Wavelength dependence of photosynthetic quantum yields.

[DavidCampen]

http://www.plantcell.org/content/ear...97972.full.pdf

[Magnus A]

And what are your conclusion from this paper? And what relevance has cucamber metabolism to do with orchids?

[Ray]

Good question, Magnus.

The group doing experimentation using a range of LED wavelengths are finding that the "optimal" spectrum varies from plant to plant.

[DavidCampen]

Originally Posted by Magnus A

... what relevance has cucamber metabolism to do with orchids?

Cucumbers use the same pigments and structures to absorb light as orchids do. Metabolism was not discussed.

Originally Posted by Magnus A

And what are your conclusion from this paper?

I conclude that LEDs chosen for maximally effective wavelengths are at most about twice as photosynthetically efficacious per watt of input power as a standard fluorescent lamp and that fluorescent lamps whose output wavelengths are similar to LEDs will have about the same efficacy. (This is based on current LEDs being about as efficient as current fluorescent lamps at converting input power into photons.)

[Magnus A]

Originally Posted by DavidCampen

Cucumbers use the same pigments and structures to absorb light as orchids do. Metabolism was not discussed.

Sorry, but "quantum yield for CO2 fixation" is ALL about metabolism! The light harvesting photosystem I and II do not fixate CO"...they only harvest the energy and they work in consecutive manner. The QB is produced in PSII and the electrons and protons are then transfered to PSI through the Thylakoid membrane by QB. And yes I have followed the fundamental research on energy transfer in PSII for about 10 years...

There are Many more light induced reactions in plants, protection mechanism and so on. And it has been shown that different specie reacts differently on illumination with light of selected wave lenght..

[Magnus A]

Originally Posted by DavidCampen

....fluorescent lamps whose output wavelengths are similar to LEDs will have about the same efficacy. (This is based on current LEDs being about as efficient as current fluorescent lamps at converting input power into photons.)

Same wavelenght
Same efficiency

THat meen 1 W of power in give excact the same light from your hypothesised LED and Flourecent light...

You say that a LED and a fluorescent that is "identical" have different impact on the plants metabolism to harvest the light and process it in CO2 fixation?

This is a physical impossibility!

[DavidCampen]

Originally Posted by Magnus A

Sorry, but "quantum yield for CO2 fixation" is ALL about metabolism!

Sorry, absolute quantum yield is about metabolism. This paper is comparing relative quantum yield as related to wavelength.

Originally Posted by Magnus A

The light harvesting photosystem I and II do not fixate CO"...they only harvest the energy and they work in consecutive manner.
The QB is produced in PSII and the electrons and protons are then transfered to PSI through the Thylakoid membrane by QB. And yes I have followed the fundamental research on energy transfer in PSII for about 10 years...

Yes, this is basic and does not negate my statements. It seems that perhaps you are having trouble seeing the forest for the trees.

Originally Posted by Magnus A

There are Many more light induced reactions in plants, protection mechanism and so on. And it has been shown that different specie reacts differently on illumination with light of selected wave lenght..

Again, yes, basic, but does not negate my statements.

You were the one who asked what I concluded, I had deliberately not stated my conclusions so that I would not have to argue with people who want to prove how smart they are. I see that, again, I was correct.

Take what ever you want from the article and have a nice day.

[Magnus A]

The problem with this kind of article is that most of the board member have not a clue how to read them. Therefore I asked if you had some intresting conclution to why you posted a highly advanced article on this board.

[DavidCampen]

Originally Posted by Magnus A

The problem with this kind of article is that most of the board member have not a clue how to read them.

Yes, with respect to at least some people you have proven that point. Sorry to have upset your sense of order.

[Magnus A]

As have been discussed before on OB most orchids is not C3 but C4 or CAM... : Are orchids C3, C4, or CAM plants?

So still this paper has probably very little paractical or theoretical relevance for orchids.


And still, the light source is irrelevant as long as the emitted light is the same wavelenght and at the same intensity!

Sorry to try to make light simple for the general orchid grower and trying to keep the discussion relevant for orchids....