Re: [APD] RE: substrate vs the water column

["Richard J. Sexton" <richard at aquaria_net>]

>> I don't doubt that, but aren't roots more efficient that leaves at doing
>this?
>
>At transporting nutrients to the leaves?
>Errr.........I really do not see how. There is no evapo-transpirational
>pull in submersed aquatic plants either.

No but there has to be some circulation within the plant. Photosynthesis
takes place in the leaves, not the roots and the food made there gets to 
the roots somehow.

Nyway I don't know, I'm just asking.

>> That's all roots do and there's typically as much of them as there are
>leaves.
>
>So that assumes what? A root tank?

Now that's about what a good healty colony of crypts is like. ALmost
more roots than leaves, it's sore like fungus in that you have a mass
in the subsrtate - mycelia in fungus - and stuff above ground (fruiting
bodies, or "mushrooms" in higher fungi)

>That is not all roots do, try Spadderdock, lilies, Hydrilla, Potamogeton,
>Swords, Crypts, => roots are storage organs as are leaves, they also
>provide mechanical support to  keep the lotic weeds like Swords attached in
>fast flowing water that shears the banks where they live.  

Sure, but I suspect there's some physiological differences between, say
hydrilla and crypts. Just a guess though.

>> Roots can sit in such nutrient rich muck it would turn a tank green
>overnight
>> if there was that much fertilizer in the water column.
>
>Well at 2ppm of PO4, 30ppm NO3, that is pretty mucky. No green.
>I dosed a month's worth of Flourish the other day to see what might happen.
>
>> I'm being rather crypt-centric what I say this. I'm sure it doesn't matter
>> for, say, Egeria najas...
>
>No, I say it doesn't matter for Crypts and swords, I've somehow grown them
>well in nutrient poor media for years. Swords are monstrous weeds.
>How do I manage that if that is the case? Humbug. The observations I've
>seen don't suggest they care if there's enough in the water column anymore
>than Egeria najas. 
>I've had both for many years in RFUG's together(extremely nutrient poor
>media). 
>
>> But, why do we care? Either work, both, IMO work better than either. YMMV.
>
>Perhaps "the how" is all you pursue then rather than why? 
>The need for better understanding of the __individual components__ is great
>when suggesting adding "both" together. What role does each component play
>and why?
>When someone says, Crypts or swords prefer this or that, do we really know
>they "prefer it" anymore than any other plant? 

Well, to find that out we'd have to do a comparison of plants grown in
nutrient poor water with a rish substrate and one grown in an
inert substrate and ferts in the water. With the initial weiht of the
plant and the final weight of the plant it should be easy to measure
how much they've grown. 


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