Enzymatically stabilized glutathione water-soluble fertilizer and preparation method thereof

Abstract

This invention belongs to the field of agricultural fertilizer technology, specifically relating to an enzyme-stabilized glutathione water-soluble fertilizer and its preparation method. It comprises a functional microcapsule component and an NPK water-soluble salt system; the functional microcapsule component consists of a microcapsule core and a microcapsule wall material. This invention utilizes a glutathione reductase combined with a coenzyme regeneration system to directionally convert glutathione in the raw material into a reduced state; impurities are removed through enzyme inactivation, ultrafiltration, and fine filtration to suppress side reactions; under a weakly acidic environment, sodium gluconate and buffer salts are used to regulate the ionic environment, enabling zinc and manganese ions to form reversible coordination complexes with glutathione, possessing both storage protection and release utilization properties; sodium alginate-calcium gel combined with chitosan secondary encapsulation constructs a physical barrier, enhancing salt tolerance and shock resistance; low-temperature drying and low-shear granulation ensure the integrity of the microcapsules, resulting in a final product that combines storage stability and application dispersibility, achieving a synergistic effect of glutathione with zinc and manganese.

Description

Technical Field

[0001] This invention belongs to the field of agricultural fertilizer technology, specifically relating to an enzyme-stabilized glutathione water-soluble fertilizer and its preparation method. Background Technology

[0002] Water-soluble fertilizers, due to their rapid dissolution in water and compatibility with modern fertigation methods such as fertigation, drip irrigation, sprinkler irrigation, and foliar spraying, offer advantages such as high nutrient utilization, convenient application, and easy precise control, making them a commonly used fertilizer form in facility agriculture and large-scale planting. Meanwhile, as crops increasingly demand higher levels of stress resistance, improved quality, and stable yields, traditional water-soluble fertilizers primarily composed of N, P, and K are gradually evolving towards a composite function combining nutrient supply and biostimulation. This involves introducing functional active ingredients with antioxidant, stress-resistance, and growth-promoting effects into the basic fertilizer system to enhance crop physiological stability under conditions such as salt stress, drought, high temperature, low temperature, and disease induction.

[0003] Glutathione (GSH), a natural tripeptide compound containing a thiol group, possesses important antioxidant and reducing buffering functions. In biological systems, it participates in the scavenging of reactive oxygen species, maintaining cellular redox balance, and promoting related stress-resistance metabolic processes. Therefore, introducing glutathione into water-soluble fertilizer systems as a functional component has the potential to enhance crop stress resistance and improve physiological conditions. However, the current technology of directly adding glutathione to water-soluble fertilizer systems often faces the following problems: First, glutathione molecules contain active thiol groups, which are easily oxidized and transformed in solution by dissolved oxygen, light, and trace metal ions (especially copper and iron), leading to a decrease in the proportion of reduced form and a reduction in effectiveness, resulting in poor product shelf-life stability and insufficient batch-to-batch consistency. Second, water-soluble fertilizer systems usually have high ionic strength and complex salt backgrounds, and glutathione may complex, coordinate, or compete with trace element salts, buffer salts, or other adjuvants, causing changes in the morphology of active ingredients and even phenomena such as turbidity and precipitation, affecting the product appearance and compatibility with filtration / drip irrigation at the application end. Third, even if a certain degree of stability is achieved during the preparation stage, traditional mixed products may still experience rapid oxidation or consumption of active ingredients after application and dilution due to changes in environmental pH and ionic composition, making it difficult to achieve stable, controllable functional release and sustained effects.

[0004] To address the aforementioned issues, existing solutions have attempted to improve stability using chelating agents, antioxidants, encapsulation, or repackaging. However, these solutions generally suffer from the following shortcomings: for example, strong chelating agents may reduce the bioavailability of the target trace elements or introduce compatibility risks in the formulation; simple physical encapsulation, without pre-regulation of the chemical form of glutathione, is prone to inconsistencies in the form before and after encapsulation, leading to fluctuations in efficacy; and, without targeted restriction and removal of pro-oxidative trace metals, it remains difficult to fundamentally solve the problem of oxidative inactivation of glutathione in high-salt-water fertilizer systems. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide an enzyme-catalyzed stable glutathione water-soluble fertilizer and its preparation method. This invention solves the problem that glutathione, due to the presence of highly reactive thiol groups in its molecular structure, is prone to oxidative transformation and activity decay in complex water-soluble fertilizer systems with strong electrolytes, high ionic strength, dissolved oxygen, and light exposure, especially under the catalysis of trace transition metal ions such as copper and iron. Furthermore, in high-salt environments, its chemical form and solution stability fluctuate due to coordination competition and changes in ionic strength, easily leading to turbidity, flocculation, or salting out and producing filterable residues. This results in poor product storage stability and increases the risk of clogging in drip irrigation systems, making it difficult for antioxidant active ingredients to achieve stable, controllable release and sustained stress-relieving and synergistic effects in the rhizosphere or leaves of crops.

