Quantification and Allelopathy Potential of Phenolic Acids in Aqueous Extracts of Legumes

Phenolic acid is one of the allelochemicals. Phenolic acids, namely p-hydroxybenzoic, chlorogenic,caffeic, ferulic, p-coumaric, protocatechuic,syringic,vanillic and cinnamonic acids, in aqueous extracts of over ground part of alfalfa(Medicago sativa L. cv. Alfaking), hairy vetch(Vicia rillosa Roth.), yellow sweetclover (Melilotus officinalis Desr. ), white clover(Trifolium repens L. cv. Haifa), red clover(Trifolium pretense L.), and alsike clover(Trifolium hybridum L.)had been quantified by high performance liquid chromatography. And the inhibition rate of root growth of Italian ryegrass(Lolium multiflorum Lam. cv. Tetragold)treated by the aqueous extracts and phenolic acid solutions were tested. The result showed that root growth of Italian ryegrass seedling was inhibited significantly by application of the aqueous extracts with inhibition rates of 59.6%～97.7%. Nine tested phenolic acids were all detected in the aqueous extracts of the 6 tested legumes. Althought the allelopathic effect of the phenolic acids on root growth of Italian ryegrass seedlings was significantly different, but the inhibition rate of the root growth was stronger with the phenolic acid solutions concentration increasing. Allelopathic interactions existed among phenolic acids in the aqueous extracts of legume herbages.