Plant-source nano-composite bactericide as well as preparation method and application thereof

Abstract

The invention relates to the technical field of plant sterilization and preservation, in particular to a plant source nano-composite bactericide and a preparation method and application thereof.The plant source nano-composite bactericide is prepared from, by mass, 1 part of fig leaf composite bactericide, 1 part of nano-silver solution and 1 part of chitosan solution; wherein the fig leaf composite bactericide is composed of a fig leaf extracting solution mother solution and an amoxicillin diluent. According to the plant-source nano-composite bactericide, green prevention and treatment of postharvest diseases of muskmelons are carried out through the synergistic effect of the plant-source bacteriostatic agent and the chemical bactericide, and the plant-source nano-composite bactericide has multiple functions of obviously reducing rotting of the muskmelons, reducing water loss, increasing glossiness of muskmelon skins and the like and is suitable for postharvest storage and fresh keeping of the muskmelons.

Description

Technical Field

[0001] The invention relates to the technical field of plant sterilization and fresh-keeping, and is a plant-derived nano composite bactericide and a preparation method and application thereof. Background Art

[0002] Amixid (a commercial formulation of azoxystrobin) is a broad-spectrum fungicide. In the early stages of the development and research of strobilurin fungicides, studies on their inherent resistance risk suggested that this type of fungicide had a medium resistance risk. However, in reality, resistance developed after two years of use of this type of fungicide and the control effect was significantly reduced.

[0003] Fusarium spp. is a pathogen of many important crops. It can not only cause serious losses in crop yield and quality, but also produce secondary metabolites of Fusarium toxins under in vitro culture conditions or in plant hosts, seriously affecting food safety. The main pathogenic fungi of postharvest rot in different thick-skinned melon varieties in Xinjiang were identified and analyzed for diversity. It was found that the postharvest pathogenic fungal colonies of melons have rich diversity, with Fusarium being dominant. In addition to causing postharvest rot, Fusarium can produce a variety of mycotoxins such as deoxynivalenol, zearalenone, and fumonisin due to metabolism, which endangers the safety of melons. At present, the inhibition of postharvest Fusarium in melons is mainly dominated by chemical pesticides. The use of chemical pesticides can easily lead to problems such as deterioration of melon quality, environmental pollution, and resistance of pathogens.

[0004] Therefore, it is imperative to develop plant material extracts with better antibacterial effects and mix them with chemical fungicides to reduce the toxic effects and drug resistance problems of chemical fungicides, achieve the synergistic inhibition of the harm of Fusarium, and develop a new type of high-efficiency and low-toxic plant-based compound fungicide. Summary of the invention

[0005] The present invention provides a plant-derived nanocomposite fungicide, which overcomes the deficiencies of the prior art and can effectively solve the problems of large dosage of fungicides used in the prior art for preserving fruits and vegetables and drug resistance.

[0006] One of the technical solutions of the present invention is achieved through the following measures: a plant-based nano-composite fungicide, the raw materials of which include, by mass, 1 part of a fig leaf composite fungicide, 1 part of a nano-silver solution and 1 part of a chitosan solution; wherein the fig leaf composite fungicide is composed of a fig leaf extract mother liquor and an Amisida dilution solution.

[0007] The following is a further optimization and / or improvement of one of the above-mentioned technical solutions: The above-mentioned fig leaf composite fungicide is obtained by mixing the fig leaf extract mother liquor and the Amicid dilution liquid in a mass ratio of 6:1 to 3:1, the concentration of myclobutanil in the Amicid dilution liquid is 0.5g / L, and the concentration of the fig leaf extract mother liquor is 1g / mL.

[0008] The mass fraction of the chitosan solution is 0.5% to 1%.

[0009] The concentration of the nanosilver solution is 1 μmol / L to 3 μmol / L.

[0010] The above-mentioned plant-derived nanocomposite fungicide is prepared by the following method: Step 1, extracting fig leaves with ethanol, concentrating the extract to obtain a fig leaf extract mother liquor, measuring an Amicid solution, adding it to sterile distilled water to obtain an Amicid diluted solution with a concentration of 0.5 g / L of myclobutanil, mixing the fig leaf extract mother liquor and the Amicid diluted solution in a ratio of 6:1 to 3:1 to obtain a fig leaf composite fungicide; Step 2, taking a required amount of silver nitrate particles, adding them into sterile water, stirring evenly, and ultrasonically treating to obtain a nanosilver solution; Step 3, taking a required amount of chitosan and adding it to a glacial acetic acid solution, adding Tween, filtering and removing insoluble matter after dissolving, to obtain a chitosan solution, wherein the volume fraction of the glacial acetic acid solution is 0.5%; Step 4: Mix the fig leaf composite fungicide, the nano silver solution and the chitosan solution in a mass ratio of 1:1:1 to obtain a plant-derived nano composite fungicide.

[0011] In the above step 3, the amount of Tween added is 0.5 mL per 100 mL of glacial acetic acid solution.

