Blue light at night the controversy rages

[Storm Shadow]

http://www.ncbi.nlm.nih.gov/pubmed/22686322

Plant Biol (Stuttg). 2013 Jan;15(1):67-74. doi: 10.1111/j.1438-8677.2012.00603.x. Epub 2012 Jun 12.
Blue light effects on rose photosynthesis and photomorphogenesis.

Abidi F, Girault T, Douillet O, Guillemain G, Sintes G, Laffaire M, Ben Ahmed H, Smiti S, Huché-Thélier L, Leduc N.
Source

INRA, Institut de Recherche en Horticulture et Semences, (INRA, Agrocampus-Ovest, Université d'Angers), SFR 4207 QUASAV, F-49071 Beaucouzé, France.

Abstract

Through its impact on photosynthesis and morphogenesis, light is the environmental factor that most affects plant architecture. Using light rather than chemicals to manage plant architecture could reduce the impact on the environment. However, the understanding of how light modulates plant architecture is still poor and further research is needed. To address this question, we examined the development of two rose cultivars, Rosa hybrida'Radrazz' and Rosa chinensis'Old Blush', cultivated under two light qualities. Plants were grown from one-node cuttings for 6 weeks under white or blue light at equal photosynthetic efficiencies. While plant development was totally inhibited in darkness, blue light could sustain full development from bud burst until flowering. Blue light reduced the net CO(2) assimilation rate of fully expanded leaves in both cultivars, despite increasing stomatal conductance and intercellular CO(2) concentrations. In 'Radrazz', the reduction in CO(2) assimilation under blue light was related to a decrease in photosynthetic pigment content, while in both cultivars, the chl a/b ratio increased. Surprisingly, blue light could induce the same organogenetic activity of the shoot apical meristem, growth of the metamers and flower development as white light. The normal development of rose plants under blue light reveals the strong adaptive properties of rose plants to their light environment. It also indicates that photomorphogenetic processes can all be triggered by blue wavelengths and that despite a lower assimilation rate, blue light can provide sufficient energy via photosynthesis to sustain normal growth and development in roses.
© 2012 Université d’Angers, France.

 

[Storm Shadow]

http://www.ncbi.nlm.nih.gov/pubmed/22589732

PLoS Genet. 2012;8(5):e1002674. doi: 10.1371/journal.pgen.1002674. Epub 2012 May 10.
Hypersensitive to red and blue 1 and its modification by protein phosphatase 7 are implicated in the control of Arabidopsis stomatal aperture.

Sun X, Kang X, Ni M.
Source

Department of Plant Biology, University of Minnesota Twin Cities, Saint Paul, Minnesota, United States of America.

Abstract

The stomatal pores are located on the plant leaf epidermis and regulate CO(2) uptake for photosynthesis and the loss of water by transpiration. Their stomatal aperture therefore affects photosynthesis, water use efficiency, and agricultural crop yields. Blue light, one of the environmental signals that regulates the plant stomatal aperture, is perceived by the blue/UV-A light-absorbing cryptochromes and phototropins. The signal transduction cascades that link the perception of light to the stomatal opening response are still largely unknown. Here, we report two new players, Hypersensitive to Red and Blue 1 (HRB1) and Protein Phosphatase 7 (PP7), and their genetic and biochemical interactions in the control of stomatal aperture. Mutations in either HRB1 or PP7 lead to the misregulation of the stomatal aperture and reduce water loss under blue light. Both HRB1 and PP7 are expressed in the guard cells in response to a light-to-dark or dark-to-light transition. HRB1 interacts with PP7 through its N-terminal ZZ-type zinc finger motif and requires a functional PP7 for its stomatal opening response. HRB1 is phosphorylated in vivo, and PP7 can dephosphorylate HRB1. HRB1 is mostly dephosphorylated in a protein complex of 193 kDa in the dark, and blue light increases complex size to 285 kDa. In the pp7 mutant, this size shift is impaired, and HRB1 is predominately phosphorylated. We propose that a modification of HRB1 by PP7 under blue light is essential to acquire a proper conformation or to bring in new components for the assembly of a functional HRB1 protein complex. Guard cells control stomatal opening in response to multiple environmental or biotic stimuli. This study may furnish strategies that allow plants to enjoy the advantages of both constitutive and ABA-induced protection under water-limiting conditions.

 

[budlover123]

It's hard to say, but I think when they talk about blue light in those papers they're talking about blue light during the day cycle.

The new version of my light control software I'll be releasing soon supports up to 4 different RS-485 devices, which means it's easy to split the signal 4 ways to control 4 different grow rooms. The 24-hour timer mode is almost complete and it is practically made for doing experiments like these. Is anyone looking into the possibility of getting an experimental grow room set up with funds from kickstarter? It's a stretch, but especially if we have some botanist on here that can do some scientific research, maybe that'll get approved and funded.

