Azospirillum brasilense dr43-29 and its application in preparing seed coating agent and improving drought resistance of crops

Abstract

The application provides a Brazil azotobacter Dr43-29 and application thereof in preparation of seed coating agents and improvement of drought resistance of crops, and belongs to the technical field of microbial function development.The application provides the Brazil azotobacter Dr43-29, the preservation number of which is CGMCC No.35622, and further provides application of the Brazil azotobacter Dr43-29 in crop yield increase, improvement of drought resistance of crops and preparation of seed coating agents.The application provides a seed coating agent and a seed coating method, and the seed coating can significantly improve the biomass and drought tolerance of the plant seedlings, has wide application prospect, and is favorable for popularization and application.

Description

Technical Field

[0001] This invention belongs to the field of microbial functional development technology, specifically involving the Brazilian azospirobacter spirochete Dr43-29 and its application in the preparation of seed coating agents and improving crop drought resistance. Background Technology

[0002] Under the dual pressures of intensifying global climate change and deteriorating arable land quality, abiotic stresses such as drought, salinity, and low temperatures have become core bottlenecks restricting crop yield improvement and quality optimization. Meanwhile, the traditional model of relying on chemical fertilizers and pesticides to enhance crop resistance has led to ecological problems such as soil compaction and rhizosphere microbial imbalance, and the risk of chemical residues in agricultural products is significant, contradicting the strategic goal of green and sustainable agricultural development. Seed coating technology, as a core pretreatment method in modern agriculture, achieves multiple effects such as stress resistance and growth promotion by forming a functional film layer on the seed surface, offering advantages such as ease of use and strong targeting. Among them, bio-coating agents with microorganisms as active ingredients, due to their combined functions of nitrogen fixation, phosphorus solubilization, growth promotion, and enhanced stress resistance, have become an ideal alternative to chemical agents. Their research and application have become a key direction for ensuring food security and promoting agricultural transformation and upgrading.

[0003] Nitrogen-fixing microorganisms convert atmospheric nitrogen into usable nitrogen for crops through biological nitrogen fixation. They also secrete active substances such as auxins and cytokinins, promoting root development and the expression of stress-resistance genes, and have a long history of application in agricultural production. However, existing nitrogen-fixing microbial strains generally suffer from the following drawbacks: First, they have poor stress adaptability; the survival rate of most strains drops sharply under stress environments such as high salinity, drought, and low temperature, making it difficult for them to function stably under extreme conditions. Second, they exhibit strong functional specificity; a single strain usually cannot meet the comprehensive stress resistance requirements of complex field environments. Furthermore, existing strains lack compatibility with seed coating systems, are easily inactivated by excipients in coating agents, resulting in short shelf life and unstable field effects, thus limiting the industrial application of bio-coating agents. Therefore, developing new nitrogen-fixing bacteria and their related preparations for seed coating and improving crop drought resistance has significant practical importance and application value for promoting green and high-yield planting and ensuring sustainable agricultural development. Summary of the Invention

[0004] To address the problems existing in the prior art, the primary objective of this invention is to provide a *Azotobacter brasiliensis* (Brazil *Zynobacterium*). Azospirillum brasiliense Dr43-29, the accession number of the Brazilian azotospirobacter Dr43-29 is CGMCC No. 35622.

[0005] A second objective of this invention is to provide *Azotobacter brasiliensis* (… Azospirillum brasilienseApplications of Dr43-29 in increasing crop yield, improving crop drought resistance, and preparing seed coating agents.

[0006] A third objective of this invention is to provide a seed coating agent, a seed coating method, and its application.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a *Azotobacter brasiliensis* ( Azospirillum brasiliense Dr43-29, the accession number of the Brazilian azotospira Dr43-29 is CGMCC No.35622.

[0008] This invention provides the application of the above-mentioned Azotobacter brasiliensis Dr43-29 in increasing crop yield and / or improving crop drought resistance.

[0009] This invention provides the application of the above-mentioned *Azotrophus brasiliensis* Dr43-29 in the preparation of seed coating agents.

[0010] This invention provides a seed coating agent, comprising, by weight, the following components: 5 parts polyvinylpyrrolidone, 1 part polyvinyl alcohol, 1-3 parts *Azotoxinus brasiliensis* Dr43-29, and 3 parts water; the preservation number of *Azotoxinus brasiliensis* Dr43-29 is CGMCC No. 35622; the viable count of *Azotoxinus brasiliensis* Dr43-29 is 10. 7 ~10 9 cfu / g.

