A microbial inoculant for promoting the growth and development of orchid plants and its preparation process

Abstract

This invention relates to the field of orchid seedling cultivation technology, specifically to a microbial inoculant for promoting the growth and development of orchids and its preparation process. The preparation process includes the following steps: preparing cottonseed hull biochar material; preparing a carbon-based microbial fixative solution; and preparing the microbial inoculant for promoting the growth and development of orchids. This invention fixes oyster mushroom spores inside the lignocellulose structure of cottonseed hulls. Enzymes secreted by the fungus during its natural growth break down the plant framework, obtaining a well-developed biochar precursor. After the cottonseed hulls are processed into biochar at high temperatures, the spores are fixed within the pores of the biochar material for growth and reproduction, forming a continuous, homogeneous biofilm. This allows for the proliferation and expansion of the same microbial population, increasing the concentration of dominant microorganisms in the microbial solution, thereby enhancing the growth-promoting effect of the microbial inoculant on plants.

Description

Technical Field

[0001] This invention relates to the field of orchid seedling technology, specifically to a microbial agent that promotes the growth and development of orchids and its preparation process. Background Technology

[0002] Microbial inoculants are products that utilize beneficial microorganisms such as bacteria, fungi, and actinomycetes, and their metabolic products to improve plant growth, soil health, or control pests and diseases. Based on their uses, they can be categorized into soil conditioners, plant growth regulators, and biopesticides.

[0003] Orchids are a type of plant with high requirements for environmental conditions. Due to their high requirements for nutrient absorption and soil environment, orchids usually form a symbiotic structure with mycorrhizal fungi, which greatly expands the root absorption range of orchids and enhances their ability to absorb water and nutrients. Therefore, during the growth and development of orchids, the seedling formation rate of orchids can be improved by using microbial inoculants.

[0004] However, the commonly used microbial agents in existing inoculants generally consist of nitrogen-fixing bacteria such as rhizobia and Frankincense, and plant hormone-producing bacteria such as Bacillus subtilis and Pseudomonas fluorescens. These bacteria enrich soil nutrients through their life activities or produce plant hormones to promote plant growth. However, orchids absorb less nutrients during seed formation and are correspondingly less responsive to external hormone stimulation. Therefore, the commonly used microbial agents have limited effect on promoting orchid seed development. Therefore, this invention provides a microbial agent for promoting the growth and development of orchids and its preparation process, which achieves the effect of promoting the growth and development of orchids through a microbial agent prepared from endophytic fungi of orchids. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a microbial inoculant for promoting the growth and development of orchid plants and its preparation process.

[0006] S1: Preparation of cottonseed hull biochar materials

[0007] Cottonseed hulls, MgSO4, KH2PO4, urea, lime and white sugar were added to deionized water, and then oyster mushroom inoculum was added and mixed evenly. The mixture was then incubated at a constant temperature and subsequently steam-inactivated to obtain microbially treated cottonseed hulls. The microbially treated cottonseed hulls were pyrolyzed to obtain cottonseed hull powder, which was then ground and sieved. NaOH was then added and heated to activate the powder, which was then heated to obtain heat-treated powder. The heat-treated powder was washed and dried to obtain cottonseed hull biochar material.

[0008] S2: Preparation of carbon-based microbial fixative

[0009] Rice husks, corn stalks, and rice straw are mixed, crushed, and sieved. The mixture is then placed in a quartz boat, flattened, compacted, sealed with tin foil, and placed in a vacuum tube furnace. Nitrogen is used as the carrier gas and protective gas for pyrolysis in the vacuum tube furnace to obtain mixed biochar material. The mixed biochar material is then mixed with cottonseed hull biochar material to obtain mixed powder. The mixed powder is then mixed with PDA culture medium, shaken, adsorbed, and fixed to obtain a carbon-based microbial fixative.

