Fruit anti-sunburn protective agent as well as preparation method and application thereof

Abstract

The invention discloses a sunscald-preventing protective agent for fruits. The sunscald-preventing protective agent is prepared from the following raw materials in parts by mass: 1 to 20 parts of monodisperse calcium carbonate filter cake, 0.01 to 0.9 part of ethyoxyl modified polytrisiloxane, 0.01 to 0.8 part of polyvinyl acetate emulsion, 0.01 to 0.8 part of glycerol, 0.01 to 0.8 part of enzyme and 10 to 180 parts of water. The raw materials are mixed in two steps according to a certain sequence, stirred and dispersed to obtain the novel fruit anti-sunburn protective agent, and the novel fruit anti-sunburn protective agent can be used for fruit anti-sunburn planting after being diluted with water until the solid content of calcium carbonate is 2-6%. The sunburn-preventing protective agent is safe and non-toxic, can be sprayed on fruit surfaces or fruit tree leaf surfaces during use, can remarkably avoid the risk that fruits and fruit trees are burnt by strong sunlight, improves the disease resistance and stress resistance of the fruit trees, and reduces the occurrence probability of sunburn spots, sunburn fruits and diseased fruits. The anti-sunburn protective agent for the fruits has no great influence on transmission of visible light, does not influence normal photosynthesis of fruit trees, and can obviously improve the yield and quality of the fruits when being used for fruit planting compared with other sunshade modes.

Description

Technical Field

[0001] The invention belongs to the field of plant growth protective agents, and in particular relates to a fruit anti-sunburn protective agent and a preparation method and application thereof. Background Art

[0002] Sunscald of fruit is a physiological disease caused by solar radiation heat. In late summer and early autumn in most parts of my country, the weather is clear and the temperature is high. The intensity and duration of solar radiation are the longest in the year. Long-term high-intensity sunlight radiation can make the field temperature reach above 40°C, and the temperature of the fruit surface and leaves exposed to direct sunlight can reach as high as 55-60°C, leading to high-temperature dehydration of leaves and fruits and destruction of the antioxidant defense system, causing irreversible burns - this is sunscald.

[0003] Sunscald mainly harms fruits in the expansion stage and larger leaves exposed to direct sunlight. After sunscald occurs, a yellow halo will appear on the fruit, mostly in a round shape, and then gradually expand. The oil cells on the fruit's epidermal cells rupture until they turn brown, black and necrotic. Sunscald is a common disease. Even if there are no obvious lesions on the peel, the flesh will become lignified due to high temperature dehydration and lose its edible value. In addition, sunscald can form chlorotic yellow spots on the leaves, which are easily infected with anthracnose after rain. Therefore, sunscald not only directly damages fruit trees, but also significantly reduces their resistance to adversity.

[0004] At present, measures such as bagging, covering with shade nets, and applying lime milk are often used to prevent sunburn in the process of fruit tree planting. These measures can achieve certain results, but there are problems such as high cost, large labor demand, and poor overall effect. Some protective measures also have their own negative effects that cannot be overcome. For example, whether it is bagging or covering with shade nets, it will inhibit the normal photosynthesis of fruit trees; and the use of lime milk will bring huge labor costs. Therefore, it is urgent to develop a safe and low-cost protective agent that can effectively protect fruits from sunburn. Summary of the invention

[0005] The main purpose of the present invention is to provide a fruit anti-sunburn protective agent, which can be directly sprayed onto the surface of the fruit or the leaves of the fruit tree when used, which can significantly avoid the risk of fruits and fruit trees being burned by strong sunlight, improve the disease resistance and stress resistance of the fruit trees, and reduce the probability of sunburn spots, sun fruits, and diseased fruits.

[0006] The technical solution adopted by the present invention to achieve the above-mentioned purpose is:

[0007] A fruit sunburn protection agent, the raw material composition of which comprises, by weight: 1-20 parts of monodisperse calcium carbonate filter cake, 0.01-0.9 parts of ethoxy-modified polytrisiloxane, 0.01-0.8 parts of polyvinyl acetate emulsion, 0.01-0.8 parts of glycerol, 0.01-0.8 parts of enzyme, and 10-180 parts of clean water.

[0008] Further preferably, the raw material composition of the fruit sunburn protection agent includes, by mass: 1 to 20 parts of monodisperse calcium carbonate filter cake, 0.01 to 0.5 parts of ethoxy-modified polytrisiloxane, 0.02 to 0.8 parts of polyvinyl acetate emulsion, 0.01 to 0.5 parts of glycerol, 0.01 to 0.8 parts of enzyme, and 30 to 166 parts of water.

[0009] Furthermore, the mass of the monodisperse calcium carbonate filter cake is 20 to 150 times, preferably 20 to 90 times, that of the ethoxy-modified polytrisiloxane.

[0010] Furthermore, the mass of water is 1.9 to 30 times, preferably 9 to 15 times, that of the monodisperse calcium carbonate filter cake.

[0011] Furthermore, the mass of the monodisperse calcium carbonate filter cake is 25 to 60 times that of the polyvinyl acetate emulsion.

[0012] Furthermore, the mass of the monodisperse calcium carbonate filter cake is 36 to 300 times, preferably 36 to 100 times, that of glycerol.

[0013] Furthermore, the mass of the monodisperse calcium carbonate filter cake is 25 to 300 times that of the enzyme, preferably 25 to 100 times.

[0014] According to the above scheme, the characteristics of the monodisperse calcium carbonate filter cake are as follows: the moisture content of the filter cake is 35% to 40%, the calcium carbonate particles are cubic or nearly spherical, the average particle size is between 200 and 400 nm, and the particles with a particle size greater than 400 nm account for less than 5%; the particle surface is clean, in a monodisperse state, has a small surface energy, and its specific surface area is less than 17m 2 / g, the specific surface area is preferably 13 to 15m 2 / g; the content of harmful metal elements such as cadmium in calcium carbonate is less than 200ppm; the monodisperse calcium carbonate filter cake can be stirred and dispersed in the aqueous solution without adding any chemical dispersant, and can remain stably suspended. Specifically, the monodisperse calcium carbonate filter cake is dispersed in water to obtain a suspension; when the solid content of the suspension is 2% to 5%, it can be stably suspended for more than 2 hours.

