JP7706763B2 - Herbicide - Google Patents

Description

NITE NITE P-03447

(1) Manual for presenters, 2020 Annual Meeting of the Japanese Society of Soil Science and Plant Nutrition, Okayama: August 25, 2020: https://www.jssspn.org/2020/pdf/jssspn2020_manual_lincbiz.pdf (2) Abstracts of the 2020 Annual Meeting of the Japanese Society of Soil Science and Plant Nutrition, Okayama: September 1, 2020: https://www.jssspn.org/2020/lecture_summary.html (3) J-STAGE Abstracts of the Japanese Society of Soil Science and Plant Nutrition, Vol. 66: November 2, 2020: https://www.jstage.jst. go.jp/browse/dohikouen/66/0/_contents/-char/ja? from=4 <<Publication address: https://www.tandfonline.com/doi/full/10.1080/1343943X. 2021.1896953 Release date: March 4, 2021>>

The present invention relates to Clostridium bacteria that use organic matter as a resource to produce one or more compounds selected from the group consisting of fatty acids such as butyric acid, alcohols having 1 to 10 carbon atoms, and aromatic aldehydes, and a method for controlling target plants using the same.

In order to improve crop yield and quality, it is important to suppress the germination and growth of weeds without affecting the crop itself. Numerous synthetic chemical pesticides have been developed as herbicide inhibitors and are widely used as single agents and mixtures. In general, synthetic chemical pesticides are widely used as weed control and weed suppression means because they are stable, highly effective, and cost-effective. However, in recent years, from the perspective of environmental burden, cultivation methods that do not rely on synthetic chemical pesticides have been explored. The Ministry of Agriculture, Forestry and Fisheries has also announced a policy goal of increasing the area of organic farming from the current 23,500 ha to 63,000 ha by 2030 (Non-Patent Document 1), and the need to expand the area of organic flooded cultivation is even greater. However, most of the herbicide inhibitors and weed suppression techniques that can be used in flooded cultivation are based on synthetic chemical pesticides. Therefore, there are only a limited number of weed suppression methods that can be used in organic farming that do not rely on synthetic chemical pesticides.

The traditional method for suppressing weeds such as Monochoria vaginalis in organic flooded cultivation is a combination of two plowings, deep water management, bran spreading, and mechanical weeders. However, plowing and deep water management are not very effective in controlling Monochoria vaginalis, and the use of mechanical weeders results in uneven effectiveness between plants and rows. Therefore, it is expected that the most effective method is to spread bran, for example rice bran, on the field. When bran is spread on the field, an environment with low oxygen concentration is created in the soil that is difficult for weeds to grow, and it can have a strong weed suppression effect. However, this method also has some important drawbacks. One of them is that the weed suppression effect is unstable. The effectiveness of rice bran varies greatly from field to field, and in some cases it may promote the emergence of weeds. In particular, one of the drawbacks is that the effect is not stable on weeds such as Monochoria vaginalis, which can germinate and grow even in low-oxygen environments in many fields. Therefore, there was a need to develop a herbicide that could be used in organic rice cultivation and was stable and effective against a wide variety of weeds, and was not a synthetic pesticide.

Basic Policy for Promoting Organic Farming Ministry of Agriculture, Forestry and Fisheries April 30, 2020

The objective of the present invention is to develop and provide a method for suppressing weeds that is stable and effective against weeds that can germinate and grow even in low-oxygen environments and does not use synthetic chemical pesticides.

In order to solve the above problems, the inventors focused on fields where the growth of weeds such as Monochoria vaginalis, which is a typical weed in organic flooded cultivation, can be stably suppressed by spraying rice bran. Using bacteria isolated from these fields, the effect of suppressing the germination of Monochoria vaginalis when rice bran is administered was verified, and bacteria capable of completely suppressing germination were successfully isolated. Furthermore, from the 16S rDNA sequence, these bacteria were found to be Clostridium bacteria. Analysis of the volatile components contained in the rice bran decomposition products of these Clostridium bacteria revealed that these bacteria use bran as a resource to produce lower fatty acids including butyric acid, alcohols, aromatic aldehydes, etc. The present invention is based on the above novel findings and provides the following.

[1] A herbicide comprising a bacterium of the genus Clostridium that uses organic matter as a resource to produce one or more compounds selected from the group consisting of butyric acid, alcohols having 1 to 10 carbon atoms, and aromatic aldehydes, and that inhibits the germination and/or growth of target plants in organic flooded cultivation.
[1-1] A herbicide comprising a bacterium of the genus Clostridium that uses organic matter as a resource to produce one or more compounds selected from the group consisting of fatty acids, alcohols having 1 to 10 carbon atoms, and aromatic aldehydes, and that inhibits the germination and/or growth of target plants in organic flooded cultivation.
[2] The herbicide according to [1] or [1-1], wherein the Clostridium bacterium produces butyric acid.
[2-1] The herbicide according to [1-1], wherein the fatty acid contains butyric acid.
[3] The herbicide according to any one of [1] to [2-1], wherein the Clostridium bacterium produces methylbenzaldehyde.
[3-1] The herbicide according to any one of [1] to [2-1], wherein the aromatic aldehyde includes methylbenzaldehyde.
[4] The herbicide according to any one of [1] to [3-1], wherein the 16S rDNA of the Clostridium bacterium consists of the following base sequence:
(1) A base sequence as shown in SEQ ID NO: 1. (2) A base sequence having 90% or more base identity to the base sequence as shown in SEQ ID NO: 1. (3) A base sequence in which one or more bases have been deleted, substituted or added to the base sequence as shown in SEQ ID NO: 1. [4-1] The herbicide according to any one of [1] to [3-1], wherein the 16S rDNA of the Clostridium bacterium has the following base sequence:
(1) A base sequence shown in SEQ ID NO: 1 or 6. (2) A base sequence having 90% or more base identity to the base sequence shown in SEQ ID NO: 1 or 6. (3) A base sequence in which one or more bases have been deleted, substituted or added to the base sequence shown in SEQ ID NO: 1 or 6. [5] The herbicide described in [4] or [4-1], wherein the Clostridium bacterium is a bacterium deposited under the accession number: NITE P-03447.
[6] The herbicide according to any one of [1] to [5], wherein the organic matter comprises bran.
[7] The herbicide according to any one of [1] to [6], wherein the target plant includes Monochoria vaginalis.
[8] A weed suppression composition for organic flooded cultivation, comprising one or more weed suppressants according to any one of [1] to [7].
[9] A control composition for controlling the germination and/or growth of a target plant in organic flooded cultivation, comprising a culture of Clostridium bacteria that uses organic matter as a resource to produce one or more selected from the group consisting of butyric acid, alcohols having 1 to 10 carbon atoms, and aromatic aldehydes.
[9-1] A control composition for controlling the germination and/or growth of a target plant in organic flooded cultivation, comprising a culture of Clostridium bacteria that uses organic matter as a resource to produce one or more selected from the group consisting of fatty acids, alcohols having 1 to 10 carbon atoms, and aromatic aldehydes.
[10] The control composition according to [9] or [9-1], wherein the 16S rDNA of the Clostridium bacterium consists of the following base sequence:
(1) A base sequence as shown in SEQ ID NO: 1. (2) A base sequence having 90% or more base identity to the base sequence as shown in SEQ ID NO: 1. (3) A base sequence in which one or more bases have been deleted, substituted or added to the base sequence as shown in SEQ ID NO: 1. [11] The control composition according to [10], wherein the Clostridium bacterium is a bacterium deposited under the accession number: NITE P-03447.
[12] The control composition according to any one of [9] to [11], wherein the organic matter comprises bran.
[13] The control composition according to any one of [9] to [12], wherein the target plant includes Monochoria vaginalis.
[14] A composition for controlling target plants in organic flooded cultivation, comprising one or more herbicide inhibitors according to any one of [1] to [7] and an organic matter as active ingredients.
[15] The control composition according to [14], wherein the organic matter comprises bran.
[16] A method for controlling a target plant in organic flooded cultivation, comprising:
The method includes a herbicide application step of applying one or more herbicides according to any one of [1] to [7] and/or a herbicide composition according to [8] to an application site, and an organic matter application step of applying an organic matter to the application site.
The method.
[17] The control method according to [16], wherein the organic flooded cultivation is transplant cultivation.
[18] The control method according to [16] or [17], wherein the step of administering a herbicide or the like is carried out during and/or before the establishment of the target crop.
[19] The control method according to any one of [16] to [18], wherein the herbicide or other administration step is carried out simultaneously with or after the organic matter administration step.
[20] The control method according to any one of [16] to [19], wherein the target plant includes Monochoria vaginalis.
[21] A method for controlling a target plant in organic flooded cultivation, comprising:
[9] to [15], comprising an administration step of administering one or more control compositions according to any one of the above to an application site;
The method.
[22] The control method according to [21], wherein the organic flooded cultivation is transplant cultivation.
[23] The control method according to [21] or [22], wherein the administration step is carried out during and/or before the establishment of the target crop.