[0010] S3: Preparation of composite humic acid hydrogel powder

[0011] Take healthy Paphiopedilum orchids and rinse the surface substrate under running water. Blot dry with filter paper. Cut out the roots of Paphiopedilum orchids and disinfect them. First, soak the roots of Paphiopedilum orchids in alcohol, then disinfect them with mercuric chloride to obtain treated roots. Place the treated roots on a petri dish and cut them into tissue segments. Inoculate them on PDA medium and add carbon-based microbial fixative. Incubate in the dark in an incubator. After the tissue segments grow mycelia, pick the mycelia at the edge of the colony and transfer them to a new petri dish containing PDA medium for purification and culture. After purification, obtain growth-promoting microorganisms. Dilute the growth-promoting microorganisms with deionized water and add L-tryptophan to obtain a microbial agent that promotes the growth and development of orchid plants.

[0012] Further, step S1, preparing cottonseed hull biochar material, includes the following steps:

[0013] S1.1: Add 4-5 parts by weight of cottonseed hulls, 0.2-0.5 parts by weight of MgSO4, 1-3 parts by weight of KH2PO4, 0.5-2 parts by weight of urea, 0.1-0.5 parts by weight of lime and 1-3 parts by weight of white sugar to 100 parts by weight of deionized water, then add 0.2-0.4 parts by weight of oyster mushroom inoculum and mix well. Incubate at 24-26℃ for 40 days, then steam inactivate at 120-125℃, wash three times with deionized water, and dry at 100-105℃ to constant weight to obtain microbially treated cottonseed hulls.

[0014] S1.2: Microbially treated cottonseed hulls are heated to 500-550℃ in an argon atmosphere at a flow rate of 100mL / min and a heating rate of 3℃ / min for 1-1.5h to obtain cottonseed hull powder. The powder is then ground through an 80-mesh sieve, followed by the addition of 4-4.5 times its mass of NaOH. Argon gas is then introduced at a flow rate of 100mL / min and heated to 800-850℃ for 3-3.5h to obtain heat-treated powder.

[0015] S1.3: The heat-treated powder was washed with 0.1 mol / L HCl and dried at 60-80℃ to constant weight to obtain cottonseed hull biochar material.

[0016] Further, step S2, preparing the carbon-based microbial fixative, includes the following steps:

[0017] S2.1: Mix rice husks, corn stalks and rice straw in a mass ratio of 1:1:(1-2), crush them and pass them through an 18-mesh sieve. Then, put them into a quartz boat, flatten and compact them, wrap them with tin foil and seal them. Place them in a vacuum tube furnace, use nitrogen as the carrier gas and protective gas, and pyrolyze them in the vacuum tube furnace for 2-2.5 hours at a pyrolysis temperature of 600℃ to obtain mixed biochar material.

[0018] S2.2: Mix the mixed biochar material with cottonseed hull biochar material at a mass ratio of 1:(2-3) to obtain a mixed powder. Mix the mixed powder with PDA culture medium at a ratio of 1g:(10-12)mL. Shake and adsorb the mixture at 35-36℃ and 160-180r / min for 24-25h to obtain a carbon-based microbial fixative.

[0019] Further, step S3, preparing a microbial inoculant to promote the growth and development of orchid plants, includes the following steps:

[0020] S3.1: Take a healthy Paphiopedilum hard-leaved orchid and rinse the surface substrate under running water. Use filter paper to absorb the water. Cut out the roots of the hard-leaved orchid and disinfect them. First, soak the roots of the hard-leaved orchid in alcohol for 60-65 seconds, rinse them 2-3 times with sterile water, wipe the surface water with sterile filter paper, then disinfect them with 0.1-0.15% mercuric chloride for 5-9 minutes. Rinse them 2-3 times with sterile water and wipe the surface water with sterile filter paper to obtain the treated roots.

[0021] S3.2: Place the treated root on a culture dish and cut it into 4.8-5.2 mm tissue segments. Inoculate the segments on PDA medium and add 5-20% carbon-based microbial fixative to the total mass of the system. Incubate at 25-26℃ in the dark for 7 days. After the tissue segments have grown mycelia, pick the mycelia at the edge of the colony and transfer them to a new culture dish containing PDA medium for purification and culture. Purify 2-3 times to obtain growth-promoting microorganisms.

