Application of a haloxylon rhizosphere growth promoting bacteria

Abstract

This invention discloses the application of a rhizosphere growth-promoting bacterium of Haloxylon ammodendron, relating to the field of agricultural microbiology technology. The rhizosphere growth-promoting bacterium of Haloxylon ammodendron is *Bacillus belye* (…). Bacillus velezensis SSTB7, deposited at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC No. 38576, dated May 8, 2026, and located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, is used to prepare agricultural microbial agents for the prevention and control of plant fungal diseases, promoting plant growth, and enhancing plant stress resistance. SSTB7 exhibits broad-spectrum and highly effective antifungal activity against apple rot and pepper blight, and also possesses excellent phosphorus-solubilizing, iron-chelating, and salt- and drought-tolerant properties. Field applications have shown that this strain significantly promotes crop root development, enhances crop drought resistance, and substantially increases plant yield, providing excellent microbial germplasm resources for building green agriculture.

Description

Technical Field

[0001] This invention relates to the field of agricultural microbiology, and more specifically, to a rhizosphere growth-promoting bacterium of Haloxylon ammodendron and its application in agriculture. Background Technology

[0002] Plant rhizosphere microorganisms, enriched in the rhizosphere soil, have become the most extensively studied and widely applied microbial groups in soil biomanagement and green agriculture due to their ability to promote soil mineral dissolution and enhance plant tolerance to abiotic stress. Haloxylon ammodendron, mainly distributed in arid desert regions, is characterized by its well-developed root system, tolerance to extreme environments such as -40°C cold, 80°C surface temperatures, and extreme drought, exhibiting exceptional resilience. The rhizosphere of Haloxylon ammodendron is rich in diverse functional microbial communities, which play crucial ecological roles in promoting drought and salinity resistance in the host plant and participating in carbon, nitrogen, and phosphorus cycles. However, the in-depth exploration of Haloxylon ammodendron rhizosphere microbial resources remains insufficient. Therefore, targeted screening from this extreme environment to identify superior rhizosphere growth-promoting strains with multiple functions including disease resistance, growth promotion, and stress resistance has direct and significant practical implications for building a green and sustainable modern agricultural system. Summary of the Invention

[0003] The present invention provides a multifunctional Haloxylon ammodendron rhizosphere growth-promoting strain and its application, which has broad-spectrum antibacterial, highly efficient growth-promoting, and extremely strong stress resistance (salt and drought tolerance). It can solve the technical problems in existing agricultural production caused by the overuse of chemical agrochemical products, resulting in environmental pollution and reduced efficacy, as well as the severe crop yield reduction caused by adverse stresses such as drought and salinity.

[0004] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0005] Application of a rhizosphere growth-promoting bacterium of Haloxylon ammodendron, wherein the rhizosphere growth-promoting bacterium is Bacillus velezensis SSTB7, which has been deposited at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC No. 38576, deposit date of May 8, 2026, and deposit address of No. 3, No. 1 Beichen West Road, Chaoyang District, Beijing;

[0006] The *Haloxylon ammodendron* rhizosphere growth-promoting bacteria or their fermentation broth are used in the preparation of agricultural microbial agents, which have the following combined functions:

[0007] (1) Prevention and control of fungal diseases of plants: The fungal diseases include diseases caused by Phytophthora capsici, diseases caused by Phytophthora aubergina, or diseases caused by Phytophthora aubergina;

[0008] (2) Promote plant growth: Increase plant height, stem diameter, fresh weight and dry weight through inoculation treatment, and promote plant root development to increase total root length, total root surface area and number of root branches; the plants in the plant growth promotion include pepper, melon, strawberry or potato;

[0009] (3) Improve plant stress resistance: under drought stress conditions, improve the drought resistance of plants and increase the fresh weight and dry weight of plants after stress.

[0010] Compared with the prior art, the beneficial effects of the present invention are:

[0011] This invention provides a novel strain of Bacillus velezensis, SSTB7, which possesses strong potential for multiple agricultural applications. Firstly, it exhibits broad-spectrum and highly effective antifungal activity (inhibition rate exceeding 95%) against various major agricultural pathogens, including apple rot fungus and pepper blight fungus, effectively reducing reliance on chemical pesticides. Secondly, it possesses excellent growth-promoting functions such as inorganic phosphorus degradation, iron chelation, and amylase production. In field trials, it significantly promotes root development and substantially increases yields in crops such as peppers, melons, and potatoes (e.g., single-plant yield increase in peppers exceeding 106%). More importantly, SSTB7 maintains vigorous vitality under drought and salinity stress; inoculation with this strain significantly improves crop drought resistance, perfectly solving the three major agricultural challenges of disease, drought, and salinization identified in the background art.

