Composition for preventing and treating soil-borne diseases of crops and preparation method thereof

Abstract

The invention relates to the technical field of crop disease prevention and treatment, in particular to a composition for preventing and treating crop soil-borne diseases and a preparation method thereof.The preparation method comprises the steps that strains are subjected to activation culture and fermentation culture respectively, and a microbial agent mixed solution is obtained; performing high-temperature carbonization on corn straws to obtain biochar, and adding the biochar into the fungicide mixed solution to obtain biochar powder adsorbed and fixed with strains; uniformly mixing biochar powder with a polyvinyl alcohol solution to obtain a strain suspension; dropwise adding the strain suspension into a calcium chloride solution to obtain biochar-based composite strain microspheres; preparing a chitosan / poly (N-isopropylacrylamide) solution, judging whether the preparation of the mixed solution meets a preset standard or not according to a light transmittance difference value of the mixed solution, and transferring the biochar-based composite strain microspheres into the chitosan / poly (N-isopropylacrylamide) solution for coating to obtain the temperature-sensitive composite microbial agent microspheres. The environmental adaptability of the composition for preventing and treating the soil-borne diseases of the crops is improved.

Description

Technical Field

[0001] The invention relates to the technical field of crop disease prevention and treatment, and in particular to a composition for preventing and treating soil-borne diseases of crops and a preparation method thereof. Background Art

[0002] Soil-borne diseases refer to diseases caused by pathogens such as fungi, bacteria, nematodes and viruses that live in the soil with diseased remains and attack crops from the roots or stems when conditions are right.

[0003] A compound bacterial agent for soil-borne diseases is a microbial preparation used to prevent and control soil-borne diseases. It is usually made of two or more non-antagonistic microbial species. These species can not only cooperate with each other in the soil, but also improve soil structure, increase soil fertility and promote crop growth.

[0004] Chinese Patent Publication No.: CN111357771B discloses a biocontrol agent for preventing and controlling soil-borne diseases, which is prepared from the following raw materials in weight ratio: Sargassum, staghorn, chlorella, eucheuma, Ulva pertusa, rhodiola rosea root, Bacillus amyloliquefaciens HAB-2, Bacillus subtilis, Trichoderma acanthosporum, yeast and Chaetomium aureum. The present invention can effectively prevent and control soil-borne diseases, improve soil quality and soil microbial composition, greatly improve the growth of field crops, and promote increased production and income. It can prevent and control soil-borne diseases such as cucumber wilt, strawberry anthracnose and rice blast, which is of great significance to the sustainable development of agricultural production. It can be seen that in the above technical scheme, the outer layer of the biocontrol agent has no protective film and is easily disturbed by soil temperature. The environmental adaptability of the biocontrol agent is poor, and the effect of preventing and controlling soil-borne diseases of crops is poor, resulting in low crop yields. Summary of the invention

[0005] To this end, the present invention provides a composition for preventing and controlling soil-borne diseases of crops and a preparation method thereof, so as to overcome the problem in the prior art that the outer layer of the composite bacterial agent has no protective film and is easily disturbed by the soil temperature, the environmental adaptability of the biocontrol bacterial preparation is poor, the effect of preventing and controlling soil-borne diseases of crops is poor, and the crop yield is low.

[0006] To achieve the above object, on the one hand, the present invention provides a method for preparing a composition for preventing and controlling soil-borne diseases of crops, comprising:

[0007] inoculating Bacillus subtilis and Bacillus amyloliquefaciens into two activation culture media for cultivation respectively, to obtain a first seed culture solution and a second seed culture solution respectively;

[0008] Fermenting the first seed culture solution and the second seed culture solution to obtain a first fermentation culture solution and a second fermentation culture solution respectively;

[0009] The first fermentation bacterial liquid and the second fermentation bacterial liquid are filtered and impurities are removed to obtain a first bacterial stock solution and a second bacterial stock solution, and the mixture is mixed in proportion to obtain a bacterial agent mixed solution;

[0010] The corn stalks are carbonized at high temperature and then ground into biochar by a ball mill; the biochar is added to the bacterial agent mixed solution, and the precipitate after separation treatment of the bacterial agent mixed solution is vacuum dried to obtain biochar powder with the Bacillus subtilis and the Bacillus amyloliquefaciens adsorbed and fixed thereon;

[0011] The biochar powder is mixed with a polyvinyl alcohol solution to obtain a bacterial suspension, and the suspension is added dropwise to a calcium chloride solution to obtain biochar-based composite bacterial microspheres;