[0022] S3.3: Dilute the growth-promoting microorganisms with 10 times the volume of deionized water, and then add 0.5-0.6 g / L of L-tryptophan to obtain a microbial inoculant that promotes the growth and development of orchid plants.

[0023] Furthermore, the oyster mushroom strain is a fungus with the scientific name Pleurotus ostreatus.

[0024] Furthermore, the HCl concentration is 0.1 mol / L.

[0025] Furthermore, the nitrogen flow rate is 100 mL / min, and the heating rate is set to 18-20 °C / min.

[0026] Furthermore, the PDA culture medium was prepared by mixing 15g of agar, 200g of peeled potato, 20g of glucose, and 1L of pure water.

[0027] Furthermore, the hard-leaved slipper orchid is a three-year-old plant with the scientific name Paphiopedilum micranthum Tang & FT Wang.

[0028] A microbial inoculant for promoting the growth and development of orchid plants is prepared by the above-mentioned preparation process for microbial inoculants for promoting the growth and development of orchid plants.

[0029] Compared with the prior art, the present invention has at least the following beneficial effects:

[0030] 1. This invention involves embedding oyster mushroom spawn into the interior of cottonseed hulls with a lignocellulose structure. The fungus utilizes naturally secreted enzymes to break down the plant framework, resulting in a biochar precursor with well-developed pores. This precursor is then modified with NaOH to further increase its pore size and looseness. When these cottonseed hulls are processed into biochar at high temperatures, the spawn is immobilized within the pores of the biochar material, allowing it to grow and reproduce, forming a continuous, homogeneous biofilm. This promotes the proliferation and expansion of the same microbial population, increases the concentration of dominant microbial species in the microbial inoculum, and ultimately enhances the promoting effect of the microbial agent on plant growth.

[0031] 2. This invention isolates endophytic fungi from the roots of Paphiopedilum sclerotium. Endophytic fungi help orchid plants grow and develop by producing growth hormones, promoting the absorption of mineral nutrients, and enhancing the plant's resistance to adverse conditions. Because orchid seeds are tiny and lack endosperm, they heavily rely on fungi to provide the nutrients needed for seed germination. After the hyphae invade the seed, they transfer nutrients to the seed through the embryo. Therefore, the fungal agent prepared from the endophytic fungi extracted from Paphiopedilum sclerotium can coexist with orchid seeds after spraying and promote seed germination and plant growth and development by secreting hormones, vitamins, and glycoproteins rich in hydroxyproline. Attached Figure Description

[0032] The accompanying drawings, which are incorporated herein and form part of the specification, illustrate embodiments of the present disclosure and, together with the specification, further serve to explain the principles of the present disclosure and enable those skilled in the art to implement and use the present disclosure.

[0033] Figure 1 This is a flowchart illustrating the preparation process of a microbial agent for promoting the growth and development of orchid plants, as used in an embodiment of the present invention. Detailed Implementation

[0034] The following describes in detail, with reference to the accompanying drawings and specific embodiments, a microbial inoculant for promoting the growth and development of orchid plants and its preparation process, provided by the present invention. It should be noted that, to make the embodiments more detailed, the following embodiments are the best and preferred embodiments; those skilled in the art can also use other alternative methods to implement some known technologies; and the accompanying drawings are only for more specific description of the embodiments and are not intended to specifically limit the present invention.

[0035] Example 1: A preparation process for a microbial inoculant that promotes the growth and development of orchid plants, such as... Figure 1 As shown, it includes the following steps:

[0036] S1: Preparation of cottonseed hull biochar materials

[0037] S1.1: Add 4 parts by weight of cottonseed hulls, 0.2 parts by weight of MgSO4, 1 part by weight of KH2PO4, 0.5 parts by weight of urea, 0.1 parts by weight of lime and 1 part by weight of white sugar to 100 parts by weight of deionized water, then add 0.2 parts by weight of oyster mushroom spawn (scientific name: Pleurotus ostreatus), mix well, and incubate at 24℃ for 40 days. Then, steam inactivate at 120℃, wash 3 times with deionized water, and dry at 100℃ to constant weight to obtain microbially treated cottonseed hulls.

