Allelopathic potential and chemical constituents of volatile oil from Praxelis clematidea

The allelopathic potential of volatile oil from Praxelis clematidea was studied using laboratory bioassay and volatile oil analysis was performed by GC-MS. Sesquiterpenes and monoterpenes were the main groups of constituents. The effects of volatile oil were examined on seedling growth of lettuce (Lactuca sativa L) and Brassica rapa L. cv. gr. Caixin. The volatile oil inhibited all the growth parameters in both test species. With the increase in dose of volatile oil, the seedlings growth of both test species was significantly reduced. Besides, the radial growth of fungal colonies (Fusarium oxysporum, Magnaporthe grisea and Phytophthora capsici) was reduced by volatile oil concentrations from 100 mg-L-1 to 1600 mg-L-1 except in M. grisea. Besides, Praxelis volatile oil inhibited the feeding activity and pupation of Spodoptera litura third instar larvae.