A multifunctional and efficient selenium-enriched foliar fertilizer for plants, its preparation method and application

Abstract

This invention discloses a multifunctional and efficient selenium-enriched foliar fertilizer for plants, its preparation method, and its application, belonging to the field of agricultural bio-fertilizer technology. The selenium-enriched foliar fertilizer is prepared by liquid fermentation of raw materials including water, rice bran, camellia seed meal, and sodium selenite using a compound microbial strain composed of Bacillus subtilis, Saccharomyces cerevisiae, and Lactobacillus plantarum. The foliar fertilizer prepared by this invention possesses multiple functions, including selenium enrichment, pest and disease control, and high adhesion. It significantly improves the spreading force and resistance to rain erosion on leaf surfaces, reduces nutrient loss, and significantly enhances the control effect on diseases such as rice blast and fertilizer utilization. Simultaneously, the organic selenium content reaches over 75% of the total selenium. This invention effectively solves the technical pain points of existing selenium-enriched foliar fertilizers, such as low selenium conversion rate, weak adhesion, single function, and reliance on chemical pesticides, demonstrating significant environmental friendliness and broad agricultural application prospects.

Description

Technical Field

[0001] This invention relates to the field of agricultural bio-fertilizer technology, and in particular to a multifunctional and efficient selenium-enriched foliar fertilizer for plants, its preparation method, and its application. Background Technology

[0002] Foliar fertilizer, as a highly efficient fertilization method, allows plants to directly absorb nutrients through their leaves, quickly responding to crop growth needs and playing a crucial role in improving crop yield and quality. It has been widely applied in modern agricultural planting systems. With the promotion of green and ecological agriculture concepts, traditional single-nutrient foliar fertilizers are no longer sufficient to meet diversified production needs. Multifunctional compound foliar fertilizers integrating nutrient supply, stress resistance induction, and pest and disease control have become a current research hotspot. Selenium, a beneficial trace element required for plant growth and also an essential nutrient for humans, can effectively increase the added value of agricultural products through foliar spraying of selenium-enriched fertilizers. However, existing selenium-enriched foliar fertilizers mostly use inorganic selenium or single organic selenium as the selenium source. In practical applications, these fertilizers suffer from low selenium conversion efficiency, poor stability, weak leaf adhesion, and easy erosion by rainwater after spraying, limiting the effective utilization of selenium and hindering the full realization of selenium enrichment and stress resistance effects. The reason for these problems lies in the lack of bioactive carriers in existing technologies that can promote the efficient conversion of selenium, and the insufficient adhesion of foliar fertilizers to the leaf surface, making it difficult for plants to fully absorb and utilize selenium.

[0003] On the other hand, agricultural pest and disease control still relies heavily on chemical pesticides. Long-term, excessive application leads to pesticide residue accumulation, environmental pollution, and increased pesticide resistance in pests and diseases, severely hindering sustainable agricultural development. To alleviate these problems, developing bio-based foliar fertilizers using natural active substances has become a key research focus. Tea saponins are natural non-ionic surfactants found in camellia oil cake, possessing excellent emulsifying, dispersing, and wetting functions, as well as antibacterial, insecticidal, and insecticidal activities. They are also environmentally friendly and residue-free. Glycoterpenes, on the other hand, are natural bioactive complexes composed of sugars, glycosides, and organic acids found in camellia oil kernel meal. They have strong surface adhesion activity, improving the adhesion and spreading performance of foliar fertilizers on leaf surfaces and reducing fertilizer loss. However, research on the combined use of tea saponins and glycoterpenes in foliar fertilizers is still relatively lacking, especially in improving the adhesion efficiency and functional synergy of selenium-enriched foliar fertilizers. Existing technologies struggle to simultaneously address the multiple technical challenges of low selenium conversion rates, weak adhesion, and reliance on chemical pesticides for pest and disease control.

