Seed coating agent and method for improving the effect of arbuscular mycorrhizal fungi infecting crops

Abstract

The present invention relates to the field of arbuscular mycorrhizal bioremediation technology, and more particularly to a seed coating agent and method for improving the effectiveness of arbuscular mycorrhizal fungi in infecting crops. The present invention provides a seed coating agent for improving the effectiveness of arbuscular mycorrhizal fungi in infecting crops, comprising the following components: an arbuscular mycorrhizal fungi inoculant, straw compost, a water-retaining agent, chitosan oligosaccharides, an adhesive, and a film-forming agent. The seed coating agent is mixed with seeds to form seed pellets, which are then incubated for 50 to 70 minutes. This method can effectively improve the effectiveness of arbuscular mycorrhizal fungi in infecting crops, requires a small amount of arbuscular mycorrhizal fungi, and has a simple and easy-to-use process.

Description

Technical Field

[0001] The invention relates to the technical field of arbuscular mycorrhizal bioremediation, in particular to a seed coating agent and a method for improving the effect of arbuscular mycorrhizal fungi infecting crops. Background Art

[0002] In recent years, heavy metal contamination in soils has intensified due to the introduction of large quantities of heavy metal ions into the environment through industrial, mining, and agricultural activities. These heavy metals migrate through the soil-plant system into crops through physical, chemical, and biological processes such as leaching and adsorption, causing physiological dysfunction and nutritional imbalances in crops, thereby affecting their growth, yield, and quality. These heavy metals can also enter the human body through the food chain, posing a potentially significant threat to human health and life.

[0003] Arbuscular mycorrhizal fungi (AMF) are a very important group of mycorrhizal fungi in nature, and they coexist with a wide range of plants. Nearly 90% of plants in nature form symbiotic relationships with AMF. Studies have shown that AMF can enhance host plant resistance to heavy metal stress by regulating the absorption and transport of heavy metals. AMF can penetrate plant walls, entering the cortical cells to form the periphyton membrane (PAM). This interface allows for the exchange of substances between AMF and the plant. The other end of the fungal hyphae grows into crevices inaccessible to roots, indirectly increasing the contact area between roots and soil, promoting the absorption of essential nutrients, improving plant nutritional status, and enhancing resistance to adverse external factors. Glomalin, produced by the mycelium, acts as a "super glue," adhering to soil particles 3 to 10 times more effectively than other soil carbohydrates. Currently, the application of AMF in plants primarily involves mixing an appropriate amount of microbial agent into the seedling medium to cultivate mycorrhized seedlings, followed by normal transplanting and then applying the appropriate amount of microbial agent in holes or strips at sowing. This method has the disadvantages of requiring a large amount of AMF, high cost, and low infection intensity and arbuscular richness. Therefore, finding a low-cost AMF infection method with high infection rate (intensity) is crucial for improving AMF application in agriculture. Summary of the Invention

[0004] The present invention aims to provide a seed coating agent and method for improving the effect of arbuscular mycorrhizal fungi on infecting crops. The method can effectively improve the effect of arbuscular mycorrhizal fungi on infecting crops, and the amount of arbuscular mycorrhizal fungi used is small, the process is simple, and the operation is easy.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a seed coating agent for improving the effect of arbuscular mycorrhizal fungi infecting crops, comprising the following components: an arbuscular mycorrhizal fungi agent, straw compost, a water-retaining agent, chitosan oligosaccharide, an adhesive and a film-forming agent;

[0007] The mass ratio of chitosan oligosaccharide to arbuscular mycorrhizal fungi agent is 1:20-40;

[0008] The mass ratio of chitosan oligosaccharide to straw compost is 1:112-132;

[0009] The mass ratio of chitosan oligosaccharide to water retaining agent is 1:2-6;

[0010] The mass volume ratio of chitosan oligosaccharide and adhesive is 1g:33-53mL;

[0011] The mass volume ratio of chitosan oligosaccharide and film-forming agent is 1g:30-50mL.

[0012] Preferably, the effective species in the arbuscular mycorrhizal fungal agent is Heterosporangium heterorhizogenes; and the number of propagules of the arbuscular mycorrhizal fungal agent is ≥70 / g.

