Screening And Preliminary Application Of Phosphate-solubilizing Bacteria In High-cold-cool Environment

In this paper,Bacillus mucilaginosus Krassilnikov,Bacillus megaterium debary,Bacillus cereus,Streptomyces violovariabilis,Streptomyces cinnamofuscus,Streptomyces flavoagglomeratus were used for the primary screening of solid plate medium and the re-screening of liquid medium to screen phosphate solubilizers.The relay ability of the phosphate solubilizer was screened,and the effect of phosphate solubilizing bacteria on soil available phosphorus and inorganic phosphorus components was studied in a cool environment of simulated cold.The three strains of phosphate-solubilizing bacteria have strong phosphate-solubilizing ability and stable effect.The three strains of phosphorus-solubilizing bacteria were made into liquid inoculants,and the small rapeseed pot experiment was carried out in the cool climate in September.By measuring and analyzing the biomass indicators such as plant height,fresh weight,dry weight,root length and root weight of rapeseed and the nutrients of rapeseed rhizosphere soil,it was finally concluded that Streptomyces violaceum had the most growth-promoting effect on rapeseed.It has a strong effect on the nutrients in the rhizosphere soil.The final selected Streptomyces mutans was added to the compost of pig manure and rape straw according to a certain proportion,and the microbial organic fertilizer was developed by measuring the nutrient content of the compost product.And using distiller’s grains,corn flour and bran as carriers,Streptomyces violaceum was inserted into different C/N carriers,and by measuring the total nitrogen,total phosphorus,total potassium,organic matter,electrical conductivity and p H in the microbial organic fertilizer,The number of effective viable bacteria in the microbial inoculum.To determine the best C/N suitable for the growth of Streptomyces violaceans,and then develop microbial inoculants.Its main findings are as follows:(1)Streptomyces violaceum had the largest dephosphorization circle on calcium phosphate on solid plate medium,and its D/d was 3.10,followed by Streptomyces xanthophyllum and Bacillus jelly-like.Streptomyces violaceans dissolved calcium phosphate,phytic acid and lecithin more than other strains under liquid culture,and their values were 19mg/L,3.15mg/L and 3.52mg/L,followed by Bacillus megaterium and Jelly-like Bacillus.In a simulated cool climate experiment,the treatments inoculated with Streptomyces violaceum had the highest soil available phosphorus content and alkaline phosphatase activity at any temperature,followed by Streptomyces cinnamonis and Bacillus jelly,and violet mutans The soil available phosphorus content of Streptomyces at 15°C was 4.92 mg/kg,which was higher than that at 5°C and 25°C.There was a significant negative correlation between p H and soil available phosphorus content.The contents of Ca2-P and Ca8-P in the inorganic phosphorus fraction of Streptomyces violaceans at 15℃ were also higher than those of other treatments.(2)Compared with the control,after applying Streptomyces mutans agent,the plant height increased by 35.5%,the fresh weight increased by 191.0%,the root length increased by 26.2%,and the root weight increased by 35.5% in high-fertility cultivated soil.282.7%,the phosphorus absorption increased by 968.9%,the total phosphorus in the rhizosphere soil increased by 5.1%,and the available phosphorus increased by 2.1%;in the natural soil with low fertility,the plant height increased by 45.8%,and the fresh weight increased by 61.3%.%,root length decreased by 2.6%,root weight decreased by 4.4%,phosphorus absorption increased by 91.5%,total phosphorus in rhizosphere soil increased by 29.1%,and available phosphorus increased by 213.7%.The effect of the other two phosphate-solubilizing inoculants was not as obvious as that of Streptomyces violaceum,which indicated that Streptomyces violaceum was a phosphate-solubilizing strain suitable for the cool climate environment in Qinghai.(3)In the preparation of microbial inoculants,when the carrier of the inoculum was vinasse and bran and the C/N was 17.05,the effective viable count of Streptomyces violaceans inoculum reached the highest of 15.92 billion g-1.The inoculant was added to the compost of pig manure and rape straw.During the decomposing process of the organic fertilizer,the high temperature period above 55 °C reached 14 days,which was 4 days longer than that of CK without S.mutans.After the compost was fully decomposed,the total nitrogen content increased by 24.7%,the total phosphorus content increased significantly by 44.7%,the total potassium content increased significantly by 31.4%,the organic matter content decreased by 19.9%,the p H decreased by 8.0%,and the electrical conductivity(EC)depressed by 12.67%.The nutrient content of CK without S.mutans after decomposing was not as high as that in the treatment with S.mutans except for organic matter.In the microbial inoculum,when the C/N of the carrier is 17.05,the effective viable count of Streptomyces violaceans is the highest at 15.92 billion g-1,so adding Streptomyces violaceans inoculants can reduce the loss of nutrients in the process of organic fertilizer composting,significantly improve the nutrients of organic fertilizer.