Compound microbial agent for preventing and treating rice sheath blight disease and preparation method thereof
By using complex microbial agents, including Streptocyanidae, Trichoderma ginger and yeast, the pollution problem of chemical pesticides in the prevention and control of rice streak blight has been solved, and efficient prevention and control and the improvement of rice yield has been achieved.
Patent Information
- Application Number
- CN202510141016.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-08
- Publication Date
- 2025-04-15
AI Technical Summary
The prevention and treatment of rice streak blight depends on chemical pesticides, which leads to environmental pollution and drug resistance problems, and lacks high resistance varieties, which affects the green and sustainable development of the rice industry.
A complex microbial agent, including Streptocyanus burgdoria, Trichoderma ginger and yeast, was prepared in a liquid form for spraying on rice by synergistically acting with additives (potassium dihydrogen phosphate and methyl jasmonate).
This fungal agent significantly inhibits the growth of rice veins blight bacteria, improves the stress resistance and yield of rice, reduces the use of chemical pesticides, and improves environmental pollution problems.
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Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of microorganisms, and particularly relates to a composite microbial agent for preventing and controlling rice sheath blight and a preparation method thereof. Background Art
[0002] Rice not only meets basic food needs, but also plays an important role in the agricultural economy. Rice is an important cash crop with a wide planting area and high output value. The by-products of rice processing, such as rice straw and rice husk, have a wide range of uses and can be used in feed, papermaking, winemaking and other fields, further increasing the added value of agriculture. In addition, the development of the rice industry has also promoted the prosperity of the rural economy and increased farmers' income.
[0003] Rice sheath blight, rice blast and bacterial leaf blight are collectively known as the three major rice diseases in the world. Sheath blight can infect rice from the seedling stage to the late growth stage, causing the rice to fail to head normally or an increase in the number of barren grains. The main prevention and control measures for rice diseases include the prediction and forecast of major diseases, the breeding and planting of resistant varieties, agricultural prevention and control, physical prevention and control, chemical prevention and control, and biological prevention and control. However, due to the limitations of rice resistant germplasm resources, disease prediction and forecast, and agricultural prevention and control measures, chemical prevention and control has always been the main means of controlling various rice diseases in years of epidemics. However, the excessive and blind application of chemical agents not only increases agricultural production costs and affects the quality of rice and the safety of the ecological environment, but also causes pathogens to develop drug resistance, causing the disease to become rampant again, which seriously restricts the green and sustainable development of my country's rice industry.
[0004] Rice sheath blight is a worldwide soil-borne fungal disease caused by Rhizoctonia solani. With the promotion of close planting, high fertilizer and high-yield cultivation techniques of dwarf and multi-tiller varieties and changes in management methods, the occurrence of sheath blight is becoming more and more serious, with yield losses exceeding 30% in severe cases. At present, no resource materials immune to rice sheath blight have been found in rice breeding, and there is a lack of highly resistant varieties. Its prevention and control measures are still mainly based on efficient, fast and simple chemical control, but the environmental pollution, pesticide residues and resistance caused by the irrational use of chemical pesticides are becoming increasingly prominent. Therefore, it is more urgent to find more suitable prevention and control methods to control rice sheath blight. Summary of the invention
[0005] The purpose of the present invention is to provide a composite microbial agent for preventing and controlling rice sheath blight, which can effectively prevent and control rice sheath blight and increase rice yield.
[0006] In order to achieve the above technical objectives, the technical solution adopted by the present invention is:
[0007] A composite microbial agent for preventing and controlling rice sheath blight, comprising Streptomyces vinaceus drappus, Trichoderma viridescens, and Saccharomyces paradoxus;
[0008] Furthermore, the preservation number of the Streptomyces ruticosa is CGMCC No.4.7294, purchased from the China General Microorganism Collection Center, and the original preservation date is June 26, 2015; the preservation number of the Trichoderma viridis is CGMCC No.5.1040, purchased from the China General Microorganism Collection Center, and the original preservation date is August 8, 2005; the preservation number of the Saccharomyces paradoxus is CGMCC No.2.5691, purchased from the China General Microorganism Collection Center, and the original preservation date is December 5, 2016.
[0009] Furthermore, the microbial agent is a liquid agent.