[0012] At room temperature, weigh chitosan powder and add it to a 2% acetic acid solution, stir and stand to prepare a chitosan solution with a concentration of 4%, and obtain the viscosity of the chitosan solution;

[0013] dissolving poly(N-isopropylacrylamide) in deionized water at room temperature, adding an initiator and a cross-linking agent to perform a free radical polymerization reaction, stirring to obtain a poly(N-isopropylacrylamide) solution, and obtaining the viscosity of the poly(N-isopropylacrylamide) solution;

[0014] At room temperature, pouring the chitosan solution into the poly(N-isopropylacrylamide) solution at a preset pouring speed, stirring for a preset time and continuously acquiring the transmittance of the mixed solution to determine the time when the transmittance stops changing;

[0015] When it is determined according to the transmittance difference of the mixed solution that the preparation of the mixed solution does not meet the preset standard, the preset pouring speed is reduced, or, according to the uniform characteristic value of the solution, the stirring speed during the preparation of the mixed solution is reduced or the mixed solution is filtered to obtain a chitosan / poly (N-isopropylacrylamide) solution;

[0016] The biochar-based composite bacterial microspheres are transferred to a chitosan / poly (N-isopropylacrylamide) solution for coating, filtered, separated, washed, and then vacuum dried to obtain thermosensitive composite bacterial agent microspheres.

[0017] Furthermore, the activation culture conditions of the Bacillus subtilis and the Bacillus amyloliquefaciens are that the pH of the culture medium is set to 7.4, the temperature is 37° C., the culture is carried out for 18 hours, and the shaking speed is 180 r / min.

[0018] Furthermore, the weight ratio of the activation culture medium is 20% potato, 4% glucose, 0.5% beef extract, 2% peptone, 2% sodium chloride, 1.5% agar, and the balance is water.

[0019] Furthermore, the fermentation culture process of Bacillus subtilis and Bacillus amyloliquefaciens includes: under sterile conditions, inoculating the first seed culture solution and the second seed culture solution into two fermentation tanks respectively, with the inoculation amount of 4%; the components of the two fermentation culture media are the same, and the mass content of each component in 1L of distilled water is: 2% soybean meal, 0.5% urea, 0.2% ammonium sulfate, 4% starch, 5% molasses, 0.8% potassium dihydrogen phosphate, 0.2% disodium hydrogen phosphate, 0.01% magnesium sulfate, the stirring speed is 240r / min, the culture temperature is 30°C to 35°C, the ventilation volume is 1:0.8, and the fermentation time is 24h to 30h.

[0020] Furthermore, the process of obtaining the viscosity of the chitosan solution and the viscosity of the poly(N-isopropylacrylamide) solution comprises:

[0021] The chitosan solution and the poly (N-isopropylacrylamide) solution were placed in a constant temperature water bath respectively, and the water bath temperature was adjusted to room temperature and kept constant;

[0022] Slowly immersing the rotor of the first rotational viscometer and the rotor of the second rotational viscometer into the chitosan solution and the poly(N-isopropylacrylamide) solution, respectively;

[0023] Start the rotational viscometer and record the torque value of the rotor at the preset speed;

[0024] Viscosity is the ratio of the product of the rotational viscometer constant and torque to the angular velocity;

[0025] Repeat the measurement several times to calculate the average value of the viscosity of the chitosan solution and the average value of the viscosity of the poly(N-isopropylacrylamide) solution;

[0026] The average value of the viscosity of the chitosan solution is recorded as the viscosity of the chitosan solution; the average value of the viscosity of the poly(N-isopropylacrylamide) solution is recorded as the viscosity of the poly(N-isopropylacrylamide) solution.

[0027] Furthermore, the process of determining, based on the transmittance difference of the mixed solution, that the preparation of the mixed solution does not meet the preset standard comprises:

[0028] At room temperature, the timing starts when the chitosan solution is poured into the poly(N-isopropylacrylamide) solution at a preset pouring speed;

[0029] Obtaining the initial transmittance of the mixed solution by a transmission spectrometer;

[0030] When the transmittance of the mixed solution stops changing, stop timing, and obtain the time from the start of timing to the time when the transmittance of the mixed solution stops changing;

[0031] Calculating the transmittance difference of the mixed solution;

[0032] Comparing the transmittance difference of the mixed solution with the first preset transmittance difference and the second preset transmittance difference respectively;

[0033] If the transmittance difference of the mixed solution is less than the first preset transmittance difference, it is determined that the preparation of the mixed solution does not meet the preset standard, and the preset pouring speed is reduced according to the ratio between the first preset transmittance difference and the transmittance difference of the mixed solution;

[0034] If the transmittance difference of the mixed solution is greater than or equal to the first preset transmittance difference and less than the second preset transmittance difference, it is determined that the preparation of the mixed solution does not meet the preset standard, and a second determination is made based on the uniform characteristic value of the solution whether the preparation of the mixed solution meets the preset standard.

