CN113024313B

CN113024313B - Mycorrhizal fungi agent and preparation method thereof

Info

Publication number: CN113024313B
Application number: CN202110465655.6A
Authority: CN
Inventors: 林江一; 陈彪; 卢丽珍; 蒋蕊
Original assignee: Shanghai Macro World Bio Technology Co ltd
Current assignee: Shanghai Macro World Bio Technology Co ltd
Priority date: 2021-04-28
Filing date: 2021-04-28
Publication date: 2022-07-12
Anticipated expiration: 2041-04-28
Also published as: CN113024313A

Abstract

The invention discloses a mycorrhizal inoculant and a preparation method thereof, and belongs to the technical field of mycorrhizal inoculants. The preparation method of the mycorrhizal fungi agent comprises the following steps: s1, strain propagation: mixing distilled water, bran, ammonium molybdate, sodium tripolyphosphate and glucose uniformly, sterilizing, inoculating strains and Sudan grass seeds, performing aseptic culture in a plant tissue culture bottle for 3-5 weeks, and taking roots and culture medium as propagation strains; s2, preparation: adding the propagation strain into a solid culture medium, uniformly mixing, sowing seeds of Sudan grass, uniformly mixing, continuously culturing for 2-3 months after seedling emergence, cutting off the overground part of the Sudan grass, cutting up root segments, uniformly mixing with a culture medium, drying and crushing to obtain the mycorrhizal fungi agent. The mycorrhizal inoculant can promote plants to absorb nutrients from underified minerals, and meanwhile, mycorrhiza can generate various growth stimulants in the metabolic process to regulate nutrient operation in the plants, so that the growth of crops is promoted.

Description

Mycorrhizal fungi agent and preparation method thereof

Technical Field

The invention relates to the technical field of mycorrhizal fungi agents, and particularly relates to a mycorrhizal fungi agent and a preparation method thereof.

Background

The mycorrhizal fungi are used as a symbiont formed by a plant root system and fungi, and have a remarkable effect on the growth promotion effect of plants. The growth and development of plants are influenced from multiple aspects: (1) the absorption of host plants to various mineral nutrients is improved, and mycorrhizal fungi can remarkably promote the absorption of plants to nutrient substances in soil and improve the capability of plants to resist diseases and insect pests; (2) the survival rate of the transplanted plants is improved; (3) promoting plant growth, increasing yield and improving quality, thereby increasing economic benefits to a certain extent; (4) enhancing the resistance of plants to stress. Therefore, the mycorrhizal fungi have important physiological effects on the nutrient absorption and growth and development of plants such as corn, soybean and the like.

The mycorrhizal fungi agent can be suitable for various types of soil, has wide practicability, and generally speaking, all lands with plant growth can be applied with microorganism bacterial manure to improve the soil and reduce the use of chemical fertilizers so as to promote the growth of crops. The thallus in the bacterial manure can generate various auxin in the metabolic process, can effectively regulate the running of nutrients in the plant body, is favorable for the absorption of mineral substances such as N, P in soil and the like, and promotes the rooting, growth and development of the plant. The developed root system is beneficial to improving the resistance and the survival rate of crops. Therefore, the utilization of the microbial fertilizer is beneficial to improving the nutrient absorption efficiency of crops and further improving the quality of the crops.

The invention provides a mycorrhizal inoculant which can solve the problem that the utilization rate of the traditional chemical fertilizer is low; the mass use of the mycorrhizal inoculant can greatly reduce the quality of vegetables and fruits, and has low survival rate in heavy metal polluted environment.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides a mycorrhizal fungi agent and a preparation method thereof.

