Preliminary evaluation of the allelopathy of common garden plants

The allelopathy of aqueous extracts of 44 different garden plants and volatile oil of Mentha haplocalyx which was the strongest allelopathic plant on radish (Raphanus sativus) were studied in Petri dishes in laboratory. And the allelopathy of Magnolia denudata was validated through pot experiment. Meanwhile, the effects of several in vitro allelopathic testing methods were compared in the present study. M. haplocalyx, M. denudata and Pterocarla stenoptera had the strongest allelopathic inhibitory effects, and the synthetic effect (SE) were -0.72, -0.65 and -0.38, respectively. Pittosporum tobira, Sophora japonical and Ginkgo biloba had the strongest allelopathic promoting effects, and the SE were 0.47, 0.41 and 0.26, respectively. With the 0.5 mg·mL-1 concentration, the volatile oil of M. haplocalyx had significant inhibitory effects (P0.05) on seed germination and seedling growth and root growth (P0.01) of R. sativus. The different testing methods had significantly different effects on allelopathy which was related to the test plant. This study will provide some reference for systematic study on the allelopathy of garden plants.