[0035] Furthermore, the solution uniformity characteristic value is determined based on the viscosity of the chitosan solution, the viscosity of the poly (N-isopropylacrylamide) solution, and the time it takes for the transmittance of the mixed solution to reach stability.

[0036] Furthermore, the process of secondarily determining whether the preparation of the mixed solution meets a preset standard according to the uniform characteristic value of the solution includes:

[0037] Comparing the uniform characteristic value of the solution with a preset uniform characteristic value of the solution;

[0038] If the uniform characteristic value of the solution is less than the preset uniform characteristic value of the solution, it is determined that the preparation of the mixed solution meets the preset standard, and the mixed solution meeting the preset standard is filtered to obtain a chitosan / poly (N-isopropylacrylamide) solution;

[0039] If the solution uniformity characteristic value is greater than or equal to the preset solution uniformity characteristic value, it is determined that the preparation of the mixed solution does not meet the preset standard, and the stirring speed during the preparation of the mixed solution is reduced according to the difference between the solution uniformity characteristic value and the preset solution uniformity characteristic value.

[0040] Furthermore, several speed reduction methods are provided for reducing the stirring speed during the preparation of the mixed solution, and each speed reduction method has a different reduction range for the stirring speed during the preparation of the mixed solution.

[0041] On the other hand, the present invention also provides a composition for preventing and controlling soil-borne diseases of crops, wherein the composition is composed of the following raw materials: biochar, Bacillus subtilis, Bacillus amyloliquefaciens, polyvinyl alcohol, chitosan and poly (N-isopropylacrylamide).

[0042] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention activates and ferments the Bacillus subtilis and Bacillus amyloliquefaciens flora respectively, mixes the bacterial stock solutions to obtain a bacterial agent mixed solution, uses biochar to adsorb and solidify the composite bacterial species to improve the survival rate of the bacterial species, forms biochar-based composite bacterial species microspheres through a polyvinyl alcohol solution, and finally transfers the biochar-based composite bacterial species microspheres to a chitosan / poly (N-isopropylacrylamide) solution for coating, thereby providing a protective layer for the biochar-based composite bacterial species microspheres, protecting the activity of the bacterial species, and improving the environmental adaptability of the composite bacterial agent.

[0043] Furthermore, the present invention has a control effect on various soil-borne diseases by formulating a composite bacterial agent including Bacillus subtilis and Bacillus amyloliquefaciens, thereby improving the utilization rate of the composition.

[0044] Furthermore, the present invention grinds the corn stalks in a ball mill after carbonization to increase the specific surface area of ​​the biochar, thereby improving the adsorption capacity of the biochar.

[0045] Furthermore, the present invention utilizes biochar as a composite bacterial strain carrier, which not only allows the bacterial strain to be adsorbed and fixed through the porous structure of the biochar but also provides nutrients and a living environment for the bacterial strain, thereby improving the stability of the bacterial strain.

[0046] Furthermore, the present invention ensures the eligibility of the mixed solution by determining whether the preparation of the mixed solution meets the preset standard according to the transmittance difference of the mixed solution.

[0047] Furthermore, the present invention provides an evaluation standard for the preparation of a mixed solution by setting a solution uniformity characteristic value, thereby improving the scientific nature of the preparation process of the mixed solution.

[0048] Furthermore, the present invention secondarily determines whether the preparation of the mixed solution meets a preset standard based on the uniform characteristic value of the solution, thereby improving the reliability of the mixed solution preparation process.