[0004] In developing multifunctional foliar fertilizers that combine selenium enrichment, pest and disease control, and high adhesion properties, the challenges faced by those skilled in the art lie in: how to achieve synergistic fermentation of rice bran and camellia seed meal to promote the efficient dissolution of tea saponins and glycoterpenes; how to improve the organic conversion rate of inorganic selenium through compound microbial fermentation; and how to achieve synergistic effects of nutrient supply, pest and disease control, and high adhesion properties in a single product. Currently, there are no reports on combining rice bran, camellia seed meal, and selenium sources to prepare multifunctional foliar fertilizers with the above functions through liquid fermentation. Summary of the Invention

[0005] The purpose of this invention is to provide a multifunctional and efficient selenium-enriched foliar fertilizer for plants, its preparation method, and its application, thereby solving the problems existing in the prior art. This invention uses rice bran and camellia seed meal as raw materials, and produces a selenium-enriched foliar fertilizer through fermentation with a compound microbial strain. Through the synergistic effect of the antibacterial activity of tea saponins and the high adhesiveness of glycoterpenes, it significantly improves selenium conversion rate, resistance to rainwater erosion, and pest and disease control efficacy, solving the technical problems of existing foliar fertilizers having single functions and low selenium utilization rate. It also possesses environmental friendliness and broad application prospects. To achieve the above objectives, the present invention provides the following solution: This invention provides a multifunctional and efficient selenium-enriched foliar fertilizer for plants, which is prepared by liquid fermentation of the following raw materials using a compound microbial strain: Water, rice bran, camellia seed meal, and sodium selenite; The compound bacterial strain is Bacillus subtilis ( Bacillus subtilis ), brewer's yeast ( Saccharomyces cerevisiae ) and Lactobacillus plantarum ( Lactiplantibacillus plantarum () mixed strains.

[0006] Optionally, in the raw materials, the amount of rice bran is 3%-7% by weight of water, the amount of camellia seed meal is 12%-18%, and the amount of sodium selenite is 0.012%-0.015%.

[0007] Optionally, in the raw materials, the amount of rice bran is 7% by weight of water, the amount of camellia seed meal is 15% by weight, and the amount of sodium selenite is 0.015%.

[0008] Optionally, the ratio of viable Bacillus subtilis, Saccharomyces cerevisiae, and Lactobacillus plantarum is 1:1:1.

[0009] This invention also provides a method for preparing the aforementioned selenium-enriched foliar fertilizer, comprising the following steps: (1) Raw material pretreatment: Rice bran and camellia seed meal were crushed and sieved respectively; sodium selenite was dissolved in water to prepare a mother liquor; (2) Preparation of fermentation substrate: Water, pretreated rice bran and camellia seed meal are mixed evenly, sodium selenite mother liquor is added, and the mixture is stirred evenly to obtain the fermentation substrate; (3) Inoculation of microorganisms: Inoculate the compound microorganisms into the fermentation substrate, stir evenly, and carry out liquid fermentation; (4) Post-processing: Filter the fermentation liquid, collect the filtrate, sterilize and cool it to obtain the plant selenium-enriched foliar fertilizer.

[0010] Optionally, in step (1), the sieving is performed through a 40-60 mesh sieve; the concentration of the sodium selenite mother liquor is 0.12-0.15 g / L.

[0011] Optionally, in step (3), the inoculation amount of the compound strain is 3%-5% of the total solids weight in the fermentation substrate; the temperature of the fermentation substrate during inoculation is 28-32℃.

[0012] Optionally, in step (3), the temperature of the liquid fermentation is 28-32℃ and the fermentation time is 72-96 h.

[0013] This invention also provides the application of the plant selenium-enriched foliar fertilizer described above or the plant selenium-enriched foliar fertilizer prepared by the method described above in the prevention and control of crop diseases and pests or in improving the adhesion of foliar fertilizer to the surface of crop leaves.

[0014] Optionally, the crop includes rice; the pests and diseases include rice blast or rice sheath blight.

