Rapeseed flowering period one promotes four prevents multifunctional foliar fertilizer and its preparation method and application

Abstract

The application discloses rape flower period one promotes four prevents multifunctional foliar fertilizer and a preparation method and application thereof, and the preparation method comprises the following steps: firstly, preparing citric acid-glycine copolymer through polycondensation reaction of citric acid and glycine, and preparing polyaspartic acid-caprolactam copolymer through ring-opening copolymerization reaction of polyaspartic acid and caprolactam; secondly, mixing quick-acting chelated boron and non-ionic surfactant, and mixing long-acting chelated boron and anionic dispersant to form dispersion liquids at 40-50 DEG C, mixing the dispersion liquids in proportion, and adding polyethylene glycol to obtain composite chelated boron; finally, mixing base nutrient components, bacillus subtilis, imidacloprid and the composite chelated boron in sequence, adjusting the pH value to 6-7, and filtering the mixture through a 200-300 mesh filter screen to obtain the finished product. The quick-acting chelated boron formed by the citric acid-glycine copolymer realizes rapid boron absorption, and the long-acting chelated boron formed by the polyaspartic acid-caprolactam copolymer realizes long-acting supply, so that the continuous supply of boron during the flowering period is ensured.

Description

Technical Field

[0001] This invention relates to the field of crop fertilizer preparation technology, specifically to a multifunctional foliar fertilizer for rapeseed flowering period that promotes growth and prevents four types of damage, as well as its preparation method and application. Background Technology

[0002] Rapeseed is an important oilseed crop in my country. The flowering period, a crucial node in its growth cycle, directly affects pod development, seed setting rate, and final yield. During this stage, rapeseed has an urgent need for nutrients and faces various environmental and biological stresses, requiring a high degree of comprehensive adaptability to foliar fertilizers.

[0003] Currently, the application of foliar fertilizers during the rapeseed flowering period still faces several technical limitations in practical applications: First, their functional coverage is limited. Most products focus on a single effect, either emphasizing nutrient supplementation or pest and disease control, making it difficult to meet the multiple needs of rapeseed during the flowering period for nutrient supply, disease control, pest control, and stress resistance. This results in the need for multiple sprayings of different products in the field, increasing labor costs and potentially causing component antagonism. Second, the utilization efficiency of key nutrients is low, especially the supply of boron, which is significantly insufficient. Traditional products often use simple boron compounds such as boric acid and borax, which easily combine with other ions in the soil to form insoluble salts. Firstly, foliar spraying can easily lead to loss due to rain or volatilization, failing to provide a continuous and stable boron support for rapeseed pollination and fruit setting. Secondly, there is insufficient component compatibility; some compound foliar fertilizers do not fully consider the physicochemical properties of different components in their formulation design, and the mixing of chemical agents and bioactive ingredients can easily lead to activity inhibition, and precipitation reactions may also occur between nutrient elements, causing the actual effect of the product to deviate from expectations. Thirdly, the product stability is poor; some foliar fertilizers lack suitable dispersion and emulsification systems, and are prone to stratification and flocculation during storage, making it difficult to adhere evenly to the leaf surface after spraying, affecting absorption efficiency.

[0004] At the same time, existing foliar fertilizers also lack adaptability to application scenarios. They do not fully combine the field environment characteristics and plant physiological state during the rapeseed flowering period to adjust the spraying plan, which further limits the effectiveness of their application.

[0005] Therefore, it is necessary to provide a multifunctional foliar fertilizer for promoting rapeseed flowering and preventing four types of damage, as well as its preparation method and application, to solve the above-mentioned technical problems. Summary of the Invention

[0006] The purpose of this invention is to provide a multifunctional foliar fertilizer for rapeseed flowering period that promotes growth and prevents disease and pests, as well as its preparation method and application, in order to solve the problems of existing foliar fertilizers for rapeseed flowering period having single function, low boron utilization efficiency, poor component compatibility and poor application adaptability, and difficulty in meeting the needs of nutrient supply, disease and pest control and stress resistance.

[0007] To achieve the above objectives, the present invention provides the following technical solution: In its first aspect, this invention provides a multifunctional foliar fertilizer for rapeseed flowering, promoting growth and preventing disease while protecting against pests and diseases. The fertilizer comprises 100 parts by weight, containing the following components: 0.1-0.2 parts urea, 0.08-0.15 parts potassium dihydrogen phosphate, 0.05-0.15 parts brassinolide, 0.5-1 part Bacillus subtilis, 0.3-0.8 parts imidacloprid, 0.2-0.3 parts compound chelated boron, 1-2 parts nonionic surfactant, 0.8-1.2 parts anionic dispersant, 1-2 parts polyethylene glycol, and the balance being deionized water; wherein the viable bacteria content of the Bacillus subtilis is 10%. 7 -10 9 CFU / g; the composite chelated boron is composed of a mixture of fast-acting chelated boron and long-acting chelated boron in a ratio of 40-60:60-40; the chelating agent of the fast-acting chelated boron is a citric acid-glycine copolymer; the chelating agent of the long-acting chelated boron is a polyaspartic acid-caprolactam copolymer; the overall pH value of the foliar fertilizer is 6-7.

[0008] In this invention, urea and potassium dihydrogen phosphate provide core nitrogen and phosphorus nutrients for rapeseed during its flowering period, meeting the nutritional needs of plant growth, flower bud differentiation, and silique development. Brassinolide regulates plant physiological metabolism, enhances stress resistance, and promotes nutrient absorption and conversion. Bacillus subtilis forms a biofilm on the rapeseed leaf surface, inhibiting pathogen colonization and reproduction, achieving a biological disease control effect; its viable bacterial content is controlled at 10%. 7 -10 9 Within the CFU / g range, it ensures both disease-preventing activity and avoids resource waste. Imidacloprid specifically controls piercing-sucking pests such as aphids, blocking pest feeding and virus transmission, and ensuring normal plant growth. The compound chelated boron uses a dual-chelation system: the fast-acting chelated boron formed by citric acid-glycine copolymer has a small molecular structure that is easily absorbed by the leaves, timely replenishing the boron needed for pollination during flowering; the long-acting chelated boron formed by polyaspartic acid-caprolactam copolymer has strong stability, achieving long-term release of boron. The two are mixed in a 40-60:60-40 ratio to ensure a continuous and stable supply of boron, preventing flowering without fruiting. At the same time, nonionic surfactants reduce the surface tension of the foliar fertilizer, improving leaf adhesion and wetting effects; anionic dispersants prevent component aggregation; and polyethylene glycol enhances system stability, thereby ensuring uniform application and storage stability of the foliar fertilizer. The pH value is controlled at 6-7, which matches the absorption characteristics of rapeseed leaves and the survival requirements of Bacillus subtilis, ensuring that each component functions efficiently and achieving the effects of promoting growth, preventing diseases and pests, preventing lodging, and preventing flowering without fruiting.

[0009] In a second aspect, this invention provides a method for preparing a multifunctional foliar fertilizer for rapeseed flowering period that promotes growth and prevents four types of damage, comprising the following steps: a: Preparation of citric acid-glycine copolymer; b: Preparation of polyaspartic acid-caprolactam copolymer; c: Preparation of composite chelated boron; d: Prepare foliar fertilizer by mixing the components prepared in steps a, b, and c.

[0010] The preparation method provided by this invention, by first preparing citric acid-glycine copolymer and polyaspartic acid-caprolactam copolymer, allows for precise control of the structure and purity of the chelating agent, laying the foundation for the subsequent preparation of chelated boron. The separate preparation step of the composite chelated boron ensures that the fast-acting and long-acting chelated boron are fully mixed in a set ratio, forming a stable dual supply. Finally, the components are mixed in an orderly manner to avoid premature reactions between different functional components, ensuring the synergistic effect of nutrients, biological agents, and chemical agents, and improving the consistency and stability of product performance.

[0011] Preferably, the preparation step of the citric acid-glycine copolymer in step a is as follows: a1: Mix citric acid and glycine at a molar ratio of 1:0.8-1.2. Dry the citric acid at 100-110℃ for 1-1.2 hours in advance to remove moisture; a2: Add the mixture obtained in step a1 to the reaction apparatus, slowly heat to 130-155℃, and continue stirring until the system becomes homogeneous and transparent; a3: Maintain the temperature after step a2 for 1-3 hours, during which time the water produced in the reaction is discharged; a4: After the reaction is complete, the mixture is naturally cooled to room temperature to obtain a citric acid-glycine copolymer.

