CN114395397B

CN114395397B - Microbial soil improvement microbial inoculum for preventing and treating tobacco blight and preparation method thereof

Info

Publication number: CN114395397B
Application number: CN202210097289.8A
Authority: CN
Inventors: 敖金成; 李永梅; 李博
Original assignee: Yunnan Agricultural University
Current assignee: Yunnan Agricultural University
Priority date: 2022-01-27
Filing date: 2022-01-27
Publication date: 2022-09-27
Anticipated expiration: 2042-01-27
Also published as: CN114395397A

Abstract

The invention provides a microbial soil improvement microbial inoculum for preventing and treating tobacco blight, which comprises bacillus amyloliquefaciens cd5bc rape straw leavening and streptomyces oxysporum WS-29246; the preservation number of the bacillus amyloliquefaciens cd5bc is CCTCC NO: M2016232; the preservation number of the streptomyces oxysporum WS-29246 is CCTCC NO: M2012413; the bacillus amyloliquefaciens cd5bc rape straw leavening is obtained by taking rape straws as a leavening substrate and inoculating bacillus amyloliquefaciens cd5bc as zymocyte to ferment. The control effect of the invention aiming at tobacco black shank and tobacco root black rot can reach more than 85%; the invention can effectively reduce the cadmium accumulation in the tobacco, effectively reduce the lysine in the tobacco, improve the quality of the tobacco and reduce the harm to human bodies, and has good application prospect.

Description

Microbial soil improvement microbial inoculum for preventing and treating tobacco blight and preparation method thereof

Technical Field

The invention belongs to the technical field of agriculture, relates to a tobacco planting technology, and particularly relates to a microbial soil improvement microbial inoculum for preventing and treating tobacco blight and a preparation method thereof.

Background

Root rot in tobacco production ^[1] And black shank ^[2] Is a serious soil-borne disease and has been highly concerned by researchers. The root black rot and the black shank mainly occur in Yunnan, Guizhou, Hubei, Hunan, Sichuan and other places in China, the incidence rate of serious disease fields can reach more than 30 percent, and if the root black rot and the black shank are not controlled, the harm of the serious disease fields can be increased year by year.

Root black rot is caused by rhizomatoid moniliforme: (Thielaviopsis basicola) The hyphae of the tobacco are colorless in the initial stage and brown after the hyphae are branched, the tobacco can generate black root rot from the seedling stage to the adult stage, and the black root rot has great influence on the yield and the quality of the tobacco ^[3] . The black shank is caused by phytophthora nicotianae, can be attacked in seedling stage and field stage, and is easier to attack under the conditions of long continuous cropping annual limit and excessive concentration of varieties of tobaccos ^[4] 。

At present, the control methods for epidemic diseases including root black rot and black shank can be divided into chemical control methods, biological control methods, soil control methods, botanical drug control methods, and comprehensive control methods combining various methods.

The chemical prevention method is to use chemical agents to block pathogenic bacteria infection or inhibit and kill pathogenic bacteria. Common chemical agents for root rot include thiram, thiophanate methyl, and nail cream

Manganese, zinc, carbendazim, etc ^[5] The common chemical agents aiming at the black shank comprise fluocinoxabexae, thiophanate-methyl, dimethomorph, azoxystrobin, flufenoxaprop-p-ethyl, fenoxaprop-p-ethyl and fenoxaprop-ethyl,Cream of nails, manganese zinc, etc ^[6] . However, although the chemical control method has good and quick effect, the long-term use of high dose is not beneficial to agricultural development, and has important influence on soil, environment, animals and human beings.

The botanical drug control method is more and more favored by people because of better environmental protection property, although it still uses drugs for control than the generally recognized chemical control method. Chinese patent (publication No. CN 106804632A) obtains a plant source medical fertilizer capable of preventing and treating tobacco black shank by fermenting a plurality of traditional Chinese medicinal materials.

The biological control method mainly utilizes exogenous microorganisms as fertilizers, can avoid the problem of '3R' caused by high-dose application of chemical agents, and is a green and environment-friendly method. The current situation of biological control of black shank and black root rot is Luoyanyan ^[7] Henhaiying ^[8] All of which are discussed in greater detail in the Master thesis. At present, the biological control microorganisms which are often selected mainly include bacillus, pseudomonas and azotobacter. For example, Liujianjin et al ^[9] The bacillus amyloliquefaciens YN48 strain is adopted as a biocontrol bacterium to obtain good effect on preventing and treating the tobacco black shank; yilong et al ^[10] The method has the advantages that a spore strain R27 is separated, the growth and pathogenicity of hypha of the rhizoctonia solani can be well inhibited, and the control effects of carbendazim and thiophanate methyl are approximate to those of the control effects of the carbendazim and thiophanate methyl in the aspects of the disease rate and the disease index of tobacco seedlings; zhang Meng et al ^[11] Stenotrophomonas maltophilia YCYM-04 and Bacillus belgii YCYM-09 are separated, and the control effect of the two strains on the tobacco black shank reaches more than 50 percent; royuying et al ^[12] Two strains of bacillus amyloliquefaciens and one strain of bacillus subtilis are screened, and the control effect on the tobacco black shank reaches 60.2-70.1%; in Chinese patent CN108135178A, the agricultural biological community of America, Inc. has screened Bacillus subtilis AIP61892 which has preventing and treating effect on many pathogens.

In the above-exemplified biological control method, a strain having a control efficacy is mainly screened in a large amount or discovered by chance, which causes difficulties in finding the corresponding strain, thereby making the research of the biological control method slow. In fact, although the existing strains with control effects on black rot and black shank are mainly concentrated in a few genera such as bacillus, pseudomonas and azotobacter, the strains with control effects are found to be no different from canhai millet compared with the total amount of the strains in the genera, and the difficulty is great when seeking new strains with control effects from the known strains in the genera. In the prior art, the discovery of new strains is generally to discover soil with a low incidence rate, then to perform a large amount of strain screening work aiming at the soil, and to perform a large amount of detailed microorganism experiments, and finally to determine whether the strains obtained by corresponding separation have the control efficacy.

In addition to the prevention and treatment of epidemic diseases by using a single strain alone, in the field of biological prevention and treatment, a method of combining a plurality of strains is usually adopted, such as Liuchang and the like ^[13] The method comprises the steps of enabling pseudomonas to be matched with trichoderma viride, enabling bacillus to be matched with trichoderma harzianum, and enabling the bacillus to be matched with the trichoderma harzianum

The control of the fusarium root rot of the tobacco and the improvement of the agronomic traits achieve better effects, but the control may be in the reason of confidentiality, and the report does not disclose specific information of related strains; plum seedling, etc ^[14] In order to solve the problem of unstable control effect of a single strain, a large number of tests are carried out to screen out Bacillus belgii GY1, Bacillus amyloliquefaciens GY10 and Bacillus subtilis GY12, and the three are mixed, so that the potted control effect reaches 74.53%.

