Water-soluble fertilizer based on pollen polysaccharide and preparation method thereof

Abstract

The invention relates to the technical field of fertilizers, and provides a pollen polysaccharide-based water-soluble fertilizer and a preparation method thereof. The water-soluble fertilizer is prepared from the following components in percentage by mass: 14 to 40 percent of chemical fertilizer, 6 to 10 percent of vegetable protein-based pollen polysaccharide temperature-sensitive hydrogel, 0.1 to 0.5 percent of chlorogenic acid, 1 to 5 percent of humic acid and the balance of water. According to the invention, the pollen polysaccharide is wrapped by the vegetable protein to prepare the temperature-sensitive hydrogel, and the pollen polysaccharide is isolated from inorganic salt in the water-soluble fertilizer; then a stronger hydrogen bond network and electrostatic interaction are formed by carboxyl and multiple hydroxyls in chlorogenic acid molecules, pollen polysaccharide and vegetable protein, so that the stability and the uniform dispersity of a hydrogel system are remarkably improved. The combination of the two improves the flowability of the fertilizer, avoids layering, improves the system consistency during spraying or application, and improves the fertilizer efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of fertilizers, and particularly relates to a water-soluble fertilizer based on pollen polysaccharide and a preparation method thereof. Background Art

[0002] With the increasing demand for efficient and environmentally friendly fertilizers in modern agriculture, water-soluble fertilizers have become a research hotspot due to their advantages such as rapid absorption and precise fertilization. After dilution, water-soluble fertilizers can be used for irrigation fertilization, foliar spraying, soilless cultivation, seed soaking and root dipping, etc., which can improve the utilization rate of fertilizers and reduce resource waste and environmental pollution.

[0003] Existing water-soluble fertilizers still have some technical bottlenecks, such as uneven nutrient release, single functionality, insufficient solubility, etc. As a natural plant extract, pollen polysaccharide has excellent biological activity, can promote plant growth, enhance stress resistance, and improve the soil microenvironment. Therefore, the compounding of pollen polysaccharide and water-soluble fertilizer can solve the problem of single functionality of water-soluble fertilizer.

[0004] However, due to the complex molecular structure of pollen polysaccharide, when directly compounded with water-soluble fertilizer, there will be an incompatibility problem between the inorganic salts in the water-soluble fertilizer and pollen polysaccharide, resulting in precipitation or stratification after mixing, which affects the stability and application effect of the fertilizer. Summary of the Invention

[0005] In view of this, in order to overcome the compatibility obstacle between pollen polysaccharide and traditional water-soluble fertilizers, the present invention proposes a water-soluble fertilizer based on pollen polysaccharide and a preparation method thereof.

[0006] The technical solution of the present invention is realized as follows: On the one hand, the present invention provides a water-soluble fertilizer based on pollen polysaccharide. Calculated according to 100% by mass percentage, the water-soluble fertilizer includes 14% - 40% of chemical fertilizer, 6% - 10% of plant protein-based pollen polysaccharide thermosensitive hydrogel, 0.1% - 0.5% of chlorogenic acid, 1% - 5% of humic acid, and the balance is water.

[0007] The present invention wraps pollen polysaccharide with plant protein to form a thermosensitive hydrogel, isolating pollen polysaccharide from the inorganic salts in the water-soluble fertilizer, effectively solving the incompatibility problem. The carboxyl group (-COOH) and multiple hydroxyl groups (-OH) in chlorogenic acid form stronger hydrogen bond networks and electrostatic interactions with pollen polysaccharide and plant protein, significantly enhancing the stability and uniform dispersion of the hydrogel system. The combination of the two can improve the fluidity of the fertilizer, avoid stratification, and enhance the system consistency during spraying or application. In addition, the thermosensitive release mechanism of the thermosensitive hydrogel can improve the nutrient utilization efficiency of the fertilizer during the peak crop metabolism period such as high temperature and strong light, realizing release on demand.

