CN114085797B - Bacillus complex inoculant and application thereof to rice - Google Patents

Abstract

The invention belongs to the field of agricultural microorganisms, and discloses a bacillus composite microbial agent and application thereof to rice, wherein the composite microbial agent consists of Bacillus belgii SD120 and Bacillus megaterium CY32, the preservation number of the Bacillus belgii is CCTCC NO: M20211411, and the preservation number of the Bacillus megaterium is CCTCC NO: M20211409. Compared with a single strain, the composite strain has the functions of promoting growth and increasing yield of rice, and simultaneously has the functions of preventing and controlling rice sheath blight. Has certain application prospect in the aspect of preventing diseases and increasing yield of rice.

Description

Bacillus complex inoculant and application thereof to rice

Technical Field

The invention belongs to the field of agricultural microorganisms, and particularly relates to a bacillus composite microbial agent and application thereof to rice.

Background

The plant rhizosphere microorganisms are considered as a second genome of plants, play a key role in the aspects of nutrient absorption of hosts and assisting the plants to cope with various biotic and abiotic stresses and the like, and are one of important trends of modern green agriculture development by applying the plant rhizosphere growth-promoting bacteria to improve the yield and the quality of crops. At present, the main bottleneck limiting the development of the bio-fertilizer industry is the instability of field application effect, the rejection and competition of indigenous microorganisms after the functional microorganisms in the fertilizer are applied to soil, and the stable exertion of the biological function of the microbial fertilizer is difficult to guarantee. Scientific research shows that the application of the compound microbial agent can enhance the exertion and stability of various biological functions of the microbial fertilizer. Can effectively improve the quality and the yield of crops and the disease resistance, thereby achieving the effects of losing weight and reducing drug consumption and being beneficial to realizing the intensive production and sustainable development of agriculture.

Tea trees mostly grow in warm and humid tropical and subtropical regions, and the climate of the regions is also favorable for breeding tea tree diseases. Tea cake diseases and alternaria leaf spot diseases are two important diseases of tea, are reported in tea planting areas all over the world, are commonly generated in tea areas in China, can cause great yield reduction of tea, reduce quality and seriously affect tea production. Wherein, the tea cake disease pathogenic bacteria are Exobasium vexans which are outside damage basidiomycetes, belong to obligate parasitic bacteria and can not be cultured in vitro, which brings difficulty to the research of the disease. At present, pseudomonas fluorescens Pf1 is reported to have a certain prevention and control effect on tea cake disease fields, but biocontrol bacteria such as Pseudomonas exist in a vegetative form, have no spores, cause short shelf life and have great difficulty in popularization and application, and in addition, bacillus subtilis B-9 is reported to have a certain antibacterial activity on tea cake disease pathogenic bacteria. At present, only one kind of polyoxin pesticide is registered in China for tea cake diseases.

The tea round spot disease is mainly caused by Pestalotiopsis spp, sanjay and the like separate Trichoderma harzianum (Trichoderma harzianum), gliocladium virena and Pseudomonas fluorescens (Pseudomonas fluorescens) from tea garden soil, the field control effect is below 40%, and the effect is not ideal. In addition, a certain control effect of bacillus belgii CY30 on tea round diseases is reported, and no registered medicament of tea round diseases exists at present.

Bacillus megaterium has been reported to have biocontrol effect on various germs at present, but the bacteriostasis principle is not particularly clear. At present, most reports show that only one kind of bacillus megaterium has two inhibition types on pathogenic bacteria, CN111793571A discloses a bacillus megaterium with a relatively larger antibacterial spectrum, which mainly has good inhibition rates on fungi, particularly fusarium oxysporum, penicillium, mucor and the like, and reaches more than 93%, and the inhibition rate on alternaria tenuissima is only 27%.

