Study On Controlling Continuous Cropping Obstacle Which Happened In Strawberry Continunous Cropping By Biological Method

This study measured the antagonistic effect and the fermentation fluid's inhibition to pathogens by agar block method and growth rate method. Discovered the inhibiting mechanism of the actinomyces to pathogen mycelium at microcosmic aspect. Further measure the Biological Control Disease and Promotion Growth, induced resistance and fruitage by pot culture, nursery garden, plot, open field and Middle Plastic-Shed experiment, make sured the optimum dosage of the biocontrol actinomycets formulation. The results are as follows:1 The used three actinomycets strains Act11,Act12 and Act1 all have strong inhibition to the five pathogenetic fungi. Antagonistic diameters is 6mm to 21mm and inhibition zones are transparent. Fermentation fluid's inhibition ratio reach to P.fragaride Hickm reach to 88.3%, 86.5% and 70.3%. The inhibition mechanisms of actinomycets to pathogens is that the biocontrol actinomycets fomulations'mycelium entwine to the pathogens'make the pathogens'mycelium become short, course, enlarging, taking the shape of moniliform, bundle braches accumulating, even dissoluting, futher lose infection ability.2 The biocontrol actinomycets formulation can transparently discrease the strawberry's disease incidence. Especially, in Middle-Plastic-Shed experiment, relative effect reaches to 73.7%, and make the small plant ratio reduce to 57.5%.3 The biocontrol actinomycets formulations have transparent Promotion Growth effect to strawberry plants. The results showed that in nursery garden condition The biocontrol actinomycets formulations can increase the weight of plant root by 127.1%,265.6% and 122.4%. The mixed formulations of Act11 and Act12 respectively make the strip and the weight of strawberry increased by 63.4 and 50.4%.4 The biocontrol actinomycets formulations can improve PPO activity of the strawberry plants.The young leaves'PPO activity of strawberry in the pot cultural increased by 17.1%,16.8% and 16.9% after treated by Act1, Acr11 and Act12.In nursery experiment, the thick root and thin roots'PPO activity respectively increased by 11.3% to 40.4% and 20.0% to 51.6%. Act12 has the strongest effect to the PPO activity of strawberry roots, which make the thick root and thin root's PPO activity increased by 40.4% and 51.6%. The mixed formulations of Act11 and Act12 recreased the strawberry leaves'PPO activity by 26.9% in the Middle-plastic-shed condition. 5 The biocontrol actinomycetes formulation can transparently affect the microbiology quatities in root zone. Act11 , Act12 can increased bacteria and actinomycetes'total quatity that growing in strawberry root surface by574.8%,289.8% and 359.9%,809.6% after dipping inoculaition. The use of the biocontrol actinomycetes had slight effect to the tatio of bacteria to actinomycetes that growing in the whole strawberry's root-zone, but transparently changed the ratio of bacteria to fungi and actinomycetes to fungi. Increased the population of bacteria and actinomycetes, futher controlled the growth of fungi, reduced the occurrence of the disease.6 By measuring the pot cultured strawberry's survival rate, biomass, PPO activity and the colonization capacity of the accessed actinomyctes, make sured the optimum dosage of the biocontrol actinomycets formulation is between 0.10% and 0.15%.7 The biocontrol actinomycets formulations can improve strawberry fruitage. Make the fruitage increased 39.8% in plot condition, fruit number of each plant increased 12.9% in open field, fruit weight of each plant increased by 21.1% in Middle-plastic-shed. Didn't affect the sugar degree of strawberry in plot and field experiments.