A microbial organic fertilizer for promoting rice growth and resisting bacteria

Abstract

This application relates to a microbial organic fertilizer for promoting rice growth and inhibiting bacterial growth. It promotes the absorption and utilization of nitrogen and phosphorus nutrients by significantly upregulating the expression of specific functional genes in plants, while enhancing the disease resistance of plants. It has broad application prospects in agricultural production.

Description

Technical Field

[0001] This application belongs to the field of agricultural biotechnology, specifically relating to a microbial organic fertilizer that promotes rice growth and has antibacterial properties. Background Technology

[0002] As one of the world's most important food crops, rice's yield and quality directly impact human food security. With continuous population growth and increasing scarcity of arable land resources, improving rice yield and disease resistance has become a crucial research topic in agriculture. While traditional chemical fertilizer application can increase rice yield in the short term, long-term excessive use can lead to soil compaction, decreased fertility, and environmental pollution, hindering sustainable agricultural development. Therefore, exploring green, environmentally friendly, and efficient compound fertilizers (such as organic fertilizers and microbial fertilizers) is particularly urgent.

[0003] Traditional research focuses on the direct effects of compound fertilizers on plant growth phenotypes, often resulting in inconsistent effects depending on the application of compound fertilizers to crops under different growth conditions. Without understanding the intrinsic mechanisms of plant responses to fertilizers, such as which functional genes are regulated by fertilizers, it is difficult to identify the root causes of these differences and find quick solutions. However, studying the effects of compound fertilizers on plant gene regulation and combining this with phenotypic analysis can deepen our understanding of plant growth mechanisms, offering far-reaching application value and providing crucial theoretical support for precision agriculture, genetic engineering, and sustainable agricultural development.

[0004] Rice contains tens of thousands of functional genes. Among them, the genes OsMGD2 and OsMGD3 encode monogalactosylglycerol synthase (MGD), which mainly participates in the synthesis of galactolipases (MGDG and DGDG) in non-photosynthetic tissues (such as roots and flowers), thereby improving photosynthetic efficiency and biomass. The gene OsSAE1a is involved in the absorption, transport, and redistribution of phosphorus and nitrogen, and may play a key role in rhizosphere phosphorus activation and nitrogen assimilation. The gene OsSIZ2 regulates nitrogen metabolism-related genes (such as nitrate transporters and glutamine synthase), affecting nitrogen absorption, transport, and redistribution in the later stages of growth. The gene OsNR1 encodes nitrate reductase, a core enzyme in nitrogen metabolism, catalyzing the conversion of nitrate to nitrite and enhancing carbon-nitrogen co-operational efficiency. Summary of the Invention

[0005] To address the aforementioned technical issues, this application first provides a strain of Pseudomonas sp. SJA1, which was deposited on November 11, 2022, at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC No. 26128.

[0006] This application also provides a biological agent comprising one or more of the following: bacterial culture, bacterial suspension, bacterial powder, bacterial fermentation product (such as fermentation broth), bacterial culture or filtrate of the culture, or bacterial metabolites.

[0007] This application also provides a complex microbial community, including the aforementioned Pseudomonas sp. SJA1 and Bacillus megaterium JSY3; the JSY3 was deposited on August 10, 2023, at the China General Microbiological Culture Collection Center (CGMCC), with accession number CGMCC No. 28153 (CN117586914B). In some embodiments, SJA1 and JSY3 are mixed in an equal ratio (e.g., 1:1), where the ratio can be a mass ratio or a volume ratio.

[0008] This application also provides a biological agent comprising the above-mentioned complex microbial community, and one or more mixtures of the microbial community's bacterial suspension, bacterial metabolites, bacterial fermentation products (such as fermentation broth), bacterial culture or filtrate of the culture, or bacterial metabolites.