[0008] On the basis of the above technical solutions, preferably, the plant protein-based pollen polysaccharide thermosensitive hydrogel is conjugated with gallic acid or phytic acid.

[0009] In the present invention, conjugating gallic acid or phytic acid on the plant protein-based pollen polysaccharide thermosensitive hydrogel can improve the film-forming property of the water-soluble fertilizer. After being sprayed on the plant leaf surface, it has a certain ability to resist rain erosion.

[0010] On the basis of the above technical solutions, preferably, the preparation method of the plant protein-based pollen polysaccharide thermosensitive hydrogel includes the following steps: S1. Add plant protein into water, adjust the pH to 7 - 8, and stir until the protein is dispersed and dissolved to obtain a protein solution; S2. Add pollen polysaccharide into the protein solution, continue to stir to make it evenly dispersed, then add gallic acid or phytic acid, raise the temperature to 50 - 60 °C, and react for 1 - 2 h; S3. After the reaction is completed, cool the reaction solution to 20 - 30 °C, slowly add a β-glycerophosphate solution (aqueous solution), stir evenly and place it in an environment at 4 °C to obtain a plant protein-embedded pollen polysaccharide hydrogel.

[0011] On the basis of the above technical solutions, preferably, add sorbitol to the protein solution, stir and dissolve it fully, and then add pollen polysaccharide.

[0012] Adding sorbitol can increase the stability of the water-soluble fertilizer during long-term storage. The hydroxyl groups of sorbitol can form a large number of hydrogen bonds and weak van der Waals forces with the amino groups, hydroxyl groups and other groups of protein and polysaccharide molecules, enhancing the intermolecular interaction force, making the gel network more dense and stable, and not easily disintegrating especially under high-temperature storage or external disturbance.

[0013] On the basis of the above technical solutions, preferably, the dosage of sorbitol is 10% - 15% of the mass of the protein solution.

[0014] On the basis of the above technical solutions, preferably, in step S1, the mass ratio of the plant protein to water is 1:10 - 20.

[0015] On the basis of the above technical solutions, preferably, in step S2, the mass ratio of the plant protein to pollen polysaccharide to gallic acid is 10:2 - 3:0.1 - 0.3; the mass ratio of the plant protein to pollen polysaccharide to phytic acid is 10:2 - 3:0.4 - 0.6.

[0016] On the basis of the above technical solutions, preferably, in step S3, the mass concentration of the β-glycerophosphate solution is 8% - 12%, and the dosage is 10% - 15% of the volume of the reaction solution.

[0017] On the basis of the above technical solutions, preferably, the chemical fertilizer is one or more of nitrogen fertilizer, potassium fertilizer and phosphate fertilizer; the plant protein is selected as soybean protein.

[0018] On the other hand, the present invention also provides a preparation method of a water-soluble fertilizer based on pollen polysaccharide, comprising the following steps: Add the chemical fertilizer into water and stir until dissolved, then add humic acid, stir evenly and then add the plant protein-based pollen polysaccharide thermosensitive hydrogel, shear at a high speed of 10000 rpm for 5-10 min until the gel form of microparticles (D50≤10 μm), then add the chlorogenic acid alcohol solution and make up the water, stir evenly, and adjust the pH value to 6.5-7.5.

[0019] The water-soluble fertilizer based on pollen polysaccharide and its preparation method of the present invention have the following beneficial effects compared with the prior art: The present invention wraps pollen polysaccharide with plant protein to make a thermosensitive hydrogel, isolating the pollen polysaccharide from the inorganic salts in the water-soluble fertilizer; the carboxyl group and multiple hydroxyl groups in chlorogenic acid form stronger hydrogen bond networks and electrostatic interactions with pollen polysaccharide and plant protein, significantly improving the stability and uniform dispersion of the hydrogel system. The combination of the two can improve the fluidity of the fertilizer, avoid stratification, and enhance the system consistency during spraying or application. In addition, the thermosensitive release mechanism of the thermosensitive hydrogel can improve the nutrient utilization efficiency of the fertilizer during the vigorous crop metabolism period such as high temperature and strong light, realizing release on demand.

