Salt-tolerant growth-promoting microbial agent and application thereof in synergistic saline-alkali soil corn planting

Abstract

The invention belongs to the technical field of agricultural biology, and relates to a salt-tolerant growth-promoting microbial agent and application thereof in synergistic saline-alkali soil corn planting. The salt-tolerant growth-promoting microbial agent provided by the invention is formed by compounding arbuscular mycorrhizal fungi (AMF) of a specific type and salt-tolerant growth-promoting microorganisms, and aims to remarkably improve the growth performance and yield of corn in a saline-alkali soil environment by combined application of the two microorganisms.

Description

Technical Field

[0001] The invention belongs to the field of agricultural biotechnology and relates to a salt-tolerant growth-promoting microbial agent and its application in improving the efficiency of corn planting in saline-alkali land. Background Technology

[0002] Saline-alkali land is a significant factor affecting agricultural production, as its high salinity hinders plant growth and reduces yields. Traditional methods for improving saline-alkali land mainly include physical, chemical, and biological methods. Physical methods, such as drainage and irrigation, are costly and have limited effectiveness; while chemical methods can quickly reduce soil salinity, long-term use can easily cause soil pollution and ecological damage; biological methods, on the other hand, are gaining increasing attention due to their low cost and environmental friendliness.

[0003] In recent years, microbial methods for soil improvement have shown great potential in the treatment of saline-alkali land. In particular, the combined application of arbuscular mycorrhizal fungi (AMF) and salt-tolerant growth-promoting microorganisms has proven highly effective in improving plant salt tolerance and promoting growth. AMF can form a symbiotic relationship with plant roots, increasing the root absorption area and enhancing the plant's ability to absorb soil nutrients; while salt-tolerant growth-promoting microorganisms can decompose soil organic matter, releasing nutrients such as nitrogen, phosphorus, and potassium, and enhancing plant resistance through the secretion of plant hormones.

[0004] Studies have shown that the use of AMF or salt-tolerant growth-promoting microorganisms alone has a positive effect on the growth of crops in saline-alkali land. However, there are currently no reports on the combined use of AMF and salt-tolerant growth-promoting microorganisms to promote the growth of maize in saline-alkali land. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide a salt-tolerant growth-promoting microbial agent and its synergistic effect in corn cultivation in saline-alkali land. By combining the application of AMF and salt-tolerant growth-promoting microorganisms, the invention solves the problems of inhibited growth and low yield of corn in saline-alkali land, thereby improving the growth performance and yield of corn in saline-alkali environments.

[0006] On one hand, this invention relates to a salt-tolerant growth-promoting microbial agent, the active ingredients of which are arbuscular mycorrhizal fungi and Bacillus subtilis. Bacillus subtilis and Bacillus megaterium Bacillus megaterium constitute; The arbuscular mycorrhizal fungus is *Glomus radicans*. Rhizophagus intraradiculitis and / or Moses's globosum Funnel-shaped mosses .

[0007] Furthermore, in the salt-tolerant growth-promoting microbial agent provided by the present invention, the effective components of the salt-tolerant growth-promoting microbial agent consist of arbuscular mycorrhizal fungi and beta-spores. The density of arbuscular mycorrhizal fungal spores in the inoculum is not less than 250 spores / g; The bispore inoculum was prepared by co-culturing Bacillus subtilis and Bacillus megaterium. The viable count of Bacillus subtilis in the aforementioned Bacillus inoculant is usually not less than 200 million CFU / g, and the viable count of Bacillus megaterium is not less than 10 billion CFU / g.

[0008] Furthermore, in the salt-tolerant growth-promoting microbial inoculant provided by the present invention, the mass ratio of the arbuscular mycorrhizal fungal inoculant to the dispore inoculant is 1:1~5.

[0009] Furthermore, the salt-tolerant growth-promoting microbial agent provided by the present invention also includes an auxiliary carrier, wherein the auxiliary carrier is organic fertilizer.

[0010] Furthermore, in the salt-tolerant growth-promoting microbial agent provided by the present invention, the organic fertilizer is selected from at least one of humic acid, peat soil, and compost.

[0011] Furthermore, in the salt-tolerant growth-promoting microbial agent provided by the present invention, the mass ratio of the active ingredient to the auxiliary carrier is 1:40~50.

[0012] On the other hand, the present invention relates to the application of the salt-tolerant growth-promoting microbial agent in enhancing the planting efficiency of maize in saline-alkali land.

[0013] Furthermore, in the applications provided by the present invention, the salt-tolerant growth-promoting microbial agent is applied to the saline-alkali soil before or during the sowing of corn.

[0014] Furthermore, in the application provided by the present invention, the application rate of the salt-tolerant growth-promoting microbial agent is 500-1500 kg per acre of soil.

[0015] Furthermore, in the application provided by this invention, after sowing corn, fertilization management is carried out. In the fertilization management, the amount of nitrogen fertilizer applied is 10-20t per mu, the amount of phosphorus fertilizer applied is 5-10t per mu, and the amount of potassium fertilizer applied is 8-15t per mu.

