Self-allelopathy of aquatic extracts from different parts of Ageratum conyzoides and Bidens pilosa

Filter paper method using petri dishes was applied to determine the self-allelopathy of Ageratum conyzoides L.and Bidens pilosa L.Effects of aquatic extracts from roots,stems and leaves of each plant were tested under concentrations of 0,0.10,0.25 and 0.50 g/mL on seedling root length,height and fresh weight of their own plant.The result showed both plants exhibited self-allelopathy: aqueous extracts showed obvious inhibition on seedling root length,the inhibition effects increased with increasing concentration of the aqueous extracts;showed double effects on the height of the seedling,which promoted seedling height in low concentration but inhibited in high concentration;and showed marked inhibition on fresh weight under higher concentrations.