Microbial agent for preventing and treating soil-borne diseases of food crops and preparation method of microbial agent

Abstract

The invention discloses a microbial agent for preventing and treating soil-borne diseases of food crops and a preparation method of the microbial agent, and belongs to the technical field of microorganisms. The microbial inoculum comprises three functional strains, namely pseudomonas guayensis, paenibacillus polymyxa and trichoderma koningiopsis, the three strains are mixed in equal proportion and cooperate with one another, so that the microbial inoculum has a remarkable disease-resistant effect, has an antagonistic effect on various diseases of wheat and corn, can be used for preventing and treating wheat root rot, take-all and banded sclerotial blight as well as corn stem rot and banded sclerotial blight, and has a wide application prospect. Particularly, the inhibition effect on the take-all disease of wheat is optimal. Meanwhile, the coating agent and the auxiliaries are used, so that the acting durability and stability of the microbial inoculum are improved. The microbial agent is matched with a conventional base fertilizer for use, use of chemical bactericides is reduced, growth of common pathogenic bacteria of food crops is effectively inhibited, and the yield of the food crops is increased.

Description

Technical Field

[0001] The invention belongs to the technical field of microorganisms, and in particular relates to a microbial agent for preventing and controlling soil-borne diseases of grain crops and a preparation method thereof. Background Art

[0002] Soilborne diseases refer to a type of crop disease in which pathogens use soil as the main transmission medium. In China, due to the long-term continuous cropping of crops, continuous cropping problems often occur, and soilborne diseases are serious. These soilborne diseases occur in secret, and the peak of disease often occurs when the crops are close to harvest. When obvious symptoms appear, the effective prevention and control period is usually over, which can easily cause huge economic losses. In agricultural production, soilborne diseases are often controlled mainly by chemical pesticides. Due to the lack of high-efficiency and low-toxic chemical agents, the amount of pesticides used has increased year by year, resulting in serious excessive and over-frequency use of pesticides, causing environmental pollution and food safety problems.

[0003] At present, soil-borne diseases are mainly controlled by agricultural control, chemical control and biological control. Biological control is a method of controlling diseases through interactions such as antagonism, competition, induced resistance and parasitism between microorganisms. Antagonistic bacteria change the population structure and number of soil microorganisms by secreting antimicrobial substances or population competition, reducing the occurrence of diseases. At the same time, they can also change the soil structure and physical and chemical properties to reduce the harm of diseases. Microbial agents for controlling soil-borne diseases use beneficial soil microorganisms to improve soil physical and chemical properties, promote crop growth, reduce the infection of harmful microorganisms, and thus inhibit the occurrence of crop diseases. It is the main method and important way of biological control of crop diseases.

[0004] Crop diseases caused by various plant pathogenic microorganisms will seriously affect agricultural production worldwide, and at the same time lead to a significant decline in food production and food security. Therefore, a more stable, reliable and environmentally friendly crop disease prevention and control measure is urgently needed. The use of microorganisms to prevent and control crop diseases is an innovative method that can not only directly antagonize plant pathogens, but also comprehensively improve the disease resistance of crops. Summary of the invention

[0005] The present invention provides a microbial agent for preventing and controlling soil-borne diseases of grain crops, thereby improving the disease resistance of wheat and corn to various diseases and effectively increasing yield.

[0006] In order to achieve the above technical objectives, the technical solution adopted by the present invention is:

[0007] A microbial agent for preventing and controlling soil-borne diseases of grain crops comprises the following raw materials: 22-28 parts of microbial liquid, 45-48 parts of a carrier, 0.4-0.5 parts of a coating agent, and 10-15 parts of an auxiliary agent.

[0008] Furthermore, the microbial culture liquid is Pseudomonas guguanensis, Paenibacillus polymyxa, and Trichoderma koningiopsis in a volume ratio of 1:1:1.

[0009] Furthermore, the Pseudomonas guguanyi has a preservation number of CGMCC No.1.15627, purchased from China General Microorganism Collection Center; the Bacillus polymyxa has a preservation number of CGMCC No.1.15984, purchased from China General Microorganism Collection Center; the Trichoderma pseudokoningii has a preservation number of CGMCC No.1.4914, purchased from China General Microorganism Collection Center.

[0010] Furthermore, the carrier is modified diatomaceous earth; the coating agent includes sodium alginate, hydroxyethyl cellulose, sodium carboxymethyl cellulose; and the auxiliary agent includes sodium lignosulfonate and humic acid.

[0011] Furthermore, the preparation method of the modified diatomaceous earth is: pretreating the diatomaceous earth with a 3 mol / L hydrochloric acid solution, soaking it for 0.5-1h, washing it with deionized water and drying it; the mass ratio of the hydroxyethyl cellulose, sodium carboxymethyl cellulose and sodium alginate is 1:2:2; the mass ratio of the sodium lignosulfonate and humic acid is 1:1.

[0012] Furthermore, the solid-liquid ratio of diatomaceous earth and hydrochloric acid solution is 1kg:3L.

[0013] A method for preparing a microbial agent for preventing and controlling soil-borne diseases of grain crops, characterized in that the preparation is carried out by the following steps:

[0014] S1 Preparation of Pseudomonas guguanis and Paenibacillus polymyxa: Pseudomonas guguanis and Paenibacillus polymyxa were thawed and activated in LB solid medium, and then single colonies were picked and inoculated into LB liquid medium, and cultured at 30°C and 180 r / min until OD600 = 0.6 to obtain seed liquid. The seed liquid was evenly inoculated into 200 mL LB liquid medium at 1% and cultured at 30°C and 180 r / min. The number of active colonies in the bacterial liquid was detected by the dilution plate method, and the number reached 1×10 8 cfu·mL -1 After the culture was terminated, the cells were washed three times with sterile PBS buffer solution and then resuspended to obtain two bacterial suspensions;

[0015] S2 Preparation of Trichoderma pseudocorningii fermentation broth: Activate the Trichoderma pseudocorningii test tube slant strain, pick a single colony and inoculate it into PDA medium, culture it at 25°C and 170 r / min until OD600 = 0.6 to obtain seed liquid, and evenly inoculate 1% of the seed liquid into 200 mL PDA liquid medium and culture it at 25°C and 170 r / min. Use the dilution plate method to detect the number of active colonies in the bacterial liquid, and the number of active colonies reaches 1×10 8 cfu·mL -1 Then the culture is terminated to obtain the Trichoderma koningii fermentation liquid;

[0016] S3: preparing a mixed bacterial solution: mixing the Pseudomonas guguanyi bacterial suspension and the Paenibacillus polymyxa bacterial suspension prepared in step S1 and the Trichoderma pseudokoningii fermentation liquid prepared in step S2 at a volume ratio of 1:1:1 to obtain a mixed bacterial solution;

[0017] Preparation of S4 microbial agent: After the modified diatomaceous earth and the auxiliary agent are stirred evenly, the mixed bacterial solution is added dropwise under continuous stirring, and after the addition is completed, it is allowed to stand for 2-3 hours to obtain a mixture A; the coating agent is slowly added into distilled water, and stirred at 20°C to fully dissolve it to obtain a mixed solution B; the mixed solution B is added into the mixture A while stirring, and the mixture is fully mixed. After standing for 3 hours, it is added into an oven for drying until the moisture content is ≤15%, and granulated at 50°C by a disc granulator, and particles with a particle size of 2-5mm are screened out to obtain the final product microbial agent.