[0013] Preferably, the method for preparing the straw compost comprises the following steps:

[0014] 1) mixing straw with a fermentation agent, cornmeal, urea, and superphosphate to obtain a mixed material;

[0015] 2) adjusting the water content of the mixed material to 50-70%, stacking and fermenting to obtain a fermentation product;

[0016] 3) airing the fermentation product until the moisture content reaches 10-20% to obtain straw compost;

[0017] The fermentation agent is a BFA fermentation agent; the mass ratio of the straw to the fermentation agent is 250-1000:1; the mass ratio of the straw to urea is 60-200:1; the mass ratio of the straw to superphosphate is 6-20:1; and the mass ratio of the straw to cornmeal is 25-100:0.8-1.2.

[0018] Preferably, the adhesive uses water as a solvent and includes the following components at the following concentrations: 20-80 g / L polyvinyl alcohol and 5-15 g / L sodium carboxymethyl cellulose.

[0019] Preferably, the film-forming agent uses water as a solvent and includes the following components in the following concentrations: 30-90 g / L polyvinyl alcohol, 10-30 g / L sodium carboxymethyl cellulose, and 10-30 g / L talc.

[0020] The present invention also provides a method for improving the effect of arbuscular mycorrhizal fungi infecting crops, comprising the following steps:

[0021] (1) mixing seeds and a seed coating agent to obtain seed pellets;

[0022] (2) Incubate the pellets for 50-70 minutes;

[0023] The seed coating agent is the seed coating agent described above.

[0024] Preferably, in step (2), the culture temperature is 25-35°C.

[0025] Beneficial effects of the present invention:

[0026] The invention provides a seed coating agent for improving the effect of arbuscular mycorrhizal fungi on infecting crops. The seed coating agent comprises an arbuscular mycorrhizal fungi agent, straw compost, a water-retaining agent, chitosan oligosaccharides, an adhesive and a film-forming agent. When the seed coating agent is used to treat seeds, the infection effect of the arbuscular mycorrhizal fungi agent can be significantly improved. Moreover, the amount of the arbuscular mycorrhizal fungi agent used is less than that of conventional infection methods, which saves costs, and the process is simple and easy to operate. The method can be used for cultivating plants in contaminated soil and planting crops in agricultural risk soil. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a standard chart for infestation grading;

[0028] Figure 2 It is the criterion for the richness of arbuscule branches;

[0029] Figure 3 This is the microscopic morphology of wheat root infection;

[0030] Figure 4 It is the microscopic morphology of sorghum root infection. DETAILED DESCRIPTION

[0031] The present invention provides a seed coating agent for improving the effect of arbuscular mycorrhizal fungi infecting crops, comprising the following components: an arbuscular mycorrhizal fungi agent, straw compost, a water-retaining agent, chitosan oligosaccharide, an adhesive and a film-forming agent;

[0032] The mass ratio of chitosan oligosaccharide to arbuscular mycorrhizal fungus agent is 1:20-40, preferably 1:25-35, and more preferably 1:30;

[0033] The mass ratio of chitosan oligosaccharide to straw compost is 1:112-132, preferably 1:117-127, and more preferably 1:122;

[0034] The mass ratio of chitosan oligosaccharide to water-retaining agent is 1:2-6, preferably 1:3-5, and more preferably 1:4;

[0035] The mass volume ratio of chitosan oligosaccharide to adhesive is 1g:33-53mL, preferably 1g:38-48mL, and more preferably 1g:43mL;

[0036] The mass volume ratio of chitosan oligosaccharide to film-forming agent is 1 g:30-50 mL, preferably 1 g:35-45 mL, and more preferably 1 g:40 mL.

[0037] In the present invention, the effective fungus species in the arbuscular mycorrhizal fungal agent is Heterosporangium heterorhizogenes; the number of propagules of the arbuscular mycorrhizal fungal agent is ≥70 per gram, preferably 75 to 85 per gram, and more preferably 80 per gram.

[0038] In the present invention, the method for preparing straw compost comprises the following steps:

[0039] 1) mixing straw with a fermentation agent, cornmeal, urea, and superphosphate to obtain a mixed material;

[0040] 2) adjusting the water content of the mixed material to 50-70%, stacking and fermenting to obtain a fermentation product;

[0041] 3) airing the fermentation product until the moisture content reaches 10-20% to obtain straw compost;

[0042] In step 1), the length of the straw is 2 to 5 cm, preferably 3 cm; the straw is corn straw; the fermentation agent is a BFA fermentation agent; the mass ratio of the straw to the fermentation agent is 250 to 1000:1; preferably 500 to 750:1, more preferably 625:1; the mass ratio of the straw to urea is 60 to 200:1, preferably 100 to 160:1, more preferably 130:1; the mass ratio of the straw to superphosphate is 6 to 20:1, preferably 10 to 16:1, more preferably 13:1; the mass ratio of the straw to cornmeal is 25 to 100:0.8 to 1.2, preferably 50 to 75:0.9 to 1.1, more preferably 62.5:1;

[0043] In step 2), the specific steps of the pile fermentation are: fermenting the mixed material at 55-65° C. for 9-11 days, turning the pile for the first time, and then turning the pile for another 9-11 days, and obtaining a fermentation product when the temperature is 35-45° C.;

[0044] Preferably, the mixed material is mixed and fermented at 60°C for 10 days, and then the compost is turned for the first time. After another 10 days of fermentation, the compost is turned for the second time. When the temperature reaches 40°C, a fermentation product is obtained.

