A compound probiotic fertilizer for regulating the growth of Platycodon grandiflorum and its application

Abstract

The present invention provides a compound probiotic fertilizer for regulating the growth of Platycodon grandiflorum and its application, belonging to the field of microbial fertilizers. The compound probiotic fertilizer is prepared from a microbial inoculant JG-002, Platycodon grandiflorum root exudates, and a carrier. The mass ratio of the microbial inoculant JG-002, Platycodon grandiflorum root exudates, and the carrier is 100:1-5:10-20. The microbial inoculant JG-002 is composed of Bacillus subtilis, Bacillus licheniformis, and Bacillus laterosporus in a viable bacteria number ratio of 5:3:2. The carrier is humic acid, sodium alginate, and calcium chloride, and the mass ratio of humic acid, sodium alginate, and calcium chloride is 3-5:2-3:1-2. The compound probiotic fertilizer in the present invention has a biological antagonistic effect, can effectively inhibit the growth and reproduction of pathogenic microorganisms such as Fusarium in the soil, reduce the incidence of Platycodon grandiflorum root rot, and solve the continuous cropping obstacle.

Description

Technical Field

[0001] The invention belongs to the field of microbial fertilizers, in particular to a composite probiotic fertilizer for regulating the growth of platycodon grandiflorum and application thereof. Background Art

[0002] As an important medicinal plant, Platycodon grandiflorus has long been threatened by continuous cropping and root rot. Traditional continuous cropping leads to an imbalance in the soil microbial flora, which in turn inhibits plant growth and can reduce yields by 30%-50%.

[0003] Continuous planting of Platycodon grandiflorum will lead to a large accumulation of pathogenic microorganisms such as Fusarium spp. in the soil, while the number of beneficial microorganisms such as nitrogen-fixing bacteria and phosphate-solubilizing bacteria will decrease significantly, destroying the balance of soil microbial communities. Studies have shown that in Platycodon grandiflorum fields that have been continuously planted for more than three years, the ratio of fungi / bacteria in the rhizosphere soil increases, which is positively correlated with the occurrence of root rot. Continuous cropping will also lead to a decrease in soil organic matter content, increased compaction, and decreased nutrient utilization efficiency. For example, Platycodon grandiflorum's preference for potassium absorption can easily lead to soil potassium depletion, further affecting the plant's disease resistance.

[0004] At present, solutions to the above problems include crop rotation / fallow and chemical control. However, it takes 2-3 years to restore the soil ecology through crop rotation / fallow, which is a long cycle. A large amount of land cannot be fully utilized, resulting in waste of resources. Although chemical control can inhibit pathogens in the short term, long-term use will cause pathogen resistance, pesticide residues to pollute groundwater, and destroy soil biodiversity. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a composite probiotic fertilizer for regulating the growth of Platycodon grandiflorum, wherein the composite probiotic fertilizer is made of microbial agent JG-002, Platycodon grandiflorum root secretions, and a carrier;

[0006] The mass ratio of the microbial agent JG-002, Platycodon grandiflorum root secretions, and the carrier is 100: 1-5: 10-20;

[0007] The microbial agent JG-002 is composed of Bacillus subtilis (Bacillus subtilis GYH20240327-1), Bacillus licheniformis, and Bacillus laterosporus in a ratio of 5:3:2 in terms of live bacteria count;

[0008] The strain deposit number of the Bacillus subtilis is: CCTCC NO: M2025520, the deposit date is: March 18, 2025; the deposit unit is: China Center for Type Culture Collection; the deposit address is: No. 299, Bayi Road, Wuchang District, Wuhan City, Hubei Province.

[0009] The carrier is humic acid, sodium alginate, and calcium chloride, and the mass ratio of humic acid, sodium alginate, and calcium chloride is 3-5:2-3:1-2.

