Nielsenella with plant growth-promoting rhizosphere effects and its applications

Abstract

The present invention belongs to the field of microbial technology, and particularly relates to the Nielsonia bacteria with plant rhizosphere growth-promoting effects and its applications. The strain is Niallia nealsonii BN5, and the preservation number is CGMCC No. 31380. The Nielsonia bacteria BN5 provided by the present invention has a wide growth temperature range, is easy to adapt to various soil environments, and has characteristics such as phosphorus solubilization and IAA production; the present invention provides a new method for promoting plant growth in crop production, which helps to improve the yield and quality of crops, and at the same time promotes the development of sustainable agriculture. This technology is not limited to cucumbers, but can also be applied to the cultivation of other crops, bringing important technological progress and economic benefits to modern agricultural production; it has broad application prospects and is suitable for the sustainable development and production optimization of modern greenhouse agriculture.

Description

Technical Field

[0001] The present invention belongs to the technical field of microbiology, and particularly relates to a strain of Nilsonia ( Niallia nealsonii BN5) with plant rhizosphere growth-promoting effect and its application. Background Art

[0002] Nilsonia ( Niallia nealsonii ) is a member of the genus Bacillus and is usually widely present in natural environments, including soil, water bodies, and inside plants.

[0003] In agricultural production, especially in the field of greenhouse crop cultivation, improving crop yield and quality has always been an important research direction. Traditional agriculture relies on chemical fertilizers to promote crop growth, but long-term use has brought many problems such as soil compaction and environmental pollution. Therefore, it is crucial to seek green and environmentally friendly and effective growth-promoting methods. As a new type of fertilizer, microbial fertilizers have received extensive attention. PGPR plays an important role in protected agriculture and can directly or indirectly promote plant growth through various mechanisms. They can produce plant growth hormones, such as auxin, gibberellin, and cytokinin, etc., stimulate plant cell division and elongation, and promote root growth and plant development 。

[0004] Due to the wide variety of biogenic substances and the fact that the effects of growth-promoting bacteria are easily affected by environmental conditions, the growth-promoting effects of current growth-promoting bacteria in crop cultivation are not ideal. Summary of the Invention

[0005] The purpose of the present invention is to provide a strain of Nilsonia ( Niallia nealsonii BN5) with plant rhizosphere growth-promoting effect in view of the deficiencies of existing research.

[0006] Another purpose of the present invention is to provide the application of the above-mentioned Nilsonia in promoting crop growth.

[0007] To achieve the above purposes, the technical solutions adopted by the present invention are as follows:

[0008] The present invention provides a strain of Nilsonia with plant rhizosphere growth-promoting effect, and this strain is Niallia nealsonii BN5, with the preservation number of CGMCC No. 31380, preserved in the China General Microbiological Culture Collection Center, and the preservation date is July 22, 2024.

[0009] The present invention also provides the application of the above-mentioned Nilsonia in promoting crop growth.

[0010] Another purpose of the present invention is to provide a crop growth promoter prepared by using the above-mentioned Nilsonia.

[0011] Preferably, the crop growth promoter contains a culture of Nielsonia, a culture concentrate, a culture bacterial suspension or its volatile organic compounds (VOC).

[0012] The Nielsonia provided by the present invention ( Niallia nealsonii BN5) has the ability to decompose phosphorus and produce IAA.

[0013] For the proximal and distal treated roots of Arabidopsis thaliana, the fresh weights increased by 135.29% and 82.35% respectively, and the main root length was significantly increased, and the number of lateral roots was significantly increased, indicating that BN5 has a strong promoting effect on roots. Through specific analysis of its underground part, it was found that after exogenous addition of BN5 for proximal and distal treatments, the main root length increased by 12.22% and 27.52% respectively, the number of lateral roots increased by 683.33% and 600.00% respectively, the root surface area increased by 58.18% and 62.26% respectively, and the density increased by 533.86% and 196.75% respectively.

