A fertilizer synergist containing inositol or its derivatives and a method for preparing the same

Abstract

The present application belongs to the technical field of fertilizer synergist, and particularly relates to a fertilizer synergist containing inositol or its derivative and a preparation method thereof, which comprises the following raw materials in parts by weight: modified fucoidan 10-15 parts, phytic acid-arginine compound 8-12 parts, polyaspartic acid 5-10 parts, modified inositol 1.5-3 parts, trace element salt 6.5-7 parts, and auxiliary agent 0.2-0.7 parts; the modified fucoidan is grafted with epsilon-polylysine after being oxidized by sodium periodate, the phytic acid-arginine compound is prepared by the reaction of phytic acid and L-arginine, and the modified inositol is prepared by esterification of inositol and boric acid. The components are compounded and spray dried to obtain the finished product. Through the synergy of multiple components, the present application realizes nutrient slow release and absorption promotion, improves the fertilizer utilization rate and crop yield.

Description

Technical Field

[0001] This invention relates to the field of fertilizer synergists, specifically to a fertilizer synergist containing inositol or its derivatives and its preparation method. Background Technology

[0002] Fertilizer synergists play a crucial role in agricultural production, not only improving fertilizer utilization efficiency but also enhancing soil conditions, promoting crop growth, and improving the quality of agricultural products. Currently, most synergists on the market are chemically synthesized, which has drawbacks such as high safety requirements, potential for phytotoxicity, long residual time, and premature crop aging. Therefore, developing efficient, safe, and environmentally friendly naturally derived fertilizer synergists is of significant practical importance. Inositol and its derivatives are natural plant growth regulators that can promote root development, improve photosynthetic efficiency, enhance stress resistance, and improve fruit quality; alginate oligosaccharides (fucoidan) regulate plant growth and induce improved plant disease resistance; polyaspartic acid is a biodegradable polymer that can effectively inhibit urea hydrolysis, reduce ammonia volatilization, and nitrogen leaching. Existing technologies have already reported on the application of these substances in fertilizer synergism.

[0003] Chinese invention patent CN121449468A discloses an environmentally friendly water-soluble fertilizer containing seaweed extract and polyglutamic acid. It is prepared by combining seaweed oligosaccharides, double-grafted sodium poly-L-γ-glutamic acid, and then complexing them, exhibiting slow-release properties and good stability. This technical solution modifies seaweed extract with polyglutamic acid and combines seaweed oligosaccharides with other ingredients through physical mixing or simple compounding. Its core lies in utilizing the water-retaining and chelating properties of polyglutamic acid. However, seaweed oligosaccharides themselves are not chemically modified and lack functional groups capable of actively anchoring metal ions, resulting in insufficient chelation and dispersion of trace elements, especially zinc, iron, and manganese. Chinese invention patent CN121377861A discloses a fertilizer synergist based on polyaspartic acid, fucoidan, and mannooligosaccharide, and its preparation method. Using plant-derived amino acid-based polyaspartic acid, fucoidan, and mannooligosaccharide as main raw materials, the three synergistically form a "induction-complexation-adsorption" three-in-one mechanism to reduce nutrient leaching and significantly improve nitrogen utilization and root vitality. However, in this technical solution, the fucoidan is used directly in an unmodified form. The surface of the fucoidan is dominated by negatively charged carboxyl groups. In the negatively charged soil colloidal environment, there is electrostatic repulsion between it and the similarly negatively charged polyaspartic acid, making it difficult to form a stable polyelectrolyte network.

[0004] Therefore, developing a multi-component synergistic fertilizer enhancer is of great practical significance for improving fertilizer utilization and promoting green agricultural development. Summary of the Invention

[0005] To address the problems of the prior art, this invention provides a fertilizer synergist containing inositol or its derivatives and its preparation method. Modified brown algae oligosaccharides are obtained by oxidizing with sodium periodate and then grafting with ε-polylysine. A phytic acid-arginine complex is prepared by reacting phytic acid with L-arginine. Modified inositol is obtained by esterifying inositol with borate. The above three modified components are then compounded with polyaspartic acid, trace element salts, and auxiliary agents to obtain a fertilizer synergist containing inositol or its derivatives that possesses long-lasting chelated nutrients, root-promoting and stress-resistant properties, and a slow-release boron synergistic effect.

[0006] The technical solution of the present invention to solve the above problems is as follows: A fertilizer synergist containing inositol or its derivatives comprises the following raw materials in parts by weight: 10-15 parts modified brown algae oligosaccharide, 8-12 parts phytic acid-arginine complex, 5-10 parts polyaspartic acid, 1.5-3 parts modified inositol, 6.5-7 parts trace element salts, and 0.2-0.7 parts auxiliary agents; The modified alginate oligosaccharide is prepared as follows: Step S1: Dissolve the brown algae oligosaccharide in deionized water, add sodium periodate, react at room temperature and in the dark for 2-2.5 h, add ethylene glycol, and obtain the intermediate product after post-treatment; Step S2: Dissolve the intermediate product in borate buffer, add ε-polylysine, stir to dissolve, add sodium cyanoborohydride, react at room temperature for 23-25 ​​h, adjust pH to 3.8-4.2 to terminate the reaction, and obtain modified fucoidan after post-treatment.

[0007] Further, in step S1, the mass-to-volume ratio of the brown algae oligosaccharide, sodium periodate, and deionized water is 1g:0.1-0.14g:8-12mL, and the amount of ethylene glycol added is such that the final volume concentration reaches 0.8-1.2%.

[0008] Further, in step S2, the mass-to-volume ratio of the intermediate product and the borate buffer is 8g:70-90mL, and the mass ratio of the intermediate product, ε-polylysine, and sodium cyanoborohydride is 80:9.5-10.5:3.7-4.3.

