A multi-factor response controlled-release pesticide and its preparation method and application

Abstract

The present invention relates to a multi-factor response controlled-release pesticide and a preparation method and application thereof. The pesticide is compounded with modified biochar loaded with carbendazim as a core and cellulose biomass as a response shell, and the modified biochar is phosphoric acid-modified corn straw biochar. In the present invention, the phosphoric acid-modified corn straw biochar can greatly increase the loading amount of carbendazim, obtain a core with a high loading amount, and use cellulose biomass as a response shell, which has good responsiveness to enzymes, pH and temperature, and can form a response shell that is unified with the onset conditions of crop diseases, so as to achieve a more accurate controlled-release effect of pesticides, which has a promoting effect on reducing the application and increasing the efficiency of pesticides in practical applications, and has important practical significance for the safe production and quality of food crops.

Description

Technical Field

[0001] The invention belongs to the field of pesticides, and in particular relates to a multi-factor response controlled-release pesticide and a preparation method and application thereof. Background Art

[0002] Pesticides play an important role in pest control and crop yield increase in modern agriculture, but they also bring many negative effects. In particular, due to the inefficiency of traditional pesticides, about 90% of pesticides will enter the ecosystem through evaporation, infiltration, degradation and migration, causing great threats to the environment and human health. With the increase in pesticide dosage and application frequency, the resistance of pests and diseases to pesticides has led to a global crop productivity decline of about 50%. At the same time, the increase in agricultural residues in grain crops has also brought about food safety problems. Therefore, the development of green and efficient crop pest control technology is of great practical significance to the yield, quality and safe production of grain crops.

[0003] Common diseases on crops have their own unique infection and disease conditions. For example, at the beginning of the occurrence of wheat fusarium rust, Fusarium graminearum will first secrete cellulase, pectinase and amylase to destroy the plant's conductive tissue vascular bundles and infect the crop's vascular system. The optimum temperature for the occurrence of wheat fusarium rust is 24-28°C, with a minimum of 8°C and a maximum of 32°C. For example, sheath blight is a high temperature and high humidity disease. A daily average temperature of around 25°C is conducive to the occurrence of the disease, while temperatures below 20°C or above 30°C are not conducive to the development of sheath blight. At the same time, when the pathogen infects the plant, it will secrete cell wall degrading enzymes containing cellulase to destroy the plant cell walls to achieve the purpose of infection. The pesticides in the prior art cannot be more accurately controlled and released according to the environment when the crop disease occurs, and the effect of reducing the amount of pesticides and increasing their efficiency is poor. Based on the above problems, the present invention provides a multi-factor responsive controlled-release pesticide and a preparation method and application thereof. Summary of the invention

[0004] The purpose of the present invention is to provide a multi-factor responsive controlled-release pesticide and its preparation method and application in order to solve the above problems, aiming to solve the problem that pesticides in the prior art cannot be more accurately controlled-released according to the environment when crop diseases occur, and the effect of reducing pesticide dosage and increasing efficiency is poor.

[0005] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0006] A multi-factor responsive controlled-release pesticide, wherein the pesticide is compounded with modified biochar loaded with carbendazim as a core and cellulose biomass as a responsive shell, and the modified biochar is phosphoric acid-modified corn straw biochar.

[0007] As a further optimization scheme of the present invention, the cellulose biomass is one of carboxymethyl cellulose and hydroxypropyl methyl cellulose.

