Nano silicon-calcium concentrated liquid as well as preparation method and application thereof

Abstract

The invention discloses a nano silicon-calcium concentrated liquid and a preparation method and application thereof. According to the nano silicon-calcium concentrated liquid, silicon and calcium are respectively dispersed in water in the form of SiO2 and Ca < 2 + >; wherein the mass ratio of SiO2 to Ca < 2 + > is (1-10): (1-10); the concentration of silicon calcium is 80-300 g / L. The problem of antagonism of liquid silicate and calcium ions is solved, silicon and calcium exist in the forms of nano SiO2 single molecules and Ca < 2 + > ions and are uniformly and stably dispersed in medium water, the absorption rate of plant root systems and leaves is remarkably increased, bitter pox diseases of apples in the mature period and the storage period are reduced, and then the apple quality is improved; the composition can be used for preventing and treating the apple bitter pit disease, and meanwhile, the storage stability of apples is ensured; the product can be stored for more than 24 months at normal temperature, and is high in stability, convenient to use and convenient to popularize.

Description

Technical Field

[0001] The invention relates to a nano-silicon calcium concentrated liquid, a preparation method and application thereof, and belongs to the technical field of nano-silicon calcium concentrated liquid. Background Art

[0002] Apple bitter pit disease, also known as bitter pit disease, is a physiological disease that often occurs during the ripening and storage period of apples, and is mainly manifested on the fruit. Symptoms begin to appear when the fruit is nearly ripe and continue to develop during the storage period. The lesions mostly occur near the calyx concave part, and rarely near the fruit shoulder. The flesh under the skin of the diseased part first becomes diseased, producing brown lesions, and the external color is dark, with dark purple-red spots on red varieties, dark green spots on green varieties, and gray-brown spots on cyan varieties. In the late storage period, the diseased part is damaged by saprophytes, and discoloration and rot, the flesh of the diseased part shrinks, the epidermis necrotizes, and sunken brown spots appear, which are 2 to 3 mm deep in the flesh and have a bitter taste. There are generally 3 to 5 lesions on lightly diseased fruits, and 60 to 80 on severe ones, covering the fruit surface.

[0003] Apple bitter pit disease is mainly caused by physiological calcium deficiency in the tree. When the calcium ion concentration in apples is lower than 110ppm, the respiration rate increases, the protoplasm and vacuole membrane collapse, and the thin-walled cells under the epidermal tissue cells become reticular, causing the internal tissue of the fruit to become soft, and even brown spots appear on the flesh, and sunken spots appear on the outside. When the calcium ion concentration in apples is higher than 110ppm, the respiration is stable, the protein and nucleic acid synthesis rates increase, and the fruit behaves normally.

[0004] Silica and calcium have a synergistic effect in plants, which can promote the absorption and transportation of calcium by the roots and reduce the probability of bitter pit disease (caused by calcium deficiency). However, when silicate ions in liquid silicates meet calcium ions, a chemical reaction will occur to generate insoluble calcium silicate precipitates. This precipitation reaction reduces the concentration of calcium ions and silicate ions in the solution, inhibiting their original chemical activities and functions, thereby reducing biological effectiveness. Summary of the invention

[0005] The present invention provides a nano-silicon calcium concentrated liquid, a preparation method and an application thereof, wherein the silicon calcium is respectively SiO 2 and Ca 2+ It is dispersed in the water in the form of calcium, which promotes the absorption of calcium by the roots and reduces the occurrence of bitter pit disease in apples during the ripening and storage periods.

[0006] In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows:

[0007] A nano-silicon calcium concentrated liquid, silicon and calcium are respectively SiO 2 and Ca 2+ dispersed in water in the form of 2 With Ca2+ The mass ratio is (1-10): (1-10); the concentration of silicon and calcium is 80-300g / L.

[0008] The above silicon calcium concentration refers to SiO 2 and Ca 2+ The sum of the contents.