[0012] In this invention, citric acid is dried beforehand to remove moisture, which avoids the impact of moisture on the efficiency of the polycondensation reaction and ensures that citric acid and glycine react fully at the set molar ratio. The molar ratio is controlled at 1:0.8-1.2 to balance the chelating ability and molecular size of the chelating agent, ensuring that the chelate formed by subsequent binding with boron ions is easily absorbed by the leaf surface and possesses a certain degree of stability. A reaction temperature of 130-155℃ and a reaction time of 1-3 hours provide suitable conditions for the polycondensation reaction, promoting the formation of a structurally stable copolymer between citric acid and glycine. Water generated during the reaction is discharged, driving the reaction forward. Natural cooling to room temperature avoids the destruction of the copolymer structure due to high temperatures. The final citric acid-glycine copolymer has high purity and stable chelating properties, and can efficiently bind with boron ions to form a chelate that is easily absorbed by the leaf surface.

[0013] Preferably, the preparation step of the polyaspartic acid-caprolactam copolymer in step b is as follows: b1: Mix polyaspartic acid and caprolactam in a molar ratio of 1:1-2 and dissolve them in an organic solvent; b2: Add 0.3%-1% of the catalyst by total mass to the system and heat to 150-175℃ under nitrogen protection; b3: React at a constant temperature for 2-4 hours, with continuous stirring during the process to promote the ring-opening copolymerization reaction; b4: After the reaction is complete, the organic solvent is removed, and the polyaspartic acid-caprolactam copolymer is obtained after purification and drying.

[0014] In this invention, polyaspartic acid and caprolactam are mixed in a molar ratio of 1:1-2 and dissolved in an organic solvent to ensure sufficient contact between the two. A catalyst dosage of 0.3%-1% effectively promotes the ring-opening copolymerization reaction while avoiding excessive catalyst residue that could affect product safety. Heating to 150-175℃ under nitrogen protection prevents oxidation of the reaction system, providing a stable environment for ring-opening copolymerization. A constant temperature reaction time of 2-4 hours ensures the reaction proceeds fully, forming a long-chain macromolecular copolymer. Subsequent removal of the organic solvent and purification and drying improve the copolymer purity, ensuring strong stability and long-lasting chelating ability when used as a long-acting boron chelating agent, preventing rapid loss or fixation of boron in the soil.

[0015] Preferably, the preparation step of the composite chelated boron in step c is as follows: c1: Mix fast-acting chelated boron with a nonionic surfactant and stir at low speed at 40-50℃ to form dispersion A; c2: Mix long-acting chelated boron with anionic dispersant and stir at low speed at 40-50℃ to form dispersion B; c3: Mix dispersion A and dispersion B in a ratio of 40-60:60-40, add polyethylene glycol, and stir at a constant speed for 30 minutes to form a composite chelated boron.

[0016] In this invention, a temperature of 40-50℃ and low-speed stirring conditions promote the full combination of fast-acting chelated boron with nonionic surfactants and long-acting chelated boron with anionic dispersants, while avoiding damage to the chelate structure. The separate preparation of dispersion A and dispersion B optimizes the dispersion state of the two chelated borons respectively, and then they are mixed in a set ratio to ensure uniform distribution. The addition of polyethylene glycol further enhances the system stability, prevents stratification and agglomeration, and uniform stirring for 30 minutes ensures that the composite chelated boron forms a uniform and stable dispersion system, guaranteeing the functions of rapid foliar absorption and long-term soil replenishment, and improving the overall utilization efficiency of boron.

[0017] Preferably, step d, which involves mixing the specific components to prepare the foliar fertilizer, includes: d1: Weigh out urea, potassium dihydrogen phosphate, brassinolide, Bacillus subtilis, imidacloprid, compound chelated boron, nonionic surfactant, anionic dispersant, polyethylene glycol and deionized water according to the weight proportions, with deionized water as the remainder, for later use; among them, urea, potassium dihydrogen phosphate and brassinolide are mixed evenly in advance. d2: Add the weighed deionized water to the stirred reactor and heat it to 30-40℃. During the stirring process, slowly add the prepared mixture of urea, potassium dihydrogen phosphate, and brassinolide and stir until completely dissolved to obtain the basic nutrient solution. d3: Add Bacillus subtilis and imidacloprid to the basic nutrient solution in sequence, maintain a constant temperature of 30-40℃, and stir for 15-20 minutes to ensure uniform dispersion of the components; d4: Add composite chelated boron, nonionic surfactant, anionic dispersant and polyethylene glycol to the mixture obtained in step d3, and stir continuously for 20-30 minutes. During this period, adjust the pH of the system to 6-7 using a pH adjuster. d5: Cool the above system to room temperature, filter it through a 200-300 mesh filter to remove insoluble impurities, and obtain the foliar fertilizer.

[0018] In this invention, urea, potassium dihydrogen phosphate, and brassinolide are pre-mixed to ensure uniform dispersion of nutrients, allowing for rapid dissolution upon subsequent addition of deionized water. A temperature of 30-40°C and stirring accelerate the dissolution process, forming a stable basic nutrient solution. Bacillus subtilis and imidacloprid are added sequentially to prevent premature contact and antagonistic reactions. Maintaining a constant temperature of 30-40°C and stirring for 15-20 minutes ensures the activity of the biological agents and the uniform dispersion of the chemical agents. The subsequent addition of compound chelated boron and various adjuvants prevents interference with the biological agents and chemical agents. Continuous stirring ensures full integration of all components, and the pH is adjusted to 6-7, providing the optimal environment for each component to function. Filtering with a 200-300 mesh screen removes insoluble impurities, preventing nozzle clogging during spraying, improving the purity of the foliar fertilizer, ensuring uniform application and absorption, and ultimately resulting in a stable and reliable foliar fertilizer product.

[0019] Preferably, the organic solvent in step b1 is at least one of N,N-dimethylformamide, dimethyl sulfoxide, or ethylene glycol dimethyl ether; and the catalyst is at least one of p-toluenesulfonic acid, sulfuric acid, or phosphoric acid.

[0020] In this invention, N,N-dimethylformamide, dimethyl sulfoxide, and ethylene glycol dimethyl ether all possess good solubility, rapidly dissolving polyaspartic acid and caprolactam, providing a uniform reaction environment for their ring-opening copolymerization reaction and ensuring the reaction proceeds fully. Toluenesulfonic acid, sulfuric acid, and phosphoric acid serve as catalysts, exhibiting strong catalytic activity and effectively reducing the activation energy of the ring-opening copolymerization reaction, promoting the formation of a structurally stable copolymer between polyaspartic acid and caprolactam.

[0021] Preferably, the nonionic surfactant in step c1 is at least one of fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, or sorbitan fatty acid ester polyoxyethylene ether; and the anionic dispersant in step c2 is at least one of sodium lignosulfonate, sodium naphthalenesulfonate formaldehyde condensate, or sodium alkylbenzenesulfonate.

[0022] In this invention, fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, and sorbitan fatty acid ester polyoxyethylene ether all possess excellent surface activity and wettability, reducing the surface tension of the fast-acting chelated boron dispersion and improving the adhesion effect during subsequent foliar spraying. Simultaneously, they promote the uniform distribution of fast-acting chelated boron in the dispersion. Sodium lignosulfonate, sodium naphthalenesulfonate formaldehyde condensate, and sodium alkylbenzenesulfonate, as anionic dispersants, exhibit excellent dispersing performance, effectively preventing the aggregation of long-acting chelated boron particles and ensuring the stability of dispersion B. The selected surfactants and dispersants all possess good biocompatibility, exhibit no antagonistic effects with other components, and synergistically enhance the dispersion stability and application effect of the composite chelated boron.

[0023] Preferably, the pH adjuster in step d4 is at least one of citric acid, acetic acid, or potassium dihydrogen phosphate.