[0020] Coupling gallic acid or phytic acid on the plant protein-based pollen polysaccharide thermosensitive hydrogel of the present invention can improve the film-forming property of the water-soluble fertilizer, and has a certain ability to resist rain erosion after being sprayed on the plant leaf surface.

[0021] Adding sorbitol can increase the stability of the water-soluble fertilizer during long-term storage. The hydroxyl groups of sorbitol can form a large number of hydrogen bonds and weak van der Waals forces with the amino groups, hydroxyl groups and other groups of protein and polysaccharide molecules, enhancing the intermolecular interaction force and making the gel network more dense and stable, especially not easy to disintegrate under high-temperature storage or external disturbance. Specific embodiments

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0023] The chlorogenic acid (purity 98%) used in the present invention is purchased from Shanghai Yuanye Bio-Technology Co., Ltd.

[0024] The pollen polysaccharide used in the present invention is a self-made product, and the extraction method is as follows: 1. Pretreatment: Take dry rape pollen, crush it to 100 meshes, then wash it with anhydrous ethanol to remove surface impurities and grease; then filter and air-dry. Soak the pollen powder in pure water at a ratio of 1:10 (m / v) to make the pollen absorb water and swell. 2. Enzymolysis: Add 2% cellulase, 1.5% pectinase and 1% xylanase based on the mass of the pollen powder, adjust the pH to 5, and carry out enzymolysis at 50 °C for 8 h. After completion, heat in a water bath at 95 °C for 10 min to inactivate the enzyme. 3. Separation of crude polysaccharide: After enzymolysis, cool down to room temperature, centrifuge to collect the supernatant, and then concentrate it under reduced pressure to 1 / 2. 4. Purification of crude polysaccharide: Add ethanol with a volume fraction of 80% to the concentrated enzymolysis solution at a volume ratio of 1:3 (enzymolysis solution: ethanol), mix well and let it stand overnight at 4 °C. Centrifuge to collect the precipitate, and wash it successively with a small amount of 95% ethanol and ether. Then freeze-dry the polysaccharide solution to obtain rape pollen polysaccharide.

[0025] Example 1 For the water-soluble fertilizer based on pollen polysaccharide of the present invention, calculated by 100% of mass percentage, the water-soluble fertilizer includes 21% of chemical fertilizer (the mass ratio of urea to potassium dihydrogen phosphate is 2:1), 9% of plant protein-based pollen polysaccharide thermosensitive hydrogel, 0.3% of chlorogenic acid, 3% of humic acid, and the balance is water.

[0026] The preparation method of the plant protein-based pollen polysaccharide thermosensitive hydrogel includes the following steps: S1, Add 10 g of soy protein to 160 g of water, adjust the pH to 7, and stir until the protein is dispersed and dissolved to obtain a protein solution; S2, Add 2.5 g of pollen polysaccharide to the protein solution, continue to stir to make it evenly dispersed, heat up to 55 °C, and react for 1.5 h; S3, After the reaction is completed, cool the reaction solution to 25 °C, slowly add an aqueous solution of β-glycerophosphate with a mass concentration of 10% and a volume of 14% of the reaction solution, stir evenly and place it in an environment at 4 °C to obtain a plant protein-embedded pollen polysaccharide hydrogel.

[0027] The preparation method of the above water-soluble fertilizer includes the following steps: First, add the chemical fertilizer to water and stir until dissolved, then add humic acid, stir evenly, add the plant protein-based pollen polysaccharide thermosensitive hydrogel, shear at 10000 rpm for 10 min to the form of microparticle gel, then add chlorogenic acid and make up the water, stir evenly, and adjust the pH value to 6.5.

