carried out as plate diffusion assays following the procedures outlined
in Berger and Schagerl (2004). The Petri dish-based screening
assay
is designed to detect the diffusion of chemical substances
by
macrophytes through a waterbody (agar layers mimic the
water
column). These types of assays reveal the effective radius
of
allelochemical activity, which is visually evident as a clear area
radiating
out from the macrophyte (Berger and Schagerl, 2004).
These
bioassays (Exp. I and II) alone could reveal the release and
diffusion
of allelochemicals. However, a further experiment (Exp.
III)
was carried out to confirm that exudation of allelopathic agents
by
live macrophyte material could occur in an aquatic setting (i.e.,
this
experiment simulated conditions that were closer to reality).