Preparation and application of microcapsule compounded with walnut green seedcase extract and lavender essential oil

Abstract

The invention discloses preparation and application of a microcapsule compounded with walnut green seedcase extract and lavender essential oil, and belongs to the technical field of botanical pesticides. The walnut green seedcase extract is prepared with an ultrasonic-assisted two-phase salting-out extraction method, lavender essential oil is compounded to serve as a core material, beta-cyclodextrin serves as a wall material, and the composite microcapsule which is good in slow release performance and has an efficient inhibition effect on botrytis cinerea is obtained with a composite coacervation method. The compound essential oil microcapsule based on the walnut green seedcase extract is a natural plant effective component, is an efficient, safe and slow-release plant source agricultural bactericide, and has a remarkable antibacterial effect on botrytis cinerea.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of plant source pesticides, and more particularly relates to preparation and application of walnut green husk extract compound lavender essential oil microcapsules. BACKGROUND

[0002] Various pathogenic bacteria cause great economic losses to agricultural production. Among them, Botrytis cinerea, as a widely existing plant pathogenic fungus, causes devastating damage to a variety of crops. Botrytis cinerea can infect more than 200 kinds of fruit and vegetable crops such as tomatoes, strawberries, cucumbers and grapes, causing gray mold disease, leading to crop yield reduction and quality decline. In the early stage of infection, Botrytis cinerea forms a layer of gray mold on the surface of plant tissue, which then rapidly expands, causing tissue necrosis and rot. Not only does it cause a large amount of crop damage during the field growth stage, but it also causes serious deterioration during the storage and transportation of agricultural products, resulting in huge economic losses. In addition, Botrytis cinerea also produces toxins, affecting the safety of agricultural products for consumption and posing a potential threat to human and animal health.

[0003] Walnut green husk is rich in juglone, flavonoids, polyphenols and naphthoquinone derivatives and other active ingredients. These ingredients have inhibitory effects on a variety of plant pathogenic fungi. However, the effective components extracted by different methods differ greatly, and the effective components in the extract are unstable, resulting in a significant decrease in the bacteriostatic effect. Studies have shown that plant essential oils have broad-spectrum antibacterial properties, but their application is limited due to their volatility and instability. Therefore, walnut green husk extract and essential oil are compounded to prepare microcapsules, which enhance the stability, slow-release performance and bacteriostatic effect of walnut green husk extract and essential oil through the protection mechanism of microcapsules, and realize the wide application of walnut green husk extract and essential oil in agricultural prevention and control.

[0004] In view of this, the present application is proposed. SUMMARY

[0005] The purpose of the present application is to provide a preparation and application of walnut green husk extract compound lavender essential oil microcapsules to solve the problems existing in the prior art. The walnut green husk extract and lavender essential oil are compounded and microencapsulated. The walnut green husk extract and lavender essential oil are wrapped with suitable wall materials, reducing their contact with the external environment, enhancing their stability, slow-release performance and bacteriostatic performance. At the same time, the compounded walnut green husk extract and lavender essential oil have a synergistic effect, exerting a better bacteriostatic effect. This process realizes the preparation of an environmentally friendly, non-toxic, biodegradable and environmentally friendly plant source pesticide.

[0006] To achieve the above purpose, the present application provides the following scheme:

[0007] One of the technical solutions of the present application: provide a kind of based on walnut green peel extract composite lavender essential oil microcapsule, the based on walnut green peel extract composite lavender essential oil microcapsule includes core material and wall material wrapped in core material outside;The preparation raw material of the core material includes walnut green peel extract and lavender essential oil;The preparation raw material of the wall material includes β-cyclodextrin.

[0008] Preferably, the mass ratio of walnut green peel extract and lavender essential oil is 1-3:3-5.

[0009] Preferably, the mass ratio of the core material and wall material is 1-4:1-3.

[0010] The second technical solution of the present application: provide the preparation method of the above based on walnut green peel extract composite lavender essential oil microcapsule, including the following steps:

[0011] Preparation of wall material: β-cyclodextrin is mixed with water, stirred and dissolved to form a wall material solution;

[0012] Preparation of core material: walnut green peel extract is dissolved in water, lavender essential oil is dissolved in ethanol, and then the two are mixed to form a core material mixture;

[0013] Composite microcapsule preparation: the core material mixture is added to the wall material solution, and stirred while adding, so that the core material mixture is uniformly wrapped in the wall material to form a microcapsule precursor;Then, calcium chloride solution is added, and stirring is continued to fully coagulate the wall material, to obtain the based on walnut green peel extract composite lavender essential oil microcapsule.