In order to solve the technical problems, the invention adopts the technical scheme that:

a preparation method of a mycorrhizal fungi agent is characterized by comprising the following steps:

s1, strain propagation: uniformly mixing 8-12 parts by weight of distilled water, 10-30 parts by weight of bran, 2-8 parts by weight of ammonium molybdate, 1-3 parts by weight of sodium tripolyphosphate and 1-5 parts by weight of glucose, sterilizing at the temperature of 110-125 ℃ for 25-40min, cooling to obtain a propagation culture medium, inoculating strains and Sudan grass seeds, carrying out sterile culture in a plant tissue culture bottle at the temperature of 28-35 ℃ for 3-5 weeks, and taking roots and the culture medium as the propagation strains;

s2, preparation: adding the propagation strains into a solid culture medium, uniformly mixing, wherein the addition amount of the propagation strains is 10-30 wt% of the solid culture medium, sowing sudan grass seeds, the content of the sudan grass seeds is 1-5 wt% of the solid culture medium, uniformly mixing, after seedling emergence, continuously culturing for 2-3 months, cutting off the overground part of the sudan grass, cutting up root segments, uniformly mixing with a culture medium, drying and crushing the preparation to obtain the mycorrhizal fungi agent.

The strain in the S1 is arbuscular mycorrhiza, and preferably, the arbuscular mycorrhiza is Gliocladium moxidense.

The strain inoculation amount in the S1 is 0.2-1.5 wt% of the mass of the liquid culture medium, and the sudan grass seeds are 1-5 wt% of the mass of the liquid culture medium.

The preparation method of the solid culture medium in the step S2 includes: the preparation method of the solid medium in the step S2 includes: uniformly mixing 40-80 parts by weight of distilled water, 200-400 parts by weight of bran, 30-50 parts by weight of activated vermiculite powder, 30-50 parts by weight of perlite particles, 30-60 parts by weight of ammonium molybdate, 10-30 parts by weight of sodium tripolyphosphate and 2-5 parts by weight of glucose, and stirring at room temperature for 3-10min to obtain the solid culture medium.

Preferably, the preparation method of the solid medium in step S2 is: uniformly mixing 40-80 parts by weight of distilled water, 200-400 parts by weight of bran, 30-50 parts by weight of vermiculite powder, 30-50 parts by weight of activated perlite particles, 30-60 parts by weight of ammonium molybdate, 10-30 parts by weight of sodium tripolyphosphate and 2-5 parts by weight of glucose, and stirring at room temperature for 3-10min to obtain the solid culture medium.

More preferably, the preparation method of the solid medium in step S2 is: uniformly mixing 40-80 parts by weight of distilled water, 200-400 parts by weight of bran, 30-50 parts by weight of activated vermiculite powder, 30-50 parts by weight of activated perlite particles, 30-60 parts by weight of ammonium molybdate, 10-30 parts by weight of sodium tripolyphosphate and 2-5 parts by weight of glucose, and stirring at room temperature for 3-10min to obtain the solid culture medium.

One of the ideas of the invention is to use activated vermiculite powder when preparing solid culture medium, the vermiculite belongs to expandable clay, when heating to 500 ℃, interlayer water molecules are expelled from interlamination, but when being placed in moisture, the activated vermiculite powder is quickly rehydrated. If the temperature exceeds 700 ℃, the rehydration phenomenon can not occur, the distance between the base surfaces disappears, the product is the expanded vermiculite, meanwhile, the glucose aqueous solution remained between the vermiculite layers in the heating and activating process begins to melt when the temperature exceeds 150 ℃, the product begins to boil when the temperature exceeds 500 ℃, and the water vapor on the surface or in the gaps of the vermiculite can carry glucose molecules to evaporate in the activating process, so that the vermiculite has a rich pore structure in the activating process to form a worm-shaped fluffy porous structure, therefore, the specific surface area of the activated vermiculite is greatly improved, the culture process of the strains can be facilitated to fully absorb nutrient substances, and the propagation and growth of the strains are promoted.

The activated vermiculite powder is prepared by the following method: putting 40-60 parts by weight of vermiculite powder into a rotary frying pan with the temperature of 60-80 ℃ for constant-temperature frying for 15-25min, taking out, immersing into 80-120 parts by weight of 3-10 wt% glucose aqueous solution for 20-40min, carrying out ultrasonic treatment for 20-40min by ultrasonic waves with the power of 120-140W and the frequency of 20-50kHz, filtering, putting the precipitate into a muffle furnace, heating to the temperature of 700-900 ℃, carrying out heat preservation and calcination for 1-4h, and taking out to obtain the activated vermiculite powder.