[0015] The present invention discloses the following technical effects: This invention uses rice bran and camellia seed meal as fermentation substrates, both of which are agricultural processing byproducts, widely available, and inexpensive, thus realizing the resource utilization of waste. Rice bran is rich in dietary fiber, which can loosen the fermentation system and promote the dissolution of sodium selenite during fermentation; camellia seed meal is rich in starch, protein, tea saponins, and glycoterpenes, providing the main carbon and nitrogen sources and functional components for fermentation. Through the synergistic fermentation of a compound strain of Bacillus subtilis, Saccharomyces cerevisiae, and Lactobacillus plantarum, not only are the raw materials efficiently decomposed to produce a large amount of free amino acids, but inorganic selenium is also efficiently converted into organic selenium (conversion rate of 75%~85%). At the same time, it promotes the full dissolution of tea saponins and glycoterpenes, giving the foliar fertilizer multiple functions, including nutrient supply, selenium enrichment, high adhesion and retention, and pest and disease control.

[0016] In the foliar fertilizer prepared by this invention, tea saponin, as a natural surfactant, possesses excellent emulsifying, dispersing, and antibacterial activities, capable of disrupting the cell membrane structure of pathogens and inhibiting disease spread. Glycoterpenes exhibit superior surface adhesion activity, significantly enhancing the spreading power and rain erosion resistance of the foliar fertilizer on leaf surfaces, reducing nutrient loss. The synergistic effect of these two components significantly improves the control effect of the foliar fertilizer on diseases such as rice blast, as well as fertilizer utilization, while simultaneously achieving an organic selenium content exceeding 75% of the total selenium. This invention effectively solves the technical pain points of existing selenium-enriched foliar fertilizers, such as low selenium conversion rate, weak adhesion, limited functionality, and reliance on chemical pesticides, demonstrating significant environmental friendliness and broad agricultural application prospects. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 Scanning electron microscope images of the adhesion of different foliar fertilizers to rice leaves; (a) is the leaf surface of the blank control group; (b) is the leaf surface of control group 1; (c) is the leaf surface of example 2 group; Figure 2 The diagram shows the antibacterial activity of different foliar fertilizers against Rhizoctonia solani. In the diagram, A represents Rhizoctonia solani treated as a blank control group; B represents Rhizoctonia solani treated as a control group 1; and C represents Rhizoctonia solani treated as a group in Example 2. Figure 3 Scanning electron microscope (SEM) images of the microstructure of Rhizoctonia solani after different foliar fertilizer treatments are shown below. Among them, A is the SEM image of the microstructure of Rhizoctonia solani after treatment with the blank control group; B is the SEM image of the microstructure of Rhizoctonia solani after treatment with control group 1; and C is the SEM image of the microstructure of Rhizoctonia solani after treatment with Example 2. Detailed Implementation

[0019] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0020] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0021] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0022] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0023] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0024] In the embodiments of the present invention, rice bran and camellia seed meal are both commercially available agricultural processing by-products, which are crushed and passed through a 40-60 mesh sieve for later use; sodium selenite is food grade with a purity of ≥99%; all reagents used are conventional commercially available reagents, and all equipment used are conventional laboratory or industrial production equipment.

[0025] In this invention, Bacillus subtilis (Bt) in the compound bacterial strain Bacillus subtilis ), brewer's yeast ( Saccharomyces cerevisiae ) and Lactobacillus plantarum ( Lactiplantibacillus plantarum All three can be obtained through regular commercial purchases, and are used in a live bacteria ratio of 1:1:1. In a specific embodiment of the present invention, Bacillus subtilis is selected from strain CGMCC No.1.1086, Saccharomyces cerevisiae is selected from strain CGMCC No.2.1042, and Lactobacillus plantarum is selected from strain CGMCC No.1.557.

[0026] Example 1 A multifunctional and efficient selenium-enriched foliar fertilizer for plants, with water as the base material, has the following components by weight percentage of water: 3% rice bran, 18% camellia seed meal and 0.0135% sodium selenite.

