A composite microbial agent and application thereof in improving salt-alkali stress resistance of crops

Abstract

The application discloses a kind of composite microbial inoculant and its application in improving the ability of crop to resist saline-alkali stress, the composite microbial inoculant includes the following weight fraction components: bacillus cereus 1-3 parts, bacillus megaterium 1-3 parts, hetero root sporocyst 6-8 parts, gypsum powder 50-70 parts, humic acid 10-30 parts, yeast metabolite 2-3 parts, aluminum sulfate 2-5 parts, citric acid 2-5 parts and adjuvant 0.4-0.6 parts.The application combines bacillus cereus, bacillus megaterium and hetero root sporocyst for the first time, and synergistically exerts its biological function, significantly improves the growth performance of crops under saline-alkali stress, by adding humic acid, yeast metabolite and other components, effectively improves the physical and chemical properties and nutrient status of saline-alkali soil, improves soil fertility, and provides a favorable environment for the growth of microbial inoculant;Significantly improve plant root activity, improve the salt tolerance of crops under saline-alkali stress conditions, improve the growth state of plants, thereby improving the yield of crops.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of agricultural microorganism technology, in particular to a compound microbial agent and its application in improving the salt-alkali stress resistance of crops. BACKGROUND

[0002] Salt-alkali land refers to land where excessive salt and alkali components accumulate on the surface of the soil, causing adverse effects on crop growth, and is a general term for saline land, alkaline land, salinized land and alkalized land. Salt-alkali land usually has the following characteristics: high salt and alkali content in the soil, hard soil texture, alkaline soil, low organic matter content, unbalanced nutrients, and low biological activity. As an important reserve arable land resource in China, the development and improvement of salt-alkali land is of great significance to the expansion of arable land area, the improvement of land use efficiency and the guarantee of food security. The improvement methods of salt-alkali land mainly include physical, chemical, biological and comprehensive management. Among them, biological improvement is one of the most effective methods, whose principle is to absorb, transform and transport soil salt through the growth and metabolism of plants or microorganisms, thereby improving soil quality.

[0003] Bacillus cereus and Bacillus megaterium are common salt-tolerant bacteria, which are widely used as microbial agents in agriculture. Liu Xin et al. (CN114214245A) found a strain of Bacillus cereus SS1, which has salt-alkali tolerance and drought resistance, can significantly alleviate the damage caused by drought stress to plants, can significantly improve the salt and drought tolerance of plants under stress, and can reduce the damage to plants under stress, thereby promoting the growth of plants. Zhang Ruifeng et al. (CN109897806A) found a strain of Bacillus megaterium T4-9, which can improve the salt stress resistance of crops, increase crop yield and reduce soil salt content.

[0004] Arbuscular mycorrhizal fungi are widely distributed in soil ecosystems and can form symbiotic bodies with more than 80% of terrestrial higher plants, i.e. arbuscular mycorrhizal fungi. Through interaction with plant roots, arbuscular mycorrhizal fungi significantly improve the tolerance of plants to salt-alkali stress, promote the absorption of water and nutrients in the soil by plants, and especially the effective use of phosphorus. Although the effects of Bacillus cereus, Bacillus megaterium and arbuscular mycorrhizal fungi have been widely studied and confirmed in individual applications, there is currently no report on the combination of the three for improving the salt-alkali stress resistance of crops. SUMMARY

[0005] In view of the above prior art, the purpose of the present application is to provide a compound microbial agent and its application in improving the salt-alkali stress resistance of crops.

[0006] To achieve the above object, the present application adopts the following technical solutions:

[0007] In a first aspect of the present application, a composite microbial inoculant is provided, comprising the following ingredients in the following weight proportions: Bacillus cereus 1-3 parts, Bacillus megaterium 1-3 parts, Gigaspora multiforme 6-8 parts, humic acid 10-30 parts, gypsum powder 50-70 parts, yeast metabolites 2-3 parts, aluminum sulfate 2-5 parts, citric acid 2-5 parts, and an auxiliary agent 0.4-0.6 parts.