[0009] Furthermore, the preparation method of the phytic acid-arginine complex is as follows: dilute the phytic acid aqueous solution, add L-arginine under stirring, control the temperature to not exceed 40℃, raise the temperature to 55-65℃ after the addition is complete, keep the temperature for 1-2 hours, and obtain the phytic acid-arginine complex after post-treatment.

[0010] Furthermore, the phytic acid aqueous solution dilution refers to diluting a 70% phytic acid aqueous solution with deionized water to obtain a phytic acid solution with a mass-volume concentration of 27-33%, wherein the molar ratio of phytic acid to arginine is 1:2-2.5.

[0011] Further, the preparation method of the modified inositol is as follows: inositol is dissolved in deionized water, boric acid is added, then the pH is adjusted to 8.3-8.7, the temperature is raised to 75-85℃, the reaction is kept at the temperature for 3-4 hours, the temperature is cooled to room temperature, the pH is adjusted to 7.0 to terminate the reaction, and the modified inositol is obtained after post-treatment.

[0012] Furthermore, the mass-to-volume ratio of inositol, boric acid, and deionized water is 4.5-5.5g:2.7-3.3g:50mL.

[0013] Furthermore, the trace element salts are a mixture of zinc sulfate, ferric sulfate, manganese sulfate, and boric acid, and the auxiliary agent is an alkyl glycoside.

[0014] Furthermore, the mass ratio of zinc sulfate, ferric sulfate, manganese sulfate, and boric acid is 40:12-18:5-10:3-7.

[0015] The preparation method of the above-mentioned fertilizer synergist containing inositol or its derivatives is as follows: dissolve phytic acid-arginine complex in deionized water, adjust the pH to 6.3-6.7, add trace element salts, heat to 50-55℃, and stir for 1-1.5h; cool to room temperature, add polyaspartic acid, modified fucoidan oligosaccharide, and modified inositol, continue stirring for 30-40min, add auxiliary agents, stir to dissolve, and finally spray dry to obtain the product.

[0016] The present invention has the following beneficial effects: This invention employs a stepwise chemical modification strategy to optimize the structure and enhance the activity of three core functional components, with a clear progressive synergistic relationship between each step. In step S1, the fucoidan oligosaccharide is selectively oxidized with sodium periodate, introducing aldehyde active sites onto the molecular chain. The resulting intermediate product retains the inherent functions of fucoidan oligosaccharide in promoting root growth and enhancing stress resistance, while also acquiring the chemical basis for reversible coordination with metal ions and fertilizer nutrients, providing a highly reactive functional anchor for subsequent grafting reactions. In step S2, the intermediate product is grafted with ε-polylysine through a reductive amination reaction. The introduction of polylysine significantly enhances the cation density of the molecular chain, enabling the modified fucoidan oligosaccharide to form an amphiphilic structure. This structure allows it to adsorb onto the surface of soil colloids via electrostatic interactions and form a nutrient enrichment layer in the rhizosphere microzone. Simultaneously, the amino group of polylysine forms multiple hydrogen bonds and an electrostatic network with the phosphate group in the phytate-arginine complex and the hydroxyl group in the modified inositol, constructing a three-dimensional nutrient retention system. In the preparation of the phytate-arginine complex, the introduction of arginine regulates the release behavior of phytate through electrostatic interactions and hydrogen bonds. This retains phytate's ability to coordinate and fix trace elements such as zinc, iron, and manganese while avoiding excessive fixation of soil mineral nutrients by free phytate. Simultaneously, arginine, as a nitrogen metabolism signaling molecule, can activate the root nitrogen absorption and transport system, forming a synergistic nitrogen-phosphorus supply effect with the phosphorus source provided by phytate. In the preparation of modified inositol, borate esterification not only retains the bioactivity of inositol but also endows it with the ability to synergistically participate in cell wall pectin crosslinking and membrane lipid metabolism regulation with boron. Furthermore, the borate ester structure can be controlled to hydrolyze under weakly acidic soil conditions, achieving a temporal match between nutrient supply and signal activation. The modification steps of the above three components are not carried out in isolation, but in a progressive manner: the aldehyde grouping of the fucoidan provides a chemical basis for the grafting of polylysine; the cationization of polylysine creates conditions for the construction of an electrostatic network with phytic acid-arginine and modified inositol; the complexation of phytic acid-arginine and the esterification of inositol respectively enhance the chelation and signal transduction functions of trace elements. The three components ultimately form a quadruple synergistic mechanism of physical adsorption, chemical chelation, biostimulation and signal activation in the synergist system.

