Iron powder coating and coating method for rice seeds directly seeded in workmanship

Abstract

The invention discloses an iron powder coating for rice seeds directly seeded in workmanship, which comprises a rice seed body, the rice seed body is coated with an iron powder substrate layer, a water-sensitive bubble disintegration layer and a fungal spore active layer in sequence from inside to outside, and rice seed composite coated pellets are formed. Trichoderma fungi or endophytic fungi are selected as beneficial strains of the fungal spore active layer, and the problem that chemical agents and biological agents are incompatible is solved.

Description

Technical Field

[0001] This invention belongs to the field of seed treatment. Background Technology

[0002] Direct seeding of rice in anaerobic paddy fields is a highly efficient cultivation method, but when seeds germinate in the anaerobic environment, they face three major challenges:

[0003] Hypoxia stress: The water layer blocks the atmosphere, resulting in insufficient oxygen around the seeds, which severely inhibits germination and seedling growth, causing seed rot and weak seedlings.

[0004] Soil-borne diseases: Seeds that sink to the bottom of the water are susceptible to infection by soil-borne pathogens such as Fusarium and Rhizoctonia solani, leading to root rot and seedling blight.

[0005] Incompatibility between chemical and biological agents: Traditional seed coating technology struggles to coordinate chemical protection and biological control. To ensure germination, coatings often contain oxygen-providing agents such as calcium peroxide, pesticides, and iron powder. However, these substances, including chemical pesticides, the highly alkaline environment generated during oxidation, hydrogen peroxide, and OH free radicals, can inhibit or kill beneficial fungal spores used for biological control, resulting in a "1+1<2" effect, or even rendering the biological agents completely ineffective.

[0006] The lack of a solution in current technology to effectively isolate these functional components in time and space makes achieving simultaneous physical oxygen supply, chemical protection, and efficient biological control a challenge for the industry. Summary of the Invention

[0007] Purpose of the invention: In order to overcome the shortcomings of the existing technology, the present invention provides an iron powder coating for direct-seeded rice seeds and a coating method, which successfully solves the problem of incompatibility between chemical agents and biological agents.

[0008] Technical solution: To achieve the above objectives, the present invention provides an iron powder coating for direct-seeded rice seeds in Zhanshui, comprising a rice seed body, wherein the outer surface of the rice seed body is coated from the inside out with an iron powder base layer, a water-sensitive bubble disintegration layer and a fungal spore active layer, forming a composite coated rice seed pellet.

[0009] Furthermore, the beneficial fungal species selected for the fungal spore active layer are Trichoderma fungi or endophytic fungi.

[0010] Furthermore, the mass ratio of the rice seed body, the iron powder base layer, the water-sensitive bubble disintegration layer, and the fungal spore active layer is 65:25:6:4.

[0011] Furthermore, the iron powder base layer formulation, by weight:

[0012] Reduced iron powder: 60-80 parts;

[0013] Calcium peroxide: 10-15 parts;

[0014] Adhesive: 5-8 parts;

[0015] Insecticide: 1-3 parts;

[0016] Nutritional elements: 1-3 servings.

[0017] Furthermore, the water-sensitive bubble disintegration layer formulation, by weight:

[0018] Anhydrous citric acid: 40-45 parts;

[0019] Sodium bicarbonate: 35-40 parts;

[0020] Fumaric acid: 5-8 parts;

[0021] Polyvinylpyrrolidone K30: 3-5 parts;

[0022] Crosslinked carboxymethyl cellulose sodium: 4-6 parts;

[0023] Micronized silica gel: 1-2 parts.

[0024] Furthermore, the fungal spore active layer formulation, by weight:

[0025] Porous carrier spore carrier: 70-75 copies;

[0026] Highly active fungal spore powder: 1-1.5 parts

[0027] Xanthan gum: 17-20 parts

[0028] Glucose: 2-4 portions.

