Substrate special for potato virus-free breeder's seed cultivation and preparation method thereof

Abstract

The invention relates to a special substrate for potato virus-free breeder's seed cultivation. The special substrate comprises a substrate body and a microbial agent adsorbed on the substrate body, the matrix body comprises an organic component and an inorganic component in a volume ratio of (10-40): (90-60); the total viable count in the matrix body is not less than 2.0 * 10 < 8 > CFU / g. The microbial agent is prepared from bacillus cereus CBBL-18, bacillus paralicheniformis CBJ-7 and bacillus korla CBK-5. The invention further discloses a preparation method of the microbial agent. The substrate disclosed by the invention can efficiently promote the growth of potatoes, is disease-resistant and low in cost, and has important significance on promoting green and sustainable development of agriculture while promoting resourceful treatment of solid wastes.

Description

Technical Field

[0001] The present invention relates to the technical field of resource and environmental protection, and particularly relates to a special substrate for cultivating virus-free potato minitubers and a preparation method thereof. Background Art

[0002] Potato is the fourth largest food crop in the world and is an important food, vegetable and industrial raw material. Its cultivation is of great significance for increasing farmers' income and food security. Potato is a tuber-propagated crop. After long-term asexual reproduction, the tubers will become smaller and the yield will decrease, resulting in "degeneration" and losing the significance of cultivation. High-quality potato seeds are the basis for high yield and good quality of potatoes. Therefore, the production of virus-free potato seeds is a very important and key link in the potato industrial chain and plays a decisive role in the development of the potato industry. According to the requirements of the national standard "Potato Seeds" (GB18133-2012), virus-free potato seeds are divided into a four-level system, namely minitubers, basic seeds, first-generation seeds, and second-generation seeds. In order to rapidly improve the quality of potato seeds, some regions have vigorously promoted the minituber breeding system of potatoes.

[0003] The virus-free potato minitubers widely adopt the substrate cultivation production technology, that is, in the greenhouse, using facilities such as seedbeds, and adopting substrates such as perlite, vermiculite, peat, and humus pine needle soil to fix the plants in the facilities for cultivation. Compared with other production methods, the minitubers produced by substrate cultivation have the advantages of good appearance, high yield, low cost, convenient transportation and storage, no pests and diseases, and can effectively avoid the accumulation of harmful substances and the lack of nutrients. The use of substrate types has an important impact on the production of minitubers.

[0004] At present, most of the substrates used are mainly vermiculite or vermiculite added with peat and other substances. The material sources are relatively single and the production cost is relatively high. The over-exploitation of peat soil will cause the greenhouse effect and aggravate environmental pollution. Although vermiculite can play a role in water retention, its nutrient content is very small. Repeated use requires high-temperature calcination and disinfection, which is time-consuming and laborious, and the use cost is relatively high. After repeated use, the air permeability and water retention are also greatly reduced, which is easy to cause plant diseases. Therefore, it is of great significance to make full use of local resources, adjust measures to local conditions, and develop a special substrate for virus-free potato minitubers with high efficiency, disease prevention and low cost. Summary of the Invention

[0005] The purpose of the present invention is to provide a special substrate for cultivating virus-free potato minitubers with high efficiency in promoting growth, disease prevention and low cost and a preparation method thereof.

[0006] The present invention adopts the following technical solutions: A special substrate for cultivating virus-free potato minitubers, which comprises a substrate body and a microbial inoculant adsorbed on the substrate body; the substrate body comprises organic components and inorganic components with a volume ratio of 10~40∶90~60; the total viable bacteria count in the substrate body is not less than 2.0×108 CFU / g.

[0007] Furthermore, the microbial inoculant includes Bacillus cereus CBBL-18, Bacillus licheniformis subsp. parafirmus CBJ-7, and Bacillus kuerlensis CBK-5.

