Aqueous suspension pesticide composition and angiosperm seed treatment method

Abstract

The invention provides a water-based suspension pesticide composition. The water-based suspension pesticide composition comprises the following components: a solvent deionized water; based on the mass of the solvent, the core-shell structure active particles account for 0.5-20w%; based on the mass of the solvent, 0.01-5w% of a suspension stabilizer; the core-shell structure active particles are humidity response microspheres resistant to acid and alkali, the core-shell structure active particles are used, intermolecular acting force is reduced, particle agglomeration is reduced, dispersity of active ingredients is improved, a natural polymer material is adopted as a shell, biocompatibility is good, biodegradability is achieved, pollution to the environment is reduced, and the core-shell structure active particles are environmentally friendly. Meanwhile, the PEG-PCL block copolymer is introduced, so that the pesticide release rate can be accurately controlled according to the environment humidity change, and the pesticide utilization rate is increased. Moreover, the chitosan-sodium alginate composite gel of the particle shell layer is stably and slowly released in neutral and weakly alkaline soil, in acidic and strongly alkaline environments, the microspheres are prevented from collapsing, the stability of the particle slow-release system in soil with different PH values is improved, and the application range of the active particles is expanded.

Description

Technical Field

[0001] The present invention relates to the technical field of plant seed treatment, and specifically to an aqueous suspension pesticide composition and a method for treating angiosperm seeds. Background Art

[0002] An aqueous suspension pesticide composition is a pesticide preparation made by a special process with water as the medium for active ingredients, adjuvants, etc. Due to its high efficacy, long persistence, and friendliness to humans, animals, and the environment, it has gradually replaced traditional pesticides and is widely used in agricultural pest control, plant growth regulation, etc. In order to extend the action time of the active ingredient, the active component is encapsulated by a polymer material to form microparticles, and the polymer outside the microparticles decomposes in the soil to extend the effective coverage protection days.

[0003] However, this active ingredient sustained-release system of microparticles is mostly applied in neutral soil and has uncontrollability. When the external environmental humidity is too low, the released active ingredient becomes inactivated due to poor crop absorption, pathogen dormancy, poor microbial activity, etc. When the humidity is too high or the soil is acidic or alkaline, the microparticles collapse and cannot maintain their shape, resulting in the complete release of the active substance, thus causing a too high local concentration and leading to crop poisoning or seedling burning. Therefore, there is an urgent need to develop a new humidity-responsive microparticle that can avoid the inactivation of the active component in a low-humidity environment and maintain stable slow release under high humidity or acidic or alkaline conditions to maintain the effective coverage protection days of the active component. Summary of the Invention

[0004] (I) Technical Problems to be Solved

[0005] In view of the deficiencies of the prior art, the present invention provides an aqueous suspension pesticide composition and a method for treating angiosperm seeds to solve the problems raised in the above background art.

[0006] (II) Technical Solutions

[0007] To achieve the above object, the present invention is realized through the following technical solutions: An aqueous suspension pesticide composition, comprising the following components: deionized water as the solvent; 0.5 - 20 w% of core-shell structure active microparticles based on the mass of the solvent; 0.01 - 5 w% of a suspension stabilizer based on the mass of the solvent.

[0008] The core-shell structure active microparticle is an acid- and alkali-resistant humidity-responsive microsphere.

[0009] As a further preference, the suspension stabilizer is one or more of sodium carboxymethylcellulose, xanthan gum, guar gum, and polyvinyl alcohol.

[0010] As a further preference, the core-shell structured active particles include a composite gel shell of chitosan and sodium alginate, and an active component core wrapped by a hydrophilic chain and a hydrophobic chain PEG-PCL block copolymer.

[0011] As a further preference, the molecular weight of the PEG is 2 KDa, the molecular weight of the PCL is 5 KDa, and the PEG / PCL value is 8:2 - 2:8.