[0029] Iron powder base layer process: Rice seeds are placed in a rotating coating machine, and the adhesive is evenly sprayed onto the tumbling seed surface through atomizing nozzles; then, insecticide and nutrient element powders are added; then, a mixture of calcium peroxide and reduced iron powder is added evenly to the tumbling seeds; under the action of the adhesive and the machine's rotation, the dry powder gradually and evenly adheres to the moist seed surface; during the powder addition process, the coating machine continues to rotate, and through friction and collision between seeds and between seeds and the pot wall, the coating layer is continuously compacted, and the surface becomes smooth and dense; at the same time, a micro-heating or suction device is used to slowly remove excess moisture during or at the end of the process, allowing the coating to solidify and set; after coating, the seeds are removed and spread out in a ventilated, cool environment for final curing and drying to ensure that the coating hardness meets the requirements.

[0030] Water-sensitive bubble disintegration layer process: All raw materials for the water-sensitive bubble disintegration layer, except for polyvinylpyrrolidone K30, are vacuum dried at 40-45℃ for 4 hours to completely remove moisture. Citric acid, sodium bicarbonate, and fumaric acid are pulverized through a 200-mesh sieve to ensure fine and uniform particles. The dried citric acid, sodium bicarbonate, fumaric acid, and micronized silica gel are placed in a low-speed mixer according to the formula ratio. The mixing time is 15-20 minutes to ensure uniformity. Under continuous stirring, an anhydrous ethanol solution of polyvinylpyrrolidone K30 is slowly sprayed. The mixture is then granulated by sieving. The wet granules are vacuum dried at a low temperature (<40℃) until the moisture content is below 1%. After drying, the granules are sieved again to obtain uniform effervescent granules. Using a dedicated coating device, the effervescent granules are sprayed onto an iron powder substrate layer of rice seeds to form a uniform water-sensitive bubble disintegration layer.

[0031] The process flow for the fungal spore active layer is as follows: Pre-mix precisely weighed dry spore powder and porous spore carrier evenly in a mixer, then thoroughly mix with glucose; prepare a 1% aqueous solution of xanthan gum, and slowly spray it into the mixed dry material in a mist form. Control the liquid volume to form uniform wet granules; rapidly dry at a low temperature (<35℃) until the moisture content is below 5%, then sieve and granulate to obtain free-flowing "spore-carrier" composite granules.

[0032] In a coating pan, a very dilute xanthan gum solution is sprayed onto the surface of rice seeds that have already undergone the water-sensitive bubble disintegration layer, serving as a "base liquid." Simultaneously, the aforementioned composite particles are added and rolled evenly. Finally, the seeds are thoroughly air-dried at a low temperature.

[0033] A water-soluble isolation membrane is placed between the iron powder substrate layer and the water-sensitive bubble disintegration layer.

[0034] Beneficial effects: The core innovation of this invention lies in the design of a multi-layer coating structure with temporal response and spatial separation functions, which successfully solves the problem of incompatibility between chemical agents and biological agents.

[0035] The specific innovations are as follows:

[0036] This invention features a pioneering three-layer coating structure: an iron powder base layer, a water-sensitive bubble disintegration layer, and a fungal spore activity layer. This structure achieves spatially ordered separation of functions through the sequential responses of each layer upon contact with water. The outer layer of fungal spores is rapidly dispersed into the soil, away from the seeds, by the bubble disintegration layer; the inner iron powder base layer then slowly releases oxygen and the pesticide, with both layers working synergistically without interference.

[0037] Mechanism innovation: A "water-sensitive bubble disintegration layer" is introduced as a key layer for isolation and active dispersal.

[0038] This layer is not only a physical barrier but also a functional activation layer. Upon contact with water, it rapidly generates a large number of bubbles through an acid-base reaction, and, in conjunction with the expansion force of the superabsorbent resin, achieves an expansionary collapse. This process actively "pushes" the outer fungal spore-active layer away from the seed surface, causing it to form a high-concentration "spore cloud" at the mud-water interface and improving the looseness of the soil near the seed. This is the key to achieving the physical spatial separation of spores from the inner layer's harmful chemical environment.

