Herbicidal activity of Stylosanthes guianensis and its phytotoxic components

Stylosanthes guianensis is a popular pasture legume and cover crop. The legume possessed strong allelopathic potential and suppressed spontaneous growth of paddy weeds. In a bioassay, aqueous extract of S. guianensis remarkably inhibited germination and growth of barnyardgrass and monochoria. Application of 1 ton ha(-1) upland parts of S. guianensis significantly reduced paddy weed biomass by 80% and increased rice yield by 40% when compared with the control. Gas chromatography-mass spectrometry analysis reveals the presence of several allelochemicals in S. guianensis including phenolic acids, coumarin and long-chain fatty acids. Stylosanthes guianensis may be used as a source of natural herbicide for reducing the dependency on synthetic herbicides in agricultural production.