Aiming at the problems, the invention separates and screens a bacillus megaterium CY32 strain from tea tree rhizosphere soil, and the biocontrol bacterium has excellent prevention and control effects on tea cake diseases and alternaria leaf spot, and also has tea tree rhizosphere colonization ability and tea tree growth promoting and yield increasing effects. From the aspect of antibacterial effect, the inhibition rate of the bacterial strain specificity of the invention on the tea pseudodisc hairy cells (Pestalotiopsis theta) reaches 92.34 percent, while the inhibition rate on Fusarium oxysporum (Fusarium oxysporum) is only 21.68 percent, which indicates that the effective antibacterial substance of the bacterial strain provided by the invention is different from the secretion of Bacillus megaterium FJW1 in CN 111793571A.

The Bacillus velezensis SD120 and Bacillus megaterium CY32 are respectively obtained by separating from rhizosphere of rice and tea trees, the composite Bacillus is firstly reported to be applied to prevention and control of rice sheath blight and growth promotion and yield increase of rice, and the composite microbial agent has no interactive drug resistance with the existing bactericide. Because the plant extract is from the natural environment, the plant extract has the advantages of high efficiency, low toxicity, no environmental pollution, difficult generation of drug resistance and the like, and has wide application prospect.

Disclosure of Invention

The invention aims to provide composite Bacillus, which is Bacillus velezensis SD120 and Bacillus megaterium CY32, and the preservation numbers of the composite Bacillus are respectively CCTCC NO: M20211411 and CCTCC NO: M20211409. The composite bacillus can be used for promoting the growth and increasing the yield of rice and preventing and treating rice sheath blight disease.

The invention also aims to provide the application of the composite bacillus in rice cultivation.

In order to achieve the purpose, the invention adopts the following technical scheme to realize

A Bacillus composite bacterial agent comprises Bacillus velezensis SD120 and Bacillus megaterium CY32 with the preservation numbers of M20211411 and M20211409 respectively.

Preferably, the complex microbial inoculum is prepared by mixing the bacillus beleisi and the bacillus megaterium in an effective bacteria concentration ratio of 1.4-0.93.

The protection scope of the invention also includes the application of the complex microbial inoculum in rice cultivars, including the application in preventing and treating rice sheath blight disease or/and promoting rice growth.

The invention also provides the application of the composite bacterial agent in preparing bacteriostatic agents, wherein the bacteriostatic agents are inhibition targets of Pestalotiopsis pilosula (Pestalotiopsis theta), sclerotinia sclerotiorum (Sclerotinia sclerotiorum), rhizoctonia solani (Rhizoctonia solani), alternaria solani (Alternaria solani), colletotrichum gloeosporioides (Colletotrichum gloeosporioides), xanthomonas campestris (Xanthomonas campestris) and/or Vitis vinifera (Botrytis cinerea).

Compared with the prior art, the invention has the following advantages:

(1) The invention provides a compound microbial agent which is reported for the first time to be used for promoting growth and increasing yield of rice and preventing and treating sheath blight, and has no cross drug resistance with the existing sterilization.

(2) Compared with the existing chemical synthetic pesticide, the pesticide has the advantages of high efficiency, low toxicity, no environmental pollution, difficult generation of drug resistance and the like because of being from natural environment.

(3) Compared with a single strain, the composite bacillus obtained by the invention has synergistic effect in growth promotion and yield increase, and is particularly suitable for rice production.

(4) The bacillus megaterium provided by the invention has strong stress resistance, is easy to ferment in a large scale and has wide antibacterial spectrum.

(5) The bacillus megaterium provided by the invention has growth promoting activity on tea trees, can be colonized on the roots of the tea trees, is convenient to use, has no residue and pollution, and can effectively reduce the application of chemical fertilizers and pesticides.

Drawings

FIG. 1 colony morphology of SD120 and CY32 strains.

Fig. 2 is a schematic representation of the bacteriostatic activity of SD120 and CY32.

FIG. 3 is a schematic diagram of the growth promotion of rice by the composite microbial inoculum.

FIG. 4 is a schematic diagram of the compound bacterial agent for preventing and controlling rice sheath blight disease.