The second idea of the invention is that activated perlite particles are adopted when preparing the solid culture medium, and the perlite adopted by the invention has the advantages of higher porosity, better water absorption, stable property, low price and the like. Firstly, the perlite is ultrasonically cleaned by acidic citric acid aqueous solution to increase the porosity and the specific surface area of the perlite, then the activating agent is added, the sodium bicarbonate can be gradually decomposed under the heating condition, the generated carbon dioxide needs to overflow from perlite particles, and the porosity of the perlite can be increased; under the high-temperature activation of sodium hydroxide, the crystalline inactive aluminosilicate in the perlite particles is converted into amorphous active aluminosilicate, and the water in the perlite in the roasting process is vaporized by utilizing the synergistic effect of sodium bicarbonate and sodium hydroxide, so that a porous structure with rich porosity and large specific surface area is formed. The invention uses the activated perlite culture medium to greatly improve the survival rate and the reproduction rate of bacteria.

The activated perlite particles are prepared by the following method: pouring 40-60 parts by weight of perlite particles into an ultrasonic cleaning instrument, ultrasonically cleaning 120-160 parts by weight of 10-20% citric acid aqueous solution at the power of 150-220W and the ultrasonic frequency of 20-50kHz for 1-3h, then transferring the cleaned product into a Buchner funnel, performing suction filtration and washing for 20-40min by using distilled water, drying the suction filtration product, crushing the dried product, and sieving the crushed product by using a 80-120-mesh standard sieve to obtain purified perlite particles; and (2) adding 120-180 parts by weight of an activating agent with the mass fraction of 1-5% into all the purified perlite particles, soaking at the temperature of 30-50 ℃ for 1-3h, filtering, placing the precipitate in a muffle furnace, heating to 400-500 ℃, calcining for 0.5-2h, and taking out to obtain the activated perlite particles.

The activating agent is sodium bicarbonate and/or sodium hydroxide; preferably, the activating agent is sodium bicarbonate and sodium hydroxide, and the mass ratio of the sodium bicarbonate to the sodium hydroxide is 1: (1-3).

A mycorrhiza microbial inoculum is prepared by adopting the preparation method of any one of the mycorrhiza microbial inoculants.

The invention has the beneficial effects that: the invention provides a mycorrhizal inoculant. The mycorrhizal fungi agent has a good promotion effect on the growth of corn, the activated vermiculite powder and the activated perlite particles prepared by the specific method are used for preparing the solid culture medium, so that rich nutrient substances possessed by the growth of the mycorrhizal fungi are provided, the rapid propagation of the mycorrhizal fungi can be promoted, the obtained mycorrhizal fungi agent is excellent in property, and the mycorrhizal fungi can secrete various enzymes in the metabolic process to decompose minerals and organic matters which are not dissolved in soil, so that the mycorrhizal fungi agent is changed into substances which can be directly absorbed and utilized by plants. Under the promotion of mycorrhiza, the plant can absorb nutrients from weathered minerals and also can absorb required nutrients from organic compounds such as rough humus, lignin, protein and the like, meanwhile, the mycorrhiza generates various growth stimulants in the metabolic process to regulate the nutrient operation in the plant body, so that the rooting, growth and development of crops can be promoted, and the survival rate of the crops in the environment polluted by heavy metal can be improved.

Detailed Description

The above summary of the present invention is described in further detail below with reference to specific embodiments, but it should not be understood that the scope of the above subject matter of the present invention is limited to the following examples.

Introduction of some raw materials in this application:

in the embodiment, the sacculus mosseae is preserved in the China general microbiological culture Collection center of China Committee for culture Collection of microorganisms, and the serial number of the sacculus mosseae is CGMCC No. 3012.

In the examples, glucose was purchased from Huaxin Xue chemical technology Co., Ltd, Suzhou, cat #: HXX-001.

Examples bran was purchased from Shanghai gallop Asahi agricultural products trade company Limited.

In the examples, vermiculite powder is purchased from Hebei Hemiguang mineral products Co., Ltd, and the particle size is as follows: 40 mesh, SiO₂The content is as follows: 40 percent.