[0038] S1.2: Microbially treated cottonseed hulls were heated to 500℃ in an argon atmosphere at a flow rate of 100mL / min and a heating rate of 3℃ / min for 1h to obtain cottonseed hull powder. The powder was then ground through an 80-mesh sieve, followed by the addition of 4 times the mass of NaOH. Argon gas was then introduced at a flow rate of 100mL / min and heated to 800℃ for 3h to obtain heat-treated powder.

[0039] S1.3: The heat-treated powder was washed with 0.1 mol / L HCl and dried at 60°C to constant weight to obtain cottonseed hull biochar material.

[0040] S2: Preparation of carbon-based microbial fixative

[0041] S2.1: Rice husks, corn stalks and rice straw are mixed in a mass ratio of 1:1:1 and then crushed through an 18-mesh sieve. The mixture is then placed in a quartz boat, flattened and compacted, sealed with tin foil, and placed in a vacuum tube furnace. Nitrogen is used as the carrier gas and protective gas, with a flow rate of 100 mL / min. The mixture is pyrolyzed in the vacuum tube furnace for 2-2.5 hours at a temperature of 600℃ and a heating rate of 18℃ / min to obtain the mixed biochar material.

[0042] S2.2: Mix the mixed biochar material and cottonseed hull biochar material at a mass ratio of 1:2 to obtain a mixed powder. Mix the mixed powder with PDA medium at a ratio of 1g:10mL. The PDA medium is prepared by mixing 15g of agar, 200g of peeled potato, 20g of glucose, and 1L of pure water. The mixture is shaken and adsorbed at 35℃ and 160r / min for 24h to obtain a carbon-based microbial fixative.

[0043] S3: Preparation of microbial inoculants to promote the growth and development of orchid plants.

[0044] S3.1: Take a healthy Paphiopedilum micranthum Tang & FT Wang, rinse the surface substrate under running water and blot dry with filter paper. Cut off the roots of the Paphiopedilum micranthum and disinfect them. First, soak the roots of the Paphiopedilum micranthum in 70% alcohol for 60 seconds, rinse twice with sterile water, wipe the surface moisture with sterile filter paper, then disinfect with 0.1% mercuric chloride for 5 minutes, rinse twice with sterile water, wipe the surface moisture with sterile filter paper, and obtain the treated roots.

[0045] S3.2: Place the treated root on a culture dish and cut it into 4.8-5.2 mm tissue segments. Inoculate the segments on PDA medium and add 5% carbon-based microbial fixative solution to the total mass of the system. Incubate at 25°C in the dark for 7 days. After the tissue segments have grown mycelia, pick the hyphae at the edge of the colony and transfer them to a new culture dish containing PDA medium for purification and culture. Purify twice to obtain growth-promoting microorganisms.

[0046] S3.3: Dilute the growth-promoting microorganisms with 10 times the volume of deionized water, and then add 0.5 g / L of L-tryptophan to obtain a microbial inoculant that promotes the growth and development of orchid plants.

[0047] Example 2: A preparation process for a microbial inoculant that promotes the growth and development of orchid plants, such as... Figure 1 As shown, it includes the following steps:

[0048] S1: Preparation of cottonseed hull biochar materials

[0049] S1.1: Add 5 parts by weight of cottonseed hulls, 0.5 parts by weight of MgSO4, 3 parts by weight of KH2PO4, 2 parts by weight of urea, 0.5 parts by weight of lime and 3 parts by weight of white sugar to 100 parts by weight of deionized water, then add 0.4 parts by weight of oyster mushroom inoculum (scientific name: Pleurotus ostreatus), mix well, and incubate at 24℃ for 40 days. Then, inactivate by steam at 120℃, wash 3 times with deionized water, and dry at 100℃ to constant weight to obtain microbially treated cottonseed hulls.

