Water-retaining gel, traditional chinese medicine seed coating agent, preparation method thereof and application in promoting traditional chinese medicine seed germination and drought resistance

Abstract

This invention relates to water-retaining gels, seed coating agents for traditional Chinese medicine, their preparation methods, and their applications in promoting seed germination and drought resistance, belonging to the fields of agriculture and functional materials technology. The water-retaining gel obtained by crosslinking urea with sodium carboxymethyl cellulose in this invention not only has excellent water retention capacity but also achieves complete degradation in soil, making it an environmentally friendly water-retaining material. The seed pelleting coating agent for traditional Chinese medicine of this invention comprises the following components by weight: 10 parts seeds, 40-60 parts inert filler, 3-6 parts water-retaining gel, and 0.2-0.6 parts binder. The water-retaining gel of this invention has a unique three-dimensional porous network structure and outstanding water retention capacity. Seedlings grown from seeds coated with the water-retaining pelleting agent of this invention can maintain better external morphology and growth status under drought conditions; the coating effectively enhances the drought resistance of seedlings.

Description

Technical Field

[0001] This invention belongs to the field of agricultural and functional materials technology, specifically relating to an environmentally friendly water-retaining material based on sodium carboxymethyl cellulose cross-linked urea (CMC / Urea), a seed coating agent for traditional Chinese medicine, its preparation method, and its application in promoting seed germination and enhancing drought resistance. Background Technology

[0002] Understory semi-wild cultivation has become an important direction for the development of the Chinese medicinal herb industry in recent years. It fully utilizes forest resources and produces medicinal herbs with quality closer to that of wild herbs. However, the complex understory environment, rapid evaporation of topsoil moisture, and poor water retention capacity pose significant challenges to the direct sowing and seedling emergence of medicinal herbs. Taking Scutellaria baicalensis seeds as an example, their small size and limited content make them highly susceptible to low germination rates and uneven emergence due to water loss when directly sown in the arid understory environment, severely hindering the development of the understory medicinal herb industry. Therefore, the use of water-retaining materials to improve germination and seedling emergence rates has become an important means of solving the problem of drought and water loss. Numerous existing technologies have been reported regarding water-retaining materials. For example, CN110272314A discloses a method for preparing a coated straw fiber-based water-retaining slow-release fertilizer. This method uses straw cellulose polysaccharide chains as the backbone, grafting acrylic acid and acrylamide-like substances generated from the reaction with urea onto the cellulose backbone. A three-dimensional network polymer structure is then formed through cross-linking with a cross-linking agent. Simultaneously, it interpenetrates with polyvinyl alcohol to form a semi-interpenetrating network structure of highly absorbent resin. This resin is then coated onto fertilizer granules, and a film is formed by cross-linking a mixture of polyvinyl alcohol, sodium alginate, and carboxymethyl cellulose to coat the outermost layer, thus obtaining the coated straw fiber-based water-retaining slow-release fertilizer. CN119822889A discloses a carboxymethyl cellulose-based water-retaining slow-release fertilizer and its preparation method, composed of an aqueous solution, carboxymethyl cellulose (CMC), soluble starch (St), a cross-linking agent, and urea.

[0003] Seed pelleting and coating technology is widely used to improve seed germination rates and stress resistance. This technology creates a favorable microenvironment for seed germination by coating the seed surface with a layer containing functional components. Currently, most common pelleting coatings use organic polymer-based superabsorbent resins as water-retaining agents. For example, CN116649336A discloses a seed coating agent and its preparation method, comprising: 1-3 parts polymer, 3-6 parts fungicide, 8-15 parts nutrients, 4-7 parts plant growth regulator, and 2-5 parts dye; wherein the polymer is composed of one or more of vinyl alcohol (PVA), polyacrylamide (PAM), and sodium carboxymethyl cellulose (CMS-Na); wherein the fungicide is composed of one or more of enrofloxacin, imidacloprid, and metalaxyl-M; wherein the plant growth regulator is composed of one or more of auxin, gibberellin, nitrourea, and ethylene; and wherein the dye is composed of one or more of carmine, penicillin, xanthan gum, xylose, and soy isoflavones. CN121080504A discloses a seed pelleting formula and processing method for improving the salt tolerance of Suaeda salsa in coastal saline-alkali land. The pelleting formula includes a filler, a binder, a water-retaining agent, and a biostimulant. The filler consists of 348-492 parts, including attapulgite, talc, and vermiculite; the binder consists of 73-89 parts, including sodium carboxymethyl cellulose, polyvinyl alcohol, and starch; the water-retaining agent consists of 30-42 parts, which is polyacrylamide; and the biostimulant consists of 20-78 parts, including yeast metabolites, potassium humate, seaweed extract, rhamnose glycolipids, and microbial inoculants. CN121698696A discloses seed coating materials and processes for wheat and rice. The seed coating material includes micron-sized iron powder, nano-sized calcium phosphate, nano-sized magnesium hydroxide, and a binder. The amount of micron-sized iron powder, nano-sized calcium phosphate, and nano-sized magnesium hydroxide added accounts for 10%–20%, 2%–10%, and 3%–10% of the total seed weight, respectively. The binder is at least one of polyvinyl alcohol colloidal solution, carboxymethyl cellulose colloidal solution, and hydroxypropyl methyl cellulose colloidal solution.