[0006] The technical effects described in this invention are achieved through the following technical solution: an enzyme-stabilized glutathione water-soluble fertilizer, comprising a functional microcapsule component and an NPK water-soluble salt system; the functional microcapsule component comprises 10-20 parts by mass, and the NPK water-soluble salt system comprises 80-90 parts by mass. Preferably, the functional microcapsule component is composed of a microcapsule core and a microcapsule wall material, wherein, by mass parts, the microcapsule core is 40-55 parts and the microcapsule wall material is 45-60 parts; Preferably, the microcapsule core comprises the following raw materials in parts by weight: 16-22 parts reduced glutathione, 1.2-2.5 parts zinc source, 0.8-1.8 parts manganese source, 0.2-0.7 parts sodium gluconate, 0.8-2 parts buffer stabilizer salt, and 21-26 parts protectant; Preferably, the zinc source is any one of zinc sulfate, zinc nitrate, zinc acetate, and zinc gluconate; Preferably, the manganese source is any one of manganese sulfate, manganese nitrate, manganese acetate, and manganese gluconate; Preferably, the amount of zinc source used is calculated based on Zn element; the amount of manganese source used is calculated based on Mn element. Preferably, the buffer stabilizing salt is any one of sodium citrate, potassium citrate, sodium acetate, and phosphate; Preferably, the protective agent is any one of trehalose, betaine, glycerol, and sorbitol; Preferably, the microcapsule wall material comprises the following raw materials in parts by weight: 26-33 parts sodium alginate, 10-15 parts chitosan, 8-10 parts calcium crosslinking agent, and 1-2 parts regulator; Preferably, the calcium crosslinking agent is either calcium chloride or calcium lactate; Preferably, the regulator is any one of pectin, xanthan gum, and hydroxypropyl methylcellulose; Preferably, the mass ratio of N, P2O5, and K2O in the NPK water-soluble salt system is 20:20:20 or 15:5:30 based on nutrients; Preferably, another aspect of the present invention provides a method for preparing an enzyme-stabilized glutathione water-soluble fertilizer, specifically comprising the following steps: S1: Place deionized water in a reaction vessel and control the temperature at 25-30℃. Add reduced glutathione under light-protected conditions to adjust the total glutathione concentration in the solution to 60-100 g / L. Adjust the pH of the solution to 6.8-7.2 using a sodium phosphate buffer system. Add glutathione reductase and coenzyme sequentially under stirring at 300-500 rpm, and then add the coenzyme regeneration system, i.e., glucose and glucose dehydrogenase. Continue stirring and reacting under light-protected conditions for 60-180 min to obtain a highly reduced glutathione shaping solution. S2: The highly reduced glutathione shaping solution obtained in S1 is heated to 55-65℃ and kept at that temperature for 10-30 minutes to inactivate the enzyme. After cooling to room temperature, it is ultrafiltered using an ultrafiltration membrane with a molecular weight cutoff of 10kDa to remove protein and enzyme residues. Then it is filtered through a 0.22μm filter membrane to obtain the glutathione shaping clear solution. S3: Adjust the temperature of the glutathione-based clarifying solution obtained in S2 to 15–30°C, adjust the pH of the solution to 5.6–6.4 using sodium hydroxide, add sodium gluconate and a buffer stabilizer while stirring, and continue stirring until the solution is completely dissolved; then add zinc source solution dropwise, controlling the pH at 5.8–6.2 during the dropwise addition; after the zinc source is added, add manganese source solution dropwise, continue stirring for 30–60 min, and finally add a protective agent and stir until the solution is clear to obtain GSH-Zn / Mn pre-coordinated core solution; S4: Weigh each raw material component according to the stated mass fractions, prepare a 1-2.5 wt% sodium alginate aqueous solution, add a regulator, stir until completely dissolved, and let stand to remove bubbles; separately prepare a 0.3-1 wt% chitosan aqueous solution and adjust the pH to 5-6; prepare a 1-3 wt% calcium crosslinking agent aqueous solution; S5: The pre-coordinated core fluid obtained in S3 is mixed with the sodium alginate aqueous solution in S4 and stirred evenly under low shear to obtain a shaped mixture. Then, the shaped mixture is added to the calcium crosslinking agent aqueous solution in S4 at a flow rate of 2-5 mL / min through a dropper with a pore size of 0.3-0.5 mm to form beads, so that the wet bead size is 0.6-1 mm. Crosslinking is carried out for 5-15 min. After crosslinking is completed, the microbeads are collected by filtration, washed with deionized water, and then placed in the chitosan aqueous solution in S4 for 5-15 min for secondary coating. After washing with deionized water again, wet microcapsules are obtained. S6: The wet microcapsules obtained in S5 are vacuum dried at 40-55℃ until the moisture content is ≤5%, and then passed through a 40-mesh sieve to obtain powder. The microcapsule powder and NPK water-soluble salt system are then sheared and mixed at a low speed of 30-60 rpm, and granulated by drum granulation. The material temperature is ≤60℃ and the target particle size is 0.8-1.6 mm. Subsequently, the material is dried with hot air at 45-60℃ until the moisture content is ≤2% to obtain water-soluble fertilizer. Preferably, in step S1, the coenzyme is NADPH, and its dosage is 0.02-0.05 mmol / L; Preferably, in step S1, the specific activity of the glutathione reductase is ≥200 U / mg, and its dosage is 1000-3000 U / L based on the enzyme activity in the reaction system, to drive glutathione to migrate towards a highly reduced state; the specific activity of the glucose dehydrogenase is ≥150 U / mg, and its dosage is 200-1000 U / L based on the enzyme activity in the reaction system; the glucose concentration is 10-30 g / L, and coenzyme regeneration is provided during the reaction to ensure that the reaction endpoint is reached within 60-180 min; deoxygenation treatment is performed immediately after the reaction in step S1, with nitrogen bubbling for 5-15 min; Preferably, in step S1, the reaction endpoint is determined by enzymatic or chromatographic methods, and the reaction is stopped when either of the following conditions is met: GSH accounts for ≥85% of total glutathione or GSH:GSSG ≥6:1.

[0007] The beneficial effects of this invention are as follows: This invention introduces glutathione reductase at the front end of the process, along with a coenzyme and coenzyme regeneration system, to drive the glutathione system to migrate stably towards a highly reduced state, achieving pre-forming and locking of the effective chemical form. This enzymatic molecular state regulation can transform potentially oxidized components or unfavorable sulfide forms in the raw materials into the target reduced state, making the effective form of the system more consistent. This reduces activity fluctuations caused by batch-to-batch differences in raw materials, providing a uniform and controllable chemical basis for subsequent gentle metal ion coordination and microencapsulation.

[0008] Furthermore, this invention performs enzyme inactivation treatment on the shaping solution and combines ultrafiltration to remove proteins with microfiltration to construct a clean liquid system with high chemical stability and low impurities. This significantly reduces the risk of aggregation, adsorption, or non-specific reactions induced by enzyme proteins and macromolecular impurities in a high-salt background, and reduces complex side reactions and uncertain changes that may occur during storage. At the same time, by removing colloids and suspended particles, it improves the reproducibility of subsequent microcapsule formation and the clarity of the finished solution, thereby improving the physical permeability and stability of the product at application terminals such as filtration, drip irrigation, and fertigation.

[0009] Under weakly acidic conditions, this invention utilizes sodium gluconate and buffer / stabilizing salts to construct a stable ionic environment, and employs a sequential dropwise addition strategy to form a mild coordination complex with zinc and manganese ions and glutathione. This complex, at the molecular level, can provide a certain shielding and slow-release effect on the highly reactive microenvironment surrounding thiol groups, reducing premature oxidation consumption induced by dissolved oxygen and trace pro-oxidative factors. Simultaneously, due to the reversibility of the coordination structure, it can gradually dissociate and release during application dilution and changes in the rhizosphere / foliar microenvironment, giving the active components both protective properties during storage and usability during use. Furthermore, by limiting the content of trace transition metals such as Cu and Fe in the finished product, the triggering probability of metal-catalyzed oxidation chain reactions is further reduced, enhancing the stability of the system from the source. Furthermore, the introduction of protective agents such as trehalose, betaine, and glycerol / sorbitol into the core stabilizes glutathione and its coordination complex by reducing local water activity, enhancing hydrogen bonding, and increasing glass transition tendency. The inhibitory effect of buffer / stabilizing salts on acid-base drift helps maintain the coordination form and reactive window, preventing morphological mutations and stability decreases due to environmental fluctuations. The mild complexing effect of sodium gluconate on trace harmful metal ions, combined with the aforementioned microenvironment regulation mechanisms, creates a dual stabilization pathway where both chemical form and microenvironment are controllable.