In addition to the combination of multiple strains, some researchers have also studied the control effect of combining specific microorganisms with chemicals in the field of tobacco blight. Such as Liujianjin ^[15] The combination of bacillus amyloliquefaciens YN48 and flumioaluminum, refined methyl frost and manganese zinc is considered to have better control effect. However, the combination of microorganisms with drugs often results in reduced control, probably because chemical drugs are highly inhibitory to the growth of microorganisms or antagonistic to microbial metabolitesFor example, Xuyuru et al ^[16] The control effect is greatly reduced after the cream A and the manganese zinc are added on the basis of the trichoderma.

However, while biological control methods have advantages over existing methods, the control obtained by biological control methods is generally low relative to chemical control. Such as Yan Qing Yan ^[17] The control effect of 5 common chemical agents on the black shank can reach more than 70 percent through investigation, while the control effect of more than 70 percent is difficult to obtain through a biological control method, and the control effect of only a few biological control bacteria approaches or slightly exceeds 70 percent. Meanwhile, as mentioned above, the biocontrol bacteria are not easily obtained, and a large amount of screening work is required.

In addition, the control of tobacco quality, such as reducing heavy metal absorption, controlling the content of corresponding amino acid, etc., often depends on tedious cultivation system or chemical agent ^[18] The microorganisms are extremely easy to be inhibited by chemical agents, so that the obvious defect exists in the tobacco epidemic disease prevention and control by utilizing the microorganisms, namely the occurrence of the epidemic disease can be usually prevented, but the quality of the tobacco is difficult to further improve.

It is worth pointing out that although the above prevention and control methods have advantages, they have been applied to different degrees in the industry, and promote the development of tobacco planting industry. However, the above-mentioned control methods usually cannot change the quality of the tobacco field, and it is difficult to fundamentally improve the tobacco planting level in the tobacco field. Therefore, a plurality of researchers can prevent and treat related tobacco epidemic diseases and improve the agronomic traits and related quality indexes of tobacco from the aspect of improving the tobacco field quality.

Soil improvement to prevent epidemic diseases belongs to a soil control method, and the soil control method is to improve soil or to plant crops by using special soil. Generally, researchers believe that the incidence of root black rot is lower when the pH of the soil is lower ^[19] This may be related to pH affecting the distribution and activity of antagonistic microorganisms and pathogens in the soil ^[20] . In addition to adjusting physical properties such as pH of soil, researchers mainly use drugs ^[21] Or a microorganism ^[22] The soil is treated to a level suitable for reducing morbidity.

In the field of soil improvement, the cost of chemical treatment is high, and environmental pollution or sanitation hazards are easily caused, so that the improvement of soil by using a microbial agent is a high-recognized research direction at present. Zhang Yan et al ^[23] Introduces the advantages of the microbial soil conditioner and the application of the microbial soil conditioner in tobacco planting. He Pei et al ^[24] Some reports on microbial soil conditioners have been introduced correspondingly.

In the aspect of preparing the microbial soil improvement microbial inoculum for preventing and treating tobacco black shank and tobacco black root rot, the adopted microorganisms and biocontrol bacteria adopted by a biological control method usually coincide to a certain extent. Such as plum updates ^[25] When the composite microbial agent for improving the soil of the tobacco field is prepared by the people, the bacillus and the trichoderma which are also used in the biological control method are also used; renwei for Renwei ^[26] The influence of the spore fungicide for improving the tobacco field soil on the agronomic characters of the tobacco is researched by the people. Generally speaking, when a soil conditioner (or called soil conditioner) is prepared by using biocontrol bacteria, in addition to the inhibition effect of the corresponding biocontrol bacteria on specific epidemic disease pathogenic bacteria, the adopted substrate is required to meet the requirement that the biocontrol bacteria and the flora in the soil reach a new balance so as to play a role in preventing and treating epidemic diseases and improving the agronomic traits and relevant quality indexes of crops. As found in the Master thesis of Wang Guangxiang, only after the pepper seeds and the biochar are used together, good fermentation conditions can be provided for the bacillus subtilis Tpb55, and 59.41% of control effect can be obtained in the aspect of controlling the tobacco black shank.

In the aspect of preparing the tobacco field soil conditioner by using microorganisms, the biological control method introduced in the foregoing also faces the difficulty that the control effect on black shank and black root rot is too low, and industrial practitioners lack the power to popularize and use the method. Meanwhile, the microbial balance in the soil is reestablished, and both the biological control and the selection of the carrier matrix have high unpredictability, so that the research difficulty of the related soil control method is further increased.

In view of the above, there is a need in the art to provide a microbial soil improvement fungicide technology that has high control efficiency, improves the growth characteristics of tobacco, and improves the quality of tobacco, aiming at the disadvantages faced by the existing soil control methods (especially tobacco field microbial soil improvement fungicides).

References in this section:

[1] molecular identification and pathogenicity analysis of Nicotiana tabacum of Henan province [ J ] tobacco science and technology, 2017, 50(3):7.

[2] Occurrence and comprehensive control of tobacco black shank by Lemna minor [ J ] southern agriculture, 2018, 12(35):2.

[3] Zhao Wen Jun, Yang Jiu Wen, Von Yu, and so on, the research on the prevention and treatment of black rot of tobacco root [ J ] Hunan agricultural science 2015(1):3.

[4] Zhaohui, Wangxi English, Liu national right, Tan Zhiyong, tobacco black shank occurrence factor and comprehensive prevention and treatment research progress [ J ] Hunan agricultural science 2020(11):5.

[5] Juan Song Yu, Trichoderma asperellum T-6 has growth promoting and disease resisting effects on tobacco [ D ] Shandong agricultural university, 2019.

[6] Yanqingyan, the control effect of different medicaments on tobacco black shank is compared and analyzed, wherein the Yanqingyan, Henan agriculture, 2019(11) and 3.

[7] Research on screening, identification and biological control of rhizosphere antagonistic bacteria of Royun Yan tobacco root black rot [ D ]. northwest university of agriculture and forestry science and technology, 2021.

[8] Technical research on biological control of tobacco black shank and root black rot in Penhai, D. Shandong university of agriculture 2020.

[9] Liu Jian jin, Liu Zi apparatus, Luoshan, etc. adopts biocontrol bacterium YN48 to prevent and control tobacco black shank [ J ] in the early stage, Jiangxi agricultural science, 2019, 31(4):4.

[10] Screening of antagonistic spore strains for preventing and treating tobacco root black rot [ J ] plant pathology report 2011, 41(3):4.

