Application of Bacillus cereus and Bacillus brevis in promoting growth of salt-alkali tolerant plants and improving saline-alkali soil

Abstract

The present invention belongs to the technical field of microbial soil improvement, and specifically relates to the application of Bacillus cereus and Bacillus pumilus in promoting plant growth and improving saline-alkali soil. The present invention provides the application of Bacillus cereus and Bacillus pumilus in promoting the growth of salt-tolerant plants. Bacillus cereus and Bacillus pumilus of the present invention promote each other and have a synergistic effect, and promote the growth of salt-tolerant plants by producing NH3, dissolving inorganic phosphorus, producing IAA, producing siderophores and producing protease. Results of the examples: The compound microbial fertilizer prepared from Bacillus cereus and Bacillus pumilus can effectively improve the emergence rate, leaf area and plant height of sunflowers in saline-alkali soil; improve the emergence rate of upland rice and promote growth.

Description

Technical Field

[0001] The invention belongs to the technical field of microbial soil improvement, and particularly relates to application of Bacillus cereus and Bacillus pumilus in promoting the growth of salt-alkali tolerant plants and improving saline-alkali soil. Background Art

[0002] In the context of an ever-increasing population, the effective use of limited land resources is crucial for global development. However, saline-alkali land is widely distributed in the current land resources, and saline-alkali land is still an important reserve land resource for food security. In view of the increasing degree of soil salinization, the increasing shortage of arable land resources and the increasing demand for food in my country, improving saline-alkali land and promoting the growth of plants in saline-alkali land are important means to ensure the sustainable development of agriculture. At present, the improvement of saline-alkali land is the basis of agricultural utilization. The improved saline-alkali land resources have a variety of utilization methods, such as the development of grass and grassland animal husbandry, the planting of cash crops and Chinese medicinal materials. At present, the methods for improving saline-alkali soil include chemical method, physical method and biological method. Although physical and chemical improvement are effective, there may be problems such as large engineering workload, easy anti-salinity and high cost. Biological methods, including planting salt-alkali tolerant plants and microorganisms to improve saline-alkali soil, have become the most popular research method.

[0003] The key to growing salt-alkali tolerant plants is to promote their growth. Salt-alkali stress is a common factor affecting plant growth, which will inhibit the entire growth cycle of plants to varying degrees. Composite microbial strains are more effective and stable than single strains, and can secrete different active substances. Therefore, it is necessary to strengthen the research on the growth-promoting effect of composite microbial strains on salt-alkali tolerant plants. Summary of the invention

[0004] The purpose of the present invention is to provide an application of Bacillus cereus and Bacillus pumilus in promoting the growth of salt-alkali tolerant plants, so as to promote the growth of salt-alkali plants.

[0005] The invention provides application of Bacillus cereus and Bacillus pumilus in promoting the growth of salt-alkali tolerant plants.

[0006] Preferably, the plants include salt-alkali tolerant plants.

[0007] Preferably, the salt-alkali tolerant plants include upland rice or oil sunflower; and the plant growth promotion includes increasing any one or more of the seedling emergence rate, plant height, leaf area and yield.

[0008] The invention provides application of Bacillus cereus and Bacillus pumilus in improving saline-alkali soil.

[0009] Preferably, the improved saline-alkali soil includes any one or more of 1) to 4);

[0010] 1) Increase the water holding capacity and water supply capacity of saline-alkali soil;

[0011] 2) Reduce the salt content of saline-alkali soil;

[0012] 3) Increase the content of one or more nutrients including total nitrogen, available phosphorus, available potassium, ammonia nitrogen and nitrate nitrogen in saline-alkali soil;

[0013] 4) Increase the content of water-stable aggregates in soil.

[0014] Preferably, the growth-promoting properties of Bacillus cereus and Bacillus pumilus include production of NH 3 , dissolving inorganic phosphorus, producing IAA, producing siderophore and producing protease, or one or more of the following.

[0015] Preferably, the Bacillus cereus includes Bacillus cereus G2, and the Bacillus pumilus includes Bacillus pumilus G5;

[0016] The deposit number of the Bacillus cereus G2 is CGMCC No. 16671; the deposit number of the Bacillus pumilus G5 is CGMCC No. 16879.

[0017] Preferably, the application of the Bacillus cereus and Bacillus pumilus includes preparing them into composite seed liquid or composite microbial fertilizer and then applying them to plants or soil;

[0018] The preparation of the composite seed solution includes: mixing Bacillus cereus seed solution and Bacillus pumilus seed solution; the number of live bacteria of Bacillus cereus in the composite seed solution is 1.5×10 12 cfu / mL~1.8×10 12 cfu / mL; the number of viable Bacillus pumilus in the composite seed solution is 4×10 11 cfu / mL~5.5×10 11 cfu / mL;

[0019] The preparation of the composite microbial fertilizer comprises: fermenting the composite seed liquid to obtain the composite microbial fertilizer; the culture medium used in the fermentation comprises 20g maltose, 16.8g yeast extract powder, 4.0g Na 2 HPO 4 , 2.0gNaH 2 PO 4 、0.5gMgSO 4 , 0.2gCaCl 2 and 1L of distilled water.

[0020] Preferably, the total number of effective living bacteria of Bacillus cereus and Bacillus pumilus in the composite microbial fertilizer is 50×10 12 cfu / mL~60×10 12 cfu / mL; when the compound microbial fertilizer is used in a planting pot, the mass ratio of the compound microbial fertilizer to the dry weight of saline-alkali soil is (1-5mL):1kg, and when the compound microbial fertilizer is used in the field, the application amount of the compound microbial fertilizer is 1-2L / mu.

[0021] The invention provides a composite biofertilizer for improving saline-alkali soil. The composite biofertilizer comprises Bacillus cereus G2 and Bacillus pumilus G5. The preservation number of Bacillus cereus G2 is CGMCC No.16671; the preservation number of Bacillus pumilus G5 is CGMCC No.16879.

[0022] Beneficial effects of the present invention: The present invention provides the use of Bacillus cereus and Bacillus pumilus in promoting the growth of salt-alkali tolerant plants. The Bacillus cereus and Bacillus pumilus of the present invention promote each other and have a synergistic effect. 3 , dissolving inorganic phosphorus, producing IAA, producing siderophore and producing protease, and promoting the growth of salt-alkali tolerant plants. Example Results: The composite microbial fertilizer prepared by Bacillus cereus and Bacillus pumilus can effectively improve the emergence rate, leaf area and plant height of oil sunflower in saline-alkali soil, and improve the emergence rate of upland rice.

[0023] Biological deposit information

[0024] Bacillus cereus G2 was deposited in the General Microbiology Center of China Microorganism Culture Collection (CGMCC) on October 31, 2018. The deposit address is No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences, and the deposit number is CGMCC No. 16671.

[0025] Bacillus pumilus G5 was deposited in the General Microbiology Center (CGMCC) of China Microorganism Culture Collection Administration on December 6, 2018. The deposit address is No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences, and the deposit number is CGMCC No. 16879. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required to be used in the embodiments are briefly introduced below.