[0010] Preferably, the preparation method of the Platycodon grandiflorum root exudates is as follows:

[0011] S21. Take sterile Platycodon grandiflorum seedlings and cultivate them in sterilized quartz sand, and supply 1 / 2 Hoagland nitrogen-free nutrient solution for 30-40 days;

[0012] S22. Pull out the Platycodon grandiflorum seedlings together with their roots, rinse the roots with sterile deionized water, collect the rinsing solution, and the rinsing solution contains beneficial substances such as Platycodin D, ferulic acid, and sucrose;

[0013] S23. Filter the rinsing solution through a 200-mesh sieve and concentrate it to 1 / 10 of the original volume to obtain a concentrated solution;

[0014] S24. Freeze-dry the concentrated solution to obtain PRE powder, which is the Platycodon grandiflorum root exudates.

[0015] Preferably, the preparation method of the compound probiotic fertilizer is as follows:

[0016] S31. Dissolve sodium alginate and humic acid in water and stir evenly to form a colloidal solution;

[0017] S32. Uniformly disperse the microbial inoculant JG-002 and the Platycodon grandiflorum root exudates in the colloidal solution to obtain a mixed colloidal solution;

[0018] S33. Drop the mixed colloidal solution into the calcium chloride solution for solidification to form compound probiotic fertilizer particles;

[0019] S34. Dry the compound probiotic fertilizer particles at a temperature below 40°C to obtain the compound probiotic fertilizer.

[0020] Preferably, in step S21, the cultivation environment maintains a temperature of 25±2°C and a light of 16 h / day.

[0021] Preferably, in step S33, the mass concentration of the calcium chloride solution is 2%.

[0022] On the other hand, the present invention provides the application of the above compound probiotic fertilizer for preventing and treating Platycodon grandiflorum root rot, alleviating Platycodon grandiflorum continuous cropping obstacles, and / or promoting Platycodon grandiflorum root development and plant growth.

[0023] Preferably, the compound probiotic fertilizer is mixed with organic fertilizer in a mass ratio of 1:15-25 and then prepared into a compound fertilizer for use. The usage method is as follows: Base application or topdressing during the growth period before sowing Platycodon grandiflorum, and the dosage per mu is 50-100 kg.

[0024] Preferably, the organic fertilizer is a granular organic fertilizer made from crop straws and livestock and poultry manure through fermentation and decomposition.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] 1. The compound probiotic fertilizer in the present invention is composed of Bacillus subtilis, Bacillus licheniformis, and Bacillus laterosporus in a specific proportion, and has a biological antagonistic effect, which can effectively inhibit the growth and reproduction of pathogenic microorganisms such as Fusarium in the soil, reduce the incidence of Platycodon grandiflorum root rot, and effectively solve the problem of continuous cropping obstacle of Platycodon grandiflorum.

[0027] 2. Long-term continuous cropping will lead to the imbalance of soil microbial flora, the reduction of beneficial microorganisms, the enrichment of pathogenic microorganisms, the decrease of soil organic matter content, and the decline of nutrient utilization efficiency. The compound probiotic fertilizer provided by the present invention can increase the number of beneficial microorganisms in the soil, improve the microbial community structure, and alleviate the continuous cropping obstacle; the probiotics in the compound probiotic fertilizer can also decompose organic substances, release nutrients, improve soil fertility, provide sufficient nutrition for the growth of Platycodon grandiflorum, help the roots of Platycodon grandiflorum better absorb nutrients and water, promote root development and plant growth, and thus further alleviate the continuous cropping obstacle.

[0028] 3. The present invention replaces the traditional chemical control method by biological control means, reduces the usage amount of chemical pesticides, and reduces the pollution risk of pesticide residues to the groundwater and soil environment.

[0029] 4. The PRE in the compound probiotic fertilizer provided by the present invention contains beneficial substances such as Platycodin D, ferulic acid, and sucrose, which have a direct promoting effect on the growth of Platycodon grandiflorum and can stimulate root development and plant growth.

[0030] 5. As a chemotactic signal molecule, PRE can form a clear concentration gradient in the rhizosphere soil, enabling the microbial inoculant JG-002 to perceive and respond to this signal, thereby directing the microbial inoculant JG-002 to migrate towards the roots and surrounding areas of Platycodon grandiflorum. This not only increases the number of beneficial microorganisms around the roots but also optimizes the soil microbial community structure, creating a more favorable microecological environment for plant roots.

