Blue light at night the controversy rages

[Tonygreen]

Thanks for joining in the discussion OG.

 

[Tonygreen]

Another factor to consider there seems to be some literature saying plants go into dark mode 2 hours after lights off, we would probably want to wait for that before turning on the blue.

Researching more I'll come up with some more info.

 

[Buddy Holly]

where would plants have evolved to use blue light at night? am i missing something blatantly obvious here?

 

[Crusader Rabbit]

Plants didn't evolve to use blue light at night. Humans didn't evolve to read or ride bicycles. But if it works, why not make good use of it?

This really isn't that much different from using twenty four hours of light in veg.

 

[Tonygreen]

where would plants have evolved to use blue light at night? am i missing something blatantly obvious here?

The hypothesis is basically that we can modify a plants expression by messin with lighting intensity and frequency.

 

[SeaMaiden]

This part of the discussion is making me think of moonlight and what lighting is used in (typically reef) aquaria to mimic moonlight. I found this, though I'm not done searching. I want to know what the spectrum is of moonlight.

http://www.cira.colostate.edu/people/view.php?username=Miller

Ha! Just go a couple of links over and I find myself yet again reading Orphek.

http://blog.aquanerd.com/2011/03/orphek-announces-moonlight-and-pr-25-colors.html

So, there are folks putting out 'moonlight' mimic lights. I believe both of these spectrum graphs show that moonlight is mostly blue, though it does reflect the other wavelengths, but I believe that they're not strong enough to make the bounces back to earth and remain sufficiently strong (why are both water and the sky blue, Mommy?).

 

[budlover123]

I looked up micrometers to nanometer conversions and according to that 0.2 micrometers = 200 nanometers and 1.2 micrometers = 1200 nanometers, thats pretty high in the red spectrum, that graph is weird but very cool. Is that saying there's lots of red in moonlight but it looks blue because of all the very blue light (looks like > 300 nm)

Lightput would totally allow you to have blue light with a tiny bit of red and green, as a matter of fact I have my lamp like that right now because my girlfriend has a migraine.

 

[SeaMaiden]

You can see how the graph delineates between phases of the moon, too.

I'm sorry about your girlfriend's migraine. One of my sisters gets them VERY badly, and she's gone through a whole slew of medications and treatments that only work for a short time. Last thing she did that works best is Botox, but this last Tx only lasted 2mos, not the 3 that are usually discussed.

 

[2 Legal Co]

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?

Speaking of Green; I'm using a Green CFL in the room outside my Cab during the 'night',,, so far no bad things.

Blue??? interesting, I'll be watching.

 

[CFP65]

something tells me that using light no matter what colour during the night will turn on the auxin production when its supposed to sleep, and doing so on a species thats prone to express gender problems when messing with its "homonemotors" is like waving a flag for trouble, thats just my cents. and ok iwe also read some things about light during night hours from the 60.ies on other types of plants, and they say that its the wawelength of the light thats used just before darkhours that will determine the plants setting flowers. iwill try and find the book and translate the chapter here later

 

[omera1]

theres a theory that youu can reduce the dark period by using a moonlight lamp for 10 minutes right after normal lights go out. It says with this you can run 14/10 without problems in flower. more light = more photosynthesis = more yield, thats the theory...

 

[omera1]

(infrared moonlight lamps)

 

[budlover123]

theres a theory that you can reduce the dark period by using a moonlight lamp for 10 minutes right after normal lights go out. It says with this you can run 14/10 without problems in flower. more light = more photosynthesis = more yield, thats the theory...(infrared moonlight lamps)

Hello, infrared huh? All I can find for infrared moonlight bulbs are bulbs made for reptile enclosures, and it seems like the infrared they are referring too is more the heat coming off the bulb.

Infrared Light
The exothermic nature of reptiles (being cold-blooded) emphasizes the importance of infrared
radiation (heat) for thermoregulation. The infrared segment of the electromagnetic spectrum occurs
just below or “infra” to red light and is not visible. It can, however, be perceived as heat by the
skin. The sun produces most of its energy output in the infrared segment of the spectrum.
The best artificial source of heat for diurnal reptiles is through an overhead radiant source
by means of incandescent light bulbs, all emitting high amounts of infrared light (+700 nm).