[0010] At the structural level, this invention employs an ionogel network formed by sodium alginate and calcium ions to spatially confine the core, and utilizes the cationic properties of chitosan for secondary encapsulation, constructing a dense composite wall layer. This forms a physical barrier against strong electrolyte backgrounds and external dissolved oxygen, enhancing the microcapsules' resistance to shock and salting out in high-salt systems. Combined with a regulator to control gel pore size and viscoelasticity, release kinetics are optimized, reducing oxidative loss caused by initial high-concentration exposure, resulting in a more stable and sustained release of active ingredients. Finally, this invention uses low-temperature drying to control moisture within a suitable range, reducing the risk of thermal degradation caused by high temperatures. During the compounding and granulation process with the NPK water-soluble salt system, low-shear mixing and gentle molding processes are employed to reduce mechanical stress on the microcapsule structure, thereby ensuring uniform dispersion and structural integrity of the microcapsules within the high-salt macronutrient fertilizer framework. The resulting water-soluble fertilizer combines long-term storage stability, good water solubility and dispersibility with application-friendly properties. It can more stably exert the antioxidant and stress-resistance synergistic effects of glutathione in the rhizosphere or leaf surface of crops, and form a synergistic enhancement effect with components such as zinc and manganese. Attached Figure Description

[0011] Figure 1 The graph shows the percentage change of reduced glutathione in total glutathione in the water-soluble fertilizers of Examples 1 and Comparative Examples 1-4 during storage tests; (A) shows the results of storage at room temperature of 25℃, and (B) shows the results of accelerated storage at 40℃. Figure 2 The graph shows the turbidity changes of water-soluble fertilizers in Example 1 and Comparative Examples 1-4 during storage tests; (A) shows the results of storage at room temperature (25°C), and (B) shows the results of accelerated storage at 40°C. Figure 3 The figures show the pH changes of water-soluble fertilizers from Examples 1 and Comparative Examples 1-4 after reconstitution during storage tests; (A) shows the results of storage at room temperature (25℃), and (B) shows the results of accelerated storage at 40℃. Figure 4 The graph shows the changes in flow retention rate of water-soluble fertilizers in Example 1 and Comparative Examples 1-4 in the irrigation simulation test in deionized water medium. Figure 5 The graph shows the changes in flow retention rate of water-soluble fertilizers in hard water media during irrigation simulation tests in Examples 1 and Comparative Examples 1-4. Detailed Implementation

[0012] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Unless otherwise specified, the raw materials involved in the present invention are all purchased through conventional commercial channels. Experimental methods without specific conditions are conventional methods and conditions well known in the art, or according to the conditions recommended by the instrument manufacturer.

[0013] Example 1: An enzyme-stabilized glutathione water-soluble fertilizer, comprising a functional microcapsule component and an NPK water-soluble salt system; the functional microcapsule component comprises 15 parts by mass, and the NPK water-soluble salt system comprises 85 parts by mass. The functional microcapsule component is composed of 48 parts by weight of microcapsule core and 52 parts by weight of microcapsule wall material; The microcapsule core comprises the following raw materials in parts by weight: 19 parts reduced glutathione, 1.8 parts zinc source, 1.3 parts manganese source, 0.5 parts sodium gluconate, 1.4 parts buffer stabilizer salt and 24 parts protectant. The amount of zinc source used is calculated based on Zn element; the amount of manganese source used is calculated based on Mn element; The microcapsule wall material comprises the following raw materials in parts by weight: 30 parts sodium alginate, 12 parts chitosan, 8 parts calcium crosslinking agent and 2 parts regulator; The mass ratio of N, P2O5, and K2O in the NPK water-soluble salt system is 20:20:20 (based on nutrient content). The preparation method of the enzyme-stabilized glutathione water-soluble fertilizer specifically includes the following steps: S1: Place deionized water in a reaction vessel and control the temperature at 27℃. Add reduced glutathione under light-protected conditions to adjust the total glutathione concentration in the solution to 80 g / L. Adjust the pH of the solution to 7 using a sodium phosphate buffer system. Add glutathione reductase and 0.04 mmol / L coenzyme NADPH sequentially under stirring at 400 rpm, and then add the coenzyme regeneration system, i.e., glucose and glucose dehydrogenase. Continue stirring and reacting under light-protected conditions for 120 min, followed by nitrogen bubbling deoxygenation treatment for 10 min to obtain a highly reduced glutathione shaping solution. The specific activity of the glutathione reductase is preferably ≥200 U / mg, and its dosage is 2000 U / L based on the enzyme activity in the reaction system, to drive glutathione to migrate towards a highly reduced state; the specific activity of the glucose dehydrogenase is preferably ≥150 U / mg, and its dosage is 600 U / L based on the enzyme activity in the reaction system; the glucose concentration is 20 g / L, and coenzyme regeneration is provided during the reaction to ensure that the reaction endpoint is reached within 120 min; the GSH:GSSG ratio is determined to be ≥6:1; S2: The highly reduced glutathione shaping solution obtained in S1 was heated to 60℃ and kept at that temperature for 20 min to inactivate the enzyme. After cooling to room temperature, it was ultrafiltered using an ultrafiltration membrane with a molecular weight cutoff of 10 kDa to remove protein and enzyme residues. Then it was filtered through a 0.22 μm filter membrane to obtain the glutathione shaping clear solution. S3: Adjust the temperature of the glutathione-based clarifying solution obtained in S2 to 25℃, adjust the pH of the solution to 6 using sodium hydroxide, add sodium gluconate and sodium citrate while stirring, and continue stirring until dissolved evenly; then add zinc nitrate solution dropwise, controlling the pH at 6 during the dropwise addition; after the zinc nitrate addition is complete, add manganese nitrate solution dropwise, continue stirring for 50 min, and finally add trehalose and stir until the solution is clear to obtain the GSH-Zn / Mn pre-coordinated core solution; S4: Weigh each raw material component according to the stated mass fractions, prepare a 2wt% sodium alginate aqueous solution, add xanthan gum, stir until completely dissolved, and let stand to remove bubbles; separately prepare a 0.6wt% chitosan aqueous solution and adjust the pH to 5.5; prepare a 2wt% calcium chloride aqueous solution; S5: The pre-coordinated core fluid obtained in S3 is mixed with the sodium alginate aqueous solution in S4 and stirred evenly under low shear to obtain a shaped mixture. Then, the shaped mixture is added to the calcium chloride aqueous solution in S4 at a flow rate of 3 mL / min through a dropper with a pore size of 0.4 mm to form beads, so that the wet bead size is 0.8 mm. After cross-linking for 10 min, the microbeads are collected by filtration, washed with deionized water, and then placed in the chitosan aqueous solution in S4 for 10 min for secondary coating. After washing with deionized water again, wet microcapsules are obtained. S6: The wet microcapsules obtained in S5 are vacuum dried at 50℃ until the moisture content is ≤5%, and then passed through a 40-mesh sieve to obtain powder. The microcapsule powder and NPK water-soluble salt system are then sheared and mixed at 50rpm, granulated by drum granulation, with the material temperature ≤60℃ and the target particle size 1.2mm. Subsequently, the powder is dried with hot air at 55℃ until the moisture content is ≤2% to obtain water-soluble fertilizer. The total Cu content in the finished water-soluble fertilizer is ≤5ppm, and the total Fe content is ≤50ppm.