[0050] S1.2: Microbially treated cottonseed hulls were heated to 500℃ in an argon atmosphere at a flow rate of 100mL / min and a heating rate of 3℃ / min for 1h to obtain cottonseed hull powder. The powder was then ground through an 80-mesh sieve, followed by the addition of 4 times the mass of NaOH. Argon gas was then introduced at a flow rate of 100mL / min and heated to 800℃ for 3h to obtain heat-treated powder.

[0051] S1.3: The heat-treated powder was washed with 0.1 mol / L HCl and dried at 60°C to constant weight to obtain cottonseed hull biochar material.

[0052] S2: Preparation of carbon-based microbial fixative

[0053] S2.1: Rice husks, corn stalks and rice straw are mixed in a mass ratio of 1:1:2, crushed and passed through an 18-mesh sieve, then placed in a quartz boat, flattened and compacted, sealed with tin foil and placed in a vacuum tube furnace. Nitrogen is used as the carrier gas and protective gas, with a nitrogen flow rate of 100 mL / min. The mixture is pyrolyzed in the vacuum tube furnace for 2-2.5 h at a pyrolysis temperature of 600 °C and a heating rate of 18 °C / min to obtain mixed biochar material.

[0054] S2.2: Mix the mixed biochar material and cottonseed hull biochar material at a mass ratio of 1:3 to obtain a mixed powder. Mix the mixed powder with PDA medium at a ratio of 1g:12mL. The PDA medium is prepared by mixing 15g of agar, 200g of peeled potato, 20g of glucose, and 1L of pure water. The mixture is shaken and adsorbed at 35℃ and 160r / min for 24h to obtain a carbon-based microbial fixative.

[0055] S3: Preparation of microbial inoculants to promote the growth and development of orchid plants.

[0056] S3.1: Take a healthy Paphiopedilum micranthum Tang & FT Wang, rinse the surface substrate under running water and blot dry with filter paper. Cut off the roots of the Paphiopedilum micranthum and disinfect them. First, soak the roots of the Paphiopedilum micranthum in 70% alcohol for 60 seconds, rinse twice with sterile water, wipe the surface moisture with sterile filter paper, then disinfect with 0.1% mercuric chloride for 5 minutes, rinse twice with sterile water, wipe the surface moisture with sterile filter paper, and obtain the treated roots.

[0057] S3.2: Place the treated root on a culture dish and cut it into 4.8-5.2 mm tissue segments. Inoculate the segments on PDA medium and add 20% carbon-based microbial fixative solution of the total system mass. Incubate at 25°C in the dark for 7 days. After the tissue segments grow mycelia, pick the mycelia at the edge of the colony and transfer them to a new culture dish containing PDA medium for purification and culture. Purify twice to obtain growth-promoting microorganisms.

[0058] S3.3: Dilute the growth-promoting microorganisms with 10 times the volume of deionized water, and then add 0.6 g / L of L-tryptophan to obtain a microbial inoculant that promotes the growth and development of orchid plants.

[0059] Example 3: A preparation process for a microbial inoculant that promotes the growth and development of orchid plants, such as... Figure 1 As shown, it includes the following steps:

[0060] S1: Preparation of cottonseed hull biochar materials

[0061] S1.1: Add 4 parts by weight of cottonseed hulls, 0.2 parts by weight of MgSO4, 1 part by weight of KH2PO4, 0.5 parts by weight of urea, 0.1 parts by weight of lime and 1 part by weight of white sugar to 100 parts by weight of deionized water, then add 0.2 parts by weight of oyster mushroom spawn (scientific name: Pleurotus ostreatus), mix well, and incubate at 26℃ for 40 days. Then, steam inactivate at 125℃, wash 3 times with deionized water, and dry at 105℃ to constant weight to obtain microbially treated cottonseed hulls.

[0062] S1.2: Microbially treated cottonseed hulls were heated to 500℃ in an argon atmosphere at a flow rate of 100mL / min and a heating rate of 3℃ / min for 1.5h to obtain cottonseed hull powder. The powder was then ground through an 80-mesh sieve, and 4.5 times its mass of NaOH was added. Argon gas was then passed through at a flow rate of 100mL / min and heated to 850℃ for 3.5h to obtain heat-treated powder.

