The Value Of Green Light

[jewels]

Found an intersesting article on the effects of light spectrums; specificly green. Although mostly over my head , I have deduced that we asumed red and blue soley drove photosynthesis because that is what cloroplasts so readily absorb. However green light had greater penetration and thus becomes available (present) to more [of the] tissue.

http://pcp.oxfordjou...t/50/4/684.full

" In other words, < 1% of the red or blue light is transmitted through the chloroplast. On the other hand, for wavelengths that are weakly absorbed, such as green light, T is considerable. When ε for green light is assumed to be 500 m² mol^–1, A and T would be 0.05 and 79.4%, respectively."

[Iceturf]

Interesting observation. Are you thinking that this is of benefit due to the fact that it would mean energy in the form of sugars is available more directly verses transportation methods?

[troni]

So from a scale of 1 to 10 red and blue are absorbed at 10 but only reach the plant at 1 while green is a 4 it ends at 3 lmao if that makes sense.

[werner]

Interesting! The article is based on "woody plants grown outdoors in high light." Wondering if the same holds true for aquatic plants grown submerged in moderate light? Water would modify the light quality significantly, and the leaf structure is different too.

Here's one for you: http://books.google.ca/books?id=It5GePwa2EIC&printsec=frontcover&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false

[Iceturf]

I would suspect though that with more penetration means more energy lost to heat when the light hits other structures (ei not cloroplasts) where as if other wavelengths are more readily absorbed perhaps higher overall efficiency.

[jvision]

I'm kinda thinkin the same thing - just because green light penetrates, doesn't mean it's useful, it just means it penetrates more.

[jewels]

"data shown in Figs. 10 and 11 clearly demonstrate that green light more effectively drove photosynthesis than red light in the white light at high PPFDs.

,,,Namely, red light is more effective than green light in white light at low PPFDs, but as PPFD increases, light energy absorbed by the uppermost chloroplasts tends to be dissipated as heat, while penetrating green light increases photosynthesis by exciting chloroplasts located deep in the mesophyll. Thus, for leaves, it could be adaptive to use chlorophylls as photosynthetic pigments, because, by having chlorophyll with a ‘green window’ the leaves are able to maintain high quantum yields for the whole leaf in both weak and strong light conditions"

The "high" ppfd's of which they speak, granted are higher than what is typicly seen @ the substrate in our aquariums.

The reason I found this intriguing was due to odd values Iwas getting from my Apogee PAR sensor.

It would seem the metre really could care less about the manufactures spectral plots. I got equal values from a well used Marine-GLO bulb vs.'s a spanking new 6500K bulb.

Long story short - buy bulbs that emit a colour you find pleasing.

[ubr0ke]

yup..ive been saying this..color temp is for our eyes only...the plants do not care

also t5's seem to keep relatively the same par from brand new to the day they burn out.

t-8 or 12's not so much

Edited December 2, 2011 by ubr0ke

[PistolPete]

Green light is useless to some plants. In fact plants that need a constant light/dark cycle are not interrupted by green light at night