[0045] The water content of the mixed material is preferably 60%;

[0046] The moisture content of the drying in step 3) is preferably 15%;

[0047] In the present invention, the preparation method of the water-retaining agent comprises the following steps:

[0048] (1) Mix straw compost, dimethyl sulfoxide, and catalyst and let it stand for 5 to 15 minutes, then filter and collect the residue;

[0049] (2) mixing the filter residue and the alkaline solution, and shaking to obtain a fortified compost;

[0050] (3) activating the fortified compost in a water bath to obtain activated fortified compost;

[0051] (4) mixing the activated fortified compost with neutralized acrylic acid, acrylamide, an initiator, and N,N'-methylenebisacrylamide, and heating for 25 to 35 minutes to obtain a black colloid;

[0052] (5) ultrasonically cleaning the black colloid and drying it to obtain a water-retaining agent;

[0053] The catalyst is a potassium hydroxide aqueous solution with a mass concentration of 1 to 3%, preferably 2%;

[0054] The alkaline solution is a potassium hydroxide aqueous solution with a mass concentration of 0.5-3%, preferably 1.5-2%, and more preferably 1.75%;

[0055] The initiator is a mixture of potassium persulfate and sodium thiosulfate; the mass ratio of potassium persulfate to sodium thiosulfate is 2-5:1-3, preferably 3.5:2;

[0056] The preparation method of the neutralized acrylic acid comprises: mixing acrylic acid and potassium hydroxide aqueous solution in an ice-water bath to obtain neutralized acrylic acid;

[0057] The mass concentration of the potassium hydroxide aqueous solution is 8-12%, preferably 10%;

[0058] The volume ratio of the acrylic acid to the potassium hydroxide aqueous solution is 1-3:3-7, preferably 2:5.

[0059] In the present invention, the standing time in step (1) is preferably 9 to 11 minutes, more preferably 10 minutes;

[0060] The oscillation temperature is 25-35°C, preferably 29-31°C, more preferably 30°C; the oscillation time is 15-25 minutes, preferably 19-21 minutes, more preferably 20 minutes;

[0061] The water bath activation temperature is 65-85°C, preferably 70-80°C, more preferably 75°C, and the water bath activation time is 30-60 min, preferably 40-50 min, more preferably 45 min;

[0062] The heating is water bath heating; the heating temperature is 70-90°C, preferably 78-82°C, more preferably 80°C; the heating time is preferably 30 minutes.

[0063] The drying temperature is 40-60°C, preferably 45-55°C, and more preferably 50°C.

[0064] In the present invention, the mass volume ratio of the straw compost and dimethyl sulfoxide is 1-3 g: 3-7 mL, preferably 2 g: 5 mL;

[0065] The mass volume ratio of the straw compost and the catalyst is 1-3 g: 20-30 mL, preferably 2 g: 25 mL;

[0066] The mass volume ratio of the straw compost and the alkaline solution is 1-3 g:40-60 mL, preferably 2 g:50 mL;

[0067] The mass volume ratio of the straw compost and the neutralized acrylic acid is 1-3 g: 2-11 mL, preferably 2 g: 6.5 mL;

[0068] The mass ratio of the straw compost to acrylamide is 1-3:0.5-5.0, preferably 2:2.75;

[0069] The mass ratio of the straw compost to the initiator is 1-3:0.22-0.42, preferably 2:0.32;

[0070] The mass ratio of the straw compost to N,N'-methylenebisacrylamide is 1-3:0.01-0.09, preferably 2:0.05.

[0071] In the present invention, the adhesive uses water as a solvent and includes the following components in mass concentrations:

[0072] Polyvinyl alcohol 20-80 g / L, preferably 30-60 g / L, more preferably 40 g / L,

[0073] Sodium carboxymethylcellulose 5 to 15 g / L, preferably 8 to 12 g / L, more preferably 10 g / L.