[0014] The present application prepares walnut green peel extract by ultrasonic-assisted two-phase salting-out extraction technology. β-cyclodextrin is mixed with water, stirred to fully dissolve, and a uniform solution is formed. Walnut green peel extract is dissolved in ultrapure water, lavender essential oil is dissolved in anhydrous ethanol, and then they are oscillated and mixed to form a core material mixture. The core material mixture is slowly added to the β-cyclodextrin solution, and stirred while adding, so that the core material mixture is uniformly wrapped in the wall material to form a microcapsule precursor;Then, calcium chloride solution is added, and stirring is continued to fully coagulate the wall material, to form stable composite microcapsules. After that, the above composite microcapsules are centrifuged to remove excess solution, and then washed with deionized water several times to remove unreacted raw materials and impurities. Finally, the obtained composite microcapsules are dried to obtain the final product.

[0015] Preferably, the walnut green peel extract is prepared by ultrasonic-assisted two-phase salting-out extraction technology;In the ultrasonic-assisted two-phase salting-out extraction technology: organic solvents include ethanol, ethyl acetate, cyclohexane or dichloromethane, and inorganic salts include ammonium sulfate, sodium phosphate or sodium chloride.

[0016] Preferably, the mass ratio of the organic phase and the salt phase in the ultrasonic-assisted two-phase salting-out extraction technology is 2-3:2-3; in the ultrasonic-assisted two-phase salting-out extraction technology, the extraction temperature is 30-50 DEG C, the solid-liquid ratio is 1-5:15-20 g / mL, the extraction time is 1-3 h, the ultrasonic time is 30-50 min, and the ultrasonic power is 200-800 W.

[0017] Preferably, the temperature for stirring and dissolving is 30-50 DEG C, and the time is 0.5-2 h; in the preparation of the core material, the mixing time is 10-30 min.

[0018] Preferably, in the preparation of the composite microcapsules, the stirring time is independently 30-50 min, the stirring temperature is independently 30-35 DEG C, the stirring speed is independently 200-650 rpm, and the mass percentage concentration of the calcium chloride solution is 10-15%.

[0019] Preferably, before obtaining the walnut green peel extract composite lavender essential oil microcapsules, centrifugation and drying steps are further included; the centrifugation speed is 6000-9000 rpm, and the time is 3-6 min; the drying temperature is 30-35 DEG C, and the time is 5-10 h.

[0020] Further, after the microcapsule precursor is mixed with the calcium chloride solution, the pH is adjusted to 4.3-4.8, and then stirring is performed; the stirring speed is 350-550 rpm, and the time is 10-60 min.

[0021] The third technical scheme of the present application provides the above-mentioned walnut green peel extract composite lavender essential oil microcapsules in the application in preventing and treating agricultural diseases, and the agricultural disease is an agricultural disease caused by Botrytis cinerea.

[0022] The walnut green peel extract composite lavender essential oil microcapsules have good sustained-release performance, have a significant inhibitory effect on Botrytis cinerea, and have high application value in the field of plant source pesticides.

[0023] The present application discloses the following technical effects:

[0024] The present application adopts the ultrasonic-assisted two-phase salting-out technology to extract effective components of walnut green peel, and the yield of the effective components and the antibacterial activity are significantly higher than those of other extraction methods; after the extract obtained by the method is microencapsulated with lavender essential oil, the antibacterial performance of the composite microcapsules is significantly higher than that of the walnut green peel extract and the lavender essential oil. It is shown that the walnut green peel extract and the lavender essential oil after compounding have a synergistic antibacterial effect, and the microencapsulation enhances the stability of the walnut green peel extract and the essential oil to the environment, avoids the situation that the initial release is too fast and the later release is insufficient, and thus better antibacterial effect is achieved. Attached Figure Description

[0025] Figure 1 To evaluate the yield and antibacterial effect of different methods for extracting effective components from walnut green husk;

[0026] Figure 2 The inhibitory effect of walnut green husk extract and different essential oil compounds on gray mold;

[0027] Figure 3 The encapsulation efficiency and drug loading of the composite microcapsules of walnut green peel extract and lavender essential oil prepared in Example 3 were determined.