[0039] Innovative compatibility: It solved the compatibility problem between oxygen supply / chemical protection systems and biological control systems.

[0040] Through the aforementioned structure and mechanism, this scheme successfully integrates the iron powder-calcium peroxide oxygen supply system with highly active fungal spores onto the same seed. This completely avoids the inactivation effects of alkaline substances, hydrogen peroxide, free radicals, and chemical pesticides produced by iron powder oxidation and calcium peroxide decomposition on beneficial fungal spores, thus achieving a combination of "chemical seedling protection" and "biological root protection."

[0041] Iron powder base layer: The ratio and addition order of reduced iron powder, calcium peroxide, binder, pesticide and nutrients were optimized to ensure the water-sinking property, mechanical strength and slow release of functional components of the coating.

[0042] Water-sensitive bubble disintegration layer: It adopts a citric acid-fumaric acid "fast and slow combination" acid source system and uses anhydrous ethanol solvent process to ensure stability during production and storage and rapid disintegration after contact with water.

[0043] Fungal spore active layer: A porous carrier is used to adsorb high concentrations of spore powder, with xanthan gum as a binder and glucose as a germination promoter. This achieves efficient spore loading and rapid colonization while ensuring spore activity. Attached Figure Description Figure 1 It has an iron powder coating structure. Detailed Implementation

[0044] The invention will now be further described with reference to the accompanying drawings.

[0045] The iron powder coating of direct-seeded rice seeds in Zhanshui consists of the rice seed itself, which is then coated from the inside out with an iron powder base layer, a water-sensitive bubble disintegration layer, and a fungal spore activity layer, forming composite coated pellets. Figure 1 Figure 1 In this context, A, B, and C refer to the iron powder base layer, the water-sensitive bubble disintegration layer, and the fungal spore active layer, respectively.

[0046] Through the multi-layer coating structure design, the synergistic effect of physical protection, chemical oxygen supply and biological control is achieved. In particular, the innovative introduction of a water-sensitive bubble disintegration layer solves the problem of the inner iron powder base layer chemical substance inhibiting the outer fungal spores, thus ensuring the colonization efficiency of beneficial fungi.

[0047] In this scheme, the beneficial fungal species for the active layer of fungal spores are selected from Trichoderma fungi or endophytic fungi. Trichoderma fungi directly inhibit pathogens through parasitism and competition mechanisms, while endophytic fungi enhance the host's resistance through systemic symbiosis. Both can adapt to the rice growth environment, and their spores have strong storage tolerance, making them suitable for coating processes.

[0048] Trichoderma fungi, such as *Trichoderma harzianum* and *Trichoderma viride*, can rapidly colonize rice seeds and roots with their spores. By competing for nutrients and space, they directly parasitize or inhibit the growth of various soil-borne pathogens, such as *Fusarium* and *Rhizoctonia solani*. Simultaneously, they secrete substances that stimulate plant growth and enhance crop tolerance to adverse conditions (such as salinity and drought). In coating designs, *Trichoderma* spores germinate first, establishing a reliable biological protective barrier for seedlings.

[0049] Endophytic fungi: such as some strains of the genus *Chaetoceros* isolated from wild rice or healthy plants, can promote plant growth and enhance the host's resistance to biotic and abiotic stresses. Integrating these beneficial endophytic fungal spores into a coating allows them to establish a symbiotic relationship with rice seedlings at an early stage.

[0050] When these rice seed pellets are placed in a flooded paddy field and sink to the bottom, the outermost layer of fungal spores on the seed absorbs water and becomes loose. As the water further penetrates the water-sensitive bubble disintegration layer, it rapidly disintegrates and releases a large number of bubbles. This disintegration causes the outermost layer of fungal spores to collapse outwards, detaching and combining with nearby soil or adhering to the nearby water surface in a collapsed manner. Simultaneously, as a large number of bubbles escape, the fungal spores in the active layer form a localized, high-concentration spore cloud at the mud-water interface around the seed, facilitating rapid and concentrated contact between the spores and soil particles to seize ecological niches. Furthermore, the large number of bubbles also makes the soil near the seed more porous and loose, increasing its overall looseness. When the iron powder substrate comes into contact with water, the iron powder in the substrate gradually undergoes an oxidation reaction. The calcium peroxide in the iron powder substrate decomposes and stably releases oxygen. At the same time, other nutrients and pesticides in the iron powder substrate formula are released and take effect.

