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Re: [APD] Aquatic-Plants Digest, Vol 31, Issue 38

The O2 evolution over a PAr range is actually even and tapers at
the ends. 
So that chart with the two Chl a/b and carotenoid does not
represent the plant light harvesting complex.

Light is not that simple nor at the plants. There are a number
of assessory pigments and these pigments can be changed over
seconds, minutes, hours, days, weeks to accomodate the given
light quality and quanatity.

Even though there is a dip in the graph, there is not a dip in
the amount of photosynthesis that takes places as you scale the
nm range up and down except near the very ends. 

So if plants are not able to use it, or are very poor at it, why
wouldn't we see an associate drop that was porportional to light
and O2?

O2 evolution over that same gragh does not have that dip in most
Tom Barr 
> Yes with accessoric pigments, but very inefficiently:
> The dip in the yellow-grreen is where it hurts.
> > The spread is not about the blue in the High-kelvin though,
> but
> variations in the far-red part of the spectrum:
> http://www.cc.jyu.fi/~aphalo/old_pages/pdf/notes1.pdf

That part is true, phytochrome mediates that and is very
sensitive, actually extremely sensitive.

I've tried to tell people in the past this, few understood it.
"Blue light penatrates deep, makes plants all bushy etc, blah
blah." Nope, canopy formation in weeds competition really shows
the red/far red effect and how sensitive it is.

Blue may open some of the stomata farther(at least this seems
true for terrestrial plants), but some plants like Egeria and
Hydrilla don't even have stomata. They don't need stomata. 

> Best regards
> Daniel Larsson

Tom Barr

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