[0012] As a further preference, the core-shell structured active particles are prepared by the following steps:

[0013] ① Dissolve PEG-PCL in dichloromethane (DCM), add a pesticide active ingredient and a nano metal oxide, ultrasonically disperse uniformly, and drop the above solution into an aqueous phase containing 1% emulsifier under stirring to form a stable emulsion;

[0014] ② Stir in a water bath at 40 °C for 4 h, volatilize DCM, centrifuge to collect microspheres, wash 3 times with deionized water, disperse the solid matter in a 3% calcium chloride aqueous solution and impregnate for 3 - 6 h, filter to remove the solvent, and freeze-dry for 12 h to obtain Ca 2+ —core microspheres;

[0015] ③ Slowly add chitosan to a 1% acetic acid solution and stir until completely dissolved to obtain a chitosan solution; dissolve sodium alginate in deionized water and stir until completely dissolved to obtain a sodium alginate solution. Mix the chitosan solution and the sodium alginate solution in a volume ratio of 1:1 to form a solution system. Disperse the Ca 2+ —core microspheres in the solution system, stir at 400 rpm for 30 min, after gelation, centrifuge, wash and freeze-dry to obtain the core-shell structured active particles.

[0016] As a further preference, the pesticide active ingredient is one or more of tebuconazole, difenoconazole, fludioxonil, azoxystrobin, pyraclostrobin, imidacloprid, thiamethoxam, lambda-cyhalothrin, indole-3-butyric acid, naphthaleneacetic acid, and brassinolide.

[0017] As a further preference, the nano metal oxide is one or more of zinc oxide, titanium oxide, copper oxide, and cerium oxide.

[0018] As a further preference, the emulsifier is one or more of Tween-20, Tween-80, Tween-60, Span-20, and Span-80.

[0019] A method for treating angiosperm seeds, using the above aqueous suspension pesticide composition, first treating the angiosperm seeds by low-temperature plasma, then assembling the aqueous suspension pesticide composition into a seed coating machine with a liquid-solid ratio of 1:5 - 1:10, spraying the seeds through a spraying system, and stirring the seeds during the spraying process. After coating, the seeds are dried by low-temperature hot air to reduce the seed moisture content to 8% - 10%.

[0020] (III) Beneficial effects

[0021] The present invention provides an aqueous suspension pesticide composition and a method for treating angiosperm seeds, having the following beneficial effects:

[0022] The core-shell structured active particles of the present invention include a composite gel shell of chitosan and sodium alginate, and an active component core wrapped by a hydrophilic chain and a hydrophobic chain PEG-PCL block copolymer. The suspension stability of the particles is improved through the core-shell structure, prolonging the product shelf life. At the same time, the outer shell layer reduces the intermolecular force, reduces particle aggregation, and improves the dispersibility of the active ingredient. Moreover, using natural polymer materials as the shell has good biocompatibility and is biodegradable, reducing environmental pollution;

[0023] At the same time, the introduced PEG-PCL block copolymer, when the humidity ≥ threshold, the hydrophilic chain absorbs water and swells, increasing the porosity of the nuclear membrane microspheres, promoting the release of the active component. When the humidity < threshold, the hydrophilic chain and the hydrophobic chain form a dense structure to seal the active component, avoiding the inactivation caused by the release of the active component under drought conditions. The humidity-responsive characteristic can accurately control the pesticide release rate according to the environmental humidity change, improving the pesticide utilization rate and reducing waste.

[0024] Moreover, the chitosan-sodium alginate composite gel of the particle shell layer is stable and slowly releases in neutral and weakly alkaline soils. In acidic and strongly alkaline environments, while increasing the release rate of the active component, it maintains the microsphere morphology, avoiding microsphere collapse, improving the stability of the micro-particle sustained-release system in different pH soils, and expanding the applicable range of the active particles. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the preparation of the aqueous suspension pesticide composition of the present invention and the seed treatment process;

[0026] Figure 2 It is a schematic diagram of the core-shell structured active particle structure of the present invention.

[0027] Among them, 1 is the active particle, 11 is the core, 12 is the nuclear membrane, 121 is the hydrophobic layer, 122 is the hydrophilic layer, 13 is the shell, 2 is the nano-metal oxide, 3 is the pesticide active component, 4 is the sodium alginate gel, 5 is the chitosan gel, and 6 is the calcium ion. DETAILED DESCRIPTION OF THE INVENTION

[0028] In the present invention, unless otherwise clearly specified and defined, the first feature being "on" or "under" the second feature may include direct contact between the first and second features, or may include the first and second features not being in direct contact but in contact through additional features therebetween. Moreover, the first feature being "above", "over" and "on top of" the second feature includes the first feature being directly above and obliquely above the second feature, or merely indicating that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "underneath" the second feature includes the first feature being directly below and obliquely below the second feature, or merely indicating that the first feature has a lower horizontal height than the second feature.

