Corn stover fermentation product and use of corn stover fermentation product to promote plant growth

Abstract

The application discloses a corn stalk fermentation product, which is prepared by solid fermentation and leaching with corn stalk as a substrate, and by simultaneously introducing Streptomyces hygroscopicus B04 and Guizhou Trichoderma NJAU4742 as functional microorganisms; the strain of Streptomyces hygroscopicus B04 has a preservation number of CGMCC NO.9918; and the strain of Guizhou Trichoderma NJAU4742 has a preservation number of CGMCC No.12166. In the present application, corn stalk is used as a substrate, and functional substances required for growth are generated by decomposing the stalk in the co-fermentation process, so that the fermentation process is better performed, and the biomass of Streptomyces hygroscopicus B04 is significantly increased after fermentation, and the order of magnitude reaches 10 9 million / g of stalk. Meanwhile, the metabolites can significantly promote the growth of plants, and the plant biomass is significantly increased. The application also discloses application of the corn stalk fermentation product in promoting the growth of plants or in preparing a fertilizer or preparation for promoting the growth of plants.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of microorganisms, and relates to a corn stalk fermentation product, in particular to a fermentation product obtained by jointly fermenting agricultural waste corn stalks with Streptomyces hygroscopicus B04 and Trichoderma guizhouense NJAU4742, and application of the corn stalk fermentation product in promoting plant growth. BACKGROUND

[0002] Microbial fermentation refers to a process of using microorganisms to convert raw materials into products required by humans through specific metabolic pathways under suitable conditions. Microbial fermentation technology is one of important means for functional microorganisms to synthesize certain or certain types of compounds, and has a wide range of applications in medicine, food, and agriculture and many other fields. In the past, most compounds were synthesized by chemical synthesis and extracted from plants, which could meet the demand to a large extent, but would inevitably cause serious damage to the environment and ecology. With the progress of society and the urgent demand of people for high quality of life, microbial fermentation technology has become a research hotspot and gradually replaced the above two means.

[0003] Straw is one of agricultural wastes and is also one of recognized important biomass resources. There are many nitrogen, phosphorus, potassium and other essential nutrients for crops in straw. The complex structure and composition of straw lead to its difficult degradation and utilization, and straw resource utilization is faced with many problems, such as low product value, limited application range, and easy secondary pollution. The utilization of straw resources is conducive to solving the problems of solid waste pollution and sustainable development, and in recent years, the use of microorganisms to degrade straw has become the focus of many researchers.

[0004] Straw can be utilized by microorganisms because some substances contained in straw help microorganisms grow or improve their ability to produce antagonistic substances. There are many kinds of actinomycetes, and the most commonly used is Streptomyces, which produces enzymes that can degrade lignin, cellulose, hemicellulose and the like. Actinomycetes produce secondary metabolites to affect the normal life activities of pathogenic bacteria, achieve disease control, and promote plant growth and yield and improve quality. Trichoderma produces a large amount of extracellular cellulase to efficiently degrade lignocellulose, has the effects of high-efficiency antagonism to plant pathogenic bacteria, induction of plant resistance, and promotion of plant growth. The use of microorganisms to regulate plant growth and development is considered to be a key technology for reducing agricultural fertilizer input and increasing nutrient utilization rate.

[0005] Functional strains and fermentation substrates are key factors affecting the effect of directional fermentation. Through selecting functional strains with strong degradation ability and functional substance production ability and combining with cheap and easily obtained fermentation substrates of straw, fermentation products with large biomass and rich functional substances are obtained. By investigating the degradation ability of different strains or combinations and the promoting effect of straw fermentation extract on crops, suitable substrate resources for the combination of beneficial bacteria and degrading bacteria are provided, high value-added utilization of straw is realized, and theoretical basis and technical support for realizing stable interaction of degrading bacteria and beneficial bacteria and promoting crop growth are provided. SUMMARY