[0074] In the present invention, the film-forming agent uses water as a solvent and includes the following components in mass concentrations:

[0075] Polyvinyl alcohol 30-90 g / L, preferably 50-70 g / L, more preferably 60 g / L,

[0076] Sodium carboxymethyl cellulose 10-30 g / L, preferably 15-25 g / L, more preferably 20 g / L,

[0077] The content of talc is 10 to 30 g / L, preferably 15 to 25 g / L, and more preferably 20 g / L.

[0078] The present invention also provides a method for improving the effect of arbuscular mycorrhizal fungi infecting crops, comprising the following steps:

[0079] (1) mixing seeds and a seed coating agent to obtain seed pellets;

[0080] (2) Incubate the pellets for 50-70 minutes;

[0081] The seed coating agent is the seed coating agent described above.

[0082] In the present invention, before the seeds and the seed coating agent are mixed, the seeds need to be treated, and the specific steps are as follows:

[0083] After soaking the seeds in water for 2 hours, wrap them with a damp cloth, transfer them to a white porcelain plate, and incubate them at a temperature of 20-30°C and a humidity of 70-80% for 24-48 hours, turning the seeds every 12 hours.

[0084] The culture temperature is preferably 23-27°C, more preferably 25°C; the culture humidity is preferably 73-77%, more preferably 75%; the culture time is preferably 32-42 hours, more preferably 36 hours;

[0085] The specific steps of mixing the seeds and the seed coating agent are as follows: crushing the water retaining agent and straw compost to 200 mesh, stirring and mixing with seeds, arbuscular mycorrhizal fungi agent, chitosan oligosaccharide, indole fresh fat and adhesive, forming pellets, and adding a film-forming agent to obtain seed pellets.

[0086] In the present invention, in step (2), the culture temperature is 25-35°C, preferably 28-32°C, and more preferably 30°C.

[0087] The technical solutions provided by the present invention are described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0088] In the examples and comparative examples of the present invention, the arbuscular mycorrhizal fungal agent was purchased from Beijing Jinbilai Biotechnology Co., Ltd., chitosan oligosaccharide was purchased from Shandong Hailongyuan Biotechnology Co., Ltd., indole fresh fat was purchased from Zhengzhou Dehua Xinlu Pesticide Co., Ltd., and BFA fermentation agent was purchased from Fujian Oasis Biochemical Co., Ltd.

[0089] Example 1

[0090] Preparation of straw compost: 300 kg of corn straw was dried and crushed into segments with a length of 2 cm, 1.2 kg of BFA fermentation agent, 14.4 kg of cornmeal, 5 kg of urea, and 30 kg of superphosphate were added and mixed to obtain a mixture; the moisture content of the mixture was adjusted to 55%, and the mixture was piled into strips, the surface of which was covered with a nano-biocompost film; after mixing and fermenting at 60°C for 10 days, the pile was turned for the first time, and after fermenting for another 10 days, the pile was turned for the second time. When the temperature reached 40°C, a fermentation product was obtained; the fermentation product was air-dried until the moisture content was 17% to obtain straw compost.

[0091] Preparation of neutralized acrylic acid: 4 mL of acrylic acid and 13.6 mL of 12% potassium hydroxide aqueous solution were mixed and allowed to stand in an ice-water bath for 20 min to obtain neutralized acrylic acid.

[0092] Preparation method of the initiator: Potassium persulfate and sodium thiosulfate are mixed in a mass ratio of 3:1 to prepare the initiator.

[0093] The preparation of water retaining agent includes:

[0094] (1) Mix 3 g of straw compost, 6 mL of dimethyl sulfoxide, and 30 mL of 2% potassium hydroxide aqueous solution, let it stand for 12 minutes, and filter to obtain the residue;

[0095] (2) Add 165 mL of 2.46% potassium hydroxide aqueous solution to the filter residue and shake at 25° C. for 25 min to obtain enhanced compost.

[0096] (3) activating the fortified compost in a water bath at 85°C for 48.8 minutes to obtain activated fortified compost;

[0097] (4) The activated fortified compost was mixed with 26.4 mL of neutralized acrylic acid, 4.47 g of acrylamide, 0.78 g of initiator, and 0.06 g of N,N'-methylenebisacrylamide, and heated in a water bath at 90 °C for 25 min to obtain a black colloid;

[0098] (5) The black colloid was ultrasonically cleaned at 30° C. for 5 min and dried at 60° C. to obtain a water-retaining agent.

