Assessment of Allelopathic Potential of Wedelia trilobata on the Germination, Seedling Growth and Chlorophyll Content of Rape

Wedelia trilobata(L.) Hitche is a widespread alien invasive weed in south China and has been reported to show allelopathic potential causing biological suppression on some plants. In this study, the allelopathic effects of aqueous extracts from the leaves ofW. trilobatawere tested on the seed germination, shoot growth and total chlorophyll content of rape (Brassica campestrisL.) using Petri dish bioassay. The results showed that the aqueous extracts at the concentration from 25% to 100% caused a significant reduction in the germination percentage, shoot length and total chlorophyll content of rape. This inhibitory effect was concentration-dependent. These results suggested there was a strong potential phytotoxic effect ofW. trilobataon rape andthis effect might reduce the production of some crop species.