Foliar nutrition closed-loop synergist based on allelopathic synergy as well as preparation method and application of foliar nutrition closed-loop synergist

Abstract

The invention discloses a foliar nutrition closed-loop synergist based on allelopathic synergy as well as a preparation method and application thereof, and belongs to the technical field of agricultural fertilizers. Comprising the following raw materials in percentage by weight: 10%-20% of a sophora alopecuroide seed extract, 20%-30% of a citrus young fruit extract, 15%-25% of a green coffee bean extract, 5%-15% of a licorice root extract, 3%-8% of a natural surfactant and the balance of deionized water. Wherein the synergist is used when being prepared with a basic foliar fertilizer, so that a closed-loop synergistic system of foliar nutrition is constructed through plant-derived allelochemicals; through cooperation of various plant source allelochemicals, seven closed-loop functions from permeation to circulation are realized, and improvement of a single link is not realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of agricultural fertilizers, and particularly relates to a leaf surface nutrient closed loop synergist based on allelopathy synergy, a preparation method and application thereof. BACKGROUND

[0002] In current agricultural production, leaf fertilization becomes one of important fertilization methods because it can quickly supplement crop nutrients and relieve nutrient deficiency symptoms, but traditional leaf fertilizers and existing synergistic technologies have significant defects. Absorption barrier is difficult to break through: the surface of plant leaves is covered with a hydrophobic cuticle and wax layer, and traditional leaf fertilizer droplets easily form water beads (high surface tension) and cannot spread fully; and the leaf surface is negatively charged, repelling charged nutrient ions (such as K + , PO4 3- ), only about 30% of the nutrients can penetrate into the leaves, and the rest is lost with evaporation and rainwater.

[0003] Fertilizer effect duration is short: traditional leaf fertilizers have no nutrient storage and release mechanism, the nutrients entering the leaves are quickly consumed, the effective period is only 3-5 days, frequent re-spraying is required, increasing the labor cost of farmers; and the intercellular space of monocotyledonous crops (such as rice) is small, and the storage "capacity" is insufficient, the absorption defect is more prominent.

[0004] Effect stability is poor: affected by temperature and humidity (stomata close at low temperature, droplets dry quickly at high temperature), crop type (single leaf vs. double leaf structure difference), water quality (hard water easily leads to nutrient flocculation), the field effect of traditional leaf fertilizers fluctuates by 40%-60%, and farmers have low recognition.

[0005] Existing synergistic technologies have limitations: biological stimulants (such as alginic acid, single amino acid) on the market can only target "root promotion" "stress resistance" and other single links, and have no systematic closed loop; although some synthetic hormones (such as 2,4-D analogues) can promote growth in the short term, they can easily lead to crop overgrowth and early decline, and have residual risks.

[0006] In summary, there is an urgent need for a leaf fertilizer synergistic technology that can break through the absorption barrier, achieve long-term utilization of nutrients, and have stable and safe effects, to solve the pain points of existing technologies. SUMMARY

[0007] In order to overcome some of the problems mentioned in the background, the present application provides a leaf surface nutrient closed loop synergist based on allelopathy synergy, a preparation method and application thereof, to at least partially solve the above problems.

[0008] According to the technical scheme of the present application, a leaf surface nutrient closed loop synergist based on allelopathy synergy is provided, which comprises the following raw materials in percentage by weight: 10%-20% of Sophora alopecuroides seed extract, 20%-30% of citrus young fruit extract, 15%-25% of green coffee bean extract, 5%-15% of licorice root extract, 3%-8% of natural surfactant and the balance of deionized water; The synergist is used with the base foliar fertilizer to configure and use at present to build the closed loop synergistic system of foliar nutrition by plant source allelochemicals.

[0009] Preferably, the coumarin content in the Sophora alopecuroides seed extract is not less than 5%, the flavonoid content in the citrus young fruit extract is not less than 20%, the chlorogenic acid content in the green coffee bean extract is not less than 30%, and the licorice flavone content in the licorice root extract is not less than 15%.

[0010] Preferably, the natural surfactant is tea saponin.

