Blue light at night the controversy rages

[Crusader Rabbit]

Rosenthal obviously didn't know about cryptochromes when he wrote that. They are a relatively new discovery.

You blew off the work done by Sativa Dragon and Verdant Green.

I just spent some time searching and had little luck finding articles in nontechnical language.

Here's a title from a New Scientist article. I don't have a subscription to access it;

Blue light tells plants when to flower
Protein that marks day length also coordinates blooming genes

By Rebecca Cheung

Web edition: May 25, 2012



Here's one critical sentence from another article;

In summary: the blue-light/CRY1 pathway doesn’t directly switch genes on. instead, it switches off the default dark condition mechanism.

http://thenode.biologists.com/got-the-blues-how-plants-respond-to-blue-light/research/

The cry family of blue light receptors regulates various aspects of plant development, most notably seedling de-etiolation—the transition from a pale nonautotrophic seedling to a green photosynthetically competent one, entrainment of the circadian clock, and day length-sensitive timing of flowering (Lin and Shalitin, 2003).

http://www.plantphysiol.org/content/133/4/1429.full


I'm going to bed now.

 

[Infinitesimal]

I haven't read the whole thread... just wanted to bookmark it... and also add really quickly that my portable A/C has blue LED backlighting and I saw no nanners and excellent quality even throughout a tortuous environment.

I don't know if the blue light played a factor, though at the time I was worried about the light causing hermies, just thought I'd throw my observations out there.

 

[k-grower]

would explain the accelareted growth in nature as they get lot bigger there usually, i have been touch of some farmers - they have told that sometimes too bright nights (as full moon) have made their crops hermie.

 

[Crusader Rabbit]

I learned an interesting thing from my reading last night. It is the absence of blue light that causes stem elongation in seedlings. This suggests that intense blue light in early growth would promote a shorter internode spacing.

 

[habeeb]

^ well I know when you "nuke a plant with blue" it is alot more squat..

I've gotten like 5 inch autos with high high blue, when they should have been 12 inches tall.. also evident in veg with super squat bushes..


but I also thought shade avoidance syndrome ( SAS ) came into play with stem length? where if I understood it correct ( correct if wrong ) the far red ( 720-740nm ) basically penetrates all the way down to the floor, where as the R ( 660nm ) gets absorbed by top leaf or any leaf that it hits, getting "absorbed" , so the lower set senses the absence of R, and grows to get "quality light" ( 660nm ) and grows till the bottoms are getting some red.. did I explain that right at all?



here's a crazy complicated one if someone can decipher at all

 

[habeeb]

from jib : "If you hit the plant with IR light (i think 720 nm far red) after the plant was hit with 620ish nm, the phytochrome will essentially do an instant switch to "dark mode". There is a natural 2hr period where this happens in the absence of IR. If we can flash the plant right after we turn the red lights off with IR we can shorten the "night" by two hours"


I am wondering about this, as I have heard it also, someone told me a link, and will find it later ( short on time ) and wonder the effects of it, if used in a "normal cycle" ( 12/12 ) and not in what I think the suggested would be ( more light time on 14/10 )

 

[habeeb]

am I jacking the thread??

here's some info I have copied and pasted who knows when , on blue light and cryptochromes:

"Blue light systems

As for the red/far-red system, plants contain multiple blue light photoreceptors which have different functions.

Based on studies with action spectra, mutants and molecular analyses, it has been determined that higher plants contain at least 4, and probably 5, different blue light photoreceptors.

Cryptochromes were the first blue light receptors to be isolated and characterized from any organism. The proteins use a flavin as a chromophore. The cryptochromes have evolved from microbial DNA-photolyase, an enzyme that carries out light-dependent repair of UV damaged DNA.

Two cryptochromes have been identified in plants.

Cryptochromes control stem elongation, leaf expansion, circadian rhythms and flowering time.

In addition to blue light, cryptochromes also perceive long wavelength UV irradiation (UV-A).

