Effect of aqueous leaf extract of Parthenium hysterophorus L. on the germination and shoot growth of two native species

In order to evaluate the allelopathic potential of an exotic invasive weed, Parthenium hysterophorus L., the effect of different concentrations of aqueous extracts (5%, 25%, 50%, 75% and 100%) prepared from leaves of P. hysterophorus were studied on the seed germination and seedling shoot growth of two common native herbs, Plantago asiatica L. and Youngia japonica (L.) DC., through laboratory bioassays. The aqueous leaf extracts at the concentrations of 25%, 75% and 100% significantly inhibited the seed germination and seedling shoot growth of two target species. There was complete failure of seed germination of Y. japonica in 75% and 100% aqueous leaf extracts. The inhibitory effect increased with increasing extract concentration. These results suggested that allelopathy may play a role in the impact of P. hysterophorus invasion on native plant recruitment of invaded communities in southern China.