[0008] Furthermore, the Bacillus cereus ( Bacillus c ereus ) CBBL-18 has a deposit number of CGMCC No. 30805; it is deposited in the China General Microbiological Culture Collection Center, located in Beijing, China, and the deposit date is May 29, 2024. This strain not only has the abilities of silicon release, phosphorus solubilization, potassium solubilization, nitrogen fixation, siderophore production, and IAA production, but also has good acid-base tolerance, heavy metal tolerance, and wide temperature adaptability.

[0009] Furthermore, the Bacillus licheniformis subsp. parafirmus ( Bacillus paralicheniformis ) CBJ-7 has a deposit number of CGMCC No. 31960, and is deposited in the China General Microbiological Culture Collection Center, located in Beijing, China, and the deposit date is September 13, 2024. This bacterium not only has the abilities of cellulase production and amylase production, which helps in the degradation and decomposition of organic waste. Moreover, it has obvious antagonistic effects against Fusarium oxysporum f. sp. vasinfectum and Bipolaris maydis.

[0010] Furthermore, the Bacillus kuerlensis ( Bacillus korlensis ) CBK-5 has a deposit number of CGMCC No. 33651, and is deposited in the China General Microbiological Culture Collection Center, located in Beijing, China, and the deposit date is February 25, 2025. This strain not only has the abilities of silicon release, potassium solubilization, siderophore production, and IAA production, but also has broad-spectrum anti-plant pathogen ability, and has antagonistic effects against Streptomyces scabies, Phytophthora infestans, Botrytis cinerea, etc.

[0011] Furthermore, for the Bacillus cereus CBBL-18, Bacillus licheniformis subsp. parafirmus CBJ-7, and Bacillus kuerlensis CBK-5 in the microbial inoculant, when the three strains are cultured pairwise on a PB medium plate using the cross-streak method, each strain grows well at the cross-section, indicating that there is no mutual antagonism between the strains.

[0012] Furthermore, the cell number ratio of the Bacillus cereus CBBL-18, Bacillus licheniformis subsp. parafirmus CBJ-7, and Bacillus kuerlensis CBK-5 in the microbial inoculant is 30 - 50:15 - 30:30 - 50.

[0013] Furthermore, the organic components include biogas residue and coir pith with a volume ratio of 50 - 80:20 - 50.

[0014] Further, the biogas residue is the biogas residue generated by solid-liquid separation after anaerobic fermentation and decomposition of livestock and poultry manure and / or crop straw.

[0015] Preferably, the livestock and poultry manure includes cow dung, pig dung, chicken dung, and sheep dung. The crop straw includes corn straw, wheat straw, and sorghum straw.

[0016] Further, the particle size of the organic component is less than 5 mm.

[0017] Further, the inorganic component includes iron tailings sand, fly ash, and vermiculite with a volume ratio of 30-50:20-40:10-30.

[0018] Further, the size of each component in the inorganic component is 0.25 mm - 1 mm, but the volume percentage of the broken particles with a particle size of 1 mm is 30% - 50%, and the volume percentage of the broken particles with a particle size of 1 mm - 3 mm is 50% - 70%.

[0019] A preparation method of the special substrate for cultivating the virus-free potato original seed includes the following steps: (1) Ferment Bacillus cereus CBBL-18, Bacillus licheniformis subsp. paramycoides CBJ-7, and Bacillus kuerlensis CBK-5 with PB liquid medium until spores are produced, count the spore content in the spore suspension, and mix them in proportion to obtain a microbial suspension; (2) Dry and crush the biogas residue and coconut coir to a particle size below 5 mm, and mix them in proportion to obtain dried organic matter; (3) Dry and crush iron tailings sand, fly ash, and vermiculite to different particle sizes, and mix them in proportion; (4) Mix the organic component and the inorganic component evenly, adsorb the microbial suspension, so that the total number of spores in the substrate is not less than 2×10 8 CFU / g.

