Effects of Aqueous Extracts from Stems of Four Invasive Compositae Plants on Seed Germination of Cynodon dactylon

To investigate the allelopathic effects of different compositae invasive plants on the seed germination of Cynodon dactylon. Using assays with petri dishes and filter papers, the effects of the aqueous extracts from leaves of four invasive plants（Argeratina adenophoras, Chromolaena odoratum, C. Canadensi and Tithonia diversifolia） with different concentration（0.00 g/L（ck）, 0.25 g/L, 0.50 g/L, 1.00 g/L and 2.00 g/L） on the germination rate, germination potential and allopathic effect index of Cynodon dactylon seeds were investigated and compared. Results showed that aqueous extracts from leaves of the all four invasive plants had significant inhibitory effects on seed germination of C. dynodon; and the inhibitory effects increased with the corresponding concentrations. Moreover, at medium and high concentrations（0.50 g/L, 1.00 g/L and 2.00 g/L）, the order of their water extracts on the germination rate and allelopathic index of C. dynodon seeds was from small to big as follows: A. adenophoras, C. odoratum, C. Canadensi, T. diversifolia. And at a low concentration（0.25 g/L）, A. adenophoras had the smallest inhibitory effect on the germination rate of bermudagrass seeds, while there was no significant difference in the inhibitory effect on the germination rate of C. dynodon seeds among the other three invasive plants. The effects of the water extracts from the stems of the four invasive plants on the germination potential of C. dynodon seeds increased with the increase of the extract concentration, but they all showed different intensity of change. It was conclued that these four invasive plant stem water extracts had strong allelopathic effects on C. dynodon seed germination. It was necessary to take appropriate measures to deal with the harmful effects of allelopathy when applying C. dynodon s to resist ecological invasion or implement ecological restoration.