[0006] The present application uses different crop straws as substrates, Streptomyces hygroscopicus B04 and Guizhou Trichoderma NJAU4742 as functional microorganisms, explores the influence of different crop straws and different fermentation methods on the biomass of Streptomyces hygroscopicus B04, and finds that the biomass of Streptomyces hygroscopicus B04 increases most significantly after fermentation with corn straw as substrate and by using the co-fermentation method. The present inventors further explore the growth-promoting effect of corn straw fermentation products of Streptomyces hygroscopicus B04 and Guizhou Trichoderma NJAU4742 on plants, and analyze the functional substances that play a key role in promoting growth. The present inventors find that: after corn straw is co-fermented by Streptomyces hygroscopicus B04 and Guizhou Trichoderma NJAU4742, the growth-promoting related secondary metabolite indole acetic acid and iron carrier plant in the extract are significantly enriched, and can significantly promote the growth of tomato plants. It shows that Streptomyces hygroscopicus B04 and Guizhou Trichoderma NJAU4742 can efficiently decompose corn straw and produce abundant functional substances for promoting crop growth, so that the agricultural waste corn straw realizes resource utilization.

[0007] The purpose of the present application is realized by the following technical solutions:

[0008] A corn straw fermentation product, wherein the corn straw fermentation product is prepared by solid fermentation and extraction with corn straw as substrate, and Streptomyces hygroscopicus B04 and Guizhou Trichoderma NJAU4742 as functional microorganisms.

[0009] Streptomyces hygroscopicus B04 is classified and named as Streptomyces hygroscopicus, and was preserved in China General Microbiological Culture Collection Center on November 2, 2014, located at No. 1, Beichen West Road, Yard 3, Chaoyang District, Beijing, with a strain preservation number of CGMCC NO. 9918. Streptomyces hygroscopicus B04 is a known microorganism, which is recorded in Chinese patent application CN 104403976 A.

[0010] Trichoderma guizhouense, was preserved in China General Microbiological Culture Collection Center, located at No. 1, Beichen West Road, Haidian District, Beijing, on April 11, 2016, and the accession number is CGMCC No. 12166. The Trichoderma guizhouense NJAU4742 is a known microorganism, which is recorded in Chinese patent application CN 106085871 A.

[0011] The corn stalk fermentation product contains IAA and iron carrier.

[0012] The variety of the corn stalk is not limited.

[0013] Another object of the present application is to provide a preparation method of the corn stalk fermentation product, which comprises: drying, grinding, screening and sterilizing the corn stalk, inoculating Streptomyces hygroscopicus B04 spore solution and Trichoderma guizhouense NJAU4742 spore solution, adjusting the water content of the corn stalk powder to 70-80% by using a carbon-free culture medium, performing solid fermentation for 12-16 days, and then extracting with water, filtering and removing bacteria to obtain the fermentation product.

[0014] Preferably, the water content of the corn stalk powder is adjusted to 75%.

[0015] Preferably, the solid fermentation time is 14 days.

[0016] The concentration of the Streptomyces hygroscopicus B04 spore solution is 10 5 -10 8 mL of the Streptomyces hygroscopicus B04 spore solution is inoculated per 1-5 g of the corn stalk; and the concentration of the Trichoderma guizhouense NJAU4742 spore solution is 10 5 -10 8 mL of the Trichoderma guizhouense NJAU4742 spore solution is inoculated per 1-5 g of the corn stalk.

[0017] Preferably, the concentration of the Streptomyces hygroscopicus B04 spore solution is 10 7 mL of the Streptomyces hygroscopicus B04 spore solution is inoculated per 1.2 g of the corn stalk; and the concentration of the Trichoderma guizhouense NJAU4742 spore solution is 10 7 mL of the Trichoderma guizhouense NJAU4742 spore solution is inoculated per 1.2 g of the corn stalk.

