Application of bradyrhizobium sp. G94 in acid soil improvement

Abstract

The invention discloses application of bradyrhizobium G94 in acid soil improvement, and relates to the technical field of soil improvement and plant growth promotion. The bradyrhizobium G94 disclosed by the invention is applied to improvement of acid soil, regulation and control of crop nutrient accumulation and improvement of crop stress resistance. The bradyrhizobium G94 is inoculated under acid stress, so that the pH of non-hot-area soil of corn and soybeans is remarkably improved; the total amount of exchangeable acid in soil in the corn and soybean hot areas is remarkably reduced, the content of exchangeable H < + > in the soil in the corn hot area and the non-hot area is increased, and the content of H < + > in the soil in the soybean hot area is reduced; the content of exchangeable Al < 3 + > in soil in a corn and soybean hot area is obviously reduced; the fresh weight of the overground part is obviously reduced, and the fresh and dry weight of root systems of two crops is improved; the TN cumulant, the TC cumulant and the TP content of the root system are remarkably increased, and the TC cumulant and the TP content of the soybean overground part and the TN cumulant and the TC cumulant of the root system are remarkably improved.

Description

Technical Field

[0001] The invention belongs to the technical field of soil improvement and plant growth promotion, and more specifically, relates to the application of Bradyrhizobium G94 in acidic soil improvement. Background Art

[0002] Plant ash has many effects on soil, mainly including improving soil, providing nutrients, repelling insects and preventing diseases. First of all, plant ash is a natural alkaline substance rich in potassium, calcium and trace elements, which makes it a soil conditioner and fertilizer in agriculture. Applying plant ash can neutralize acidic soil, increase soil pH, improve soil structure, increase soil permeability, provide plants with the nutrients they need, and thus increase the yield and quality of crops. Secondly, plant ash has the ability to prevent and control pests and diseases. It can be spread in the field to form a layer of fine powder, which has a certain deterrent effect on many pests such as aphids and ants. In addition, plant ash can also reduce fungi and bacteria in the soil, helping to prevent the spread of soil-borne diseases. Plant ash also has the effect of promoting root growth. Spreading plant ash in the field can promote the growth of crop roots, supplement the mineral elements needed by crops, improve the ability of crops to absorb water and fertilizer, and enhance the robustness and resistance to lodging of plants. Finally, plant ash also has a bactericidal effect. It can be used to control aphids, blocking the pests' pores with its alkaline properties and fine particles, causing physiological disorders and death. However, there are some problems with plant ash in soil improvement, including: reaction with acidic fertilizers to cause nitrogen volatilization, unsuitable for alkaline soils, possible burning of seedlings and roots, excessive heavy metals and nutrient loss, possible impact on soil microbial communities, and excessive use of plant ash may also affect groundwater quality, because some soluble minerals and salts may penetrate into groundwater with water. In addition, nutrients in plant ash are easily lost in a humid environment.

[0003] Bradyrhizobium is a type of Gram-negative bacteria that forms nodules with legumes and can fix nitrogen biologically in the nodules. They live in the soil or in nodules formed on the roots of legumes, providing nitrogen nutrition to plants by converting nitrogen in the atmosphere into ammonia that can be used by plants, thereby promoting plant growth. This symbiotic relationship is beneficial to both plants and rhizobia, with plants providing carbohydrates and energy required by rhizobia, while rhizobia provide nitrogen required by plants.

[0004] The colony of Bradyrhizobium grows slowly, with a colony diameter of less than 1 mm after 5 to 7 days, and it takes 6 to 8 days to grow significantly on the culture medium. It does not produce acid on the culture medium containing carbohydrates, but is alkaline instead. This characteristic makes Bradyrhizobium of great application value in agricultural production, especially in the cultivation of leguminous crops. By inoculating Bradyrhizobium, the nitrogen fixation efficiency of crops can be improved, and the use of chemical nitrogen fertilizers can be reduced, which is of great significance to improving soil fertility and sustainable agricultural development.

[0005] In agricultural production, the application of bradyrhizobia is mainly focused on improving the nitrogen fixation efficiency and yield of leguminous crops, reducing the use of chemical nitrogen fertilizers, and improving the agricultural ecological environment. Through synthetic biology, scientists are also working hard to obtain new rhizobia agents suitable for peanut cultivation to further improve crop production efficiency and environmental sustainability. However, the problems existing in the application of bradyrhizobia mainly include the following aspects: slow growth rate, high sensitivity to environmental conditions (especially temperature and pH), narrow range of carbon and nitrogen source utilization, and weak antibiotic resistance.

