A plant nutrient composition containing a polypeptide and a method for preparing the same

Abstract

The application discloses a kind of plant nutrition composition containing polypeptide and preparation method thereof, it is related to agricultural fertilizer technical field, raw material includes according to weight part: polypeptide active component 10~40 parts, plant immune component 2~15 parts, trace element complex 5~20 parts, biomimetic gradient porous carrier 20~60 parts, functional adjuvant 1~10 parts;The polypeptide active component is composed of small molecule active polypeptide with molecular weight 300~1000Da, medium molecular weight functional polypeptide with molecular weight 1000~3000Da and macromolecular immune induction polypeptide with molecular weight 3000~5000Da;The polypeptide of different molecular weight range is scientifically graded in the application, and different functions, such as intracellular signal transduction and metabolic regulation, cell surface receptor activation and immune induction, are exerted respectively, so that the problem that polypeptide molecular weight grading design is insufficient in existing product and comprehensive control effect is difficult to realize is solved.

Description

Technical Field

[0001] This invention relates to the field of agricultural fertilizer technology, specifically to a plant nutrient composition containing polypeptides and its preparation method. Background Technology

[0002] Polypeptides play a crucial regulatory role in plant growth and development, acting as signaling molecules to participate in physiological processes such as growth, stress response, and nutrient absorption. In recent years, fertilizers containing polypeptides have gained increasing attention due to their ability to enhance crop resistance and immunity, reduce crop disease incidence, and produce no pollution or residues, demonstrating promising applications in green and sustainable agriculture.

[0003] Field trials of plant immune inducers such as amino oligosaccharides on pear trees have shown their effects in preventing frost damage, protecting flowers and fruits, controlling diseases, and increasing yield and income. Spraying amino oligosaccharides on citrus trees has also demonstrated significant effects in preventing frost damage, improving fruit set rate, and enhancing fruit quality. Chitosan oligosaccharides have also been proven to be a broad-spectrum plant flower and fruit protectant, applicable to both vegetables and fruit trees. Existing research indicates that peptides of different molecular weights exhibit significantly different mechanisms of action in plants: small-molecule peptides are easily absorbed directly into cells by plants, participating in intracellular signal transduction and metabolic regulation; medium-molecule peptides are more suitable for receptor activation and immune induction on the cell surface. Furthermore, peptides possess excellent metal ion chelating abilities and can act as natural chelating agents to promote the absorption and utilization of trace elements such as zinc, iron, and manganese by plants.

[0004] Although the application value of peptides in plant nutrition and fruit setting is widely recognized, existing plant nutrition products containing peptides still have significant shortcomings. First, the active ingredients have poor stability; peptides are easily degraded and inactivated during storage and transportation, with particularly severe loss of activity under high temperature and humidity conditions. While some products use carrier materials to load the active ingredients, the pore structure of existing carriers is relatively simple, making it difficult to achieve differentiated protection and gradient controlled release based on the characteristics of different functional components. Second, the molecular weight classification design of peptide components is insufficient. Existing products have peptides with a wide molecular weight distribution range or concentrated in a narrow range, failing to scientifically combine and grade peptides based on differences in absorption pathways and target sites within plants, thus limiting the comprehensive regulatory effects of peptides in promoting flowering, maintaining flowering, and preserving fruit.

[0005] Therefore, developing a plant nutrient composition containing peptides that can achieve gradient controlled release based on the characteristics of peptides with different molecular weights, has good stability of active ingredients, and excellent comprehensive regulatory effects has important practical significance and application value. Summary of the Invention

[0006] The purpose of this invention is to provide a plant nutrient composition containing polypeptides and its preparation method, so as to solve the problems of poor stability of active ingredients, lack of gradient controlled release, and unreasonable polypeptide compatibility in existing polypeptide plant nutrient compositions.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a plant nutrient composition containing polypeptides, wherein the raw materials by weight include: 10-40 parts of polypeptide active components, 2-15 parts of plant immune induction components, 5-20 parts of trace element complexes, 20-60 parts of biomimetic gradient porous carriers, and 1-10 parts of functional additives.