The herbicide or herbicide composition of the present invention can stabilize or enhance the effect of inhibiting the germination and growth of undesirable target plants in organic flooded cultivation. The control composition of the present invention can inhibit the germination and growth of undesirable target plants in organic flooded cultivation. Furthermore, the herbicide method of the present invention can inhibit the germination and growth of undesirable target plants in organic flooded cultivation without adversely affecting the target crop.

1 shows the germination inhibitory effect of isolated bacteria on Monochoria vaginalis seeds, with the lower part of the graph showing the conditions of use of rice bran and bacteria for each group. 2A and 2B show total ion chromatograms of the mass spectrometry analysis of volatile components in the rice bran decomposition products by bacteria that showed weed suppression activity. Some peaks are labeled with the names of the substances they represent. Figure 2A shows the results for the culture medium of Clostridium bacteria cultured with rice bran, and Figure 2B shows the results for rice bran alone. 3 shows extracted ion chromatograms showing the results of mass spectrometry of the volatile component with m/z value 43 in the rice bran decomposition product by the bacteria that showed weed suppression activity. Some peaks are labeled with the name of the substance that the peak indicates its presence. Figure 3A shows the results for the culture medium of Clostridium bacteria cultured with rice bran, and Figure 3B shows the results for rice bran alone. This is a diagram showing the relationship between the concentration of fatty acids and the germination inhibitory effect in the culture solution of various bacteria. In the figure, the black circles show the results for acetic acid, and the white circles show the results for butyric acid. In the figure, the white circles, which are placed at positions that appear to exceed 100%, are placed to distinguish them from the black circle data, and represent 100%.

1. Herbicide 1-1. Overview The first aspect of the present invention is a herbicide. The herbicide of the present invention contains as an active ingredient a bacterium of the genus Clostridium that uses organic matter as a resource to produce one or more selected from the group consisting of fatty acids, alcohols having 1 to 10 carbon atoms, and aromatic aldehydes, and promotes a weed-suppressing effect on target plants. The herbicide of the present invention can be an active ingredient of a control composition for target plants used in organic flooded cultivation.

1-2. Definitions The terms used in this specification are defined as follows.
"Flooded cultivation" is a cultivation method in which crops are grown in land that is filled with water, and is used synonymously with paddy field cultivation. Flooded cultivation is divided into flooded direct seeding cultivation and flooded transplant cultivation. Flooded direct seeding cultivation is a cultivation method in which the seeds of the target crop are directly sown on the surface of a rice field, and flooded transplant cultivation is a cultivation method in which the target crop is grown to seedlings in a location separate from the application site and then transplanted to a field. The flooded cultivation used in the present invention may be any cultivation method, but is preferably flooded transplant cultivation. The initial work steps in flooded transplant cultivation are as follows. First, fertilization, plowing, ridge painting, and plowing are performed as field preparation. Next, the seedlings that have been raised are transplanted into the field. After that, the crop goes through a rooting period and then a tillering period.

In this specification, "organic flooded cultivation" refers to flooded cultivation using organic farming methods. "Organic farming (organic agriculture)" refers to a cultivation method that does not use synthetic chemical fertilizers or synthetic chemical pesticides and reduces the environmental burden caused by agricultural production as much as possible. In this specification, organic farming does not necessarily have to be cultivation without synthetic chemical fertilizers or synthetic chemical pesticides, but also includes cultivation with reduced synthetic chemical fertilizers, cultivation with reduced pesticides, special cultivation, etc.

In this specification, the term "target crop" refers to a crop that is grown under flooded conditions. There are no particular limitations on the target crop, so long as it is a crop that can grow under flooded conditions. Specific examples include crops of the order Poaceae and the family Gramineae.

In this specification, "plowing" refers to work carried out to level the rice field surface, prevent water leakage, and loosen the soil, and includes roughing and planting.

In this specification, "transplanting" refers to the act of planting seedlings of the desired crop in a field.

In this specification, "taking root" refers to the state in which the roots of the seedlings of the target crop have developed more than before transplantation and are able to absorb nutrients and water. In this specification, "taking root period" refers to the period from transplantation until the seedlings take root.

In this specification, "tillering" refers to the branching of lateral branches of the seedlings of the target crop. For example, in the case of a cereal crop, it means that lateral branches emerge and grow from nodes on the stem close to the roots. "Tillering stage" refers to the period from establishment to the end of tillering, and includes the early tillering stage, late tillering stage, and maximum tillering stage.

In this specification, the term "target plant" refers to a plant whose presence is agriculturally undesirable, particularly a plant that is undesirable for the cultivation of a target crop. Therefore, the type of target plant varies depending on the target crop and its cultivation environment. In this specification, preferred target plants are, for example, broadleaf weeds or annual weeds, and specifically include, for example, Monochoria vaginalis.

In this specification, "control" refers to controlling one or more of the germination, growth, or reproduction of the target plant, and "control agent" refers to a drug having that activity. Therefore, as used in this specification, the term control includes weed control and weed killing. This control does not need to be complete, and it is sufficient that the germination, growth, or reproduction of the target plant is suppressed, for example, by at least 50%, at least 55%, at least 60%, at least 70%, at least 75%, at least 80%, at least 90%, at least 95%, or at least 99% compared to normal conditions. In this specification, "weed suppression" refers to creating an environment in which the control effect of the target plant is easily obtained, and suppressing one or more of the germination, growth, or reproduction of the target plant, and "weed suppressor" refers to a drug having that activity. Therefore, by administering a weed suppressor in an environment where organic matter is present, a better control effect can be achieved than when it is not administered. Good control effect does not necessarily mean that the control effect is enhanced, but also includes, for example, that the control effect lasts for a long period of time and that the control effect is stable.

As used herein, "organic matter" broadly refers to materials that contain compounds that contain carbon, including, for example, lipids, proteins, carbohydrates, or combinations thereof. Preferred organic matter in this specification includes, for example, bran.

"Bran" refers to the peeled off material such as the pericarp, seed coat and germ that is produced when the seeds of grasses are polished, and may also contain endosperm in some cases.

In this specification, "administration of organic matter" or "administering organic matter" refers to applying an organic matter to the soil or water of the application target, and preferably refers to applying an organic matter to the surface layer of the soil of the application target. Specifically, for example, spraying in a farm field is an example. In this specification, "soil surface layer" refers to the layer of the soil that is exposed to the atmosphere or flooding.

The term "bacteria" broadly refers to prokaryotes, but in this specification, the bacteria refers to Clostridium bacteria. "Clostridium bacteria" refers to gram-positive obligately anaerobic bacteria belonging to the genus Clostridium. In this specification, Clostridium bacteria are, in principle, a bacterial species that can use organic matter as a resource to produce one or more compounds selected from the group consisting of fatty acids, alcohols having 1 to 10 carbon atoms, and aromatic aldehydes. Therefore, unless otherwise specified, in this specification, when simply referring to Clostridium bacteria, it means Clostridium bacteria that can use organic matter as a resource to produce one or more compounds selected from the group consisting of fatty acids, alcohols having 1 to 10 carbon atoms, and aromatic aldehydes.

"Fatty acid" refers to an acid having a carboxy group represented by the chemical formula -COOH. In this specification, examples of fatty acids include higher fatty acids and lower fatty acids. "Lower fatty acid" refers to a fatty acid having 1 to 6 carbon atoms, and is usually volatile. "Higher fatty acid" refers to a fatty acid having 7 or more carbon atoms. As with the alcohols described below, the fatty acid in this invention may be linear, branched, straight-chain, cyclic, saturated, or unsaturated. In addition, the number of carboxy groups contained in the fatty acid of the present invention is not particularly limited. Specific fatty acids include, for example, formic acid, acetic acid, butyric acid, propionic acid, valeric acid, caproic acid, etc. In this specification, the preferred fatty acid is acetic acid and/or butyric acid.

"Acetic acid" is a lower fatty acid represented by the chemical formula CH ₃ COOH, and is a volatile substance.

"Butyric acid" is a lower fatty acid represented by the chemical formula _CH3 ( _CH2 ) _2COOH , and is a volatile substance. It has an isomer, isobutyric acid represented by the chemical formula _CH3CH ( _CH3 )COOH, but in this specification butyric acid does not include isobutyric acid. Butyric acid is also known by other names such as n-butyric acid, normal butyric acid, butanoic acid, n-butanoic acid, 3-methylpropanoic acid, and 3-methylpropionic acid.