Phototropin is the blue light photoreceptor that controls phototropism. It also uses flavin as chromophore. Only one phototropin has been identified so far (NPH1). Phototropin also perceives long wavelength UV irradiation (UV-A) in addition to blue light.

Recent experiments indicate that a 4th blue light receptor exists that uses a carotenoid as a chromophore. This new photoreceptor controls blue light induction of stomatal opening. However, the gene and protein have not yet been found.

Other blue light responses exist that seem to function in plants that are missing the cryptochrome, phototropin and carotenoid photoreceptors suggesting that at least one more will be found.

Since the cryptochromes were discovered in plants, several labs have identified homologous genes and photoreceptors in a number of other organisms, including humans, mice and flies. It appears that in mammals and flies, the cryptochromes function in entrainment of the biological clock. Indeed, in flies, a cryptochrome may be a functional part of the clock mechanism."




also found this on another blue light receptor:



"Other plant photoreceptors include cryptochromes and phototropins, which are sensitive to light in the blue and ultra-violet regions of the spectrum. "




"Phototropism is directional growth in which the direction of growth is determined by the direction of the light source. In other words, it is the growth and response to a light stimulus. Phototropism is most often observed in plants, but can also occur in other organisms such as fungi. The cells on the plant that are farthest from the light have a chemical called auxin that reacts when phototropism occurs. This causes the plant to have elongated cells on the farthest side from the light. Phototropism is one of the many plant tropisms or movements which respond to external stimuli. Growth towards a light source is a positive phototropism, while growth away from light is called negative phototropism (or Skototropism). Most plant shoots exhibit positive phototropism, while roots usually exhibit negative phototropism, although gravitropism may play a larger role in root behavior and growth.
This is very important!
Phototropins are photoreceptor proteins (specifically, flavoproteins) that mediate phototropism responses in higher plants. Along with cryptochromes and phytochromes they allow plants to respond and alter their growth in response to the light environment. Phototropins may also be important for the opening of stomata.

Phototropins are autophosphorylating protein kinases that activate in response to blue light. When blue light hits the phototropin protein in the cell membrane, the phototropin protein will unfold and undergo phosphorylation that can cause a cascade of events inside of the cell.

Phototropins are part of the phototropic sensory system in plants that causes various environmental responses in plants. Phototropins specifically will cause stems to bend towards light, and stomata to open. Also, phototropins are important in chloroplast movements inside the cell. They also mediate the first changes in stem elongation in blue light (before cryptochromes become active) and phototropin 1 also is required for blue light mediated transcript destabilization of specific mRNAs in the cell.
Phototropism in plants such as Arabidopsis thaliana is directed by blue light receptors called phototropins.[1] Other photosensitive receptors in plants include phytochromes that sense red light[2] and cryptochromes that sense blue light.[3] Different organs of the plant may exhibit different phototropic reactions to different wavelengths of light. Stem tips exhibit positive phototropic reactions to blue light, while root tips exhibit negative phototropic reactions to blue light. Both root tips and most stem tips exhibit positive phototropism to red light"

 

[Crusader Rabbit]

am I jacking the thread??

No, because of your questions in your other thread related to this, it has been revitalized.

"It's alive. It's ALIVE!"

 

[budlover123]

Hello, I thought I should pop into this thread again and mention aliexpress.com, because sometimes advertising is a public service, like when you can get 700mA 3-channel DMX controlled LED drivers for $16 and great prices and availability of cree and generic 1-3 watt LEDs mounted on star boards (fyi "star" is a good keyword to include in your search over there). If you go to the forum on Lighput.com in the general LED discussion section there's a thread about affordable dmx drivers where much much research is being done on these products. you might want to check it out. I got some 420nm and 405nm LED's on order right now. A supplier I got the 420nm LED's told me I can get LEDs in wavelengths as low as 365nm!