[0008] The polypeptide active component is composed of small molecule active polypeptides with a molecular weight of 300-1000 Da, medium molecule functional polypeptides with a molecular weight of 1000-3000 Da, and large molecule immune-inducing polypeptides with a molecular weight of 3000-5000 Da in a mass ratio of 2-4:1-2:0.5-1.

[0009] The biomimetic gradient porous carrier has a three-layer pore structure with a decreasing pore size gradient from the outer layer to the inner layer. The outer layer has a pore size of 50-100 nm, the middle layer has a pore size of 20-50 nm, and the inner layer has a pore size of 5-20 nm. The surface is modified with amino and carboxyl active groups.

[0010] Furthermore, the small molecule active polypeptide is derived from the enzymatic hydrolysis product of soybean protein isolate, the medium molecule functional polypeptide is derived from the enzymatic hydrolysis product of fish skin collagen, and the large molecule immune-inducing polypeptide is derived from the enzymatic hydrolysis product of yeast protein.

[0011] Furthermore, the plant immune-inducing component is composed of amino oligosaccharides and chitosan oligosaccharides in a mass ratio of 1-3:1-2.

[0012] Furthermore, the trace element complex is a product obtained by complexation reaction of polypeptide active component and EDTA-trace element at a mass ratio of 1-2:1-3, and the trace element includes zinc, iron, manganese, boron and molybdenum.

[0013] Furthermore, the functional additives include polyaspartic acid and γ-polyglutamic acid in a mass ratio of 1-3:1-2.

[0014] This invention also discloses a method for preparing a plant nutrient composition containing polypeptides, which is used to prepare the above-mentioned plant nutrient composition containing polypeptides. The preparation method includes the following steps:

[0015] S1. Weigh out the polypeptide active components, plant immune induction components, trace element complexes and functional additives according to the ratio, add them to deionized water, stir and dissolve at 20-40℃, and prepare a mixed solution with a mass fraction of 20%-40%.

[0016] S2. Add the biomimetic gradient porous support to the mixed solution and stir and adsorb in stages at 20-45℃ for 1.5-6 hours to obtain the loaded product.

[0017] S3. Pre-freeze the loaded product at -40 to -20°C for 4 to 8 hours, and then freeze-dry it under vacuum for 24 to 48 hours with a vacuum degree ≤20Pa to obtain the dried product.

[0018] S4. The dried product is pulverized and sieved to obtain a plant nutrient composition containing polypeptides.

[0019] Furthermore, the stirring adsorption in S2 is a segmented stirring adsorption: first, stirring at low speed for 50-100 r / min for 1-2 hours at 20-30℃; then, heating to 30-40℃ and stirring at medium speed for 100-200 r / min for 1-2 hours; finally, stirring at high speed for 200-300 r / min for 1-2 hours at 40-50℃.

[0020] Furthermore, the preparation method of the biomimetic gradient porous carrier in S2 includes:

[0021] A1. Dissolve polylactic acid-glycolic acid copolymer (PLGA) in dichloromethane to prepare a solution with a mass fraction of 5% to 15%, add polyethylene glycol as a porogen, the amount of porogen being 10% to 40% of the mass of PLGA, and stir evenly to use as the outer layer spinning solution.

[0022] A2. Dissolve chitosan in a 2% acetic acid solution to prepare a solution with a mass fraction of 2% to 8%. Add nano silica, the amount of which is 5% to 20% of the mass of chitosan. Stir well to prepare the intermediate spinning solution.

[0023] A3. Dissolve sodium alginate in deionized water to prepare a solution with a mass fraction of 1% to 5%, add nano calcium carbonate, the amount of nano calcium carbonate is 5% to 15% of the mass of sodium alginate, stir evenly to make it the inner layer spinning solution.

[0024] A4. Spinning is carried out using three-layer coaxial electrospinning technology, with a spinning voltage of 15-25kV and a receiving distance of 10-20cm to obtain a fiber membrane.

[0025] A5. After drying the obtained fiber membrane, soak it in deionized water to remove the pore-forming agent, and freeze-dry it to obtain a biomimetic gradient porous carrier.

[0026] A6. The obtained biomimetic gradient porous carrier is then subjected to surface modification with amino and carboxyl active groups in sequence.

