目的通过对当归根际土壤提取液的生物学试验和有机化合物的分离鉴定,探讨当归连作障碍与自毒作用的关系。方法设置水(CK)、当归根际土水提液100、125、250、500 mg/mL共5个处理,用于当归自毒作用的生物学实验;气相色谱-质谱联用技术(GC-MS)鉴定当归根际土壤有机化合物。结果 125 mg/mL当归根际土壤水提液能显著抑制当归自身种子发芽率、发芽指数及胚根和胚芽的伸长,且随水提液浓度的升高,这种抑制作用增强。在当归根际土壤水提液中鉴定到17个化合物,包括有机酸、酮、醛、酯和烃类等化感物质,其中很多被报道是化感物质。结论 当归根际土壤水提液对自身种子萌发和幼苗生长具有明显的自毒作用,且自毒效应具有一定的浓度依赖性,推断自毒作用可能是造成当归连作障碍的原因之一。

Objective To explore the relationship between continuous cropping obstacle and autotoxicity of Angelica sinensis,autotoxic effect and organic compounds of rhizosphere soil water extract were determined.Methods Distilled water(CK),water extract of rhizosphere soil(100,125,250,and 500 mg/mL) were applied to testing their effect on early development of A.sinensis.Seed germination rate,germination index,elongation of radicle and embryo were recorded,and GC-MS was conducted for the compound identification in the extract.Results The water extract at concentraion as low as 125 mg/mL significantly inhibited the germination and seedling growth of A.sinensis,and this inhibitory effect generally increased with the increase of the concentration of water extracts.Seventeen compounds in rhizosphere soil water extract were identified,including organic acids,ketones,aldehydes,esters,and hydrocarbons,most of them are allelophathic substance.Conclusion Water extracts from A.sinensis rhizosphere soil have inhibitory effects on A.sinensis germination and seedling growth,and this inhibitory effect generally increased with the increases of the water extract concentration at a certain ranges.In conclusion,there is autotoxicity in continuous cropping of A.sinensis,which is one of the causes of problems associated with the continuous cropping obstacle of a single plant species.

国家自然科学基金项目(31060182);甘肃省农业生物技术研究与应用开发项目;宁夏自然科学基金项目(NZ10109);甘肃省教育厅项目(0906B-04);国家科技支撑计划项目(2007BAI37B02)