[0028] Figure 4 The results are the test results of the sustained-release performance described in Example 3;

[0029] Figure 5 The test results for the antibacterial performance against Botrytis cinerea described in Example 4;

[0030] Figure 6 The test results show the control effect of the control effect on tomato gray mold described in Example 5;

[0031] Figure 7 The results are the test results of the control effect of the control effect on strawberry gray mold described in Example 6. Detailed Implementation

[0032] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0033] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0034] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0035] Many modifications and variations to the illustrative embodiments described herein will be apparent to those skilled in the art from consideration of the specification and practice of the subject technology. Additional embodiments of the technology will be apparent to those skilled in the art from consideration of the specification and practice of the subject technology. The specification and examples given herein are by way of illustration only and are not intended to limit the technology in any way.

[0036] As used herein, the terms "comprises", "comprising", "includes", "including", "has", "having" or the like are open-ended expressions that are intended to denote the presence of stated features, elements, integers, steps or the like, but do not preclude the presence or addition of one or more other features, elements, integers, steps, acts, objects, or the like.

[0037] It should be noted that the present application does not specifically describe the conventional operation means in the art, and is not the focus of the present application.

[0038] The application provides a green and efficient plant source pesticide preparation method, comprising a walnut green peel extract compound lavender essential oil microcapsule preparation and application, aiming at botrytis cinerea infection of tomato plants and strawberry plants.

[0039] The composite microcapsule powder has significant antibacterial activity, especially high inhibition effect on botrytis cinerea, and can be applied as a green and efficient plant source pesticide in the prevention and treatment of botrytis cinerea infection of tomato plants and strawberry plants. In use, the composite microcapsule powder is dissolved in water according to a certain proportion, stirred uniformly, and then prepared into a suspension, which is uniformly sprayed on the leaf, fruit and stem surface of the tomato plant or strawberry plant infected by botrytis cinerea by using a sprayer. The walnut green peel extract and lavender essential oil in the composite microcapsule are continuously released by the slow release effect of the microcapsule, which can effectively inhibit the growth and reproduction of botrytis cinerea, reduce the occurrence and spread of botrytis cinerea, and thus achieve the purpose of preventing and treating botrytis cinerea. Compared with traditional chemical pesticides, the plant source pesticide provided by the application is green, environmentally friendly, residue-free, friendly to the environment, safe for humans and animals, and can improve the stability and utilization efficiency of active ingredients, prolong the action time, reduce the frequency of use, reduce the cost of agricultural production, and has a wide application prospect.

[0040] The room temperature involved in the application is 25±5 DEG C.

[0041] Unless otherwise specified, the experimental methods described in the following examples and comparative examples of the application are conventional methods; and unless otherwise specified, the reagents and materials are commercially available products, and the source of the commercially available products does not affect the technical effects of the application.

[0042] Example 1

[0043] A method for preparing walnut green peel extract by using ultrasonic-assisted two-phase salting-out extraction technology:

[0044] The condition of the ultrasonic-assisted two-phase salting-out extraction technology is that the organic phase in the extraction system is selected as anhydrous ethanol.

[0045] The condition of the ultrasonic-assisted two-phase salting-out extraction technology is that the salt phase in the extraction system is selected as ammonium sulfate.

[0046] The condition of the ultrasonic-assisted two-phase salting-out extraction technology is that the mass percentage of the organic phase to the salt phase in the extraction system is 25:20.

[0047] The condition of the ultrasonic-assisted two-phase salting-out extraction technology is that the extraction temperature in the extraction system is 50℃, the solid-liquid ratio is 1:20 g / ml, the extraction time is 1.5 h, the ultrasonic time is 50 min, and the ultrasonic power is 600 W.

[0048] After the extraction is completed, the supernatant is collected by centrifugation at 8000 rpm for 5 min, the yield of each component is determined by ultraviolet spectrophotometry, and the supernatant is concentrated by using a rotary evaporator to 15% of the original volume, then anhydrous ethanol is added to the supernatant in an amount of 1.5 times the volume of the concentrated liquid, and the supernatant is precipitated for 3 h and then centrifuged at 4800 rpm for 10 min, and the supernatant is concentrated to a paste by using a rotary evaporator. The extract is collected, freeze-dried, and the walnut green peel extract is obtained.