[0015] According to the above scheme, the method for preparing the monodisperse calcium carbonate filter cake comprises the following steps:

[0016] S1. Prepare calcium carbonate slurry by calcination, digestion, carbonization and other processes. The calcination process is as follows: select limestone with uniform grain size and harmful heavy metal content of less than 400ppm such as cadmium, lead, chromium as raw material, adopt calcination temperature matching the grain size, and obtain quicklime with ideal activity. The activity of quicklime is between 250 and 300mL (4mol / L HCl, 40±1℃, 10min), and the uniformity and consistency are good; the digestion process is as follows: digest the quicklime obtained by the above calcination in hot water at 50 to 90℃ to obtain lime milk; the aging and impurity removal process is as follows: age the lime milk slurry obtained by digestion for 24 to 48h, and obtain refined raw slurry after filtering and impurity removal; the carbonization process is as follows: add water to the refined raw slurry to adjust the solid content to 8% to 12%, and then carbonize it. The starting temperature of carbonization is 20 to 30℃, CO 2 The content is 30% to 40%, and the slurry is carbonized until the pH value reaches 7.5 to 8.5, and then the carbonization is terminated to obtain the calcium carbonate cooked slurry;

[0017] The calcium carbonate particles in the calcium carbonate cooked slurry are nearly spherical or chain-shaped in shape, the average particle size of the nearly spherical particles is 100 to 150 nm, and the average width (lateral dimension) of the chain-shaped particles is 100 to 150 nm;

[0018] S2. Adding an inorganic salt crystal surface reconstructor and an organic crystal surface reconstructor to the calcium carbonate slurry obtained in S1, and then keeping the temperature at 160-200°C for 2.0-6.0h to obtain a calcium carbonate suspension; wherein the inorganic crystal surface reconstructor is one or more of inorganic salts such as sodium silicate, sodium chloride, aluminum chloride, zinc sulfate, etc., and the amount used is 0.5%-3% of the dry mass of calcium carbonate; the organic crystal surface reconstructor is one or more of organic substances such as ethanol, polyethylene glycol, polyvinyl pyrrolidone, polyvinyl alcohol, sodium dodecylbenzene sulfonate, hexadecyltrimethylammonium bromide, sodium dodecyl sulfate, disodium ethylenediaminetetraacetic acid, etc., and the amount used is 1%-5% of the dry mass of calcium carbonate;

[0019] S3. The calcium carbonate suspension obtained in S2 is filtered and dehydrated to obtain a calcium carbonate filter cake, and the moisture content of the filter cake is controlled between 35% and 40%, that is, a monodisperse calcium carbonate filter cake. At this time, it meets the requirements of "the calcium carbonate particles are cubic or nearly spherical, the average particle size is between 200 and 400nm, and the particles with a particle size greater than 400nm account for less than 10%; the particle surface is clean, in a monodisperse state, with a small surface energy, and a specific surface area of ​​less than 17m 2 / g; the content of harmful metal elements such as cadmium in calcium carbonate is less than 200ppm; it can be dispersed after stirring in an aqueous solution without adding any chemical dispersant and remain stably suspended.

[0020] According to the above scheme, the enzyme is a commercially available agricultural enzyme, which contains agricultural biological agents, polysaccharides, amino acids and other ingredients. When used in combination with calcium carbonate, it can increase the level of absorption of micro-nano calcium carbonate from plants.

[0021] The preparation method of the above-mentioned fruit anti-sunburn protective agent comprises the following steps:

[0022] (1) According to the raw materials of the sunburn protection agent of the present invention and their mass proportions, 1 to 20 parts of monodisperse calcium carbonate filter cake, 0.01 to 0.9 parts of ethoxy-modified polytrisiloxane, 0.01 to 0.8 parts of polyvinyl acetate emulsion, 0.01 to 0.8 parts of glycerol, 0.01 to 0.8 parts of enzyme, and 10 to 180 parts of clean water are prepared;

[0023] (2) placing the monodisperse calcium carbonate filter cake in a small amount of clean water at a temperature of 5 to 30° C. (the weight of the “small amount of clean water” is 1 to 2 times the weight of the monodisperse calcium carbonate filter cake in the formula) and dispersing it in a high-speed disperser at room temperature at a linear speed of 80 to 120 m / min for 15 to 40 min;

[0024] (3) After the stirring in step (2) is completed, the remaining other raw materials and the excess water are added, and the mixture is dispersed in a high-speed disperser at a linear speed of 80 to 120 m / min for 15 to 30 min to obtain the fruit sunburn protection agent of the present invention.

[0025] When the fruit sunburn protection agent of the invention is used, water is added to dilute it to a solid content of calcium carbonate of 2% to 6% before spraying.

[0026] According to the above scheme, the fruits that can be used to prevent sunburn include citrus, apple, pear, grape, pitaya, kiwi, grapefruit, etc.

[0027] The application method of the fruit sunburn protection agent of the present invention is as follows: in dry and rainless weather, the sunburn protection agent of the present invention is diluted and sprayed on the surface of the fruit (generally diluted to a solid content of calcium carbonate of 2% to 6% and then sprayed), without avoiding branches and leaves. Depending on the type of fruit, it is necessary to spray 1 to 4 times during the ripening process of the fruit; when it rains for more than 5 days within less than 24 hours after spraying, and the total rainfall reaches 250 mm or more, it is necessary to spray once more after the rain.

[0028] The present invention selects limestone with uniform grain size and harmful heavy metal content of less than 400ppm such as cadmium, lead, chromium, etc. as the raw material for preparing monodisperse calcium carbonate filter cake, and then adopts a calcination temperature matching the grain size to obtain quicklime with moderate and uniform activity, which is digested and carbonized to obtain calcium carbonate slurry. The limestone with uniform grain size is used to adjust the lime activity through the limestone calcination process to avoid partial raw burning and partial overburning caused by porphyritic grains; the lime with good uniformity and moderate activity is conducive to the control of the digestion reaction, and the uniform lime milk with controllable properties is obtained, and then the control of the later carbonization process is realized, so as to obtain calcium carbonate slurry with expected particle size and grain morphology. The content of harmful heavy metals such as cadmium, lead, chromium, etc. in the limestone is less than 400ppm, which can ensure that the content of harmful heavy metals in the prepared monodisperse calcium carbonate filter cake is less than 200ppm.

[0029] After the carbonization is completed, there is a process step of reconstructing the surface of the grains, which is to promote the reconstruction of the surface of the grains by adding inorganic surface reconstruction agents and organic surface reconstruction agents and keeping them warm at a certain temperature, so as to make the crystals more complete, the particle surface smoother, and reduce the surface energy, which is conducive to dispersion. Among them, the role of the inorganic surface reconstruction agent is to promote crystal development, repair defects, and make the crystals more complete; the role of the organic surface reconstruction agent is to adjust the surface potential of the particles, control the mutual repulsion of the grains in water, and avoid adhesion during the crystal repair process. The present invention controls the average particle size of the calcium carbonate particles to 200-400nm by controlling the temperature and time of the grain surface reconstruction, and is in a highly monodisperse state. This form of calcium carbonate particles can ensure the diffraction and transmission of visible light in the wavelength range of 400-800nm, so it does not affect the photosynthesis of the fruit and the surface coloring, and can effectively absorb ultraviolet light that is harmful to plants (for example, the anti-sunburn protectant of the present invention is diluted to a solid content of calcium carbonate of 2% and sprayed to form a film, and the absorption of ultraviolet rays can reach more than 90%, and the absorption of visible light is less than 40%). The present invention utilizes the relatively wide absorption band of calcium carbonate near the wave number of 1425 to realize the absorption of infrared in the solar spectrum and atmospheric emission, thereby significantly reducing the temperature of the fruit surface. The monodisperse calcium carbonate slurry obtained by the reconstruction of the grain surface is subjected to filter pressing or centrifugation to obtain a monodisperse calcium carbonate filter cake of the required particle size. Among them, filter pressing and centrifugation can discharge excess water to form a monodisperse calcium carbonate filter cake, which is beneficial to the processing and transportation of calcium carbonate, and also rapidly reduces other soluble ions present in the solution during the production process, so as not to affect and interfere with the use and performance of the fruit sunburn protection agent of the present invention.