[0029] The following disclosure provides many different embodiments or examples for implementing different structures of the present invention. To simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. In addition, the present invention may repeat reference numerals and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides examples of various specific processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0030] One aspect of the present invention provides an aqueous suspension pesticide composition, comprising the following components: solvent deionized water; 0.5 - 20 w% of core-shell structured active particles based on the mass of the solvent; 0.01 - 5 w% of a suspension stabilizer based on the mass of the solvent.

[0031] Wherein: the above-mentioned suspension stabilizer is one or more of sodium carboxymethylcellulose, xanthan gum, guar gum, and polyvinyl alcohol.

[0032] The above-mentioned core-shell structured active particles are acid- and alkali-resistant humidity-responsive microspheres;

[0033] As Figure 2 shown, the active particle 1 includes a core 11, a nuclear membrane 12, and a shell 13. Among them, the core 11 includes a nano metal oxide 2 and a pesticide active ingredient 3. The nuclear membrane 12 is composed of a hydrophobic layer 121 and a hydrophilic layer 122 formed by a hydrophilic chain and a hydrophobic chain PEG-PCL block copolymer. The shell 13 is a composite gel composed of a chitosan gel 5 and an alginate gel 4, and calcium ions 6 are distributed on the outer wall of the hydrophilic layer 122.

[0034] Specifically, the core-shell structured active particles include a composite gel shell of chitosan and alginate, and an active component inner core wrapped by a hydrophilic chain and a hydrophobic chain PEG-PCL block copolymer.

[0035] Furthermore, the active ingredient core includes nano metal oxide 2 and pesticide active ingredient 3, with a PEG molecular weight of 2 KDa, a PCL molecular weight of 5 KDa, and a PEG / PCL ratio of 8:2 - 2:8.

[0036] It can be understood that by adjusting the PEG / PCL ratio to control the hydrophilic / hydrophobic balance and regulate the humidity response threshold, when the humidity ≥ the threshold, the hydrophilic chains absorb water and swell, increasing the porosity of the core-shell microspheres and promoting the release of the active ingredients. When the humidity < the threshold, the hydrophilic and hydrophobic chains form a dense structure to seal the active ingredients and prevent inactivation caused by the release of the active ingredients under drought conditions.

[0037] In other embodiments, other block copolymers containing hydrophilic and hydrophobic chains can be used instead of the PEG-PCL block copolymer, such as polyethylene glycol-b-polylactic acid block copolymer.

[0038] Furthermore, the core-shell structured active microparticles are prepared by the following steps:

[0039] ① Dissolve PEG-PCL in dichloromethane (DCM), add the pesticide active ingredient and nano metal oxide, and ultrasonically disperse them evenly. Then, under stirring, drop the above solution into the aqueous phase containing 1% emulsifier to form a stable emulsion.

[0040] Among them, the concentration of the pesticide active ingredient is 3% - 10% w / w, based on PEG-PCL, specifically one or more of tebuconazole, difenoconazole, fludioxonil, azoxystrobin, pyraclostrobin, imidacloprid, thiamethoxam, lambda-cyhalothrin, indole-3-butyric acid, naphthaleneacetic acid, and brassinolide.

[0041] The concentration of the nano metal oxide is 0.3% - 10% w / w, based on PEG-PCL, specifically one or more of zinc oxide, titanium oxide, copper oxide, and cerium oxide.

[0042] It can be understood that zinc oxide can photocatalytically antibacterial, provide UV protection, promote plant growth, and reduce fungal diseases such as powdery mildew and rust; titanium oxide can sterilize through photocatalysis, reduce organic pollutants, repair the soil, and enhance soil stress resistance; copper oxide is antifungal, improves plant immunity, and prevents diseases such as downy mildew and anthracnose; cerium oxide scavenges reactive oxygen species, improves stress resistance, and protects seeds under stress conditions. The metal oxides can be compounded according to specific requirements and usage scenarios.

