Rhizosphere phosphate-solubilizing bacterium for promoting activation of insoluble phosphorus in southern red soil and application of prebiotics of rhizosphere phosphate-solubilizing bacterium

Abstract

The invention discloses a rhizosphere phosphate-solubilizing bacterium for activating insoluble inorganic phosphorus in southern red soil and combined application of prebiotics of the rhizosphere phosphate-solubilizing bacterium. The invention provides rhizosphere phosphorus solubilizing Burkholderia capable of activating insoluble inorganic phosphorus in southern red soil, and also provides prebiotic oxalic acid capable of specifically enhancing the phosphorus solubilizing capacity of the strain. By directly applying the strain, insoluble phosphate (iron phosphate) in red soil can be activated, available phosphorus can be released, and phosphorus deficiency stress of red soil crops can be relieved; the combined application of the strain and prebiotics can further improve the rhizosphere phosphate solubilizing and crop growth promoting effects. The invention has important significance for developing a functional microbial preparation for enhancing the phosphorus activation capability of the crop rhizosphere under the low phosphorus stress and promoting the growth and development of the crop.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of agricultural biological product production, and particularly relates to a combined application of a rhizosphere phosphorus-solubilizing bacterium for promoting activation of difficult-to-dissolve phosphorus in southern acid red soil and a prebiotic. BACKGROUND

[0002] Low phosphorus availability in red soil is one of the most important factors limiting agricultural quality and yield. In southern China, organic phosphorus accounts for about 10% to 15% of total phosphorus in red soil. The content of iron and aluminum elements in red soil is relatively high, and the difficult-to-dissolve inorganic phosphorus is the main form of phosphorus in red soil, mainly including Fe-P and Al-P, and further being coated by the insoluble colloidal film of (hydro) oxidized iron, which are all difficult-to-dissolve phosphorus forms for plants. These difficult-to-dissolve inorganic phosphorus accounts for a high proportion in the phosphorus pool of acid red soil, affecting the soil phosphorus availability and the seasonal utilization rate of phosphorus fertilizer.

[0003] At present, there are many studies on how to improve the phosphorus deficiency in red soil. Most of the improvement methods focus on adding inorganic and organic modifiers to red soil to improve the phosphorus availability of red soil. Among them, the inorganic modifier includes alkaline lime, calcium-magnesium phosphate fertilizer, industrial by-products (such as bone meal, alkali residue, etc.), and wood ash. Adding lime (alkaline material such as quicklime and slaked lime) to red soil is the simplest and most direct improvement method, which can increase the availability of red soil phosphorus by increasing the pH value of red soil and reducing the fixation and adsorption of iron and aluminum on phosphorus. However, long-term application of lime can lead to soil compaction, nutrient imbalance and other adverse conditions, which can cause red soil to be acidic again and reduce the availability of phosphorus. Application of organic fertilizers such as straw and manure as organic modifiers is also an important way to improve the low phosphorus in red soil. In addition to the above-mentioned methods, biological organic fertilizer is also a research hotspot at present. Biological organic fertilizer and microbial fertilizer are important means for improving red soil and increasing the availability of phosphorus in red soil. Microbial fertilizer is a special fertilizer containing active microorganisms, which can increase the content of various mineral nutrients in the soil through the life activities of microorganisms in the fertilizer, thereby increasing soil fertility and promoting plant growth. In view of the current situation of phosphorus deficiency in red soil, phosphorus bacterial fertilizer is the main biological organic fertilizer applied in red soil. Phosphorus bacterial fertilizer is mainly based on phosphorus-solubilizing bacterial strains, which can secrete organic acids to activate the difficult-to-dissolve phosphorus in red soil, and has important significance for red soil agricultural production. SUMMARY

[0004] The present application aims to solve the problem of low biological availability of phosphorus elements in red soil in agricultural production, and to screen functional strains capable of activating difficult-to-dissolve ferric phosphate and prebiotics capable of enhancing the phosphorus-solubilizing capacity of the strains in the rhizosphere of crops in red soil.

[0005] In order to solve the above technical problems, the present application first provides a Burkholderia strain Bur_R_PS, which is obtained from the rhizosphere of rape in red soil.

[0006] A rhizosphere phosphorus-solubilizing Burkholderia sp. Bur_R_PS was preserved in China General Microbiological Culture Collection Center on July 5, 2023, and the preservation number is CGMCC No. 27804.