"Alcohol" refers to an organic compound having one hydroxyl group. Specific examples include chain alcohols such as methanol, ethanol, 1-propanol, isopropanol, and butanol, and cyclic alcohols such as cycloheptanol. The number of carbon atoms of alcohol in this specification is 1 to 10. Unless otherwise specified, when simply described as alcohol in this specification, it means an alcohol having 1 to 10 carbon atoms. In this specification, alcohol includes both lower alcohols having 1 to 4 carbon atoms and higher alcohols having 5 to 10 carbon atoms. In addition, the structure of the alcohol is not particularly limited. For example, it may be either an unsaturated alcohol or a saturated alcohol. In addition, the alcohol in this specification may be branched or unbranched. Furthermore, when isomers such as positional isomers, geometric isomers, and optical isomers exist, all of these isomers are included. The properties of the alcohol are not particularly limited. For example, it may be hydrophilic (solubility in water at 25±5° C. and 1013 hPa is 1% by weight or more) or hydrophobic (solubility in water at 25° C. and 1013 hPa is less than 1% by weight). In addition, the alcohol in this specification may have a functional group other than a hydroxy group, and includes, for example, a hydroxyketone having a ketone group.

"Aromatic aldehyde" refers to an aromatic organic compound having one aldehyde group. Specific examples include methylbenzaldehyde. The number of carbon atoms is not particularly limited. In addition, when isomers exist, all isomers, such as positional isomers, geometric isomers, and optical isomers, are included. In addition, the aromatic aldehyde in this specification may have a functional group other than the aldehyde group.

In this specification, the term "active ingredient" refers to a component in the herbicide, herbicide composition, or control composition of the present invention that directly or indirectly contributes to the herbicide or control effect. For example, in the case of a herbicide, it refers to a bacterium of the genus Clostridium that acts on an organic substrate to produce one or more active substances selected from the group consisting of fatty acids, alcohols, and aromatic aldehydes, and in the case of a control composition based on a culture, it refers to a lower fatty acid such as butyric acid, an alcohol, an aromatic aldehyde, or a combination thereof.

In this specification, the term "active substance" refers to a substance that directly exerts a weed-suppressing or control effect on a target plant. For example, in this specification, this term refers to a fatty acid, an alcohol, an aromatic aldehyde, or a combination thereof. When the active ingredient directly contributes to the weed-suppressing or control effect, the active ingredient is synonymous with an active substance. For example, lower fatty acids such as butyric acid, alcohols, aromatic aldehydes, or combinations thereof, which are active ingredients of a control composition, are also active substances.

In this specification, "base identity" refers to the percentage (%) of identical bases in one polynucleotide relative to the total number of bases in the other polynucleotide when the base sequences of two polynucleotides are aligned and, if necessary, gaps are introduced into one of the base sequences to maximize the degree of base identity between the two. The percentage identity can be easily determined using a known program such as the homology search program BLAST (Basic local alignment search tool; Altschul, S. F. et al., J. Mol. Biol., 215, 403-410, 1990) search. For example, when determining whether the obtained bacterium belongs to the above-mentioned genus Clostridium, the base identity of 16S rDNA can be used. In addition, in this specification, "multiple bases" refers to, for example, 2 to 60, 2 to 45, 2 to 30, 2 to 14, 2 to 10, 2 to 8, 2 to 6, 2 to 5, 2 to 4, or 2 to 3 bases.

"Culture medium" refers to a substance that contains nutrients and other components for culturing cells and is used as a place for the growth environment of cells. In the present invention, it particularly refers to a substance used for culturing Clostridium bacteria.

As used herein, the term "culture" refers to a liquid or solid component consisting of a medium in which cells have been cultured, and in this specification, it particularly refers to a material obtained from a medium in which Clostridium bacteria have been cultured.

In this specification, the term "application site" refers to the site to which the herbicide, herbicide composition, or control composition of the present invention is administered. Specifically, for example, this refers to a farm field or an agricultural experimental site, and the area is not limited. In principle, the application site is a flooded area (e.g., a paddy field), but the herbicide, etc. may be administered before flooding.

1-3. Constitution The herbicide of the present invention contains, as an essential component, a bacterium belonging to the genus Clostridium, which uses organic matter as a resource and produces one or more selected from the group consisting of fatty acids, alcohols having 1 to 10 carbon atoms, and aromatic aldehydes. The details are explained below.

The organic matter used in the present invention is preferably a natural substance, and does not contain or does not substantially contain chemically synthesized substances. Specific organic matter is not particularly limited, but examples include organic fertilizers. Examples of organic fertilizers include bone meal, blood meal, feather meal, animal or human or animal waste (including chicken manure, cow manure, pig manure, etc.), compost, oil cake, rice bran, bat guano, wood ash, organic lime, dried or fermented products thereof, or extracts thereof. For example, bokashi fertilizer, which is a mixture of multiple types of these in a desired ratio, can also be used as the organic matter of the present invention. The organic matter of the present invention preferably contains rice bran.

The bran used in the present invention may be processed or not. For example, at least a portion of it may be processed into a powder. Also, bran harvested at any time during the milling process may be used. For example, it may be first bran, second bran, or a combination of both. There are no particular limitations on the type of bran, but bran from rice bran, wheat bran, and wheat bran (barley bran), as well as buckwheat, rye, and pearl barley, can be used. The bran of the present invention may consist of one type of bran or may be a mixture of multiple types of bran.

"Using organic matter as a resource to produce one or more selected from the group consisting of fatty acids, alcohols having 1 to 10 carbon atoms, and aromatic aldehydes" refers to metabolizing organic matter as a substrate and producing one or more selected from the group consisting of fatty acids, alcohols having 1 to 10 carbon atoms, and aromatic aldehydes as one of the products. There are no particular limitations on the type or amount of the components produced. For example, when Clostridium bacteria produce alcohol, the Clostridium bacteria may produce multiple types of alcohols and may also produce fatty acids and/or aromatic aldehydes. For example, when Clostridium bacteria produce fatty acids, the Clostridium bacteria may produce multiple types of fatty acids and may also produce alcohols and/or aromatic aldehydes. The Clostridium bacteria used in the herbicide of the present invention are not particularly limited, and any specific species is acceptable, as long as they use organic matter as a resource to produce one or more selected from the group consisting of fatty acids, alcohols having 1 to 10 carbon atoms, and aromatic aldehydes. There are also no particular limitations on the form of the Clostridium bacteria. For example, it may contain Clostridium bacteria in the form of spores.

Clostridium bacteria are classified into clusters 1 to 19 based on the sequence of 16S rDNA (COLLINS et al., Int. J. Syst. Bacteriol., 1994, 44, 812-826.), but the Clostridium bacteria used in the present invention are not particularly limited. Preferred species are species belonging to cluster 1, cluster 2, cluster 3, or cluster 4. Specifically, for example, Clostridium acetobutylicum, Clostridium uliginosum, Clostridium sardiniense, Clostridium baratii, Clostridium moniliforme, Clostridium chromiireducens, Clostridium saccharobutylicum, Clostridium paraputrificum, Clostridium vincentii, Clostridium saudiense, Clostridium swellfunianum, Clostridium gasigenes, Clostridium maxima, Clostridium polyendosporum, Clostridium peptidovorans, Clostridium oryzae, Clostridium bovifaecis, Clostridium fallax, Clostridium butyricum, Clostridium putrefaciens, Clostridium lentoputrescens, Clostridium cadaveris, Clostridium indologenes, Clostridium capitovale, Clostridium tertium, Clostridium bifermentans, Clostridium proteolyticum, Clostridium limosum, Clostridium historyticum, Clostridium pfennigii, Clostridium amygdalinum, Clostridium aerotolerans, Clostridium diolis, Clostridium fungisolvens, Clostridium zeae, and Clostridium fervidus.

Preferably, the base sequence of the 16S rDNA has 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, 99% or more, 99.5% or more, 99.9% or more, or 100% base identity to the base sequence shown in SEQ ID NO: 1 or SEQ ID NO: 2. Alternatively, the Clostridium bacterium used in the herbicide of the present invention preferably has a 16S rDNA base sequence in which one or more bases have been deleted, substituted, or added to the base sequence shown in SEQ ID NO: 1 or SEQ ID NO: 2. Also, preferably, the base sequence of the 16S rDNA has 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, 99% or more, 99.5% or more, 99.9% or more, or 100% base identity with the base sequence shown in SEQ ID NO: 7 or SEQ ID NO: 8. Alternatively, the Clostridium bacterium used in the herbicide of the present invention preferably has a 16S rDNA base sequence in which one or more bases are deleted, substituted, or added with respect to the base sequence shown in SEQ ID NO: 7 or SEQ ID NO: 8. Specifically, the Clostridium bacterium used in the herbicide of the present invention may be, for example, a bacterium deposited at the Patent Microorganisms Depositary Center under the accession number: NITE P-03447.

The Clostridium bacterium used in the herbicide of the present invention may have a 16S rDNA base sequence that has 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, 99% or more, 99.5% or more, 99.9% or more, or 100% base identity with the base sequence shown in SEQ ID NO:5 or SEQ ID NO:6. Alternatively, the Clostridium bacterium used in the herbicide of the present invention may have a 16S rDNA base sequence in which one or more bases have been deleted, substituted, or added with respect to the base sequence shown in SEQ ID NO:5 or SEQ ID NO:6.