[0030] On the basis of the above, the present invention uses the monodisperse calcium carbonate filter cake as the main raw material, and mixes with other raw materials and disperses them in clear water, thereby obtaining the fruit sunburn protection agent of the present invention. The monodisperse calcium carbonate filter cake maintains 35% to 40% of water, and maintains a water film and a double electric layer structure between the solid calcium carbonate particles, which can ensure that the surface state and repulsion of the calcium carbonate particles are not destroyed to the greatest extent, and no agglomeration occurs, so that it can be quickly redispersed in the aqueous solution when the disperser assists in stirring, and maintains a stable suspension.

[0031] The fruit sunburn protection agent of the technical solution of the present invention is sprayed on the surface of the fruit to quickly form a light white protective film. Due to the special particle size and dispersibility design of calcium carbonate, the protective film does not affect the transmission of visible light, and thus does not affect the photosynthesis of the fruit. In addition, the present invention utilizes the ultraviolet light absorption and infrared radiation characteristics of calcium carbonate, combined with the particle size design of the present invention, can effectively reduce ultraviolet burns on the surface of the fruit, reduce the temperature of the fruit, and form effective physical and optical protection.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. The fruit sunburn protection agent of the present invention is directly sprayed on the surface of the fruit when used, without having to specifically avoid branches and leaves, and can significantly avoid the risk of fruit and fruit trees being burned by strong sunlight, can effectively absorb ultraviolet rays, radiate infrared rays, and reduce the temperature of the fruit surface. It is used for sunburn-proof fruit planting and reduces the probability of sunburn spots, sun fruits, and diseased fruits.

[0034] 2. The fruit sunburn protection agent of the present invention is safe and non-toxic. When used, it is directly sprayed on the surface of the fruit and the leaves of the fruit tree. It has good physical protection effect, significantly improves the disease resistance and adversity resistance of the fruit, and can be used in fruit planting to significantly improve the yield and quality of the fruit compared with other shading methods;

[0035] 3. The fruit sunburn protection agent of the present invention sprayed on the surface of the fruit and the leaves of the fruit tree does not affect the passage of visible light, does not interfere with the normal photosynthesis of the fruit, increases the fullness of the fruit, and significantly improves the taste and quality of the fruit. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a scanning electron microscope photograph of calcium carbonate particles in the calcium carbonate slurry prepared in Example 1;

[0037] Figure 2 This is a scanning electron microscope photograph of the monodisperse calcium carbonate obtained in Example 1;

[0038] Figure 3 This is a diagram showing the effect of using the sunburn protection agent prepared in Example 1 on citrus fruits;

[0039] Figure 4The figure is a comparison of the surface temperature of citrus fruits after spraying the sunburn protection agent prepared in Example 1 (left figure) and the surface temperature of citrus fruits sprayed with water as a control (right figure);

[0040] Figure 5 This is a comparison diagram of the flesh of ripened citrus fruits after spraying the sunburn protection agent prepared in Example 1 with that after spraying with water;

[0041] Figure 6 This is a scanning electron microscope photograph of calcium carbonate particles in the calcium carbonate slurry prepared in Example 2;

[0042] Figure 7 This is a scanning electron microscope photograph of the monodisperse calcium carbonate obtained in Example 2;

[0043] Figure 8 This is a diagram showing the effect of using the sunburn protection agent prepared in Example 2 on apples;

[0044] Fig. 9 This is a scanning electron microscope photograph of calcium carbonate particles in the calcium carbonate slurry prepared in Example 3;

[0045] Fig.10 This is a scanning electron microscope photograph of the monodisperse calcium carbonate obtained in Example 3;

[0046] Fig.11 This is a diagram showing the effect of using the sunburn protection agent prepared in Example 3 on pears;

[0047] Fig.12 This is a scanning electron microscope photograph of calcium carbonate particles in the calcium carbonate slurry prepared in Example 4;

[0048] Fig.13 This is a scanning electron microscope photograph of the monodisperse calcium carbonate obtained in Example 4;

[0049] Fig.14 This is a scanning electron microscope photograph of the calcium carbonate prepared in Comparative Example 1;

[0050] Fig.15 This is a diagram showing the effect of using the sunburn protection agent prepared in Example 4 on pitaya;

[0051] Fig.16 It is a comparison diagram of the effect of calcium carbonate dispersed in water of the embodiment and the comparative example;

[0052] Fig.17 This is a diagram showing the effect of using the sunburn protection agent made of calcium carbonate in Comparative Examples 1 and 2 on citrus;

[0053] Fig.18 This is a scanning electron microscope photograph of the calcium carbonate prepared in Comparative Example 2;

[0054] Fig.19This is a diagram showing the effect of using the sunburn protection agent made of calcium carbonate in Comparative Example 3 on apples;

[0055] Fig. 20 This is a diagram showing the effect of using the sunburn protection agent made from calcium carbonate in Comparative Example 4 on pears. Specific implementation methods

[0057] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0058] In the following examples, the ethoxy-modified polytrisiloxane is a commercially available product purchased from GE Silicones USA, model Silwet, with an active ingredient content of more than 98%.

[0059] In the following examples, the polyvinyl acetate emulsion is a commercially available reagent, also known as polyvinyl acetate, CAS No.: 9003-20-7.

[0060] In the following embodiments, the propylene glycol is a commercially available product, and the product indicators meet the requirements of the national standard GB / T 13206-2022.

[0061] In the following embodiments, the enzyme is a commercially available agricultural enzyme, the main component of which is an agricultural biological agent, and it also contains polysaccharides, amino acids and other ingredients. It was purchased from Jining Alida Bioengineering Co., Ltd., model: MLQ-plant enzyme.

[0062] Example 1

[0063] The present embodiment provides a fruit sunburn protection agent, which is prepared from the following raw materials in the following weight ratio: 20 parts of monodisperse calcium carbonate filter cake, 0.5 parts of ethoxy-modified polytrisiloxane, 0.8 parts of polyvinyl acetate emulsion, 0.1 parts of glycerol, 0.8 parts of enzyme, and 38 parts of water.

[0064] The preparation method of the fruit sunburn protection agent described in this embodiment is as follows: according to the above raw materials and mass fractions, 20 parts of monodisperse calcium carbonate filter cake are placed in 28 parts of water, and stirred for 40 minutes with a high-speed disperser at a stirring line speed of 100m / min, and then 0.5 parts of ethoxy-modified polytrisiloxane, 0.8 parts of polyvinyl acetate emulsion, 0.1 parts of propylene glycol, 0.8 parts of enzyme and the remaining 10 parts of water are added according to the above formula, and stirring is continued at a stirring line speed of 120m / min for 15 minutes to obtain the sunburn protection agent described in this embodiment, and the solid content of calcium carbonate is about 20%.