[0051] The core working principle of this invention lies in the temporal and spatial separation mechanism: the water-sensitive bubble disintegration layer reacts rapidly upon contact with water, and through bubble generation and disintegration, it preferentially pushes the fungal spore active layer away from the seed surface, allowing it to disperse into the soil before the iron powder base layer releases potentially harmful substances, thereby avoiding damage to the spores by chemicals; at the same time, the iron powder base layer then slowly releases oxygen and nutrients, supporting seed germination and seedling growth. This stratified response design ensures the independent and efficient operation of biological and chemical components.

[0052] The core function of the water-sensitive bubble disintegration layer is that, after entering the water, the fungal spore active layer will first disperse and fully detach from the iron powder base layer under the action of bubble disintegration in the water-sensitive bubble disintegration layer, and combine with the mud-water interface, effectively preventing the substances slowly released by the innermost iron powder base layer after encountering water from destroying the activity of the fungal spore active layer.

[0053] Without the water-sensitive bubble disintegration layer, the following problems would exist:

[0054] The insecticide slowly released by the iron powder base layer when it comes into contact with water will inhibit or kill the beneficial fungal spores in the vicinity, and continuously inhibit the germination of beneficial spores and mycelial growth in the fungal spore active layer;

[0055] When calcium peroxide in the iron powder base layer comes into contact with water, it generates hydrogen peroxide (H2O2) and oxygen, which can oxidize the cell membrane lipids of beneficial spores in the fungal spore active layer, leading to increased membrane permeability and leakage of contents; it also damages the sulfhydryl groups and disulfide bonds of proteins, causing enzyme denaturation and inactivation; at the same time, the generated calcium hydroxide will form a persistent high-alkaline environment nearby, which will also inhibit the germination of beneficial spores and hyphal growth in the fungal spore active layer.

[0056] When the iron powder substrate comes into contact with water, the iron powder itself will generate highly reactive ·OH free radicals through the Fenton reaction in the presence of water and oxygen. This is similar to the principle of calcium peroxide, which will cause severe oxidative damage to the fungal spores in the active layer of fungal spores.

[0057] Through the aforementioned temporal and physical spatial separation, the iron powder, calcium peroxide, and chemical pesticides in the iron powder substrate layer exert their physical and chemical protective effects in the inner layer, while the beneficial fungal spores in the fungal spore active layer are kept away from these harmful environments and can safely enter the soil for colonization. This separation mechanism not only protects the fungal spores but also optimizes resource utilization: the bubble generation in the bubble disintegration layer enhances the uniformity and range of spore dispersion, while the slow oxidation of the iron powder substrate layer provides a continuous oxygen supply, solving the common oxygen deficiency problem in direct-seeded rice, thereby improving the overall seed survival rate and disease resistance.

[0058] In this design, the mass ratio of the rice seed body, iron powder base layer, water-sensitive bubble disintegration layer, and fungal spore active layer is 65:25:6:4. This ensures a balance of mechanical strength, functional layer thickness, and weight in the coating. The iron powder base layer provides sufficient weight for the seed to sink in water, while the water-sensitive bubble disintegration layer and fungal spore active layer maintain the minimum necessary thickness for rapid response, while avoiding excessive coating that could affect seed germination.

[0059] Iron powder base layer formulation, by weight:

[0060] Reduced iron powder: 60-80 parts;

[0061] Function: It serves as the skeleton and main filler material of the coating. It provides the main weight, ensuring that the seeds can sink into the mud, and also constitutes the physical structure of the coating.