a search for "LED star 1w" on aliexpress is a good demonstration of how not all 1-Watt and higher LED's are created equal. But at least there you can get amazing deals on them, like 50 cool white 100 lumen @350 mA for like $18 shipped to the US!

http://lightput.com/forum/viewtopic.php?f=4&t=520

You could build the lighting for little experimental test grow rooms with 9 high powered LEDs with Lenses for under $40 a room with supplies from here. maybe 6 warm white, 3 blue you could use DMX control to keep the rooms all timed differently. I'm pretty sure that using a 24V adapter with some of these cheap drivers would allow you to have around 6 LED's per channel, but I have trouble finding cheap 24V adapters, 12V ones are everywhere for cheap. The LED driver at the bottom of the thread, the PX703 can work with up to 48V DC adapter, you could probably power over 12 LEDs at 3-watts (700mA) using one of those. I Imagine 48 Volt DC adapters aren't too cheap though

If a good grower with good methods could do a well documented side by side testing out some of these theories at the same time doing the same things except light schedules which are all computer controlled, that would be pretty awesome and, I think, an argument for legalization right there if any significant findings happened.

If you were running Lightput 24-hour timer, make sure you turn off day light savings time auto adjustments in your OS, the timer follows the current system time.

I guess 1 driver per room might be kind of weak, even with using good lenses, this is a better idea for a test

each grow room has 2 dmx controlled drivers (6 dmx channels per room)

4 channels are filled with warm white LEDs
1 channel is filled with 420nm LED lights
1 channel is filled with 445nm LED lights

2 grow rooms (veg stage)
room 1 - 24 hour 420nm light, 24 hour 445nm light 18 hours warm white light
room 2 - 18-hour 420nm light, 18 hour 445nm light 18 hours warm white light

I guess red should be in there somewhere too

I looked into 48V adapters. You can get them on Aliexpress for about $30-$40, one of these cheap PXM703 $16 LED drivers should power 9-12 LEDs per DMX channel, 27-36 LED's total using it in conjunction with a 48V adapter. You could build an impressive DMX controlled light for around $100 If you already have a heatsink to use.

I also like the idea of testing different intensities of the blue throughout the night period, like less blue for the first 2 hours, that would be easy using computer controlled lights, as well as the far red right after lights out tests.

 

[budlover123]

I guess a controversy is better than an answer. I'll get around to doing these experiments on legal plants eventually.

 

[Martian Meds]

Rabbit, you seem to actually understand most of the PAD info.. Great Job.. Now if we could just get others to understand..

 

[ghostmade]

tag

 

[Martian Meds]

I no this might seem silly to most reading this.. But if one wants to practice with this method. Here are some very cheap bulbs to work with..


Ruber's simple PAD method would use just the Red cfl's and the Blue cfl's with two timers.

Ruber's advanced PAD method would use all three bulbs and three timers. Of course the advanced method get a little complicated with three timers.. You need to use an invert or a flip flop switch as they are called in the grow stores.

The use of the invert or flip flop switch is for the 660nm and 730nm 1/2 hour cycles in the advanced PAD setup..

It seem without an invert or a flip flop switch it impossible to keep the two timers in perfect half hour segments.. If the 660/730 cycles aren't in exact half hour segments.. It throws the time factor way off... Meaning, the plants will think they are either getting to much darkness or not enough darkness.

So the advanced PAD method needs some timer adjustments at first to get the exact half hour segments.. But once you get that part tackled the rest is down hill..

The simple method using just red and blue bulbs is MUCH easier to setup.. But of course the simple method is mostly for veg.. 18/6

I guess I need to post the manual up.. Since my space no longer has it up there..

 

[Martian Meds]

Here is the spectrum charts for the red and blue bulbs..

 

[Martian Meds]

Only the Red cfl and the Black inc bulb are actually considered to be a PAD light.. The blue cfl is not a PAD light and should not be ran during the darkness.