[0008] A method for preparing a multi-factor responsive controlled-release pesticide comprises the following steps:

[0009] S1. Preparation of multi-factor responsive controlled release pesticide core:

[0010] S1-1, adding the corn stalk powder after crushing and passing through a 200-mesh sieve into a 20% by volume phosphoric acid solution, completely immersing it, stirring at room temperature, and filtering the resulting solution and drying it to obtain phosphoric acid-modified corn stalk powder;

[0011] S1-2, transferring the phosphoric acid-modified corn straw powder to an oxygen-deficient atmosphere, and obtaining phosphoric acid-modified corn straw biochar after thermal cracking;

[0012] S1-3, preparing a carbendazim solution with a volume percentage of 3% acetic acid solution as a solvent, adding phosphoric acid-modified corn straw biochar, placing it in a constant temperature water bath shaker, and filtering after dynamic adsorption to obtain phosphoric acid-modified corn straw biochar loaded with carbendazim;

[0013] S2. Preparation of multi-factor responsive controlled-release pesticides: Cellulosic biomass and ultrapure water are prepared in a mass ratio to obtain a cellulose solution, the phosphate-modified corn straw biochar loaded with carbendazim obtained in S1 is evenly mixed with the cellulose solution, the obtained mixed system is ultrasonically treated, taken out, and dried to a constant weight to obtain a pesticide with a multi-factor response.

[0014] As a further optimization scheme of the present invention, in S1 and S2, the drying temperature is 50-80°C.

[0015] As a further optimization scheme of the present invention, in S1, the pyrolysis temperature is 400-900°C, and the pyrolysis time is 30-120 min.

[0016] As a further optimization scheme of the present invention, in S1, the water bath shaking speed is 80-120 r / min.

[0017] As a further optimization scheme of the present invention, in S2, the cellulosic biomass and ultrapure water are prepared in a mass ratio of 1:10 to obtain a cellulose solution, and the mass ratio of the phosphate-modified corn straw biochar loaded with carbendazim to the cellulosic biomass is 3:1.

[0018] Application of a multi-factor response controlled-release pesticide in inhibiting pathogen spore germination and crop infection

[0019] As a further optimization scheme of the present invention, the pathogenic bacteria include Fusarium graminearum, Rhizoctonia solani and Metarhizium griseum.

[0020] The beneficial effects of the present invention are:

[0021] 1) The corn straw biochar modified with phosphoric acid in the present invention can greatly increase the loading capacity of carbendazim, obtain a core with a high loading capacity, and use cellulose biomass as a response shell, which has good responsiveness to enzymes, pH and temperature, and can form a response shell that is consistent with the conditions for the onset of crop diseases, so as to achieve a more accurate controlled release effect of pesticides, thereby improving the effect of reducing the amount of pesticides and increasing their effectiveness;

[0022] 2) The preparation method of the multi-factor responsive controlled-release pesticide of the present invention is highly versatile, simple in process, less time-consuming, and has good controllability. The multi-factor responsive controlled-release pesticide prepared by the method can significantly increase the release rate of the pesticide under the response of cellulase, further improving the effect of reducing the amount of the pesticide and increasing its efficiency;

[0023] 3) The multi-factor response controlled-release pesticide of the present invention has a good inhibitory effect on pathogens, including Fusarium graminearum, Rhizoctonia solani and Aspergillus niger, especially the spore germination, mycelial growth and crop infection of Fusarium graminearum, during actual use, and can effectively promote the reduction of pesticide application and increase of efficiency;

[0024] 4) The raw material cost of the phosphoric acid-modified corn straw biochar in the present invention is low, and it has the effect of improving soil quality after entering the soil, is environmentally friendly, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The adsorption effect of carbendazim on phosphoric acid-modified corn straw biochar obtained at different pyrolysis temperatures.

[0026] Figure 2 The adsorption effect of carbendazim on phosphoric acid-modified corn straw biochar obtained at different pyrolysis times at a pyrolysis temperature of 900℃.

[0027] Figure 3 The controlled release effect of pesticides in response to different organic matter shells, where A is phosphate-modified biochar (HB) without organic matter shell; B is carboxymethyl cellulose with organic matter shell; C is hydroxypropyl methyl cellulose with organic matter shell; D is hydroxyethyl cellulose with organic matter shell.

[0028] Figure 4 The present invention shows the response effect of the multi-factor response controlled-release pesticide (CHBC) on cellulase.

[0029] Figure 5 The multi-factor response controlled-release pesticide (CHBC) prepared by the present invention responds to temperature.