[0062] Calcium peroxide: 10-15 parts;

[0063] Function: It serves as the functional core of the seed coating. It decomposes in water, continuously providing oxygen for seed germination, and is key to solving the problem of underwater hypoxia.

[0064] Adhesive: 5-8 parts (such as polyvinyl alcohol or sodium carboxymethyl cellulose)

[0065] Function: To firmly bind iron powder, calcium peroxide, etc. to the surface of seeds.

[0066] Insecticide: 1-3 parts, imidacloprid;

[0067] Function: To prevent underground pests from attacking tender seeds and seedlings.

[0068] Nutrients: 1-3 parts (potassium dihydrogen phosphate, zinc fertilizer or trace element compounds);

[0069] Function: Serves as an initial nutrient reserve for seed coating. Provides easily absorbed, fast-acting nutrients during the early stages of seedling growth, helping to cultivate strong seedlings.

[0070] Iron powder substrate process flow:

[0071] Selected rice seeds are placed into a rotating coating machine. Adhesive is evenly sprayed onto the tumbling seed surface through atomizing nozzles. Then, pesticide and nutrient powders are added; adding them first ensures more even distribution on the seed surface, rather than being covered by a large amount of iron powder later. Next, a mixture of calcium peroxide and reduced iron powder is added evenly to the tumbling seeds. Under the action of the adhesive and the machine's rotation, these dry powders gradually and evenly adhere to the moist seed surface. During the powder addition process, the coating machine continues to rotate, and the friction and collision between seeds and between seeds and the pot wall continuously compacts the coating layer. The surface becomes smooth and dense. To achieve the required coating thickness and weight, the process of "spraying adhesive - adding powder - rolling" usually needs to be repeated multiple times. At the same time, a gentle breeze or suction device is used to slowly remove excess moisture during or at the end of the process, allowing the coating to solidify and set, but the temperature should not be too high to avoid damaging the activity of calcium peroxide and biological agents. After coating, the seeds are taken out and spread in a ventilated, cool environment for final curing and drying to ensure that the coating hardness meets the requirements. A low-mesh sieve is used to remove any debris and clumps that may fall off, ensuring the cleanliness of the finished product. This completes the coating process of the iron powder base layer.

[0072] Water-sensitive bubble disintegration layer formulation, by weight:

[0073] Anhydrous citric acid: 40-45 parts; the product after the reaction is sodium citrate, which is microbial and environmentally friendly. Use the anhydrous form to avoid moisture absorption during storage.

[0074] Sodium bicarbonate: 35-40 parts; the molar reaction ratio with citric acid is approximately 1:0.7. A slight excess of sodium bicarbonate in this formula can make the microenvironment weakly alkaline to neutral after the reaction, thus avoiding strong acid stress on some fungal spores.

[0075] Fumaric acid: 5-8 parts; Fumaric acid has poor water solubility, which can slow down the reaction rate and form a "fast-slow combination" acid source system with citric acid, making gas production more persistent and disintegration more thorough, avoiding excessively violent one-time reaction that could cause splashing.

[0076] Polyvinylpyrrolidone K30: 3-5 parts; Form: Use 8%-10% anhydrous ethanol solution as a granulation wetting agent. It has good solubility in anhydrous ethanol, and ethanol will not cause acid-base reactions, ensuring stability in the production process. It has good film-forming properties and can give the effervescent layer sufficient mechanical strength.

[0077] Crosslinked sodium carboxymethyl cellulose: 4-6 parts; while generating gas to tear the structure during the effervescent reaction, it can rapidly absorb water and expand, generating secondary expansion force, which forms a synergistic effect with the gas pressure to ensure disintegration without residue.

[0078] Micronized silica gel: 1-2 parts; extremely hygroscopic, it adsorbs trace amounts of moisture that may be present during production, protecting the stability of the effervescent system. It also acts as a good flow aid, improving powder flowability.