[0049] The yield calculation formula is as follows:

[0050] In the formula, Yield is the yield, C is the effective ingredient concentration, mg / mL, V is the volume of the extraction liquid, mL, D is the dilution multiple, and M is the mass of the walnut green peel powder, g.

[0051] The following provides a comparative example of other extraction methods for extracting effective ingredients from walnut green peel:

[0052] Comparative Example 1

[0053] Immersion extraction: 70wt% anhydrous ethanol is used as the extraction solvent, the solid-liquid ratio is 1:20 g / mL, the extraction temperature is 60℃, the extraction time is 40 min, and then the filtrate is collected by filtration, the extraction liquid is concentrated at 40℃ under reduced pressure, and then freeze-dried to obtain the walnut green peel extract.

[0054] Comparative Example 2

[0055] Ultrasonic-assisted extraction: 70wt% anhydrous ethanol is used as the extraction solvent, the solid-liquid ratio is 1:20 g / mL, the ultrasonic temperature is 60℃, the ultrasonic power is 600 W, the ultrasonic time is 50 min, and then the filtrate is collected by filtration, the extraction liquid is concentrated at 40℃ under reduced pressure, and then freeze-dried to obtain the walnut green peel extract.

[0056] Comparative Example 3

[0057] Microwave-assisted extraction: 70wt% anhydrous ethanol was used as the extraction solvent, the solid-liquid ratio was 1:20 g / mL, the microwave temperature was 60℃, the microwave power was 200W, and the microwave time was 70min. After filtration, the filtrate was concentrated under reduced pressure at 40℃ and then freeze-dried to obtain the walnut green peel extract.

[0058] Comparative Example 4

[0059] Two-phase salting-out extraction (SOE): A 30% ethanol (w / w) / 19% ammonium sulfate (w / w) two-phase salting-out system was selected, the solid-liquid ratio was 1:20 g / mL, and the extraction was carried out at 30℃ for 1h. After standing for 30min, the upper phase was collected and centrifuged at 8000rpm for 5min. The remaining steps were the same as in Example 1.

[0060] Example 2

[0061] The antibacterial effect of a complex based on walnut green peel extract and different essential oils on Botrytis cinerea:

[0062] Step one: Preparation of the complex: Walnut green peel extract was mixed with lavender essential oil, cinnamon essential oil, tea tree essential oil, sweet orange essential oil, and rose essential oil at a ratio of 1:1 (mass ratio) to prepare a complex solution.

[0063] Step two: Minimum inhibitory concentration (MIC) determination: The MIC was determined by broth dilution method. 0.1mL of test bacterial solution with a concentration of 1×10 6 CFU / mL was inoculated into 9.9mL of nutrient broth medium containing different proportions of complex solution, so that the final mass concentration of the complex was 10, 5, 2.5, 1.25, 0.62, 0.31, 0.16, and 0.08mg / mL, respectively. A blank control (medium without complex) was set. Three replicates were set for each concentration. The medium was incubated in a 37℃ constant temperature incubator, and the bacterial growth was observed the next day. The lowest complex concentration without visible bacterial growth was recorded as the MIC.

[0064] Step three: Minimum bactericidal concentration (MFC) determination: The MFC was determined by broth dilution method, and the remaining operations were as shown in Step two. The bacterial growth was observed on the fifth day, and the lowest complex concentration without visible bacterial growth was recorded as the MFC.

[0065] Example 3

[0066] Step one: a preparation method of walnut green peel extract composite lavender essential oil microcapsules: walnut green peel extract is prepared by ultrasonic-assisted two-phase salting-out extraction technology; β-cyclodextrin is mixed with water, stirred at 35°C for 1h to fully dissolve, forming a uniform solution; walnut green peel extract is dissolved in ultrapure water, and lavender essential oil is dissolved in anhydrous ethanol, and the two are oscillated and mixed for 20min to form a core material mixture with a mass ratio of walnut green peel extract to lavender essential oil of 1:3; then, the mixed solution is slowly added to the β-cyclodextrin solution, and stirred at 30°C, with a stirring speed of 400rpm, so that the core material mixture is uniformly wrapped in the wall material to form a microcapsule precursor with a core-wall ratio of 2:1, then 10% calcium chloride solution is added and oscillated and stirred for 10min to make the wall material fully coagulate, forming stable composite microcapsules; then, the composite microcapsules are centrifuged at a speed of 8000rpm for 5min to remove excess solution, and washed several times with deionized water to remove unreacted raw materials and impurities; finally, the obtained composite microcapsules are dried at 35°C for 8h to obtain the final product.

