A method to promote methane oxidation, nitrogen fixation, and rice growth
By forming an iron film on the root surface of rice roots and working synergistically with methanogenic bacteria, the problems of methane emissions and nitrogen fertilizer use in paddy fields have been solved, promoting rice growth and reducing greenhouse gas emissions, thus achieving environmentally friendly rice production.
Patent Information
- Application Number
- CN202410120545.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-01-29
- Publication Date
- 2025-12-02
- Estimated Expiration
- 2044-01-29
AI Technical Summary
In existing technologies, methane emissions from paddy fields and the use of nitrogen fertilizers cause environmental pollution problems, and the increase in rice yield is limited.
By forming an iron film on the root surface of rice seedlings and transplanting them into an environment containing methanogenic bacteria, methane oxidation and nitrogen fixation are promoted, reducing the use of nitrogen fertilizer.
It improved the growth rate, polysaccharide content, and protein content of rice, reduced methane emissions from paddy fields, and achieved environmentally friendly rice production.
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Figure CN117814103B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the technical field of microbial enrichment and rice yield promotion, specifically to a method for promoting methane oxidation and nitrogen fixation and rice growth. Background Technology
[0002] Methane plays a vital role in human production and daily life as an energy source, but it is also the second largest greenhouse gas after carbon dioxide. Rice paddies and natural wetland ecosystems are among the main sources of methane emissions, making the reduction of methane emissions extremely important.
[0003] Rice is one of the most important food crops, and since the application of chemical nitrogen fertilizers to paddy fields, rice yields have increased significantly. However, long-term or excessive nitrogen fertilizer application leads to the release of nitrogen load, namely the volatilization of ammonium, the emission of nitrous oxide, and the leaching of nitrates from paddy soil into the natural environment, causing environmental problems such as global warming, eutrophication, and nitrate pollution of groundwater. Reducing the use of nitrogen fertilizers is a necessary condition for environmentally friendly and sustainable rice production.
[0004] Developing an environmentally friendly and feasible method to promote methane oxidation and biological nitrogen fixation provides a potential pathway to reduce methane emissions from paddy fields. At the same time, reducing the application of nitrogen fertilizer can also increase rice yield, which is of great significance for responding to the concept of sustainable ecological and environmental development and energy conservation and emission reduction. Summary of the Invention
[0005] The purpose of this invention is to provide a method for promoting methane oxidation and nitrogen fixation and rice growth.
[0006] According to one aspect of the present invention, a method for promoting methane oxidation and nitrogen fixation and rice growth is provided, which involves inducing rice seedlings to form a root surface iron film and then transplanting the rice seedlings with the root surface iron film into an environment containing methane-oxidizing bacteria for cultivation.
[0007] In some implementations, the method includes the following steps:
[0008] S1. Disinfection of rice seeds: Select plump rice seeds and soak them for disinfection.
[0009] S2. Rice seed germination: Rinse the disinfected rice seeds with sterile water, soak the rinsed rice seeds for a period of time, and then place them in a petri dish for germination.
[0010] S3. Seedling raising: Transplant the germinated rice seeds into a complete nutrient solution for hydroponic cultivation;
[0011] S4. Formation of root surface iron film: Rice seedlings are transferred to deionized water and cultured for 24 hours to remove metal ions from the roots. Then, they are transferred to a solution containing ferrous ions and cultured until an iron film is attached to the root surface of the rice seedlings, thus obtaining rice seedlings with a root surface iron film.
[0012] S5. Planting: Transplant rice seedlings with iron film on the root surface into an environment containing methanogenic bacteria for cultivation.
[0013] In some embodiments, in step S1, the rice seeds are soaked in a 0.15% H2O2 solution for disinfection for 30 minutes.
[0014] In some embodiments, in step S2, the rinsed seeds are soaked in the dark at 30°C for 24 hours, then placed in a petri dish lined with moist filter paper. The petri dish is then placed in an artificial climate chamber to promote germination. The artificial climate chamber is set at 28°C for 14 hours during the day and 25°C for 10 hours at night.
[0015] In some implementations, the rice nutrient solution is replaced weekly in step S3, and the pH value of the rice nutrient solution is 5.4-5.7.
[0016] In some implementations, hydroponic cultivation in steps S3-S4 is carried out in an artificial climate chamber, with cultivation conditions of 28°C for 14 hours during the day and 25°C for 10 hours at night.
[0017] In some embodiments, the rice seedlings in step S4 are four-leaf stage rice seedlings, and the solution containing ferrous ions is a 100 mg / L ferrous sulfate solution.