[0012] In the above step 1, the steps of preparing the fig leaf extract mother liquor include: The first step is to wash, dry and crush the fig leaves to obtain fig leaf dry powder; The second step is to use ethanol to ultrasonically extract the fig leaves to obtain a fig leaf extract, wherein the volume fraction of ethanol is 75% to 85%; The third step is to concentrate the fig leaf extract to remove ethanol from the fig leaf extract, and dissolve the concentrate with sterile water to obtain a fig leaf extract mother solution with a concentration of 1 g / mL.

[0013] In the above second step, the ultrasonic time is 30 min to 40 min, and the extraction temperature is 30° C. to 40° C.

[0014] In the above second step, the material-liquid ratio is 1:20 to 1:30.

[0015] The second technical solution of the present invention is achieved by the following measures: A method for preparing a plant-derived nanocomposite fungicide comprises the following steps: Step 1, extracting fig leaves with ethanol, concentrating the extract to obtain a fig leaf extract mother liquor, measuring an Amicid solution, adding it to sterile distilled water to obtain an Amicid diluted solution with a concentration of 0.5 g / L of myclobutanil, mixing the fig leaf extract mother liquor and the Amicid diluted solution in a ratio of 6:1 to 3:1 to obtain a fig leaf composite fungicide; Step 2, taking a required amount of silver nitrate particles, adding them into sterile water, stirring evenly, and ultrasonically treating to obtain a nanosilver solution; Step 3, taking a required amount of chitosan and adding it to a glacial acetic acid solution, adding Tween, filtering and removing insoluble matter after dissolving, to obtain a chitosan solution, wherein the volume fraction of the glacial acetic acid solution is 0.5%; Step 4: Mix the fig leaf composite fungicide, the nano silver solution and the chitosan solution in a mass ratio of 1:1:1 to obtain a plant-derived nano composite fungicide.

[0016] The third technical solution of the present invention is achieved through the following measures: application of a plant-derived nano-composite fungicide in melon preservation.

[0017] The plant-derived nanocomposite fungicide of the present invention utilizes the synergistic effect of plant-derived antibacterial agents and chemical fungicides to carry out green prevention and control of post-harvest melon diseases, and can significantly reduce melon rot, reduce water loss, increase the glossiness of the melon skin and other functions, and is suitable for post-harvest storage and preservation of melons. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Attached Figure 1 This is a schematic diagram of the effect of the composite treatment in Example 17 of the present invention on the residual amount of myclobutanil during the storage period of melons.

[0019] Attached Figure 2 This is a diagram showing the broad-spectrum antibacterial effect of the combination of fig leaf extract and Amiside in Example 18 of the present invention.

[0020] Attached Figure 3 This is a diagram showing the inhibitory effect of diameter of the composite preparation of fig extract in Example 19 of the present invention in the second year of storage.

[0021] Attached Figure 4 This is a diagram showing the antibacterial effect of nanosilver concentration screening in Example 20 of the present invention.

[0022] Attached Figure 5 Schematic diagram of the effect of single and composite nanoformulations in Example 21 of the present invention on the antibacterial diameter of major post-harvest fungi in melon.

[0023] Attached Figure 6Schematic diagram of the effect of single and composite nanoformulations on the diameter of the inhibition zone of melon inoculated with fungi in Example 22 of the present invention. DETAILED DESCRIPTION

[0024] The present invention is not limited by the following embodiments, and the specific implementation method can be determined according to the technical scheme of the present invention and the actual situation. Unless otherwise specified, the various chemical reagents and chemicals mentioned in the present invention are all chemical reagents and chemicals known and used in the prior art; unless otherwise specified, the percentages in the present invention are all mass percentages; unless otherwise specified, the solutions in the present invention are all aqueous solutions with water as the solvent, for example, hydrochloric acid solution is a hydrochloric acid aqueous solution; the normal temperature and room temperature in the present invention generally refer to a temperature of 15°C to 25°C, and are generally defined as 25°C.

[0025] The present invention will be further described below in conjunction with embodiments: Example 1: The plant-derived nano-composite fungicide comprises, by weight, 1 part of a fig leaf composite fungicide, 1 part of a nano-silver solution and 1 part of a chitosan solution; wherein the fig leaf composite fungicide is composed of a fig leaf extract mother liquor and an Amisida diluent.

[0026] Example 2: As an optimization of the above example, the fig leaf composite fungicide is obtained by mixing the fig leaf extract mother liquor and the Amisida dilution in a mass ratio of 6:1 to 3:1, the concentration of myclobutanil in the Amisida dilution is 0.5 g / L, and the concentration of the fig leaf extract mother liquor is 1 g / mL (i.e., 1 mL of mother liquor is obtained after 1 g of fig leaf is extracted).

[0027] Example 3: As an optimization of the above example, the mass fraction of the chitosan solution is 0.5% to 1%.

[0028] Example 4: As an optimization of the above example, the concentration of the nanosilver solution is 1 μmol / L to 3 μmol / L.