[0006] Therefore, it is urgent to develop diversified application strategies for bradyrhizobia according to different crops and soil conditions to ensure the effective application of bradyrhizobia in different environments. Summary of the invention

[0007] In view of the above-mentioned problems existing in the prior art, the technical problem to be solved by the present invention is to provide the application of Bradyrhizobium G94 in acidic soil improvement. Another technical problem to be solved by the present invention is to provide the application of Bradyrhizobium G94 in promoting crop growth in acidic soil. Another technical problem to be solved by the present invention is to provide the application of Bradyrhizobium G94 in regulating crop nutrient accumulation in acidic soil. Another technical problem to be solved by the present invention is to provide the application of Bradyrhizobium G94 in improving crop stress resistance, which is used for soil improvement and plant growth promotion.

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0009] The application of Bradyrhizobium G94 in acidic soil improvement, the Bradyrhizobium G94 is deposited in Guangdong Provincial Microbial Culture Collection Center, the preservation date is August 14, 2023, the preservation number is GDMCC.No: 63598, and the preservation address is 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou.

[0010] The soil improvement is to promote the reduction of the total amount of exchangeable acid in acidic soil.

[0011] The soil improvement is to promote H + The content is reduced.

[0012] The soil improvement is to promote the exchangeable Al 3+ The content is reduced.

[0013] The role of Bradyrhizobium G94 in promoting crop growth in acidic soil. The Bradyrhizobium G94 is deposited in the Guangdong Provincial Microbial Culture Collection Center, with a preservation date of August 14, 2023, a preservation number of GDMCC.No: 63598, and a preservation address of 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou.

[0014] The promoting of crop growth is promoting the increase of fresh weight and dry weight of the root system.

[0015] The role of Bradyrhizobium G94 in regulating crop nutrient accumulation in acidic soil. The Bradyrhizobium G94 is deposited in the Guangdong Provincial Microbial Culture Collection Center, with a preservation date of August 14, 2023, a preservation number of GDMCC.No: 63598, and a preservation address of 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou.

[0016] The regulation of crop nutrient accumulation is to promote the increase of total nitrogen, total carbon and total phosphorus content in the crop root system.

[0017] The regulation of crop nutrient accumulation is to promote the increase of total nitrogen and total phosphorus content in the aboveground part of soybeans.

[0018] The application of Bradyrhizobium G94 in improving crop stress resistance, the Bradyrhizobium G94 is deposited in Guangdong Provincial Microbial Culture Collection Center, the preservation date is August 14, 2023, the preservation number is GDMCC.No: 63598, and the preservation address is 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1) Inoculation of Bradyrhizobium G94 (AS+B) under acid stress significantly increased the pH of soil in non-tropical areas of corn and soybean, but had no significant difference in the soil in tropical areas; significantly reduced the total amount of exchangeable acid in soil in tropical areas of corn and soybean; and increased the exchangeable pH of soil in tropical areas and non-tropical areas of corn. + content, but significantly reduced the soil H + The content of soil exchangeable Al in corn and soybean hot zone was significantly reduced. 3+ The content.

[0021] 2) The inoculation of Bradyrhizobium G94 under acid stress conditions significantly increased the fresh weight of the aboveground parts of the plants; inoculation of Bradyrhizobium G94 increased the fresh and dry weights of the roots of the two crops under the level of acid stress.

[0022] 3) Under acid stress treatment, inoculating Bradyrhizobium japonicum G94 significantly increased the TN accumulation, TC accumulation and TP content in the roots; it had no significant effect on the TN accumulation, TC accumulation and TP content in the above-ground parts; it significantly increased the TC accumulation, TP content in the above-ground parts of soybeans and the TN accumulation, TC accumulation in the roots, and had no significant effect on the TN accumulation in the above-ground parts and the TC accumulation, TP content in the roots. Description of the Drawings

[0023] Figure 1 It is the scanning electron microscope image of plant ash;

[0024] Figure 2 It is the N2 adsorption-desorption isotherm diagram of plant ash;

[0025] Figure 3 It is the FT-IR diagram of plant ash;

[0026] Figure 4 It is the diagram of the physical and chemical properties of paddy soil after adding plant ash;

[0027] Figure 5 It is the diagram of the dynamic changes of the physical and chemical properties of paddy soil after adding plant ash;

