LAUSR

Abstract Continuous cropping obstacles are widespread problems in agriculture but the reasons for their occurrence are generally considered complicated. Autotoxic allelopathy has been thought to be a critical factor in replant problems. To investigate the autotoxic allelochemicals of Angelica sinensis (Oliv.) Diels, whose cultivation has been frequently hampered by replant failure, five compounds were isolated from the rhizosphere soil and identified as imperatorin ( 1 ), α-spinasterol ( 2 ), vanillin ( 3 ), dibutyl phthalate ( 4 ) and ferulic acid ( 5 ). Bioassays showed that compounds 1 , 3 and 5 significantly inhibited the growth of A. sinensis and L. sativa seedlings. The existence of the allelochemicals in the soil environment of A. sinensis was further confirmed and quantified by high-performance liquid chromatography (HPLC). The total concentration of these allelochemicals in the rhizosphere soil reached 17.67 μg/g. Determination of reactive oxygen species (ROS) in the root tips of the treated seedlings indicated that the generation of ROS-induced oxidative damage could be an essential factor in the autotoxicity of the allelochemicals. These findings provide new insights for understanding the mechanism of autotoxicity and replant failure in the cultivation of A. sinensis. This could be helpful for the development of a strategy to eliminate some replant problems in agriculture. 1