[0011] Preferably, when the synergist is compounded with the base foliar fertilizer, the dilution volume ratio is 1: (200-500).

[0012] Preferably, the base foliar fertilizer comprises one or more of urea, potassium dihydrogen phosphate and trace element fertilizer.

[0013] Further, the application also provides a preparation method of the foliar nutrition closed loop synergistic agent based on allelopathy, comprising the following steps: Raw material pretreatment: Sophora alopecuroides seeds, citrus young fruits, green coffee beans and licorice roots are sequentially cleaned, dried and crushed to obtain powders of the raw materials; Low-temperature enzymolysis: the raw material powders are subjected to enzymolysis treatment by composite cellulase and pectinase at 40-50℃ to obtain a plurality of enzymolysis raw materials; Synergistic extraction: the plurality of enzymolysis raw materials are mixed, and a water-ethanol circulation extraction system is used to perform directional segmented extraction by regulating the pH value to obtain an extraction liquid; Membrane separation refining: the extraction liquid is sequentially filtered and refined by a ceramic membrane system with pore sizes of 100 nm, 50 nm and 10 nm to obtain a refined liquid; Vacuum concentration and compounding: the refined liquid is vacuum concentrated to a predetermined concentration at a temperature lower than 50℃, and then compounded with a natural surfactant and deionized water, and the homogenized product is the synergist.

[0014] Preferably, the synergistic extraction step comprises the following steps: The first segment extraction is performed under acidic conditions at pH 4-5, and the extraction liquid rich in coumarins and caffeic acids is collected; The pH of the system is adjusted to 7.5-8.5 for the second segment extraction, and the extraction liquid rich in flavonoids is collected; The two segment extraction liquids are combined.

[0015] Preferably, in the water-ethanol extraction system, the volume fraction of ethanol is 50%-70%, the extraction temperature is 45-60 DEG C, and the extraction times is 2-4 times.

[0016] In another aspect, the application also provides an application of a leaf surface nutrient closed loop synergist based on allelopathy, wherein the synergist is mixed with a basic leaf surface fertilizer and sprayed on the leaf surface of crops to achieve at least one of the following: enhancing the penetration ability of the leaf to nutrients, enhancing the storage and slow release ability of the leaf cell to nutrients, activating the active absorption mechanism of the crops, promoting the rapid synergistic transformation of the nutrients in the crops, and constructing the nutrient recycling closed loop function between the crops and the soil.

[0017] Preferably, the crops are rice, corn or soybean, and the spraying time includes the late tillering stage, the early jointing stage, the booting stage or the early grain filling stage.

[0018] Compared with the prior art, the application has the following beneficial effects: The application realizes seven closed loop functions from "penetration" to "recycling" through the synergism of multiple plant source allelochemicals, rather than the improvement of a single link. The application effectively breaks through the cuticle barrier of the leaf through the chelation of small molecule coumarin and flavonoids, so that the nutrient absorption efficiency is improved by more than 50%. The application prolongs the holding period of the leaf surface fertilizer to 10-15 days through the strengthening of the storage capacity of the leaf and the activation of the active absorption of the crops, all components are derived from plants, there is no chemical synthetic hormone and no residue, which meets the development direction of green agriculture; the product is a general synergist, which can be compounded with various basic fertilizers, and is suitable for different crops and growth periods. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments will be described below in a clear and complete manner. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments; based on the embodiments, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope.

[0020] The cuticle (fluff) on the surface of the plant leaf is the first difficulty of leaf fertilization. The cuticle is composed of wax and cutin, has strong hydrophobicity and is negatively charged. On the one hand, it prevents water loss, and on the other hand, it blocks the entry of exogenous nutrients into the leaf. When we spray the fertilizer solution containing metal ions on the leaf, the positively charged nutrient ions will be adsorbed by the negatively charged wax layer and are difficult to penetrate into the cell. This explains why the absorption rate of the traditional leaf fertilizer is often low - most of the nutrients remain on the leaf surface and are finally lost with wind and rain.