I actually got Lightput working for the Rasberry Pi, its on the Pi Store but the standalone install from the Lightput website works better than the Pi Store one. As I mentioned before, the Raspberry Pi runs on a 6-watt power supply and is ideal for a constantly running application like a light timer, it has like 2 chips on it and it doesn't get hot at all. It's surprising how simple it is. It can run on 4 AA batteries, so making a battery backup for it should be pretty easy too.

Also, its probably worth noting that involving the Raspberry Pi will likely increase the probability of approval, they love that kind of stuff over there.

 

[budelight]

sub'd

sub'd

 

[budlover123]

Lightput version 0.3 is out for Windows only and it has the 24-hour timer mode working, although I only tested it for a couple days and it would have to be tested more before actually using in a grow room, it seems like it's ready. The design prioritizes the fact that lights stay on when they're supposed to and off when they're supposed over the transition between hours. The timer mode is also designed in a way that if you were to lay on your keyboard by accident while running it shouldn't effect Lightput.

The Ubuntu Linux and Raspberry Pi versions should be ready soon, the problem is they may not support multiple RS-485 devices, if that's the case, if your DMX drivers don't support DMX out to connect multiple drivers together, you'll have to use a DMX splitter with Lightput to send the output to 2 or more different DMX devices.

more or less by the time someone gets the resources to do do a test like this, Lightput should be ready, free, and has a feature specifically built for this.

 

[Crusader Rabbit]

Well, addressing the original subject ...

Did a bit of reading on the net. If I got something wrong here, hopefully someone more knowledgeable will point out my mistakes.

The ratio of Chlorophyll A to Chlorphyll B is 3 : 1. This suggests that a lighting system favoring the absorption spectra of Chlorophyll A would maximize photosynthetic activity by a factor of three.





LED grow light manufacturers are producing light arrays which have peak intensities at 430nm, 453nm, 642nm, and 662nm to hit the peak absorption spectra of both Chlorophyll A and B.

Supposedly it is the red light wavelength of 660nm which manipulates flowering hormones and will cause problems in the flowering room. Whether 642nm is close enough to have this effect I don't know.

If this blue light at night technique works (and I see no reason why not), it would be advantageous for a manufacterer to produce an LED array in which those LEDs which do not affect flowering hormones are wired separate from those that do. The diodes which emit wavelengths that don't influence flowering could then be run round the clock. Diodes emitting the wavelengths which do affect flowering would be wired through a timer so they could shut down during "dark periods".

 

[Sativa Dragon]

I thought it was green light that the plants can't use and blue spectrum equals daylight. I'm actually using a blue energy saving lamp for flowering right now, so I find all this hard to swallow. Do blue leds really differ that much from light bulbs with a 6400k spectrum?

Thule, 6400k is a temperature good for vegging you would be more productive if you ran a 2900k CFL, if you are using more than one bulb you can mix them up a bit as long as the lower Kelvins are dominant. 2900k's are more red, 6500k is more full spec daylight.

Peace

 

[Tonygreen]

Well, addressing the original subject ...

Did a bit of reading on the net. If I got something wrong here, hopefully someone more knowledgeable will point out my mistakes.

The ratio of Chlorophyll A to Chlorphyll B is 3 : 1. This suggests that a lighting system favoring the absorption spectra of Chlorophyll A would maximize photosynthetic activity by a factor of three.


https://www.icmag.com/ic/picture.php?albumid=42262&pictureid=1010867View Image


LED grow light manufacturers are producing light arrays which have peak intensities at 430nm, 453nm, 642nm, and 662nm to hit the peak absorption spectra of both Chlorophyll A and B.

Supposedly it is the red light wavelength of 660nm which manipulates flowering hormones and will cause problems in the flowering room. Whether 642nm is close enough to have this effect I don't know.

If this blue light at night technique works (and I see no reason why not), it would be advantageous for a manufacterer to produce an LED array in which those LEDs which do not affect flowering hormones are wired separate from those that do. The diodes which emit wavelengths that don't influence flowering could then be run round the clock. Diodes emitting the wavelengths which do affect flowering would be wired through a timer so they could shut down during "dark periods".

If 642 is too close and affects flowering Im not sure but thats the main reason I suggest that area between like 380-450 nm, pretty good a absorption in that area.

 

[Tonygreen]

Good point crusader. +1 mate
This is better then my first suggestion , bit better a +b absorbtion

 

[Crusader Rabbit]

If you look at the vertical scale, moving "BAM" over to that point increases the absorption by Chlorophyll B by 8%, and doubles the absorption by Chlorophyll A.

But reading that there is three times as much Chlorophyll A in a leaf surface as there is Chlorophyll B, it then makes sense to just target the peak absorption wavelength of Chlorophyll A (which does happen to be very close to BAM anyway). They are making LED arrays that target both the peaks, A and B, but it really might be better to optimize for A.

