RESULTS AND DISCUSSION
Inhibition of O. crenata Seed Germination. No
germination was observed in the O. crenata seeds treated
with the negative control. High levels of O. crenata seed
germination (72.9%) were achieved in the positive control
GR24. Moderate but significant O. crenata seed inhibition
(around 33%) was caused by 2-benzoxazolinone (1) when
applied at rates higher than 1 μg/mL. No effect was observed
for 6-benzyloxy-2-benzoxazolinone (2) at any doses applied.
On the contrary, germination was markedly inhibited in
presence of 6-chloroacetyl-2-benzoxazolinone (3), with a
moderate but significant inhibition when applied at 1 μg/mL
and a complete inhibition of germination at concentrations
higher than 4 μg/mL (Figure 2). All other allelochemicals
tested had little or no inhibitory effect at any dose, except for
scopoletin that caused slight inhibition (19%) at concentrations
≥13 μg/mL (Figures 2B and 2C).