[0099] Preparation of adhesive: Dissolve 6 g of polyvinyl alcohol and 1 g of sodium carboxymethyl cellulose in water and dilute to 100 mL to obtain an adhesive.

[0100] Preparation of film-forming agent: Dissolve 5 g of polyvinyl alcohol, 2 g of sodium carboxymethyl cellulose and 2 g of talc in water and dilute to 100 mL to obtain a film-forming agent.

[0101] A method for improving the effect of arbuscular mycorrhizal fungi infecting crops:

[0102] (1) After soaking the seeds in water for 2 h, wrap them with a wet cloth, transfer them to a white porcelain plate, and place them in an incubator at 25°C and 75% humidity for 48 h. The seeds are turned over every 12 h to obtain seeds to be treated; 100 g of seeds to be treated are mixed with 15 g of arbuscular mycorrhizal fungus agent (the number of propagules is 80 / g), 2 g of water-retaining agent (crushed to 200 mesh), 61 g of straw compost (crushed to 200 mesh), 0.5 g of chitosan oligosaccharide, and 21.5 mL of adhesive, and the mixture is stirred and pelleted. After the pellets are formed, 20 mL of film-forming agent is added to wrap the pellets;

[0103] (2) Place the seed pellets in an incubator at 30°C for 1 hour.

[0104] Comparative Example 1

[0105] The preparation steps of straw compost, adhesive and film-forming agent are the same as those in Example 1;

[0106] A method for improving the effect of arbuscular mycorrhizal fungi infecting crops:

[0107] 1) Soak the seeds in water for 2 hours, wrap them with a damp cloth, transfer them to a white porcelain plate, and incubate them in an incubator at 25°C and 75% humidity for 48 hours, turning the seeds every 12 hours. Then, mix 100 g of seeds with 15 g of arbuscular mycorrhizal fungus inoculant (80 propagules / g), 63.5 g of straw compost (crushed to 200 mesh), and 21.5 mL of adhesive, forming pellets. Then, add 20 mL of film-forming agent and wrap the pellets.

[0108] (2) Place the seed pellets in an incubator at 30°C for 1 hour.

[0109] Comparative Example 2

[0110] The preparation steps of straw compost, water retaining agent, adhesive and film forming agent are the same as those in Example 1;

[0111] (1) After soaking the seeds in water for 2 h, wrap them with a wet cloth, transfer them to a white porcelain plate, and place them in an incubator at 25°C and 75% humidity for 48 h, turning the seeds every 12 h. 100 g of seeds were mixed with 15 g of arbuscular mycorrhizal fungus agent (with 80 propagules / g), 2 g of water-retaining agent (crushed to 200 mesh), 61.5 g of straw compost (crushed to 200 mesh), and 21.5 mL of adhesive, and then 20 mL of film-forming agent was added to form pellets.

[0112] (2) Place the seed pellets in an incubator at 30°C for 1 hour.

[0113] Comparative Example 3

[0114] The preparation steps of straw compost, water retaining agent, adhesive and film forming agent are the same as those in Example 1;

[0115] A method for improving the effect of arbuscular mycorrhizal fungi infecting crops:

[0116] (1) After soaking the seeds in water for 2 h, wrap them with a wet cloth, transfer them to a white porcelain plate, and place them in an incubator at 25°C and 75% humidity for 48 h, turning the seeds every 12 h. 100 g of seeds were mixed with 15 g of arbuscular mycorrhizal fungus agent (with 80 propagules / g), 2 g of water-retaining agent (crushed to 200 mesh), 60 g of straw compost (crushed to 200 mesh), 0.5 g of chitosan oligosaccharide, 1 mL of indole ethyl ester, and 21.5 mL of adhesive, and stirred to form pellets. 20 mL of film-forming agent was then added to wrap the pellets.

[0117] (2) Place the seed pellets in an incubator at 30°C for 1 hour.

[0118] Experimental Example 1

[0119] The experiment was conducted at the Xichang University Innovation and Entrepreneurship Greenhouse Planting Base, using pots with a diameter of 15 cm and a height of 12.5 cm as cultivation containers (a tray was placed at the bottom to prevent nutrient loss).

[0120] Uncontaminated soil: Soil was collected from the forest on the campus of Xichang University, placed in a ventilated place, air-dried, and then passed through a 20-mesh sieve. Its physical and chemical properties were as follows: pH 8.55, organic matter 15.38 g / kg, total nitrogen 0.77 g / kg, alkaline-hydrolyzable nitrogen 39.30 mg / kg, total phosphorus 0.42 g / kg, available phosphorus 12.07 mg / kg, total potassium 19.0 g / kg, available potassium 71 mg / kg, and cadmium 0.76 mg / kg.