[0028] Example 2 Example 2 adds the following content on the basis of Example 1: The plant protein-based pollen polysaccharide thermosensitive hydrogel is conjugated with gallic acid, and the preparation method includes the following steps: S1 is the same as that in Example 1.

[0029] S2. Add 2.5 g of pollen polysaccharide to the protein solution, continue stirring to make it evenly dispersed, then add 0.2 g of gallic acid, raise the temperature to 55 °C, and react for 1.5 h.

[0030] S3 is the same as Example 1.

[0031] Example 3 Example 3 adds the following content on the basis of Example 2: Preparation method of plant protein-based pollen polysaccharide thermosensitive hydrogel conjugated with gallic acid, which includes the following steps: S1 is the same as Example 1.

[0032] S2. Add sorbitol accounting for 13% of the mass of the protein solution to the protein solution. After fully stirring and dissolving, add 2.5 g of pollen polysaccharide, continue stirring to make it evenly dispersed, then add 0.2 g of gallic acid, raise the temperature to 55 °C, and react for 1.5 h.

[0033] S3 is the same as Example 1.

[0034] Example 4 For the water-soluble fertilizer based on pollen polysaccharide in this example, calculated by mass percentage of 100%, the water-soluble fertilizer includes 14% of chemical fertilizer (the mass ratio of urea to potassium dihydrogen phosphate is 2:1), 7% of plant protein-based pollen polysaccharide thermosensitive hydrogel, 0.1% of chlorogenic acid, 2% of humic acid, and the balance is water.

[0035] Preparation method of plant protein-based pollen polysaccharide thermosensitive hydrogel conjugated with gallic acid or phytic acid, which includes the following steps: S1. Add 10 g of soy protein to 100 g of water, adjust the pH to 7, and stir until the protein is dispersed and dissolved to obtain a protein solution; S2. Add sorbitol accounting for 10% of the mass of the protein solution to the protein solution. After fully stirring and dissolving, add 2 g of pollen polysaccharide, continue stirring to make it evenly dispersed, then add 0.4 g of phytic acid, raise the temperature to 50 °C, and react for 1 h; S3. After the reaction, cool the reaction solution to 25 °C, slowly add a β-glycerophosphate sodium solution with a mass concentration of 8% and a volume of 10% of the reaction solution, stir evenly, and place it in an environment of 4 °C to obtain a plant protein-embedded pollen polysaccharide hydrogel.

[0036] Preparation method of the water-soluble fertilizer based on pollen polysaccharide, which includes the following steps: Add the chemical fertilizer to water and stir until dissolved, then add humic acid, stir evenly, add the plant protein-based pollen polysaccharide thermosensitive hydrogel, shear at a high speed of 10,000 rpm for 5 min to the microparticle gel form, then add chlorogenic acid and make up the water, stir evenly, and adjust the pH value to 6.5.

[0037] Example 5 The water-soluble fertilizer based on pollen polysaccharide, calculated according to 100% by mass percentage, comprises 27% of chemical fertilizer (the mass ratio of urea to potassium dihydrogen phosphate is 2:1), 8% of plant protein-based pollen polysaccharide thermosensitive hydrogel, 0.4% of chlorogenic acid, 5% of humic acid, and the balance is water.

[0038] The plant protein-based pollen polysaccharide thermosensitive hydrogel is coupled with gallic acid or phytic acid, and the preparation method comprises the following steps: S1. Add 10 g of soy protein into 180 g of water, adjust the pH to 8, and stir until the protein is dispersed and dissolved to obtain a protein solution. S2. Add 14% of sorbitol based on the mass of the protein solution into the protein solution, fully stir and dissolve it, then add 2.8 g of pollen polysaccharide, continue to stir to make it evenly dispersed, and then add 0.1 g of gallic acid, heat up to 60 °C, and react for 1.5 h. S3. After the reaction is completed, cool the reaction solution to 30 °C, slowly add 13% of the reaction solution volume of a 11% sodium β-glycerophosphate solution, stir evenly, and place it in an environment of 4 °C to obtain a plant protein-embedded pollen polysaccharide hydrogel.

