Preliminary Study on Allelopathy of Aqueous Extracts from Conyza canadensis on Five Kinds of Receptor Plants in the Tropical Area

Take Raphanus sativus,Vigna radata,Cucumis sativus,Stylosanthes guianensias and Acalypha hainanensis which were common plants in the tropical area as acceptor plants,allelopathic effects of the aqueous extracts from Conyza canadensis on the seed germination and seedling of the acceptor plants were determined.The test results showed that the aqueous extracts from Conyza canadensis obviously suppressed the germination of the 5 kinds of acceptor plant's seeds,for instance,the RI value of 0.20 g/mL aqueous extracts from Conyza canadensis stem leaf on the germination rate and germination index of A.hainanensis seeds were-0.822 and-0.892 respectively.The aqueous extracts from Conyza canadensis showed inhibitory effect on R.sativus,S.guianensias and A.hainanensis seedling growth.When the concentration of the aqueous extracts of root was 0.15 g/mL,the seedling's root of these 3 acceptor plant was extremely suppressed,their RI value was-0.399,-0.622 and-0.667 respectively.According to synthetic analysis,the allelopathic effects of aqueous extracts from Conyza canadensis to different acceptor plants were reamarkably different,the allelopathic effects on A.hainanensis was the strongest;while the next best was S.guianensias.The majority of the allelochemicals in aqueous extracts from Conyza canadensis could dissolve in ethyl acetate.