[0027] Its fermentation preparation method includes the following steps: Raw material pretreatment: Crush rice bran and camellia seed meal separately and pass them through a 50-mesh sieve to remove impurities; take sodium selenite, dissolve it in a small amount of deionized water, and prepare a 0.135g / L mother liquor for later use; Fermentation substrate preparation: Add 100 kg of water to the fermentation tank, turn on the stirring device, slowly add 3 kg of rice bran and 18 kg of camellia seed meal, stir until evenly dispersed, then add sodium selenite mother liquor, continue stirring for 5 min to obtain the fermentation substrate; Inoculation: Adjust the temperature of the fermentation substrate to 28℃, inoculate with the compound inoculum, and the inoculation amount is 4% (w / w) of the total solids weight. Stir well after inoculation. Liquid fermentation: The fermentation temperature was controlled at 28℃, and an aeration and stirring method was used with an aeration rate of 0.5 m³ / h. 3 The stirring speed was 120 r / min, the fermentation cycle was 84 h, and the pH value was monitored regularly during the period. When the pH value dropped to 3.8, the fermentation liquid had no odor and had a yeasty aroma, and the cell concentration was stable, the fermentation was stopped. Post-processing: Vacuum filter the fermentation broth through a 90-mesh filter (filtration pressure 0.03MPa) to remove solid residues and obtain a clarified fermentation broth; sterilize the clarified fermentation broth at 105℃ for 15 minutes and cool it to room temperature to obtain the finished foliar fertilizer; Packaging and storage: Dispense the finished product into sterile plastic bottles, seal them, and store them at 4°C.

[0028] Example 2 A multifunctional and efficient selenium-enriched foliar fertilizer for plants, with water as the base material, has the following components by weight percentage of water: 5% rice bran, 12% camellia seed meal, and 0.012% sodium selenite.

[0029] Its fermentation preparation method includes the following steps: Raw material pretreatment: Crush rice bran and camellia seed meal separately and pass them through a 50-mesh sieve to remove impurities; take sodium selenite, dissolve it in a small amount of deionized water to prepare a 0.12g / L mother liquor for later use; Fermentation substrate preparation: Add 100 kg of water to the fermentation tank, turn on the stirring device, slowly add 5 kg of rice bran and 12 kg of camellia seed meal, stir until evenly dispersed, then add sodium selenite mother liquor, continue stirring for 8 minutes to obtain the fermentation substrate; Inoculation: Adjust the fermentation substrate temperature to 30℃, inoculate with compound microbial strains, and the inoculation amount is 3% (w / w) of the total solids weight. Stir well after inoculation. Liquid fermentation: The fermentation temperature is controlled at 30℃, and a shaking fermentation method is adopted. The shaking speed is preferably 120r / min. The fermentation cycle is 96h. During the period, the pH value is monitored regularly. When the pH value drops to 4.2, the fermentation liquid has no odor and has a yeasty aroma, and the cell concentration is stable, the fermentation is stopped. Post-processing: Vacuum filter the fermentation broth through a 90-mesh filter (filtration pressure 0.04MPa) to remove solid residues and obtain a clarified fermentation broth; sterilize the clarified fermentation broth at 105℃ for 15 minutes and cool it to room temperature to obtain the finished foliar fertilizer; Packaging and storage: Dispense the finished product into sterile plastic bottles, seal them, and store them at 20°C.

[0030] Example 3 A multifunctional and efficient selenium-enriched foliar fertilizer for plants, with water as the base material, has the following components by weight percentage of water: 7% rice bran, 15% camellia seed meal, and 0.015% sodium selenite.

[0031] Its fermentation preparation method includes the following steps: Raw material pretreatment: Crush rice bran and camellia seed meal separately and pass them through a 50-mesh sieve to remove impurities; take sodium selenite, dissolve it in a small amount of deionized water, and prepare a 0.15g / L mother liquor for later use; Fermentation substrate preparation: Add 100 kg of water to the fermentation tank, turn on the stirring device, slowly add 7 kg of rice bran and 15 kg of camellia seed meal, stir until evenly dispersed, then add sodium selenite mother liquor, continue stirring for 10 min to obtain the fermentation substrate; Inoculation: Adjust the temperature of the fermentation substrate to 32℃, inoculate with the compound inoculum, and the inoculation amount is 5% (w / w) of the total solids weight. Stir well after inoculation. Liquid fermentation: The fermentation temperature was controlled at 32℃, and an aeration and stirring method was used with an aeration rate of 1.0 m³. 3 The stirring speed was 150 r / min, the fermentation cycle was 72 h, and the pH value was monitored regularly during the period. When the pH value dropped to 4.5, the fermentation liquid had no odor and had a yeasty aroma, and the cell concentration was stable, the fermentation was stopped. Post-processing: Vacuum filter the fermentation broth through a 90-mesh filter (filtration pressure 0.05MPa) to remove solid residues and obtain a clarified fermentation broth; sterilize the clarified fermentation broth at 105℃ for 15 minutes and cool it to room temperature to obtain the finished foliar fertilizer. Packaging and storage: Dispense the finished product into sterile plastic bottles, seal them, and store them at 25°C.