[0011] Preferably, the polyvinylpyrrolidone is any one of polyvinylpyrrolidone K60, polyvinylpyrrolidone K70, and polyvinylpyrrolidone K80; the average degree of polymerization of the polyvinyl alcohol is 2000~2500.

[0012] This invention provides a seed coating method, in which the above-mentioned seed coating agent is used to coat the seed surface.

[0013] Preferably, the mass ratio of the seed coating agent to the seed is 1:(200~300).

[0014] Preferably, the seeds include corn, wheat, rice, soybeans, red beans, black beans, peanuts, cabbage, cucumbers, tomatoes, peppers, kale, rapeseed, and bok choy.

[0015] This invention provides the application of the above-mentioned seed coating agent or coating method in increasing crop yield and / or improving crop drought resistance.

[0016] This invention provides the application of the above-described seed coating agent or coating method in any of the following: (1) Increase the biomass of maize seedlings; (2) Improve the drought tolerance of maize seedlings; (3) Increase rapeseed yield; (4) Improve the drought tolerance of rapeseed; (5) Increase the yield of fast-growing vegetables; (6) Improve the drought tolerance of fast-growing vegetables; (7) Promotes chili pepper growth; (8) Improve the drought tolerance of chili peppers; (9) Promotes eggplant growth; (10) Improve the drought tolerance of eggplant.

[0017] Compared with the prior art, the beneficial effects of the technical solution of the present invention are as follows: This invention has for the first time screened a strain of *Azotobacter brasiliensis* (…). Azospirillum brasiliense Dr43-29 can be used to prepare seed coating agents. Adding this *Azotobacter brasiliensis* to the coating agent can significantly promote crop seedling growth, increase yield and drought tolerance, and has broad application prospects, which is conducive to its promotion and application.

[0018] Biological Preservation Instructions Azotoxinus brasiliensis Dr43-29, classified and named Azotoxinus brasiliensis ( Azospirillum brasiliense (), deposited at: China General Microbiological Culture Collection Center (CGMCC), address: No. 3, No. 1 Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences, accession number: CGMCC No. 35622, deposit date: August 14, 2025. Attached Figure Description

[0019] Figure 1 The classification and identification results of *Azotobacter brasiliensis* Dr43-29; Figure 2 Statistical analysis of growth phenotypes and biomass of maize seeds after seed coating treatment; Figure 3 Statistical analysis of growth phenotypes and biomass of rapeseed seeds after coating treatment; Figure 4 Statistical analysis of growth phenotypes and biomass of *Gnaphalium affine* seeds after seed coating treatment; Figure 5 Growth phenotypes of chili seeds after seed coating treatment; Figure 6 Growth phenotypes and biomass statistics of eggplant seeds after seed coating treatment. Detailed Implementation

[0020] This invention provides a *Azotobacter brasiliensis* ( Azospirillum brasilienseDr43-29, the accession number of the Brazilian azotospira Dr43-29, is CGMCC No. 35622. It was deposited on August 14, 2025 at the China General Microbiological Culture Collection Center (CGMCC), located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences.

[0021] This invention provides the application of *Azotrophus brasiliensis* Dr43-29 in increasing crop yield and / or improving crop drought resistance. Preferably, the application uses *Azotrophus brasiliensis* Dr43-29 as a component of a seed coating agent, thereby promoting seedling growth and improving crop drought resistance. The crops used in this invention preferably include cash crops and vegetables, more preferably including corn, wheat, rice, soybeans, red beans, black beans, peanuts, cabbage, cucumber, tomato, pepper, kale, rapeseed, and fast-growing vegetables.

[0022] This invention provides the application of the above-mentioned *Azotobacter brasiliensis* Dr43-29 in the preparation of seed coating agents, wherein the preferred application is to add a bacterial suspension of *Azotobacter brasiliensis* Dr43-29 to the seed coating agent.

