A soybean rhizoctonia disease biocontrol agent with the functions of improving soybean yield and oil content, a bacterial agent, a preparation method and applications

Abstract

This invention belongs to the field of microbial control technology, specifically relating to a biocontrol bacterium for soybean root rot, a microbial agent, its preparation method, and its application, which can improve soybean yield and oil content. The biocontrol bacterium is *Alcaligenes faecalis* (Factophytes). Alcaligenes faecalis A new strain, named GY16, was deposited at the China Center for Type Culture Collection (CCTCC) on November 12, 2025, with accession number CCTCC M 20252536. This alkali-producing bacterium, GY16, exhibits a specific affinity for soybean, enabling it to colonize soybean roots and effectively control soybean root rot. GY16 also promotes soybean plant growth, increases soybean yield, and improves seed oil content. Inoculants prepared using GY16 can replace pesticides, offering a green, environmentally friendly, and pollution-free alternative that positively contributes to building a sustainable farmland ecosystem.

Description

Technical Field

[0001] This invention belongs to the field of microbial control technology, specifically relating to a biocontrol agent for soybean root rot that can improve soybean yield and oil content, as well as its preparation method and application. Background Technology

[0002] Soybeans Glycine max (L.) Merr. As one of the world's most important food and oil crops, it is not only an important source of high-quality plant protein and edible oil for humans, but also an important raw material for livestock and poultry feed and biofuel.

[0003] However, the soybean industry currently faces challenges such as long development cycles and difficulties in developing high-yield oilseed varieties, as well as shrinking arable land resources and soil degradation. Soybean root rot, a soil-borne disease that severely damages yield, is caused by a complex array of pathogens that can remain dormant in the soil for years. Coupled with the imbalance of the microbial community caused by continuous cropping, the incidence rate remains high. Among existing control methods, crop rotation can only reduce pathogen density to a limited extent, while chemical control easily leads to drug resistance, soil acidification, and food safety issues. In recent years, microbial control technologies have been increasingly adopted due to their green and environmentally friendly characteristics; however, commonly available biocontrol agents are limited by their poor colonization ability and unstable efficacy. Therefore, there is an urgent need to develop a soybean root rot biocontrol agent with specific affinity for soybeans that can stably colonize the rhizosphere to promote the implementation of green control technologies.

[0004] Furthermore, research shows that phosphorus promotes fat synthesis and potassium enhances nutrient transport efficiency, both playing a crucial role in oil accumulation. Therefore, converting insoluble phosphorus and potassium in the soil into easily absorbable forms through microbial inoculants would provide a new approach to increasing soybean oil content.

[0005] In summary, developing compound functional microbial agents that combine root rot prevention, yield enhancement, and oil content improvement is expected to become a key technology for overcoming the challenges facing the soybean industry and contributing to green and sustainable development. Summary of the Invention

[0006] To address the problems existing in the prior art, one of the objectives of this invention is to provide a fecal alkali-producing bacterium (FAG). Faecal alkalis The sample, named GY16, was deposited at the China Center for Type Culture Collection on November 12, 2025, with accession number CCTCC M 20252536.

[0007] A second objective of this invention is to provide a biocontrol agent comprising the alkali-producing bacteria GY16 as described above.

[0008] Preferably, the biocontrol agent is a liquid agent, which is fermented by *Alkali-producing bacteria* GY16.

[0009] Preferably, the number of viable bacteria in the liquid bacterial agent is 1×10⁻⁶. 8 -9×10 8 CFU·mL -1 Within the range.

[0010] A third objective of this invention is to provide a method for preparing the biocontrol agent as described above, wherein the method for preparing the biocontrol agent is as follows:

[0011] S1. Activation of bacterial strain: Inoculate GY16 strain into LB liquid medium and incubate at 28-32℃ for 14-20 h to obtain activated bacterial solution;

[0012] S2. Fermentation culture: The activated bacterial solution from step S1 is inoculated into 180 mL of LB liquid medium at a volume ratio of 1-5%, and placed on a shaker at 28-32℃ and 160-200 r·min. -1 After shaking culture for 16-20 h, the biocontrol agent was obtained.

[0013] The fourth objective of this invention is to provide a microbial compound fertilizer, comprising the alkali-producing bacteria GY16 as described above and excipients that are well compatible with the alkali-producing bacteria GY16.