[0014] Example 2: An enzyme-stabilized glutathione water-soluble fertilizer, comprising a functional microcapsule component and an NPK water-soluble salt system; the functional microcapsule component comprises 10 parts by mass, and the NPK water-soluble salt system comprises 90 parts by mass. The functional microcapsule component is composed of 40 parts by weight of microcapsule core and 60 parts by weight of microcapsule wall material; The core of the microcapsule comprises the following raw materials in parts by weight: 16 parts reduced glutathione, 1.2 parts zinc source, 0.8 parts manganese source, 0.2 parts sodium gluconate, 0.8 parts buffer stabilizer salt and 21 parts protectant. The amount of zinc source used is calculated based on Zn element; the amount of manganese source used is calculated based on Mn element; The microcapsule wall material comprises the following raw materials in parts by weight: 33 parts sodium alginate, 15 parts chitosan, 10 parts calcium crosslinking agent and 2 parts regulator; The mass ratio of N, P2O5, and K2O in the NPK water-soluble salt system is 15:5:30 (based on nutrient content). The preparation method of the enzyme-stabilized glutathione water-soluble fertilizer specifically includes the following steps: S1: Place deionized water in a reaction vessel and control the temperature at 25℃. Add reduced glutathione under light-protected conditions to adjust the total glutathione concentration in the solution to 60 g / L. Adjust the pH of the solution to 7.2 using a sodium phosphate buffer system. Add glutathione reductase and 0.02 mmol / L coenzyme NADPH sequentially under stirring at 300 rpm, and add the coenzyme regeneration system, i.e., glucose and glucose dehydrogenase. Continue stirring and reacting under light-protected conditions for 60 min, and then treat with nitrogen bubbling deoxygenation for 5 min to obtain a highly reduced glutathione shaping solution. The specific activity of the glutathione reductase is preferably ≥200 U / mg, and its dosage is 1000 U / L based on the enzyme activity in the reaction system, to drive glutathione to migrate towards a highly reduced state; the specific activity of the glucose dehydrogenase is preferably ≥150 U / mg, and its dosage is 200 U / L based on the enzyme activity in the reaction system; the glucose concentration is 10 g / L, and coenzyme regeneration is provided during the reaction to ensure that the reaction endpoint is reached within 60 min; the reaction endpoint is determined by enzymatic and chromatographic methods, and the determination shows that GSH accounts for ≥85% of total glutathione; S2: The highly reduced glutathione shaping solution obtained in S1 was heated to 55℃ and kept at that temperature for 30 min to inactivate the enzyme. After cooling to room temperature, it was ultrafiltered using an ultrafiltration membrane with a molecular weight cutoff of 10 kDa to remove protein and enzyme residues. Then it was filtered through a 0.22 μm filter membrane to obtain the glutathione shaping clear solution. S3: Adjust the temperature of the glutathione-based clarifying solution obtained in S2 to 15℃, adjust the pH of the solution to 6.4 using sodium hydroxide, add sodium gluconate and potassium citrate while stirring, and continue stirring to dissolve evenly; then add zinc sulfate solution dropwise, controlling the pH at 6.2 during the dropwise addition; after the zinc sulfate addition is complete, add manganese sulfate solution dropwise, continue stirring for 30 minutes, and finally add sorbitol and stir until the solution is clear to obtain the GSH-Zn / Mn pre-coordinated core solution; S4: Weigh each raw material component according to the stated mass fractions, prepare a 1wt% sodium alginate aqueous solution, add pectin, stir until completely dissolved, and let stand to remove bubbles; separately prepare a 0.3wt% chitosan aqueous solution and adjust the pH to 6; prepare a 1wt% calcium lactate aqueous solution; S5: The pre-coordinated core fluid obtained in S3 is mixed with the sodium alginate aqueous solution in S4 and stirred evenly under low shear to obtain a shaped mixture. Then, the shaped mixture is added to the calcium lactate aqueous solution in S4 at a flow rate of 2 mL / min through a dropper with a pore size of 0.3 mm to form beads, so that the wet bead size is 0.6 mm. After cross-linking for 5 min, the microbeads are collected by filtration, washed with deionized water, and then placed in the chitosan aqueous solution in S4 for 5 min for secondary coating. After washing with deionized water again, wet microcapsules are obtained. S6: The wet microcapsules obtained in S5 are vacuum dried at 40℃ until the moisture content is ≤5%, and then passed through a 40-mesh sieve to obtain powder. The microcapsule powder and NPK water-soluble salt system are then sheared and mixed at 30 rpm, granulated by drum granulation, with a material temperature ≤60℃ and a target particle size of 0.8 mm. Subsequently, the powder is dried with hot air at 45℃ until the moisture content is ≤2% to obtain water-soluble fertilizer. The total Cu content in the finished water-soluble fertilizer is ≤5ppm, and the total Fe content is ≤50ppm.

