Study on the allelopathic effects of Flaveria bidentis on seed germination and seedling growth of two vegetables

In order to reveal the allelopathy of Flaveria bidentis grown in Hengshui Lake on Brassica napus and Lactuca sativa, it was studied that allelopathic effects of aqueous extracts from root and stem+leaf crumbs of F. bidentis on the seed germination and seedling growth of B. napus and L. sativa. The study indicated that the aqueous extracts of F. bidentis had significantly depressed seed germination and germination speed index of L. sativa，but did not affect that of B. napus. The aqueous extracts of F. bidentis also siginificantly inhibited the length of root and seedling of B. napus and L. sativa. In general， synthetic inhibitory effect （SE） of F. bidentis on B. napus and L. sativa increased with the enhancing of extract concentration， and the allelopathic inhibition of F. bidentis root extracts was stronger than that of its stem+leaf. The allelopathic effect of F. bidentis on L. sativa was stronger than that on B. napus. The inhibited effect on root growth was greater than that of the seedling length. Allelopathic susceptibility was significant different between seedling stage and germination stage, and the former was more susceptible than the latter.