[0031] 6. PRE can attract microorganisms such as Bacillus to form a close symbiotic relationship with the roots of Platycodon grandiflorum, helping Platycodon grandiflorum more efficiently absorb nutrients and nutrient elements in the soil; at the same time, the aggregation of microorganisms around the roots can also enhance the stress resistance of plants, improve the abilities of drought resistance, cold resistance, and pest and disease resistance, thereby promoting the healthy growth of plants.

[0032] 7. The present invention uses humic acid - sodium alginate to form a colloidal solution, which is loaded with microbial inoculants JG - 002 and PRE, and then dropped into a calcium chloride solution to be solidified into composite probiotic fertilizer granules. This enables the microbial inoculants JG - 002 and PRE to be slowly dissolved and released in the humic acid - sodium alginate form. At the same time, it can reduce the damage of ultraviolet rays and chemical fertilizers to the bacterial cells and PRE, extend the validity period, significantly reduce the fertilization frequency, and improve the utilization rate of the inoculants. Description of the Drawings

[0033] Figure 1 is the yield per mu of three groups of platycodon grandiflorum;

[0034] Figure 2 is the saponin content of three groups of platycodon grandiflorum;

[0035] Figure 3 is the flavonoid content of three groups of platycodon grandiflorum;

[0036] Figure 4 is the number of bacteria measured in the root - zone soil of three groups of platycodon grandiflorum;

[0037] Figure 5 is the number of actinomycetes measured in the root - zone soil of three groups of platycodon grandiflorum;

[0038] Figure 6 is the number of fungi measured in the root - zone soil of three groups of platycodon grandiflorum;

[0039] Figure 7 is the determination result of sucrase in the roots of three groups of platycodon grandiflorum;

[0040] Figure 8 is the determination result of urease in the roots of three groups of platycodon grandiflorum;

[0041] Figure 9 is the determination result of cellulase in the roots of three groups of platycodon grandiflorum;

[0042] Figure 10 is the determination result of protease in the roots of three groups of platycodon grandiflorum;

[0043] Figure 11 is the determination result of catalase in the roots of three groups of platycodon grandiflorum;

[0044] Figure 12 is the number of fusarium in the root - zone soil of three groups of platycodon grandiflorum;

[0045] Figure 13 is the picture of platycodon grandiflorum planted in the JG - 002 group in Experiment 1;

[0046] Figure 14 is the picture of platycodon grandiflorum planted in the PT group in Experiment 1;

[0047] Figure 15 is the picture of platycodon grandiflorum planted in the Pcontrol group in Experiment 1. Specific Embodiments

[0048] In the embodiments, the Bacillus licheniformis used was purchased from Beihai Yiqiang Biotechnology Co., Ltd., the Bacillus laterosporus was purchased from Guangxi Nongbao Bioengineering Co., Ltd., and the Bacillus subtilis was isolated from yogurt.

[0049] Embodiment 1

[0050] A compound probiotic fertilizer for regulating the growth of Platycodon grandiflorum, the compound probiotic fertilizer is made of a microbial inoculant JG-002, Platycodon grandiflorum root exudates, and a carrier;

[0051] The mass ratio of the microbial inoculant JG-002, Platycodon grandiflorum root exudates, and the carrier is 100:1:10;

[0052] The microbial inoculant JG-002 is composed of Bacillus subtilis, Bacillus licheniformis, and Bacillus laterosporus according to the viable count ratio of 5:3:2;

[0053] The preservation number of the Bacillus subtilis strain is: CCTCC NO: M2025520, and the preservation date is: March 18, 2025;

[0054] The carrier is humic acid, sodium alginate, and calcium chloride, and the mass ratio of the humic acid, sodium alginate, and calcium chloride is 3:2:1.

