Benzoxazolinones were again very active metabolites
interfering with O. crenata radicle growth. Their growth
inhibitory effect on other plant species has been attributed to
the ability to modify auxin action40 as well as the enhancement
of cell wall peroxidase activity, which leads to increased
production of H2O2 and premature lignification of cell walls.41
We observed differences in inhibitory effects in the three
benzoxazolinones studied, suggesting their influence on the
selectivity toward the inhibition of O. crenata. Similarly,
inhibition of the auxin-induced growth of etiolated coleoptile
in maize with benzoxazolinones carrying an alkoxy group at the
C-6 position has been reported,42 but (1) without a side chain
and (2) with benzyloxy ring at C-6 did not show the inhibitory
effect.