| Strawberries are favored by many Chinese consumers because of their unique taste and flavor.With the increase of strawberry cultivation area year by year,continuous cropping obstacles caused by strawberry growth deterioration,yield and quality reduction,soil borne diseases aggravated a series of problems,has seriously hindered the development of strawberry industry in China.Strawberry root rot is the general name of a kind of disease manifested as the symptom of strawberry root and stem rot,and will increase with the growth of planting years,is a soil borne disease difficult to control.In this study,pathogenic bacteria were isolated from strawberry root rot seedlings collected,and two strains of Bacillus with antagonistic effect were screened.Using two strains of Bacillus as fermentation strains,three kinds of microbial fertilizer were prepared by using the optimized formula and fermentation conditions.The developed bacterial fertilizer was applied to strawberry in the field according to the experimental treatment.The biocontrol effect of the two strains of Bacillus on strawberry root rot,the growth promotion effect on strawberry and the continuous cropping soil improvement effect were investigate through the field test of two year.The main research results are as follows:1.Fusarium solani was identified as the pathogen causing strawberry root rot,and two strains of Bacillus 913 and Rf were screened out,the inhibitory rates of which were 37.8%and 38.9% respectively.In this study,three kinds of fungi were isolated from strawberry root rot seedlings,and the pathogen of strawberry root rot was identified by morphological observation and molecular biological,identification and Koch’s law verification.The antagonistic Bacillus was screened by using the Bacillus preserved in the laboratory to confront the pathogen.2.The ability of two bacillus strains to produce extracellular enzymes and biomass was verified.Through the plate screening test of the two bacillus strains,it was verified that both bacillus had the ability to produce cellulase,protease,amylase and ammonia,among which Bacillus 913 also had the ability to produce auxin.3.The optimum fermentation formula of microbial bacterial fertilizer is that the mass ratio of potassium fulvate to peat is 1: 2,and the optimum fermentation conditions are as follows: fermentation temperature is 27℃,initial water content is 80%,inoculation amount is 15%,initial p H is 8,and fermentation days are 7d.Using the fermentation formula and fermentation conditions,the fermentation effect of microbial fertilizer is the best.4.The overall effect of T4 treatment(20g/plant compound microbial fertilizer)is stronger than that of T3 treatment(20g/plant 913 single bacterial fertilizer),T2 treatment(20g/plant Rf single bacterial fertilizer)and T1 treatment(20g/plant fermentation substrate).Compared with CK blank treatment,the average total yield per plant of strawberry treated with T4 in the first year and the second year increased by 10.35% and 13.67% respectively.After microbial fertilizer was applied,the growth,biomass and photosynthesis of strawberry plants were obviously enhanced,the single fruit weight and average total yield per plant were increased,the contents of soluble protein,vitamin C,anthocyanin and soluble total sugar in fruits were all increased,and the disease index of strawberry root rot was obviously reduced.The results of two-year field experiment showed that T4 treatment had the best application effect,and the microbial fertilizer treatment in the second year achieved better results in promoting strawberry growth and preventing strawberry root rot compared with the first year.5.The application of microbial fertilizer can improve the continuous cropping soil.After applying microbial bacterial fertilizer for two years,soil p H and soil bulk density decreased,while soil total potassium and total phosphorus contents increased.Compared with CK blank treatment,T4 treatment in 20 cm soil layer decreased soil p H by 1.07%,soil bulk density by 12.3%,soil total phosphorus content by 17.2% and soil total potassium content by 31.69%.After applying microbial fertilizer,the number of bacteria,actinomycetes and Bacillus in soil increased obviously,while the number of fungi decreased.To sum up,the two strains of Bacillus showed good bacteriostatic effect on the pathogen of strawberry root rot,and had strong growth-promoting characteristics.Microbial fertilizer made from two strains of Bacillus showed good biocontrol effect and growth promotion effect on strawberry root rot in field experiment,and improved continuous cropping soil,which has the significance of continuing research and development and popularization. |
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