Allelopathic Effects and Allelochemicals analysis of the Aqueous Extracts of Alternanthera philoxeroides

Allelopathic effects of aqueous extracts of from the root,rhizome,stem and leaf of Alternanthera philoxeroides on seed germination and seedling growth of sudex(Sorghum bicolor × S.Sudanense) were invesgated using Petri dish bioassays,and the chemical components of the aqueous extracts were analyzed by GC-MS.The results showed that the sudex seed germination speed and germination rate deceased with increasing concentrations of the aqueous extracts from different parts(root,rhizome,stem and leaf) of A.philoxeroides,and the aqueous extract from the stem promoted shoot height and taproot length at lower concentration promotions and inhibited them at higher concentrations,while the aqueous extract from the other parts had no influences at lower concentration promotions and inhibited them at higher concentrations,As for the allelopathic effects,it had promotion effects to the sudex seed germinaion and seedling growth when the aqueous extract from the stem was at a concentration of less than 30 mg/mL,and the aqueous extract from the root and rhizome was at a concentration of less than 2mg/mL,otherwise the aqueous extract would have an inhibition effect.The main chemical compounds contained in the extracts included benzenecarboxylic acid,benzaldehyde,2-hydroxy-benzoic acid,1,2-benzenedicarboxylic acid,dimethyl ester,1,2-benzenedicarboxylic acid,dibutyl ester,1,2-benzenedicarboxylic acid,butyl 2-methylpropyl ester,1,2-benzenedicarboxylic acid and bis(2-methylpropyl) ester.