[0027] Figure 1The growth-promoting properties of the composite seed solution at different salt levels in Example 2, where a represents the production of NH 3 activity, b represents the ability to produce IAA, c represents the ability to produce siderophores, d represents the phosphate solubilization effect, and e represents the activity of producing protease;

[0028] Figure 2 The early growth of licorice seedlings in different treatment groups in Example 2;

[0029] Figure 3 It is a display diagram of the overall state of the straight-cylinder pot soil column experiment after watering in Examples 3 to 7 and Comparative Example 1;

[0030] Figure 4 It is a graph showing the change of soil moisture characteristic curves of Examples 3 to 7 and Comparative Example 1;

[0031] Figure 5 This is the morphological diagram of sunflower in each treatment group of Application Example 1. Figure 5 The left side shows the morphology of sunflowers in each treatment group at the budding stage (July 10). Figure 5 On the right are graphs of soil salinity and nutrient content monitored in each treatment group;

[0032] Figure 6 For application example 2 F 2 Treatment group, F 1 Seedling emergence of upland rice in the treatment groups;

[0033] Figure 7 This is the emergence of upland rice in the CK treatment group of Application Example 2. DETAILED DESCRIPTION

[0034] The invention provides application of Bacillus cereus and Bacillus pumilus in promoting the growth of salt-alkali tolerant plants.

[0035] The present invention provides the use of Bacillus cereus and Bacillus pumilus in promoting the growth of salt-alkali tolerant plants, preferably the use of a composite seed liquid or a composite microbial fertilizer prepared by Bacillus cereus and Bacillus pumilus in promoting the growth of salt-alkali tolerant plants, and more preferably the use of a composite microbial fertilizer prepared by Bacillus cereus and Bacillus pumilus in promoting the growth of salt-alkali tolerant plants.

[0036] The present invention provides the use of Bacillus cereus and Bacillus pumilus in improving saline-alkali soil, preferably the use of composite seed solution or composite microbial fertilizer prepared by Bacillus cereus and Bacillus pumilus in improving saline-alkali soil, more preferably the use of composite microbial fertilizer prepared by Bacillus cereus and Bacillus pumilus in improving saline-alkali soil. The improved saline-alkali soil of the present invention includes one or more of 1) to 4);

[0037] 1) Increase the water holding capacity and water supply capacity of saline-alkali soil;

[0038] 2) Reduce the salt content of saline-alkali soil;

[0039] 3) Increase the content of one or more nutrients including total nitrogen, available phosphorus, available potassium, ammonia nitrogen and nitrate nitrogen in saline-alkali soil;

[0040] 4) Increase the content of water-stable aggregates in saline-alkali soil.

[0041] The composite microbial fertilizer of the present invention improves saline-alkali soil by more preferably increasing soil water holding capacity and water supply capacity, reducing soil salt content, increasing the content of total nitrogen, available phosphorus, available potassium, ammonia nitrogen and nitrate nitrogen in the soil, and increasing the content of water-stable aggregates in the soil.

[0042] The Bacillus cereus of the present invention preferably includes Bacillus cereus G2, and the deposit number of the Bacillus cereus G2 is CGMCC No.16671.

[0043] The Bacillus pumilus of the present invention preferably includes Bacillus pumilus G5, and the deposit number of the Bacillus pumilus G5 is CGMCC No.16879.

[0044] The Bacillus cereus and Bacillus pumilus of the present invention have a synergistic effect. The growth-promoting properties of the Bacillus cereus and Bacillus pumilus of the present invention are preferably achieved by producing NH 3 , dissolving inorganic phosphorus, producing IAA, producing siderophore and producing protease, more preferably producing NH 3 , dissolve inorganic phosphorus, produce IAA, produce siderophore and produce protease.

[0045] The application mode of the Bacillus cereus and Bacillus pumilus of the present invention is preferably to prepare a composite seed liquid or a composite microbial fertilizer and then apply it to plants or soil. The preparation method of the composite seed liquid of the present invention preferably includes mixing the Bacillus cereus seed liquid and the Bacillus pumilus seed liquid; the number of viable bacteria of Bacillus cereus in the composite seed liquid is preferably 1.5×10 12 cfu / mL~1.8×10 12 cfu / mL, more preferably 1.65×10 12 cfu / mL; the number of viable Bacillus pumilus in the composite seed solution is preferably 4×10 11 cfu / mL~5.5×10 11 cfu / mL, more preferably 4.95×10 11cfu / mL. The preparation of the Bacillus cereus seed solution of the present invention preferably includes activating Bacillus cereus and inoculating it into NA liquid culture medium for seed culture to obtain Bacillus cereus seed solution. The activation of Bacillus cereus of the present invention preferably involves applying Bacillus cereus to NA solid culture medium for activation culture to obtain a single colony of Bacillus cereus. The temperature of the activation culture of the present invention is preferably 28-35°C, more preferably 30°C; the time of the activation culture is preferably 46-50h, more preferably 48h; the rotation speed of the seed culture is preferably 160-200rpm, more preferably 180rpm. The composition of the NA solid culture medium of the present invention preferably includes 9-11g of peptone, 2-4g of beef extract, 4-6g of sodium chloride, 14-17g of agar and 1000mL of distilled water, more preferably 10g of peptone, 3g of beef extract, 5g of sodium chloride, 15g of agar and 1000mL of distilled water.

[0046] Obtain a single colony of Bacillus cereus. The present invention preferably inoculates a single colony of Bacillus cereus into a NA liquid culture medium for seed culture to obtain a Bacillus cereus seed solution. The temperature of the seed culture of the present invention is preferably 28-35°C, more preferably 30°C; the time of the seed culture is preferably 20-26h, more preferably 24h; the rotation speed of the seed culture is preferably 160-200rpm, more preferably 180rpm. The composition of the NA liquid culture medium of the present invention preferably includes 9-11g of peptone, 2-4g of beef extract, 4-6g of sodium chloride and 1000mL of distilled water, more preferably 10g of peptone, 3g of beef extract, 5g of sodium chloride and 1000mL of distilled water.

[0047] The preparation of the Bacillus pumilus seed solution of the present invention preferably includes activating Bacillus pumilus and inoculating it into NA liquid culture medium for seed culture to obtain Bacillus pumilus seed solution. The activation of Bacillus pumilus of the present invention preferably involves applying Bacillus pumilus to NA solid culture medium for activation culture to obtain a single colony of Bacillus pumilus. The temperature of the activation culture of the present invention is preferably 28-35°C, more preferably 30°C; the time of the activation culture is preferably 46-50h, more preferably 48h; the rotation speed of the seed culture is preferably 160-200rpm, more preferably 180rpm. The composition of the NA solid culture medium of the present invention preferably includes 9-11g of peptone, 2-4g of beef extract, 4-6g of sodium chloride, 14-17g of agar and 1000mL of distilled water, more preferably 10g of peptone, 3g of beef extract, 5g of sodium chloride, 15g of agar and 1000mL of distilled water.

[0048] Obtain a single colony of Bacillus pumilus. The present invention preferably inoculates a single colony of Bacillus pumilus into a NA liquid culture medium for seed culture to obtain a Bacillus pumilus seed solution. The temperature of the seed culture of the present invention is preferably 28-35°C, more preferably 30°C; the time of the seed culture is preferably 20-26h, more preferably 24h; the rotation speed of the seed culture is preferably 160-200rpm, more preferably 180rpm. The composition of the NA liquid culture medium of the present invention preferably includes 9-11g of peptone, 2-4g of beef extract, 4-6g of sodium chloride and 1000mL of distilled water, more preferably 10g of peptone, 3g of beef extract, 5g of sodium chloride and 1000mL of distilled water.

[0049] The culture medium used for seed culture of Bacillus pumilus and Bacillus cereus of the present invention is preferably a NA solid culture medium. The composition of the NA liquid culture medium of the present invention preferably includes 9-11g of peptone, 2-4g of beef extract, 4-6g of sodium chloride and 1000mL of distilled water, more preferably 10g of peptone, 3g of beef extract, 5g of sodium chloride and 1000mL of distilled water.