[0029] Example 5: As an optimization of the above example, a plant-derived nanocomposite fungicide was prepared according to the following method: Step 1: extracting fig leaves with ethanol, concentrating the extract to obtain a fig leaf extract mother liquor; measuring an Amicid solution, adding it to sterile distilled water, and obtaining an Amicid diluted solution with a concentration of 0.5 g / L of myclobutanil; mixing the fig leaf extract mother liquor and the Amicid diluted solution in a ratio of 6:1 to 3:1 to obtain a fig leaf composite fungicide; Step 2, taking a required amount of silver nitrate particles, adding them into sterile water, stirring evenly, and ultrasonically treating to obtain a nanosilver solution; Step 3, taking a required amount of chitosan and adding it to a glacial acetic acid solution, adding Tween, filtering and removing insoluble matter after dissolving, to obtain a chitosan solution, wherein the volume fraction of the glacial acetic acid solution is 0.5%; Step 4: Mix the fig leaf composite fungicide, the nano silver solution and the chitosan solution in a mass ratio of 1:1:1 to obtain a plant-derived nano composite fungicide.

[0030] Example 6: As an optimization of the above example, in step 3, the amount of Tween added is 0.5 mL per 100 mL of glacial acetic acid solution.

[0031] Example 7: As an optimization of the above example, in step 1, the steps of preparing the mother liquor of fig leaf extract include: The first step is to wash, dry and crush the fig leaves to obtain fig leaf dry powder; The second step is to use ethanol to ultrasonically extract the fig leaves to obtain a fig leaf extract, wherein the volume fraction of ethanol is 75% to 85%; The third step is to concentrate the fig leaf extract to remove ethanol from the fig leaf extract, and dissolve the concentrate with sterile water to obtain a fig leaf extract mother solution with a concentration of 1 g / mL.

[0032] Example 8: As an optimization of the above example, in the second step, the ultrasonic time is 30 min to 40 min, and the extraction temperature is 30°C to 40°C.

[0033] Example 9: As an optimization of the above example, in the second step, the material-liquid ratio (mass volume ratio of fig leaves and ethanol) is 1:20 to 1:30.

[0034] Example 10: Application of the plant-derived nanocomposite fungicide in melon preservation.

[0035] Example 11: The plant-derived nanocomposite fungicide is prepared by the following method: Preparation of fig leaf extract mother liquor: the collected fig leaves are repeatedly rinsed with clean water and dried, dried in a constant temperature drying oven at 70°C to constant weight, crushed into powder with a universal grinder, and passed through an 80-mesh sieve to obtain fig leaf dry powder; the fig leaf dry powder is extracted with 80% ethanol by volume, 4g of fig leaf dry powder is weighed into a 100mL conical flask, the solid-liquid ratio is 4g:100mL, placed in an ultrasonic cell crusher, and extracted at 35°C for 40min; after the extraction is completed, the fig leaf extract is filtered through filter paper, and the filtrate is placed in a rotary evaporator for reduced pressure distillation to eliminate the influence of the extraction solvent ethanol, and after distillation, the volume is fixed with sterile high-purity water to obtain a fig leaf extract mother liquor with a concentration of 1g / mL, which is stored in a refrigerator at 4°C for standby use.

[0036] Preparation of Amicida dilution: Measure 1 mL of Amicida solution, add it into 500 mL of sterile distilled water, stir evenly, and degas by ultrasonication for 30 minutes to obtain an Amicida dilution with a concentration of 0.5 g / L of myclobutanil.

[0037] Preparation of fig leaf compound fungicide: Mix the fig leaf extract mother liquor and the Amicida dilution liquid in a mass ratio of 5:1, stir evenly, and then obtain the fig leaf compound fungicide.

[0038] Preparation of nanosilver solution: Weigh 34 mg of silver nitrate particles, add into 100 mL of sterile distilled water, stir evenly, and degas by ultrasonic for 30 min to obtain 2 μmol / L nanosilver solution.

[0039] Preparation of chitosan solution: Weigh 0.7 g of chitosan and add it to 100 ml of 0.5% by volume glacial acetic acid solution, and add 0.5 mL of Tween to dissolve it. After ultrasonic degassing, filter to remove insoluble matter to prepare a chitosan solution with a mass fraction of 0.7%.

[0040] Preparation of plant-derived nano-composite fungicide: Fig leaf composite fungicide, nano-silver solution and chitosan solution were mixed in a ratio of 1:1:1, stirred evenly, and ultrasonically degassed for 30 minutes to obtain the plant-derived nano-composite fungicide.