[0014] Preferably, the excipients include any one or more combinations of fermentation substrate, organic and / or inorganic fertilizers permissible in soil fertility science, and slow-release adsorption carriers.

[0015] The fifth objective of this invention is to provide the application of the biocontrol agent or the microbial compound fertilizer described above in the prevention and control of soybean root rot and / or the promotion of soybean growth and / or the increase of soybean seed oil content.

[0016] The sixth objective of this invention is to provide a method for preventing and controlling soybean root rot and / or promoting soybean growth and / or increasing the oil content of soybean seeds. The method is to apply an effective amount of the biocontrol agent as described above to soybeans, or to apply the microbial compound fertilizer as described above to soybeans.

[0017] Preferably, the soybean roots are irrigated with the biocontrol agent described above, and the application rate of the biocontrol agent is 20-25 L per acre.

[0018] The beneficial effects of this application are as follows:

[0019] 1. The *Alcaligenes faecalis* GY16 provided in this application exhibits a specific affinity for soybean and can colonize soybean roots for a long period to exert a control effect. Soybean roots can produce lectins, which are proteins or glycoproteins not derived from the immune system. These lectins can specifically bind to polysaccharides on bacterial cell walls and trigger agglutination reactions. The GY16 antagonistic strain obtained from soybean rhizosphere soil in this application has an affinity for soybean lectins and can undergo agglutination reactions with them. Under the mediation of lectins, the GY16 strain can colonize soybean plant roots for a long period and stably exert a control effect against soybean root rot.

[0020] 2. The alkali-producing bacterium GY16 provided in this application also possesses the ability to dissolve insoluble phosphorus such as calcium phosphate, convert insoluble potassium into available potassium, and produce IAA. Phosphorus can participate as a constituent element in the synthesis of many important compounds in plants, such as phospholipids, ATP, and some enzymes, enhancing the plant's resistance to cold, salt, and lodging. Potassium affects plant growth, development, and yield formation; sufficient potassium can improve photosynthesis and the transport capacity of photosynthetic products, promoting the accumulation of plant dry matter. Phosphorus and potassium also play a key role in oil accumulation. Indoleacetic acid (IAA) is an important plant growth regulator that can regulate and promote plant growth and affect plant organogenesis. The GY16 strain can improve the nutritional basis of soybeans through a series of processes such as phosphorus and potassium dissolution and IAA production, significantly promoting soybean pod formation, increasing yield, and also increasing the oil content and oil extraction rate of the grains.

[0021] 3. Liquid microbial agents were prepared using strain GY16. The dosage of the agent applied to the soil was 20-25 L / mu, significantly lower than the commonly used field application rate of 50-60 L / mu for conventional microbial pesticides. This reduction in agent dosage lowers production costs and labor input for field application, enhancing the technology's economic viability and potential for wider adoption. Furthermore, precise control of the agent dosage minimizes structural disturbances to the native soil microbial community, helping to maintain the stability and biodiversity of the rhizosphere microecology and avoiding potential ecological risks from excessive introduction of exogenous microorganisms.

[0022] 4. Utilizing strain GY16 to prepare liquid microbial agents as an alternative to chemical pesticides exhibits significant environmentally friendly characteristics. This functional strain GY16 was screened from the natural environment; after completing its life cycle in the soil, it can be completely biodegraded by the indigenous microbial community without producing toxic metabolic residues, thus maintaining the stability and safety of the soil micro-ecosystem. Microbial agents can also maintain soil microbial balance, preserve soil fertility, improve the quality and safety of soybeans, and prevent pathogens from developing pesticide resistance. Detailed Implementation

[0023] The present invention will be further described below through embodiments.

[0024] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this article can be purchased from the market or prepared by existing methods.

[0025] Example 1

[0026] Strain screening

[0027] Soybean plants from fields infected with root rot were collected. The entire root system, including the soil, was dug up, and large clods of soil and other useless debris were removed to obtain the complete root system and rhizosphere soil. 5 g of rhizosphere soil from each sample was placed in an Erlenmeyer flask containing 100 mL of sterile physiological saline and placed on a shaker at 160 r·min. -1 Shake for 0.5 h to obtain the rhizosphere soil bacterial suspension. Take 1 mL of the above bacterial suspension and add it to 9 mL of sterile physiological saline containing nystatin, then serially dilute to 10⁻⁶. -7 Concentration. The colonies were diluted and spread on LB plates, and those with different growth morphologies were purified separately.