[11] Zhang Meng, Liang Junyang, Wang Qing Fu, Dou ya Fei, Zhang Jie, Liu Qiang, Pabo, Peng Jianfei tobacco Black shank biocontrol bacteria identification and prevention efficacy determination [ J/OL ]. Henan university of agriculture bulletin 1-13[2022-01-05].

[12] Screening of tobacco black shank biocontrol bacillus and field control effect thereof [ J ] Guizhou agricultural science, 2019, 47(1):6.

[13] Liu Chang, Yaoheng 34387, Li Xiaojie, and the like.

[14] The prevention and treatment effect of plum seedling, king phoenix dragon, king xiaoqiang, etc. on tobacco black shank by biocontrol bacteria recombination [ J ] Chinese tobacco science 2020, 41(2):7.

[15] The study on the prevention and treatment of tobacco black shank by matching of the bacillus amyloliquefaciens YN48 and a bactericide [ J ]. the school newspaper of Yunnan agricultural university: nature science edition 2020,35 (2):6.

[16] Xuyuru, Yangshaoxing, Quzhengyuan, etc. the prevention and cure effect of different medicines on tobacco black shank [ J ] Liaoning agricultural science, 2021(5):5.

[17] Yanqingyan, the control effect of different medicaments on tobacco black shank is compared and analyzed, wherein the Yanqingyan, Henan agriculture, 2019(11) and 3.

[18] Huang Zhen Rui, Lin Aten, Li Ji Du, Mazhu Wen, Li Shu Ling-Nai' an and humic acid promote the growth of flue-cured tobacco and reduce the tobacco leaf cadmium pollution synergistic effect [ J ]. southern agricultural science, 2021,52(02): 429-.

[19]Doran W L．Relation of the adjustment of soil reaction to black root rot of tobacco.Science,1927,66：661~662.

[20]Kaufmann D DWilliams L E∙Effect of mineral fertilization and soil reaction on soil fungi.Phytopathology,1964,54：134~139.

[21] Huangshiwang, Wangchun, Wenyun, etc. research on the prevention and control effect of soil fumigation on tobacco soil-borne diseases [ J ] Hunan agricultural science 2021(11) 59-61.

[22] Study on the improvement of soil biological characteristics and the prevention and treatment of tobacco black shank by using a compound microbial preparation [ J ] China soil and fertilizer, 2021(1).

[23] Zhanyan, Deng Dang, great luck and auspicious, application of microbial technology in tobacco planting [ J ] Jiangxi agriculture, 2020(08) 40-41.

[24] Development and utilization of microorganisms in tobacco by He Pei, Soi generation, Yanjunyu, Show, Liu Shi, Tou Long. the progress of research, development and utilization of microorganisms in tobacco [ J ]. Hubei agricultural science, 2019,58(S2):42-57+60.

[25] Plum renewal, Yanglian, Zhang Yinhua, Yinjiang, Zhang Yuan, Yanluo, influence of the composite microbial agent for improving tobacco field soil on the yield and quality of tobacco leaves [ J ] modern agricultural science, 2018(22):7-8+10.

[26] The influence of the spore-forming agent for improving the soil of tobacco field on the agronomic traits of tobacco [ J ] agricultural science and technology communication, 2019(09): 123-126).

Disclosure of Invention

Aiming at the defects and the actual needs of the prior art, the invention aims to provide a microbial soil improvement microbial inoculum for preventing and treating tobacco blight and a preparation method thereof, so as to solve the following defects of the prior art: (1) the problem that the control effect of the existing soil control method is too low for tobacco black shank and root black rot is solved; (2) the problem that the growth character of the tobacco is difficult to improve under the condition of low control effect is solved; (3) solves the problem that the content of heavy metal and related amino acid in tobacco can not be effectively improved by the existing soil control method.

On the basis, the invention specifically aims to provide a microbial soil improvement microbial inoculum which has the control effect on tobacco black shank and tobacco root black rot of more than 85 percent, effectively improves the growth characteristics of tobacco, obviously reduces the content of mesophyll in the tobacco and reduces the content of lysine in the tobacco and a preparation method thereof.

In order to achieve the above purpose, the invention provides the following technical scheme:

a microbial soil improvement microbial inoculum for preventing and treating tobacco blight, which comprises bacillus amyloliquefaciens cd5bc rape straw leavening and streptomyces oxysporum WS-29246;

the preservation number of the bacillus amyloliquefaciens cd5bc is CCTCC NO: M2016232; the preservation number of the streptomyces oxysporum WS-29246 is CCTCC NO: M2012413;

the bacillus amyloliquefaciens cd5bc rape straw leavening is obtained by taking rape straws as a leavening substrate and inoculating bacillus amyloliquefaciens cd5bc as zymocyte to ferment.

Bacillus amyloliquefaciens cd5bc is disclosed in Chinese patent "A Bacillus amyloliquefaciens cd5bc and its application" (publication No. CN 105907683A), with the preservation number of CCTCC NO: M2016232, and is used for preventing and treating pathogenic bacteria of capsicum sclerotinia, bitter melon fusarium wilt, cucumber fusarium wilt, yellow black spot, rice blast, rice sheath blight, broad bean red spot, broad bean brown spot, broad bean red spot, and broad bean brown spot. Streptomyces oxysporus WS-29246 is disclosed in Chinese patent "Streptomyces oxysporus and its application in preventing and treating clubroot of Cruciferae", with the preservation number of CCTCC NO: M2012413, and is used for preventing and treating clubroot of Cruciferae.

In the process of the prevention and treatment research of the tobacco black shank and the black root rot, the inventor unexpectedly finds that after the bacillus amyloliquefaciens cd5bc, the streptomyces oxysporum WS-29246 and the frost-a-methyl and manganese-zinc are combined, the prevention and treatment effects on the tobacco black shank and the tobacco black root rot can be remarkable, and the usage amount of the frost-a-methyl and manganese-zinc can be extremely low. Based on the technical solution under the discovery, the inventors filed an additional patent. Since the combination of biocontrol bacteria under this discovery is also the basis of the present invention, the main discovery process is still recorded in the second test example of the present invention in order to better understand the present invention.

Generally speaking, after a certain bacterium or a certain compound bacterium is found to be a biocontrol bacterium, the biocontrol bacterium can be generally considered to be made into a soil conditioner so as to fundamentally change the microbial flora relationship in soil and further realize a long-term epidemic disease control effect.

In the above findings, although the chemical agent cream methylen/manganin is applied at a low rate, when it is used as a soil conditioner, there is still a great concern because the application rate is generally large. Therefore, the inventors considered how to prepare a soil conditioner having a good control effect without using methyl ethyl zinc.

As shown in the first test example of the invention, when the fermentation substrate is selected, except for the rape straw, the other substrates are difficult to ferment or cannot generate good control effect.