[0018] The Streptomyces hygroscopicus B04 spore solution is prepared by the following method: picking a single colony of Streptomyces hygroscopicus B04 in oat liquid medium, and placing it in a shaking bed at 20-30℃, 150-170 r·min -1Culturing for 5-7 days to obtain the Streptomyces hygroscopicus B04 bacterial suspension; the Streptomyces hygroscopicus B04 bacterial suspension is coated on oat solid culture medium, and cultured at 20-30 DEG C for 5-7 days; spore liquid is washed off with sterile water, filtered through two layers of sterile gauze, and adjusted to a target concentration with sterile water to obtain the Streptomyces hygroscopicus B04 spore liquid.

[0019] The Trichoderma guizhouense NJAU4742 spore liquid is obtained by the following method: the Trichoderma guizhouense NJAU4742 is inoculated on a PDA plate, placed in a constant temperature incubator, and cultured at 30 DEG C for 7 days; spore liquid is washed off with sterile water, filtered through two layers of sterile gauze, and adjusted to a target concentration with sterile water to obtain the Trichoderma guizhouense NJAU4742 spore liquid.

[0020] The environmental temperature of the solid fermentation (i.e. the solid fermentation after the inoculation of the Streptomyces hygroscopicus B04 and the Trichoderma guizhouense NJAU4742) is 20-30 DEG C, and the relative humidity of air is 75%-85%.

[0021] Preferably, the corn stalks are added with water to extract at a mass ratio of corn stalks to water of 1:20-1:40.

[0022] The extraction conditions are as follows: the temperature is 20-30 DEG C, the rotation speed is 150-170 r·min -1 The extraction is performed for 0.5-1 h.

[0023] Another object of the present application is to provide the use of the corn stalk fermentation product in promoting plant growth.

[0024] The plant is tomato.

[0025] Another object of the present application is to provide a method for promoting plant growth, which comprises: when the tomato seedlings reach the stage of 2-4 true leaves, the corn stalk fermentation product is applied by root irrigation, and the application amount of the corn stalk fermentation product is 10-30 mL per tomato.

[0026] Another object of the present application is to provide the use of the corn stalk fermentation product in preparing a fertilizer or preparation for promoting plant growth.

[0027] The present application has the following beneficial effects:

[0028] In the present application, corn stalks are used as substrates, and a fermentation product is obtained by the co-fermentation of the Streptomyces hygroscopicus B04 and the Trichoderma guizhouense NJAU4742; in the co-fermentation process, the stalks are degraded by the Trichoderma guizhouense NJAU4742 into functional substances that can provide growth for the Streptomyces hygroscopicus B04, so that the fermentation process can be better performed.

[0029] After the fermentation is completed, the number of the Streptomyces hygroscopicus B04 reaches the order of magnitude of 10 90.5 g straw; at the same time, the metabolites after fermentation can play a significant role in promoting growth, promoting the growth of plants, and significantly increasing plant biomass. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 IAA production of each fermentation method.

[0031] Figure 2 siderophore production of each fermentation method.

[0032] Figure 3 Effect of each fermentation method on the root length of germinated seeds.

[0033] Figure 4 Effect of each fermentation method on the plant height of tomato.

[0034] Figure 5 Effect of each fermentation method on the stem thickness of tomato.

[0035] Figure 6 Effect of each fermentation method on the SPAD value.

[0036] Figure 7 Effect of each fermentation method on the dry fresh weight of tomato aboveground.

[0037] Figure 8 Effect of each fermentation method on the dry fresh weight of tomato underground.

[0038] Figure 9 Effect of each fermentation method on the root configuration of tomato: total root length, root area, root volume, and root tip number.

[0039] BIOLOGICAL MATERIAL PRESERVATION INFORMATION

[0040] B04, classified as Streptomyces hygroscopicus, was preserved in the China General Microbiological Culture Collection Center, located at No. 1, Xiliujia Hutong, Beichen West Road, Chaoyang District, Beijing, on November 2, 2014, with a strain preservation number of CGMCC NO. 9918.

[0041] NJAU4742, classified as Trichoderma guizhouense, was preserved in the China General Microbiological Culture Collection Center, located at No. 1, Xiliujia Hutong, Beichen West Road, Chaoyang District, Beijing, on April 11, 2016, by the Institute of Microbiology, Chinese Academy of Sciences, with a strain preservation number of CGMCC No. 12166. DETAILED DESCRIPTION

[0042] The technical solutions of the present application are further described below in combination with specific embodiments.