[0009] In the nano-silicon calcium concentrated liquid of the present application, silicon calcium is respectively 1 to 10 nanometers SiO 2 Single molecules and Ca 2+ It exists in the form of ions and is evenly and stably dispersed in the medium water, rather than calcium silicate molecules (CaSiO 3 ). It significantly improves the absorption rate of plant roots and leaves, and at the same time increases cell strength. It combats various problems caused by adverse environments (low temperature, high temperature, drought, salinity, etc.), increases oxygen supply, strengthens the inner wall strength of vascular bundles, and reduces vascular bundle diseases. And drip irrigation into the soil can form different encapsulation forms with soil colloidal particles, forming a larger soil aggregate structure, reducing the EC value (electrical conductivity) in the soil, and reducing the risk of metal cadmium enrichment and aluminate passivation in acidic soils.

[0010] The preparation method of the nano-silicon calcium concentrated liquid comprises the following steps:

[0011] 1) Preparation of Nano-SiO 2 :

[0012] 1.1) Mix ethyl orthosilicate and anhydrous ethanol, add NH 4 F, placed in a low-temperature water bath at 3-5°C, reacted for 20-30 minutes, to obtain a pre-hydrolyzed solution; in this step, fluoride ions (F-) attack the Si-O bond of TEOS to generate highly active silicic acid intermediates, inhibit excessive polycondensation, and control the particle size to <20nm;

[0013] 1.2) Add hexadecyl trimethyl ammonium bromide to the pre-hydrolyzed solution, and adjust the pH to 9.5-10 with 25% ammonia water, react at 35-45°C for 1-2h, and successively extract, purify, centrifuge, wash, and supercritically dry to obtain nano-SiO 2 ; In this step, CTAB cooperates with self-assembly and acts as a soft template to guide the condensation of silicate to form an ordered and uniform structure;

[0014] 2) Nano-SiO 2 Passivation: Add 3-aminopropyltriethoxysilane to anhydrous ethanol, add acetic acid to adjust the pH to 4-4.5, promote the hydrolysis and directional condensation of silane, stir evenly, add nano-SiO 2, nitrogen protection was introduced, the reaction was carried out at 60-70°C for 8-10 hours, the solid was collected by centrifugation, washed with anhydrous ethanol and deionized water in turn to remove free silane and by-products, dispersed in a 1wt% dodecyl phosphate (DDP) ethanol solution, ultrasonically treated at 30-40°C for 0.5-1 hour to promote phosphate adsorption, centrifuged and dried, and 2 A dense anti-calcium layer is formed on the surface to obtain passivated nano-SiO 2 ; This step is based on nano-SiO 2 A silane-phosphate double-layer passivation structure is formed on the surface, which can significantly reduce the reactivity with calcium ions while maintaining the high specific surface area and dispersibility of the material, improving its stability and durability.

[0015] 3) Heat the deionized water to 60-80°C, add a mixture of polyoxyethylene sorbitan fatty acid ester (Tween 80) and polyethylene glycol octylphenyl ether (Triton X-100) in an amount of 1-3% by mass of the deionized water, stir evenly, and add passivated nano-SiO 2 and calcium-containing compounds, stir evenly, add an auxiliary agent in an amount of 0.1-2% by mass of deionized water, stir at 1000-1500r / min for 30-60min, cool naturally to room temperature, stir at a speed of 200-300r / min during the cooling process, and obtain nano-silicon calcium concentrated liquid.

[0016] % in this application, unless otherwise specified, are all mass percentages.

[0017] In the above step 1.1), the volume ratio of ethyl orthosilicate to anhydrous ethanol is 1:(3-5); NH 4 The mass dosage of F is 1 to 3% of the mass of ethyl orthosilicate.

[0018] In the above step 1.2), the mass amount of hexadecyltrimethylammonium bromide is 2-5% of the mass of ethyl orthosilicate.