[0028] Figure 6 It is the correlation analysis diagram of the physical and chemical properties of paddy soil after adding plant ash ("*" indicates 0.01 < p ≤ 0.05, "**" indicates p ≤ 0.01);

[0029] Figure 7 It is the two-dimensional analysis diagram of PC1 and PC2 of the physical and chemical properties of paddy soil after adding plant ash;

[0030] Figure 8 It is the diagram of the effect of inoculating Bradyrhizobium japonicum G94 on the soil microecology of maize and soybeans under acid stress (A is soil pH; B is the total amount of exchangeable acid in soil; C is exchangeable hydrogen ion in soil; D is exchangeable aluminum ion in soil);

[0031] Fig. 9 It is the diagram of the effect of inoculating Bradyrhizobium japonicum G94 on the biomass of maize and soybeans under acid stress;

[0032] Fig.10 It is the diagram of the effect of inoculating Bradyrhizobium japonicum G94 on the nutrient content of maize and soybean plants under acid stress. Detailed Embodiments

[0033] To make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described below in conjunction with specific embodiments. In the following embodiments, unless otherwise specified in detail, the technical means used are all conventional means well known to those skilled in the art.

[0034] The Bradyrhizobium G94 used in the following examples is classified and named Bradyrhizobium centrosematis, and is deposited in Guangdong Provincial Microbial Culture Collection Center, with a deposit date of August 14, 2023, a deposit number of GDMCC.No: 63598, and a deposit address of 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou.

[0035] Example 1

[0036] 1. Physical and chemical properties of wood ash

[0037] The wood ash used in this embodiment is the residue remaining from high-temperature combustion of eucalyptus bark as raw material in a biomass power plant. The results are shown in Table 1.

[0038] Table 1 Basic physical and chemical properties of the wood ash prepared in this application

[0039] Material Ash pH 12.2 Conductivity (μS / cm) 2540 Cation exchange capacity (cmol+ / kg) 6.12 Total carbon (%) 6.74 <![CDATA[Available potassium (calculated as K2O) (%)]]> 1.47 Water-soluble calcium (%) 0.35 Water-soluble magnesium (mg / kg) 9.12 Total cadmium (mg / kg) 0.00 Available cadmium (mg / kg) 0.00

[0040] 3. Surface morphology

[0041] The surface morphology of biochar and wood ash was recorded at different magnifications using a German Zeiss Merlin Compact scanning electron microscope with an accelerating voltage of 5 kV.

[0042] The results are as follows Figure 1 As shown, there are more broken particles on the surface of wood ash, but the overall structure is intact with few pores; under the same magnification, it was found that the biochar has a smaller particle size than wood ash, the pores are significantly increased, and the inside of the biochar is hollow; this indicates that biochar has more adsorption sites than wood ash and can adsorb more functional groups, thereby increasing the cation exchange capacity of biochar.

[0043] 4. Specific surface area and pore structure

[0044] The specific surface area and pore size structure of biochar and plant ash were determined using the Micromeritics Tristar 3000 specific surface area and pore size analyzer. The samples were first degassed at 200 °C, and then the adsorption-desorption of N2 on the samples was measured at 77 K. The BET isotherm model was used for analysis and processing to calculate the specific surface area and pore size of the samples.

[0045] The results are shown in Table 2. The specific surface area of ​​wood ash is 9.22 m 2 / g, the specific surface area of ​​biochar is 50.88m 2 / g, which is much higher than that of wood ash. The increase in specific surface area means that the biochar surface contains more adsorption sites, which is conducive to the adsorption and solidification of heavy metals. The total pore volume of wood ash and biochar is not much different, but the micropore volume in wood ash is only 0.001m 2 / g, most of which are mesopores; while the micropore volume in biochar is 0.015m 2 / g, and the mesopore volume is 0.022m 2 / g. The micropore volume in biochar increased significantly, which was consistent with the results observed by scanning electron microscopy.

[0046] The results are as follows Figure 2 As shown in the figure, the N2 adsorption-desorption isotherm of wood ash is concave and has no inflection point. The N2 adsorption amount increases with the increase of the partial pressure of the component, which is a type III N2 adsorption-desorption isotherm. The curve is concave because the mutual attraction between the adsorbate molecules exceeds the attraction between the adsorbate and the adsorbent, which means that the adsorbent faces great difficulties in the initial adsorption of the adsorbate. However, as the adsorption process gradually advances, the adsorption behavior begins to show a self-accelerating trend, and the formation of the adsorption layer is no longer restricted to the isothermal adsorption curve, and the inflection point often appears at a stage close to monolayer adsorption. With the further increase of relative pressure, multilayer adsorption begins to form, and when the saturated vapor pressure of the liquid is reached, the number of adsorption layers tends to be infinite. This makes it difficult to accurately determine the limiting equilibrium adsorption amount by experimental measurement.

