2.3.2.
Experiment II – screening of live material
This
experiment investigated the possible exudation of allelo-
chemicals
by macrophyte shoots and their effects on the growth
of
A. variabilis. An agar diffusion assay was conducted as described
for
Exp. I. Four replicate sterile Petri dishes were each filled with
agar
as the basal layer. The second layer comprised culture medium
(BG-11
with 0.2% agar added) enriched with the target cyanobacteria
that were added after 2 h (to a height of about 5 mm) and
incubated
for 24 h. Following the incubation period, two shoots of
either
C. australis or P. crispus were placed in the centre of each Petri
dish
and were partially covered by the second layer. Young shoots
of
macrophytes (similar-sized) were used to control for variability
in anatomy and physiology of the organisms. The density of