Identification and bioassay of allelopathic substances from the root exudates of Malus prunifolia

The root exudates of Malus prunifolia were collected and isolated using XAD-16 resin. The methanol extracts from the root exudates were detected with gas chromatography-mass spectroscopy (GC-MS). Twenty compounds (hydrocarbons, organic acid, phenol, esters, alcohol, benzene, etc.) were detected, but phthalate derivates, butylated hydroxytoluene, sitosterol and palmitic acid occurred in higher quantity. The allelopathic effects of root exudates and four main identified compounds were determined on the radical elongation of M. prunifolia. The solutions of 4-compounds and root exudates inhibited the radical length of M. prunifolia. The degree of inhibition increased with the increasing concentration of root exudates and compounds. These results demonstrated that root exudates of M. prunifolia were autotoxic to its own seedling growth.