[0041] Example 12: The plant-derived nanocomposite fungicide is prepared by the following method: Preparation of fig leaf extract mother liquor: the collected fig leaves are repeatedly rinsed with clean water and dried, dried in a constant temperature drying oven at 70°C to constant weight, crushed into powder with a universal grinder, and passed through an 80-mesh sieve to obtain fig leaf dry powder; the fig leaf dry powder is extracted with 75% volume fraction ethanol, 3.5g of fig leaf dry powder is weighed into a 100mL conical flask, the solid-liquid ratio is 3.5g:100mL, placed in an ultrasonic cell crusher, and extracted at 40°C for 30min; after the extraction is completed, the fig leaf extract is filtered through filter paper, and the filtrate is placed in a rotary evaporator for reduced pressure distillation to eliminate the influence of the extraction solvent ethanol, and after distillation, the volume is fixed with sterile high-purity water to obtain a fig leaf extract mother liquor with a concentration of 1g / mL, which is stored in a refrigerator at 4°C for later use.

[0042] Preparation of Amicida dilution: Measure 1 mL of Amicida solution, add it into 500 mL of sterile distilled water, stir evenly, and degas by ultrasonication for 30 minutes to obtain an Amicida dilution with a concentration of 0.5 g / L of myclobutanil.

[0043] Preparation of fig leaf compound fungicide: Mix the fig leaf extract mother liquor and the Amicida dilution liquid in a mass ratio of 4:1, stir evenly, and then obtain the fig leaf compound fungicide.

[0044] Preparation of nanosilver solution: Weigh 51 mg of silver nitrate particles, add into 100 mL of sterile distilled water, stir evenly, and degas by ultrasonic for 30 min to obtain 3 μmol / L nanosilver solution.

[0045] Preparation of chitosan solution: Weigh 0.5 g of chitosan and add it to 100 ml of 0.5% by volume glacial acetic acid solution, and add 0.5 mL of Tween to dissolve it. After ultrasonic degassing, filter to remove insoluble matter to prepare a chitosan solution with a mass fraction of 0.5%.

[0046] Preparation of plant-derived nano-composite fungicide: Fig leaf composite fungicide, nano-silver solution and chitosan solution were mixed in a ratio of 1:1:1, stirred evenly, and ultrasonically degassed for 30 minutes to obtain the plant-derived nano-composite fungicide.

[0047] Example 13: The plant-derived nanocomposite fungicide is prepared by the following method: Preparation of fig leaf extract mother liquor: the collected fig leaves are repeatedly rinsed with clean water and dried, dried in a constant temperature drying oven at 70°C to constant weight, crushed into powder with a universal grinder, and passed through an 80-mesh sieve to obtain fig leaf dry powder; the fig leaf dry powder is extracted with 80% ethanol by volume, 5g of fig leaf dry powder is weighed into a 100mL conical flask with a solid-liquid ratio of 5g:100mL, placed in an ultrasonic cell crusher, and extracted at 35°C for 30min; after the extraction is completed, the fig leaf extract is filtered through filter paper, and the filtrate is placed in a rotary evaporator for reduced pressure distillation to eliminate the influence of the extraction solvent ethanol, and after distillation, the volume is fixed with sterile high-purity water to obtain a fig leaf extract mother liquor with a concentration of 1g / mL, which is stored in a refrigerator at 4°C for later use.

[0048] Preparation of Amicida dilution: Measure 1 mL of Amicida solution, add it into 500 mL of sterile distilled water, stir evenly, and degas by ultrasonication for 30 minutes to obtain an Amicida dilution with a concentration of 0.5 g / L of myclobutanil.

[0049] Preparation of fig leaf compound fungicide: Mix the fig leaf extract mother liquor and the Amicida dilution liquid in a mass ratio of 6:1, stir evenly, and then obtain the fig leaf compound fungicide.

[0050] Preparation of nanosilver solution: Weigh 17 mg of silver nitrate particles, add into 100 mL of sterile distilled water, stir evenly, and ultrasonically degas for 30 min to obtain 1 μmol / L nanosilver solution.

[0051] Preparation of chitosan solution: Weigh 0.9 g of chitosan and add it to 100 ml of 0.5% glacial acetic acid solution, and add 0.5 mL of Tween to dissolve it. After ultrasonic degassing, filter to remove insoluble matter to prepare a chitosan solution with a mass fraction of 0.9%.

[0052] Preparation of plant-derived nano-composite fungicide: Fig leaf composite fungicide, nano-silver solution and chitosan solution were mixed in a ratio of 1:1:1, stirred evenly, and ultrasonically degassed for 30 minutes to obtain the plant-derived nano-composite fungicide.

[0053] Example 14: Optimization of Extraction Process of Fig Leaf Extract The response surface methodology was used to optimize the effects of ethanol concentration, ultrasonic time, and solid-liquid ratio on the total flavonoids yield of fig leaf extract. The optimal extraction process conditions obtained by design expert software were: ethanol concentration 79.73%, ultrasonic time 36.81min, solid-liquid ratio 1:24, theoretical yield 1.57785mg / g, experimental result 1.5325mg / g, actual yield and theoretical yield relative error 2.96%, the two are close, so the response surface design results are accurate and reliable. The optimal extraction process parameters of fig leaf extract were determined as follows: ethanol volume percentage 79.73%, ultrasonic time 36.81min, solid-liquid ratio 1:24. The response surface analysis scheme and results are shown in Table 1, and the regression model variance analysis and results are shown in Table 2.