[0019] In order to ensure that SiO 2 The fineness is small, and agglomeration is avoided or reduced. In step 1.2), the nano-SiO is extracted with n-hexane, and the lower ethanol-water phase is collected, centrifuged, washed with ethanol, and supercritically dried to obtain nano-SiO 2 The drying medium for supercritical drying is CO 2 , supercritical drying can effectively inhibit particle agglomeration.

[0020] In order to improve the passivation effect, in the above step 2), the mass dosage of 3-aminopropyltriethoxysilane is nano-SiO 2 15-20% of the mass; the volume ratio of 3-aminopropyltriethoxysilane to anhydrous ethanol is 1: (20-30)

[0021] In order to ensure the dispersion effect, in step 3), the auxiliary agent is at least one of sodium alginate, polymerized glutamic acid, polymerized aspartic acid, aminobutyric acid and betaine.

[0022] In order to improve the dispersion effect, it is further preferred that in step 3), the auxiliary agent is a mixture of sodium alginate, polymerized glutamic acid, polymerized aspartic acid, aminobutyric acid and dodecyl dimethyl betaine in a mass ratio of 1:1:1:1:(1-3).

[0023] The above-mentioned sodium alginate, polyglutamic acid, polyaspartic acid, aminobutyric acid and dodecyl dimethyl betaine can not only enhance the stability of the concentrated liquid, but also have the functions of regulating plant growth, retaining water and increasing efficiency (fertilizer), promoting plant absorption of nutrients (such as calcium and iron), improving plant resistance (enhancing cold and drought resistance), enhancing permeability, inhibiting pathogens, etc., and they promote each other synergistically to improve the quality of apples.

[0024] In the above step 3), the calcium-containing compound is ionic calcium (calcium nitrate, calcium chloride, etc.) or organic calcium.

[0025] More preferably, in the above step 3), the calcium compound is organic calcium, and the organic calcium is at least one of chelated calcium (calcium ethylenediaminetetraacetate EDTA-Ca, calcium ethylenediaminetetramethylenephosphonate EDTMPS-Ca, etc.), sugar alcohol calcium, calcium gluconate or calcium lactate.

[0026] In order to further improve the stability of the concentrate, in the above step 3), the mass ratio of polyoxyethylene sorbitan fatty acid ester to polyethylene glycol octylphenyl ether is preferably 1:1.

[0027] When the above concentrate is used, it is diluted 400 to 800 times to obtain a diluted solution, which is sprayed on leaves for the prevention and treatment of apple bitter pit disease. The single usage of the diluted solution is 200 to 400 jin / mu;

[0028] If bagged, spray two to three times during the young fruit stage and once after removing the bag;

[0029] Without bagging, spray for the first time 30-45 days after flowering, and then spray once every 3 weeks until harvest. Spray the leaves 5-7 times during the entire growth cycle.

[0030] The technologies not mentioned in the present invention are all referred to the prior art.

[0031] The nano-silicon calcium concentrated liquid of the present invention has the following beneficial effects:

[0032] First, it solves the problem of antagonism between liquid silicate and calcium ions. Silicon and calcium are nano-SiO 2 Single molecules and Ca 2+It exists in the form of ions and is evenly and stably dispersed in the medium water, which significantly improves the absorption rate of plant roots and leaves, thereby improving the quality of apples.

[0033] Second, it overcomes calcium absorption barriers and can be used to prevent and treat apple bitter pit disease, while ensuring the storage stability of apples.

[0034] Third, at room temperature, the product can be stored for more than 24 months, has high stability, is easy to use and easy to promote.

[0035] Fourth, use nano-silicon calcium liquid, diluted with 400-800 times water and spray on the leaves, two to three times during the young fruit stage and once after removing from the bags; for unbagged fruits, spray five to six times throughout the process, and the rate of high-quality fruits will reach more than 95%. DETAILED DESCRIPTION

[0036] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with the embodiments, but the content of the present invention is not limited to the following embodiments.