[0018] In some embodiments, step S5 is: transplanting hydroponics: adding a nitrogen-free inorganic salt culture medium containing methanogenic bacteria as a culture solution to the container, transplanting rice seedlings with iron film on the root surface into the container for hydroponic culture, and aerating the container with nitrogen and carbon dioxide to fill the container, sealing the container, and filling the sealed container with methane for partial gas replacement.
[0019] In some embodiments, the culture medium is prepared by mixing a nitrogen-free inorganic salt culture medium with a bacterial suspension of methanogenic bacteria at a volume ratio of 200:1, and the OD of the culture medium is... 600 The value is 0.5, the volume ratio of nitrogen to carbon dioxide is 4:1, and methane accounts for 20% of the headspace volume of the sealed container.
[0020] According to another aspect of the present invention, a method for promoting methane oxidation and nitrogen fixation and rice growth is provided for application in paddy field wetland environments to reduce nitrogen fertilizer use, reduce methane emissions, and promote rice growth.
[0021] The beneficial effects of this invention are as follows: By forming an iron film on the root surface of rice seedlings, this invention enables the iron film to synergistically enhance the nitrogen fixation activity of methane-oxidizing bacteria in the environment. This leads to a significant increase in physiological indicators of rice, such as growth, polysaccharide content, protein content, and chlorophyll content, while reducing nitrogen fertilizer usage. Furthermore, the iron reduction process is coupled simultaneously with methane oxidation and nitrogen fixation, reducing methane emissions from paddy fields. The method provided by this invention is an environmentally friendly in-situ technology with strong practical operability. It can enrich methane-oxidizing, iron-reducing, and nitrogen-fixing microorganisms, enhance biological nitrogen fixation to promote rice growth, and reduce nitrogen fertilizer use and methane emissions from paddy fields. This is of great significance in responding to the concept of sustainable ecological development and energy conservation and emission reduction. Attached Figure Description
[0022] Figure 1 These are images of rice seedlings induced to form a root surface iron film in Example 3 of the present invention, along with a blank control.
[0023] Figure 2 The graph shows the changes in the content of divalent iron ions in headspace methane and root surface iron membrane over time in different treatments of Example 4 of the present invention.
[0024] Figure 3 This is a comparison chart of ethylene production rates under different treatments in Example 5 of the present invention.
[0025] Figure 4 Isotope concentrations in rice roots and non-roots after 30 days of isotopic nitrogen culture in different treatments according to Example 6 of the present invention 15 Comparison chart of N content.
[0026] Figure 5 Isotope concentrations in rice roots and non-roots after 30 days of isotopic nitrogen culture in different treatments according to Example 6 of the present invention 13 Comparison chart of C content.
[0027] Figure 6 This is a comparison diagram of plant biomass of rice plants under different treatments in Example 7 of the present invention.
[0028] Figure 7 This is a comparison diagram of soluble proteins in rice plants treated with different methods in Example 7 of the present invention.
[0029] Figure 8 This is a comparison chart of the total soluble sugars in rice plants under different treatments in Example 7 of the present invention.
[0030] Figure 9 This is a comparison diagram of chlorophyll in rice plants under different treatments in Example 7 of the present invention. Detailed Implementation
[0031] The present invention is further described in detail through specific implementation examples. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. After reading this invention, any modifications of the present invention in various equivalent forms by those skilled in the art fall within the scope defined by the appended claims. Unless otherwise specified, all raw materials and reagents of the present invention are commercially available.
[0032] Example 1
[0033] A method for promoting methane oxidation nitrogen fixation and rice growth includes the following steps:
[0034] S1. Disinfection of rice seeds: Wash the rice seeds of the Nipponbare variety three times with water, pick out the shriveled and floating seeds, and select the plump seeds to be disinfected by soaking them in 0.15% H2O2 solution for 30 minutes.
[0035] S2. Rice seed germination: After rinsing and disinfecting the rice seeds with running water to remove residual H2O2, rinse them three times with sterile water. Under dark conditions at 30℃, soak the rinsed rice seeds in sterile water for 24 hours. Remove them and place them in a petri dish lined with moist filter paper. Place the petri dish in an artificial climate chamber and germinate them under the conditions of 28℃ for 14 hours during the day and 25℃ for 10 hours at night.