[0063] S1.3: The heat-treated powder was washed with 0.1 mol / L HCl and dried at 80°C to constant weight to obtain cottonseed hull biochar material.

[0064] S2: Preparation of carbon-based microbial fixative

[0065] S2.1: Rice husks, corn stalks and rice straw are mixed in a mass ratio of 1:1:1 and then crushed through an 18-mesh sieve. The mixture is then placed in a quartz boat, flattened and compacted, sealed with tin foil, and placed in a vacuum tube furnace. Nitrogen is used as the carrier gas and protective gas, with a flow rate of 100 mL / min. The mixture is pyrolyzed in the vacuum tube furnace for 2-2.5 h at a pyrolysis temperature of 650 °C and a heating rate of 20 °C / min to obtain mixed biochar material.

[0066] S2.2: Mix the mixed biochar material and cottonseed hull biochar material at a mass ratio of 1:2 to obtain a mixed powder. Mix the mixed powder with PDA medium at a ratio of 1g:10mL. The PDA medium is prepared by mixing 15g of agar, 200g of peeled potato, 20g of glucose, and 1L of pure water. The mixture is shaken and adsorbed at 35℃ and 180r / min for 25h to obtain a carbon-based microbial fixative.

[0067] S3: Preparation of microbial inoculants to promote the growth and development of orchid plants.

[0068] S3.1: Take a healthy Paphiopedilum micranthum Tang & FT Wang, rinse the surface substrate under running water and blot dry with filter paper. Cut off the roots of the Paphiopedilum micranthum and disinfect them. First, soak the roots of the Paphiopedilum micranthum in 75% alcohol for 65 seconds, rinse 3 times with sterile water, wipe the surface moisture with sterile filter paper, then disinfect with 0.1% mercuric chloride for 5 minutes, rinse 3 times with sterile water, wipe the surface moisture with sterile filter paper, and obtain the treated roots.

[0069] S3.2: Place the treated root on a culture dish and cut it into 5.2 mm tissue segments. Inoculate the segments on PDA medium and add 5% carbon-based microbial fixative solution of the total mass of the system. Incubate at 26°C in the dark for 7 days. After the tissue segments grow mycelia, pick the mycelia at the edge of the colony and transfer them to a new culture dish containing PDA medium for purification and culture. Purify 3 times to obtain growth-promoting microorganisms.

[0070] S3.3: Dilute the growth-promoting microorganisms with 10 times the volume of deionized water, and then add 0.5 g / L of L-tryptophan to obtain a microbial inoculant that promotes the growth and development of orchid plants.

[0071] Comparative Example 1: Compared with Example 1, Comparative Example 1 is a commercially available microbial agent that promotes plant growth and development.

[0072] Comparative Example 2: Compared with Example 1, the difference of Comparative Example 2 is that cottonseed hull biochar material is not added in step S2.2. Specifically, "S2.2: Mix the mixed biochar material with PDA culture medium at a ratio of 1g:10mL. The PDA culture medium is prepared by mixing 15g of agar, 200g of peeled potato, 20g of glucose, and 1L of pure water. The mixture is shaken and adsorbed for 24h at 35℃ and 160r / min to obtain a carbon-based microbial fixative." The prepared microbial agent that promotes the growth and development of orchid plants is recorded as Comparative Example 2.

[0073] Comparative Example 3: Compared with Example 1, the difference of Comparative Example 3 is that no mixed biochar material is added in step S2.2. Specifically, "S2.2: Cottonseed hull biochar material is mixed with PDA culture medium at a ratio of 1g:10mL. The PDA culture medium is prepared by mixing 15g of agar, 200g of peeled potato, 20g of glucose, and 1L of pure water. The mixture is shaken and adsorbed for 24h at 35℃ and 160r / min to obtain a carbon-based microbial fixative." The prepared microbial agent that promotes the growth and development of orchid plants is recorded as Comparative Example 3.

