeps those parts cool enough for photosynthesis to continue.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3975419/
It is a natural defence system, Leaves in the shade of other leaves receive green light.
This allows the plant to transpire more in parts exposed to direct light, as there is only one source for water to transpire with, namely the roots.
This, in turn, keeps those parts cool enough for photosynthesis to continue.
ZeroTrousers
Well-Known Member
however it is important to note that sunlight contains a significant portion of green spectra
https://en.wikipedia.org/wiki/Sunlight
500-530nm, given that nautural sunlight has an average color temp of 5500k-6500k.
Our lighting is significantly different from that of natural sunlight and more heavily weighted in the reds, yellow and blue spectra; so unless you are actively supplementing green LED or choosing LEDs with a heavy weighting in the green spectrum it's not going to significantly impact your grow.
nfhiggs
Well-Known Member
The Calvin cycle applies to ALL terrestrial plants.
biostudent
Well-Known Member
mauricem00
Well-Known Member
you forgot to factor in ballast lost which is factored into T5 ratings. a 315 cmh produces 33000 lumens and draws 355 watts from the wall. (93LPW) an f54 T5 energy miser produces 4800 lumens and draws 49 watt with a program start ballast (98 LPW) and only 46 watts with an instant start ballast (104 LPW) some people have had bad luck with T5s because they use low quality ballast and bulbs from a hydro or aquarium shop. with commercial grade ballast and bulbs lights can last years. supermarket. box stores like walmart or home depot. factories and warehouses use a lot of bulbs and replacing them is expensive with labor and parts cost so if they did not have a long life they would not be cost effective.a 6 bulb fixture works well in a 2ft by 4 ft tent. a 6 bulb T5 produces a ppfd of 551 using 324 watts of power (529 PPFD at 294 watts using energymiser) . using 2 150 watt HPS lights to get uniform coverage produces a ppfd of 531 at 330 watts. in a 4ft by 4 ft tent a single 600 watt HPS would provide a slightly higher PPFD than T5s (4% higher) for the same input power using standard bulbs. for a large commercial grow 1000 watt DE CMH bulbs are the best option but for a small PU closet grower T5s work well. comparing hydro shop lights is like comparing cheap led grow lights from E-BAY to HPS or CMH. commercial grade T5s are a different breed.just like COBs or 561 strip lights are a different breed from $50 ebay leds http://www.ebay.com/itm/BLOOMSPECT-300W-600W-LED-Grow-Light-Full-Spectrum-Hydroponic-Veg-Bloom-Plant/302341440316?ssPageName=STRK:MEBIDX:IT&var=601176440232&_trksid=p2055119.m1438.l2649. ppfd was calculated using an apogee conversion table https://www.apogeeinstruments.com/conversion-ppf-to-lux/ a couple years ago TRW developed a white led for use in photography that came close to natural sunlight. it used a UV LED to drive a tri phosphor mix. unfortunately UV led are still inefficient and expensive so these diodes were expensive and only produced 50LPW. but it's just a matter of time before someone develops a cheap highly efficient UV diode and this may be the future of horticultural LEDs but that technology is not here yet.
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Abiqua
Well-Known Member
There is too much Blue light in White light....and not enough green and red with efficacy, which the plants seem, seem to want.....
Here is that paper, some have dropped but little have "read".....
Green Light Drives Leaf Photosynthesis More Effi ciently than Red Light in Strong White Light: Revisiting the Enigmatic Question of Why Leaves are Green
https://oup.silverchair-cdn.com/oup/backfile/Content_public/Journal/pcp/50/4/10.1093_pcp_pcp034/2/pcp034.pdf?Expires=1502177472&Signature=KORzgKyhVRp2sWyY0zhMxFrbx33feNoFka88o-0Y5m1FA-mliC-QvCDjwUwCqjgE~r7TMu9XPZK0uaqbVDTTarlOXGDY44jlHEBk6PVfYAdrmALmXQ1sdg9lXne95Me9XK3gt9hUdH7znZe3jpLorZeWd2RGnS6vCaX-nhaCYWJajFy-lLCR0GvWziNTkkASEg45RASJkmRZ-nef6gGcxSUSsNfPX~mxmw4tvCgbYx-uIXDC2xQA2FinTTGrlHnUMssNnwFa6N8L8jls7bLFjzXVl0LE1DfCo~AB8qHMWlF61XtCg1Uy022bF4FUyqLceO2tFtD-rCuPcCkWoH1ApA__&Key-Pair-Id=APKAIUCZBIA4LVPAVW3Q
Moreover, as already mentioned above, it has been clearly shown that the quantum yield of photosynthesis based on absorbed photosynthetically active photon fl ux density (PPFD), measured at low PPFDs, was comparable between green and red light. When measured in leaves grown under natural conditions, particularly for those of trees, the quantum yield of green light is considerably greater than that of blue light ( Inada 1976 ), because some fraction of blue light is absorbed by fl avonoids in vacuoles and/or carotenoids in chloroplast envelopes.
