Autotoxicity of Phthalate Esters in Tobacco Root Exudates: Effects on Seed Germination and Seedling Growth

Autotoxicity is among the major reasons that are causing continuous cropping obstacle. It is a toxic influence of chemicals released from one plant species on the germination and growth of individuals of the same species. Here, in order to analyze the autotoxicity of tobacco root exudates, root exudates were collected from tobacco plants cultivated in both cultural solution and natural soil. Through ultra-performance liquid chromatography coupled with triple-quadrupole tandem mass spectrometry main autotoxic chemical substances in the root exudates were identified. Further, the autotoxic effects of the suspected autotoxins on seed germination (including germination rate, germination potential, germination index and vigor index) and seedling growth were also analyzed. As a result, dibutyl phthalate (or diisobutyl phthalate), dioctyl phthalate and diisooctyl phthalate were identified in tobacco root exudates. It was observed high concentration (greater than 0.5 mmol L −1 ) of each produced phthalate esters caused the significant ( P