We observed a 42% O. crenata radicle length reduction at the
highest concentration tested of benzoic acid. Benzoic acid had
already been reported to reduce the root length of plants such
as lettuce45 and mustard.
We found that coumalic acid did not inhibit the germination
of O. crenata seeds, but once germinated, radicles exposed to
coumalic acid were significantly shorter. Coumalic acid has
been reported as having an allelochemical effect in Ageratum
conyzoides against the early growth of rice.22 It has been
associated with autotoxicity under continuously monocropped
peanuts and Rehmannia glutinousa.
Gramine has been reported to inhibit the germination and
seedling growth of white mustard25 and to reduce the
vegetative growth of chickweed.In our experiments, gramine
did not affect the germination of O. crenata seeds. The growth
of the O. crenata radicle was slightly reduced (by 25%) at
maximum concentration.