[0049] Furthermore, the present invention combines biochar-based composite bacterial microspheres with chitosan / poly (N-isopropylacrylamide) solution to prepare thermosensitive composite bacterial agent microspheres, which can release bacteria only under specific temperature conditions to achieve precise prevention and control, thereby improving the prevention and control effect of the composition. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 This is a flow chart of a method for preparing a composition for preventing and controlling soil-borne diseases of crops according to an embodiment of the present invention;

[0051] Figure 2 A flow chart of determining whether the preparation of the mixed solution meets a preset standard according to an embodiment of the present invention;

[0052] Figure 3 A flow chart of a second determination of whether the preparation of the mixed solution meets a preset standard according to an embodiment of the present invention;

[0053] Figure 4 The present invention is a flowchart of determining a method for reducing the stirring speed during the preparation of the mixed solution according to an embodiment of the present invention. DETAILED DESCRIPTION

[0054] In order to make the objects and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0055] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0056] See also Figure 1 , Figure 2 , Figure 3 as well as Figure 4 As shown, they are respectively a flow chart of a method for preparing a composition for preventing and controlling soil-borne diseases of crops according to an embodiment of the present invention; a flow chart of determining whether the preparation of the mixed solution meets a preset standard according to an embodiment of the present invention; a flow chart of determining whether the preparation of the mixed solution meets a preset standard for a second time according to an embodiment of the present invention; and a flow chart of determining a method for reducing the stirring speed during the preparation of the mixed solution according to an embodiment of the present invention.

[0057] The embodiment of the present invention provides a method for preparing a composition for preventing and controlling soil-borne diseases of crops, comprising:

[0058] Step S1, inoculating Bacillus subtilis and Bacillus amyloliquefaciens into two activation culture media for shaking culture, respectively, to obtain a first seed culture solution and a second seed culture solution;

[0059] Step S2, inoculating the first seed culture liquid and the second seed culture liquid into two fermentation mediums under sterile conditions for fermentation culture, so that the number of viable bacteria in the fermentation liquid of each strain reaches the standard, thereby obtaining a first fermentation liquid and a second fermentation liquid respectively;

[0060] Step S3, filtering and removing impurities from the first fermentation bacterial liquid and the second fermentation bacterial liquid to obtain a first bacterial stock solution and a second bacterial stock solution respectively; mixing the first bacterial stock solution and the second bacterial stock solution in a ratio of 1:1 to obtain a bacterial agent mixed solution;

[0061] Step S4, carbonizing the corn stalks at high temperature and then grinding them in a ball mill to form biochar; adding the biochar to the bacterial agent mixture, shaking on a shaker, standing, and centrifuging, and vacuum drying the precipitate obtained by centrifugation to obtain biochar powder with the Bacillus subtilis and the Bacillus amyloliquefaciens adsorbed and fixed thereon;

[0062] Step S5, uniformly mixing the biochar powder on which the Bacillus subtilis and the Bacillus amyloliquefaciens are adsorbed and fixed with a polyvinyl alcohol solution to obtain a bacterial suspension; dropwise adding the bacterial suspension into a calcium chloride solution, cross-linking and curing for 24 hours, filtering and separating to obtain biochar-based composite bacterial microspheres;

[0063] Step S6, weighing 4 g of chitosan powder and pouring it into 100 ml of 2% acetic acid solution at room temperature, stirring evenly, and preparing a chitosan solution with a concentration of 4% after standing, and obtaining the viscosity of the chitosan solution;

[0064] Step S7, dissolving poly(N-isopropylacrylamide) in deionized water at room temperature, adding an initiator and a cross-linking agent, performing a free radical polymerization reaction at 65° C. under nitrogen protection, stirring evenly to obtain a poly(N-isopropylacrylamide) solution, and obtaining the viscosity of the poly(N-isopropylacrylamide) solution;

[0065] Step S8, pouring the chitosan solution into the poly(N-isopropylacrylamide) solution at room temperature at a preset pouring speed of 10 ml / min, stirring for a preset time of 45 min and continuously acquiring the transmittance of the mixed solution to determine the time when the transmittance stops changing;

[0066] Step S9, when it is determined according to the transmittance difference of the mixed solution that the preparation of the mixed solution does not meet the preset standard, the preset pouring speed is reduced, or, according to the uniform characteristic value of the solution, the stirring speed during the preparation of the mixed solution is reduced or the mixed solution is filtered to obtain a chitosan / poly (N-isopropylacrylamide) solution;

[0067] Step S10, transferring the biochar-based composite bacterial microspheres to a chitosan / poly (N-isopropylacrylamide) solution for coating, filtering, separating, washing, and vacuum drying to obtain temperature-sensitive composite bacterial agent microspheres.

[0068] In this embodiment, the molar ratio of chitosan to N-isopropylacrylamide is 1:0.25.

[0069] In this embodiment, the initiator may be potassium persulfate or ammonium persulfate; and the cross-linking agent may be N,N'-methylenebisacrylamide.

[0070] In this embodiment, the viable bacterial count of each strain fermentation broth reached the standard range of 4×108 cfu / g-5×10 8 cfu / g.