In the examples, perlite particles were purchased from Shijiazhuang Ruizi Ore products, Inc., particle size: 200 meshes, cargo number: RM-25.

Ammonium molybdate in the examples, CAS: 13106-76-8.

Examples sodium tripolyphosphate, CAS: 7758-29-4.

In the examples, citric acid was purchased from Xuli chemical Co., Ltd, Jinning, cat #: 001, content: 99.5 percent.

In the examples, the commercial mycorrhizal fungi agent is purchased from Shengqi vegetable seed sale Co., Ltd, Sichuan province, with the product number: 59.

example 1

A preparation method of a mycorrhizal fungi agent comprises the following steps:

s1, strain propagation: uniformly mixing 10 parts by weight of distilled water, 20 parts by weight of bran, 6 parts by weight of ammonium molybdate, 2 parts by weight of sodium tripolyphosphate and 3 parts by weight of glucose, sterilizing for 30min at 121 ℃, cooling to obtain a propagation culture medium, inoculating a strain and Sudan grass seeds, performing aseptic culture in a plant tissue culture bottle at the temperature of 30 ℃ for 4 weeks, and taking roots and the culture medium as propagation strains; the strain inoculation amount is 1 wt% of the mass of the liquid culture medium, and the sudan grass seeds are 2 wt% of the mass of the liquid culture medium;

s2, preparation: adding a propagation strain into a solid culture medium, uniformly mixing, wherein the addition amount of the propagation strain is 20 wt% of the solid culture medium, sowing sudan grass seeds, the content of the sudan grass seeds is 4 wt% of the solid culture medium, uniformly mixing, after seedling emergence, continuously culturing for 2 months, cutting off the overground part of the sudan grass, cutting up root segments, uniformly mixing with a culture medium, drying and crushing a preparation to obtain a mycorrhizal fungi agent;

the preparation method of the solid culture medium comprises the following steps: uniformly mixing 60 parts by weight of distilled water, 300 parts by weight of bran, 40 parts by weight of vermiculite powder, 40 parts by weight of perlite particles, 40 parts by weight of ammonium molybdate, 20 parts by weight of sodium tripolyphosphate and 3 parts by weight of glucose, and stirring at room temperature for 5min to obtain a solid culture medium.

Example 2

Essentially the same as example 1, except that: replacing vermiculite powder with activated vermiculite powder;

the activated vermiculite powder is prepared by the following method: putting 50 parts by weight of vermiculite powder into a rotary frying pan with the temperature of 70 ℃ for constant temperature frying for 20min, taking out, immersing into 100 parts by weight of 6 wt% glucose aqueous solution for soaking for 30min, putting into ultrasonic waves with the power of 130W and the frequency of 25kHz for ultrasonic treatment for 30min, filtering, putting precipitates into a muffle furnace, heating to 800 ℃, keeping the temperature and calcining for 2h, and taking out to obtain the activated vermiculite powder.

Example 3

Essentially the same as example 1, except that: replacing the perlite particles with activated perlite particles;

the activated perlite particles are prepared by the following method: adding 50 parts by weight of perlite particles into 150 parts by weight of citric acid aqueous solution with the mass fraction of 15%, ultrasonically washing for 2h at the power of 200W and the frequency of 25kHz, transferring the perlite particles into a Buchner funnel, carrying out suction filtration and washing for 30min by using distilled water, drying and crushing the suction filtration product, and sieving the crushed product by using a 100-mesh sieve to obtain purified perlite particles; taking all the purified perlite particles, adding 150 parts by weight of an activating agent with the mass fraction of 3%, soaking at the temperature of 40 ℃ for 2h, filtering, putting the precipitate into a muffle furnace, heating to 450 ℃, calcining for 1h, and taking out to obtain activated perlite particles;

the activating agent is sodium bicarbonate.