[0039] The preparation method of the water-soluble fertilizer based on pollen polysaccharide comprises the following steps: Add the chemical fertilizer into water and stir until it is dissolved, then add humic acid, stir evenly, add the plant protein-based pollen polysaccharide thermosensitive hydrogel, perform high-speed shearing at 10000 rpm for 8 min until it forms a microparticle gel form, then add chlorogenic acid and make up the water, stir evenly, and adjust the pH value to 7.

[0040] Example 6 The water-soluble fertilizer based on pollen polysaccharide, calculated according to 100% by mass percentage, comprises 40% of chemical fertilizer (the mass ratio of urea to potassium dihydrogen phosphate is 2:1), 8% of plant protein-based pollen polysaccharide thermosensitive hydrogel, 0.5% of chlorogenic acid, 4% of humic acid, and the balance is water.

[0041] The plant protein-based pollen polysaccharide thermosensitive hydrogel is coupled with gallic acid or phytic acid, and the preparation method comprises the following steps: S1. Add 10 g of soy protein into 200 g of water, adjust the pH to 8, and stir until the protein is dispersed and dissolved to obtain a protein solution. S2. Add 15% of sorbitol based on the mass of the protein solution into the protein solution, fully stir and dissolve it, then add 3 g of pollen polysaccharide, continue to stir to make it evenly dispersed, and then add 0.3 g of gallic acid, heat up to 60 °C, and react for 2 h. S3, after the reaction is completed, the reaction solution is cooled to 30°C, and a 12% sodium β-glycerophosphate solution with a mass concentration of 15% of the reaction solution is slowly added, and the mixture is stirred evenly and placed at 4°C to obtain a plant protein-encapsulated pollen polysaccharide hydrogel.

[0042] The preparation method of the water-soluble fertilizer based on pollen polysaccharide comprises the following steps: Add the fertilizer into the water and stir until dissolved, then add humic acid, stir evenly and add the plant protein-based pollen polysaccharide thermosensitive hydrogel, high-speed shear at 10,000 rpm for 10 minutes until it becomes a micro-gel form, then add chlorogenic acid and add water, stir evenly, and adjust the pH value to 7.5.

[0043] Example 7 The water-soluble fertilizer based on pollen polysaccharides in this embodiment includes 16% chemical fertilizer (the mass ratio of urea to potassium dihydrogen phosphate is 2:1), 6% plant protein-based pollen polysaccharide thermosensitive hydrogel, 0.2% chlorogenic acid, 1% humic acid, and the balance is water, calculated based on the mass percentage of 100%.

[0044] The plant protein-based pollen polysaccharide thermosensitive hydrogel is coupled with gallic acid or phytic acid, and the preparation method comprises the following steps: S1, adding 10 g of soy protein to 130 g of water, adjusting the pH to 8, and stirring until the protein is dispersed and dissolved to obtain a protein solution; S2, add sorbitol (11% of the mass of the protein solution) to the protein solution, stir thoroughly to dissolve, then add 2.2g of pollen polysaccharide, continue stirring to make it evenly dispersed, then add 0.6g of phytic acid, heat to 60°C, and react for 2h; S3, after the reaction is completed, the reaction solution is cooled to 30°C, and a 9% sodium β-glycerophosphate solution with a mass concentration of 11% of the reaction solution is slowly added, and the mixture is stirred evenly and placed at 4°C to obtain a plant protein-encapsulated pollen polysaccharide hydrogel.

[0045] The preparation method of the water-soluble fertilizer based on pollen polysaccharide comprises the following steps: Add the fertilizer into the water and stir until dissolved, then add humic acid, stir evenly and add the plant protein-based pollen polysaccharide thermosensitive hydrogel, high-speed shear at 10,000 rpm for 10 minutes until it becomes a micro-gel form, then add chlorogenic acid and add water, stir evenly, and adjust the pH value to 7.5.