[0043] The emulsifier is one or more of Tween-20, Tween-80, Tween-60, Span-20, and Span-80.

[0044] ② Stir in a 40 °C water bath for 4 h, evaporate DCM, centrifuge to collect the microspheres, wash them 3 times with deionized water, disperse the solid matter in a 3% calcium chloride aqueous solution and soak for 3 - 6 h, filter to remove the solvent, and freeze-dry for 12 h to obtain Ca 2+ —core microspheres.

[0045] It can be understood that in step ①, a W / O emulsion is formed, that is, the hydrophobic end of the PEG-PCL block copolymer wraps the pesticide active ingredient and the nano metal oxide inward to form the core, and the hydrophilic end forms the nuclear membrane outward. After freeze-drying, the core microspheres are obtained, and Ca is loaded on the nuclear membrane of the core by impregnation. 2+ .

[0046] ③ Slowly add chitosan to a 1% acetic acid solution and stir until completely dissolved to obtain a chitosan solution; dissolve sodium alginate in deionized water and stir until completely dissolved to obtain a sodium alginate solution. Mix the chitosan solution and the sodium alginate solution in a volume ratio of 1:1 to form a solution system. Disperse the Ca 2+ —core microspheres in the solution system, stir at 400 rpm for 30 min, centrifuge, wash and freeze-dry after gelation to obtain the core-shell structured active particles.

[0047] Among them, the deacetylation degree of chitosan is ≧85%, Mw = 100KDa, and the concentration is 1% - 4% w / v; the Mw of sodium alginate is 30 - 50KDa, and the concentration is 2% - 5% w / v.

[0048] It can be understood that Ca loaded on the nuclear membrane 2+ guides the cross-linking of sodium alginate on the outer wall of the nuclear membrane. At the same time, the chitosan mixed with sodium alginate is deposited on the surface of the nuclear membrane due to hydrogen bond action and capillary force. After freeze-drying, a chitosan-sodium alginate composite gel is formed, in which Ca 2+ and the sodium alginate gel act as the composite gel skeleton, improving the mechanical strength of the particles while increasing the binding force between the gel and the core.

[0049] Furthermore, on the premise that the soil environmental humidity is suitable, when the soil is neutral, the chitosan-sodium alginate composite gel on the particle shell absorbs water, and the core active ingredient is slowly released into the soil, increasing the effective coverage protection days of the slow-release system; when the soil is acidic, the solubility of chitosan increases, accelerating the release of the active component to improve the stress resistance of crops. At the same time, the sodium alginate gel skeleton supports the microspheres to prevent the microspheres from breaking and affecting the stability of the slow-release system; when the soil is alkaline, the precipitated chitosan interacts with the sodium alginate gel skeleton to ensure the mechanical strength of the microspheres and maintain the stability of the slow-release system; when the soil is strongly alkaline, part of the sodium alginate gel decomposes, accelerating the release of the active component from the pores. At the same time, the precipitated chitosan wraps and supports the core to prevent the microspheres from breaking. Thereby improving the stability of the particles in soils with different pH values and enhancing the stress resistance of crops.

[0050] Preparation of aqueous suspension system:

[0051] Disperse the core-shell structured active particles in water at a ratio of 1:10, and perform ultrasonic treatment (20 kHz, 3 min) to prevent agglomeration;

[0052] Add a suspension stabilizer to enhance the suspension stability, and mix evenly to obtain an aqueous suspension pesticide composition.

[0053] Among them, the composite gel coating the outside of the core-shell structured active particles reduces the intermolecular force, thereby avoiding particle agglomeration, reducing the use of emulsifiers in the system, improving the biocompatibility of the aqueous suspension pesticide composition, reducing environmental pollution. At the same time, the core-shell structure ensures the stable suspension of the particles in the solution and extends the product shelf life.