[0020] The beneficial effects of the present invention are as follows: First, the microbial inoculant in the special substrate for producing virus-free potato original seeds in the present invention is composed of 3 probiotics. Among them, Bacillus cereus CBBL-18 has the abilities of silicon release, phosphorus solubilization, potassium release, nitrogen fixation, siderophore production, and IAA production; Bacillus licheniformis subsp. paramycoides CBJ-7 has the abilities of cellulase and amylase production, which is beneficial to the degradation and decomposition of organic waste; Bacillus kuerlensis CBK-5 has an antagonistic effect on potato scab pathogen, potato late blight pathogen, etc. It not only has a broad-spectrum anti-plant pathogen ability, but also has the abilities of silicon release, potassium release, siderophore production, and IAA production. The 3 microorganisms have a synergistic effect in function and have multiple functions such as disease prevention, growth promotion, and soil improvement for plants.

[0021] Second, the present invention uses agricultural waste and anaerobic fermentation biogas residues of livestock and poultry manure as organic components to produce a special substrate for producing virus-free potato minitubers, providing a new type of nutrient raw material for the substrate; not only greatly reducing the production cost of the substrate, but also being able to utilize waste, laying a foundation for the development of a healthy ecological circular agriculture.

[0022] Third, appropriate amounts of iron tailings sand and fly ash are added as inorganic components, which not only enrich the content of various trace elements in the potato production substrate, improve the air permeability and water permeability of the substrate, effectively improve the soil environment, but also utilize waste resources and reduce environmental pollution.

[0023] Fourth, the three probiotics in the microbial inoculant in the special substrate for producing virus-free potato minitubers all have strong tolerance characteristics to acids and alkalis, salts, and heavy metals, and produce various extracellular enzymes such as cellulase, protease, and starch. They have strong colonization ability and strong adaptability to changes in the external environment. After potato production, they can also be used for ecological restoration of obstacle soils.

[0024] Finally, using this composite microorganism to combine organic components and inorganic components to prepare a special substrate for producing virus-free potato minitubers can not only effectively improve soil nutrients, promote plant growth, but also utilize waste, reduce production costs, reduce the application amount of chemical fertilizers and pesticides, and promote the green and sustainable development of industry and agriculture. It has practical economic benefits and broad application prospects. Detailed implementation manners

[0025] The following further illustrates the present invention in conjunction with embodiments. The protection scope of the present invention is not limited to the embodiments, and any modifications made by those skilled in the art within the scope defined by the claims also fall within the protection scope of the present invention.

[0026] Example 1 Antagonism experiment The preservation number of Bacillus cereus CBBL-18 is CGMCC No. 30805, which is preserved in the China General Microbiological Culture Collection Center, located at the Institute of Microbiology, Chinese Academy of Sciences, No. 3, Beichen West Road, Chaoyang District, Beijing, China. The preservation date is May 29, 2024.

[0027] The preservation number of Bacillus subtilis CBJ-7 is CGMCC No. 31960, which is preserved in the China General Microbiological Culture Collection Center, located in Beijing, China. The preservation date is September 13, 2024.

[0028] The preservation number of Bacillus kuerlensis CBK-5 is CGMCC No. 33651, which is preserved in the China General Microbiological Culture Collection Center, located in Beijing, China. The preservation date is February 25, 2025.

[0029] Bacillus cereus CBBL-18, Bacillus licheniformis subsp. paramycoides CBJ-7, and Bacillus kuerlensis CBK-5. When the three strains were cultured pairwise on a PB medium plate using the cross-streak method, good growth was observed at the cross-section of the cross, indicating that there was no antagonistic effect between the strains.

[0030] Example 2 Preparation of a special substrate for producing virus-free potato minitubers (1) Preparation of the spore suspension of the microbial inoculant PB liquid medium: 10 g of peptone, 5 g of beef extract, 5 g of NaCl, 1 L of distilled water, pH 7.0 - 7.2.

[0031] Using an inoculation loop, pick the bacterial colonies of the test strains and inoculate them into the PB liquid medium respectively. Incubate at 28°C for 2 - 3 d, smear and observe under a microscope. When more than 80% of the bacteria produce spores, stop the incubation and perform plate counting to make the concentration of the Bacillus spore suspension ≥ 2×10 8 CFU / mL.