[0017] The abundant carboxyl and amino groups on the polyaspartic acid molecular chain can form coordination compounds with ammonium nitrogen, nitrate nitrogen, and potassium ions in the soil, reducing nutrient loss. Its biodegradability also ensures that it will not cause cumulative pollution to the soil environment after exerting a slow-release effect. The micronutrient salts are a specific mixture of zinc sulfate, ferric sulfate, manganese sulfate, and boric acid. Zinc, iron, and manganese, as essential micronutrients for plants, participate in the formation of active centers of various enzymes and the electron transport process in photosynthesis, while boron participates in cell wall synthesis and sugar transport regulation. These four elements synergistically supplement the deficiencies of micronutrients in conventional macronutrient fertilizers. The adjuvant alkyl glycoside, as a non-ionic biosurfactant, has good wetting and penetrability, reducing the surface tension of the synergist aqueous solution and promoting its spreading and absorption on plant leaves and roots. Its biocompatibility and biodegradability align with the development direction of green agriculture. The components of this invention form a multi-level synergistic network through hydrogen bonding, electrostatic interaction, coordination chelation, and hydrophobic interaction: the cationic polysaccharide skeleton of the modified brown algae oligosaccharide provides the physical basis for rhizosphere adsorption and nutrient retention for the entire system; the phytic acid-arginine complex is anchored to the skeleton by phosphate groups and guanidine groups and loaded with trace elements; the modified inositol enhances the water solubility and stability of the system through the hydroxyl network; polyaspartic acid is interspersed in the network to regulate the nitrogen release rate; trace element salts are pre-complexed with phytic acid-arginine under weakly acidic conditions and then uniformly dispersed in the network nodes; and alkyl glycosides are distributed on the network surface to optimize the interfacial properties. This holistic and synergistic design enables the synergist to simultaneously exert multiple functions after being applied to the soil, including slow release of nutrients, rhizosphere enrichment, micronutrient activation, signal transduction, and cell structure regulation. Field trials have shown that the fertilizer synergist of this invention can significantly increase crop plant height, ear length, number of grains per ear, thousand-grain weight, and yield, increase the zinc, iron, and manganese content in the grains, enhance the accumulation of nitrogen, phosphorus, and potassium in the aboveground parts of the plant, and improve nitrogen fertilizer partial productivity and nitrogen fertilizer utilization rate, thus having good economic and social benefits. Attached Figure Description

[0018] Figure 1 Comparison chart of zinc, iron, and manganese content in grains from different treatment groups; Figure 2 A comparison chart of nitrogen, phosphorus, and potassium accumulation in maize from different treatment groups. Detailed Implementation

[0019] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0020] All raw materials used in the following examples are commercially available products. Alkyl glycosides (99% active ingredient content) were from Shandong Jubang Chemical Co., Ltd.; fucoidan (99% active ingredient content) was from Hebei Hongtao Bioengineering Co., Ltd.; ε-polylysine (99% active ingredient content) was from Jiangsu Aofu Biotechnology Co., Ltd.; L-arginine (99% active ingredient content) was from Wuhan Jiyesheng Chemical Co., Ltd.; inositol (99% active ingredient content) was from Jiangsu Huace Biotechnology Co., Ltd.; and polyaspartic acid (40% active ingredient content) was from Shandong Xuchen Chemical Technology Co., Ltd.

[0021] Example 1 A fertilizer synergist containing inositol or its derivatives comprises the following raw materials in parts by weight: 10 parts modified fucoidan, 8 parts phytic acid-arginine complex, 5 parts polyaspartic acid, 1.5 parts modified inositol, 6.5 parts trace element salts, and 0.2 parts auxiliary agents; wherein the trace element salts are a mixture of zinc sulfate, ferric sulfate, manganese sulfate, and boric acid in a mass ratio of 40:15:8:5, and the auxiliary agents are alkyl glycosides; The modified alginate oligosaccharide is prepared as follows: Step S1: Dissolve fucoidan oligosaccharide in deionized water, add sodium periodate, react at room temperature and in the dark for 2.3 h, add ethylene glycol, and perform ultrafiltration at a molecular weight cutoff of 500 Da. Freeze-dry the retentate to obtain the intermediate product. The mass-to-volume ratio of fucoidan oligosaccharide, sodium periodate, and deionized water is 1 g:0.12 g:10 mL, and the amount of ethylene glycol added is to achieve a final volume concentration of 1%. Step S2: Dissolve the intermediate product in 0.1 M borate buffer at pH 8.5, add ε-polylysine, stir to dissolve, and then add sodium cyanoborohydride in batches. The first batch is added after the ε-polylysine is dissolved, and the amount added is 35% of the total sodium cyanoborohydride mass. The second batch is added after the first batch is added and stirred for 1 hour, and the amount added is 35% of the total sodium cyanoborohydride mass. The third batch is added after the second batch is added and stirred for 1 hour, and the amount added is the remaining sodium cyanoborohydride. After all the additions are complete, react at room temperature for 22 hours. Adjust the pH to 3.8-4.2 with 1M dilute hydrochloric acid solution to terminate the reaction. Perform ultrafiltration washing three times at a molecular weight cutoff of 3000 Da, and freeze-dry to obtain modified fucoidan oligosaccharide. The mass-to-volume ratio of intermediate product to borate buffer is 8 g:80 mL, and the mass ratio of intermediate product, ε-polylysine, and sodium cyanoborohydride is 80:10:4.

[0022] The preparation method of the phytic acid-arginine complex is as follows: a 70% phytic acid aqueous solution is diluted with deionized water to obtain a 30% phytic acid solution. L-arginine is added under stirring, and the temperature is controlled not to exceed 40℃. After the addition is completed, the temperature is raised to 60℃ and the reaction is carried out under the conditions of stirring for 1.5h. The phytic acid-arginine complex is obtained by spray drying under the conditions of inlet air temperature of 120℃, outlet air temperature of 80℃ and feed rate of 5mL / min. The molar ratio of phytic acid to arginine is 1:2.3.

[0023] The modified inositol is prepared by dissolving inositol in deionized water, adding boric acid, adjusting the pH to 8.3-8.7 with 1M sodium hydroxide solution, heating to 80℃, stirring and refluxing for 3.5h, naturally cooling to room temperature, adjusting the pH to 7.0 with 1M dilute hydrochloric acid solution to terminate the reaction, concentrating under reduced pressure to half the original volume, and spray drying under conditions of 120℃ inlet air temperature, 80℃ outlet air temperature, and 5mL / min feed rate to obtain modified inositol, wherein the mass-volume ratio of inositol, boric acid, and deionized water is 5g:3g:50mL.