[0065] In this embodiment, the monodisperse calcium carbonate filter cake used is prepared in the following steps:

[0066] S1. Prepare calcium carbonate pulp by calcination, digestion, carbonization and other processes. The calcination process is as follows: select limestone with a grain size of 0.2-0.5 mm and a content of harmful heavy metals such as cadmium, lead, and chromium less than 400 ppm as raw material, adopt a calcination temperature of 900°C, calcine for 2 hours, and obtain quicklime with ideal activity; the digestion process is as follows: digest the quicklime obtained by the above calcination with water at 90°C to obtain lime milk, and then remove impurities after aging for 24 hours to obtain refined raw pulp; the carbonization process is as follows: add water to the refined raw pulp obtained by digestion to adjust the solid content to 10%, and then carbonize, the carbonization starting temperature is 20°C, CO 2 The content is 33%, and the slurry is carbonized until the pH value reaches 7.5-8.5, and then the carbonization is terminated to obtain the calcium carbonate cooked slurry;

[0067] From the scanning electron microscope photos (see Figure 1 ) It can be observed that the calcium carbonate particles in the obtained cooked pulp are chain-like, and the average particle width is about 110nm;

[0068] S2. Add 0.5% aluminum chloride, 1.0% sodium silicate, 2.0% ethanol and 0.5% disodium ethylenediaminetetraacetate to the calcium carbonate slurry obtained in S1, and heat at 160°C for 4.0h to obtain a calcium carbonate suspension;

[0069] S3. The calcium carbonate suspension obtained in S2 is filtered and dehydrated to obtain a calcium carbonate filter cake. The moisture content of the filter cake is controlled between 35% and 40%, that is, monodisperse calcium carbonate. At this time, an appropriate amount of filter cake is taken and dried at 105°C, and then its composition, specific surface area, micromorphology and particle size are tested and analyzed. The composition and specific surface area tests are carried out according to the "Calcium Carbonate Analysis Method" (GB / T 19281-2014) standard, and the micromorphology and particle size tests are carried out according to the "Nano Calcium Carbonate" (GB / T 19590-2023) standard. The content of harmful impurities such as cadmium, lead, barium, mercury, and arsenic in the obtained monodisperse calcium carbonate is less than 0.0002%, and the total content of harmful impurities is less than 200ppm; the specific surface area is about 16.86m 2 / g; from the scanning electron microscope photo (see Figure 2 ) It can be clearly seen that the average particle size of the monodisperse calcium carbonate particles obtained is about 200nm, the particles are cubic, and the surface is flat and clean. The monodisperse calcium carbonate filter cake is dispersed in clean water to obtain a suspension with a solid content of 2%, and then the suspension effect is observed after standing for 2 hours. It can still be stably suspended (see Fig.16 ).

[0070] Application test: The fruit sunburn protection agent prepared in this embodiment is used for citrus sunburn protection planting, and the specific process is: in the early or middle stage of fruit expansion, from the end of June to the beginning of July each year, before the high temperature and strong sunshine environment of more than 30°C are about to arrive, the above-mentioned sunburn protection agent is diluted by 4 times (the solid content of calcium carbonate after dilution is about 5%) and sprayed on the surface of citrus fruit and the places where branches and leaves are easily exposed to the sun, and the growth status of the whole plant of citrus fruit trees is recorded by taking pictures after spraying, and then regularly observed once a month. When it encounters continuous rainfall for more than 5 days within less than 24h after spraying, and the total rainfall reaches 250mm and above, it is necessary to spray again after the rain. In the later stage of fruit expansion, it is necessary to spray again once, and when spraying again, the above-mentioned fruit sunburn protection agent is diluted by 6 times (the solid content of calcium carbonate after dilution is about 3%) and sprayed on the surface of citrus fruit and the places where branches and leaves are easily exposed to the sun.

[0071] like Figure 3 As shown in the figure, the fruit sunburn protection agent is evenly attached to the citrus fruits and leaves, forming a thin and uniform protective film; Figure 4 As shown in the figure, the surface temperature of the citrus fruit sprayed with water is 49.9°C, while after spraying the fruit sunburn protection agent prepared in this embodiment, the surface temperature of the citrus fruit is 39.7°C, and the fruit surface temperature is effectively reduced by about 26%.

[0072] The state of the pulp of the citrus fruits sprayed with the fruit sunburn protection agent of this embodiment and the control sprayed with water was observed after ripening (see Figure 5 ), the citrus pulp sprayed with water appears dry, while the citrus pulp sprayed with the fruit sunburn protection agent of this embodiment is sweet and juicy. Compared with spraying with water, spraying the sunburn protection agent of this embodiment can effectively prevent the occurrence of citrus sunburn, and the incidence of sunburn is reduced by 100%.

[0073] The price of the fruit sunburn protection agent in this embodiment has been calculated in detail, and the annual cost per mu of land is only about 780 yuan. The specific cost calculation is as follows: there are about 100 fruit trees in one mu of land, and the annual fruit production is about 3,600 catties. The amount of sunburn protection agent used is 35 kg / mu, and the unit price is about 10 yuan / kg. UAV spraying is used, and the machine rental fee (including labor costs) is about 40 yuan / mu / time. The cost of spraying one mu of land twice a year is (2*35*10+2*40) yuan, that is, 780 yuan / mu; the economic loss of not spraying the sunburn protection agent is calculated as follows: the rotten fruit rate is 20%, the citrus price is 1.5 yuan / catty, and the unit price is low due to the poor appearance of the fruit, which is 0.2 yuan / catty. The economic loss is estimated to be 1,656 yuan / mu (3,600*1.5-3,600*0.8*1.3). The fruit sunburn protection agent can recover the economic loss of 876 yuan per mu, improve the economic benefits, and has a broad market prospect.

[0074] Example 2

[0075] The present embodiment provides a monodisperse calcium carbonate fruit sunburn protection agent, which is prepared from the following raw materials in parts by weight: 1 part of monodisperse calcium carbonate filter cake, 0.05 parts of ethoxy-modified polytrisiloxane, 0.02 parts of polyvinyl acetate emulsion, 0.01 parts of glycerol, 0.01 parts of enzyme, and 30 parts of water.

[0076] The preparation method of the monodisperse calcium carbonate fruit sunburn protection agent described in this embodiment is as follows: according to the above raw materials and mass fractions, 1 part of monodisperse calcium carbonate filter cake is placed in 2 parts of water, and stirred for 40 minutes with a high-speed disperser at a stirring line speed of 80m / min, and then 0.05 parts of ethoxy-modified polytrisiloxane, 0.02 parts of polyvinyl acetate emulsion, 0.01 parts of propylene glycol, 0.01 parts of enzyme and the remaining 28 parts of water are added according to the above formula, and stirring is continued at a stirring line speed of 80m / min for 20 minutes to obtain the sunburn protection agent described in this embodiment, and the solid content of calcium carbonate is about 2%.