[0004] However, existing water-retaining materials or seed coating agents mostly use petroleum-derived materials such as polyacrylic acid and polyacrylamide, which are difficult to degrade in soil. Long-term accumulation can lead to soil compaction and microplastic pollution, failing to meet the requirements of green and sustainable development. Furthermore, the screening of traditional pelleting formulations is mostly focused on single crops, with limited research on their universality for different seeds. Optimization studies on key parameters such as coating layer thickness and the synergistic effect of binders and fillers are also insufficient, resulting in repeated trials and errors for different medicinal herb seeds, leading to low efficiency.

[0005] Therefore, developing an environmentally friendly water-retaining material that combines high water retention performance and complete biodegradability, and applying it to seed pelleting coating, and systematically optimizing the coating formula, to solve the problems of low seed germination rate and poor seedling drought resistance in forest-based semi-wild planting, has important practical significance and application value. Summary of the Invention

[0006] Given the current state of existing technologies, particularly concerning the poor water retention capacity of soil in semi-wild forest environments, leading to water loss, low germination rates, and uneven seedling emergence after direct sowing of medicinal herbs; existing water-retaining materials such as polyacrylic acid resins are difficult to degrade in soil, posing environmental residue and ecological pollution risks; and the lack of universally applicable and environmentally friendly water-retaining pelleting coating formulas tailored to the characteristics of medicinal herb seeds, making it difficult to effectively enhance seedling adaptability under drought stress while improving seed germination quality. This invention discovers that a water-retaining gel obtained by cross-linking urea with sodium carboxymethyl cellulose not only possesses excellent water retention capacity but also achieves complete degradation in soil, classifying it as an environmentally friendly water-retaining material. Its application in pelleting coating formulas for medicinal herb seeds not only improves the germination rate and drought resistance of Scutellaria baicalensis seeds but also demonstrates good effects on other medicinal herb seeds such as Astragalus membranaceus, Glycyrrhiza uralensis, Salvia miltiorrhiza, Bupleurum chinense, and Perilla frutescens, exhibiting significant universality. This invention is based on these findings.

[0007] Therefore, one object of the present invention is to provide an environmentally friendly water-retaining gel based on sodium carboxymethyl cellulose cross-linked urea (CMC / Urea) and its preparation method.

[0008] The second objective of this invention is to provide a formulation for granulation of traditional Chinese medicine seeds containing the above-mentioned water-retaining gel and a method for preparing the coating formulation.

[0009] The third objective of this invention is to provide the application of the above-mentioned water-retaining gel and granulation coating formulations in improving the germination rate of Chinese medicinal herbs and the drought resistance of seedlings in a simulated wild environment under forest cover.

[0010] The technical solution for achieving the above-mentioned objectives can be summarized as follows:

[0011] A water-retaining gel, which is a material with a three-dimensional cross-linked network structure formed by cross-linking sodium carboxymethyl cellulose with urea.

[0012] According to the present invention, the preparation method of the above-mentioned water-retaining gel includes the following steps:

[0013] Sodium carboxymethyl cellulose was dissolved in a solvent, activated with an activator, and then urea was added and stirred to react. After the reaction was completed, the mixture was washed and dried to obtain a hydrogel.

[0014] According to the present invention, preferably, the solvent has a pH of 5 to 7, and more preferably a phosphate buffer solution.

[0015] According to the present invention, preferably, sodium carboxymethyl cellulose is added to the solvent and allowed to swell naturally for 12 to 24 hours before being stirred to dissolve;

[0016] Further preferably, the stirring and dissolving temperature is 20~30℃, and the stirring and dissolving time is 10~30 min.

[0017] According to the present invention, preferably, the material ratio of sodium carboxymethyl cellulose and urea is controlled according to the molar ratio of urea-NH2 to carboxymethyl cellulose-COOH of 1:1 to 2:1.