[0071] In this embodiment, the preset time is selected within the range of [30min, 42min].

[0072] Specifically, the activation culture conditions of the Bacillus subtilis and the Bacillus amyloliquefaciens are that the pH of the culture medium is set to 7.4, the temperature is 37° C., the culture is carried out for 18 hours, and the shaking speed is 180 r / min.

[0073] Specifically, the total number of viable bacteria in the bacterial agent mixture is not less than 3×10 8 cfu / g.

[0074] Specifically, the weight ratio of the activation culture medium is 20% potato, 4% glucose, 0.5% beef extract, 2% peptone, 2% sodium chloride, 1.5% agar, and the balance is water.

[0075] Specifically, the fermentation and cultivation process of Bacillus subtilis and Bacillus amyloliquefaciens comprises: under sterile conditions, inoculating the first seed culture solution and the second seed culture solution into two fermentation tanks respectively, with the inoculation amount of both being 4%, the components of the two fermentation culture media being the same, and the mass content of each component in 1L of distilled water being: 2% soybean meal, 0.5% urea, 0.2% ammonium sulfate, 4% starch, 5% molasses, 0.8% potassium dihydrogen phosphate, 0.2% disodium hydrogen phosphate, and 0.01% magnesium sulfate, the stirring speed being 240r / min, the culture temperature being 30°C to 35°C, the ventilation volume being 1:0.8, and the fermentation time being 24h to 30h.

[0076] Specifically, the process of obtaining the viscosity of the chitosan solution and the viscosity of the poly(N-isopropylacrylamide) solution includes:

[0077] Step S701, placing the chitosan solution and the poly (N-isopropylacrylamide) solution in a constant temperature water bath respectively, adjusting the water bath temperature to room temperature, and maintaining the constant temperature;

[0078] Step S702, slowly immersing the rotor of the first rotational viscometer and the rotor of the second rotational viscometer into the chitosan solution and the poly (N-isopropylacrylamide) solution respectively to avoid generating bubbles;

[0079] Step S703, start the rotational viscometer and record the torque value of the rotor at a preset speed of 30 r / min;

[0080] Step S704, viscosity is the ratio of the product of the rotational viscometer constant and the torque to the angular velocity;

[0081] Step S705, repeating the measurement several times to calculate the average value of the viscosity of the chitosan solution and the average value of the viscosity of the poly (N-isopropylacrylamide) solution;

[0082] Step S706, recording the average value of the viscosity of the chitosan solution as the viscosity of the chitosan solution; recording the average value of the viscosity of the poly(N-isopropylacrylamide) solution as the viscosity of the poly(N-isopropylacrylamide) solution.

[0083] Specifically, the process of determining, according to the transmittance difference of the mixed solution, that the preparation of the mixed solution does not meet the preset standard includes:

[0084] At room temperature, the timing starts when the chitosan solution is poured into the poly(N-isopropylacrylamide) solution at a preset pouring speed;

[0085] Obtaining the transmittance of the mixed solution by a transmission spectrometer;

[0086] When the transmittance of the mixed solution stops changing, the timing is stopped, and the time from the start of the timing to the transmittance of the mixed solution reaching stability is obtained;

[0087] The absolute value of the difference between the transmittance of the mixed solution when the transmittance stops changing and the transmittance of the mixed solution when it starts changing is recorded as the transmittance difference of the mixed solution;

[0088] Calculating the transmittance difference of the mixed solution;

[0089] The transmittance difference of the mixed solution is compared with a first preset transmittance difference of 3.29% and a second preset transmittance difference of 5.26% respectively;

[0090] If the transmittance difference of the mixed solution is less than the first preset transmittance difference, it is determined that the preparation of the mixed solution does not meet the preset standard, and the preset pouring speed is reduced according to the ratio between the first preset transmittance difference and the transmittance difference of the mixed solution;

[0091] If the transmittance difference of the mixed solution is greater than or equal to the first preset transmittance difference and less than the second preset transmittance difference, it is determined that the preparation of the mixed solution does not meet the preset standard, and a second determination is made based on the solution uniformity characteristic value whether the preparation of the mixed solution meets the preset standard.

