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Re: potassium & big uns

Roger S. Miller wrote, Fri., Apr. 3:

>....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 plants?
Potassium seems to have mostly 'nonspecific' roles in plant cells.  It
contributes to turgor pressure and osmotic balance---rather vague terms.
It is definitely needed, and sodium can not substitute for it.  Many
enzymes in cells are quite sensitive to K levels, and have optimum
activities at the levels maintained in cells.  These nonspecific roles
account for virtually all the potassium needed, and potassium in algal
cells presumably has the same nonspecific roles.

It is interesting that aquatic invertebrates exposed to changing salinities
can adjust the amount of solute in their cells to maintain the correct
osmotic pressure.  They do this by increasing or decreasing the amount of
dissolved amino acids in their cells, and they don't change the amount of
potassium, which they need to keep relatively constant because potassium
has a very similiar nonspecific role in animal cells.

Michael Reid wrote, Fri., Apr 3:

>Just got 2 light units and a transformer? from the local sheriff dept.  They
>were use by a local for growing wacky tobackey.  The bulbs have a large
>screw in base, one is 9" and is a sylvania lumalux s51  LU400   some is hard
>to read  the other is a ge lucalox  LU 1000
>a little help would be appreciated

They sound big all right.  I don't know if you need that much power for
aquatic plants.  Try setting them up and then go outside and see how many
of the little dials are spinning around on your electric meter.  If the
very first in the series of dials is visibly moving, I would think twice
about using those lights.

Paul Krombholz, in summer-like central Mississippi.