[0028] Bacteria isolated from soybean rhizosphere soil were activated, and the antagonistic ability of bacterial strains against different soybean root rot pathogens was determined using the plate confrontation culture method. The soybean root rot pathogens tested were obtained from soybean rhizosphere soil and were: Fusarium solani (…). Fusarium solani L1, Fusarium solani ( Fusarium solani L2 and Fusarium equisetifolium ( Fusarium horsetail L3.

[0029] The specific steps are as follows: A 5 mm diameter mycelial block of each root rot pathogen was inoculated in the center of a PDA plate, and bacterial strains for testing were placed at equidistant points on both sides of the inoculated block. The control group only received mycelial blocks of the pathogen. All plates were incubated at 28℃ for 5 days. The diameter of the pathogen colonies was measured, and the inhibition rate of each bacterial strain was calculated. Strains with high inhibition rates were selected and purified by repeated streaking on LB agar plates to obtain pure cultures of antagonistic strains.

[0030] The selected antagonistic strains were inoculated into LB liquid medium and cultured under constant temperature and shaking until the logarithmic growth phase. 25 μL of the bacterial suspension was dropped into the center of a clean glass slide, and an equal volume of soybean lectin solution was added. The mixture was gently mixed and allowed to stand at room temperature for 30 min. After air-drying and staining, the agglutination reaction was observed under an optical microscope. Strains exhibiting obvious agglutination were selected and identified as antagonistic strains with soybean affinity.

[0031] The above LB medium formula is: 10 g peptone, 5 g yeast extract, 10 g NaCl, 15 g agar, and distilled water to a final volume of 1000 mL.

[0032] The formula for calculating the antibacterial rate is:

[0033]

[0034] The GY16 strain used in this application is a soybean root rot biocontrol strain obtained using this screening method. Plate confrontation experiments showed that strain GY16 had inhibitory effects on all three obtained soybean root rot pathogens, as shown in Table 1.

[0035] Table 1. Inhibition rate of strain GY16 against three root rot pathogens.

[0036]

[0037] Example 2

[0038] Identification of strains

[0039] The strain GY16 was classified and identified by combining morphological observation, physiological and biochemical characteristic analysis and 16S rRNA gene sequence comparison.

[0040] According to the "Manual of Systematic Identification of Common Bacteria" and "Berge's Manual of Bacterial Identification," the morphology and some physiological and biochemical characteristics of strain GY16 were detected. Morphological observation included Gram staining, and physiological and biochemical assays included starch hydrolysis test, catalase test, VP test, MR test, gelatin liquefaction test, glucose oxidation fermentation test, and H2S production test. The results are shown in Table 2.

[0041] The 16S rRNA gene sequence of strain GY16 was submitted to the NCBI database for BLAST comparison. Combined with the results of physiological and biochemical tests, strain GY16 was determined to belong to the alkali-producing bacteria (Alcaligenes faecalis). Faecal alkalis The sequence information of the relevant genes of strain GY16 is shown in the sequence listing (SEQ ID NO:1).

[0042] Table 2. Partial physiological and biochemical characteristics of strain GY16

[0043]

[0044] Example 3

[0045] Determination of IAA production and phosphorus and potassium solubilization capabilities of strain GY16

[0046] 1. Inoculate strain GY16 at a 2% inoculum into a poorly soluble phosphorus liquid medium and incubate at 28°C and 160 r·min. -1 Under the specified conditions, the culture was shaken for 7 days. After the culture was completed, 1 mL of fermentation broth was taken and incubated at 8000 r·min. -1Centrifuge for 10 min and collect the supernatant. Accurately pipette 10 μL of the supernatant, add 1 mL of molybdenum anti-antichromic reagent, and dilute to 10 mL with distilled water. Mix well and let stand at room temperature for 15 min. Measure the absorbance at 700 nm to evaluate the phosphate-solubilizing ability of the strain.

[0047] The formula for the insoluble phosphorus liquid culture medium is as follows: 10 g glucose, 5 g Ca3(PO4)2, 0.3 g KCl, 0.5 g (NH4)2SO4, 0.3 g NaCl, 0.03 g MgSO4·7H2O, 0.03 g MnSO4·4H2O, diluted to 1000 mL with distilled water, and the pH value adjusted to 7.2.