[0047] Table 2 Pore structure parameters of wood ash

[0048]

[0049]

[0050] 5. Surface functional groups

[0051] Nicolet iS10 Fourier transform infrared spectrometer was used to analyze and determine various functional groups on the surface of biochar and plant ash. An appropriate amount of sample was ground into powder in an agate mortar, and then mixed with ground potassium bromide in a ratio of KBr:S=20:1. The sample was pressed into tablets using a solid tablet press for 1 minute, with potassium bromide as the background, and the spectral range was scanned from 4000 to 400 cm -1 The resolution is 4cm -1 , each sample was scanned 32 times.

[0052] The results are as follows Figure 3 As shown, wood ash and biochar are at 1690-1635cm -1 、1125-1000cm -1 、775cm -1 There are similar characteristic peaks in the band, which indicates that wood ash may contain C=C, CH-OH, -COO - etc. functional groups.

[0053] Example 2

[0054] The soil used in this embodiment was collected from paddy field soil, and its specific physical and chemical properties were as follows: pH (CaCl2) was 4.38, potential total acidity was 15.7 cmol / kg, conductivity was 290 μS / cm, available potassium content was 35 mg / kg, water-soluble calcium content was 65.8 mg / kg, and water-soluble magnesium content was 6.7 mg / kg. The plant ash used in this experiment was taken from a biomass power plant, pH 12.2, conductivity was 2540 μS / cm, available potassium (calculated as K20) content was 1.47%, water-soluble calcium content was 0.35%, and water-soluble magnesium content was 9.12 mg / kg; 4 treatments of 1%, 5%, 10% of soil mass and no addition of plant ash were set respectively, and each treatment was repeated 3 times, for a total of 12 pots. The soil culture experiment started on January 4, 2022. The paddy field soil and plant ash were fully mixed and put into pots. All soil pots were randomly placed. Water was replenished for each treatment every 3 days by weighing method to maintain the soil moisture content at about 60% of the field water holding capacity during the experiment. It was carried out in the laboratory greenhouse of Guangxi University from January to April 2022.

[0055] On the 7th, 16th, 23rd, 50th, 58th, 69th, 76th and 87th days after the start of the experiment, soil samples of 0-10 cm were collected with a soil drill, naturally air-dried, ground and sieved through a 2 mm sieve for the determination of soil pH and EC; the soil samples sieved through the 2 mm sieve were flattened, and half of the soil was taken using the "quartering method" and further ground and sieved through a 1 mm sieve for the determination of soil available potassium, water-soluble calcium, water-soluble magnesium and potential total acidity.

[0056] 1. Adding wood ash improves the physical and chemical properties of paddy soil

[0057] The results are as follows Figure 4 As shown in the results, there were significant differences in the effects of different wood ash application rates on soil physical and chemical properties. When wood ash was applied to paddy soil at 1%, 5%, and 10%, the soil pH value was significantly increased (p<0.05). Compared with the control, the pH value of paddy soil increased by 0.62, 1.84, and 2.04 units, respectively ( Figure 4 A). Applying wood ash can significantly reduce the potential total acidity of the soil ( Figure 4 B), compared with the control, the application of 1%, 5%, and 10% wood ash in paddy fields reduced the total potential acidity of the soil by 35.9%, 79.0%, and 92.1%, respectively (p<0.05). In this study, the application of 1% wood ash in paddy soil did not cause significant differences in soil conductivity, available potassium, water-soluble calcium, and water-soluble magnesium; however, when the addition of wood ash reached 5% and 10%, the soil conductivity, available potassium, water-soluble magnesium (excluding the addition of 5% wood ash), and water-soluble calcium content increased significantly (p<0.05, Figure 4 CF).