[0007] A microbial agent prepared from the rhizosphere phosphorus-solubilizing Burkholderia sp. Bur_R_PS.

[0008] Preferably, the microbial agent is a microbial liquid, a microbial suspension or a microbial powder prepared from the rhizosphere phosphorus-solubilizing Burkholderia sp. Bur_R_PS.

[0009] Preferably, the microbial agent is prepared by the following method:

[0010] (1) After activation, the strain Bur_R_PS is inoculated into LB liquid medium and cultured at 30℃ and 170 rpm until OD 600 = 1.0, i.e. the phosphorus-solubilizing bacteria liquid;

[0011] (2) The microbial suspension is obtained by centrifuging the microbial liquid, washing the microbial body with sterile water twice, and resuspending the microbial body with an equal volume of sterile water.

[0012] (3) The microbial powder is obtained by centrifuging the microbial liquid, washing the microbial body with sterile water twice, sealing with sterile gauze, placing in a 37℃ constant temperature incubator and drying for 3 days, and then grinding into powder in a mortar.

[0013] The strain or the microbial agent is used for directly acting on the rhizosphere of crops, improving the ability of activating insoluble ferric phosphate in the rhizosphere of crops, increasing the concentration of effective phosphorus and promoting the growth and development of crops.

[0014] Preferably, the crop is rape.

[0015] Preferably, the microbial agent is applied to the soil around the crop root system in an amount of not less than 1×10 7 cfu per strain.

[0016] Oxalic acid combined with the rhizosphere phosphorus-solubilizing Burkholderia sp. Bur_R_PS is used for directly acting on the rhizosphere of crops, improving the ability of activating insoluble ferric phosphate in the rhizosphere of crops, increasing the concentration of effective phosphorus and promoting the growth and development of crops.

[0017] Preferably, the microbial agent is applied to the soil around the crop root system in an amount of not less than 1×10 7 cfu per strain, and the oxalic acid solution is applied to the soil around the crop root system in an amount of not more than 50 μmol / kg of soil.

[0018] Preferably, the oxalic acid solution is applied on the third day after the application of the microbial agent.

[0019] Beneficial effects:

[0020] This invention provides a bacterial strain that enhances the activation of insoluble iron phosphate in the rhizosphere of rapeseed in red soil, along with its prebiotic combination. Direct application of this strain or its combination with prebiotics can significantly increase the content of available phosphorus in the rhizosphere soil of rapeseed, promoting crop growth. This invention is of great significance for alleviating the problem of low phosphorus availability in red soil areas and for promoting crop growth and increasing yield. Attached Figure Description

[0021] Figure 1 Photograph of Bur_R_PS bacterial colony

[0022] Figure 2 Bur_R_PS strain phylogenetic tree

[0023] Figure 3 Growth curve of strain Bur_R_PS

[0024] Figure 4 Phosphate solubilization ability of strain Bur_R_PS

[0025] Figure 5 Effects of strain Bur_R_PS on root architecture of rapeseed under low phosphorus stress

[0026] Figure 6 Effects of strain Bur_R_PS on rapeseed plant height under low phosphorus stress

[0027] Figure 7 Effects of strain Bur_R_PS on root length of rapeseed under low phosphorus stress

[0028] Figure 8 Effects of strain Bur_R_PS on total root length and root surface area of ​​rapeseed under low phosphorus stress

[0029] Figure 9 Effects of prebiotics on the ability of strain Bur_R_PS to activate ferric phosphate

[0030] Figure 10 Effects of Bur_R_PS strain combined with prebiotics on available phosphorus content in rhizosphere soil under pot cultivation conditions

[0031] Figure 11 Effects of Bur_R_PS strain combined with prebiotics on phosphorus content in plants under pot cultivation conditions

[0032] Figure 12 Effects of Bur_R_PS strain combined with prebiotics on rhizosphere soil available phosphorus content under field trial conditions

[0033] Figure 13 Effects of the combination of strain Bur_R_PS and prebiotics on the yield of rape under field test conditions

[0034] Biological material preservation information

[0035] Bur_R_PS, classified as Burkholderia sp., was preserved in the China General Microbiological Culture Collection Center on July 5, 2023, with the preservation number CGMCC No. 27804 and the address of the Institute of Microbiology, Chinese Academy of Sciences, No. 3, Beichen West Road, Chaoyang District, Beijing. DETAILED DESCRIPTION

