摘要

Autotoxicity is major problem in monocropping of Andrographis paniculata (Burm. f) Nees. The replant failure of this crop is believed to be due to the accumulation of phenolics released by the plant during its growth. By HPLC analysis, cinnamic acid, ferulic acid, syringic acids and benzoic acids were found in root exudates of A. paniculata. These phenolics were also found in the continuously cropped soil extract. Cinnamic acid was not detected in control soil, hence, it may be key component in soil sickness. We investigated the autotoxic effects of these phenolics singly and in mixture. The four phenolics (syringic acid, ferulic acid, benzoic acid, cinnamic acid) exhibited stimulatory effects at lower concentrations, while higher concentrations caused growth inhibition. Autotoxicity was stronger with mixture of phenolic acids than single phenolic acids.