Of course unless your trying to sex a plant.. In that case we need to start a dif thread.. lol

 

[Only Ornamental]

First of all, a really interesting subject!
True, I did not read everything to a 100% but I may still state that especially Tony's line of thoughts is majorly flawed (please Tony, take no offence).
There are too many errors, misunderstandings, mix-ups etc. for my taste and they certainly lead to confusion.
Example, post #11 by Tony: The blue and red are the arbitrary colours of the lines with which the two absorption spectra are drawn, not the light they absorb.
Absorption spectra of chlorophylls have nothing to do with flowering, circadian rhythm or night length. They show what part of the light spectrum can and will be used to make energy (i.e. both chlorophylls absorb in the blue and the red part of the spectrum).

Okay, I don't like folks pestering around without giving useful input. Therefore a brief summary:

General stuff first: If we speak of blue, green or red light, we may talk of different things. A we speak of a part of the light spectrum, B we talk about bulbs with apparent coloured light but still emitting the whole spectrum, C we mean monochromatic light like LEDs shining really only in one specific colour/wavelength, or D we mean light filtered over a bandpass of a given width. If you use a 'blue' CFL, you're in case B, your plants get the whole spectrum with the normal biological responses to daylight only that the emitted spectrum may overlap better with the blue absorption max. of the chlorophylls. We can only draw scientific conclusions when using monochromatic LEDs or expensive bandpass filters (maybe more to that later).
There's also the expression 'light temperature' (p.ex. 2800 K or 'warm white') circulating which indicates the perceived light colour by the human eye/brain and has no correlation to whatsoever in plants. Another thing which troubles me are 'reptile' lights: First, ExoTerra products are of low quality and you shouldn't believe their advertisement as it usually is wrong, only half the truth, a terribly bent truth, or all these together (like that crap with the 10% UVB and alike -> join a good forum for reptiles). Second, a good reptile light has four main characteristics in terms of light spectrum: UVB starts above a DNA damaging wavelength but falls well in the range where vitamin D can be synthesised, long-wavelength UVA is present as it is visible for reptiles and most other animals, the 'visible' spectrum has a high CRI (close to the spectrum of sunlight) and it focuses far red and IR in the lighted zone. They are nice products for UVA because they're nearly the only ones available but they have a 'crappy' spectrum for plants. Common HIDs and CFLs contain a UV impenetrable outer bulb to avoid as much UV as technically possible and hence resulting in negligible amounts at more than 10 cm distance (for < 150W HIDs and all CFLs).

Now to the plants:
It is important to know that many investigations have been done with Arabidopsis thaliana, a long-day flowering plant. Transposition of these results to cannabis, a short-day plant, may be biased (like the 'cry2 suppresses the phyB inhibition of floral induction' in A. thaliana may be the activated in cannabis?). Secondly, several publications I found regarding light sensing were done with germlings and not mature or flowering plants.

There are two forms of chlorophyll in higher plants. The ubiquitous form a which is best suited for direct sunlight and form b expressed mainly in shaded parts of the leave. Every plant species has its own proportion of the two and some even change it according to requirement.
Knowing their spectra helps finding an efficient light source.
Growers seek principally two things: A A light source transforming as much electricity into light ('technical efficiency') and not heat and B a light spectrum which can quantitatively be transformed into energy by the plant ('biological efficiency'). The former comes in form of HID (metal halide or HPS), fluorescent lights and LEDs. The second is determined by the overlap of the bulbs emission spectrum and the chlorophylls absorption spectrum.
Assuming you use a bulb with uniquely green light will result in nearly no absorption, the plant behaves like in deep shadow. Even a 1000 W green light will give a crappy harvest and you basically pay your electricity bill for nothing. But you can use a green light (given that it does not emit neither blue nor red) to look at your plants without them noticing it (for them it will do really nothing at all). Using an expensive full spectrum ceramic metal halide burner with a top-notch CRI (great light for the human eye) will result in a good overlap in the blue and red part but over 1/3 of the bulbs light falls into the green range and is wasted. A standard HPS spectrum is very orange-red with a good overlap above 600 nm but still, a good part of the spectrum (yellow) is poorly absorbed. There isn't much of a blue emission but that does not count (if you don't know why, ask!). On the other hand and maybe by chance, the spectrum of a 10'000-15'000K HID has most of the spectrum in the blue absorption maxima of the chlorophylls and would be optimal for electricity to growth efficiency.
But we're talking cannabis and growth isn't all. Some of us want the plant to behave different than naturally destined and only looking at which light gives the most growth for the lowest bill isn't enough.