[0036] Example 1: Screening and phosphorus solubilizing ability identification of Bur_R_PS strain

[0037] Strain isolation and initial screening of phosphorus solubilizing ability:

[0038] The tissue culture bottle planted with rape was inverted, and the seedlings were carefully separated from the soil body. The soil attached to the surface of the rape root system within 1-2 mm was the rhizosphere soil. The rhizosphere soil was extracted according to the following steps: the rape root system was cut with sterile scissors, and the part 2-6 cm away from the root tip was placed in 30 ml PBS-S buffer solution, and the rhizosphere soil and plant root system were separated in a shaking bed at 30°C and 200 rpm for 30 min; the rhizosphere soil suspension was filtered through a 100 μm nylon cell filter to remove large soil clumps and plant residues, and the filtrate was placed in a new 50 ml centrifuge tube; the filtrate was centrifuged at 3500 g for 15 min, and the supernatant was removed. Then, 1 ml of PBS-S was added to resuspend the precipitate, which was transferred to a new sterile 2 ml centrifuge tube and centrifuged at 10000 g for 5 min. The precipitate was the rape rhizosphere soil.

[0039] The above PBS-S buffer solution formula is: NaH2PO4·H2O 6.33 g, Na2HPO4·7H2O 16.5 g, Silwet L-77 200 μL, and distilled water to 1000 mL.

[0040] The collected rape rhizosphere samples were gradient diluted with PBS-S buffer solution, and the dilution gradient was selected as 10 -5 The 200 μL suspension was plated on LB solid medium plates.

[0041] The above LB medium formula is as follows: 5g yeast extract, 10g peptone, 3g sodium chloride, 20g agar powder, and distilled water to a final volume of 1000 mL, sterilized at 115℃ for 15 min. The solid medium is prepared by adding 1% agar to the liquid medium.

[0042] Single colonies with different morphologies and colors were picked from LB agar plates and streaked for purification. Colony morphology was observed. The purified strains were cultured in LB liquid medium at 30°C and 170 rpm for 12 h with shaking. At OD600=1.0, the culture was centrifuged at 2000 g for 5 min, and washed twice with sterile water to completely remove the LB medium. The resuspended bacterial suspension was inoculated into test tubes containing MS-Fe liquid medium at a 1% inoculum size and cultured at 30°C and 170 rpm for 7 days. The available phosphorus content of the supernatant was measured. A medium without inoculation was used as a control (also cultured at 30°C and 170 rpm for 7 days with shaking). The strain Bur_R_PS, which significantly increased the available phosphorus content in the fermentation broth, was selected for further screening.

[0043] The phosphorus-solubility of the strain was tested in MS-Fe medium. The MS-Fe medium (based on MS medium, with the soluble phosphorus component replaced by insoluble ferric phosphate, while other components remained unchanged) had the following formulation: 10g glucose, 5g FePO4, 5g MgCl2·6H2O, 0.25g MgSO4·7H2O, 0.2g KCl, 0.1g (NH4)2SO4, pH adjusted to 7.0, and distilled water brought to a final volume of 1000 mL. The solid medium was prepared by adding 1% agar to the liquid medium.

[0044] Solid plate preparation and secondary screening of strain phosphate solubility:

[0045] First, streak the Bur_R_PS strain on LB solid medium and incubate at 30°C. After the strain grows into single colonies on the plate, pick a single colony and inoculate it into 3 mL of LB liquid medium. Incubate with shaking at 170 rpm at 30°C until the bacterial culture reaches OD. 600 =1.0, then take 1.5 mL of bacterial culture and inoculate it into a 500 mL Erlenmeyer flask containing 150 mL of LB liquid medium. Incubate at 170 rpm and 30 °C with shaking until OD reaches 1.0. 600 =1.0 for later use. Centrifuge the bacterial fermentation broth, discard the supernatant, then resuspend the bacterial pellet in sterile water and wash twice to remove LB liquid medium from the bacteria. Finally, resuspend the bacteria in sterile water until the OD of the bacterial culture is reached. 600 =1.0. Add 150 μL of bacterial suspension to a 13*13 square petri dish. Use a blank control with no bacterial suspension but an equal amount of sterile water as a control. Then add 1 / 2 MS-Fe medium, mix well and let stand until the agar solidifies.

