O. crenata germination was not influenced by the rest of
compounds tested in this work except for scopoletin, which
also had minor inhibitory effect. Scopoletin and other
coumarins excreted by sunflower roots have already been
reported to have an inhibitory effect on O. cumana seed
germination.38
The view of Hedge and Miller39 that the inhibitory effect
associated with allelopathic plants is often more pronounced on
growth of an indicator plant than on its germination was
confirmed in this work for O. crenata. All the metabolites tested,
including those that were ineffective in seed germination,
inhibited the growth of O. crenata radicle to some degree,
although there were large differences in the dose response