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Allelochemicals, roots and competition
> From: Stephen.Pushak at saudan_HAC.COM
> Date: Thu, 21 Sep 95 18:03:25 PDT
> Subject: Re: Allelochemicals, roots and competition
> Yet A. mad. will
> continue to show very slow growth even with trimming back the
> neighbours.
I'm not at all sure that what you are seeing in this case is
competition.
> Some even suggested that Crypts and this Aponogeton
> had an affinity; increased oxygenation due to the roots of the
> neighbour.
Although it is possible that increased oxygenation (or
circulation) is beneficial to A. mad.,(it certainly seems to be to
other rooted plants) it seems unlikely that this is a Cryptocoryne
specific phenomenon. They don't even come from the same
continent, so this would be a strange adaptation, indeed. ;-)
> For the Madagascar Lace plant we've got to focus on that individ
> since its demands seem so exact and unfortunately, unknown.
I agree with you completely here. In fact, I have read several
reports of success where the plants were kept either as a single
specimen, completely by itself, or else in a monoculture.
> John Madesen wrote:
> > I am replying to the comment about rooted plants outcompeting
> > for nutrients. Scientifically, there is no good basis for thi
> > if you mean nutrients in the water. Research has shown that r
> > plants take most of their required nitrogen and phosphorus fro
> > sediment, not the water.
>
> This is very fascinating indeed. Perhaps all of our supplementat
> should be done within the substrate. It also corroborates the
> theory that iron-oxide in laterite is useful for fixing phosphat
> in the substrate. It makes me wonder more about the value of a
> slow RUGF system with an iron-oxide, high CEC substrate. Maybe
> it is a case of serendipity that a particular tropical or subtro
> location may support this Aponogeton and one should take soil
> samples and observations there to attempt to duplicate this.
John's comments may be correct as far as they go, but dismiss the
fact that _many_ of the plants we use in the aquarium are
(completely or in part) _not_ root feeders, and their needs must
be met as well.
Karen Randall
Aquatic Gardeners Assoc.
Boston, MA