[0054] Example 15: Screening of compounding of fig leaf extract with commercially available chemical fungicides: The antibacterial zone diameter method was used to compound the commercially available chemical fungicides prochloraz, tebuconazole, oxazolidinone, cymoxanil, fenpropimorph hydrochloride, difenoconazole, pyraclostrobin, and amisida with fig leaf extract, and the antibacterial test was carried out with Fusarium equiseti as the target. The test results are shown in Table 3. After the different commercial fungicides were diluted 500 times, they all had obvious inhibitory effects on Fusarium, and the inhibitory effects were different. However, after the fungicides were compounded with fig leaf extract in a 1:1 ratio, the inhibitory effects of each fungicide were weakened due to the decrease in the concentration of the agent. However, after the amisida solution was compounded with the fig leaf extract, a significant synergistic effect occurred, which increased by 14.88% compared with the single agent of amisida after compounding. Therefore, it was determined that the synergistic effect of the compounding of fig leaf extract and amisida was the most obvious.

[0055] Example 16: Study on the synergistic effect of the combination of fig leaf extract and Amicid The Wadley method was used to determine the effect of the compound agent. After the mother liquor of fig leaf extract and the dilution solution of Amisida (500 times) were mixed in the ratios of 6:1, 3:1, 1:1, 1:3 and 1:6, the concentrations of the active ingredients were designed to be 50.0000μg / mL, 25.0000μg / mL, 12.5000μg / mL, 6.2500μg / mL, 3.1250μg / mL and 1.5625μg / mL by the multiple dilution method. F. equiseti ) were 1.85, 1.60, 1.33, 1.08, and 0.96, respectively. The fig leaf extract showed an obvious synergistic effect, among which the 6:1 mixed combination had the largest synergistic coefficient (as shown in Table 4); F. solani ) were 1.686, 2.052, 1.056, 1.591, and 1.369, respectively. Fig leaf extract also played a significant synergistic role, among which the 3:1 mixed combination had the largest synergistic coefficient (as shown in Table 5). This shows that the combination of fig leaf extract and Amicida has a significant synergistic effect in inhibiting the fungus Fusarium during the storage period of melons.

[0056] Example 17: Application effect of composite fungicide for fig leaves with reduced application and increased efficiency The residual amount of azoxystrobin in the pulp of melons treated with Amisida dilution (500 times) and a 3:1 composite of fig leaf extract and Amisida dilution (500 times) was detected by high performance liquid chromatography during storage. The test results are as follows Figure 1 As shown, with the extension of treatment time, the content of myclobutanil in the melon pulp treated with Amisida gradually increased, while the combination of fig leaf extract and Amisida reduced the dosage of the agent by 66.67% compared with the single chemical fungicide Amisida treatment, and the pesticide residue was significantly reduced, reducing the pesticide residue by 65.6% to 78.2%.

[0057] Example 18: Determination of broad-spectrum antibacterial activity of the fig leaf composite fungicide: The antibacterial activity of the fig leaf compound fungicide on post-harvest melon pathogens was tested by using the inhibition zone diameter method to test the antibacterial effect of Fusarium, Alternaria, Penicillium, and Trichothecene on post-harvest melons. Figure 2 , Figure 2H-1 is Alternaria alternata, H-3 is Fusarium equisetifolia, H-5 is Fusarium chlamydophora, H-6 is Fusarium oxysporum, H-8 is Trichothecenes rosae, H-10 is Fusarium solani, 1 is Fusarium equisetifolia, T-2 is Fusarium oxysporum, and T-9 is Penicillium. In each small figure, the green circle is the control treatment, and the red circle is the fig leaf compound fungicide treatment (the mass ratio of fig leaf extract mother liquor and Amisida dilution is 3:1). The results show that the fig leaf compound fungicide has a significant inhibitory effect on the main post-harvest fungi of melon, and the compound treatment is better than the single preparation.

[0058] Example 19: Verification test of the efficacy of the fig leaf composite fungicide The efficacy of the fig leaf compound fungicide was determined by the inhibition zone method (as shown in Table 6). After the fig leaf extract and Amicida were mixed at a ratio of 3:1, the inhibitory diameter of the compound preparation against Fusarium was determined at 0d, 5d, 10d, 15d, 20d, 30d and 35d of storage. The inhibition rate at different time points was not significantly different, and the inhibition rate reached 50.12% to 61.14%. In the second year of storage, the inhibition test was carried out on the 0d, 5d, 10d, 15d, 20d, 30d and 35d preparations (as shown in Table 6). Figure 3 ), the inhibitory effect still existed at different time points, and the inhibition rate reached 54.47% to 65.20%.