[0121] 10mg / kg cadmium contaminated soil: 10mg / kg cadmium (using CdCl2·2.5H2O) was added to uncontaminated soil at one time for soil aging. After aging for two weeks, cadmium contaminated soil was obtained.

[0122] 100 g of wheat seeds were treated using the methods described in Example 1 and Comparative Examples 1 to 3, respectively. 2 kg of soil was added to each pot before sowing. A total of 10 treatments were set up in the experiment, A0, B0, C0, D0, and E0 were respectively sown in uncontaminated soil with wheat seeds that had not been coated, wheat seeds treated by the method described in Example 1, wheat seeds treated by the method described in Comparative Example 1, wheat seeds treated by the method described in Comparative Example 2, and wheat seeds treated by the method described in Comparative Example 3; A10 、B 10 、C 10 、D 10 、E 10 The wheat seeds that have not been coated, the wheat seeds that have been treated by the method described in Example 1, the wheat seeds that have been treated by the method described in Comparative Example 1, the wheat seeds that have been treated by the method described in Comparative Example 2, and the wheat seeds that have been treated by the method described in Comparative Example 3 are sown in 10 mg / kg cadmium-contaminated soil respectively; A0, A 10 Using the traditional infection method (applying 2g of mycorrhizal fungi directly next to the seeds), 2g of Heterospora heterorhizogenes was added to each pot through a hole-dose method. Regular watering was carried out during the planting period to ensure normal growth and development of the crops. After 30 days of greenhouse cultivation, the pots were brought back to the laboratory for relevant testing.

[0123] Five seedlings were selected for each treatment, and the roots were washed with pure water and cut into 1 cm root segments. The method of Trouvelot et al. (Trouvelot A, Kough JL, Gianinazzi-Pearson V. Measurement of demycorrhization V A d'unsystème radiculaire. Recherched eméthods d'estimation ayantune signification fonctionelle. In: Physiological and Genetical Aspects of Mycorrhiza e. Paris: INR Press, 1986: 217-221) was used. The roots were transparentized with 10% (w / v) potassium hydroxide, bleached with 10% hydrogen peroxide, acidified with 2% HCl, stained with lactophenol cotton blue dye, and observed under a microscope for AMF infection (such as Figure 3 The results are shown in Tables 1 and 2.

[0124] Among them, mycorrhizal infection frequency F% = (number of infected root segments / total number of root segments) × 100%;

[0125] Root infection intensity M% = (95×n5+70×n4+30×n3+5×n2+n1) / (total number of root segments)% (where n5 represents the number of root segments with level 5 infection; n4 represents the number of root segments with level 4 infection, n3 represents the number of root segments with level 3 infection, n2 represents the number of root segments with level 2 infection, and n1 represents the number of root segments with level 1 infection). The infection grading standards are as follows: Figure 1 shown);

[0126] m%=M×(number of total root segments) / (number of infected root segments)%;

[0127] Abundance of infected root segments a% = (100 × mA3 + 50 × mA2 + 10 × mA1) / 100 (where mA3 = [(95 × n5 × A3 + 70 × n4 × A3 + 30 × n3 × A3 + 5 × n2 × A3 + n1 × A3) / (number of infected root segments)] × 100 / m, mA2 = [(95 × n5 × A2 + 70 × n4 × A2 + 30 × n3 × A2 + 5 × n2×A2+n1×A2) / (number of infected root segments)]×100 / m, mA1=[(95×n5×A1+70×n4×A1+30×n3×A1+5×n2×A1+n1×A1) / (number of infected root segments)]×100 / m; A3 is the number of root segments with abundant arbuscules, A2 is the number of root segments with more arbuscules, and A1 is the number of root segments with fewer arbuscules. The criteria for the degree of arbuscule abundance are as follows: Figure 2 shown);

[0128] Root arbuscule abundance A% = a% × (M / 100).