[0021] To solve this problem, the present application introduces small molecule natural synergistic components (mainly coumarin, flavonoids and caffeic acid and other plant source bio-phenols). These molecules contain multiple polar functional groups, which can form complexes with metal nutrient ions, neutralize their charges. When the nutrients become organic chelated state, the negative surface of the leaf greatly weakens the adsorption effect on it, and the nutrients are more easily penetrated through the cuticle micropores or stomata. This is somewhat similar to the principle of modern chelated micro-fertilizer, but the present application uses plant metabolites as chelating agents, which is more natural and mild.

[0022] The embodiment of the present application provides a leaf nutrition closed loop synergist based on allelopathy synergy, which comprises the following raw materials in percentage by weight: 10%-20% of Sophora alopecuroides seed extract, 20%-30% of citrus young fruit extract, 15%-25% of green coffee bean extract, 5%-15% of licorice root extract, 3%-8% of natural surfactant and the balance of deionized water; The synergist is used with the base foliar fertilizer, so as to construct a leaf nutrition closed loop synergistic system by plant source allelochemicals.

[0023] In a further embodiment of the present application, the coumarin content in the Sophora alopecuroides seed extract is not less than 5%, the flavonoid content in the citrus young fruit extract is not less than 20%, the chlorogenic acid content in the green coffee bean extract is not less than 30%, and the licorice flavone content in the licorice root extract is not less than 15%.

[0024] In a further embodiment of the present application, the natural surfactant is tea saponin.

[0025] In a further embodiment of the present application, when the synergist is compounded with the base foliar fertilizer, the dilution volume ratio is 1: (200-500).

[0026] In a further embodiment of the present application, the base foliar fertilizer comprises one or more of urea, potassium dihydrogen phosphate and trace element fertilizer.

[0027] Further, the embodiment of the present application also provides a preparation method of a leaf nutrition closed loop synergist based on allelopathy synergy, comprising the following steps: Raw material pretreatment: Sophora alopecuroides seeds, citrus young fruits, green coffee beans and licorice roots are sequentially cleaned, dried and crushed to obtain powders of the raw materials; Low-temperature enzymolysis: the raw material powders are subjected to enzymolysis treatment by composite cellulase and pectinase at 40-50 DEG C to obtain a plurality of enzymolysis raw materials; Co-extraction: after enzymatic hydrolysis, multiple raw materials are mixed, a water-ethanol cyclic extraction system is used, directional segmented extraction is carried out by regulating pH value, and an extraction liquid is obtained; Membrane separation and refining: the extraction liquid is filtered and refined by a ceramic membrane system with 100 nm, 50 nm and 10 nm in turn, and a refined liquid is obtained; Vacuum concentration and compounding: the refined liquid is vacuum concentrated to a predetermined concentration under the condition of less than 50 DEG C, and then compounded with natural surfactants and deionized water, and a synergistic agent is obtained after homogenization.

[0028] In a further embodiment of the present embodiment, the co-extraction step comprises the following steps: The first-stage extraction is carried out under acidic conditions at pH 4-5, and an extraction liquid rich in coumarins and caffeic acids is collected; The pH of the system is adjusted to 7.5-8.5 for the second-stage extraction, and an extraction liquid rich in flavonoids is collected; The two-stage extraction liquids are combined.

[0029] In a further embodiment of the present embodiment, in the water-ethanol cyclic extraction system, the volume fraction of ethanol is 50%-70%, the extraction temperature is 45-60 DEG C, and the extraction times is 2-4 times.

[0030] On the other hand, the present embodiment also provides an application of a leaf nutrient closed-loop synergistic agent based on allelopathy, which is mixed with a basic leaf fertilizer and sprayed on the leaf surface of crops to at least one of the following: enhancing the penetration ability of the leaf to nutrients, enhancing the storage and slow-release ability of the leaf cells to nutrients, activating the active absorption mechanism of the crops, promoting the rapid synergistic transformation of nutrients in the crops, and constructing the nutrient recycling closed-loop function between the crops and the soil.

[0031] In a further embodiment of the present embodiment, the crops are rice, corn or soybean; and the spraying time includes the late tillering stage, the early jointing stage, the booting stage or the early grain filling stage.