[0059] Example 20: Antibacterial effect of different concentrations of nanosilver on postharvest diseases of melons: like Figure 4 As shown in the figure, the growth rate method was used to study the antibacterial effects of different nanosilver concentrations of 1μmol / L (Ag-1), 2μmol / L (Ag-2) and 3μmol / L (Ag-3) on the main post-harvest fungi of melon, Fusarium equisetifolia (No. 1 fungus), Fusarium oxysporum (Fom fungus), Alternaria alternata (No. 21 fungus) and Trichothecene pink (No. H8 fungus). The inhibitory effects of different nanosilver treatment concentrations on the main post-harvest fungi of melon were significantly better than those of the control treatment, and the difference reached an extremely significant level, while there was no significant difference between different concentration treatments. Therefore, it can be judged that the treatment concentration of nanosilver is 1μmol / L to 3μmol / L.

[0060] Example 21: Antibacterial effect of plant-derived nanocomposite fungicide on postharvest fungal diseases of melon Fig leaf extract (1 g / mL), Amisida dilution, nanosilver solution (1 μmol / L), chitosan solution (0.5%) and different combinations of the four were used to test the antibacterial effects of the main post-harvest melon pathogens Fusarium equisetum, Fusarium oxysporum, Trichothecene pink and Alternaria alternata. The results are shown in Figure 5In Figures A to D, “W” is a fig leaf extract, “A” is a diluted solution of Amisida, “Fu” is a composite fungicide of fig leaves (the mass ratio of the mother solution of fig leaf extract and the diluted solution of Amisida is 3:1), “Shell” is a chitosan solution, and silver is a nanosilver solution. “W+Silver” is a mixture of a fig leaf extract and a nanosilver solution (mass ratio is 1:1), “Shell+Silver” is a mixture of a chitosan solution and a nanosilver solution (mass ratio is 1:1), and “Fu+Shell” is a mixture of a chitosan solution and a nanosilver solution (mass ratio is 1:1). " is a mixture of fig leaf compound fungicide and chitosan solution (mass ratio is 1:1), "complex + silver" is a mixture of fig leaf compound fungicide and nanosilver solution (mass ratio is 1:1), "no + shell + silver" is a mixture of fig leaf extract, chitosan solution and nanosilver solution (mass ratio is 1:1:1), and "complex + shell + silver" is a mixture of fig leaf compound fungicide, chitosan solution and nanosilver solution (mass ratio is 1:1:1).

[0061] Depend on Figure 5 As shown in Figure A, the inhibition rates of different treatment combinations on the main postharvest fungus Fusarium equisetum in melons were significantly and extremely significantly different from those in the control treatment group. Among them, the best effect was obtained by the 1:1:1 compound preparation of fig leaf compound fungicide, 0.5% chitosan solution and 1μmol / L nanosilver solution, followed by the 1:1 compound preparation of fig leaf compound fungicide and 0.5% chitosan solution and 0.5% chitosan solution, with inhibition rates of 85.48%, 78.09% and 74.67% on Fusarium equisetum, respectively.

[0062] Depend on Figure 5 As shown in Figure B, the inhibition rates of different treatment combinations on the main postharvest fungus Fusarium oxysporum of melons were significantly and extremely significantly different from those of the control treatment group. Among them, the best effect was obtained by the compound fungicide of fig leaf, 0.5% chitosan solution and 1μmol / L nanosilver solution in a ratio of 1:1:1, followed by the compound fungicide of fig leaf, 0.5% chitosan solution in a ratio of 1:1 and 0.5% chitosan solution, with inhibition rates of 81.41%, 81.21% and 80.24% on Fusarium equiseti, respectively.

[0063] Depend on Figure 5 As shown in Figure C, the inhibition rates of different treatment combinations on the main postharvest fungus pink trichothecene in melons were significantly and extremely significantly different from those in the control treatment group. Among them, the best effect was obtained by the 1:1:1 compound preparation of fig leaf compound fungicide, 0.5% chitosan solution and 1μmol / L nanosilver solution, followed by the 1:1 compound preparation of fig leaf compound fungicide and 0.5% chitosan solution and 0.5% chitosan solution, with inhibition rates of 86.47%, 86.38% and 86.12% on pink trichothecene, respectively.

[0064] Depend on Figure 5As shown in Figure D, the inhibition rates of different treatment combinations on the main postharvest fungus Alternaria alternata of melons were significantly and extremely significantly different from those of the control treatment group. Among them, the compound preparation of fig leaf fungicide, 0.5% chitosan solution and 1μmol / L nanosilver solution in a ratio of 1:1:1 had the best effect, followed by the compound preparation of fig leaf fungicide, 0.5% chitosan solution in a ratio of 1:1 and Amisida dilution (500 times), with inhibition rates of 89.45%, 89.36% and 79.71% on Alternaria alternata, respectively.

[0065] Overall, different treatment combinations had a certain inhibitory effect on the main post-harvest fungi of melon, Fusarium equisetifolia, Fusarium oxysporum, Trichothecene pink and Alternaria alternata, but the best effect was achieved by the compound preparation of fig leaf fungicide, 0.5% chitosan solution and 1 μmol / L nanosilver solution in a 1:1:1 ratio, which significantly inhibited the growth and spread of post-harvest fungi in melon.