[0077] The preparation steps of the monodisperse calcium carbonate filter cake are different from those in Example 1 in that the digestion temperature in step S1 is 50°C, the aging time is 48h, the solid content of the refined raw pulp in the carbonization process is 12%, and the CO 2 The content is 40%, and the carbonization is completed when the pH reaches 7.5-8.0. After the carbonization is completed, the microscopic morphology of the calcium carbonate particles in the obtained cooked pulp is characterized. It can be observed that the calcium carbonate particles are nearly spherical and short rod-shaped, with an average particle size of about 149nm (see Figure 6 ); Step S2: During the grain surface reconstruction process, 1.0% zinc sulfate, 0.5% aluminum chloride and 2.0% polyvinyl alcohol were added to the dry basis of calcium carbonate and kept at 180°C for 3.0h.

[0078] The same test method as in Example 1 was used to test and analyze the composition, specific surface area, microscopic morphology and particle size of the monodisperse calcium carbonate filter cake obtained in this example. The contents of harmful impurities such as cadmium, lead, barium, mercury and arsenic in the monodisperse calcium carbonate obtained were all less than 0.0002%, and the total content of harmful impurities was less than 200 ppm; the specific surface area was about 14.27 m 2 / g; From the SEM photos (see Figure 7 ) It can be clearly seen that the average particle size of the monodisperse calcium carbonate particles obtained is about 260nm, the particles are cubic, and the surface is flat and clean. The monodisperse calcium carbonate filter cake is dispersed in clean water to obtain a suspension with a solid content of 2%, and then the suspension effect is observed after standing for 2 hours. It can still be stably suspended (see Fig.16 ).

[0079] When used for spraying apples: Before the apple fruit expansion period, the sunburn protection agent prepared in this embodiment is directly sprayed on the surface of the apple fruit, and the leaves and branches of the fruit trees do not need to be avoided during the spraying process. After spraying, the growth status of the whole apple tree is recorded by taking photos, and then regularly observed every week. During the ripening process of apples, it is necessary to spray 2 to 3 times. If there is continuous rainfall for more than 5 days and the total rainfall reaches 250 mm or more, it is necessary to spray once more after the rain.

[0080] The effect of using the sunburn protection agent of this embodiment on apples is shown in the figure below. Figure 8 After spraying, compared with bagging, spraying the anti-sunburn protective agent of this embodiment can effectively prevent the occurrence of apple sunburn, and the incidence of sunburn is reduced by 100%.

[0081] The price of the product of this embodiment is calculated in detail, and the cost per mu of land per year is only about 580 yuan. The specific calculation of the cost is as follows: there are about 100 fruit trees in one mu of land, and the annual fruit production is about 2500 kg. The amount of anti-sunburn protective agent is 250 kg / mu at a time, and the unit price of anti-sunburn protective agent is about 1 yuan / kg. The plant protection machine is used for spraying, and the machine rental fee (including labor cost) is about 40 yuan / mu. The cost of spraying twice a year on one mu of land is (2*250*1+2*40) yuan, that is, 580 yuan / mu; the cost of bagging is calculated as follows: one mu of land requires about 10,000 bags / mu, and the cost of manual bagging is about 0.24 yuan / piece, so the cost of manual bagging is 2,400 yuan / mu (10000*0.24). Spraying the anti-sunburn protective agent of this embodiment can save 1,820 yuan per mu compared to manual bagging, which greatly improves the economic benefit and has a broad market prospect.

[0082] Example 3

[0083] The present embodiment provides a monodisperse calcium carbonate fruit sunburn protection agent, which is prepared in the following weight ratios: 5 parts of monodisperse calcium carbonate filter cake, 0.2 parts of ethoxy-modified polytrisiloxane, 0.1 parts of polyvinyl acetate emulsion, 0.05 parts of glycerol, 0.05 parts of enzyme, and 55 parts of water.

[0084] The preparation method of the monodisperse calcium carbonate fruit sunburn protection agent described in this embodiment is as follows: according to the above raw materials and mass fractions, 5 parts of monodisperse calcium carbonate filter cake are placed in 10 parts of water, and stirred for 15 minutes with a high-speed disperser at a stirring line speed of 120m / min, and then 0.2 parts of ethoxy-modified polytrisiloxane, 0.1 parts of polyvinyl acetate emulsion, 0.05 parts of propylene glycol, 0.05 parts of enzyme and the remaining 45 parts of water are added according to the above formula, and stirring is continued at a stirring line speed of 90m / min for 30 minutes to obtain the sunburn protection agent described in this embodiment, and the solid content of calcium carbonate is about 5%.

[0085] The preparation steps of the monodisperse calcium carbonate filter cake are different from those in Example 1 in that the digestion temperature in step S1 is 80°C, the aging time is 30h, the solid content of the refined raw pulp during the carbonization process is 8%, the carbonization starting temperature is 30°C, and the CO 2 The content is 30%, and the carbonization is completed when the pH reaches 8.0-8.5. After the carbonization is completed, the microscopic morphology of the calcium carbonate particles in the obtained cooked pulp is characterized. It can be observed that the calcium carbonate particles are nearly spherical, and the average particle size is about 120nm (see Fig. 9 ); Step S2: during the grain surface reconstruction process, 1.5% sodium chloride, 1.0% aluminum chloride, 0.5% sodium silicate, 0.5% sodium dodecylbenzene sulfonate and 0.5% sodium dodecyl sulfate were added to the dry mass of calcium carbonate and then kept at 180°C for 4h.

[0086] The composition, specific surface area, microscopic morphology and particle size of the monodisperse calcium carbonate filter cake obtained in this embodiment were tested and analyzed by the same test method as in Example 1. The contents of harmful impurities such as cadmium, lead, barium, mercury and arsenic in the monodisperse calcium carbonate obtained were all less than 0.0002%, and the total content of harmful impurities was less than 200 ppm; the specific surface area was about 13.02 m 2 / g; From the SEM photos (see Fig.10 ) It can be clearly seen that the average particle size of the monodisperse calcium carbonate particles obtained is about 285nm, the particles are cubic, and the surface is flat and clean. The monodisperse calcium carbonate filter cake obtained is dispersed in clean water to obtain a suspension with a solid content of 2%, and then the suspension effect is observed after standing for 2 hours. It can still be stably suspended (see Fig.16 ).

[0087] When used for pear spraying: before the pear fruit is about to expand, dilute the monodisperse calcium carbonate fruit sunburn protection agent by 2 times (solid content of calcium carbonate is about 2.5%) and spray it on the surface of the pear fruit. After spraying, take photos to record the growth status of the whole pear tree, and observe it regularly once a week thereafter. Spray 1 to 2 times during the ripening process of the pear. If there is continuous rainfall for more than 5 days and the total rainfall reaches 250mm or more, it is necessary to spray once after the rain. Before spraying, make sure there will be no rainfall for 24 hours.

