Abstract: The herbicidal activity and active components of Artemisia annua Linn. were determined by laboratory bioassay of herbicidal activity of ethanolic extract from Artemisia annua leaves against four weeds (Amaranthus retroflexus L., Abutilon theophrasti Medic., Setaria viirdis L. Beauv. and Echinachlao crusgali L. Beauv.) and by separation and identification of the extract using solvent separation, silica gel column chromatography and gas chromatography-mass spectrometry (GC-MS). The results showed that, at a concentration of 5.0 mg/mL, the ethanolic extract from the leaves of A. annua showed certain inhibitory effects on the germination rate, germination potential and germination index of weeds. The order inhibitory effects from high to low was redroot pigweed, velvetleaf, green bristlegrass and barnyard grass. Germination was inhibited at above 85% in redroot pigweed, velvetleaf, green bristlegrass and barnyard grass. Germination potential of redroot pigweed, velvetleaf, green bristlegrass and barnyard grass was also strongly inhibited, all at above 73.36%. A total of 17 compounds were identified from the ethanolic extract of A. annua leaves, mainly including gartemisinic acid, (Z,Z)-9,12-octadecadienoic acid, and diethyl phthalate, among the others. Therefore, there are a lot of herbicidal active substances in ethanolic extract of A. annua leaves, which can significantly delay the germination and reduce the germination rate of weeds.

Key words: Artemisia annua, herbicidal activity, separation, identification