Plant source nanocomposite bactericide, preparation method and application thereof

Abstract

The present application relates to the field of plant sterilization and preservation technology, and is a plant source nano composite fungicide, a preparation method and application thereof, the plant source nano composite fungicide raw materials include fig leaf composite fungicide 1 part, nano silver solution 1 part and chitosan solution 1 part according to mass fraction; wherein the fig leaf composite fungicide is composed of fig leaf extract mother liquor and amixetrin diluent solution. The plant source nano composite fungicide of the present application utilizes the synergistic effect of plant source bacteriostatic agent and chemical fungicide to carry out green prevention and control of postharvest disease of melon, can obviously reduce melon rot, reduce water loss, increase the gloss of melon skin and other functions, and is suitable for postharvest storage and preservation of melon.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of plant fungicidal preservation technology, and is a plant source nanometer composite fungicide as well as a preparation method and application thereof. BACKGROUND

[0002] Amicarbaz (a commercial preparation of azoxystrobin) is a broad-spectrum fungicide. In the early development and research of methoxyacrylate fungicides, the inherent resistance risk research considered that this type of fungicide is of medium drug resistance risk. However, in fact, after the application of this type of fungicide for two years, drug resistance is generated and the control effect is significantly reduced.

[0003] Fusarium spp. is a pathogen of many important crops, which not only can cause serious loss of crop yield and quality, but also can produce secondary metabolites of fusarium toxins under in vitro culture conditions or in plant hosts, seriously affecting food safety. The main pathogenic bacteria species of postharvest rot of different muskmelon varieties in Xinjiang were identified and diversity analysis was performed, and it was found that the postharvest pathogenic fungal colonies of muskmelon had rich diversity, and fusarium was dominant. In addition to causing postharvest rot, fusarium can produce deoxysnowden, zearalenone, fumonisin and other mycotoxins through metabolism, which endangers the safety of muskmelon. At present, the inhibition of postharvest fusarium of muskmelon is mainly dominated by chemical pesticide treatment, and the use of chemical pesticides can easily cause problems such as quality decline of muskmelon, environmental pollution and drug resistance of pathogenic bacteria.

[0004] Therefore, it is imperative to develop a new type of plant source compound fungicide with good bacteriostatic effect and low toxicity by mixing plant material extract with chemical fungicide to reduce the toxic effects and drug resistance problems of chemical fungicide, so as to achieve the effect of synergistically inhibiting fusarium hazards. SUMMARY

[0005] The present application provides a plant source nanometer composite fungicide, which overcomes the shortcomings of the prior art and effectively solves the problems of large dosage and drug resistance of existing fungicides for preserving melons and fruits.

[0006] One of the technical solutions of the present application is achieved by the following measures: a plant source nanometer composite fungicide, raw materials including, by mass fraction: 1 part of fig leaf composite fungicide, 1 part of nanometer silver solution and 1 part of chitosan solution; wherein the fig leaf composite fungicide is composed of fig leaf extract mother liquor and amicarbaz diluent.

[0007] The following is a further optimization or / and improvement of the above-mentioned one of the technical solutions of the present application:

[0008] The ficus carica leaf composite fungicide is obtained by mixing the ficus carica leaf extract mother liquor and azoxystrobin diluent according to a mass ratio of 6:1 to 3:1, the concentration of azoxystrobin in the azoxystrobin diluent is 0.5 g / L, and the concentration of the ficus carica leaf extract mother liquor is 1 g / mL.

[0009] The concentration of the chitosan solution is 0.5% to 1%.

[0010] The concentration of the nanosilver solution is 1 μmol / L to 3 μmol / L.

[0011] The plant source nanocomposite fungicide is prepared by the following method:

[0012] In step one, the ficus carica leaves are extracted by ethanol, and the extract is concentrated to obtain the ficus carica leaf extract mother liquor; the azoxystrobin diluent is obtained by adding the azoxystrobin solution into sterile distilled water to obtain the azoxystrobin diluent with a concentration of 0.5 g / L; and the ficus carica leaf composite fungicide is obtained by mixing the ficus carica leaf extract mother liquor and the azoxystrobin diluent according to a mass ratio of 6:1 to 3:1.

[0013] In step two, the required amount of silver nitrate particles is added into sterile water and stirred uniformly, and then ultrasonic treatment is performed to obtain the nanosilver stock solution.

[0014] In step three, the required amount of chitosan is added into the glacial acetic acid solution, and then Tween is added, and after dissolution, the insoluble substances are removed by filtration to obtain the chitosan solution, wherein the volume fraction of the glacial acetic acid solution is 0.5%.

[0015] In step four, the ficus carica leaf composite fungicide, the nanosilver solution and the chitosan solution are mixed according to a mass ratio of 1:1:1 to obtain the plant source nanocomposite fungicide.

[0016] In step three, the amount of Tween added is 0.5 mL per 100 mL of the glacial acetic acid solution.

[0017] In step one, the preparation steps of the ficus carica leaf extract mother liquor include:

[0018] In the first step, the ficus carica leaves are washed, dried and crushed to obtain the ficus carica leaf dry powder.