[0050] The Bacillus cereus seed solution and the Bacillus pumilus seed solution are obtained. In the present invention, the Bacillus cereus seed solution and the Bacillus pumilus seed solution are preferably mixed to obtain a composite seed solution. The volume ratio of the mixed Bacillus cereus seed solution and the Bacillus pumilus seed solution is preferably (1-2): (1-2), more preferably 1:1.

[0051] After obtaining the composite seed liquid, the present invention ferments the composite seed liquid to obtain a composite microbial fertilizer, and more preferably, the composite seed liquid is inoculated into a culture medium for fermentation to obtain the composite microbial fertilizer.

[0052] The preparation method of the composite seed solution of the present invention has been described above and will not be repeated here. The inoculation amount of the composite seed solution of the present invention is preferably 1.5-3% of the volume of the specific culture medium, more preferably 2%.

[0053] The temperature of the composite seed liquid fermentation of the present invention is preferably 25-30°C, more preferably 26-28°C, and more preferably 28°C; the time of the composite seed liquid fermentation is preferably 24-36h, preferably 24-30h, and more preferably 24h; the speed of the composite seed liquid fermentation is preferably 160-200r / min, and more preferably 180r / min. The composition of the culture medium used in the fermentation of the present invention preferably includes 20g maltose, 16.8g yeast extract powder, Na 2 HPO 4 4.0 g, NaH 2 PO 4 2.0 g, MgSO 4 0.5 g, CaCl 20.2g and 1L of distilled water.

[0054] After the fermentation is completed, the total number of effective living bacteria of Bacillus cereus and Bacillus pumilus in the composite microbial fertilizer preferably obtained by the present invention is preferably (50-60)×10 12 cfu / mL, more preferably 56.55×10 12 The composite microbial fertilizer (also called composite biological fertilizer) of the present invention has strong stability, can improve the water retention performance of saline-alkali soil, increase the water holding and water supply capacity of saline-alkali soil; reduce the salt content in saline-alkali soil; can increase the nutrients of saline-alkali soil including nitrogen, phosphorus, ammonia nitrogen and nitrate nitrogen; can effectively increase the content of water-stable aggregates in saline-alkali soil; the composite biological fertilizer of the present invention can also effectively promote the growth of crops in saline-alkali soil and increase yield.

[0055] The present invention provides a composite biofertilizer for improving saline-alkali soil, the composite biofertilizer comprising Bacillus cereus G2 and Bacillus pumilus G5, the Bacillus cereus G2 is deposited as CGMCC No. 16671; the Bacillus pumilus G5 is deposited as CGMCC No. 16879. The composite microbial fertilizer of the present invention is preferably a composite seed liquid inoculated into a culture medium for fermentation to obtain a composite microbial fertilizer. The preparation parameters of the composite seed liquid of the present invention and the parameters for fermenting the composite seed liquid have been discussed above and will not be repeated here.

[0056] The present invention preferably applies the composite microbial fertilizer or composite seed solution with water into saline-alkali soil to promote the growth of salt-alkali tolerant plants and / or improve saline-alkali soil. The volume ratio of the composite microbial fertilizer and water of the present invention is preferably 1: (1000-2000), more preferably 1: (1700-1800). The composite microbial fertilizer of the present invention is applied into saline-alkali soil with water to make it easier for the composite microorganisms to penetrate the soil and improve the application effect of the composite microbial fertilizer.

[0057] The salt-alkali tolerant plants of the present invention preferably include upland rice or oil sunflower, and the plant growth promotion of the present invention includes improving one or more of the emergence rate, plant height, leaf area and yield, and more preferably improving the emergence rate, plant height, leaf area and yield at the same time. The composite microbial fertilizer prepared by Bacillus cereus and Bacillus pumilus of the present invention can effectively promote the emergence rate, leaf area and plant height of oil sunflower in saline-alkali soil, and improve the emergence rate of upland rice, and the emergence rate of upland rice is increased by 79.99% to 99.96%.

[0058] When the effective number of living bacteria of the composite microbial fertilizer is (50-60)×10 12cfu / mL, the application amount of the composite microbial fertilizer of the present invention is preferably a mass ratio of the composite microbial fertilizer to the dry weight of the improved saline-alkali soil of (1-5mL):1kg, more preferably (4mL):1kg. The saline-alkali soil of the present invention preferably includes mild saline-alkali soil; the salt content of the mild saline-alkali soil is preferably 3.5-6.0g / kg, more preferably 4.04g / kg, and the pH value of the mild saline-alkali soil is preferably 7.8-8.6, more preferably 8.2. The improved saline-alkali soil of the present invention is obtained by air drying to obtain the improved saline-alkali soil dry weight value.

[0059] When the effective number of living bacteria of the composite microbial fertilizer is (50-60)×10 12 cfu / mL, the application amount of the composite microbial fertilizer of the present invention when applied in the field is preferably 1-2 L / mu, more preferably 1.5 L / mu.

[0060] Although there are many types of bacterial fertilizers and microbial agents sold in the domestic and foreign markets, there are few efficient bacterial fertilizers and microbial agents for improving saline-alkali land, and microbial products suitable for the restoration of saline-alkali land in different regions are even more scarce. The composite seed liquid and composite microbial fertilizer prepared by the present invention using Bacillus cereus G2 and Bacillus pumilus G5 have salt-alkali resistance, can grow and reproduce in saline-alkali soil, secrete growth-promoting substances, and promote the growth of salt-alkali tolerant plants.

[0061] The composite microbial fertilizer of the present invention can improve the water retention performance of saline-alkali soil, increase the soil water content, and the maximum growth rate can reach 25.32%; it can increase the water holding and water supply capacity of the soil, and the water capacity of the treated soil at different suction forces is improved; it can significantly reduce the soil salinity, and the maximum reduction can be 57%; it can improve the nutrients of the soil, and the nitrogen, phosphorus, ammonia nitrogen and nitrate nitrogen in the soil after treatment are increased by 72.32%, 68.64%, 73.49% and 79.27% ​​respectively; it can effectively increase the content of soil water-stable aggregates, and the content of water-stable aggregates after treatment can be increased by 82% compared with the control group. The composite microbial fertilizer of the present invention can effectively improve the emergence rate and seedling protection rate of plants on saline-alkali soil, promote growth, and increase crop yield.

[0062] In order to further illustrate the present invention, the technical solution provided by the present invention is described in detail below in conjunction with the accompanying drawings and embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0063] Example 1 Preparation of composite microbial seed solution and composite microbial fertilizer

[0064] Culture medium: NA solid culture medium consists of 10 g peptone, 3 g beef extract, 5 g sodium chloride, 15 g agar, and 1000 mL distilled water, pH = 7.3 ± 0.1;

[0065] NA liquid medium consists of 10 g of peptone, 3 g of beef extract, 5 g of sodium chloride, 1000 mL of distilled water, pH = 7.3 ± 0.1;

[0066] The specific culture medium consists of 20 g maltose, 16.8 g yeast extract powder, Na 2 HPO 4 4.0 g, NaH 2 PO 4 2.0 g, MgSO 4 0.5 g, CaCl 2 0.2g and 1L of distilled water;

[0067] (1) Activation of bacterial strains: Bacillus cereus G2 (CGMCC No. 16671) was activated on NA solid medium and cultured in a 30°C incubator for 48 h to obtain a single G2 colony for later use;

[0068] Bacillus pumilus G5 (CGMCC No. 16879) was activated on NA solid medium and cultured in a 30°C incubator for 48 hours to obtain a single colony of G5 for later use.