It is noted that although Streptomyces oxysporum WS-29246 and Bacillus amyloliquefaciens cd5bc did not have antagonistic action as shown in test example one of the present invention, the control effect was significantly reduced when both were inoculated for fermentation, compared to inoculation of Bacillus amyloliquefaciens cd5bc alone. The phenomenon is probably because when the rape straws are used as substrates for fermentation, secondary metabolites produced by the streptomyces oxysporum WS-29246 can inhibit the metabolites of the bacillus amyloliquefaciens cd5bc to a certain extent in the aspect of epidemic disease resistance. When the culture solution of streptomyces oxysporum WS-29246 is mixed with the fermentation product of the rape straw of bacillus amyloliquefaciens cd5bc, the control effect is greatly improved, which proves the guess to a certain extent, but the inhibition effect among different metabolites needs further research.

As shown in the embodiment of the invention, the soil conditioner disclosed by the invention not only has excellent control effect on tobacco black shank and tobacco black root rot, but also can improve the agronomic characters and relevant important indexes (such as cadmium content and lysine content) of tobacco. As has been found out unexpectedly, the key point in achieving the above technical effects is to select Streptomyces oxysporum WS-29246 and Bacillus amyloliquefaciens cd5bc as biocontrol bacteria, but as shown in the first test example of the present invention, the selection of fermentation substrate has a great influence on the above technical effects. The results show that the biocontrol bacterium disclosed by the invention is dependent on the selected substrate in the aspect of regulating and controlling the soil microorganism balance system, and the biocontrol bacterium disclosed by the invention can effectively change the abundance of different microorganisms in soil under the substrate disclosed by the invention, so that a soil environment suitable for the growth of tobacco is created. Similarly to the case where biocontrol bacteria rely on a substrate to promote soil improvement, microbial improving agents exemplified in the background art have also been reported.

The invention adopts rape straws as fermentation substrates, produces fermentation products through the fermentation of bacillus amyloliquefaciens cd5bc and is matched with streptomyces oxysporum WS-29246, and the soil conditioner with excellent technical effect is obtained.

The use of straw as a fermentation substrate for microorganisms has been reported in the art, for example, Korea swordlike ^[27] The corn straws are fermented by the people, and the fertilizer for improving the saline-alkali soil is preparedEnergetic soil conditioner, Zhou Xiao Fei ^[28] The microorganism is utilized to ferment the corn straws, and a compost formula and cultivation conditions which can promote the growth of wheat and improve the property of saline-alkali soil are screened out. However, the inventor finds that when other straws (such as corn straws) are used as fermentation substrates, although a good control effect can still be obtained, the control effect is still at the level (below 70%) of the control effect of general biocontrol bacteria and bacterial manure or soil conditioners prepared by the biocontrol bacteria, and the effect of reducing the content of lysine is unexpectedly lost. The inventor guesses that the slight difference of the content between the rape straws and other straws probably has important influence on the generation or the yield of important metabolites which have important influence on improving the control effect of the tobacco black shank and the tobacco black root rot and determine whether the lysine in the tobacco can be reduced.

Because the invention lacks chemical agents of cream-methyl and manganese-zinc, the technical effect of reducing lysine is probably generated by the synergistic effect of metabolites which have similar effect with the cream-methyl and manganese-zinc and the biocontrol bacterium of the invention. Therefore, to solve the problem that the lysine in tobacco cannot be reduced by using other raw materials as fermentation substrates, the metabolite in the fermentation product of the invention needs to be separated and combined with two biocontrol bacteria to examine the influence of the metabolite on the content of the lysine in tobacco, so as to determine which metabolite in the fermentation product of the invention has a key influence on the content of the lysine in tobacco. Research work in this regard will be carried out in the future.

As an alternative embodiment of the invention, the Streptomyces oxysporum WS-29246 is added in the form of a culture broth.

Preferably, the concentration of the Streptomyces oxysporum WS-29246 in the culture solution is 1 × 10 ⁶ cfu/mL~1×10 ⁷ cfu/mL。

Preferably, the bacillus amyloliquefaciens cd5bc rape straw leavening is prepared by crushing rape straws to be used as a fermentation substrate.

Preferably, when the bacillus amyloliquefaciens cd5bc rape straw leavening is inoculated with the bacillus amyloliquefaciens cd5bc, 5ml of the bacillus amyloliquefaciens cd5bc culture solution is added100g of rape straw crushed material is inoculated, the bacterial concentration of the culture solution of the bacillus amyloliquefaciens cd5bc is 1 multiplied by 10 ⁶ cfu/mL~1×10 ⁷ cfu/mL。

As a preferred technical scheme of the invention, when the bacillus amyloliquefaciens cd5bc rape straw fermentation product is prepared, a nutrient solution is also added to ensure that the water content is 65-70%; the formula of the nutrient solution is as follows: NH (NH) ₄ NO ₃ 1.2g，KH ₂ PO ₄ 1.5g，KCl 0.6g，ZnSO ₄ ·7H ₂ O 0.04g，Ca(NO ₃ )·4H ₂ O 3g，MgSO ₄ ·7H ₂ O 1g，FeSO ₄ ·7H ₂ O1 g, ethylene diamine tetraacetic acid disodium 0.6g, KI 0.2g and MnSO ₄ 0.1g，CuSO ₄ 0.01g, CoCl 0.01g, boric acid 0.03g, sodium molybdate 0.01g and purified water 370 mL.

As one alternative embodiment of the invention, the Streptomyces oxysporum WS-29246 fermentation broth is obtained by inoculating Streptomyces oxysporum WS-29246 and fermenting, wherein the used culture medium comprises the following components: 100g of cane sugar, 10g of glucose, 0.1g of casamino acid, 5g of yeast extract powder, 21g of propanesulfonic acid and K ₂ SO ₄ 0.25g，MgCl ₂ ·6H ₂ O10 g, trace element 1mL, water 1000mL, pH = 7.0; wherein the microelement formula is MnSO ₄ ·7H ₂ O 100mg，CuSO ₄ ·7H ₂ O 50mg，ZnSO ₄ ·7H ₂ O 100mg，CoCl ₂ 100mg, 100mL of purified water.

Preferably, the microbial soil improvement microbial inoculum consists of 100-120 mL of the Streptomyces oxysporum WS-29246 culture solution and 150-180 g of Bacillus amyloliquefaciens cd5bc rape straw fermentation product.

The preparation method of the microbial soil improvement microbial inoculum provided by the invention comprises the following steps: the preparation method comprises the step of mixing the bacillus amyloliquefaciens cd5bc rape straw fermentation product and the streptomyces oxysporum WS-29246.

The invention provides application of the microbial soil improvement microbial inoculum in the aspect of being used as a soil improvement agent for preventing and treating tobacco root black rot and black shank.

The invention has the beneficial effects that:

1. the invention can achieve the control effect of over 85 percent aiming at the tobacco black shank and the tobacco root black rot, and overcomes the technical problem of low control effect of the conventional soil control method by utilizing microorganisms.