Example 4

Essentially the same as example 1, except that: replacing vermiculite powder with activated vermiculite powder; replacing the perlite particles with activated perlite particles;

the activated vermiculite powder is prepared by the following method: putting 50 parts by weight of vermiculite powder into a rotary frying pan with the temperature of 70 ℃ for constant-temperature frying for 20min, taking out, immersing the vermiculite powder into 100 parts by weight of 6 wt% glucose aqueous solution for soaking for 30min, putting the solution into ultrasonic waves with the power of 130W and the frequency of 25kHz for ultrasonic treatment for 30min, filtering, putting precipitates into a muffle furnace, heating to 800 ℃, keeping the temperature and calcining for 2h, and taking out to obtain activated vermiculite powder;

the activated perlite particles are prepared by the following method: adding 50 parts by weight of perlite particles into 150 parts by weight of citric acid aqueous solution with the mass fraction of 15%, ultrasonically washing for 2 hours at the power of 200W and the frequency of 25kHz, transferring into a Buchner funnel, performing suction filtration and washing for 30min by using distilled water, drying a suction filtration product, crushing, and sieving by using a 100-mesh sieve to obtain purified perlite particles; taking all the purified perlite particles, adding 150 parts by weight of an activating agent with the mass fraction of 3%, soaking at the temperature of 40 ℃ for 2h, filtering, putting the precipitate into a muffle furnace, heating to 450 ℃, calcining for 1h, and taking out to obtain activated perlite particles;

the activating agent is sodium bicarbonate.

Example 5

Essentially the same as example 4, except that:

the activated perlite particles are prepared by the following method: adding 50 parts by weight of perlite particles into 150 parts by weight of citric acid aqueous solution with the mass fraction of 15%, ultrasonically washing for 2h at the power of 200W and the frequency of 25kHz, transferring the perlite particles into a Buchner funnel, carrying out suction filtration and washing for 30min by using distilled water, drying and crushing the suction filtration product, and sieving the crushed product by using a 100-mesh sieve to obtain purified perlite particles; taking all the purified perlite particles, adding 150 parts by weight of an activating agent with the mass fraction of 3%, soaking at the temperature of 40 ℃ for 2h, filtering, placing the precipitate in a muffle furnace, heating to 450 ℃, calcining for 1h, and taking out to obtain activated perlite particles;

the activating agent is sodium hydroxide.

Example 6

Essentially the same as example 4, except that:

the activated perlite particles are prepared by the following method: adding 50 parts by weight of perlite particles into 150 parts by weight of citric acid aqueous solution with the mass fraction of 15%, ultrasonically washing for 2h at the power of 200W and the frequency of 25kHz, transferring the perlite particles into a Buchner funnel, carrying out suction filtration and washing for 30min by using distilled water, drying and crushing the suction filtration product, and sieving the crushed product by using a 100-mesh sieve to obtain purified perlite particles; taking all the purified perlite particles, adding 150 parts by weight of an activating agent with the mass fraction of 3%, soaking at 40 ℃ for 2h, filtering, placing the precipitate in a muffle furnace, heating to 450 ℃, calcining for 1h, and taking out to obtain activated perlite particles;

the activating agent is composed of sodium bicarbonate and sodium hydroxide according to the mass ratio of 1: 2.

Test example 1

(1) Preparation of a culture medium: naturally air-drying 700 parts by weight of soil, sieving to obtain uranium-free contaminated soil, sterilizing at 180 ℃ for 2h, cooling, averagely dividing into 7 groups, respectively and fully and uniformly stirring and mixing with 75 parts by weight of the mycorrhizal fungi agents of the embodiments 1-6 and commercially available fungi agent products to obtain a required culture medium, and putting the culture medium into 7 potted plants with the same size, wherein the culture medium is recorded as T1, T2, T3, T4, T5, T6 and CK;

(2) sowing, dividing 70 cucumber seeds into 7 groups, wherein each group comprises 10 cucumber seeds, planting 10 cucumber seeds in each pot plant of a control group and an experimental group at the same distance, and irrigating each pot plant by using the same amount of tap water;

(3) placing the potted plant in an illumination incubator, and setting the illumination to 7000 luxes, the temperature to 22 ℃ and the humidity to 50%;

(4) according to the dry and wet conditions of the potted plant substrate, water is supplemented every day, and the plant growth state is observed and recorded after 15 days.