[0018] According to the present invention, preferably, the activator is selected from one of the following combinations:

[0019] A combination of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (EDC) and N-hydroxysuccinimide (NHS) in a molar ratio of 1:1 to 1:2;

[0020] Alternatively, a combination of EDC and N-hydroxybenzimidazole (HOBt) in a molar ratio of 1:1 to 1:2;

[0021] Alternatively, a combination of N,N'-dicyclohexylcarbodiimide (DCC), HOBt, and N,N'-dimethylaminopyridine (DMAP) in a molar ratio of 1:1:1 to 1:2:4.

[0022] According to the present invention, preferably, the amount of activator added is controlled to be a molar ratio of 1:1 to 2:1 with sodium carboxymethyl cellulose.

[0023] According to the present invention, preferably, the washing process involves rinsing with deionized water 3 to 5 times, with each rinse lasting 5 to 15 minutes.

[0024] According to the present invention, preferably, the drying process adopts vacuum drying or freeze drying; more preferably, the vacuum drying conditions are: temperature 5~40℃, pressure <133 Pa, time 2~24 h, and the freeze drying conditions are: temperature -20 ~ -80℃, pressure <5 Pa, time 12~48 h.

[0025] The present invention also provides a seed pelleting coating agent containing the above-mentioned water-retaining gel, which comprises the following components by weight: 10 parts of seeds, 40-60 parts of inert filler, 3-6 parts of water-retaining gel, and 0.2-0.6 parts of binder.

[0026] According to the present invention, preferably, the seeds are Scutellaria baicalensis, Astragalus membranaceus, Glycyrrhiza uralensis, Salvia miltiorrhiza, Bupleurum chinense, or Perilla frutescens.

[0027] According to the present invention, preferably, the inert filler is at least two of talc, bentonite, activated carbon, diatomite, and vermiculite; more preferably, a mixture of talc and bentonite.

[0028] Preferably, the mass ratio of each component of the inert filler is determined as follows:

[0029] Talc powder 50-100 parts, bentonite 10-40 parts, activated carbon 1-10 parts, diatomaceous earth 1-10 parts, vermiculite powder 1-10 parts.

[0030] According to the present invention, preferably, the adhesive is one of polyvinyl alcohol, methylcellulose, carboxymethylcellulose, gum arabic, or peach gum.

[0031] According to the present invention, preferably, the coating layer thickness of the coating agent is 2-3 mm.

[0032] According to the present invention, the preparation method of the above-mentioned traditional Chinese medicine seed granulation coating agent includes the following steps:

[0033] The adhesive is mixed with water to prepare an adhesive solution with a mass concentration of 2% to 6%. The adhesive solution is sprayed onto the seed surface until it is moistened. Then, a portion of inert filler and water-retaining gel powder is added to coat the seed surface with powder. When the seed surface is coated with powder and appears loose, the adhesive solution is sprayed again and the mixed powder is added to continue coating. This process is repeated until all the mixed powder has been added. Then, the mixture is sieved and dried to obtain the seed pelleting coating agent for traditional Chinese medicine.

[0034] According to the present invention, preferably, the seeds are pretreated before being sprayed with the adhesive solution. The pretreatment process is to disinfect with a 0.1% to 2% NaClO solution for 5 to 15 minutes, rinse with distilled water, and dry at 30 to 50°C for 2 to 4 hours.

[0035] According to the present invention, preferably, the particle size is 2 mm to 3 mm after sieving.

[0036] According to the present invention, preferably, the coating agent for granulation of Chinese herbal seeds is dried to a moisture content of less than 12%.

[0037] This invention also provides the use of the above-mentioned water-retaining gel and the seed pelleting coating agent for traditional Chinese medicine, specifically its application in improving the germination rate of traditional Chinese medicine seeds and the drought resistance of seedlings in a semi-wild environment under forest cover.

[0038] The beneficial effects of this invention are as follows:

[0039] 1. Excellent eco-friendly properties: The CMC / Urea functional water-retaining gel constructed in this invention uses natural biodegradable materials as a matrix and can be completely degraded in soil within 32 days. It completely solves the problem of traditional polyacrylic acid water-retaining agents being difficult to degrade and leaving residues that pollute the soil, demonstrating excellent eco-friendliness and providing a new path for the development of green agricultural inputs.

[0040] 2. Outstanding water retention performance: The water-retaining gel of this invention has a unique three-dimensional porous network structure. Not only does it maintain a water retention rate of over 90% for one week at room temperature, but it can also maintain a high water retention rate of over 60% even under pressure conditions simulating soil stress at a depth of 5-10 cm (40℃). This indicates that it can continuously and effectively retain moisture in the actual environment of forest soil, providing a stable and moist microenvironment for seed germination.