[0043] Example 1

[0044] Preparation of spore solution of Streptomyces hygroscopicus B04: Streptomyces hygroscopicus B04 strain stored in a-80℃ refrigerator was streaked on oat solid culture medium plates and placed in a constant temperature incubator for culture at 28℃ until single colonies appeared; single colonies on the oat solid culture medium plates were picked and placed in liquid oat liquid culture medium in a shaker, at a temperature of 28℃ and a rotation speed of 170r·min-1 -1 for 7 days to obtain Streptomyces hygroscopicus B04 bacterial suspension; the Streptomyces hygroscopicus B04 bacterial suspension was spread on oat solid culture medium and cultured at 28℃ for 7 days, and spore solution was washed off with sterile water, filtered with two layers of sterile gauze into a 2mL centrifuge tube, and a certain amount of spore solution was taken to a hemocytometer for counting, diluted with sterile water to obtain Streptomyces hygroscopicus B04 spore solution with a spore concentration of 10 7 individuals / mL, which was collected in a centrifuge tube for later use.

[0045] Preparation of spore solution of Trichoderma guizhouense NJAU4742: the stored Trichoderma guizhouense NJAU4742 was point-inoculated on PDA plates and placed in a constant temperature incubator for culture at 30℃ for 7 days, and spore solution was washed off with sterile water, filtered with two layers of sterile gauze into a 2mL centrifuge tube, and a certain amount of spore solution was taken to a hemocytometer for counting, diluted with sterile water to obtain Trichoderma guizhouense NJAU4742 spore solution with a spore concentration of 10 7 individuals / mL, which was collected in a centrifuge tube for later use.

[0046] As shown in Table 1, corn stalks were fermented in different ways.

[0047] Table 1. Different fermentation methods

[0048]

[0049] Influence of corn stalks and fermentation methods on the biomass of beneficial bacteria

[0050] Stalks: corn stalks, chrysanthemum stalks, jerusalem artichoke stalks.

[0051] Corn stalks: corn plants were taken, roots and leaves were removed, dried, ground into powder, and passed through a 20-mesh sieve, 1.2g of stalks were placed in each centrifuge tube, sealed, sterilized at 121℃ for 20min, and used later.

[0052] Chrysanthemum stalks: dried, ground into powder, and passed through a 20-mesh sieve, 1.2g of stalks were placed in each centrifuge tube, sealed, sterilized at 121℃ for 20min, and used later.

[0053] Jerusalem artichoke straw: dried, ground, sieved to 20 mesh, 1.2 g of straw was put into each centrifuge tube, sealed, sterilized at 121℃ for 20 min, and used later.

[0054] Fermentation mode: single strain fermentation of S. hygroscopicus B04 for 14 days (A1); relay fermentation of S. hygroscopicus B04 for 7 days after Guizhou Trichoderma NJAU4742 was fermented for 7 days (A2); simultaneous inoculation of Guizhou Trichoderma NJAU4742 and S. hygroscopicus B04, and co-fermentation for 14 days (A3); single strain fermentation of Guizhou Trichoderma NJAU4742 for 14 days (A4).

[0055] Single strain fermentation (A1): 1.20 g of straw powder was weighed into a 50 mL centrifuge tube, sealed with a sealing film, sterilized at a temperature of 121℃ for 20 min, and dried; in a clean bench, 100 μL of S. hygroscopicus B04 spore solution (spore concentration of 10 7 individual / mL) was inoculated, and the moisture content was adjusted to 75% with carbon-free medium, and placed in an incubator at an air relative humidity of 80% and a temperature of 30℃ for static fermentation and culture for 14 days; the centrifuge tube was taken out, 24 mL of sterile water was added, and extraction was carried out at a temperature of 28℃ and a rotation speed of 170 r·min -1 for 1 h.