[0067] Step two: determination of the embedding rate and drug loading of walnut green peel extract and lavender essential oil composite microcapsules: 0.05g of walnut green peel extract and lavender essential oil composite microcapsules with different wall material to core material mass ratios are dispersed in 50mL of petroleum ether, and the volume is made up with a 50mL volumetric flask. The mixed solution is ultrasonicated for 50min to dissolve the walnut green peel extract and lavender essential oil in the inclusion compound into petroleum ether. The solution is centrifuged at a speed of 8500r / min for 10min, and the supernatant is diluted and subjected to absorbance determination. The measured absorbance value is substituted into the standard curve y=0.846x+0.5603(R 2 =0.9918) to calculate the concentration of walnut green peel extract and lavender essential oil, which is converted to mass, and the average value of three parallel tests is taken.

[0068] Step three: determination of the sustained-release performance of walnut green peel extract and lavender essential oil composite microcapsules:

[0069] Sustained-release performance determination method: accurately weigh a certain mass of walnut green peel extract and lavender essential oil composite microcapsules in a reagent bottle, seal it, and place it at 25°C. Sample every few days. The content of the core material in the microcapsules is determined by ultraviolet spectrophotometry, and the relative cumulative release rate is calculated.

[0070] Example 4

[0071] The antibacterial effect of walnut green peel extract and lavender essential oil composite microcapsules on botrytis cinerea:

[0072] Step one: preparation of the composite microcapsule suspension: accurately weigh 1 g of the composite microcapsule powder, place it in a beaker, add 100 mL of ultrapure water, and stir with a glass rod to disperse the microcapsules thoroughly, to prepare a 1% (w / v) composite microcapsule suspension. At the same time, prepare a 1% (w / v) walnut green peel extract solution, a 1% (w / v) lavender essential oil solution, and a blank control solution without microcapsules.

[0073] Step two: determination of antibacterial performance by mycelial growth rate method: the strain is Botrytis cinerea, and the antibacterial activity is determined by the mycelial growth rate method. In the ultraclean bench after ultraviolet disinfection, the sample is taken and added to the sterilized 60 mL PDA medium, mixed thoroughly to prepare a drug plate containing 2 mg / mL of the drug, and the blank control is sterile water. A 0.5 cm diameter fungus cake is inoculated in the center of the drug plate, and dark culture is carried out in a 33°C constant temperature incubator. After 72 hours, the colony diameter is measured by cross method, and the antibacterial activity of walnut green peel extract (WGHE), lavender essential oil (LEO), mixture of walnut green peel extract and lavender essential oil (WGHE-LEO), and composite microcapsule of walnut green peel extract and lavender essential oil (WGHE-LEO / β-CD) on Botrytis cinerea is determined.

[0074] Example 5

[0075] A composite microcapsule based on walnut green peel extract and lavender essential oil for the prevention and treatment of tomato gray mold.

[0076] Step one: preparation of the composite microcapsule suspension according to step one of Example 3.

[0077] Step two: pot experiment for preventing and treating tomato gray mold: when the tomato seedlings grow to the flowering stage, artificial inoculation of Botrytis cinerea is carried out. The mycelial block inoculation method is used, and a 5 mm diameter puncher is used to take the well-grown Botrytis cinerea mycelial block on the PDA medium, and placed on the middle and lower leaf wound of the tomato seedling (the leaf wound is caused by a sterile needle). After the mycelial block grows stably, different agents are used for spraying treatment. When spraying, a sprayer is used to uniformly spray the drug solution until the leaf surface is completely wet but not dripping. The blank control group is sprayed with an equal amount of sterile water. After spraying the agents, the disease incidence of tomato plants is observed every day, and the observation is carried out for 3 days.