[0008] The present application uses Bacillus cereus, Bacillus megaterium, Gigaspora multiforme, humic acid, yeast metabolites, etc. as raw materials to prepare a microbial inoculant for improving the salt and alkali stress tolerance of plants. The Bacillus cereus in the microbial inoculant can produce extracellular polysaccharide EPS to stimulate the antioxidant activity of plant cells, up-regulate the expression of salt and alkali tolerance genes, and regulate the ion metabolism pathway to improve the salt and alkali tolerance of plants. The Bacillus megaterium can secrete phosphatase and organic acids to decompose and activate organic phosphorus and insoluble inorganic phosphorus, and reduce the soil pH. The Gigaspora multiforme can form mycorrhizal roots with plants to enhance the water and nutrient (especially phosphorus) absorption capacity of plants, thereby significantly improving the growth performance of crops under salt and alkali stress. The humic acid can provide good conditions for the reproduction of microorganisms, fully exert the transformation effect of microorganisms, and complex some metal cations in the soil of salt and alkali land to reduce the salt concentration. The yeast metabolites are rich in various amino acids, biochemical fulvic acid, and other organic substances, which can provide the microorganisms in the microbial inoculant with the nutrients required for activation. The acid conditioners such as gypsum powder, aluminum sulfate, and citric acid can cooperate with the microbial compound powder to condition the soil, so that the alkaline soil can be more durably conditioned, and the long-term and complete improvement of alkaline soil is achieved.

[0009] As a preferred embodiment, the composite microbial inoculant comprises the following ingredients in the following weight proportions:

[0010] Bacillus cereus 2 parts, Bacillus megaterium 2 parts, Gigaspora multiforme 8 parts, humic acid 20 parts, gypsum powder 60 parts, yeast metabolites 3 parts, aluminum sulfate 2 parts, citric acid 2.5 parts, and an auxiliary agent 0.5 parts.

[0011] As a preferred embodiment, the preservation number of the Bacillus cereus is CGMCC No. 33090, and the preservation number of the Gigaspora multiforme is CGMCC No. 41723.

[0012] As a preferred embodiment, the viable count of the Bacillus cereus is ≥100 billion / g, the viable count of the Bacillus megaterium is ≥100 billion / g, and the effective propagule count of the Gigaspora multiforme is ≥70 / g.

[0013] As a preferred embodiment, the auxiliary agent is one or more of Chunzhisu No. 2, Jinggen, and Huangtiaomai.

[0014] In a second aspect of the present application, a preparation method of the composite microbial agent is provided, comprising the following steps: taking each raw material by weight fraction, mixing each raw material uniformly to obtain the composite microbial agent.

[0015] In a third aspect of the present application, the composite microbial agent is applied to improve the salt-alkali stress resistance of crops.

[0016] Preferably, the composite microbial agent improves the salt-alkali stress resistance of crops through at least one of the following (1)-(5):

[0017] (1) improving the germination rate of crops under salt-alkali stress;

[0018] (2) improving the stem diameter of crops under salt-alkali stress;

[0019] (3) improving the plant height of crops under salt-alkali stress;

[0020] (4) improving the chlorophyll SPAD value of crops under salt-alkali stress;

[0021] (5) improving the yield of crops under salt-alkali stress.

[0022] Advantages of the present application:

[0023] 1. The present application first combines Bacillus cereus, Bacillus megaterium and Gigaspora heteromallum to synergistically exert their biological functions. Bacillus cereus up-regulates the expression of salt-alkali tolerance genes and regulates ion metabolism pathways to improve the salt-alkali tolerance of plants by stimulating the antioxidant activity of plant cells. Bacillus megaterium can secrete phosphatase and organic acids to decompose and activate organic phosphorus and insoluble inorganic phosphorus, and reduce the soil pH. Gigaspora heteromallum forms mycorrhizal roots with plants to enhance the plant's ability to absorb water and nutrients (especially phosphorus), thereby significantly improving the growth performance of crops under salt-alkali stress. By adding ingredients such as potassium humate, acid conditioner and yeast metabolites, the present application effectively improves the physical and chemical properties and nutrient status of saline-alkali soil, improves soil fertility, and provides a favorable environment for the growth of microbial agents.