[0018] Furthermore, in step S4, the mass-volume ratio of the coating agent to distilled water is 20 g:1 L.

[0019] The raw materials required for the present invention are all commercially available.

[0020] In the prevention and control of diseases of grain crops, Trichoderma pseudokoningii secretes antibacterial metabolites to inhibit the growth of pathogens, and has a significant inhibitory effect on a variety of pathogens, which is safe and long-lasting. In addition, Trichoderma pseudokoningii can induce disease resistance in plants and improve their resistance to pathogens; on the other hand, it can improve the rhizosphere microecological environment and promote the growth and development of plant roots, thereby indirectly improving the resistance of plants to diseases.

[0021] Bacillus polymyxa forms a dominant population around the roots of crops through the mechanism of using bacteria to treat bacteria, prevents pathogens from infecting, and secretes broad-spectrum antibacterial substances to inhibit pathogens.

[0022] Pseudomonas guguanyi produces antibiotics and secondary metabolites that directly inhibit the growth of pathogens, and activates the plant's immune response and induces plant systemic resistance by symbiosis with plant roots.

[0023] Beneficial Effects

[0024] The present invention selects three disease-resistant microbial agents, and the three strains have antagonistic effects on various diseases of wheat and corn, and can prevent and control wheat root rot, take-all disease, sheath blight and corn stem rot, sheath blight, and have the best inhibitory effect on wheat take-all disease. After the three strains are mixed in equal proportions, they cooperate synergistically and have a significant disease resistance effect.

[0025] The microbial agent of the present invention is coated with a protective film, which not only coats and fixes the microorganisms but also loads them in diatomaceous earth, effectively reducing the damage caused to the microorganisms by the external environment during use; in addition, the addition of auxiliary agents can provide certain energy substances for the microorganisms, enhance the activity of the microorganisms, and enhance the durability and stability of the agent.

[0026] The microbial agent of the present invention is used in combination with conventional base fertilizer, reduces the use of chemical fungicides, effectively inhibits the growth of common pathogenic bacteria of grain crops, and increases the yield of grain crops. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The graphs are the inhibition of the microbial agent of Example 3 of the present invention on the pathogens of wheat root rot, take-all disease and sheath blight, and corn sheath blight and stem rot, and a blank control graph. DETAILED DESCRIPTION

[0028] The technical solution of the present invention is further described below in conjunction with specific embodiments, but is not limited thereto.

[0029] Example 1

[0030] A microbial agent for preventing and controlling soil-borne diseases of grain crops comprises the following raw materials: 22 parts of microbial liquid, 45 parts of a carrier, 0.4 parts of a coating agent and 10 parts of an adjuvant.

[0031] The microbial bacterial liquid contains Pseudomonas guineensis, Paenibacillus polymyxa and Trichoderma pseudokoningii in a volume ratio of 1:1:1.

[0032] The carrier is modified diatomaceous earth; the coating agent comprises sodium alginate, hydroxyethyl cellulose and sodium carboxymethyl cellulose; and the auxiliary agent comprises sodium lignosulfonate and humic acid.

[0033] The preparation method of the modified diatomite is as follows: pretreating the diatomite with a 3 mol / L hydrochloric acid solution, soaking it for 0.5-1h, washing it with deionized water and drying it; the mass ratio of the hydroxyethyl cellulose, sodium carboxymethyl cellulose and sodium alginate is 1:2:2; the mass ratio of the sodium lignosulfonate and humic acid is 1:1.

[0034] The solid-to-liquid ratio of the diatomaceous earth and the hydrochloric acid solution is 1kg:3L.

[0035] A method for preparing a microbial agent for preventing and controlling soil-borne diseases of grain crops, characterized in that the preparation is carried out by the following steps:

[0036] S1 Preparation of Pseudomonas guguanis and Paenibacillus polymyxa: Pseudomonas guguanis and Paenibacillus polymyxa were thawed and activated in LB solid medium, and then single colonies were picked and inoculated into LB liquid medium, and cultured at 30°C and 180 r / min until OD600 = 0.6 to obtain seed liquid. The seed liquid was evenly inoculated into 200 mL LB liquid medium at 1% and cultured at 30°C and 180 r / min. The number of active colonies in the bacterial liquid was detected by the dilution plate method, and the number reached 1×10 8 cfu·mL -1 After the culture was terminated, the cells were washed three times with sterile PBS buffer solution and then resuspended to obtain two bacterial suspensions;

[0037] S2 Preparation of Trichoderma pseudocorningii fermentation broth: Activate the Trichoderma pseudocorningii test tube slant strain, pick a single colony and inoculate it into PDA medium, culture it at 25°C and 170 r / min until OD600 = 0.6 to obtain seed liquid, and evenly inoculate 1% of the seed liquid into 200 mL PDA liquid medium and culture it at 25°C and 170 r / min. Use the dilution plate method to detect the number of active colonies in the bacterial liquid, and the number of active colonies reaches 1×10 8 cfu·mL -1 Then the culture is terminated to obtain the Trichoderma koningii fermentation liquid;

[0038] S3: preparing a mixed bacterial solution: mixing the Pseudomonas guguanyi bacterial suspension and the Paenibacillus polymyxa bacterial suspension prepared in step S1 and the Trichoderma pseudokoningii fermentation liquid prepared in step S2 at a volume ratio of 1:1:1 to obtain a mixed bacterial solution;

[0039] Preparation of S4 microbial agent: After the modified diatomaceous earth and the auxiliary agent are stirred evenly, the mixed bacterial solution is added dropwise under continuous stirring, and after the addition is completed, it is allowed to stand for 2-3 hours to obtain a mixture A; the coating agent is slowly added into distilled water, and stirred at 20°C to fully dissolve it to obtain a mixed solution B; the mixed solution B is added into the mixture A while stirring, and the mixture is fully mixed. After standing for 3 hours, it is added into an oven for drying until the moisture content is ≤15%, and granulated at 50°C by a disc granulator, and particles with a particle size of 2-5mm are screened out to obtain the final product microbial agent.