[0041] 3. Significantly Improves Seed Germination Quality: Through scientific and systematic single-factor and orthogonal experiments, the optimal formulation for pelleting coating, including this environmentally friendly water-retaining gel, was determined. This optimal coating treatment significantly improved the germination rate, germination index, and vigor index of Scutellaria baicalensis seeds (the germination rate of the experimental group reached 74.00±2.00%, significantly higher than the 55.33±3.06% of the control group), proving that this coating technology can effectively improve the sowing microenvironment and promote seed germination.

[0042] 4. Enhanced drought resistance in seedlings: Water deprivation stress tests showed that seedlings grown from seeds coated with the water-retaining pellets of this invention maintained better external morphology and growth under drought conditions, with significantly lower wilting levels compared to the bare seed group. This confirms that the coating layer effectively enhances the drought resistance of seedlings, laying a solid foundation for later survival and growth in semi-wild understory planting.

[0043] 5. Strong applicability: The water-retaining granulation coating agent of this invention is not only effective on Scutellaria baicalensis seeds, but also shows good applicability on the seeds of various Chinese medicinal herbs such as Astragalus membranaceus, Glycyrrhiza uralensis, Salvia miltiorrhiza, Bupleurum chinense, and Perilla frutescens, providing a universal and efficient technical solution for the large-scale and standardized understory planting of various Chinese medicinal herbs. Attached Figure Description

[0044] Figure 1 SEM image of the CMC / Urea functional hydrogel obtained in Example 1 of this invention.

[0045] Figure 2 FTIR spectrum of CMC / Urea functional hydrogel obtained in Example 1 of this invention.

[0046] Figure 3 The time-varying curve of water retention rate of CMC / Urea hydrogel under room temperature and 40°C high temperature and pressure in Experiment Example 1 of this invention.

[0047] Figure 4 Figure 2 shows the germination verification results of granulated coated seeds of Scutellaria baicalensis in Experiment Example 2 of this invention.

[0048] Figure 5 : Comparison of the degree of wilting of seedlings in the experimental group and the control group under drought stress in Experiment Example 2 of this invention. Detailed Implementation

[0049] This invention provides an environmentally friendly water-retaining gel based on sodium carboxymethyl cellulose cross-linked urea (CMC / Urea) and its preparation method. The water-retaining gel obtained by cross-linking urea with sodium carboxymethyl cellulose not only has excellent water retention capacity but also achieves complete degradation in soil, making it an environmentally friendly water-retaining material. Its application in the granulation coating formulation of traditional Chinese medicine seeds not only improves the germination rate and drought resistance of Scutellaria baicalensis seeds but also shows good effects on the seeds of other traditional Chinese medicines such as Astragalus membranaceus, Glycyrrhiza uralensis, Salvia miltiorrhiza, Bupleurum chinense, and Perilla frutescens, demonstrating significant versatility.

[0050] The water-retaining gel of the present invention is a material with a three-dimensional cross-linked network structure formed by cross-linking sodium carboxymethyl cellulose with urea.

[0051] The preparation method of the above-mentioned water-retaining gel of the present invention includes the following steps:

[0052] Sodium carboxymethyl cellulose was dissolved in a solvent, activated with an activator, and then urea was added and stirred to react. After the reaction was completed, the mixture was washed and dried to obtain a hydrogel.

[0053] According to the present invention, sodium carboxymethyl cellulose is first added to a solvent for natural swelling, and then fully dissolved under stirring. The solvent has a pH of 5-7. In one or more preferred embodiments, the solvent is a phosphate buffer solution.

[0054] In one or more preferred embodiments, sodium carboxymethyl cellulose is added to the solvent and allowed to swell naturally for 12-24 hours before being stirred to dissolve; preferably, the stirring and dissolving temperature is 20-30°C and the stirring and dissolving time is 10-30 min.

[0055] According to the present invention, sodium carboxymethyl cellulose is first activated with an activator to convert the -COOH group into an active ester intermediate, which facilitates nucleophilic substitution reaction with the amino group of the urea molecule to generate an amide bond.

[0056] In one or more preferred embodiments, the activator is selected from one of the following combinations:

[0057] A combination of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (EDC) and N-hydroxysuccinimide (NHS) in a molar ratio of 1:1 to 1:2;

[0058] Alternatively, a combination of EDC and N-hydroxybenzimidazole (HOBt) in a molar ratio of 1:1 to 1:2;

[0059] Alternatively, a combination of N,N'-dicyclohexylcarbodiimide (DCC), HOBt, and N,N'-dimethylaminopyridine (DMAP) in a molar ratio of 1:1:1 to 1:2:4.