[0019] In the second step, the ficus carica leaves are ultrasonically extracted by ethanol to obtain the ficus carica leaf extract, wherein the volume fraction of the ethanol is 75% to 85%.

[0020] In the third step, the ficus carica leaf extract is concentrated to remove the ethanol in the ficus carica leaf extract, and the concentrate is dissolved in sterile water to obtain the ficus carica leaf extract mother liquor with a concentration of 1 g / mL.

[0021] In the second step, the ultrasonic time is 30-40 min, and the extraction temperature is 30-40 DEG C.

[0022] In the second step, the ratio of material to liquid is 1:20-1:30.

[0023] The second technical solution of the present application is realized by the following measures: a preparation method of a plant source nano composite fungicide, comprising the following steps:

[0024] In step one, ethanol is used to extract fig leaves, and after the extraction liquid is concentrated, a fig leaf extraction liquid mother liquor is obtained, an azoxystrobin solution is measured, and sterile distilled water is added to obtain an azoxystrobin diluent with a concentration of 0.5 g / L, and the fig leaf extraction liquid mother liquor and the azoxystrobin diluent are mixed in a ratio of 6:1 to 3:1 to obtain a fig leaf composite fungicide.

[0025] In step two, a required amount of silver nitrate particles is added to sterile water, stirred uniformly, and ultrasonically treated to obtain a nano silver stock solution.

[0026] In step three, a required amount of chitosan is added to an ice acetic acid solution, and Tween is added, and after dissolution, the insoluble substances are removed by filtration to obtain a chitosan solution, wherein the volume fraction of the ice acetic acid solution is 0.5%.

[0027] In step four, the fig leaf composite fungicide, the nano silver solution, and the chitosan solution are mixed in a mass ratio of 1:1:1 to obtain a plant source nano composite fungicide.

[0028] The third technical solution of the present application is realized by the following measures: application of a plant source nano composite fungicide to preservation of melons.

[0029] The plant source nano composite fungicide of the present application uses the synergistic effect of plant source bacteriostatic agents and chemical fungicides to greenly control postharvest diseases of melons, can obviously reduce melon rot, reduce water loss, increase the glossiness of melon skin, and has many other functions, and is suitable for postharvest storage and preservation of melons. BRIEF DESCRIPTION OF DRAWINGS

[0030] FIG. 1 is a schematic diagram of the effect of the composite treatment in Example 17 of the present application on the residual amount of azoxystrobin during the storage period of melons. Figure 1 FIG. 2 is a broad-spectrum bacteriostatic effect diagram of the fig leaf extraction liquid and azoxystrobin compounding in Example 18 of the present application.

[0031] Figure 2 FIG. 3 is an inhibition diameter effect diagram of the fig extraction liquid compounding preparation in Example 19 of the present application in the second year of storage.

[0032] FIG. 4 is a schematic diagram of the effect of the plant source nano composite fungicide in Example 20 of the present application on the residual amount of azoxystrobin during the storage period of melons. Figure 3 FIG. 5 is a broad-spectrum bacteriostatic effect diagram of the plant source nano composite fungicide in Example 20 of the present application.

[0033] FIG. 6 is an inhibition diameter effect diagram of the plant source nano composite fungicide in Example 20 of the present application in the second year of storage.​Figure 4 Figure of antibacterial effect of concentration screening of nano-silver in embodiment 20 of the present application.

[0034] Figure Figure 5 Figure of influence of single and complex nano-preparation on antibacterial diameter of main fungi of postharvest muskmelon in embodiment 21 of the present application.

[0035] Figure Figure 6 Figure of influence of single and complex nano-preparation on antibacterial circle diameter of inoculated muskmelon in embodiment 22 of the present application. DETAILED DESCRIPTION

[0036] The present application is not limited by the following embodiments, and the specific implementation can be determined according to the technical solution of the present application and the actual situation. The various chemical reagents and chemical supplies mentioned in the present application are common chemical reagents and chemical supplies known in the prior art unless otherwise specified; the percentages in the present application are mass percentages unless otherwise specified; the solution in the present application is an aqueous solution with water as the solvent unless otherwise specified, for example, a hydrochloric acid solution is a hydrochloric acid aqueous solution; the normal temperature and room temperature in the present application generally refer to a temperature of 15℃ to 25℃, and is generally defined as 25℃.

[0037] The present application will be further described below in conjunction with embodiments:

[0038] Embodiment 1: The plant source nano-composite bactericide includes, in terms of mass fraction, 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 fig leaf extract mother liquor and azoxystrobin diluent.

[0039] Embodiment 2: As an optimization of the above embodiment, the fig leaf composite bactericide is obtained by mixing fig leaf extract mother liquor and azoxystrobin diluent in a mass ratio of 6:1 to 3:1, the concentration of azoxystrobin in the azoxystrobin diluent is 0.5g / L, and the concentration of the fig leaf extract mother liquor is 1g / mL (i.e. 1g of fig leaf extract obtains 1mL of mother liquor).

[0040] Embodiment 3: As an optimization of the above embodiment, the mass fraction of the chitosan solution is 0.5% to 1%.