[0032] Comparative Example 1 The difference between this comparative example and Example 1 is that a single fermentation base material is used, namely, only camellia seed meal is used, and rice bran is not used. The remaining raw material ratios and preparation processes are completely consistent with Example 1.

[0033] The raw material is water-based, and the composition by weight percentage of water is as follows: 21% camellia seed meal and 0.0135% sodium selenite.

[0034] The specific preparation method for the fermentation substrate is as follows: Add 100 kg of water to the fermentation tank, turn on the stirring device, slowly add 21 kg of camellia seed meal (replacing the rice bran + camellia seed meal composite substrate in Example 1), stir until evenly dispersed, add sodium selenite mother liquor (same as in Example 1), and the subsequent inoculation, fermentation, post-treatment and storage steps are the same as in Example 1.

[0035] Comparative Example 2 The difference between this comparative example and Example 1 is that a single fermentation base material is used, namely, only rice bran is used, and camellia seed meal is not used. The remaining raw material ratios and preparation processes are completely consistent with Example 1.

[0036] The raw materials are water-based, and the composition by weight percentage of water is as follows: rice bran 21% and sodium selenite 0.0135%.

[0037] The specific preparation method for the fermentation substrate is as follows: Add 100 kg of water to the fermentation tank, turn on the stirring device, slowly add 21 kg of rice bran (replacing the rice bran + camellia seed meal composite substrate in Example 1), stir until evenly dispersed, add sodium selenite mother liquor (same as in Example 1), and the subsequent inoculation, fermentation, post-treatment and storage steps are the same as in Example 1.

[0038] Comparative Example 3 The difference between this comparative example and Example 1 is that a single-strain fermentation is used, that is, only Bacillus subtilis is used, and Saccharomyces cerevisiae and Lactobacillus plantarum are not used. The remaining raw material ratios and preparation processes are completely consistent with Example 1.

[0039] Prepare the raw materials according to the proportions in Example 1. In the inoculation step, only Bacillus subtilis (CGMCC No. 1.1086) is inoculated, and the inoculation amount is 4% (w / w) of the total solids weight. The subsequent fermentation, post-processing and storage steps are the same as in Example 1.

[0040] Experimental Example 1 The foliar fertilizer products prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to systematic performance testing and efficacy verification. All tests were performed in triplicate, and the average value was taken. Specific testing methods and parameters are as follows: 1. Determination of component content: Total selenium content: determined by inductively coupled plasma mass spectrometry (ICP-MS).

[0041] Organic selenium content: Inorganic selenium was removed by solvent extraction. The residue was digested with nitric acid and perchloric acid, and the total selenium content was determined. The organic selenium content and conversion rate (organic selenium / total selenium × 100%) were calculated by difference method.

[0042] Free amino acid content: The absorbance was measured at a wavelength of 570 nm using the ninhydrin colorimetric method with leucine as the standard.

[0043] Tea saponin content: The vanillin-sulfuric acid colorimetric method was used, and a standard curve was prepared using tea saponin standards. The content was measured at a wavelength of 470 nm.

[0044] Glycoterpenoid content: High performance liquid chromatography (HPLC) was used, with glycoterpenoid standards as a reference, and the content was calculated by external standard method based on peak area.

[0045] 2. Adhesion Test: Using a contact angle meter, the foliar fertilizer concentrate was diluted 50 times, and 2 μL was added to the surface of a fresh rice leaf using a micro-syringe. After standing for 30 seconds, the contact angle was measured. The smaller the contact angle, the stronger the wettability and adhesion of the foliar fertilizer.