[0032] It should be noted that: the present embodiment simulates and strengthens the natural "allelopathy" and "endogenous regulation" mechanisms in the plant kingdom, uses a group of scientifically matched plant-derived functional biophenols (coumarins, flavonoids, caffeic acids), and constructs an intelligent, efficient and self-driven leaf nutrient "closed-loop" management system in and outside the crops; the present system upgrades the leaf fertilization from a passive and linear "supplement" behavior to an active and cyclic "regulation" behavior, and realizes the perfect unity of "external force assistance" and "internal force activation".

[0033] Coumarin (from Sophora alopecuroides) has the effect of "penetration pioneer" and "signal simulator". Its small molecular weight and amphiphilic structure (both hydrophilic and lipophilic) enable it to quickly penetrate the hydrophobic wax cuticle of the leaf and open a channel for the carried nutrient ions. Its molecular structure is similar to the substance secreted by the plant itself under nutrient stress (such as iron deficiency). This "molecular disguise" can deliver a mild "stress signal" to the crop, inducing the crop to activate the coping mechanism and open more nutrient absorption channels, changing from "passive reception" to "active search".

[0034] Flavonoids (from citrus and licorice) act as intelligent chelating agents and system dispatchers. The abundant phenolic hydroxyl functional groups can effectively chelate positively charged metal nutrient ions to form electrically neutral organic complexes, thereby shielding the charge repulsion on the leaf surface and allowing the nutrients to pass through the barrier "stealthily". As an important plant endogenous signal molecule, it can up-regulate the expression of multiple nutrient transporter genes, fully activate the absorption and transport system of nitrogen, phosphorus, potassium and trace elements, indirectly affect the metabolism and distribution of endogenous hormones such as auxin and cytokinin, and achieve soft regulation of nutrient flow, prioritizing the supply of reproductive growth and weak parts.

[0035] Caffeic acid (from green coffee beans) is a direct precursor of lignin synthesis. Exogenous supplementation of caffeic acid and the like is equivalent to providing "pre-made building materials" for crops, which can significantly accelerate the thickening and lignification process of cell walls, thereby achieving control of vigorous growth and strengthening of stems; by promoting cell development and cell wall strengthening, the physical space and physiological capacity of mesophyll cells are indirectly increased, allowing the leaf to accommodate and stably store more nutrients, thereby achieving the function of a fertilizer reservoir and avoiding ion toxicity and nutrient waste.

[0036] The action process of the present application is not a simple linear sequence, but a closed-loop system with interlocking and positive feedback. Coumarin and flavonoids work together to first break through the leaf absorption barrier on the physical and chemical levels, allowing nutrients to enter the mesophyll tissue efficiently. Subsequently, substances such as caffeic acid begin to play a role, enhancing the storage capacity of the leaf and temporarily storing nutrients in the vacuole warehouse, forming preliminary buffering and slow-release capacity.

[0037] The signal simulation of coumarin and the gene regulation of flavonoids activate the active absorption mechanism of the crop, and the crop itself changes from passive acceptance to active seeking. At the same time, the influx of nutrients and the stimulation of endogenous signals work together to accelerate the assimilation and conversion of nutrients, rapidly synthesizing dry matter such as protein, cellulose, and lignin, and converting inorganic nutrients into organic yield.

[0038] The activated crop body intelligently optimally allocates nutrients to the most needed places (such as grains, tender tissues) under the regulation of functional biological phenol. The overall improvement of crop health, especially through more developed roots, secretes more organic matter to the soil. These secretions activate rhizosphere microorganisms, building a "plant-soil" nutrient cycle, releasing nutrients that are originally difficult to utilize in the soil for root absorption again.

[0039] The external circulation is connected with the efficient utilization channel inside the crop, so that the whole system is repeated and continuously strengthened. The nutrients supplemented on the leaf surface ultimately bring more soil nutrients to the crop through promoting rhizosphere circulation, forming a growing flywheel that is getting stronger and stronger.