Detailed Description

In order to better explain the invention, the following embodiments further illustrate the main content of the invention, but the invention is not limited to the following embodiments. The technical solutions of the present invention, if not specifically mentioned, are conventional in the art, and the reagents or materials, if not specifically mentioned, are commercially available.

Example 1:

obtaining and identifying bacillus beleisi SD 120:

a separated bacterium is separated from rhizosphere soil of rice (shrimp rice No. I) in xi county in Hubei province, belongs to Bacillus velezensis (figure 1, table 1 and table 2) after being identified by 16s rDNA in combination with physiology and biochemistry, and is delivered to the China center for type culture collection for preservation in 2021, 11, 15 days, and classified and named: bacillus velezensis SD120; the preservation number is CCTCC NO: M20211411; a place: wuhan university in Wuhan, china.

In the present invention, bacillus belgii SD120 or simply SD120.

Morphological characteristics: the colonies were round and milky white (FIG. 1).

Physiological and biochemical characteristics of the strain:

TABLE 1 physiological and biochemical characteristics of strain SD 120-enzyme activity, carbon source oxidation

+: positive reaction; -: negative reaction;

TABLE 2 physiological and biochemical characteristics of the strain SD 120-production of acid by carbon source

+: carrying out positive reaction; -: negative reaction; w: weak positive reaction

Example 2:

acquisition and characterization of Bacillus megaterium CY 32:

the bacillus megaterium CY32 is separated from the rhizosphere soil of tea trees in Wangjiapo village in Enyao county of Hubei province (figure 1), the strain is further determined to be taxonomic status by 16s rDNA and physiological and biochemical identification (table 3 and table 4), and the strain is delivered to a China center for type culture collection for preservation at 11 and 15 days 2021, and is classified and named: bacillus megaterium (Bacillus megaterium) CY32; the preservation number is CCTCC NO:20211409; a place: china, wuhan university.

In the present invention, bacillus megaterium CY32 or simply CY32 is used.

Morphological characteristics: the colonies were round and milky white (FIG. 1).

Physiological and biochemical characteristics of the strain:

TABLE 3 physiological and biochemical characteristics of Strain CY 32-enzyme Activity, carbon Source Oxidation

+: positive reaction; -: negative reaction;

TABLE 4 physiological and biochemical characteristics of Strain CY 32-production of acid Using a carbon Source

+: positive reaction; -: negative reaction;

example 3:

fermentation of bacillus beleisi SD120 (the percentages in the following culture medium formula are mass fractions):

1) First-stage seed culture: 100ml of first-stage seed culture medium is filled in a 500ml triangular flask, moist heat sterilization is carried out for 15-30min at 121 ℃, SD-120 freeze-dried tube strains are inoculated in the first-stage seed culture medium, and shaking culture is carried out for 10h at 35 ℃ and 180 rpm; the raw materials and the dosage of the culture medium used for first-level seed culture are as follows: 1% of glucose, 0.5% of beef extract, 2% of peptone, 0.8% of sodium chloride and 7% of the pH value of a culture medium;

2) Secondary seed culture: 200L of secondary seed culture medium is filled in a 500L fermentation tank, moist heat sterilization is carried out for 15-30min at 120 ℃, and 200ml of primary seeds are inoculated in the secondary seed culture medium; culturing at 35 deg.C for 10 hr; controlling the tank pressure to be 0.05Mpa, the stirring speed to be 200rpm, the aeration ratio to be 1, and the raw materials and the dosage of the culture medium used for the second-stage seed culture are as follows: glucose 01%, yeast extract 2%, peptone 1%, potassium dihydrogen phosphate 0.003%, magnesium sulfate 0.02%, and culture medium pH7;