[0056] Relay fermentation (A2): 1.20 g of straw powder was weighed into a 50 mL centrifuge tube, sealed with a sealing film, sterilized at a temperature of 121℃ for 20 min; in a clean bench, 100 μL of Trichoderma spore solution (spore concentration of 10 7 individual / mL) was inoculated, and the moisture content was adjusted to 75% with carbon-free medium, and placed in an incubator at an air relative humidity of 80% and a temperature of 30℃ for static fermentation and culture for 7 days; the centrifuge tube was taken out from the incubator, and 100 μL of S. hygroscopicus B04 spore solution (spore concentration of 10 7 individual / mL) was inoculated in a clean bench, and placed in an incubator at an air relative humidity of 80% and a temperature of 30℃ for static fermentation and culture for 7 days; after the relay fermentation was completed, the centrifuge tube was taken out, 24 mL of sterile water was added, and extraction was carried out at a temperature of 28℃ and a rotation speed of 170 r·min -1 for 1 h.

[0057] Co-fermentation (A3): 1.20 g of straw powder was weighed into a 50 mL centrifuge tube, sealed with a sealing film, sterilized at a temperature of 121℃ for 20 min; in a clean bench, 100 μL of S. hygroscopicus B04 spore solution (spore concentration of 10 7 individual / mL) and 100 μL of Guizhou Trichoderma NJAU4742 spore solution (spore concentration of 10 7centrifuge tube, 24 mL sterile water was added, and the centrifuge tube was placed in a shaking incubator at a temperature of 28℃ and a rotation speed of 170 r·min-1for 1 h. -1 centrifuge tube, 24 mL sterile water was added, and the centrifuge tube was placed in a shaking incubator at a temperature of 28℃ and a rotation speed of 170 r·min-1for 1 h.

[0058] Single-bacterium fermentation (A4): 1.20 g of straw powder was weighed into a 50 mL centrifuge tube, which was sealed with a sealing film and sterilized at a temperature of 121℃ for 20 min; in a clean bench, 100 μL of Guizhou Trichoderma NJAU4742 spore solution (spore concentration was 10 7 centrifuge tube, 24 mL sterile water was added, and the centrifuge tube was placed in a shaking incubator at a temperature of 28℃ and a rotation speed of 170 r·min-1for 1 h. -1 centrifuge tube, 24 mL sterile water was added, and the centrifuge tube was placed in a shaking incubator at a temperature of 28℃ and a rotation speed of 170 r·min-1for 1 h.

[0059] After the end of the fermentation mode A1, A2, A3 extraction, the following treatment was carried out: standing for half an hour, taking the supernatant, and filtering the supernatant with sterile gauze. The filtrate was diluted and coated on oat solid medium (added 50 μg / mL of cycloheximide) plates, and the plates were cultured at a temperature of 30℃ and an air relative humidity of 80% for about 5 days, and counted.

[0060] The effects of fermentation modes A1, A2, A3 on the biomass of Streptomyces hygroscopicus B04 were analyzed, and the results are shown in Table 2. It can be seen that, compared with chrysanthemum straw and jerusalem artichoke straw, under the same fermentation mode, the biomass of Streptomyces hygroscopicus B04 increased significantly after fermentation with corn straw as the substrate. Compared with the other two fermentation modes, the biomass of Streptomyces hygroscopicus B04 increased significantly after 14 days of co-fermentation with Guizhou Trichoderma NJAU4742 (A3), and the effective viable count of Streptomyces hygroscopicus B04 could reach 1.1×10 9 The results show that Streptomyces hygroscopicus B04 and Guizhou Trichoderma NJAU4742 have good corn straw degradation capacity, and can decompose straw to produce functional substances needed for growth during co-fermentation, thereby better fermentation, and the biomass of Streptomyces hygroscopicus B04 increases significantly after co-fermentation. Therefore, it is determined that corn straw is used as the substrate, and the fermentation mode (A3) is the best fermentation mode.