[0041] Embodiment 4: As an optimization of the above embodiment, the concentration of the nano-silver solution is 1μmol / L to 3μmol / L.

[0042] Embodiment 5: As an optimization of the above embodiment, the plant source nano-composite bactericide is prepared by the following method:

[0043] Step one, the ficus carica leaves are extracted by ethanol, and the extract is concentrated to obtain the ficus carica leaf extract mother liquor; the azoxystrobin solution is measured and added into sterile distilled water to obtain the azoxystrobin diluent with a concentration of 0.5 g / L; the ficus carica leaf extract mother liquor and the azoxystrobin diluent are mixed in a ratio of 6:1 to 3:1 to obtain the ficus carica leaf composite fungicide;

[0044] Step two, the required amount of silver nitrate particles is added into sterile water and stirred uniformly, and then ultrasonic treatment is performed to obtain the nano-silver stock solution;

[0045] Step three, the required amount of chitosan is added into the glacial acetic acid solution, and then Tween is added, and after dissolution, the insoluble substances are removed by filtration to obtain the chitosan solution, wherein the volume fraction of the glacial acetic acid solution is 0.5%;

[0046] Step four, the ficus carica leaf composite fungicide, the nano-silver solution and the chitosan solution are mixed in a ratio of 1:1:1 to obtain the plant source nano-composite fungicide.

[0047] Example 6: As an optimization of the above examples, in step three, the amount of Tween added is 0.5 mL per 100 mL of glacial acetic acid solution.

[0048] Example 7: As an optimization of the above examples, in step one, the preparation steps of the ficus carica leaf extract mother liquor include:

[0049] First step, after cleaning, drying and crushing the ficus carica leaves, the ficus carica leaf dry powder is obtained;

[0050] Second step, the ficus carica leaves are ultrasonically extracted by ethanol to obtain the ficus carica leaf extract, wherein the volume fraction of ethanol is 75% to 85%;

[0051] Third step, the ficus carica leaf extract is concentrated to remove ethanol in the ficus carica leaf extract, and the concentrate is dissolved in sterile water to obtain the ficus carica leaf extract mother liquor with a concentration of 1 g / mL.

[0052] Example 8: As an optimization of the above examples, in the second step, the ultrasonic time is 30 min to 40 min, and the extraction temperature is 30°C to 40°C.

[0053] Example 9: As an optimization of the above examples, in the second step, the solid-liquid ratio (mass-volume ratio of ficus carica leaves and ethanol) is 1:20 to 1:30.

[0054] Example 10: Application of the plant source nano-composite fungicide in melon preservation.

[0055] Example 11: The plant source nano-composite fungicide is prepared by the following method:

[0056] Preparation of mother liquor of ficus carica leaf extract: The collected ficus carica leaves were repeatedly washed with clean water and dried, dried in a constant temperature drying oven at 70°C until constant weight, and then crushed into powder with a universal grinder, and sieved through an 80-mesh sieve to obtain ficus carica leaf dry powder; 4 g of the ficus carica leaf dry powder was weighed into a 100 mL triangular flask, the solid-liquid ratio was 4 g: 100 mL, and the mixture was placed in an ultrasonic cell crusher and extracted at 35°C for 40 min; after the extraction was completed, the ficus carica leaf extract was filtered through filter paper, and the filtrate was placed in a rotary evaporator for reduced pressure distillation to remove the influence of the extraction solvent ethanol; after distillation, the filtrate was made up to volume with sterile high-purity water to obtain a ficus carica leaf extract mother liquor with a concentration of 1 g / mL, which was stored at 4°C in a refrigerator for standby use.

[0057] Preparation of amicarbazium dilution: 1 mL of amicarbazium solution was taken and added to 500 mL of sterile distilled water, stirred uniformly, and ultrasonically degassed for 30 min to obtain an amicarbazium dilution with a concentration of 0.5 g / L.

[0058] Preparation of ficus carica leaf composite fungicide: the ficus carica leaf extract mother liquor and the amicarbazium dilution were mixed in a mass ratio of 5:1, and stirred uniformly to obtain the ficus carica leaf composite fungicide.

[0059] Preparation of nano-silver solution: 34 mg of silver nitrate particles was weighed and added to 100 mL of sterile distilled water, stirred uniformly, and ultrasonically degassed for 30 min to obtain a nano-silver solution with a concentration of 2 μmol / L.

[0060] Preparation of chitosan solution: 0.7 g of chitosan was weighed and added to 100 mL of 0.5% acetic acid solution, and 0.5 mL of Tween was added for dissolution, and after ultrasonic degassing, the insoluble matter was removed by filtration to prepare a chitosan solution with a mass fraction of 0.7%.

[0061] Preparation of plant source nano-composite fungicide: the ficus carica leaf composite fungicide, the nano-silver solution and the chitosan solution were mixed in a ratio of 1:1:1, stirred uniformly, and ultrasonically degassed for 30 min to obtain the plant source nano-composite fungicide.