[0009] In some embodiments, the biological agent can be a suitable formulation such as a microbial agent or fertilizer. In some embodiments, the microbial agent is an antibacterial agent (e.g., an antibacterial agent against bacterial blight); or the fertilizer is a compound fertilizer made from microbial fertilizer, organic fertilizer, and / or inorganic fertilizer. In some specific embodiments, the fertilizer is a compound fertilizer prepared by mixing organic fertilizer and microbial fertilizer. In some specific embodiments, the fertilizer is a compound fertilizer prepared by mixing inorganic fertilizer and microbial fertilizer. In some specific embodiments, the compound fertilizer is applied directly to the plant (e.g., rice). In some specific embodiments, the microbial fertilizer is applied to the plant (e.g., rice) sequentially with other fertilizers (e.g., organic fertilizer or inorganic fertilizer). In some specific embodiments, the application is performed at the root or above ground (e.g., foliar spraying).

[0010] This application also provides a microbial agent, including the aforementioned Pseudomonas or complex microorganisms and acceptable adjuvants.

[0011] In some embodiments, the adjuvant is, for example, a culture medium or microbial protectant suitable for the growth of the complex microbial community.

[0012] Examples of microbial protectants include alginate oligosaccharides, burdock oligosaccharides, vegetable oils, tetrahydropyrimidine, fumaric acid, etc.

[0013] This application also provides a method for upregulating the expression levels of plant OsMGD2, OsMGD3, OsSIZ2, OsSAE1a and / or OsNR1 genes, or a method for promoting plant growth, or a method for promoting nitrogen and phosphorus accumulation in plants, or a method for promoting plant resistance to bacterial blight, comprising applying a complex microbial community or applying a biological agent containing said complex microbial community; said complex microbial community includes a strain of Pseudomonas sp. SJA1 and Bacillus megaterium JSY3; said SJA1 was deposited at the China General Microbiological Culture Collection Center on November 11, 2022, with accession number: CGMCC No. 26128; said JSY3 was deposited at the China General Microbiological Culture Collection Center on August 10, 2023, with accession number: CGMCC No. 28153.

[0014] In some implementations, the OsMGD2, OsMGD3, OsSIZ2, OsSAE1a and / or OsNR1 genes are located in the leaves or roots of the plant.

[0015] In some implementations, promoting plant growth means promoting the biomass of both the aboveground and underground parts of the plant.

[0016] In some implementations, the aboveground and underground biomass includes one or more of plant height, fresh or dry weight of leaves, and fresh or dry weight of roots.

[0017] In some implementations, promoting nitrogen and phosphorus accumulation in plants means promoting nitrogen and phosphorus accumulation in plant leaves and roots.

[0018] In this field, obtaining bacterial solutions, suspensions, powders, fermentation products (such as fermentation broth), cultures or filtrates of single or complex bacterial groups is a conventional technique. Nevertheless, this application provides some examples: Single-cell bacterial solutions are prepared by inoculating activated strains SJA1 and JSY3 separately into liquid culture medium; these solutions are centrifuged and resuspended in sterile water to obtain single-cell suspensions; the bacterial cells obtained after centrifuging these solutions or suspensions are dried and ground into powder to obtain single-cell powder; SJA1 and JSY3 are inoculated separately or simultaneously into fermentation medium to obtain single-cell fermentation broth or fermentation broth of a complex bacterial group; single-cell bacterial solutions or suspensions of SJA1 and JSY3 are mixed in equal volumes, or single-cell powders of the two strains are mixed in equal masses to obtain a complex bacterial agent or biological preparation. The complex bacterial agent or biological preparation can be a solid or liquid product.

[0019] Microbial fertilizers include the aforementioned Pseudomonas or complex microbial communities.

[0020] This application also provides a compound fertilizer prepared using the above-mentioned biological agent.

[0021] This application also provides fertilizers prepared from the aforementioned Pseudomonas or complex microbial communities. In some embodiments, the fertilizer is a compound fertilizer. In some embodiments, the fertilizer includes the aforementioned microbial fertilizer, organic fertilizer, and / or inorganic fertilizer.