[0036] S3. Seedling raising: After germination, rice seeds are transplanted into rice nutrient solution and placed in an artificial climate chamber with the following conditions: daytime temperature 28℃ for 14 hours and nighttime temperature 25℃ for 10 hours for hydroponics. The rice nutrient solution is changed once a week for 3-4 weeks. The pH value of the rice nutrient solution is 5.4-5.7.
[0037] S4. Formation of root surface iron film: Rice seedlings at the four-leaf stage are transferred to deionized water and cultured for 24 hours to remove metal ions from the roots. Then, they are transferred to a 100 mg / L ferrous sulfate solution and cultured for 2-3 days to allow an iron film to adhere to the root surface of the rice seedlings, thus obtaining rice seedlings with a root surface iron film.
[0038] S5. Planting: Transplant rice seedlings with iron film on the root surface into a paddy field wetland environment containing methanogenic bacteria for cultivation.
[0039] Example 2
[0040] A method for promoting methane oxidation nitrogen fixation and rice growth includes the following steps:
[0041] S1. Disinfection of rice seeds: Wash the rice seeds of the Nipponbare variety three times with water, pick out the shriveled and floating seeds, and select the plump seeds to be disinfected by soaking them in 0.15% H2O2 solution for 30 minutes.
[0042] S2. Rice seed germination: After rinsing and disinfecting the rice seeds with running water to remove residual H2O2, rinse them three times with sterile water. Under dark conditions at 30℃, soak the rinsed rice seeds in sterile water for 24 hours. Remove them and place them in a petri dish lined with moist filter paper. Place the petri dish in an artificial climate chamber and germinate them under the conditions of 28℃ for 14 hours during the day and 25℃ for 10 hours at night.
[0043] S3. Seedling raising: After germination, rice seeds are transplanted into rice nutrient solution and placed in an artificial climate chamber with the following conditions: daytime temperature 28℃ for 14 hours and nighttime temperature 25℃ for 10 hours for hydroponics. The rice nutrient solution is changed once a week for 3-4 weeks. The pH value of the rice nutrient solution is 5.4-5.7.
[0044] S4. Formation of root surface iron film: Rice seedlings at the four-leaf stage are transferred to deionized water and cultured for 24 hours to remove metal ions from the roots. Then, they are transferred to a 100 mg / L ferrous sulfate solution and cultured for 2-3 days to allow an iron film to adhere to the root surface of the rice seedlings, thus obtaining rice seedlings with a root surface iron film.
[0045] S5. Planting: Transplant rice seedlings with iron film on the root surface into a culture medium containing methanogenic bacteria and place them in an artificial climate chamber with the following culture conditions: daytime temperature 28℃ for 14 hours and nighttime temperature 25℃ for 10 hours for hydroponic culture.
[0046] Example 3
[0047] A method for promoting methane oxidation nitrogen fixation and rice growth includes the following steps:
[0048] S1. Disinfection of rice seeds: Wash the rice seeds of the Nipponbare variety three times with water, pick out the shriveled and floating seeds, and select the plump seeds to be disinfected by soaking them in 0.15% H2O2 solution for 30 minutes.
[0049] S2. Rice seed germination: After rinsing and disinfecting the rice seeds with running water to remove residual H2O2, rinse them three times with sterile water. Under dark conditions at 30℃, soak the rinsed rice seeds in sterile water for 24 hours. Remove them and place them in a petri dish lined with moist filter paper. Place the petri dish in an artificial climate chamber and germinate them under the conditions of 28℃ for 14 hours during the day and 25℃ for 10 hours at night.
[0050] S3. Seedling raising: After germination, rice seeds are transplanted into rice nutrient solution and placed in an artificial climate chamber with the following conditions: daytime temperature 28℃ for 14 hours and nighttime temperature 25℃ for 10 hours for hydroponics. The rice nutrient solution is changed once a week for 3-4 weeks. The pH value of the rice nutrient solution is 5.4-5.7.
[0051] S4. Formation of root surface iron film: Rice seedlings at the four-leaf stage were transferred to deionized water and cultured for 24 hours to remove metal ions from the roots. Then, the rice seedlings were transferred to a 100 mg / L ferrous sulfate solution and cultured for 2-3 days to allow an iron film to adhere to the root surface, thus obtaining rice seedlings with a root surface iron film. The culture conditions were: daytime temperature 28℃ for 14 hours and nighttime temperature 25℃ for 10 hours.