[0054] The present invention also provides a method for treating angiosperm seeds. Treat the angiosperm seeds by low-temperature plasma (power 50 W, treatment time 15 s), assemble the above aqueous suspension pesticide composition into a seed coating machine, with a liquid-solid ratio of 1:5 - 1:10, spray the seeds through a spray system, and stir the seeds during the spraying process. After coating, the seeds are dried by low-temperature hot air (below 40°C) to reduce the moisture content to 8% - 10%.

[0055] Specifically, the specific surface area of the seed coat surface is increased by plasma treatment, and the loading amount and adhesion strength of the aqueous suspension pesticide composition are improved.

[0056] To further understand the present invention, the following examples are used to illustrate the aqueous suspension pesticide composition provided by the present invention. The protection scope of the present invention is not limited by the following examples.

[0057] Example 1

[0058] ① Dissolve 100 g of PEG-PCL in dichloromethane (DCM), add 0.5 g of fludioxonil, 8.5 g of imidacloprid, 1 g of difenoconazole and 5 g of nano-metal cerium oxide, disperse them evenly by ultrasonic treatment, and drop the above solution into the aqueous phase containing 1% Tween-80 under stirring to form a stable emulsion.

[0059] ② Stir in a 40°C water bath for 4 h, volatilize DCM, collect the microspheres by centrifugation, wash them 3 times with deionized water, disperse the solid matter in 3% calcium chloride aqueous solution and impregnate for 5 h, filter off the solvent by suction filtration, and freeze-dry for 12 h to obtain Ca 2+ —core microspheres.

[0060] ③ Slowly add 2 g of chitosan to 50 ml of 1% acetic acid solution, stir until completely dissolved to obtain a chitosan solution; dissolve 2 g of sodium alginate in 50 ml of deionized water, stir until completely dissolved to obtain a sodium alginate solution, mix the chitosan solution and the sodium alginate solution in a volume ratio of 1:1 to form a solution system, and disperse 10 g of Ca 2+ — core microspheres in the solution system, stir at 400 rpm for 30 min, after gelation, centrifuge, wash and freeze-dry to obtain core-shell structured active microparticles.

[0061] ④ Disperse the core-shell structured active microparticles in water at a ratio of 1:10, perform ultrasonic treatment (20 kHz, 3 min) to prevent aggregation; add 0.01% sodium carboxymethylcellulose to enhance the suspension stability, and mix evenly to obtain an aqueous suspension pesticide composition.

[0062] ⑤ Treat wheat seeds by low-temperature plasma (power 50 W, treatment time 15 s), assemble the aqueous suspension pesticide composition prepared in step ④ into a seed coating machine, with a liquid-solid ratio of 1:10, spray the seeds through a spraying system, and stir the seeds during the spraying process. After coating, the seeds are dried by low-temperature hot air (below 40 °C) to reduce the moisture content to 8%.

[0063] Example 2

[0064] ① Dissolve 100 g of PEG-PCL in dichloromethane (DCM), add 6.95 g of thiamethoxam, 1 g of azoxystrobin, 0.05 g of indole-3-butyric acid and 2 g of nano-metal zinc oxide, ultrasonically disperse evenly, and drop the above solution into the aqueous phase containing 1% Tween-80 under stirring to form a stable emulsion.

[0065] ② Stir in a 40 °C water bath for 4 h, volatilize DCM, centrifuge to collect the microspheres, wash 3 times with deionized water, disperse the solid matter in 3% calcium chloride aqueous solution and impregnate for 4 h, filter to remove the solvent, and freeze-dry for 12 h to obtain Ca 2+ — core microspheres.

[0066] ③ Slowly add 1 g of chitosan to 50 ml of 1% acetic acid solution, stir until completely dissolved to obtain a chitosan solution; dissolve 2.5 g of sodium alginate in 50 ml of deionized water, stir until completely dissolved to obtain a sodium alginate solution, mix the chitosan solution and the sodium alginate solution in a volume ratio of 1:1 to form a solution system, and disperse 12 g of Ca 2+ — core microspheres in the solution system, stir at 400 rpm for 30 min, after gelation, centrifuge, wash and freeze-dry to obtain core-shell structured active microparticles.

[0067] ④Disperse the core-shell structured active microparticles in water at a ratio of 1:10, and perform ultrasonic treatment (20 kHz, 3 min) to prevent agglomeration; add 0.01% sodium carboxymethylcellulose to enhance the suspension stability, and mix evenly to obtain an aqueous suspension pesticide composition.