[0022] In some embodiments, the inorganic fertilizer is inorganic nitrogen fertilizer, inorganic phosphate fertilizer, and / or inorganic potassium fertilizer. In some embodiments, the inorganic nitrogen fertilizer includes urea and / or ammonium sulfate; in some embodiments, the inorganic phosphate fertilizer includes monoammonium phosphate and / or diammonium phosphate; in some embodiments, the inorganic potassium fertilizer includes potassium sulfate and / or potassium chloride.

[0023] This application also provides an antibacterial agent prepared using the above-mentioned biological agents, such as an antibacterial agent for combating bacterial blight.

[0024] Since the OsMGD2, OsMGD3, OsSIZ2, OsSAE1a, and OsNR1 genes are ubiquitous in plant tissues and have similar functions, the research results on the expression of these genes in this application are expected to be extended to more plant types besides rice. Plants can be monocotyledonous or dicotyledonous, herbaceous or woody, crops (e.g., rice), vegetable plants, or fruit plants, etc.

[0025] This application also provides the application of the above-mentioned bacteria, compound microbial groups, microbial agents, compound microbial agents, biological agents, compound fertilizers, or antibacterial agents in the field of agricultural planting, especially in the planting of crops (such as rice), vegetables, or fruits.

[0026] This application also provides a plant growth promoter prepared from the aforementioned bacteria, compound microbial communities, microbial agents, compound microbial agents, biological agents, the aforementioned compound fertilizers, or the aforementioned antibacterial agents. The plant growth promoter can be used, for example, to promote the biomass of the aboveground and underground parts of rice.

[0027] In some embodiments, the aboveground and underground biomass is at least one of the following: plant height, fresh or dry weight of leaves, and fresh or dry weight of roots.

[0028] This application also provides the use of the above-mentioned biological agent, the above-mentioned compound fertilizer, or the above-mentioned antibacterial agent in increasing the expression levels of the OsMGD2, OsMGD3, OsSIZ2, OsSAE1a and / or OsNR1 genes in rice leaves and roots.

[0029] This application also provides the use of the above-mentioned biological agent, the above-mentioned compound fertilizer, or the above-mentioned antibacterial agent in promoting the accumulation of nitrogen and phosphorus in rice leaves and roots.

[0030] This application also provides the use of the above-mentioned biological agent, the above-mentioned compound fertilizer, or the above-mentioned antibacterial agent in promoting rice resistance to bacterial blight. Attached Figure Description

[0031] Figure 1 Rice plant height under different treatments.

[0032] Figure 2 Fresh weight and dry weight of rice leaves under different treatments.

[0033] Figure 3 Fresh and dry weight of rice roots under different treatments.

[0034] Figure 4 Nitrogen and phosphorus accumulation in rice leaves under different treatments.

[0035] Figure 5 Nitrogen and phosphorus accumulation in rice roots under different treatments.

[0036] Figure 6 Relative expression levels of the OsMGD2 gene in rice leaves and roots under different treatments.

[0037] Figure 7 Relative expression levels of the OsMGD3 gene in rice leaves and roots under different treatments.

[0038] Figure 8 Relative expression levels of the OsS I Z2 gene in rice leaves and roots under different treatments.

[0039] Figure 9 Relative expression levels of the OsSAE1 a gene in rice leaves and roots under different treatments.

[0040] Figure 10 Relative expression levels of the OsNR1 gene in rice leaves and roots under different treatments.

[0041] Figure 11 Determination of the growth capacity of Bacillus subtilis after JS and MC treatment. Detailed Implementation

[0042] To illustrate the universal design concept of this application, rice is used as an example below, but this should not be used as a reason to limit the scope of protection of this application.

[0043] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0044] Example 1 Experimental Design

[0045] I. Experimental Materials:

[0046] Rice variety: Huruan 1212 was selected, which is a common rice variety in this region and has a certain degree of representativeness and adaptability.

[0047] Soil: The soil used in the experiment was taken from paddy field soil of the control (CK) in the Qingpu Modern Agricultural Park to ensure a consistent soil background and reduce the impact of soil differences on the experimental results. The basic physicochemical properties of the soil before the experiment were: total nitrogen 1.70 g·kg⁻¹ -1 Total phosphorus 0.95 g·kg -1 0.11 g / kg of readily available potassium -1 Organic matter 29.60 g·kg -1 The pH value is 7.02.