[0037] Example 1

[0038] Preparation of nano-silicon:

[0039] Mix 300 mL of ethyl orthosilicate with 1200 mL of anhydrous ethanol and add 3 g of NH 4 F, magnetic stirring (300rpm) to form a homogeneous system; placed in a 5℃ low-temperature water bath, stirred (300rpm) for 30 minutes. Then add 50ml of 0.5mol / L CTAB (hexadecyltrimethylammonium bromide) aqueous solution, and adjust the pH to 9.5 with 25% ammonia water, and react for 2h at 45℃ with magnetic stirring (300rpm). Add 500mL of n-hexane, shake for 10 minutes, and let stand for stratification. The lower layer contains nano-SiO 2 The upper layer is the n-hexane-byproduct (ethyl glycolate) phase. The lower ethanol-water phase is taken and centrifuged at 10,000 rpm for 15 minutes. The precipitate is collected and washed three times with anhydrous ethanol to replace the residual water. The precipitate is placed in a supercritical drying device and liquid CO is introduced. 2 , the temperature was raised to 35°C, the pressure was increased to 8MPa, and maintained for 2 hours to obtain nano-SiO 2 , particle size 5-8nm. FTIR: 1090cm -1 The reaction was carried out at room temperature of 20 to 25°C unless otherwise specified.

[0040] Example 2

[0041] Nano-SiO 2 Passivation:

[0042] 4 mL of 3-aminopropyltriethoxysilane was added to 100 mL of anhydrous ethanol, acetic acid was added dropwise to adjust the pH to 4.5, and the mixture was stirred (200 rpm) for 5 min to mix well. 20 g of nano-SiO 2 (prepared according to the method of Example 1), under nitrogen protection and stirring at 200 rpm, refluxed in a 70°C water bath for 10 hours, the solid was collected by centrifugation, washed three times with anhydrous ethanol and deionized water respectively, then dispersed in 50 mL of ethanol solution containing 1% dodecyl phosphate monoester, ultrasonically treated (100 W) for 1 hour (40°C), centrifuged (10000 rpm, 15 minutes), vacuum dried at 60°C for 6 hours, and dried on SiO 2 A double layer of dense anti-calcium layer is formed on the surface. The above-mentioned temperature is not particularly specified, and is carried out at room temperature of 20 to 25°C.

[0043] FTIR analysis: 3450cm -1 (-NH 2 stretching vibration) and 2920cm -1 (-CH 2 - characteristic peak), proving that 3-aminopropyltriethoxysilane was successfully grafted. 1050cm -1 The characteristic peak of P=O bond appears at , indicating the formation of phosphate layer.

[0044] Zeta potential test: Before passivation: surface potential -35mV (strong negative charge, easy to adsorb Ca 2+ ). After passivation: surface potential +10mV.

[0045] Anti-calcium adsorption experiment:

[0046] 0.2g SiO before and after passivation 2 Immerse in 100 mL of 5 mM Ca 2+ Solution (pH 7), after 24 hours, the Ca content of the solution was measured 2+ Concentration. Ca before passivation 2+ The adsorption amount was 48.3 mg / g, and the Ca 2+ Adsorption amount: 0.2mg / g.

[0047] Comparative Example 1

[0048] The difference from Example 2 is that the step of treating dodecyl phosphate monoester is omitted, and the rest is referred to Example 2, and the specific steps are as follows:

[0049] 4 mL of 3-aminopropyltriethoxysilane was added to 100 mL of anhydrous ethanol, acetic acid was added dropwise to adjust the pH to 4.5, and the mixture was stirred (200 rpm) for 5 min to mix well. 20 g of nano-SiO 2(Prepared according to the method of Example 1), under nitrogen protection and stirring at 200 rpm, reflux in a 70°C water bath for 10 hours, collect the solid by centrifugation, wash with anhydrous ethanol and deionized water three times each, centrifuge (10000 rpm, 15 minutes), and vacuum dry at 60°C for 6 hours.