[0023] This invention provides a seed coating agent, comprising, by weight, the following components: 5 parts polyvinylpyrrolidone, 1 part polyvinyl alcohol, 1-3 parts *Azotomyces brasiliensis* Dr43-29, and 3 parts water; preferably, comprising 5 parts polyvinylpyrrolidone, 1 part polyvinyl alcohol, 2 parts *Azotomyces brasiliensis* Dr43-29, and 3 parts water; the *Azotomyces brasiliensis* Dr43-29 has the preservation number CGMCC No. 35622; and the viable count of *Azotomyces brasiliensis* Dr43-29 is 10. 7 ~10 9 cfu / g, preferably 10 8 cfu / g.

[0024] The polyvinylpyrrolidone (PVP) of the present invention is preferably any one of PPVK K60, PPVK K70, and PPVK K80; the average degree of polymerization of the polyvinyl alcohol is preferably 2000-2500.

[0025] This invention provides a seed coating method: coating the seed surface with the seed coating agent described in this invention. The preferred mass ratio of the seed coating agent to the seed is 1:(200~300), more preferably 1:210, 1:220, 1:230, 1:240, 1:250, 1:260, 1:270, 1:280, or 1:290. As an optional embodiment, the seed coating method of this invention involves: selecting uniformly sized, plump, and undamaged corn or vegetable seeds; placing the seeds in the seed coating agent, shaking manually or on a shaker at a speed of 60~120 rpm / min until the seed coating agent evenly coats the seed surface; and then air-drying indoors. The preferred seeds for this invention are corn, wheat, rice, soybean, red bean, black bean, peanut, cabbage, cucumber, tomato, pepper, kale, rapeseed, and fast-growing vegetables.

[0026] This invention provides the application of the above-mentioned seed coating agent or coating method in increasing crop yield and / or improving crop drought resistance. The application includes any one of the following: (1) Increase the biomass of maize seedlings; (2) Improve the drought tolerance of maize seedlings; (3) Increase rapeseed yield; (4) Improve the drought tolerance of rapeseed; (5) Increase the yield of fast-growing vegetables; (6) Improve the drought tolerance of fast-growing vegetables; (7) Promotes chili pepper growth; (8) Improve the drought tolerance of chili peppers; (9) Promotes eggplant growth; (10) Improve the drought tolerance of eggplant.

[0027] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0028] In a specific embodiment of the present invention, the LB liquid culture medium formula is as follows: yeast extract 5g / L, tryptone 10g / L, sodium chloride 10g / L, pH adjusted to 7.0 with NaOH, and autoclaved at 121°C for 20min.

[0029] Unless otherwise specified, the following embodiments are all conventional methods.

[0030] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0031] Example 1 Isolation, purification and identification of Azospirillum brasiliense Dr43-29: 1. Separation: Preparation of soil extract: Weigh 5g of soil sample into a 1000mL Erlenmeyer flask and add 200mL of sterile water to the Erlenmeyer flask; mix the above mixture thoroughly by shaking on a shaker at 37℃ (220rpm, 30min); let the resulting mixture stand for 30min; filter the mixture through a 70μm filter membrane to obtain the soil extract.

[0032] Prepare dilution gradient solutions to determine the optimal dilution concentration. Add 4500µL, 1500µL, 500µL, 167µL, 56µL, and 19µL of soil extract to reagent bottles containing 1L of 10% TSB solution to prepare gradient dilutions of 222×, 666×, 2000×, 6000×, 18000×, and 54000×.

[0033] The diluent was aliquoted into 96-well cell culture plates. In a biosafety cabinet, 160 µL of the diluent was transferred into each well of the 96-well cell culture plate, and each vial of diluent was transferred to three 96-well cell culture plates. A 10% TSB solution without soil extract was transferred to three 96-well cell culture plates as a negative control.

[0034] Incubate the culture plate in the dark for 1 week.

[0035] 2. Purification: The optimal dilution concentration (ODC) was initially determined. After one week, the growth of bacteria in the 96-well cell culture plate was observed. If about 30% of the wells in the 96-well cell culture plate showed visible turbidity, the dilution concentration corresponding to this 96-well cell culture plate was taken as the optimal dilution concentration.

[0036] Prepare sample gradient dilutions. Based on the optimal dilution concentration (ODC) initially determined in the preliminary experiment, prepare 1 / 3×ODC, ODC, and 3×ODC gradient dilutions using 10% TSB solution.