[0062] Example 12: The plant source nano-composite fungicide was prepared by the following method:

[0063] Preparation of mother liquor of ficus carica leaf extract: The collected ficus carica leaves were repeatedly washed with clean water and dried, dried in a constant temperature drying oven at 70°C until constant weight, and then crushed into powder with a universal grinder, and sieved through an 80-mesh sieve to obtain ficus carica leaf dry powder; 3.5 g of the ficus carica leaf dry powder was weighed into a 100 mL triangular flask, the solid-liquid ratio was 3.5 g: 100 mL, and the mixture was placed in an ultrasonic cell crusher and extracted at 40°C for 30 min; after the extraction was completed, the ficus carica leaf extract was filtered through filter paper, and the filtrate was placed in a rotary evaporator for reduced pressure distillation to remove the influence of the extraction solvent ethanol; after distillation, the filtrate was made up to volume with sterile high-purity water to obtain a ficus carica leaf extract mother liquor with a concentration of 1 g / mL, which was stored at 4°C in a refrigerator for standby use.

[0064] Preparation of amicarbazium dilution: 1 mL of amicarbazium solution was taken and added to 500 mL of sterile distilled water, stirred uniformly, and ultrasonically degassed for 30 min to obtain an amicarbazium dilution with a concentration of 0.5 g / L.

[0065] Preparation of ficus carica leaf composite fungicide: The ficus carica leaf extract mother liquor and the amicarbazium dilution were mixed in a mass ratio of 4:1, and stirred uniformly to obtain the ficus carica leaf composite fungicide.

[0066] Preparation of nanosilver solution: 51 mg of silver nitrate particles was weighed and added to 100 mL of sterile distilled water, stirred uniformly, and ultrasonically degassed for 30 min to obtain a nanosilver solution with a concentration of 3 μmol / L.

[0067] Preparation of chitosan solution: 0.5 g of chitosan was added to 100 mL of 0.5% (by volume fraction) glacial acetic acid solution, and 0.5 mL of Tween was added for dissolution, and the mixture was filtered after ultrasonic degassing to remove insoluble substances to prepare a chitosan solution with a mass fraction of 0.5%.

[0068] Preparation of plant source nanocomposite fungicide: The ficus carica leaf composite fungicide, nanosilver solution, and chitosan solution were mixed in a ratio of 1:1:1, stirred uniformly, and ultrasonically degassed for 30 min to obtain the plant source nanocomposite fungicide.

[0069] Example 13: The plant source nanocomposite fungicide was prepared by the following method:

[0070] Preparation of mother liquor of ficus carica leaf extract: The collected ficus carica leaves were repeatedly washed with clean water and dried, dried in a constant temperature drying oven at 70°C until constant weight, and then crushed into powder with a universal crusher, and sieved through an 80-mesh sieve to obtain ficus carica leaf dry powder; 5 g of the ficus carica leaf dry powder was weighed into a 100 mL triangular flask, the solid-liquid ratio was 5 g: 100 mL, and the mixture was placed in an ultrasonic cell crusher and extracted at 35°C for 30 min; after the extraction was completed, the ficus carica leaf extract was filtered through filter paper, and the filtrate was placed in a rotary evaporator for reduced pressure distillation to remove the influence of the extraction solvent ethanol; after distillation, the filtrate was made up to volume with sterile high-purity water to obtain a ficus carica leaf extract mother liquor with a concentration of 1 g / mL, which was stored at 4°C in a refrigerator for standby use.

[0071] Preparation of amicarbazium dilution: 1 mL of amicarbazium solution was taken and added to 500 mL of sterile distilled water, stirred uniformly, and ultrasonically degassed for 30 min to obtain an amicarbazium dilution with a concentration of 0.5 g / L.

[0072] Preparation of ficus carica leaf composite fungicide: The ficus carica leaf extract mother liquor and the amicarbazium dilution were mixed in a mass ratio of 6:1, and stirred uniformly to obtain the ficus carica leaf composite fungicide.

[0073] Preparation of nanosilver solution: 17 mg of silver nitrate particles was weighed and added to 100 mL of sterile distilled water, stirred uniformly, and ultrasonically degassed for 30 min to obtain a nanosilver solution with a concentration of 1 μmol / L.

[0074] Preparation of chitosan solution: 0.9 g of chitosan was added to 100 mL of 0.5% acetic acid solution, and 0.5 mL of Tween was added for dissolution, and the mixture was filtered after ultrasonic degassing to remove insoluble substances to prepare a chitosan solution with a mass fraction of 0.9%.

[0075] Preparation of plant source nanocomposite fungicide: The ficus carica leaf composite fungicide, nanosilver solution and chitosan solution were mixed in a ratio of 1:1:1, stirred uniformly, and ultrasonically degassed for 30 min to obtain the plant source nanocomposite fungicide.