[0030] Figure 6 The figure shows the response effect of the multi-factor response controlled-release pesticide (CHBC) prepared by the present invention on pH.

[0031] Figure 7 The kinetic curves of the sustained release of carbendazim from the multi-factor response controlled-release pesticide (CHBC) prepared by the present invention and the phosphate-modified biochar (HB) not wrapped in an organic matter shell without environmental response.

[0032] Figure 8 SEM characterization of different materials, where A is unmodified biochar; B is phosphoric acid-modified biochar; C is the modified biochar core loaded with carbendazim; and D is a multi-factor response controlled-release pesticide (CHBC).

[0033] Fig. 9 is the inhibition rate of CHBC on spore germination of Fusarium graminearum in the spore germination inhibition experiment.

[0034] Fig.10 The inhibitory effect of CHBC on the mycelial growth of Fusarium graminearum in the mycelial growth inhibition leaf method experiment (CK: control; HB: phosphate-modified biochar not wrapped in an organic matter shell; CHBC: multi-factor response controlled-release pesticide prepared by the present invention; A, B, and C are 3 parallels in each group, respectively).

[0035] Fig.11 is the mycelium growth inhibition rate of CHBC on Fusarium graminearum in the mycelium growth inhibition experiment.

[0036] Fig.12 The inhibitory effect of CHBC on the mycelial growth of Fusarium graminearum on PDA plates (CK: control; HB: phosphate-modified biochar not wrapped in an organic matter shell; CHBC: a multi-factor response controlled-release pesticide prepared by the present invention; A, B, C, D, and E are 5 parallels in each group). DETAILED DESCRIPTION

[0037] The present invention is further described below in conjunction with the accompanying drawings and several optional embodiments. It should be noted that the present invention is not limited to the following embodiments. Any technical features and implementation schemes in the following embodiments are one or more of a variety of optional technical features and a variety of optional implementation schemes. For the sake of simplicity of description, this document cannot exhaustively list all the alternative technical features and implementation schemes contained in this patent. Therefore, those skilled in the art should know that any technical features and implementation schemes in this embodiment do not limit the scope of protection of this patent, which includes any alternative technical features and implementation schemes adopted by all those skilled in the art without creative work.

[0038] 1. Description

[0039] If no specific techniques and conditions are specified in the examples, the procedures are carried out according to the techniques and conditions described in the literature in the art or according to the product instructions. If no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0040] 2. Methods

[0041] Example 1

[0042] A method for preparing a multi-factor responsive controlled-release pesticide, the specific steps are as follows:

[0043] S1. Prepare 1 L of 20% phosphoric acid by volume with ultrapure water and phosphoric acid solution, weigh 50 g of dried corn stalk powder that has passed through a 200-mesh sieve, completely immerse it in the 20% phosphoric acid solution by volume, and stir it at room temperature for 18 hours;

[0044] S2, filtering the solution obtained in S1, and drying the filtered powder in a 50° C. forced air drying oven to obtain phosphoric acid-modified corn stalk powder;

[0045] S3, transferring the phosphoric acid-modified corn straw powder into a muffle furnace, and pyrolyzing it at 900°C for 30 minutes in an oxygen-deficient atmosphere to obtain phosphoric acid-modified corn straw biochar;

[0046] S4. Prepare 1 L of carbendazim solution with 3% by volume acetic acid solution as solvent, add phosphoric acid-modified corn straw biochar, place it in a constant temperature water bath shaker, and dynamically adsorb at a speed of 80 r / min for 24 hours at a temperature of 25° C., and then filter to obtain phosphoric acid-modified corn straw biochar loaded with carbendazim;

[0047] S5, take 1g of carboxymethyl cellulose, the mass ratio of carboxymethyl cellulose to ultrapure water is 1:10, prepare 10ml of carboxymethyl cellulose solution, take 3g of phosphoric acid-modified corn straw biochar loaded with carbendazim and mix it evenly with 10ml of cellulose solution;

[0048] S6. After ultrasonic treatment of the mixed system for 10 minutes, the mixed system was taken out and placed in a 50° C. forced air drying oven to dry to constant weight to obtain a pesticide (CHBC) loaded with carbendazim and having multiple responses to enzymes, temperature and pH.

