Abstract: To investigate the autotoxicity of continuous cropping obstacle of Angelica sinensis, the allelopathic effects of the aqueous extract of A. sinensis rhizosphere soil on A. sinensis seed germination, seedling growth, and physiological indices were determined by applying allelopathic effect index (RI), integrated allelopathic effect index (M), and variance analysis. It was shown that the aqueous extracts of A. sinensis rhizosphere and nonrhizosphere soils had significant inhibitory effects on the seed germination, seedling growth, and enzyme activities of A. sinensis, compared with distilled water and unplanted soil aqueous extract. The integrated allelopathic effects of A. sinensis rhizosphere soil extract increased with its increasing mass concentration, and had significant differences (P<005) between various mass concentrations (0125〖KG-*2〗-〖KG-*7〗1000 g·ml-1). At the same mass concentrations, the effects of rhizosphere soil extract were more distinct than those of nonrhizosphere soil extract. The rhizosphere and nonrhizosphere soil extracts at the mass concentration of 0500 g·ml-1 inhibited the SOD, POD, CAT and NR activities of A. sinensis seedlings significantly, and there was a significant difference (P<005) in the inhibitory effects between the two soil extracts. The inhibitory effect of the aqueous extracts of rhizosphere-, nonrhizosphere- and unplanted soils on the seed germination, seedling growth, and enzymatic activities of A. sinensis was in the order of rhizosphere soil>nonrhizosphere soil>unplanted soil, indicating that autotoxicity could be one of the reasons of continuous cropping obstacle of A. sinensis.

Key words: Northern China semi-arid region, Rainwater harvesting for supplemental irrigation, Water-saving agriculture, Developing model