[0024] In this invention, citric acid and acetic acid are weak acids, providing gentle and stable pH adjustment without causing drastic pH fluctuations. They are also compatible with other components in the system without adverse reactions. Potassium dihydrogen phosphate, a nutrient component of foliar fertilizer, acts as a pH adjuster, regulating the system pH to a suitable range of 6-7 while also supplementing some phosphorus and potassium, achieving a dual function of regulation and nutrient supplementation. The selected pH adjuster ensures the stability of the foliar fertilizer system, meeting the needs of rapeseed foliar absorption and Bacillus subtilis survival.

[0025] In a third aspect, this invention provides an application of a multifunctional foliar fertilizer that promotes growth and prevents disease during the rapeseed flowering period, comprising the following steps: Step 1: 1-2 days before spraying, clear the silt and weeds from the field ditches, waist ditches, and perimeter ditches. Adjust the depth and width of the ditches according to the slope and soil texture of the plot to ensure that the soil moisture content in the field is controlled at 60%-70% after drainage. Step 2: At the initial flowering stage of rapeseed, spray foliar fertilizer at a rate of 25-35 kg per mu (approximately 0.067 hectares). Use a fan-shaped nozzle, adjust the working pressure to 0.3-0.5 MPa, keep the nozzle 20-30 cm away from the top of the plant, and move at a speed of 0.8-1.0 m / s to ensure that the foliar fertilizer evenly covers the upper leaves, flower stems, flower buds, and base of the stem. If there is continuous rainy weather, postpone spraying until 9-11 am on a sunny day. If it rains within 4 hours after spraying, re-spray with 40%-60% of the original amount. Step 3: 5-7 days after spraying, inspect the plant growth in the field; for plots with weak growth, apply an additional low-concentration nutrient supplement solution. The supplement solution is calculated as 8-12 parts urea, 4-6 parts potassium dihydrogen phosphate, and 9982-9988 parts deionized water per 10,000 parts by weight, with a dosage of 15-25 kg per acre; keep the field free of significant water accumulation during the growing season, and promptly check and clear any blockages in the drainage system after heavy rain.

[0026] In this invention, before spraying, field ditches are cleared and their depth and width adjusted to control soil moisture content at 60%-70%. This provides a suitable water environment for rapeseed root growth while preventing excessive soil moisture that could lead to disease, laying the foundation for the effectiveness of foliar fertilizer. The initial flowering stage of rapeseed is a critical period for nutrient demand and pest and disease control; spraying foliar fertilizer at this time precisely meets the plant's growth needs. A dosage of 25-35 kg per acre, a fan-shaped nozzle with specific working pressure, nozzle height, and movement speed ensures even coverage of key areas, improving absorption efficiency. Adjusting the spraying time and re-spraying measures according to weather conditions prevents rainwater runoff and ensures application effectiveness. Inspections are conducted 5-7 days after spraying, and weak seedlings are supplemented with a low-concentration nutrient solution. This specifically addresses differences in growth, promotes uniform plant growth in the field, and the low-concentration formula supplements nutrients while avoiding fertilizer burn. Maintaining a dry field during the growing season and promptly clearing ditches can reduce the risk of disease outbreaks, further ensure the effectiveness of foliar fertilizers, and ultimately achieve increased rapeseed yield and improved quality.

[0027] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention provides a nutritional foundation for plant growth, flower bud differentiation, and silique development through nitrogen and phosphorus nutrition. Brassinolide regulates physiological metabolism, enhances stress resistance, and promotes nutrient conversion; the two work synergistically to promote robust plant growth. Bacillus subtilis forms a biological protective film on the leaf surface, inhibiting the colonization and reproduction of pathogens, while imidacloprid specifically blocks feeding by pests such as aphids and the spread of viruses. The complementary effects of biological disease control and chemical insect control effectively reduce the risk of plant damage and ensure unobstructed nutrient absorption pathways.

[0028] 2. This invention addresses the low utilization efficiency of traditional boron fertilizers through a dual supply of compound chelated boron. The small molecular structure of the fast-acting chelated boron allows for rapid absorption by the leaves, promptly replenishing the boron needed for pollination during flowering. The long-acting chelated boron, with its stable long-chain structure, slowly releases boron into the soil. The two are mixed in a specific ratio to ensure a continuous and stable supply of boron throughout the flowering period, significantly reducing the phenomenon of flowers failing to set. Furthermore, the combined effect of nitrogen and phosphorus nutrients and boron improves photosynthetic efficiency and nutrient distribution, promotes carbohydrate transport and accumulation, and simultaneously increases the number of siliques, grains, and grain weight, significantly optimizing rapeseed yield and quality.

[0029] 3. This invention utilizes the combined action of nonionic surfactants, anionic dispersants, and polyethylene glycol to reduce the surface tension of foliar fertilizers, prevent component aggregation, enhance system stability, ensure uniform distribution of nutrients, biological agents, and chemical agents, and improve leaf adhesion and wetting effects. Precise pH control within a suitable range not only matches the absorption characteristics of rapeseed leaves but also ensures the activity of Bacillus subtilis and the stability of its chelates, enabling each component to function efficiently.

[0030] 4. This invention employs a step-by-step synthesis and orderly mixing process. First, high-purity chelating agents and composite chelated boron are precisely prepared. Then, the functional components are mixed in a rational order to avoid premature reactions and antagonistic effects, ensuring consistent and stable product performance. In application, by considering the physiological characteristics of rapeseed at its initial flowering stage and the field environment, spraying parameters, supplementary spraying measures, and field management plans are optimized to achieve synergy between environmental control, foliar fertilizer effects, and precise fertilization, maximizing overall effectiveness while reducing the number of field sprays and lowering labor costs. Attached Figure Description

[0031] Figure 1 The bar chart shows the comparison of yield per mu (unit of land area) after the application of the multifunctional foliar fertilizer for promoting flowering period and preventing four diseases in rapeseed prepared in Examples 1-3 and Comparative Examples 1-6. Figure 2 Line graphs showing the comparison of sclerotinia disease incidence rates after application of the multifunctional foliar fertilizer for rapeseed flowering period promotion and prevention prepared in Examples 1-3 and Comparative Examples 1-6; Figure 3 Line graphs showing the comparison of aphid population reduction rates after application of the multifunctional foliar fertilizer for rapeseed flowering period promotion and prevention prepared in Examples 1-3 and Comparative Examples 1-6. Figure 4 Line graphs showing the lodging rates after application of the multifunctional foliar fertilizer for promoting flowering and preventing four types of damage to rapeseed prepared in Examples 1-3 and Comparative Examples 1-6; Figure 5 This is a bar chart comparing the boron content of rapeseed grains after application of the multifunctional foliar fertilizer for promoting flowering and preventing four types of damage prepared in Examples 1-3 and Comparative Examples 1-6. Detailed Implementation

[0032] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] Example 1: This embodiment provides a multifunctional foliar fertilizer for promoting flowering and preventing four types of damage in rapeseed. The total weight is 100 parts, and the specific components are: 0.15 parts urea, 0.12 parts potassium dihydrogen phosphate, 0.1 parts brassinolide, 0.7 parts Bacillus subtilis, 0.6 parts imidacloprid, 0.25 parts compound chelated boron, 1.5 parts fatty alcohol polyoxyethylene ether, 1.1 parts sodium lignosulfonate, 1.5 parts polyethylene glycol, and the remainder is deionized water. The overall pH of the foliar fertilizer is 6.5; the viable bacteria content of Bacillus subtilis is 5 × 10⁻⁶. 8 CFU / g; The composite chelated boron is a mixture of fast-acting chelated boron and long-acting chelated boron in a 50:50 ratio; the chelating agent of the fast-acting chelated boron is citric acid-glycine copolymer; the chelating agent of the long-acting chelated boron is polyaspartic acid-caprolactam copolymer.

[0034] Its preparation method includes the following steps: a: Preparation of citric acid-glycine copolymer a1: Mix solid citric acid and glycine in a molar ratio of 1:1. The citric acid is dried at 105℃ for 1 hour in advance to remove moisture. a2: Add the mixture to the reactor, slowly heat to 140°C, and stir continuously at 70 rpm until the system becomes homogeneous and transparent; a3: Maintain 140℃ and distill under reduced pressure at 0.085MPa for 2 hours, during which the water produced in the reaction is discharged; a4: After the reaction is complete, the mixture is allowed to cool naturally to room temperature and then sieved through an 80-mesh filter to obtain a citric acid-glycine copolymer.