[0069] (2) Preparation of seed solution: Pick a single G2 colony after activation and inoculate it into NA liquid culture medium. After culturing in a constant temperature shaker at 28°C and 180 rpm for 24 h, obtain G2 seed solution for later use;

[0070] Pick up the activated G5 single colony, inoculate it into NA liquid culture medium, and culture it in a constant temperature shaker at a temperature of 28°C and a rotation speed of 180 rpm for 24 hours to obtain G5 seed solution for use.

[0071] (3) Preparation of composite seed solution: G2 seed solution and G5 seed solution were mixed at a volume ratio of 1:1 to obtain a composite seed solution; the number of viable Bacillus cereus in the composite seed solution was 1.65×10 12 cfu / mL; the number of viable Bacillus pumilus in the composite seed solution was 4.95×10 11 cfu / mL.

[0072] (4) Preparation of composite microbial fertilizer: The composite seed liquid was inoculated into a specific culture medium for composite fermentation. The initial pH value of the specific culture medium was 5, and the volume of the specific culture medium was 100 mL / 250 mL. The inoculation amount of the composite seed liquid was 2% of the volume of the specific culture medium. The composite fermentation temperature was 30°C, the composite fermentation speed was 180 r / min, and the composite fermentation time was 24 h, thereby obtaining a composite microbial fertilizer. The total number of effective live bacteria of Bacillus cereus and Bacillus pumilus in the composite microbial fertilizer was 56.55 × 10 12 cfu / mL.

[0073] Example 2 Salt tolerance of composite seed solution and its growth-promoting properties under salt stress environment

[0074] 1. Determination of salt tolerance of composite seed solution

[0075] The composite seed solution is the composite seed solution prepared in step (3) of Example 1;

[0076] The composition of TSB medium is: 15 g tryptone, 5 g soy peptone, 5 g sodium chloride and 1000 mL distilled water, pH = 7.2 ± 0.2, and it is used after being sterilized by pressure steam at 121°C.

[0077] NaCl was added to the original TSB medium to prepare a series of TSB medium concentrations to simulate different levels of salt conditions. The final mass concentrations of NaCl in the TSB medium were 0mM, 50mM, 100mM, 200mM and 400mM, respectively. The composite seed solution was inoculated into the TSB medium with different salt stress levels at a volume ratio of 1%. After inoculation, the TSB medium was shaken for 48 hours at a temperature of 28°C and a speed of 180r / min to obtain the culture solution. The absorbance of the culture solution at 600nm indicates the salt tolerance of the composite seed solution. Three groups of repeated parallel experiments were set up under each NaCl mass concentration condition. The results are shown in Table 1. According to Table 1, the composite seed solution can grow and reproduce under different NaCl mass concentrations and has salt tolerance.

[0078] Table 1 Salt tolerance of composite seed solution

[0079]

[0080] 2. Growth-promoting properties of composite seed solution in simulated salt environment

[0081] The composite seed solution is the composite seed solution prepared in step (3) in Example 1.

[0082] 1) NH production 3 Activity: Take the composite seed solution that has been cultured for 24 hours and inoculate it into a test tube containing 10mL of peptone water (10g of peptone, 5g of NaCl and 1000mL of distilled water, pH=7.6), and culture it at 28℃ for 2 days. Add 0.5mL of Nessler's reagent to each tube. If a yellow-brown precipitate appears, it indicates that the NH4+-producing cell has the ability to produce NH4+- ... 3 If there is no yellow-brown precipitate, it means that it does not produce NH 3 Activity. Results are shown in Figure 1 and Table 2-1, according to Figure 1 As shown in Table 2-1, the composite seed solution has the ability to produce NH under different levels of salt stress. 3activity.

[0083] 2) Ability to dissolve inorganic phosphorus: Take the fresh composite seed solution cultured for 24 hours and inoculate it on Pikovasky's phosphate dissolving medium with an inoculum volume of 8 μL. Culture it at 28°C for 5 days. If a transparent circle appears around the colony, it indicates that it has the ability to dissolve inorganic phosphorus. Figure 1 and Table 2-1, according to Figure 1 As shown in Table 2-1, the composite seed solution has the ability to dissolve inorganic phosphorus at a salt level greater than or equal to 100 mM.

[0084] 3) IAA production capacity: The composite seed solution freshly cultured for 24 hours was inoculated into LB liquid medium containing 0.5 g / L tryptophan, with an inoculum amount of 1% of the volume of the LB liquid medium. The culture was shaken at 28°C and 180 r / min for 5 days. The absorbance was measured at 530 nm and the IAA (indoleacetic acid) content was calculated. The standard curve formula for calculating IAA was Y=0.0147X-0.0004, R 2 =0.9979, where Y is OD 530 The content of X is the measured IAA value. Figure 1 and Table 2-1, according to Figure 1 As shown in Table 2-1, the ability of the composite seed liquid to produce IAA is higher than that of the control under different levels of salt stress. 4) Ability to produce iron carriers: Take the freshly cultured composite seed liquid for 24 hours and inoculate it on the universal CAS medium plate with an inoculation volume of 8μL. Culture it at 28℃ for 5 days. If a transparent circle appears around the colony, it is positive. Measure the diameter of the transparent circle D (cm) and the colony diameter d (cm), and calculate the D / d value. The larger the D / d ratio, the greater the iron carrier production activity. See the results. Figure 1 and Table 2-1, according to Figure 1 As can be seen from Table 2-1, the composite seed liquid has the ability to produce iron carriers at different salt levels.

[0085] 5) Protease activity: Take the composite seed liquid that has been cultured for 24 hours and inoculate it on the protease-producing bacteria screening medium using the filter paper method. Culture it at 28℃ for 5 days. The transparent circle around the colony is positive. Measure the diameter of the transparent circle D (cm) and the colony diameter d (cm), and calculate the D / d value. The larger the D / d value, the stronger the protease production ability. See the results. Figure 1 and Table 2-1, according to Figure 1 As can be seen from Table 2-1, the composite seed liquid has protease activity at different salt levels.

[0086] Table 2-1 Growth-promoting properties of composite seed solution under different simulated salt environments

[0087]

[0088]

[0089] Note: When determining the IAA production capacity of the composite seed liquid, the original absorbance is the data obtained after the bacterial liquid is diluted four times. Therefore, when calculating the concentration, the data obtained by the standard curve formula should be multiplied by four times.

[0090] 3. Growth-promoting effect of composite seed solution

[0091] (1) Licorice seed pretreatment: Select licorice seeds with full grains and uniform size, first use 85% concentrated H 2 SO 4 The samples were immersed for 45 min, then rinsed with distilled water for 3 times, and then treated with 0.1% H 2 O 2 Disinfect for 10 minutes, rinse with distilled water several times, place in a beaker, soak in distilled water for 6 hours to allow the seeds to fully absorb water, and set aside.

[0092] (2) Experimental design: A completely randomized design was adopted, with a total of 2 treatments, namely, a salt stress treatment group (S, NaCl mass concentration of 150mM) and a composite seed solution treatment group (S+B, NaCl was added to the composite seed solution, the mass concentration of NaCl in the composite seed solution was 150mM) prepared in step (3) of Example 1 of the present invention. Select the licorice seeds that have fully absorbed water and are plump and uniform in step (1), dry the surface moisture, and evenly place them on a culture dish (diameter 9cm) padded with a double layer of sterile filter paper, 50 seeds per dish, 10mL of sodium chloride solution with a mass concentration of 150mM was added to each dish of the salt stress treatment group, and 10mL of composite seed solution with a mass concentration of 150mM was added to each dish of the composite seed solution treatment group, and 3 parallel experiments were set for each treatment group. The seed germination experimental conditions were light treatment for 12h, temperature of 28°C; dark treatment for 12h, temperature of 20°C. Distilled water was added to each dish by weighing method to a constant mass every day to maintain constant matrix conditions. After germination, the diameter of the embryo and radicle of each treatment of licorice seedling was measured with a vernier caliper, and the dry weight was measured by drying at 60℃. The results are shown below. Figure 2 According to Table 2-2 and Figure 2 It can be seen that the composite seed solution prepared by the present invention can promote the growth of licorice seedlings in a salt environment.