[0040] The mass-volume ratio of the coating agent to distilled water in step S4 is 20 g:1 L.

[0041] Example 2

[0042] A microbial agent for preventing and controlling soil-borne diseases of grain crops comprises the following raw materials: 24 parts of microbial liquid, 46 parts of a carrier, 0.4 parts of a coating agent and 12 parts of an auxiliary agent.

[0043] The microbial bacterial liquid contains Pseudomonas guineensis, Paenibacillus polymyxa and Trichoderma pseudokoningii in a volume ratio of 1:1:1.

[0044] The carrier is modified diatomaceous earth; the coating agent comprises sodium alginate, hydroxyethyl cellulose and sodium carboxymethyl cellulose; and the auxiliary agent comprises sodium lignosulfonate and humic acid.

[0045] The preparation method of the modified diatomite is as follows: pretreating the diatomite with a 3 mol / L hydrochloric acid solution, soaking it for 0.5-1h, washing it with deionized water and drying it; the mass ratio of the hydroxyethyl cellulose, sodium carboxymethyl cellulose and sodium alginate is 1:2:2; the mass ratio of the sodium lignosulfonate and humic acid is 1:1.

[0046] The solid-to-liquid ratio of the diatomaceous earth and the hydrochloric acid solution is 1kg:3L.

[0047] A method for preparing a microbial agent for preventing and controlling soil-borne diseases of grain crops, characterized in that the preparation is carried out by the following steps:

[0048] S1 Preparation of Pseudomonas guguanis and Paenibacillus polymyxa: Pseudomonas guguanis and Paenibacillus polymyxa were thawed and activated in LB solid medium, and then single colonies were picked and inoculated into LB liquid medium, and cultured at 30°C and 180 r / min until OD600 = 0.6 to obtain seed liquid. The seed liquid was evenly inoculated into 200 mL LB liquid medium at 1% and cultured at 30°C and 180 r / min. The number of active colonies in the bacterial liquid was detected by the dilution plate method, and the number reached 1×10 8 cfu·mL -1 After the culture was terminated, the cells were washed three times with sterile PBS buffer solution and then resuspended to obtain two bacterial suspensions;

[0049] S2 Preparation of Trichoderma pseudocorningii fermentation broth: Activate the Trichoderma pseudocorningii test tube slant strain, pick a single colony and inoculate it into PDA medium, culture it at 25°C and 170 r / min until OD600 = 0.6 to obtain seed liquid, and evenly inoculate 1% of the seed liquid into 200 mL PDA liquid medium and culture it at 25°C and 170 r / min. Use the dilution plate method to detect the number of active colonies in the bacterial liquid, and the number of active colonies reaches 1×10 8 cfu·mL -1 Then the culture is terminated to obtain the Trichoderma koningii fermentation liquid;

[0050] S3: preparing a mixed bacterial solution: mixing the Pseudomonas guguanyi bacterial suspension and the Paenibacillus polymyxa bacterial suspension prepared in step S1 and the Trichoderma pseudokoningii fermentation liquid prepared in step S2 at a volume ratio of 1:1:1 to obtain a mixed bacterial solution;

[0051] Preparation of S4 microbial agent: After the modified diatomaceous earth and the auxiliary agent are stirred evenly, the mixed bacterial solution is added dropwise under continuous stirring, and after the addition is completed, it is allowed to stand for 2-3 hours to obtain a mixture A; the coating agent is slowly added into distilled water, and stirred at 20°C to fully dissolve it to obtain a mixed solution B; the mixed solution B is added into the mixture A while stirring, and the mixture is fully mixed. After standing for 3 hours, it is added into an oven for drying until the moisture content is ≤15%, and granulated at 50°C by a disc granulator, and particles with a particle size of 2-5mm are screened out to obtain the final product microbial agent.

[0052] The mass-volume ratio of the coating agent to distilled water in step S4 is 20 g:1 L.

[0053] Example 3

[0054] A microbial agent for preventing and controlling soil-borne diseases of grain crops comprises the following raw materials: 28 parts of microbial liquid, 48 parts of a carrier, 0.5 parts of a coating agent and 15 parts of an adjuvant.

[0055] The microbial bacterial liquid contains Pseudomonas guineensis, Paenibacillus polymyxa and Trichoderma pseudokoningii in a volume ratio of 1:1:1.

[0056] The carrier is modified diatomaceous earth; the coating agent comprises sodium alginate, hydroxyethyl cellulose and sodium carboxymethyl cellulose; and the auxiliary agent comprises sodium lignosulfonate and humic acid.

[0057] The preparation method of the modified diatomite is as follows: pretreating the diatomite with a 3 mol / L hydrochloric acid solution, soaking it for 0.5-1h, washing it with deionized water and drying it; the mass ratio of the hydroxyethyl cellulose, sodium carboxymethyl cellulose and sodium alginate is 1:2:2; the mass ratio of the sodium lignosulfonate and humic acid is 1:1.

[0058] The solid-to-liquid ratio of the diatomaceous earth and the hydrochloric acid solution is 1kg:3L.

[0059] A method for preparing a microbial agent for preventing and controlling soil-borne diseases of grain crops, characterized in that the preparation is carried out by the following steps:

[0060] S1 Preparation of Pseudomonas guguanis and Paenibacillus polymyxa: Pseudomonas guguanis and Paenibacillus polymyxa were thawed and activated in LB solid medium, and then single colonies were picked and inoculated into LB liquid medium, and cultured at 30°C and 180 r / min until OD600 = 0.6 to obtain seed liquid. The seed liquid was evenly inoculated into 200 mL LB liquid medium at 1% and cultured at 30°C and 180 r / min. The number of active colonies in the bacterial liquid was detected by the dilution plate method, and the number reached 1×10 8 cfu·mL -1After the culture was terminated, the cells were washed three times with sterile PBS buffer solution and then resuspended to obtain two bacterial suspensions;

[0061] S2 Preparation of Trichoderma pseudocorningii fermentation broth: Activate the Trichoderma pseudocorningii test tube slant strain, pick a single colony and inoculate it into PDA medium, culture it at 25°C and 170 r / min until OD600 = 0.6 to obtain seed liquid, and evenly inoculate 1% of the seed liquid into 200 mL PDA liquid medium and culture it at 25°C and 170 r / min. Use the dilution plate method to detect the number of active colonies in the bacterial liquid, and the number of active colonies reaches 1×10 8 cfu·mL -1 Then the culture is terminated to obtain the Trichoderma koningii fermentation liquid;