[0014] After exogenous addition of Nielsonia BN5, the growth of cucumber seedlings was significantly higher than that of the control group. The above-ground fresh weight increased by 34.10%, the underground fresh weight increased by 288%, and the number of root tips was significantly increased, indicating a stronger promoting effect on roots. Through specific analysis of its underground part, it was found that after exogenous addition, the main root length increased by 40.95%, the number of root tips increased by 78.49%, the root area increased by 30.87%, and the total root surface area increased by 12.37%.

[0015] After indirect regulation of cucumber by Nielsonia BN5, the growth of crop seedlings was significantly higher than that of the control group. The above-ground fresh weight increased by 169.23%, the underground fresh weight increased by 876.19%, indicating a stronger promoting effect on roots. Through specific analysis of its underground part, it was found that after exogenous addition, the main root length increased by 13.31%, the number of root tips increased by 50.22%, and the root area increased by 4.39%. The total root surface area, total root volume and average diameter had relatively little impact.

[0016] After applying Nielsonia BN5, the growth of wheat was significantly higher than that of the control group. The above-ground dry weight increased by 23.49%, and the root dry weight increased by 11.48%, indicating a stronger promoting effect on the above-ground part of wheat. Through specific analysis, it was found that after adding BN5, the main root length increased by 21.30%, the stem diameter increased by 27.45%, and the strong seedling index of wheat applied with Nielsonia BN5 was higher than that of the control group.

[0017] The crop growth promoter provided by the present invention, the culture containing Nielsonia bacteria is obtained by inoculating Nielsonia bacteria BN5 into NB liquid medium and culturing it with shaking; the culture containing Nielsonia bacteria is concentrated to obtain the concentrated BN5 culture; the culture containing Nielsonia bacteria is centrifuged, the supernatant is removed, and the bacterial cells are resuspended in sterile water to obtain the BN5 bacterial suspension; Nielsonia bacteria BN5 is inoculated into NB solid medium and cultured statically, and its volatile substances are collected to obtain its volatile substances VOC.

[0018] Furthermore, the culture containing Nielsonia bacteria, the concentrated BN5 culture, and the BN5 bacterial suspension are prepared by the following methods:

[0019] (1) Inoculate a single colony of purified Nielsonia bacteria BN5 into 5 mL of NB liquid medium and culture it overnight until OD≈1.0, and then inoculate it into a new NB liquid medium at an inoculation amount of 5 wt% and culture it at 30 °C with shaking at 180 rpm for 20 - 24 h to obtain the culture containing Nielsonia bacteria;

[0020] (2) Centrifuge the culture containing Nielsonia bacteria, remove the supernatant, leaving only the bacterial cells, and then add sterile water to suspend the bacterial cells to obtain the BN5 bacterial suspension.

[0021] Preferably, the OD 600 value of the culture containing Nielsonia bacteria is 1 - 1.5.

[0022] Preferably, the centrifugation is carried out at 5000 - 7000 rpm for 3 - 5 min.

[0023] Advantages of the present invention:

[0024] (1) In the present invention Niallia nealsonii BN5 is isolated from the rhizosphere soil of greenhouses. It has a wide growth temperature range and is easy to adapt to various soil environments. It has characteristics such as phosphorus solubilization and IAA production;

[0025] (2) The present invention provides a new method for promoting plant growth in crop production, which helps to improve crop yield and quality, and at the same time promotes the development of sustainable agriculture. This technology is not limited to cucumbers, but can also be applied to the cultivation of other crops, bringing important technological progress and economic benefits to modern agricultural production; it has broad application prospects and is suitable for the sustainable development and production optimization of modern greenhouse agriculture.

[0026] Preservation information

[0027] Preservation time: July 22, 2024;

[0028] Preservation unit: General Microbiological Center of China Committee for Culture Collection of Microorganisms;

[0029] Deposit number: CGMCC No. 31380;

[0030] Address of the depositary institution: Institute of Microbiology, Chinese Academy of Sciences, No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing;

[0031] Postal code: 100101;

[0032] Taxonomic nomenclature: Niallia nealsonii . Brief description of the drawings

[0033] Figure 1 It is the electrophoresis detection result of the 16S rRNA PCR amplification product of Nielsenella BN5 provided by the present invention;