[0061] Table 2. Effects of different straws and fermentation modes on the biomass of Streptomyces hygroscopicus B04

[0062]

[0063] Note: Different lowercase letters represent significant differences (P<0.05) among treatments.

[0064] Example 2

[0065] Effect of different fermentation methods on IAA production

[0066] The leaching liquor of the co-fermentation method (A3) was selected to determine the production of IAA and siderophore, and the single-bacterial fermentation (A1) and single-bacterial fermentation (A4) were selected for comparative analysis.

[0067] In Example 1, corn stalks were used as the substrate, and after the leaching of fermentation methods A1, A3 and A4 was completed, the following treatment was performed: standing for half an hour, taking the supernatant, filtering with a 0.22 μm sterile filter membrane, and obtaining sterile leaching liquor.

[0068] The level of indole acetic acid (IAA) in the sterile leaching liquor was determined by double antibody sandwich method. The detection principle is as follows: purified indole acetic acid (IAA) capture antibody was used to coat the microplate to prepare a solid phase antibody, indole acetic acid (IAA) was added to the coated microplate in turn, and then combined with HRP-labeled detection antibody to form an antibody antigen-enzyme-labeled antibody complex. After thorough washing, the substrate TMB was added for color development. TMB is converted to blue under the catalysis of HRP enzyme, and is converted to yellow under the action of acid. The color depth is positively correlated with the indole acetic acid (IAA) in the sample. The absorbance (OD value) was measured at 450 nm wavelength by an enzyme-labeled instrument, and the content of indole acetic acid (IAA) in the sample was calculated by a standard curve. The specific operation method is as follows: according to the reagent kit instructions, 40 μL of sample diluent was added to each well of the enzyme-labeled back plate, 10 μL of sterile leaching liquor was added, and blank control wells and standard wells (50 μL of standard was added to each well) were set. 100 μL of enzyme-labeled reagent was added to each well (except the blank well), then the enzyme-labeled back plate was sealed with a sealing film and incubated in a 37℃ constant temperature incubator for 60 min. After incubation, the sealing film was torn off, the liquid was poured out, and the wells were filled with washing solution, then the plate was left to stand for 30 s and the liquid was discarded. The wells were dried by repeating the above steps five times. 50 μL of color developing agent A was added to each well, followed by 50 μL of color developing agent B, which was mixed gently and then placed in a 37℃ constant temperature incubator to develop color for 15 min. Finally, 50 μL of stop solution was added to each well to terminate the color developing reaction. Then, the OD450 of each treatment was measured on an enzyme-labeled instrument with the blank well as the zero point to determine the auxin output of the sterile leaching liquor of the stalk fermentation.

[0069] The siderophore production was determined by the conventional laboratory method, i.e. CAS detection solution determination method. This method is based on the fact that the substances in the detection solution can bind with siderophore to produce a color reaction (Himpsl et al., 2019). The sterile extract solution and the CAS detection solution were mixed at a volume ratio of 1:1, and the mixture was allowed to stand for 1 h. The absorbance value at a wavelength of 630 nm was determined by an enzyme-labeled instrument, and the value A was obtained. The sterile MKB medium was used as a control, and the sterile MKB medium and the CAS detection solution were mixed at a volume ratio of 1:1, and the mixture was allowed to stand for 1 h. The absorbance value at a wavelength of 630 nm was determined by an enzyme-labeled instrument, and the value Ar was obtained. The relative content of siderophore (SU) was calculated according to the reference (Schwyn et al., 1987).

[0070] Siderophore activity unit (SU) = [(Ar-A) / Ar]x100

[0071] In the formula, SU represents the relative content of siderophore, A represents the detection value of the sterile extract solution, and Ar represents the control value.

[0072] It can be seen from Figure 1 , Figure 2 that the IAA content in the fermentation extract solution obtained by the co-fermentation method (A3) is 65.97 nmol / L, and the siderophore activity SU is 57.3%. Compared with the single-bacterium fermentation (A1) and (A4), the IAA content and the siderophore activity SU in the fermentation extract solution obtained by the co-fermentation method (A3) are significantly different.

