mineral nutrition

Carl Pike c_pike at ACAD.FANDM.EDU
Thu Mar 4 16:10:35 EST 1999


For years I've made general-use nutrient solutions with what I suspect is a
standard recipe (it's in the Machlis and Torrey lab manual, for those of
you who go back that far, and also in the Reiss lab manual).  Only today
did I notice that this recipe has no chloride - nitrate, phosphate, and
sulfate are the major anions.  Chloride is not an essential element, but
then whenever we talk about guard cells we say that chloride (as well as
malate) is the major counterion.  Indeed, discussions of the general
electrophysiology of plant cells seem always to involve chloride.
So how come if chloride is so important it isn't in the nutrient solution?
Chloride does get added when one is, for example, making a solution lacking
nitrate -- substitute KCl for KNO3.  How do plants without chloride manage
their membrane potentials, open/close their stomata, etc.?  Can they do it
with the other anions?  Am I missing something?

Carl S. Pike                         (717) 291-3958
Department of Biology                FAX (717) 399-4548
Franklin and Marshall College        email  C_PIKE at ACAD.FANDM.EDU
P.O. Box 3003
Lancaster, PA  17604-3003  USA





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