[0012] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, embodiments of the present invention are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0013] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1This is a graph showing the antagonistic activity of strain SSTB7 against 14 tested pathogens in this invention embodiment; where uppercase letters represent controls and lowercase letters represent the corresponding SSTB7 strains; A and a correspond to *Cytospora maliQH2* (apple rot pathogen); B and b correspond to *Cytospora chrysosperma* YSFL4-2 (poplar rot pathogen); C and c correspond to *Fusarium sambucinum* GQGF1-3 (goji berry root rot pathogen); D and d correspond to *Colletotrichum gloeosporioides* CMGF-TJ (strawberry root rot anthracnose pathogen); E and e correspond to *Fusarium oxysporum* CMGF-LD (strawberry root rot pathogen); F and f correspond to *Acrostalagmus luteoalbus* CMGF-A (strawberry root rot fungus); G and g correspond to *Dactylonectria macrodidyma* (strawberry root rot fungus). CMGF-D); H, h correspond to *Diplodia natalensis* LDF (pear stem rot pathogen); I, i correspond to *Botryosphaeria berengerianade* LLW (pear ring rot pathogen); J, j correspond to *Fusarium pseudograminearum* XMJF (wheat stem rot pathogen); K, k correspond to *Verticillium dahlia* MLSHW (potato verticillium dahlia pathogen); L, l correspond to *Phytophthora capsica* SP90 (pepper blight pathogen); M, m correspond to *Fusarium solani* WQ1 (carrot root rot and solanaceous plant rot pathogen); N, n correspond to *Phytophthora infestans* MLSWY (potato late blight pathogen).

[0015] Figure 2 This is a diagram showing the field resistance results of strain SSTB7 to pepper blight in an embodiment of the present invention;

[0016] Figure 3 This is a graph showing the in-plate activity test results of strain SSTB7 in the embodiments of the present invention; wherein, A is the CAS medium complexing iron activity test, B is the inorganic phosphorus solubilizing activity test, C is the starch solubilizing activity test, D is the salt tolerance (10% NaCl) test, and E is the drought tolerance (5% PEG) test.

[0017] Figure 4 This is a comparison diagram of the pot-growing effects of strain SSTB7 on pepper, melon, and strawberry seedlings in the embodiments of the present invention;

[0018] Figure 5This is a comparison image of the root morphology of melons after potted plant treatment, analyzed using a root scanner in an embodiment of the present invention.

[0019] Figure 6 This is a potted plant test result of the drought resistance of strain SSTB7 on chili peppers in an embodiment of the present invention;

[0020] Figure 7 These are comparative photos showing the effect of strain SSTB7 on potato field growth promotion in the embodiments of this invention;

[0021] Figure 8 These are comparative photos showing the effect of strain SSTB7 on promoting the growth of chili peppers in the field, as described in the embodiments of this invention.

[0022] Figure 9 These are plate colony morphology diagram (A) and scanning electron microscope microscopic morphology observation diagram (B) of strain SSTB7 in the embodiments of the present invention.

[0023] Figure 10 This is a phylogenetic tree constructed in this embodiment of the invention based on the 16S rRNA gene and whole genome sequence of the strain to be identified SSTB7 and the reference strain;

[0024] Figure 11 This is a site distribution map of the secondary metabolite synthesis gene cluster of strain SSTB7 based on whole genome sequence prediction in this embodiment of the invention. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0026] This invention provides the application of a rhizosphere growth-promoting bacterium from Haloxylon ammodendron. The strain was isolated from the rhizosphere soil of Haloxylon ammodendron and systematically screened for multifunctional rhizosphere growth-promoting strains with antibacterial, salt-tolerant, drought-tolerant, iron-chelating, phosphorus-solubilizing, growth-promoting, and activity properties through methods such as in-plate activity screening, pot simulation, and field experiments. The strains were accurately classified and identified from morphological and genomic perspectives, in order to lay the foundation for the development of subsequent microbial agents.

[0027] This invention obtained a rhizosphere growth-promoting bacterium of Haloxylon ammodendron through isolation and identification. It was identified as Bacillus velezensis SSTB7 and deposited on May 8, 2026 at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC No. 38576. The deposit address is No. 3, No. 1 Beichen West Road, Chaoyang District, Beijing.