[0015] Example 3: An enzyme-stabilized glutathione water-soluble fertilizer, comprising a functional microcapsule component and an NPK water-soluble salt system; the functional microcapsule component comprises 20 parts by mass, and the NPK water-soluble salt system comprises 80 parts by mass. The functional microcapsule component is composed of 55 parts by weight of microcapsule core and 45 parts by weight of microcapsule wall material; The core of the microcapsule comprises the following raw materials in parts by weight: 22 parts reduced glutathione, 2.5 parts zinc source, 1.8 parts manganese source, 0.7 parts sodium gluconate, 2 parts buffer stabilizer salt and 26 parts protectant. The amount of zinc source used is calculated based on Zn element; the amount of manganese source used is calculated based on Mn element; The microcapsule wall material comprises the following raw materials in parts by weight: 26 parts sodium alginate, 10 parts chitosan, 8 parts calcium crosslinking agent and 1 part regulator; The mass ratio of N, P2O5, and K2O in the NPK water-soluble salt system is 20:20:20 (based on nutrient content). The preparation method of the enzyme-stabilized glutathione water-soluble fertilizer specifically includes the following steps: S1: Place deionized water in a reaction vessel and control the temperature at 30℃. Add reduced glutathione under light-protected conditions to adjust the total glutathione concentration in the solution to 100 g / L. Adjust the pH of the solution to 6.8 using a sodium phosphate buffer system. Add glutathione reductase and 0.05 mmol / L coenzyme NADPH sequentially under stirring at 300–500 rpm, and then add the coenzyme regeneration system, i.e., glucose and glucose dehydrogenase. Continue stirring and reacting under light-protected conditions for 180 min, followed by nitrogen bubbling deoxygenation treatment for 15 min to obtain a highly reduced glutathione shaping solution. The specific activity of the glutathione reductase is preferably ≥200 U / mg, and its dosage is 3000 U / L based on the enzyme activity in the reaction system, to drive glutathione to migrate towards a highly reduced state; the specific activity of the glucose dehydrogenase is preferably ≥150 U / mg, and its dosage is 1000 U / L based on the enzyme activity in the reaction system; the glucose concentration is 30 g / L, and coenzyme regeneration is provided during the reaction to ensure that the reaction endpoint is reached within 180 min; the reaction endpoint is determined by enzymatic and chromatographic methods, and the GSH:GSSG ratio is ≥6:1. S2: The highly reduced glutathione shaping solution obtained in S1 was heated to 65℃ and kept at that temperature for 10 min to inactivate the enzyme. After cooling to room temperature, it was ultrafiltered using an ultrafiltration membrane with a molecular weight cutoff of 10 kDa to remove protein and enzyme residues. Then it was filtered through a 0.22 μm filter membrane to obtain the glutathione shaping clear solution. S3: Adjust the temperature of the glutathione-based clarifying solution obtained in S2 to 30℃, adjust the pH of the solution to 5.6 using sodium hydroxide, add sodium gluconate and sodium acetate while stirring, and continue stirring until dissolved evenly; then add zinc acetate solution dropwise, controlling the pH at 5.8 during the dropwise addition; after the zinc acetate addition is complete, add manganese acetate solution dropwise, continue stirring for 60 min, and finally add betaine and stir until the solution is clear to obtain the GSH-Zn / Mn pre-coordinated core solution; S4: Weigh each raw material component according to the stated mass fractions, prepare a 2.5wt% sodium alginate aqueous solution, add hydroxypropyl methylcellulose, stir until completely dissolved, and let stand to remove bubbles; separately prepare a 1wt% chitosan aqueous solution and adjust the pH to 5; prepare a 3wt% calcium chloride aqueous solution; S5: The pre-coordinated core fluid obtained in S3 is mixed with the sodium alginate aqueous solution in S4 and stirred evenly under low shear to obtain a shaped mixture. Then, the shaped mixture is added to the calcium chloride aqueous solution in S4 at a flow rate of 5 mL / min through a dropper with a pore size of 0.5 mm to form beads, so that the wet beads have a particle size of 1 mm. After cross-linking for 15 min, the microbeads are collected by filtration, washed with deionized water, and then placed in the chitosan aqueous solution in S4 for 15 min for secondary coating. After washing with deionized water again, wet microcapsules are obtained. S6: The wet microcapsules obtained in S5 are vacuum dried at 55℃ until the moisture content is ≤5%, and then passed through a 40-mesh sieve to obtain powder. The microcapsule powder and NPK water-soluble salt system are then sheared and mixed at 60rpm, granulated by drum granulation, with the material temperature ≤60℃ and the target particle size of 1.6mm. Subsequently, the powder is dried with hot air at 60℃ until the moisture content is ≤2% to obtain water-soluble fertilizer. The total Cu content in the finished water-soluble fertilizer is ≤5ppm, and the total Fe content is ≤50ppm.

[0016] Comparative Example 1: In the preparation of Comparative Example 1, glutathione reductase, coenzyme, glucose dehydrogenase and glucose of the coenzyme regeneration system were not added; that is, the reduced glutathione was directly dissolved and the pH was adjusted before entering the step S2 process; the other raw materials and operating parameters were the same as those in Example 1.

[0017] Comparative Example 2: Comparative Example 2 did not undergo 10kDa ultrafiltration to remove protein, but still underwent 0.22μm filtration; the remaining raw materials and operating parameters remained the same as in Example 1.

[0018] Comparative Example 3: In Comparative Example 3, zinc and manganese sources were directly added to the NPK water-soluble salt system for mixing, and zinc and manganese sources were not added to the microcapsule core; the remaining raw materials and operating parameters were the same as in Example 1.

[0019] Comparative Example 4: After completing the sodium alginate and calcium crosslinking to form beads and the washing steps, Comparative Example 4 did not perform secondary chitosan coating; the remaining raw materials and operating parameters were the same as in Example 1.

[0020] Physicochemical index testing: Referring to GB / T 17419-2018, NY / T 1973-2021 and GB / T 10516-2012 standards, the moisture content, pH value, water insoluble matter (100 mesh sieve) and particle hardness of the water-soluble fertilizers in Examples 1-3 and Comparative Examples 1-4 were measured. The measurement results are shown in Table 1 below.