[0024] 2. The present application significantly improves the root activity of plants, improves the salt tolerance of crops under salt-alkali stress conditions, and improves the growth state of plants, thereby improving the yield of crops. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 : Germination rate of corn seeds under salt stress in different treatments;

[0026] Figure 2 : Physiological indicators of corn seeds under salt-alkali field in different treatments. DETAILED DESCRIPTION

[0027] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0028] In order for those skilled in the art to more clearly understand the technical solutions of the present application, the technical solutions of the present application will be described in detail below with specific examples.

[0029] The test materials used in the embodiments of the present application are all conventional test materials in the art and can be purchased through commercial channels.

[0030] The potassium humate used in the present application is purchased from Shandong Nongda Fertilizer Technology Co., Ltd.

[0031] The yeast metabolite used in the present application is purchased from Angel Yeast (Binzhou) Co., Ltd.

[0032] The purchase sources of the adjuvants used in the present application are as follows:

[0033] Chunzhisu No. 2 is purchased from Henan Zhongwei Chunyu Plant Nutrition Co., Ltd.

[0034] Jingen is purchased from Henan Xuyang Agricultural Technology Co., Ltd.

[0035] Huangtiemai is purchased from Henan Enno Agricultural Technology Co., Ltd.

[0036] The Bacillus cereus used in the present application is named SNF7, and the preservation information is as follows:

[0037] Strain name: Bacillus cereus SNF7

[0038] Latin name: Bacillus cereus

[0039] Preservation agency: China General Microbiological Culture Collection Center

[0040] Abbreviation of preservation agency: CGMCC

[0041] Address: No. 3, Yihao Yard, Beichen West Road, Chaoyang District, Beijing

[0042] Preservation date: December 17, 2024

[0043] Preservation number: CGMCC No. 33090.

[0044] The Bacillus cereus in the present application is added in the form of bacterial powder, and the preparation method of the Bacillus cereus is as follows:

[0045] The activated Bacillus cereus SNF7 seed liquid is inoculated into LB liquid culture medium at an inoculation amount of 10% (volume fraction), and is cultured at 35 DEG C and 180 rpm for 36 hours, and then the culture liquid is centrifuged (4,000 rpm, 10 minutes), the supernatant is discarded, the precipitated bacteria are collected, and dried to obtain Bacillus cereus powder, and the viable count of the Bacillus cereus powder is 10 billion / g.

[0046] The Rhizophagus irregularis used in the application is named NDFY-Ri1, and the preservation information is as follows:

[0047] Strain name: Rhizophagus irregularis NDFY-Ri1

[0048] Latin name: Rhizophagus irregularis

[0049] Preservation agency: China General Microbiological Culture Collection Center

[0050] Abbreviation of preservation agency: CGMCC

[0051] Address: No. 3, Beichen West Road, Beijing City

[0052] Preservation date: December 17, 2024

[0053] Preservation number: CGMCC No. 41723.

[0054] The Rhizophagus irregularis in the application is added in the form of powder, and the preparation method of the Rhizophagus irregularis powder is as follows:

[0055] The whole culture of the single-spore cultured Rhizophagus irregularis NDFY-Ri1 is inoculated into the sand culture medium at an inoculation amount of 1% (mass fraction), 8 corn seeds are sowed according to the size of the pot, and the culture medium and all the roots are collected after the aboveground part of the corn is cut off and cultured at 25 DEG C for 3 months, and then the culture medium and all the roots are crushed, dried and passed through a 1mm sieve to obtain the Rhizophagus irregularis powder, and the propagule number of the Rhizophagus irregularis is greater than or equal to 70 per gram.

