Bioactivity Of Root Exudates And Separation And Indentification Of Allelopathic Compounds Of Rehmannia Glutinosa

In this thesis,we added four penolic acids which were investigated in cropping soil to nutrient solution to test allelopathic effect on Rehmannia glutinosa Libosch;Use the same way to evalulate allelopathy of Ferulic acid at different level ferulic acid; The nutrient solution(CK) was collected with Amberlite XAD-4 resin,Macroporous adsorption resin named HPD-600,Silicon dioxide resin which got seven components;With the allelopathic effect on seedling growth,the serious effect components were identificated and quantified by GC-MS.The main results show that:The adding ferulic acid (8.8 mg·L-1),vanillic acid (0.8 mg·L-1),Vanillin (1.2 mg·L-1),andβ-hydroxybenzoic acid (3.0 mg·L-1) obviously inhibited R. glutinosa root length,root mass,fresh plant mass,and plant height with a remarked significant difference or significant difference compared with control.The rate of ferulic acid prevented were 73.84%,57.84%,62.77% and 58.92%.Besides,the content of chlorophyll in treated leaf decreased and except forβ-hydroxybenzoic acid all other phenolic acids showed the remarked significant difference from control. The SOD and POD enzyme activity in R. glutinosa plant were enhanced at first and afterwards decreased and the content of malondialdehyde (MDA) increased,all with a remarked significant difference or significant difference.Especially the SOD and POD enzyme activity in root under ferulic acid treatment was the lowest among four phenolic acids with the root rot and dead,the difference being remarked significant.All these indicated that the four phenolic acids might be the allelomechemicals of Rehmannia glutinosa Libosch.A water cultural experiment about the effect of ferulic acid at different levels on the growth of Rehmannia glutinosa was conducted to imitate the allelomechemicals of the root exudates.the results indicated that at the level of 2 mg·L-1the ferulic acid had litter effect on the growth of Rehmannia glutinosa with the control.the level of 5 mg·L-1and 8 mg·L-1 obviously inhibited Rehmannia glutinosa frensh weight, root weight, root length and plant heigh; the changes of leaf and root SOD enzyme and POD enzyme activity were enhanced at first and decreased then ,the content of malondialdehyde (MDA) increased at the level of 5 mg·L-1 and the same trend is with 8 mg·L-1level in the leaf.At the level of 8 mg·L-1,the root's SOD enzyme and POD enzyme were low,the same was low with MDA content,the root was dead,and the difference was statistically significant compared to the control.The nutrient solution(CK) was collected with Amberlite XAD-4 resin,Macroporous adsorption resin named HPD-600,Silicon dioxide resin which got seven components:X30,H30,G201,G202,G203,G204 and G205.With the combination of bioassay,the germination and radicel of Rehmannia glutinosa Libosch seeding were inhibited stronger by X30,H30 and G203 among the seven compenents,the rates of inhibition on radicel were 71.5%,58.6% and 70%,on embryo were 49.1%,17.3% and 44%.X30,H30 and G203 were indentificated and quantified by GC-MS,the results show:H30 had 17 organic acids,6 alcohols,6 esters,1 sugar,1 phenol;X30 had 14 organic acids,4 alcohols,2 esters;G203 had 4 erganic acids,2 alcohols,4 esters,2 ketone,1 phenol.β-hydroxybenzoic acid,β-hydroxyphenylacetic acid and vanillic acid were indentificated in X30 which were reported as allochemicals in many papers.