[0062] S3: preparing a mixed bacterial solution: mixing the Pseudomonas guguanyi bacterial suspension and the Paenibacillus polymyxa bacterial suspension prepared in step S1 and the Trichoderma pseudokoningii fermentation liquid prepared in step S2 at a volume ratio of 1:1:1 to obtain a mixed bacterial solution;

[0063] Preparation of S4 microbial agent: After the modified diatomaceous earth and the auxiliary agent are stirred evenly, the mixed bacterial solution is added dropwise under continuous stirring, and after the addition is completed, it is allowed to stand for 2-3 hours to obtain a mixture A; the coating agent is slowly added into distilled water, and stirred at 20°C to fully dissolve it to obtain a mixed solution B; the mixed solution B is added into the mixture A while stirring, and the mixture is fully mixed. After standing for 3 hours, it is added into an oven for drying until the moisture content is ≤15%, and granulated at 50°C by a disc granulator, and particles with a particle size of 2-5mm are screened out to obtain the final product microbial agent.

[0064] The mass-volume ratio of the coating agent to distilled water in step S4 is 20 g:1 L.

[0065] Comparative Example 1

[0066] A microbial agent for preventing and controlling soil-borne diseases of grain crops comprises the following raw materials: 28 parts of microbial liquid, 48 parts of a carrier, 0.5 parts of a coating agent and 15 parts of an adjuvant.

[0067] The microbial bacterial liquid contains Pseudomonas guineensis, Paenibacillus polymyxa and Trichoderma pseudokoningii in a volume ratio of 2:1:1.

[0068] The carrier is modified diatomaceous earth; the coating agent comprises sodium alginate, hydroxyethyl cellulose and sodium carboxymethyl cellulose; and the auxiliary agent comprises sodium lignosulfonate and humic acid.

[0069] The preparation method of the modified diatomite is as follows: pretreating the diatomite with a 3 mol / L hydrochloric acid solution, soaking it for 0.5-1h, washing it with deionized water and drying it; the mass ratio of the hydroxyethyl cellulose, sodium carboxymethyl cellulose and sodium alginate is 1:2:2; the mass ratio of the sodium lignosulfonate and humic acid is 1:1.

[0070] The solid-to-liquid ratio of the diatomaceous earth and the hydrochloric acid solution is 1kg:3L.

[0071] A method for preparing a microbial agent for preventing and controlling soil-borne diseases of grain crops, characterized in that the preparation is carried out by the following steps:

[0072] S1 Preparation of Pseudomonas guguanis and Paenibacillus polymyxa: Pseudomonas guguanis and Paenibacillus polymyxa were thawed and activated in LB solid medium, and then single colonies were picked and inoculated into LB liquid medium, and cultured at 30°C and 180 r / min until OD600 = 0.6 to obtain seed liquid. The seed liquid was evenly inoculated into 200 mL LB liquid medium at 1% and cultured at 30°C and 180 r / min. The number of active colonies in the bacterial liquid was detected by the dilution plate method, and the number reached 1×10 8 cfu·mL -1 After the culture was terminated, the cells were washed three times with sterile PBS buffer solution and then resuspended to obtain two bacterial suspensions;

[0073] S2 Preparation of Trichoderma pseudocorningii fermentation broth: Activate the Trichoderma pseudocorningii test tube slant strain, pick a single colony and inoculate it into PDA medium, culture it at 25°C and 170 r / min until OD600 = 0.6 to obtain seed liquid, and evenly inoculate 1% of the seed liquid into 200 mL PDA liquid medium and culture it at 25°C and 170 r / min. Use the dilution plate method to detect the number of active colonies in the bacterial liquid, and the number of active colonies reaches 1×10 8 cfu·mL -1 Then the culture is terminated to obtain the Trichoderma koningii fermentation liquid;

[0074] S3: preparing a mixed bacterial solution: mixing the Pseudomonas guguanii suspension and the Paenibacillus polymyxa suspension prepared in step S1 and the Trichoderma pseudokoningii fermentation solution prepared in step S2 at a volume ratio of 2:1:1 to obtain a mixed bacterial solution;

[0075] Preparation of S4 microbial agent: After the modified diatomaceous earth and the auxiliary agent are stirred evenly, the mixed bacterial solution is added dropwise under continuous stirring, and after the addition is completed, it is allowed to stand for 2-3 hours to obtain a mixture A; the coating agent is slowly added into distilled water, and stirred at 20°C to fully dissolve it to obtain a mixed solution B; the mixed solution B is added into the mixture A while stirring, and the mixture is fully mixed. After standing for 3 hours, it is added into an oven for drying until the moisture content is ≤15%, and granulated at 50°C by a disc granulator, and particles with a particle size of 2-5mm are screened out to obtain the final product microbial agent.

[0076] The mass-volume ratio of the coating agent to distilled water in step S4 is 20 g:1 L.

[0077] Compared with Example 3, this comparative example is the same as Example 3 except that the ratio of the three liquids in the microbial inoculant is changed. The other raw materials and steps are the same as those in Example 3.

[0078] Comparative Example 2

[0079] A microbial agent for preventing and controlling soil-borne diseases of grain crops comprises the following raw materials: 28 parts of microbial liquid, 48 parts of a carrier, 0.5 parts of a coating agent and 15 parts of an adjuvant.

[0080] The microbial bacterial liquid contains Pseudomonas guineensis, Paenibacillus polymyxa and Trichoderma pseudokoningii in a volume ratio of 1:2:1.

[0081] The carrier is modified diatomaceous earth; the coating agent comprises sodium alginate, hydroxyethyl cellulose and sodium carboxymethyl cellulose; and the auxiliary agent comprises sodium lignosulfonate and humic acid.

[0082] The preparation method of the modified diatomite is as follows: pretreating the diatomite with a 3 mol / L hydrochloric acid solution, soaking it for 0.5-1h, washing it with deionized water and drying it; the mass ratio of the hydroxyethyl cellulose, sodium carboxymethyl cellulose and sodium alginate is 1:2:2; the mass ratio of the sodium lignosulfonate and humic acid is 1:1.

[0083] The solid-to-liquid ratio of the diatomaceous earth and the hydrochloric acid solution is 1kg:3L.

