Plant growth-promoting compound microbial agent and application thereof

Abstract

The invention relates to a growth-promoting compound microbial agent, which is prepared from bacillus pseudomycoides, bacillus subtilis and Trichoderma longibrachiatum, and is characterized in that the growth-promoting compound microbial agent is prepared from bacillus pseudomycoides, bacillus subtilis and Trichoderma longibrachiatum, and the growth-promoting compound microbial agent is prepared from bacillus amyloliquefaciens, bacillus subtilis and Trichoderma longibrachiatum. The compound microbial agent (bacillus subtilis, pseudofungal bacillus and trichoderma longibrachiatum) has excellent performance in the aspects of promoting plant growth and improving the soil environment, and the plant height, the fresh weight and the root length of plants are remarkably increased. The application of the complex microbial inoculant effectively relieves the chive continuous cropping obstacle, improves the chive growth potential and soil fertility, and provides a theoretical basis and technical support for sustainable planting of chives in facility agriculture.

Description

Technical Field

[0001] The present invention relates to the field of agricultural biotechnology, and in particular to a plant growth-promoting composite microbial agent and application thereof. Background Art

[0002] In recent years, the overuse of chemical fertilizers and pesticides and the continuous cropping of crops have led to increasingly severe soil ecological imbalances, severely hindering the sustainable development of agriculture. Microbial agents, due to their environmentally friendly properties, improved soil microenvironment, and enhanced plant resistance, have gradually become an important research direction to replace traditional chemical agents. Among them, Bacillus subtilis and Trichoderma have been widely used to inhibit bacteria and promote growth. For example, Bacillus subtilis inhibits pathogens by secreting lipopeptide antibiotics, while Trichoderma controls soil-borne diseases through a hyperparasitic mechanism. However, the effectiveness of a single strain in resolving the complex soil-microbe-crop coupling problem is limited. The application of composite microbial agents to soil ecological health has received widespread attention. Studies have attempted to combine multiple microorganisms to expand their functional coverage. For example, patent CN114456143A discloses a composite agent for combating strawberry plant death, comprising Bacillus subtilis, Bacillus licheniformis, Bacillus amyloliquefaciens, and Trichoderma. However, the synergistic mechanism between the strains in this combination of strains has not been clearly defined. Existing compound microbial agents often suffer from poor stability due to antagonism between microorganisms. For example, differences in the growth environment (pH, temperature) or nutritional requirements of different bacterial species may inhibit each other's activity, resulting in unsatisfactory field application effects.

[0003] In summary, existing technologies still face challenges such as single strain combinations, insufficient synergistic effects, limited functional coverage, over-reliance on traditional strains (such as Bacillus subtilis and Trichoderma), and insufficient development of novel functional strains (such as Bacillus pseudomycoides). The development of new composite microbial agents is urgently needed to overcome these technical bottlenecks. Therefore, identifying compatible strains, optimizing synergistic mechanisms, and improving agent stability are key to overcoming these bottlenecks. Summary of the Invention

[0004] The purpose of the present invention is to solve the technical problems of insufficient strain synergy and poor field application stability in existing composite microbial agents. The present invention enhances the plant growth-promoting function (such as nutrient activation and improvement of stress resistance) and the environmental adaptability of the agent by optimizing the strain combination and synergistic mechanism.

[0005] The object of the present invention is achieved through the following technical solutions: A plant growth-promoting composite microbial agent, characterized in that: the composite microbial agent is composed of pseudomycobacterium-like Bacillus ( Pseudomycoides bacillus ), Bacillus subtilis ( Bacillus subtilis ) and long-branch mold ( Trichoderma longibrachiatum )composition.

[0006] Further, the pseudofungal-like Bacillus ( Pseudomycoides bacillus ) The deposit number is GDMCC No.: 800059; Bacillus subtilis ( Bacillus subtilis ) The deposit number is GDMCC No.: 1.1665; Long-branched mold ( Trichoderma longibrachiatum ) The deposit number is GDMCC No.: 3.139.

[0007] Furthermore, the composite microbial agent comprises Bacillus pseudomycoides, Bacillus subtilis and Bacillus longifolia in a viable bacteria mass ratio of 1:1:1.