[0028] The following detailed examples illustrate the isolation, identification, and application effects of strain SSTB7. The culture medium and reagent formulations used in these examples are as follows:

[0029] (1) Potato glucose medium (PDA): 200g of potatoes, boiled in small pieces for 20-30 minutes, filtered and brought to a final volume of 1L, 17-20g of agar powder added, dissolved completely, then 20g of glucose added, dispensed and sterilized.

[0030] (2) LB medium: 10.0g peptone, 5.0g yeast powder, 2.0g sodium chloride, 1000mL distilled water, pH 7.0 (18.0g agar powder added to solid LBA medium).

[0031] (3) Monkina phosphate-solubilizing medium (1L): glucose 10.0g, NaCl 0.3g, KCl 0.3g, FeSO4·7H2O 0.03g, (NH4)2SO4 0.5g, MnSO4·7H2O 0.03g, MgSO4·7H2O 0.3g, Ca3(PO4)2 5g, yeast extract 0.4g, distilled water 1000 mL, pH 7.0-7.5.

[0032] (4) CAS solid culture medium (mg / L): Chromium azurite S (CAS) 68.5, hexadecyltrimethylammonium bromide (HDTMA) 72.9, ferric chloride hexahydrate 2.645, sodium dihydrogen phosphate dihydrate 295.25, disodium hydrogen phosphate dodecahydrate 1213.5, ammonium chloride 125, potassium dihydrogen phosphate 37.5, sodium chloride 62.5, agar 9000, pH 6.8±0.1. Weigh 10.87g, heat to boiling and completely dissolve in 1L of distilled water, sterilize at 120℃ for 30min before use.

[0033] The pathogens tested in the embodiments of this invention include: *Cytospora maliQH2* (apple rot pathogen), *Cytospora chrysosperma* YSFL4-2 (poplar rot pathogen), *Fusarium sambucinum* GQGF1-3 (goji berry root rot pathogen), *Colletotrichum gloeosporioides* CMGF-TJ (strawberry root rot anthracnose pathogen), *Fusarium oxysporum* CMGF-LD (strawberry root rot pathogen), *Acrostalagmus luteoalbus* CMGF-A (strawberry root rot pathogen), *Dactylonectria macrodidyma* CMGF-D (strawberry root rot pathogen), *Diplodia natalensis* LDF (pear stem rot pathogen), *Botryosphaeria berenengerianade* LLW (pear ring rot pathogen), and *Fusarium pseudograminearum* (wheat stem rot pathogen). The pathogens of XMJF (Potato Verticillium dahlia MLSHW), Phytophthora capsica SP90 (Pepper Phytophthora), Fusarium solani WQ1 (Carrot Root Rot), and Phytophthora infestans MLSWY (Potato Late Blight) were all provided or isolated and identified by relevant research institutes and agricultural universities.

[0034] I. Isolation and in vitro activity screening of SSTB7, a biocontrol fungicide from the rhizosphere of Haloxylon ammodendron

[0035] 1. Isolation and in vitro antagonistic screening of rhizosphere biocontrol bacteria of Haloxylon ammodendron

[0036] Rhizosphere soil samples were collected from Haloxylon ammodendron production base in Bayannur, Inner Mongolia. Bacteria were isolated from the soil using a stepwise dilution method. The isolated strains were then transferred to LBA medium for purification and culture to obtain single-strain isolates. The antagonistic activity of the isolated strains against 14 pathogenic fungi, including Phytophthora blight of pepper, was determined using the plate confrontation culture method.

[0037] Using pathogenic fungi as indicator bacteria, the antagonistic activity of SSTB7 was determined: A 6mm diameter fungal disc was placed in the center of a PDA plate, and bacteria cultured on LBA medium for 2 days were inoculated 2cm away from both sides of the pathogen. The treatment with only pathogenic fungi inoculation served as a control. Each group was repeated 3 times. All plates were incubated upside down at 28℃. After the control plates were fully covered, the diameter of the lesions was measured, and the average inhibition rate was calculated according to formula (1):

[0038] Average inhibition rate = [1 - (colon radius of treatment group / colony radius of control group)] × 100% (1)

[0039] In-plate antagonism test (see) Figure 1 As shown in Table 1, SSTB7 achieved an in-plate inhibition rate of over 75% against 13 of the 14 tested pathogens, excluding potato late blight. Specifically, the inhibition rate against apple rot (QH2) and poplar rot (YSFL4-2) was above 95%; the inhibition rates against pear brown rot, pear bark rot, strawberry root rot, and potato verticillium wilt ranged from 75% to 90%; and the inhibition rate against pepper causal agent SP90 reached 76.05%. SSTB7 maintained a high inhibition rate against the vast majority of tested pathogens, exhibiting a broad spectrum of inhibition and stable antibacterial effects.