[0056] The Bacillus megaterium used in the application is purchased from Shandong Nongda Fertilizer Technology Co., Ltd., and the commodity name is "Yuanjun Tai - super concentrated agricultural microbial agent Bacillus megaterium", and the bacterial content is 100 billion / g.

[0057] Example 1: Preparation of a composite microbial agent

[0058] (1) Raw material composition (weight parts):

[0059] Bacillus cereus 2 parts, Bacillus megaterium 2 parts, Rhizomucor variabilis 8 parts, humic acid 20 parts, gypsum powder 60 parts, yeast metabolite 3 parts, aluminum sulfate 2 parts, citric acid 2.5 parts and Chunzhisu No. 2 0.5 parts;

[0060] (2) Preparation method:

[0061] The above raw materials are weighed by weight fraction, and each raw material is uniformly mixed to obtain a compound microbial agent.

[0062] Example 2:

[0063] (1) Raw material composition (weight fraction):

[0064] Bacillus cereus 1 part, Bacillus megaterium 1 part, Rhizomucor variabilis 6 parts, humic acid 10 parts, gypsum powder 60 parts, yeast metabolite 2 parts, aluminum sulfate 2 parts, citric acid 2 parts and Jinggen 0.4 parts.

[0065] The preparation method is the same as that of Example 1, and a compound microbial agent is prepared.

[0066] Example 3:

[0067] (1) Raw material composition (weight fraction):

[0068] Bacillus cereus 3 parts, Bacillus megaterium 3 parts, Rhizomucor variabilis 8 parts, humic acid 3 parts, gypsum powder 70 parts, yeast metabolite 3 parts, aluminum sulfate 5 parts, citric acid 5 parts and Huangteamine 0.6 parts;

[0069] The preparation method is the same as that of Example 1, and a compound microbial agent is prepared.

[0070] Comparative Example 1:

[0071] Raw material composition (weight fraction):

[0072] Humic acid 20 parts, gypsum powder 60 parts, yeast metabolite 3 parts, aluminum sulfate 2 parts, citric acid 2.5 parts and Chunzhisu No. 2 0.5 parts;

[0073] (2) Preparation method:

[0074] The above raw materials are weighed by weight fraction, and each raw material is uniformly mixed to obtain a compound microbial agent.

[0075] Comparative Example 2:

[0076] Raw material composition (weight fraction):

[0077] Bacillus cereus 2 parts, humic acid 20 parts, gypsum powder 60 parts, yeast metabolite 3 parts, aluminum sulfate 2 parts, citric acid 2.5 parts and Chunzhisu No. 2 0.5 parts;

[0078] (2) Preparation method:

[0079] The raw materials are weighed by parts by weight, and each raw material is uniformly mixed to obtain a compound microbial agent.

[0080] Comparative Example 3:

[0081] Raw material composition (parts by weight):

[0082] Bacillus megaterium 2 parts, humic acid 20 parts, gypsum powder 60 parts, yeast metabolites 3 parts, aluminum sulfate 2 parts, citric acid 2.5 parts, and Chunzisu No. 2 0.5 parts;

[0083] (2) Preparation method:

[0084] The raw materials are weighed by parts by weight, and each raw material is uniformly mixed to obtain a compound microbial agent.

[0085] Comparative Example 4:

[0086] Raw material composition (parts by weight):

[0087] Heterocephalomyces 8 parts, humic acid 20 parts, gypsum powder 60 parts, yeast metabolites 3 parts, aluminum sulfate 2 parts, citric acid 2.5 parts, and Chunzisu No. 2 0.5 parts;

[0088] (2) Preparation method:

[0089] The raw materials are weighed by parts by weight, and each raw material is uniformly mixed to obtain a compound microbial agent.