[0024] The preparation method of the above-mentioned fertilizer synergist containing inositol or its derivatives is as follows: phytic acid-arginine complex is dissolved in deionized water, the pH is adjusted to 6.3-6.7 with 1M sodium hydroxide solution, trace element salts are added, the temperature is raised to 50℃, and the reaction is stirred for 1 hour; after natural cooling to room temperature, polyaspartic acid, modified fucoidan oligosaccharide, and modified inositol are added, and stirring is continued for 30 minutes. Additives are added, and the mixture is stirred to dissolve. Finally, spray drying is carried out under the conditions of an inlet air temperature of 120℃, an outlet air temperature of 80℃, and a feed rate of 5 mL / min to obtain the final product.

[0025] Example 2 A fertilizer synergist containing inositol or its derivatives comprises the following raw materials in parts by weight: 12 parts modified brown algae oligosaccharide, 10 parts phytic acid-arginine complex, 8 parts polyaspartic acid, 2 parts modified inositol, 6.8 parts trace element salts, and 0.5 parts auxiliary agents; wherein the trace element salts are a mixture of zinc sulfate, ferric sulfate, manganese sulfate, and boric acid in a mass ratio of 40:15:8:5, and the auxiliary agents are alkyl glycosides; The preparation methods for the modified brown algae oligosaccharide, the phytic acid-arginine complex, and the modified inositol are the same as in Example 1.

[0026] The preparation method of the above-mentioned fertilizer synergist containing inositol or its derivatives is as follows: phytic acid-arginine complex is dissolved in deionized water, the pH is adjusted to 6.3-6.7 with 1M sodium hydroxide solution, trace element salts are added, the temperature is raised to 53℃, and the reaction is stirred for 1.2h; after natural cooling to room temperature, polyaspartic acid, modified fucoidan oligosaccharide, and modified inositol are added, and stirring is continued for 35min. Additives are added, and the mixture is stirred to dissolve. Finally, spray drying is carried out under the conditions of inlet air temperature of 120℃, outlet air temperature of 80℃, and feed rate of 5mL / min to obtain the final product.

[0027] Example 3 A fertilizer synergist containing inositol or its derivatives comprises the following raw materials in parts by weight: 15 parts modified fucoidan, 12 parts phytic acid-arginine complex, 10 parts polyaspartic acid, 3 parts modified inositol, 7 parts trace element salts, and 0.7 parts auxiliary agents; wherein the trace element salts are a mixture of zinc sulfate, ferric sulfate, manganese sulfate, and boric acid in a mass ratio of 40:15:8:5, and the auxiliary agents are alkyl glycosides; The preparation methods for the modified brown algae oligosaccharide, the phytic acid-arginine complex, and the modified inositol are the same as in Example 1.

[0028] The preparation method of the above-mentioned fertilizer synergist containing inositol or its derivatives is as follows: phytic acid-arginine complex is dissolved in deionized water, the pH is adjusted to 6.3-6.7 with 1M sodium hydroxide solution, trace element salts are added, the temperature is raised to 55℃, and the reaction is stirred for 1.5h; after natural cooling to room temperature, polyaspartic acid, modified fucoidan oligosaccharide, and modified inositol are added, and stirring is continued for 40min. Additives are added, and the mixture is stirred to dissolve. Finally, spray drying is carried out under the conditions of inlet air temperature of 120℃, outlet air temperature of 80℃, and feed rate of 5mL / min to obtain the final product.

[0029] Example 4 A fertilizer synergist containing inositol or its derivatives comprises the following raw materials in parts by weight: 10 parts modified fucoidan, 8 parts phytic acid-arginine complex, 5 parts polyaspartic acid, 1.5 parts modified inositol, 6.5 parts trace element salts, and 0.2 parts auxiliary agents; wherein the trace element salts are a mixture of zinc sulfate, ferric sulfate, manganese sulfate, and boric acid in a mass ratio of 40:18:10:7, and the auxiliary agents are alkyl glycosides; The modified alginate oligosaccharide is prepared as follows: Step S1: Dissolve fucoidan oligosaccharide in deionized water, add sodium periodate, react at room temperature and in the dark for 2.5 h, add ethylene glycol, and perform ultrafiltration at a molecular weight cutoff of 500 Da. Freeze-dry the retentate to obtain the intermediate product. The mass-to-volume ratio of fucoidan oligosaccharide, sodium periodate, and deionized water is 1 g:0.14 g:12 mL, and the amount of ethylene glycol added is to achieve a final volume concentration of 1.2%. Step S2: Dissolve the intermediate product in 0.1 M borate buffer at pH 8.5, add ε-polylysine, stir to dissolve, and then add sodium cyanoborohydride in batches. The first batch is added after the ε-polylysine is dissolved, and the amount added is 35% of the total sodium cyanoborohydride mass. The second batch is added after the first batch is added and stirred for 1 hour, and the amount added is 35% of the total sodium cyanoborohydride mass. The third batch is added after the second batch is added and stirred for 1 hour, and the amount added is the remaining sodium cyanoborohydride. After all the additions are complete, react at room temperature for 23 hours. Adjust the pH to 3.8-4.2 with 1M dilute hydrochloric acid solution to terminate the reaction. Perform ultrafiltration washing three times at a molecular weight cutoff of 3000 Da, and freeze-dry to obtain modified fucoidan oligosaccharide. The mass-to-volume ratio of intermediate product to borate buffer is 8 g:90 mL, and the mass ratio of intermediate product, ε-polylysine, and sodium cyanoborohydride is 80:10.5:4.3.