[0048] 2. Inoculate strain GY16 at a rate of 2% into potassium-solubilizing medium and incubate at 28°C and 160 r·min. -1 Under the specified conditions, the culture was shaken for 5 days. After the culture was completed, 10 mL of the bacterial suspension was accurately pipetted, 0.4 mL of 30% hydrogen peroxide solution was added, and the mixture was digested at 121℃ for 30 min at 4000 r·min. -1 Centrifuge for 20 min, collect the supernatant, and bring the volume to 100 mL with distilled water. Measure the absorbance at 420 nm using the molybdenum-antimony colorimetric method to calculate the water-soluble potassium content and assess the strain's potassium-solubilizing ability.

[0049] The potassium-solubilizing liquid culture medium formula is as follows: Na2HPO4 2.5 g, MgSO4·7H2O 2.5 g, casein 5 g, glycerol 15 mL, distilled water to a final volume of 1000 mL, and pH adjusted to 7.2.

[0050] 3. Inoculate strain GY16 at a rate of 2% into nitrogenous liquid medium and incubate at 28°C and 160 r·min. -1 The culture was shaken and cultured for 5 days under the specified conditions. After the culture was completed, the fermentation broth was centrifuged and the supernatant was collected. An appropriate amount of the supernatant was mixed with Salkowski's colorimetric reagent at a volume ratio of 1:2 and reacted in the dark at 25°C for 30 min. An uninoculated nitrogenous liquid medium was used as a blank control, and the absorbance value was measured at a wavelength of 530 nm. The content of IAA produced by strain GY16 was calculated based on this.

[0051] Salkowski's colorimetric reagent formulation is: 1 mL 0.5 mol·L⁻¹ -1 Add FeCl3 solution to 50 mL of 35% HClO4 solution, mix well and set aside.

[0052] The nitrogenous liquid culture medium formula is as follows: 10.0 g sucrose, 2.0 g K2HPO4, 0.5 g MgSO4·7H2O, 0.1 g NaCl, 0.5 g yeast extract, 0.5 g CaCO3, and distilled water to a final volume of 400 mL, adjusting the pH to 7.0.

[0053] The measurement results are shown in Table 3.

[0054] Table 3 Growth-promoting characteristics of strain GY16

[0055]

[0056] As shown in Table 3, strain GY16 has the ability to solubilize phosphorus and potassium and produce IAA, indicating that this strain has the potential to promote plant growth and increase the oil content of grains.

[0057] Example 4

[0058] Pot experiment

[0059] 1. Preparation of microbial agents

[0060] The GY16 strain was inoculated into 5 mL LB liquid culture tubes and cultured at 28°C for 20 h. Then, it was inoculated into 180 mL LB liquid culture medium at a volume ratio of 1% and placed on a shaker at 28°C and 180 r·min. -1 After shaking culture for 16-18 h, GY16 liquid bacterial agent was obtained, OD 600 =1.0.

[0061] 2. The efficacy of GY16 in preventing soybean root rot

[0062] The experiment was divided into a control group and an experimental group. In the control group, soybeans that had undergone pre-germination treatment were soaked in LB medium for 30 min before sowing, and then covered with soil and 10 mL of LB medium was applied. When the first pair of true leaves had just unfolded, another 10 mL of LB medium was applied to the base of the seedling stem. Once the first pair of true leaves had fully unfolded, 10 mL of a mixed Fusarium inoculum solution containing Fusarium oxysporum L1, Fusarium oxysporum L2, and Fusarium equisetifolium L3 (each of the three Fusarium inoculum solutions had a concentration of 1×10⁻⁶) was applied. 8 cfu·mL -1 (Mixed in equal volumes). In the experimental group, soybeans treated with pre-germination were soaked in GY16 inoculant for 30 min before sowing. After covering with soil, 10 mL of GY16 inoculant was applied. When the first pair of true leaves had just unfolded, another 10 mL of GY16 inoculant was applied to the base of the seedling stem. After the first pair of true leaves had fully unfolded, 10 mL of a mixed inoculant solution containing three types of Fusarium was applied. After 60 days, the disease severity of the plants was recorded, and the disease index and control effect were calculated. The occurrence of soybean root rot was classified according to GB / T 17980.88-2004, "Classification and Investigation Methods for Soybean Root Rot Disease".