So if this does work, then a LED light array for cannabis should have two cords. One powers the blue light emitting diodes, the second cord powers all the rest. The first cord plugs straight into the wall outlet for 24 hours of light. The second cord plugs into your timer.

 

[Sativa Dragon]

This sounds like it needs a test, so what is the wavelength that has to run for twenty four hours and what is the ones that get the timer 12/12?

Maybe I can put together a small test, I have been moonlighting a distributer of LED's and was going to solder one together but I need specifics for the test so I know what to order. Maybe I will test it on a lowryder to keep the test small. So can we compile the nessecary wavelegnths in NM.

Peace

 

[Tonygreen]

so it looks like 430 nm for 24 hours, regular lighting 12/12?

 

[Crusader Rabbit]

so it looks like 430 nm for 24 hours, regular lighting 12/12?

That should do it.

 

[Sativa Dragon]

Alright I believe 430nm is the blue that the LED guys try to nail down for the veg stage, What would be the 12/12 lighting just all other spectrums? I am going to contact the supplier today and get some gear.

Peace

P.S. Finally an experiment with no colateral damage.

 

[Tonygreen]

Yup that sounds right Sativa dragon. The other thought was to let 2 hours pass after normal 12/12 so the plant is induced into its normal night cycle then turning on the blue.

Either way its good to start somewhere. I'm pumped about this.

It will be awesome to see how this goes. Cheers man. Side by side results will be interesting.

 

[Sativa Dragon]

Okay so I have emailed the supplier and I am asking for a price on two driers 700ma each and 20 430nm 3watt high intensity cree, and 20 660nm 3watt high intensity cree, so this project will be a long haul but I will PM both of you in the discussions to keep you updated. I have all the other supplies like soldering station etc, just need to dream up a physical configuration. it will be a UFO style or in a circular pattern Drivers incorperated, I am going to look around for a timer that can be made integeral for each spectrum so I can program it on board. Any Ideas throwem out here.

Peace

 

[Sativa Dragon]

So it would be like this 12 on both spectrums 2 off for the blue and back on 10, and for the red it stays of for 12 hours. I did a quick budget looking at about $500 us for the gear that is if the company gives me no feebies, I told them it was R&D and could potentially go into production, some companies like to be favourable in these situations an throw in some freebies. As far as the light goes I am looking at 20 3watt 430nm high intensity, and 20 660nm 3 wat high intensity and two drivers. What is the physical configureation what will this thing look like? a ufo maybe

Peace

 

[Sativa Dragon]

WTF I made one post and it never showed up so I made a second and now I go to check and they are both there, I bet some Mod is watching my posts, I was banned recently for eledgidly Gay bashing, it was no where near gay bashing so much as mentioning the gay people I know refer to themselves as homosexuals, note to moderator, stating some ones orientaton as being Homosexual is not gay bashing, Just like me calling myself heterosexual is not straight bashing.

 

[Tonygreen]

Looks good, excited to see this getting a test.

 

[SeaMaiden]

Sativa, the site (server) is having issues. I've been told it's my browser and I know factually it is not. It could be related to my ISP and its interaction with the server, but I also believe that some spam IPs have been blocked, many originating in Australia, but not all. I believe Skip, et alia, are still working through it.

Well, addressing the original subject ...

Did a bit of reading on the net. If I got something wrong here, hopefully someone more knowledgeable will point out my mistakes.

The ratio of Chlorophyll A to Chlorphyll B is 3 : 1. This suggests that a lighting system favoring the absorption spectra of Chlorophyll A would maximize photosynthetic activity by a factor of three.


[URL=https://www.icmag.com/ic/picture.php?albumid=42262&pictureid=1010867]View Image[/URL]


LED grow light manufacturers are producing light arrays which have peak intensities at 430nm, 453nm, 642nm, and 662nm to hit the peak absorption spectra of both Chlorophyll A and B.

Supposedly it is the red light wavelength of 660nm which manipulates flowering hormones and will cause problems in the flowering room. Whether 642nm is close enough to have this effect I don't know.

If this blue light at night technique works (and I see no reason why not), it would be advantageous for a manufacterer to produce an LED array in which those LEDs which do not affect flowering hormones are wired separate from those that do. The diodes which emit wavelengths that don't influence flowering could then be run round the clock. Diodes emitting the wavelengths which do affect flowering would be wired through a timer so they could shut down during "dark periods".

YES, I am understanding the situation as you. I believe it's fairly well documented (what wavelengths of red light control flowering in Arabidopsis, which is the standard research plant, and is, IIRC, a photoperiod flowering plant, or has some species that are photoperiod flowering {aka regenerative phase}). I believe there are two photoreceptors for different flowering wavelengths, but I cannot remember where I read it. One switches on, another switches off, IF I recollect correctly, that is.