[0079] The working principle of the water-sensitive bubble disintegration layer is based on the synergistic effect of gas generation from acid-base reactions and polymer expansion: upon contact with water, citric acid and sodium bicarbonate react rapidly to generate carbon dioxide bubbles, while fumaric acid slows down the reaction, resulting in more uniform bubble release; at the same time, cross-linked sodium carboxymethyl cellulose absorbs water and swells, intensifying the disintegration of the layered structure, thereby pushing the fungal spore active layer away from the seed surface; this design ensures rapid and thorough disintegration, avoiding residues that could hinder seed germination.

[0080] Water-sensitive bubble disintegration layer process flow:

[0081] All raw materials (except polyvinylpyrrolidone K30) were vacuum dried at 40-45℃ for 4 hours to completely remove moisture. Citric acid, sodium bicarbonate, and fumaric acid were then pulverized through a 200-mesh sieve to ensure fine and uniform particles.

[0082] Place the dried citric acid, sodium bicarbonate, fumaric acid, and micronized silica gel into a low-speed mixer according to the formula ratio. The mixing equipment must be grounded to prevent static electricity. Mix for 15-20 minutes to ensure uniformity.

[0083] While continuously stirring, a solution of anhydrous ethanol in polyvinylpyrrolidone K30 is slowly sprayed. The amount of ethanol is controlled to form a soft material that "clumps when squeezed but crumbles easily when pressed." The granules are then sieved through a 20-mesh sieve. The wet granules are vacuum dried at a low temperature (<40℃) until the moisture content is below 1% (determined by Karl Fischer method). After drying, the granules are sieved through a 20-mesh sieve again to obtain uniform effervescent granules. Using a specialized coating device, the effervescent granules are sprayed onto an iron powder substrate layer of rice seeds to form a uniform water-sensitive bubble disintegration layer.

[0084] Fungal spore active layer formulation, by weight:

[0085] Porous spore carriers: 70-75 parts, such as vermiculite powder or diatomaceous earth; are key to achieving physical protection and uniform dispersion of spores. These materials can adsorb spores, buffer mechanical shock, and release them rapidly in water.

[0086] Highly active fungal spore powder: 1-1.5 parts: This ensures that each seed carries a sufficient number of spores (target: 10^5-10^6 CFU / seed). Using a high concentration of spore powder instead of liquid inoculant is to avoid introducing excessive moisture, ensuring the dryness and storage stability of this layer.

[0087] Xanthan gum (dry basis): 17-20 parts: Purpose: The higher amount of xanthan gum is required because it is needed to firmly adhere the lightweight carrier and spores to the water-sensitive bubble-disintegrating layer. After drying, it forms a tough but water-soluble film that prevents powdering during storage and does not hinder the shedding and dispersion of the spore layer when needed.

[0088] Glucose: 2-4 parts: Purpose: To provide the "first energy" to stimulate spores to quickly break dormancy and germinate once they enter the soil environment, thus seizing their ecological niche. This ratio is effective while avoiding excessive amounts that could become a "culture medium" for other microorganisms.

[0089] Fungal spore active layer process flow:

[0090] Dry mixing: Pre-mix the precisely weighed spore powder and porous carrier spore carrier evenly in a small mixer, and then mix them thoroughly with glucose.

[0091] Granulation: Xanthan gum is prepared into a 1% aqueous solution and slowly sprayed into the mixed dry material in the form of atomization. The liquid volume is controlled to form uniform wet granules. The granules are then rapidly dried at a low temperature (<35℃) until the moisture content is below 5%, and then sieved and granulated to obtain free-flowing "spore-carrier" composite granules.

[0092] Coating: In a coating pan, a very dilute xanthan gum solution is sprayed onto the surface of the rice seeds, which have already undergone the water-sensitive bubble disintegration layer, as a "base liquid." Simultaneously, the aforementioned composite granules are added and rolled evenly. Finally, the seeds are thoroughly air-dried at a low temperature.

