Identification And Prevention Of Root Diseases Of Pseudostellaria Heterophylla In Guizhou Province

Pseudostellaria heterophylla is used as a medicine with tuberous roots.It was good for health,invigorating spleen and nourishing lungs.Guizhou P.heterophylla was highly appraised in the market for its good commercial properties.Serious root diseases occur due to serious monoculture continuous cropping obstacles,affact the control effect.To confirm the pathogens of main root dieases on Guizhou P.heterophylla and disease control safety,this study collected from the samples of P.heterophylla root diseases and identified them.Screen the biocontrol agents for field control experiment,then do the further study on the relationship among pathogenic bacteria,biocontrol bacteria and the changes of host defense enzyme activities,then got the following results:1.Based on morphological characteristics and molecular biological identification,the pathogens of root rot of P.heterophylla was identified as Fusarium oxysporum and Southern blight as Sclerotium rolfsii;and pathogen of violet rot root of P.heterophylla was identified as Helicobasidium mompa.2.L34,D4 and MA strains with strong antagonistic effects against pathogenic bacteria were screened out.After morphological,physiological,biochemical and molecular identification,L34 and D4 were identified as Bacillus velezensis and MA as Trichoderma hamatum.Three strains of biocontrol bacteria have the highest inhibition rate against H.mompa in the screening test.Yield control effect results showed that MA and L34-D4 treatment had the highest control effect on violet rot root,which were 83.27% and 79.23%,respectively.3.The results of size,yield and polysaccharide content determination of tuberous root of P.heterophylla showed that,Biocontrol treatments had no significant effect on root tuber size and single weight,and root tuber yield under MA MA-D4 and L34-D4 treatment was significantly higher than CK1,increasing by 58.45%,49.32% and 33.22%,respectively.The contents of polysaccharide from root tuber of P.heterophylla treated with MA,L34-D4 and CK2 were significantly higher than those treated with CK1,which were 33.97%,33.92 % and 33.91 %,respectively.4.The results of carbon and nitrogen metabolism and defense enzyme activities in the leaves of P.heterophylla showed that the protein,proline and PPO activities in the leaves were decreased,while the soluble sugar content,nitrate reductase,SOD and POD activities were increased after treat with treatments.There was no significant difference in protein and proline content in each treatment,PPO activity was significantly increased in CK1 treatment.SOD and POD activity peaks under MA treatment were significantly higher than CK1,and the nitrate reductase,SOD and POD activity peaks under L34-D4 treatment were significantly higher than CK1.These biocontrol treatments were beneficial to increase the carbon and nitrogen metabolism and active oxygen metabolism of P.heterophylla.