[0074] Examples 1-3 and Comparative Examples 1-3 were divided into six groups, and each group of 25 orchid seeds were co-germinated with the seeds. The seedling formation rate of the orchid seeds was observed, as shown in Table 1.

[0075] Table 1

[0076] Seedling formation rate (%) Example 1 16 Example 2 16 Example 3 16 Comparative Example 1 12 Comparative Example 2 8 Comparative Example 3 8

[0077] The seedling formation rate of Examples 1-3 was 16%, while that of Comparative Example 1 (the commercially available product) was 12%. It can be seen that the microbial agent of the present invention improved the seedling formation rate of orchid plants compared with commercially available products and promoted the growth and development of orchid plants.

[0078] The seedling formation rate of Comparative Examples 2 and 3 was 8%. It can be seen that the biochar material prepared from cottonseed hulls treated with Pleurotus ostreatus can give the endophytic fungi of Paphiopedilum sclerotium a better reproductive advantage during cultivation and a higher concentration in the fungal solution after supporting the carbon-based microbial fixative solution, thus having a better effect on promoting plant growth.

[0079] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A preparation process for a microbial inoculant that promotes the growth and development of orchid plants, characterized in that, Includes the following steps: S1: Preparation of cottonseed hull biochar material; Cottonseed hulls, MgSO4, KH2PO4, urea, lime and white sugar were added to deionized water, and then oyster mushroom inoculum was added and mixed evenly. The mixture was incubated at a constant temperature and then steam-inactivated to obtain microbially treated cottonseed hulls. The microbially treated cottonseed hulls were pyrolyzed to obtain cottonseed hull powder, which was then ground and sieved. NaOH was then added and heated to activate the powder, which was then heated to obtain heat-treated powder. The heat-treated powder was washed and dried to obtain cottonseed hull biochar material. S2: Preparation of carbon-based microbial fixative; Rice husks, corn stalks, and rice straw are mixed, crushed, and sieved. The mixture is then placed in a quartz boat, flattened, compacted, sealed with tin foil, and placed in a vacuum tube furnace. Nitrogen is used as the carrier gas and protective gas for pyrolysis in the vacuum tube furnace to obtain mixed biochar material. The mixed biochar material is then mixed with cottonseed hull biochar material to obtain mixed powder. The mixed powder is then mixed with PDA culture medium, shaken, adsorbed, and fixed to obtain a carbon-based microbial fixative. S3: Preparation of composite humic acid hydrogel powder; Take healthy Paphiopedilum hard-leaved orchids and rinse the surface substrate under running water. Use filter paper to absorb the moisture. Cut out the roots of the hard-leaved orchids and disinfect them. First, soak the roots of the hard-leaved orchids in alcohol, and then disinfect them with mercuric chloride to obtain treated roots. Place the treated roots on a culture dish and cut them into tissue segments. Inoculate them on PDA medium and add carbon-based microbial fixative. Incubate them in the dark in an incubator. After the tissue segments grow mycelia, pick the mycelia at the edge of the colony and transfer them to a new culture dish containing PDA medium for purification and culture. After purification, obtain growth-promoting microorganisms. Dilute the growth-promoting microorganisms with deionized water and add L-tryptophan to obtain a microbial agent that promotes the growth and development of orchid plants. Step S1, preparing cottonseed hull biochar material, includes the following steps: S1.1: Add 4-5 parts by weight of cottonseed hulls, 0.2-0.5 parts by weight of MgSO4, 1-3 parts by weight of KH2PO4, 0.5-2 parts by weight of urea, 0.1-0.5 parts by weight of lime and 1-3 parts by weight of white sugar to 100 parts by weight of deionized water, then add 0.2-0.4 parts by weight of oyster mushroom inoculum and mix well. Incubate at 24-26℃ for 40 days, then steam inactivate at 120-125℃, wash three times with deionized water, and dry at 100-105℃ to constant weight to obtain microbially treated cottonseed hulls. S1.2: Microbially treated cottonseed hulls are heated to 500-550℃ in an argon atmosphere at a flow rate of 100mL / min and a heating rate of 3℃ / min for 1-1.5h to obtain cottonseed hull powder. The powder is then ground through an 80-mesh sieve, followed by the addition of 4-4.5 times its mass of NaOH. Argon gas is then introduced at a flow rate of 100mL / min and heated to 800-850℃ for 3-3.5h to obtain heat-treated powder. S1.3: The heat-treated powder was washed with 0.1 mol / L HCl and dried at 60-80℃ to constant weight to obtain cottonseed hull biochar material; Step S2, preparing the carbon-based microbial fixative, includes the following steps: S2.1: Mix rice husks, corn stalks and rice straw in a mass ratio of 1:1:(1-2), crush them and pass them through an 18-mesh sieve. Then, put them into a quartz boat, flatten and compact them, wrap them with tin foil and seal them. Place them in a vacuum tube furnace, use nitrogen as the carrier gas and protective gas, and pyrolyze them in the vacuum tube furnace for 2-2.5 hours at a pyrolysis temperature of 600℃ to obtain mixed biochar material. S2.2: Mix the mixed biochar material and cottonseed hull biochar material at a mass ratio of 1:(2-3) to obtain a mixed powder. Mix the mixed powder with PDA culture medium at a ratio of 1g:(10-12)mL. Shake and adsorb the mixture at 35-36℃ and 160-180r / min for 24-25h to obtain a carbon-based microbial fixative. The oyster mushroom strain is a fungus with the scientific name Pleurotus ostreatus.