[0073] Based on the data of the biomass of the target functional strain Streptomyces hygroscopicus B04, the IAA content of the fermentation liquid, and the siderophore activity SU, it is further determined that the co-fermentation method (A3) is the best.

[0074] Example 3

[0075] Effect of extract solutions obtained by different fermentation methods on seed germination

[0076] In Example 1, corn stalks were used as the substrate, and after the extraction of the fermentation methods (A1), (A3) and (A4) was completed, the following treatment was performed: the supernatant was obtained by standing for half an hour, filtering the supernatant with a 0.22 μm filter membrane, and obtaining the sterile extract solution.

[0077] Seeds: red dwarf tomato seeds.

[0078] The seeds were soaked in water for 3 hours, then disinfected with 5% sodium hypochlorite for 1 minute, and rinsed with ultrapure water for 6 times. The seeds were placed in a flat plate with 1 layer of filter paper (referred to as the first day of the experiment), and 5 mL of sterile extract obtained by different fermentation methods was added. 5 mL of sterile water was used instead of the extract as a blank control (CK). The number of germinated seeds in each culture dish was observed and recorded daily. After 5 days of the experiment, no new seeds germinated in all treatments, so the seed germination rate on the 5th day was calculated (the percentage of the number of germinated seeds to the number of test seeds, %). On the 14th day, the root length of the germinated seeds was measured using a vernier caliper.

[0079] As shown in Table 3, compared with the blank control (CK), the seed germination rates of each fermentation extract treatment (A1), (A3) and (A4) were slightly increased, indicating that the extract had no significant inhibitory effect on seed germination. As shown in Table 4, the root length of the tomato seeds treated with fermentation extract (A3) was about 27.10 mm, which was significantly higher than that of the control group, indicating that the extract (A3) had a significant promoting effect on the growth of tomato seed roots. Figure 3

[0080] Table 3. Effect of different fermentation methods on tomato seed germination rate

[0081]

[0082] Note: Different lowercase letters indicate significant differences between treatments (P<0.05).

[0083] Example 4

[0084] Pot experiment analysis of corn straw fermentation extract

[0085] In Example 1, corn straw was used as the substrate, and after the extraction of fermentation methods A1, A3 and A4, the following treatments were performed: standing for half an hour, taking the supernatant, filtering with a 0.22 μm filter membrane to obtain sterile extract.

[0086] Pot experiment analysis of corn straw fermentation extract

[0087] ​6 plants were randomly selected for each treatment, and each plant was separated into aboveground and underground parts. The height, stem diameter, SPAD value (relative chlorophyll content), and fresh and dry weight of the aboveground part were measured. The root architecture (total root length, root area, root volume, and root tip number) and fresh and dry weight of the underground part were measured. The results are shown in Figures 4-9 .

[0088] Figures 4-6 The height, stem diameter, and SPAD value of the plants treated with the extract obtained by different fermentation methods are shown. Figure 7 The fresh and dry weight of the aboveground part of the plants treated with the extract obtained by different fermentation methods is shown. Figure 8 The fresh and dry weight of the underground part of the plants treated with the extract obtained by different fermentation methods is shown. Figure 9 The root architecture of the plants treated with the extract obtained by different fermentation methods, including root area, total root length, root tip number, and root volume, is shown.

[0089] As shown in Figures 4-6 , the extract obtained by co-fermentation (A3) significantly increased the plant height, stem diameter, and SPAD value. As shown in Figure 7 and Figure 8 , the extract obtained by co-fermentation (A3) significantly increased the fresh and dry weight of the aboveground and underground parts of the plants. As shown in Figure 9 , the extract obtained by co-fermentation (A3) significantly increased the total root length, root area, root volume, and root tip number of the tomato plants.