[0035] b: Preparation of polyaspartic acid-caprolactam copolymer b1: Mix polyaspartic acid and caprolactam in a molar ratio of 1:1.4, add N,N-dimethylformamide in an amount 6 times the total mass of the mixture, and stir at 90 rpm at 45°C to dissolve. b2: Add 0.6% p-toluenesulfonic acid by mass to the system and heat to 160°C under nitrogen protection; b3: React at a constant temperature for 2.5 hours, during which the mixture is continuously stirred at a rate of 80 rpm to promote the ring-opening copolymerization reaction; b4: After the reaction was completed, the organic solvent was removed by rotary evaporation at 65℃ and 0.09MPa. The product was washed three times with ethanol and dried at 85℃ for 2.5h to obtain polyaspartic acid-caprolactam copolymer.

[0036] c: Preparation of composite chelated boron c1: Take fast-acting chelated boron and fatty alcohol polyoxyethylene ether, mix them, and stir at 40 rpm for 20 min at 45℃ to form a dispersion A with a solid content of 9%. c2: Take long-acting chelated boron and sodium lignosulfonate, mix them, and stir at 40 rpm for 20 min at 45℃ to form a dispersion B with a solid content of 9%. c3: Mix dispersion A and dispersion B in a 50:50 ratio, add polyethylene glycol, and stir at a constant speed of 70 rpm for 30 min while maintaining a temperature of 45°C to obtain composite chelated boron.

[0037] d: Mix the components to prepare foliar fertilizer d1: Weigh each component according to the above weight proportions and set aside; among them, urea, potassium dihydrogen phosphate, and brassinolide should be mixed in advance using a high-speed mixer at a speed of 1200 rpm for 5 minutes. d2: Add deionized water to a stirred reactor and heat it to 35°C at a rate of 1°C / min. Add the mixture of urea, potassium dihydrogen phosphate and brassinolide in three portions at 80 rpm intervals, stirring until completely dissolved to obtain the basic nutrient solution. d3: First add imidacloprid to the basic nutrient solution, keep the temperature at 35℃ and stir at 80 rpm for 10 min, then lower the system temperature to 28℃, add Bacillus subtilis, stir at 35 rpm for 5 min to make the components evenly dispersed. d4: Add composite chelated boron, fatty alcohol polyoxyethylene ether, sodium lignosulfonate and polyethylene glycol to the above mixture, and stir continuously at 75 rpm for 25 min. During this period, adjust the pH of the system to 6.5 with citrate-sodium citrate buffer solution. The amount of buffer solution added is 0.8% of the total weight of the system. d5: Cool the above system to room temperature, filter it through a 250-mesh filter at a pressure of 0.15 MPa to obtain the foliar fertilizer.

[0038] Example 2: This embodiment provides a multifunctional foliar fertilizer for promoting flowering and preventing four types of damage in rapeseed. The total weight is 100 parts, and the specific components are as follows: 0.13 parts urea, 0.14 parts potassium dihydrogen phosphate, 0.08 parts brassinolide, 0.6 parts Bacillus subtilis, 0.4 parts imidacloprid, 0.22 parts compound chelated boron, 1.2 parts alkylphenol polyoxyethylene ether, 0.9 parts sodium naphthalenesulfonate formaldehyde condensate, 1.3 parts polyethylene glycol, and the remainder is deionized water. The overall pH value of the foliar fertilizer is 6.2; the viable bacteria content of Bacillus subtilis is 3 × 10⁻⁶. 7 CFU / g; The composite chelated boron is a mixture of fast-acting chelated boron and long-acting chelated boron in a ratio of 40:60; the chelating agent of the fast-acting chelated boron is citric acid-glycine copolymer; the chelating agent of the long-acting chelated boron is polyaspartic acid-caprolactam copolymer.

[0039] Its preparation method includes the following steps: a: Preparation of citric acid-glycine copolymer a1: Mix solid citric acid and glycine at a molar ratio of 1:0.9. The citric acid is dried at 102℃ for 1.1h beforehand to remove moisture. a2: Add the mixture to the reactor, slowly heat to 135°C, and stir continuously at 65 rpm until the system becomes homogeneous and transparent. a3: Maintain 135℃ and distill under reduced pressure at 0.08MPa for 1.8h, during which the water produced in the reaction is discharged; a4: After the reaction is complete, the mixture is allowed to cool naturally to room temperature and then sieved through an 80-mesh filter to obtain a citric acid-glycine copolymer.

[0040] b: Preparation of polyaspartic acid-caprolactam copolymer b1: Mix polyaspartic acid and caprolactam in a molar ratio of 1:1.2, add dimethyl sulfoxide in an amount of 5 times the total mass of the mixture, and stir at 85 rpm at 42°C to dissolve. b2: Add 0.5% p-toluenesulfonic acid by mass to the system and heat to 155°C under nitrogen protection; b3: React at a constant temperature for 2 hours, during which the ring-opening copolymerization reaction is promoted by continuous stirring at a rate of 75 rpm. b4: After the reaction was completed, the organic solvent was removed by rotary evaporation at 62℃ and 0.09MPa. The product was washed twice with ethanol and dried at 82℃ for 2 hours to obtain the polyaspartic acid-caprolactam copolymer.

[0041] c: Preparation of composite chelated boron c1: Take fast-acting chelated boron and alkylphenol polyoxyethylene ether, mix them, and stir at 35 rpm for 20 min at 42℃ to form a dispersion A with a solid content of 8%. c2: Take the long-acting chelated boron and sodium naphthalene sulfonate formaldehyde condensate, mix them, and stir at 35 rpm for 20 min at 42℃ to form a dispersion B with a solid content of 8%. c3: Mix dispersion A and dispersion B in a ratio of 40:60, add polyethylene glycol, and stir at a constant speed of 65 rpm for 30 min while maintaining a temperature of 42°C to obtain composite chelated boron.

[0042] d: Mix the components to prepare foliar fertilizer d1: Weigh each component according to the above weight proportions and set aside; among them, urea, potassium dihydrogen phosphate, and brassinolide should be mixed in advance using a high-speed mixer at a speed of 1100 rpm for 4 minutes. d2: Add deionized water to the stirred reactor and heat it to 33°C at a rate of 1.2°C / min. Add the mixture of urea, potassium dihydrogen phosphate and brassinolide in three portions at 75 rpm intervals, stirring until completely dissolved to obtain the basic nutrient solution. d3: First add imidacloprid to the basic nutrient solution, keep the temperature at 33℃ and stir at 75 rpm for 8 minutes, then lower the system temperature to 26℃, add Bacillus subtilis, stir at 30 rpm for 6 minutes to make the components evenly dispersed. d4: Add composite chelated boron, alkylphenol polyoxyethylene ether, sodium naphthalene sulfonate formaldehyde condensate and polyethylene glycol to the above mixture, and stir continuously at 70 rpm for 22 min. During this period, adjust the pH of the system to 6.2 with citrate-sodium citrate buffer solution. The amount of buffer solution added is 0.6% of the total weight of the system. d5: Cool the above system to room temperature, filter it through a 220-mesh filter at a pressure of 0.12 MPa to obtain the foliar fertilizer.

[0043] Example 3: This embodiment provides a multifunctional foliar fertilizer for promoting flowering and preventing four types of damage during rapeseed flowering. The total weight is 100 parts, and the specific components are as follows: 0.18 parts urea, 0.09 parts potassium dihydrogen phosphate, 0.14 parts brassinolide, 0.9 parts Bacillus subtilis, 0.7 parts imidacloprid, 0.28 parts compound chelated boron, 1.8 parts sorbitan fatty acid ester polyoxyethylene ether, 1.1 parts sodium alkylbenzene sulfonate, 1.8 parts polyethylene glycol, and the remainder is deionized water. The overall pH value of the foliar fertilizer is 6.8; the viable bacteria content of Bacillus subtilis is 8 × 10⁻⁶. 9 CFU / g; The composite chelated boron is a mixture of fast-acting chelated boron and long-acting chelated boron in a ratio of 60:40; the chelating agent of the fast-acting chelated boron is citric acid-glycine copolymer; the chelating agent of the long-acting chelated boron is polyaspartic acid-caprolactam copolymer.