[0046] After the above-mentioned solid plate was cultured in a 30°C constant temperature incubator for 3 days, the effective phosphorus content of the solid plate was determined. In a clean bench, a sterile plate puncher was used to take samples from the four corners of the solid plate and transfer them to 2 mL centrifuge tubes, with three replicates for each treatment. After adding 1 mL of sterile water to the centrifuge tubes, vortex for 10 min until the sample was fully mixed with the sterile water, centrifuge at 6000g for 5 min, and determine the effective phosphorus content of the supernatant.

[0047] 1.5 mL of the above-mentioned supernatant was added to a 2 mL sterile centrifuge tube, centrifuged at 6000g for 5 min, 1 mL of the supernatant was transferred to a 50 mL centrifuge tube, 30 mL of deionized water was added, 5 mL of molybdenum antimony anti-color developing solution was added, and then the volume was made up to 50 mL with deionized water. After standing at room temperature for 20 min, the colorimetric determination was carried out at a wavelength of 700 nm and the value was recorded, and then the phosphorus content was calculated by the standard curve.

[0048] Strain Bur_R_PS morphology and classification identification:

[0049] The morphology of the strain Bur_R_PS after 48 h of culture in LB solid medium.

[0050] The 16S rRNA gene was selected for amplification for strain classification identification, Illumina Miseq PE 2000 platform was used, and the primers were: 27F: 5'-AGAGTTTGATCCTGGCTCAG-3', 1492R: 5'-GGTTACCTTGTTACGACTT-3'. DNA library construction, high-throughput sequencing and raw data output were completed by Nanjing Qikexing Biological Technology Co., Ltd. The DNA sequences obtained by sequencing were uploaded to NCBI (https: / / www.ncbi.nlm.nih.gov / ) for BLAST comparison, and strain identification was performed according to the comparison results. The DNA sequences of the top ten strains with high genetic similarity to the sequenced strain were downloaded for constructing a phylogenetic tree. MEGA10.0 was used for phylogenetic analysis to construct a phylogenetic tree. According to the top 10 similar strains, a phylogenetic tree was constructed. According to the results of the phylogenetic tree, the strain Bur_R_PS was most closely related to the strain Burkholderia lata 383. Combined with the morphological characteristics and molecular biology, the strain Bur_R_PS was identified as Burkholderia lata.

[0051] The growth curve of the strain was determined by using the full-automatic growth curve analyzer Bioscreem. The strain Bur_R_PS was cultured in LB liquid medium to OD600=1.0, and then was moved to a 2 mL centrifuge tube, centrifuged at 2000 g for 5 min, washed with sterile water twice, and then resuspended to OD600=1.0. 200 μL of the bacterial suspension was taken to a microplate, and 5 replicates were set for different bacteria in each medium. The microplate was placed in the full-automatic growth curve analyzer Bioscreem, and the measurement temperature was set to 30℃, the measurement wavelength was OD=600, the measurement frequency was 30 min / time, and the monitoring was performed for 2 d.

[0052] Experimental results:

[0053] As shown in Figure 1 , the Bur_R_PS colony was round, transparent and slightly yellow, about 2 mm in diameter, smooth and slightly raised in surface, and the edge was neat.

[0054] As shown in Figure 2 , the strain Bur_R_PS was most closely related to the strain B. lata 383, and was identified as B. latens.

[0055] As shown in Figure 3 , the strain Bur_R_PS first showed exponential growth in LB liquid medium and then basically remained stable, and the OD reached the maximum value after about 24 h.

[0056] As shown in Figure 4 , the results showed that a small amount of soluble phosphate was still produced on the plate after the addition of iron phosphate, and the concentration was about 0.3 mg / L; after inoculation of the Burkholderia Bur_R_PS, the water-soluble phosphorus content was significantly improved, about 4.96 times of the CK.

[0057] Example 2: Effect of Burkholderia Bur_R_PS on alleviating low phosphorus stress of rape

[0058] Zao 19 was selected as the experimental variety, and three treatments were set, namely (1) normal phosphorus level: phosphorus MS (1 / 2 conventional MS medium, in which the phosphorus element was provided in the form of KH2PO4); (2) low phosphorus stress: no phosphorus MS + iron phosphate (1 / 2 MS-Fe medium); (3) low phosphorus stress with the addition of functional strain: Bur_R_PS (1 / 2 MS-Fe medium inoculated with the strain Bur_R_PS).