[0010] A method for preparing a composite microbial agent for preventing and controlling rice sheath blight comprises the following steps:
[0011] S1 Preparation of mixed bacterial solution: Thaw Streptomyces rutinus, Trichoderma chlororaphis, and Saccharomyces paradoxus and activate them in LB solid medium. Then pick a single colony and inoculate it into LB liquid medium. Cultivate at 25-28℃ and 170r / min until OD 600 =0.6 to obtain seed solution, and the seed solution was inoculated into 200 mL LB liquid medium at 1% and cultured at 25-28°C and 170 r / min. The bacterial colony activity was detected by the dilution plate method, and the number of colonies reached 1×10 8 cfu / mL, the culture was terminated, and three bacterial solutions were obtained, and the three bacterial solutions were mixed in a volume ratio of 1:1:1 to obtain a mixed bacterial solution;
[0012] S2 Preparation of microbial agent: Add potassium dihydrogen phosphate and methyl jasmonate into 1L of distilled water, sterilize after fully dissolving, then add starch and mix thoroughly to obtain a mixed solution A, add the mixed bacterial solution into the mixed solution A, stir and mix thoroughly to obtain the microbial agent.
[0013] Furthermore, in step S2, the solid-to-liquid ratio of potassium dihydrogen phosphate, methyl jasmonate, starch and distilled water is 1g:0.5g:10g:1L.
[0014] Furthermore, in step S2, the volume ratio of the mixed solution A to the mixed bacterial solution is 1:2.
[0015] The raw materials used in the present invention are all commercially available, and the three strains used can be publicly purchased by searching in the strain catalog of the China General Microbiological Collection Center, without the need for repeated biological preservation.
[0016] Beneficial Effects
[0017] (1) The present invention screens three functional microbial strains, and the three strains have antagonistic effects on rice sheath blight and can effectively prevent and control rice sheath blight. Streptomyces viniferae has a significant inhibitory effect on the pathogen of sheath blight, protects plants from disease invasion, and also produces antibiotics and other metabolites to stimulate rice growth, improve rice stress resistance and yield, and can also induce plant systemic disease resistance; Trichoderma chlororaphis can secrete antibiotics, chitinase, β-glucanase and other substances to directly inhibit the growth and infection of plant pathogenic fungi. Trichoderma chlororaphis can also promote plant root development and overall growth by secreting indoleacetic acid and nutrients; Saccharomyces cerevisiae can inhibit the growth of pathogenic fungi, reduce the occurrence of diseases, produce antibacterial substances and antioxidants, and improve the resistance of plants to environmental stress and pathogens. After the three strains are mixed in equal proportions, they cooperate synergistically, with significant anti-disease and growth-promoting effects. During the growth process of rice, the activity of defense enzymes in seedlings can be increased, and the resistance of rice can be improved.
[0018] (2) Potassium dihydrogen phosphate and methyl jasmonate are also added to the microbial liquid of the present invention. Potassium dihydrogen phosphate can activate the activity of enzymes such as phenol oxidase and promote the process of lignin synthesis. Lignin is an important component of plant cell walls, which provides additional mechanical strength and stability for cell walls, protects cells from damage by the external environment, and promotes plant resistance to pathogens; it also provides the required phosphorus element for rice plants, promotes photosynthesis and nutrient absorption of plants, thereby increasing the growth rate and yield of rice. Methyl jasmonate can enhance the disease resistance of plants. Methyl jasmonate directly toxicates pathogens by activating the defense response of plants, such as inducing the production of alkaloids and phenolic acids, and can also regulate plant photosynthesis and promote growth and development. Starch can provide energy for the survival of microorganisms and maintain the high activity of microorganisms.
[0019] (3) The microbial agent of the present invention has a simple and convenient preparation method, reduces the application of chemical fungicides, improves environmental pollution, effectively inhibits the growth of rice sheath blight pathogens, and increases rice yield. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 This is a diagram showing the antibacterial effect of the mixed bacterial solution of Example 1 of the present invention. DETAILED DESCRIPTION
[0021] The technical solution of the present invention is further described below in conjunction with specific embodiments, but is not limited thereto.
[0022] Example 1
[0023] A composite microbial agent for preventing and controlling rice sheath blight, comprising Streptomyces ruticosa, Trichoderma chlororaphis, and Saccharomyces paradoxus;
[0024] The deposit number of the Streptomyces ruticosa is CGMCC No.4.7294, which was purchased from the China General Microorganism Collection Center, and the original deposit date is June 26, 2015; the deposit number of the Trichoderma viridis is CGMCC No.5.1040, which was purchased from the China General Microorganism Collection Center, and the original deposit date is August 8, 2005; the deposit number of the Saccharomyces paradoxus is CGMCC No.2.5691, which was purchased from the China General Microorganism Collection Center, and the original deposit date is December 5, 2016.