[0034] Figure 2 It is the phylogenetic tree of BN5 based on the 16S rRNA sequence homology provided by the present invention;

[0035] Figure 3 It is the growth curve of Nielsenella BN5 at different temperatures provided by the present invention; from top to bottom are 20 °C, 25 °C, 30 °C, 35 °C, 40 °C;

[0036] Figure 4 It is the phosphorus solubilization determination of Nielsenella BN5 provided by the present invention; A: Size of the transparent circle B: Phosphorus solubilization standard curve;

[0037] Figure 5 It is the determination of the IAA production ability of Nielsenella BN5 provided by the present invention; A: Salkowski colorimetric result B: IAA production standard curve;

[0038] Figure 6 It is the diagram of the growth of Arabidopsis thaliana seedlings with exogenous addition of Nielsenella BN5 provided by the present invention; from left to right are CK group, BN5 (proximal), BN5 (distal);

[0039] Figure 7 It is the diagram of the growth of cucumber seedlings with exogenous addition of Nielsenella BN5 provided by the present invention; the left side is the CK group and the right side is BN5;

[0040] Figure 8 It is the diagram of the indirect regulation of cucumber growth with exogenous addition of Nielsenella BN5 provided by the present invention; the left side is the CK group and the right side is BN5;

[0041] Figure 9 It is the diagram of the influence of applying Nielsenella BN5 on the growth of field wheat provided by the present invention; the left side is the CK group and the right side is BN5. Detailed implementation manners

[0042] The present invention will be further explained in combination with the following embodiments, but the embodiments do not limit the present invention in any form.

[0043] In the present invention, a strain was screened from the rhizosphere soil of a greenhouse, Niallia nealsonii , its growth-promoting function was explored, and its influence on the growth of greenhouse crops was also explored. Therefore, screening strains with growth-promoting functions N. nealsonii provides strain resources for related research.

[0044] The NB (Nutrient Broth) medium used in the present invention contains 10.0 g of peptone, 3.0 g of beef extract powder and 5.0 g of sodium chloride, placed in 1 L of water, and the pH is 7.2 ± 0.2.

[0045] Example 1 Niallia nealsonii Isolation and identification of BN5

[0046] 1. Niallia nealsonii Isolation of BN5

[0047] Take 10 g of fresh rhizosphere soil samples from the greenhouse vegetable planting area, put them into a triangular flask containing 90 mL of sterile water and a small amount of glass beads, place it in a constant temperature shaker at 30 °C, and shake and culture at 180 rpm for 30 min to evenly disperse the soil samples in the diluent (sterile water) to make a 10 -1 diluent. Pipette 1 mL of 10 -1 diluent into a glass test tube containing 9 mL of sterile water, shake and mix well to make a 10 -2 diluent. By analogy, continuously dilute until diluted to 10- 7 . Select the soil diluents of three dilution gradients of 10- 5 , 10- 6 , 10- 7 , respectively pipette 100 μL of the diluent and spread it on the NB solid medium (NB liquid medium added with 12 g / L of agar powder) plate, culture at 30 °C for 24 h. After the microbial colonies on the plate grow, select the strains with different colony morphologies, streak and transfer them to the NB solid medium, and culture at 30 °C for 24 h. Continuously streak and purify the culture more than 3 times in this way, microscopically examine its purity until pure culture is obtained, preserve the bacterial solution with 30% glycerol, and store it in a -20 °C refrigerator for standby. A total of 36 strains of bacteria were isolated. By using whether a transparent circle appears around the colonies in the PVK (Pikovskaya) inorganic phosphorus medium (purchased from Beijing Coolaber Technology Co., Ltd.), and the reaction of indole acetic acid with Salkowski reagent showing pink, a strain that can simultaneously decompose phosphorus and produce IAA was finally screened out.

[0048] 2. Niallia nealsonii Identification of BN5

[0049] Inoculate a single colony of purified Nielsonia sp. BN5 into 5 mL of NB liquid medium and culture it overnight until OD≈1.0. Then, inoculate it into a new NB liquid medium at an inoculation amount of 5 wt%, and culture it at 30 °C with shaking at 180 rpm for 24 h. Take the cultured fermentation broth and extract DNA using the Ezup Column Bacterial Genomic DNA Extraction Kit. After DNA extraction, perform PCR amplification on its 16S rDNA.