[0040] Example 1 Raw material pretreatment: 10wt% Sophora alopecuroides seeds, 20wt% citrus young fruits, 15wt% green coffee beans, and 5wt% licorice roots were washed, dried, and ground through a 60-mesh sieve, respectively; Low-temperature enzymolysis: the powder of each raw material was mixed, 2% of a composite enzyme (cellulase: pectinase = 1:1) based on the total weight of the raw materials was added in a 45℃ water bath, and enzymolysis was performed for 2 hours; Synergistic extraction: the enzymolysis product was placed in an extraction tank, 5 times the volume of 60% ethanol solution was added, citric acid was used to adjust the pH to 4.5, and extraction was performed at 50℃ for 1.5 hours to collect the first-stage extraction liquid; 3 times the volume of 60% ethanol solution was added to the residue, sodium hydroxide was used to adjust the pH to 8.0, and extraction was performed at the same temperature for 1 hour to collect the second-stage extraction liquid, and the two-stage extraction liquids were combined; Membrane separation refining: the combined extraction liquid was subjected to cross-flow filtration through a ceramic membrane system with pore sizes of 100nm, 50nm, and 10nm, respectively, to remove macromolecular impurities; Vacuum concentration and compounding: the refined liquid was vacuum concentrated at 50℃ and -0.09MPa to 1 / 5 of the original volume to obtain a concentrated paste, then compounded with tea saponin and deionized water according to the formula, and high-speed shearing homogenization was performed for 30 minutes to obtain a brownish translucent liquid enhancer product.

[0041] Example 2 Raw material pretreatment: 15wt% Sophora alopecuroides seeds, 25wt% citrus young fruits, 20wt% green coffee beans, and 10wt% licorice roots were washed, dried, and ground through a 60-mesh sieve, respectively; Low-temperature enzymolysis: the powder of each raw material was mixed, 2% of a composite enzyme (cellulase: pectinase = 1:1) based on the total weight of the raw materials was added in a 45℃ water bath, and enzymolysis was performed for 2 hours; Simultaneous extraction: the enzymatic hydrolysate was placed in an extraction tank, 5 times the volume of 60% ethanol solution was added, the pH was adjusted to 4.5 with citric acid, and extraction was carried out at 50°C for 1.5 hours, and the first-stage extraction liquid was collected; 3 times the volume of 60% ethanol solution was added to the residue, the pH was adjusted to 8.0 with sodium hydroxide, and extraction was carried out at the same temperature for 1 hour, and the second-stage extraction liquid was collected, and the two-stage extraction liquids were combined; Membrane separation refining: the combined extraction liquid was subjected to cross-flow filtration through a ceramic membrane system with pore sizes of 100 nm, 50 nm and 10 nm in sequence to remove macromolecular impurities; Vacuum concentration and compounding: the refined liquid was vacuum concentrated to 1 / 5 of the original volume at 50°C and -0.09 MPa to obtain a concentrated paste, and then compounded with tea saponin and deionized water according to the formula proportion, and high-speed shearing homogenization was carried out for 30 minutes to obtain a brownish translucent liquid synergist product.

[0042] Example 3 Raw material pretreatment: 20wt% Sophora alopecuroides seeds, 30wt% citrus young fruits, 25wt% green coffee beans and 15wt% licorice roots were washed, dried and ground through a 60-mesh screen in sequence; Low-temperature enzymatic hydrolysis: the raw material powders were mixed, 2% of the total weight of the raw materials of a composite enzyme (cellulase: pectinase = 1:1) was added, and enzymatic hydrolysis was carried out in a 45°C water bath for 2 hours; Simultaneous extraction: the enzymatic hydrolysate was placed in an extraction tank, 5 times the volume of 60% ethanol solution was added, the pH was adjusted to 4.5 with citric acid, and extraction was carried out at 50°C for 1.5 hours, and the first-stage extraction liquid was collected; 3 times the volume of 60% ethanol solution was added to the residue, the pH was adjusted to 8.0 with sodium hydroxide, and extraction was carried out at the same temperature for 1 hour, and the second-stage extraction liquid was collected, and the two-stage extraction liquids were combined; Membrane separation refining: the combined extraction liquid was subjected to cross-flow filtration through a ceramic membrane system with pore sizes of 100 nm, 50 nm and 10 nm in sequence to remove macromolecular impurities; Vacuum concentration and compounding: the refined liquid was vacuum concentrated to 1 / 5 of the original volume at 50°C and -0.09 MPa to obtain a concentrated paste, and then compounded with tea saponin and deionized water according to the formula proportion, and high-speed shearing homogenization was carried out for 30 minutes to obtain a brownish translucent liquid synergist product.