[0058] 2. Dynamic changes in the physical and chemical properties of paddy soil after adding wood ash

[0059] The results are as follows Figure 5 As shown in the figure, in acidic paddy soil, the application of plant ash in the early stage of the experiment (0-7 days) can significantly increase the soil pH, EC, available potassium, and water-soluble calcium and magnesium content, while reducing the potential total acidity of the soil. With the increase in the amount of plant ash applied, the soil pH value increased significantly, and when the amount of plant ash applied reached 10%, the soil pH value reached 6.8. In the middle of the experiment (7-69 days), the soil pH value tended to be stable, the potential total acidity, EC and water-soluble calcium content gradually decreased, while the content of available potassium first increased and then decreased. In the late stage of the experiment (after 69 days), the soil pH value and available potassium were basically stable, but the potential total acidity and EC showed an increasing trend. It can be seen that in paddy soil, the early stage of plant ash application (the first 7 days) can significantly reduce soil acidity and increase the number of base ions. However, due to the soil buffering effect, its effect gradually decayed, and after 69 days of the experiment, the low amount of plant ash application (1%) had no significant effect on increasing soil base ions.

[0060] 3. Correlation and principal component analysis between soil physical and chemical properties after wood ash addition

[0061] The correlation analysis of six soil physical and chemical properties of paddy soil was carried out, and the results are as follows: Figure 6 As shown in the results, there is a very significant correlation between the pH value of paddy soil and the potential total acidity, electrical conductivity, available potassium, water-soluble calcium, and water-soluble magnesium content. Among them, the pH value is negatively correlated with the potential total acidity content (p<0.01), and is strongly positively correlated with electrical conductivity, available potassium, water-soluble calcium, and water-soluble magnesium (p<0.01). The potential total acidity of paddy soil is extremely significantly negatively correlated with soil electrical conductivity, available potassium, water-soluble calcium, and water-soluble magnesium (p<0.01).

[0062] The results are as follows Figure 7 As shown, the first principal component (PC1) has the highest contribution rate, which can explain 88.2% of the total variation, and the second principal component (PC2) contributes 6.0%. Therefore, PC1 can represent most of the screening information. In PC1, EC, available potassium and water-soluble calcium account for a relatively high proportion, so we named this principal component "base ion factor". In order to more clearly show the impact of the treatment on the "base ion factor", we used PC1 and PC2 as the horizontal and vertical coordinates for a two-dimensional principal component analysis (PCA) and plotted it as Figure 3-7 In this figure, the increase in the horizontal axis represents the greater degree of gain of the treatment in the "base ion factor". In the four treatments of this experiment, as the amount of wood ash applied increased, the horizontal axis of the corresponding treatment in the two-dimensional PCA analysis diagram also increased. This shows that wood ash can increase the content of base ions in the soil, thereby increasing the pH value of the soil.

[0063] Example 3

[0064] The test soil in this example is a strongly acidic agricultural soil with a pH of 4.3 and specific nutrient contents of: total carbon 8.93 g / kg; total nitrogen 0.95 g / kg; available phosphorus 12.16 g / kg; and available potassium 76.54 mg / kg. The soil was sieved through a 2 mm sieve and sterilized before the test.

[0065] This implementation uses in situ zymography technology to analyze three enzymes and define the soil partitions in the experiment. The area with a gray value exceeding 25% of the vertical photographic image of the entire planting box (including the root system) is defined as the enzyme activity hotspot area, and the area below 25% is the enzyme activity non-hotspot area. The specific steps are as follows:

[0066] The in situ zymography technique was used to directly study the distribution of enzyme activity at the root-soil interface of corn and soybean plants. The distribution of rhizosphere enzyme activity was observed using a saturated filter membrane soaked in 4-Methyl umbelliferone (MUF) in advance. The filter membrane size was 20 cm × 20 cm. The principle is that the substrate will fluoresce under the hydrolysis of a specific enzyme. Under ultraviolet light, the fluorescence intensity released after the substrate is hydrolyzed by the enzyme is proportional to the enzyme activity. Open from one side of the transparent root box, and place the saturated membrane soaked in the substrate close to the root-soil interface to allow the substrate and enzyme to react fully. Cover the membrane surface with a layer of tin foil to create a dark environment and cover the transparent plate of the root box back. After the enzymatic reaction for 1 hour, carefully peel off the membrane from the soil surface, gently remove the attached soil particles with tweezers and a small brush, and then place the filter membrane in a dark box and use a camera to image under ultraviolet light with an excitation wavelength of 355 nm and an emission wavelength of 460 nm. In the re-imaged picture, the difference in grayscale values ​​combined with the different degrees of fluorescence can distinguish between hot and non-hot areas.