That brings me to the flowering, circadian rhythm and night length.
Plants have light sensing molecules/proteins.
One are phytochromes (nice link HERE): There are two main forms used differently in different species and reacting species-dependent towards varied light intensities; also, only the activity of phyB to intermediate light is reversibly. Phytochromes in the resting state (Pr) absorb red light at about the same absorption maximum as chlorophylls. Once excited, they change form (Pfr) and absorb now far red light (where chlorophylls don't absorb). The trick is now this: In direct sunlight, the plants get red and far red, the balance is towards the Pfr form signalling the plant to grow normally (stocky). In the shade of other leaves, only far red is present (as the red is absorbed by the chlorophyll of shading leaves) pushing the equilibrium to the Pr form. This tells the plant to grow tall in an attempt to outgrow the shading plants ('shade avoidance').
During the night, as stated in earlier posts, the Pfr form spontaneously returns to the Pr form within two hours. At this point, the plant would react like in daytime trying to grow taller if it weren't for the light sensing cryptochromes telling here if it's day or night. We can use that to our advantage by applying far red light on 'lights out' to immediately obtain the Pr form or to reverse the effect of a short term light flash in the night (remember, cannabis flowers when the nights are long, not the days short!). We can't trick the plant to think it's a long night by applying far red during illumination because any sort of illumination causing growth (light absorbed by chlorophyll) will either activate cryptochromes or phytochromes and hence the plant knows always if its day. Well, there are two important forms of cryptochromes which both absorb (and hence detect) blue light in the range where the chlorophylls also show an absorption maximum.
As stated in a like a few posts back, one form is important to tell the plant whether it's day or night. Basically, they shut the 'dark condition mechanism' down so that the plant won't panic and try to grow out of the shadow in the middle of the night but will realise when they're kept in the dark for several days.
The other form is responsible for the synchronisation of the inner clock with the actual day-length resulting in the true circadian rhythm. This is important because the inner clock is species dependent and has days from 20 to 30 hours sometimes with individual differences.
With most lighting we apply some blue to the plants and they will realise that it's day and we also apply some red immediately shifting the equilibrium between Pr <-> Pfr towards Pfr. Concurrently, they will switch off the 'night response' and switch on the 'daytime business' and we can't trick them with far red. If we apply blue light at a wavelength which is absorbed either by chlorophyll or cryprochromes (as said, the two are strongly overlapping) in the night, the night for the plant ends within minutes. The only way to stop damage to a flowering cannabis mom is to apply far red shortly after switching on (and quickly off again!) the blue light source. We could use other wavelengths not detected by the plant during the night but they can neither use these by chlorophylls...

That means: No theoretical way of cheating the plants with blue or far red light except at 'lights out' by using a short far red light pulse (>700 nm).

What remains to be tested is the effect of blue light v.s. red HPS where one light sensing part in either spectrum lacks.
From what I've read so far, cannabis plants grow differently under a 'blue' spectrum versus an 'orange' spectrum.

One could grow plants in 'pure' red light; on one hand they should think it's night due to a lack in cryptochrome activation while on the other still producing energy and obtaining the 'enough light' response from the phytochromes. Plants may get really troubled by that! But it's unlikely that there are affordable red light sources (imperatively >550 nm) apart from LEDs and I really don't know if the costs and efforts would pay off with regard to harvest quantity and quality. Someone else should try that...