[0059] Solid culture plate preparation: (1) Phosphorus MS treatment: 30 mL of sterilized 1 / 2 MS medium was added in a 13 cm*13 cm square culture dish; (2) Phosphorus-free MS + ferric phosphate treatment: 1 / 2 MS-Fe medium was added in a 13*13 square culture dish; (3) Low phosphorus stress added functional strain treatment: 150 μL of Bur_R_PS bacterial suspension with OD 600 = 1.0 was added in 1 / 2 MS-Fe medium.

[0060] Rape seed sterilization treatment: Full and basically uniform size Zhongyouza 19 rape seeds were selected, soaked in sterile water for 30 min, and the floating rape seeds were discarded, and the sterile water was poured out, 1% sodium hypochlorite solution was added for 8 min, and then washed with sterile water for 6-7 times to completely remove the sodium hypochlorite on the surface of the rape seed. Placed in a 22℃ light incubator for 4 days. Transplanting experiment was carried out in a clean bench, and the rape seedlings with uniform growth were transplanted into the plate. 3 rape seedlings were transplanted in each plate. After transplanting, the plate was placed in a light incubator for culture, and the culture conditions were 25℃, light 16h and dark 8h, humidity 50%, and growth for 14 days.

[0061] The rape seedlings cultured for 14 days were taken out from the plate, washed with tap water, and the plant height and root length were measured. The rape and rice root systems were scanned by a scanner (EPSON PERFECTION V700 PHOTO), and the total root length and total root surface area were recorded.

[0062] Experimental results:

[0063] As shown in Figure 5 , under low phosphorus stress, the addition of Burkholderia Bur_R_PS had obvious differences in rape root configuration compared with the phosphorus-free MS + ferric phosphate control.

[0064] As shown in Figure 6 , under low phosphorus stress, the addition of Burkholderia Bur_R_PS could significantly increase the plant height of rape under low phosphorus stress compared with the phosphorus-free MS + ferric phosphate control, and the average increase of rape plant height was 3.1 cm.

[0065] As shown in Figure 7 , after adding Burkholderia Bur_R_PS under low phosphorus stress, the rape root length was higher than that of the phosphorus-free MS + ferric phosphate blank control, and there was a significant increase compared with the phosphorus-free MS + ferric phosphate blank control, and the rape root length increased by 6.3 cm.

[0066] As shown in Figure 8As shown, under low phosphorus stress, the addition of Burkholderia rubra (Bur_R_PS) significantly increased the total root length and root surface area of ​​rapeseed compared to the phosphorus-free MS + iron phosphate control. The total root length increased by 33.1 cm, and the total root surface area increased by 5.1 cm. 2 .

[0067] Example 3: The promoting effect of oxalic acid on the activating ability of ferric phosphate in Bur_R_PS strain

[0068] Oxalic acid was prepared into a 50 mM aqueous solution using deionized water. The oxalic acid solution was sterilized by membrane filtration in a clean bench. 2 mL of the oxalic acid aqueous solution was drawn using a syringe and passed through a sterile aqueous filter membrane with a pore size of 0.22 μm into a sterile centrifuge tube. The oxalic acid stock solution after membrane filtration was stored at -20°C for later use.

[0069] Liquid culture was performed in test tubes, with three treatments: (1) Oxalic acid treatment: oxalic acid-added medium was prepared, consisting of 4.90 mL NBRIP medium + 100 μL of oxalic acid stock solution. No bacterial strain was inoculated; the culture was carried out directly. (2) Bur_R_PS strain treatment: 100 μL of Bur_R_PS bacterial suspension with an OD600 of 1.0 was inoculated into 4.9 mL NBRIP medium. (3) Bur_R_PS strain with added oxalic acid treatment: 100 μL of Bur_R_PS bacterial suspension with an OD600 of 1.0 was inoculated into 4.9 mL NBRIP medium with added oxalic acid. Each treatment had three biological replicates. All treatment replicates were cultured at 30°C and 170 rpm for 7 days, and the effective phosphorus concentration in the supernatant of the fermentation broth was measured. The measurement method was the same as in Example 2.