[0050] The experimental method for calcium adsorption resistance refers to Example 2. In this example, after passivation, Ca 2+ Adsorption amount: 18.1 mg / g.

[0051] Comparative Example 2

[0052] The difference from Example 2 is that the step of treating 3-aminopropyltriethoxysilane is omitted, and the rest is referred to Example 2, and the specific steps are as follows:

[0053] 20g nano-SiO 2 (prepared according to the method of Example 1), dispersed in 50 mL of ethanol solution containing 1% dodecyl phosphate monoester, ultrasonically treated (100 W) for 1 hour (40°C), centrifuged (10000 rpm, 15 minutes), and vacuum dried at 60°C for 6 hours.

[0054] The experimental method for calcium adsorption resistance refers to Example 2. In this example, after passivation, Ca 2+ Adsorption amount: 36.7 mg / g.

[0055] Example 3

[0056] The difference from Example 2 is that 3-aminopropyltriethoxysilane is replaced by γ-methacryloxypropyltrimethoxysilane, and the rest is the same as Example 2.

[0057] Example 4

[0058] Preparation of Nano-Silicon Calcium Concentrated Liquid:

[0059] Heat 2L of deionized water to 70°C, add 20g of polyoxyethylene sorbitan fatty acid ester (Tween 80) and 20g of polyethylene glycol octylphenyl ether (Triton X-100), stir at 200rmp for 2min, add 100g of passivated nano-SiO 2 (prepared according to the method of Example 2) and 100g of calcium lactate pentahydrate, stirred at 200rmp for 5min, added 20g of additives (sodium alginate 4g, polyglutamic acid 4g, polyaspartic acid 4g, aminobutyric acid 4g, dodecyl dimethyl betaine 4g), stirred at 1200r / min for 40min, cooled naturally to room temperature, stirred at a speed of 200r / min during the cooling process, and obtained nano-silicon calcium concentrated liquid. X-ray diffraction (XRD) test showed that no characteristic diffraction peak corresponding to calcium silicate appeared, and SiO 2The characteristic diffraction peak of . The calcium ion content was determined by ion chromatography and was 6.41g / L. This shows that silicon and calcium are nano-SiO 2 Single molecules and Ca 2+ The above-mentioned temperature is not particularly specified, and is carried out at room temperature of 20 to 25°C.

[0060] Centrifugal stability test: 3000rpm, centrifuge for 30 minutes, stand for 10 minutes, no precipitation.

[0061] Stability at room temperature: ≥24 months.

[0062] Comparative Example 3

[0063] The difference from Example 4 is that no auxiliary agent is added, and the rest is the same as Example 4. Centrifugal stability test: 3000 rpm, centrifuge for 30 minutes, stand for 10 minutes, and precipitate is generated.

[0064] Comparative Example 4

[0065] The difference from Example 4 is that 20g sodium alginate, 20g polymerized glutamic acid, 20g polymerized aspartic acid, 20g aminobutyric acid, or 20g dodecyl dimethyl betaine are used as auxiliary agents, and the rest are the same as Example 4. Centrifugal stability test: 3000rpm, centrifugation for 30 minutes, standing for 10 minutes, precipitation is generated.

[0066] Comparative Example 5

[0067] Different from Example 4, Triton X-100 was omitted and the amount of polyoxyethylene sorbitan fatty acid ester (Tween 80) was increased to 40 g. Centrifugal stability test: 3000 rpm, centrifuge for 30 minutes, stand for 10 minutes, and a precipitate is generated.

[0068] Comparative Example 6

[0069] Different from Example 4, polyoxyethylene sorbitan fatty acid ester (Tween 80) was omitted, and polyethylene glycol octylphenyl ether (Triton X-100) was increased to 40 g. Centrifugal stability test: 3000 rpm, centrifuge for 30 minutes, stand for 10 minutes, and precipitate is generated.