[0025] The microbial agent is a liquid agent.
[0026] A method for preparing a composite microbial agent for preventing and controlling rice sheath blight comprises the following steps:
[0027] S1 Preparation of mixed bacterial solution: Thaw Streptomyces rutinus, Trichoderma chlororaphis, and Saccharomyces paradoxus and activate them in LB solid medium. Then pick a single colony and inoculate it into LB liquid medium. Cultivate at 25-28℃ and 170r / min until OD 600 =0.6 to obtain seed solution, and the seed solution was inoculated into 200 mL LB liquid medium at 1% and cultured at 25-28°C and 170 r / min. The bacterial colony activity was detected by the dilution plate method, and the number of colonies reached 1×10 8 cfu / mL, the culture was terminated, and three bacterial solutions were obtained, and the three bacterial solutions were mixed in a volume ratio of 1:1:1 to obtain a mixed bacterial solution;
[0028] S2 Preparation of microbial agent: Add potassium dihydrogen phosphate and methyl jasmonate into 1L of distilled water, sterilize after fully dissolving, then add starch and mix thoroughly to obtain a mixed solution A, add the mixed bacterial solution into the mixed solution A, stir and mix thoroughly to obtain the microbial agent.
[0029] In step S2, the solid-to-liquid ratio of potassium dihydrogen phosphate, methyl jasmonate, starch and distilled water is 1g:0.5g:10g:1L.
[0030] In step S2, the volume ratio of the mixed solution A to the mixed bacterial solution is 1:2.
[0031] Comparative Example 1
[0032] A composite microbial agent for preventing and controlling rice sheath blight, comprising Streptomyces ruticosa, Trichoderma chlororaphis, and Saccharomyces paradoxus;
[0033] The deposit number of the Streptomyces ruticosa is CGMCC No.4.7294, which was purchased from the China General Microorganism Collection Center, and the original deposit date is June 26, 2015; the deposit number of the Trichoderma viridis is CGMCC No.5.1040, which was purchased from the China General Microorganism Collection Center, and the original deposit date is August 8, 2005; the deposit number of the Saccharomyces paradoxus is CGMCC No.2.5691, which was purchased from the China General Microorganism Collection Center, and the original deposit date is December 5, 2016.
[0034] The microbial agent is a liquid agent.
[0035] A method for preparing a composite microbial agent for preventing and controlling rice sheath blight comprises the following steps:
[0036] S1 Preparation of mixed bacterial solution: Thaw Streptomyces rutinus, Trichoderma chlororaphis, and Saccharomyces paradoxus and activate them in LB solid medium. Then pick a single colony and inoculate it into LB liquid medium. Cultivate at 25-28℃ and 170r / min until OD 600 =0.6 to obtain seed solution, and the seed solution was inoculated into 200 mL LB liquid medium at 1% and cultured at 25-28°C and 170 r / min. The bacterial colony activity was detected by the dilution plate method, and the number of colonies reached 1×10 8 cfu / mL, the culture was terminated, and three bacterial solutions were obtained, and the three bacterial solutions were mixed in a volume ratio of 2:1:1 to obtain a mixed bacterial solution;
[0037] S2 Preparation of microbial agent: Add potassium dihydrogen phosphate and methyl jasmonate into 1L of distilled water, sterilize after fully dissolving, then add starch and mix thoroughly to obtain a mixed solution A, add the mixed bacterial solution into the mixed solution A, stir and mix thoroughly to obtain the microbial agent.
[0038] In step S2, the solid-to-liquid ratio of potassium dihydrogen phosphate, methyl jasmonate, starch and distilled water is 1g:0.5g:10g:1L.
[0039] In step S2, the volume ratio of the mixed solution A to the mixed bacterial solution is 1:2.
[0040] Compared with Example 1, this comparative example is the same as Example 1 except that the volume ratio of the three bacterial liquids of Streptomyces rutinus, Trichoderma chlororaphis and Saccharomyces paradoxus is changed to 2:1:1. The other raw materials and steps are the same as those of Example 1.
[0041] Comparative Example 2
[0042] A composite microbial agent for preventing and controlling rice sheath blight, comprising Streptomyces ruticosa, Trichoderma chlororaphis, and Saccharomyces paradoxus;
[0043] The deposit number of the Streptomyces ruticosa is CGMCC No.4.7294, which was purchased from the China General Microorganism Collection Center, and the original deposit date is June 26, 2015; the deposit number of the Trichoderma viridis is CGMCC No.5.1040, which was purchased from the China General Microorganism Collection Center, and the original deposit date is August 8, 2005; the deposit number of the Saccharomyces paradoxus is CGMCC No.2.5691, which was purchased from the China General Microorganism Collection Center, and the original deposit date is December 5, 2016.