[0070] Experimental results:

[0071] like Figure 9 As shown, although high concentrations of oxalic acid have phosphorus-solubilizing ability, the phosphorus-solubilizing effect of oxalic acid at this concentration is weak, and there is no significant difference between the treatment with added oxalic acid and the control (CK). The phosphorus-solubilizing effect of the strain is significant, and the effective phosphorus content in the fermentation broth is about 3.2 times that of the control (CK). Adding oxalic acid can significantly improve the ability of the functional strain Bur_R_PS to activate iron phosphate. The effective phosphorus content in the fermentation broth after the strain is used in combination with oxalic acid is 8.2 times that of the control (CK) and 2.6 times that of the treatment with the strain alone.

[0072] Example 4: Potted plant growth promotion effect of Bur_R_PS strain combined with prebiotics

[0073] Zhongyouza 19 was selected as the experimental variety, and red soil was used as the test soil. Four treatments were set up: (1) blank control, (2) oxalic acid treatment alone, (3) Bur_R_PS strain inoculation treatment alone, and (4) Bur_R_PS strain and oxalic acid combined treatment. Each treatment was repeated three times. The pot experiment was carried out in a smart greenhouse. The greenhouse settings were: temperature 25℃, light intensity 10 h, and circulating ventilation.

[0074] To disinfect the surface of the rapeseed, first soak it in sterile water for 30 minutes, then soak it in a 2% sodium hypochlorite solution for 8 minutes. Rinse it repeatedly with sterile water until no sodium hypochlorite solution residue remains. Place the disinfected rapeseed seeds in petri dishes containing moistened filter paper and incubate them at 37°C until germination. Select seedlings with uniform germination and transplant them into seedling soil.

[0075] When the rapeseed seedlings reached the three-leaf stage, select seedlings with uniform growth and transplant them into pots containing red soil for testing. Five days after transplanting, evenly apply the inoculum suspension around the roots of the rapeseed seedlings, ensuring that the number of mycorrhizal cells at the roots of each seedling is approximately 1 × 10⁻⁶. 7 CFU. The blank control group was watered with an equal volume of sterile water. Oxalic acid was added three days after inoculation, at a dosage of 50 μmol / kg soil. The control group was watered with an equal volume of sterile water. Plant samples were collected four weeks after rapeseed growth. The roots were rinsed with tap water and the root length was measured. The root samples were blanched at 105℃ for 30 min, dried at 70℃ to constant weight, and the dry weight of the underground parts was measured.

[0076] The experimental results are as follows:

[0077] like Figure 10 As shown, the treatment with added oxalic acid slightly increased the available phosphorus content in the rhizosphere soil compared to the control (CK), by approximately 2.1 mg / kg. The strain exhibited significant phosphorus-solubilizing effects, with the available phosphorus content in the rhizosphere soil increasing by approximately 5.8 mg / kg compared to the CK. Adding oxalic acid further enhanced the phosphorus activation ability of the functional strain Bur_R_PS; the combined use of the strain and oxalic acid increased the available phosphorus content in the rhizosphere soil by 7.0 mg / kg compared to the CK. This indicates that the combined use of the strain and prebiotics can effectively increase the available phosphorus content in the rhizosphere.

[0078] like Figure 11 As shown, there was no significant difference in phosphorus content between the oxalic acid treatment and the control (CK). The phosphorus content of rapeseed plants inoculated with the strain increased by 1.1 g / kg compared to the CK. Adding oxalic acid further increased the phosphorus content, with the combined use of the strain and oxalic acid increasing the phosphorus content by 2.2 g / kg compared to the CK. This indicates that the combined use of the strain and prebiotics can effectively increase the phosphorus content of plants and alleviate phosphorus deficiency stress.

