[Chemical composition analysis of Eucalyptus essential oil and allelopathic effects of α-terpineol]

We extracted Eucalyptus essential oil by steam distillation and analyzed its chemical components by GC-MS. The inhibitory effects of α-terpineol, a component in Eucalyptus essential oil, were tested in Petri dishes on the germination and growth of Amaranthus retroflexus. The allelopathic effects of α-terpineol on A. retroflexus were examined with a pot experiment by measuring germination rate and biomass. The yield of essential oil was 0.04%. Ninety-two chemical components were detected from the essential oil. In Petri dish experiment, the germination inhibitory effect under 5 μL and 7.5 μL of α-terpineol per dish reached 100%. In pot experiment, germination, aboveground fresh and dry weights of A. retroflexus were significantly affected by α-terpineol. At the concentration of 1.6 μL·cm^-3, the inhibition effect was strongest, with the allelopathic response index being -0.51 for germination, -0.62 for aboveground fresh weight, and -0.44 for aboveground dry weight, and the inhibition ratio being 51%, 62% and 44%, respectively.