[0088] The effect of using the sunburn protection agent prepared in this embodiment on pears is shown in the figure below: Fig.11 The protective agent can be quickly spread and evenly attached to the fruit surface. Compared with bagging after spraying, spraying the anti-sunburn protective agent of this embodiment can effectively prevent the occurrence of pear sunburn, and the incidence of sunburn is reduced by 100%.

[0089] The price of the product of this embodiment has been calculated in detail, and the cost per mu of land per year is only about 780 yuan. The specific calculation of the cost is as follows: there are about 110 fruit trees in one mu of land, and the annual fruit production is about 2500 kg. The amount of anti-sunburn protective agent is 140 kg / mu at a time, and the unit price of anti-sunburn protective agent is about 2.5 yuan / kg. The plant protection machine is used for spraying, and the machine rental fee (including labor cost) is about 40 yuan / mu. The cost of spraying twice a year on one mu of land is 780 yuan / mu (2*140*2.5+2*40); the cost of bagging is calculated as follows: the cost of bagging is about 1.4 yuan / kg, and the cost of manual bagging is 3500 yuan / mu (2500*1.4). Spraying the anti-sunburn protective agent of this embodiment can save 2720 yuan per mu compared with manual bagging, which greatly improves the economic benefit and has a broad market prospect.

[0090] Example 4

[0091] The present embodiment provides a monodisperse calcium carbonate fruit sunburn protection agent, which is prepared from the following raw materials in parts by weight: 15 parts of monodisperse calcium carbonate filter cake, 0.2 parts of ethoxy-modified polytrisiloxane, 0.5 parts of polyvinyl acetate emulsion, 0.2 parts of glycerol, 0.5 parts of enzyme, and 45 parts of water.

[0092] The method for preparing the monodisperse calcium carbonate fruit sunburn protection agent described in this embodiment is as follows: according to the above raw materials and mass fractions, 15 parts of monodisperse calcium carbonate filter cake are placed in 20 parts of clean water, and stirred for 30 minutes with a high-speed disperser at a stirring line speed of 90m / min, and then 0.2 parts of ethoxy-modified polytrisiloxane, 0.5 parts of polyvinyl acetate emulsion, 0.2 parts of propylene glycol, 0.5 parts of enzyme and the remaining 25 parts of water are added according to the above formula, and the stirring is continued at a stirring line speed of 110m / min for 25 minutes to obtain the sunburn protection agent described in this embodiment, and the solid content of calcium carbonate is about 15%. Among them, the preparation steps of the monodisperse calcium carbonate filter cake are different from those in Example 1 in that the digestion temperature of step S1 is 70°C, the aging time is 40h, the solid content of the refined raw pulp in the carbonization process is 11%, the carbonization starting temperature is 25°C, and CO 2 The content is 35%, and the carbonization is completed when the pH reaches 7.5-8.0. After the carbonization is completed, the microscopic morphology of the calcium carbonate particles in the obtained cooked pulp is characterized. It can be observed that the calcium carbonate particles are chain-like with an average width of about 130nm (see Fig.12 ); Step S2: During the grain surface reconstruction process, 0.5% zinc sulfate, 1.4% polyethylene glycol, 0.6% ethanol, 0.5% hexadecyltrimethylammonium bromide and 2.5% polyvinylpyrrolidone were added to the calcium carbonate dry basis mass and kept at 200°C for 2h.

[0093] The same test method as in Example 1 was used to test and analyze the composition, specific surface area, microscopic morphology and particle size of the monodisperse calcium carbonate filter cake obtained in this example. The contents of harmful impurities such as cadmium, lead, barium, mercury and arsenic in the monodisperse calcium carbonate obtained were all less than 0.0002%, and the total content of harmful impurities was less than 200 ppm; the specific surface area was about 15.73 m 2 / g; From the SEM photos (see Fig.13 ) It can be clearly seen that the average particle size of the monodisperse calcium carbonate particles obtained is about 230nm, the particles are cubic, and the surface is flat and clean. The monodisperse calcium carbonate filter cake obtained is dispersed in clean water to obtain a suspension with a solid content of 2%, and then the suspension effect is observed after standing for 2 hours. It can still be stably suspended (see Fig.16 ).

[0094] When used for pitaya sunburn prevention: During the pitaya fruit expansion period, choose a dry, rainless day and use a conventional sprayer to dilute the anti-sunburn protectant 5 times (the solid content of calcium carbonate is about 3%) and spray it on the surface of the pitaya fruit. There is no need to avoid the branches of the fruit tree. After spraying, take photos to record the growth status of the whole pitaya tree, and observe it regularly once a week thereafter. If there is continuous rainfall for more than 5 days and the total rainfall reaches 250mm or more, it is necessary to spray again after the rain. If there is no rainfall before picking, no additional spraying is required.

[0095] The effect of using the sunburn protection agent prepared in this embodiment on pitaya is shown in the figure below: Fig.15 As shown, the anti-sunburn protective agent is evenly attached to the surface of the pitaya fruit to form a thin and uniform protective film. Compared with bagging after spraying, spraying the anti-sunburn protective agent of this embodiment can effectively prevent the occurrence of pitaya sunburn, and the incidence of sunburn is reduced by 100%.

[0096] The price of the product of this embodiment is calculated in detail, and the cost per mu of land per year is only about 350 yuan. The specific calculation of the cost is as follows: there are about 450 fruit trees in one mu of land, and the annual fruit production is about 2500 kg. The amount of anti-sunburn protective agent is 10 kg / mu at a time, and the unit price of anti-sunburn protective agent is about 7.5 yuan / kg. Artificial spraying is adopted, and the labor cost is about 100 yuan / mu·time. The cost of spraying twice a year on one mu of land is 350 yuan / mu (2*10*7.5+2*100); the cost of bagging is calculated as follows: the cost of bagging is about 0.3 yuan / kg, and the cost of manual bagging is 750 yuan / mu (0.3*2500). Spraying the anti-sunburn protective agent of this embodiment can save 400 yuan per mu compared with manual bagging, which improves economic benefits and has broad market prospects.

[0097] Example 5

[0098] The present embodiment provides a monodisperse calcium carbonate fruit sunburn protection agent, which is prepared from the following raw materials in parts by weight: 18 parts of monodisperse calcium carbonate filter cake, 0.2 parts of ethoxy-modified polytrisiloxane, 0.6 parts of polyvinyl acetate emulsion, 0.5 parts of glycerol, 0.6 parts of enzyme, and 166 parts of water.

[0099] The preparation method of the monodisperse calcium carbonate fruit sunburn protection agent described in this embodiment is as follows: according to the above raw materials and mass fractions, 18 parts of monodisperse calcium carbonate filter cakes are placed in 26 parts of water, and stirred for 35 minutes with a high-speed disperser at a stirring line speed of 85m / min, and then 0.2 parts of ethoxy-modified polytrisiloxane, 0.6 parts of polyvinyl acetate emulsion, 0.5 parts of glycerol, 0.6 parts of enzymes and the remaining 140 parts of water are added according to the above formula, and the stirring is continued at a stirring line speed of 90m / min for 25 minutes to obtain the sunburn protection agent described in this embodiment, and the solid content of calcium carbonate is about 6%. Among them, the preparation method of the monodisperse micro-nano calcium carbonate filter cake is the same as that of Example 3.