[0027] Further, the preparation method of the trace element complex in S1 is as follows: the active peptide component is dissolved in deionized water to prepare a solution with a mass fraction of 5% to 15%, EDTA-trace element is added, and the mixture is stirred and reacted for 2 to 6 hours at 40 to 70°C and pH 6.0 to 8.0. The trace element complex is obtained after spray drying.

[0028] The present invention also discloses the application of a plant nutrient composition containing polypeptides in promoting plant growth, enhancing plant stress resistance, protecting flowers and fruits, and improving crop yield and quality.

[0029] Compared with the prior art, the plant nutrient composition containing polypeptides and its preparation method provided by the present invention have the following beneficial effects:

[0030] (1) This invention scientifically graded and matched peptides of different molecular weight ranges to give full play to their differentiated functions such as intracellular signal transduction and metabolic regulation, cell surface receptor activation and immune induction, thus solving the problem that the existing products have insufficient peptide molecular weight graded design and difficulty in achieving comprehensive regulatory effect.

[0031] (2) The present invention uses a biomimetic gradient porous carrier with a three-layer pore structure with a decreasing pore size from the outer layer to the inner layer to achieve graded loading and gradient controlled release of peptides and functional components of different molecular weights. Furthermore, the amino and carboxyl active groups modified on the surface enhance the loading stability through electrostatic interaction and hydrogen bonding, thus solving the problem that the existing carriers have a single pore structure and are difficult to achieve differentiated protection and gradient controlled release.

[0032] (3) The present invention prepares the composition by vacuum freeze-drying technology and segmented stirring adsorption process, avoiding the destruction of peptide activity by high temperature, and combining the synergistic effect of peptide active components, plant immune induction components, trace element complexes and functional adjuvants, solving the problems of easy degradation and inactivation and poor stability of peptide substances during storage and transportation, and comprehensively improving plant growth, stress resistance, flower and fruit preservation and yield and quality. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0034] Figure 1 This is a schematic flowchart of a method for preparing a plant nutrient composition containing polypeptides, provided in an embodiment of the present invention. Detailed Implementation

[0035] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0036] Example 1:

[0037] Please see Figure 1 A plant nutrient composition containing polypeptides, wherein the raw materials by weight include: 25 parts of polypeptide active component, 8 parts of plant immune induction component, 12 parts of trace element complex, 40 parts of biomimetic gradient porous carrier, and 5 parts of functional additive.

[0038] The small-molecule active peptides in the polypeptide active components are derived from the enzymatic hydrolysis products of soybean protein isolate, the medium-molecule functional peptides are derived from the enzymatic hydrolysis products of fish skin collagen, and the large-molecule immune-inducing peptides are derived from the enzymatic hydrolysis products of yeast protein; the mass ratio of small-molecule active peptides: medium-molecule functional peptides: large-molecule immune-inducing peptides in the polypeptide active components is 3:1.5:0.8.

[0039] The plant immune-inducing component consists of amino oligosaccharides and chitosan oligosaccharides in a mass ratio of 2:1.5.

[0040] The functional additive is composed of polyaspartic acid and γ-polyglutamic acid, with a mass ratio of polyaspartic acid to γ-polyglutamic acid of 2:1.5.

[0041] The preparation method of trace element complexes is as follows:

[0042] The active peptide component was dissolved in deionized water to prepare a 10% (w / w) solution. EDTA-trace elements (EDTA-Zn:EDTA-Fe:EDTA-Mn:EDTA-B:EDTA-Mo in a ratio of 1:1:1:1:1) were added, with a mass ratio of 1.5:2 between the active peptide component and the trace elements. The mixture was stirred and reacted at 55°C and pH 7.0 for 4 hours. After spray drying, a trace element complex was obtained. The inlet temperature of the spray dryer was 160°C and the outlet temperature was 80°C.

[0043] The preparation method of the biomimetic gradient porous carrier is as follows:

[0044] A1. Dissolve PLGA (molecular weight 50,000) in dichloromethane to prepare a 10% solution by mass. Add polyethylene glycol (PEG-4000) as a porogen, with the amount of porogen being 25% of the mass of PLGA. Stir well to prepare the outer spinning solution.