[0067] The biomass wood ash used in this experiment was sourced from Beihai Hepu Annong Co., Ltd., and its pH value was 11.78.

[0068] The test crops in this implementation are soybean, the variety is Guixia No. 7; corn, the variety is Zhengdan 958.

[0069] The Bradyrhizobium G94 tested in this implementation is classified and named Bradyrhizobium centrosematis, and is deposited in Guangdong Provincial Microbial Culture Collection Center. The deposit date is August 14, 2023, the deposit number is GDMCC.No: 63598, and the deposit address is 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou.

[0070] Each root box was filled with 2.5 kg of soil, and air-permeable drainage pipes were installed on both sides of the root box. Sterile water was used to irrigate the root box to about 70% ± 5% of the field water holding capacity by weighing method, and the seed was placed in a walk-in incubator for pre-culture for two weeks. Before the seeds were germinated, they were first soaked in 75% alcohol for 30 seconds and 1% sodium hypochlorite solution for 10 minutes to sterilize the seeds. After being rinsed with sterile water, they were placed in a sterilized container and covered with gauze. Sterile water was sprayed to keep the gauze moist, and then the container was placed in a 28°C incubator for 48 hours for germination. Seeds with the same germination degree were selected and sown along the root window surface at a depth of about 1 cm, and then the transparent surface of the root box was placed downward, and the transparent surface was sealed with tin foil to keep it in a dark environment, and cultured at an angle of 45° to allow the roots to grow along the transparent root window surface. The soil moisture content was controlled at 70% ± 5% of the field water holding capacity by weighing method. The temperature of the walk-in incubator was set at 28℃ during the day and 22℃ at night to simulate the growth environment. The light intensity was 600uMol during the day and the humidity was 65%. No fertilizer was applied to all treatments, and the management measures were the same for each treatment. Destructive sampling was performed after 30 days to measure relevant indicators.

[0071] In the experiment, a blank control group (NS), acid stress (AS), inoculation of Bradyrhizobium G94 (AS+B) under acid stress, and inoculation of Bradyrhizobium G94 (NS+B) under no stress were set up respectively, and each treatment was repeated 3 times, and the inoculation amount was 2% (w / w) (i.e., the amount of bacterial liquid per 100g of air-dried soil was 2mL). The blank control group without stress soil was: 2% biomass wood ash was applied to the acid stress soil to adjust the pH of the strongly acidic soil to 6.7.

[0072] 1. Bradyrhizobium G94 improves soil microecology

[0073] The results are as follows Figure 8 As shown, inoculation with Bradyrhizobium G94 (AS+B) under acid stress significantly increased the pH of soil in non-thermal zones of corn and soybean by 2.73% and 2.27%, respectively, while there was no significant difference in soil in the hot zone; inoculation with bacteria without stress significantly reduced the pH of soil in the hot zone of corn, but had no significant effect on soil in the hot zone of soybean. Inoculation with bacteria G94 under acid stress treatment can significantly reduce the total amount of exchangeable acid in soil in hot zones of corn and soybean by 10.72% and 11.1%, respectively, and there is a decreasing trend in soil in non-thermal zones, but it did not reach a significant level; inoculation with G94 under no stress treatment had no significant effect on the total amount of exchangeable acid in soil in hot and non-thermal zones of corn and soybean. Inoculation with bacteria G94 under acid stress treatment increased the exchangeable pH of soil in hot and non-thermal zones of corn. + content, but significantly reduced the soil H + The content of Al in the soil of maize and soybean in the hot zone was reduced by 14.28%. Under no stress treatment, there was no significant difference between the hot zone and non-hot zone soils after inoculation of G94. Under acid stress treatment, inoculation of G94 significantly reduced the exchangeable Al content of maize and soybean in the hot zone soil3+ The contents decreased by 13.9% and 9.62% respectively, and had no significant effect on the non-heat zone soil. Under the non-stress treatment, inoculating with G94 had no significant effect on the exchangeable Al in the heat zone and non-heat zone soils of both crops. 3+ There was no significant effect.

[0074] 2. Rhizobium lentis G94 promotes crop growth under acid stress

[0075] As shown in Table 3, through three-way ANOVA, it can be seen that the three factors of crop type, whether inoculated with Rhizobium lentis G94, and the presence or absence of acid stress, as well as some of their interactions, had significant effects on the fresh weight and dry weight of the above-ground parts and roots; among them, the three factors and their interactions all had significant effects on the dry and fresh weights of the roots.