2. The method can effectively reduce the cadmium accumulation in the tobacco, improve the quality of the tobacco and enlarge the planting range of the tobacco.

3. The invention can effectively reduce lysine in tobacco, reduce ammonia in tobacco and reduce the damage of tobacco to human body.

References in this section:

[27] korean Jianhong, Wang Xuping, Zhangke, Yuwei Jia, Jia Li Yan, Wang Weida, the influence of fermented corn stalk on the soil fertility index of saline-alkali soil [ J ] irrigation drainage science, 2017,36(12):56-61.

[28] Dawn fly, straw microbial compost formula optimization and initial exploration for saline-alkali soil improvement [ D ]. tianjin science university, 2012.

Detailed Description

The present invention is described in detail below by way of examples, and it should be noted that the following examples are only for illustrating the present invention and should not be construed as limiting the scope of the present invention.

In each of the examples and test examples of the present invention, the strains used were purchased commercially or given away, and the present invention does not relate to screening of new strains.

Example 1

1. Raw materials

The bacillus amyloliquefaciens cd5bc with the preservation number of CCTCC NO of M2016232 is sold in the market;

streptomyces oxysporum WS-29246 with preservation number of CCTCC NO: M2012413, available on the market;

LB medium (for bacillus amyloliquefaciens cd5 bc): self-preparation in a laboratory;

streptomyces oxysporum WS-29246 medium, laboratory self-prepared: 100g of cane sugar, 10g of glucose, 0.1g of casamino acid and 5g of yeast extract powderg, propanesulfonic acid 21g, K ₂ SO ₄ 0.25g，MgCl ₂ ·6H ₂ O10 g, trace element 1mL, water 1000mL, pH = 7.0; wherein the microelement formula is MnSO ₄ ·7H ₂ O 100mg，CuSO ₄ ·7H ₂ O 50mg，ZnSO ₄ ·7H ₂ O 100mg，CoCl ₂ 100mg and 100mL of purified water;

the formula of the nutrient solution is as follows: NH (NH) ₄ NO ₃ 1.2g，KH ₂ PO ₄ 1.5g，KCl 0.6g，ZnSO ₄ ·7H ₂ O 0.04g，Ca(NO ₃ )·4H ₂ O 3g，MgSO ₄ ·7H ₂ O 1g，FeSO ₄ ·7H ₂ O1 g, disodium ethylene diamine tetraacetate 0.6g, KI 0.2g, MnSO ₄ 0.1g，CuSO ₄ 0.01g, CoCl 0.01g, boric acid 0.03g, sodium molybdate 0.01g, and purified water 370mL, pH = 7.2.

Test soil: the physical and chemical properties of the disease-free soil in the tobacco planting field are as follows: pH =8.43, volume weight 1.41g/cm ³ Total porosity 56.12%, respiration intensity 3.47mg g ^-1 ·h ^-1 。

Tobacco seedling: yunyan 87, owned by the laboratory.

2. Potted plant control effect experiment

Culturing Bacillus amyloliquefaciens cd5bc with LB culture medium to obtain bacterial liquid (bacterial concentration 1 × 10) ⁶ cfu/mL), culturing Streptomyces oxysporus WS-29246 by using Streptomyces oxysporus WS-29246 culture medium to obtain Streptomyces oxysporus WS-29246 culture solution (bacterial concentration 1X 10) ⁶ cfu/mL); crushing rape straws to serve as a fermentation substrate, adding 5ml of a bacterial liquid obtained after culturing bacillus amyloliquefaciens cd5bc into 100g of the crushed rape straws for inoculation, adding a nutrient solution to enable the water content to be 70%, and fermenting at room temperature until the rape straws are thoroughly decomposed to obtain a bacillus amyloliquefaciens cd5bc rape straw fermented product; 100mL of Streptomyces oxysporus WS-29246 culture solution is mixed with 150g of Bacillus amyloliquefaciens cd5bc rape straw fermentation product to obtain the microbial soil improvement microbial inoculum.

Mixing the microbial soil improvement microbial inoculum and the soil to be tested according to the weight ratio of 1:5, and placing the mixture in a cultivation pot. After mixing, the physicochemical properties of the soil were: pH =8.10, volume weight 1.03g/cm ³ Total, ofPorosity of 76.33%, respiratory strength of 5.37mg g ^-1 ·h ^-1 . Therefore, the microbial soil improvement microbial inoculum can improve the physical properties of soil and is more suitable for the growth of crops.

Transplanting the tobacco seedlings into a cultivation pot, dividing the tobacco seedlings into two groups after 40 days, inoculating phytophthora nicotianae on one group and inoculating alternaria solani on the other group, and investigating the disease incidence according to the standard GB/T23222-2008.

Through detection, the prevention effect of the experiment on the tobacco black shank reaches 87.9%, and the prevention effect on the tobacco root black rot reaches 85.3%. The prevention effect of the invention even exceeds that of common chemical agents, such as CN 108633913B, and the breakthrough of preparing the soil conditioner by using the microorganism in the aspect of preventing and controlling tobacco black shank and tobacco black root rot is realized.

On the basis, the culture solution of streptomyces oxysporum WS-29246 is adjusted to 120mL, and the fermentation product of the cd5bc bacillus amyloliquefaciens rape straw is adjusted to 160g and is marked as an experimental group 1; the same experiment was carried out with the culture solution of Streptomyces oxysporum WS-29246 adjusted to 110mL and the fermentation product of Bacillus amyloliquefaciens cd5bc rape straw adjusted to 180g, which was designated as experiment group 2, and the results are shown in Table 1.

TABLE 1

3. Agronomic trait experiment of potted plant

The test soil without the microbial soil improvement fungicide is used as a control group, and the control group potted soil is not inoculated with the tobacco root black rot and the tobacco phytophthora. The stem height, stem circumference and seedling uniformity were investigated at the heart stage of 5 leaves and 1 in tobacco seedlings, and the results are shown in Table 2.

TABLE 2

As shown in Table 3, the present invention can effectively improve the agronomic characteristics of tobacco.

4. Lysine content investigation experiment

While the experiment of the agricultural character of the potted plant is carried out, the lysine content in the experimental group and the control group is also considered. The method for measuring the lysine content comprises the following steps: 10g of leaf was taken from each plant and analyzed by amino acid assay, the percentage of lysine = the lysine content of the sample ÷ the total amino acid content in the sample. The results are shown in FIG. 4.

TABLE 3

As can be seen from Table 3, the lysine content in tobacco can be significantly increased by the method.

5. Cadmium reduction experiment

Cadmium is added into the tested soil until the content of cadmium in an effective state in the soil is measured to be 3.8 mg/kg by the method in GB/T17141-1997, the cadmium content in the lower leaves, the middle leaves and the upper leaves is examined according to the experiment of pot agronomic characters, and the result is shown in Table 5.