[0060] In one or more preferred embodiments, the amount of activator added is controlled to be a molar ratio of 1:1 to 2:1 with sodium carboxymethyl cellulose.

[0061] According to the present invention, carboxymethyl cellulose is used as the backbone, and the carboxyl groups (-COOH) on its molecular chain undergo an amidation condensation crosslinking reaction with the amino groups (-NH2) in urea to construct a stable three-dimensional network gel structure through chemical bonds. This micro-network can efficiently bind and slowly release water, while the crosslinking network can gradually degrade and slowly release nitrogen, thus having the dual functions of water retention and drought resistance as well as nutrient supply. Moreover, the material is mainly composed of natural polymers, which can be completely biodegradable and leave no environmental residue.

[0062] In one or more preferred embodiments, the material ratio of sodium carboxymethyl cellulose to urea is controlled according to a molar ratio of urea-NH2 to carboxymethyl cellulose-COOH of 1:1 to 2:1.

[0063] According to the present invention, after the crosslinking reaction is completed, washing is performed to remove unreacted urea and condensation reagent.

[0064] In one or more preferred embodiments, the washing process involves rinsing with deionized water 3 to 5 times, with each rinse lasting 5 to 15 minutes.

[0065] According to the present invention, after washing, drying is performed to obtain a water-retaining gel solid. In one or more preferred embodiments, the drying process employs vacuum drying or freeze drying; preferably, the vacuum drying conditions are: temperature 5~40℃, pressure <133 Pa, time 2~24 h; the freeze drying conditions are: temperature -20 ~ -80℃, pressure <5 Pa, time 12~48 h.

[0066] According to a preferred embodiment of the method for preparing a hydrogel according to the present invention, the method includes the following steps:

[0067] First, prepare a solution by adding 100-150 mL of solvent (pH range 5-7) to every 3 g of sodium carboxymethyl cellulose (CMC) and allowing it to swell naturally for 12-24 hours. Stir for 10-30 min at a temperature of 25±2℃ and a stirring speed of 100-500 r / min to ensure complete dissolution of the CMC. Then, add an activator selected from one of the following combinations: a molar ratio of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (EDC) to N-hydroxysuccinimide (NHS) of 1:1 to 1:2; a molar ratio of EDC to N-hydroxybenzimidazole (HOBt) of 1:1 to 1:2; or a molar ratio of N,N'-dicyclohexylcarbodiimide (DCC), HOBt, and N,N'-dimethylaminopyridine (DMAP) of 1:1:1 to 1:2:4. Continue stirring for 10-60 min until activation is complete. Next, according to the molar ratio of urea-NH2 to carboxymethyl cellulose-COOH of 1:1 to 2:1, an appropriate amount of urea was added and the mixture was stirred for 1 to 6 hours. After the reaction was completed, the prepared CMC / Urea hydrogel was allowed to stand to remove bubbles and then poured into a mold. The hydrogel was then removed from the mold and rinsed 3 to 5 times with deionized water, each rinse lasting 5 to 15 minutes, to remove unreacted urea and condensation reagents. Finally, the rinsed hydrogel was placed in a vacuum drying oven or freeze dryer and dried under vacuum conditions (vacuum drying: temperature 5 to 40℃, pressure < 133 Pa, time 2 to 24 h; freeze drying: temperature -20 to -80℃, pressure < 5 Pa, time 12 to 48 h) to obtain the environmentally friendly CMC / Urea functional hydrogel product.

[0068] The present invention also provides a seed pelleting coating agent containing the above-mentioned water-retaining gel, which comprises the following components by weight: 10 parts of seeds, 40-60 parts of inert filler, 3-6 parts of water-retaining gel, and 0.2-0.6 parts of binder.

[0069] According to the present invention, the seeds are Scutellaria baicalensis, Astragalus membranaceus, Glycyrrhiza uralensis, Salvia miltiorrhiza, Bupleurum chinense, or Perilla frutescens. The granulation coating agent of the present invention is not only highly effective on Scutellaria baicalensis seeds, but also exhibits good versatility on the seeds of various other Chinese medicinal herbs such as Astragalus membranaceus, Glycyrrhiza uralensis, Salvia miltiorrhiza, Bupleurum chinense, and Perilla frutescens.

[0070] According to the present invention, the inert filler can serve as a pellet skeleton support agent, adjust the pellet size and mechanical strength, ensure that the pellets are regular and uniform, facilitate mechanized precision seeding, and reduce the formulation cost.

[0071] In one or more preferred embodiments, the inert filler is at least two of talc, bentonite, activated carbon, diatomaceous earth, and vermiculite; a mixture of talc and bentonite is further preferred.