[0032] (2) Preparation of the microbial inoculant Mix Bacillus cereus CBBL-18, Bacillus licheniformis subsp. paramycoides CBJ-7, and Bacillus kuerlensis CBK-5 evenly according to the spore number (or bacterial number) ratio of 40∶20∶40 to prepare a bacterial liquid with a total spore (bacterial) number not less than 1.0×10 10 CFU / mL.

[0033] (3) Preparation of the special substrate for producing virus-free potato minitubers The organic components are composed of biogas residue and coconut coir in a volume ratio of 80∶20. The biogas residue is from the anaerobic fermentation of pig manure. Dry and crush the biogas residue and coconut coir to a particle size less than 5 mm. Dry the inorganic components of iron tailings sand, fly ash, and vermiculite and crush them into different particle sizes. Among them, the volume percentage of the particles with a size of 0.25 mm - 1 mm but without 1 mm particle size fraction is 30%, and the volume percentage of the particles with a size of 1 mm - 3 mm is 70%. Then mix them according to a volume ratio of 30∶40∶30. Mix 10% of the organic components and 90% of the inorganic components evenly, and then adsorb the microbial inoculant and mix evenly to make the total spore (bacterial number) in the substrate not less than 2.0×10 8 CFU / g. Example 3 Same as Example 2, except that in step (2), Bacillus cereus CBBL-18, Bacillus licheniformis subsp. paramycoides CBJ-7, and Bacillus kuerlensis CBK-5 are mixed evenly according to the spore number (or bacterial number) ratio of 30∶20∶50, and the total spore (bacterial) number is not less than 1×10 10CFU / mL. In step (3), the organic component consists of biogas residue and coconut coir in a volume ratio of 70:30. The biogas residue is from the biogas residue produced by the mixed anaerobic fermentation of pig manure and corn straw. The biogas residue is dried and crushed to a particle size less than 5 mm. The inorganic components of iron tailings sand, fly ash and vermiculite are dried and crushed into different particle sizes. Among them, the volume percentage of the particles with a size of 0.25 mm to 1 mm but excluding the 1 mm particle size fraction is 45%, and the volume percentage of the particles with a size of 1 mm to 3 mm is 55%. Then they are mixed in a volume ratio of 40:30:30. 20% of the organic component and 80% of the inorganic component are mixed evenly, and then adsorbed with microbial inoculum and mixed evenly so that the total spores (bacterial count) in the substrate are not less than 2.0×10 8 CFU / g.

[0034] Example 4 Same as Example 2, the difference is that in step (2), Bacillus cereus CBBL-18, Bacillus licheniformis subsp. parafirmus CBJ-7 and Bacillus kuerlensis CBK-5 are mixed evenly according to the spore number (or bacterial count) ratio of 50:15:35, and the total spore (bacterial cell) number is not less than 1×10 10 CFU / mL. In step (3), the organic component consists of biogas residue and coconut coir in a volume ratio of 60:40. The biogas residue is from the biogas residue produced by the mixed anaerobic fermentation of cow dung, corn and wheat straw. The biogas residue is dried and crushed to a particle size less than 5 mm. The inorganic components of iron tailings sand, fly ash and vermiculite are dried and crushed into different particle sizes. Among them, the volume percentage of the particles with a size of 0.25 mm to 1 mm but excluding the 1 mm particle size fraction is 40%, and the volume percentage of the particles with a size of 1 mm to 3 mm is 60%. Then they are mixed in a volume ratio of 50:20:30. 15% of the organic component and 85% of the inorganic component are mixed evenly, and then adsorbed with microbial inoculum and mixed evenly so that the total spores (bacterial count) in the substrate are not less than 2.0×10 8 CFU / g.