[0048] Organic fertilizer: provided by Qingpu Modern Agricultural Park, rich in various organic matter and nutrients, providing basic nutrients for rice growth.

[0049] Microbial fertilizers: ① Compound microbial fertilizer: SJA1 Pseudomonas and JSY3 were used in combination to explore their synergistic effect. ② Commercial Bacillus (fertilizer) and commercial Pseudomonas (fertilizer): Commercially available products were used as a comparison to evaluate the relative advantages of compound microbial fertilizers.

[0050] II. Experimental Design: This study employed a pot experiment method, setting up 7 different treatment combinations, with 3 replicates for each treatment, for a total of 21 potted plants. Details are as follows:

[0051] Blank treatment (CK): Organic fertilizer from Qingpu Modern Agricultural Park was applied as a control group to evaluate the relative effects of other treatments.

[0052] Microbial fertilizer treatment (JS): Organic fertilizer from Qingpu Modern Agricultural Park was applied, and simultaneously, Bacillus megaterium microbial fertilizer JSY3 (CGMCC No. 28153) and Pseudomonas microbial fertilizer SJA1 (CGMCC No. 26128) were added to explore the growth-promoting effect of the compound microbial fertilizer.

[0053] Microbial fertilizer treatment (JC): Organic fertilizer from Qingpu Modern Agricultural Park was applied, combined with JSY3 Bacillus megaterium and commercial Pseudomonas, and the differences between compound microbial fertilizer and commercial microbial fertilizer were compared.

[0054] Microbial fertilizer treatment (SC): Organic fertilizer from Qingpu Modern Agricultural Park was applied, combined with commercially available Bacillus subtilis fertilizer and SJA1 Pseudomonas aeruginosa, to further compare the effects of different microbial fertilizer combinations.

[0055] Microbial fertilizer treatment (MC): Organic fertilizer from Qingpu Modern Agricultural Park was applied, and commercially purchased Bacillus spp. and commercially purchased Pseudomonas spp. were added as a representative treatment of commercial microbial fertilizer.

[0056] Microbial fertilizer + bacterial blight treatment (JS+B): Based on the microbial fertilizer treatment (JS), bacterial blight pathogens were inoculated to evaluate the disease resistance effect of the compound microbial fertilizer.

[0057] Microbial fertilizer + bacterial blight treatment (MC+B): Based on the microbial fertilizer treatment (MC), bacterial blight pathogens were inoculated to compare the disease resistance of different microbial fertilizer treatments.

[0058] Example 2 Experimental Method

[0059] The collected fresh soil was manually removed of residue and then air-dried. It was then sieved through a 20-mesh sieve to remove larger particles and impurities. White plastic buckets with a bottom diameter of 13.5 cm and a height of 16 cm were selected as potting containers. Before rice transplanting, 1.5 kg of sieved dry soil was added to each bucket according to the treatment groups and thoroughly mixed with organic fertilizer. The application rate of organic fertilizer was calculated based on the standard of 240 kg·hm⁻² N to ensure consistent nutrient supply across treatments. After filling the pots, the soil was watered one day in advance to allow it to fully absorb water and reach a suitable moisture level. For rice transplanting, healthy rice seedlings with uniform growth were selected, with three seedlings per hole per pot. Care was taken to maintain the integrity of the seedling root system during transplanting to avoid damage and facilitate rapid recovery and growth in the pots.

[0060] The activated strains JSY3 and SJA1 were inoculated into LB liquid medium and cultured on a shaker at 140 rpm for 24 hours. Next, 3 liters of LB liquid medium were prepared and sterilized to ensure sterility of the culture environment. Then, 50 ml of the bacterial culture was added to the 3 liters of LB liquid medium and transferred to a fermenter for further shaking culture. In the fermenter, the bacterial culture was cultured under suitable conditions for three days to promote the proliferation of the strains. After fermentation, the bacterial culture was poured into sterile bottles for later use. JSY3 and SJA1, JSY3 and commercial Pseudomonas, and SJA1 and commercial Bacillus were mixed in a 1:1 ratio to prepare a solution. 25 ml of the mixed bacterial solution was applied to each rice plant twice, once on the first day and once on the seventh day after transplanting, for a total of two applications.