[0084] A method for preparing a microbial agent for preventing and controlling soil-borne diseases of grain crops, characterized in that the preparation is carried out by the following steps:

[0085] S1 Preparation of Pseudomonas guguanis and Paenibacillus polymyxa: Pseudomonas guguanis and Paenibacillus polymyxa were thawed and activated in LB solid medium, and then single colonies were picked and inoculated into LB liquid medium, and cultured at 30°C and 180 r / min until OD600 = 0.6 to obtain seed liquid. The seed liquid was evenly inoculated into 200 mL LB liquid medium at 1% and cultured at 30°C and 180 r / min. The number of active colonies in the bacterial liquid was detected by the dilution plate method, and the number reached 1×10 8 cfu·mL -1 After the culture was terminated, the cells were washed three times with sterile PBS buffer solution and then resuspended to obtain two bacterial suspensions;

[0086] S2 Preparation of Trichoderma pseudocorningii fermentation broth: Activate the Trichoderma pseudocorningii test tube slant strain, pick a single colony and inoculate it into PDA medium, culture it at 25°C and 170 r / min until OD600 = 0.6 to obtain seed liquid, and evenly inoculate 1% of the seed liquid into 200 mL PDA liquid medium and culture it at 25°C and 170 r / min. Use the dilution plate method to detect the number of active colonies in the bacterial liquid, and the number of active colonies reaches 1×10 8 cfu·mL -1 Then the culture is terminated to obtain the Trichoderma koningii fermentation liquid;

[0087] S3: preparing a mixed bacterial solution: mixing the Pseudomonas guguanii suspension and the Paenibacillus polymyxa suspension prepared in step S1 and the Trichoderma pseudokoningii fermentation solution prepared in step S2 at a volume ratio of 1:2:1 to obtain a mixed bacterial solution;

[0088] Preparation of S4 microbial agent: After the modified diatomaceous earth and the auxiliary agent are stirred evenly, the mixed bacterial solution is added dropwise under continuous stirring, and after the addition is completed, it is allowed to stand for 2-3 hours to obtain a mixture A; the coating agent is slowly added into distilled water, and stirred at 20°C to fully dissolve it to obtain a mixed solution B; the mixed solution B is added into the mixture A while stirring, and the mixture is fully mixed. After standing for 3 hours, it is added into an oven for drying until the moisture content is ≤15%, and granulated at 50°C by a disc granulator, and particles with a particle size of 2-5mm are screened out to obtain the final product microbial agent.

[0089] The mass-volume ratio of the coating agent to distilled water in step S4 is 20 g:1 L.

[0090] Compared with Example 3, this comparative example is the same as Example 3 except that the ratio of the three bacterial liquids in the microbial inoculant is changed. The other raw materials and steps are the same as those in Example 3.

[0091] Comparative Example 3

[0092] A microbial agent for preventing and controlling soil-borne diseases of grain crops comprises the following raw materials: 28 parts of microbial liquid, 48 parts of a carrier, 0.5 parts of a coating agent and 15 parts of an adjuvant.

[0093] The microbial bacterial liquid contains Pseudomonas guineensis, Bacillus polymyxa and Trichoderma pseudokoningii in a volume ratio of 1:1:2.

[0094] The carrier is modified diatomaceous earth; the coating agent comprises sodium alginate, hydroxyethyl cellulose and sodium carboxymethyl cellulose; and the auxiliary agent comprises sodium lignosulfonate and humic acid.

[0095] The preparation method of the modified diatomite is as follows: pretreating the diatomite with a 3 mol / L hydrochloric acid solution, soaking it for 0.5-1h, washing it with deionized water and drying it; the mass ratio of the hydroxyethyl cellulose, sodium carboxymethyl cellulose and sodium alginate is 1:2:2; the mass ratio of the sodium lignosulfonate and humic acid is 1:1.

[0096] The solid-to-liquid ratio of the diatomaceous earth and the hydrochloric acid solution is 1kg:3L.

[0097] A method for preparing a microbial agent for preventing and controlling soil-borne diseases of grain crops, characterized in that the preparation is carried out by the following steps:

[0098] S1 Preparation of Pseudomonas guguanis and Paenibacillus polymyxa: Pseudomonas guguanis and Paenibacillus polymyxa were thawed and activated in LB solid medium, and then single colonies were picked and inoculated into LB liquid medium, and cultured at 30°C and 180 r / min until OD600 = 0.6 to obtain seed liquid. The seed liquid was evenly inoculated into 200 mL LB liquid medium at 1% and cultured at 30°C and 180 r / min. The number of active colonies in the bacterial liquid was detected by the dilution plate method, and the number reached 1×10 8 cfu·mL -1 After the culture was terminated, the cells were washed three times with sterile PBS buffer solution and then resuspended to obtain two bacterial suspensions;

[0099] S2 Preparation of Trichoderma pseudocorningii fermentation broth: Activate the Trichoderma pseudocorningii test tube slant strain, pick a single colony and inoculate it into PDA medium, culture it at 25°C and 170 r / min until OD600 = 0.6 to obtain seed liquid, and evenly inoculate 1% of the seed liquid into 200 mL PDA liquid medium and culture it at 25°C and 170 r / min. Use the dilution plate method to detect the number of active colonies in the bacterial liquid, and the number of active colonies reaches 1×10 8 cfu·mL -1 Then the culture is terminated to obtain the Trichoderma koningii fermentation liquid;

[0100] S3: preparing a mixed bacterial solution: mixing the Pseudomonas guguanyi bacterial suspension and the Paenibacillus polymyxa bacterial suspension prepared in step S1 and the Trichoderma pseudokoningii fermentation liquid prepared in step S2 in a volume ratio of 1:1:2 to obtain a mixed bacterial solution;

[0101] Preparation of S4 microbial agent: After the modified diatomaceous earth and the auxiliary agent are stirred evenly, the mixed bacterial solution is added dropwise under continuous stirring, and after the addition is completed, it is allowed to stand for 2-3 hours to obtain a mixture A; the coating agent is slowly added into distilled water, and stirred at 20°C to fully dissolve it to obtain a mixed solution B; the mixed solution B is added into the mixture A while stirring, and the mixture is fully mixed. After standing for 3 hours, it is added into an oven for drying until the moisture content is ≤15%, and granulated at 50°C by a disc granulator, and particles with a particle size of 2-5mm are screened out to obtain the final product microbial agent.

[0102] The mass-volume ratio of the coating agent to distilled water in step S4 is 20 g:1 L.

[0103] Compared with Example 3, this comparative example is the same as Example 3 except that the ratio of the three bacterial liquids in the microbial inoculant is changed. The other raw materials and steps are the same as those in Example 3.