[0045] A2. Dissolve chitosan (degree of deacetylation ≥ 90%) in 2% acetic acid solution to prepare a 5% solution by mass. Add nano silica (particle size 20nm), the amount of nano silica being 10% of the mass of chitosan. Stir well to prepare the intermediate spinning solution.

[0046] A3. Dissolve sodium alginate in deionized water to prepare a 3% solution by mass. Add nano calcium carbonate (50nm particle size) at 10% of the mass of sodium alginate and stir well to prepare the inner spinning solution.

[0047] A4. Spinning was performed using a three-layer coaxial electrospinning technique with an outer layer flow rate of 0.5 mL / h, a middle layer flow rate of 0.3 mL / h, and an inner layer flow rate of 0.2 mL / h. The spinning voltage was 20 kV, and the receiving distance was 15 cm, resulting in a fiber membrane.

[0048] A5. After drying the obtained fiber membrane at 40°C for 12 hours, it was soaked in deionized water for 48 hours to remove the pore-forming agent. After freeze-drying, a biomimetic gradient porous carrier was obtained.

[0049] A6. The obtained biomimetic gradient porous carrier is subjected to surface modification with amino and carboxyl active groups in sequence: first, 3-aminopropyltriethoxysilane (APTES) is used for amination modification, and then succinic anhydride is used for carboxyl modification to obtain a biomimetic gradient porous carrier with amino and carboxyl active groups on its surface.

[0050] The specific implementation method is as follows: the obtained biomimetic gradient porous support is sequentially modified with amino and carboxyl active groups: first, it is immersed in an anhydrous ethanol solution containing 1%–5% (v / v) of 3-aminopropyltriethoxysilane (APTES), and stirred at 50–70°C for 6–12 hours. After washing with anhydrous ethanol, it is vacuum dried to obtain an amino-modified porous support; then, the amino-modified porous support is immersed in an N,N-dimethylformamide (DMF) solution containing 5%–15% (w / w) of succinic anhydride and the catalyst 4-dimethylaminopyridine (DMAP), and stirred at 20–40°C for 12–24 hours. After washing with DMF and deionized water sequentially, it is freeze-dried to obtain a biomimetic gradient porous support with amino (-NH2) and carboxyl (-COOH) active groups simultaneously modified on its surface. Fourier transform infrared spectroscopy (FT-IR) detection shows that at approximately 3400 cm⁻¹... -1 A characteristic absorption peak for NH bonds appears at approximately 1700 cm⁻¹. -1 The presence of characteristic absorption peaks for C=O bonds confirms that amino and carboxyl active groups have been successfully grafted onto the support surface.

[0051] The preparation method of the above-mentioned plant nutrient composition containing polypeptides includes the following steps:

[0052] S1. Weigh out the polypeptide active components, plant immune induction components, trace element complexes and functional additives according to the ratio, add them to deionized water, stir and dissolve at 20-40℃, and prepare a mixed solution with a mass fraction of 20%-40%.

[0053] The specific implementation method is as follows: weigh out the polypeptide active component, plant immune induction component, trace element complex and functional adjuvant according to the ratio, add them to deionized water, stir and dissolve at 30°C to prepare a mixed solution with a mass fraction of 30%.

[0054] S2. Add the biomimetic gradient porous support to the mixed solution and stir and adsorb in stages at 20-45℃ for 1.5-6 hours to obtain the loaded product.

[0055] The specific implementation method is as follows: a biomimetic gradient porous support is added to a mixed solution and subjected to segmented stirring adsorption: first, the mixture is stirred at a low speed of 80 r / min for 1.5 hours at 25°C; then, the temperature is raised to 35°C and stirred at a medium speed of 150 r / min for 1.5 hours; finally, the mixture is stirred at a high speed of 250 r / min for 1.5 hours at 45°C to obtain the loaded product.

[0056] S3. Pre-freeze the loaded product at -40 to -20°C for 4 to 8 hours, and then freeze-dry it under vacuum for 24 to 48 hours with a vacuum degree ≤20Pa to obtain the dried product.

[0057] The specific implementation method is to pre-freeze the loaded product at -30℃ for 6 hours, and then perform vacuum freeze drying for 36 hours with a vacuum degree ≤20Pa to obtain the dried product.

[0058] S4. The dried product is pulverized and sieved to obtain a plant nutrient composition containing polypeptides.

