Effects of herbicides application on allelopathic potential of Eupatorium catarium

This study aimed to evaluate the effects of 3-herbicides (Paraquat, Glyphosate, Fluazifop-butyl) on the aqueous extract of Eupatorium catarium on seed germination of Brassica rapa L. ssp. Chinensis L. experiments. The E. catarium aqueous extract were prepared every 10-days after the herbicides application at various rates. The B. rapa L. ssp. Chinensis L. seeds were immersed in 4- concentrations (0.5, 0.25, 0.125 and 0.0625 g/ml) of aqueous extract of E. catarium. The inhibitory effects of E. catarium aqueous extracts on germination were enhanced under herbicides stress. Compared to control, the 0.5g/mL aqueous extract treated with herbicides drastically reduced germination from 80-90% to 5-20%, while, aqueous extract <0.25 g/mL concentrations had no inhibit the germination. Furthermore, herbicides stress time influenced the allelopathic potential of E. catarium, the aqueous extracts at day 10 after application of paraquat (extract concentration: 0.25,0.5 g/mL) and fluazifop-butyl (extract concentration: 0.5 g/mL) caused maximum inhibition, while, for glyphosate (extract concentration: 0.25,0.5 g/mL), aqueous extracts at 30 days after application was most inhibitory. Thus, our results indicated that allelopathic activities of aqueous extracts from E. catarium varied with herbicides stress, which strongly inhibited the germination of B. rapa L. ssp. Chinensis..