The plant height, root length, fresh weight of the plant, seedling survival rate and pest and disease incidence of each group of cucumbers respectively applied with the mycorrhizal fungi agent prepared by the implementation steps 1-6 and the fungi agent sold in a control group are measured, and the results are shown in the table I below.

TABLE I, cucumber growth index determination

From the results, the comparison of T1 with a blank control shows that the growth effect of the cucumber seedlings without applying the microbial inoculum fertilizer is obviously inferior to that of the cucumber seedlings without applying the microbial inoculum fertilizer, so that the microbial inoculum fertilizer can promote the plant height, root length, fresh weight of plants and seedling survival rate of the plants, and reduce the incidence rate of plant diseases and insect pests of the seedlings; further comparing examples T1, T2 and T3, it can be seen that the mycorrhizal fungi obtained by using a solid culture medium of activated vermiculite or activated perlite particles in T2 and T3 have higher activity, because the activated vermiculite or activated perlite particles obtained by preparation have rich pore structures in the activation process to form a worm-like fluffy porous structure, so that the specific surface area of the activated vermiculite is greatly increased, the activated vermiculite can fully absorb nutrient substances in the culture process of the strains, the propagation and growth of the strains are promoted, the poultry fertilizer is used as an organic carrier, the arbuscular mycorrhizal fungi are added, and the nitrogen, phosphorus and other trace elements in the inorganic mineral fertilizer are matched to combine the long-acting property of the fertilizer, the unique physiological regulation function of microorganisms and the high efficiency of the mineral fertilizer to prepare the organic compound fertilizer special for cucumbers, and the fertilizer improves the utilization rate of the fertilizer while reducing the using amount, The yield and the quality of the cucumbers have the effects of balancing nutrition supply, increasing the fertility of soil and promoting the growth of the cucumbers; comparing examples T2, T3 and T4, it can be seen that the good growth of cucumber can be further promoted by adopting the activated vermiculite powder and the activated perlite particles, and meanwhile, the occurrence of plant diseases and insect pests is reduced; the reason is that the activated vermiculite powder and the activated perlite particles can play a role in synergy, and the activated vermiculite and the activated perlite particles have rich pore structures in the activation process to form a worm-like fluffy porous structure, so that the specific surface area of the activated vermiculite is greatly improved, and the activated vermiculite powder and the activated perlite particles are beneficial to fully absorbing nutrient substances in the strain culture process; further comparing examples T4, T5, and T6, it can be seen that the activated perlite adopted in T6, which is prepared by compounding a modifier of sodium bicarbonate and sodium hydroxide, can be used for preparing a culture medium of a mycorrhizal inoculant, and has a significant effect on the growth of cucumbers, because perlite is ultrasonically cleaned by an acidic citric acid aqueous solution to increase the porosity and specific surface area of the perlite, and then an activator is added, sodium bicarbonate can be gradually decomposed under heating, and generated carbon dioxide needs to overflow from perlite particles, so that the porosity of perlite can be increased; under the high-temperature activation of sodium hydroxide, the crystalline inactive aluminosilicate in the perlite particles is converted into amorphous active aluminosilicate, and the water in the perlite in the roasting process is vaporized by utilizing the synergistic effect of sodium bicarbonate and sodium hydroxide, so that a porous structure with rich porosity and large specific surface area is formed. The mycorrhizal fungi agent prepared by the culture medium prepared by the specific method can greatly improve the survival rate and the reproduction rate of bacteria.

Test example 2

And (3) determining the content of heavy metal: (1) naturally air-drying 700 parts by weight of soil, sieving to obtain uranium-free contaminated soil, sterilizing at 180 ℃ for 2h, cooling, averagely dividing into 7 groups, respectively and fully and uniformly stirring and mixing with 75 parts by weight of the mycorrhizal fungi agents of the embodiments 1-6 and commercially available fungi agent products to obtain a required culture medium, and putting the culture medium into 7 potted plants with the same size, wherein the culture medium is recorded as K1, K2, K3, K4, K5, K6 and CK;