TABLE 4

As can be seen from Table 4, the present invention can significantly reduce the cadmium content in tobacco.

The following test examples are provided to illustrate the procedure for obtaining the compositions according to the invention.

Test example 1

In the course of the study, the present inventors examined the effects of different fermentation substrates, which were used in the fermentation with Bacillus amyloliquefaciens cd5bc and Streptomyces oxysporum WS-29246, as shown in Table 5. During the fermentation process, the nutrient solution in the examples was also used to adjust the water content to 70%. As shown in Table 5, no matter the selection of rape straws, corn straws or rice bran, fermentation is difficult to start so that the substrate reaches a decomposed state, and the bacillus amyloliquefaciens cd5bc can well decompose the rape straws, the corn straws or the rice bran.

TABLE 5

	Rape straw	Corn stalk	Rice bran
				Bacillus amyloliquefaciens cd5bc	Smoothly become thoroughly decomposed	Smoothly become thoroughly decomposed	Smoothly become thoroughly decomposed
Streptomyces oxysporum WS-29246	Difficult to become thoroughly decomposed	Difficult to become thoroughly decomposed	Partially decomposed

As the inoculated streptomyces oxysporum WS-29246 can not successfully decompose the fermentation substrate, the inventor considers that the culture solution of the two is mixed with the same volume as the inoculated bacterial solution (mainly thinking that the fermentation is carried out by mainly depending on bacillus amyloliquefaciens cd5 bc) and the rape straw is taken as the fermentation substrate for fermentation, but the prevention effect of the obtained microbial soil improvement microbial inoculum on tobacco black shank and tobacco root black rot is less than 45%. The inventor guesses that as the streptomyces oxysporum WS-29246 can also partially decompose the rape straws to generate corresponding metabolites, the remarkable reduction of the prevention effect is probably related to the antagonism of certain metabolites of the streptomyces oxysporum WS-29246 and the metabolites of the rape straws fermented by the bacillus amyloliquefaciens cd5 bc.

In addition, when the corn straw or the rice bran is used for replacing the rape straw, the microbial soil improvement microbial inoculum is prepared by referring to the method of the embodiment, and the tobacco black shank and the tobacco black root rot are examined by the method of the embodiment, the control effect on the tobacco black shank and the tobacco black root rot is only about 50-65%, and the effect of reducing the content of the tobacco lysine is not surprisingly achieved (compared with a control group, the difference of the content ratio is not more than 2%).

Test example two

Test example 1

Raw materials:

the fermentation liquor of the bacillus amyloliquefaciens cd5bc and the streptomyces oxysporum WS-29246 are obtained by liquid culture fermentation of bacillus amyloliquefaciens cd5bc and streptomyces oxysporum WS-29246 strains;

the 72% wettable powder of the cream-methyl and the manganese zinc is obtained by the market;

tobacco seedling: yunyan 87, owned by the laboratory;

the tobacco root black rot and tobacco phytophthora are owned by the laboratory.

Potted plant control effect test: fermenting the fermentation liquor (bacterial concentration 1 × 10) of the bacillus amyloliquefaciens cd5bc ⁶ cfu/mL), Streptomyces oxysporus WS-29246 fermentation broth (concentration 1X 10) ⁶ cfu/mL) and 72% of methyloxathite-manganin wettable powder (diluted by 5000 times of water) are mixed according to the volume ratio of 1:1:0.1 to obtain a mixed medicament; after 40 days of tobacco seedling transplantation, the tobacco seedlings are divided into two groups, each plant in the two groups is irrigated with 20mL of mixed medicament, one group is inoculated with phytophthora nicotianae and the other group is inoculated with the tobacco root rot pathogen after 5 days, and the disease incidence condition is investigated according to the standard GB/T23222-2008.

Through detection, the control effect of the test on the tobacco black shank reaches 91.3%, and the control effect on the tobacco root black rot reaches 90.7%.

Test example 2

Test example 1 is one of the test schemes randomly performed by the inventors in the process of investigating whether streptomyces oxysporum has a control effect on phytophthora nicotianae. Encouraged by the results of test example 1, the inventors investigated the combination of Streptomyces oxysporum WS-29246 with other Bacillus amyloliquefaciens reported to have good control effect, and examined the effects of the different combinations on the control of tobacco black shank and tobacco root black rot with reference to the method of test example 1.

The strain source is as follows:

bacillus amyloliquefaciens YN48 purchased from the research center of microbial fermentation engineering of Yunnan province, Co., Ltd;

bacillus amyloliquefaciens X60 with the preservation number of CCTCC M2013375, which is sold in the market;

bacillus amyloliquefaciens GUMT319 with the preservation number of CCTCC NO: m2018872, commercially available.

Referring to test example 1, fermentation broths (OD) of the above three strains ₆₀₀ = 0.3) and Streptomyces oxysporum WS-29246 fermentation liquor (OD) according to the volume ratio of 1:1:1 ₆₀₀ = 0.3) and 72% wettable powder of methyl cream and manganese zinc (1000-fold dilution) to obtain mixed agents which are respectively named as a bacillus amyloliquefaciens YN48 scheme (scheme one), a bacillus amyloliquefaciens X60 scheme (scheme two) and a bacillus amyloliquefaciens GUMT319 scheme (scheme three). After 40 days of tobacco seedling transplantation, the tobacco seedlings are divided into two groups, each plant in the two groups is irrigated with 20mL of mixed medicament in each scheme, one group is inoculated with phytophthora nicotianae after 5 days, the other group is inoculated with phytophthora nicotianae, the disease incidence condition is investigated according to the standard GB/T23222-2008, and the results are shown in Table 6:

TABLE 6

Scheme(s)	Tobacco black shank control effect (%)	Tobacco root rot control (%)
			Scheme one	21.6%	17.4%
Scheme two	33.4%	35.3%
			Scheme three	18.7%	27.6%

As shown in Table 6, the control effect of the bacillus amyloliquefaciens YN48 scheme and the bacillus amyloliquefaciens GUMT319 scheme on tobacco black shank and tobacco root black rot is not more than 30%, and the control effect of the bacillus amyloliquefaciens X60 scheme on tobacco black shank and tobacco root black rot is not more than 40%, so that the control effect is very limited.

From the test results, the bacillus amyloliquefaciens which has good control effect on the black shank or the black root rot at present has poor control effect on the black shank and the black root rot of the tobacco after being combined with the streptomyces oxysporum WS-29246 and the frost-methyl manganese zinc.

