TITLE:
The Allelopathic Potential of Hairy Vetch (Vicia villosa Roth.) Mulch
AUTHORS:
Charles M. Geddes, Andrea Cavalieri, Fouad Daayf, Robert H. Gulden
KEYWORDS:
Cyanamide, Germination, Hormesis, Phytotoxin, Radicle Elongation
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.6 No.16,
October
27,
2015
ABSTRACT: Hairy vetch (Vicia villosa Roth.) has been recognized as a good candidate for weed suppressive
mulch in organic no-till cropping systems. In our study, the allelopathic potential of hairy vetch,
fall rye (Secale cereale L.) and winter wheat (Triticum aestivum L.) (extracted species) were evaluated
at both vegetative and reproductive developmental stages (extract stage) based on the
germination and radicle elongation of five response species using aqueous extracts in soil microcosms.
Our study found hairy vetch shoot extract to have little allelopathic potential compared to
fall rye or winter wheat, both species for which the allelopathic potential is well documented. Interestingly,
hairy vetch was the only extracted species to increase in allelopathic suppression of
radicle elongation at the reproductive stage when plant biomass is near maximum. This result was
conceivably due to the increased concentration of the putative allelochemical cyanamide in reproductive
tissue. Chemical inhibition of radicle elongation in this extract, however, was only observed
in the domesticated response species wheat (Triticum aestivum L.) and canola (Brassica
napus L.). The allelopathic effect on germination varied and depended on extracted species, extract
stage, and response species; whereas the effect on radicle elongation was similar among extracted
species, yet unique within response species. This research demonstrated that allelopathy
studies should include multiple allelopathic and response species to accurately quantify the magnitude
of chemical effects among allelopathic species and to rule out potential phytotoxic chemical
defense/detoxification mechanisms that exist in some response species.