(3) the same lead and cadmium contaminated soil was artificially applied to each of the 7 pots at a lead concentration of 500mg/kg and Pb (NO) as an application material₃)₂Cadmium concentration of 120mg/kg, respectively, and Cd (NO) as an application substance₃)₂(ii) a Ca (NO) is additionally added into each pot plant₃)₂To make NO in soil of various pollution levels^3-The content is the same, the seedlings cultivated in the test example 1 are transplanted to K1, K2, K3, K4, K5, K6 and CK, 4 seedlings are uniformly planted in each pot, the test is carried out in a sunlight greenhouse, the maximum water holding capacity of the plants is kept at 70% during the growth period of the plants, the plants are harvested after 60 days of transplantation, the test is carried out for 4 times, the average value is taken, and the test results are shown in Table II.

TABLE II test results of heavy metal contamination

From the results, the microbial inoculum obtained by applying the specific culture medium for culture can adsorb heavy metal ions, so that the heavy metal residual quantity of the crop roots is reduced, the reason is that the solid culture medium adopted by the invention is a solid substrate with large porous specific surface area and strong adsorbability, compared with blank groups CK1 and K1-K3, the blank group adopts the microbial inoculum sold in the market to have a remarkably large adsorption effect on the heavy metals, seedlings die in the polluted soil artificially added with cadmium, the mycorrhizal microbial inoculum obtained by culturing the mycorrhiza by adopting the activated vermiculite powder or the activated perlite particles can obviously reduce the content of the heavy metals in the crop roots, the reason is that the activated vermiculite powder or the activated perlite particles have large specific surface area and can adsorb the heavy metals as the substrate for culturing the crops, so that the adsorption of the heavy metals by the crop roots is reduced, thereby improving the growth of crops; compared with K2-K4, the effect of adsorbing heavy metal by compounding K4 with the activated vermiculite powder and the activated perlite particles is obviously better than that of a microbial inoculum obtained by culturing strains by adopting any one of the activated substrates K2 or K3, the reason is obvious, and meanwhile, the specific surface area compounded by adopting the activated vermiculite powder and the activated perlite particles is obviously larger than that compounded by adopting the activated vermiculite powder or the activated perlite particles, so that the effect of adsorbing heavy metal is also obviously increased, and the heavy metal pollution of the heavy metal to the root systems of crops and the overground parts is reduced; finally, compared with K4-K6, the activated perlite prepared by compounding sodium bicarbonate and sodium hydroxide as a modifier in K6 can be used for preparing a culture medium of the mycorrhizal fungi agent, and the mycorrhizal fungi agent obtained finally can increase the effect of adsorbing heavy metals when used for cultivating crops, so that the adsorption of crop roots to the heavy metals is reduced, because the perlite is subjected to ultrasonic cleaning by using an acidic citric acid aqueous solution to increase the porosity and the specific surface area of the perlite, and the sodium bicarbonate can be gradually decomposed under the heating condition by adding an activating agent, so that the generated carbon dioxide needs to overflow from perlite particles, and the porosity of the perlite can be increased; under the high-temperature activation of sodium hydroxide, crystalline inactive aluminosilicate in perlite particles is converted into amorphous active aluminosilicate, and the water in the perlite during the roasting process is vaporized by utilizing the synergistic effect of sodium bicarbonate and sodium hydroxide, so that a porous structure with rich porosity and large specific surface area is formed, the adsorption effect on heavy metals can be greatly improved, the adsorption of crops on the heavy metals is reduced, and the survival rate and the quality of the crops in the environment polluted by the heavy metals are improved.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims

1. A preparation method of a mycorrhizal fungi agent is characterized by comprising the following steps:

s1, strain propagation: uniformly mixing 8-12 parts by weight of distilled water, 10-30 parts by weight of bran, 2-8 parts by weight of ammonium molybdate, 1-3 parts by weight of sodium tripolyphosphate and 1-5 parts by weight of glucose, sterilizing at 110-;