[0030] The preparation method of the phytic acid-arginine complex is as follows: a 70% phytic acid aqueous solution is diluted with deionized water to obtain a 30% phytic acid solution. L-arginine is added under stirring, and the temperature is controlled not to exceed 40℃. After the addition is completed, the temperature is raised to 65℃ and stirred for 2 hours. The phytic acid-arginine complex is obtained by spray drying under the conditions of inlet air temperature of 120℃, outlet air temperature of 80℃ and feed rate of 5mL / min. The molar ratio of phytic acid to arginine is 1:2.5.

[0031] The modified inositol is prepared as follows: inositol is dissolved in deionized water, boric acid is added, and then the pH is adjusted to 8.3-8.7 with 1M sodium hydroxide solution. The temperature is raised to 85℃, and the mixture is kept at this temperature and stirred under reflux for 4 hours. The mixture is then naturally cooled to room temperature, and the pH is adjusted to 7.0 with 1M dilute hydrochloric acid solution to terminate the reaction. The mixture is concentrated under reduced pressure to half of its original volume, and spray-dried under the conditions of inlet air temperature of 120℃, outlet air temperature of 80℃, and feed rate of 5mL / min to obtain modified inositol. The mass-volume ratio of inositol, boric acid, and deionized water is 5.5g:3.3g:50mL.

[0032] The preparation method of the above-mentioned fertilizer synergist containing inositol or its derivatives is the same as in Example 1.

[0033] Comparative Example 1 A fertilizer synergist containing inositol or its derivatives comprises the following raw materials in parts by weight: 5 parts modified brown algae oligosaccharide, 5 parts phytic acid-arginine complex, 5 parts polyaspartic acid, 5 parts modified inositol, 6.5 parts trace element salts, and 0.2 parts auxiliary agents; wherein the trace element salts are a mixture of zinc sulfate, ferric sulfate, manganese sulfate, and boric acid in a mass ratio of 40:15:8:5, and the auxiliary agents are alkyl glycosides; The modified alginate oligosaccharide is prepared as follows: Step S1: Dissolve fucoidan oligosaccharide in deionized water, add sodium periodate, react at room temperature and in the dark for 1 hour, add ethylene glycol, and perform ultrafiltration at a molecular weight cutoff of 500 Da. Freeze-dry the retentate to obtain the intermediate product. The mass-to-volume ratio of fucoidan oligosaccharide, sodium periodate, and deionized water is 1 g:0.05 g:10 mL, and the amount of ethylene glycol added is to achieve a final volume concentration of 1%. Step S2: Dissolve the intermediate product in 0.1 M borate buffer at pH 8.5, add ε-polylysine, stir to dissolve, add sodium cyanoborohydride, and react at room temperature for 22 h. Adjust the pH to 3.8-4.2 with 1 M dilute hydrochloric acid solution to terminate the reaction. Perform ultrafiltration washing three times at a molecular weight cutoff of 3000 Da, and freeze-dry to obtain modified fucoidan oligosaccharide. The mass-to-volume ratio of intermediate product to borate buffer is 8 g:80 mL, and the mass ratio of intermediate product, ε-polylysine, and sodium cyanoborohydride is 80:5:4.

[0034] The preparation method of the phytic acid-arginine complex is as follows: a 70% phytic acid aqueous solution is diluted with deionized water to obtain a 30% phytic acid solution. L-arginine is added under stirring, and the temperature is controlled not to exceed 40℃. After the addition is completed, the temperature is raised to 40℃ and the reaction is carried out with stirring for 1.5h. The phytic acid-arginine complex is obtained by spray drying under the conditions of inlet air temperature of 120℃, outlet air temperature of 80℃ and feed rate of 5mL / min, wherein the molar ratio of phytic acid to arginine is 1:1.

[0035] The modified inositol is prepared by dissolving inositol in deionized water, adding boric acid, adjusting the pH to 8.3-8.7 with 1M sodium hydroxide solution, heating to 50℃, stirring and refluxing for 3.5h, naturally cooling to room temperature, adjusting the pH to 7.0 with 1M dilute hydrochloric acid solution to terminate the reaction, concentrating under reduced pressure to half the original volume, and spray drying under conditions of 120℃ inlet air temperature, 80℃ outlet air temperature, and 5mL / min feed rate to obtain modified inositol, wherein the mass-volume ratio of inositol, boric acid, and deionized water is 3g:3g:50mL.

[0036] The preparation method of the above-mentioned fertilizer synergist containing inositol or its derivatives is as follows: phytic acid-arginine complex is dissolved in deionized water, the pH is adjusted to 6.3-6.7 with 1M sodium hydroxide solution, trace element salts are added, the temperature is raised to 40℃, and the reaction is stirred for 1 hour; after natural cooling to room temperature, polyaspartic acid, modified fucoidan oligosaccharide, and modified inositol are added, and stirring is continued for 30 minutes. Additives are added, and the mixture is stirred to dissolve. Finally, spray drying is carried out under the conditions of an inlet air temperature of 120℃, an outlet air temperature of 80℃, and a feed rate of 5 mL / min to obtain the final product.

[0037] Comparative Example 2 A fertilizer synergist containing inositol or its derivatives, wherein the modified fucoidan is replaced with commercially available fucoidan, and the rest is the same as in Example 1.

[0038] Comparative Example 3 A fertilizer synergist containing inositol or its derivatives, wherein the phytic acid-arginine complex is replaced with commercially available phytic acid, and the rest is the same as in Example 1.

[0039] Comparative Example 4 A fertilizer synergist containing inositol or its derivatives, wherein modified inositol is replaced with commercially available inositol, and the rest is the same as in Example 1.