3) Fermentation: 5 tons of SD-120 fermentation medium is filled in a 10 ton fermentation tank, moist heat sterilization is carried out for 20-30min at the temperature of 121 ℃, 200LL of secondary seed liquid is transplanted into the fermentation medium, the tank pressure is controlled to be 0.05Mpa, the stirring speed is 150rpm, the aeration ratio is 1, and the culture is carried out for 30-36h at the temperature of 28-35 ℃; the raw materials and the dosage of the culture medium used for fermentation are as follows: 1.0% of corn starch, 0.5% of sucrose, 0.5% of fish peptone, 2.0% of soybean meal, 0.010% of potassium dihydrogen phosphate, 0.03% of magnesium sulfate, 0.10% of calcium carbonate and the pH value of a culture medium of 7;

4) Ending fermentation when spores fall off by 20-40%. The number of spores in the obtained fermentation broth was about 140 hundred million cfu/mL, and it was used in the following examples.

Fermentation of bacillus megatherium CY32 (the percentages in the following culture medium formulas are mass fractions):

1) First-stage seed culture: placing 100ml of first-stage seed culture medium in 500ml triangular flask, performing moist heat sterilization at 121 deg.C for 15-30min, inoculating strain of CY32 lyophilized tube in the first-stage seed culture medium, and shake culturing at 35 deg.C and 180rpm for 10 hr; the raw materials and the dosage of the culture medium used for first-level seed culture are as follows: 3% of glucose, 1.5% of beef extract, 0.8% of peptone, 0.5% of sodium chloride and 7% of culture medium pH;

2) Secondary seed culture: 200L of secondary seed culture medium is filled in a 500L fermentation tank, moist heat sterilization is carried out for 15-30min at 121 ℃, and 200ml of primary seeds are inoculated in the secondary seed culture medium; culturing at 35 deg.C for 10 hr; controlling the tank pressure to be 0.05Mpa, the stirring speed to be 200rpm, the aeration ratio to be 1.5, and the raw materials and the dosage of a culture medium used for culturing the second-stage seeds as follows: 0.5% of glucose, 1% of yeast extract, 3% of peptone, 0.001% of potassium dihydrogen phosphate, 0.01% of magnesium sulfate and pH7 of a culture medium;

3) And (3) fermentation: 6 tons of CY32 fermentation medium is filled in a 10 ton fermentation tank, moist heat sterilization is carried out for 30min at 121 ℃, 200L of secondary seed liquid is transferred into the fermentation medium, the tank pressure is controlled to be 0.02Mpa, the stirring speed is 150rpm, the aeration ratio is 0.5-1.0, and the culture is carried out for 24h at 35 ℃; the raw materials and the dosage of the culture medium used for fermentation are as follows: corn flour 2.0%, molasses 1.0%, peanut meal 1.5%, yeast extract 1.5%, monopotassium phosphate 0.015%, magnesium sulfate 0.04%, calcium carbonate 0.15%, and culture medium pH7;

4) And (3) stopping fermentation when the spores fall off by 20-40%, and obtaining fermentation liquor with 50 hundred million cfu/mL of spores after the spores are put into a tank. Used in the following examples.

Example 4:

in vitro bacteriostatic activity of bacillus megaterium CY 32:

the test tea leaf roller spot (Pestalotiopsis theta) was isolated from tea leaf roller spot disease leaves and stored on PDA slants at 4 ℃. Other pathogenic fungi are anthracnose (Colletotrichum gloeosporioides), sclerotinia sclerotiorum (Sclerotinia sclerotiorum), botrytis cinerea (Botrytis cinerea), rhizoctonia solani (Rhizoctonia solani), fusarium solani (Alternaria solani), fusarium solani (Fusarium solani) and Fusarium oxysporum (Fusarium oxysporum), both of which are stored at 4 ℃ on PDA slant, and Humicola melongena (Pythium hanidermatum) is stored at 10 ℃ on PDA slant.