[0021] Table 1. Physicochemical property test results of the water-soluble fertilizers in the examples and comparative examples

[0022] Based on the results in Table 1, the examples are significantly superior to the comparative examples overall. The synergistic effect of the examples across the entire process allows the functional components to enter the microcapsule core in a more controllable chemical form and into the high-salt NPK framework with a denser and more uniform composite wall layer. This reduces the risk of aggregation / flocculation of macromolecular impurities, colloidal particles, and wall material fragments under high ionic strength from the source, while also improving the integrity and wear resistance of the particle structure. Comparative Example 1 lacks the pre-shaping and locking of the effective form of glutathione in S1, making it more prone to insufficient reduction ratio and morphological consistency in the system. In subsequent high-salt environments and processing, it is more likely to induce local morphological fluctuations and amplify system instability. Therefore, compared with the examples, it exhibits higher residue levels and worse physicochemical consistency. Although Comparative Example 2 still underwent 0.22μm filtration, protein / enzyme residues and some macromolecular impurities were not effectively removed. Under high-salt conditions, these impurities were more prone to aggregation, adsorption, and non-specific entanglement, resulting in a higher proportion of retainable insoluble matter during resolution of the finished product. This also made the system more hygroscopic and caused greater fluctuations in physicochemical properties. This is the core reason why its water-insoluble matter and moisture content were significantly inferior to the examples. Comparative Example 3 deprived Zn / Mn of the opportunity to form a mild pre-coordinated complex with GSH under a weakly acidic window. The core lacked "reversible coordination chemical shielding / slow-release synergy," making it more susceptible to local instability and morphological fluctuations caused by complexation competition under high ionic strength conditions. Therefore, compared to the examples, its resolution residue was higher, and its overall physicochemical performance was inferior. Comparative Example 4 lacked the densification and salt shock resistance provided by the alginate-chitosan composite wall layer. During high-salt resolution, the cross-linked gel was more prone to wall material fragmentation, local flocculation and agglomeration, and reduced particle mechanical integrity, resulting in higher insoluble residue and significantly reduced particle hardness.

[0023] Storage stability test: The water-soluble fertilizers of Example 1 and Comparative Examples 1-4 were stored at room temperature (25℃) and accelerated temperature (40℃), respectively, for a test period of 60 days. Samples were taken and analyzed on days 0, 7, 14, 30, and 60. The test indicators were: percentage of reduced glutathione (GSH) to total glutathione (%); turbidity (NTU); and pH after reconstitution. The results are as follows: Figure 1-3 As shown.

[0024] based on Figure 1-3Results analysis showed that Example 1 was superior to all comparative examples. Based on the full-chain synergy of Example 1, it exhibited the highest GSH retention rate, the slowest turbidity increase, and the smallest pH drift at both 25℃ and 40℃. Comparative Example 1 showed the most significant degradation. The lack of the S1 step for pre-locking of the effective form resulted in a higher proportion of oxidized template in the system, accelerating the induced oxidation of thiol groups by dissolved oxygen and trace metal ions. With the large-scale degradation of GSH, acidic oxidation byproducts accumulated continuously, leading to a significant decrease in pH and inducing micro-precipitation, causing a continuous increase in turbidity. Comparative Example 2 showed significant turbidity and GSH decay: although enzymatic shaping was involved, protein / enzyme residues and macromolecular impurities were not effectively removed. Under high-salt environments and accelerated heating conditions, aggregation, adsorption, and non-specific reactions were more likely to occur, resulting in the highest turbidity, rapid GSH decay, and greater pH drift. In Comparative Example 3, Zn / Mn does not enter the core and does not form a reversible, mild complex with GSH, thus losing the protection and sustained-release-utilization synergy of the thiol microenvironment. This results in greater morphological fluctuations during storage and reconstitution, leading to inferior GSH retention and turbidity control compared to the examples. Comparative Example 4 exhibits the most significant increase in turbidity and a larger pH drift: the lack of chitosan densification and salt shock resistance makes it easier for wall material fragments or flocculation to form during reconstitution / storage, resulting in a significant increase in turbidity. Insufficient structural protection also makes the core more susceptible to exposure to pro-oxidative environments, thereby accelerating GSH decay and causing pH fluctuations.

[0025] Application-end compatibility test: Water-soluble fertilizer products from Examples 1 and 1-4 were used to prepare working solutions (1.0 g / L) at the same application concentration. Two water preparation conditions were also set up: deionized water and simulated hard water (containing 100 mg / L Ca). 2+ and 100 mg / L Mg 2+ Hard water was used to dissolve the solution completely and allowed to stand for 10 minutes to defoam. Then, filtration and drip irrigation simulations were performed on each group of working solutions. In the filtration evaluation, a fixed volume of working solution (500 mL) was filtered through a 150-mesh sieve, and the filtration time was recorded. The filter screen was gently washed with deionized water to remove surface salts and then dried in a 60℃ oven until constant weight. The mass of the filter membrane residue was weighed and converted to mg / 100 mL. Simultaneously, the turbidity (NTU) before and after filtration was measured as an indicator of solution clarity. The test results are shown in Tables 2 and 3 below. In the drip irrigation simulation, a standard drip irrigation system was used. The irrigation system (main pipe + branch pipe + pressure gauge) uses pressure-compensated drippers with a rated flow rate of 1L / h and a minimum flow channel width of approximately 0.5mm (drippers from the same batch). The working pressure is set at 0.10MPa, with three drippers connected in parallel for each group as a repeat. The corresponding working solution is placed in a storage tank with a stirrer and continuously circulated at 25℃ for 8 hours. The actual water output of each dripper is recorded at 0, 2, 4, 6, and 8 hours. The flow retention rate and attenuation rate are calculated: Flow retention rate (%) = Water output at sampling point / Initial water output × 100%. The drip irrigation simulation test results are as follows: Figure 4-5 As shown.

[0026] Table 2. Test results of deionized water filtration performance of water-soluble fertilizers in the examples and comparative examples.

[0027] Table 3. Test results of hard water filtration performance of water-soluble fertilizers in the examples and comparative examples.

