Isolation And Identification Ofautotoxicity Substances From Rehmannia Glutinosa Libosch

Rehmannia glutinosa Libosch is a perennial herb of Scrophulariaceae,and its root is used frequently as a crude drug in traditional Chinese medicine.Rehmannia glutinosa Libosch is widely planted in china, but Rehmannia glutinosa Libosch that can be planted again 8-10 years at the same place after being planted, has very serious continuous cropping obstacle problem that seriously restrict sustainable planting. Therefore, it is necessary to study the main reason of continuous cropping obstacle problem of Rehmannia glutinosa Libosc, to provide important for resolving cropping obstacle problem. In this thesis, the reasons that cause continuous cropping obstacle problem of Rehmannia glutinosa Libosc were studied and analyzed, by the means of field simulation, chemical and instrumental analysis, etc. Results are as follows:(1) A series of experiments were designed such as experiments of transplanting Rehmannia glutinosa seedling, irrigating water extraction of soil planting Rehmannia glutinosa last year to soil never planting Rehmannia glutinosa,imitating continuous cropping obstacles by adding Rehmannia glutinosa tissue to soil. The results showed that the continuous cropping obstacle of Rehmannia glutinosa was resulted by autotoxicity substances not by pathogenic microorganism or lack of nutrition. And the root tuber part has higher autotoxicity substances content.(2)The root of Rehmannia glutinosa Libosch were grinded and extracted by organic solvent.With the bioassay of different extraction phases, ethyl acetate phase and butanol phase inhibit Rehmannia glutinosa Libosch seeding growth.(3) Ethyl acetate phase was separated and identified by the means of silica gel chromatography, TLC and GC-MS, etc. Eighteen kinds of allelochemicals were identified by GC/MS. Among them, ferulic acid, vanillic acid, vanillin and p-hydroxybenzoic acid were also identified in our early trials. In this thesis, the four kinds of phenolic acid and their mixture were added to field. The results showed that ferulic acid was the greatest toxicity, but the phenomenon of continuous cropping obstacle can not be simulated though the treat of ferulic acid.(4) Butanol phase was separated and identified to bioassay as a guide, The results showed that succinic acid inhibit Rehmannia glutinosa Libosch seeding growth. Seedlings growth was significantly inhibited at 0.4mg/mL and the inhibition rate on root length and Shoot length were 42% and 36%.