[0046] 3. Rain erosion resistance test: Select rice plants of uniform growth (3-leaf stage), dilute the foliar fertilizer 50 times and spray it evenly until the leaves drip. After the leaves air dry naturally, place the plants under an artificial rainfall simulation device and rain them continuously at a rainfall intensity of 10 mm / h for 2 hours. Collect the leaves after rain, wash the surface with deionized water, measure the total nitrogen content in the washing solution, and compare it with the theoretical adhesion amount at the time of spraying to calculate the nutrient residue rate.

[0047] 4. Pest and disease control efficacy test: Rice blast was used as the target disease. Foliar fertilizer diluted 50 times was sprayed on the leaves of potted rice seedlings (4-5 leaf stage). 24 hours later, rice blast spore suspension (1×10⁻⁶) was manually sprayed inoculated. 5 After insulating with heat and moisture for 24 hours, the plants were placed in a greenhouse for routine management. The disease index was assessed 7 days later, and the relative control effect was calculated using the following formula: Control effect (%) = (Disease index of control group - Disease index of treatment group) / Disease index of control group × 100%.

[0048] The test results are summarized in Table 1.

[0049] Table 1. Performance test results of foliar fertilizers prepared in the examples and comparative examples. As shown in Table 1, the foliar fertilizers prepared in Examples 1-3 of this invention have significantly higher contents of total selenium, organic selenium conversion rate, free amino acids, tea saponins, and glycoterpenes than those in Comparative Examples 1-3. The foliar fertilizers prepared in Examples 1-3 consistently exhibit an organic selenium conversion rate of over 75% (up to 85.3%), a free amino acid content of 12-30 g / L, and are also rich in tea saponins (1.5-3.5 g / L) and glycoterpenes (2.0-4.0 g / L). This multi-functional characteristic allows the product of this invention to provide amino acid nutrition and organic selenium while simultaneously achieving excellent resistance to rainwater runoff (nutrient residue rate >90%) and significant pest and disease control effects (up to 82% control efficacy against rice blast) through the bioactivity of tea saponins and the adhesion and immune-inducing effects of glycoterpenes.

[0050] The fermentation substrate of Comparative Example 2 contained only rice bran, and its fermentation products did not contain tea saponins and glycoterpenes (both at 0 g / L), resulting in extremely low efficacy against rice blast and extremely low nutrient residue after simulated rain (20.3%). This directly confirms that camellia seed meal is the sole source of tea saponins and glycoterpenes in the foliar fertilizer of this invention, and is the key component that endows the foliar fertilizer with pest and disease control functions and high adhesion.

[0051] Experimental Example 2 To verify the advantages of the foliar fertilizer prepared in this embodiment of the invention in terms of physical properties and biological activity, this verification example systematically tests the interfacial properties, adhesion properties, and antibacterial activity of the foliar fertilizers prepared in Examples 1-3. A commercially available ordinary selenium-enriched foliar fertilizer (excluding tea saponins and glycoterpenes) was used as control group 1 (CK1), and water was used as a blank control (CK0). Specific test methods and parameters are as follows.

[0052] 1. Experimental Materials and Instruments Foliar fertilizer tested: Foliar fertilizer stock solution prepared in Examples 1-3; Control group 1 (commercially available ordinary selenium-enriched foliar fertilizer, selenium content 100mg / L, no surfactant); Blank control (distilled water).

[0053] Test plants: Grain-filling stage rice (variety: Xiangzaoxian 45), collected from experimental fields in Changsha City, Hunan Province, with healthy leaves from the middle of the plant growing uniformly selected.

[0054] Main instruments: interfacial tension meter, contact angle meter, scanning electron microscope, ultraviolet spectrophotometer, constant temperature incubator, freeze dryer.

[0055] 2. Testing Methods 2.1 Verification of interfacial tension and critical micelle concentration Surface tension measurement: The foliar fertilizer stock solution of each example and the control group was diluted 500 times with distilled water. The surface tension of the diluted solution was measured at (28±2)℃ using the maximum bubble pressure method. Each group was repeated 6 times and the average value was taken.

[0056] Critical micelle concentration verification: The diluted solution of the example group was further prepared into a series of concentration gradients (0, 0.1, 0.5, 1, 2, 5, 10, 20 mg / mL), the surface tension at each concentration was measured, and the surface tension-concentration logarithmic curve was plotted to determine the inflection point concentration.