[0037] The diluent was aliquoted into 96-well cell culture plates. In a biosafety cabinet, 160 µL of the diluent was transferred into each well of the 96-well cell culture plate, with each vial being transferred to 30–45 cell culture plates. 10% TSB solution without soil extract was transferred to 3 96-well cell culture plates as a negative control.

[0038] The culture plates were incubated in the dark for 2 weeks.

[0039] Two weeks later, the bacterial growth in the 96-well cell culture plates was observed. Approximately 30% of the wells were retained as visibly turbid 96-well cell culture plates. Using a multipipe, 10 µL of sample was transferred from each well of the retained 96-well cell culture plates into a 96-well PCR plate and stored at -20°C for later bacterial identification.

[0040] 3. Identification: PCR amplification of the hypervariable region V5-V7 of the bacterial 16S rRNA gene was performed using primer pairs 799F and 1193R. The PCR system (20 µL) consisted of: 10 µL 2×PCR Taq Mix (Beijing Bomei Biotechnology Co., Ltd.), 0.4 µL forward primer (5 µM), 0.4 µL reverse primer (5 µM), 0.5 µL DNA template, and 8.7 µL ddH2O. The PCR program was: 95℃ for 30 s pre-denaturation, 55℃ for 30 s annealing, 72℃ for 30 s extension, for 35 cycles. The amplified products were subjected to 1% agarose gel electrophoresis. After confirming the band size to be approximately 400 bp, the PCR products were sequenced. The sequences were compared with known sequences in the GenBank database, and a phylogenetic tree analysis was performed. The results are shown below. Figure 1 As shown. The results confirmed that the purified strain was *Azotobacter brasiliensis* (…). Azospirillum brasiliense It was named *Azotobacter brasiliensis* Dr43-29.

[0041] Azotobacter brasiliensis Dr43-29 was deposited on August 14, 2025, at the China General Microbiological Culture Collection Center (CGMCC), located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences, with accession number CGMCC No. 35622.

[0042] Example 2 A seed coating agent, by weight, comprises the following components: 5 parts polyvinylpyrrolidone, 1 part polyvinyl alcohol, 1 part *Azotoxinus*, and 3 parts water. The *Azotoxinus* is a suspension of *Azotoxinus brasiliensis* Dr43-29 with a viable count of 10-1. 8 cfu / g, polyvinylpyrrolidone is polyvinylpyrrolidone K60; the average degree of polymerization of polyvinyl alcohol is 2000.

[0043] The bacterial suspension was prepared as follows: An appropriate volume (1:1000; v:v) of -80℃ frozen bacterial suspension was inoculated into LB liquid medium; the culture was then incubated overnight at 37℃ / 220 rpm until OD reached [value missing]. 600=0.6~1.0; Centrifuge at 12000 rpm for 5 min to collect bacteria, discard the supernatant; Resuspend the bacterial cells in sterile water, centrifuge at 12000 rpm for 5 min to collect bacteria, discard the supernatant; Resuspend the bacterial cells in sterile water, centrifuge at 12000 rpm for 5 min to collect bacteria, discard the supernatant; The viable count of the bacterial cells resuspended in sterile water is 10. 8 cfu / g.

[0044] Seed coating agent preparation method: Mix the raw materials of each component according to the above ratio to form a paste, and obtain a viscous mixture, which is the seed coating agent.

[0045] Example 3 A seed coating agent, by weight, comprises the following components: 5 parts polyvinylpyrrolidone, 1 part polyvinyl alcohol, 2 parts *Azotoxinus*, and 3 parts water. The *Azotoxinus* is a suspension of *Azotoxinus brasiliensis* Dr43-29 with a viable count of 10-1. 7 cfu / g; polyvinylpyrrolidone is polyvinylpyrrolidone K70; the average degree of polymerization of polyvinyl alcohol is 2000.

[0046] The bacterial suspension was prepared as follows: An appropriate volume (1:1000; v:v) of -80℃ frozen bacterial suspension was inoculated into LB liquid medium; the culture was then incubated overnight at 37℃ / 220 rpm until OD reached [value missing]. 600 =0.6~1.0; Centrifuge at 12000 rpm for 5 min to collect bacteria, discard the supernatant; Resuspend the bacterial cells in sterile water, centrifuge at 12000 rpm for 5 min to collect bacteria, discard the supernatant; Resuspend the bacterial cells in sterile water, centrifuge at 12000 rpm for 5 min to collect bacteria, discard the supernatant; The viable count of the bacterial cells resuspended in sterile water is 10. 7 cfu / g.