[0092] Specifically, the process of determining the uniform characteristic value of the solution includes:

[0093] The ratio of the viscosity of the chitosan solution to the preset viscosity of the chitosan solution is obtained and multiplied by the first evaluation coefficient, which is recorded as the first evaluation value, wherein the first evaluation coefficient is 0.34; the ratio of the viscosity of the poly(N-isopropylacrylamide) solution to the preset viscosity of the poly(N-isopropylacrylamide) solution is multiplied by the second evaluation coefficient, which is recorded as the second evaluation value, wherein the first evaluation coefficient is 0.37; and the ratio of the time for the transmittance of the mixed solution to reach stability to the preset stable time of 15 minutes is multiplied by the third evaluation coefficient, which is recorded as the third evaluation value, wherein the third evaluation coefficient is 0.44;

[0094] The sum of the first evaluation value, the second evaluation value and the third evaluation value is recorded as the solution uniformity characteristic value.

[0095] In this embodiment, the viscosity of the chitosan solution is preset to be selected within the range of [0.6η1, 0.8η1], where η1 is the average value of the viscosity of the chitosan solution;

[0096] The viscosity of the poly(N-isopropylacrylamide) solution is preset to be selected within the range of [0.7η2, 0.9η2], where η2 is the average value of the viscosity of the poly(N-isopropylacrylamide) solution;

[0097] Specifically, the process of secondarily determining whether the preparation of the mixed solution meets the preset standard according to the uniform characteristic value of the solution includes:

[0098] Comparing the uniform characteristic value of the solution with a preset uniform characteristic value of 0.87;

[0099] If the uniform characteristic value of the solution is less than the preset uniform characteristic value of the solution, it is determined that the preparation of the mixed solution meets the preset standard, and the mixed solution meeting the preset standard is filtered to obtain a chitosan / poly (N-isopropylacrylamide) solution;

[0100] If the solution uniformity characteristic value is greater than or equal to the preset solution uniformity characteristic value, it is determined that the preparation of the mixed solution does not meet the preset standard, and the stirring speed during the preparation of the mixed solution is reduced according to the difference between the solution uniformity characteristic value and the preset solution uniformity characteristic value.

[0101] Specifically, there are several speed reduction methods for reducing the stirring speed during the preparation of the mixed solution, wherein:

[0102] If the solution characteristic difference is less than the first preset solution characteristic difference of 0.23, then using the first speed adjustment coefficient of 0.98 to reduce the stirring speed during the preparation of the mixed solution;

[0103] If the solution characteristic difference is greater than or equal to the first preset solution difference and less than the second preset solution difference of 0.46, then using a second speed adjustment coefficient of 0.96 to reduce the stirring speed during the preparation of the mixed solution;

[0104] If the solution characteristic difference is greater than or equal to the second preset solution difference, the third speed adjustment coefficient 0.94 is used to reduce the stirring speed during the preparation of the mixed solution; the solution characteristic difference is the difference between the solution uniform characteristic value and the preset solution uniform characteristic value.

[0105] On the other hand, an embodiment of the present invention provides a composition for preventing and controlling soil-borne diseases of crops, wherein the composition is composed of the following raw materials: biochar, Bacillus subtilis, Bacillus amyloliquefaciens, polyvinyl alcohol, chitosan and poly (N-isopropylacrylamide).

[0106] The composition for preventing and controlling soil-borne diseases of crops prepared in the embodiment of the present invention can be used in combination with other fertilizers and applied to the soil, or seeds or seedlings can be soaked in the composition before planting crops to achieve the purpose of preventing and controlling soil-borne diseases.

[0107] Example 1

[0108] Taking tomatoes as an example, the tomato field was divided into three areas, which were respectively recorded as a test group, a control group and a blank group. The test group was fertilized by mixing the composition of the present invention with traditional fertilizers in a ratio of 1:2; the control group was fertilized by mixing the microbial agent in the prior art with traditional fertilizers in a ratio of 1:2; and the blank group was fertilized by traditional fertilizers. When the tomatoes were picked, the damage ratio due to soil-borne diseases was counted, and the statistical results are shown in Table 1 below:

[0109] Table 1 Relationship between soil-borne disease incidence and yield of mixed fertilization of the combination and traditional fertilizer at a ratio of 1:2

[0110] Experimental Group Comparison group Blank group Incidence of bacterial wilt (%) 8.3 16.2 21.7 Tomato yield (kg / mu) 3985 3421 2946

[0111] Example 2

[0112] Taking corn as an example under the condition of large temperature difference between day and night, the corn field was divided into three areas, which were respectively recorded as the test group, the control group and the blank group, wherein the test group was fertilized by mixing the composition of the present invention with the traditional fertilizer in a ratio of 1:2; the control group was fertilized by mixing the microbial agent in the prior art with the traditional fertilizer in a ratio of 1:2; and the blank group was fertilized by only applying the traditional fertilizer; when the corn was picked, the damage ratio due to soil-borne diseases was counted, and the statistical results are shown in Table 2 below:

[0113] Table 2 Relationship between soil-borne disease incidence and yield under conditions of large day and night temperature difference

[0114] Experimental Group Comparison group Blank group Incidence of bacterial wilt (%) 12.7 22.3 57.3 Corn yield (kg / mu) 843 579 367

[0115] Summarizing the two tables, it is concluded that the per-acre yield of tomatoes in the test area is greatly increased when the composition and traditional fertilizers are mixed and fertilized in an appropriate ratio compared with conventional fertilization, and the composition has a significant control effect on bacterial wilt. Under the condition of large temperature difference between day and night, the control rate of bacterial wilt in the test group applied with the thermosensitive composite bacterial agent microspheres of the present invention is still effective, and the crop yield can still be increased, thereby improving the environmental applicability of the composite bacterial agent.

[0116] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

[0117] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a composition for preventing and controlling soil-borne diseases of crops, characterized in that: include: inoculating Bacillus subtilis and Bacillus amyloliquefaciens into two activation culture media for cultivation respectively, to obtain a first seed culture solution and a second seed culture solution respectively; Fermenting the first seed culture solution and the second seed culture solution to obtain a first fermentation culture solution and a second fermentation culture solution respectively; The first fermentation bacterial liquid and the second fermentation bacterial liquid are filtered and impurities are removed to obtain a first bacterial stock solution and a second bacterial stock solution, and the mixture is mixed in proportion to obtain a bacterial agent mixed solution; The corn stalks are carbonized at high temperature and then ground into biochar by a ball mill; the biochar is added to the bacterial agent mixed solution, and the precipitate after separation treatment of the bacterial agent mixed solution is vacuum dried to obtain biochar powder with the Bacillus subtilis and the Bacillus amyloliquefaciens adsorbed and fixed thereon; The biochar powder is mixed with a polyvinyl alcohol solution to obtain a bacterial suspension, and the suspension is added dropwise to a calcium chloride solution to obtain biochar-based composite bacterial microspheres; At room temperature, weigh chitosan powder and add it to a 2% acetic acid solution, stir and stand to prepare a chitosan solution with a concentration of 4%, and obtain the viscosity of the chitosan solution; dissolving poly(N-isopropylacrylamide) in deionized water at room temperature, adding an initiator and a cross-linking agent to perform a free radical polymerization reaction, stirring to obtain a poly(N-isopropylacrylamide) solution, and obtaining the viscosity of the poly(N-isopropylacrylamide) solution; At room temperature, pouring the chitosan solution into the poly(N-isopropylacrylamide) solution at a preset pouring speed, stirring for a preset time and continuously acquiring the transmittance of the mixed solution to determine the time when the transmittance stops changing; When it is determined according to the transmittance difference of the mixed solution that the preparation of the mixed solution does not meet the preset standard, the preset pouring speed is reduced, or, according to the uniform characteristic value of the solution, the stirring speed during the preparation of the mixed solution is reduced or the mixed solution is filtered to obtain a chitosan / poly (N-isopropylacrylamide) solution; The biochar-based composite bacterial microspheres are transferred to a chitosan / poly (N-isopropylacrylamide) solution for coating, filtered, separated, washed, and then vacuum dried to obtain thermosensitive composite bacterial agent microspheres.

2. The method for preparing the composition for preventing and controlling soil-borne diseases of crops according to claim 1, characterized in that: The activation culture conditions of the Bacillus subtilis and the Bacillus amyloliquefaciens are that the pH of the culture medium is set to 7.4, the temperature is 37° C., the culture is carried out for 18 hours, and the shaking speed is 180 r / min.

3. The method for preparing the composition for preventing and controlling soil-borne diseases of crops according to claim 2, characterized in that: The weight ratio of the activation culture medium is 20% potato, 4% glucose, 0.5% beef extract, 2% peptone, 2% sodium chloride, 1.5% agar, and the balance is water.

4. The method for preparing the composition for preventing and controlling soil-borne diseases of crops according to claim 3, characterized in that: The fermentation and culturing process of the Bacillus subtilis and the Bacillus amyloliquefaciens comprises: under sterile conditions, inoculating the first seed culture solution and the second seed culture solution into two fermentation tanks respectively, with the inoculation amount of both being 4%, the components of the two fermentation culture media being the same, and the mass content of each component in 1L of distilled water being: 2% soybean meal, 0.5% urea, 0.2% ammonium sulfate, 4% starch, 5% molasses, 0.8% potassium dihydrogen phosphate, 0.2% disodium hydrogen phosphate, and 0.01% magnesium sulfate, the stirring speed being 240r / min, the culturing temperature being 30°C to 35°C, the ventilation volume being 1:0.8, and the fermentation time being 24h to 30h.