[0035] Example 5 Same as Example 2, the difference is that in step (2), Bacillus cereus CBBL-18, Bacillus licheniformis subsp. parafirmus CBJ-7 and Bacillus kuerlensis CBK-5 are mixed evenly according to the spore number (or bacterial count) ratio of 45:25:30, and the total spore (bacterial cell) number is not less than 1×10 10CFU / mL. In step (3), the organic components are composed of biogas residue and coconut coir in a volume ratio of 50:50. The biogas residue is from the biogas residue produced by the mixed anaerobic fermentation of pig manure + chicken manure + corn straw. The biogas residue is dried and crushed to a particle size less than 5 mm. The inorganic components of iron tailings sand, fly ash and vermiculite are dried and crushed into different particle sizes. Among them, the volume percentage of the particles with a size of 0.25 mm to 1 mm but excluding the 1 mm particle size is 35%, and the volume percentage of the particles with a size of 1 mm to 3 mm is 65%. Then they are mixed in a volume ratio of 50:40:10. 30% of the organic components and 70% of the inorganic components are mixed evenly, and then the microbial inoculant is adsorbed and mixed evenly so that the total spores (bacterial count) in the substrate are not less than 2.0×10 8 CFU / g.

[0036] Example 6 Same as Example 2, the difference is that in step (2), Bacillus cereus CBBL-18, Bacillus licheniformis subsp. CBJ-7 and Bacillus kuerlensis CBK-5 are mixed evenly according to the spore number (or bacterial count) ratio of 35:30:35, and the total spore (bacterial cell) number is not less than 1×10 10 CFU / mL. In step (3), the organic components are composed of biogas residue and coconut coir in a volume ratio of 65:35. The biogas residue is from the biogas residue produced by the mixed anaerobic fermentation of pig manure + sheep manure + sorghum straw. The biogas residue is dried and crushed to a particle size less than 5 mm. The inorganic components of iron tailings sand, fly ash and vermiculite are dried and crushed into different particle sizes. Among them, the volume percentage of the particles with a size of 0.25 mm to 1 mm but excluding the 1 mm particle size is 50%, and the volume percentage of the particles with a size of 1 mm to 3 mm is 50%. Then they are mixed in a volume ratio of 40:40:20. 40% of the organic components and 60% of the inorganic components are mixed evenly, and then the microbial inoculant is adsorbed and mixed evenly so that the total spores (bacterial count) in the substrate are not less than 2.0×10 8 CFU / g.

[0037] Example 7 Same as Example 2, the difference is that in step (2), Bacillus cereus CBBL-18, Bacillus licheniformis subsp. CBJ-7 and Bacillus kuerlensis CBK-5 are mixed evenly according to the spore number (or bacterial count) ratio of 30:25:45, and the total spore (bacterial cell) number is not less than 1×10 10CFU / mL. The organic component of step (3) is composed of biogas residue and coconut bran in a volume ratio of 55:45. The biogas residue is produced by anaerobic fermentation of cow dung, sheep dung and corn straw. The biogas residue is dried and crushed to a particle size of less than 5 mm. The inorganic components of iron tailings, fly ash and vermiculite are dried and crushed into different particle sizes, of which the volume percentage of particles with a size of 0.25 mm~1 mm but not including 1 mm particle size is 33%, and the volume percentage of particles with a size of 1 mm~3 mm particle size is 67%, and then mixed in a volume ratio of 45:30:25. 25% of the organic component and 75% of the inorganic component are mixed evenly, and then the adsorbed microbial agent is mixed evenly, so that the total spores (bacterial count) in the matrix is ​​not less than 2.0×10 8 CFU / g.