[0055] Moreover, the preparation method of the Platycodon grandiflorum root exudates is as follows:

[0056] S21. Take sterile Platycodon grandiflorum seedlings and cultivate them in sterilized quartz sand, supply 1 / 2 Hoagland nitrogen-free nutrient solution and culture for 30 days;

[0057] S22. Pull out the Platycodon grandiflorum seedlings with roots, rinse the roots with sterile deionized water, and collect the rinsing solution;

[0058] S23. Filter the rinsing solution through a 200-mesh sieve and concentrate it to 1 / 10 of the original volume to obtain a concentrated solution;

[0059] S24. Freeze-dry the concentrated solution to obtain PRE powder, which is the Platycodon grandiflorum root exudates.

[0060] Moreover, the preparation method of the compound probiotic fertilizer is as follows:

[0061] S31. Dissolve sodium alginate and humic acid in water and stir evenly to form a colloidal solution;

[0062] S32. Uniformly disperse the microbial inoculant JG-002 and Platycodon grandiflorum root exudates in the colloidal solution to obtain a mixed colloidal solution;

[0063] S33. Drop the mixed colloidal solution into the calcium chloride solution for solidification to form composite probiotic fertilizer particles;

[0064] S34. Dry the composite probiotic fertilizer particles below 40 °C to obtain the composite probiotic fertilizer.

[0065] Moreover, in the step S21, the cultivation environment maintains a temperature of 25 °C and a light of 16 h / day.

[0066] Moreover, in the step S33, the mass concentration of the calcium chloride solution is 2%.

[0067] Example 2

[0068] A composite probiotic fertilizer for regulating the growth of Platycodon grandiflorum, which is made of a microbial inoculant JG-002, Platycodon grandiflorum root exudates, and a carrier;

[0069] The mass ratio of the microbial inoculant JG-002, Platycodon grandiflorum root exudates, and the carrier is 100:5:20;

[0070] The microbial inoculant JG-002 is composed of Bacillus subtilis, Bacillus licheniformis, and Bacillus laterosporus according to the viable count ratio of 5:3:2;

[0071] The preservation number of the Bacillus subtilis strain is: CCTCC NO: M2025520, and the preservation date is: March 18, 2025;

[0072] The carrier is humic acid, sodium alginate, and calcium chloride, and the mass ratio of humic acid, sodium alginate, and calcium chloride is 5:3:2.

[0073] Moreover, the preparation method of the Platycodon grandiflorum root exudates is as follows:

[0074] S21. Take sterile Platycodon grandiflorum seedlings and cultivate them in sterilized quartz sand, and supply 1 / 2 Hoagland nitrogen-free nutrient solution for 30-40 days;

[0075] S22. Pull up the Platycodon grandiflorum seedlings by the roots, rinse the roots with sterile deionized water, and collect the rinse solution;

[0076] S23. Filter the rinse solution through a 200-mesh sieve and concentrate it to 1 / 10 of the original volume to obtain a concentrated solution;

[0077] S24. Freeze-dry the concentrated solution to obtain PRE powder, which is the Platycodon grandiflorum root exudates.

[0078] Moreover, the preparation method of the composite probiotic fertilizer is as follows:

[0079] S31. Dissolve sodium alginate and humic acid in water and stir evenly to form a colloidal solution;

[0080] S32. Uniformly disperse the microbial inoculant JG-002 and the root exudates of Platycodon grandiflorum in a colloidal solution to obtain a mixed colloidal solution;

[0081] S33. Drop the mixed colloidal solution into a calcium chloride solution for solidification to form composite probiotic fertilizer granules;

[0082] S34. Dry the composite probiotic fertilizer granules below 40 °C to obtain the composite probiotic fertilizer.

[0083] Moreover, in the step S21, the culture environment maintains a temperature of 27 °C and a light of 16 h / day.

[0084] Moreover, in the step S33, the mass concentration of the calcium chloride solution is 2%.