[0068] ⑤Treat vegetable seeds by low-temperature plasma (power 50 W, treatment time 15 s), assemble the aqueous suspension pesticide composition prepared in step ④ into a seed coating machine, with a liquid-solid ratio of 1:15, spray the seeds through a spraying system, and stir the seeds during the spraying process. After coating, the seeds are dried by low-temperature hot air (below 40°C) to reduce the moisture content to 10%.

[0069] Comparative Example 1

[0070] ①Ultrasonically disperse 0.5 g of fludioxonil, 8.5 g of imidacloprid, 1 g of difenoconazole and 5 g of nano-metal cerium oxide evenly, and drop the above solution into the aqueous phase containing 1% Tween-80 under stirring to form a stable emulsion. Add 0.01% sodium carboxymethylcellulose to enhance the suspension stability, and mix evenly to obtain a comparative suspension pesticide composition.

[0071] ②Treat wheat seeds by low-temperature plasma (power 50 W, treatment time 15 s), assemble the comparative suspension pesticide composition prepared in step ① into a seed coating machine, with a liquid-solid ratio of 1:10, spray the wheat seeds through a spraying system, and stir the seeds during the spraying process. After coating, the seeds are dried by low-temperature hot air (below 40°C) to reduce the moisture content to 8%.

[0072] Comparative Example 2

[0073] ①Dissolve 100 g of PEG-PCL in dichloromethane (DCM), add 6.95 g of thiamethoxam, 1 g of azoxystrobin, 0.05 g of indole-3-butyric acid and 2 g of nano-metal zinc oxide, ultrasonically disperse evenly, and drop the above solution into the aqueous phase containing 1% Tween-80 under stirring to form a stable emulsion.

[0074] ②Stir in a 40°C water bath for 4 h, evaporate DCM, centrifuge to collect the microspheres, wash 3 times with deionized water, disperse the solid matter in 3% calcium chloride aqueous solution and impregnate for 4 h, filter off the solvent by suction, and freeze-dry for 12 h to obtain Ca 2+ —core microspheres.

[0075] ③Disperse the Ca 2+ —core microspheres in water at a ratio of 1:10, and perform ultrasonic treatment (20 kHz, 3 min) to prevent agglomeration; add 0.01% sodium carboxymethylcellulose to enhance the suspension stability, and mix evenly to obtain a comparative suspension pesticide composition.

[0076] ④Treat vegetable seeds with low-temperature plasma (power 50 W, treatment time 15 s), assemble the comparative suspension pesticide composition prepared in step ③ into a seed coating machine, with a liquid-solid ratio of 1:15, spray the seeds through a spray system, and stir the seeds during the spraying process. After coating, the seeds are dried with low-temperature hot air (below 40 °C) to reduce the moisture content to 10%.

[0077] Comparative Example 3

[0078] ①Dissolve 100 g of PEG-PCL in dichloromethane (DCM), add 6.95 g of thiamethoxam, 1 g of azoxystrobin, 0.05 g of indole-3-butyric acid, and 2 g of nano-metal zinc oxide, ultrasonically disperse evenly, and drop the above solution into the aqueous phase containing 1% Tween-80 under stirring to form a stable emulsion.

[0079] ②Stir in a 40 °C water bath for 4 h, volatilize DCM, centrifuge to collect the microspheres, wash 3 times with deionized water, and freeze-dry for 12 h to obtain the core microspheres.

[0080] ③Slowly add 1 g of chitosan to 50 ml of 1% acetic acid solution and stir until completely dissolved to obtain a chitosan solution; dissolve 2.5 g of sodium alginate in 50 ml of deionized water and stir until completely dissolved to obtain a sodium alginate solution. Mix the chitosan solution and the sodium alginate solution in a volume ratio of 1:1 to form a solution system. Disperse 12 g of core microspheres in the solution system, stir at 400 rpm for 30 min, centrifuge, wash, and freeze-dry after gelation to obtain the comparative core-shell structured active particles.