[0047] Preparation method: Mix the raw materials according to the above proportions to form a paste, and obtain a viscous mixture, which is the seed coating agent.

[0048] Example 4 A seed coating agent, by weight, comprises the following components: 5 parts polyvinylpyrrolidone, 1 part polyvinyl alcohol, 3 parts *Azotoxinus*, and 3 parts water. The *Azotoxinus* is a suspension of *Azotoxinus brasiliensis* Dr43-29 with a viable count of 10-1. 9 cfu / g; polyvinylpyrrolidone is polyvinylpyrrolidone K80; the average degree of polymerization of polyvinyl alcohol is 2500.

[0049] The bacterial suspension was prepared as follows: An appropriate volume (1:1000; v:v) of -80℃ frozen bacterial suspension was inoculated into LB liquid medium; the culture was then incubated overnight at 37℃ / 220 rpm until OD reached [value missing]. 600=0.6~1.0; Centrifuge at 12000 rpm for 5 min to collect bacteria, discard the supernatant; Resuspend the bacterial cells in sterile water, centrifuge at 12000 rpm for 5 min to collect bacteria, discard the supernatant; Resuspend the bacterial cells in sterile water, centrifuge at 12000 rpm for 5 min to collect bacteria, discard the supernatant; The viable count of the bacterial cells resuspended in sterile water is 10. 9 cfu / g.

[0050] Preparation method: Mix the raw materials according to the above proportions to form a paste, and obtain a viscous mixture, which is the seed coating agent.

[0051] Example 5 A seed coating method: The seed coating agent of Example 2 is used to coat the seed surface, with the preferred mass ratio of seed coating agent to seed being 1:250. Select seeds that are uniform in size, plump, and undamaged. Place the seeds in the seed coating agent and shake on a shaker at 100 rpm / min until the seed coating agent evenly coats the seed surface; then air dry indoors.

[0052] Example 6 A seed coating method: The seed coating agent of Example 3 is used to coat the seed surface, with the preferred mass ratio of seed coating agent to seed being 1:200. Select seeds that are uniform in size, plump, and undamaged. Place the seeds in the seed coating agent and manually shake at 60 rpm / min until the seed coating agent evenly coats the seed surface; then air dry indoors.

[0053] Example 7 A seed coating method: The seed coating agent of Example 4 is used to coat the seed surface, with the preferred mass ratio of seed coating agent to seed being 1:300. Select seeds that are uniform in size, plump, and undamaged. Place the seeds in the seed coating agent and shake on a shaker at 120 rpm / min until the seed coating agent evenly coats the seed surface; then air dry indoors.

[0054] Experimental Example 1 The method of Example 5 was used to coat corn seeds.

[0055] Coated and uncoated corn seeds were used as the experimental and control groups, respectively, and were sown normally. The control group was operated the same as the experimental group except for the untreated seeds. Sowing was carried out in October, with a seed quantity of 6 seeds per pot. Sowing was done by spot sowing at a depth of 1 cm. Before sowing, 0.4 L of water was poured into each pot from the bottom. The pots were 10 cm in diameter and 10 cm in height. The experimental temperature was 15°C at night and 25°C during the day outdoors. Seven days after sowing, the corn seedlings were thinned, leaving 4 seedlings of uniform size per pot for further cultivation. Fourteen days after sowing, half of the corn seedlings were subjected to drought treatment.

[0056] Statistics on growth phenotypes and biomass of maize seeds after seed coating treatment are as follows: Figure 2 The figure shows the growth phenotypes of maize seeds under control and drought conditions (A: uncoated, coated, and drought-treated). Figure B shows the biomass of maize seeds under control and drought conditions (B: uncoated, coated, and drought-treated). Note: Different letters in the figure indicate significant differences (P<0.05). Results showed that under normal culture conditions, the biomass per plant in the control group was 2.425 g, while the biomass per plant after seed coating treatment was 3.027 g, representing a 24.82% increase in fresh weight per seedling compared to the control. Under drought conditions, the biomass per plant in the control group was 0.897 g, while the biomass per plant after seed coating treatment was 1.709 g, representing a 90.52% increase in fresh weight per seedling compared to the control.

[0057] Experimental Example 2 The method of Example 5 was used to coat rapeseed seeds.