[0049] Example 2

[0050] A method for preparing a multi-factor responsive controlled-release pesticide, the specific steps are as follows:

[0051] S1. Prepare 1 L of 20% phosphoric acid by volume with ultrapure water and phosphoric acid solution, weigh 50 g of dried corn stalk powder that has passed through a 200-mesh sieve, completely immerse it in the 20% phosphoric acid solution by volume, and stir it at room temperature for 18 hours;

[0052] S2, filtering the solution obtained in S1, and drying the filtered powder in an air drying oven at 80° C. to obtain phosphoric acid-modified corn straw powder;

[0053] S3, transferring the phosphoric acid-modified corn straw powder into a muffle furnace, and pyrolyzing it at 900°C for 30 minutes in an oxygen-deficient atmosphere to obtain phosphoric acid-modified corn straw biochar;

[0054] S4. Prepare 1 L of carbendazim solution with 3% by volume acetic acid solution as solvent, add phosphoric acid-modified corn straw biochar, place it in a constant temperature water bath shaker, and dynamically adsorb at a speed of 120 r / min for 24 hours at 25°C, and then filter to obtain phosphoric acid-modified corn straw biochar loaded with carbendazim;

[0055] S5, take 1g of hydroxypropyl methylcellulose, the mass ratio of hydroxypropyl methylcellulose to ultrapure water is 1:10, prepare 10ml of hydroxypropyl methylcellulose solution, take 3g of phosphate-modified corn straw biochar loaded with carbendazim and mix it evenly with 10ml of cellulose solution;

[0056] S6. After ultrasonic treatment of the mixed system for 10 minutes, the mixed system was taken out and placed in a 50° C. forced air drying oven to dry to constant weight to obtain a pesticide (CHBC) loaded with carbendazim and having multiple responses to enzymes, temperature and pH.

[0057] like Figure 1-7 As shown in the figure, the phosphate-modified corn straw biochar obtained by thermal cracking at 900°C for 30 minutes has a higher loading capacity for carbendazim. Compared with hydroxyethyl cellulose as the response shell, the multi-factor responsive controlled-release pesticide prepared by using carboxymethyl cellulose and hydroxypropyl methyl cellulose, especially carboxymethyl cellulose as the response shell of the phosphate-modified corn straw biochar loaded with carbendazim has good responsiveness to multiple factors such as enzyme, pH and temperature, and can achieve a more precise pesticide controlled-release effect, thereby improving the effect of reducing the amount of pesticide and increasing its efficiency.

[0058] 3. Experimental Verification

[0059] 3.1 In order to verify the effect of different biochars prepared by different modification methods on the adsorption of carbendazim, the present invention retrieved a number of data. The specific biochars provided include sludge biochar, peanut shell biochar continuously modified by KMnO4 and KOH, corn straw biochar modified by FeCl3, and rape straw biochar. The above biochars were used to conduct experiments on the adsorption effect of carbendazim. The experimental data are shown in Table 1. In addition, the present invention also conducted multiple groups of experiments to conduct experiments on the adsorption effect of carbendazim on biochars modified with different modification agents or different raw materials. It should be noted that:

[0060] KOH modified corn straw biochar is to modify corn straw powder using KOH solution instead of phosphoric acid solution, and the remaining steps are consistent with Example 1;

[0061] Phosphoric acid-modified rape straw biochar is prepared by modifying rape straw powder using phosphoric acid solution, and the remaining steps are the same as those in Example 1;

[0062] Phosphoric acid-modified rice husk biochar is to modify rice husk powder using phosphoric acid solution, and the remaining steps are consistent with Example 1;

[0063] A control group, i.e., unmodified corn straw biochar, was set up. The experimental data on the adsorption of carbendazim are shown in Table 1:

[0064] Table 1

[0065]

[0066]

[0067]

[0068]

[0069] Experimental conclusion: As shown in Table 1, the corn straw biochar modified with phosphoric acid prepared by the present invention has a high loading capacity for carbendazim, which is much higher than the high value reported in the current literature. The phosphoric acid-modified corn straw biochar in the present invention is used as a carrier of carbendazim, which is cheap, easy to obtain, and has a high pesticide loading capacity.