[0008] The plant growth-promoting composite microbial agent is prepared according to the following steps: (1) Single strain liquid fermentation: Bacillus subtilis 、 Pseudomycoides bacillus and Trichoderma longibrachiatum preparing seed liquid respectively, inoculating into fermentation medium and culturing on a shaker to obtain fermentation liquid; (2) Compounding: The fermentation broths were mixed at a ratio of 1:1:1 in terms of the number of live bacteria to prepare a compound microbial agent.

[0009] The application of the above-mentioned plant growth-promoting composite microbial agent in continuous cropping of chives.

[0010] During continuous cropping of chives, root secretions or decomposition of chive residues release allelopathic substances (such as phenolic acids and terpenoids) that accumulate in the soil, inhibiting seed germination, root growth, and nutrient absorption. This leads to reduced emergence rates, slow seedling growth, and short plant size. Furthermore, continuous cropping of chives can lead to reduced yield and quality due to soil nutrient imbalances, accumulation of pests and diseases, autotoxicity, and soil degradation.

[0011] The use of the composite microbial agent in the present invention can alleviate the above problems, effectively break the continuous cropping barrier during the continuous cropping of chives, and improve the yield and quality of chives planted in the continuous cropping soil.

[0012] The present invention has the following technical effects: The composite microbial agent (Bacillus subtilis + Bacillus pseudomycoides + Trichoderma longibrachiatum) demonstrated excellent performance in promoting plant growth and improving the soil environment, significantly increasing plant height, fresh weight, and root length. Application of the composite agent effectively alleviated the barriers to continuous cropping of chives, enhanced their growth potential, and improved soil fertility, providing a theoretical basis and technical support for the sustainable cultivation of chives in protected agriculture. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 : Changes in soil pH of each experimental group in pot experiment.

[0014] Figure 2 : Changes of available phosphorus content in soil of each experimental group in pot experiment.

[0015] Figure 3 : Changes of soil available potassium content in each experimental group of potted plant experiment.

[0016] Figure 4 : Changes in soil organic matter content in each experimental group of potted experiment. DETAILED DESCRIPTION

[0017] The present invention is described in detail below through examples. It is necessary to point out that the following examples are only used to further illustrate the present invention and are not to be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above-mentioned contents of the present invention.

[0018] The microorganisms used in the present invention are specifically: Pseudomonas aeruginosa ( Pseudomycoides bacillus ) The deposit number is GDMCC No.: 800059; Bacillus subtilis ( Bacillus subtilis ) The deposit number is GDMCC No.: 1.1665; Long-branched mold ( Trichoderma longibrachiatum ) The deposit number is GDMCC No.: 3.139, and they were purchased from Guangdong Provincial Microbial Culture Collection Center.

[0019] Example 1 The preparation of the plant growth-promoting composite microbial agent is as follows: (1) Single strain liquid fermentation: Bacillus subtilis 、 Pseudomycoides bacillus and Trichoderma longibrachiatum preparing seed liquid respectively, inoculating into fermentation medium and culturing on a shaker to obtain fermentation liquid; (2) Compounding: The fermentation broths were mixed at a ratio of 1:1:1 in terms of the number of live bacteria to prepare a compound microbial agent.

[0020] Control experiment: The preparation of the composite microbial agent is as follows: (1) Single strain liquid fermentation: Bacillus subtilis 、 Pseudomycoides bacillus 、 Bacillus velezensis and Trichoderma longibrachiatum preparing seed liquid respectively, inoculating into fermentation medium and culturing on a shaker to obtain fermentation liquid; (2) Compounding: The fermentation broths were mixed according to the mass ratio of the number of live bacteria to prepare a compound microbial agent, and a compound microbial agent with different formulas was obtained, as shown in Table 1.

[0021] Table 1:

[0022] A potted experiment using various composite microbial inoculants was conducted on chives using soil from a multi-year continuous cropping program. The control group (CK) received no composite inoculant. Three replicates were set up for each treatment. Every seven days, 60 mL of inoculant was applied to the treatment group, while the control group received an equal amount of distilled water. The pot experiment lasted for 60 days, maintaining a soil water holding capacity of 60%. Soil samples were taken every 15 days using the "five-point method" to measure soil physical and chemical parameters (pH, available phosphorus, available potassium, and organic matter). Following the experiment, agronomic characteristics of the chives (plant height, fresh weight, root length, and stem diameter) were measured. Table 2 shows the agronomic characteristics of the chives.