[0052] S5. Hydroponic culture: The concentrated methanogenic bacteria culture solution was mixed with nitrogen-free inorganic salt medium at a volume ratio of 1:200 to obtain a culture medium containing methanogenic bacteria. The OD of this culture medium was... 600 With a value of 0.5, 200 mL of culture medium containing methanogenic bacteria was added to a 1 L glass bottle. Four-leaf stage rice seedlings with iron film formed on the root surface were transplanted into the glass bottle. Nitrogen and carbon dioxide were introduced into the glass bottle at a volume ratio of 4:1 to fill the glass bottle. The glass bottle was then sealed and filled with methane, replacing 20% of the headspace volume of the sealed glass bottle with methane. The sealed glass bottle was then placed in an artificial climate chamber with the following culture conditions: daytime temperature of 28°C for 14 h and nighttime temperature of 25°C for 10 h for hydroponics.
[0053] Example 4: Verification Experiment of the Method
[0054] Using steps S1-S3 in Example 3, rice seeds of the Nipponbare variety were germinated and seedlings were raised to obtain rice seedlings at the four-leaf stage. The four-leaf stage rice seedlings were then treated with metal ion removal according to step S4 in Example 3. The rice seedlings were then divided into two parts. One part was further treated with root surface iron film attachment according to step S4 to obtain rice seedlings with root surface iron film. The other part was not treated and served as a blank control rice seedling.
[0055] Rice seedlings with iron film forming on the root surface were divided into four different treatment groups: methane + iron film + MOB bacteria group (CH4 + Fe + MOB), methane + MOB bacteria group (CH4 + MOB), methane + iron film group (CH4 + Fe), and iron film + MOB bacteria group (Fe + MOB). Each group had three replicates and was hydroponically cultured in an artificial climate chamber with a daytime temperature of 28℃ for 14 hours and a nighttime temperature of 25℃ for 10 hours.
[0056] The concentrated methanogenic bacteria culture (MOB) was mixed with nitrogen-free inorganic salt medium at a volume ratio of 1:200 to prepare a culture medium containing methanogenic bacteria. The OD of this culture medium was... 600 The value is 0.5, pending use.
[0057] The specific treatment procedure for the methane + iron film + MOB bacterial group is as follows: 200 mL of culture medium containing methanogenic bacteria is added to a 1 L glass bottle. Three four-leaf stage rice seedlings that have formed an iron film on the root surface are transplanted into the glass bottle. Nitrogen and carbon dioxide are introduced into the glass bottle at a volume ratio of 4:1 to fill the glass bottle. The glass bottle is then sealed and filled with methane, replacing 20% of the headspace volume of the sealed glass bottle with methane. The sealed glass bottle is then placed in an artificial climate chamber with the following culture conditions: daytime temperature 28℃ for 14 h and nighttime temperature 25℃ for 10 h for hydroponics.
[0058] The specific treatment procedure for the methane + MOB bacterial group is as follows: 200 mL of culture medium containing methanogenic bacteria is added to a 1 L sealed glass bottle. Three blank control rice seedlings at the four-leaf stage are transplanted into the glass bottle. Nitrogen and carbon dioxide are introduced into the glass bottle at a volume ratio of 4:1 to fill the glass bottle. The glass bottle is then sealed and filled with methane, replacing 20% of the headspace volume of the sealed glass bottle with methane.
[0059] The specific treatment procedure for the methane + iron film group is as follows: 200 mL of nitrogen-free inorganic salt culture medium is added to a 1 L glass bottle as a culture medium. The culture medium does not contain methanogenic bacteria. Three rice seedlings at the four-leaf stage that have formed an iron film on the root surface are transplanted into the glass bottle. Nitrogen and carbon dioxide are introduced into the glass bottle at a volume ratio of 4:1 to fill the glass bottle. The glass bottle is then sealed and filled with methane, replacing 20% of the headspace volume of the sealed glass bottle with methane.
[0060] The specific treatment procedure for the iron film + MOB bacterial group is as follows: Add 200mL of culture medium containing methanogenic bacteria to a 1L sealed glass bottle, transplant 3 four-leaf stage rice seedlings that have formed root surface iron film into the glass bottle, introduce nitrogen and carbon dioxide into the glass bottle at a volume ratio of 4:1, and seal the glass bottle to fill it completely.
[0061] To determine the redox changes in the iron film on the root surface, destructive root sampling was performed on rice seedlings from the four treatment groups every two days to measure the Fe content in the root surface. 2+ The changes in content are shown in the attached figure. Figure 2 A.