[0061] For disease inoculation, when the rice reaches the appropriate growth stage (about two weeks after transplanting), the JS+B and MC+B treatments are inoculated by spraying. The bacterial blight pathogen with OD600=1.5 is evenly sprayed onto the rice leaves. After three days, observations are made and samples are taken to determine the bacterial growth capacity.

[0062] Throughout the growing season, do not drain the water; maintain a water level of 1-3 cm in the pot. Regularly check the water level of the potted plants and replenish water as needed to meet the water requirements for rice growth. Regularly record the growth status of the rice and check for the occurrence of rice diseases, and take photos of the leaf morphology for later analysis of rice growth and development. Calculate the disease index based on the severity of disease occurrence to evaluate the disease resistance effects of different treatments.

[0063] The experiment concluded at the tillering stage of the rice potted plants, during which rice samples were collected. Rice leaves and roots were used to analyze the nitrogen and phosphorus content in the plants and to detect the expression of nitrogen and phosphorus-related genes using qPCR technology, providing fundamental data for further research.

[0064] The physicochemical properties of roots and leaves were determined as follows: total phosphorus was determined by the molybdenum-antimony colorimetric method; total nitrogen was determined by the Kjeldahl method.

[0065] To study the expression of functional genes in roots and leaves: Total RNA was extracted from rice leaves and roots using a plant rapid extraction kit from Beijing Bestgen Biotech Co., Ltd. RNA concentration was detected using a NanoDrop 2000 spectrophotometer, and total RNA quality was assessed by agarose gel electrophoresis. 0.5–1 μg of total RNA was reverse transcribed into cDNA. Using cDNA as a template, qRT-PCR was performed to determine the relative expression levels of nitrogen and phosphorus-related genes. The reaction volume was 20 μl, and the reaction program was: 95℃ for 30 s; 95℃ for 10 s; 60℃ for 30 s; 40 cycles. Each sample underwent qRT-PCR in triplicate. The relative gene expression levels were calculated using the 2-ΔΔCt method. OsActin and OsUbq were used as internal control genes.

[0066] Method for determining bacterial growth capacity: The bacterial suspension was resuspended in 10 mM MgCl2 and diluted to an OD600 of 0.2. The OD600 was then diluted 1000-fold. Rice leaves were placed in 1.2 ml of 10 mM MgCl2 solution with three sterile steel balls added. The sample was then ground in an automated grinder for 30 seconds at a frequency of 50 Hz, repeated six times. After grinding, 40 μl of the bacterial suspension was diluted in 160 μl of 10 mM MgCl2 solution. This serial dilution was repeated until the bacterial concentration was suitable for counting. 10 μl of each concentration of bacterial suspension was added to NA medium. After the medium was clear of visible liquid, it was sealed and incubated at 28°C for 40 h. Bacterial numbers were expressed as colony forming units (CFU). Counts were performed at concentration gradients within the CFU range of 20-100, with three replicates for each concentration gradient.

[0067] Rice disease statistics method: 15 days after spray inoculation, the diseased area of ​​rice leaves was counted, with at least 15 leaves counted per rice plant. The leaves were graded and recorded according to the severity of the diseased area. Based on the survey results, the rice disease index was calculated as follows: Disease Index = [(Number of diseased leaves at each grade * Relative grade value) / (Total number of leaves surveyed * 11)] * 100.