The production of fatty acids, alcohols, or aromatic aldehydes can be confirmed using any method known in the art. For example, any of instrumental analysis using an analytical device, olfactory measurement, which is a sensory test, or a combination thereof may be used. For instrumental analysis, for example, a gas chromatography mass spectrometer, an odor detector, and a gas detector tube can be used. When a gas chromatography mass spectrometer is used, pretreatment can be performed. Pretreatment can be performed, for example, by solvent extraction, solid-phase adsorption-solvent elution, solid-phase adsorption-thermal desorption, solid-phase microextraction, etc. As an adsorbent used for solid-phase adsorption, for example, activated carbon, silica gel, or MonoTrap can be used. As an olfactory measurement method, a relatively strict method such as a three-point comparison odor bag method or a six-level odor intensity display method can also be used. It is also possible to simply smell the sample and determine that butyric acid is present if it smells like sweat.

The herbicide of the present invention exerts a control effect on target plants when used together with organic matter.

The target plant may be a single type of plant or multiple types of plants. In the present invention, in which organic flooded cultivation is performed, the target plant may be paddy field weeds. Paddy field weeds include, but are not limited to, seed plant weeds including annual weeds and perennial weeds, and algae. Examples of annual weeds include broadleaf weeds including Pontederiaceae weeds (e.g., Monochoria korsakowii, Monochoria korsakowii, etc.), Scrophulariaceae weeds (e.g., Lindera monadelpha, American Lindera, Taketo Lindera, Rhizome monadelpha, Aedes aegypti, and Large Aedes aegypti, etc.), Lythrum salicaria weeds (e.g., Lythrum salicaria, Lythrum nigra, and Lythrum nigra, etc.), Gramineae weeds including Echinochloa spp. (e.g., Echinochloa oryzicola, Echinochloa crus-galli, Echinochloa spp., etc.), and Cyperaceae weeds (e.g., Cyperus persica, Cyperus globulus, etc.). Here, broadleaf weeds refer to plants that do not belong to the Gramineae or Cyperaceae families, and literally mean weeds that have relatively broad leaves. Examples of perennial weeds include broadleaf weeds including Albatross family weeds (e.g., Sagittaria pygmaea, Ardisia trifolia, Ardisia gracilis, etc.), Potamogaceae weeds (e.g., Potamogaceae, etc.), Umbelliferae weeds (e.g., Japanese parsley, etc.), Poaceae weeds including Polytrichum commune (e.g., Polytrichum formosum, Polytrichum formosum, etc.), Phragmites spp. (e.g., Phragmites repens, etc.) and Paspalum spp. (e.g., Paspalum nigra, Paspalum japonica, etc.), Cyperaceae weeds (e.g., Scirpus juncoides, Cyperus serotinus, Pinus japonica, Eulognathus kuroguwai, etc.), and Typhaceae weeds (e.g., Typha truncatula, etc.). Examples of algal weeds include green algae, diatoms, and blue-green algae. In the present invention, preferred target plants are broadleaf weeds or annual weeds, including, for example, Monochoria vaginalis.

2. Weed-suppressing composition 2-1. Overview The second aspect of the present invention is a weed-suppressing composition for target plants. The weed-suppressing composition of the present invention contains as an active ingredient a Clostridium bacterium that uses the organic matter described in the first aspect as a resource to produce one or more selected from the group consisting of fatty acids, alcohols having 1 to 10 carbon atoms, and aromatic aldehydes, and has a weed-suppressing effect on target plants. By applying the weed-suppressing composition of the present invention to organic flooded cultivation, weeds of target plants such as Monochoria vaginalis can be suppressed simply and effectively.

2-2. Composition 2-2-1. Constituents The constituents of the weed suppressor composition of the present invention will be explained. The weed suppressor composition of the present invention contains one or more active ingredients as essential components, and agriculturally acceptable solvents and/or carriers as optional components. Each of the constituents will be specifically explained below.

(1) Active Ingredient The weed suppressor composition of the present invention contains, as an essential active ingredient, one or more herbicide agents as described in the first aspect. If necessary, it may further contain one or more herbicide agents.

The herbicide is described in detail in the first embodiment, and therefore a detailed description thereof will be omitted here. The weed suppressor composition of the present invention may contain one or more herbicide.
There are no particular limitations on the type or amount of the herbicide contained in the weed control composition of the present invention.

The content of the active ingredient per a given amount of the weed suppressor composition of the present invention varies depending on various conditions such as the type of Clostridium bacteria, the type of target crop, the formulation, and the method of administration. Usually, it is preferable that the active ingredient of the weed suppressor composition of the present invention contains an amount sufficient to exhibit the weed suppression effect at the time of administration. This amount may be determined taking into consideration each condition within the scope of common general knowledge in the art. When the formulation of the weed suppressor composition of the present invention is a liquid formulation, for example, the Clostridium bacteria in the solution may be in the range of 10 ⁵ to 10 ¹⁰ cfu/mL, and a sufficient amount of organic matter may be contained. If necessary, the active ingredient may be diluted 10 to 1000 times with water or a buffer at the time of administration.

The weed suppressant composition of the present invention can also contain other active ingredients with pharmacological effects, such as insecticides, herbicides, and fertilizers, to the extent that they do not affect the viability of Clostridium bacteria.

(2) Agriculturally Acceptable Carriers The weed suppressant composition of the present invention may contain, as necessary, one or more agriculturally acceptable carriers within the range in which Clostridium bacteria can grow.

In this specification, the term "agriculturally acceptable carrier" refers to a substance that facilitates administration of the weed suppressor composition, maintains the viability of the active ingredient, Clostridium bacteria, and/or controls the rate of action of the active ingredient, and has no or only a small harmful effect on the environment, such as soil and water quality, when administered to a field where the target crop is grown, or has no or low harmfulness to animals, particularly humans.

Agriculturally acceptable carriers include, for example, crushed natural minerals, crushed synthetic minerals, excipients such as dispersants, emulsifiers and surfactants, and soil.

Ground natural minerals include, for example, kaolin, clay, talc, and chalk.
Ground synthetic minerals include, for example, highly dispersed silica and silicates.
Dispersants include, for example, lignosulfite waste liquor and methylcellulose.

Emulsifiers include nonionic and anionic emulsifiers (e.g., polyoxyethylene fatty alcohol ethers, alkyl sulfonates, and aryl sulfonates).

Examples of surfactants include alkali metal salts, alkaline earth metal salts and ammonium salts of lignosulfonic acid, naphthalenesulfonic acid, phenolsulfonic acid and dibutylnaphthalenesulfonic acid, alkylarylsulfonates, alkyl sulfates, alkylsulfonates, fatty alcohol sulfates, fatty acids and sulfated fatty alcohol glycol ethers, as well as condensates of sulfonated naphthalene and naphthalene derivatives with formaldehyde, condensates of naphthalene or naphthalenesulfonic acid with phenol and formaldehyde, and polyoxyethylene octylphenyl ether. , ethoxylated isooctylphenol, octylphenol, nonylphenol, alkylphenyl polyglycol ether, tributylphenyl polyglycol ether, tristearylphenyl polyglycol ether, alkylaryl polyether alcohol, alcohol and fatty alcohol/ethylene oxide condensates, ethoxylated castor oil, polyoxyethylene alkyl ether, ethoxylated polyoxypropylene, lauryl alcohol polyglycol ether acetal, sorbitol ester, lignosulfite waste liquor, and methylcellulose. Natural surfactants may also include, for example, plant-derived components (e.g., lecithin, saponin, gum arabic, etc.), animal-derived components (e.g., lanolin, bile acid, cholesterol, etc.), protein components (e.g., casein, gelatin, serum albumin, egg albumin, soybean protein, etc.), and biosurfactants produced by microorganisms.

The soil or soil used in the present invention is not particularly limited as long as it is capable of growing the target crop. Typically, for example, planting soil containing appropriate nutrients (nitrogen, phosphorus, potassium, etc.) and having an appropriate pH value is used. The soil or soil of the present invention may be artificially prepared, for example, by adding additives such as fertilizers or soil conditioners to the soil, or may be soil prepared by mixing multiple soils, or may be natural soil (including, for example, soil collected from a farm field). The soil or soil used in the present invention preferably does not contain, or substantially does not contain, chemically synthesized substances.

(3) Agriculturally acceptable solvents Examples of agriculturally acceptable solvents include water (including sterilized water, deionized water, ultrapure water, and water obtained from paddy fields), buffers (including phosphate buffer and carbonate buffer), physiological saline, a culture medium for Clostridium bacteria, and a mixture thereof.

2-2-2. Dosage form The formulation of the weed suppressor composition of the present invention may be in any form so long as the active ingredient can be applied to water or soil, for example, it may be a liquid formulation in a liquid state or a solid formulation in a solid state. In the case of a liquid formulation, examples of the formulation include a solution in which the active ingredient is suspended in a suitable solution, an oil-based dispersion, an emulsion, and a suspension. In the case of a solid formulation, there is no particular limitation so long as the active ingredient can be applied to water or soil by diffusion or the like. Examples of the formulation include granules, dusts, powders, pastes, and gels.

