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Re: algae, plants and potassium
>I've heard or read that potassium is used by algae and plants for
>turgor, phototropism and transport. Are there other important roles?
>It seems to me that these functions (with the exception of turgor)
>might be much more important to higher plants than they are to algae.
>I've never heard of algae "following the sun" and they would seem to
>have much smaller transport requirements than higher plants.
>Does a shortage of potassium favor the growth of algae over higher
I don't see how. K deficiency would be equally perturbing to both, as
algae have approximately the same K requirements as higher plants,
i.e., their intracellular K concentrations are about equal. Both have
an amazing ability to uptake and concentrate K many many times greater
than that of their external environment. K is also an activator of
some enzymes, BTW. It's mainly the osmotic requirements for K that
cause plants to concentrate it in their cells, though.
However, potassium is strongly adsorbed by many soils, so if you have
a substrate with a high potassium-binding capacity, then I can
envision a situation where the water column could be low in potassium,
but the soil could have tons o' K. Here, it seems this situation
would favor rooted plants over non-rooted ones.
Kinda like that P-limiting idea Sears and Conlin came up with ;-)