[0076] Table 3 Effect test of the interaction of treatments on the biomass of different crops

[0077]

[0078]

[0079] Note: * indicates 0.01 < p < 0.05, ** indicates 0.001 < p < 0.01, *** indicates p < 0.001, NS indicates p > 0.05.

[0080] The results are as Fig. 9As shown in the figure, in corn and soybean, compared with the non-stress treatment, acid stress treatment significantly reduced the aboveground fresh weight, and inoculation of Bradyrhizobium G94 significantly increased the aboveground fresh weight of plants compared with the non-inoculated treatment, regardless of whether it was under acid stress or non-stress conditions. For corn, compared with the non-stress treatment, acid stress treatment significantly reduced the aboveground fresh weight by 136.8%, while inoculation significantly increased by 101.3% under acid stress treatment and 27.9% under non-stress treatment; for soybean, compared with the non-stress treatment, acid stress treatment significantly reduced the aboveground fresh weight by 67.9%, while inoculation significantly increased by 31.5% under acid stress treatment and 12.02% under non-stress treatment. For the aboveground dry weight, inoculation of Bradyrhizobium G94 significantly increased the aboveground dry weight of plants compared with the non-inoculated treatment, regardless of whether it was under acid stress or non-stress conditions. In corn, a fibrous root crop, the aboveground dry weight was significantly reduced by 100.22% under acid stress compared with the non-stress treatment, and the inoculation increased by 74.38% under acid stress, and increased by 21.84% under non-stress treatment; in soybean, a taproot crop, the aboveground dry weight was significantly reduced by 70.34% under acid stress compared with the non-stress treatment, and the inoculation increased by 55.3% under acid stress, and increased by 11.73% under non-stress treatment. It is worth noting that the positive effect of inoculation with Bradyrhizobium G94 on the aboveground dry and fresh weight of the two different types of crops under acid stress treatment was greater than that under non-stress treatment, and corn responded more to stress than soybean, indicating that the strain played a greater role under adversity than under non-adversity, and the inoculation increased the stress resistance of the two crops, with corn being higher than soybean.

[0081] In the case of no inoculation with Bradyrhizobium, acid stress treatment significantly reduced the fresh and dry weights of the roots of both crops compared with non-stress treatment, while inoculation with Bradyrhizobium G94 increased the fresh and dry weights of the roots under both acid stress and non-stress conditions. Specifically, for maize, compared with non-stress treatment, acid stress treatment significantly reduced the fresh and dry weights of the roots by 102.75% and 113.15% respectively, while inoculation with Bradyrhizobium G94 under acid stress treatment significantly increased the fresh and dry weights of the roots by 99.2% and 122.9% respectively, basically restoring to the non-stress level. Inoculation with the bacteria under non-stress treatment significantly increased the fresh and dry weights of the roots by 14.63% and 11.37% respectively; for soybean, compared with non-stress treatment, acid stress treatment significantly reduced the fresh and dry weights of the roots by 71.03 and 32.39% respectively, while inoculation with Bradyrhizobium G94 under acid stress treatment significantly increased the fresh and dry weights of the roots by 39.37% and 26.32% respectively. Inoculation with the bacteria under non-stress treatment significantly increased the fresh and dry weights of the roots by 23.2% and 4.28% respectively; similar to the dry and fresh weights of the above-ground parts, the positive effects of inoculation with Bradyrhizobium G94 on the dry and fresh weights of the roots of the two different types of crops under acid stress were greater than those of inoculation with the bacteria under non-stress treatment.

[0082] 3. Bradyrhizobium G94 Promotes Nutrient Accumulation in Crops under Acid Stress

[0083] As shown in Table 4, three-factor variance analysis showed that acid stress, whether inoculated with bacteria, different crop types and their interactions had significant effects on the total nitrogen, total carbon and total phosphorus in the above-ground parts and roots of plants.

[0084] Table 4 Effect Test of Interaction of Treatments on Nutrients of Different Crop Plants

[0085]

[0086] Note: * indicates 0.01 < p < 0.05, ** indicates 0.001 < p < 0.01, *** indicates p < 0.001, NS indicates p > 0.05.