[0078] Step three: in vitro leaf experiment for preventing and treating tomato gray mold: select healthy, consistent growth tomato leaves, respectively, with the composite microcapsule suspension, walnut green skin extract solution, lavender essential oil solution sprayed on the surface of the leaves, until the leaves are wet but not dripping, and dry naturally. The blank control group is sprayed with the same amount of sterile water. The sprayed leaves are placed in a culture dish, and the mycelial block inoculation method is used. Fresh mycelial blocks with a diameter of 5 mm are taken from the cultured gray mold plate and placed upside down in the middle of each leaf. Each leaf is inoculated with 1 mycelial block, repeated 3 times. The inoculated culture dishes are placed in a 25°C, 95% relative humidity incubator to keep the leaves moist. From the first day after inoculation, observe for 3 days.

[0079] Example 6

[0080] A composite microcapsule based on walnut green skin extract and lavender essential oil for the prevention and treatment of strawberry gray mold. The difference from Example 5 is that the tomato plants are replaced by strawberry plants, and the others are the same as Example 5.

[0081] Calculation formula:

[0082] The formula for the embedding rate of walnut green skin extract and lavender essential oil is as follows:

[0083]

[0084] The drug loading rate formula is as follows:

[0085] The relative cumulative release rate formula is as follows:

[0086]

[0087] Result analysis:

[0088] Figure 1 For the yield of effective components of walnut green skin extracted by different methods and the bacteriostatic effect, the yield of polyphenols, juglone and flavonoids in the walnut green skin extract of Example 1 is significantly better than that of extraction, ultrasonic-assisted, microwave-assisted and two-phase salting-out extraction, and the inhibition effect on gray mold is also the strongest, which shows that the yield of effective components and the bacteriostatic effect of walnut green skin extract extracted by ultrasonic-assisted two-phase salting-out extraction are better than those of other methods.

[0089] Figure 2 For the inhibition effect of walnut green skin extract and different essential oil compounds on gray mold, the results show that the walnut green skin extract and lavender essential oil compound exhibit the most significant antibacterial activity against gray mold, with a MIC value of 0.62 mg / mL and a MFC value of 1.25 mg / mL.

[0090] Figure 3The embedding rate and drug loading of the complex microcapsules of the walnut green husk extract and lavender essential oil prepared in Example 3 were determined. The embedding rate of the complex microcapsules of the walnut green husk extract and lavender essential oil was 78.4%, and the drug loading was 53.5%, indicating that most of the core material was successfully wrapped inside the microcapsules, and the content of the core material in the microcapsules was relatively high, having good drug loading capacity.

[0091] Figure 4 The sustained-release performance of the complex microcapsules of the walnut green husk extract and lavender essential oil prepared in Example 3 was determined. As can be seen from the figure, the release speed of the complex microcapsules was relatively fast in the initial stage (0-4d), and the cumulative release percentage was about 22.5%; then the release speed gradually slowed down, and the cumulative release percentage was about 25.2% on the 8th day; thereafter, the release tended to be stable, and the release percentage was about 34.7% on the 16th day. Compared with the walnut green husk extract and lavender essential oil without wrapping, the complex microcapsules significantly prolonged the release time of the effective components (the cumulative release percentage of the walnut green husk extract and lavender essential oil complex was about 81.2% within 12d under the same conditions). This indicates that the complex microcapsules have good sustained-release performance, can effectively control the release of active ingredients, and prolong their action time.

[0092] Figure 5 The test results of the antibacterial performance of the complex microcapsules of the walnut green husk extract and lavender essential oil against Botrytis cinerea described in Example 4 show that the antibacterial decline rate of the WGHE-LEO / β-CD complex microcapsules was only 3.8%, which is much better than that of the walnut green husk extract and lavender essential oil alone. This indicates that microencapsulation can protect the effective components from the influence of environmental factors (such as temperature, humidity, and light), and maintain their stability and biological activity.

[0093] Figure 6 The test results of the control effect of the complex microcapsules of the walnut green husk extract and lavender essential oil on tomato gray mold described in Example 5 show that, according to the steps in Example 5, after the tomato plants and leaves were treated for 3 days, compared with the blank control group, the walnut green husk extract solution, lavender essential oil solution, and complex microcapsule suspension all had a certain control effect on tomato gray mold, but the control effect of the complex microcapsule suspension was the most significant. The tomato plants in the complex microcapsule suspension treatment group grew well, with obvious growth in plant height, increase in leaf number, and dark green and shiny leaves. In contrast, the tomato plants in the blank control group grew poorly, with yellow and withered leaves and rapid expansion of the disease spots. The growth of the plants in the walnut green husk extract solution and lavender essential oil solution treatment groups was between that in the blank control group and the complex microcapsule suspension treatment group.