[0093] Table 2-2 Germination of licorice seeds in the treatment group

[0094]

[0095] Note: Different letters in the same column represent significant differences among treatments, P < 0.05.

[0096] Example 3 Method and effect of compound microbial fertilizer in improving saline-alkali soil

[0097] 1. Test materials

[0098] (1) The composite microbial fertilizer prepared in Example 1; (2) Saline-alkali soil: The test soil samples were taken from the 0-20 cm surface soil of the test field of Team 1, Nanliang Farm, Xixia District, Yinchuan City, Ningxia. The retrieved soil samples were placed in a cool place to air-dry, and the plant roots, gravel and other debris in the soil samples were removed. They were air-dried, ground, and sieved to 2.5 mm for use. The mechanical composition of the soil was measured using the Bettersizer 2000 laser particle size analyzer produced by Dandong Better Instrument Co., Ltd. The volume fractions of the physical sand and powder particles in the soil were 86.47% and 12.39%, respectively. According to the international soil texture classification standard, the soil is sandy loam, and the bulk density of the test soil is 1.41 g / cm 3 The field water holding rate is 20.99% by mass percentage, the initial salt content is 4.04 g / kg, and the pH value is 8.2, which belongs to slightly saline-alkali soil (the type of slightly saline-alkali soil is determined according to the literature (Zhao Zizhen, Yin Xuefeng. Afforestation technology for wind-eroded and desertified saline-alkali land in Tongshuo area [J]. Inner Mongolia Forestry Investigation and Design, 2012, 35(05): 60-61.)).

[0099] 2. Test methods and design

[0100] A soil column simulation infiltration test was conducted using a straight cylindrical pot with holes at the bottom. The diameter of the straight cylindrical pot was 19.5 cm and the height was 16.5 cm. Filling was performed according to the dry bulk density. Each straight cylindrical pot was filled with 6.90 kg of air-dried soil. The specific filling steps were as follows: first fill the bottom of the straight cylindrical pot with air-dried soil and then compact it. The thickness of the compacted air-dried soil was 2 cm, and the air-dried soil was spread on the top of the previously compacted soil. Three parallel experiments were set up, with a total of three straight cylindrical pots.

[0101] The application rate of compound microbial fertilizer was 1 mL / kg air-dried soil, that is, 6.9 mL of compound microbial fertilizer was applied to each straight pot, and the compound microbial fertilizer infiltrated into the soil with the first irrigation. During the experiment, irrigation was carried out three times, and the amount of water for each irrigation was 1750 mL according to the saturated irrigation volume.

[0102] After each irrigation, the straight pots were placed in an outdoor greenhouse for natural evaporation for 10 days before sampling. After the first sampling, all test pots were irrigated for the second time, and natural evaporation continued for 10 days after the irrigated pots, and the second sampling was carried out. After the second sampling, all test pots were irrigated for the third time, and natural evaporation continued for 10 days after the irrigated pots, and the third sampling was carried out. Only 1750 mL of water was used for the second and third irrigated pots.

[0103] Example 4

[0104] Same as Example 3, the only difference is that the application rate of the composite microbial fertilizer in the test method and design of step 2 is 2 mL / kg air-dried soil.

[0105] Example 5

[0106] Same as Example 3, the only difference is that the application rate of the composite microbial fertilizer in the test method and design of step 2 is 3 mL / kg air-dried soil.

[0107] Example 6

[0108] Same as Example 3, the only difference is that the application rate of the composite microbial fertilizer in the test method and design of step 2 is 4 mL / kg air-dried soil.

[0109] Example 7

[0110] Same as Example 3, the only difference is that the application rate of the composite microbial fertilizer in the test method and design in step 2 is 5 mL / kg air-dried soil.

[0111] Comparative Example 1

[0112] The same as Example 3, the only difference is that the application amount of the composite microbial fertilizer in the experimental method and design of step 2 is 0 mL / kg air-dried soil, that is, no composite microbial fertilizer is applied.

[0113] The application amount of composite microbial fertilizer and the total amount of irrigation water for Examples 3 to 7 and Comparative Example 1 are shown in Table 3-1. Figure 3 .

[0114] Table 3-1 Application amount of composite microbial fertilizer and total amount of first irrigation in Examples 3 to 7 and Comparative Example 1

[0115] Treatment Group Application amount of compound microbial fertilizer (mL) Water volume (mL) Total irrigation volume (mL) Comparative Example 1 0 1750 1750 Example 3 6.9 1743.1 1750 Example 4 13.8 1736.2 1750 Example 5 20.7 1729.3 1750 Example 6 27.6 1722.4 1750 Example 7 34.5 1715.5 1750

[0116] The sampled soils of Examples 3 to 7 and Comparative Example 1 were tested, and the test items and methods were as follows:

[0117] (1) Content of soil water-stable aggregates

[0118] The soil aggregates of Examples 3 to 7 and Comparative Example 1 after three samplings were determined by wet sieving method, as follows:

[0119] Stack the sieves with aperture sizes of 2, 1, 0.5, 0.25, and 0.053 mm from top to bottom, weigh 100g of soil sample from the CK treatment group and place it on the top sieve, slowly put the sieve into water and let it soak for 5 minutes, and then use an aggregate analyzer to grade the soil sample at a vibration frequency of 40 times / min, an amplitude of 5cm, and oscillation for 5 minutes. Finally, slowly take the sieve out of the water, collect the soil aggregates of each level in each sieve into an aluminum box, place it in an oven to dry, and weigh it to determine the content of soil aggregates at each level. The temperature of the oven is set to 55℃.

[0120] Water stable macroaggregate content (R 0.25 ) is calculated as:

[0121]

[0122] In formula (1): R 0.25 is the content of agglomerates with a particle size greater than 0.25 mm (%); m r>0.25 is the weight of agglomerates with a particle size greater than 0.25 mm (g); m T is the total mass of the aggregates (g).

[0123] (2) Soil quality and moisture content

[0124] The soil moisture content of Examples 3 to 7 and Comparative Example 1 was immediately measured by drying method after three samplings.

[0125] The drying method was adopted: 2-10 cm of soil was taken from the straight pots of each treatment group in Examples 3-7 and Comparative Example 1, and the soil mass moisture content of the soil samples in parallel experiments was measured respectively.

[0126] Soil mass water content (%) = (m 1 -m 2 ) / m 2 ×100 (2)

[0127] In formula (2): m 1 、m 2 They are original soil mass and dried soil mass respectively.

[0128] (3) Soil moisture characteristic curve

[0129] In Examples 3 to 7 and Comparative Example 1, soil samples were obtained after three times of sampling with a circular knife. The soil samples were respectively soaked in distilled water for 48 hours to make the soil saturated. The relationship between the water suction of the soil and the water content of the soil mass was determined by using a pressure membrane instrument method and selecting different pressure values.

[0130] The soil moisture characteristic curve was fitted using the Gardner power function equation according to formula (3).