[0050] Use 16S rRNA amplification primers 27F (SEQ ID NO: 1) and 1492R (SEQ ID NO: 2) as the upstream and downstream primers, Niallia nealsonii and use the total bacterial DNA as the template for PCR amplification. Detect the amplified product by agarose gel electrophoresis.

[0051] As Figure 1 shown, a specific band consistent with the expectation appears at 1000 - 2000 bp, indicating successful 16S rRNA amplification. Send the 16S rRNA PCR product detected by electrophoresis to Shandong Huabo Genetic Engineering Co., Ltd. for sequencing, and compare the sequencing results in GenBank. The sequence is as follows. The results show that through comparison in NCBI, it is inferred that strain BN5 is Nielsonia sp., named Niallia nealsonii BN5, and its phylogenetic analysis is as Figure 2 shown.

[0052] SEQ ID NO:1 AGAGTTTGATCMTGGCTCAG

[0053] SEQ ID NO:2 TACGGYTACCTTGTTACGACTT

[0054] SEQ ID NO:3 BN5 16S rRNA sequence

[0055]

[0056] The above-mentioned separated and purified strain is a strain of Nielsonia bacterium ( Niallia nealsonii BN5), which has been deposited in the General Microbiology Center of the China Microbial Culture Collection Management Committee. The deposit location is No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing. The deposit number is CGMCC NO. 31380, and the deposit date is July 22, 2024.

[0057] Example 2 Determination of the biological properties of Nielsonia bacterium BN5

[0058] 1. Growth curve determination

[0059] Inoculate a single colony of purified Nielsonia bacterium BN5 into 5 mL of NB liquid medium and incubate overnight until OD≈1.0. Inoculate it into a new NB liquid medium at an inoculation amount of 5 wt%, and culture it at 30 °C with shaking at 180 rpm for 24 h to make the BN5 strain in an active state. Inoculate the activated bacterial liquid into 50 mL of NB liquid medium at an inoculation amount of 5 wt%, and culture it at 180 rpm at 20, 25, 30, 35, and 40 °C respectively. Measure the OD value of the bacterial liquid every 2 h 600 until the OD value tends to be stable. Do three parallel groups, and use the blank medium as a control to draw the growth curve. As Figure 3 shown, the BN5 strain reaches the logarithmic phase fastest at 40 °C. At 20 °C, 25 °C, 30 °C, and 40 °C, after reaching the stationary phase, the growth amount of the bacterial cells has no significant difference. However, under the culture condition of 35 °C, after reaching the stationary phase for a period of time, there is a tendency of secondary growth.

[0060] 2. Determination of the ability to dissolve organic phosphorus

[0061] Inoculate a single colony of purified Nielsonia bacterium BN5 into 5 mL of NB liquid medium and incubate overnight until OD≈1.0. Inoculate it into a new NB liquid medium at an inoculation amount of 5 wt%, and culture it at 30 °C with shaking at 180 rpm for 24 h to make the BN5 strain in an active state, and culture it until OD 600 =0.8. Spot inoculate 3 μL of the activated bacterial liquid on the PVK inorganic phosphorus medium, and culture it in a constant temperature incubator at 30 °C for 7 d. Observe and record whether the strain produces a phosphorus-dissolving circle. The size of the phosphorus-dissolving circle can be used as a sign of the strength of phosphorus dissolution. The larger the phosphorus-dissolving circle, the stronger the phosphorus-dissolving ability of the strain. Repeat three times, and the results are as Figure 4Record the diameter (D) of the phosphorus-dissolving circle and the diameter (d) of the colony. The D / d value is 1.22. At the same time, inoculate the activated bacterial liquid into 50 mL of inorganic phosphorus liquid medium at an inoculation amount of 2 wt%, and culture it by shaking at 30 °C and 180 rpm for 7 d. The phosphorus-dissolving amount is determined by the molybdenum-antimony anti-colorimetric method. The curve equation is y = 0.5216x + 0.0003, R 2 = 0.9986, and the phosphorus-dissolving amount is 3.221 ± 0.013 μg / mL.