Moreover, some carotenoids in thylakoid membranes do not transfer energy to reaction centers, or transfer with an effi ciency signifi cantly less than 1.0 ( Akimoto and Mimuro 2005 ). For example, one of the most abundant carotenoids in thylakoids, lutein, transfers its energy to chlorophyll with an effi - ciency of 0.7 ( Akimoto et al. 2005 ). The effi ciency for neoxanthin is even less, at most 0.09 ( Akimoto et al. 2005 ). Accumulation of fl avonoids and carotenoids is well known to increase in response to ultraviolet and/or strong light ( Lambers et al. 2008 ). This probably explains to a considerable extent why the quantum yield of blue light is low. Evans and Anderson (1987) reconstructed the absorbance spectrum of thylakoid membranes from those of the chlorophyll–protein complexes and estimated the relative excitation of PSII and PSI.
Evans (1987) argued that imbalance of PSII/PSI excitation would occur at wavelengths where light is absorbed by Chl b because energy is preferentially transferred to PSII. This might also explain why the quantum yield of blue light on an absorbed quantum basis is low. If this effect is large, a decrease in the PSII quantum yield (Genty's parameter, see below) might be expected at wavelengths strongly absorbed by Chl b . In a preliminary study with rice leaf discs illuminated with monochoromatic lights at a low PPFD of 5–12 µ mol m –2 s –1 , Fig. 2 Model explaining the détour effect on absorptance. Left: no détour effect. Right: the light path is lengthened 3-fold by the détour effect. For strongly absorbed monochromatic light, the increase in absorptance by the détour effect is small (above), while for weakly absorbed light the increase is marked (below). 686 I. Terashima et al. Plant Cell Physiol. 50(4): 684–697 (2009) doi:10.1093/pcp/pcp034 © The Author 2009. we observed small reduction of the PSII reaction center [decreased ( Fm′ – Fs ′ )/ Fm′ mainly due to the decrease in photochemical quenching] in two wavelength regions with peaks at 470 and 650 nm, respectively, implying overexcitation of PSII at these wavelengths. However, the decreases observed were not enough to account for the large decrease in the quantum yield of blue light.
Abiqua
Well-Known Member
a side by side means nothing in terms of quantifying results, other than your eyeballs....It does nothing to really further good science, cm'on man....elimating variables is a key in gathering good data not grounded in bias....a side by side is great for selling stuff, but too many unaccounted for variables.....unless your standardize everything, then you might as well be in business rather than underground, but still......
BobCajun
Well-Known Member
I actually bought the filters a long time ago but I was using only LEDs at the time and it didn't seem to help, just made it dimmer and more leaves dropped off the bottoms. But since I already had them and I recently started using the HPS I thought they might actually help in that case, since HPS is green heavy. Maybe it will just make it dimmer, have to see how it turns out.
Hybridway
Well-Known Member
Well, it's the best we got as growers.a side by side means nothing in terms of quantifying results, other than your eyeballs....It does nothing to really further good science, cm'on man....elimating variables is a key in gathering good data not grounded in bias....a side by side is great for selling stuff, but too many unaccounted for variables.....unless your standardize everything, then you might as well be in business rather than underground, but still......
Abiqua
Well-Known Member
Doubtful.....but if your willing to expand your position on it, I am willing to listen....Just google: protocol for doing an experiment, at least you would think we could follow that.....
Another way, that I am familiar with......Ask the questions of the scientific method [there's 7] and see if it interfaces with the protocols of a side by side....
Hybridway
Well-Known Member
The Digilux had the nicest I thought but the Horti's put out more lumens. Those are the only 2 I liked to use.
Hybridway
Well-Known Member
Say What to Who??? Man, grow that shit.Doubtful.....but if your willing to expand your position on it, I am willing to listen....Just google: protocol for doing an experiment, at least you would think we could follow that.....
Another way, that I am familiar with......Ask the questions of the scientific method [there's 7] and see if it interfaces with the protocols of a side by side....
Abiqua
Well-Known Member
Feigning ignorance doesn't compute....are you saying you cant increase your knowledge to improve your growing...or am I taking that all wrong?
Abiqua
Well-Known Member
I think you should reconsider.....
MichiganMedGrower
Well-Known Member
I believe my galaxy ballast paperwork recommends digilux. But I have not tried one. I read too many reviews of failures and my store at the time had many returns. They were newer then though. I can't say personally.
I have been happy with Hortilux from the beginning and have had no failures or problems. I even ran a couple of 400's at 600 watts for most of a day accidentally and both bulbs are still fine.
Ushio is recommended by some respectable growers around here. And on other forums.
Hortilux always tests highest par. Not lumens. Other companies exaggerate lumens according to Hortilux I read on their site.
Of course that's what we want.
chemphlegm
Well-Known Member
My UFO has always sucked even though the manufacturer said it didnt suck
Abiqua
Well-Known Member
This part is kinda important here:
Lettuce leaves were exposed to (522 nm), red (639 nm) and blue (470 nm) LEDs of different light intensities.
My thoughts.....so blue green runs the nm spectrum from roughly 475 to 580-590 [yellow]. I just think there is a hint of caution to be taken, heavily in fact, but good news, none the less.