I'm sure I forgot several things but I also think that's enough info/recap for now.

 

[Martian Meds]

I posted the reptile black light bulb as a cheap far red source for use in an advanced PAD setup..

One can also use a standard 75 watt Black incandescent bulb as well.

Below is a spectrum chart for a standard 75 watt Black light bulb made from woods glass. Yes it does omit a tiny bit of UV and because the woods glass on these standard inc bulbs have variations in them.. The amount of UV contamination can vary depending bulb..

So I like the reptile ones for consistency. But both work.


But I will say.. Red light has a few tricks up it's sleeve. 660nm and 730nm both have tricks that are not widely known to the public.. Yet!

Found this info on 75 watt incandescent black lights.

The spectrum of an incandescent will always roughly follow a black body curve. It will always have high IR output, medium visible output, and low UV output. Woods glass only filters visible, and IR is still passed. So you're still left with high IR output and low UV output. Here is a typical 75W tungsten black light:

 

[Martian Meds]

Growing a plant in a 24 hour pure red 660nm spectrum has been done.. It will veg for a few months then go into flower and take approx 3 to 4 months to finish with small flowers. All under 24 hours of pure red spectrum.

But BLUE light can't contaminate the growing area or the plant will start to veg..

 

[Only Ornamental]

I posted the reptile black light bulb as a cheap far red source for use in an advanced PAD setup..

One can also use a standard 75 watt Black incandescent bulb as well.

Below is a spectrum chart for a standard 75 watt Black light bulb made from woods glass. Yes it does omit a tiny bit of UV and because the woods glass on these standard inc bulbs have variations in them.. The amount of UV contamination can vary depending bulb..

So I like the reptile ones for consistency. But both work.


But I will say.. Red light has a few tricks up it's sleeve. 660nm and 730nm both have tricks that are not widely known to the public.. Yet!

Found this info on 75 watt incandescent black lights.

The spectrum of an incandescent will always roughly follow a black body curve. It will always have high IR output, medium visible output, and low UV output. Woods glass only filters visible, and IR is still passed. So you're still left with high IR output and low UV output. Here is a typical 75W tungsten black light:

Wait, black light or Wood's light usually revere to UV lights but you show here a spectrum of an IR light... there's something weird. Also, Wood's glass has a cut-off at 400 nm and wouldn't do that much good in a plant.
But this spectrum would work as a far red source (the one to simulate a longer night) as it emits only above 700 nm.

Your older two spectra overlap very nicely with the blue and the red absorption maxima of chlorophyll. The biological efficacy would be great just that such bulbs (filtered ones) have a low technical efficacy and you can't economise electricity.

Also, incandescent black lights give off a very weak UV but heat up a lot (so give off also IR due to the filter).

Gotta go...

 

[Martian Meds]

I use the black inc (woods glass) for a 730nm far red source NOT a UV source.. I don't damage my plants with UV.. I avoid as much UV as possible. UV is a blue light trigger and must not be present during PAD darkness or plants will start to veg.

But yes.. Black inc bulbs give off a tiny bit of UV.. But it's so small it don't trigger BLUE light veg.. But some of the cheap standard 75 watt ones will bleed more UV then others because of the woods glass inconsistency.. (hence why I use the reptile ones).. The reptile Glass seem to be more contestant to me.. That's all. Nothing more nothing less.

So just to clear up why I posted those three bulbs..

Advanced PAD requires three spectrum's.. 420-450nm blue 660nm red and Far red 730nm. All three spectrum's put on three different timers and cycled properly.. You can flower with 24 hours of light with this method. Those three bulbs are a cheap way to practice PAD before setting up a flowering room and finding out one needs practice with timer synchronization.

Simple PAD requires just Blue 425-450nm and 660nm red and two timers.. This is for veg 18/6.

I will post the PAD manual.. It's 22 pages long. But I will post it..