[0076] Example 14: Optimization of ficus carica leaf extract extraction process

[0077] The effects of ethanol concentration, ultrasonic time and solid-liquid ratio on the yield of total flavonoids from Ficus carica L. leaf extract were optimized by response surface methodology. The optimal extraction conditions were obtained by design expert software as follows: ethanol concentration 79.73%, ultrasonic time 36.81 min, and solid-liquid ratio 1:24. The theoretical yield was 1.57785 mg / g, and the experimental yield was 1.5325 mg / g. The relative error between the actual yield and the theoretical yield was 2.96%, which was close to each other. Therefore, the results obtained by response surface design were accurate and reliable. The optimal extraction parameters of Ficus carica L. leaf extract were as follows: ethanol concentration 79.73%, ultrasonic time 36.81 min, and 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.

[0078] Example 15: Screening of Ficus carica L. leaf extract and commercial chemical fungicides

[0079] The diameters of inhibition zones were used to screen the commercial chemical fungicides prochloraz, triforine, thiophanate-methyl, propineb, fenpropimorph, pyraclostrobin, and amicarbazole for the preparation of mixtures with Ficus carica L. leaf extract. The target fungus was Fusarium equiseti. The results are shown in Table 3. After being diluted 500 times, the commercial fungicides showed obvious inhibitory effects on the target fungus, but the inhibitory effects were different. After being mixed with Ficus carica L. leaf extract at a ratio of 1:1, the inhibitory effects of the fungicides were weakened due to the decrease of the concentration of the fungicides. However, after being mixed with Ficus carica L. leaf extract, the amicarbazole solution showed obvious synergistic effect, which was increased by 14.88% compared with the single amicarbazole. Therefore, the synergistic effect of Ficus carica L. leaf extract and amicarbazole was the most obvious.

[0080] Example 16: Study on the synergistic effect of Ficus carica L. leaf extract and amicarbazole

[0081] The effects of the mixtures were determined by Wadley's method. The mother liquor of Ficus carica L. leaf extract was mixed with the amicarbazole dilution solution (500 times) at ratios of 6:1, 3:1, 1:1, 1:3, and 1:6, respectively. The effective ingredient concentrations were designed as 50.0000 μg / mL, 25.0000 μg / mL, 12.5000 μg / mL, 6.2500 μg / mL, 3.1250 μg / mL, and 1.5625 μg / mL by multiple dilution. The synergistic coefficients of the mixtures on Fusarium equiseti and F. verticillioides were 1.85, 1.60, 1.33, 1.08, 0.96, and 1.85, 1.60, 1.33, 1.08, 0.96, respectively. Ficus carica L. leaf extract showed obvious synergistic effect, and the synergistic coefficient of the mixture at a ratio of 6:1 was the largest (as shown in Table 4). F. equiseti F. solani ​The synergistic coefficients of the two compounds were 1.686, 2.052, 1.056, 1.591, and 1.369, respectively. Fig leaf extract also showed a significant synergistic effect, with the 3:1 mixture exhibiting the largest synergistic coefficient (as shown in Table 5). This indicates that the combination of fig leaf extract and amistar has a significant synergistic effect in inhibiting Fusarium oxysporum, a fungus that infects melons during storage.

[0082] Example 17: Application Effect of Reduced Application and Enhanced Efficacy of Compound Fungicide for Fig Leaves

[0083] High-performance liquid chromatography (HPLC) was used to detect the residual amount of azoxystrobin in melon pulp during storage after treatment with a 500-fold dilution of azoxystrobin and a 3:1 mixture of fig leaf extract and a 500-fold dilution of azoxystrobin. The experimental results are as follows: Figure 1 As shown, with the extension of treatment time, the content of azoxystrobin in melon pulp treated with amistar gradually increased, while the compound of fig leaf extract and amistar reduced the amount of pesticide used by 66.67% compared with the treatment with amistar alone, and the pesticide residue was significantly reduced, with a reduction of pesticide residue by 65.6% to 78.2%.

[0084] Example 18: Determination of the broad-spectrum antibacterial activity of a compound fungicide for fig leaves:

[0085] The inhibitory effect of a compound fungicide for fig leaves on postharvest pathogens of melon was determined by using the inhibition zone diameter method to test the antibacterial effects against Fusarium, Alternaria, Penicillium, and Trichophyton mentagrophytes in melons after harvest. The test results are as follows: Figure 2 , Figure 2 H-1 is *Alternaria alternata*, H-3 is *Fusarium equisetifolium*, H-5 is *Fusarium chrysogenum*, H-6 is *Fusarium oxysporum*, H-8 is *Trichoderma purpureus*, H-10 is *Fusarium solani*, 1 is *Fusarium equisetifolium*, 2 is *Fusarium oxysporum*, and T-9 is *Penicillium*. In each subplot, the green circle indicates the control treatment, and the red circle indicates the treatment with the fig leaf compound fungicide (the mass ratio of fig leaf extract stock solution to azoxystrobin dilution was 3:1). The results show that the fig leaf compound fungicide has a significant inhibitory effect on the major post-harvest fungi of melon, and the compound treatments are superior to the single formulations.