[0057] 2.2 Verification of leaf wettability and adhesion Contact angle measurement: Fresh rice leaves were fixed flat on a glass slide with double-sided tape. 5 μL of the test diluent (diluted 500 times) was added using a microsyringe. The static contact angle was measured using a contact angle meter. Each group was repeated 5 times and the average value was taken.

[0058] Maximum stable holding capacity determination: The immersion weighing method was used. A 1 cm² rice leaf was cut, weighed (m1), and immersed in the diluent to be tested for 10 seconds. It was then removed, hung vertically, and weighed again (m2) when no more droplets fell. The maximum stable holding capacity (mg / cm³) was calculated using the formula Rm = (m2 - m1) / S × 1000. 2 ), repeat 5 times for each group.

[0059] Verification of resistance to rain erosion: The diluted solution was sprayed onto rice leaves, and after natural air drying, the leaves were placed under a simulated rainfall device (rain intensity 10 mm / h, rain for 2 hours). After air drying, the leaves were cut off, freeze-dried, sprayed with gold, and the morphology of fertilizer residues on the leaf surface was observed using a scanning electron microscope.

[0060] 2.3 Validation of antibacterial activity Preparation of drug-containing culture medium: The foliar fertilizer stock solution of each example and the control group (the examples need to be diluted to a final concentration of glycoterpenoids of 10 mg / mL, i.e., its CMC concentration) was filtered through a 0.22 μm filter membrane for sterilization. The sterilized PDA culture medium was cooled to 50°C, and the above filtrate was added at a ratio of 1:50. After shaking well, it was poured into plates.

[0061] Inoculation and culture: Take a well-activated Rhizoctonia solani mycelium cake (5 mm in diameter), inoculate it in the center of a plate, and incubate at 26℃ for 7 days.

[0062] Antibacterial rate calculation: The colony diameter was measured using the cross-cross method, and the antibacterial rate was calculated using the following formula.

[0063] Inhibition rate (%) = (colon diameter of blank control group - colony diameter of treatment group) / colony diameter of blank control group × 100.

[0064] Microscopic morphological observation of hyphae: Hyphae were picked from the edge of plates in the control group and the example group, fixed with glutaraldehyde, dehydrated in a gradient of ethanol, freeze-dried, and sputter-coated with gold. The changes in the microstructure of hyphae were then observed using scanning electron microscopy.

[0065] 3. Results and Analysis 3.1 Interface Performance Table 2 shows a comparison of the interfacial properties of different foliar fertilizers.

[0066] Table 2. Interfacial properties of different foliar fertilizers As shown in Table 2, the surface tension (34.01~36.12 mN / m) of the foliar fertilizers prepared in Examples 1-3 was significantly lower than that of Control Group 1 and the blank control group. This means that the foliar fertilizer of the present invention can spontaneously wet and spread on the surface of rice leaves after spraying, creating the preconditions for nutrient absorption.

[0067] 3.2 Adhesion and retention capacity Table 3 shows a comparison of the adhesion and retention capabilities of different foliar fertilizers.

[0068] Table 3 Adhesion and retention capacity of different foliar fertilizers As shown in Table 3, the maximum stable holding capacity of the example group reached 9.74 mg / cm³. 2 The fertilizer residue was 3.03 times that of control group 1. SEM observations further confirmed that after simulated rainwater washing, the rice leaves treated in the example group still had a dense fertilizer film layer, while the leaves of control group 1 had virtually no residue. Figure 1 This fully demonstrates that the glycoterpenoids in the foliar fertilizer of this invention exhibit excellent surface adhesion activity, enhancing the topological adhesion effect between the fertilizer and the leaves by forming a micelle network structure, and significantly improving the resistance to rainwater erosion.