[0066] Example 22: Verification of the effect of plant-derived nanocomposite fungicide on post-harvest damage of melons The lesion was inoculated with 20 μL of suspension at a concentration of 1×10 6 spores / mL of melons infected with Fusarium spores, Trichothecene roseum and Alternaria alternata, and the antibacterial diameter of the melon skin of each treatment was determined. The results are shown below Figure 6 In Figures A to C, "None" is a fig leaf extract, "A" is a diluted solution of Amisida, "Fu" is a fig leaf compound fungicide (the mass ratio of fig leaf extract mother liquor and Amisida diluted solution is 1:1), "Shell" is a chitosan solution, and "Silver" is a nanosilver solution. "None+Silver" is a mixture of fig leaf extract and nanosilver solution (mass ratio is 1:1), "Shell+Silver" is a mixture of chitosan solution and nanosilver solution (mass ratio is 1:1), "Fu+Shell" is a mixture of fig leaf compound fungicide and chitosan solution (mass ratio is 1:1), "Fu+Silver" is a mixture of fig leaf compound fungicide and nanosilver solution (mass ratio is 1:1), "None+Shell+Silver" is a mixture of fig leaf extract, chitosan solution and nanosilver solution (mass ratio is 1:1), and "Fu+Shell+Silver" is a mixture of fig leaf compound fungicide, chitosan solution and nanosilver solution (mass ratio is 1:1:1).

[0067] Depend on Figure 6As shown in Figure A, the inhibition rates of different treatment combinations on melons inoculated with the fungus Fusarium oxysporum were significantly and extremely significantly different from those of the control treatment group. Among them, the compound preparation of fig leaf fungicide, 0.5% chitosan solution and 1μmol / L nanosilver solution in a ratio of 1:1:1 had the best effect, followed by the compound preparation of fig leaf fungicide and 1μmol / L nanosilver solution in a ratio of 1:1 and fig leaf fungicide, with the inhibition rates of 48.20%, 44.83% and 38.42% on Fusarium oxysporum in melon peel, respectively.

[0068] Depend on Figure 6 As can be seen from Figure B, the inhibition rates of different treatment combinations on melons inoculated with pink trichothecene fungi were significantly and extremely significantly different from those of the control treatment group. Among them, the compound preparation of fig leaf fungicide, 0.5% chitosan solution and 1μmol / L nanosilver solution in a ratio of 1:1:1 had the best effect, followed by the compound preparation of fig leaf fungicide and 0.5% chitosan solution in a ratio of 1:1 and fig leaf fungicide, whose inhibition rates on pink trichothecene fungi on melon peel were 58.67%, 47.88% and 46.09%, respectively.

[0069] Depend on Figure 6 As shown in Figure C, the inhibition rates of different treatment combinations on postharvest melons inoculated with Alternaria fungi were significantly and extremely significantly different from those of the control treatment group. Among them, the compound preparation of fig leaf fungicide, 0.5% chitosan solution and 1μmol / L nanosilver solution in a ratio of 1:1:1 had the best effect, followed by the compound preparation of fig leaf fungicide and 0.5% chitosan solution in a ratio of 1:1 and fig leaf fungicide, with inhibition rates of 52.18%, 45.31% and 42.11% on melon peel Alternaria fungi, respectively.

[0070] In summary, different treatment combinations had certain inhibitory effects on melons inoculated with the fungi Fusarium oxysporum, Pink Trichothecene and Alternaria, but the compound preparation of fig leaf fungicide, 0.5% chitosan solution and 1 μmol / L nanosilver solution in a 1:1:1 ratio had the best inhibitory effect on melon epidermal fungi, which significantly inhibited the growth and spread of melon epidermal fungi.

[0071] The present invention has the following beneficial effects: (1) Fig leaf is a natural plant leaf with no chemical pollution, high safety, abundant resources, no damage to the ecological environment, and strong antibacterial properties.

[0072] (2) Botanical pesticides are rich in secondary metabolites and have the characteristics of strong targeting effects, good environmental compatibility, and low resistance to pesticides. By compounding botanical pesticides with chemical fungicides, the toxic effects and resistance problems of chemical fungicides can be reduced, while at the same time compensating for the problems of slow effect and unstable efficacy of botanical pesticides.

[0073] (3) The synergistic effect of plant-based antibacterial agents and chemical fungicides was used for green control of post-harvest melon diseases. The combined agent reduced the dosage of the agent by 66.67% compared with the chemical fungicide, but increased the efficacy by 25.59% and reduced the pesticide residue by 65.6% to 78.2%.

[0074] (4) The present invention organically combines botanical fungicides and chemical fungicides, and has the advantages of both. The botanical compound fungicide has multiple functions such as significantly reducing melon rot, reducing water loss, and increasing the glossiness of the melon skin, and is suitable for post-harvest storage and preservation of melons.