[0062] As attached Figure 2As shown in Figure A, with the extension of culture time, the Fe content in the iron film on the root surface of rice seedlings in the CH4+Fe+MOB group increased. 2+ The content of Fe in the iron film on the root surface increased significantly during days 2-10 of cultivation. 2+ The content of these components was significantly higher than that of the CH4+Fe group and the Fe+MOB group, indicating that iron reduction was coupled with methane oxidation, which reduced ferric ions in the iron film on the rice root surface to ferrous ions.
[0063] The Fe content on the root surface of rice seedlings in the CH4+Fe group was... 2+ The content only fluctuated within a small range, and the Fe content on the 10th day... 2+ Content and Fe at the beginning of the experiment 2+ The similar levels of Fe content, without a significant increase, indicate the absence of methanogenic bacteria, meaning that methanogenesis and iron reduction are impossible. In contrast, the Fe content on the root surface of rice seedlings in the Fe+MOB group... 2+ The Fe content peaked on day 8, but decreased again on day 10 to the level at the beginning of the experiment. 2+ The similar content indicates that only methanogenic bacteria are present; without methane, methanogenesis is impossible. Iron redox activity is weak and unsustainable, affecting the Fe content on the root surface of rice seedlings. 2+ The content cannot achieve a stable and continuous increase.
[0064] To determine whether the root surface iron film promotes methane consumption, gas samples were taken from sealed glass bottles of the four treatment groups every two days, and the methane content was determined using GC-Shimadzu. A total of five gas samples were taken and measured. The results are attached. Figure 2 B.
[0065] As attached Figure 2 As shown in Figure B, the methane concentration in the sealed glass bottle of the CH4+Fe+MOB group continuously decreased with the extension of culture time. During the 0-10 days of culture, the methane concentration was significantly lower than that of the CH4+Fe and CH4+MOB groups, indicating that the root surface iron film promotes methane oxidation by methanogenic bacteria. The root surface iron film increases the oxidation rate of methane by methanogenic bacteria.
[0066] In summary, it can be directly concluded that the synergistic effect of the methane-oxidizing bacteria and the root surface iron film in the CH4+Fe+MOB group of this embodiment can not only increase the rate of methane oxidation and remove more methane, but also couple the iron reduction reaction, strengthen the redox reaction in rice roots, reduce methane emissions in paddy fields, and reduce the greenhouse effect.
[0067] Example 5
[0068] Four different treatment groups from Example 4 were used: methane + iron film + MOB bacteria (CH4 + Fe + MOB), methane + MOB bacteria (CH4 + MOB), methane + iron film (CH4 + Fe), and iron film + MOB bacteria (Fe + MOB), with three replicates for each group. To determine whether the root surface iron film promoted nitrogen fixation, nitrogenase activity was detected using the acetylene reduction method after methane was measured on day 10. The specific procedure was as follows: the gas in the sealed glass bottle was replaced with helium, then oxygen and acetylene were introduced to a headspace concentration of 2% and 1%, respectively. 2% methanol was added as an electron donor, and after 24 hours of reaction, the amount of ethylene produced was determined by gas chromatography. Specific results are shown in the appendix. Figure 3 .
[0069] As attached Figure 3 As shown, the CH4+Fe+MOB group had the highest ethylene production, indicating that its nitrogenase activity was the strongest and significantly higher than the other three groups. This preliminarily confirms that the root surface iron membrane can significantly enhance the oxidative nitrogen fixation of methane.
[0070] Example 6
[0071] Four different treatment groups from Example 4 were used: methane + iron film + MOB bacteria group (CH4 + Fe + MOB), methane + MOB bacteria group (CH4 + MOB), methane + iron film group (CH4 + Fe), and iron film + MOB bacteria group (Fe + MOB), with three replicates in each group. To further determine whether the root surface iron film promotes the methane oxidation and nitrogen fixation by methane-oxidizing bacteria, the contents of sealed glass bottles from the above four treatment groups were... 14 N2 and 12 CH4 replaced with 15 N and 13 After one month of CH4 culture, the levels of [unclear - possibly "containment substances"] in the roots and other parts of the rice plants were measured. 15 N and 13 The content of C isotopes. Detection results are attached. Figure 4 and Figure 5 .
[0072] As attached Figure 4 and Figure 5 As shown, the root portion (Root in the figure) and the portion outside the root (Leaf in the figure) of the CH4+Fe+MOB group 13 C and 15 The N content was significantly higher than that of the other three groups, further demonstrating that the root surface iron film has a promoting effect on methane oxidation and nitrogen fixation.