Test example 3

After obtaining the results of test example 2, the inventors hypothesized that antagonism between strains may lead to a decrease in control efficacy. Based on this guess, the inventors conducted an inter-strain antagonism test. In the test, antagonism among strains is explored through a flat plate cross scribing method, and the growth condition of the strains at the cross points is observed. Antagonism between microorganisms refers to the growth and metabolic activity of one microorganism that exerts inhibitory, interfering or deleterious effects on other microorganisms, resulting in the growth being affected.

In addition to the strains used in experiments 1 and 2, this experiment further examined Bacillus subtilis (accession number CGMCC NO: 10248), Pseudomonas glanadensis PF3402 (accession number CCTCC NO: M2018545), Bacillus amyloliquefaciens GUMT319 (accession number CCTCC NO: M2018872), Bacillus amyloliquefaciens F11 (obtained by gift), and Bacillus amyloliquefaciens YN48 (obtained from microbial fermentation engineering research center, Inc. of Yunnan province).

In the test, the adopted preservation number of the bacillus subtilis is CGMCC No. 10248, and the bacillus subtilis is disclosed in Chinese patent of microbial agent for resisting both tobacco root rot and black shank and a preparation method and application thereof (publication No. CN 110511891A); the adopted preservation number of the pseudomonas glaradida PF3402 is CCTCC NO: m2018545, published in Chinese patent "a strain of Pseudomonas glanadensis capable of preventing and treating tobacco black shank and root black rot simultaneously and having growth promoting effect" and its application "(CN 109136154A); the adopted collection number of the bacillus amyloliquefaciens GUMT319 is CCTCC NO: m2018872, published in Chinese patent "Bacillus amyloliquefaciens GUMT319 and its application" (CN 109504639A); the adopted bacillus amyloliquefaciens F11 is a strain in an article published by von Rong (von Rong, Liuli, Chenhai reciting, Yangyoshu, Cynanchum lechleri and Dingxifeng. research on antifungal activity of the bacillus amyloliquefaciens F11 [ J ]. journal of agricultural resources and environment, 2021,38(05): 849-; the bacillus amyloliquefaciens YN48 is purchased from a limited company of the research center of microbial fermentation engineering in Yunnan province, and related reports are published in articles published by Liujian gold (Liujian gold, Liuzi instrument, Wangchao, Zhanyan, Xuyanpeng, Lujie, Luoshan and Haoyouqiu. the bacillus amyloliquefaciens YN48 is matched with a bactericide to prevent and treat tobacco black shank research [ J ]. the university of Yunnan university of agriculture (Nature science), 2020,35(02):361 + 365+ 370.). The bacterial strains are all bacterial strains with good control effect on black shank and/or black root rot.

As shown in Table 7, except for Bacillus amyloliquefaciens cd5bc, Streptomyces oxysporum WS-29246 was antagonistic to other strains.

TABLE 7

Note: in the table, "-" indicates no antagonism, and "+" indicates antagonism

As is clear from Table 7, it is found that the antagonistic action of Bacillus amyloliquefaciens F11, Bacillus amyloliquefaciens YN48 and Streptomyces oxysporum WS-29246 is not likely to be the reason why it is difficult to obtain a good control effect in the manner of test example 1 by mixing the Streptomyces oxysporum WS-29246 with the above-mentioned both bacteria. The mechanism is that the antagonism inhibits the growth of the bacteria or prevents the generation of some important metabolites, thereby reducing the control effect of the corresponding strains. Due to the fact that Streptomyces oxysporum WS-29246 and CGMCC NO: 10248. CCTCC NO: m2018545, CCTCC NO: m2018872 has antagonism, and the control effect is necessarily reduced after being mixed respectively, so that the inventor does not perform a specific control effect test.

Test example 4

The inventors further examined the case where the 72% wettable powder of methoprene and manganin was replaced with another drug in the test example 1.

As shown in table 8, when the 72% wettable pulvis Fumi Carbonisatus-Mandarin was replaced by 1500-fold diluted Fluorubitril-Pericarb suspension (comparative drug group 1) or 1500-fold diluted wettable thiophanate-methyl powder (comparative drug group 2), the control effect was significantly reduced.

TABLE 8

Scheme(s)	Tobacco black shank control effect (%)	Tobacco root rot control (%)
			Comparative drug group 1	53.4	43.1
Comparative drug group 2	59.5	53.2

The inventor investigates the inhibition of 72% methyloxanil-manganin wettable powder, fluorine bacterium-propamocarb suspending agent and thiophanate-methyl wettable powder to the strain in the test example 3, and takes MIC (minimum inhibitory concentration) as an investigation standard. As shown in Table 9, the MIC of the 72% wettable powder of methyl frost and manganese zinc to Bacillus amyloliquefaciens cd5bc and Streptomyces oxysporum WS-29246 is more than 5000 mug/mL, but the MIC of the fluorine bacterium and propamocarb suspending agent and the wettable powder of thiophanate-methyl to Bacillus amyloliquefaciens cd5bc and Streptomyces oxysporum WS-29246 are both small, and the bactericidal activity is strong. Therefore, it can be seen that after 72% of the wettable pulvis methyloxanil and manganese-zinc is replaced on the basis of the test example 1, the bacillus amyloliquefaciens cd5bc and the streptomyces oxysporum WS-29246 are greatly inhibited, which may be partially responsible for the lower control effect of the comparative drug group 1 and the comparative drug group 2.

TABLE 9

Note: in the table, "> 100 and < 500" indicates that the MIC is between 100 and 500. mu.g/mL, and no further experiment is performed to determine the specific MIC, since it is not necessary to determine the exact value.

Test example 5

On the basis of the experimental example 2, the inventor inspects the influence of the first scheme to the third scheme on the cadmium accumulation and the lysine content of the tobacco, and finds that the first scheme, the second scheme and the third scheme have no influence on the cadmium accumulation and the lysine, and the related data have no statistical difference.

Test example II summary

The inventor unexpectedly finds that after the bacillus amyloliquefaciens cd5bc, the streptomyces oxysporum WS-29246 and the cream-a-methyl-manganese-zinc are combined, the composition has remarkable control effect on tobacco black shank and tobacco black root rot, and the dosage of the cream-a-manganese-zinc can be extremely low. This unexpected result was discovered by the inventors in their work to try to utilize whether Streptomyces oxysporum has a preventive effect against related blight of tobacco. To the best of the inventor, no report exists in the prior art for preventing and treating related epidemic diseases of tobacco by using streptomyces oxysporum.

Encouraged by the unexpected discovery, the inventor researches the combination of Streptomyces oxysporum WS-29246 and other reported strains with control efficacy on tobacco black shank and black root rot and the cream-A-Mn-Zn, and examines the control efficacy of the combination on the tobacco black shank and the black root rot. Unfortunately, however, although selected strains have been reported to have control efficacy, the control efficacy after combination is very limited. The inventors speculate that antagonism between strains or inhibition of the selected strains by drugs may be responsible, and confirmed this by the present invention through test examples 3 and 4.

