Abstract: The allelopathic effects of various extracts from Hylotelephium erythrostictum flowers on germination and early growth of seeds of the ‘weeds’ species Echinochloa crusgalli, Amaranthus retroflexus, and Trifolium repens, were studied by laboratory bioassay. Petroleum ether, methylene chloride, ethyl acetate, N-butanol and aqueous extracts were prepared. The dichloromethane extract had a strong inhibitory effect on weed germination and growth, and the inhibitory effect increased with increasing concentration. The inhibition effect on the three tested weed species reached 100% at an extract test concentration of 10 g·L^-1. The methylene chloride extract also displayed strong allelopathic activity. GC-MS was used to analyze the chemical constituents of these extracts, and 18 compounds were initially identified, from which 5 potential allelopathic were screened out: dibutyl phthalate, methyl hexadecanoate, benzenemethonic acid, octadecanoic acid methyl ester, and phenol. For these five compounds, samples of analytical purity were obtained and used to test for allelochemical activity. The effect of dibutyl phthalate was weak, with the allelopathic inhibitory effect on T. repens germination only 14.1%, while the other four had strong inhibitory effects, and there were significant differences in allelopathic activities. T. repens was the most sensitive among the tested species, and methyl hexadecanoate, benzenemethonic acid and phenol had an inhibitory effect of 100% in this species. This study identifies compounds with allelochemical activity that might potentially be used as bioherbicides for H. erythrostictum.

Key words: sedum spectabile flower, allelopathy, GC-MS, allelochemicals, weed