Re: Re: [AGA Member] Red Pigment-K spectrum anecdotes

["Stephan Mifsud" <valerandi@nextgen.net.mt>]

MotomanBarton@aol.com Bevan said
> Subject: Re: [AGA Member] Red Pigment-K spectrum anecdotes
>
>Red plants NEED high light because of the red  and green
pigment thing I mentioned earlier.
>Also their are not a lot of red
> plants that have a stem strong enough to survive out of
water. Why? I donna!

Most Red Plants DO NOT 'NEED high light'. Quite the
contrary. Just because Red plants are associated
with strong light does not imply a NEED:-
1) The deepest ocean plants are red algae. Does that imply a
need for strong light? And I can assure you that
the amount of red algae throughout the oceans is
considerable.
2) We have many red/purple/brown plants here in the
Mediterranean. But they do not NEED bright light.
In the darker winter light they turn green. They develop the
red colour in bright spring/summer light as a sunscreen.
3) There are also a number of arctic/tundra plants which are
brightly coloured. The Northernmost points of our globe are
the domain of coloured lichens, and for most part of the
year they live in the dark.

> And I could not tell you why some plants chose to grow in
or out of water I
> think that the fact that most of the out of water plants
are green just by
> coninsidence.

Maybe they are in your parts of the world.

> But the part that I said about the red and green pigment
is a fact!! It is
> scientifically proven.

Is it ?

.

And if I may comment/hypothesise on some of the points
discussed so far:
1) Why do many understorey/aquatic plants have a lower red
surface and an upper green. I think Phil explained it well.
To me its just a question of less waste. The stronger light
is bound to come from the top so Chlorophyll is the main
pigment there. But light rebounding from other lower
leaves/plants will be more green-blue. If it hit a lower
green surface it would be wasted. Not so with a red lower
surface. In low light situations anything helps.
2) Don't forget that nutrients also come into play. (Tom
Barr has on many occasions suggested less N inputs for
redder plants)
 Red pigments production does not require as much Nitrogen
than chlorophyll (Anthocyanins,carotenoids,xanthophylls do
not have N in their molecules). Photosynthesis with red
pigments is less efficient in white light but is also less
costly/less maintenance.
Since Red pigments are cheaper, slow growing plants living
in stessful/high/XS  light situatuations, such as many
succulents, will find red colour pigments enough for their
needs. Arid situations mean less Nitrogen availability. And
there is the sunscreen factor. A Win-win situation.
Aquatic Red Plants like Rotala below water may utilise less
costly red pigments because they are more stressed while
submerged - less oxygen(?), after all they normally grow as
emered marsh plants. Being submerged they are more stressed.
On hitting the surface, they 'breath a sigh of relief', more
oxygen, less stress, can spend more on Chlorophyll, greener
leaves.

Maybe Oxygen content should be one of the
variables/constants in the experiment.
You have'nt included any crypts/Lotus?
Maybe include UV lamps. Possibly filters for specific
wavelenghts
Take note of diatom growth!
Again good luck Phil.

regards
Stephan



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