[0085] Example 3

[0086] A composite probiotic fertilizer for regulating the growth of Platycodon grandiflorum, which is made of a microbial inoculant JG-002, root exudates of Platycodon grandiflorum, and a carrier;

[0087] The mass ratio of the microbial inoculant JG-002, the root exudates of Platycodon grandiflorum, and the carrier is 100:3:15;

[0088] The microbial inoculant JG-002 is composed of Bacillus subtilis, Bacillus licheniformis, and Bacillus laterosporus according to the viable count ratio of 5:3:2;

[0089] The preservation number of the Bacillus subtilis strain is: CCTCC NO: M2025520, and the preservation date is: March 18, 2025;

[0090] The carrier is humic acid, sodium alginate, and calcium chloride, and the mass ratio of the humic acid, sodium alginate, and calcium chloride is 4:2.5:1.5.

[0091] Moreover, the preparation method of the root exudates of Platycodon grandiflorum is as follows:

[0092] S21. Take sterile Platycodon grandiflorum seedlings and cultivate them in sterilized quartz sand, and supply 1 / 2 Hoagland nitrogen-free nutrient solution for 35 days;

[0093] S22. Uproot the Platycodon grandiflorum seedlings, rinse the roots with sterile deionized water, and collect the rinsing solution;

[0094] S23. Filter the rinsing solution through a 200-mesh sieve and concentrate it to 1 / 10 of the original volume to obtain a concentrated solution;

[0095] S24. Freeze-dry the concentrated solution to obtain PRE powder, which is the root exudates of Platycodon grandiflorum.

[0096] Moreover, the preparation method of the composite probiotic fertilizer is as follows:

[0097] S31. Dissolve sodium alginate and humic acid in water and stir evenly to form a colloidal solution;

[0098] S32. Uniformly disperse the microbial inoculant JG-002 and platycodon root exudates in the colloidal solution to obtain a mixed colloidal solution;

[0099] S33. Drop the mixed colloidal solution into calcium chloride solution for solidification to form composite probiotic fertilizer particles;

[0100] S34. Dry the composite probiotic fertilizer particles below 40°C to obtain the composite probiotic fertilizer.

[0101] Moreover, in the step S21, the cultivation environment maintains a temperature of 26°C and a light of 16 h / day.

[0102] Moreover, in the step S33, the mass concentration of the calcium chloride solution is 2%.

[0103] Example 4

[0104] Mix the composite probiotic fertilizer prepared in Example 3 with organic fertilizer in a mass ratio of 1:20 to prepare a compound fertilizer.

[0105] Moreover, the organic fertilizer is a granular organic fertilizer made from crop straws and livestock and poultry manure through fermentation and decomposition.

[0106] Experimental part

[0107] Experiment 1

[0108] In Meilihe Town, Yuanbaoshan District, Chifeng City, Inner Mongolia, the same piece of land was selected and three experimental fields were set up to study the effects of different fertilizers on the growth of platycodon. During the period from 2022 to 2024, in April each year, farmyard manure was applied as the base fertilizer to the three experimental fields, and then platycodon was planted. In August, different fertilization treatments were carried out on the three experimental fields: one group was not fertilized as the control group (control), one group was applied with 80 kg / mu of organic fertilizer (PT), and the other group was applied with 80 kg / mu of the composite probiotic fertilizer (JG-002) prepared in Example 4 of the present invention. In October each year, the platycodon was harvested, and the experiment was carried out continuously for three years.

[0109] Among the platycodon samples harvested in 2024, three groups of platycodon were randomly selected for observation. The results of the JG-002 group are as Figure 13 shown, and no symptoms of root rot disease appeared; in contrast, the platycodon in the PT group and the control group showed root rot problems to varying degrees, asFigure 14 and Figure 15 as shown

[0110] In addition, the yield per mu, saponin content, and flavonoid content of three groups of Platycodon grandiflorum were measured and recorded for three consecutive years, and the results are as Figures 1-3 shown in Table 1-3. It can be seen that compared with the PT group and the control group, applying the compound probiotic fertilizer prepared by the present invention (JG-002 group) can significantly promote the growth of Platycodon grandiflorum, improve the yield and quality of Platycodon grandiflorum. Particularly importantly, after three consecutive years of continuous cropping with the compound fertilizer of the present invention, the yield per mu, saponin content, and flavonoid content of Platycodon grandiflorum were not affected and even increased, which fully indicates that the compound fertilizer of the present invention can effectively solve the problem of continuous cropping obstacles of Platycodon grandiflorum.