[0072] Preferably, the mass ratio of each component of the inert filler is determined as follows:

[0073] Talc powder 50-100 parts, bentonite 10-40 parts, activated carbon 1-10 parts, diatomaceous earth 1-10 parts, vermiculite powder 1-10 parts.

[0074] According to the present invention, the adhesive serves to coat the inert filler and the water-retaining gel onto the seed surface.

[0075] In one or more preferred embodiments, the adhesive is one of polyvinyl alcohol, methylcellulose, carboxymethylcellulose, gum arabic, or peach gum.

[0076] In one or more preferred embodiments, the coating layer thickness of the coating agent is 2-3 mm.

[0077] According to the present invention, the preparation method of the above-mentioned traditional Chinese medicine seed granulation coating agent includes the following steps:

[0078] The adhesive is mixed with water to prepare an adhesive solution with a mass concentration of 2% to 6%. The adhesive solution is sprayed onto the seed surface until it is moistened. Then, a portion of inert filler and water-retaining gel powder is added to coat the seed surface with powder. When the seed surface is coated with powder and appears loose, the adhesive solution is sprayed again and the mixed powder is added to continue coating. This process is repeated until all the mixed powder has been added. Then, the mixture is sieved and dried to obtain the seed pelleting coating agent for traditional Chinese medicine.

[0079] According to the present invention, the seeds are pretreated before being sprayed with the adhesive solution. The pretreatment process is to disinfect with a 0.1% to 2% NaClO solution for 5 to 15 minutes, rinse with distilled water, and dry at 30 to 50°C for 2 to 4 hours.

[0080] In one or more preferred embodiments, the particles are sieved to a particle size of 2 mm to 3 mm.

[0081] In one or more preferred embodiments, the product is dried to a moisture content of less than 12%.

[0082] According to the present invention, a preferred embodiment of the preparation method of a coating agent for granulation of traditional Chinese medicine seeds includes the following steps:

[0083] Before pelleting and coating, the Scutellaria baicalensis seeds are first pretreated by disinfecting them with a 0.1%–2% NaClO solution for 5–15 min, rinsing them several times with distilled water, and drying them at 30–50℃ for 2–4 h. Then, at least two of the following are selected as inert fillers: talc (50%–100%), bentonite (10%–40%), activated carbon (1%–10%), diatomaceous earth (1%–10%), and vermiculite (1%–10%). The required mass is weighed and passed through a 120-mesh sieve. Subsequently, it is thoroughly mixed with 6%–12% CMC / Urea water-retaining gel. Finally, a certain amount of one of the following—polyvinyl alcohol, methylcellulose, carboxymethylcellulose, gum arabic, or peach gum—is weighed and mixed with water to prepare a 2%–6% binder solution.

[0084] Scutellaria baicalensis seeds were pelleted and coated using a polishing and spheronizing machine at a speed of 30-60 r / min. Before starting the coating machine, pre-treated Scutellaria baicalensis seeds were poured in, and a suitable amount of binder solution was sprayed in using a pressure sprayer until the seed surface was slightly moistened and no liquid dripped. One-quarter of the volume of the mixture of filler powder and water-retaining agent was added to the coating pan. When the seed surface began to be coated with a powder layer and became loose, and dust was flying in the coating pan, a second layer of binder solution was added. This process of adding powder and repeating was continued until all the filler powder was added. After the Scutellaria baicalensis pellets reached a particle size of 2-3 mm, they were sieved and dried at 30-40 ℃ until the moisture content was less than 12%.

[0085] This invention also provides the use of the above-mentioned water-retaining gel and the seed pelleting coating agent for traditional Chinese medicine, specifically its application in improving the germination rate of traditional Chinese medicine seeds and the drought resistance of seedlings in a semi-wild environment under forest cover.

[0086] The present invention will be further described below through specific embodiments, but is not limited thereto.

[0087] Example 1: Preparation and characterization of environmentally friendly CMC / Urea functional hydrogel

[0088] Accurately weigh 3.0 g of sodium carboxymethyl cellulose (MW 250000, DS=0.7) and dissolve it in 100 mL of phosphate buffer at pH 6 to obtain a colorless, transparent, homogeneous solution. Add activator EDC at a molar ratio of 1.2:1 to sodium carboxymethyl cellulose-COOH and react for 5 min. Then add NHS, keeping the molar ratio of EDC to NHS at 1:1. Stir at 300 rpm for 15 min until it is homogeneous with the CMC solution. Then add urea according to the molar ratio of urea-NH2 to carboxymethyl cellulose-COOH of 1:0.75 and continue stirring for 1 h. After the reaction is complete, allow the prepared CMC / Urea hydrogel to stand to remove bubbles and pour it into a mold.