[0062] 3. Determination of IAA production ability

[0063] Preparation of Salkowski colorimetric solution: Mix 50 mL of 35% concentration HClO4 with 1 mL of 0.5 mol / L FeCl3, place it in a brown bottle, and prepare it freshly for immediate use.

[0064] Inoculate a single colony of purified Nierensenia BN5 into 5 mL of NB liquid medium and culture it overnight until OD≈1.0. Inoculate it into a new NB liquid medium at an inoculation amount of 5 wt%, culture it by shaking at 30 °C and 180 rpm for 24 h, centrifuge at 8000 rpm, wash it with sterile water, and adjust OD 600 = 0.8. Pipette 200 μL of the bacterial liquid and inoculate it into 4 mL of NB liquid medium (containing 1% 200 mg / L L-tryptophan). Use the medium without inoculated bacterial liquid as the blank control. Each treatment is repeated 3 times. Culture it by shaking at 28 °C and 180 rpm for 4 d. After the culture, centrifuge the bacterial liquid at 8000 rpm for 10 min, take 1 mL of the supernatant, add an equal volume of Salkowski colorimetric reagent, and let it stand in the dark for 30 min. Observe the color change. If the color turns red, it is considered to have the ability to produce IAA. The darker the color, the stronger the IAA synthesis ability. The results are as Figure 5 At the same time, measure its absorbance at a wavelength of 530 nm using an ultraviolet-visible spectrophotometer, and calculate the IAA production content by referring to the standard curve. The standard curve is drawn by gradient dilution of the IAA analytical standard. The curve equation is y = 0.0326x + 0.0068, R 2 = 0.9994, and the measured IAA production per unit of BN5 is 8.69 ± 0.11 μg / mL.

[0065] Example 3 Determination of the growth-promoting ability of Nierensenia BN5

[0066] Prepare 0.2 M MS solid medium (MS (MS Medium) medium contains 1.9 g potassium nitrate, 1.65 g ammonium nitrate, 0.17 g potassium dihydrogen phosphate, 0.37 g magnesium sulfate, 0.44 g calcium chloride, 12 g agar powder, etc., placed in 1 L of water, with a pH of 5.7 ± 0.1). Add approximately 25 mL of MS solid medium to each square petri dish. Select Arabidopsis thaliana wild type Columbia - 0 (Col - 0): Disinfect with 2.5% sodium hypochlorite for 3 minutes while shaking constantly, rinse 3 times with sterile water, then disinfect with 70% alcohol for 3 minutes, and rinse the seeds with sterile water, rinsing 3 minutes each time for 3 times. Use a sterile pipette tip to place the disinfected seeds at the 1 / 3 position of the solid medium, place 8 seeds on each plate, air - dry and then seal the plate and place it in a 4°C refrigerator for vernalization for two days.

[0067] Inoculate a single colony of purified Nilssonia sp. BN5 into 5 mL of NB liquid medium and culture overnight until OD≈1.0, then inoculate it into a new 10 mL of NB liquid medium at an inoculation amount of 5 wt% and culture overnight. The next day, centrifuge the cells at 4°C and 7000 rpm, discard the supernatant, and only retain the cells. Add an appropriate amount of sterile water to resuspend the cells to an OD 600 value of 1, and pipette 40 μL and spot it at the 1 / 2 position of the plate. Place the petri dish in a growth chamber at 25 °C for vertical culture, with a light photoperiod of 16 hours and a dark photoperiod of 8 hours, and observe, measure, and take pictures after 10 d.

[0068] The results are as Figure 6 shown. The fresh weights of the proximal - treated and distal - treated roots increased by 135.29% and 82.35% respectively, and the main root length was significantly increased, and the number of lateral roots was significantly increased. This shows that Nilssonia sp. BN5 has a strong promoting effect on roots. Through specific analysis of its underground part, it was found that after exogenous addition of Nilssonia sp. BN5 and proximal and distal treatments respectively, the main root lengths increased by 12.22% and 27.52% respectively, the number of lateral roots increased by 683.33% and 600.00% respectively, the root surface area increased by 58.18% and 62.26% respectively, and the density increased by 533.86% and 196.75% respectively. The growth indexes are shown in Table 1.