5. The method for preparing the composition for preventing and controlling soil-borne diseases of crops according to claim 4, characterized in that: The process of obtaining the viscosity of the chitosan solution and the viscosity of the poly(N-isopropylacrylamide) solution comprises: The chitosan solution and the poly (N-isopropylacrylamide) solution were placed in a constant temperature water bath respectively, and the water bath temperature was adjusted to room temperature and kept constant; Slowly immersing the rotor of the first rotational viscometer and the rotor of the second rotational viscometer into the chitosan solution and the poly(N-isopropylacrylamide) solution, respectively; Start the rotational viscometer and record the torque value of the rotor at the preset speed; Viscosity is the ratio of the product of the rotational viscometer constant and torque to the angular velocity; Repeat the measurement several times to calculate the average value of the viscosity of the chitosan solution and the average value of the viscosity of the poly(N-isopropylacrylamide) solution; The average value of the viscosity of the chitosan solution is recorded as the viscosity of the chitosan solution; the average value of the viscosity of the poly(N-isopropylacrylamide) solution is recorded as the viscosity of the poly(N-isopropylacrylamide) solution.

6. The method for preparing the composition for controlling soil-borne diseases of crops according to claim 5, characterized in that: The process of determining, based on the transmittance difference of the mixed solution, that the preparation of the mixed solution does not meet the preset standard comprises: At room temperature, the timing starts when the chitosan solution is poured into the poly(N-isopropylacrylamide) solution at a preset pouring speed; Obtaining the initial transmittance of the mixed solution by a transmission spectrometer; When the transmittance of the mixed solution stops changing, stop timing, and obtain the time from the start of timing to the time when the transmittance of the mixed solution stops changing; Calculating the transmittance difference of the mixed solution; Comparing the transmittance difference of the mixed solution with the first preset transmittance difference and the second preset transmittance difference respectively; If the transmittance difference of the mixed solution is less than the first preset transmittance difference, it is determined that the preparation of the mixed solution does not meet the preset standard, and the preset pouring speed is reduced according to the ratio between the first preset transmittance difference and the transmittance difference of the mixed solution; If the transmittance difference of the mixed solution is greater than or equal to the first preset transmittance difference and less than the second preset transmittance difference, it is determined that the preparation of the mixed solution does not meet the preset standard, and a second determination is made based on the solution uniformity characteristic value whether the preparation of the mixed solution meets the preset standard.

7. The method for preparing the composition for controlling soil-borne diseases of crops according to claim 6, characterized in that: The solution uniformity characteristic value is determined based on the viscosity of the chitosan solution, the viscosity of the poly(N-isopropylacrylamide) solution, and the time it takes for the transmittance of the mixed solution to reach stability.

8. The method for preparing the composition for controlling soil-borne diseases of crops according to claim 7, characterized in that: The process of secondarily determining whether the preparation of the mixed solution meets a preset standard according to the uniform characteristic value of the solution includes: Comparing the uniform characteristic value of the solution with a preset uniform characteristic value of the solution; If the uniform characteristic value of the solution is less than the preset uniform characteristic value of the solution, it is determined that the preparation of the mixed solution meets the preset standard, and the mixed solution meeting the preset standard is filtered to obtain a chitosan / poly (N-isopropylacrylamide) solution; If the solution uniformity characteristic value is greater than or equal to the preset solution uniformity characteristic value, it is determined that the preparation of the mixed solution does not meet the preset standard, and the stirring speed during the preparation of the mixed solution is reduced according to the difference between the solution uniformity characteristic value and the preset solution uniformity characteristic value.

9. The method for preparing the composition for controlling soil-borne diseases of crops according to claim 8, characterized in that: Several speed reduction methods are provided for reducing the stirring speed during the preparation of the mixed solution, and each speed reduction method has a different reduction range for the stirring speed during the preparation of the mixed solution.

10. A composition for preventing and controlling soil-borne diseases of crops prepared by the method according to any one of claims 1 to 9, characterized in that: The composition consists of the following raw materials: biochar, Bacillus subtilis, Bacillus amyloliquefaciens, polyvinyl alcohol, chitosan and poly (N-isopropylacrylamide).

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