[0100] When used for sunburn prevention of kiwifruit: about 30 days after the flowers fall, choose a dry, rainless day, use a conventional sprayer to dilute the anti-sunburn protectant 3 times (the solid content of calcium carbonate is about 2%) and spray it on the surface of the kiwifruit fruit, without avoiding the leaves and branches. After spraying, take photos to record the growth status of the entire kiwifruit tree, and observe it regularly once a week thereafter. If there is continuous rainfall for more than 5 days and the total rainfall reaches 250mm or more, it is necessary to spray again after the rain. If there is no rainfall before picking, no additional spraying is required.

[0101] The kiwifruit sprayed with the anti-sunburn protective agent prepared in this example had almost no sunburn damage, and the fruit surface of the untreated natural fruit facing the sun was brown, and the fruit was shrunken. The anti-sunburn effect of the kiwifruit sprayed with the anti-sunburn protective agent in this example was much higher than that of the untreated one, and was equal to the effect of bagging.

[0102] The price of the product of this embodiment is calculated in detail, and the cost per mu of land per year is only about 440 yuan. The specific calculation of the cost is as follows: there are about 55 fruit trees in one mu of land, and the annual fruit production is about 2000 kg. The amount of anti-sunburn protective agent is 40 kg / mu at a time, and the unit price of anti-sunburn protective agent is about 3 yuan / kg. Artificial spraying is adopted, and the labor cost is about 100 yuan / mu·time. The cost of spraying twice a year on one mu of land is 440 yuan / mu (2*40*3+2*100); the cost of bagging is calculated as follows: the cost of bagging is about 0.06 yuan / piece, and the single fruit weighs 120g, so the cost of manual bagging is 1000 yuan / mu (0.06*2000 / 0.12). Spraying the anti-sunburn protective agent of this embodiment can save 560 yuan per mu compared with manual bagging, which improves economic benefits and has broad market prospects.

[0103] Example 6

[0104] The present embodiment provides a monodisperse calcium carbonate fruit sunburn protection agent, which is prepared from the following raw materials in parts by weight: 3 parts of monodisperse calcium carbonate filter cake, 0.02 parts of ethoxy-modified polytrisiloxane, 0.05 parts of polyvinyl acetate emulsion, 0.01 parts of glycerol, 0.01 parts of enzyme, and 43 parts of water.

[0105] The preparation method of the monodisperse calcium carbonate fruit sunburn protection agent described in this embodiment is as follows: according to the above raw materials and mass fractions, 3 parts of monodisperse calcium carbonate filter cakes are placed in 6 parts of water, and stirred for 40 minutes with a high-speed disperser at a stirring line speed of 80m / min, and then 0.02 parts of ethoxy-modified polytrisiloxane, 0.05 parts of polyvinyl acetate emulsion, 0.01 parts of glycerol, 0.01 parts of enzyme and the remaining 40 parts of water are added according to the above formula, and the stirring is continued at a stirring line speed of 80m / min for 30 minutes to obtain the sunburn protection agent described in this embodiment, and the solid content of calcium carbonate is about 4%. Wherein, the preparation method of the monodisperse calcium carbonate filter cake is the same as that of Example 2.

[0106] When used for honey pomelo planting: When the fruit diameter reaches 3-5cm, choose a dry, rainless day, use a conventional sprayer to dilute the anti-sunburn protectant 2 times (the solid content of calcium carbonate is about 2%) and spray it on the surface of the honey pomelo fruit, without avoiding the leaves and branches of the fruit tree. After spraying, take photos to record the growth status of the honey pomelo fruit tree, and observe it regularly once a week thereafter. If there is continuous rainfall for more than 5 days and the total rainfall reaches 250mm or more, it is necessary to spray again after the rain. If there is no rainfall before picking, no additional spraying is required.

[0107] The honey pomelo sprayed with the anti-sunburn protective agent prepared in this example had almost no sunburn damage, while the natural fruit sprayed with water had more dry water in the flesh near the fruit stem. The anti-sunburn effect of the honey pomelo sprayed with the anti-sunburn protective agent of this example was much higher than that of the control sprayed with water, and was equal to the effect of bagging.

[0108] The price of the product of this embodiment is calculated in detail, and the cost per mu of land per year is only about 320 yuan. The specific calculation of the cost is as follows: there are about 50 fruit trees in one mu of land, and the annual fruit production is about 3000 kg. The amount of anti-sunburn protective agent is 60 kg / mu at a time, and the unit price of anti-sunburn protective agent is about 2 yuan / kg. Artificial spraying is adopted, and the labor cost is about 100 yuan / mu·time. The cost of spraying twice a year on one mu of land is 440 yuan / mu (2*60*2+2*100); the cost of bagging is calculated as follows: the cost of bagging is about 0.4 yuan / piece, and the single fruit weighs 1 kg, so the cost of manual bagging is 1200 yuan / mu (0.4*3000 / 1). Spraying the anti-sunburn protective agent of this embodiment can save 760 yuan per mu compared with manual bagging, which improves economic benefits and has broad market prospects.

[0109] Comparative Example 1

[0110] Comparative Example 1 has the same formula as Example 1, except that no inorganic grain surface reconstructor is added in the preparation method of calcium carbonate. The microscopic morphology of the obtained product is shown in FIG. Fig.14 .

[0111] In Comparative Example 1, because no inorganic crystal surface reconstructor was added, the surface of the calcium carbonate crystals was rough, the dispersion between the particles was relatively poor, and the particles were connected to each other, resulting in reduced dispersion stability in water. Fig.16 As shown. And because the particles are hard and agglomerated, the film formed on the surface of citrus fruits is uneven (see Fig.17 ), which cannot achieve good visible light transmission, resulting in low fruit maturity, sour taste, and uneven coloring on the fruit surface.

[0112] Comparative Example 2

[0113] Comparative Example 2 has the same formula as Example 1, except that no organic crystal surface reconstruction agent is added in the preparation method of calcium carbonate. The microscopic morphology of the obtained product is shown in FIG. Fig.18 .

[0114] In Comparative Example 2, since no organic crystal surface reconstructor was added, the surface of the calcium carbonate crystals was clean, but the dispersion between the particles was still relatively poor, and connections were formed between the particles, resulting in reduced dispersion stability in water. Fig.16 As shown in the figure. And because the particles are hard and agglomerated, the film formed on the surface of citrus fruits is uneven (such as Fig.17 As shown in the figure, it is impossible to achieve good visible light transmission, resulting in low fruit maturity, sour taste and uneven coloring of the fruit surface.

[0115] Comparative Example 3

[0116] The formula of Comparative Example 3 is the same as that of Example 2, except that in the preparation method of calcium carbonate, pressure filtration is not performed to obtain a monodisperse calcium carbonate filter cake of a special form, but the slurry obtained after the surface of the grains is directly formulated according to the proportions described in Example 1.