[0044] Its preparation method includes the following steps: a: Preparation of citric acid-glycine copolymer a1: Mix solid citric acid and glycine in a molar ratio of 1:1.1. The citric acid is dried at 108℃ for 1 hour in advance to remove moisture; a2: Add the mixture to the reactor, slowly heat to 150°C, and stir continuously at 75 rpm until the system becomes homogeneous and transparent; a3: Maintain 150℃ and distill under reduced pressure at 0.09MPa for 2.2h, during which the water produced in the reaction is removed; a4: After the reaction is complete, the mixture is allowed to cool naturally to room temperature and then sieved through an 80-mesh filter to obtain a citric acid-glycine copolymer.

[0045] b: Preparation of polyaspartic acid-caprolactam copolymer b1: Mix polyaspartic acid and caprolactam in a molar ratio of 1:1.6, add ethylene glycol dimethyl ether in an amount of 7 times the total mass of the mixture, and stir at 95 rpm at 48°C to dissolve. b2: Add 0.9% p-toluenesulfonic acid by mass to the system and heat to 170°C under nitrogen protection; b3: React at a constant temperature for 3 hours, during which the mixture is continuously stirred at a rate of 85 rpm to promote the ring-opening copolymerization reaction; b4: After the reaction was completed, the organic solvent was removed by rotary evaporation at 68℃ and 0.09MPa. The product was washed three times with ethanol and dried at 88℃ for 3 hours to obtain the polyaspartic acid-caprolactam copolymer.

[0046] c: Preparation of composite chelated boron c1: Take fast-acting chelated boron and dehydrated sorbitan fatty acid ester polyoxyethylene ether and stir at low speed of 45 rpm for 20 min at 48℃ to form a dispersion A with a solid content of 10%. c2: Take long-acting chelated boron and sodium alkylbenzene sulfonate, mix them, and stir at 45 rpm for 20 min at 48℃ to form a dispersion B with a solid content of 10%. c3: Mix dispersion A and dispersion B in a ratio of 60:40, add polyethylene glycol, and stir at a constant speed of 75 rpm for 30 min while maintaining the temperature at 48°C to obtain composite chelated boron.

[0047] d: Mix the components to prepare foliar fertilizer d1: Weigh each component according to the above weight proportions and set aside; among them, urea, potassium dihydrogen phosphate, and brassinolide should be mixed in advance using a high-speed mixer at a speed of 1300 rpm for 6 minutes. d2: Add deionized water to the stirred reactor and heat it to 37°C at a rate of 0.8°C / min. Add the mixture of urea, potassium dihydrogen phosphate and brassinolide in three portions at 85 rpm intervals, stirring until completely dissolved to obtain the basic nutrient solution. d3: First add imidacloprid to the basic nutrient solution, keep the temperature at 37℃ and stir at 85 rpm for 12 min, then lower the system temperature to 30℃, add Bacillus subtilis, stir at 40 rpm for 4 min to make the components evenly dispersed. d4: Add composite chelated boron, dehydrated sorbitan fatty acid ester polyoxyethylene ether, sodium alkylbenzene sulfonate and polyethylene glycol to the above mixture, and stir continuously at 80 rpm for 28 min. During this period, adjust the pH of the system to 6.8 with potassium dihydrogen phosphate-dipotassium hydrogen phosphate buffer. The amount of buffer added is 1.0% of the total weight of the system. d5: Cool the above system to room temperature, filter it through a 280-mesh filter at a pressure of 0.18 MPa to obtain the foliar fertilizer.

[0048] Example 4: This embodiment provides a multifunctional foliar fertilizer for rapeseed flowering, promoting growth and preventing four types of damage. The total weight is 100 parts, and the specific components are: 0.11 parts urea, 0.09 parts potassium dihydrogen phosphate, 0.06 parts brassinolide, 0.5 parts Bacillus subtilis, 0.3 parts imidacloprid, 0.2 parts compound chelated boron, 1.1 parts fatty alcohol polyoxyethylene ether, 0.8 parts sodium lignosulfonate, 1.1 parts polyethylene glycol, with the remainder being deionized water. The overall pH of the foliar fertilizer is 6.0; the viable bacteria content of Bacillus subtilis is 1×10⁻⁶. 7 CFU / g; The composite chelated boron is a mixture of fast-acting chelated boron and long-acting chelated boron in a ratio of 40:60; the chelating agent of the fast-acting chelated boron is citric acid-glycine copolymer; the chelating agent of the long-acting chelated boron is polyaspartic acid-caprolactam copolymer.

[0049] Its preparation method includes the following steps: a: Preparation of citric acid-glycine copolymer a1: Mix solid citric acid and glycine at a molar ratio of 1:0.8. The citric acid is dried at 100℃ for 1 hour in advance to remove moisture. a2: Add the mixture to the reactor, slowly heat to 130°C, and stir continuously at 60 rpm until the system becomes homogeneous and transparent. a3: Maintain 130℃ and distill under reduced pressure at 0.08MPa for 1 hour, during which the water produced in the reaction is discharged; a4: After the reaction is complete, the mixture is allowed to cool naturally to room temperature and then sieved through an 80-mesh filter to obtain a citric acid-glycine copolymer.

[0050] b: Preparation of polyaspartic acid-caprolactam copolymer b1: Mix polyaspartic acid and caprolactam in a molar ratio of 1:1, add N,N-dimethylformamide in an amount of 5 times the total mass of the mixture, and stir at 80 rpm at 40°C to dissolve. b2: Add 0.3% p-toluenesulfonic acid by mass to the system and heat to 150°C under nitrogen protection; b3: React at a constant temperature for 2 hours, during which the ring-opening copolymerization reaction is promoted by continuous stirring at a rate of 70 rpm. b4: After the reaction was completed, the organic solvent was removed by rotary evaporation at 60℃ and 0.09MPa. The product was washed twice with ethanol and dried at 80℃ for 2 hours to obtain the polyaspartic acid-caprolactam copolymer.

[0051] c: Preparation of composite chelated boron c1: Take fast-acting chelated boron and fatty alcohol polyoxyethylene ether, mix them, and stir at 30 rpm for 20 min at 40℃ to form a dispersion A with a solid content of 8%. c2: Take long-acting chelated boron and sodium lignosulfonate, mix them, and stir at 30 rpm for 20 min at 40℃ to form a dispersion B with a solid content of 8%. c3: Mix dispersion A and dispersion B in a ratio of 40:60, add polyethylene glycol, and stir at a constant speed of 60 rpm for 30 min while maintaining a temperature of 40°C to obtain composite chelated boron.

[0052] d: Mix the components to prepare foliar fertilizer d1: Weigh each component according to the above weight proportions and set aside; among them, urea, potassium dihydrogen phosphate, and brassinolide should be mixed in advance using a high-speed mixer at a speed of 1000 rpm for 4 minutes. d2: Add deionized water to a stirred reactor and heat it to 30°C at a rate of 1°C / min. Add the mixture of urea, potassium dihydrogen phosphate and brassinolide in three portions at 70 rpm intervals, stirring until completely dissolved to obtain the basic nutrient solution. d3: First add imidacloprid to the basic nutrient solution, keep the temperature at 30℃ and stir at 70rpm for 8min, then lower the system temperature to 25℃, add Bacillus subtilis, stir at 30rpm for 5min to make the components evenly dispersed. d4: Add composite chelated boron, fatty alcohol polyoxyethylene ether, sodium lignosulfonate and polyethylene glycol to the above mixture, and stir continuously at 65 rpm for 20 min. During this period, adjust the pH of the system to 6.0 with citrate-sodium citrate buffer solution. The amount of buffer solution added is 0.5% of the total weight of the system. d5: Cool the above system to room temperature, filter it through a 200-mesh filter at a pressure of 0.1 MPa to obtain the foliar fertilizer.