[0070] 3.2 To verify the inhibitory effect of (CHBC) on the spore germination of Fusarium graminearum, the specific steps are as follows:

[0071] Step 1, prepare 1L of 4% mung bean soup culture medium and dispense it into 150ml conical bottles, 50ml per bottle;

[0072] Step 2: Use a 7mm puncher to punch out several bacterial discs from the Fusarium graminearum bacterial plate cultured on the PDA plate for 4 days, and add the bacterial discs into the packaged mung bean soup culture medium, with 5-6 bacterial discs placed in each bottle;

[0073] Step 3, placing the mung bean soup culture medium in the bacterial dish in a constant temperature incubator at 28°C for 3 days;

[0074] Step 4, centrifuging and concentrating the spore suspension of Fusarium graminearum cultured for 3 days to obtain a spore suspension concentration of 1×106;

[0075] Step 5, take 0.2 ml of the concentrated spore suspension and place it in a sterilized 2 ml centrifuge tube. Several tubes are required;

[0076] Step 6, prepare 20ul of five CHBC solutions with different concentration gradients, add them to the spore concentrate respectively, and then place them in a constant temperature incubator at 28°C for 24h;

[0077] Step 7, streak the spore solution after culturing for 24 hours on a 1% water culture medium using a plate streak method, and then place it in a constant temperature incubator at 28° C. and culture it for 3 hours;

[0078] Step 8: Place the spores cultured on 1% water agar under an electron microscope to count and observe the spore germination. The inhibition results are shown in the attached Fig. 9 .

[0079] 3.3 To verify the inhibitory effect of (CHBC) on the mycelial growth of Fusarium graminearum on wheat leaves, the specific steps are as follows:

[0080] Step 1, preparing three CHBC solutions of different concentrations;

[0081] Step 2: Cut wheat leaves at the one-leaf and one-heart stage, with a leaf height of about 7 cm, and treat 15 leaves per treatment;

[0082] Step 3, 15 leaves were divided into three groups and immersed in three CHBC solutions of different concentrations. After 30 seconds, the leaves were taken out and dried with filter paper. Each group was treated three times.

[0083] Step 4, prepare 200 ml of 1% water agar medium and dispense it into 20 ml test tubes, with 5 ml placed in each test tube, and sterilize the dispensed medium in a high pressure steam sterilizer at 121° C. for 20 minutes;

[0084] Step 5, punch out several bacterial discs from the Fusarium graminearum bacterial plate cultured on the PDA plate for 4 days using a 7mm puncher;

[0085] Step 6, inoculate the bacterial disc into a test tube containing water agar medium;

[0086] Step 7, the treated leaves were divided into 1% water agar test tubes, 5 leaves in each test tube, and placed in an artificial climate box (28°C, 12hL / 12hD) for 5 days;

[0087] Step 8: During the culture period, the mycelium growth needs to be observed every day, the mycelium growth height needs to be recorded and photographed. The inhibition results are attached. Fig.10 .