s2, preparation: adding a propagation strain into a solid culture medium, uniformly mixing, wherein the addition amount of the propagation strain is 10-30 wt% of the solid culture medium, sowing sudan grass seeds, the content of the sudan grass seeds is 1-5 wt% of the solid culture medium, uniformly mixing, after emergence of seedlings, continuously culturing for 2-3 months, cutting off the overground part of the sudan grass, cutting up root segments, uniformly mixing with a culture medium, drying and crushing a preparation to obtain a mycorrhizal fungi agent;

the preparation method of the solid medium in the step S2 includes: uniformly mixing 40-80 parts by weight of distilled water, 200-400 parts by weight of bran, 30-50 parts by weight of activated vermiculite powder, 30-50 parts by weight of activated perlite particles, 30-60 parts by weight of ammonium molybdate, 10-30 parts by weight of sodium tripolyphosphate and 2-5 parts by weight of glucose, and stirring at room temperature for 3-10min to obtain a solid culture medium;

the activated vermiculite powder is prepared by the following method: putting 40-60 parts by weight of vermiculite powder into a rotary frying pan with the temperature of 60-80 ℃ for constant-temperature frying for 15-25min, taking out, immersing into 80-120 parts by weight of 3-10 wt% glucose aqueous solution for 20-40min, carrying out ultrasonic treatment for 20-40min by ultrasonic waves with the power of 120-140W and the frequency of 20-50kHz, filtering, putting the precipitate into a muffle furnace, heating to the temperature of 700-900 ℃, carrying out heat preservation and calcination for 1-4h, and taking out to obtain activated vermiculite powder;

the activated perlite particles are prepared by the following method: pouring 40-60 parts by weight of perlite particles into an ultrasonic cleaning instrument, ultrasonically cleaning 120-160 parts by weight of 10-20% citric acid aqueous solution at the power of 150-220W and the ultrasonic frequency of 20-50kHz for 1-3h, then transferring the cleaned product into a Buchner funnel, performing suction filtration and washing for 20-40min by using distilled water, drying the suction filtration product, crushing the dried product, and sieving the crushed product by using a 80-120-mesh standard sieve to obtain purified perlite particles; taking all the purified perlite particles, adding 120-180 parts by weight of an activating agent with the mass fraction of 1-5%, soaking at the temperature of 30-50 ℃ for 1-3h, filtering, placing the precipitate in a muffle furnace, heating to 400-500 ℃, calcining for 0.5-2h, and taking out to obtain activated perlite particles;

the activating agent is sodium bicarbonate and sodium hydroxide, and the mass ratio of the sodium bicarbonate to the sodium hydroxide is 1: (1-3).

2. The method for preparing a mycorrhizal fungi agent according to claim 1, characterized in that: the strain in the S1 is arbuscular mycorrhiza.

3. The method for preparing a mycorrhizal fungi agent according to claim 1, characterized in that: the strain inoculation amount in the S1 is 0.2-1.5 wt% of the mass of the liquid culture medium, and the sudan grass seeds are 1-5 wt% of the mass of the liquid culture medium.

4. The method for preparing a mycorrhizal fungi agent according to claim 1, characterized in that: the method comprises the following steps:

s1, strain propagation: uniformly mixing 10 parts by weight of distilled water, 20 parts by weight of bran, 6 parts by weight of ammonium molybdate, 2 parts by weight of sodium tripolyphosphate and 3 parts by weight of glucose, sterilizing for 30min at 121 ℃, cooling to obtain a propagation culture medium, inoculating a strain and Sudan grass seeds, performing sterile culture in a plant tissue culture bottle at the temperature of 30 ℃ for 4 weeks, and taking roots and the culture medium as propagation strains; the strain inoculation amount is 1 wt% of the mass of the liquid culture medium, and the sudan grass seeds are 2 wt% of the mass of the liquid culture medium;

the preparation method of the solid culture medium comprises the following steps: uniformly mixing 60 parts by weight of distilled water, 300 parts by weight of bran, 40 parts by weight of activated vermiculite powder, 40 parts by weight of activated perlite particles, 40 parts by weight of ammonium molybdate, 20 parts by weight of sodium tripolyphosphate and 3 parts by weight of glucose, and stirring at room temperature for 5min to obtain a solid culture medium;

5. A mycorrhizal fungi agent prepared by the method of any one of claims 1 to 4.