[0069] Table 1

[0070]

[0071] Example 4 Verification of the growth - promoting ability of Nilssonia sp. BN5 on cucumber

[0072] 1. Pretreatment of cucumber seeds and Nilssonia sp. BN5 strain

[0073] Pretreatment of cucumber seeds: Cucumber seeds were placed in a water bath at 55 °C. After heat shock for 5 min, they were first surface sterilized with 70% alcohol for 1 min, then surface sterilized with 4% sodium hypochlorite solution for 7 min, and finally rinsed 7 - 8 times with sterile water. Seeds of greenhouse crops were spot inoculated into MS solid medium and cultured in the dark at 25 °C for 2 d.

[0074] Pretreatment of Nielsonia BN5: A single colony of purified Nielsonia BN5 was spot inoculated into 5 mL NB liquid medium and cultured overnight until OD≈1.0. It was then inoculated into fresh NB liquid medium at an inoculation amount of 5 wt%, and cultured with shaking at 30 °C and 180 rpm for 24 h to make Nielsonia BN5 in an active state. 1 mL of the bacterial liquid was taken into a 1.5 mL centrifuge tube, centrifuged at 5000 rpm for 3 min, the supernatant was removed, and the precipitate was thoroughly dispersed and mixed with 1 mL of ddH2O to make the OD600 of the BN5 bacterial suspension ≈1.5.

[0075] 2. Promoting effect of exogenous addition of Nielsonia BN5 on cucumber seedlings

[0076] Cucumber seedlings with a bud length of about 1 cm after the above pretreatment were transplanted into blank MS medium. 5 seedlings were transplanted into each plate, and 120 μL of the BN5 bacterial suspension was dropped onto the roots of the seedlings. They were placed in an illumination incubator and cultured for 14 d (cultured at 26 °C for 16 h under a light intensity of 15000 Lux and at 18 °C for 8 h in the dark), and then the growth indexes of the seedlings were measured. ddH2O was dropped onto the roots of the cucmber seedlings as a control, and three replicates were set for each experiment.

[0077] After exogenous addition of the BN5 bacterial suspension, the growth of cucumber seedlings was significantly higher than that of the control group, as Figure 7 shown. However, the difference in germination rate was small, indicating that Nielsonia BN5 had little effect on the germination of cucumber seeds. The aboveground fresh weight increased by 34.10%, the underground fresh weight increased by 288%, and the number of root tips increased significantly, indicating that the promoting effect on roots was stronger. Specific analysis of its underground part found that after exogenous addition, the main root length increased by 40.95%, the number of root tips increased by 78.49%, the root area increased by 30.87%, and the total root surface area increased by 12.37%. The growth indexes are shown in Table 2.

[0078] Table 2

[0079]

[0080] 3. Promoting effect of the indirect regulation of BN5 on cucumber seedlings

[0081] Take 9 μL of the BN5 bacterial suspension obtained in the above steps and divide it into three drops, which are dropped onto one side of the nutrient agar medium in a Petri dish. After culturing at 30 °C for three days, select cucumber seedlings with a bud length of about 1 cm after pretreatment and transplant them to the other side of the Petri dish containing MS medium. Transfer 2 seedlings into each plate, seal it with a sealing film, and place it in a light incubator for 14 days (cultivate at 26 °C for 16 h under the condition of a light intensity of 15000 Lux and at 18 °C for 8 h under dark conditions), and then measure the growth indexes of the seedlings. Use ddH2O dropped on the side of the nutrient agar medium as a control, and set three parallels for each group of experiments.