3. Control composition based on culture 3-1. Overview A third aspect of the present invention is a control composition for target plants. The control composition of the present invention contains as an active ingredient a culture of Clostridium bacteria that uses organic matter as a resource and produces one or more selected from the group consisting of fatty acids, alcohols having 1 to 10 carbon atoms, and aromatic aldehydes, and has a control effect on target plants. By applying the control composition of the present invention to organic flooded cultivation, target plants such as Monochoria vaginalis can be controlled simply and effectively.

3-2. Configuration The configuration of the control composition of this embodiment will be described. The control composition of the present invention contains one or more active ingredients as essential components, and contains an agriculturally acceptable solvent and/or carrier as optional components. The carrier and solvent used in the control composition of this embodiment, as well as the formulation, are described in detail in the second embodiment, so a detailed description here will be omitted. Below, the active ingredient will be described in detail.

The control composition of the present invention contains, as an essential component, a culture of Clostridium bacteria that uses organic matter as a resource and produces one or more selected from the group consisting of fatty acids, alcohols having 1 to 10 carbon atoms, and aromatic aldehydes. In addition, if necessary, the composition may further contain one or more types of herbicide, organic matter, and control agent. The details are explained below.

Since Clostridium bacteria are described in detail in the first embodiment, a detailed description will be omitted here.

The culture may be of any type as long as it is derived from the Clostridium bacteria. It may be derived from a single species or multiple species. The culture may contain bacteria, and in that case, the number of bacteria is not particularly limited. The bacteria may be either live or dead, or both. The form of the bacteria is also not particularly limited. For example, the bacteria may be in the form of spores. The culture conditions, such as temperature, oxygen concentration, and period, may be appropriately set so that the active substance in the culture contains a sufficient amount to exert a weed suppression effect when the control composition of the present invention is administered. The active substance of the control composition of the present invention is a part or all of the collection of substances produced by the Clostridium bacteria using organic matter as a resource. The active substance of the control composition of the present invention includes, for example, lower fatty acids such as butyric acid.

The type of medium is not particularly limited. For example, any of synthetic medium, natural medium, and semi-synthetic medium can be used. Synthetic medium is a medium composed of known chemical substances (e.g., amino acids or inorganic salts, etc.) mixed at known mixing ratios, and natural medium is a medium composed only of natural substances (e.g., serum or tissue extract, etc.) whose components are unclear. Semi-synthetic medium is a medium in which chemical substances are added to natural medium. Furthermore, the form of the medium is not particularly limited. For example, either liquid medium or solid medium can be used. In the present invention, preferred media are, for example, semi-synthetic liquid medium or natural liquid medium.

The medium contains various nutritional components, such as carbon sources, nitrogen sources, phosphate sources, sulfur sources, inorganic salts, and trace elements, as necessary. Examples of carbon sources include alcohols such as methanol and ethanol, organic acids such as pyruvic acid, acetic acid, and lactic acid, and sugars such as glucose, starch, and dextrin. Examples of nitrogen sources include amino acids such as arginine, ammonium salts and nitrates (e.g., ammonium chloride, ammonium nitrate, and sodium nitrate), urea, peptone, casitone, meat extract, yeast extract, dry yeast, corn steep liquor, soybean flour, and casamino acids. Examples of phosphate sources include sodium dihydrogen phosphate, potassium dihydrogen phosphate, disodium hydrogen phosphate, and dipotassium hydrogen phosphate. Examples of sulfur sources include ammonium sulfate, magnesium sulfate, and sulfuric acid. Examples of inorganic salts include phosphate salts, potassium salts, magnesium salts, manganese salts, and calcium salts. Examples of trace elements include iron, cobalt, copper, zinc, boron, iodine, lead, nickel, and molybdenum. The medium may further contain trace nutrient sources such as vitamins.

The nutritional components can be used alone or in combination, and the type and concentration can be appropriately set depending on conditions such as the type of bacteria. The composition of the medium does not need to be constant throughout the entire culture period, and may change over time, for example, by adding a medium with a different composition during the culture by feeding, or by subculturing using a medium with a different composition. A preferred medium used in the present invention contains, for example, an organic substance.

The form of the culture is not particularly limited, but is preferably a liquid (culture solution). The presence or absence of bacterial cells in the culture is not an issue. For example, the culture medium may be used as is, or after removing only impurities, or after removing cellular components by centrifugation or the like. Although not limited, the preferred culture is a culture supernatant.

The culture may be further processed. The method used for processing is not particularly limited, but a method that does not cause the loss of volatile components such as butyric acid in the culture is preferred. Specific processing methods include, for example, modification of properties (e.g., dilution with the same medium, extraction, concentration, etc.), modification of shape (e.g., freezing, solidification, liquefaction, etc.), and modification of shape and volume (e.g., molding, cutting, dividing into small portions, etc.).

In this embodiment, the culture method is not particularly limited. As a culture method for the Clostridium bacteria in this embodiment, for example, an anaerobic culture method known in the art can be used. Examples of the culture methods that can be used in the present invention include the stratification method, the substitution method, the reduction method, and combinations thereof. The stratification method is a culture method that limits contact with air, and examples of the method include the puncture method, the Burri method, the Einberg tube method, the double-dish flattening method, the Hall method, the deep culture method, and the seal method. The substitution method is a culture method that removes oxygen or replaces it with other gases, and examples of the method include the Shoentensack method, the suction method, the Novy method, the Botkin method, the Rosenthal method, the iron or steel wool method, and the yellow phosphorus method. The reduction method is a culture method in which a reducing agent is added to the medium, and examples of the method include a method using sodium sulfide, thioglycolate salt, cysteine, cysteine hydrochloride, or ascorbic acid as a reducing agent, a method of adding sterilized liver pieces, and a method of performing mixed culture with aerobic bacteria. Examples of methods that combine these include the Hungate method, the modified Miller et al. method, the Bryant et al. method, and methods that use an anaerobic chamber or a glove box. Alternatively, the culture method used in the culture of this embodiment does not have to be an anaerobic culture method. Preferably, the culture is at least partially under anaerobic conditions, but it is not necessary for the entire culture to be under anaerobic conditions throughout the entire culture period. For example, even if the culture is under normal aerobic conditions, it is sufficient that anaerobic conditions are created in a part of the culture. The methods exemplified above can be used alone or in combination.

Culture conditions such as culture time may be set appropriately depending on, for example, the type of Clostridium bacteria used, the culture method used, and the purpose. Specific culture times may be, for example, 1 hour or more, 3 hours or more, 6 hours or more, 12 hours or more, 20 hours or more, 1 day or more, 2 days or more, 3 days or more, 4 days or more, 5 days or more, 6 days or more, 7 days or more, 8 days or more, 10 days or more, 14 days or more, 15 days or more, 20 days or more, 21 days or more, 25 days or more, 28 days or more, or 30 days or more.

The control composition of this embodiment contains an active substance such as butyric acid. Therefore, the control effect on the target plant is obtained from the time of application.

4. Control composition based on herbicide 4-1. Overview The fourth aspect of the present invention is a control composition. The control composition of the present invention contains the herbicide of the first aspect and an organic matter as essential components, and contains a solvent and a pharma- ceutical acceptable carrier as optional components. By applying the control composition of the present invention to organic flooded cultivation, target plants such as Monochoria vaginalis can be simply and effectively controlled.

4-2. Configuration The configuration of the control composition of this embodiment will be described. The control composition of the present invention contains one or more active ingredients as essential components, and contains an agriculturally acceptable solvent and/or carrier as optional components. The carrier and solvent used in the control composition of the present invention, as well as the formulation, are described in detail in the second embodiment, so a detailed description here will be omitted. The active ingredient will be described below.

The control composition of the present invention contains, as essential active ingredients, one or more herbicides and organic substances described in the first aspect. In addition, if necessary, it may further contain one or more types of herbicides, organic substances, and control agents.

Since the herbicide is described in detail in the first embodiment, a detailed description thereof will be omitted here. The control composition of the present invention may contain one or more herbicide types.

The type of organic matter contained in the control composition of the present invention is not particularly limited, but is, for example, bran. The amount of organic matter is also not particularly limited. Since the organic matter is used as a nutrient source for the Clostridium bacteria contained in the herbicide, the control composition of the present invention preferably contains more organic matter than the herbicide. The preferred mass of the organic matter contained in the control composition of the present invention is, for example, at least 1 time, at least 5 times, at least 10 times, at least 25 times, at least 50 times, at least 100 times, at least 200 times, at least 250 times, at least 500 times, at least 1000 times, or at least 10000 times the mass of the Clostridium bacteria.

The control composition of the present invention can also contain other active ingredients having pharmacological actions, such as insecticides, herbicides, and fertilizers (e.g., urea, ammonium nitrate, and superphosphates), to the extent that they do not affect the viability of Clostridium bacteria.