[0046] Comparative Example 1 Compared with Example 1, in Comparative Example 1, pollen polysaccharide is not prepared into a plant protein-based pollen polysaccharide thermosensitive hydrogel state, but is directly added.

[0047] Comparative Example 2 Compared with Example 1, Comparative Example 2 did not add chlorogenic acid, and the rest of the contents were the same.

[0048] Comparative Example 3 Compared with Example 1, the addition amount of the plant protein-based pollen polysaccharide thermosensitive hydrogel in Comparative Example 3 is higher than the specified range, specifically 20% of the total weight of the water-soluble fertilizer, and the rest is the same.

[0049] Comparative Example 4 Compared with Example 1, the addition amount of chlorogenic acid in Comparative Example 4 is higher than the specified range, specifically 1.5% of the total weight of the water-soluble fertilizer, and the rest is the same.

[0050] Comparative Example 5 Compared with Example 2, the dosage of gallic acid in Comparative Example 5 is higher than the specified range, specifically 1 g, and the rest is the same.

[0051] Comparative Example 6 Compared with Example 3, the dosage of sorbitol in Comparative Example 6 is higher than the specified range, specifically 15% of the mass of the protein solution added with sorbitol, and the rest is the same.

[0052] Stability test: Take 1 L of the finished water-soluble fertilizer prepared in the examples and comparative examples, pour it into a volumetric flask, and place it in an incubator to test the stability during storage. The test conditions are 25°C at room temperature for 90 d and 45°C at high temperature for 14 d. The results are shown in Table 1.

[0053]

[0054] In Example 2, due to the coupling of gallic acid, the multifunctional effects of gallic acid or phytic acid can improve the thermal stability of the gel system, so that even when stored at a relatively high temperature such as 45°C for 7 - 14 d, it is not easy to precipitate and layer, and the overall fertilizer efficiency and use performance are guaranteed. In Example 3, due to the addition of sorbitol, sorbitol can interact with protein and polysaccharide molecules, making the gel network more dense and stable, and it is not easy to disintegrate especially under high-temperature storage or external disturbance.

[0055] In Comparative Example 1, the pollen polysaccharide was prone to adverse reactions (such as crystallization and flocculation) with inorganic salts, resulting in a significant decrease in dispersibility and system stability. It was easy to precipitate and delaminate during storage, especially more obvious at high temperatures. In Comparative Example 2, the intermolecular interactions brought by chlorogenic acid were lost, and the ability to strengthen the stable colloidal network was insufficient, leading to a decrease in its thermal stability and particle dispersibility, and easy precipitation. In Comparative Example 3, due to the too high proportion of thermosensitive hydrogel, the system was viscous, and the particles were prone to aggregation and sedimentation, especially with worse stability at high temperatures. In Comparative Example 4, excessive chlorogenic acid complexed with proteins and polysaccharides, which would lead to chaos in the colloidal system, possibly resulting in insoluble precipitation or colloidal rupture, and easy delamination. In Comparative Example 5, excessive gallic acid would lead to local complexation precipitation in the system, particle aggregation, and a decrease in dispersibility and transparency, especially with significant precipitation at high temperatures. In Comparative Example 6, excessive sorbitol led to a decrease in the water content of the colloid, an overly dense network, and even dehydration and hardening. The colloid was easy to agglomerate and precipitate during storage at normal and high temperatures.