[0016] Compared with the prior art, the technical solution provided by the present invention has at least the following beneficial effects or advantages: (1) Improve corn salt tolerance: AMF effectively resists salt and alkali stress and improves corn salt tolerance by increasing the root absorption area and enhancing the absorption capacity of readily available nutrients in the soil. This helps corn maintain normal growth in saline-alkali environments and reduces growth stagnation and yield decline caused by salt damage.

[0017] (2) Promoting maize growth: Salt-tolerant growth-promoting microorganisms enhance the stress resistance of maize roots by promoting the decomposition of soil organic matter, nitrogen, phosphorus, and potassium, and secreting plant hormones such as IAA, thus significantly increasing maize emergence rate and yield. This helps maize achieve high and stable yields in saline-alkali environments and improves agricultural production efficiency.

[0018] (3) Improve soil structure: The combined application of AMF and salt-tolerant growth-promoting microorganisms helps to enhance soil cohesion, resist soil compaction, and improve soil physical properties. This helps to improve the soil's water and fertilizer retention capacity, providing a good soil environment for corn growth.

[0019] (4) Green and environmentally friendly: This method uses biological improvement techniques, eliminating the need for chemical fertilizers and pesticides, thus reducing environmental pollution and meeting the requirements of green agriculture development. This helps protect the ecological environment and achieve sustainable agricultural development. Detailed Implementation

[0020] The technical solution of the present invention will be described below with reference to embodiments. However, the present invention is not limited to the following embodiments. Unless otherwise specified, the experimental and detection methods described in each embodiment are conventional methods; the reagents and materials described are commercially available unless otherwise specified. Unless otherwise specified, all percentages in the following embodiments refer to mass percentages. Unless otherwise specified, all proportions in the following embodiments refer to mass ratios.

[0021] Example This embodiment provides a method for promoting the growth of maize in saline-alkali land.

[0022] (1) Preparation of AMF mycorrhizal inoculum: Select fine river sand and zeolite in a volume ratio of 1:1, mix them thoroughly, sterilize them with moist heat at 121℃ for 2 hours, repeat the moist heat sterilization at 121℃ for 2 hours after an interval of 24 hours, and let them stand for 1-2 weeks to use as the culture medium for AMF bacterial agent. Containing an equal amount of *Gloydium Root* Rhizophagus intraradiculitis and Moses globosum Funnel-shaped mosses The spore-forming agent was added to the above culture medium and sweet sorghum was sown. Sorghum dochna (Forssk.) Snowden After 3-4 months of cultivation under natural light conditions in a plastic greenhouse, the substrate and root segments are harvested, ensuring that the root segment infection rate is above 70% and the infection intensity is above 40%. Furthermore, after air drying, the AMF spore density was measured to ensure that each kilogram of inoculation substrate contained at least 250 mature and healthy spores, which served as the standard AMF inoculum.

[0023] (2) Preparation of Bacillus subtilis inoculum: Bacillus subtilis and Bacillus megaterium were cultured on LB solid medium and then sterilized by autoclaving to prepare solid culture medium. Next, under aseptic conditions, bacterial strains were obtained from lyophilized tubes, slant agar plates, or glycerol tubes and inoculated onto LB liquid medium using the streak plating method. The culture temperature and time are controlled at 30-37℃. After 12-24 hours to reach the logarithmic growth phase, the culture is briefly stored at 4℃ to prepare a *Bacillus subtilis* inoculum. The viable count of *Bacillus subtilis* in the inoculum is typically no less than 200 million CFU / g, and the viable count of *Bacillus megaterium* is no less than 10 billion CFU / g.

[0024] (3) Accurately weigh AMF standard bacterial agent, Bacillus spp. bacterial agent and organic fertilizer, and add them to a clean mixing container in a ratio of 1:1:50.

[0025] Use a suitable mixing tool to mix thoroughly and evenly to ensure that the three components are fully combined to form a homogeneous mixed microbial agent.

[0026] The prepared mixed bacterial agent should be placed in a dry, well-ventilated environment, avoiding direct sunlight to prevent high temperatures from affecting the activity of microorganisms in the agent.

[0027] At the same time, it is important to ensure a clean storage environment to prevent contamination by other microorganisms. If the agent will not be used in the short term, it can be sealed in a package and stored in a low-temperature environment (such as around 4°C). This will effectively extend the shelf life of the agent and maintain its good performance.

[0028] (4) Application of microbial agents: Before corn sowing, apply compound microbial agents to saline-alkali soil. The application rate is 500-1500 kg per mu of soil. The specific application rate is adjusted according to the degree of soil salinization and microbial activity. Apply 500-800 kg per mu for mildly saline-alkali soil, 800-1200 kg per mu for moderately saline-alkali soil, and 1200-1500 kg per mu for severely saline-alkali soil.