[0053] Example 5: This embodiment provides a multifunctional foliar fertilizer for rapeseed flowering, promoting growth and preventing four types of damage. The total weight is 100 parts, and the specific components are: 0.2 parts urea, 0.15 parts potassium dihydrogen phosphate, 0.15 parts brassinolide, 1 part Bacillus subtilis, 0.8 parts imidacloprid, 0.3 parts compound chelated boron, 2 parts fatty alcohol polyoxyethylene ether, 1.2 parts sodium lignosulfonate, 2 parts polyethylene glycol, and the remainder is deionized water. The overall pH of the foliar fertilizer is 7.0; the viable bacteria content of Bacillus subtilis is 1×10⁻⁶. 9 CFU / g; The composite chelated boron is a mixture of fast-acting chelated boron and long-acting chelated boron in a ratio of 60:40; the chelating agent of the fast-acting chelated boron is citric acid-glycine copolymer; the chelating agent of the long-acting chelated boron is polyaspartic acid-caprolactam copolymer.

[0054] Its preparation method includes the following steps: a: Preparation of citric acid-glycine copolymer a1: Mix solid citric acid and glycine in a molar ratio of 1:1.2. The citric acid is dried at 110℃ for 1.2 hours in advance to remove moisture. a2: Add the mixture to the reactor, slowly heat to 155°C, and stir continuously at 80 rpm until the system becomes homogeneous and transparent; a3: Maintain 155℃ and distill under reduced pressure at 0.09MPa for 3 hours, during which the water produced in the reaction is discharged; a4: After the reaction is complete, the mixture is allowed to cool naturally to room temperature and then sieved through an 80-mesh filter to obtain a citric acid-glycine copolymer.

[0055] b: Preparation of polyaspartic acid-caprolactam copolymer b1: Mix polyaspartic acid and caprolactam in a molar ratio of 1:2, add N,N-dimethylformamide in an amount equal to 8 times the total mass of the mixture, and stir at 100 rpm at 50°C to dissolve. b2: Add 1% p-toluenesulfonic acid by mass to the system and heat to 175°C under nitrogen protection; b3: React at a constant temperature for 4 hours, during which the ring-opening copolymerization reaction is promoted by continuous stirring at a rate of 90 rpm. b4: After the reaction was completed, the organic solvent was removed by rotary evaporation at 70℃ and 0.09MPa. The product was washed three times with ethanol and dried at 90℃ for 3 hours to obtain the polyaspartic acid-caprolactam copolymer.

[0056] c: Preparation of composite chelated boron c1: Take fast-acting chelated boron and fatty alcohol polyoxyethylene ether, mix them, and stir at low speed of 50 rpm for 20 min at 50℃ to form a dispersion A with a solid content of 10%. c2: Take long-acting chelated boron and sodium lignosulfonate, mix them, and stir at 50 rpm for 20 min at 50℃ to form a dispersion B with a solid content of 10%. c3: Mix dispersion A and dispersion B in a ratio of 60:40, add polyethylene glycol, and stir at a constant speed of 80 rpm for 30 min while maintaining a temperature of 50°C to obtain composite chelated boron.

[0057] d: Mix the components to prepare foliar fertilizer d1: Weigh each component according to the above weight proportions and set aside; among them, urea, potassium dihydrogen phosphate, and brassinolide should be mixed in advance using a high-speed mixer at a speed of 1500 rpm for 6 minutes. d2: Add deionized water to a stirred reactor and heat it to 40°C at a rate of 1.5°C / min. Add the mixture of urea, potassium dihydrogen phosphate and brassinolide in three portions at 90 rpm intervals, stirring until completely dissolved to obtain the basic nutrient solution. d3: First add imidacloprid to the basic nutrient solution, keep the temperature at 40℃ and stir at 90 rpm for 12 min, then lower the system temperature to 30℃, add Bacillus subtilis, and stir at 40 rpm for 5 min to make the components evenly dispersed. d4: Add composite chelated boron, fatty alcohol polyoxyethylene ether, sodium lignosulfonate and polyethylene glycol to the above mixture, and stir continuously at 85 rpm for 30 min. During this period, adjust the pH of the system to 7.0 with potassium dihydrogen phosphate-dipotassium hydrogen phosphate buffer solution. The amount of buffer solution added is 1.0% of the total weight of the system. d5: Cool the above system to room temperature, filter it through a 300-mesh filter at a pressure of 0.2 MPa to obtain the foliar fertilizer.

[0058] To further highlight the advantages of the embodiments of the present invention, the following traditional rapeseed flowering period spraying scheme of promoting growth and preventing four types of damage is provided: Option 1: This solution is suitable for fields with medium fertility and low incidence of pests and diseases. The specific formula and application are as follows: 1. Formula (dosage per acre) Nutritional composition: 80g potassium dihydrogen phosphate granules + 100g borax, with an effective boron content of not less than 11%; Disease prevention components: 50g of 50% carbendazim wettable powder + 40ml of 25% prochloraz emulsifiable concentrate; Insect repellent component: 4.5% high-efficiency cypermethrin emulsifiable concentrate 30ml; Adjusting component: Brassinolide 10ml; Solvent: Add 40kg of water and stir until completely dissolved.

[0059] 2. Application Method Spray for the first time when 25% of the rapeseed plants are in bloom at the initial flowering stage, and spray for the second time when 50% of the plants are in full bloom, with an interval of 7 days. Use a manual sprayer and spray at a rate of no less than 30 kg / mu to ensure even coverage of the flower stems, leaves, flower buds and stem base. If it rains within 4 hours after spraying, re-spray with 50% of the original amount.

[0060] 3. Expected Results It controls rapeseed aphids and sclerotinia disease, prevents flowering without fruiting and premature aging, and promotes silique development, increasing the number of siliques and the thousand-seed weight compared to the blank control group. However, boron is easily fixed by the soil or washed away by rainwater, making it impossible to achieve long-term supply. In addition, there is no nitrogen supplementation, resulting in insufficient nutritional support for flower bud differentiation and silique development. Multiple sprayings are required, which is labor-intensive. The mixing of chemical agents is prone to antagonism, and the stability of the effect is greatly affected by the operation.

[0061] Option 2: This solution is suitable for fields where the incidence of sclerotinia leaf disease in rapeseed is not less than 10% and aphids are prevalent. The specific formula and application are as follows: 1. Formula (dosage per acre) Nutritional composition: 100g potassium dihydrogen phosphate granules + 50g fast-acting boron, with an effective boron content greater than 20%; Disease prevention components: 100g of 40% iprodione wettable powder + 70g of 50% procymidone wettable powder; Insect-repellent components: 20g of 25% pymetrozine suspension concentrate + 10g of 25% thiamethoxam water-dispersible granules; Adjusting components: 70g of 15% paclobutrazol + 10ml of brassinolide; Solvent: Mix with 50kg of water using a two-stage dilution method. First, dissolve the powder in a small amount of water, then add the emulsifiable oil and nutrient components.

[0062] 2. Application Method The first spray should be applied at the initial flowering stage, and the second spray should be applied at the peak flowering stage. If the disease is not controlled, an additional spray should be applied when 10% of the plants are in bloom at the end of the flowering stage, with each application 10 days apart. Use a motorized sprayer with a pressure of 0.3-0.5 MPa and a spray rate of 15 kg / mu. Keep the nozzle 20-30 cm away from the top of the plant. Strictly start spraying when the leaf disease rate is not less than 10% to avoid blind application of pesticides.

[0063] 3. Expected Results This invention improves aphid population reduction and sclerotinia disease control, reduces flowering failure, increases yield compared to conventional methods, enhances stem toughness, and reduces lodging rate. However, it relies entirely on chemical pesticides, which can easily lead to excessive residues, pesticide resistance in pests and diseases, and requires cumbersome secondary dilution and multiple sprayings, resulting in labor-intensive and time-consuming processes. It lacks a biological control component, is less environmentally friendly, and lacks a long-term nutrient supply mechanism, making it prone to nutrient deficiency in the later stages. The invention also provides the following comparative examples: Comparative Example 1: The only difference between this comparative example and Example 1 is that the composite chelated boron contains only fast-acting chelated boron and no long-acting chelated boron; otherwise, it is completely the same as Example 1.