The control composition of this embodiment does not contain an active substance such as butyric acid. Therefore, the control effect is obtained after a certain period of time after application. The certain period of time is, for example, 1 hour or more, 3 hours or more, 6 hours or more, 12 hours or more, 20 hours or more, 1 day or more, 2 days or more, 3 days or more, 4 days or more, 5 days or more, 6 days or more, or 7 days or more.

5. Control method using herbicide and/or herbicide composition 5-1. Overview The fifth aspect of the present invention is a control method using one or more herbicide and/or herbicide composition described in the first aspect. The method of this aspect includes a herbicide and/or organic matter administration step as essential steps. According to this method, the germination, growth, etc. of target plants such as Monochoria vaginalis can be efficiently inhibited in organic flooded cultivation.

5-2. Method The method of this embodiment includes, as essential steps, a step of administering a herbicide or the like and a step of administering an organic matter. Each step will be specifically described below.

The "step of administering a herbicide or the like" is a step of administering an effective amount of the herbicide described in the first aspect and/or the herbicide composition described in the second aspect to the soil or water of an application site where a target plant may grow. There is no particular limitation on the timing of carrying out this step.

The herbicide and the herbicide composition are described in detail in the first and second aspects, so a detailed description is omitted here. In the control method of this aspect, either the herbicide or the herbicide composition may be used, or they may be used in combination.

The cultivation method used in the present invention is not particularly limited as long as it is flooded cultivation. Organic flooded cultivation is preferable. Organic flooded cultivation does not necessarily have to be cultivation without chemical synthetic fertilizers or without chemical synthetic pesticides, but also includes cultivation with reduced chemical synthetic fertilizers or reduced pesticides. In addition, the cultivation method used in the present invention is preferably flooded transplant cultivation. Specific cultivation conditions can be appropriately determined depending on various conditions such as the target crop, the location of the application site, the climate, the quality of the soil, and the quality of the water.

The target crop is not particularly limited as long as it can grow in a flooded environment. Examples include Poaceae crops such as rice, barnyard millet, watercress, and wild rice (Zizania latifolia), and Poaceae crops such as rush, as well as water parsley, taro, arrowhead, watercress, wasabi, water congee (water spinach or morning glory), and lotus (lotus root).

The time when this step is carried out is not particularly limited, but is preferably the weed emergence period. The weed emergence period differs depending on the type of weed to be controlled, but specifically, for example, it is from immediately after plowing to the tillering period. Specifically, it refers to the period from immediately after plowing to 14 days, 20 days, 21 days, 25 days, 28 days, 30 days, 31 days, 33 days, 35 days, 38 days, 40 days, 45 days, or 50 days after transplanting.

The timing of carrying out this process is, for example, before field preparation, before fertilization, before plowing, before ridge painting, before plowing, before the transplanting period, before transplanting, before the rooting period, before the tillering period, before the end of the tillering period, or before the end of the weed emergence period. Alternatively, for example, the compound may be administered during field preparation, during fertilization, during plowing, during ridge painting, during plowing, during the transplanting period, during the rooting period, during the tillering period, or during the weed emergence period. It does not matter whether the paddy field is filled with water at the time of administration. For example, this process may be carried out when the paddy field is not filled with water, such as before flooding or during mid-drying (e.g., during the weed emergence period). This process may also be carried out multiple times a year.

This step can be carried out, for example, during and/or before the tillering stage. The tillering stage specifically refers to the period from the end of the establishment stage described below to 20, 21, 25, 28, 30, 31, 33, 35, 38, 40, 45, or 50 days after transplantation. The determination of whether or not tillering has occurred can be made, for example, by visual inspection or by considering tillering to have occurred after a certain period of time has passed.

This step can be preferably carried out, for example, during the survival period and/or before. The survival period is, for example, the period from immediately after transplantation to 3 days, 4 days, 7 days, 10 days, 12 days, 14 days, 15 days, 17 days, or 20 days after transplantation. The determination of whether or not the plants have survived can be made, for example, by visual inspection or by determining that the plants have survived after a certain period of acclimation.

Alternatively, for example, this step can be carried out during and/or after plowing. Puddling is carried out, for example, 5 weeks, 4 weeks, 3 weeks, 2 weeks, 1 week, 6 days, 5 days, 4 days, 3 days, 2 days, or 1 day before transplanting. When plowing is carried out multiple times, this step may be carried out, for example, during and/or after any of the plowing. Preferably, for example, this step is carried out after the last plowing before transplanting. Note that even in the case of non-plowing cultivation where plowing is not carried out, this period can be conveniently referred to as the plowing period.

Herbicides and the like can be administered into the soil or water of the application site. There are no particular limitations on the method of administration, and they may be administered by machine or by hand. When administering by machine, examples of administration methods include spraying using aircraft (e.g., unmanned aircraft, including agricultural drones and radio-controlled helicopters), tillers, sprinklers, or large work machines (including boom sprayers, power spreaders, etc.).

When administered to soil, it is administered to the soil surface and/or into the soil. It can also be administered by methods similar to fertilization methods such as full-layer fertilization or side-stripe fertilization. In addition, soil administration can be carried out at any time before, during, or after flooding.

When administered to water, it may be administered during or after flooding. Administration to water may be to the surface of the water and/or into the water. Specific administration methods include, for example, simply pouring the herbicide into the water, spraying with a sprayer, and administering the herbicide at the water inlet when the water is introduced.

This step may be performed once per embodiment, or may be performed multiple times as necessary. When performing the step multiple times, the same method may be used each time, or different methods may be used each time, or a combination of both may be used.

5-2-2. Organic matter administration step The "organic matter administration step" is a step of administering an effective amount of organic matter to the soil or water of the application site. Since the organic matter is described in detail in the first embodiment, a detailed description thereof will be omitted here.

The timing and administration method of this step may be the same as those described in detail in the herbicide administration step. Therefore, only the differences will be described here. In this step, the organic matter is administered, for example, in water or on the water surface, or on the soil surface or in the soil. Preferably, the organic matter is administered, for example, in water, on the water surface, or on the soil surface. Preferred administration methods in this step include, for example, a method in which the organic matter is administered to the soil surface and then water is poured over the soil and allowed to diffuse, a method in which the organic matter is mixed into the water when the soil is flooded, and a method in which the organic matter is poured on the water surface and/or into the water during flooding.

This step can be carried out simultaneously with, before, or after the step of administering the herbicide, etc. When this step is carried out simultaneously with the step of administering the herbicide, etc., the administration methods used in both steps may be the same or different.

This step may be performed once or multiple times per embodiment. When this step is performed multiple times, it may be performed alternately with the step of administering a herbicide or the like, or this step may be performed intermittently multiple times. In addition, it may be administered in the same way each time, or in a different way each time, or a combination of these.

There is no limit to the number of times this step may be carried out. It may be carried out once, but since the organic matter administered in this step is generally consumed by soil bacteria such as Clostridium bacteria and other organisms, it may be carried out multiple times.

In order to obtain a control effect, the target crop may be cultivated in a normal manner after carrying out both administration steps. According to the method of this embodiment, as the Clostridium bacteria grow, active substances are produced using organic matter as a resource, and the target crop can be cultivated in an environment in which the germination and/or growth of target plants such as Monochoria vaginalis are suppressed.

6. Control method using a control composition 6-1. Overview The sixth aspect of the present invention is a control method using one or more control compositions according to the third and fourth aspects. The method of this aspect includes an administration step as an essential step. Germination, growth, etc. of a target plant in organic flooded cultivation is suppressed. According to this method, germination, growth, etc. of a target plant in organic flooded cultivation can be efficiently suppressed.

6-2. Method The method of this embodiment includes an administration step as an essential step. The control method of this embodiment is similar to the control method of the fifth embodiment, but differs in that the substance used is a control composition, and therefore the organic matter administration step is not an essential step. The administration step, which is an essential step, will be described below.

6-2-1. Administration step The "administration step" is a step of administering an effective amount of a control composition to soil or water. Except that the administered substance is a control composition, the basic method of the step is similar to the organic matter administration step described in the fifth aspect. Therefore, a detailed description here is omitted.