[0023] Table 2:

[0024] As can be seen, the Bacillus subtilis and Trichoderma longibrachiatum composite inoculant (Group A0) significantly improved all agronomic traits of chives compared to the CK group. When Bacillus Velez was added to the composite inoculant (Group A1), the agronomic traits of chives declined compared to Group A0. However, when Bacillus Velez was replaced with Bacillus subtilis (Group A3), the agronomic traits of chives significantly improved compared to Group A2. Furthermore, when Bacillus subtilis was added to Group A2 (Group A4), the changes in all indices were not significant, remaining close to those of Group A2.

[0025] Soil physical and chemical indicators: Appropriate pH in the soil can reduce the damage of acidic soil to plant roots, promote root cell division and growth, and enhance the root system's ability to absorb water and nutrients. Figure 1 As shown, it can be seen that compared with the CK group, each microbial agent group increased the pH value of the soil to varying degrees, but the soil pH of the A1 and A3 groups increased to neutral, while the pH of the other groups remained weakly acidic.

[0026] After planting plants, the content of available phosphorus and available potassium in the soil decreased, indicating that plants actively absorbed soil nutrients. However, the excessive decrease in the content of available phosphorus and available potassium also reflects the dynamic imbalance between the active absorption of soil nutrients by plants and the soil's nutrient supply capacity. Figure 2 and Figure 3As shown, it can be seen that with the extension of planting time, the contents of available phosphorus and quick-acting potassium showed a downward trend. When the planting time exceeded 45 days, the available phosphorus in the compound microbial agent group decreased more than that in the CK group. When the planting time was extended from 45 days to 60 days, the available phosphorus in the A3 group showed an upward trend, indicating that the metabolic activities of the compound microbial agent in the A3 group produced a synergistic effect, which increased the content of available phosphorus in the soil, which was higher than that of the CK group, while the other compound microbial agent groups continued to decline.

[0027] During plant growth, although organic matter is not directly absorbed, microorganisms decompose organic matter to produce inorganic nutrients for plant root absorption. However, a moderate decline may be a normal nutrient cycle process, but a long-term continuous decline will lead to the destruction of soil structure, weakened water and fertilizer retention capacity, reduced microbial diversity, and affect crop yield and stress resistance. The changes in organic matter content in the soil of each treatment group are as follows: Figure 4 shown.

[0028] In summary, the application of the composite microbial agent composed of Bacillus subtilis + Bacillus pseudomycoides + Trichoderma longibrachiatum in the present invention effectively alleviates the obstacles of continuous cropping of shallots, improves the growth potential of shallots and soil fertility, and provides a theoretical basis and technical support for the sustainable cultivation of shallots in facility agriculture.

Claims

1. A plant growth-promoting composite microbial agent, characterized in that: The composite microbial agent is composed of pseudofungal-like Bacillus ( Bacillus Pseudomycoides ), Bacillus subtilis ( Bacillus subtilis ) and long-branch mold ( Trichoderma longibrachiatum )composition.

2. The plant growth-promoting composite microbial agent according to claim 1, characterized in that: The pseudomycoides-like Bacillus, Bacillus subtilis and long-branch mold are composed according to a live bacteria mass ratio of 1:1:

1.

3. The plant growth-promoting composite microbial agent according to claim 1 is prepared according to the following steps: (1) Single strain liquid fermentation: Bacillus subtilis 、 Bacillus Pseudomycoides and Trichoderma longibrachiatum preparing seed liquid respectively, inoculating into fermentation medium and culturing on a shaker to obtain fermentation liquid; (2) Compounding: The fermentation broths were mixed at a ratio of 1:1:1 in terms of the number of live bacteria to prepare a compound microbial agent.

4. Use of the plant growth-promoting composite microbial agent according to any one of claims 1 to 3 in continuous cropping of chives.

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