[0063] The grading standards for soybean root rot are as follows:

[0064] Grade 0: No disease spots on the base of the stem and main root;

[0065] Grade 1: A few lesions on the base of the stem and the main root;

[0066] Grade 3: There are many lesions at the base of the stem or on the main root, and the lesion area accounts for 1 / 4 to 1 / 2 of the total area of ​​the stem and root;

[0067] Grade 5: Numerous and large lesions on the base of the stem and the main root, with the lesion area accounting for 1 / 2 to 3 / 4 of the total area of ​​the stem base and roots;

[0068] Level 7: Patches of disease on the base of the stem and main root merge together, forming a phenomenon of wrapping around the stem, but the root system is not dead;

[0069] Level 9: Root necrosis, withered or dead above-ground parts of the plant.

[0070] The calculation formula is as follows:

[0071] Disease index = [Σ(number of diseased plants at each level × disease severity level) / (total number of plants × highest disease severity level)] × 100;

[0072] Prevention and control effect (%) = [(disease index of control group - disease index of treatment group) / disease index of control group] × 100.

[0073] Table 4. Control efficacy of GY16 inoculant against soybean root rot in pot experiments.

[0074]

[0075] As shown in Table 4, the disease index of the experimental group treated with GY16 inoculant was lower than that of the control group, and the control effect reached 76.19%. This indicates that GY16 has excellent control effect on soybean root rot.

[0076] Example 5

[0077] Pot experiment

[0078] Impact on soybean growth

[0079] The method for preparing the microbial agent used in Example 5 is the same as that in Example 4.

[0080] The experiment was divided into two groups: an experimental group treated with GY16 fungicide and a control group treated without fungicide, with six replicates in each group.

[0081] In the experimental group, soybeans treated with pre-germination were soaked in GY16 inoculant for 30 min before sowing. After covering with soil, 10 mL of GY16 inoculant was applied. When the first pair of true leaves had just unfolded, another 10 mL of GY16 inoculant was applied to the base of the seedling stem. After 60 days, the plant height, root length, fresh weight of stems and leaves, fresh weight of roots, dry weight of stems and leaves, and dry weight of roots were measured. In the control group, soybeans treated with pre-germination were soaked in LB medium for 30 min before sowing. After covering with soil, 10 mL of LB medium was applied. When the first pair of true leaves had just unfolded, another 10 mL of LB medium was applied to the base of the seedling stem. After 60 days, the plant height, root length, fresh weight of stems and leaves, fresh weight of roots, dry weight of stems and leaves, and dry weight of roots were measured. The results are shown in Table 5.

[0082] Table 5 Effects of GY16 on soybean growth

[0083]

[0084] Note: This indicates that the differences between treatments are significant ( p <0.05), This indicates that the differences between treatments are highly significant ( p <0.01).

[0085] As shown in Table 5, compared with the control group without fungal application, the fresh weight and dry weight of stems and leaves in the experimental group treated with GY16 increased by 47.63% and 47.44%, respectively. p <0.05). Root fresh weight and root dry weight increased by 106.73% and 91.84%, respectively. p <0.01). The results show that GY16 can effectively promote soybean growth and root development.

[0086] Example 6

[0087] field trials

[0088] The method for preparing the inoculant used in Example 6 is the same as in Example 4.

[0089] The experiment was divided into two groups: an experimental group treated with GY16 inoculant and a control group without inoculant treatment. In the experimental group, soybean seeds were treated with GY16 inoculant before sowing. When the first pair of true leaves of the soybean seedlings had just unfolded, 10 mL of GY16 inoculant diluted 10 times with water was applied to the base of each seedling stem. In the control group, soybean seeds were treated with LB medium before sowing. When the first pair of true leaves of the soybean seedlings had just unfolded, 10 mL of LB medium diluted 10 times with water was applied to the base of each seedling stem. After 100 days of growth, the disease severity of the plants was recorded, and the disease index and control effect were calculated. The results are shown in Table 6.

[0090] Meanwhile, the plant height, bottom pod height, number of nodes, number of effective branches, number of pods per plant, number of seeds per plant, weight of soybeans per plant, and weight of 100 seeds were measured for each soybean plant. The results are shown in Table 7. The number of 0-pod, 1-pod, 2-pod, 3-pod, and 4-pod plants, as well as their length and width, were also counted for each plant. The results are shown in Table 8.

[0091] Table 6. Control efficacy of GY16 inoculant against soybean root rot in field trials.