[0111] Table 1 Results of yield per mu

[0112]

[0113] Table 2 Results of saponin content

[0114]

[0115] Table 3 Results of flavonoid content

[0116]

[0117] Experiment 2

[0118] The numbers of bacteria, actinomycetes, and fungi in the root soil of the three groups of Platycodon grandiflorum in Experiment 1 were measured respectively, and the results are shown in Table 4-6 and Figures 4-6 . The analysis results show that compared with the PT group and the control group, the compound fertilizer provided by the present invention (JG-002 group) can increase the number of beneficial microorganisms in the soil and improve the microbial community structure; the probiotics in the compound fertilizer can also decompose organic substances, release nutrients, improve soil fertility, provide sufficient nutrition for the growth of Platycodon grandiflorum, help the roots of Platycodon grandiflorum better absorb nutrients and water, and promote root development and plant growth.

[0119] At the same time, compared with the Control group and the PT group, after three years of continuous cropping with JG-002 treatment, the numbers of bacteria, actinomycetes, and fungi in the soil all showed a significant improvement trend. This result indicates that the compound fertilizer provided by the present invention can not only effectively increase the number of beneficial microorganisms in the soil, but also help solve the problem of continuous cropping obstacles of Platycodon grandiflorum.

[0120] Table 4 Results of bacteria number measurement

[0121]

[0122] Table 5 Results of actinomycetes number measurement

[0123]

[0124] Table 6 Results of measuring the number of fungi

[0125]

[0126] Experiment 3

[0127] The soil enzyme activities of the three groups of Platycodon grandiflorum roots in Experiment 1 were measured respectively, and the results are shown in Tables 7 - 11 and Figures 7-11 As can be clearly seen, compared with the PT group and the Control group, the activities of sucrase, urease, cellulase, protease and catalase in the JG - 002 group were all significantly increased. This result fully indicates that the compound fertilizer of the present invention can effectively improve the activities of various soil enzymes in the soil of Platycodon grandiflorum roots.

[0128] In addition, further analysis shows that after three years of continuous cropping, compared with the Control group and the PT group, the soil enzyme content in the JG - 002 group did not show a significant decrease, and the activities of some enzymes even showed an increasing trend, further verifying the long - term promotion effect of the compound fertilizer of the present invention on soil enzyme activities and effectively solving the problem of continuous cropping obstacles of Platycodon grandiflorum.

[0129] Table 7 Results of measuring sucrase

[0130]

[0131] Table 8 Results of measuring urease

[0132]

[0133] Table 9 Results of measuring cellulase

[0134]

[0135] Table 10 Results of measuring protease

[0136]

[0137] Table 11 Results of measuring catalase

[0138]

[0139] Experiment 4

[0140] The number of Fusarium in the root soil of the three groups of Platycodon grandiflorum in Experiment 1 was measured respectively, and the results are shown in Table 12 and Figure 12 , analyzing Table 12 and Figure 12According to the data, compared with the PT group and the Control group, the number of harmful Fusarium in the soil of the JG-002 group decreased, proving that the prepared compound fertilizer can effectively inhibit the growth and reproduction of pathogenic microorganisms such as Fusarium in the soil and reduce the incidence of Platycodon grandiflorum root rot. Particularly significantly, after three years of continuous cropping, compared with the Control group and the PT group, the number of Fusarium in the soil of the JG-002 group further decreased. This result indicates that the compound fertilizer of the present invention can not only inhibit the growth and reproduction of Fusarium, reduce the incidence of Platycodon grandiflorum root rot, but also effectively solve the problem of continuous cropping obstacle of Platycodon grandiflorum.