[0117] In Comparative Example 3, because the soluble ions in the slurry were not removed by filtration, the harmful ions were sprayed on the apple surface, and the surface of the fruit had many spots and cracks after ripening. Fig.19 shown.

[0118] Comparative Example 4

[0119] Comparative Example 4 has the same formula as Example 3, except that the preparation method of the sunburn protection agent does not follow the two-step dispersion step, but directly adds 5 parts of monodisperse calcium carbonate filter cake to 55 parts of clean water, and stirs for 15 minutes with a high-speed disperser at a stirring line speed of 120m / min. After stirring evenly, 0.2 parts of ethoxy-modified polytrisiloxane, 0.1 parts of polyvinyl acetate emulsion, 0.05 parts of propylene glycol and 0.05 parts of enzyme are added according to the ingredient relationship, and stirring is continued at a stirring line speed of 100m / min for 15 minutes.

[0120] Comparative Example 5 has no high concentration stirring step, resulting in poor dispersion of calcium carbonate. When sprayed on the pear fruit surface, the slurry cannot form a good film on the fruit surface (see Fig. 20 ), there are local differences in light and dark, and most of them are accumulated in the fruit pedicle, resulting in more spots on the surface of the mature fruit and a high fruit drop rate.

[0121] The above is only a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and changes without departing from the creative concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A fruit sunburn protection agent, characterized in that: The raw material composition includes, by weight: 1 to 20 parts of monodisperse calcium carbonate filter cake, 0.01 to 0.9 parts of ethoxy-modified polytrisiloxane, 0.01 to 0.8 parts of polyvinyl acetate emulsion, 0.01 to 0.8 parts of glycerol, 0.01 to 0.8 parts of enzyme, and 10 to 180 parts of water; The water content of the monodisperse calcium carbonate filter cake is 35% to 40%, the average particle size of the calcium carbonate particles is between 200 and 400 nm, the particles with a particle size greater than 400 nm account for less than 5%, and the specific surface area is less than 17 m 2 / g; and the monodisperse calcium carbonate filter cake is stirred and dispersed in the aqueous solution without adding any chemical dispersant, and remains stably suspended.

2. A fruit sunburn protection agent according to claim 1, characterized in that: The raw material composition includes, by weight: 1 to 20 parts of monodisperse calcium carbonate filter cake, 0.01 to 0.5 parts of ethoxy-modified polytrisiloxane, 0.02 to 0.8 parts of polyvinyl acetate emulsion, 0.01 to 0.5 parts of glycerol, 0.01 to 0.8 parts of enzyme, and 30 to 166 parts of water.

3. A fruit sunburn protection agent according to claim 1, characterized in that: The method for preparing the monodisperse calcium carbonate filter cake comprises the following steps: S1. Prepare calcium carbonate pulp by processes including calcination, digestion and carbonization; S2. Adding an inorganic salt crystal surface reconstruction agent and an organic crystal surface reconstruction agent to the calcium carbonate slurry obtained in S1, and then keeping the temperature at 160 to 200° C. for 2.0 to 6.0 hours to obtain a calcium carbonate suspension; S3. The calcium carbonate suspension obtained in S2 is dehydrated by hydraulic filtration to obtain a calcium carbonate filter cake, wherein the water content of the filter cake is controlled between 35% and 40%, i.e., a monodisperse calcium carbonate filter cake.

4. A fruit sunburn protection agent according to claim 3, characterized in that: The calcination process is as follows: limestone with uniform grain size and harmful heavy metal content less than 400ppm is selected as raw material, and calcined to obtain quicklime, the activity of which is in the range of 250 to 300mL; The digestion process is as follows: the quicklime obtained by the calcination is digested in hot water at 50-90°C to obtain lime milk, which is then aged for 24-48 hours and filtered to remove impurities to obtain refined raw pulp; The carbonization process is as follows: add water to the refined raw pulp to adjust the solid content to 8% to 12%, and then carbonize it. The starting temperature of carbonization is 20 to 30°C, the CO2 content is 30% to 40%, and the pulp is carbonized until the pH value reaches 7.5 to 8.

5. Then the carbonization is terminated to obtain calcium carbonate cooked pulp.

5. The fruit sunburn protection agent according to claim 3, characterized in that: The inorganic crystal surface reconstruction agent is one or more of sodium silicate, sodium chloride, aluminum chloride, and zinc sulfate, and the dosage is 0.5-3% of the dry basis mass of calcium carbonate; the organic crystal surface reconstruction agent is one or more of ethanol, polyethylene glycol, polyvinyl pyrrolidone, polyvinyl alcohol, sodium dodecylbenzene sulfonate, hexadecyltrimethylammonium bromide, sodium dodecyl sulfate, and disodium ethylenediaminetetraacetate, and the dosage is 1%-5% of the dry basis mass of calcium carbonate; the monodisperse calcium carbonate filter cake is stirred and dispersed in an aqueous solution without adding any chemical dispersant to obtain a suspension, and when the solid content of the suspension is 2%-5%, it can be stably suspended for more than 2 hours.

6. The fruit sunburn protection agent according to claim 1, characterized in that: The enzyme is a commercially available agricultural enzyme.

7. The method for preparing the fruit sunburn protection agent according to any one of claims 1 to 6, characterized in that: The steps include: (1) According to the raw materials and their weight proportions, prepare 1 to 20 parts of monodisperse calcium carbonate filter cake, 0.01 to 0.9 parts of ethoxy-modified polytrisiloxane, 0.01 to 0.8 parts of polyvinyl acetate emulsion, 0.01 to 0.8 parts of glycerol, 0.01 to 0.8 parts of enzyme, and 10 to 180 parts of clean water; (2) placing the monodisperse calcium carbonate filter cake in a portion of water at a temperature of 5 to 30° C. and dispersing it in a high-speed disperser at a linear speed of 80 to 120 m / min for 15 to 40 min; (3) After the stirring in step (2) is completed, other raw materials and the remaining amount of water are added, and the mixture is dispersed in a high-speed disperser at a linear speed of 80 to 120 m / min for 15 to 30 min to obtain the fruit sunburn protection agent.

8. The method for preparing the fruit sunburn protection agent according to claim 7, characterized in that: In step (2), the amount of water used to disperse the monodisperse calcium carbonate filter cake is 1 to 2 times the weight of the monodisperse calcium carbonate filter cake.

9. The application method of the fruit sunburn protection agent according to any one of claims 1 to 6, characterized in that: When used for fruit sunburn prevention planting, the fruit sunburn prevention protective agent is diluted with water to a solid content of calcium carbonate of 2% to 6% and then sprayed.

10. The application method of the fruit sunburn protection agent according to claim 9, characterized in that: In rainless and dry weather, the fruit sunburn protection agent is diluted and sprayed on the surface of the fruit without avoiding branches and leaves. It is necessary to spray 1 to 4 times during the fruit ripening process. If it rains for more than 5 days within less than 24 hours after spraying, and the total rainfall reaches 250 mm or more, it is necessary to spray again after the rain.

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