[0070] Example 5

[0071] The difference from Example 4 is that the passivation nano-SiO 2 The preparation was carried out according to the method of Example 3, and the rest was referred to Example 4. The calcium ion content was determined by ion chromatography and was 5.92 g / L. This indicates that silicon calcium is nano-SiO 2 Single molecules and Ca 2+It exists in the form of ions. Centrifugal stability test: 3000rpm, centrifuge for 30 minutes, stand for 10 minutes, no precipitation. Room temperature stability: ≥24 months.

[0072] Application examples:

[0073] Experimental base: Luochuan, Shaanxi. Apple species: Qincui, 5 years. Spraying method: dilute the silicon calcium agent obtained in each case 600 times, spray on the leaves, 3 parallel tests per case, each test is 1 mu, 60 plants per mu, and the spraying amount per mu is 250 catties per time. The first spraying is in late May, without bagging, and spray once every 3 weeks until harvest (late September). Spraying with clean water is used as the control CK.

[0074] Comparative application example 1

[0075] Nano calcium silicate solution is used, and the preparation method refers to Example 3 in CN 109482635 B.

[0076] Comparative Application Example 2

[0077] 200 g of calcium lactate pentahydrate was dissolved in 2 L of deionized water to obtain a calcium lactate solution.

[0078] Comparative Application Example 3

[0079] Heat 2L of deionized water to 70°C, add 20g of polyoxyethylene sorbitan fatty acid ester (Tween 80) and 20g of polyethylene glycol octylphenyl ether (Triton X-100), stir at 200rmp for 2min, add 200g of passivated nano-SiO 2 (Prepared according to the method of Example 2), stirred at 200 rpm for 5 min, added 20 g of additives (4 g of sodium alginate, 4 g of polymerized glutamic acid, 4 g of polymerized aspartic acid, 4 g of aminobutyric acid, 4 g of dodecyl dimethyl betaine), stirred at 1200 rpm for 40 min, naturally cooled to room temperature, stirred at a speed of 200 rpm during the cooling process, and obtained nano-silicon concentrated liquid.

[0080] Except for the silica-calcium spraying step, the other conditions of each application example are the same.

[0081] The following characteristics are considered good quality fruit: the fruit is regular, without deformity (such as deflection, depression), and the fruit stalk is intact; the fruit diameter is ≥80mm; the coloring area is ≥85%, and the color is even and bright; the base color is yellow-green or yellow-white, without blue spots or too light coloring areas. The fruit was picked in late September, and 300 apples from each treatment of "Qincui" were randomly surveyed to calculate the good fruit rate and average single fruit weight.

[0082]

[0083] Apple bitter pit disease classification:

[0084]

[0085]

[0086] Grade 0 is considered good fruit, grades 1-4 are considered diseased fruit, and the incidence rate is the percentage of diseased fruits to the number of samples.

[0087] The fruits were picked in late September. 300 fruits from each treatment of 'Qincui' apples were randomly surveyed to count the occurrence of bitter pit disease, which was counted as the first statistics. After the survey, 300 good fruits from each treatment were selected and stored in a cold storage (temperature 1-3℃, relative humidity 90-95%) until the end of February of the following year, for a second statistics.

[0088]

Claims

1. A nano-silicon calcium concentrated liquid, characterized in that: Silicon calcium is SiO2 and Ca 2+ dispersed in water in the form of SiO2 and Ca 2+ The mass ratio is (1-10): (1-10); the concentration of silicon and calcium is 80-300g / L.

