Na is also an essential micronutrient for some plants - its not clear if it
is essential for all. Peter Fergus Brownell (Brownell the Brutal to his
students!) demonstrated that, although not required by C3 plants, it is
required by C4 plants (probably from all groups) and CAM plants - the
latter only if they are only fixing CO2 at night. It is not essential for
CAM plants that also fix CO2 during the light by C3 processes. There may
also be some obligate halophytes.
As for chlorine and nickel, the demonstration of essentiality requires
stringent procedures to prevent contamination from environmental Na.
Brownell recrystallises his nurient salts several times in silica-glass
containers, his water is double-distilled in silica stills and plants are
grown in filtered air in a pressurised glasshouse to reduce contamination
from Na-containing dust.
Joe Holtum
Dr Joe Holtum
Dept of Tropical Plant Sciences
School of Biological Sciences,
James Cook University of North Queensland,
Townsville, North Queensland 4111
AUSTRALIA
Facsimile: - 61 (int) 07 47 251570
Telephone: - 61 (int) 07 47 814391
E-mail: - joseph.holtum at jcu.edu.au