[0044] The microbial agent is a liquid agent.
[0045] A method for preparing a composite microbial agent for preventing and controlling rice sheath blight comprises the following steps:
[0046] S1 Preparation of mixed bacterial solution: Thaw Streptomyces rutinus, Trichoderma chlororaphis, and Saccharomyces paradoxus and activate them in LB solid medium. Then pick a single colony and inoculate it into LB liquid medium. Cultivate at 25-28℃ and 170r / min until OD 600 =0.6 to obtain seed solution, and the seed solution was inoculated into 200 mL LB liquid medium at 1% and cultured at 25-28°C and 170 r / min. The bacterial colony activity was detected by the dilution plate method, and the number of colonies reached 1×10 8 cfu / mL, the culture was terminated, and three bacterial solutions were obtained, which were mixed in a volume ratio of 1:2:1 to obtain a mixed bacterial solution;
[0047] S2 Preparation of microbial agent: Add potassium dihydrogen phosphate and methyl jasmonate into 1L of distilled water, sterilize after fully dissolving, then add starch and mix thoroughly to obtain a mixed solution A, add the mixed bacterial solution into the mixed solution A, stir and mix thoroughly to obtain the microbial agent.
[0048] In step S2, the solid-to-liquid ratio of potassium dihydrogen phosphate, methyl jasmonate, starch and distilled water is 1g:0.5g:10g:1L.
[0049] In step S2, the volume ratio of the mixed solution A to the mixed bacterial solution is 1:2.
[0050] Compared with Example 1, this comparative example is the same as Example 1 except that the volume ratio of the three bacterial liquids of Streptomyces rutinus, Trichoderma chlororaphis and Saccharomyces paradoxus is changed to 1:2:1. The other raw materials and steps are the same as those of Example 1.
[0051] Comparative Example 3
[0052] A composite microbial agent for preventing and controlling rice sheath blight, comprising Streptomyces ruticosa, Trichoderma chlororaphis, and Saccharomyces paradoxus;
[0053] The deposit number of the Streptomyces ruticosa is CGMCC No.4.7294, which was purchased from the China General Microorganism Collection Center, and the original deposit date is June 26, 2015; the deposit number of the Trichoderma viridis is CGMCC No.5.1040, which was purchased from the China General Microorganism Collection Center, and the original deposit date is August 8, 2005; the deposit number of the Saccharomyces paradoxus is CGMCC No.2.5691, which was purchased from the China General Microorganism Collection Center, and the original deposit date is December 5, 2016.
[0054] The microbial agent is a liquid agent.
[0055] A method for preparing a composite microbial agent for preventing and controlling rice sheath blight comprises the following steps:
[0056] S1 Preparation of mixed bacterial solution: Thaw Streptomyces rutinus, Trichoderma chlororaphis, and Saccharomyces paradoxus and activate them in LB solid medium. Then pick a single colony and inoculate it into LB liquid medium. Cultivate at 25-28℃ and 170r / min until OD 600 =0.6 to obtain seed solution, and the seed solution was inoculated into 200 mL LB liquid medium at 1% and cultured at 25-28°C and 170 r / min. The bacterial colony activity was detected by the dilution plate method, and the number of colonies reached 1×10 8 cfu / mL, the culture was terminated, and three bacterial solutions were obtained, and the three bacterial solutions were mixed in a volume ratio of 1:1:2 to obtain a mixed bacterial solution;
[0057] S2 Preparation of microbial agent: Add potassium dihydrogen phosphate and methyl jasmonate into 1L of distilled water, sterilize after fully dissolving, then add starch and mix thoroughly to obtain a mixed solution A, add the mixed bacterial solution into the mixed solution A, stir and mix thoroughly to obtain the microbial agent.
[0058] In step S2, the solid-to-liquid ratio of potassium dihydrogen phosphate, methyl jasmonate, starch and distilled water is 1g:0.5g:10g:1L.
[0059] In step S2, the volume ratio of the mixed solution A to the mixed bacterial solution is 1:2.