[0068] Example 3: Rice growth and the response of functional genes OsMGD2 and OsMGD3 I. Effects on functional genes:

[0069] Relative expression levels of the OsMGD2 gene under different treatments: from Figure 6 As can be seen, in leaves, the relative expression level of the OsMGD2 gene was higher in both the JSY3+SJA1 treatment and the SJA1+commercial bacteria treatment, significantly higher than that in the commercial microbial fertilizer treatment. In roots, the relative expression level of the OsMGD2 gene was also highest in the JSY3+SJA1 treatment, and the relative expression level in the SJA1+commercial bacteria treatment was also significantly higher than that in the commercial microbial fertilizer treatment.

[0070] Relative expression levels of the OsMGD3 gene under different treatments: from Figure 7 As can be seen, the expression level of the OsMGD3 gene in the leaves was highest in the JSY3+SJA1 treatment, which was significantly higher than that in the commercial microbial fertilizer treatment. The relative expression levels of JSY3+commercial bacteria and SJA1+commercial bacteria were also significantly higher than those in the commercial microbial fertilizer treatment. Similarly, in the roots, the relative expression level of the JSY3+SJA1 treatment was the highest, which was significantly higher than that of other treatments.

[0071] II. Impact on rice growth:

[0072] Rice plant height under different treatments: such as Figure 1 As shown, among all treatments, the JS treatment had the longest plant height (36.4 cm), and both the JS and SC treatments were significantly taller than the other groups. The JC treatment had the shortest plant height (22.9 cm), slightly shorter than the CK treatment. The JS treatment significantly promoted rice seedling growth, while JC, SC, and MC treatments did not increase plant height as much as the JS treatment. The JS treatment showed a highly significant difference compared to the MC treatment, indicating that the JS treatment was significantly more effective than the MC treatment in promoting rice seedling growth.

[0073] Fresh weight and dry weight of rice leaves under different treatments: from Figure 2 As can be seen, the JS treatment showed significantly higher fresh and dry weights of rice leaves than other groups, indicating that the JS treatment had a significant growth-promoting effect on rice leaves. The CK treatment had the lowest fresh and dry weights of rice leaves and served as a control group. The JC, SC, and MC treatments all showed higher fresh and dry weights of rice leaves than the CK treatment, but lower than the JS treatment, indicating that commercial microbial fertilizers were less effective at promoting plant growth than the JS treatment. There was a significant difference between the JS treatment and the MC treatment.

[0074] Fresh weight and dry weight of rice roots under different treatments: from Figure 3 The results show that the JS treatment had higher root fresh weight and dry weight than other groups, and significantly higher than the CK treatment, indicating that the JS treatment had the best effect on promoting root growth in rice. The JC treatment had a similar root fresh weight to the CK treatment, but a significantly higher dry weight. The SC treatment had both higher root fresh weight and dry weight than the CK treatment, but lower than the JS treatment. The MC treatment had root fresh weight and dry weight similar to the CK treatment, indicating that commercial microbial fertilizers had no significant effect on promoting root growth in rice. Applying JSY3 or SJA1 bacteria in combination with commercial bacteria could still show a growth-promoting effect, and there was a highly significant difference between the JS treatment and the MC treatment.

[0075] Example 4: Nitrogen and phosphorus accumulation in rice and the response of functional genes OsSIZ2, OsSAE1a, and OsNR1.

[0076] I. Effects on functional genes:

[0077] Relative expression levels of the OsSIZ2 gene under different treatments: from Figure 8 As can be seen from the data, in the leaves, the relative expression level of the OsSIZ2 gene was the highest in the JSY3+ commercial microbial fertilizer treatment, which was significantly higher than that in the commercial microbial fertilizer treatment. The relative expression level of the JSY3+SJA1 treatment was also significantly higher than that in the commercial microbial fertilizer treatment. In the roots, the expression level of the OsSIZ2 gene was the highest in the JSY3+SJA1 treatment, which was significantly higher than that in other treatments.

[0078] Relative expression levels of the OsSAE1a gene under different treatments: from Figure 9 As can be seen from the data, in the leaves, the relative expression level of the OsSAE1a gene was the highest in the JSY3+SJA1 treatment and the SJA1+commercial bacteria treatment, which was significantly higher than other treatments. In the roots, the relative expression level of the OsSAE1a gene in the JSY3+commercial bacteria treatment was significantly higher than other treatment groups. There was no significant difference between the JSY3+SJA1 treatment and the commercial microbial fertilizer treatment.