[0059] The specific implementation method is to pulverize the dried product and pass it through an 80-mesh sieve to obtain a plant nutrient composition containing polypeptide substances.

[0060] Example 2:

[0061] Please see Figure 1 This embodiment provides a technical solution based on Embodiment 1: a plant nutrient composition containing polypeptides, the raw materials of which include, by weight: 10 parts of polypeptide active component, 2 parts of plant immune induction component, 5 parts of trace element complex, 20 parts of biomimetic gradient porous carrier, and 1 part of functional additive.

[0062] The mass ratio of small molecule active peptides, medium molecule functional peptides, and large molecule immune-inducing peptides in the polypeptide active component is 2:1:0.5.

[0063] The plant immune-inducing component is composed of amino oligosaccharides and chitosan oligosaccharides in a mass ratio of 1:1.

[0064] The functional additive is composed of polyaspartic acid and γ-polyglutamic acid, with a mass ratio of polyaspartic acid to γ-polyglutamic acid of 1:1.

[0065] The preparation methods for trace element complexes and biomimetic gradient porous carriers are the same as in Example 1.

[0066] The preparation method of the above-mentioned plant nutrient composition containing polypeptides includes the following steps:

[0067] S1. Weigh out the active polypeptide component, plant immune-inducing component, trace element complex and functional adjuvant according to the ratio, add them to deionized water, stir and dissolve at 30°C to prepare a mixed solution with a mass fraction of 30%.

[0068] S2. Add the biomimetic gradient porous support to the mixed solution and perform segmented stirring adsorption: first, stir at low speed of 80 r / min for 1.5 hours at 25℃; then raise the temperature to 35℃ and stir at medium speed of 150 r / min for 1.5 hours; finally, stir at high speed of 250 r / min for 1.5 hours at 45℃ to obtain the loaded product.

[0069] S3. Pre-freeze the loaded product at -30℃ for 6 hours, and then freeze-dry it under vacuum for 36 hours with a vacuum degree ≤20Pa to obtain the dried product.

[0070] S4. The dried product is pulverized and passed through an 80-mesh sieve to obtain a plant nutrient composition containing polypeptides.

[0071] Example 3:

[0072] Please see Figure 1 This embodiment provides a technical solution based on Embodiment 1: a plant nutrient composition containing polypeptides, the raw materials of which include, by weight: 40 parts of polypeptide active component, 15 parts of plant immune induction component, 20 parts of trace element complex, 60 parts of biomimetic gradient porous carrier, and 10 parts of functional additive.

[0073] The mass ratio of small molecule active peptides, medium molecule functional peptides, and large molecule immune-inducing peptides in the polypeptide active component is 4:2:1.

[0074] The plant immune-inducing component is composed of amino oligosaccharides and chitosan oligosaccharides in a mass ratio of 3:2.

[0075] The functional additive is composed of polyaspartic acid and γ-polyglutamic acid, with a mass ratio of polyaspartic acid to γ-polyglutamic acid of 3:2.

[0076] The preparation methods for trace element complexes and biomimetic gradient porous carriers are the same as in Example 1.

[0077] The preparation method of the above-mentioned plant nutrient composition containing polypeptides includes the following steps:

[0078] S1. Weigh out the active polypeptide component, plant immune-inducing component, trace element complex and functional adjuvant according to the ratio, add them to deionized water, stir and dissolve at 30°C to prepare a mixed solution with a mass fraction of 30%.

[0079] S2. Add the biomimetic gradient porous support to the mixed solution and perform segmented stirring adsorption: first, stir at a low speed of 80 r / min for 1.5 hours at 25℃; then raise the temperature to 35℃ and stir at a medium speed of 150 r / min for 1.5 hours; finally, stir at a high speed of 250 r / min for 1.5 hours at 45℃ to obtain the loaded product.

[0080] S3. Pre-freeze the loaded product at -30℃ for 6 hours, and then freeze-dry it under vacuum for 36 hours with a vacuum degree ≤20Pa to obtain the dried product.

[0081] S4. The dried product is pulverized and passed through an 80-mesh sieve to obtain a plant nutrient composition containing polypeptides.