[0086] Example 19: Efficacy Verification Test of Fig Leaf Compound Fungicide

[0087] The antibacterial circle method was used to determine the efficacy of the compound fungicide of fig leaves (as shown in Table 6). After the fig leaf extract and amicarbalide were mixed at a ratio of 3:1, the inhibition diameters of the mixed preparation on fusarium were measured at 0d, 5d, 10d, 15d, 20d, 30d and 35d. The inhibition rates at different time points were not significantly different, and the inhibition rates reached 50.12% to 61.14%. In the second year of the storage period, the prepared agents at 0d, 5d, 10d, 15d, 20d, 30d and 35d were subjected to inhibition test (as shown in Figure 3 ), and the inhibition effect at different time points still existed, and the inhibition rate reached 54.47% to 65.20%.

[0088] Example 20: Antibacterial effect of different concentrations of nano-silver on postharvest disease of melon

[0089] As shown in Figure 4 , the growth rate method was used to study the antibacterial effect of different concentrations of nano-silver 1 μmol / L (Ag-1), 2 μmol / L (Ag-2) and 3 μmol / L (Ag-3) on postharvest main fungi of melon, i.e. fusarium oxysporum (No. 1 fungus), fusarium oxysporum (Fom fungus), alternaria alternata (No. 21 fungus) and powdery single-end fungus (H8 fungus). The inhibition effect of different concentrations of nano-silver on postharvest main fungi of melon was significantly better than that of the control treatment, and the difference reached a very significant level, while the difference between different concentrations of treatment was not significant. Therefore, it can be judged that the treatment concentration of nano-silver is 1 μmol / L to 3 μmol / L.

[0090] Example 21: Antibacterial effect of plant source nano-composite fungicide on postharvest fungal disease of melon

[0091] Fig leaf extract (1 g / mL), amicarbalide diluent, nano-silver solution (1 μmol / L), chitosan solution (0.5%) and different combinations of the four were used to determine the antibacterial effect of main pathogenic fungi of postharvest melon, i.e. fusarium oxysporum, fusarium oxysporum, powdery single-end fungus and alternaria alternata. The results are shown in Figure 5, Fig. A to D is no fig leaf extract, A is amicarbazide dilution, "complex" is fig leaf complex fungicide (fig leaf extract mother liquor and amicarbazide dilution mass ratio is 3:1), "shell" is chitosan solution, silver is nano silver solution, "no + silver" is fig leaf extract and nano silver solution mixture (mass ratio is 1:1), "shell + silver" is chitosan solution and nano silver solution mixture (mass ratio is 1:1), "complex + shell" is fig leaf complex fungicide and chitosan solution mixture (mass ratio is 1:1), "complex + silver" is fig leaf complex fungicide and nano silver solution mixture (mass ratio is 1:1), "no + shell + silver" is fig leaf extract, chitosan solution and nano silver solution mixture (mass ratio is 1:1:1), "complex + shell + silver" is fig leaf complex fungicide, chitosan solution and nano silver solution mixture (mass ratio is 1:1:1).

[0092] From Figure 5 Fig. A in the middle can be seen, the inhibition rate of different treatment combinations on the main fungus of postharvest melon Fusarium oxysporum reached significant and extremely significant level compared with the control treatment group. Among them, the fig leaf complex fungicide, 0.5% chitosan solution and 1 μmol / L nano silver solution compounded preparation effect is best, followed by fig leaf complex fungicide and 0.5% chitosan solution 1:1 complex and 0.5% chitosan solution, its inhibition rate on Fusarium oxysporum was 85.48%, 78.09% and 74.67% respectively.

[0093] From Figure 5 Fig. B in the middle can be seen, the inhibition rate of different treatment combinations on the main fungus of postharvest melon Fusarium oxysporum reached significant and extremely significant level compared with the control treatment group. Among them, the fig leaf complex fungicide, 0.5% chitosan solution and 1 μmol / L nano silver solution compounded preparation effect is best, followed by fig leaf complex fungicide and 0.5% chitosan solution 1:1 complex and 0.5% chitosan solution, its inhibition rate on Fusarium oxysporum was 81.41%, 81.21% and 80.24% respectively.

[0094] From Figure 5 Fig. C in the middle can be seen, the inhibition rate of different treatment combinations on the main fungus of postharvest melon Fusarium oxysporum reached significant and extremely significant level compared with the control treatment group. Among them, the fig leaf complex fungicide, 0.5% chitosan solution and 1 μmol / L nano silver solution compounded preparation effect is best, followed by fig leaf complex fungicide and 0.5% chitosan solution 1:1 complex and 0.5% chitosan solution, its inhibition rate on Fusarium oxysporum was 86.47%, 86.38% and 86.12% respectively.

[0095] From Figure 5As can be seen from Fig. D, the inhibition rates of different treatment combinations on the main fungus Alternaria alternata of postharvest melon were significantly different from those of the control group. Among them, the effect of the preparation of 1:1:1 complex of fig leaf composite fungicide, 0.5% chitosan solution and 1 μmol / L nano-silver solution was the best, followed by 1:1 complex of fig leaf composite fungicide and 0.5% chitosan solution and amicarbazic diluent (500 times), and the inhibition rates of them on Alternaria alternata were 89.45%, 89.36% and 79.71% respectively.