[0040] Comparative Example 5 A fertilizer synergist containing inositol or its derivatives, wherein the modified fucoidan is replaced with commercially available fucoidan, the phytic acid-arginine complex is replaced with commercially available phytic acid, the modified inositol is replaced with commercially available inositol, and the rest is the same as in Example 1.

[0041] Performance testing: Performance tests were conducted using field plot trials to evaluate the effects of the fertilizer synergists prepared in Examples 1-4 and Comparative Examples 1-5. The trials included 11 treatment groups: Examples 1-4, Comparative Examples 1-5, a conventional fertilizer control group (CK, receiving water-soluble fertilizer with equal nutrient content and dosage but without any added synergist), and a no-fertilizer control group (CK0). Each treatment was replicated three times in a randomized block design, with each plot measuring 20 m². 2 The maize variety used in the test was Zhengdan 958. The base fertilizer application was 450 kg / hm² of compound fertilizer (15-15-15). 2 Apply 150 kg / hm² of water-soluble fertilizer containing macro-elements (N-P₂O₅-K₂O=30-10-10) at the jointing stage and the tasseling stage of maize, respectively. 2In each treatment group, 2% of the total fertilizer mass was added with the corresponding synergist from the example or comparative example, while the CK group received no synergist. At the maize maturity stage, 10 representative consecutive plants from each plot were selected for evaluation, and the following indicators were measured: plant height (cm), ear length (cm), ear diameter (cm), number of kernels per ear (kernels / ear), and thousand-kernel weight (g). Simultaneously, the yield of each plot was calculated based on the actual harvested area and converted to yield (kg / hm²). 2 ), and count the number of effective ears (ears / hm) 2 Before harvest, five representative plants were selected from each plot, and the zinc, iron, and manganese content (mg / kg) in the maize kernels was determined using the ICP-OES method. The aboveground plant samples were dried, pulverized, and digested, and the nitrogen, phosphorus, and potassium accumulation (kg / hm²) was determined. 2 Nitrogen fertilizer partial productivity (PFPN, kg / kg) was calculated as yield / total nitrogen application, and nitrogen fertilizer utilization rate (NUE, %) was calculated as (nitrogen uptake by plants in the nitrogen-approved area - nitrogen uptake by plants in the unfertilized control area) / nitrogen application rate × 100%. The experimental data were analyzed for significance using Duncan's new multiple range test (P < 0.05).

[0042] The specific test data results are shown in Table 1 and Table 2. Figure 1 and Figure 2 .

[0043] Table 1. Effects of different treatments on maize growth traits and yield CK0 168.5±4.2 g 13.2±0.3 g 3.8±0.2 f 285±12 g 245±5 g 38500±1200 g 3820±150 g CK 245.6±5.2 f 18.2±0.4 f 4.6±0.2 e 462±15 f 328±5 f 49500±1500 f 8560±210 f Example 1 276.8±4.8 b 20.5±0.3 b 5.2±0.2 b 573±12 b 362±4 b 53200±1400 b 10580±260 b Example 2 278.5±5.1 b 20.7±0.4 b 5.3±0.2 ab 582±13 ab 365±4 ab 53600±1500 ab 10820±280 ab Example 3 282.3±4.9 a 21.0±0.3 a 5.4±0.2 a 593±12 a 369±4 a 54200±1400 a 11150±300 a Example 4 277.2±5.0 b 20.6±0.4 b 5.2±0.2 b 576±13 b 363±4 b 53400±1450 b 10650±270 b Comparative Example 1 258.4±4.5 d 19.0±0.3 d 4.8±0.2 d 498±14 d 340±4 e 50800±1300 d 9120±220 e Comparative Example 2 262.5±4.6 c 19.3±0.4 c 4.9±0.2 c 518±13 c 346±4 d 51500±1350 c 9520±240 d Comparative Example 3 260.2±4.7 cd 19.1±0.3 cd 4.8±0.2 cd 505±14 cd 343±4 de 51100±1320 cd 9310±230 de Comparative Example 4 264.0±4.8 c 19.5±0.4 c 5.0±0.2 c 528±13 c 349±4 cd 52000±1380 c 9680±250 cd Comparative Example 5 252.5±4.2 e 18.5±0.3 e 4.5±0.2 e 475±15 e 333±5 ef 49800±1280 e 8720±210 f Table 2. Effects of different treatments on micronutrient content and nitrogen fertilizer utilization efficiency in maize kernels. CK0 15.2±1.3 f 12.2±1.1 f 8.5±0.8 f 45±2.4 f 20±1.2 f 30±2.0 f — — CK 22.5±1.2 e 18.5±1.0 e 12.5±0.7 e 110±2.3 e 50±1.1 e 90±1.9 e 58.41±1.27 e 41.27±1.46 e Example 1 35.2±1.2 a 30.5±1.0 a 20.8±0.8 a 138±2.5 a 68±1.2 a 115±2.0 a 69.71±1.33 a 59.05±1.59 a Example 2 36.8±1.1 a 31.2±0.9 a 21.5±0.7 a 142±2.2 a 70±1.1 a 118±1.8 a 72.70±1.21 a 61.59±1.40 a Example 3 38.5±1.3 a 32.0±1.1 a 22.2±0.8 a 145±2.4 a 72±1.2 a 120±2.0 a 75.68±1.40 a 63.49±1.52 a Example 4 34.5±1.2 a 29.8±1.0 a 20.2±0.7 a 135±2.3 a 66±1.1 a 112±1.9 a 68.06±1.27 a 57.14±1.46 a Comparative Example 1 32.8±1.1 b 28.5±0.9 b 19.5±0.8 b 132±2.2 b 64±1.2 b 108±2.0 b 66.35±1.14 b 55.24±1.40 b Comparative Example 2 28.5±1.2 c 25.2±1.0 c 17.2±0.7 c 125±2.3 c 60±1.1 c 102±1.9 c 64.00±1.21 c 50.79±1.46 c Comparative Example 3 27.2±1.1 c 24.5±0.9 c 16.5±0.8 c 122±2.2 c 58±1.2 c 100±2.0 c 63.17±1.14 c 48.89±1.40 c Comparative Example 4 26.8±1.2 c 24.2±1.0 c 16.2±0.7 c 120±2.3 c 57±1.1 c 98±1.9 c 62.35±1.21 c 47.62±1.46 c Comparative Example 5 25.5±1.1 d 23.5±0.9 d 15.5±0.8 d 118±2.2 d 55±1.2 d 95±2.0 d 61.46±1.14 d 46.35±1.40 d The data in the table are presented as "mean ± standard deviation," and different letters in the same column indicate significant differences (P < 0.05). The total nitrogen application rate was 157.5 kg / hm². 2 (Calculation basis: 450 kg / hm² of base fertilizer and compound fertilizer) 2 The nitrogen content of 15% is 67.5 kg / hm². 2 Apply water-soluble fertilizer twice, 150 kg / hm² each time. 2 30% nitrogen content, totaling 90 kg / hm 2 CK0 is a blank control without fertilization; PFPN and NUE are not calculated.