[0081] ④Disperse the comparative core-shell structured active particles in water at a ratio of 1:10, and perform ultrasonic treatment (20 kHz, 3 min) to prevent agglomeration; add 0.01% sodium carboxymethylcellulose to enhance the suspension stability, and mix evenly to obtain the comparative suspension pesticide composition.

[0082] ⑤Treat vegetable seeds with low-temperature plasma (power 50 W, treatment time 15 s), assemble the comparative suspension pesticide composition prepared in step ④ into a seed coating machine, with a liquid-solid ratio of 1:15, spray the seeds through a spray system, and stir the seeds during the spraying process. After coating, the seeds are dried with low-temperature hot air (below 40 °C) to reduce the moisture content to 10%.

[0083] Comparative Example 4

[0084] ①Dissolve 100 g of PEG-PCL in dichloromethane (DCM), add 6.95 g of thiamethoxam, 1 g of azoxystrobin, 0.05 g of indole-3-butyric acid, ultrasonically disperse evenly, and drop the above solution into the aqueous phase containing 1% Tween-80 under stirring to form a stable emulsion.

[0085] ② Stir in a 40 °C water bath for 4 h, evaporate DCM, centrifuge to collect the microspheres, wash them 3 times with deionized water, disperse the solid matter in a 3% calcium chloride aqueous solution and impregnate for 4 h, filter to remove the solvent, and freeze-dry for 12 h to obtain Ca 2+ —core microspheres.

[0086] ③ Slowly add 1 g of chitosan to 50 ml of 1% acetic acid solution and stir until completely dissolved to obtain a chitosan solution; dissolve 2.5 g of sodium alginate in 50 ml of deionized water and stir until completely dissolved to obtain a sodium alginate solution. Mix the chitosan solution and the sodium alginate solution in a volume ratio of 1:1 to form a solution system. Disperse 12 g of Ca 2+ —core microspheres in the solution system, stir at 400 rpm for 30 min, centrifuge, wash and freeze-dry after gelation to obtain core-shell structured active particles.

[0087] ④ Disperse the core-shell structured active particles in water at a ratio of 1:10, and perform ultrasonic treatment (20 kHz, 3 min) to prevent agglomeration; add 0.01% sodium carboxymethylcellulose to enhance the suspension stability, and mix evenly to obtain a comparative suspension pesticide composition.

[0088] ⑤ Treat vegetable seeds by low-temperature plasma (power 50 W, treatment time 15 s), assemble the comparative suspension pesticide composition prepared in step ④ into a seed coating machine, with a liquid-solid ratio of 1:15, spray the seeds through a spray system, and stir the seeds during spraying. After coating, the seeds are dried by low-temperature hot air (below 40 °C) to reduce the moisture content to 10%.

[0089] Test example:

[0090] Collect the microspheres prepared in Examples 1-2 and Comparative Examples 2-3, and perform particle size testing using a laser particle size analyzer.

[0091] Perform sedimentation rate testing and long-term stability observation on the suspension pesticide compositions prepared in Examples 1-2 and Comparative Examples 1-3.

[0092] Perform in vitro release tests on the microspheres prepared in Examples 1-2 and Comparative Examples 2-3. Respectively test the release rate of the active ingredient at RH50% under the conditions of Ph = 7 ± 0.5, Ph = 5 ± 0.5, and Ph = 8 ± 0.5, as well as the release rates when RH is increased to 70% and 100%.

[0093] Table 1 Test statistical table of each example and comparative example

[0094] For Examples 1-2 and Comparative Examples 1-3, the prepared seeds were used to simulate acidic soil, alkaline soil, and neutral soil, and germination was induced under the conditions of temperature (20-25 °C) and humidity (0-24 h, RH < 50%; 24-72 h, maintaining RH at 75%-80%), and the germination rate was calculated. When the seedlings grew to a certain stage, the pathogen spore suspension was evenly sprayed on the seedlings with a sprayer, and the disease incidence was investigated after 30 days of moisture-preserving culture, and the incidence rate was calculated. 3-5 groups of repeated experiments were set up to reduce errors.