[0090] Test Example 1: Effect of Compound Microbial Agent on Germination of Corn under Salt Stress

[0091] 1. Test method:

[0092] Select corn seeds that are not damaged, full of particles, and uniform in size for use. Fill 1 kg of nutrient soil as a substrate into the germination box, and drop different concentrations of NaCl solution into the germination box to make the salt content of the substrate reach 0.6%, 1.2%, 1.8%, 2.4%, and 3%, respectively, with distilled water as a control. Then, seeds, compound microbial agent prepared in Example 1, and fertilizers prepared in Comparative Examples 1-3 are sown at the same time, 20 seeds per box, repeated 4 times.

[0093] The test is divided into 6 treatment groups:

[0094] Treatment 1: Apply the compound microbial agent prepared in Example 1, with a treatment concentration of 40 kg / acre;

[0095] Treatment 2: Apply the compound microbial agent prepared in Example 2, with a treatment concentration of 40 kg / acre;

[0096] Treatment 3: The composite microbial inoculant prepared in Example 3 was applied at a concentration of 40 kg / acre.

[0097] Treatment 4: The fertilizer prepared in Comparative Example 1 was applied at a concentration of 40 kg / acre.

[0098] Treatment 5: The fertilizer prepared in Comparative Example 2 was applied at a concentration of 40 kg / acre.

[0099] Treatment 6: The fertilizer prepared in Comparative Example 3 was applied at a concentration of 40 kg / acre.

[0100] Treatment 7: The fertilizer prepared in Comparative Example 4 was applied at a concentration of 40 kg / acre.

[0101] Control: No fertilizer was applied.

[0102] The germination boxes were placed in a light incubation room and water was added regularly to maintain the concentration of the salt solution.

[0103] Detection method: The number of germinated seeds was counted daily. After germination began, if the number of germinated seeds did not increase for 3 consecutive days, it was considered that germination had ended.

[0104] The germination rate of the seeds was determined according to the following formula.

[0105] Germination rate (%) = (total number of normal germinated seeds / total number of test seeds) x 100%.

[0106] 2. Test results:

[0107] Figure 1 It was shown that as the salt concentration increased, the germination rate of all groups decreased. The germination rate of CK (control group) decreased relatively greatly, and when the salt concentration reached 3%, the germination rate decreased to about 79%. The germination rates of Examples 1, 2, and 3 decreased relatively gently, and when the salt concentration was 3%, the germination rate could still be maintained at about 93%, indicating that the treatment methods in these examples could alleviate the negative effects of salt concentration on germination rate to some extent and improve the germination ability of seeds in saline-alkaline environments. The germination rates of Comparative Examples 1, 2, 3, and 4 decreased at a rate between CK and the examples, indicating that the synergistic effect of Bacillus cereus, Bacillus megaterium, and Phytonyces heteromorphus in the examples was better than that of a single strain.

[0108] Test Example 2: Field test of the effect of composite microbial inoculant on the growth of corn under salt stress

[0109] Test treatment: A saline-alkaline land plot in Dui County, Binzhou City, Shandong Province was selected for the field test. The soil physical and chemical properties are shown in Table 1.

[0110] Table 1 Basic physical and chemical properties of the test site soil

[0111]

[0112] The test treatments are as follows:

[0113] T1: conventional fertilization (CK);

[0114] T2: conventional fertilization + compound microbial agent (40 kg / acre) treatment, the compound microbial agent is part of the base fertilizer, and is applied together with other base fertilizers;

[0115] T3: conventional fertilization + fertilizer prepared by Comparative Example 1 (40 kg / acre) treatment, the fertilizer prepared by Comparative Example 1 is part of the base fertilizer, and is applied together with other base fertilizers;

[0116] T4: conventional fertilization + fertilizer prepared by Comparative Example 2 (40 kg / acre) treatment, the fertilizer prepared by Comparative Example 2 is part of the base fertilizer, and is applied together with other base fertilizers;

[0117] T5: conventional fertilization + fertilizer prepared by Comparative Example 3 (40 kg / acre) treatment, the fertilizer prepared by Comparative Example 3 is part of the base fertilizer, and is applied together with other base fertilizers.