[0028] Based on Table 2 and Figure 4-5 Results analysis showed that Example 1 performed best under both deionized water and hard water conditions. The process chain simultaneously addressed both the source of residue formation and the mechanism by which residue is amplified under hard water conditions. Firstly, Example 1 employed 10kDa ultrafiltration combined with 0.22μm filtration after enzyme inactivation in S2, significantly reducing protein / enzyme residue and macromolecular impurities, thus reducing aggregation, adsorption, and non-specific entanglement of particles prone to occur in high-salt environments. This resulted in less residue on the sieve and lower filtration resistance during sieving, leading to the shortest filtration time and lowest residue. Secondly, Example 1 formed a mild pre-coordination of GSH-Zn / Mn and introduced sodium gluconate and a buffer stabilizing salt in the weak acid window of S3, reducing the risk of local instability and flocculation caused by coordination competition / ionic strength fluctuations after dissolution. Therefore, the turbidity before filtration was already low, and the turbidity reduction after filtration was even more significant. Thirdly, Example 1 employed a composite wall structure of alginate cross-linking + chitosan secondary coating + regulator, resulting in a dense wall layer with stronger resistance to salt shock, particularly in hard water (high Ca2+). 2+ / Mg 2+ Under these conditions, the wall material network is less prone to peeling and gel fragmentation, thus significantly suppressing the amplification effect of hard water on turbidity and residue. It should be noted that although a 150-mesh sieve was used in this experiment to remove obvious large particulate impurities in the filtration evaluation, the flow rate attenuation in the drip irrigation system is not solely caused by direct blockage by large particles; pressure-compensated drippers typically employ a labyrinth channel structure, with localized low-shear reflux zones and microscale deposition sites within the channels. Under cyclic shear and localized concentration conditions, the high concentration of Ca in hard water... 2+ / Mg 2+ It readily interacts with anions such as phosphate in the system to generate microcrystalline deposits; at the same time, wall material micro-fragments and colloidal components can serve as nucleation and bridging sites for microcrystalline deposits, thereby forming soft-hard composite deposits that can gradually accumulate in the flow channel, as evidenced by the decrease in flow retention rate over time during the 8-hour cyclic pressure test.

[0029] In contrast, although Comparative Example 2 possesses S1 enzymatic shaping, protein / enzyme residues and large molecular impurities were not effectively removed. In a high ionic strength environment, these impurities are more prone to aggregation and the formation of soft agglomerates that can be trapped by a 150-mesh screen. This not only directly increases the residue on the screen and filtration time, but also gradually deposits in narrow sections of the flow channel during drip irrigation, inducing secondary trapping and causing a rapid decrease in flow retention rate. Under hard water conditions, Ca... 2+ / Mg 2+ This further promotes colloidal bridging and flocculation, significantly amplifying the process; therefore, Comparative Example 2 performed one of the worst in hard water. Comparative Example 4 may not show significant turbidity at initial dissolution, but lacks the densification and ion exchange barrier of the alginate network provided by the chitosan layer, resulting in poor performance in high-salt and Ca-containing environments. 2+ / Mg 2+ In hard water, ion exchange and network loosening are more likely to occur, producing wall material fragments or gel microflocculations, leading to a rapid increase in turbidity, a significant increase in residue on the screen, and a greater tendency to form deposits and blockages in the drip irrigation channel. Therefore, its turbidity rise rate and blockage speed are generally faster than other comparative examples. Comparative Example 3 transferred Zn / Mn to the NPK framework, leaving the core without the chemical protection and stable ionic environment provided by mild and reversible coordination. After dissolution, it is more prone to morphological fluctuations and flocculation, resulting in higher residue and turbidity than the example and a decrease in drip irrigation retention rate. However, since it still retains ultrafiltration purification and secondary coating, its degree of deterioration is generally lower than that of Comparative Example 2 / 4. Comparative Example 1 lacks a high-reduced state base, resulting in poor consistency of the effective morphology of the system. After dissolution, it is more prone to unstable side reactions and flocculation tendency, thus its overall filtration and drip irrigation performance is inferior to Example 1.

[0030] Potted plant stress resistance enhancement test: Seedlings of the same batch and with consistent growth were selected and transplanted into uniform plastic pots (12cm diameter) at the 2-3 true leaf stage. Each pot contained approximately 0.8kg of substrate, which was peat moss:perlite = 3:1 (v / v) with an initial pH of 6.0. After transplanting, the seedlings were allowed to recover for 5 days under greenhouse conditions. The greenhouse environment was controlled as follows: daytime 24±2℃, nighttime 18±2℃, relative humidity 55±10%, and light exposure 14h / day. Four treatment groups were set up: Example 1, Comparative Example 1, Comparative Example 3, and CK group (watered only under salt stress, no fertilizer). Each group had 6 pots, and the pots were randomly arranged and rotated every 2 days to reduce positional errors. Except for the treatment factors, all other management conditions were consistent. Application method: Fertigation. Prepare working solutions of the corresponding water-soluble fertilizers for each group at the same concentration, with a working solution concentration of 2.0 g / L. Start application from the day after the seedling establishment period ends, which is recorded as day 0. Apply 80 mL per pot each time, once every 5 days, for a total of 2 applications (day 0 and day 5). During the remaining time, replenish water with deionized water to maintain the soil moisture content at 70% of field capacity. Salt stress is established starting from day 6: To avoid non-specific damage caused by a sudden increase in salt concentration, salt is added gradually. On day 6, apply 80 mL of 50 mM NaCl solution to each pot, and on day 7, apply 80 mL of 100 mM NaCl solution to each pot. During the subsequent stress maintenance period, only deionized water is used to replenish water to the same pot weight by weighing, and NaCl solution is not added again. Index determination: SPAD was measured once before salt addition (day 6, before stress) as a baseline; SPAD values ​​were measured on day 3 (day 10) and day 7 (day 14) after salt addition (3 functional leaves were selected from each pot, 3 points were measured on each leaf and the average was taken); at the end of day 7 (day 14) of stress, the plants were harvested, the above-ground parts were cut and the fresh weight of a single plant (g / plant) was measured, and then the plants were dried in an 80℃ oven to constant weight and the dry weight (g / plant) was measured. The test results are shown in Table 4 below.

[0031] Table 4. Pot stress resistance test results of the water-soluble fertilizers in the examples and comparative examples

[0032] Based on the results in Table 4, under the same salt stress background, Example 1 established a higher proportion of reduced state and a more consistent effective speciation base at the front end of the process through enzymatic shaping in S1. In S3, a weak acid window was used to promote the formation of a mild and reversible pre-coordinated complex between GSH and Zn / Mn. Subsequently, alginate cross-linking and chitosan secondary coating achieved spatial confinement and a salt shock resistance barrier, thus slowing down the oxidative inactivation of GSH and achieving a more stable and effective release even under high ionic strength conditions in the rhizosphere. The synergistic effect of the above chemical speciation locking + reversible coordination protection + double-layer coating confinement resulted in a slower decline in chlorophyll levels in crops under salt stress (better preservation of SPAD), which was converted into higher fresh weight and dry weight accumulation. Comparative Example 1 lacked enzymatic shaping, resulting in insufficient consistency of the initial effective morphology. After entering the rhizosphere, it was more prone to oxidation and inactivation, thus limiting its stress resistance enhancement. Comparative Example 3 eliminated the pre-coordination protection of Zn / Mn entering the nucleus, weakening the synergistic effect of thiol microenvironment shielding and slow release. Therefore, its SPAD and biomass improvement were between those of Example 1 and Comparative Example 1. Due to the lack of exogenous stress resistance signals and basic nutrient buffers, the CK group suffered the most severe oxidative damage to its chloroplast structure and photosynthetic system under salt stress, resulting in the fastest deterioration of its physiological state and the worst biomass accumulation index. This, in turn, corroborated the physiological rescue value of the system in Example 1 under adverse conditions.