[0095] Table 2 Statistical table of seed germination rate and incidence rate of each example and comparative example

[0096] In summary, the core-shell structured active particles in the aqueous suspension pesticide composition of the present invention are composed of a composite gel shell of chitosan and sodium alginate, and an active ingredient core wrapped by a hydrophilic chain and a hydrophobic chain PEG-PCL block copolymer. They can reduce the release of active ingredients under dry conditions, avoid the loss of active ingredients, and reduce soil pollution. They can maintain a stable release rate of active ingredients in an environment with excessive humidity. At the same time, they can maintain the integrity of the particles in harsh soil environments such as acidic or alkaline, ensure the stability of the slow-release system, and extend the effective coverage protection days of the active ingredients. The active ingredients compounded with pesticide active ingredients and metal oxides can significantly improve the germination rate and tolerance of crops. At the same time, the doping of calcium ions enhances the mechanical strength of the composite gel and the adhesion strength between the shell layer and the core, thereby improving the stability of the shell layer in acidic and alkaline environments.

[0097] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An aqueous suspension pesticide composition, characterized in that: The composition includes the following components: deionized water as solvent; 0.5-20w% of active particles of core-shell structure based on the mass of solvent; 0.01-5w% of suspension stabilizer based on the mass of solvent; The core-shell structure active microparticles are acid- and alkali-resistant humidity-responsive microspheres, and the core-shell structure active microparticles include a chitosan and sodium alginate composite gel shell and an active component core wrapped by a hydrophilic chain and a hydrophobic chain PEG-PCL block copolymer.

2. The aqueous suspension pesticide composition according to claim 1, characterized in that: The suspension stabilizer is one or more of sodium carboxymethyl cellulose, xanthan gum, guar gum and polyvinyl alcohol.

3. The aqueous suspension pesticide composition according to claim 1, characterized in that: The molecular weight of PEG is 2KDa, the molecular weight of PCL is 5KDa, and the PEG / PCL value is 8:2-2:

8.

4. The aqueous suspension pesticide composition according to claim 1, characterized in that: The core-shell structure active microparticles are prepared by the following steps: ① Dissolve PEG-PCL in dichloromethane (DCM), add pesticide active ingredients and nano-metal oxides, disperse evenly by ultrasonication, and drop the above solution into the aqueous phase containing 1% emulsifier under stirring to form a stable emulsion; ② Stir in a water bath at 40℃ for 4h to evaporate DCM, collect the microspheres by centrifugation, wash with deionized water 3 times, disperse the solid matter in a 3% calcium chloride aqueous solution and immerse for 3-6h, remove the solvent by suction, and freeze-dry for 12h to obtain Ca 2+ —Core microspheres; ③ Slowly add chitosan to 1% acetic acid solution and stir until completely dissolved to obtain chitosan solution; dissolve sodium alginate in deionized water and stir until completely dissolved to obtain sodium alginate solution; mix the chitosan solution and sodium alginate solution in a volume ratio of 1:1 to form a solution system; 2+ The core microspheres were dispersed in the solution system, stirred at 400 rpm for 30 min, centrifuged after gelation, washed and freeze-dried to obtain core-shell structured active microparticles.

5. The aqueous suspension pesticide composition according to claim 4, characterized in that: The active ingredients of the pesticide are one or more of tebuconazole, difenoconazole, fludioxonil, azoxystrobin, pyraclostrobin, imidacloprid, thiamethoxam, lambda-cyhalothrin, indolebutyric acid, naphthylacetic acid, and brassinolide.

6. The aqueous suspension pesticide composition according to claim 4, characterized in that: The nano metal oxide is one or more of zinc oxide, titanium oxide, copper oxide and cerium oxide.

7. The aqueous suspension pesticide composition according to claim 4, characterized in that: The emulsifier is one or more of Tween-20, Tween-80, Tween-60, Span-20, and Span-80.

8. A method for treating angiosperm seeds, characterized in that: Using the aqueous suspension pesticide composition described in any one of claims 1 to 7, firstly treat angiosperm seeds by low-temperature plasma, then assemble the aqueous suspension pesticide composition into a seed coating machine, with a liquid-to-solid ratio of 1:5-1:10, spray the seeds through a spray system, and stir the seeds during the spraying process. After coating, the seeds are dried by low-temperature hot air to reduce the moisture content of the seeds to 8% to 10%.

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