[0090] In summary, corn straw was co-fermented with Streptomyces hygroscopicus B04 and Trichoderma guizhouense NJAU4742 (A3). The biomass of Streptomyces hygroscopicus B04 was significantly increased. The fermentation extract had strong IAA production capacity. The height, stem diameter, and root length of the plants treated with the fermentation extract were significantly increased. The fresh and dry weight of the aboveground and underground parts of the plants was significantly increased. The SPAD value of the plants was significantly increased. Therefore, the co-fermentation method (A3) was selected as the best fermentation method, and the extract obtained by this method can significantly promote the growth of tomatoes.

Claims

1. A fermented product of corn stalks, characterized in that: The aforementioned corn stalk fermentation product uses corn stalks as a substrate. The corn stalks are dried, ground, sieved, and sterilized. Simultaneously, spores of *Streptomyces boulardii* B04 and *Trichoderma guizhouense* NJAU4742 are inoculated. The moisture content of the corn stalk powder is adjusted to 70-80% using a carbon-free culture medium, and solid-state fermentation is carried out for 12-16 days. After fermentation, the product is extracted with water, filtered, and sterilized to obtain the fermentation product. The corn stalk fermentation product contains IAA and iron carriers. Streptomyces hygroscopicus B04, classified and named Streptomyces hygroscopicus Streptomyces hygroscopicus The strain preservation number is CGMCC NO.9918; *Trichoderma guiyuanensis* NJAU4742, and its classification name is *Trichoderma guiyuanensis*. Trichoderma guizhouense The strain has the CGMCC No. 12166 preservation number.

2. A method for preparing the fermentation product of corn stalks according to claim 1, characterized in that: include: Corn stalks are dried, ground, sieved, and sterilized. Simultaneously, spores of *Streptomyces boulardii* B04 and *Trichoderma guizhouense* NJAU4742 are inoculated. The moisture content of the corn stalk powder is adjusted to 70-80% using a carbon-free culture medium, and solid-state fermentation is carried out for 12-16 days. After fermentation, the powder is extracted with water, filtered, and sterilized to obtain the fermentation product.

3. The method for preparing corn straw fermentation products according to claim 2, characterized in that: The concentration of the spore solution of *Streptomyces hygroscopicus* B04 was 10. 5 Cells / mL ~ 10 8 For each 1–5 g of corn stalks, inoculate with 0.1–2 mL of *Streptomyces boulardii* B04 spore solution; for *Trichoderma guizhouense* NJAU4742 spore solution, the concentration is 10. 5 Cells / mL ~ 10 8 0.1-2 mL of Trichoderma Guizhouensis NJAU4742 spore solution was inoculated per 1-5 g of corn stalks.

4. The method for preparing corn straw fermentation products according to claim 3, characterized in that: The concentration of the spore solution of *Streptomyces hygroscopicus* B04 was 10. 7 100 μL of *Streptomyces boulardii* B04 spore solution was inoculated per 1.2 g of corn stalks; the concentration of *Trichoderma guizhouense* NJAU4742 spore solution was 10... 7 100 μL of Trichoderma Guizhouensis NJAU4742 spore solution was inoculated with 1.2 g of corn stalks per mL.

5. The method for preparing corn straw fermentation products according to claim 2, characterized in that: The ambient temperature for solid-state fermentation is 20–30°C, and the relative humidity is 75%–85%.

6. The method for preparing corn straw fermentation products according to claim 2, characterized in that: Add water for extraction at a mass ratio of corn stalks to water of 1:20 to 1:

40.

7. The method for preparing corn straw fermentation products according to claim 2 or 6, characterized in that: The extraction conditions are: a temperature of 20–30°C and a rotation speed of 150–170 r / min. -1 Soak for 0.5–1 hour.

8. The application of the corn stalk fermentation product according to claim 1 in promoting plant growth.

9. The application of the corn stalk fermentation product according to claim 1 in the preparation of fertilizers or preparations that promote plant growth.

10. A method for promoting plant growth, characterized in that: include: When the tomato seedlings reach the stage of 2-4 true leaves, the fermented corn stalk product described in claim 1 is applied by root irrigation, and the amount of fermented corn stalk product applied is 10-30 mL per tomato plant.

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