[0069] 3.3 Antibacterial and bacteriostatic functions The antibacterial effects of different foliar fertilizers on Rhizoctonia solani in rice are as follows: Figure 2 As shown, the foliar fertilizer in Example 2 achieved an inhibition rate of 78.6% against Rhizoctonia solani, while the control group 1 (commercially available selenium-enriched fertilizer) had an inhibition rate of only 5.3%, showing almost no antibacterial effect. SEM microscopic morphology observations are shown below. Figure 3 As shown, the mycelia treated in Example 2 exhibited extensive shriveling, breakage, and leakage of contents, while the mycelia in Control Group 1 showed normal morphology and smooth surfaces. This indicates that the synergistic effect of tea saponins and glycoterpenes in the foliar fertilizer of this invention effectively disrupts the cell membrane structure of pathogens, inhibits mycelial growth, and achieves a green control effect by replacing chemical pesticides.

[0070] In summary, this invention, through a specific compounding of rice bran and camellia seed meal, utilizes the dietary fiber properties of rice bran to promote the release and transformation of functional components in camellia seed meal. Combined with deep liquid fermentation using compound microbial strains, it successfully prepares a multifunctional foliar fertilizer that integrates nutrient supply, high-efficiency selenium enrichment, high adhesion and retention, and biological control. This invention solves the technical pain points of existing technologies, such as single function, low selenium utilization rate, and reliance on chemical pesticides, and has significant progress and broad industrial application prospects.

[0071] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A multifunctional and efficient selenium-enriched foliar fertilizer for plants, characterized in that, The plant selenium-enriched foliar fertilizer is prepared from the following raw materials through liquid fermentation with compound microbial strains: Water, rice bran, camellia seed meal, and sodium selenite; The compound bacterial strain is Bacillus subtilis ( Bacillus subtilis ), brewer's yeast ( Saccharomyces cerevisiae ) and Lactobacillus plantarum ( Lactiplantibacillus plantarum () mixed strains.

2. The selenium-enriched foliar fertilizer for plants according to claim 1, characterized in that, Of the raw materials, the amount of rice bran is 3%-7% by weight of water, the amount of camellia seed meal is 12%-18%, and the amount of sodium selenite is 0.012%-0.015%.

3. The plant selenium-enriched foliar fertilizer according to claim 2, characterized in that, Of the raw materials, the amount of rice bran is 7% by weight of water, the amount of camellia seed meal is 15% by weight, and the amount of sodium selenite is 0.015%.

4. The selenium-enriched foliar fertilizer for plants according to claim 1, characterized in that, The ratio of viable Bacillus subtilis, Saccharomyces cerevisiae, and Lactobacillus plantarum is 1:1:

1.

5. A method for preparing a selenium-enriched foliar fertilizer for plants as described in any one of claims 1-4, characterized in that, Includes the following steps: (1) Raw material pretreatment: Rice bran and camellia seed meal were crushed and sieved respectively; sodium selenite was dissolved in water to prepare a mother liquor; (2) Preparation of fermentation substrate: Water, pretreated rice bran and camellia seed meal are mixed evenly, sodium selenite mother liquor is added, and the mixture is stirred evenly to obtain the fermentation substrate; (3) Inoculation of microorganisms: Inoculate the compound microorganisms into the fermentation substrate, stir evenly, and carry out liquid fermentation; (4) Post-processing: Filter the fermentation liquid, collect the filtrate, sterilize and cool it to obtain the plant selenium-enriched foliar fertilizer.

6. The preparation method according to claim 5, characterized in that, In step (1), the sieving is performed through a 40-60 mesh sieve; the concentration of the sodium selenite mother liquor is 0.12-0.15 g / L.

7. The preparation method according to claim 5, characterized in that, In step (3), the inoculation amount of the compound strain is 3%-5% of the total solids weight in the fermentation substrate; the temperature of the fermentation substrate during inoculation is 28-32℃.

8. The preparation method according to claim 5, characterized in that, In step (3), the temperature of the liquid fermentation is 28-32℃ and the fermentation time is 72-96 h.

9. The application of a selenium-enriched foliar fertilizer as described in any one of claims 1-4 or a selenium-enriched foliar fertilizer prepared by the preparation method described in any one of claims 5-8 in the prevention and control of crop diseases and pests or in improving the adhesion of foliar fertilizer to the surface of crop leaves.

10. The application according to claim 9, characterized in that, The crops mentioned include rice; the diseases and pests mentioned include rice blast or rice sheath blight.

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