[0075] The present invention provides a botanical nano composite fungicide and a preparation method and application thereof. The botanical nano composite fungicide utilizes the synergistic effect of a botanical antibacterial agent and a chemical fungicide to carry out green prevention and control of post-harvest melon diseases, and can significantly reduce melon rot, reduce water loss, increase the glossiness of the melon skin and other functions, and is suitable for post-harvest storage and preservation of melons.

[0076] The above technical features respectively constitute various embodiments of the present invention, which have strong adaptability and implementation effect. Non-essential technical features can be added or reduced according to actual needs to meet the requirements of different situations.

Claims

1. A plant-derived nanocomposite fungicide, characterized in that The raw materials include, by weight: 1 part of a fig leaf compound fungicide, 1 part of a nano-silver solution and 1 part of a chitosan solution; wherein the fig leaf compound fungicide consists of a fig leaf extract mother liquor and an Amisida diluent.

2. The plant-derived nanocomposite fungicide according to claim 1, characterized in that The fig leaf composite fungicide is obtained by mixing a fig leaf extract mother liquor and an amisida dilution liquid in a mass ratio of 6:1 to 3:1, the concentration of myclobutanil in the amisida dilution liquid is 0.5 g / L, and the concentration of the fig leaf extract mother liquor is 1 g / mL.

3. The plant-derived nanocomposite fungicide according to claim 1 or 2, characterized in that The mass fraction of the chitosan solution is 0.5% to 1%.

4. The plant-derived nanocomposite fungicide according to any one of claims 1 to 3, characterized in that The concentration of the nanosilver solution is 1 μmol / L to 3 μmol / L.

5. The plant-derived nanocomposite fungicide according to any one of claims 1 to 4, characterized in that The plant-derived nanocomposite fungicide is prepared by the following method: Step 1, extracting fig leaves with ethanol, concentrating the extract to obtain a fig leaf extract mother liquor, measuring an Amicid solution, adding it to sterile distilled water to obtain an Amicid diluted solution with a concentration of 0.5 g / L of myclobutanil, mixing the fig leaf extract mother liquor and the Amicid diluted solution in a ratio of 6:1 to 3:1 to obtain a fig leaf composite fungicide; Step 2, taking a required amount of silver nitrate particles, adding them into sterile water, stirring evenly, and ultrasonically treating to obtain a nanosilver solution; Step 3, taking a required amount of chitosan and adding it to a glacial acetic acid solution, adding Tween, filtering and removing insoluble matter after dissolving, to obtain a chitosan solution, wherein the volume fraction of the glacial acetic acid solution is 0.5%; Step 4: Mix the fig leaf composite fungicide, the nano silver solution and the chitosan solution in a mass ratio of 1:1:1 to obtain a plant-derived nano composite fungicide.

6. The plant-derived nanocomposite fungicide according to claim 5, characterized in that In step 3, the amount of Tween added is 0.5 mL per 100 mL of glacial acetic acid solution.

7. The plant-derived nanocomposite fungicide according to claim 5 or 6, characterized in that In step 1, the steps of preparing the fig leaf extract mother solution include: The first step is to wash, dry and crush the fig leaves to obtain fig leaf dry powder; The second step is to use ethanol to ultrasonically extract the fig leaves to obtain a fig leaf extract, wherein the volume fraction of ethanol is 75% to 85%; The third step is to concentrate the fig leaf extract to remove ethanol from the fig leaf extract, and dissolve the concentrate with sterile water to obtain a fig leaf extract mother solution with a concentration of 1 g / mL.

8. The plant-derived nanocomposite fungicide according to any one of claims 1 to 7, characterized in that In the second step, the ultrasonic time is 30 min to 40 min, and the extraction temperature is 30° C. to 40° C.; or / and, in the second step, the solid-liquid ratio is 1:20 to 1:

30.

9. A method for preparing the plant-derived nanocomposite fungicide according to claim 1 or 2 or 3 or 4 or 6 or 7 or 8, characterized in that The following steps are involved: Step 1: extracting fig leaves with ethanol, concentrating the extract to obtain a fig leaf extract mother liquor; measuring an Amicid solution, adding it to sterile distilled water, and obtaining an Amicid diluted solution with a concentration of 0.5 g / L of myclobutanil; mixing the fig leaf extract mother liquor and the Amicid diluted solution in a ratio of 6:1 to 3:1 to obtain a fig leaf composite fungicide; Step 2, taking a required amount of silver nitrate particles, adding them into sterile water, stirring evenly, and ultrasonically treating to obtain a nanosilver solution; Step 3, taking a required amount of chitosan and adding it to a glacial acetic acid solution, adding Tween, filtering and removing insoluble matter after dissolving, to obtain a chitosan solution, wherein the volume fraction of the glacial acetic acid solution is 0.5%; Step 4: Mix the fig leaf composite fungicide, the nano silver solution and the chitosan solution in a mass ratio of 1:1:1 to obtain a plant-derived nano composite fungicide.

10. Use of the plant-derived nanocomposite fungicide according to claims 1 to 8 in preserving melons.

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