[0093] In a preferred embodiment, a water-soluble barrier membrane can be placed between the iron powder substrate layer and the water-sensitive bubble-disintegrating layer. This barrier membrane is made of water-soluble polymers such as polyvinyl alcohol or hydroxypropyl methylcellulose. Its function is to form a physical barrier between the iron powder substrate layer and the water-sensitive bubble-disintegrating layer, preventing moisture penetration during storage and preventing pre-reactions. Simultaneously, it dissolves rapidly in an aqueous environment, ensuring timely activation of the bubble-disintegrating layer. This further enhances the stability and functional reliability of the coating and is an important supplement to optimizing the time-sequential separation mechanism.

[0094] To verify the effectiveness of this multi-layer coated pelleting method, a comparative experiment was designed to simulate a direct seeding environment in Zhanshui, observing seed germination, seedling growth, and disease incidence under different treatments. Experimental conditions: soil taken from paddy fields was used in a temperature- and light-controlled incubator, maintaining a water layer of 3-5 cm to simulate a field environment. Each treatment was repeated three times. Germination rate was recorded on day 7 after sowing, and various indicators were evaluated on day 15.

[0095] The experimental design is shown in the table below:

[0096]

[0097] Comparison of key indicators among treatment groups on day 15 post-sowing:

[0098]

[0099] Conclusion Analysis:

[0100] The control group (A) had a higher rate of seed rot due to lack of oxygen and disease.

[0101] Traditional iron powder coating (B) provides oxygen, but the chemical agents may cause slight toxicity to the embryos and there is no biological protection, resulting in a lower germination rate than the control group. The rate of seed rot is improved but not completely.

[0102] This scheme (C) significantly improved the germination rate and minimized the seed rot rate by synergistic oxygen supply (iron powder + calcium peroxide) and the priority establishment of a biological protective barrier of fungal spores, demonstrating its comprehensive seedling protection capabilities.

[0103] Biological control effect:

[0104] The disease index directly reflects the effectiveness of biological control. The disease index of this scheme (C) was significantly lower than that of the other two groups. This is attributed to the successful colonization of the fungal spore active layer by the disintegration layer, which effectively inhibited soil-borne pathogens.

[0105] Spore germination rate is key evidence of the success of this method. Traditional iron powder coating (B) almost completely inhibits the germination of exogenous spores due to the chemical substances released inside and the alkaline environment. In contrast, this method creates a safe germination environment for spores through the "spatiotemporal isolation" mechanism of the bubble disintegration layer, resulting in a germination rate of over 70%.

[0106] Seedlings from scheme (C) showed the best performance in both plant height and root length. This was due to: improved root respiration and energy metabolism; reduced disease damage to the roots through biological control; and growth hormones secreted by beneficial fungi such as Trichoderma promoting seedling growth.

[0107] Overall benefit comparison:

[0108]

[0109] Compared with existing technologies, this solution, through its innovative multi-layer structure design, especially the introduction of a water-sensitive bubble disintegration layer, not only solves the compatibility problem between beneficial fungal spores and inner chemical substances, but also optimizes the colonization environment of spores through an active dispersal mechanism. Ultimately, it achieves a breakthrough effect of synergistic synergy in germination rate, disease control, and seedling growth promotion, fully demonstrating its creativity and practicality.

[0110] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An iron powder coating method for direct-seeded rice seeds, characterized in that: The rice seed body is coated with an iron powder base layer, a water-sensitive bubble disintegration layer, and a fungal spore activity layer from the inside out, forming a composite coated rice seed pellet.

2. The iron powder coating method for direct-seeded rice seeds in Zhanshui according to claim 1, characterized in that: Beneficial fungal species for the active layer of fungal spores are selected from Trichoderma fungi or endophytic fungi.

3. The iron powder coating method for direct-seeded rice seeds in Zhanshui according to claim 1, characterized in that: Iron powder base layer formulation, by weight: Reduced iron powder: 60-80 parts; Calcium peroxide: 10-15 parts; Adhesive: 5-8 parts; Insecticide: 1-3 parts; Nutritional elements: 1-3 servings.

