Aqueous suspension pesticide composition and treatment method for angiosperm seeds

Abstract

The present invention provides an aqueous suspension pesticide composition, comprising the following components: solvent deionized water; based on the mass of the solvent, 0.5 - 20 w% of core-shell structured active microparticles; based on the mass of the solvent, 0.01 - 5 w% of a suspension stabilizer; the core-shell structured active microparticles are humidity-responsive microspheres resistant to acids and alkalis. The present invention uses core-shell structured active microparticles to reduce the intermolecular force, reduce particle aggregation, and improve the dispersibility of the active ingredient. Moreover, a natural polymer material is used as the outer shell, which has good biocompatibility and can be biodegradable, reducing environmental pollution. At the same time, the introduced PEG-PCL block copolymer can accurately control the pesticide release rate according to environmental humidity changes, improving the pesticide utilization rate. Furthermore, the chitosan-sodium alginate composite gel in the particle shell layer releases stably and slowly in neutral and weakly alkaline soils. In acidic and strongly alkaline environments, the microspheres are prevented from collapsing, improving the stability of the microparticle sustained-release system in soils with different pH values and expanding the applicable range of the active microparticles.

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, containing active ingredients, adjuvants, etc. Due to its high efficacy, long persistence, and being friendly to humans, livestock, and the environment, it has gradually replaced traditional pesticides and is widely used in agricultural pest control, plant growth regulation, etc. 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 slow-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 at the same time 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 objectives, the present invention is realized through the following technical solutions: An aqueous suspension pesticide composition includes 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 PEG has a molecular weight of 2 KDa, the PCL has a molecular weight of 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 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 40 °C water bath 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, and 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.

[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-mentioned aqueous suspension pesticide composition. First, the angiosperm seeds are treated by low-temperature plasma, and then the aqueous suspension pesticide composition is assembled into a seed coating machine with a liquid-solid ratio of 1:5 - 1:10. The seeds are sprayed through a spray system and stirred 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, extending 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] Meanwhile, the introduced PEG-PCL block copolymer causes the hydrophilic chain to absorb water and swell when the humidity ≥ threshold, increasing the porosity of the nuclear membrane microspheres and 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 inactivation caused by the release of the active component under arid 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 releases stably and slowly 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, avoids microsphere collapse, improves the stability of the particle sustained-release system in different pH soils, and expands 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 the direct contact between the first and second features, or may include the situation where the first and second features are not 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 that the first feature is directly above and obliquely above the second feature, or merely indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "beneath" and "underneath" the second feature includes that the first feature is directly below and obliquely below the second feature, or merely indicates that the horizontal height of the first feature is lower than that of 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. Such repetition is for the purpose of simplification and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed. Furthermore, 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] On the one hand, 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 suspension stabilizer based on the mass of the solvent.

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

[0032] The above 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 component 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 ≥ threshold, the hydrophilic chains absorb water and swell, increasing the porosity of the core-shell microspheres and promoting the release of the active components. When the humidity < threshold, the hydrophilic and hydrophobic chains form a dense structure to seal the active components and prevent inactivation caused by the release of the active components under arid 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, ultrasonically disperse uniformly, and drop the above solution into the aqueous phase containing 1% emulsifier under stirring 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, indolebutyric 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 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 to form the core inward, 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 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 the 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 sodium alginate gel serve 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. Thus, the stability of the particles in different pH soils is improved, and the stress resistance of crops is enhanced.

[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 wrapped outside 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 angiosperm seeds by low-temperature plasma (power 50 W, treatment time 15 s), assemble the above-mentioned 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 through 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, ultrasonically disperse evenly, 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, centrifuge to collect the microspheres, wash 3 times with deionized water, disperse the solid matter in 3% calcium chloride aqueous solution and soak for 5 h, filter to remove the solvent, 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 particles.

[0061] ④ Disperse the core-shell structured active particles in water at a ratio of 1:10, 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.

[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 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%.

[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, disperse evenly by ultrasonic wave, 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 microspheres, wash 3 times with deionized water, disperse the solid substance 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 particles.

[0067] ④Disperse 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 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 spraying 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 spraying 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, 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 4 h, filter off the solvent by suction, 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 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%.

[0089] Test examples:

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

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

[0092] Conduct in vitro release tests on the microspheres prepared in Examples 1-2 and Comparative Examples 2-3. Respectively measure 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]

[0095] 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 moisturizing culture, and the incidence rate was calculated. 3-5 groups of repeated experiments were set up to reduce errors.

[0096] Table 2 Statistical table of seed germination rate and disease incidence of each example and comparative example

[0097]

[0098] In summary, it can be seen that 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 drought 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 sustained-release system, and extend the effective coverage protection days of the active ingredients. The active ingredient compounded by the pesticide active ingredient and metal oxide 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.

[0099] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand 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, It comprises 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 suspension stabilizer based on the mass of the solvent; Among them, the core-shell structured active particles are acid and alkali resistant humidity-responsive microspheres, and 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; The core-shell structured active particles are prepared by the following steps: ① Dissolve PEG-PCL in dichloromethane, add pesticide active ingredients and nano metal oxides, ultrasonically disperse evenly, and drop the above solution into the aqueous phase containing 1% emulsifier under stirring to form a stable emulsion; Among them, the concentration of the pesticide active ingredient is 3% - 10% w / w, based on PEG-PCL, specifically one or more of difenoconazole, fludioxonil, azoxystrobin, imidacloprid, thiamethoxam, indolebutyric acid; The concentration of the nano metal oxide is 0.3% - 10% w / w, based on PEG-PCL; ②Stir in a 40 °C water bath for 4 h, evaporate dichloromethane, 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 3 - 6 h, filter to remove the solvent, and freeze-dry for 12 h to obtain Ca 2+ —core microspheres; ③ Slowly add chitosan to 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 Ca 2+ —core microspheres in the solution system, stir at 400 rpm for 30 min, centrifuge, wash and lyophilize after gelation to obtain core-shell structured active microparticles; 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; The suspension stabilizer is one or more of sodium carboxymethyl cellulose, xanthan gum, guar gum, polyvinyl alcohol.

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

8.

3. The aqueous suspension pesticide composition according to claim 1, wherein: The nano metal oxide is one or more of zinc oxide, titanium oxide, copper oxide, cerium oxide.

4. The aqueous suspension pesticide composition according to claim 1, characterized in that: The emulsifier is one or more of Tween-20, Tween-80, Tween-60, Span-20, Span-80.

5. A method for treating angiosperm seeds, characterized in that, When using the aqueous suspension pesticide composition according to any one of claims 1-4, first treat the angiosperm seeds by low-temperature plasma, then assemble the 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 to reduce the seed moisture to 8% - 10%.

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