2. A method for preparing the nano-silicon-calcium concentrated liquid according to claim 1, characterized in that: The steps include: 1) Preparation of nano-SiO2: 1.1) Mix ethyl orthosilicate and anhydrous ethanol, add NH4F, place in a low-temperature water bath at 3-5°C, and react for 20-30 minutes to obtain a pre-hydrolyzed solution; 1.2) adding hexadecyltrimethylammonium bromide to the pre-hydrolyzed solution, and adjusting the pH to 9.5-10 with 25% ammonia water, reacting at 35-45°C for 1-2h, and sequentially extracting, purifying, centrifuging, washing, and supercritical drying to obtain nano-SiO2; 2) Nano-SiO2 passivation: 3-aminopropyltriethoxysilane is added to anhydrous ethanol, acetic acid is added dropwise to adjust the pH to 4-4.5, stirred evenly, nano-SiO2 is added, nitrogen is introduced for protection, and the reaction is carried out at 60-70°C for 8-10 hours. The solid is collected by centrifugation, washed with anhydrous ethanol and deionized water in turn, and dispersed in a 1% dodecyl phosphate (DDP) ethanol solution, ultrasonically treated at 30-40°C for 0.5-1 hour, centrifuged and dried to form a dense anti-calcium layer on the surface of SiO2 to obtain passivated nano-SiO2; 3) preparing a concentrated solution: heating deionized water to 60-80° C., adding a mixture of polyoxyethylene sorbitan fatty acid ester and polyethylene glycol octylphenyl ether in an amount of 1-3% by mass of deionized water, stirring evenly, adding passivated nano-SiO2 and calcium-containing compounds in proportion, stirring evenly, adding an auxiliary agent in an amount of 0.1-2% by mass of deionized water, stirring at 1000-1500 r / min for 30-60 min, cooling naturally to room temperature, stirring at a speed of 200-300 r / min during the cooling process, and obtaining a nano-silicon calcium concentrated liquid.

3. The preparation method according to claim 2, characterized in that: In step 1.1), the volume ratio of tetraethyl orthosilicate to anhydrous ethanol is 1:(3-5); the mass amount of NH4F is 1-3% of the mass of tetraethyl orthosilicate.

4. The preparation method according to claim 2 or 3, characterized in that: In step 1.2), the mass amount of hexadecyltrimethylammonium bromide is 2-5% of the mass of ethyl orthosilicate.

5. The preparation method according to claim 2 or 3, characterized in that: In step 1.2), extract with n-hexane, collect the lower ethanol-water phase, centrifuge, wash with ethanol, and supercritically dry to obtain nano-SiO2.

6. The preparation method according to claim 2 or 3, characterized in that: In step 2), the mass amount of 3-aminopropyltriethoxysilane is 15-20% of the mass of nano-SiO2; the volume ratio of 3-aminopropyltriethoxysilane to anhydrous ethanol is 1:(20-30).

7. The preparation method according to claim 2 or 3, characterized in that: In step 3), the auxiliary agent is at least one of sodium alginate, polymerized glutamic acid, polymerized aspartic acid, aminobutyric acid and betaine.

8. The preparation method according to claim 2 or 3, characterized in that: In step 3), the auxiliary agent is a mixture of sodium alginate, polymerized glutamic acid, polymerized aspartic acid, aminobutyric acid and dodecyl dimethyl betaine in a mass ratio of 1:1:1:1:(1-3).

9. The preparation method according to claim 2 or 3, characterized in that: In step 3), the calcium-containing compound is ionic calcium or organic calcium, and the organic calcium is at least one of chelated calcium, sugar alcohol calcium, gluconate calcium or calcium lactate.

10. An application of the nano-silicon calcium concentrated liquid according to claim 1, characterized in that: After diluting 400 to 800 times, the diluted solution is sprayed on the leaves for the prevention and treatment of apple bitter pit disease. The single usage of the diluted solution is 200 to 400 catties / mu. If bagged, spray two to three times during the young fruit stage and once after removing the bag; Without bagging, the first spraying is done 30-45 days after flowering, and then once every 3 weeks until harvest.

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