[0141] Table 12 Determination results of Fusarium quantity

[0142]

[0143] In summary, for the Platycodon grandiflorum planted by adopting the technical scheme of the present invention, after three years of continuous cropping, its per mu yield, saponin content, and flavonoid content are all increased compared with the Control group and the PT group. The beneficial bacteria (bacteria, actinomycetes, fungi) in the root system soil are all increased compared with the Control group and the PT group, the harmful bacterium Fusarium decreases, and at the same time, root rot does not occur. It can be proved that the technical scheme of the present invention can effectively prevent and control Platycodon grandiflorum root rot, relieve the continuous cropping obstacle of Platycodon grandiflorum, and promote the root system development and plant growth of Platycodon grandiflorum.

Claims

1. Application of a compound probiotic fertilizer for regulating the growth of Platycodon grandiflorum, characterized in that, The composite probiotic fertilizer is used for preventing and controlling Platycodon grandiflorum root rot, alleviating the continuous cropping obstacle of Platycodon grandiflorum, and / or promoting the root development and plant growth of Platycodon grandiflorum; The composite probiotic fertilizer is made of a microbial inoculant JG-002, Platycodon grandiflorum root exudates, and a carrier; The mass ratio of the microbial inoculant JG-002, Platycodon grandiflorum root exudates, and the carrier is 100: 1-5: 10-20; The microbial inoculant JG-002 is composed of Bacillus subtilis, Bacillus licheniformis, and Bacillus laterosporus according to the viable bacteria count ratio of 5: 3: 2; The strain preservation number of the Bacillus subtilis is: CCTCC NO: M2025520, and the preservation date is: March 18, 2025; The carrier is composed of humic acid, sodium alginate, and calcium chloride, and the mass ratio of the humic acid, sodium alginate, and calcium chloride is 3-5: 2-3: 1-2; The preparation method of the composite probiotic fertilizer is as follows: S1. Dissolve sodium alginate and humic acid in water and stir evenly to form a colloidal solution; S2. Uniformly disperse the microbial inoculant JG-002 and Platycodon grandiflorum root exudates in the colloidal solution to obtain a mixed colloidal solution; S3. Drop the mixed colloidal solution into a calcium chloride solution for solidification to form composite probiotic fertilizer particles; S4. Dry the composite probiotic fertilizer particles at a temperature below 40°C to obtain the composite probiotic fertilizer; The preparation method of the Platycodon grandiflorum root exudates is as follows: (1). Take sterile Platycodon grandiflorum seedlings and cultivate them in sterilized quartz sand, and supply 1 / 2 Hoagland nitrogen-free nutrient solution for 30-40 days; (2). Pull up the Platycodon grandiflorum seedlings together with the roots, rinse the roots with sterile deionized water, and collect the rinsing solution; (3). Filter the rinsing solution through a 200-mesh sieve and concentrate it to 1 / 10 of the original volume to obtain a concentrated solution; (4). Freeze-dry the concentrated solution to obtain PRE powder, which is the Platycodon grandiflorum root exudates.

2. Use of a compound probiotic fertilizer for regulating the growth of Platycodon grandiflorum as claimed in claim 1, characterized in that, In the step (1), the cultivation environment maintains a temperature of 25±2°C and a light of 16 h / day.

3. The application of a compound probiotic fertilizer for regulating the growth of Platycodon grandiflorum as claimed in claim 1, wherein, In the step S3, the mass concentration of the calcium chloride solution is 2%.

4. Use of a compound probiotic fertilizer for regulating the growth of Platycodon grandiflorum as claimed in claim 1, characterized in that, Mix the composite probiotic fertilizer and the organic fertilizer according to a mass ratio of 1: 15-25 and prepare them into a composite fertilizer for use.

5. Use of a compound probiotic fertilizer for regulating the growth of Platycodon grandiflorum as claimed in claim 4, characterized in that, The usage method is as follows: Apply the fertilizer as a base fertilizer before sowing Platycodon grandiflorum or top-dress it during the growth period, and the dosage per mu is 50-100 kg.

6. The application of a compound probiotic fertilizer for regulating the growth of Platycodon grandiflorum as described in claim 5, characterized in that, The organic fertilizer is a granular organic fertilizer made from crop straws and livestock and poultry manure after fermentation and composting.

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