[0058] Coated and uncoated rapeseed seeds were used as the experimental and control groups, respectively, and were sown normally. The control group was operated the same as the experimental group except for the untreated seeds. Sowing was carried out in December, with a seed rate of 300g / mu (approximately 200g / acre), uniform broadcasting at a depth of 1cm. The experiment was conducted in a vegetable greenhouse at nighttime temperatures of 15°C and daytime temperatures of 25°C. Fourteen days after sowing, the rapeseed seedlings were thinned, retaining only seedlings of uniform size for further cultivation. Fourteen days after sowing, half of the seedlings were subjected to drought treatment.

[0059] Statistics on growth phenotypes and biomass of rapeseed seeds after coating treatment are as follows: Figure 3As shown in the figure, A represents the growth phenotypes of rapeseed seeds without coating, rapeseed seeds treated with coating agent, and rapeseed seeds under control and drought conditions. B represents the biomass statistics of rapeseed seeds without coating, rapeseed seeds treated with coating agent, and rapeseed seeds under control and drought conditions. Note: Different letters in the figure indicate significant differences (P<0.05). The results showed that under normal culture conditions, the biomass per plant in the control group was 14.76 g, while the biomass per plant after rapeseed seed coating treatment was 20.85 g, representing a 41.26% increase in seedling biomass (fresh weight) compared to the control. Under drought conditions, the biomass per plant in the control group was 5.98 g, while the biomass per plant after rapeseed seed coating treatment was 8.63 g, representing a 44.31% increase in seedling biomass (fresh weight) compared to the control.

[0060] Experimental Example 3 The method of Example 5 was used to coat the seeds of *Gnaphalium affine*.

[0061] Coated and uncoated *Gnaphalium affine* seeds were used as the experimental and control groups, respectively, and were sown normally. The control group was operated the same as the experimental group except for the untreated seeds. Sowing was carried out in December, with a seed rate equivalent to 300g / mu (approximately 200g / acre), using uniform broadcasting at a depth of 1cm. The experiment was conducted in a greenhouse with nighttime temperatures of 15°C and daytime temperatures of 25°C. Fourteen days after sowing, the seedlings were thinned, retaining only those of uniform size for further cultivation. Fourteen days after sowing, half of the seedlings were subjected to drought treatment.

[0062] The growth phenotype and biomass statistics of *Gnaphalium affine* seeds after seed coating treatment are as follows: Figure 4 As shown in the figure, A represents the growth phenotypes of uncoated and seed-coated *Hylocereus undatus* seeds under control and drought conditions. B represents the biomass statistics of uncoated and seed-coated *Hylocereus undatus* seeds under control and drought conditions. Note: Different letters in the figure indicate significant differences (P<0.05). The results showed that under normal culture conditions, the biomass per plant in the control was 18.50 g, while the biomass per plant after seed coating treatment was 28.58 g, representing a 54.49% increase in seedling biomass (fresh weight) compared to the control. Under drought conditions, the biomass per plant in the control was 4.50 g, while the biomass per plant after seed coating treatment was 10.27 g, representing a 128.22% increase in seedling biomass (fresh weight) compared to the control.

[0063] Test Example 4 The method in Example 5 was used to coat the chili seeds.

[0064] Coated and uncoated chili seeds were used as the experimental and control groups, respectively, and were sown normally. The control group was operated the same as the experimental group except for the seeds not being treated. Sowing was carried out in December, with a seed rate equivalent to 300g / mu (approximately 200g / acre). Sowing was done by uniform broadcasting at a depth of 1 cm. The experiment was conducted in a vegetable greenhouse with nighttime temperatures of 15°C and daytime temperatures of 25°C. Fourteen days after sowing, the chili seedlings were thinned, and those of uniform size were transplanted. Fourteen days after sowing, half of the seedlings were subjected to drought treatment.

[0065] The growth phenotype of pepper seeds after seed coating treatment is as follows Figure 5 As shown in the figure, A represents the growth phenotypes of uncoated and coated chili seeds under control conditions. B represents the growth phenotypes of uncoated and coated chili seeds under drought conditions. The results show that seed coating treatment promotes chili plant growth under both normal culture conditions and drought conditions.

[0066] Experimental Example 5 Eggplant seeds were coated using the method described in Example 5.