[0118] T6: conventional fertilization + fertilizer prepared by Comparative Example 4 (40 kg / acre) treatment, the fertilizer prepared by Comparative Example 4 is part of the base fertilizer, and is applied together with other base fertilizers.

[0119] Each treatment is set up with 3 replicates, arranged in random blocks, and the corn after sowing grows in the natural environment, and the other field management except the base fertilizer is consistent.

[0120] Detection method:

[0121] In early September 2024, the corn was in the big bell stage, and the corn row spacing and plant spacing were measured, 12 corn plants were randomly taken from each treatment, and the plant height, stem diameter and chlorophyll content were measured on the spot.

[0122] In October 2024, the corn was in the harvest stage, 3 sample points were randomly taken from each plot, 3m area was measured with a tape measure in each sample point, and the number of corn plants and the number of corn ears on both sides of the tape measure were counted; 40 ears of corn were continuously collected in each statistical sample section to measure the quality, and the yield was calculated.

[0123] Table 2 Theoretical yield of corn field test

[0124]

[0125] Test results: Figure 2It is shown that the application of the complex microbial agent and the single microbial agent can promote the growth of corn under saline-alkali conditions, but the complex microbial agent has the highest growth-promoting effect. Specifically, the plant height of T2 is increased by 27.00%, 14.54%, 4.6%, 5.38% and 4.65% compared with the control, the comparative example 1, the comparative example 2, the comparative example 3 and the comparative example 4, respectively; the stem diameter is increased by 21.64%, 5.75%, 2.36%, 5.07% and 2.04% compared with the control, the comparative example 1, the comparative example 2, the comparative example 3 and the comparative example 4, respectively; and the chlorophyll SPAD value is increased by 17.94%, 13.99%, 6.76%, 7.33 and 1.35% compared with the control, the comparative example 1, the comparative example 2, the comparative example 3 and the comparative example 4, respectively. Table 2 shows that the complex microbial agent significantly improves the yield of corn under saline-alkali conditions.

[0126] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. The present application can have various modifications and changes for those skilled in the art. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A complex microbial inoculant, characterized in that, The composite microbial agent comprises the following ingredients in parts by weight: Bacillus cereus 1-3 parts, Bacillus megaterium 1-3 parts, Absidia ramose 6-8 parts, humic acid 10-30 parts, gypsum powder 50-70 parts, yeast metabolites 2-3 parts, aluminum sulfate 2-5 parts, citric acid 2-5 parts, and an auxiliary agent 0.4-0.6 parts; the auxiliary agent is one or more of Chunzhisu No. 2, Jinggen, and Huangteiammonium; the preservation number of Bacillus cereus is CGMCC No. 33090, and the preservation number of Absidia ramose is CGMCC No. 41723.

2. The complex microbial agent according to claim 1, characterized by, The composite microbial agent comprises the following ingredients in parts by weight: Bacillus cereus 2 parts, Bacillus megaterium 2 parts, Absidia ramose 8 parts, humic acid 20 parts, gypsum powder 60 parts, yeast metabolites 3 parts, aluminum sulfate 2 parts, citric acid 2.5 parts, and an auxiliary agent 0.5 parts.

3. The composite microbial agent of claim 1, wherein the viable cell count of Bacillus cereus is ≥100 billion per gram, the viable cell count of Bacillus megaterium is ≥100 billion per gram, and the effective propagule count of Absidia ramose is ≥70 per gram.

4. Use of the composite microbial agent of any one of claims 1-3 to improve the salt-alkali stress resistance of crops.

5. Use according to claim 4, characterized in that, The composite microbial agent improves the salt-alkali stress resistance of crops by at least one of the following (1)-(5): (1) improving the germination rate of crops under salt-alkali stress; (2) improving the plant height of crops under salt-alkali stress; (3) improving the stem thickness of crops under salt-alkali stress; (4) improving the chlorophyll SPAD value of crops under salt-alkali stress; (5) improving the yield of crops under salt-alkali stress.

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