[0089] The hydrogel was removed from the mold and rinsed three times with deionized water for 10 minutes each time to remove unreacted urea and condensation reagents. The rinsed hydrogel was then placed in a freeze dryer (temperature -60℃, pressure <5 Pa, time 24h) for drying to obtain the CMC / Urea functional hydrogel product.

[0090] The SEM images of the CMC / Urea functional hydrogel obtained in this embodiment at different magnifications are as follows: Figure 1 As shown, the FTIR spectrum is as follows Figure 2 As shown. By Figure 1 , Figure 2 This confirms that urea has been successfully introduced into the CMC hydrogel system, forming a stable three-dimensional cross-linked network structure.

[0091] Example 2:

[0092] As described in Example 1, the difference is:

[0093] The activator is a 1:1 molar ratio of EDC to N-hydroxybenzimidazole (HOBt); urea is added according to a 1:1 molar ratio of urea-NH2 to carboxymethyl cellulose-COOH; the rinsed hydrogel is placed in a vacuum dryer (temperature 30℃, pressure <133 Pa, time 10h) for drying to obtain the CMC / Urea functional hydrogel product.

[0094] Example 3:

[0095] As described in Example 1, the difference is:

[0096] The activator is a combination of N,N'-dicyclohexylcarbodiimide (DCC), HOBt and N,N'-dimethylaminopyridine (DMAP) in a molar ratio of 1:1:1; urea is added according to the molar ratio of urea-NH2 to carboxymethyl cellulose-COOH of 2:1.

[0097] Example 4: Preparation and application of water-retaining pellet coating for Scutellaria baicalensis seeds

[0098] Before pelleting and coating, weigh 200 g of Scutellaria baicalensis seeds, disinfect them with 2% NaClO solution for 10 min, rinse them several times with distilled water, and dry them for later use; weigh talc powder and bentonite (mass ratio 80:20, seed powder ratio 1:5) as inert fillers, mix them thoroughly with 9% CMC / Urea water-retaining gel prepared in Example 1, and set aside; prepare 100 mL of 4% polyvinyl alcohol aqueous solution as a binder.

[0099] Scutellaria baicalensis seeds were pelleted and coated using an HBY-300 polishing and rounding machine at a speed of 35 r / min. Before starting the coating machine, the seeds were poured in, and a suitable amount of polyvinyl alcohol aqueous solution was sprayed in using a pressure sprayer until the seed surface was slightly moistened without dripping. One-quarter of the volume of the filler powder and water-retaining gel mixture was added to the coating pan. When the seed surface began to be coated with a powder layer and became loose, and dust was seen flying in the coating pan, a second layer of polyvinyl alcohol aqueous solution was added. This process was repeated until all the filler powder was added. After pelleting and coating, the seeds were sieved to obtain pellets with a particle size of approximately 2 mm. These pellets were then dried at 30-40℃ until the moisture content was less than 12%.

[0100] Example 5: Verification of the universality of the optimized formulation

[0101] The optimized pelleting coating formula obtained in Example 4 (filler talc: bentonite = 80:20, water-retaining gel addition amount 9%, binder polyvinyl alcohol concentration 4%, coating layer thickness 2 mm) was applied to the seeds of five kinds of Chinese medicinal herbs: Astragalus membranaceus, Glycyrrhiza uralensis, Salvia miltiorrhiza, Bupleurum chinense, and Perilla frutescens, and pelleting was carried out according to the same coating process.

[0102] Experimental Example 1

[0103] The water retention performance of the water-retaining gel prepared in Example 1 was tested. The tests were conducted at room temperature and under simulated soil stress at a depth of 5-10 cm at 40°C. The results are as follows: Figure 3 As shown.

[0104] Depend on Figure 3 It can be seen that the water retention rate of the water-retaining gel remains above 90% for one week under room temperature conditions, and can still maintain a water retention rate of over 60% under simulated soil stress of 5-10cm depth at 40℃.

[0105] Soil degradation experiments showed that the water-retaining gel could significantly slow down the rate of water evaporation and achieve 100% degradation within 32 days.

[0106] Experimental Example 2

[0107] Seed germination tests and germination index measurements were conducted on the water-retaining Scutellaria baicalensis granules prepared in Example 4. The results are shown in Table 1. Figure 4 As shown.

[0108] Table 1. Experimental Verification of the Granulation Coating Formulation of Huangqin Pill

[0109]

[0110] Note: Different lowercase letters in the same column indicate significant differences (P < 0.05).