[0060] Compared with Example 1, this comparative example is the same as Example 1 except that the volume ratio of the three bacterial liquids of Streptomyces rutinus, Trichoderma chlororaphis and Saccharomyces paradoxus is changed to 1:1:2. The other raw materials and steps are the same as those of Example 1.
[0061] Comparative Example 4
[0062] Compared with Example 1, the microbial mixed liquid in this comparative example only contains Streptomyces rutinus and Trichoderma chlororaphis in a volume ratio of 1:1, and the other raw materials and steps are the same as those in Example 1.
[0063] Comparative Example 5
[0064] Compared with Example 1, the microbial mixed bacterial liquid in this comparative example only contains Streptomyces ruthenicus and Saccharomyces paradoxus in a volume ratio of 1:1, and the other raw materials and steps are the same as those in Example 1.
[0065] Comparative Example 6
[0066] Compared with Example 1, the microbial mixed liquid in this comparative example only contains Trichoderma viride and Saccharomyces cerevisiae in a volume ratio of 1:1, and the other raw materials and steps are the same as those in Example 1.
[0067] Comparative Example 7
[0068] Compared with Example 1, the microbial agent in this comparative example only contains Streptomyces ruticosa, and the other raw materials and steps are the same as those in Example 1.
[0069] Comparative Example 8
[0070] Compared with Example 1, the microbial agent in this comparative example only contains Trichoderma viride, and the other raw materials and steps are the same as those in Example 1.
[0071] Comparative Example 9
[0072] Compared with Example 1, the microbial agent in this comparative example only contains Saccharomyces cerevisiae, and the remaining raw materials and steps are the same as those in Example 1.
[0073] Performance Testing
[0074] Determination of the ability to inhibit pathogens:
[0075] The activated Rhizoctonia solani was punched with a hole punch to obtain a 5 mm diameter bacterial cake, and the pathogenic bacteria cake was placed in the center of the PDA plate. 10 μL of the three bacterial suspensions obtained in step S1 of Example 1 were added at about 22 mm on both sides of the plate. An equal amount of sterile water was used as a control. Each treatment was repeated 5 times and cultured at a constant temperature of 25-28° C. The colony diameter was measured, and the antibacterial rate was calculated using the mycelial growth rate method.
[0076] Table 1 Antibacterial rate of strains
[0077] strain Inhibition rate of sheath blight pathogen (%) Streptomyces ruthenica 73.5 Trichoderma chlororaphis 57.1 Strange yeast 43.6
[0078] The plate confrontation experiment found that the three strains used in the present invention all have an inhibitory effect on rice sheath blight, among which Streptomyces vinifera has the most significant inhibitory effect on the sheath blight pathogen.
[0079] In addition, the plate confrontation method was used to detect the inhibitory effect of the mixed bacterial solution obtained in Example 1 on pathogenic bacteria, and a clear water control group was set up. The antibacterial effect diagram is shown in FIG. Figure 1 shown.
[0080] Planting test
[0081] Test rice: Runfeng Xiangzhan.
[0082] Experimental field: The rice-growing area of Honghu City, Jingzhou City, Hubei Province, where the soil is fertile, the terrain is flat, and the water resources are abundant. Rice sheath blight is prone to occur during the rice planting process.
[0083] Ten treatment groups were set up, including conventional fertilization, conventional fertilization + the bacterial agent obtained in Example 1, and comparative examples 1-9. Each treatment group was repeated 3 times, and the rice planting area of each group was 60m 2 , 30 kg / mu of compound fertilizer (nitrogen, phosphorus and potassium ratio of 20:13:15) was applied to the ground throughout the experiment. The first microbial agent was sprayed about a week before the rice grew to the break stage, and the second spraying was carried out 7 days after the first spraying. There was no rainfall during the spraying period, and the spraying amount was 25L / mu. No disease prevention and control was carried out during the experiment, and other field management measures were consistent with the field.
[0084] Index statistics: Before rice harvest, 20 clumps were surveyed in each treatment group using the diagonal 5-point sampling method to investigate the total number of plants, the number of diseased plants, the disease level and the disease index, and the disease index and control effect were calculated. When the experiment was harvested, 5 random sampling points were taken in each plot, and 1m 2 , take 20 effective ears at each point, conduct indoor planting test to calculate the plot yield, and calculate the equivalent yield and yield increase rate.
[0085] The disease grading standard for rice sheath blight is as follows: Level 0, the whole plant is disease-free; Level 1, the 4th leaf blade and the leaf sheaths and leaves below it are diseased; Level 3, the 3rd leaf blade and the leaf sheaths and leaves below it are diseased; Level 5, the 2nd leaf blade and the leaf sheaths and leaves below it are diseased; Level 7, the flag leaf blade and the leaf sheaths and leaves below it are diseased; Level 9, the whole plant is diseased and dies prematurely.
