Screening,identification And Application Of Biocontrol Microorganism From Oncidium Hybridum

Oncidium hybridum is one of the most important potted flowers and cut-flower in the world.Oncidium hybridum are very popular among people due to its graceful flower shape and bright color.Oncidium hybridum is mainly grown in greenhouses,and the high temperature and humidity environment in greenhouses can easily lead to the frequent occurrence of Oncidium hybridum diseases.At present,breeding of disease-resistant varieties and chemical agents are the main methods of disease prevention and control,but it is easy to induce problems such as drug resistance and environmental pollution.On the contrary,biological control,which has the characteristics of green and environmentally friendly,does not have these problems,has become a research hotspot of plant disease control.Biocontrol microorganism mainly come from endophytes of plants,and plants contain abundant natural microbial resources,which have many biological functions such as promoting plant growth,enhancing the resistance of host plants and preventing and controlling diseases,etc.Therefore,biocontrol microorganism are very potential resources for biological control.In order to screen biocontrol microorganism,a large number of pathogenic fungi were isolated and obtained in this study.A large number of endophytic bacteria were isolated from healthy plants of the Oncidium hybridum.The potential biocontrol microorganism were screened by plate confrontation test,bacteriostasis of fermentation broth,pathogenicity verification and broad-spectrum bacteriostasis.The antagonistic effect of Trichoderma was the best one among microorganisms.Therefore,large number of Trichoderma spores were produced by solid fermentation experiment for verifying the control effect of Trichoderma on anthracnose of Oncidium hybridum.The effect of Trichoderma on promoting the growth of tissue culture seedlings was further studied by establishing a seedling symbiosis system.The main research results are as following:(1)Isolation of endophytic bacteriaEndophytic fungi obtained from the healthy plants of Oncidium hybridum were Trichoderma,Penicillium,Hypoxylon,Fusarium,Talaromyces,Xylaria,Colletotrichum,Aspergillus,and the dominant species were Trichoderma and Penicillium,and the endophytic bacteria was Bacillus.Phyllosticta,Fusarium,Colletotrichum,Plectosphaerella,Penicillium,Trametes,Talaromyces,Annulohypoxylon,Neoscytalidium and Muyocopron were obtained from the infected plants,and the dominant species was Fusarium.(2)Screening of potential biocontrol bacteriaTwelve potential biocontrol strains were obtained through preliminary screening,rescreening and pathogenicity verification.Through broad spectrum of antibacterial experiments with 12 pathogenic fungi(containing Fusarium solani,Fusarium oxysporum,Colletotrichum tropicicola,Fusarium delphinoides,Paraconiothyrium thysanolaenae,Curvularia eragrostidis,Guignardia mangiferae,Muyocopron alcornii),the potential biocontrol bacteria including Penicillium,Talaromyces,Trichoderma,Fusarium and Bacillus were finally obtained.(3)The control effect of Trichoderma on anthrax and its effect on tissue culture seedlingsSolid state fermentation was used to make a large number of spores produced by Trichoderma among all treatments,T3 treatment(inoculation of Trichoderma 3 days after inoculation of Colletotrichum gloeosporioides)had the most significant control effect,reaching 88.89%.Trichoderma could increased the activities of POD,SOD,CAT,and PRO,and reduce the activities of PAL and MDA.Trichoderma could significantly increase the fresh weight rate and soluble content of seedlings,which were 108.11±2.56 and 16.14±1.48,respectively.