[0073] Example 7
[0074] Four different treatment groups from Example 4 were used: methane + iron film + MOB bacteria group (CH4 + Fe + MOB), methane + MOB bacteria group (CH4 + MOB), methane + iron film group (CH4 + Fe), and iron film + MOB bacteria group (Fe + MOB), with three replicates for each group. To determine whether the synergistic effect of root surface iron film and methanogenic bacteria promotes rice plant growth, four physiological indicators of rice plants—soluble protein, soluble total sugar, chlorophyll, and plant biomass—were measured on the tenth day of culture. Soluble protein and total soluble sugar were determined using the Coomassie Brilliant Blue G-250 and anthrone-sulfuric acid methods, respectively. The absorbance at 652 nm, 663 nm, and 645 nm was measured using ethanol dissolution. Chlorophyll a (mg / g) = 12.72A663 - 2.69A645 and Chlorophyll b (mg / g) = 22.9A645 - 4.68A663, respectively, and the chlorophyll content was calculated. See the appendix for detailed results. Figure 6-9 .
[0075] As attached Figure 6-9 As shown, the plant growth, soluble protein, soluble total sugar and chlorophyll of rice plants in the CH4+Fe+MOB group were significantly better than those in the other three treatment groups, indicating that the root surface iron film and methanogenic bacteria have a significant promoting effect on rice plant growth.
[0076] In summary, by inducing the formation of an iron film on the root surface of rice, the iron film and methane-oxidizing bacteria in the environment have a synergistic effect, enhancing methane oxidation, nitrogen fixation, and iron reduction. This significantly improves the growth, polysaccharide content, protein content, chlorophyll content, and other physiological indicators of rice, while reducing the amount of nitrogen fertilizer used and decreasing methane emissions from paddy fields.
[0077] The above descriptions are merely some embodiments of the present invention. For those skilled in the art, various modifications and improvements can be made without departing from the inventive concept of the present invention, and these all fall within the protection scope of the present invention.
Claims
1. A method for promoting methane oxidation and nitrogen fixation and rice growth, characterized in that, The method includes the following steps: S1. Rice seed disinfection: Select plump rice seeds and soak them for disinfection. S2. Rice seed germination: Rinse the disinfected rice seeds with sterile water, soak the rinsed rice seeds for a period of time, and then place them in a petri dish for germination. S3. Seedling raising: Transplant the germinated rice seeds into a complete nutrient solution for hydroponic cultivation; S4. Formation of root surface iron film: Rice seedlings are transferred to deionized water and cultured for 24 hours to remove metal ions from the roots. Then, they are transferred to a solution containing ferrous ions and cultured until an iron film adheres to the root surface of the rice seedlings, thus obtaining rice seedlings with a root surface iron film. S5. Transplanting hydroponics: Add nitrogen-free inorganic salt culture medium containing methanogenic bacteria as the culture solution to the container. Transplant rice seedlings with iron film on the root surface into the container. Aerate the container with nitrogen and carbon dioxide at a volume ratio of 4:1 until it is full. Seal the container and fill it with methane, replacing 20% of the headspace volume of the sealed container with methane. Then carry out hydroponic culture. The culture solution is made by mixing nitrogen-free inorganic salt culture medium and methanogenic bacteria solution at a volume ratio of 200:1, with an OD600 value of 0.
5.
2. The method according to claim 1, characterized in that, In step S1, the rice seeds are soaked in a 0.15% H2O2 solution for disinfection for 30 minutes.
3. The method according to claim 1, characterized in that, In step S2, the rinsed seeds are soaked in the dark at 30°C for 24 hours, then placed in a petri dish lined with moist filter paper. The petri dish is then placed in an artificial climate chamber to promote germination. The artificial climate chamber is set at 28°C for 14 hours during the day and 25°C for 10 hours at night.
4. The method according to claim 1, characterized in that, In step S3, the rice nutrient solution is replaced weekly, and the pH value of the rice nutrient solution is 5.4-5.
7.
5. The method according to claim 1, characterized in that, In steps S3-S4, hydroponic cultivation is carried out in an artificial climate chamber under the following conditions: daytime temperature 28℃ for 14 hours and nighttime temperature 25℃ for 10 hours.
6. The method according to claim 1, characterized in that, In step S4, the rice seedlings are four-leaf stage rice seedlings, and the solution containing ferrous ions is a 100 mg / L ferrous sulfate solution.
7. The method for promoting methane oxidation and nitrogen fixation and rice growth according to any one of claims 1-6 is applied to reducing nitrogen fertilizer use, reducing methane emissions, and promoting rice growth in paddy wetland environments.