Allelopathic Effect of Aqueous Extracts of Alternanthera philoxeroides on Root Border Cells of Oryza sativa

Allelopathic effect of aqueous extracts from invasive plant Alternanthera philoxeroides on Oryza sativa's root border cells was studied by aeroponic culture.The results showed that water-solubility allelopathic substance of A.philoxeroides inhibites and damages root border cells of rice obviously,and the effect extent depends on the vegetative parts of A.philoxeroides from which the aqueous extracts was extracted.The aqueous extracts from leaves have the strongest allelopathic effect,with the survival rate only being 21.6% when the concentrations are at 0.1g/mL,while those from stem have the weakest allelopathic effect.It appears that dose-response relationship between the survival rate of root border cells and concentrations of aqueous extracts,increased,as the survival rate decreased.The aqueous extracts from different parts of A.philoxeroides has different activity to pectin methylesterase in the root cap,The aqueous extracts of leaves,roots and rhizome first stimulated the pectin methylesterase(PME) activity as the concentrations increases,and then inhibites,but that from stems was contrary to the effect of leaves,roots and rhizome.Synthesis effect of water-solubility allelopathic substance from differences vegetative organs of A.philoxeroides are arranged as follows: leaves root and rhizome stem.