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Re: iron gluconate



I suspect its possible that for a given concentration of iron
(gluconate) compared with the same concentration of iron (EDTA) that the
foliar intake of the iron gluconate -might- be higher because in both
cases (I assume) the mechanism is:

1) the action of Fe reductase (changes Fe+++ complex to Fe++ complex) at
the plasma membrane (this won't be necessary if the complex is Fe++
already)
2) the breaking of the Fe++ complex (how does this happen?)
3) the passage of Fe++ through an Fe channel

The same mechanism is going to be used by algae cells and so there is no
net advantage to the macrophytes. If you want to maintain a given level
of Fe uptake, you would use a slightly higher concentratin of Fe-EDTA. I
don't believe, for aquarium purposes, the higher cost of Fe-EDTA is
going to be significant compared to other retail cost factors. One could
argue that Fe-EDTA is more cost effective because it should be available
longer in solution and less susceptible to bacterial breakdown. This
would be especially true if the plants are not reliant upon bacterial
break down and can utilize Fe-reductase. If on the other hand reductase
is not present in the foliar cell membranes, then maintaining Fe++ (such
as gluconate) would be important for uptake.

Dave, can you confirm if Fe reductase is used for foliar uptake? I
didn't get a response yet from Dr Jones.

Steve Pushak                              Vancouver, BC, CANADA 

Visit "Steve's Aquatic Page"      http://home.infinet.net/teban/
 for LOTS of pics, tips and links for aquatic gardening!!!