[0044] From Table 1, Table 2, Figure 1 and Figure 2It can be seen that the performance decline of Comparative Example 1 is mainly due to the fact that its formula ratio and preparation process parameters deviate from the preferred range of the present invention. Multiple process defects together lead to a significant decline in the performance of the fertilizer synergist of this comparative example in field trials. Its ability to promote the chelation and dispersion of trace elements is weakened, the absorption efficiency of crops for zinc, iron and manganese is reduced, and the trace element content of grains is reduced. Phytic acid-metal complexes are easy to precipitate in the soil, and the nitrogen fertilizer utilization efficiency and crop yield indicators are not as good as those of the example.

[0045] From Table 1, Table 2, Figure 1 and Figure 2 It is evident that the performance of Comparative Example 2 declined because it replaced the modified fucoidan with commercially available fucoidan, thus losing the aldehyde active sites introduced by sodium periodate oxidation in step S1, as well as the increased cation density and amphiphilic structural characteristics brought about by ε-polylysine grafting in step S2. While commercially available fucoidan retains the water-retention properties and weak biostimulatory activity of general polysaccharides, it lacks the nutrient retention network and metal ion chelating ability to form synergistically with polylysine. It cannot construct a three-dimensional hydrogen bond and electrostatic network with the phytic acid-arginine complex, modified inositol, and polyaspartic acid in the formulation. At the soil-plant interface, commercially available fucoidan cannot effectively adsorb onto the negatively charged soil colloid surface and is also unable to form a nutrient enrichment layer in the rhizosphere microzone, leading to increased nitrogen loss and a weakened rhizosphere nutrient concentration gradient. Ultimately, this results in reduced plant absorption efficiency of nitrogen, phosphorus, potassium, and micronutrients, with significantly lower plant height, effective spike number, spike grain number, and yield compared to Example 1. Nitrogen fertilizer utilization and partial productivity also decrease accordingly.

[0046] From Table 1, Table 2, Figure 1 and Figure 2 It is evident that the performance of Comparative Example 3 was reduced. Comparative Example 3 replaced the phytic acid-arginine complex with commercially available phytic acid, thus losing the synergistic modification effect of arginine. Although commercially available phytic acid retains the chelating ability of multiple phosphate groups for micronutrients, it lacks the electrostatic regulation and steric hindrance protection provided by the guanidine and amino groups of arginine. In the soil environment, it is easily fixed by non-specific binding with calcium and magnesium ions, resulting in a significant reduction in the bioavailability of micronutrients. At the same time, the lack of arginine means the absence of nitrogen metabolism signaling molecules, preventing the synergist from activating the nitrogen absorption and transport system on the root surface. The synergistic supply effect of nitrogen and phosphorus is lost, and the synchronous absorption of macronutrients and micronutrients by plants is inhibited. In addition, the hydrogen bonding and electrostatic interaction between commercially available phytic acid and modified fucoidan and modified inositol are weakened, reducing the stability of the overall nutrient retention system. The rhizosphere nutrient release behavior changes from slow and controllable release to rapid loss, ultimately resulting in significantly lower ear length, ear diameter, thousand-grain weight, and other ear traits and yield compared to Example 1. The zinc, iron, and manganese content of the grains and the accumulation of nitrogen, phosphorus, and potassium in the plants are also reduced accordingly.

[0047] From Table 1, Table 2, Figure 1 and Figure 2 It is evident that the performance of Comparative Example 4 was reduced. Comparative Example 4 replaced modified inositol with commercially available inositol, losing the structural stability and functional synergy brought about by borosilicate modification. Although commercially available inositol can serve as a precursor for the phosphatidylinositol signaling pathway, it lacks the protection of borosilicate bonds, exhibiting high solubility and rapid migration in soil aqueous solutions, making it difficult to stably exist in the rhizosphere microregion. This results in a large amount of inositol being lost with water before exerting its signaling regulatory effect. Simultaneously, the lack of boron prevents the synergist from participating in cell wall pectin cross-linking and membrane lipid metabolism regulation, hindering the maintenance of normal cell wall mechanical strength and extensibility, and weakening the root's promotion of transmembrane absorption of calcium ions and trace elements. The commercially available inositol's ability to form hydrogen bond networks with other components in the formulation is insufficient, reducing the overall rhizosphere adsorption and water solubility synergistic effect of the synergist system. This weakens the regulatory effect on sucrose transport and grain filling, ultimately resulting in significantly lower plant height, number of grains per ear, thousand-grain weight, and yield compared to Example 1, with reduced efficiency in the distribution and accumulation of photosynthetic products to the ear.