2. The preparation process of a microbial inoculant for promoting the growth and development of orchid plants according to claim 1, characterized in that, Step S3 involves preparing a microbial inoculant to promote the growth and development of orchid plants, including the following steps: S3.1: Take a healthy Paphiopedilum hard-leaved orchid and rinse the surface substrate under running water. Use filter paper to absorb the water. Cut out the roots of the hard-leaved orchid and disinfect them. First, soak the roots of the hard-leaved orchid in alcohol for 60-65 seconds, rinse them 2-3 times with sterile water, wipe the surface water with sterile filter paper, then disinfect them with 0.1-0.15% mercuric chloride for 5-9 minutes. Rinse them 2-3 times with sterile water and wipe the surface water with sterile filter paper to obtain the treated roots. S3.2: Place the treated root on a culture dish and cut it into 4.8-5.2 mm tissue segments. Inoculate the segments on PDA medium and add 5-20% carbon-based microbial fixative to the total mass of the system. Incubate at 25-26℃ in the dark for 7 days. After the tissue segments have grown mycelia, pick the mycelia at the edge of the colony and transfer them to a new culture dish containing PDA medium for purification and culture. Purify 2-3 times to obtain growth-promoting microorganisms. S3.3: Dilute the growth-promoting microorganisms with 10 times the volume of deionized water, and then add 0.5-0.6 g / L of L-tryptophan to obtain a microbial inoculant that promotes the growth and development of orchid plants.

3. The preparation process of a microbial inoculant for promoting the growth and development of orchid plants according to claim 1, characterized in that, The HCl concentration is 0.1 mol / L.

4. The preparation process of a microbial inoculant for promoting the growth and development of orchid plants according to claim 1, characterized in that, The nitrogen flow rate was 100 mL / min, and the heating rate was set to 18-20 °C / min.

5. The preparation process of a microbial inoculant for promoting the growth and development of orchid plants according to claim 2, characterized in that, PDA medium is prepared by mixing 15g of agar, 200g of peeled potato, 20g of glucose, and 1L of pure water.

6. The preparation process of a microbial inoculant for promoting the growth and development of orchid plants according to claim 2, characterized in that, The hard-leaved slipper orchid is a three-year-old plant with the scientific name Paphiopedilum micranthum Tang & FT Wang.

7. A microbial inoculant for promoting the growth and development of orchid plants, which is prepared by the preparation process of the microbial inoculant for promoting the growth and development of orchid plants according to any one of claims 1-6.

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