[0079] Example 5: Field effect of the combination of Bur_R_PS strain and prebiotics on the growth of oilseed rape

[0080] The medium-oil hybrid 19 was selected as the experimental variety. Three treatments were set in the field experiment, (1) blank control, (2) inoculation of Bur_R_PS strain treatment, (3) combination of Bur_R_PS strain and oxalic acid application, each treatment was set with three plot replicates, each plot was 20 m 2 , all plots were applied with 200 kg / acre of ordinary mature organic fertilizer as basal fertilizer. Oilseed rape was grown in a nursery, and when the seedlings were transplanted to the field, they were first treated with Bur_R_PS bacterial liquid for 6 h, the total bacterial number was about 1 x 10 7 cfu / plant, and then the oilseed rape seedlings were transplanted to the plots. The rhizosphere soil was collected at the mature stage of oilseed rape, and the available phosphorus content in the rhizosphere soil was determined by sodium bicarbonate extraction-ultraviolet spectrophotometer method. At the same time, the yield of oilseed rape was determined.

[0081] Experimental results:

[0082] As shown in Figure 12 , inoculation of Burkholderia Bur_R_PS can significantly increase the content of available phosphorus in the rhizosphere soil, which is increased by 4.1 mg / kg compared with the blank control; the addition of oxalic acid can further improve the ability of functional strain Bur_R_PS to activate phosphorus, and the content of available phosphorus in the rhizosphere soil after the combination of the strain and oxalic acid is increased by 11.1 mg / kg compared with CK.

[0083] As shown in Figure 13 , the soil selected in the field experiment is relatively low in phosphorus and low in fertility, which is the main limiting factor of oilseed rape yield, and the yield of oilseed rape is also low, only 124 kg / acre; the yield of oilseed rape is increased by 72 kg / acre after application of the strain; the yield of oilseed rape is increased by 111 kg / acre after the combination of the strain and oxalic acid, reaching 235 kg / acre, which has basically reached the average yield level of local oilseed rape.

[0084] Therefore, the use of phosphorus-dissolving functional strain combined with organic carrier, and the combination of prebiotics targeting to enhance the phosphorus-dissolving function of the strain can significantly improve soil fertility, alleviate phosphorus stress of crops, and increase crop yield.

Claims

1. A phosphate-solubilizing Burkholderia rhizoxinica (Bur_R_PS) characterized in that, Burkholderia sp. Burkholderia sp. was preserved in China General Microbiological Culture Collection Center on July 5, 2023, and the preservation number is CGMCC No. 27804. ​ 2. The microbial inoculum prepared from the Burkholderia sp. Bur_R_PS of claim 1.

3. The bacterial agent of claim 2, wherein The microbial inoculum is a bacterial liquid, a bacterial suspension or a bacterial powder prepared from the Burkholderia sp. Bur_R_PS.

4. The bacterial agent of claim 4, characterized in that The microbial inoculum is prepared by the following method: (1) The activated strain Bur_R_PS was inoculated into LB liquid medium and cultured at 30°C, 170 rpm until OD 600 = 1.0, i.e. the phosphorus-solubilizing bacteria bacterial liquid; (2) The bacterial suspension is prepared by centrifuging the bacterial liquid, washing the bacterial body twice with sterile water, and resuspending the bacterial body with an equal volume of sterile water; (3) The bacterial powder is prepared by centrifuging the bacterial liquid, washing the bacterial body twice with sterile water, sealing with sterile gauze, placing in a 37℃ constant temperature incubator for 3 days to completely dry the bacterial body, pouring into a mortar and grinding into powder.

5. The use of the strain of claim 1 or the microbial inoculum of any one of claims 3-4 in directly acting on the rhizosphere of crops to improve the ability to activate insoluble ferric phosphate in the rhizosphere of crops, to improve the concentration of available phosphorus and to promote the growth and development of crops.

6. Use according to claim 5, characterized in that, The crop is rape.

7. The use according to any one of claims 5 to 7, characterized in that, The bacterial agent is applied to the soil around the crop roots at a total amount of no less than 1 x 10 7 cfu / strain per strain.

8. The use of oxalic acid combined with the Burkholderia sp. Bur_R_PS of claim 1 in directly acting on the rhizosphere of crops to improve the ability to activate insoluble ferric phosphate in the rhizosphere of crops, to improve the concentration of available phosphorus and to promote the growth and development of crops.

9. The use according to claim 9, characterized in that, The bacterial agent is applied to the soil around the crop roots at a total amount of no less than 1 x 10 7 cfu / strain, and the oxalic acid solution is applied to the soil around the crop roots at an oxalic acid amount of no more than 50 μmol / kg soil diluted.

10. Use according to claim 9, characterized in that, The application time of the oxalic acid solution is the third day after the application of the microbial inoculum.

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