[0094] Figure 7The results of the test on the control effect of strawberry gray mold disease described in Example 6 show that, according to the steps in Example 6, after treating the strawberry plants and leaves for 3 days, the compound microcapsule of walnut green peel extract and lavender essential oil has a significant control effect on strawberry gray mold disease. Compared with the use of walnut green peel extract or lavender essential oil alone, the compound microcapsule effectively reduces the lesion area, which indicates that the active ingredients in the compound microcapsule can better play a synergistic role under the protection of the microcapsule structure to inhibit the growth and expansion of Botrytis cinerea. As a kind of green and efficient botanical pesticide, the compound microcapsule has a good application prospect and provides a new method and idea for the green prevention and control of gray mold disease.

[0095] The various embodiments in the specification are described in a progressive manner, and each embodiment focuses on the difference from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0096] The above description of the disclosed embodiments enables a person skilled in the art to implement or use the present application. Various modifications to the embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A microcapsule based on walnut husk extract and lavender essential oil, characterized in that, The microcapsules based on walnut husk extract and lavender essential oil comprise a core material and a wall material encapsulating the core material; the raw materials for preparing the core material include walnut husk extract and lavender essential oil; the raw materials for preparing the wall material include β-cyclodextrin.

2. The microcapsules based on walnut husk extract and lavender essential oil according to claim 1, characterized in that, The mass ratio of the walnut husk extract to the lavender essential oil is 1-3:3-5.

3. The microcapsules based on walnut husk extract and lavender essential oil according to claim 1, characterized in that, The mass ratio of the core material to the wall material is 1-4:1-3.

4. The preparation method of microcapsules based on walnut green peel extract and lavender essential oil according to any one of claims 1 to 3, characterized in that, Includes the following steps: Preparation of wall material: Mix β-cyclodextrin with water, stir to dissolve, and form a wall material solution; Preparation of core material: Dissolve walnut green peel extract in water and lavender essential oil in ethanol, then mix the two to form a core material mixture; Preparation of composite microcapsules: The core material mixture is added to the wall material solution while stirring, so that the core material mixture is uniformly coated in the wall material to form the precursor of microcapsules; then calcium chloride solution is added and stirring is continued to allow the wall material to fully solidify, thereby obtaining the microcapsules based on walnut green peel extract and lavender essential oil.

5. The preparation method according to claim 4, characterized in that, The walnut green peel extract was prepared by ultrasound-assisted two-phase salting-out extraction technology; in the ultrasound-assisted two-phase salting-out extraction technology: the organic solvent includes ethanol, ethyl acetate, cyclohexane or dichloromethane, and the inorganic salt includes ammonium sulfate, sodium phosphate or sodium chloride.

6. The preparation method according to claim 5, characterized in that, In the ultrasound-assisted two-phase salting-out extraction technology, the mass ratio of the organic phase to the salt phase is 2-3:2-3; in the ultrasound-assisted two-phase salting-out extraction technology, the extraction temperature is 30-50℃, the material-liquid ratio is 1-5:15-20g / mL, the extraction time is 1-3h, the ultrasonic time is 30-50min, and the ultrasonic power is 200-800W.

7. The preparation method according to claim 4, characterized in that, The stirring and dissolving temperature is 30–50°C, and the time is 0.5–2 h; the mixing time in the preparation of the core material is 10–30 min.

8. The preparation method according to claim 4, characterized in that, In the preparation of the composite microcapsules: the stirring time is 30-50 min, the stirring temperature is 30-35℃, the stirring speed is 200-650 rpm, and the mass percentage concentration of the calcium chloride solution is 10-15%.

9. The preparation method according to claim 4, characterized in that, Before obtaining the microcapsules based on walnut green peel extract and lavender essential oil, the process includes centrifugation and drying steps; the centrifugation speed is 6000-9000 rpm and the time is 3-6 min; the drying temperature is 30-35℃ and the time is 5-10 h.

10. The application of the microcapsules based on walnut green husk extract and lavender essential oil as described in any one of claims 1 to 3 in the prevention and control of agricultural diseases, characterized in that, The agricultural disease mentioned is an agricultural disease caused by gray mold.

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