[0082] Comparative Example 1:

[0083] A plant nutrient composition containing polypeptides, wherein the raw materials by weight include: 25 parts of active polypeptide component, 8 parts of plant immune-inducing component, 12 parts of trace element complex, and 5 parts of functional additives.

[0084] Compared with Example 1, this comparative example does not add a biomimetic gradient porous carrier.

[0085] The mass ratio of small molecule active peptides, medium molecule functional peptides, and large molecule immune-inducing peptides in the polypeptide active components is 3:1.5:0.8.

[0086] The plant immune-inducing component consists of amino oligosaccharides and chitosan oligosaccharides in a mass ratio of 2:1.5.

[0087] The functional additive is composed of polyaspartic acid and γ-polyglutamic acid, with a mass ratio of polyaspartic acid to γ-polyglutamic acid of 2:1.5.

[0088] The preparation method of the trace element complex is the same as in Example 1.

[0089] The preparation method of the above-mentioned plant nutrient composition containing polypeptides is as follows: the components are directly mixed evenly to obtain the plant nutrient composition containing polypeptides.

[0090] Comparative Example 2:

[0091] A plant nutrient composition containing polypeptides, wherein the raw materials by weight include: 25 parts of active polypeptide component, 8 parts of plant immune-inducing component, 12 parts of trace element complex, 40 parts of biomimetic gradient porous carrier, and 5 parts of functional additives.

[0092] Compared with Example 1, the active peptide component of this comparative example consists only of small molecule active peptides with a molecular weight of 300-1000 Da.

[0093] The plant immune-inducing component consists of amino oligosaccharides and chitosan oligosaccharides in a mass ratio of 2:1.5.

[0094] The functional additive is composed of polyaspartic acid and γ-polyglutamic acid, with a mass ratio of polyaspartic acid to γ-polyglutamic acid of 2:1.5.

[0095] The preparation methods for trace element complexes and biomimetic gradient porous carriers are the same as in Example 1.

[0096] The preparation method of the above-mentioned plant nutrient composition containing polypeptides includes the following steps:

[0097] S1. Weigh out the active polypeptide component, plant immune-inducing component, trace element complex and functional adjuvant according to the ratio, add them to deionized water, stir and dissolve at 30°C to prepare a mixed solution with a mass fraction of 30%.

[0098] S2. Add the biomimetic gradient porous support to the mixed solution and perform segmented stirring adsorption: first, stir at low speed of 80 r / min for 1.5 hours at 25℃; then raise the temperature to 35℃ and stir at medium speed of 150 r / min for 1.5 hours; finally, stir at high speed of 250 r / min for 1.5 hours at 45℃ to obtain the loaded product.

[0099] S3. Pre-freeze the loaded product at -30℃ for 6 hours, and then freeze-dry it under vacuum for 36 hours with a vacuum degree ≤20Pa to obtain the dried product.

[0100] S4. The dried product is pulverized and passed through an 80-mesh sieve to obtain a plant nutrient composition containing polypeptides.

[0101] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A plant nutrient composition containing polypeptides, characterized in that, The raw materials, by weight, include: 10-40 parts of polypeptide active components, 2-15 parts of plant immune induction components, 5-20 parts of trace element complexes, 20-60 parts of biomimetic gradient porous carriers, and 1-10 parts of functional additives. The polypeptide active component is composed of small molecule active polypeptides with a molecular weight of 300-1000 Da, medium molecule functional polypeptides with a molecular weight of 1000-3000 Da, and large molecule immune-inducing polypeptides with a molecular weight of 3000-5000 Da in a mass ratio of 2-4:1-2:0.5-1. The biomimetic gradient porous carrier has a three-layer pore structure with a decreasing pore size gradient from the outer layer to the inner layer. The outer layer has a pore size of 50-100 nm, the middle layer has a pore size of 20-50 nm, and the inner layer has a pore size of 5-20 nm. The surface is modified with amino and carboxyl active groups.

2. The plant nutrient composition containing polypeptides according to claim 1, characterized in that, The small molecule active polypeptides are derived from the enzymatic hydrolysis products of soybean protein isolate, the medium molecule functional polypeptides are derived from the enzymatic hydrolysis products of fish skin collagen, and the large molecule immune-inducing polypeptides are derived from the enzymatic hydrolysis products of yeast protein.