[0086] Disease index = Σ(number of diseased plants at each level × number of disease levels) / (total number of plants surveyed × number of highest disease level) × 100; control effect (%) = (disease index of control group - disease index of treatment group) / disease index of control group × 100%.
[0087] Table 2 Planting effect
[0088]
[0089]
[0090] From the data in the table, it can be seen that the microbial agent of the present invention can effectively prevent and control rice sheath blight and increase rice yield. However, in the comparative example 1-9 test group with changed agent composition, the synergistic balance between the three strains was broken, the disease resistance of rice decreased, and the yield decreased, indicating that the three strains of the microbial agent are indispensable for the prevention and control of rice sheath blight, and the effect is weak if one is missing.
[0091] Determination of defense enzyme activity in rice leaves:
[0092] 48 hours after the second microbial agent was sprayed on the rice, 2.00 g of rice leaves were frozen in liquid nitrogen and stored. The enzyme activities of peroxidase (POD), catalase (CAT) and superoxide dismutase (SOD) in the leaves were determined using corresponding kits.
[0093] Table 3 Defense enzyme activities
[0094] Group POD(U / g FW) CAT(U / g FW) SOD (U / g FW) CK 517 305 282 Example 1 762 471 510 Comparative Example 1 694 448 476 Comparative Example 2 682 436 465 Comparative Example 3 657 432 451 Comparative Example 4 631 416 437 Comparative Example 5 618 409 418 Comparative Example 6 603 383 402 Comparative Example 7 579 357 385 Comparative Example 8 567 339 374 Comparative Example 9 542 325 358
[0095] From the data in Table 3, it can be seen that the bacterial agent of the present invention effectively increases the enzyme activities of peroxidase, catalase and superoxide dismutase in rice leaves. The increase in enzyme activity can enhance the resistance of rice to diseases and insect pests, reduce the incidence of diseases, and thus achieve an increase in rice production.
[0096] 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 composite microbial agent for preventing and controlling rice sheath blight, characterized in that: The composite microorganisms are composed of Streptomyces vinaceusdrappus, Trichoderma viridescens and Saccharomyces paradoxus; the preservation number of Streptomyces vinaceusdrappus is CGMCC No.4.7294, purchased from China General Microorganism Collection Center; the preservation number of Trichoderma viridescens is CGMCC No. 5.1040, purchased from China General Microorganism Collection Center; the preservation number of the strange yeast is CGMCC No. 2.5691, purchased from China General Microorganism Collection Center.
2. The composite microbial agent for preventing and controlling rice sheath blight according to claim 1, characterized in that: The microbial agent is a liquid agent.
3. A method for preparing the composite microbial agent for controlling rice sheath blight according to claim 1-2, characterized in that: The method comprises the following steps: S1 Preparation of mixed bacterial solution: Thaw Streptomyces rutinus, Trichoderma chlororaphis, and Saccharomyces paradoxus and activate them in LB solid medium. Then pick a single colony and inoculate it into LB liquid medium. Cultivate at 25-28℃ and 170r / min until OD 600 =0.6 to obtain seed solution, and the seed solution was inoculated into 200 mL LB liquid medium at 1% and cultured at 25-28°C and 170 r / min. The bacterial colony activity was detected by the dilution plate method, and the number of colonies reached 1×10 8 cfu / mL, the culture was terminated, and three bacterial solutions were obtained, and the three bacterial solutions were evenly mixed in a volume ratio of 1:1:1 to obtain a mixed bacterial solution; S2 Preparation of microbial agent: Add potassium dihydrogen phosphate and methyl jasmonate into 1L of distilled water, sterilize after fully dissolving, then add starch and mix thoroughly to obtain a mixed solution A, add the mixed bacterial solution into the mixed solution A, stir and mix thoroughly to obtain the microbial agent.
4. The method for preparing the composite microbial agent for preventing and controlling rice sheath blight according to claim 3, characterized in that: In step S2, the solid-to-liquid ratio of potassium dihydrogen phosphate, methyl jasmonate, starch and distilled water is 1g:0.5g:10g:1L.
5. The method for preparing the composite microbial agent for preventing and controlling rice sheath blight according to claim 3, characterized in that: In step S2, the volume ratio of the mixed solution A to the mixed bacterial solution is 1:2.