[0104] Comparative Example 4

[0105] A microbial agent for preventing and controlling soil-borne diseases of grain crops comprises the following raw materials: 28 parts of microbial liquid, 48 parts of a carrier, 0.5 parts of a coating agent and 15 parts of an adjuvant.

[0106] The microbial bacterial liquid contains Pseudomonas guineensis and Bacillus polymyxa in a volume ratio of 1:1.

[0107] Compared with Example 3, this comparative example is the same as Example 3 except that only Pseudomonas guguanis and Paenibacillus polymyxa are used as microbial agents. Other raw materials and steps are the same as those of Example 3.

[0108] Comparative Example 5

[0109] A microbial agent for preventing and controlling soil-borne diseases of grain crops comprises the following raw materials: 28 parts of microbial liquid, 48 parts of a carrier, 0.5 parts of a coating agent and 15 parts of an adjuvant.

[0110] The microbial culture liquid contains Pseudomonas guineensis and Trichoderma pseudokoningii in a volume ratio of 1:1.

[0111] Compared with Example 3, this comparative example uses only Pseudomonas guineensis and Trichoderma pseudokoningii as microbial agents, and the other raw materials and steps are the same as those of Example 3.

[0112] Comparative Example 6

[0113] A microbial agent for preventing and controlling soil-borne diseases of grain crops comprises the following raw materials: 28 parts of microbial liquid, 48 parts of a carrier, 0.5 parts of a coating agent and 15 parts of an adjuvant.

[0114] The microbial liquid contains Bacillus polymyxa and Trichoderma pseudokoningii in a volume ratio of 1:1.

[0115] Compared with Example 3, this comparative example is the same as Example 3 except that only Bacillus polymyxa and Trichoderma pseudokoningii are used as microbial agents. Other raw materials and steps are the same as those of Example 3.

[0116] Comparative Example 7

[0117] A microbial agent for preventing and controlling soil-borne diseases of grain crops comprises the following raw materials: 28 parts of microbial liquid, 48 parts of a carrier, 0.5 parts of a coating agent and 15 parts of an adjuvant.

[0118] Compared with Example 3, this comparative example is the same as Example 3 except that only Pseudomonas guguanis is used as the microbial agent. The other raw materials and steps are the same as those of Example 3.

[0119] Comparative Example 8

[0120] A microbial agent for preventing and controlling soil-borne diseases of grain crops comprises the following raw materials: 28 parts of microbial liquid, 48 parts of a carrier, 0.5 parts of a coating agent and 15 parts of an adjuvant.

[0121] Compared with Example 3, this comparative example is the same as Example 3 except that only Paenibacillus polymyxa is used as the microbial agent. Other raw materials and steps are the same as those of Example 3.

[0122] Comparative Example 9

[0123] A microbial agent for preventing and controlling soil-borne diseases of grain crops comprises the following raw materials: 28 parts of microbial liquid, 48 parts of a carrier, 0.5 parts of a coating agent and 15 parts of an adjuvant.

[0124] Compared with Example 3, this comparative example uses only Trichoderma pseudokoningii as the microbial agent, and the other raw materials and steps are the same as those of Example 3.

[0125] Performance Testing

[0126] Strain resistance test: 5 plant pathogens were selected and growth inhibition experiments were carried out using the plate confrontation method. The growth inhibition activity of the target strains on plant pathogens was detected by observing the size of the antagonistic circle. The 5 pathogens were Cochliobolus graminearum, Aspergillus graminearum var. tritici, Rhizoctonia graminearum, Fusarium graminearum, and Rhizoctonia solani. The inhibition rates of each strain are shown in Table 1.

[0127] Table 1 Antibacterial rate of strains

[0128] Pseudomonas guzexinii Paenibacillus polymyxa Trichoderma pseudokoningii Coccidiophore + + + Gramina graminearum var. + ++ ++ Rhizoctonia graminearum + ++ + Fusarium graminearum ++ + + Rhizoctonia solani + ++ +

[0129] Note: ++: strong suppression (radius > 2 mm); +: suppression (radius less than 2 mm)

[0130] It can be seen from the data in Table 1 that the strains selected in the present invention have good inhibitory effects on a variety of pathogens.

[0131] Pathogen inhibition test: Using the plate confrontation method, wheat root rot, take-all and sheath blight pathogens, as well as corn sheath blight and stem rot pathogens were cultured on PDA plates at 25°C in the dark for 36 h. A 5 mm bacterial cake was taken from the edge of the colony. Each pathogenic bacteria cake was placed in the center of the PDA plate. Two sterile filter paper pieces were placed about 2.5 cm on both sides of the plate. 10 ul of the mixed microbial solution (A) of Example 3 was dripped onto each filter paper piece. 600 nm =1), and LB liquid culture medium was added as blank control. Each treatment was repeated 6 times, and the culture was cultured at 25°C. The pathogen inhibition test was shown in Figure 1 Note: A is the wheat root rot inhibition picture, B is the wheat take-all rot inhibition picture, C is the wheat sheath blight inhibition picture, D is the corn sheath blight inhibition picture, and D is the corn stalk rot inhibition picture. Below each pathogen inhibition picture is the blank control of each pathogen.

[0132] Depend on Figure 1 It can be seen that the microbial agent of Example 3 of the present invention has a significant inhibitory effect on the pathogens of wheat root rot, take-all disease and sheath blight, as well as corn sheath blight and stem rot.

[0133] Experiment on prevention and control of wheat diseases:

[0134] Test materials: The wheat variety is "Jinnong No. 6".

[0135] Experimental design: 13 groups were set up in total, including Examples 1-3, Comparative Examples 1-9 and a blank control group: CK, no microbial agent was added; T1, the microbial agent of Example 1 was applied alone; T2, the microbial agent of Example 2 was applied alone; T3, the microbial agent of Example 3 was applied alone; T4, the microbial agent of Comparative Example 1 was applied alone; T5, the microbial agent of Comparative Example 2 was applied alone; T6, the microbial agent of Comparative Example 3 was applied alone; T7, the microbial agent of Comparative Example 4 was applied alone; T8, the microbial agent of Comparative Example 5 was applied alone; T9, the microbial agent of Comparative Example 6 was applied alone; T10, the microbial agent of Comparative Example 7 was applied alone; T11, the microbial agent of Comparative Example 8 was applied alone; T12, the microbial agent of Comparative Example 9 was applied alone. Three replicates were set up for each treatment, and the area of ​​each replicate test field was 50m 2 Wheat was sown on September 26, 2023 and harvested on June 20, 2024. All 12 groups of microbial agents were mixed into the base fertilizer and applied in furrows at a rate of 5 kg / mu. A unified water and fertilizer management plan was adopted during wheat planting: 120 kg / hm2 of pure nitrogen was used as base fertilizer. 2 , P2O5 112.5kg / hm 2 , K2O 11.2kg / hm 2 The experiment was conducted at the Modern Agricultural Science and Technology Innovation Base in Wuqing District, Tianjin.