As shown in the second test example of the invention, in the research process, the composition not only has good control effect on tobacco black shank and black root rot, but also can well improve the agronomic characters of tobacco. Particularly unexpectedly, when the inventor detects the related content in the tobacco, the composition of the invention is also found to effectively reduce the accumulation of heavy metal cadmium and reduce the content of lysine.

The research of screening special strains to reduce heavy metal accumulation is still in the preliminary stage at present, and related reports are few. Many studies have been made mainly on the basis of the regulation of the pH in the soil by specific strains to modify the uptake of heavy metals by crops, such as Wangxin ^[29] Screening an alcaligenes Bacillus XT-4 which can obviously increase the pH value of rhizosphere soil and CaCl in the soil ₂ The content of the extracted cadmium is reduced, so that the content of heavy metal Cd on the overground part of the pakchoi is reduced; there are reports of the Xuhong Master thesis of the university of Hunan industry based on the same principle ^[30] . There have been studies on the regulation of heavy metal content in crops by screening heavy metal-fixing bacteria and reducing the effectiveness and migratory ability of heavy metals in soil, such as Sunleni ^[31] A technology of cadmium tolerance immobilized bacteria Pseudomonas sp.YM 4 in inhibiting wheat cadmium absorption is reported.

However, through experiments, the composition of the second test example of the present invention could not significantly increase the pH of the soil, and whether the composition of the present invention could produce the effect similar to that of heavy metal immobilized bacteria, was still to be further studied.

The content of amino acids in tobacco is influenced by variety, region, different parts and cultivation measures, and the content is shown in Zhao Tian Master thesis "influence of different cultivation and modulation measures on amino acid content of burley tobacco and flue-cured tobacco ^[32] Is described in detail in (1). At present, the reports of using microorganisms to regulate lysine in tobacco are less, and the regulation is mainly carried out by changing the cultivation and baking modes and modifying genes, such as Chinese patent 'cultivation and baking method for reducing the lysine content of flue-cured tobacco' (CN 109804879A) and Wang Yi Tung's paper' increase of lysine content in transgenic tobacco ^[33] . As shown in the embodiment of the invention, the lysine in the tobacco can be effectively reduced, so that the ammonia in the tobacco can be reduced, and the damage of the tobacco to human bodies can be reduced. Since the research of regulating and controlling specific amino acids in tobacco by using microorganisms has not been carried out on a large scale, the theoretical mechanism in the aspect needs to be further investigated.

[29] Wangxin, the research on the screening, identification and prevention and control of vegetable cadmium accumulation effect of Alcaligenes Bacillus XT-4 [ D ]. Nanjing agriculture university, 2019.

[30] Xuhong, influence and mechanism of the alkaline-producing microbial compound inoculant on cadmium accumulation of rice are explored to [ D ]. Hunan university of industry, 2021.

[31] Sunleni, Guo Ying Xue Ting, Hou Jie, Yang Zhang, Chen Meng, Tianwei, cadmium tolerance fixed bacteria screening and control effect on cadmium absorption of different varieties of wheat [ J ] agricultural environmental science reports 2020,39(09): 1878-.

[32] Effect of different cultivation and modulation measures on burley tobacco and flue-cured tobacco amino acid content [ D ] university of river south agriculture, 2012.

[33] Wang Ying, Zheng jin Gui, Xie Gui Zi increase content of lysine in transgenic tobacco [ J ]. application and environmental biology report, 2005(01): 32-35.

Claims

1. A microbial soil improvement microbial inoculum for preventing and treating tobacco blight is characterized by consisting of 100-120 mL of Streptomyces oxysporum WS-29246 culture solution and 150-180 g of Bacillus amyloliquefaciens cd5bc rape straw leavening;

2. The microbial soil improvement inoculum of claim 1, wherein the concentration of Streptomyces oxysporum WS-29246 in the culture solution is 1 x 10 ⁶ cfu/mL~1×10 ⁷ cfu/mL。

3. The microbial soil improvement inoculant according to claim 2, wherein the bacillus amyloliquefaciens cd5bc rape straw leavening is prepared by crushing rape straw and using the crushed rape straw as a fermentation substrate.

4. The microbial soil improvement inoculant according to claim 3, wherein the Bacillus amyloliquefaciens cd5bc rape straw fermented product is inoculated by adding 5ml of Bacillus amyloliquefaciens cd5bc culture solution into 100g of the crushed rape straw when inoculating Bacillus amyloliquefaciens cd5bc, wherein the bacterial concentration of the Bacillus amyloliquefaciens cd5bc culture solution is 1 x 10 ⁶ cfu/mL~1×10 ⁷ cfu/mL。

5. The microbial soil improvement inoculant according to claim 4, wherein a nutrient solution is further added during preparation of the bacillus amyloliquefaciens cd5bc rape straw leavening, so that the water content is 65-70%; the formula of the nutrient solution is as follows: NH (NH) ₄ NO ₃ 1.2g，KH ₂ PO ₄ 1.5g，KCl 0.6g，ZnSO ₄ ·7H ₂ O 0.04g，Ca(NO ₃ ) ₂ ·4H ₂ O 3g，MgSO ₄ ·7H ₂ O 1g，FeSO ₄ ·7H ₂ O1 g, disodium ethylene diamine tetraacetate 0.6g, KI 0.2g, MnSO ₄ 0.1g，CuSO ₄ 0.01g，CoCl ₂ 0.01g, 0.03g of boric acid, 0.01g of sodium molybdate and 370mL of purified water.

6. The microbial soil improvement inoculum according to any one of claims 1 to 5, wherein the culture solution of Streptomyces oxysporum WS-29246 is obtained by inoculating Streptomyces oxysporum WS-29246 and fermenting, and the components of the culture medium are as follows: 100g of cane sugar, 10g of glucose, 0.1g of casamino acid, 5g of yeast extract powder, 21g of propanesulfonic acid and K ₂ SO ₄ 0.25g，MgCl ₂ ·6H ₂ O10 g, trace element 1mL, water 1000mL, pH = 7.0; wherein the microelement formula is MnSO ₄ ·7H ₂ O 100mg，CuSO ₄ ·7H ₂ O 50mg，ZnSO ₄ ·7H ₂ O 100mg，CoCl ₂ 100mg, 100mL of purified water.

7. A preparation method of a microbial soil improvement microbial inoculum for preventing and treating tobacco blight, which is characterized in that the microbial soil improvement microbial inoculum is the microbial soil improvement microbial inoculum of any one of claims 1 to 6, and the preparation method comprises the step of mixing a bacillus amyloliquefaciens cd5bc rape straw fermentation product and a streptomyces oxysporum WS-29246 culture solution.

8. Use of a microbial soil improvement inoculant according to any one of claims 1 to 6 as a soil conditioner for the control of tobacco root rot and black shank.