The slant strain is transferred to PDA plate for activation, and cultured at 30 deg.C for 6 d. The sterilized filter paper sheets were placed on both ends of the PDA plate, and then 7. Mu.L of CY32 fermentation broth was dropped. And after 24 hours, inoculating the pathogenic fungus bacterial dishes of the fungal diseases by using a 4mm puncher, and inoculating sterile water as a blank control, wherein the distance between the pathogenic bacteria and the filter paper sheets is 25mm. Each time is set to be repeated for three times in the test, the diameter of each treated colony and the diameter of each control colony are counted after the plate is overgrown with a control, and the bacteriostasis rate is calculated.

Bacteriostasis rate = [ (control colony diameter-treated colony diameter)/(control colony diameter-cake diameter) ] × 100%

After the monascus campestris, which is a pathogenic bacterium of bacterial disease, is obtained by streaking from a glycerin tube, the monascus campestris is transferred to an NB liquid culture medium shaking table for shaking culture at the temperature of 37 ℃ at 180r/min for 48h for later use. Melting the NA culture medium, pouring the medium into a flat plate at about 45 ℃, then adding the xanthomonas campestris bacterial liquid, wherein the ratio of NA to bacterial liquid is 50. And then punching a bacterium-carrying plate by using a sterilized Oxford cup, adding 200 microliter CY32 fermentation liquor into the punched holes, and culturing at 37 ℃ for 48 hours to observe whether a bacteriostatic zone is generated.

In-vitro bacteriostatic tests show that the CY32 has higher bacteriostatic activity on tea pseudoplectania pilosula, sclerotinia sclerotiorum, colletotrichum gloeosporioides, botrytis cinerea, rhizoctonia solani and solanaceous cells, wherein the bacteriostatic activity is over 50 percent, and the bacteriostatic activity on tea pseudoplectania exsiceracus pathogenic bacteria on tea pseudoplectania is highest. Has good bacteriostatic activity on pathogenic bacteria of Xanthomonas campestris, and has an obvious bacteriostatic circle. Has poor bacteriostatic activity on pythium aphanidermatum, fusarium solani and fusarium oxysporum. (Table 5).

TABLE 5 bacteriostatic activity of CY32 against pathogenic bacteria

Activating tea leaf spot bacteria (Pestalotiopsis theta) to a PDA plate for 5d for later use, and collecting tea leaves (Zhongcha 108) which are not used with bactericides and have consistent sizes for in vitro leaf tests. CY32 fermentation broth with a spore count of about 50 hundred million cfu mL was prepared as in example 3 ^-1 The fermentation broth was diluted 10 and 20 times with sterile water, respectively, for use. And uniformly spraying the fermentation liquor on the tea leaves by using an electric sprayer, wherein each leaf is 2mL, and spraying sterile water for blank control. After each treatment, air-drying, inoculating tea wheel spot fungus cakes by using a needle-prick inoculation method, carrying out moisture-keeping culture at 28 ℃ for 12d, counting the diameters of control and treatment scabs, calculating the control effect, repeating each treatment for 3 times, repeating each treatment for 15 leaves, and multiplying the control effect by 100 (the diameter of the control scab, the diameter of the treatment scab and the diameter of the control scab).

Experiments show that the bacillus megaterium CY32 has good prevention effect on tea round spot, the diameters of the disease spots after 10 times and 20 times of fermentation liquor treatment are obviously lower than the reference diameter, and the prevention effect is 76.88 percent and 56.38 percent respectively.

TABLE 6 prevention and treatment effects of CY32 fermentation broth on tea leaf roller disease

Treatment of	Diameter of scab (mm)	Control effect (%)
			CY32 times fermentation liquor	6.25	76.88
CY32 times fermentation liquor	11.79	56.38
			Control of	27.03	-

Example 5:

growth promoting and yield increasing effects of bacillus megatherium CY32 on tea trees

The test field is located in the township of Anshi Hufeng county in Hubei province, CY32 fermentation stock solution (50 hundred million cfu. ML-1) is diluted by 20 times, the tea trees are subjected to root irrigation, the water consumption per mu is 600 jin, and clear water is irrigated in contrast. Once on 7 days, three times in total. And (4) counting the germination density at the two-leaf stage of the bud after 20 days, investigating the germination density (in a box of 33.3cm multiplied by 33.3 cm), and measuring the weight of the bud.