[0043] To comprehensively verify the effect of the synergist of the application, examples covering different crops (rice, corn, soybeans), different growth stages, different base fertilizers and different stress conditions were designed for scientific comparison. The comparative examples include: water control (CK1), conventional foliar fertilizer control (CK2), commercially available mainstream synergist control (CK3), and single component control of the application, to prove the synergistic advantage of the composite formula.

[0044] The general experimental method is as follows: test design: random block design, 3 times of each treatment.

[0045] Application method: foliar spraying, 30-45 kg of liquid per mu, uniform spraying of the front and back of the leaf.

[0046] Data collection: using professional instruments (such as chlorophyll meter, photosynthetic instrument, element analyzer, etc.) and measured by professional personnel under the same conditions. The data is expressed as "mean ± standard deviation", and Duncan's new multiple range method is used for significance analysis (p<0.05).

[0047] Experimental example 1 At the booting stage of rice, 4 treatments are set: T1: water; T2: 0.3% potassium dihydrogen phosphate (CK2); T3: 0.3% potassium dihydrogen phosphate + BASF autumn amino acid foliar fertilizer (CK3); T4: 0.3% potassium dihydrogen phosphate + 500 times solution of the product. 7 days after spraying, the flag leaf is taken to determine the total phosphorus and total potassium content.

[0048] The experimental results are shown in Table 1 below: Table 1

[0049] From Table 1 above, it can be seen that the synergist of the application can significantly promote the absorption of phosphorus and potassium nutrients by rice, and the effect is better than that of the commercially available amino acid foliar fertilizer.

[0050] Experimental example 2 At the big trumpet stage of corn, 4 treatments are set: T1: water; T2: 1% urea solution (CK2); T3: 1% urea + 500 times solution of the product. The ear leaf chlorophyll content (SPAD value) is measured on the 3rd, 7th and 14th day after spraying, respectively.

[0051] The experimental results are shown in Table 2 below: Table 2

[0052] From Table 2 above, it can be seen that the conventional urea treatment (T2) has a significant decrease in chlorophyll content at the 7th day, and the fertilizer effect is obviously declining. The treatment of the application (T3) still maintains a high level of SPAD value after 14 days, indicating that it realizes the persistent supply of fertilizer effect by enhancing the nutrient storage capacity of the leaf.

[0053] Experimental example 3 At the initial flowering stage of soybean, five treatments were set: T1: water; T2: 0.1% boric acid + 0.05% ammonium molybdate (CK2); T3: CK2 fertilizer + only bitter bean extract; T4: CK2 fertilizer + only citrus young fruit extract; T5: CK2 fertilizer + 500 times solution of the product. The number of flowers per plant, the number of pods per plant and the grain protein content were determined. The experimental results are shown in Table 3 below: Table 3

[0054] From Table 3 above, it can be seen that the whole component (T5) of the present application is the best in promoting flowering and pod setting and improving quality, and is significantly better than single component treatment (T3, T4), which proves that there is a synergistic effect between various allelochemicals, which activates the absorption and conversion mechanism of crops.

[0055] In summary, the "Zhi Gan Tong-CLC" plant source foliar nutrient closed-loop synergist provided by the present application has significant and stable advantages in improving nutrient absorption efficiency, prolonging fertilizer efficiency, activating the potential of crops, promoting yield formation and quality improvement, enhancing stress resistance, and realizing nutrient recycling, compared with traditional foliar fertilizers and commercially available synergists. Its unique composite plant source allelochemical formula and advanced preparation process jointly constitute its core technical competitiveness, providing a new, efficient and green solution to solve the technical bottlenecks in the current foliar fertilizer field.

