The Collaborative Prevention Role Of Rhizopus Nigricans And Trichoderma Pseudokoningii In Biocontrol Of Fusarium Wilt

Due to crop cultivation and using chemical fertilizers, the harmful microorganisms increase and the beneficial microbes decreased dramatically. The balance between them is damaged and the soil borne disease is further serious. The fusarium wilt disease is caused by Fusarium oxysporum and it is a devastating fungal soil borne disease, especially in cotton, sugar cane, banana, tomato, cucumber, wax gourd, watermelon, pumpkin, zucchini and the F. oxysporum destroys plant vascular bundle and cause the plants to die.The research object is fusarium wilt and systematic study the bio-control coordinated control effects, soil microflora and the impact of agricultural production by the method of confrontation experiment, fermentation experiment and biological statistics.This research has mainly the following research results and conclusions:1. Using confrontation experimental determents the five kinds of bio-control bacteria that are Rhizopus nigricans,Rhizopus stolonifer, Trichoderma pseudokoningii, Trichoderma pseudokoningii I, Trichoderma viride, Trichoderma viride I inhibition effect of five kinds of plant pathogenic bacteria that they are F. oxysporum f.sp.cucumerinum, F. oxysporum f.sp.discoreae, F. oxysporum f.sp.lycopersici, F. oxysporum f.sp.graminearum and Botrytis cinerea. The result shows that the inhibition rate of Rhizopus nigricans and Trichoderma pseudokoningii to F. oxysporum f.sp.cucumerinum, F.oxysporum f.sp.discoreae, F. oxysporum f.sp.lycopersici, F.oxysporum f.sp.graminearum and Botrytis cinerea is highest. The inhibition rate of Rhizopus nigricans and Trichoderma pseudokoningii is the highest, higher than 55.0%. So we chose two kinds of bio-control bacteria as the research object and research their control effects.2. Using the experimental determination of bio-control bacteria fermented liquid of hypha growth rate inhibition of pathogenic fungi. The result shows that the bio-control bacteria is carried out accordance with the 1:1 ratio of mixed fermentation, the inhibition rate of the mixed fermented liquid to pathogenic bacteria is 67.6%. In the aspect of disease-causing bacteria, Rhizopus nigricans and Trichoderma pseudokoningii have synergy.3. The potted experiments show that through method of damaging root, the pathogenic strains of F. oxysporum f.sp.cucumerinum is inoculated in cucumber root, the fusarium wilt of cucumber is 100%. The incidence of cucumber of treatment group of Trichoderma pseudokoningii and Rhizopus nigricans are 68.75%,75.0% and the relative control effect are 31.25%,25.0%. But the incidence of cucumber of treatment group of mixed fermentation liquor is 56.3%, the relative control effect is 43.7%. The result suggests that these two mixed fermentation liquor has synergistic effect.4. The GFP marked pathogenic bacteria is observed by fluorescent microscope. The results show that when the cucumber roots began browning phenomenon, the pathogenic bacteria content in the cucumber root, stem and rhizosphere soil is the highest. At the mixed fermentation treatment group, the pathogenic bacteria content is the lowest.5. The real-time qPCR experiments shows that Fusarium oxysporum colonize in rhizosphere soil, infect vascular bundle to the plant roots department organization. At this point, the plant roots show browing phenomenon and withering. In cucumber stem, the inhibition rate of the treatment group of Rhizopus nigricans fermentation, Trichoderma pseudokoningii fermentation and the mixed fermentation are 22.7%, 18.5% and 22.7%, respectively. In cucumber root, the inhibition rate of three kinds of treatment group is 24.3%,17.1% and 7.2%, the inhibition rate of three kinds of treatment group is 20.5%,10.6% and 6.9% in the cucumber rhizospheric soil. The results further indicate that the Rhizopus nigricans and Trichoderma pseudokoningii have synergistic effect.6. At the different periods, the change trend of POD, SOD and PAL are tested. The results show that the three kinds of bio-control bacteria fermented liquid could indiuce disease resistance of cucumber seedling system, the mixed fermentation medium cucumber defense enzyme reaction rates of the treatment group, the fastest to maintain the longest time.7. The experimental field is processed by the mixed fermentation liquid of Rhizopus nigricans and Trichoderma pseudokoningii. The field experimental results show that through processing experimental field for two years, the relative control effect is 76.5%, the cotton blight and plant height, leaf blade thick degree and the number of cotton flower bell have significantly increased.We select the Rhizopus nigricans and Trichoderma pseudokoningii and the its mixed fermentation liquor has control blight, soil improvement and promoting the cotton quality. The bio-control bacteria should apply in organic fertilizer.