Screening And Application Of Functional Microorganisms In Potato Rhizosphere

Potato（Solanum tuberosum L.）has become the fourth largest food crop in the world.The potato planting area in China has increased year by year,currently more than 6 million hectares.Long-term application of chemical fertilizers has caused serious potato disease,reduced yields,and reduced quality.Microbial fertilizers are biological products that have a specific fertilizer effect on crops;they could promote absorption of crop nutrients,regulate plant growth,and increase soil fertility.In this study,the strains of nitrogen-fixing and phosphate-solubilizing were screened from potato rhizosphere soil to develop composite microbial fertilizers,and applied in potato field trials.The main results are as follows:1.In this experiment,54 and 34 strains of nitrogen-fixing and phosphate-resolving bacteria were isolated from potato rhizosphere soil.The nitrogen activity of the isolated was determined by acetylene reduction method.The highest nitrogen activity was SN-1 and SP-2,and nitrogen activity reached 249.03nmolC₂H₄·h^-1·mL^-1and 185.11nmolC₂H₄·h^-1·mL^-1.Phosphorus method was used to measure the phosphate solubilizing activity of the isolated phosphate solubilizing bacteria.The ratio of the phosphorus solubilizing loops of SP-2 and SP-5 were the largest,being 2.62 and 2.53.2.Strains with high nitrogen fixation and phosphate solubilizing ability were tested on the plate-to-fat test of the pathogenic bacteria.The strain SP-2 had the best antagonistic effect and antibacterial band width reached 1.10mm.The fermentation broth promoted the growth of wheat,corn and rice.Results showed that the promoting effect of SN-1 and SN-2 were obvious.The SN-1 strain belongs to Bacillus mucilaginosus and the SP-2 strain belongs to Bacillus amyloliquefaciens through the comparison of 16S r DNA sequence and the results of physiological and biochemical experiments.3.The basic properties of SN-1 and SP-2 strains were determined.The yield of IAA producing was 28.14 mg·L^-1 for SN-1 and 26.41 mg·L^-1 for SP-2.The secretion of chitinase from SN-1 strain 0.072 U·mL^-1·min^-11 was higher than that of SP-2,and cellulase activity of SP-2 strain was higher 0.0560.072 U·mL^-1·min^-1.From the mechanism.4.On the basis of single-factor tests,orthogonal experiments were used to determine the optimal conditions for the combined culture of SN-1 and SP-2,glucose 10g·L^-1,peptone5g·L^-1,MgSO₄ 0.5g·L^-1,NaCl 0.5g·L^-1,temperature 28°C,120r·min^-1,initial pH 7.2,3%inoculum volume,and liquid volume 80 m L·250^-1mL,incubation time 4d,higher than before optimization 2.38%,the phosphorus-removing ability increased by 3.12%.5.Using peat soil as a carrier of bacterial fertilizer,The growth-promoting strains SN-1and SP-2 were adsorbed on the carrier to develop a composite bacterial fertilizer,and the fertilizer was applied in different proportions to the potato field test.In all treatments,70%of the fertilizer+30%functional The tuber yield of the treatment with bacterial fertilizer（T2）was the highest,and there is no significant difference between 100%fertilizer（T1）treatment.Compared with no fertilizer treatment,the yield has increased by 40.10%,and the dry matter quality of tubers has increased by 21.23%.T2 treatment can reduce the incidence of potato black shank.The result shows that the reasonable application of microbial fertilizer and chemical fertilizer can make the tuber yield of potato achieve the same effect as conventional fertilization and ensure the yield while reducing the pollution to the environment.The results showed that the reasonable application of microbial fertilizer and chemical fertilizer can make the tuber yield of potato achieve the same effect as conventional fertilization and ensure the yield while reducing the pollution to the environment.