[0131] θ=aS -b (3)

[0132] In formula (3), θ is the soil mass water content (%), S is the soil water suction (kPa); a and b are parameters, a represents the soil water holding capacity, and b represents the speed of soil water content change when the soil water suction changes;

[0133] By differentiating the Gardner equation in formula (3), we can get the expression of water capacity, see formula (4).

[0134]

[0135] (4) Soil salinity and nutrient determination methods

[0136] The test base set up an online soil moisture monitoring system (purchased from Beijing Mengchuang Weiye Technology Co., Ltd.), which is mainly composed of an automatically running information collection terminal and a host computer central control system. The soil moisture sensor is inserted into the soil to directly obtain soil moisture information, which is then converted into an analog voltage signal and transmitted to the information collection terminal, and then transmitted to the host computer central control system through a wireless communication network. Finally, the soil moisture information data is analyzed through an algorithm, and unstable data is automatically eliminated and stored in the system database.

[0137] The sampled soils of Examples 3 to 7 and Comparative Example 1 were tested, and the test results are as follows:

[0138] (1) Soil water stability aggregates and soil mass water content

[0139] The results of soil water-stable aggregates and soil mass water content after infiltration of different doses of compound microbial fertilizer are shown in Table 3-2. The composition and basic characteristics of soil aggregates are one of the key indicators that determine the physical processes and effects of soil erosion, compaction, and compaction, and are the basis of soil fertility and an important indicator for evaluating soil quality. The content of aggregates with a particle size greater than 0.25 mm is usually used as an indicator and is called water-stable aggregates. The results of soil water-stable aggregates and soil mass water content calculated according to formula (1) and formula (2) are shown in Table 3-2. It can be seen from Table 3-2 that in the soil layer, the content of soil water-stable aggregates treated with different doses of compound microbial fertilizers is greater than that of comparative example 1, and the treatments of Examples 3 to 7 are respectively increased by 17.8%, 63%, 82%, 54.7% and 64.4% compared with CK, indicating that the application of compound microbial fertilizers can improve the aggregate structure of saline-alkali soil. The profile moisture content of Examples 3 to 7 with the application amount of composite microbial fertilizer increased by 19.97%, 12.16%, 15.25%, 25.32% and 17.79% respectively compared with CK, indicating that the use of composite microbial fertilizer can improve the water retention performance of saline-alkali soil, thereby improving the quality moisture content of saline-alkali soil.

[0140] Table 3-2 Soil water-stable aggregates and soil mass water content under different treatments

[0141] Treatment Group Soil water-stable aggregate content (%) Soil mass water content (%) Comparative Example 1 7.3±0.5d 19.59±0.44e Example 3 8.6±0.3c 23.54±0.26b Example 4 11.9±0.5b 21.97±0.2d Example 5 13.3±0.2a 22.58±0.37cd Example 6 11.3±0.4b 24.55±0.24a Example 7 12±0.4b 23.08±0.17bc

[0142] Note: Different lowercase letters in the same column represent significant differences among treatments, P < 0.05.

[0143] (2) Soil water supply and water holding capacity

[0144] ①Soil moisture characteristic curve and water content expression

[0145] The soil moisture characteristic curve characterizes the relationship between soil mass water content and soil water suction, reflects the relationship between soil water energy and quantity, and is a basic characteristic curve for studying soil moisture retention and movement. The soil moisture characteristic curves of the soils treated differently in Comparative Example 1 and Examples 3 to 7 in the range of 0 to 1000 kPa are shown in the figure. Figure 4 The specific data is shown in Table 3-3. Figure 4 It can be seen that when the soil mass moisture content is the same, the soil water absorption shows a trend of first increasing and then decreasing with the increase in the amount of compound microbial fertilizer applied, among which the soil water absorption of Example 6 is the largest, that is, applying compound microbial fertilizer to the soil can reduce the soil matrix potential and enhance the soil's ability to retain water.

[0146] Table 3-3 shows the soil mass water content of the soils treated differently in Comparative Example 1 and Examples 3 to 7 within the range of 0 to 1000 kPa

[0147]

[0148]

[0149] The soil moisture characteristic curve and soil water capacity are fitted by formula (3) and formula (4). As shown in Table 4, the fitting coefficients are all above 0.953, indicating that the established power function equation can better reflect the changes in the soil moisture characteristic curve. The parameter a in formula (3) reflects the soil water holding capacity. The larger the a value, the stronger the soil water holding capacity; the parameter b reflects the speed of change of soil water content when the soil water suction changes. The larger the b value, the faster the speed of change of soil volume and soil mass water content. The parameters a of the different treatment groups of Comparative Example 1 and Examples 3 to 7 are 36.30, 37.13, 40.34, 39.69, 41.41, and 40.06, respectively. The parameters b of the different treatment groups of Comparative Example 1 and Examples 3 to 7 are 0.161, 0.162, 0.154, 0.157, and 0.155, respectively. It can be seen that the soil water holding capacity of the different treatment groups of Examples 3 to 7 is greater than that of Comparative Example 1, and the speed of change of soil water content is less than that of Comparative Example 1. Example 6 has the best effect on soil water retention performance, and after repeated dry-wet cycles, the soil texture becomes looser and the number of large pores in the soil is increased.

[0150] Table 4 Soil moisture characteristic curve and water capacity of comparative example 1 and examples 3 to 7

[0151] Treatment Group Soil moisture characteristic curve expression The expression of water content Correlation coefficient Comparative Example 1 <![CDATA[θ=36.30S -0.161 ]]> <![CDATA[C(θ)=5.84S -1.161 ]]> 0.991 Example 3 <![CDATA[θ=37.16S -0.162 ]]> <![CDATA[C(θ)=6.02S -1.162 ]]> 0.988 Example 4 <![CDATA[θ=40.43S -0.154 ]]> <![CDATA[C(θ)=6.22S -1.154 ]]> 0.971 Example 5 <![CDATA[θ=39.69S -0.157 ]]> <![CDATA[C(θ)=6.23S -1.157 ]]> 0.996 Example 6 <![CDATA[θ=41.41S -0.155 ]]> <![CDATA[C(θ)=6.42S -1.155 ]]> 0.976 Example 7 <![CDATA[θ=40.06S -0.157 ]]> <![CDATA[C(θ)=6.29S -1.157 ]]> 0.953

[0152] 2) Soil moisture constant

[0153] The soil moisture constant was calculated by combining the soil moisture characteristic curve expression in Table 4, and the results are shown in Table 5. The application of different doses of composite microbial fertilizer can increase the soil field water holding capacity (i.e., the soil moisture content when the capillary suspended water reaches the maximum value (the soil water suction is 30kPa)), the effective water content (i.e., the amount of water in the soil that can be absorbed by the plant roots (the soil water suction is 500kPa)) and the wilting water content (i.e., the water content when the crop wilts and cannot recover (the soil water suction is 1500kPa)) to varying degrees. The soil water content of the treatment groups of Examples 3 to 7 was 1.377, 1.737, 1.777, and 1.677, respectively. The field water holding capacity of soil increased by 2.04%, 14.1%, 10.86%, 16.43% and 11.91% respectively compared with comparison example 1; the effective water of soil increased by 1.72%, 16.32%, 12.06%, 18.35% and 13.11% respectively compared with comparison example 1; the wilting water content of soil increased by 1.61%, 17.17%, 12.61%, 19.14% and 13.68% respectively compared with comparison example 1.