[0088] 3.4 To verify the inhibitory effect of (CHBC) on the mycelial growth of Fusarium graminearum, the following steps are included:

[0089] Step 1. Weigh 5 groups of CHBC materials with different weights (drug concentrations are A: 10 mg / L, B: 9 mg / L, C: 8 mg / L, D: 7 mg / L, and E: 6 mg / L), place them in 5 ml centrifuge tubes, add 1 ml of ultrapure water, mix well, and place them in a high-pressure steam sterilizer at 121°C for 20 minutes;

[0090] Step 2, prepare 5 portions of PDA culture medium (100 ml), place them in a high pressure steam sterilizer and sterilize them at 121° C. for 20 minutes;

[0091] Step 3, take out the sterilized CHBC and PDA culture medium and place them on the clean bench. When the temperature of the PDA culture medium cools to 40-50°C, pour the sterilized CHBC into the culture medium, mix evenly and pour into a plate;

[0092] Step 4: Use a 7mm hole puncher to punch out several bacterial discs from the prepared Fusarium graminearum bacterial plate;

[0093] Step 5, inoculate the bacterial disc on a PDA plate mixed with CHBC;

[0094] Step 6, seal the inoculated plate and place it in a 28°C constant temperature incubator for 5 days;

[0095] Step 7: Observe and record the mycelial growth during the culture period, record the mycelial growth height and take photos. The inhibition results are attached. Figure 11-12 .

[0096] Experimental conclusion: The multi-factor response controlled-release pesticide in the present invention has a good inhibitory effect on pathogens, including Fusarium graminearum, Rhizoctonia solani and Aspergillus niger, especially the spore germination, mycelial growth and crop infection of Fusarium graminearum during actual use, and can effectively promote the reduction of pesticide application and increase its efficiency.

[0097] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A multi-factor response controlled-release pesticide, characterized in that: The pesticide is compounded with modified biochar loaded with carbendazim as the core and cellulose biomass as the response shell, and the modified biochar is corn straw biochar modified with phosphoric acid; The cellulosic biomass is carboxymethyl cellulose; The method for preparing the core of the multi-factor responsive controlled-release pesticide comprises the following steps: S1. The corn stalk powder after crushing and passing through a 200-mesh sieve is added into a 20% by volume phosphoric acid solution, completely immersed, stirred at room temperature, and the obtained solution is filtered and dried to obtain phosphoric acid-modified corn stalk powder; Among them, the drying temperature is 50-80℃; S2, transferring the phosphoric acid-modified corn straw powder to an oxygen-deficient atmosphere, and obtaining phosphoric acid-modified corn straw biochar after thermal cracking; Among them, the thermal cracking temperature is 900°C and the thermal cracking time is 30min; S3. Prepare a carbendazim solution with a volume percentage of 3% acetic acid solution as a solvent, add phosphoric acid-modified corn straw biochar, place it in a constant temperature water bath shaker, and filter after dynamic adsorption to obtain phosphoric acid-modified corn straw biochar loaded with carbendazim.

2. A multi-factor response controlled-release pesticide according to claim 1, characterized in that: In S3, the water bath shaker speed was 80-120 r / min, and the dynamic adsorption time was 24 h.

3. A method for preparing a multi-factor responsive controlled-release pesticide as claimed in any one of claims 1 to 2, characterized in that: Cellulosic biomass and ultrapure water are prepared in a mass ratio to obtain a cellulose solution, and the phosphate-modified corn straw biochar loaded with carbendazim is evenly mixed with the cellulose solution. The obtained mixed system is taken out after ultrasonic treatment, and dried at 50°C to constant weight to obtain a pesticide with multi-factor response.

4. The method for preparing a multi-factor responsive controlled-release pesticide according to claim 3, characterized in that: The cellulose biomass and ultrapure water are prepared in a mass ratio of 1:10 to obtain a cellulose solution, and the mass ratio of the phosphate-modified corn straw biochar loaded with carbendazim to the cellulose biomass is 3:

1.

5. Use of the multi-factor responsive controlled-release pesticide as claimed in any one of claims 1 to 2 in inhibiting the germination of pathogenic bacteria spores and infection of crops.

6. The use of a multi-factor responsive controlled-release pesticide according to claim 5, characterized in that: The pathogenic bacteria include Fusarium graminearum, Rhizoctonia solani and Aspergillus griseus.

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