Lots of heat at night could be another experiment to test out.

 

[omera1]

http://www.exo-terra.com/en/products/night_heat_lamp.php

 

[Crusader Rabbit]

http://www.exo-terra.com/en/products/night_heat_lamp.php

The bulb simulates natural moonlight to allow nocturnal viewing without disturbing the animal’s day and night cycle. The light emitted is bluish due to the use of blue glass. The heat generated by the bulb is minimal but enough to provide tropical night time temperatures. The lower wattage of these bulbs does not interfere with natural night drops in temperature.
Colour temperature: 1500 K




It looks like these are just incandescent bulbs that use dark blue glass. Enough blue light gets through to let you see your lizard in an eerie glow, but it's not even enough to show up on the wavelength chart. The absorbed photons cause the blue glass to heat up and emit long wave radiation. 660 nm is where the radiation emitted just begins to take off. These would not work for the purpose discussed in this thread.

 

[Azeotrope]

Thule - You mentioned earlier that you were/are under the impression that plants do not use green light. That is not accurate. They do use it and it can be highly effective at driving certain processes within the plant. Especially at high irradiance. Not totally on topic for this thread, but thought I'd throw that out in response.

Regards,

Azeo

 

[SeaMaiden]

Azeo, I've been searching for some papers that spurr shared some time ago. Unfortunately I deleted them from my harddrive, and can't remember what keywords to use to search Google Scholar. The papers support clearly that green wavelengths are used by photosynthetic plants.

 

[2 Legal Co]

Azeo, I've been searching for some papers that spurr shared some time ago. Unfortunately I deleted them from my harddrive, and can't remember what keywords to use to search Google Scholar. The papers support clearly that green wavelengths are used by photosynthetic plants.

Interesting; Well,, if my ladies 'hermie', I'll report back. So far, so good. I use a green CFL for 'night time' occasionally.

 

[SeaMaiden]

This is going from... I wanna say like 4yrs ago that I remember reading this stuff, but IIRC, they increase transpiration or... I want to say respiration of CO2 increases, but I'm not sure at all that's really a correct term, and I'm not sure if it's transpiration that's at work. But I think it's tied to CO2 use rates.

 

[Storm Shadow]

http://www.ncbi.nlm.nih.gov/pubmed/23020549

Physiol Plant. 2012 Sep 28. doi: 10.1111/j.1399-3054.2012.01698.x. [Epub ahead of print]
A high proportion of blue light increases the photosynthesis capacity and leaf formation rate of Rosa × hybrida but does not affect time to flower opening.

Terfa MT, Solhaug KA, Gislerød HR, Olsen JE, Torre S.
Source

Department of Plant and Environmental Sciences, Norwegian University of Life Sciences, PO Box 5003, NO-1432, Ås, Norway.

Abstract

Alterations in light quality affect plant morphogenesis and photosynthetic responses but the effects vary significantly between species. Roses exhibit an irradiance-dependent flowering control but knowledge on light quality responses is scarce. In this study we analyzed, the responses in morphology, photosynthesis and flowering of Rosa × hybrida to different blue (B) light proportions provided by light-emitting diodes (LED, high B 20%) and high pressure sodium (HPS, low B 5%) lamps. There was a strong morphological and growth effect of the light sources but no significant difference in total dry matter production and flowering. HPS-grown plants had significantly higher leaf area and plant height, yet a higher dry weight proportion was allocated to leaves than stems under LED. LED plants showed 20% higher photosynthetic capacity (A(max) ) and higher levels of soluble carbohydrates. The increase in A(max) correlated with an increase in leaf mass per unit leaf area, higher stomata conductance and CO(2) exchange, total chlorophyll (Chl) content per area and Chl a/b ratio. LED-grown leaves also displayed a more sun-type leaf anatomy with more and longer palisade cells and a higher stomata frequency. Although floral initiation occurred at a higher leaf number in LED, the time to open flowers was the same under both light conditions. Thereby the study shows that a higher portion of B light is efficient in increasing photosynthesis performance per unit leaf area, enhancing growth and morphological changes in roses but does not affect the total Dry Matter (DM) production or time to open flower.