[0048] From Table 1, Table 2, Figure 1 and Figure 2 It is evident that the performance of Comparative Example 5 declined. Comparative Example 5 simultaneously replaced the modified fucoidan, phytic acid-arginine complex, and modified inositol with commercially available products. This means that the three core functional components in the synergist system simultaneously lost the structural advantages and synergistic activities brought about by chemical modification. Commercially available fucoidan lacks aldehyde anchoring and polylysine cation modification; commercially available phytic acid lacks the nitrogen-phosphorus synergy and electrostatic protection of arginine; and commercially available inositol lacks boron ester stabilization and boron synergy. The combined effect of these three factors degrades the synergist from a synergistic system with multiple functions including physical adsorption, chemical chelation, biostimulation, and signal activation into a simple mixture with only single or weak activities. At the soil-plant interface, the nutrient retention network completely disintegrates, the rhizosphere enrichment layer cannot form, the chelation and slow-release functions of micronutrients are lost, the nitrogen signal activation pathway is blocked, and the plant's absorption efficiency of nitrogen, phosphorus, potassium, and micronutrients drops to levels close to or even lower than conventional fertilizers. In field trials, all agronomic traits, yield, nutrient accumulation, and nitrogen fertilizer utilization efficiency were significantly lower than in Example 1.

[0049] Although embodiments of this application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A fertilizer synergist containing inositol or its derivatives, characterized in that, The raw materials include the following parts by weight: 10-15 parts modified brown algae oligosaccharide, 8-12 parts phytic acid-arginine complex, 5-10 parts polyaspartic acid, 1.5-3 parts modified inositol, 6.5-7 parts trace element salts, and 0.2-0.7 parts auxiliary agents. The modified alginate oligosaccharide is prepared as follows: Step S1: Dissolve the brown algae oligosaccharide in deionized water, add sodium periodate, react at room temperature and in the dark for 2-2.5 h, add ethylene glycol, and obtain the intermediate product after post-treatment; Step S2: Dissolve the intermediate product in borate buffer, add ε-polylysine, stir to dissolve, add sodium cyanoborohydride, react at room temperature for 23-25 ​​h, adjust pH to 3.8-4.2 to terminate the reaction, and obtain modified fucoidan after post-treatment.

2. The fertilizer synergist containing inositol or its derivatives according to claim 1, characterized in that, In step S1, the mass-to-volume ratio of the alginate oligosaccharide, sodium periodate, and deionized water is 1g:0.1-0.14g:8-12mL, and the amount of ethylene glycol added is such that the final volume concentration reaches 0.8-1.2%.

3. The fertilizer synergist containing inositol or its derivatives according to claim 1, characterized in that, In step S2, the mass-to-volume ratio of the intermediate product and the borate buffer is 8 g: 70-90 mL, and the mass ratio of the intermediate product, ε-polylysine, and sodium cyanoborohydride is 80: 9.5-10.5: 3.7-4.

3.

4. The fertilizer synergist containing inositol or its derivatives according to claim 1, characterized in that, The preparation method of the phytic acid-arginine complex is as follows: dilute the phytic acid aqueous solution, add L-arginine, control the temperature to not exceed 40℃, raise the temperature to 55-65℃ after the addition is complete, keep the temperature for 1-2 hours, and obtain the phytic acid-arginine complex after post-treatment.

5. The fertilizer synergist containing inositol or its derivatives according to claim 4, characterized in that, The phytic acid aqueous solution dilution refers to diluting a 70% phytic acid aqueous solution with deionized water to obtain a phytic acid solution with a mass-volume concentration of 27-33%, wherein the molar ratio of phytic acid to arginine is 1:2-2.

5.

6. The fertilizer synergist containing inositol or its derivatives according to claim 1, characterized in that, The modified inositol is prepared by dissolving inositol in deionized water, adding boric acid, adjusting the pH to 8.3-8.7, heating to 75-85℃, maintaining the temperature for 3-4 hours, cooling to room temperature, adjusting the pH to 7.0 to terminate the reaction, and obtaining modified inositol after post-treatment.

7. The fertilizer synergist containing inositol or its derivatives according to claim 6, characterized in that, The mass-to-volume ratio of inositol, boric acid, and deionized water is 4.5-5.5g:2.7-3.3g:50mL.

8. The fertilizer synergist containing inositol or its derivatives according to claim 1, characterized in that, The trace element salts are a mixture of zinc sulfate, ferric sulfate, manganese sulfate, and boric acid, and the auxiliary agents are alkyl glycosides.

9. The fertilizer synergist containing inositol or its derivatives according to claim 8, characterized in that, The mass ratio of zinc sulfate, ferric sulfate, manganese sulfate, and boric acid is 40:12-18:5-10:3-7.

10. The method for preparing the fertilizer synergist containing inositol or its derivatives as described in any one of claims 1-9, characterized in that, Specifically, the phytic acid-arginine complex is dissolved in deionized water, the pH is adjusted to 6.3-6.7, trace element salts are added, the temperature is raised to 50-55℃, and the reaction is stirred for 1-1.5 hours; after cooling to room temperature, polyaspartic acid, modified fucoidan oligosaccharide, and modified inositol are added, and stirring is continued for 30-40 minutes. Then, auxiliary agents are added, stirred and dissolved, and finally spray-dried to obtain the final product.

Images