[0136] Wheat disease survey: Wheat root rot, total rot and sheath blight are counted separately during the wheat maturity period.

[0137] Wheat root rot disease classification:

[0138] Level 0, no lesions on the roots;

[0139] Level 1, brown spots on the roots, covering 1%-10% of the roots;

[0140] Level 3, a few roots turn brown, and the halo occupies 11%-25% of the root;

[0141] Level 5: Most roots turn grayish yellow, with halos covering 26%-50% of the roots;

[0142] Level 7: All roots turn gray-yellow and rot, and halos occupy more than 50% of the roots.

[0143] Disease index = Σ(disease level × number of plants at that disease level) / (highest disease level × total number of plants) × 100%

[0144] Preventive effect = (control group disease index - treatment group disease index) / control disease index × 100%

[0145] Wheat Take-All Disease Classification:

[0146] Level 0, no disease;

[0147] Level 1: the proportion of damaged root area to the total root area is less than 25%;

[0148] Level 2, 25% ≤ the proportion of damaged root area to total root area ≤ 50%;

[0149] Level 3, 50%<the proportion of damaged root area to total root area≤75%;

[0150] Level 4: the proportion of damaged root area to total root area is more than 75%;

[0151] Level 5: dwarfing and yellowing at the seedling stage;

[0152] Level 6, plant death.

[0153] Disease index = Σ(disease level × number of plants at that disease level) / (highest disease level × total number of plants) × 100%

[0154] Preventive effect = (control group disease index - treatment group disease index) / control disease index × 100%

[0155] Wheat sheath blight disease classification:

[0156] Grade 0: no disease;

[0157] Level 1: The leaf sheaths are diseased but the stems are not diseased;

[0158] Level 3: The leaf sheath is infected and invades the stem, but the lesions on the stem do not encircle more than 1 / 2 of the stem;

[0159] Level 5: The lesions on the stems cover more than 1 / 2 of the stem, but there is no lodging or breakage;

[0160] Level 7: Withering, lodging, and dry white ears.

[0161] Disease index = Σ(disease level × number of plants at that disease level) / (highest disease level × total number of plants) × 100%

[0162] Preventive effect = (disease index of control group - disease index of treatment group) / disease index of control group × 100%.

[0163] Wheat yield determination: After wheat matures and is harvested, various indicators are counted based on the results of indoor seed testing. Ten plants are selected from each of the 14 test groups for each replicate, and the number of effective ears, number of grains per ear, and thousand-grain weight are measured. The number of effective ears is the number of wheat ears with less than 5 grains removed from a single plant; the number of grains per ear is the number of grains recorded after 20 tillers are randomly selected from the root of a single plant and the spikelets are removed; the thousand-grain weight is the weight of 1,000 grains per ear. The theoretical yield is calculated based on these three indicators: Theoretical yield = (number of effective ears × number of grains per ear × thousand-grain weight) / 10 6 ×0.85. The above disease and wheat yield data are shown in Table 2.

[0164] Table 2 Effects of microbial agents on wheat disease and yield

[0165]

[0166]

[0167] As can be seen from Table 2, compared with the control group, the microbial agent of the present invention can significantly reduce multiple wheat diseases, among which the microbial agent of Example 3 performs best, with the control effects on root rot, take-all disease and sheath blight reaching 61.2%, 91.5% and 67.5%, respectively. In addition, it can be seen that the microbial agents of Comparative Examples 7-12, which change the composition of the agent, break the synergistic balance between the three strains, greatly reduce the control effect on soil-borne wheat diseases, and thus lead to a decrease in yield.

[0168] Experiment on prevention and control of corn diseases:

[0169] Test material: The corn variety is "Era 128".

[0170] Experimental design: 13 groups were set up in total, including Examples 1-3, Comparative Examples 1-9 and a blank control group: CK, no microbial agent was added; T1, the microbial agent of Example 1 was applied alone; T2, the microbial agent of Example 2 was applied alone; T3, the microbial agent of Example 3 was applied alone; T4, the microbial agent of Comparative Example 1 was applied alone; T5, the microbial agent of Comparative Example 2 was applied alone; T6, the microbial agent of Comparative Example 3 was applied alone; T7, the microbial agent of Comparative Example 4 was applied alone; T8, the microbial agent of Comparative Example 5 was applied alone; T9, the microbial agent of Comparative Example 6 was applied alone; T10, the microbial agent of Comparative Example 7 was applied alone; T11, the microbial agent of Comparative Example 8 was applied alone; T12, the microbial agent of Comparative Example 9 was applied alone. Three replicates were set for each treatment, and the area of ​​each replicate test field was 100m 2 . All 12 groups of microbial agents were mixed into the base fertilizer and applied in furrows at a dosage of 5 kg / mu. A unified water and fertilizer management plan was adopted during corn planting: 40 kg / mu of base fertilizer and long-term slow-release fertilizer were used. The experiment was conducted at the Modern Agricultural Science and Technology Innovation Base in Wuqing District, Tianjin.

[0171] Corn disease survey: since the first appearance of corn sheath blight in the field, a survey was conducted every 10 days, with a 5-point sampling method for each treatment. The number of corn sheath blight-affected plants and the disease stage were recorded, and the corn sheath blight disease index and control effect were calculated. The incidence of corn stalk rot was investigated during the milky and waxy stages of corn, and the disease index and control effect were calculated.

[0172] Corn sheath blight disease classification:

[0173] Grade 0, no lesions;

[0174] Level 1: there are lesions on the leaf sheath, and the area of ​​the lesions is less than 25% of the leaf sheath area;

[0175] Level 3: there are lesions on the leaf sheath, and the area of ​​lesions accounts for 25%-<50% of the leaf sheath area;

[0176] Level 5: There are lesions on the leaf sheath, and the area of ​​lesions accounts for 50%-75% of the leaf sheath area;

[0177] Level 7: There are lesions on the leaf sheath, the lesion area exceeds 75% of the leaf sheath area, and the leaves below the ear are diseased;

[0178] Level 9: leaf sheaths and bracts are diseased, and the plant is dead or close to death.