[0082] The results are as Figure 8 shown. After the indirect regulation of cucumber by Nierstonia BN5, the growth of cucumber seedlings was significantly higher than that of the control group. The fresh weight of the above-ground part increased by 169.23%, and the fresh weight of the underground part increased by 876.19%, indicating that the promoting effect on the roots was stronger. Through specific analysis of its underground part, it was found that after exogenous addition, the main root length increased by 13.31%, the number of root tips increased by 50.22%, and the root area increased by 4.39%. The total root surface area, total root volume, and average diameter had relatively little influence. The growth indexes are shown in Table 3.

[0083] Table 3

[0084]

[0085] Example 5 Verification of the growth-promoting ability of Nierstonia BN5 on field wheat

[0086] Select wheat seeds suitable for local sowing and sow them in the divided large field plots in Tai'an City, Shandong Province before October 9, 2024. Nierstonia BN5 is cultured and fermented in the laboratory, and the effective viable count reaches 1.03×10 9 CFU / g or more. The BN5 bacterial agent is evenly spread on the crushed peat soil at a ratio of 20%, and then fully stirred evenly with a mixer. The obtained bacterial agent is evenly spread in the large field plots, and the soil is turned over and sown according to the local wheat planting method. Sampling is carried out on November 22, 2024. Take 3 points in each plot, and 2 - 3 plants at each point. Take pictures of the whole wheat plant, measure the stem diameter, root length, number of tillers, plant height, dry the above-ground part and roots respectively to measure the dry weight, and calculate the strong seedling index according to the formula strong seedling index = (stem diameter / plant height + root dry weight / above-ground part dry weight) × whole plant dry weight, with the single application of peat soil as a control.

[0087] The results are as Figure 9As shown, after applying Nilsonia sp. BN5, the growth of wheat was significantly higher than that of the control group. Its above-ground dry weight increased by 23.49%, and the root dry weight increased by 11.48%, indicating that the promoting effect on the above-ground part of wheat was stronger. Through specific analysis, it was found that after adding Nilsonia sp. BN5, the main root length increased by 21.30% and the stem diameter increased by 27.45%. The strong seedling index of wheat applied with Nilsonia sp. BN5 was higher than that of the control group. The specific growth indicators are shown in Table 4.

[0088] Table 4

[0089]

Claims

1. A strain of Nelsonia sp. BN5 having a plant rhizosphere growth-promoting effect, characterized in that: This strain is Niallia nealsonii BN5, deposited with CGMCC No. 31380, was deposited in the General Microbiology Center of China Culture Collection Administration on July 22, 2024; The BN5 16S rRNA sequence is shown in SEQ ID NO.

3.

2. A use of Nelsonia sp. BN5 according to claim 1 in promoting crop growth, characterized in that: The crop is cucumber, Arabidopsis thaliana or wheat.

3. A crop growth promoter prepared using the Nelsonia sp. BN5 as claimed in claim 1.

4. The crop growth promoting agent according to claim 3, characterized in that The crop growth promoting agent contains Nelsonia culture, BN5 culture concentrate, BN5 bacterial suspension or its volatile matter VOC.

5. The crop growth promoting agent according to claim 4, characterized in that The culture containing Nelsonia bacteria is prepared by inoculating Nelsonia bacteria BN5 into NB liquid culture medium and shaking culture; concentrating the culture containing Nelsonia bacteria to obtain BN5 culture concentrate; centrifuging the culture containing Nelsonia bacteria, removing the supernatant, and resuspending the bacteria in sterile water to obtain BN5 bacterial suspension; inoculating Nelsonia bacteria BN5 into NB solid culture medium, statically culturing, and collecting its volatiles to obtain its volatile matter VOC.

6. The crop growth promoting agent according to claim 5, characterized in that The inoculation amount of the Nelsonia sp. BN5 in the NB liquid culture medium or the NB solid culture medium is 5 wt %.

7. The crop growth promoting agent according to claim 5, characterized in that The conditions for shaking culture are: shaking culture at 180 rpm for 20-24 h; the conditions for static culture are: static culture at 30°C for 3-5 d.

8. The crop growth promoting agent according to claim 5, characterized in that The OD of the culture containing Nelsonia 600 The value is 1 to 1.

5.

9. The crop growth promoting agent according to claim 5, characterized in that The centrifugation is carried out at 5000-7000 rpm for 3-5 min.

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