[0096] In summary, different treatment combinations had certain inhibitory effect on the main fungi Fusarium oxysporum, Fusarium solani, Corynespora cassiicola and Alternaria alternata of postharvest melon, but the effect of 1:1:1 complex of fig leaf composite fungicide, 0.5% chitosan solution and 1 μmol / L nano-silver solution was the best, which significantly inhibited the growth and spread of postharvest fungi of melon.

[0097] Example 22: Plant source nano-composite fungicide on postharvest injury inoculation of melon

[0098] The fig leaf extract mother liquor (1 g / mL), amicarbazic diluent, nano-silver solution (1 μmol / L), chitosan solution (0.5%) and different combinations of the four were used to treat the injury inoculation of 20 μL of suspension with a concentration of 1×10 6 spores / mL of Fusarium solani, Corynespora cassiicola and Alternaria alternata of melon, and the inhibition diameter of the melon skin of each treatment was determined. The results are shown in the following Figure 6 , wherein Fig. A to C are fig leaf extract, amicarbazic diluent, "complex" is fig leaf composite fungicide (the mass ratio of fig leaf extract mother liquor and amicarbazic diluent is 1:1), chitosan is chitosan solution, silver is nano-silver solution, no+silver is the mixture of fig leaf extract and nano-silver solution (the mass ratio is 1:1), chitosan+silver is the mixture of chitosan solution and nano-silver solution (the mass ratio is 1:1), complex+chitosan is the mixture of fig leaf composite fungicide and chitosan solution (the mass ratio is 1:1), complex+silver is the mixture of fig leaf composite fungicide and nano-silver solution (the mass ratio is 1:1), no+chitosan+silver is the mixture of fig leaf extract, chitosan solution and nano-silver solution (the mass ratio is 1:1), and complex+chitosan+silver is the mixture of fig leaf composite fungicide, chitosan solution and nano-silver solution (the mass ratio is 1:1:1).

[0099] From Fig. D, it can be seen that the inhibition rates of different treatment combinations on the main fungus Alternaria alternata of postharvest melon were significantly different from those of the control group. Among them, the effect of the preparation of 1:1:1 complex of fig leaf composite fungicide, 0.5% chitosan solution and 1 μmol / L nano-silver solution was the best, followed by 1:1 complex of fig leaf composite fungicide and 0.5% chitosan solution and amicarbazic diluent (500 times), and the inhibition rates of them on Alternaria alternata were 89.45%, 89.36% and 79.71% respectively. Figure 6As can be seen from the middle A figure, the inhibition rate of different treatment combinations on the inoculated fungus fusarium oxysporum of melon is significantly different from that of the control treatment group, and reaches a significant and extremely significant level. Among them, the effect of the ficus complex bactericide, 0.5% chitosan solution and 1 mu mol / L nano-silver solution compounded at 1:1:1 is the best, followed by the ficus complex bactericide and 1 mu mol / L nano-silver solution 1:1 compound and the ficus complex bactericide, and the inhibition rates of fusarium oxysporum on the melon peel are 48.20%, 44.83% and 38.42% respectively.

[0100] By Figure 6 As can be seen from the middle B figure, the inhibition rate of different treatment combinations on the inoculated fungus trichothecium roseum of melon is significantly different from that of the control treatment group, and reaches a significant and extremely significant level. Among them, the effect of the ficus complex bactericide, 0.5% chitosan solution and 1 mu mol / L nano-silver solution compounded at 1:1:1 is the best, followed by the ficus complex bactericide and 0.5% chitosan solution 1:1 compound and the ficus complex bactericide, and the inhibition rates of trichothecium roseum on the melon peel are 58.67%, 47.88% and 46.09% respectively.

[0101] By Figure 6 As can be seen from the middle C figure, the inhibition rate of different treatment combinations on the inoculated fungus alternaria alternata of melon after harvest is significantly different from that of the control treatment group, and reaches a significant and extremely significant level. Among them, the effect of the ficus complex bactericide, 0.5% chitosan solution and 1 mu mol / L nano-silver solution compounded at 1:1:1 is the best, followed by the ficus complex bactericide and 0.5% chitosan solution 1:1 compound and the ficus complex bactericide, and the inhibition rates of alternaria alternata on the melon peel are 52.18%, 45.31% and 42.11% respectively.

[0102] Comprehensively, different treatment combinations have certain inhibition effect on the inoculated fungus fusarium oxysporum, trichothecium roseum and alternaria alternata of melon, but the effect of the ficus complex bactericide, 0.5% chitosan solution and 1 mu mol / L nano-silver solution compounded at 1:1:1 on the inhibition of the fungi on the melon peel is the best, which significantly inhibits the growth and spread of the fungi on the melon peel.

[0103] The application has the following beneficial effects:

[0104] (1) Ficus leaf is a kind of natural plant leaf without chemical pollution, high safety, rich resources without destroying ecological environment, and strong bacteriostasis.

[0105] (2) The secondary metabolites of plant source pesticides are rich, have strong targeting effect, good environmental compatibility and are not easy to produce drug resistance, etc., through the compounding of plant source pesticides and chemical fungicides, the toxic effect and drug resistance problem of chemical fungicides are reduced, and the problems of slow effect and unstable efficacy of plant source pesticides are also solved.

