Allelopathy Of An Invasive Plant, Bidens Pilosa L.

Allelopathic effect is one of the mechanisms why plants can successfully invade and disperse fastly. By using biomass test,|micronucleus test technique of Vicia faba root tip cells and the paraffin section technique,the alleopathic effects of aqueous extracts from Bidens pilosa L on seed germination,seedling growth photosynthesis,membrane osmosi and chromosome behavior of receptor plants were studied. The results showed that the aqueous extracts from B. pilosa had significant inhibiting effects on seed germination,seedling growth and photosynthesis of wheat and lettuce. These effects were the aqueous leaf extractï¹¥the aqueous stem extractï¹¥the aqueous root extract. Peason correlation analysis indicated that the content of chlorophyll a and chlorophyll b were concentration dependent, decreasing with the increase of concentration. But carotenoid of receptors was not obviously affected. Chlorophyll a was the most sensitive to aqueous extracts, and then was chlorophyll b, carotenoid was the least sensitive. The content of MDA in the leaf of the two plant were first increasing and then decreasing with the increase of concentration, which showed that aqueous extracts of Bidens pilosa L affected the membrane of receptors. By the paraffin section technique, we concluded that aqueous extraxts accelerated periclinal divisions of cells and increased the layers of root tips, at the same time, inhibited cell elongation and shorted root tips ,in general , the root tips became short and rough. Aqueous extracts had inhibitory and damaged effects on mitosis and growth of root tips of Vicia Faba, and had toxic effects obviously. The effects of aqueous extracts on root tips depended on treated time and concentration. With the increase of the concentration of aqueous exacts, the number of cell in divisions decreased and the micronucleus increased. Allelopathy of Bidens pilosa L may be one mechanism why it could invade successfully and spred fastly.