[0056] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A closed-loop synergist for foliar nutrition based on allelopathic synergy, characterized in that, The raw materials include the following weight percentages: 10%-20% bitter bean seed extract, 20%-30% citrus immature fruit extract, 15%-25% green coffee bean extract, 5%-15% licorice root extract, 3%-8% natural surfactants and the balance deionized water. The synergist is used in combination with the basic foliar fertilizer for immediate application, so as to construct a closed-loop synergistic system for foliar nutrition through plant-derived allelochemicals.

2. The allelopathic synergistic foliar nutrient closed-loop synergist according to claim 1, characterized in that, The content of coumarin in the bitter bean seed extract is not less than 5%, the content of flavonoids in the citrus immature fruit extract is not less than 20%, the content of chlorogenic acid in the green coffee bean extract is not less than 30%, and the content of glycyrrhizin in the licorice root extract is not less than 15%.

3. The allelopathic synergistic foliar nutrient closed-loop synergist according to claim 1, characterized in that, The natural surfactant is tea saponin.

4. The allelopathic synergistic foliar nutrient closed-loop synergist according to claim 1, characterized in that, When the synergist is compounded with basic foliar fertilizer, its dilution volume ratio is 1:(200-500).

5. The allelopathic synergistic foliar nutrient closed-loop synergist according to claim 1, characterized in that, The basic foliar fertilizer includes one or more of urea, potassium dihydrogen phosphate, and micronutrient fertilizers.

6. A method for preparing a closed-loop foliar nutrient synergist based on allelopathic synergy according to any one of claims 1-5, characterized in that, Includes the following steps: Raw material pretreatment: The bitter bean seeds, young citrus fruits, green coffee beans and licorice root were washed, dried and pulverized in sequence to obtain powders of each raw material; Low-temperature enzymatic hydrolysis: The raw material powders are enzymatically hydrolyzed at 40-50℃ using a combination of cellulase and pectinase to obtain a variety of enzymatically hydrolyzed raw materials; Synergistic extraction: Multiple raw materials after enzymatic hydrolysis are mixed and extracted using a water-ethanol circulating extraction system. The pH value is adjusted to perform targeted segmented extraction to obtain the extract. Membrane separation purification: The extract is filtered and purified sequentially through a ceramic membrane system of 100nm, 50nm and 10nm to obtain a purified solution; Vacuum concentration and compounding: The purified liquid is vacuum concentrated to a predetermined concentration at a temperature below 50°C, and then compounded with natural surfactants and deionized water. After homogenization, the synergist is obtained.

7. The preparation method of the allelopathic synergistic foliar nutrient closed-loop synergist according to claim 6, characterized in that, The synergistic extraction step includes the following steps: The first stage of extraction was carried out under acidic conditions of pH 4-5, and the extract rich in coumarins and caffeic acid was collected. Adjust the pH of the system to 7.5-8.5 for the second stage of extraction, and collect the extract rich in flavonoids; Combine the two extracts.

8. The preparation method of the allelopathic synergistic foliar nutrient closed-loop synergist according to claim 6, characterized in that, In the water-ethanol circulating extraction system, the volume fraction of ethanol is 50%-70%, the extraction temperature is 45-60℃, and the number of extractions is 2-4.

9. The application of a foliar nutrient closed-loop synergist based on allelopathic synergy according to any one of claims 1-5, characterized in that, The synergist is mixed with the basic foliar fertilizer and sprayed onto the crop leaves to achieve at least one of the following: enhancing the leaves' ability to penetrate nutrients, enhancing the leaf cells' ability to store and slowly release nutrients, activating the crop's active absorption mechanism, promoting the rapid and synergistic transformation of nutrients in the crop, and constructing a closed-loop function for nutrient recycling between the crop and the soil.

10. The application of the allelopathic synergistic foliar nutrient closed-loop synergist according to claim 9, characterized in that, The crop is rice, corn, or soybean; the application time includes the late tillering stage, early jointing stage, booting stage, or early grain filling stage.

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