[0038] Example 8 Indoor potted plant test The pot experiment was used to determine the control effect of the composite microbial agent on potato scab. First, the scab pathogen was inoculated on solid PDA medium. After growing for 10 days, the spores were washed with sterile water and the spore concentration was adjusted to 1.0×10 8 CFU / mL, as the pathogen inoculum, the concentrations of Bacillus cereus CBBL-18, Bacillus paralicheniformis CBJ-7, Bacillus korlae CBK-5 and the composite microbial solution (the ratio of the number of Bacillus cereus CBBL-18, Bacillus paralicheniformis CBJ-7 and Bacillus korlae CBK-5 was 30:30:30) were adjusted to 1.0×10 8 CFU / mL was used as the inoculated bacterial solution. The cultivation substrate adopted the formula of Example 2 without adding microbial agents, and the scab Streptomyces spore suspension was mixed with the cultivation substrate at (V / V=1:20) and evenly packed in flower pots with a diameter of 23 cm and a depth of 20 cm. The cultivation substrate without inoculation of pathogens was used as the control CK0. The finished seedlings were transplanted, with 3 seedlings per pot. Five experimental treatments were set up, and single bacterial solution, compound bacterial solution and sterile water were applied respectively. Each treatment had 5 parallels, and 100 mL of bacterial solution was applied to each pot. After an interval of 20 days, 100 mL of bacterial solution was applied to each pot again, and the same amount of sterile water was inoculated as the pathogen control. The tuber disease situation was investigated when the potato grew for about 70 days.

[0039] The potato tuber area is divided into five levels according to the percentage of scab spots: Level 0, no spots; Level 1, 0%~15%; Level 2, 15%~30%; Level 3, 30%~50%; Level 4, greater than 50%.

[0040] Disease index = ∑ (number of diseased plants at each level × disease level) / (total number of plants surveyed × highest disease level) × 100.

[0041] Control effect (%) = (control disease index - treated disease index) / control disease index × 100.

[0042] Table 1 Control effects of different microbial inoculants on potato common scab in pot experiments .

[0043] The results showed (see Table 1) that in the control group without inoculant (CK + water), the disease occurred fully, typical scab concave lesions appeared on the tubers, the disease index reached 57.89, and the incidence rate was 100%. The incidence rate of potato tubers treated with microbial inoculants decreased significantly. Among them, the incidence rate and disease index of the treatment group with Bacillus velezensis CBK-5 were significantly lower than those of CK + water, Bacillus paralicheniformis CBJ-7, and Bacillus cereus CBBL-18. The incidence rate and disease index of potato tubers treated with compound inoculants were significantly lower than those of the control and single-bacteria-added treatments. The incidence rate was only 25.72% and the disease index was only 14.65, and the control effect reached 74.7%. In addition, the potato yield of the treatment group with compound inoculants was also significantly higher than that of the control and other treatment groups, further indicating that adding compound inoculants has the effects of preventing diseases and promoting growth on potatoes.

[0044] Example 9 Field application experiment An application experiment was carried out in a greenhouse in Chengde, Hebei. 10 treatments were set up in the experiment, including 4 control groups. The substrate formula was the same as that in Example 2 without microbial inoculants. The blank control CK0 had no microbial inoculants, CK1 only added Bacillus cereus CBBL-18 (the total number of spores or bacteria in the substrate was not less than 2.0×10 8 CFU / g), CK2 only added Bacillus paralicheniformis CBJ-7 (the total number of spores or bacteria in the substrate was not less than 2.0×10 8 CFU / g), CK3 only added Bacillus velezensis CBK-5 (the total number of spores or bacteria in the substrate was not less than 2.0×10 8 CFU / g). The 6 experimental groups corresponded to the formulated substrates in Examples 2 - 7 respectively. The finished seedlings were transplanted. Each group of experiments had 3 replicates, and each replicate was about 1.0 m 3 , and the test period was 3 months. The morphological characteristics of the plants were observed and recorded regularly, and the potato yield was statistically analyzed.

[0045] Table 2 Results of application experiments of special substrates for the production of virus-free potato minitubers .

[0046] According to the regulations of the vegetable seedling substrate NYT2118 - 2012, the physical property indexes of the substrate need to meet: bulk density 0.2 - 0.6 g / cm 3, Total porosity > 60%, aeration porosity > 15%. The results show (see Table 2 for details) that the substrate bulk density is 0.488 - 0.580 g / cm 3 , Total porosity is 65.03% - 69.28%, aeration porosity is 18.52% - 21.40%, indicating that the substrates of several formulations have good air permeability for oxygen supply, water retention and fertilizer retention capabilities. Through the observation of the morphological characteristics of the plants during the growth process of potatoes, the treatment group with the addition of compound microbial agents has significantly better growth status and plant survival rate than other experimental groups and the control group; and the potato tubers are of moderate size, regular shape, uniform color, and have no disease spots. There are a small number of disease spots on some of the tubers in the control group. In addition, whether it is the control group with the addition of single bacteria or the experimental groups with the addition of compound microbial agents, the survival rate and yield of potato plants are higher than those of the control group without bacteria; there is no significant difference in the plant survival rate and yield among the experimental groups with the addition of compound microbial agents, but they are all significantly better than the control group with the addition of single bacteria, indicating that the addition of compound microbial agents to the substrate has a disease-preventing and growth-promoting effect on potato minitubers.

