Study On The Allelopathic Control Potential Of Cuscuta Japonica Over Mikania Micrantha

Mikania micrantha is one of the native species to Central and South America,belonging to Asteraceae.It is one of the very harmful invasive plant, which is quick growing extremely,sprawling,has invaded to China in late 1980s.At present,to control the spread of invasive species by using the natural product of plant - allelochemical - has become new research hotspots.The extraction,separation and structure identification of allelochemical from Cuscuta japonica were studied respectively,which had inhibition effects to the seed germination of M.micrantha and had a potential to develop new-type biological pesticides(such as herbicide) and open a new route for the exploitation and utilization of C.japonicaThe Allelopathy of aqueous extracts of C.japonica to the seed germination of M.micrantha was evaluated by bioassay methods.The result showed that the aqueous extracts of C.japonica has stronger inhibition effects to the seed germination of M.micrantha and Raphanus sativus, moreover,the inhibition effects of aqueous extracts to the root length, seedling height and germination index were higher significant level(p＜0.01) when the aqueous extracts was at 10 mg·mL^-1.Allelochemical in the aqueous extracts of C.japonica was extracted by solid phase extraction(SPE) and eluted by eluent with different polarity respectively.The result of bioassay methods showed that the inhibition effects of acetoneparts to the root length,seedling height and germination index were higher significant level(p＜0.01) and was significantly increased with the increase of their mass concentrations when acetoneparts was at 10 mg·mL^-1.The comprehensive effects reached -0.45 when acetoneparts was at 50 mg·mL^-1. Acetoneparts was separated and purified repeatedly by using preparative HPLC,recrystallization and some other methods.Compounds were numbered 1-8,2-1,2-2,2-3,2-4,2-6 and 2-10,which had higher significant (P＜0.01) inhibition effects to the root length,seedling height,germination index and comprehensive effects,were selected by laboratory bioassay methods and analyzed spectra by using ¹HNMR,¹³CNMR and MS.The result of parsing spectrum showed that the compounds 2-1,2-2 and 2-3 had a lower purity and need further isolation and purification.The spectra of other compounds showed that the compounds 1-8 and 2-10 were the same compound-cinnamic acid,the compound 2-6 was 3-phenylpropanoic acid and the compound 2-4 was the mixture of these two compounds which ratio was about 20:13.It is first time that isolation and identification of these two compounds from Cuseuta spp.In a word,C.japonica has strong allelopathy and the allelochemical extracted from C.japonica has significant inhibition effects to the seed germination of M.micrantha and has a potential to develop new-type herbicides.