The amount of the control composition to be administered is not particularly limited. For example, the amount can be determined so that the concentration of the active substance in the water of the field is at a certain level or higher. Specifically, for example, the concentration of the active substance in the water of the field is 0.2 mM or more, 0.3 mM or more, 0.4 mM or more, 0.5 mM or more, 0.6 mM or more, 0.7 mM or more, 0.8 mM or more, 0.9 mM or more, 1 mM or more, 1.1 mM or more, 1.4 mM or more, 1.5 mM or more, 1.6 mM or more, 1.7 mM or more, 1.8 mM or more, 1.9 mM or more, 2 mM or more, 2.1 mM or more, 2.2 mM or more, 2.3 mM or more, 2.4 mM or more, 2.5 mM or more, 2.6 mM or more, 2.7 mM or more, 2.8 mM or more, 2.9 ...9 mM mM or more, 2.6mM or more, 2.7mM or more, 2.8mM or more, 2.9mM or more, 3mM or more, 3.5mM or more, 4mM or more, 4.5mM or more, 4.6mM or more, 4.7mM or more, 4.8mM or more, 4.9mM or more, 5mM or more, 10mM or more, 11mM or more, 11.1mM or more, 11.2mM or more, 11.4mM or more, 11.5mM or more, 11.6mM or more, 11.9mM or more, 12mM or more, 13mM or more, 14mM or more, 15mM 16mM or more, 19mM or more, 20mM or more, 30mM or more, 40mM or more, 50mM or more, 100mM or more, 110mM or more, 120mM or more, 130mM or more, 135mM or more, 136mM or more, 137m M or more, 138mM or more, 139mM or more, 140mM or more, 141mM or more, 144mM or more, 145mM or more, 146mM or more, 149mM or more, 150mM or more, 160mM or more, 170mM or more, 180mM or more or more, 190 mM or more, 200 mM or more, 225 mM or more, 250 mM or more, 275 mM or more, 300 mM or more, 400 mM or more, 500 mM or more, 505 mM or more, 510 mM or more, 515 mM or more, 520 mM or more, 525 mM or more, 530 mM or more, 535 mM or more, 540 mM or more, 545 mM or more, 550 mM or more, 560 mM or more, 590 mM or more, 600 mM or more, or 700 mM or more.

The method of this embodiment and the method of the fifth embodiment are not mutually exclusive, and may be carried out simultaneously, separately, or in combination in the same field.

In order to obtain a control effect, the target crop may be cultivated in a normal manner after carrying out this step. According to the method of this embodiment, as the Clostridium bacteria grow, an effective control substance is produced using organic matter as a resource, and the target crop can be cultivated in an environment in which the germination and/or growth of the target plant, such as Monochoria vaginalis, is suppressed.

Example 1: Isolation of effective bacteria from paddy field soil
(the purpose)
Bacteria that may be responsible for the weed-suppressing effect are isolated from the soil.

(method)
A 1 cm sample of soil was taken from the surface of a paddy field (Tsukubamirai City, Ibaraki Prefecture) where bran application over several years had been found to have a significant and stable inhibitory effect on the germination and growth of weeds such as Monochoria vaginalis, which can germinate and grow even in low-oxygen environments, and placed in a 1.5 mL microtube (As One Corporation). The sample was then centrifuged at 13,000 rpm for 5 minutes at 4°C using a centrifuge (Tomy Seiko Co., Ltd.). The supernatant was discarded and the weight of the soil remaining in the tube was measured. Sterile water was added at a ratio of 250 μL per 0.01 g of soil, and the soil was suspended and stirred.

The suspension was heated to 80°C for 15 minutes, and a certain amount of the diluted solution was added to an empty petri dish (Sanshosha). On top of this, 7-10mL of 10-fold diluted NA medium containing added cysteine (3g dried bouillon (Nissui), 20g agar (Fujifilm Wako Pure Chemicals), 0.3g cysteine hydrochloride, 1L distilled water) was dispensed and mixed with the suspension, and then the gel was allowed to stand at room temperature to solidify. At this time, a control plate was also prepared containing only the medium without mixing with the suspension. These were cultured under anaerobic conditions at 25°C for more than 7 days, and the formed colonies were isolated from the gel. Alternatively, 20 g of paddy soil was collected from the same paddy field in a 50 mL tube, 30 mL of sterilized water was added, and the soil was left to stand at 25°C indoors for one week. After that, 0.06 g or 0.12 g of rice bran was added and cultured for one week. After discarding the supernatant, the soil near the surface was collected and placed in a 1.5 mL microtube, and the bacteria were isolated in the same manner as above.

(result)
A total of about 20 strains of bacteria were isolated. Four of these strains (B3, D1-1, F25, and E5) were used in the following experiments. B3 strain was deposited at the Patent Microorganisms Depositary Center (Accession Number: NITE P-03447).

Example 2: Verification of the germination inhibitory effect of isolated bacteria on Monochoria vaginalis
(the purpose)
The isolated bacteria are cultured with rice bran, and the culture supernatant is applied to Monochoria vaginalis seeds to clarify the germination inhibitory effect of each of the bacteria isolated in Example 1 on Monochoria vaginalis.

(method)
1. Rice bran culture of the isolated bacteria
Rice bran medium was prepared by mixing 0.1 g of rice bran and 8 mL of distilled water and sterilizing the medium. The isolated colonies were then inoculated into the rice bran medium and cultured at 30° C. As a sterile control, agar derived from a plate containing only the 1/10 NA medium with cysteine prepared in Example 1 was added.
After one week, a portion was set aside for counting the number of bacteria, and the remainder was transferred to a 15 mL tube and centrifuged at 13,000 rpm for 10 minutes at 4° C. The supernatant was filtered and adjusted to a pH of 4.7 or less.

2. Germination test of Monochoria vaginalis Ten Monochoria vaginalis seeds were placed in 1.5 mL microtubes, the surfaces of which were sterilized with 70% ethanol and 0.5% sodium hypochlorite, and washed three times with sterile water.
0.5-1.0 mL of culture supernatant was placed in the microtube and incubated at 30°C under conditions of 12 hours of light and 12 hours of darkness. Germination was observed on the third day. If even a small number of roots had sprouted from the seed, it was counted as germination, and the ratio of germinated seeds per 10 Monochoria vaginalis seeds was calculated as the germination rate. As a negative control, sterilized water was used instead of the culture supernatant. Each group was subjected to three repeated experiments.

(result)
The results are shown in Figure 1.
Figure 1 is a graph showing the average germination rate of each group calculated in the germination test of Monochoria vaginalis. In both the negative control without rice bran and the sterile control containing rice bran, most of the Monochoria vaginalis seeds germinated (negative control: 96.7%, sterile control: 100%). In contrast, only when the B3, D1-1, and F25 strains of bacteria isolated from soil were used, the germination of Monochoria vaginalis seeds was completely inhibited (each group: 0%). Similarly, in the group using the E5 strain isolated from soil, most of the Monochoria vaginalis seeds germinated (E5 strain: 93.9%), and no inhibitory effect on the germination of Monochoria vaginalis was observed.
From the above, it was found that a significant germination inhibitory effect of Monochoria vaginalis was observed only when a specific bacterium was used together with rice bran.

Example 3. Identification of the bacterial species of isolated bacteria
(the purpose)
The species of the isolated bacteria, especially those that showed an inhibitory effect on the germination of Monochoria vaginalis, will be identified.

(method)
1. Sequencing of 16S rDNA In order to identify the bacteria isolated in Example 1, DNA was extracted from the bacteria using achromopeptidase (Fujifilm Wako Pure Chemical Industries, Ltd.). The extracted DNA was used as a template, and the 16S rRNA gene was amplified by PCR using a primer set (SEQ ID NO: 3 and SEQ ID NO: 4). The PCR conditions were 98°C for 10 seconds, 55°C for 5 seconds, and 72°C for 1.5 minutes for 30 cycles. The amplified product was electrophoresed on a 1% agarose gel, and an amplified fragment of about 1.5 kbp was confirmed. The amplified product was purified using a PCR filter plate (Mollipore, NM-LSKMPCR5), and a 1515 bp DNA base sequence was determined by cycle sequencing reaction using BigDye Terminator v.3.1 Cycle Aequencing Kit (Life Technology). The obtained base sequence was searched for identity with existing base sequences using the BLAST program and identified.

2. Creation of a molecular phylogenetic tree Using the base sequence obtained in 1 and the 16s rDNA sequences of known Clostridium bacteria, a molecular phylogenetic tree was created using MEGA X. The neighbor-joining method was used to infer the phylogenetic tree.

(result)
From the 16S rDNA sequence, it was found that all of the bacteria isolated in Example 1 (B3 strain, D1-1 strain, F25 strain, and E5 strain) belonged to the genus Clostridium. In addition, the nucleotide identity between the three strains (B3 strain, D1-1 strain, and F25 strain) that showed weed suppression effects in Example 2 exceeded 99%, and in particular, the nucleotide identity between the B3 strain and the D1-1 strain was 100%. In addition, the nucleotide identity with Clostridium polyendosporum, which is considered to be the closest relative, was 95.6%. The nucleotide sequences of the 16S rDNA of the B3 strain and the D1-1 strain are shown in SEQ ID NO: 1, and the nucleotide sequence of the 16S rDNA of the F25 strain is shown in SEQ ID NO: 2. In addition, the DNA nucleotide sequence of about 1.5 kbp of the 16S rDNA of the B3 strain and the D1-1 strain is shown in SEQ ID NO: 7, and the DNA nucleotide sequence of about 1.5 kbp of the 16S rDNA of the F25 strain is shown in SEQ ID NO: 8.