[0047] The present invention has been described in detail according to the above embodiments. It should be noted that the above embodiments are only for illustrative purposes of the invention. Without departing from the spirit and essence of the present invention, those skilled in the art can design various alternative and improved schemes of the present invention, which should all be understood to be within the protection scope of the present invention.

Claims

1. A special substrate for cultivating virus-free potato original seeds, characterized in that: It includes a matrix body and a microbial agent adsorbed on the matrix body; the matrix body includes organic components and inorganic components in a volume ratio of 10-40:90-60; the total number of viable bacteria in the matrix body is not less than 2.0×10 8 CFU / g.

2. The special substrate for cultivating virus-free potato original seed according to claim 1, characterized in that: The microbial agents include Bacillus cereus CBBL-18, Bacillus paralicheniformis CBJ-7 and Bacillus korla CBK-5.

3. The special substrate for cultivating virus-free potato original seed according to claim 2, characterized in that: The deposit number of the Bacillus cereus CBBL-18 is CGMCC No.30805; the deposit number of the Bacillus paralicheniformis CBJ-7 is CGMCC No.31960; and the deposit number of the Korla Bacillus CBK-5 is CGMCC No.33651.

4. The special substrate for cultivating virus-free potato original seed according to claim 3, characterized in that: The bacterial count ratio of Bacillus cereus CBBL-18, Bacillus paralicheniformis CBJ-7 and Bacillus korlae CBK-5 in the microbial agent is 30-50:15-30:30-50.

5. The special substrate for cultivating virus-free potato original seed according to claim 1, characterized in that: The organic components include biogas residue and coconut bran in a volume ratio of 50-80:20-50.

6. The special substrate for cultivating virus-free potato original seed according to claim 5, characterized in that: The biogas residue is the biogas residue produced by anaerobic fermentation and composting of livestock and poultry manure and / or crop straw, and then undergoing solid-liquid separation.

7. The special substrate for cultivating virus-free potato original seed according to claim 6, characterized in that: The particle size of the organic component is less than 5 mm.

8. The special substrate for cultivating virus-free potato original seed according to claim 1, characterized in that: The inorganic components include iron tailings sand, fly ash and vermiculite in a volume ratio of 30-50:20-40:10-30.

9. The special substrate for cultivating virus-free potato original seed according to claim 8, characterized in that: The size of each component in the inorganic component is 0.25 mm to 1 mm, but the volume percentage of the 1 mm particle size particles is 30% to 50%, and the volume percentage of the 1 mm to 3 mm particle size particles is 50% to 70%.

10. A method for preparing a special substrate for cultivating virus-free potato original seeds according to any one of claims 1 to 9, characterized in that: It includes the following steps: (1) fermenting Bacillus cereus CBBL-18, Bacillus paralicheniformis CBJ-7 and Bacillus korlaensis CBK-5 in PB liquid medium until spores are produced, counting the spore content in the spore suspension, and mixing them according to proportion to obtain a microbial suspension; (2) Drying and crushing biogas residue and coconut bran to a particle size of less than 5 mm, and mixing them in proportion to obtain dried organic matter; (3) Dry the iron ore tailings, fly ash and vermiculite, crush them into different particle sizes and mix them according to the proportion; (4) Mix the organic and inorganic components evenly and adsorb the microbial suspension so that the total spore count in the matrix is ​​not less than 2×10 8 CFU / g.