[0040] Table 1. Antagonistic activity of SSTB7 against 14 tested pathogens

[0041]

[0042] 2. In-plate activity assay of SSTB7

[0043] The isolated SSTB7 strains were inoculated onto CAS solid medium (for determining iron complexation activity), Monkina inorganic phosphorus medium (for determining phosphorus solubility activity), and starch-dissolving medium, respectively, and incubated upside down in a 28°C incubator for 7-10 days. Strains with iron complexation and phosphorus solubility abilities formed a clear zone around the colony. The colony diameter d and the clear zone diameter D were observed and recorded, and the phosphorus solubility and iron complexation ability of the strains were calculated using D / d. Simultaneously, the isolated strains were inoculated onto media containing 10% NaCl (salt-tolerant) and 5% PEG (drought-tolerant) using the streak plating method and incubated at 28°C for 3-5 days, during which time growth was observed and recorded.

[0044] The results show (see Figure 3 SSTB7 exhibits iron-chelating, inorganic phosphate-solubilizing, and amylase-producing activities. Its D / d value in CAS medium is 2.48±0.27, and its phosphate-solubilizing activity D / d value is 2.50±0.63. SSTB7 also demonstrates salt and drought tolerance, growing normally in media containing 10% NaCl and 5% PEG.

[0045] II. Identification of strain SSTB7 and prediction of secondary metabolites

[0046] 1. Morphological observation

[0047] The SSTB7 strain to be identified was inoculated onto LBA medium using the streak plating method and incubated at 28°C for 1 day. Colony characteristics were then observed and recorded. Electron microscopy analysis of spore and cell morphology was also performed; see [reference needed]. Figure 9Morphological results showed that SSTB7 colonies had a relatively smooth surface, were yellow in color, and exhibited irregular growth at the edges. Scanning electron microscopy revealed that the bacteria were single rod-shaped cells with distinct surface wrinkles, measuring 2.0–4.0 μm in length and 0.5–1.0 μm in width.

[0048] 2. Molecular biological identification

[0049] Strain SSTB7 was inoculated into LB liquid medium and cultured at 25°C and 180 rpm for 2 days with shaking. 1 mL of fermentation broth was taken, and total DNA was extracted from the strain using the Ezup column-based bacterial genomic DNA extraction kit. The DNA samples were then sent to Beijing Novogene Biotechnology Co., Ltd. for whole-genome next-generation sequencing + PacBio Revio sequencing platform analysis.

[0050] Based on the TYGS online platform, the genomic evolutionary distance between strain SSTB7 and known typical strains was calculated using the genomic BLAST distance method. Based on the minimum evolutionary distance, phylogenetic trees based on 16S rRNA genes and whole genome sequences were constructed using FASTME 2.1.6.1 software. To clarify taxonomic position, the average nucleotide identity (ANI) was calculated using the JSpeciesWS online platform, and digital DNA-DNA hybridization (dDDH) was estimated using the GGDC 3.0 program on the DSMZ platform (the criteria for determining same species were OrthoANI > 95% and dDDH > 70%).

[0051] The results showed that the total genome length of SSTB7 was 4,081,041 bp, the total gene length was 3,664,170 bp, the average gene length was 868 bp, and the GC content was 47.24%. See the phylogenetic tree results (see...). Figure 10 The results showed that strain SSTB7 and Bacillus velezensis FZB42 clustered on the same branch, belonging to the same species (according to current prokaryotic classification standards, Bacillus amyloliquefaciens subsp. plantarum has generally been elevated to a separate species, namely Bacillus velezensis). According to the comparison results from the TYGS database (see Table 2), SSTB7 and Bacillus velezensis FZB42 were most closely related, with an ANIb value as high as 98.74% and a dDDH value of 91%, far exceeding the threshold for species classification, indicating that they belong to the same species. Based on morphological observation and whole-genome sequencing, SSTB7 was finally accurately identified as Bacillus velezensis.

[0052] Table 2. Reference strains and their ANIb and dDDH values ​​compared to SSTB7.

