Bioassay on the herbicidal activity of extracts from eight herbs including Hemistepta lyrata

The petroleum ether,ethyl acetate and ethanol extracts from eight herbs were extracted by sequential extraction,and the herbicidal activity of these extracts were bioassayed using the seed germination test of Sorghum vulgare Pers.,Cucumis sativus L.,Triticum aestivum L.and Brassica campestris L.The results show that these extracts can inhibit the growth of root and stem of seedlings of the four crops,but the inhibition rate is different.The inhibition of ethyl acetate extracts from Hemistepta lyrata Bunge and Humulus scandens(Lour.) Merr.is the strongest,and the inhibition rate increases gradually with concentration rising.The inhibitory effect of ethyl acetate extracts from Hemistepta lyrata andHumulusscandens is stronger to rootgrowth thanto stem.Under alowerconcentration(12.5 g·L-1),the inhibition of ethyl acetate extract from Hemistepta lyrata to growth of root and stem of T.aestivum seedling is the strongest,and the inhibitions of ethyl acetate extract from Humulus scandens to root growth of S.vulgare seedling and growth of root and stem of B.campestris seedling also reach the peak.It is indicated that the ethyl acetate extracts from Hemistepta lyrata and Humulus scandens have a potential herbicidal activity.