[0056] Rainwater erosion resistance experiment: 1 L of the water-soluble fertilizers of the above-mentioned examples and comparative examples were respectively prepared to test their erosion resistance effects. The experimental method was as follows: After diluting the water-soluble fertilizers of the examples and comparative examples by 1000 times with water, foliar fertilizers were prepared, and tomato red pigment was added as an indicator according to a ratio of 1:100000 (mass ratio), and sprayed on the leaves of three plants, namely corn, kidney beans, and rice. 5 leaves were randomly selected from each group; the spraying was carried out until the leaves were completely wet and the foliar fertilizer began to drip, and the spraying amount (mL) was recorded. After the leaves dried naturally, rain was simulated, and tap water was sprayed on the leaves. The spraying amount was 5 times the spraying amount of the foliar fertilizer; after the leaves dried, the second spraying was carried out, and the spraying amount was the same as the first spraying amount. After the two sprayings were completed, 5 cm in the middle of each leaf was photographed, and software was used to calculate the staining ratio (%), and statistical analysis was carried out on the staining ratio through statistical software. The results are shown in the following table.

[0057]

[0058] It can be seen from the staining ratios in Table 2 that: compared with Example 1, after the gel was coupled with gallic acid in Example 2, the film-forming property was enhanced, and thus the rainwater erosion resistance ability was also improved. Sorbitol mainly enhanced the high-temperature and long-term storage stability of the fertilizer. Therefore, there was no significant difference in the rainwater erosion resistance ability between Example 3 and Example 2.

[0059] In comparative example 1, the unembedded pollen polysaccharide is directly exposed, with poor film-forming property, easy to lose in rain, and the residual amount is significantly reduced. In comparative example 2, chlorogenic acid is not added, the colloidal membrane network structure is weak, and the scouring resistance is reduced. The film-forming property of comparative example 3 is slightly higher than that of Example 1. The extremely high chlorogenic acid content in comparative example 4 leads to brittle film-forming property or uneven membrane structure, resulting in reduced scouring resistance. In comparative example 5, the excess gallic acid may inhibit the film-forming property, the membrane structure is too hard or mixed with precipitation, and the residual rate is reduced. In comparative example 6, the increase in the amount of sorbitol is not significantly related to the film-forming property, and there is no significant difference from Example 3.

[0060] Potted yield increase experiment: The water-soluble fertilizer of the embodiment and the comparative example was diluted 1000 times with water to make foliar fertilizer. Cucumber was used as the experimental material, and 10 repetitions were set for each embodiment or comparative example, with 1 cucumber plant in each repetition. The potted soil of the embodiment and the comparative example was consistent, and the cucumber was sown in mid-April, and fertilization and watering management were performed according to conventional operations during the growth period. During the growth process, foliar spraying treatment was carried out 4 times in total during the leaf growth period, flowering period, fruit setting period and fruit picking mid-term. Each spraying was performed to form uniform mist droplets on the surface of the plant leaves, flowers and fruits but without dripping. During the growth process, natural rain was simulated on the 3rd day after the 2nd to 4th foliar spraying, and the simulation conditions were the same as the above-mentioned rainwater erosion resistance experiment. After the fruit was harvested, the number of melons per cucumber plant, as well as the length, diameter and weight of a single melon were counted respectively. Relevant experimental data are shown in Table 3.

[0061]

[0062] As shown in Table 3, the number of melons per plant, the weight of a single melon, the length of a single melon, and the diameter of the melon in the embodiment are all higher than those in the comparative example, among which the spraying effect of embodiment 3 is the best, followed by embodiment 2. This is because the gallic acid coupling in embodiment 2 enhances the ability of the leaf film layer to resist rain erosion, and the fertilizer absorption time is prolonged, so the effect is better than that in embodiment 1. In embodiment 3, sorbitol stabilizes the gel network, and the active ingredients do not decay after storage. After multiple sprayings, the system stability is higher, and the number of melons and the weight of melons are further improved; in addition, sorbitol improves the colloid dispersibility, and the trace elements are evenly distributed on the leaf surface, which promotes cell division and expansion, thereby increasing the melon diameter.

[0063] In Comparative Example 1, due to the lack of polysaccharide encapsulation, the effective ingredients of the fertilizer (pollen polysaccharide) were directly exposed to rainwater erosion and soil environment, and lost a lot of biostimulation effect, resulting in fewer, smaller, and lighter melons. In addition, the unencapsulated pollen polysaccharide reacted with inorganic salts in the fertilizer and became inactive, and the fertilizer efficiency was seriously reduced.