[0053]

[0054] 3. Prediction of SSTB7 secondary metabolites

[0055] The antiSMASH program (Version 7.1.0) was used to predict the secondary metabolite synthesis gene clusters of strain SSTB7 (see [link to antiSMASH program]). Figure 11 (See Table 3). The results showed that 13 secondary metabolite gene clusters were identified in the SSTB7 genome, of which 9 clusters were marked with "High" similarity. These clusters cover major pathways including non-ribosomal peptides (NRPS), polyketides (PKS), terpenes, and siderophores. Highly similar clusters contained sites for the synthesis of fengycin, difficidin, bacillibactin, bacilysin, surfactantin, plantazolicin, and macrolacin H, belonging to lipopeptides, polyketides, siderophores, dipeptides, and ribosomal peptides, respectively. Overall, this genome is rich in NRPS and PKS gene clusters, possessing strong potential for the synthesis of various important secondary metabolites.

[0056] Table 3. Regions identifying secondary metabolites of SSTB7

[0057]

[0058] III. Determination of the pot-grown viability of SSTB7 on various crops

[0059] 1. Determination of the life-promoting effect of SSTB7 on peppers, melons, and strawberries.

[0060] Healthy pepper, melon, and strawberry plants with consistent growth stages were selected for pot viability testing. SSTB7 plants were transferred to LB medium and cultured for 2 days, adjusting OD... 600 The bacterial culture medium was 0.8. Inoculation was performed using the root drenching method, with 30 mL of bacterial solution applied to each pot and covered with a thin layer of soil to ensure sufficient contact between the bacteria and the roots. Each group was repeated 6 times. The control group (CK) was drenched with an equal volume of sterile LB medium. Two weeks after the first inoculation, a second root drenching treatment was performed using the same method. After three weeks of continued cultivation, plant height, root length, fresh weight, and dry weight were measured, and the melon roots were scanned using a root scanner. The strawberry growth index was measured at 15, 30, and 45 days after the first inoculation.

[0061] The results show (see Figure 4(See Tables 4 and 5): SSTB7 significantly promoted the growth of peppers, melons, and strawberries. Specifically, the SSTB7 treatment increased the fresh weight of pepper seedlings by 62.27% and the dry weight by 71.42%; the fresh weight and dry weight of melons increased by 139.8% and 118.18%, respectively. Although the early growth-promoting effect of SSTB7 on strawberries was not as strong as that on peppers and melons, 45 days after treatment, the strawberry plant height, root length, stem diameter, fresh weight, and dry weight were all higher than the control group.

[0062] A root scanner was used to analyze the root system of melons (see [link]). Figure 5 As shown in Table 6, SSTB7 has a significant effect on promoting the growth of melon roots: it significantly increased the total root length, total root surface area, average root diameter, total root volume, and number of root branches (P<0.05). Among them, the total root length, total surface area, total volume, and number of branches were all more than twice that of the control, indicating that SSTB7 can significantly promote root growth and improve crop vigor.

[0063] Table 4. Effects of SSTB7 on the growth promotion of pepper and melon seedlings in pots.

[0064]

[0065] Table 5. Growth-promoting effect of SSTB7 on 'Baozhu' strawberry seedlings.

[0066]

[0067] Note: Different letters indicate significant differences at the same time point (p<0.05).

[0068] Table 6. Effects of different bacterial strains on root growth of potted melons

[0069] 2. Potted plant screening and verification of the drought tolerance of SSTB7 peppers

[0070] Using chili peppers as test plants, the effect of SSTB7 on plant drought tolerance was analyzed. The SSTB7 inoculum solution was prepared as described above, and 30 mL / pot was inoculated into chili pepper seedlings. The control group received an equal volume of sterile LB medium, and the treatment was repeated six times. Drought stress treatment was initiated 3 days later: the drought stress group was irrigated with 30 mL of 5% PEG6000 solution per pot, while the control group received an equal volume of water. Two weeks after the stress treatment, a second root drenching treatment was administered. Growth parameters were measured after three more weeks of cultivation.

[0071] The results show (see Figure 6(See Table 7): Although there were no significant differences in plant height and stem diameter among peppers inoculated with SSTB7, fresh weight and dry weight were significantly increased. After SSTB7 treatment, the fresh weight and dry weight of peppers under drought stress increased by more than 60% compared with the control group under the same drought stress, which fully demonstrates that SSTB7 can significantly improve the drought resistance of crops.