[0111] Subsequently, its drought resistance was verified through application: an experimental group (granulated coated seeds) and a control group (naked seeds) were set up. The plant phenotypes were photographed and recorded after 0, 4, 8, and 12 days of water deprivation to observe the growth status, wilting degree, and drought resistance performance of Scutellaria baicalensis seedlings under drought stress. The results are as follows: Figure 5 As shown. Figure 5 The results showed that under continuous water shortage conditions, the seedlings in the experimental group were able to maintain a good external morphology and growth status, while the control group was almost completely withered.

[0112] Experimental Example 3

[0113] Germination and drought stress tests were conducted simultaneously on seeds from each treatment group in Example 5 and their corresponding bare-seed control groups. The results showed that the pelleting coating formula significantly promoted germination and enhanced seedling drought resistance in all five types of Chinese medicinal herbs. The germination rate, germination potential, and vigor index of each treatment group were significantly higher than those of their respective bare-seed control groups. Furthermore, under water shortage stress, the wilting degree of seedlings in the treatment groups was significantly lower than that in the control group, demonstrating good universality.

Claims

1. A water-retaining gel, characterized in that, This water-retaining gel is a material with a three-dimensional cross-linked network structure formed by cross-linking sodium carboxymethyl cellulose with urea.

2. The method for preparing the hydrogel according to claim 1, comprising the following steps: Sodium carboxymethyl cellulose was dissolved in a solvent, activated with an activator, and then urea was added and stirred to react. After the reaction was completed, the mixture was washed and dried to obtain a hydrogel.

3. The method for preparing the hydrogel according to claim 2, characterized in that, The solvent has a pH of 5-7; preferably, the sodium carboxymethyl cellulose is dissolved at a temperature of 20-30°C for 10-30 minutes.

4. The method for preparing the hydrogel according to claim 2, characterized in that, The material ratio of sodium carboxymethyl cellulose to urea is controlled according to the molar ratio of urea-NH2 to carboxymethyl cellulose-COOH of 1:1 to 2:

1.

5. The method for preparing the hydrogel according to claim 2, characterized in that, The activator is selected from one of the following combinations: A combination of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (EDC) and N-hydroxysuccinimide (NHS) in a molar ratio of 1:1 to 1:2; Alternatively, a combination of EDC and N-hydroxybenzimidazole (HOBt) in a molar ratio of 1:1 to 1:2; Alternatively, a combination of N,N'-dicyclohexylcarbodiimide (DCC), HOBt and N,N'-dimethylaminopyridine (DMAP) in a molar ratio of 1:1:1 to 1:2:4; Preferably, the amount of activator added is controlled at a molar ratio of 1:1 to 2:1 with sodium carboxymethyl cellulose; Preferably, the drying process employs vacuum drying or freeze drying.

6. A coating agent for granulation of traditional Chinese medicine seeds, comprising the water-retaining gel as described in claim 1, characterized in that, By weight, it includes the following components: 10 parts seeds, 40-60 parts inert filler, 3-6 parts hydrogel, and 0.2-0.6 parts binder.

7. The traditional Chinese medicine seed granulation coating agent according to claim 6, characterized in that, The seeds mentioned are Scutellaria baicalensis, Astragalus membranaceus, Glycyrrhiza uralensis, Salvia miltiorrhiza, Bupleurum chinense, or Perilla frutescens; Preferably, the inert filler is at least two of the following: talc, bentonite, activated carbon, diatomaceous earth, and vermiculite.

8. The seed granulation coating agent for traditional Chinese medicine according to claim 6, characterized in that, The adhesive is one of polyvinyl alcohol, methylcellulose, carboxymethylcellulose, gum arabic, or peach gum.

9. A method for preparing the seed granulation coating agent of traditional Chinese medicine according to any one of claims 6-8, comprising the following steps: The adhesive is mixed with water to prepare an adhesive solution with a mass concentration of 2% to 6%. The adhesive solution is sprayed onto the seed surface until it is moistened. Then, a portion of inert filler and water-retaining gel powder is added to coat the seed surface with powder. When the seed surface is coated with powder and appears loose, the adhesive solution is sprayed again and the mixed powder is added to continue coating. This process is repeated until all the mixed powder has been added. Then, the mixture is sieved and dried to obtain the seed pelleting coating agent for traditional Chinese medicine.

10. The use of the water-retaining gel according to claim 1 and / or the traditional Chinese medicine seed granulation coating agent according to any one of claims 6-8, characterized in that, Application in improving the germination rate of Chinese medicinal herbs and the drought resistance of seedlings in a semi-wild forest environment.

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