[0064] In Comparative Example 2, due to the lack of chlorogenic acid, the colloidal network is loose, and the fertilizer film layer is prone to rupture after simulating rain, resulting in a shortened retention time of fertilizer efficiency. However, it is slightly better than the unembedded system in Comparative Example 1. Since Comparative Example 2 still has the basic structure of the thermosensitive hydrogel, the water and fertilizer retention ability is partially retained, and the single melon weight is increased compared with that in Comparative Example 1.

[0065] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A water-soluble fertilizer based on pollen polysaccharide, characterized in that: Calculated according to 100% by mass percentage, the water-soluble fertilizer comprises 14% - 40% of chemical fertilizer, 6% - 10% of plant protein-based pollen polysaccharide thermosensitive hydrogel, 0.1% - 0.5% of chlorogenic acid, 1% - 5% of humic acid, and the balance is water.

2. The water-soluble fertilizer based on pollen polysaccharide according to claim 1, wherein: The plant protein-based pollen polysaccharide thermosensitive hydrogel is conjugated with gallic acid or phytic acid.

3. The water-soluble fertilizer based on pollen polysaccharide according to claim 2, wherein: The preparation method of the plant protein-based pollen polysaccharide thermosensitive hydrogel comprises the following steps: S1, adding plant protein into water, adjusting the pH to 7 - 8, and stirring until the protein is dispersed and dissolved to obtain a protein solution; S2, adding pollen polysaccharide into the protein solution, continuously stirring to make it evenly dispersed, then adding gallic acid or phytic acid, heating to 50 - 60 °C, and reacting for 1 - 2 h; S3, after the reaction is completed, cooling the reaction solution to 20 - 30 °C, slowly adding a β-glycerophosphate solution, stirring evenly, and placing it in an environment at 4 °C to obtain a plant protein-embedded pollen polysaccharide hydrogel.

4. The water-soluble fertilizer based on pollen polysaccharide according to claim 3, characterized in that: Add sorbitol to the protein solution, stir well until dissolved, and then add pollen polysaccharide.

5. The water-soluble fertilizer based on pollen polysaccharide according to claim 4, characterized in that: The dosage of sorbitol is 10% - 15% of the mass of the protein solution.

6. The water-soluble fertilizer based on pollen polysaccharide according to claim 3, characterized in that: In step S1, the mass ratio of the plant protein to water is 1:10 - 20.

7. The water-soluble fertilizer based on pollen polysaccharide according to claim 3, characterized in that: In step S2, the mass ratio of the plant protein to pollen polysaccharide to gallic acid is 10:2 - 3:0.1 - 0.3; The mass ratio of plant protein to pollen polysaccharide to phytic acid is 10:2 - 3:0.4 - 0.

6.

8. The water-soluble fertilizer based on pollen polysaccharide according to claim 3, wherein: In step S3, the mass concentration of the β-glycerophosphate solution is 8% - 12%, and the dosage is 10% - 15% of the volume of the reaction solution.

9. A water-soluble fertilizer based on pollen polysaccharide according to claim 1, characterized in that: The chemical fertilizer is one or more of nitrogen fertilizer, potassium fertilizer, and phosphate fertilizer; the plant protein selects soybean protein.

10. The preparation method of a water-soluble fertilizer based on pollen polysaccharide according to any one of claims 1-9, characterized in that: Comprises the following steps: Adding the chemical fertilizer into water and stirring until dissolved, then adding humic acid, stirring evenly, adding the plant protein-based pollen polysaccharide thermosensitive hydrogel, shearing at a high speed of 10000 rpm for 5 - 10 min to form a microparticle gel form, then adding chlorogenic acid and making up water, stirring evenly, and adjusting the pH value to 6.5 - 7.5.

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