[0129] Table 1 Mycorrhizal infection degree of wheat in uncontaminated soil

[0130] deal with Infection frequency F (%) Infection intensity M (%) Arbuscular abundance A(%) <![CDATA[A0]]> <![CDATA[80.41±2.64 c ]]> <![CDATA[2.83±0.69 d ]]> <![CDATA[5.98±1.49 e ]]> <![CDATA[B0]]> <![CDATA[98.89±1.09 a ]]> <![CDATA[18.37±4.096 a ]]> <![CDATA[38.5±4.06 a ]]> <![CDATA[C0]]> <![CDATA[91.11±2.81 b ]]> <![CDATA[7.09±0.593 c ]]> <![CDATA[12.68±0.64 d ]]> <![CDATA[D0]]> <![CDATA[92.22±1.48 b ]]> <![CDATA[7.92±0.925 c ]]> <![CDATA[16.2±2.75 c ]]> <![CDATA[E0]]> <![CDATA[94.44±1.93 ab ]]> <![CDATA[9.61±0.019 b ]]> <![CDATA[21.08±4.37 b ]]>

[0131] Table 2 Degree of mycorrhizal infection of wheat in 10 mg / kg cadmium-contaminated soil

[0132]

[0133]

[0134] from Figure 3 It can be seen that compared with the traditional infection methods A0 and A 10 Compared with the wheat seed coating treatments B0, C0, D0, E0, B 10 、C 10 、D 10 、E 10 The mycelium in the roots increased, among which B0, B 10 treatment, the hyphae in the roots were denser and had obvious vesicles;

[0135] From Table 1 and Table 2, we can see that the frequency F%, infection intensity M%, and arbuscular abundance A% of mycorrhizal fungi infecting wheat roots decreased under heavy metal stress. Compared with A0, A 10The infection frequency F%, infection intensity M%, and arbuscular abundance A% of the treatments decreased by 12.1%, 26.1%, and 28.3%, respectively. Compared with A0, the seed coating treatments B0, C0, D0, and E0 significantly increased the values ​​of F%, M%, and A%, especially B0. Compared with A0, the values ​​of F%, M%, and A% of B0 treatment increased by 23.0%, 549.1%, and 543.8%, respectively. 10 Compared with the seed coating treatment B 10 、C 10 、D 10 、E 10 Significantly improved the values ​​of F%, M%, and A%, especially B 10 The largest increase; 10 In comparison, B 10 The values ​​of treatment F%, M%, and A% increased by 33.5%, 564.6%, and 511.2%, respectively;

[0136] Therefore, B0 and B 10 After coating, the infection rate, infection intensity and arbuscular abundance of Cysticercus heterocystis on wheat roots increased; the coating agent and method described in Example 1 had the best infection effect on wheat roots.

[0137] Experimental Example 2

[0138] 100 g of sorghum seeds were treated with the methods described in Example 1 and Comparative Examples 1 to 3, respectively. Referring to the method described in Experimental Example 1, the AMF infection was observed (e.g. Figure 4 The results are shown in Tables 3 and 4.

[0139] Table 3 Mycorrhizal infection degree of sorghum in uncontaminated soil

[0140] deal with Infection frequency F (%) Infection intensity M (%) Arbuscular abundance A(%) A0 <![CDATA[67.02±1.86 d ]]> <![CDATA[1.48±0.89 d ]]> <![CDATA[4.11±1.54 d ]]> <![CDATA[B0]]> <![CDATA[95.83±1.54 a ]]> <![CDATA[6.46±0.41 a ]]> <![CDATA[20.38±4.74 a ]]> <![CDATA[C0]]> <![CDATA[82.72±4.69 c ]]> <![CDATA[2.14±0.67b cd ]]> <![CDATA[5.94±1.22 cd ]]> <![CDATA[D0]]> <![CDATA[88.89±3.85 bc ]]> <![CDATA[3.33±0.86 bc ]]> 7.57±2.35c <![CDATA[E0]]> <![CDATA[92.43±3.25 ab ]]> 4.02±0.68b <![CDATA[11.08±2.03 b ]]>

[0141] Table 4. Infection degree of sorghum mycorrhiza in 10 mg / kg cadmium-contaminated soil

[0142] deal with Infection frequency F(%) Infection intensity M (%) Arbuscular abundance A(%) <![CDATA[A 10 ]]> <![CDATA[59.03±2.27 d ]]> <![CDATA[1.02±0.38 c ]]> <![CDATA[3.31±1.03 d ]]> <![CDATA[B 10 ]]> <![CDATA[91.11±1.92 a ]]> <![CDATA[5.68±0.15 a ]]> <![CDATA[13.15±3.65 a ]]> <![CDATA[C 10 ]]> <![CDATA[77.49±8.25 c ]]> <![CDATA[1.69±0.83 c ]]> <![CDATA[4.88±0.62 cd ]]> <![CDATA[D 10 ]]> <![CDATA[83.08±4.34 bc ]]> <![CDATA[3.61±0.45 b ]]> <![CDATA[5.74±1.19 bc ]]> <![CDATA[E 10 ]]> <![CDATA[86.38±3.37 b ]]> <![CDATA[4.81±0.66 ab ]]> <![CDATA[7.33±2.52 b ]]>