Tests show that CY32 can obviously improve the germination density of tea trees, the weight of hundreds of buds is reduced, but the weight of one bud and two leaves in a unit area is increased, and the yield is obviously increased (Table 7).

TABLE 7 growth promoting and yield increasing effects of CY32 on tea tree

Treatment of	Germination density (volume)	Baiya weight (g)
			CY32	187.05	39.17
CK	127.41	44.63

Example 6:

bacillus megaterium CY32 colonization ability in tea tree rhizosphere soil

The single colony separated from bacillus megaterium CY32 and commercial bacillus megaterium bacterial manure is subjected to resistance screening in a rifampicin culture medium containing different concentrations to obtain rifampicin resistant mutant strain (the strain has rifampicin resistance through detection, and other physiological and biochemical characteristics have no significant difference with those of a primary strain), and the strain can contain 300 mu g/mL ^-1 Normal growth in LB of rifampicin.

Resistant mutant CY32 and a single bacillus megaterium sold in the market are fermented according to the example 2, the number of spores of 2 kinds of fermentation liquor is adjusted to 1 hundred million cfu/mL by using clear water, and the fermentation liquor is sprayed to the root of a tea tree at the application rate of 2L per plant. 30 days later, obtaining rhizosphere soil by shaking-off method, diluting by gradient dilution method, and coating on the surface of the rhizosphere soil containing 300 μ g/mL ^-1 The number of the rifampicin in the LB plate was measured after culturing at 37 ℃ for 24 hours, and the ability of CY32 and commercially available Bacillus megaterium to colonize the rhizosphere soil of tea was determined.

Experiments show that CY32 has stronger colonization ability in the rhizosphere soil of tea trees, and the colonization amount is 3.85 multiplied by 10 ⁶ cfu/g, whereas the commercial Bacillus megaterium is only 5.19X 10 ⁴ cfu/g。’

Example 7:

growth promoting and yield increasing effect of composite bacillus on rice

The SD120 and CY32 fermentation liquids prepared in example 3 are mixed in an effective concentration ratio of 1 to obtain composite bacillus (the effective bacteria concentration is 25 hundred million cfu/mL) for later use.

After accelerating germination, sowing the rice seeds in a 72-hole tray, wherein the following grass carbon in a tray matrix: vermiculite: perlite =3 (volume ratio), and 20 mL/plant of rhizosphere agent is irrigated after rice emergence.

Treatment 1: SD120 fermentation broth (50 hundred million cfu/mL); and (3) treatment 2: treating a composite microbial inoculum fermentation liquor stock solution (50 hundred million cfu/mL) by a treatment method of 3: clear water control, treatment 4: CY32 fermentation broth stock (50 hundred million cfu/mL). And (4) performing conventional management under a greenhouse condition, and counting the plant height, root length and fresh weight of each treatment after 20 days. Each treatment was repeated 3 times, and each was replicated 24 seedlings.

The test result shows that the growth promoting effect of the composite microbial inoculum is better than that of a single strain (Table 8, figure 3).

The field yield increase test is located in Hubei Zhijiang city, the rice variety is 'shrimp rice number one', the test is carried out by conventional fertilization management, the microbial inoculum is sprayed to the stem base after the rice is transplanted for 14 days, and the microbial inoculum is sprayed for the second time after 15 days. Treatment 1: SD120 fermentation broth (50 hundred million cfu/mL) was diluted 200-fold, run 2: diluting the complex microbial inoculum fermentation liquor SD120 fermentation liquor (50 hundred million cfu/mL) by 200 times, and treating the mixture by a reaction condition of 3: clear water control, treatment 4: CY32 fermentation broth SD120 fermentation broth (50 hundred million cfu/mL) was diluted 200-fold. The amount of the microbial inoculum is 20L/mu, each treatment is repeated for 3 times, and each repetition is 100m ² And (4) performing conventional management, and performing statistics on yield after harvesting rice. Test results show that under the condition that the total bacteria concentration is the same, the composite microbial inoculum has an obvious yield increase effect, and the yield increase effect is better than that of a single bacterial strain (table 8 and figure 3).