[0064] Expected performance: Relying solely on fast-acting chelated boron to provide boron, without the long-term replenishment effect of long-acting chelated boron, rapeseed is prone to insufficient boron supply in the later stages of growth, which may lead to decreased pollination efficiency and reduced seed setting rate. At the same time, the boron absorption and utilization rate is limited, making it difficult to fully meet the continuous boron demand of rapeseed during flowering. Overall, the growth-promoting effect and stress resistance are weaker than in Example 1.

[0065] Comparative Example 2: The only difference between this comparative example and Example 1 is that the composite chelated boron contains only long-acting chelated boron and does not contain fast-acting chelated boron; otherwise, it is completely consistent with Example 1.

[0066] Expected performance: Although long-acting chelated boron can release boron for a long time, the absorption rate on the leaves is slow and cannot quickly meet the urgent need for boron in the early flowering stage of rapeseed. This may lead to early flowering or incomplete development of flower organs, which in turn affects the fruit set. In addition, insufficient boron supply in the early stage will indirectly weaken plant growth and affect the synergistic effect of disease and pest control.

[0067] Comparative Example 3: The only difference between this comparative example and Example 1 is that Bacillus subtilis is not added; otherwise, they are completely identical to Example 1.

[0068] Expected performance: Lacking the biological disease control effect of Bacillus subtilis, it cannot form an effective biofilm on the rapeseed leaf surface to inhibit the reproduction of pathogens, resulting in a significant decrease in the control effect against fungal diseases such as sclerotinia rot. The plants are more susceptible to disease, which in turn affects photosynthesis and nutrient accumulation, leading to stunted growth and suppressed yield.

[0069] Comparative Example 4: The only difference between this comparative example and Example 1 is that imidacloprid is not added; otherwise, they are completely identical to Example 1.

[0070] Expected performance: Lacking the chemical insecticidal effect of imidacloprid, it is difficult to effectively control piercing-sucking pests such as aphids. Pest feeding leads to nutrient loss and leaf damage in plants, which not only directly affects the normal growth, development, flowering and fruiting of rapeseed, but may also spread viral diseases, further exacerbating the negative impact on yield and quality.

[0071] Comparative Example 5: The only difference between this comparative example and Example 1 is that the composite chelated boron is replaced with ordinary boric acid; otherwise, it is completely the same as Example 1.

[0072] Expected performance: Ordinary boric acid has no chelating and protective effect, is easily fixed in the soil, and is also easily lost quickly after foliar spraying. The utilization rate of boron is significantly reduced, and it cannot stably provide sufficient boron during the rapeseed flowering period, which may lead to rapeseed flowering without fruiting and poor silique development. At the same time, it lacks the synergistic effect of chelating agents, and the overall stability and effectiveness of nutrient supply are weaker than in Example 1.

[0073] Comparative Example 6: The only difference between this comparative example and Example 1 is that the mixing ratio of fast-acting chelated boron to long-acting chelated boron is 20:80 when preparing the composite chelated boron; otherwise, it is completely the same as Example 1.

[0074] Expected performance: The proportion of fast-acting chelated boron is too low, which cannot quickly meet the needs of foliar absorption in the early flowering stage of rapeseed. The proportion of long-acting chelated boron is too high, which leads to insufficient boron supply in the early stage. The balance of the two synergistic supplementation is broken, the absorption efficiency and supply timeliness of boron decrease, and thus affect the flowering, fruiting and stress resistance of rapeseed. The overall effect is not as good as the 40-60:60-40 mixing ratio in Example 1.

[0075] To compare the performance differences of the multifunctional foliar fertilizer for promoting rapeseed flowering and preventing four types of damage provided in Examples 1-5 and Comparative Examples 1-6, the present invention provides the following experimental methods: 1. Experimental Materials and Field Design Rapeseed varieties tested: Locally cultivated varieties were selected, with seedlings of uniform growth and an age of 30 days.

[0076] Experimental plots: Select experimental fields with uniform soil fertility and convenient irrigation and drainage. The soil type is loam, pH value is 6.5-7.0, organic matter content is 1.8-2.2%, and the previous crop is not cruciferous vegetables.

[0077] The experimental field was divided into 11 plots, corresponding to Examples 1-5 and Comparative Examples 1-6, with an additional blank control group. Each plot had an area of ​​20㎡ and a spacing of 1m between plots. The plots were randomly arranged and replicated 3 times.

[0078] Cultivation and Management: All plots adopt the same conventional planting density of 12,000 plants per mu. The application level of base fertilizer is consistent, with 2,000 kg of decomposed organic fertilizer and 30 kg of compound fertilizer per mu. Weeding and irrigation are carried out uniformly during the growing season, with the only difference being the foliar fertilizer spraying treatment.

[0079] 2. Foliar fertilizer spraying treatment Spraying time: The first spraying is carried out at the initial flowering stage of rapeseed, with a flowering rate of 5-10%. Examples 1-5 and Comparative Examples 1-6 spray the corresponding foliar fertilizer at a dosage of 25-35 kg per mu, while the blank control group is sprayed with an equal amount of deionized water.

[0080] Application method: Use a fan-shaped nozzle with a working pressure of 0.3-0.5 MPa. Keep the nozzle 20-30 cm away from the top of the plant and move it at a speed of 0.8-1.0 m / s to ensure that the foliar fertilizer evenly covers the upper leaves, flower stems, flower buds and base of the stem.

[0081] Re-spraying conditions: If it rains within 4 hours after spraying, re-spray at 40-60% of the original dosage; if there is continuous rainy weather, postpone spraying until 9-11 am on a sunny day.

[0082] Application of supplementary solution: Inspect the plots 5-7 days after spraying. For plots with weak growth, judge by plant height being 20% ​​lower than the average level and yellowing rate of lower leaves ≥30%. Spray low-concentration nutrient supplementary solution at a rate of 15-25 kg per acre.

[0083] 3. Detection Indicators and Methods Growth promotion indicators: After rapeseed matures and is harvested, 20 plants are randomly selected from each plot to determine the number of pods per plant and the number of grains per pod. The weight of 1,000 grains is measured using a 1,000-grain weight meter, and the yield per acre is calculated based on the total yield of the plot.

[0084] Disease control effect: During the flowering and maturity period of rapeseed, the incidence of sclerotinia rot was investigated every 10 days. The proportion of diseased plants to the total number of plants was counted as the incidence of sclerotinia rot. The criterion for disease was the appearance of brown lesions on the stems or pods of the plants, accompanied by the formation of sclerotia.

[0085] Insect control effect: The number of aphids was investigated 7 days and 14 days after spraying, and the aphid population reduction rate was calculated. The aphid population reduction rate = (number of aphids before spraying - number of aphids after spraying) / number of aphids before spraying × 100%.

[0086] Resistance effect: During the rapeseed maturity period, the lodging rate is the proportion of lodged plants in the plot to the total number of plants. The lodging standard is a plant tilt angle ≥45°.

[0087] Boron absorption efficiency: After harvesting, rapeseed grains were dried, crushed, and then the boron content in the grains was determined using inductively coupled plasma mass spectrometry.

[0088] The experimental data are as follows:

[0089] Based on experimental data, the significant increase in yield indicators stems from the synergistic growth-promoting mechanism of nitrogen and phosphorus nutrition, compound chelated boron, and brassinolide. Urea and potassium dihydrogen phosphate provide nitrogen and phosphorus, offering the energy basis for rapeseed flower bud differentiation and silique development. Brassinolide regulates physiological metabolism and promotes nutrient conversion, while the dual-supply system of compound chelated boron ensures a stable boron supply throughout the flowering period. The small molecular structure of fast-acting chelated boron enables rapid boron absorption, meeting the needs during the critical pollination period, while the long-chain structure of long-acting chelated boron slowly releases boron, preventing boron deficiency and subsequent fruitlessness. Under these combined effects, the number of siliques per plant, the number of seeds per silique, and the thousand-seed weight in Examples 1-5 were simultaneously optimized, ultimately leading to a significant increase in yield per acre compared to the control group.