[0106] (3) The plant source bacteriostatic agent and the chemical bactericide are used for synergistic effect to carry out the green prevention and treatment of postharvest diseases of melon, the compound agent reduces the dosage of the chemical bactericide by 66.67%, but increases the drug efficacy by 25.59%, and reduces the pesticide residue by 65.6% to 78.2%.

[0107] (4) The plant source bactericide and the chemical bactericide are combined organically, and the advantages of the two are combined. The plant source compound bactericide has the functions of obviously reducing the rot of melon, reducing the water loss, increasing the gloss of the melon skin and the like, and is suitable for postharvest storage and preservation of melon.

[0108] The application provides a plant source nano compound bactericide and a preparation method and application thereof, the plant source nano compound bactericide uses the synergistic effect of a plant source bacteriostatic agent and a chemical bactericide to carry out the green prevention and treatment of postharvest diseases of melon, can obviously reduce the rot of melon, reduce the water loss, increase the gloss of the melon skin and the like, and is suitable for postharvest storage and preservation of melon.

[0109] The above technical features respectively constitute various embodiments of the application, have strong adaptability and implementation effect, and can increase or reduce unnecessary technical features according to actual needs to meet the needs of different situations.

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Claims

1. A plant-derived nanocomposite bactericide, characterized in that... The raw materials, by mass, include: 1 part fig leaf compound bactericide, 1 part nano silver solution and 1 part chitosan solution; wherein, the fig leaf compound bactericide is composed of fig leaf extract mother liquor and amistar diluted solution; The fig leaf compound bactericide is obtained by mixing fig leaf extract stock solution and amistar diluted solution in a mass ratio of 6:1 to 3:

1. The concentration of azoxystrobin in the amistar diluted solution is 0.5 g / L, and the concentration of fig leaf extract stock solution is 1 g / mL. The fig leaf extract mother liquor was prepared according to the following steps: The first step is to wash, dry, and crush the fig leaves to obtain fig leaf powder. The second step involves ultrasonically extracting fig leaves with ethanol 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 the ethanol. The concentrate is then dissolved in sterile water to obtain the fig leaf extract mother liquor.

2. The plant-derived nanocomposite bactericide according to claim 1, characterized in that... The chitosan solution has a mass fraction of 0.5% to 1%.

3. The plant-derived nanocomposite bactericide according to claim 1 or 2, characterized in that... The concentration of the nano-silver solution ranges from 1 μmol / L to 3 μmol / L.

4. The plant-derived nanocomposite bactericide according to claim 1, characterized in that... The plant-derived nanocomposite bactericide was prepared by the following method: Step 1: Extract fig leaves with ethanol. After concentrating the extract, obtain fig leaf extract mother liquor. Measure amistar solution and add it to sterile distilled water to obtain amistar diluted solution with a concentration of 0.5 g / L. Mix the fig leaf extract mother liquor and the amistar diluted solution in a ratio of 6:1 to 3:1 to obtain a fig leaf compound fungicide. Step 2: Take silver nitrate particles, add them to sterile water, stir evenly, and then sonicate to obtain a nano silver solution. Step 3: Add chitosan to glacial acetic acid solution, add Tween, dissolve, filter to remove insoluble matter, and obtain chitosan solution, wherein the volume fraction of glacial acetic acid solution is 0.5%; Step four: Mix fig leaf compound fungicide, nano silver solution and chitosan solution in a mass ratio of 1:1:1 to obtain plant-derived nano compound fungicide.

5. The plant-derived nanocomposite bactericide according to claim 4, characterized in that... In step three, Tween is added at a rate of 0.5 mL per 100 mL of glacial acetic acid solution.

6. The plant-derived nanocomposite bactericide according to claim 4 or 5, characterized in that... In the second step, the ultrasonic time is 30 to 40 minutes, and the extraction temperature is 30°C to 40°C; or / and, in the second step, the material-to-liquid ratio is 1:20 to 1:

30.

7. A method for preparing a plant-derived nanocomposite bactericide according to claim 1, 2, 3, 5, or 6, characterized in that... Includes the following steps: Step 1: Extract fig leaves with ethanol. After concentrating the extract, obtain fig leaf extract mother liquor. Measure a miconazole solution and add it to sterile distilled water to obtain a miconazole diluted solution with a concentration of 0.5 g / L. Mix the fig leaf extract mother liquor and the miconazole diluted solution at a ratio of 6:1 to 3:1 to obtain a fig leaf compound fungicide. Step 2: Take silver nitrate particles, add them to sterile water, stir evenly, and then sonicate to obtain a nano silver solution. Step 3: Add chitosan to glacial acetic acid solution, add Tween, dissolve, filter to remove insoluble matter, and obtain chitosan solution, wherein the volume fraction of glacial acetic acid solution is 0.5%; Step four: Mix fig leaf compound fungicide, nano silver solution and chitosan solution in a mass ratio of 1:1:1 to obtain plant-derived nano compound fungicide.

8. The application of a plant-derived nanocomposite bactericide according to any one of claims 1 to 6 in the preservation of melons.

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