[0072] Table 7. Pot test results of SSTB7's drought tolerance to chili peppers.

[0073]

[0074] Note: Different letters indicate significant differences (p<0.05).

[0075] IV. Verification of the Field Control and Growth-Promoting Functions of SSTB7

[0076] 1. Verification of the field control effect on pepper blight

[0077] To evaluate the field control efficacy of SSTB7 against plant diseases, pepper blight was used as the test target in a plastic greenhouse at the Inner Mongolia Agricultural University experimental field in 2025. Healthy pepper seedlings with uniform growth were selected and, after 7 days of transplanting and cultivation, OD200 was added to each seedling. 600 =0.8% SSTB7 fermentation broth (50 mL / plant). 14 days after inoculation with biocontrol bacteria, inoculate with pepper blight pathogen (concentration of 10). 4 (Spores / mL, 50mL per plant). The experiment included a blank control (CK-) of healthy plants not inoculated with the pathogen, and a positive disease control (CK+) of plants inoculated only with the pathogen but not with biocontrols. Each group was replicated 6 times. All plants were managed uniformly, and observations were recorded 55 days after transplanting. Harvesting took place 80 days after transplanting.

[0078] Field control results (see) Figure 2 The results showed that at 55 days after transplanting, the CK+ treatment, which was only inoculated with the pathogen, had completely shown symptoms and the plants had died; while the treatment inoculated with SSTB7 not only effectively reduced the incidence of disease, but also achieved a plant height of 51.71 cm and a stem diameter of 9.38 mm in the mid-growth stage, with a final yield of 1218 g / plant.

[0079] 2. Verification of the field growth-promoting function of chili peppers and potatoes

[0080] Using chili peppers and potatoes as test plants, the growth-promoting effects of SSTB7 on field crops were determined in a greenhouse. SSTB7 fermentation broth (OD) was inoculated into chili peppers 5 days after transplanting and into potatoes after emergence, respectively. 600 =0.8, 50 mL / plant), the control group was watered with the same amount of sterile water. Two weeks after the first inoculation, the inoculation was repeated. During the growing season, the indicators were measured regularly and the yield was recorded. All data were compared with the control group through analysis of variance to screen out the superior strains with significant stress resistance and growth promotion effects.

[0081] The results show (see Figure 7 , Figure 8 (See Table 8) Under field conditions, SSTB7 significantly promoted plant growth and increased yield. After 50 days of treatment, the potato plant height in the SSTB7 treatment group was 35.38 cm, which was 49.54% higher than that in the control group; the stem diameter increased by 21.39% compared to the control group, and the final yield per plant was 65.06% higher than the control. SSTB7 also showed a strong growth-promoting effect on peppers: after inoculation with SSTB7, the plant height and stem diameter of peppers were significantly higher than those in the control group, and the final pepper yield per plant increased by 11.46%.

[0082] Table 8 Analysis of the growth-promoting effect of greenhouse potatoes

[0083]

[0084] Note: Different letters indicate significant differences (p<0.05).

[0085] In summary, the Bacillus SSTB7 strain provided by this invention is a multifunctional and excellent strain with broad-spectrum antibacterial activity, high stress resistance (salt and drought tolerance), and strong growth-promoting, potassium-solubilizing, and phosphorus-solubilizing activities. It has extremely significant application value in the development of green and sustainable agricultural microbial preparations.

[0086] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. The application of a rhizosphere growth-promoting bacterium of Haloxylon ammodendron, characterized in that, The rhizosphere growth-promoting bacteria of Haloxylon ammodendron are Bacillus belysinus (B. belysinus) Bacillus velezensis SSTB7 has been deposited at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC No. 38576, deposited on May 8, 2026, at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing. The *Haloxylon ammodendron* rhizosphere growth-promoting bacteria or its fermentation broth are used in the preparation of agricultural microbial agents, which have the following combined functions: (1) Prevention and control of fungal diseases of plants: The fungal diseases include diseases caused by Phytophthora capsici, diseases caused by Phytophthora aubergina, or diseases caused by Phytophthora aubergina; (2) Promote plant growth: Increase plant height, stem diameter, fresh weight and dry weight through inoculation treatment, and promote plant root development to increase total root length, total root surface area and number of root branches; the plants in the plant growth promotion include pepper, melon, strawberry or potato; (3) Improve plant stress resistance: under drought stress conditions, improve the drought resistance of plants and increase the fresh weight and dry weight of plants after stress.

Images