[0090] Data on disease and insect control efficacy show that in Examples 1-5, Bacillus subtilis inhibited pathogen reproduction by forming a biofilm on the leaf surface, and imidacloprid specifically blocked aphid feeding and virus transmission, resulting in a sclerotinia disease incidence rate controlled at 2.8%-7.3% and an aphid population reduction rate of 85.6%-93.1%. In contrast, Comparative Example 3, lacking Bacillus subtilis, lost its biological disease control effect, and the sclerotinia disease incidence rate soared to 15.7%; Comparative Example 4, lacking imidacloprid, lacked chemical insect control function, and the aphid population reduction rate was only 42.6%.

[0091] Data on stress resistance and boron absorption efficiency showed that the lodging rate of Examples 1-5 was only 1.8%-6.8%, and the boron content in the grains was 23.4%-31.2 mg / kg. This effect was attributed to the reasonable ratio of compound chelated boron and the synergistic effect of adjuvants. Nonionic surfactants improved leaf adhesion and absorption, while anionic dispersants and polyethylene glycol ensured system stability, enabling efficient absorption of boron by the plants and enhancing stem toughness and stress resistance. Comparative Examples 1-2 lacked a single chelated boron component, thus failing to form a continuous boron supply; Comparative Example 5 used ordinary boric acid, which lacked chelation protection, leading to easy fixation and loss of boron; Comparative Example 6 had an unbalanced ratio, disrupting the synergistic supply balance. The boron content in the grains of all three examples was below 23 mg / kg, and the lodging rate was significantly higher than that of the Examples.

[0092] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A multifunctional foliar fertilizer for rapeseed flowering period that promotes growth and prevents four types of damage, characterized in that, The total weight is 100 parts, comprising the following components: 0.1-0.2 parts urea, 0.08-0.15 parts potassium dihydrogen phosphate, 0.05-0.15 parts brassinolide, 0.5-1 parts Bacillus subtilis, 0.3-0.8 parts imidacloprid, 0.2-0.3 parts compound chelated boron, 1-2 parts nonionic surfactant, 0.8-1.2 parts anionic dispersant, 1-2 parts polyethylene glycol, and the balance being deionized water; The viable bacterial content of the Bacillus subtilis is 10. 7 -10 9 CFU / g; the composite chelated boron is composed of a mixture of fast-acting chelated boron and long-acting chelated boron in a ratio of 40-60:60-40; the chelating agent of the fast-acting chelated boron is a citric acid-glycine copolymer; the chelating agent of the long-acting chelated boron is a polyaspartic acid-caprolactam copolymer; the overall pH value of the foliar fertilizer is 6-7.

2. The preparation method of a multifunctional foliar fertilizer for promoting flowering and preventing four types of damage to rapeseed as described in claim 1, characterized in that, Includes the following steps: a: Preparation of citric acid-glycine copolymer; b: Preparation of polyaspartic acid-caprolactam copolymer; c: Preparation of composite chelated boron; d: Prepare foliar fertilizer by mixing the components prepared in steps a, b, and c.

3. The preparation method according to claim 2, characterized in that, The preparation steps of the citric acid-glycine copolymer in step a are as follows: a1: Mix citric acid and glycine at a molar ratio of 1:0.8-1.

2. Dry the citric acid at 100-110℃ for 1-1.2 hours in advance to remove moisture; a2: Add the mixture obtained in step a1 to the reaction apparatus, slowly heat to 130-155℃, and continue stirring until the system becomes homogeneous and transparent; a3: Maintain the temperature after step a2 for 1-3 hours, during which time the water produced in the reaction is discharged; a4: After the reaction is complete, the mixture is allowed to cool naturally to room temperature to obtain a citric acid-glycine copolymer.

4. The preparation method according to claim 2, characterized in that, The preparation steps of the polyaspartic acid-caprolactam copolymer in step b are as follows: b1: Mix polyaspartic acid and caprolactam in a molar ratio of 1:1-2 and dissolve them in an organic solvent; b2: Add 0.3%-1% of the catalyst by total mass to the system and heat to 150-175℃ under nitrogen protection; b3: React at a constant temperature for 2-4 hours, with continuous stirring during the process to promote the ring-opening copolymerization reaction; b4: After the reaction is complete, the organic solvent is removed, and the polyaspartic acid-caprolactam copolymer is obtained after purification and drying.

5. The preparation method according to claim 2, characterized in that, The preparation steps of the composite chelated boron in step c are as follows: c1: Mix fast-acting chelated boron with a nonionic surfactant and stir at low speed at 40-50℃ to form dispersion A; c2: Mix long-acting chelated boron with anionic dispersant and stir at low speed at 40-50℃ to form dispersion B; c3: Mix dispersion A and dispersion B in a ratio of 40-60:60-40, add polyethylene glycol, and stir at a constant speed for 30 minutes to form a composite chelated boron.

6. The preparation method according to claim 2, characterized in that, The step d, which involves mixing the specific components to prepare the foliar fertilizer, includes: d1: Weigh out urea, potassium dihydrogen phosphate, brassinolide, Bacillus subtilis, imidacloprid, compound chelated boron, nonionic surfactant, anionic dispersant, polyethylene glycol and deionized water according to the weight proportions, with deionized water as the remainder, for later use; among them, urea, potassium dihydrogen phosphate and brassinolide are mixed evenly in advance. d2: Add the weighed deionized water to the stirred reactor and heat it to 30-40℃. During the stirring process, slowly add the prepared mixture of urea, potassium dihydrogen phosphate, and brassinolide and stir until completely dissolved to obtain the basic nutrient solution. d3: Add Bacillus subtilis and imidacloprid to the basic nutrient solution in sequence, maintain a constant temperature of 30-40℃, and stir for 15-20 minutes to ensure uniform dispersion of the components; d4: Add composite chelated boron, nonionic surfactant, anionic dispersant and polyethylene glycol to the mixture obtained in step d3, and stir continuously for 20-30 minutes. During this period, adjust the pH of the system to 6-7 using a pH adjuster. d5: Cool the above system to room temperature, filter it through a 200-300 mesh filter to remove insoluble impurities, and obtain the foliar fertilizer.

7. The preparation method according to claim 4, characterized in that, The organic solvent mentioned in step b1 is at least one of N,N-dimethylformamide, dimethyl sulfoxide, or ethylene glycol dimethyl ether; The catalyst is at least one of p-toluenesulfonic acid, sulfuric acid, or phosphoric acid.

8. The preparation method according to claim 5, characterized in that, The nonionic surfactant mentioned in step c1 is at least one of fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, or sorbitan fatty acid ester polyoxyethylene ether. The anionic dispersant mentioned in step c2 is at least one of sodium lignosulfonate, sodium naphthalenesulfonate formaldehyde condensate, or sodium alkylbenzenesulfonate.

9. The preparation method according to claim 6, characterized in that, The pH adjuster mentioned in step d4 is at least one of citric acid, acetic acid, or potassium dihydrogen phosphate.

10. The application of a multifunctional foliar fertilizer for promoting flowering and preventing four types of damage to rapeseed as described in any one of claims 1-9, characterized in that, Includes the following steps: Step 1: 1-2 days before spraying, clear the silt and weeds from the field ditches, waist ditches, and perimeter ditches. Adjust the depth and width of the ditches according to the slope and soil texture of the plot to ensure that the soil moisture content in the field is controlled at 60%-70% after drainage. Step 2: At the initial flowering stage of rapeseed, spray foliar fertilizer at a rate of 25-35 kg per mu. Use a fan-shaped nozzle, adjust the working pressure to 0.3-0.5 MPa, keep the nozzle 20-30 cm away from the top of the plant, and move at a speed of 0.8-1.0 m / s to ensure that the foliar fertilizer evenly covers the upper leaves, flower stems, flower buds and base of the stem. If there is continuous rainy weather, postpone the spraying to a sunny morning between 9 and 11:00; if it rains within 4 hours after spraying, re-spray at 40%-60% of the original dosage. Step 3: 5-7 days after spraying, inspect the plant growth in the field; for plots with weak growth, apply an additional low-concentration nutrient supplement solution. The supplement solution is calculated as 8-12 parts urea, 4-6 parts potassium dihydrogen phosphate, and 9982-9988 parts deionized water per 10,000 parts by weight, with a dosage of 15-25 kg per acre; keep the field free of significant water accumulation during the growing season, and promptly check and clear any blockages in the drainage system after heavy rain.

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