4. The iron powder coating method for direct-seeded rice seeds in Zhanshui according to claim 1, characterized in that: Water-sensitive bubble disintegration layer formulation, by weight: Anhydrous citric acid: 40-45 parts; Sodium bicarbonate: 35-40 parts; Fumaric acid: 5-8 parts; Polyvinylpyrrolidone K30: 3-5 parts; Crosslinked carboxymethyl cellulose sodium: 4-6 parts; Micronized silica gel: 1-2 parts.

5. The iron powder coating method for direct-seeded rice seeds in Zhanshui according to claim 1, characterized in that: Fungal spore active layer formulation, by weight: Porous carrier spore carrier: 70-75 copies; Highly active fungal spore powder: 1-1.5 parts Xanthan gum: 17-20 parts Glucose: 2-4 portions.

6. The iron powder coating method for direct-seeded rice seeds in Zhanshui according to claim 1, characterized in that: The mass ratio of the rice seed body, iron powder base layer, water-sensitive bubble disintegration layer and fungal spore active layer is 65:25:6:

4.

7. A coating process for iron powder coating of direct-seeded rice seeds, characterized in that: Iron powder base layer process: Rice seeds are placed in a rotating coating machine, and the adhesive is evenly sprayed onto the tumbling seed surface through atomizing nozzles; then, insecticide and nutrient element powders are added; then, a mixture of calcium peroxide and reduced iron powder is added evenly to the tumbling seeds; under the action of the adhesive and the machine's rotation, the dry powder gradually and evenly adheres to the moist seed surface; during the powder addition process, the coating machine continues to rotate, and through friction and collision between seeds and between seeds and the pot wall, the coating layer is continuously compacted, and the surface becomes smooth and dense; at the same time, a micro-heating or suction device is used to slowly remove excess moisture during or at the end of the process, allowing the coating to solidify and set; after coating, the seeds are removed and spread out in a ventilated, cool environment for final curing and drying to ensure that the coating hardness meets the requirements.

8. The coating process for iron powder coating of direct-seeded rice seeds in Zhanshui according to claim 7, characterized in that: Water-sensitive bubble disintegration layer process: The water-sensitive bubble disintegration layer raw materials, except for polyvinylpyrrolidone K30, are vacuum dried at 40-45℃ to completely remove moisture; citric acid, sodium bicarbonate, and fumaric acid are pulverized and sieved separately; the dried citric acid, sodium bicarbonate, fumaric acid, and micronized silica gel are placed in a low-speed mixer according to the formula ratio; the mixing time is 15-20 minutes. Under continuous stirring, an anhydrous ethanol solution of polyvinylpyrrolidone K30 is slowly sprayed; the wet granules are vacuum dried at a low temperature (<40℃) until the moisture content is less than 1%; after drying, they are sieved again to obtain uniform effervescent granules; using a coating device, the effervescent granules are sprayed onto the iron powder base layer of rice seeds to form a uniform water-sensitive bubble disintegration layer.

9. The coating process for iron powder coating of direct-seeded rice seeds in Zhanshui according to claim 8, characterized in that: The process flow of fungal spore active layer is as follows: Pre-mix the precisely weighed spore powder and porous carrier spore carrier evenly in a mixer, and then mix them thoroughly with glucose; prepare a 1% aqueous solution of xanthan gum, and slowly spray it into the mixed dry material in the form of atomization to form uniform wet particles; quickly dry it at a low temperature (<35℃) until the moisture content is less than 5%, and then sieve and granulate to obtain "spore-carrier" composite particles with good flowability; In a coating pan, a very dilute xanthan gum solution is sprayed onto the surface of rice seeds that have already undergone the water-sensitive bubble disintegration layer as a "base liquid," while the aforementioned composite particles are added simultaneously and rolled evenly. Finally, the seeds are thoroughly air-dried at a low temperature.

10. The iron powder coating method for direct-seeded rice seeds in Zhanshui according to claim 1, characterized in that: A water-soluble isolation membrane is placed between the iron powder substrate layer and the water-sensitive bubble disintegration layer.

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