[0067] Eggplant seeds treated with coating and those without coating were used as the experimental and control groups, respectively, and were sown normally. The control group was operated the same as the experimental group except for the seeds not being treated. Sowing was carried out in December, with a seed rate equivalent to 300g / mu (approximately 200g / acre), using uniform broadcasting at a depth of 1cm. The experiment was conducted in a greenhouse with nighttime temperatures of 15°C and daytime temperatures of 25°C. Fourteen days after sowing, the eggplant seedlings were thinned, and seedlings of uniform size were transplanted. Fourteen days after sowing, half of the eggplant seedlings were subjected to drought treatment.

[0068] Statistics on growth phenotypes and biomass of eggplant seeds after seed coating treatment are as follows: Figure 6As shown in the figure, A represents the growth phenotype of eggplant seeds under control conditions (uncoated and seed-coated). B represents the growth phenotype of eggplant seeds under drought conditions (uncoated and seed-coated). C represents the fruit growth phenotype of eggplant seeds under control and drought conditions (uncoated and seed-coated). D represents the yield data of eggplant seeds under control and drought conditions (uncoated and seed-coated). Note: Different letters in the figure indicate significant differences (P<0.05). The results showed that under normal cultivation conditions, the yield per plant in the control was 0.62 kg, while the yield per plant after seed coating treatment was 0.92 kg, representing a 48.39% increase compared to the control. Under drought conditions, the yield per plant in the control was 0.42 kg, while the yield per plant after seed coating treatment was 0.70 kg, representing a 66.67% increase compared to the control. The results showed that seed coating treatment promoted eggplant plant growth under both normal culture conditions and drought treatment conditions.

[0069] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A species of *Azotobacter brasiliensis* ( Azospirillum brasiliense Dr43-29, characterized in that, The accession number of the Brazilian azospira Dr43-29 is CGMCC No. 35622.

2. The application of the *Azotrophus brasiliensis* Dr43-29 as described in claim 1 in increasing the yield of rapeseed, kale, or eggplant, and / or improving the drought resistance of corn, rapeseed, kale, pepper, or eggplant.

3. The application of *Azotrophus brasiliensis* Dr43-29 as described in claim 1 in the preparation of a seed coating agent, characterized in that... The seed coating agent is a seed coating agent for corn, rapeseed, Chinese cabbage, pepper, or eggplant.

4. A seed coating agent, characterized in that, The product comprises, by weight, the following components: 5 parts polyvinylpyrrolidone, 1 part polyvinyl alcohol, 1-3 parts *Azotoxinus brasiliensis* Dr43-29, and 3 parts water; the preservation number of *Azotoxinus brasiliensis* Dr43-29 is CGMCC No. 35622; the viable count of *Azotoxinus brasiliensis* Dr43-29 is 10. 7 ~10 9 cfu / g.

5. The seed coating agent according to claim 4, characterized in that, The polyvinylpyrrolidone is any one of polyvinylpyrrolidone K60, polyvinylpyrrolidone K70 and polyvinylpyrrolidone K80; the average degree of polymerization of the polyvinyl alcohol is 2000~2500.

6. A method for coating seeds, characterized in that, The seed coating agent according to any one of claims 4 to 5 is used to coat the surface of the seed, wherein the seed is the seed of corn, rapeseed, Chinese cabbage, chili pepper or eggplant.

7. The coating method according to claim 6, characterized in that, The mass ratio of the seed coating agent to the seed is 1:(200~300).

8. The application of the seed coating agent according to any one of claims 4 to 5 or the coating method according to any one of claims 6 to 7 in increasing the yield of rapeseed, Chinese cabbage or eggplant, and / or improving the drought resistance of corn, rapeseed, Chinese cabbage, pepper or eggplant.

9. The application of the seed coating agent according to any one of claims 4-5 or the coating method according to any one of claims 6-7 in any of the following: (1) Increase the biomass of maize seedlings; (2) Improve the drought tolerance of maize seedlings; (3) Increase rapeseed yield; (4) Improve the drought tolerance of rapeseed; (5) Increase the yield of fast-growing vegetables; (6) Improve the drought tolerance of fast-growing vegetables; (7) Promotes chili pepper growth; (8) Improve the drought tolerance of chili peppers; (9) Promotes eggplant growth; (10) Improve the drought tolerance of eggplant.

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