[0154] Table 5 Soil moisture constants of different treatments of Comparative Example 1 and Examples 3 to 7

[0155] Treatment Group Soil field water holding capacity (%) Soil effective water content (%) Soil wilting moisture content (%) Comparative Example 1 20.99 13.35 11.18 Example 3 21.42 13.58 11.36 Example 4 23.95 15.53 13.10 Example 5 23.27 14.96 12.59 Example 6 24.44 15.80 13.32 Example 7 23.49 15.10 12.71

[0156] 3) Soil water capacity

[0157] Soil water capacity is a quantitative indicator of soil water release, which can be used to evaluate the effectiveness of soil moisture. It reflects the change in soil water content caused by changes in soil water suction, and decreases with the increase of soil water suction, which characterizes the effectiveness of soil moisture and the strength of water supply capacity. Under the same soil water suction conditions, the greater the soil water capacity, the stronger the soil water supply capacity. The soil water capacity was calculated according to the water capacity expression in Table 4, and the results are shown in Table 6. According to Table 6, under any water suction, the soil water capacity of the treatment groups of Examples 3 to 7 is greater than that of Comparative Example 1, and in the entire infiltration stage, the water capacity of Example 6 under any water suction is greater than that of the other treatments. It shows that the application of any dose of composite microbial fertilizer can effectively improve the water capacity of the soil, and the addition dose of the composite microbial fertilizer in Example 6 has the best effect.

[0158] Table 6 Soil water capacity under different soil water suction (unit: mL / (kPa·g))

[0159]

[0160]

[0161] (4) Determination of soil salt and nutrient content

[0162] The soil salinity and nutrient content of the soil in Comparative Example 1 and Examples 3 to 7 were measured using a soil moisture monitoring system.

[0163] The results of soil salinity and nutrient determination at the same depth of the comparative example 1 and the treatment groups of Examples 3 to 7 are shown in Table 7. According to Table 7, in the entire soil layer, the treatment groups of Examples 3 to 7 significantly reduced the soil salt content compared with the comparative example 1, and the reduction in salt content was 13.45%, 9.11%, 25.95%, 57.01% and 46.65% respectively. The effective nitrogen, phosphorus and potassium in the soil are crucial to the growth of plants. The treatment groups of Examples 3 to 7 significantly increased the content of various nutrients in saline-alkali soil compared with the comparative example 1. The total nitrogen content of the soil in the treatment group of Comparative Example 1 increased by 8.1%, 16.51%, 31.85%, 72.32% and 59.07% respectively compared with that in Comparative Example 1; the available phosphorus content in the soil increased by 12.04%, 30.53%, 37.85%, 68.64% and 62.73% respectively compared with that in Comparative Example 1; the available potassium content in the soil increased by 11.6%, 21.11%, 43.76%, 73.09% and 47.72% respectively compared with that in Comparative Example 1; the ammonia nitrogen content in the soil increased by 19.04%, 59.06%, 67.45%, 73.49% and 70.47% respectively compared with that in Comparative Example 1; and the nitrate nitrogen content in the soil increased by 9.35%, 29.8%, 35.77%, 79.27% ​​and 72.21% respectively compared with that in Comparative Example 1.

[0164] It can be seen from this that the composite microbial fertilizer of the present invention can effectively reduce the salt content of saline-alkali soil and increase the nutrient content of soil.

[0165] Table 7 Soil salinity and nutrients in different treatment groups

[0166]

[0167] Note: Different lowercase letters in the same column represent significant differences among treatments, P < 0.05.

[0168] In summary, the application of different doses of compound microbial fertilizers by water infiltration can significantly improve salinized soil, which is specifically reflected in the following aspects: compound microbial fertilizers reduce the salt content of salinized soil by 9.11% to 57.01%; compound microbial fertilizers fertilize saline-alkali soil, that is, increase the contents of total nitrogen, available phosphorus, available potassium, ammonia nitrogen and nitrate nitrogen in saline-alkali soil by 8.10% to 72.32%, 12.04% to 68.64%, 11.60% to 73.09%, 19.04% to 73.49 and 9.35% to 79.27%, respectively.

[0169] Application Example 1: Effects of compound microbial fertilizer on the emergence and growth of oil sunflower in saline-alkali soil and soil salt, water and nutrients

[0170] 1 Test materials: The soil sample used in the test is the same as the saline-alkali soil in (2) of the test materials in step 1 of Example 3. The plant material used is oil sunflower. The composite microbial fertilizer prepared in Example 1.

[0171] 2 Test method and design: adopt outdoor pot plant test method, test pot used and soil filling method are the same as embodiment 3. Experimental setting 3 treatment groups, respectively CK treatment group, F1 treatment group, F2 treatment group, wherein the application amount of compound microbial fertilizer in each test pot of CK treatment group is 0mL, water application amount 1750mL (reaching saturated water content state); The application amount of compound microbial fertilizer in each test pot of F1 treatment group is 1mL / kg air-dried soil, i.e. compound microbial fertilizer 6.9mL, water application amount 1743.1mL, compound microbial fertilizer and water total 1750mL (reaching saturated water content state); The application amount of compound microbial fertilizer in each test pot of F2 treatment group is 2mL / kg air-dried soil, i.e. compound microbial fertilizer application amount is 13.8mL, water application amount 1736.2mL, compound microbial fertilizer and water total 1750mL (reaching saturated water content state). Each treatment group is provided with 3 parallel experiments, 3 test pots in total.

[0172] The soil of the CK, F1, and F2 treatment groups was incubated for one week after irrigation, and the soil was kept moist during this period. Sunflower seeds were sown on May 24, with 9 seeds sown in each pot and 3 pots sown in each treatment group. One week after sowing, the germination rate of the sunflower was counted and the seedlings were transplanted, with 2 plants per pot. Sunflower plant samples were collected twice during the budding and flowering stages to measure the growth indicators of the sunflower. The two collection times for the budding stage were June 28 and July 10, respectively; the two collection times for the flowering stage were July 20 and July 28, respectively. The soil was tested once on July 10 during the budding stage and on July 28 during the flowering stage (the soil sample test results adopted the average of the two times), see Figure 5 During the entire growth period of the oil sunflower, irrigation was carried out regularly according to the overall soil moisture conditions. The amount of water for each treatment was uniform during each irrigation, and the effect of water demand on crop growth was not considered. The test results were the average of 3 pots of repetitions.

[0173] 3. Measurement items and methods

[0174] (1) Determination of soil salinity and nutrient content: the same determination items and methods as step 3 of Example 3.

[0175] (2) Oil sunflower growth index: The oil sunflower crop growth index was measured twice in the test pots at the bud stage and the flowering stage. The height of each oil sunflower was measured with a tape measure. The leaves were measured one by one with a ruler. The leaf length was measured from the base to the tip of the leaf, and the leaf width was measured at the widest part of the leaf. The leaf area of ​​each oil sunflower was calculated cumulatively. The single leaf area of ​​oil sunflower (cm 2) = leaf length (cm) × leaf width (cm) × 0.65.

[0176] 4. Measurement results

[0177] The results of the measurement of the oil sunflower crop growth indexes of the CK treatment group, the F1 treatment group, and the F2 treatment group are shown in Table 8. According to Table 8, the emergence rate of the oil sunflower in the F1 treatment group and the F2 treatment group was significantly improved, and the oil sunflower in the F2 treatment group was higher than that in the F1 treatment. It can be seen that the compound microbial fertilizer has a significant promoting effect on the growth of oil sunflowers at different growth stages, that is, it significantly increases the plant height and leaf area of ​​oil sunflowers. The effect of the oil sunflower plant height in the F2 treatment group at the budding stage is better than that in the F1 treatment group, while the effect of the oil sunflower on the leaf area in the flowering stage is stronger in the F1 treatment group than in the F2 treatment group.