[0033] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An enzyme-stabilized glutathione water-soluble fertilizer, characterized in that, It comprises a functional microcapsule component and an NPK water-soluble salt system; the functional microcapsule component is 10-20 parts by mass, and the NPK water-soluble salt system is 80-90 parts by mass; the functional microcapsule component is composed of a microcapsule core and a microcapsule wall material, wherein, by mass, the microcapsule core is 40-55 parts and the microcapsule wall material is 45-60 parts; The core of the microcapsule comprises the following raw materials in parts by weight: 16-22 parts reduced glutathione, 1.2-2.5 parts zinc source, 0.8-1.8 parts manganese source, 0.2-0.7 parts sodium gluconate, 0.8-2 parts buffer stabilizer salt and 21-26 parts protectant; The microcapsule wall material comprises the following raw materials: sodium alginate, chitosan, calcium crosslinking agent, and regulator; In the NPK water-soluble salt system, the mass ratio of N, P2O5, and K2O is 20:20:20 or 15:5:30, calculated as nutrients.

2. The enzyme-stabilized glutathione water-soluble fertilizer according to claim 1, characterized in that, The zinc source is any one of zinc sulfate, zinc nitrate, zinc acetate, and zinc gluconate; the manganese source is any one of manganese sulfate, manganese nitrate, manganese acetate, and manganese gluconate.

3. The enzyme-stabilized glutathione water-soluble fertilizer according to claim 1, characterized in that, The buffer stabilizer salt is any one of sodium citrate, potassium citrate, sodium acetate, and phosphate.

4. The enzyme-stabilized glutathione water-soluble fertilizer according to claim 1, characterized in that, The protective agent is any one of trehalose, betaine, glycerol, and sorbitol.

5. The enzyme-stabilized glutathione water-soluble fertilizer according to claim 1, characterized in that, The microcapsule wall material comprises the following raw materials in parts by weight: 26-33 parts sodium alginate, 10-15 parts chitosan, 8-10 parts calcium crosslinking agent, and 1-2 parts regulator.

6. The enzyme-stabilized glutathione water-soluble fertilizer according to claim 1, characterized in that, The calcium crosslinking agent is either calcium chloride or calcium lactate.

7. The enzyme-stabilized glutathione water-soluble fertilizer according to claim 1, characterized in that, The regulator is any one of pectin, xanthan gum, and hydroxypropyl methylcellulose.

8. A method for preparing an enzyme-stabilized glutathione water-soluble fertilizer according to any one of claims 1-7, characterized in that, Specifically, the following steps are included: S1: Place deionized water in a reaction vessel and add reduced glutathione under light-protected conditions; adjust the pH of the solution using a sodium phosphate buffer system; add glutathione reductase and coenzyme sequentially under stirring, and add the coenzyme regeneration system, i.e., add glucose and glucose dehydrogenase, and continue stirring the reaction under light-protected conditions to obtain a highly reduced glutathione shaping solution. S2: The highly reduced glutathione shaping solution obtained in S1 was heated and kept at that temperature to inactivate the enzyme. After cooling to room temperature, it was ultrafiltered using an ultrafiltration membrane with a molecular weight cutoff of 10 kDa to remove protein and enzyme residues. Then, it was filtered through the membrane to obtain the glutathione shaping clear solution. S3: Adjust the temperature of the glutathione-based clean solution obtained in S2, adjust the pH of the solution with sodium hydroxide, add sodium gluconate while stirring, add a buffer stabilizer salt, and continue stirring to dissolve evenly; then add zinc source solution dropwise, controlling the pH to remain stable during the dropwise addition process; After the zinc source was added, the manganese source solution was added dropwise, and the reaction was stirred continuously. Finally, the protective agent was added and the mixture was stirred until the solution was clear to obtain the GSH-Zn / Mn pre-coordinated core liquid. S4: Weigh each raw material component according to the stated mass fractions, prepare an aqueous solution of sodium alginate, add a regulator, stir until completely dissolved, and let stand to remove bubbles; separately prepare an aqueous solution of chitosan and adjust the pH; prepare an aqueous solution of calcium crosslinking agent; S5: The pre-coordinated core fluid obtained in S3 is mixed with the sodium alginate aqueous solution in S4 and stirred evenly under low shear to obtain a shaped mixture; then, it is added to the calcium crosslinking agent aqueous solution in S4 by dripping to form beads and crosslinking treatment. After the crosslinking is completed, the microbeads are collected by filtration, washed with deionized water, and then placed in the chitosan aqueous solution in S4 for secondary coating. After washing with deionized water again, wet microcapsules are obtained. S6: Vacuum dry the wet microcapsules obtained in S5, sieve to obtain powder, then mix the microcapsule powder with the NPK water-soluble salt system at low speed, granulate by drum granulation, and then dry with hot air to obtain water-soluble fertilizer.

9. The method for preparing the enzyme-stabilized glutathione water-soluble fertilizer according to claim 8, characterized in that, In step S1, the coenzyme is NADPH, and its dosage is 0.02–0.05 mmol / L; the specific activity of the glutathione reductase is ≥200 U / mg, and its dosage is 1000–3000 U / L based on the enzyme activity in the reaction system, to drive glutathione to migrate towards a highly reduced state; the specific activity of the glucose dehydrogenase is ≥150 U / mg, and its dosage is 200–1000 U / L based on the enzyme activity in the reaction system; the glucose concentration is 10–30 g / L, and it provides coenzyme regeneration during the reaction process, so that the reaction reaches the reaction endpoint within 60–180 min; immediately after the reaction in step S1, deoxygenation treatment is performed, with nitrogen bubbling for 5–15 min.

10. The method for preparing the enzyme-stabilized glutathione water-soluble fertilizer according to claim 8, characterized in that, In step S1, the reaction endpoint is determined by enzymatic or chromatographic methods, and the reaction is stopped when either of the following conditions is met: reduced glutathione accounts for ≥85% of total glutathione or reduced glutathione: oxidized glutathione ≥6:1.

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