3. The plant nutrient composition containing polypeptides according to claim 1, characterized in that, The plant immune-inducing component is composed of amino oligosaccharides and chitosan oligosaccharides in a mass ratio of 1-3:1-2.

4. The plant nutrient composition containing polypeptides according to claim 1, characterized in that, The trace element complex is a product obtained by complexation reaction of polypeptide active components and EDTA-trace elements at a mass ratio of 1-2:1-3, and the trace elements include zinc, iron, manganese, boron and molybdenum.

5. A plant nutrient composition containing polypeptides according to claim 1, characterized in that, The functional additives include polyaspartic acid and γ-polyglutamic acid in a mass ratio of 1-3:1-2.

6. A method for preparing a plant nutrient composition containing polypeptides, characterized in that, It is used to prepare a plant nutrient composition containing polypeptide substances as described in any one of claims 1-5, and the preparation method includes the following steps: S1. Weigh out the polypeptide active components, plant immune inducing components, trace element complexes and functional additives according to the ratio, add them to deionized water, stir and dissolve at 20-40℃ to prepare a mixed solution with a mass fraction of 20-40%. S2. Add the biomimetic gradient porous support to the mixed solution and stir and adsorb in stages at 20-45℃ for 1.5-6 hours to obtain the loaded product. S3. Pre-freeze the loaded product at -40 to -20°C for 4 to 8 hours, and then freeze-dry it under vacuum for 24 to 48 hours with a vacuum degree ≤20Pa to obtain the dried product. S4. The dried product is pulverized and sieved to obtain a plant nutrient composition containing polypeptides.

7. The method for preparing a plant nutrient composition containing polypeptides according to claim 6, characterized in that, The adsorption process in S2 is a segmented adsorption process: first, the adsorption is carried out at a low speed of 50-100 r / min for 1-2 hours at 20-30℃; then, the temperature is raised to 30-40℃ and the adsorption is carried out at a medium speed of 100-200 r / min for 1-2 hours; finally, the adsorption is carried out at a high speed of 200-300 r / min for 1-2 hours at 40-50℃.

8. The method for preparing a plant nutrient composition containing polypeptides according to claim 6, characterized in that, The preparation method of the biomimetic gradient porous carrier in S2 includes: A1. Dissolve polylactic acid-glycolic acid copolymer in dichloromethane to prepare a solution with a mass fraction of 5% to 15%, add porogen polyethylene glycol, the amount of porogen is 10% to 40% of the mass of PLGA, and stir evenly to use as the outer layer spinning solution. A2. Dissolve chitosan in a 2% acetic acid solution to prepare a solution with a mass fraction of 2% to 8%. Add nano silica, the amount of which is 5% to 20% of the mass of chitosan. Stir well to prepare the intermediate spinning solution. A3. Dissolve sodium alginate in deionized water to prepare a solution with a mass fraction of 1% to 5%, add nano calcium carbonate, the amount of nano calcium carbonate is 5% to 15% of the mass of sodium alginate, stir evenly to make it the inner layer spinning solution. A4. Spinning is carried out using three-layer coaxial electrospinning technology, with a spinning voltage of 15-25kV and a receiving distance of 10-20cm to obtain a fiber membrane. A5. After drying the obtained fiber membrane, soak it in deionized water to remove the pore-forming agent, and freeze-dry it to obtain a biomimetic gradient porous carrier. A6. The obtained biomimetic gradient porous carrier is then subjected to surface modification with amino and carboxyl active groups in sequence.

9. A method for preparing a plant nutrient composition containing polypeptides according to claim 6, characterized in that, The preparation method of the trace element complex in S1 is as follows: the active polypeptide component is dissolved in deionized water to prepare a solution with a mass fraction of 5% to 15%, EDTA-trace element is added, and the mixture is stirred and reacted for 2 to 6 hours at 40 to 70°C and pH 6.0 to 8.

0. The trace element complex is obtained after spray drying.

10. The application of the plant nutrient composition containing polypeptides according to any one of claims 1-5 in promoting plant growth, enhancing plant stress resistance, protecting flowers and fruits, and improving crop yield and quality.

Images