TABLE 8 growth promoting and yield increasing effects of the complex microbial inoculum

Treatment of	Plant height (cm)	Root length (cm)	Fresh weight (g)	Yield (kg)
					SD120	53.42	12.37	3.23	611.93
CY32	52.42	12.70	3.10	607.35
					Complex microbial inoculum	58.24	14.82	3.79	673.17
Control	40.93	17.71	1.82	530.80

Example 3:

SD120 and CY32 have bacteriostatic activity on pathogenic bacteria of rice sheath blight disease and the control effect of compound fungicide on rice sheath blight disease

The sterilized filter paper sheets were placed on both ends of the PDA plate, and then 7. Mu.L of SD120 fermentation broth was dropped. And after 24 hours, inoculating the pathogenic bacteria of the rice sheath blight into the bacterial plate by using a 4mm puncher, and inoculating sterile water as a blank control, wherein the distance between the pathogenic bacteria and the filter paper is 25mm. After the control full-plate is provided with the control, the diameters of the colonies of each treatment and the control are counted, the bacteriostatic rate is calculated, and the CY32 bacteriostatic activity is determined in the same way as SD120.

Bacteriostatic rate = [ (control colony diameter-treated colony diameter)/(control colony diameter-cake diameter) ] × 100%

In-vitro bacteriostatic tests show that SD120 and CY32 have good bacteriostatic activity on pathogenic bacteria of rice sheath blight disease and have obvious bacteriostatic bands (figure 2), and the SD120 bacteriostatic rate is 48.74%.

The method for determining the prevention effect of the compound microbial inoculum on the rice sheath blight disease adopts a broad bean leaf method, the compound microbial inoculum in the embodiment 7 is diluted by 20 times, an electric sprayer is used for uniformly spraying the compound microbial inoculum on the surface of the broad bean leaves, clear water is sprayed in a contrast mode, a pathogenic bacterium dish (a 4mm puncher is used for punching) of the rice sheath blight disease is inoculated after the leaves are naturally dried in the air, the culture is carried out in a moisturizing mode, the contrast and treatment disease index are counted after the contrast is fully used for preventing diseases, and the prevention effect is calculated. Each treatment was repeated 3 times, 16 leaves per repeat. Disease index grading criteria were as follows: level 0: no lesion, grade 1: lesions account for less than 20% of the leaf area, grade 2: the lesion spots account for 20-50% of the leaf area, and the disease spots are classified into 3: the disease spots account for 50% -80% of the leaf area, and the disease spots are classified as 4: the lesion spots account for more than 80% of the leaf area.

Disease index = (number of leaves at each stage × stage)/(total number of leaves investigated × highest representative stage) × 100.

Control effect = (control disease index-treatment disease index)/control disease index × 100%

The broad bean leaf method test shows that the compound microbial inoculum diluted by 20 times has good prevention and control effects on rice sheath blight disease, and the prevention effect reaches 98.47 percent (figure 4).

Claims (4)

1. A composite bacterial preparation of Bacillus is Bacillus belgii ((B))Bacillus velezensis) And Bacillus megaterium (A), (B)Bacillus megaterium) The preservation number of the Bacillus beleisi is M20211411, and the preservation number of the Bacillus megaterium is M20211409.

2. The complex microbial inoculum according to claim 1, wherein the bacillus belgii and the bacillus megaterium are mixed according to an effective bacterial concentration of 1.

3. The application of the composite bacterial agent of claim 1 in preventing and treating rice sheath blight disease.

4. The use of the complex bacterial agent of claim 1 for promoting the growth of rice.

Images