[0179] Disease index = Σ(disease level × number of plants at that disease level) / (highest disease level × total number of plants) × 100%

[0180] Preventive effect = (disease index of control group - disease index of treatment group) / disease index of control group × 100%.

[0181] Corn stalk rot disease classification:

[0182] Level 1: The whole plant grows normally, with the leaves in the middle and lower parts showing signs of withering / yellowishness, the stem base nodes are normal, and the ear growth is normal;

[0183] Level 3: All leaves of the plant show symptoms of wilt, the stem base nodes are normal, and the ear growth is normal;

[0184] Level 5: The leaves of the whole plant show typical wilt symptoms, the base of the stem changes color and is slightly water-soaked, and the fruit clusters are basically normal;

[0185] Level 7: The leaves of the plants show typical wilt symptoms, the stem base nodes become obviously soft but not inverted, the fruit clusters droop, and the grains are not full;

[0186] Level 9: The whole plant is dead and fallen over, the vascular bundles at the base of the stem are broken, and the grains are shriveled.

[0187] Disease index = Σ(disease level × number of plants at that disease level) / (highest disease level × total number of plants) × 100%

[0188] Preventive effect = (disease index of control group - disease index of treatment group) / disease index of control group × 100%.

[0189] Corn Yield Determination: Investigate the yield impact of corn during harvest time.

[0190] The above corn disease index, disease control and corn yield data are shown in Table 3.

[0191] Table 3 Effects of microbial agents on corn disease and yield

[0192]

[0193] As shown in Table 3, the microbial agent of the present invention can effectively improve the disease resistance and increase corn yield. However, in Comparative Examples 1-9, which changed the composition of the agent, the synergistic balance between the three strains was broken, the disease resistance of corn decreased, and thus the yield decreased.

[0194] It should be noted that the above embodiments are only partial embodiments of the preferred methods of implementing the present invention, rather than all embodiments. Obviously, based on the above embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

Claims

1. A microbial agent for preventing and controlling soil-borne diseases of grain crops, characterized in that: The preparation comprises the following raw materials: 22-28 parts of microbial liquid, 45-48 parts of carrier, 0.4-0.5 parts of coating agent and 10-15 parts of auxiliary agent.

2. The microbial agent for preventing and controlling soil-borne diseases of grain crops according to claim 1, characterized in that: The microbial bacterial liquid contains Pseudomonas guguanensis, Paenibacillus polymyxa and Trichoderma koningiopsis in a volume ratio of 1:1:

1.

3. The microbial agent for preventing and controlling soil-borne diseases of grain crops according to claim 1, characterized in that: The Pseudomonas guguanyi has a preservation number of CGMCC No.1.15627, purchased from China General Microorganism Collection Center; the Bacillus polymyxa has a preservation number of CGMCC No.1.15984, purchased from China General Microorganism Collection Center; the Trichoderma pseudokoningii has a preservation number of CGMCC No.1.4914, purchased from China General Microorganism Collection Center.

4. The microbial agent for preventing and controlling soil-borne diseases of grain crops according to claim 1, characterized in that: The carrier is modified diatomaceous earth; the coating agent comprises sodium alginate, hydroxyethyl cellulose and sodium carboxymethyl cellulose; and the auxiliary agent comprises sodium lignosulfonate and humic acid.

5. The microbial agent for preventing and controlling soil-borne diseases of grain crops according to claim 4, characterized in that: The preparation method of the modified diatomite is as follows: pretreating the diatomite with 3 mol / L hydrochloric acid, fully soaking it for 0.5-1h, washing it with deionized water and drying it; the mass ratio of the hydroxyethyl cellulose, sodium carboxymethyl cellulose and sodium alginate is 1:2:2; the mass ratio of the sodium lignosulfonate and humic acid is 1:

1.

6. The microbial agent for preventing and controlling soil-borne diseases of grain crops according to claim 5, characterized in that: The solid-to-liquid ratio of the diatomaceous earth and the hydrochloric acid solution is 1kg:3L.

7. A method for preparing a microbial agent for preventing and controlling soil-borne diseases of grain crops according to any one of claims 1 to 6, characterized in that: Prepared by the following steps: S1 Preparation of Pseudomonas guguanis and Paenibacillus polymyxa: Pseudomonas guguanis and Paenibacillus polymyxa were thawed and activated in LB solid medium, and then single colonies were picked and inoculated into LB liquid medium, and cultured at 30°C and 180r / min until OD 600 =0.6 to obtain seed solution, and the seed solution was evenly inoculated into 200 mL LB liquid medium at 1% and cultured at 30°C and 180 r / min. The bacterial colony activity number was detected by the dilution plate method, and the number reached 1×10 8 cfu·mL -1 After the culture was terminated, the cells were washed three times with sterile PBS buffer solution and then resuspended to obtain two bacterial suspensions; S2 Preparation of Trichoderma pseudokoningii fermentation broth: Activate the Trichoderma pseudokoningii test tube slant strain, pick a single colony and inoculate it into PDA medium, and culture it at 25℃ and 170r / min until OD 600 =0.6 to obtain seed solution, and the seed solution was evenly inoculated into 200 mL PDA liquid culture medium at 1% and cultured at 25°C and 170 r / min. The bacterial colony activity was detected by the dilution plate method, and the number of bacterial colonies reached 1×10 8 cfu·mL -1 Then the culture is terminated to obtain the Trichoderma koningii fermentation liquid; S3: preparing a mixed bacterial solution: mixing the Pseudomonas guguanyi bacterial suspension and the Paenibacillus polymyxa bacterial suspension prepared in step S1 and the Trichoderma pseudokoningii fermentation liquid prepared in step S2 at a volume ratio of 1:1:1 to obtain a mixed bacterial solution; Preparation of S4 microbial agent: After the modified diatomaceous earth and the auxiliary agent are stirred evenly, the mixed bacterial solution is added dropwise under continuous stirring, and after the addition is completed, it is allowed to stand for 2-3 hours to obtain a mixture A; the coating agent is slowly added into distilled water, and stirred at 20°C to fully dissolve it to obtain a mixed solution B; the mixed solution B is then added into the mixture A while stirring, and the mixture is fully mixed. After standing for 3 hours, it is added into an oven for drying until the moisture content is ≤15%, and granulated at 50°C by a disc granulator, and particles with a particle size of 2-5mm are screened out to obtain the final product microbial agent.

8. The method for preparing the microbial agent for preventing and controlling soil-borne diseases of grain crops according to claim 7, characterized in that: The mass-volume ratio of the coating agent to distilled water in step S4 is 20 g:1 L.

Images