[0029] Then, till the soil to thoroughly mix the microbial agent with it. The tilling depth should be 15-20 cm to ensure that the microbial agent is evenly distributed in the topsoil.

[0030] (5) Corn Planting and Management: Corn should be planted and managed according to conventional methods, including irrigation, fertilization, and pest and disease control. During irrigation, attention should be paid to controlling the amount and frequency of water to avoid excessively wet or dry soil. Drip irrigation or sprinkler irrigation should be used, with the irrigation amount adjusted according to soil moisture and corn growth needs, maintaining soil moisture at 60%–80% of field capacity. In fertilization management, the application rate of nitrogen fertilizer is 10–20 kg / mu, phosphorus fertilizer is 5–10 kg / mu, and potassium fertilizer is 8–15 kg / mu. The ratio of nitrogen, phosphorus, and potassium fertilizers should be adjusted according to needs at different stages of corn growth. Pest and disease control should combine biological and chemical methods to reduce the use of chemical pesticides.

[0031] This example describes a slightly saline-alkali land experiment with four treatments: ① blank control group (no inoculation with mixed microbial agent); ② inoculated with 500 kg / mu of mixed microbial agent; ③ inoculated with 600 kg / mu of mixed microbial agent; ④ inoculated with 700 kg / mu of mixed microbial agent; ⑤ inoculated with 800 kg / mu of mixed microbial agent. Other conditions and planting methods were the same as described in the above implementation method, with each treatment repeated five times.

[0032] After maize completed its life cycle, its growth was investigated. The actual yield of each treatment was measured, and the yield was tallied and calculated. The experimental results are shown in Table 1.

[0033] Table 1: Comparison of Corn Growth

[0034] Note: Different letters indicate significant differences. P <0.05.

[0035] Table 1 shows that inoculation with the mixed inoculant significantly improved the growth indicators and yield of maize in saline-alkali soil. Specifically, mycorrhizal infection rate, plant height, ear length, and yield per mu (a Chinese unit of area, approximately 0.067 hectares) all increased with increasing inoculant application rate (500–800 kg / mu). Compared with the uninoculated control group, the inoculated treatments (especially at 700 and 800 kg / mu) showed significantly better results in all indicators. P <0.05 indicates that applying an appropriate amount of microbial agent can effectively promote corn growth and increase yield.

[0036] The embodiments described above are only some, not all, of the embodiments of the present invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely to illustrate preferred embodiments. All other embodiments obtained by those skilled in the art through related deductions and substitutions based on the inventive concept, without inventive effort, are within the scope of protection of the present invention.

Claims

1. A salt-tolerant growth-promoting microbial agent, characterized in that, The active ingredients consist of arbuscular mycorrhizal fungi and Bacillus subtilis. Bacillus subtilis and Bacillus megaterium Bacillus megaterium constitute; The arbuscular mycorrhizal fungus is *Glomus radicans*. Rhizophagus intraradices and / or Moses's globosum Funneliformis mosseae .

2. The salt-tolerant growth-promoting microbial agent according to claim 1, characterized in that, The effective components of the salt-tolerant growth-promoting microbial agent consist of arbuscular mycorrhizal fungi and bispores. The density of arbuscular mycorrhizal fungal spores in the inoculum is not less than 250 spores / g; The bispore inoculum was prepared by co-culturing Bacillus subtilis and Bacillus megaterium. The viable count of Bacillus subtilis in the aforementioned Bacillus inoculant is usually not less than 200 million CFU / g, and the viable count of Bacillus megaterium is not less than 10 billion CFU / g.

3. The salt-tolerant growth-promoting microbial agent according to claim 1, characterized in that, The mass ratio of the arbuscular mycorrhizal fungal inoculant to the dispore inoculant is 1:1~5.

4. The salt-tolerant growth-promoting microbial agent according to claim 1, characterized in that, It also includes an auxiliary carrier, which is organic fertilizer.

5. The salt-tolerant growth-promoting microbial agent according to claim 4, characterized in that, The organic fertilizer is selected from at least one of humic acid, peat soil, and compost.

6. The salt-tolerant growth-promoting microbial agent according to claim 4, characterized in that, The mass ratio of the active ingredient to the auxiliary carrier is 1:40~50.

7. The application of the salt-tolerant growth-promoting microbial agent according to any one of claims 1 to 6 in enhancing the planting efficiency of maize in saline-alkali land.

8. The application according to claim 7, characterized in that, include: Before or during corn planting in saline-alkali soil, the salt-tolerant growth-promoting microbial agent is applied to the saline-alkali soil.

9. The application according to claim 7, characterized in that, The application rate of the salt-tolerant growth-promoting microbial agent is 500-1500 kg per acre of soil.

10. The application according to claim 7, characterized in that, After sowing corn, fertilization management is carried out. In the fertilization management, the amount of nitrogen fertilizer applied is 10-20t per mu, the amount of phosphorus fertilizer applied is 5-10t per mu, and the amount of potassium fertilizer applied is 8-15t per mu.

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