Allelopathic Barley

["David A. Youngker" <nestor10 at mindspring_com>]

> Date: Fri, 3 Jan 2003 14:10:23 EST
> From: Duane Clark

> I know this subject has come up before but I do not believe
> it has been explored thorowly enough with regard to it's
> application in the freshwater/planted aquarium...

Could this be because its efficacy hasn't been positively established in the
_larger_ bodies yet?

> The implementation of a testing model would be very interesting
> (I have developed such a model but have not put into action yet).

Does this model include the necessary "activation period" for the straw?
Does it also account for the need to keep the water essentially _unchanged_
throughout the testing period? After all, we're not only emulating ponds
(and not streams), but for all intents and purposes using it as a
replacement for "allelopathic" compounds - how would a regimen of water
changes allow for sufficient concentration?

Outside of the inability of, say, Perdue University (
http://www.sfapms.org/Articles/barleypub.pdf ) or Ohio State University (
http://ohioline.osu.edu/a-fact/0012.html ), among others (North Carolina and
Florida State), to provide *positive* results, the majority of "studies" and
sites attribute the effect to "the release of _some chemical_". Hmm...sounds
quite a bit like most of the sites on aquatic allelopathy, come to think of
it.

> Date: Mon, 6 Jan 2003 17:55:16 EST

> If something like this could work...then it is certainly
> worth investigating.  I just think it is worth looking into
> with an open but always cautious and questioning mind.
> In any case...sure sounds like a good topic to study
> for awhile.

One site that *does* attribute it to something more than magic or smoke and
mirrors states:

"When straw rots, chemicals in the cell walls decompose at different rates.
Lignins are very persistent and are likely to remain and be released into
the water as the other components decay. If there is plenty of oxygen
available in the water, lignins can be oxidised to humic acids and other
humic substances. These humic substances occur naturally in many waters and
it has been shown that, when sunlight shines onto water which contains
dissolved oxygen, in the presence of humic substances, hydrogen peroxide is
formed." ( http://www.exit109.com/~gosta/pondstrw.sht - which is one of the
English sites, by the way)

So don't forget that _high DO levels and sunlight_ would be essential parts
of the study as well. Wouldn't *that* be a tricky balance, even in a large
tank?

Maybe it's just me, but it sure seems that nutrient balance and water
changes are quite a bit easier to control and account for...


-Y-

David A. Youngker
nestor10 at mindspring_com