[0087] The results are as Fig.10As shown in the results, under acid stress, compared with the non-stress treatment, the TN accumulation, TC accumulation and TP content of the aboveground and root of maize showed a downward trend, decreasing by 26.29%, 36.19%, 44.69% and 30.02%, 41.05%, 181.81%, respectively. The decrease in TC accumulation in both the aboveground and root systems was higher than that in TN accumulation, reaching a significant level. Inoculation with Bradyrhizobium G94 significantly increased the TN accumulation, TC accumulation and TP content of the root system under both acid stress and non-stress treatment levels, but only under non-stress treatment did inoculation have a significant effect on the TN accumulation, TC accumulation and TP content of the aboveground, while inoculation had no significant effect on the TN accumulation, TC accumulation and TP content of the aboveground under acid stress treatment. Under the acid stress treatment level, inoculation increased the accumulation of TN, TC and TP content in the root system by 95.4%, 115.83% and 171.71% respectively, and under the non-stress treatment level, inoculation increased the accumulation of TN, TC and TP content in the root system by 49.57%, 51.17% and 15.42% respectively. The positive effect of inoculation under acid stress treatment was greater than that under non-stress treatment. Under non-stress treatment level, inoculation increased the accumulation of TN and TC in the aboveground part by 63.31% and 55.43% respectively, but reduced the content of TP. Compared with the non-stress treatment, acid stress treatment reduced the accumulation of TC and TP content in the aboveground part and root system of soybean, but had no significant effect on TN accumulation. Inoculation with Bradyrhizobium G94 under acid stress treatment significantly increased TC accumulation, TP content in the aboveground part of soybean and TN accumulation, TC accumulation in the root system by 29.2%, 211.21%, 21.64% and 24.38%, respectively. Inoculation with Bradyrhizobium G94 under no stress treatment only significantly increased TC accumulation, TP content in the aboveground part and TN accumulation in the root system by 20.37%, 142.42% and 28.28%, respectively, and had no significant effect on TN accumulation in the aboveground part and TC accumulation, TP content in the root system.

[0088] The above description is only illustrative rather than restrictive of the present invention. Those skilled in the art will understand that many modifications, changes or equivalents may be made without departing from the spirit and scope defined by the appended claims, but all will fall within the scope of protection of the present invention.

Claims

1. Application of Bradyrhizobium G94 in acidic soil improvement. The Bradyrhizobium G94 is deposited in Guangdong Provincial Microbial Culture Collection Center, with a preservation date of August 14, 2023, a preservation number of GDMCC.No: 63598, and a preservation address of 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou.

2. The use of Bradyrhizobium G94 in acidic soil improvement according to claim 1, characterized in that: The soil improvement is to promote the reduction of the total amount of exchangeable acid in acidic soil.

3. The use of Bradyrhizobium G94 in acidic soil improvement according to claim 1, characterized in that: The soil improvement is to promote H + The content is reduced.

4. The use of Bradyrhizobium G94 in acidic soil improvement according to claim 1, characterized in that: The soil improvement is to promote the exchangeable Al 3+ The content is reduced.

5. The application of Bradyrhizobium G94 in promoting crop growth in acidic soil. The Bradyrhizobium G94 is deposited in the Guangdong Provincial Microbial Culture Collection Center, with a preservation date of August 14, 2023, a preservation number of GDMCC.No: 63598, and a preservation address of 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou.

6. The use of Bradyrhizobium G94 in promoting crop growth in acidic soil according to claim 7, characterized in that: The promoting of crop growth is promoting the increase of fresh weight and dry weight of the root system.

7. Application of Bradyrhizobium G94 in regulating crop nutrient accumulation in acidic soil. The Bradyrhizobium G94 is deposited in the Guangdong Provincial Microbial Culture Collection Center, with a preservation date of August 14, 2023, a preservation number of GDMCC.No: 63598, and a preservation address of 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou.

8. The use of Bradyrhizobium G94 in regulating crop nutrient accumulation in acidic soil according to claim 7, characterized in that: The regulation of crop nutrient accumulation is to promote the increase of total nitrogen, total carbon and total phosphorus content in the crop root system.

9. The use of Bradyrhizobium G94 in regulating crop nutrient accumulation in acidic soil according to claim 7, characterized in that: The regulation of crop nutrient accumulation is to promote the increase of total nitrogen and total phosphorus content in the aboveground part of soybeans.

10. The application of Bradyrhizobium G94 in improving the stress resistance of crops. The Bradyrhizobium G94 is deposited in the Guangdong Provincial Microbial Culture Collection Center, with a preservation date of August 14, 2023, a preservation number of GDMCC.No: 63598, and a preservation address of 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou.

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