[0079] Relative expression levels of the OsNR1 gene under different treatments: from Figure 10 As can be seen from the data, in the leaves, the relative expression level of the OsNR1 gene was the highest in the SJA1+ commercial bacteria treatment, which was significantly higher than that of other treatments. The relative expression level of the gene in the JSY3+SJA1 treatment was significantly higher than that in the commercial microbial fertilizer treatment. In the roots, the relative expression level of the gene in the SJA1+ commercial bacteria treatment was the highest, which was significantly higher than that in the commercial microbial fertilizer treatment and the CK treatment.

[0080] II. Nitrogen and phosphorus accumulation in rice:

[0081] Nitrogen and phosphorus accumulation in rice leaves under different treatments: From Figure 4The results showed that the JS treatment had the highest nitrogen and phosphorus accumulation in leaves, significantly higher than other treatments. The CK treatment had the lowest nitrogen and phosphorus accumulation and served as a control group. The MC treatment showed higher nitrogen accumulation in leaves than the CK treatment; while the JC, SC, and MC treatments showed a more significant increase in phosphorus accumulation in leaves than the CK treatment. This indicates that commercial organic microbial fertilizers promote nitrogen and phosphorus accumulation in rice leaves, but not as much as the JS treatment, which significantly increased nitrogen and phosphorus accumulation in rice leaves.

[0082] Nitrogen and phosphorus accumulation in rice roots under different treatments: From Figure 5 It was observed that the JS treatment resulted in the highest nitrogen and phosphorus accumulation in rice roots, showing a significant difference. The CK and MC treatments showed lower nitrogen and phosphorus accumulation in rice roots. The JC and SC treatments showed higher nitrogen and phosphorus accumulation in rice roots than the CK and MC treatments, but lower than the JS treatment. This indicates that commercial microbial fertilizers may have a significant effect on nitrogen and phosphorus accumulation in rice roots, but their effect on increasing root nitrogen and phosphorus accumulation is not significant. The JS treatment showed significant differences from other treatments, while the JC and SC treatments may have shown an ability to increase nitrogen and phosphorus accumulation in rice roots due to the combination of commercial microorganisms with the JSY3 or SJA1 microorganisms studied in this study.

[0083] Example 5: Rice Disease Resistance

[0084] The experiment involved inoculating *Bacillus thuringiensis*, the causal agent of bacterial blight, and the growth capacity of *Bacillus thuringiensis* after treatment with JS and MC was determined. The results are shown in Table 1. Figure 11 The results show that the bacterial blight pathogen grew in significantly higher numbers in the MC treatment than in the JS (JSY3+SJA1) treatment. This indicates that compound microbial fertilizer has a significant effect on enhancing the disease resistance of rice.

[0085] Table 1 Results of the White Leaf Blight Disease Index

[0086]

[0087] In summary, the combined application of organic fertilizer and microbial fertilizer can significantly improve the growth indicators and nutrient content of rice, while also enhancing its disease resistance. The JS treatment group, in particular, showed significant advantages in promoting rice growth and increasing nutrient content.

[0088] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A method for promoting rice growth, characterized in that, This includes applying a complex bacterial culture consisting of only two bacteria or a biological agent containing said complex bacterial culture; said complex bacterial culture is a single strain of Pseudomonas (…). Pseudomonas sp. SJA1 and Bacillus megaterium ( Bacillus megaterium SJA1 was deposited at the China General Microbiological Culture Collection Center (CGMCC) on November 11, 2022, with accession number CGMCC No. 26128; JSY3 was deposited at the same center on August 10, 2023, with accession number CGMCC No. 28153; and SJA1 and JSY3 were mixed in a 1:1 ratio, where the ratio is by mass or by volume.

2. The method as described in claim 1, characterized in that, The rice variety in question is Huruan 1212.

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