[0143] from Figure 4 It can be seen that the traditional infection methods A0 and A 10 Compared with the sorghum seed coating treatments B0, C0, D0, E0, B 10 、C 10 、D 10 、E 10 The mycelium in the roots increased, among which B0, B 10 treatment, the hyphae in the roots were more dense;

[0144] From Tables 3 and 4, we can see that the F%, M%, and A% of mycorrhizal fungi on sorghum roots decreased under heavy metal stress. 10 The infection frequency F%, infection intensity M%, and arbuscular abundance A% of the treatments decreased by 11.9%, 31.1%, and 19.5%, respectively. Compared with A0, the seed coating treatments B0, C0, D0, and E0 significantly increased the values ​​of F%, M%, and A%, especially B0. Compared with A0, the values ​​of F%, M%, and A% of B0 treatment increased by 43.0%, 336.5%, and 395.9%, respectively. 10 Compared with the seed coating treatment B 10 、C 10 、D 10 、E 10 Significantly improved the values ​​of F%, M%, and A%, especially B 10 The largest increase; 10 In comparison, B 10 The values ​​of treatment F%, M%, and A% increased by 54.3%, 456.9%, and 297.3%, respectively;

[0145] Therefore, B0 and B 10 After coating, the infection rate, infection intensity and arbuscule abundance of Cysticercus heterocystis on sorghum roots increased. The coating agent and method described in Example 1 had the best infection effect on sorghum roots.

[0146] As can be seen from the above examples, the present invention provides a seed coating agent and method for improving the effect of arbuscular mycorrhizal fungi on crop infection. The method can effectively improve the effect of arbuscular mycorrhizal fungi on crop infection, and the amount of arbuscular mycorrhizal fungi used is small, the process is simple, and the operation is easy.

[0147] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A seed coating agent for improving the effect of arbuscular mycorrhizal fungi infecting crops, characterized in that: The invention comprises the following components: arbuscular mycorrhizal fungi agent, straw compost, water retaining agent, chitosan oligosaccharide, adhesive and film-forming agent; The mass ratio of chitosan oligosaccharide to arbuscular mycorrhizal fungi agent is 1:20-40; The mass ratio of chitosan oligosaccharide to straw compost is 1:112-132; The mass ratio of chitosan oligosaccharide to water retaining agent is 1:2-6; The mass volume ratio of chitosan oligosaccharide and adhesive is 1g:33-53mL; The mass volume ratio of chitosan oligosaccharide and film-forming agent is 1g:30-50mL; The adhesive uses water as solvent and includes the following components in the following concentrations: 20-80 g / L polyvinyl alcohol, 5-15 g / L sodium carboxymethyl cellulose; The film-forming agent uses water as a solvent and includes components in the following concentrations: 30-90 g / L polyvinyl alcohol, 10-30 g / L sodium carboxymethyl cellulose, and 10-30 g / L talc. The effective fungus species in the arbuscular mycorrhizal fungal agent is Heterosporangium heterorhizogenes. The number of propagules of the arbuscular mycorrhizal fungal agent is ≥70 per gram. The seeds are wheat seeds or sorghum seeds. The seed coating agent is applied to cadmium-contaminated soil.

2. The seed coating agent according to claim 1, characterized in that The preparation method of the straw compost comprises the following steps: 1) mixing straw with a fermentation agent, cornmeal, urea, and superphosphate to obtain a mixed material; 2) adjusting the water content of the mixed material to 50-70%, stacking and fermenting to obtain a fermentation product; 3) airing the fermentation product until the moisture content is 10-20% to obtain straw compost.

3. The seed coating agent according to claim 2, characterized in that The fermentation agent is a BFA fermentation agent; the mass ratio of the straw to the fermentation agent is 250-1000:1; the mass ratio of the straw to urea is 60-200:1; the mass ratio of the straw to superphosphate is 6-20:1; and the mass ratio of the straw to cornmeal is 25-100:0.8-1.

2.

4. A method for improving the effect of arbuscular mycorrhizal fungi infecting crops, characterized in that: The steps include: (1) mixing seeds and a seed coating agent to obtain seed pellets; (2) Incubate the pellets for 50-70 minutes; The seed coating agent is the seed coating agent according to any one of claims 1 to 3.

5. The method according to claim 4, characterized in that In step (2), the culture temperature is 25-35°C.

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