[0178] Table 8 Effects of compound microbial fertilizer on plant height and leaf area of ​​oil sunflower in saline-alkali soil under different treatments

[0179]

[0180] The determination results of soil salinity and nutrients of potted oil sunflower in CK treatment group, F1 treatment group and F2 treatment group are shown in Table 9. The soil salt content of F1 treatment group and F2 treatment group is reduced relative to CK group. It can be seen that different doses of composite microbial fertilizer treatments have significantly reduced the salt content of saline-alkali soil. The soil nutrient content of F1 treatment group and F2 treatment group is increased relative to CK group. It can be seen that different doses of composite microbial fertilizer treatments have significantly increased the content of total nitrogen, ammonia nitrogen, nitrate nitrogen, available phosphorus and available potassium in the soil. In summary, the use of composite microbial fertilizer of the present invention can reduce the soil salt content of potted oil sunflower and increase the soil nutrient content.

[0181] Table 9 Soil salt content and nutrient content of potted oil sunflower in different treatment groups

[0182]

[0183] In summary, the composite microbial fertilizer of the present invention can improve the germination rate of oil sunflower seeds, promote the growth of oil sunflower plants, and reduce the salt content and nutrient content of the soil of potted oil sunflowers.

[0184] Application Example 2: Effect of compound microbial fertilizer on the emergence and growth of upland rice in saline-alkali soil

[0185] 1. Test materials

[0186] The soil sample used in the experiment is the same as the saline-alkali soil in step (2) of Example 3. The plant material used is upland rice.

[0187] The composite microbial fertilizer prepared in Example 1.

[0188] 2. Test methods and design:

[0189] The outdoor potted plant test method was adopted. The test pots and soil filling method used were the same as those in Example 3. Three treatment groups were set up in the experiment, namely the CK treatment group, the F1 treatment group, and the F2 treatment group.

[0190] The CK treatment group did not apply compound microbial fertilizer, and the amount of water applied was 1750 mL. The F1 treatment group applied 1 mL of compound microbial fertilizer / kg of air-dried soil, that is, 6.9 mL of compound microbial fertilizer was applied in each test pot, the amount of water applied was 1743.1 mL, and the total amount of compound microbial fertilizer and water applied was 1750 mL. The F2 treatment group applied 2 mL of compound microbial fertilizer / kg of air-dried soil, that is, 13.8 mL of compound microbial fertilizer was applied in each test pot, the amount of water applied was 1736.2 mL, and the total amount of compound microbial fertilizer and water applied was 1750 mL.

[0191] The soil was cultured for one week, and the soil was kept moist. The upland rice seeds were sown on May 24, and the germination rate was counted one week after sowing. 37 seeds were sown in each pot. Three parallel experiments were set up for each treatment group, with a total of 3 test pots, and the results are the average of the 3 pots.

[0192] 3. Measurement results

[0193] The germination rates of upland rice in the CK, F1 and F2 treatment groups are shown in Table 10. Figure 6 and Figure 7 ,in Figure 6 The three test pots in the first row from top to bottom are the upland rice germination of the F2 treatment group, and the three test pots in the second row from top to bottom are the upland rice germination of the F1 treatment group. Figure 6 and Figure 7 It can be seen that the treatments with different doses of compound microbial fertilizer, namely the F1 treatment group and the F2 treatment group, significantly increased the germination rate of upland rice, with the increase reaching 79.99% to 99.96%, promoting the growth of upland rice.

[0194] Table 10 Statistical results of upland rice germination rate in different treatment groups

[0195]

[0196] In summary, the composite seed solution of the present invention has salt tolerance and can produce NH 3 , dissolves inorganic phosphorus, produces IAA, produces iron carriers, and produces proteases. The composite microbial fertilizer prepared from the composite seed liquid can improve the water retention performance of saline-alkali soil, thereby increasing the water content of saline-alkali soil quality, enhancing the soil's ability to retain water, and increasing soil field water holding capacity, soil effective water content, soil wilting water content, and soil water capacity. The composite microbial fertilizer can also reduce the salt content of saline-alkali soil, increase the soil nutrient content, and has a plant growth-promoting effect.

[0197] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. Application of Bacillus cereus and Bacillus pumilus in promoting the growth of salt-alkali tolerant plants, wherein the salt-alkali tolerant plants are upland rice or oil sunflower; the Bacillus cereus includes Bacillus cereus ( Bacillus cereus ) G2, the Bacillus pumilus includes Bacillus pumilus ( Bacillus pumilus )G5.

2. The use according to claim 1, It is characterized in that The plant growth promotion includes increasing one or more of the seedling emergence rate, plant height, leaf area and yield.

3. Application of Bacillus cereus and Bacillus pumilus in improving saline-alkali soil, wherein the improved saline-alkali soil comprises one or more of 1) to 4); the Bacillus cereus comprises Bacillus cereus ( Bacillus cereus ) G2, the Bacillus pumilus includes Bacillus pumilus ( Bacillus pumilus )G5; 1) Increase the water holding capacity and water supply capacity of saline-alkali soil; 2) Reduce the salt content of saline-alkali soil; 3) Increase the content of one or more nutrients including total nitrogen, available phosphorus, available potassium, ammonia nitrogen and nitrate nitrogen in saline-alkali soil; 4) Increase the content of water-stable aggregates in soil.

4. The use according to claim 1 or 2, It is characterized in that The growth-promoting properties of Bacillus cereus and Bacillus pumilus include production of NH 3 , dissolving inorganic phosphorus, producing IAA, producing siderophore and producing protease, or one or more of the following.

5. The use according to any one of claims 1 to 3, It is characterized in that The application method of the Bacillus cereus and Bacillus pumilus includes preparing them into composite seed liquid or composite microbial fertilizer and then applying them to plants or soil; The preparation of the composite seed solution includes: mixing Bacillus cereus seed solution and Bacillus pumilus seed solution; the number of live bacteria of Bacillus cereus in the composite seed solution is 1.5×10 12 cfu / mL~1.8×10 12 cfu / mL; the number of viable Bacillus pumilus in the composite seed solution is 4×10 11 cfu / mL~5.5×10 11 cfu / mL; The preparation of the composite microbial fertilizer comprises: fermenting the composite seed liquid to obtain the composite microbial fertilizer; the culture medium used in the fermentation comprises 20g maltose, 16.8g yeast extract powder, 4.0g Na 2 HPO 4 , 2.0gNaH 2 PO 4 、0.5gMgSO 4 , 0.2gCaCl 2 and 1L of distilled water.

6. The use according to claim 5, It is characterized in that The number of viable bacteria of Bacillus cereus in the composite seed liquid was 1.65×10 12 cfu / mL; the number of viable Bacillus pumilus in the composite seed solution was 4.95×10 11 cfu / mL.

7. The use according to claim 5, It is characterized in that The total number of effective living bacteria of Bacillus cereus and Bacillus pumilus in the composite microbial fertilizer is 50×10 12 cfu / mL~60×10 12 cfu / mL; when the compound microbial fertilizer is applied in a planting pot, the mass ratio of the compound microbial fertilizer to the dry weight of saline-alkali soil is (1~5mL):1kg, and when the compound microbial fertilizer is applied in the field, the application amount of the compound microbial fertilizer is 1~2L / mu.

8. The use according to claim 7, It is characterized in that The total number of effective living bacteria of Bacillus cereus and Bacillus pumilus in the composite microbial fertilizer is 56.55×10 12 cfu / mL.

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