[0092]

[0093] As shown in Table 6, the disease index of the control group without fungicide and the experimental group with GY16 fungicide were 84.07 and 21.67, respectively, and the control effect of GY16 fungicide on soybean root rot was 74.22%.

[0094] Table 7. Effects of GY16 inoculant on soybean agronomic traits and yield in field trials.

[0095]

[0096] Note: This indicates that the differences between treatments are significant ( p <0.05), This indicates that the differences between treatments are highly significant ( p <0.01).

[0097] Table 8. Effects of GY16 inoculant on soybean pods in field trials.

[0098]

[0099] Note: This indicates that the differences between treatments are significant ( p <0.05), This indicates that the differences between treatments are highly significant ( p <0.01).

[0100] As shown in Tables 7 and 8, the height of the bottom pods in the experimental group treated with GY16 inoculant was reduced by 10.01% compared to the control group without inoculant treatment. p <0.05%, the plant height, number of pods per plant, number of seeds per plant, weight of beans per plant, and number of 3-seed pods per plant were increased by 19.50%, 38.51%, 51.20%, 48.48%, and 53.57% respectively compared with the control group without fungicide application. p <0.01). The results showed that the application of GY16 inoculant significantly promoted soybean plant growth and increased soybean yield.

[0101] Finally, soybean seeds from the control and experimental groups were collected, and the dry basis of the seed fat was measured using a near-infrared spectroscopy analyzer. The results are shown in Table 9.

[0102] Table 9 Effects of GY16 inoculant on the dry fat content of soybean seeds

[0103]

[0104] Note: This indicates that the differences between treatments are significant ( p <0.05).

[0105] As shown in Table 9, the soybean grains treated with GY16 inoculant had a 4.08% higher fat content (dry basis) compared to the control group without inoculant treatment. p <0.05). This indicates that GY16 inoculant can increase the oil content of soybeans and improve the oil yield.

[0106] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A biocontrol bacterium for soybean root rot, characterized in that, Alkaloid bacteria (for fecal alkali production) Alcaligenes faecalis The sample, named GY16, was deposited at the China Center for Type Culture Collection on November 12, 2025, with accession number CCTCC NO: M20252536.

2. A biocontrol agent, characterized in that, The biocontrol agent includes the soybean root rot biocontrol agent as described in claim 1.

3. The biocontrol agent as described in claim 2, characterized in that, The biocontrol agent is a liquid agent, which is fermented by fecal alkali-producing bacteria GY16.

4. The biocontrol agent according to claim 3, characterized in that, The liquid bacterial agent contains 1×10⁶ live bacteria. 8 -9×10 8 CFU·mL -1 .

5. A method for preparing the biocontrol agent as described in claim 2 or 3, characterized in that, The preparation method of the biocontrol agent is as follows: S1. Activation of bacterial strain: Inoculate GY16 strain into LB liquid medium and incubate at 28-32℃ for 14-20 h to obtain activated bacterial solution; S2. Fermentation culture: The activated bacterial solution from step S1 is inoculated into 180 mL of LB liquid medium at a volume ratio of 1-5%, and placed on a shaker at 28-32℃ and 160-200 r·min. -1 After shaking culture for 16-20 h, the biocontrol agent was obtained.

6. A microbial compound fertilizer, characterized in that, It includes the soybean root rot biocontrol agent as described in claim 1 and excipients that are compatible with the soybean root rot biocontrol agent.

7. The microbial compound fertilizer as described in claim 6, characterized in that, The auxiliary materials include any one or more combinations of fermentation substrates, organic and / or inorganic fertilizers permitted by soil fertility science, and slow-release adsorption carriers.

8. The application of the biocontrol agent according to any one of claims 2-4 or the microbial compound fertilizer according to any one of claims 6-7 in preventing soybean root rot and / or promoting soybean growth and / or increasing the oil content of soybean grains.

9. A method for preventing soybean root rot and / or promoting soybean growth and / or increasing soybean seed oil content, characterized in that, Apply an effective amount of the biocontrol agent as described in any one of claims 2-4 to soybeans, or apply the microbial compound fertilizer as described in claim 6 or 7 to soybeans.

10. The method as described in claim 9, characterized in that, Soybeans are irrigated with the biocontrol agent as described in claim 3 or 4, wherein the application rate of the biocontrol agent is 20-25 L per acre.

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