Example 4. Identification of volatile components in culture supernatants of isolated bacteria.
(the purpose)
The active ingredient with weed suppression effect present in the culture supernatant of the isolated bacterium cultured with rice bran is identified.

(method)
Analysis of Volatile Components 1 mL of each of the culture supernatants of the four strains of bacteria cultured in Example 2 was placed in a 1.5 mL centrifuge tube, and a saturated amount of sodium chloride was added. Furthermore, one MonoTrap RGPS TD Rod Type (GL Sciences) was placed in the tube, and the tube was shaken at room temperature for 1 hour. After removing the MonoTrap, the surface was washed with water, dried, and the volatile components were analyzed using a gas chromatograph mass spectrometer equipped with a thermal desorption device (Agilent 5977B: Agilent Technologies).
The volatile components collected in the collector were thermally desorbed using a thermal desorption unit (Gestell).

The conditions for thermal desorption are as follows:
・Sample heating temperature: 40°C for 30 seconds, then increase temperature to 240°C at 12°C/sec and hold for 5 minutes ・Thermal desorption mode: Splitless mode ・Carrier gas: Helium ・Transfer line temperature: 300°C

A glass liner (Gestell) filled with Carbotrap B was attached to the temperature programmed vaporization inlet and pre-cooled to -40°C. During the thermal desorption period, the inlet mode was set to solvent vent mode with a flow rate of 50 mL/min, and the volatile components were cryofocused.

After the thermal desorption was completed, the gas chromatograph (GC) analysis was started and the injection port was rapidly heated to 340°C at 12°C/sec and held for 5 minutes to introduce the volatile components into the gas chromatograph mass spectrometer. The GC column used was HeavyWax (60 m length, 0.25 mm i.d., 0.25 μm df, Agilent Technologies).

The analytical conditions for the gas chromatograph mass spectrometer are as follows.
Analysis temperature: 40°C for 1 minute, then increase temperature to 240°C at 4°C/min and hold for 10 minutes. Carrier gas flow rate: 1.1mL/min (constant flow).
・Mass spectrometer: m/z scan range 30 to 400 ・Ionization voltage: 70 eV

(result)
The results for the culture supernatant of the F25 strain are shown in FIG. 2 and FIG.
From the total ion chromatogram (Fig. 2) obtained by the gas chromatograph mass spectrometer, it was found that the culture supernatant (Fig. 2A) which showed the germination inhibitory effect on Monochoria vaginalis seeds contained a large amount of alcohols such as ethanol and butanol, methylbenzaldehyde, and lower fatty acids such as butyric acid, compared to the case of rice bran only (Fig. 2B). Among them, the content of butyric acid was particularly high. Furthermore, to compare the amount of alcohols and aldehydes with three or more carbons, an ion chromatogram (Fig. 3) was obtained by extracting ions with an m/z value of 43, which corresponds to a propyl group, from the total ion chromatogram. As a result, it was found that the culture supernatant (Fig. 3A) which showed the germination inhibitory effect on Monochoria vaginalis seeds contained even more types of alcohols and aldehydes. For example, it was found that the content of alcohols such as chain alcohols, such as butanol, pentanol, hexanol, heptanol, octanol, and decanol, hydroxyketones, such as hydroxyacetone and acetoin, unsaturated alcohols, such as 1-octen-3-ol, and cyclic alcohols, such as cycloheptanol, increased compared to the case of rice bran alone (Figure 3B).

Regarding aldehydes, it was found that linear unsaturated aldehydes such as hexanal, trans-2-heptenal, and trans-2-decenal were contained in the culture supernatant (Figure 3A) in which the germination inhibitory effect was observed. However, these were also contained in equivalent amounts in the case of rice bran alone (Figure 3B). From this, it was found that the aldehydes whose content in the culture supernatant was increased were limited to aromatic aldehydes such as methylbenzaldehyde (not included in Figure 3 because they do not have a propyl group). These results were similar for other strains that showed weed suppression effects (D1-1 strain and F25 strain). It is known that lower fatty acids such as butyric acid have weed suppression activity in the concentration range contained in the decomposition products of rice bran (Tazawa et al., PPS, 2021). From this, it was found that one of the active substances of the weed suppression effect of the isolated bacteria is butyric acid.

Example 5: Verification of the germination inhibitory effect of alcohols and aromatic aldehydes on Monochoria vaginalis
(the purpose)
By applying various types of alcohols and methylbenzaldehyde standards to Monochoria vaginalis seeds, the germination inhibitory effects of the alcohols and aromatic aldehydes detected in Example 4 on Monochoria vaginalis are clarified.

(method)
The experiment was carried out in accordance with Example 2, except that a citrate phosphate buffer solution containing alcohol and methylbenzaldehyde (mixed with 20 mM sodium hydrogen phosphate and 10 mM citric acid, pH 4.6) or sterile distilled water was added instead of the culture supernatant. As the alcohol, standard substances of alcohols with 1 to 9 carbon atoms (methanol (Fujifilm Wako Pure Chemical Industries, Ltd.), ethanol (Fujifilm Wako Pure Chemical Industries, Ltd.), 1-butanol (Fujifilm Wako Pure Chemical Industries, Ltd.), 1-pentanol (Tokyo Chemical Industry Co., Ltd.), 1-hexanol (Fujifilm Wako Pure Chemical Industries, Ltd.), 1-heptanol (Tokyo Chemical Industry Co., Ltd.), 1-octanol (Tokyo Chemical Industry Co., Ltd.), 1-nonanol (Tokyo Chemical Industry Co., Ltd.), 2-propanol (Tokyo Chemical Industry Co., Ltd.), 2-methyl-1-butanol (Fujifilm Wako Pure Chemical Industries, Ltd.), 3-methyl-1-butanol (Tokyo Chemical Industry Co., Ltd.), and 3-methyl-1-pentanol (Tokyo Chemical Industry Co., Ltd.)) were used. As aromatic aldehydes, standard substances of methylbenz isomers (2-methylbenzaldehyde (Fujifilm Wako Pure Chemical Industries, Ltd.), 3-methylbenzaldehyde (Fujifilm Wako Pure Chemical Industries, Ltd.), and 4-methylbenzaldehyde (Fujifilm Wako Pure Chemical Industries, Ltd.)) were used. The concentrations used were 500 mM, 250 mM, 137 mM, 11 mM, 4.7 mM, 4.0 mM, 0.9 mM, 0.8 mM, 0.7 mM, 0.6 mM, 0.3 mM, and 0.1 mM. As a negative control, a buffer solution containing no standard substance was used. Three repeated experiments were performed for each condition. The lowest concentration at which the average germination rate was significantly reduced compared to the negative control was determined as the minimum concentration showing a germination inhibitory effect.

(result)
The results are shown in Table 1.

In the negative control that did not contain the standard substance, the average germination rate of Monochoria vaginalis was 100% (data not shown), while all the standard substances examined showed an inhibitory effect on the germination of Monochoria vaginalis. When the minimum concentration showing the germination inhibitory effect for each standard substance was calculated, it was found that the minimum concentration showing the germination inhibitory effect for alcohol tended to decrease as the carbon number increased. This showed that the alcohol with a larger carbon number showed a stronger germination inhibitory effect. In addition, the minimum concentration showing the germination inhibitory effect for 1-pentanol, 2-methyl-1-butanol, and 3-methyl-1-butanol was all 4.7, indicating that there is no significant difference in the germination inhibitory effect between isomers such as positional isomers with the same carbon number. This was also the case for methylbenzaldehyde.

From the above, it was found that in addition to butyric acid, these alcohols and aromatic aldehydes such as methylbenzaldehyde contribute to the weed-suppressing effect of the isolated bacteria.

Example 6. Verification 1 of fatty acid concentration in culture solution and germination inhibitory effect on Monochoria vaginalis (comparison between fungal strains)
(the purpose)
Regarding fatty acids, a volatile component, the relationship between the concentration after cultivation in rice bran and the germination inhibitory effect on Monochoria vaginalis when different strains are used will be clarified.

(method)
Other than the strain used, rice bran culture and Monochoria vaginalis germination test were performed in the same manner as in Example 2, and volatile components were analyzed in the same manner as in Example 4 to measure fatty acid concentrations.
In addition to the bacteria isolated in Example 1 (strains B3, D1-1, F25 and E5), the following strains were used in this experiment.
Clostridium sp. strain G14 (isolated as in Example 1)
CSC2 strain belonging to Clostridium zeae (C. zeae) (Accession number: MAFF212476; 16S rDNA base sequence: SEQ ID NO: 5)
Clostridium amygdalinum (C. amygdalinum) strain MJC9 (accession number: MAFF516358)
SGC10 strain (accession number: MAFF516421) belonging to Clostridium diolis (C. diolis; 16S rDNA base sequence: SEQ ID NO: 6)
Clostridium aerotolerans (C. aerotolerans) strain CSC14 (deposit number: MAFF516430)

(result)
The results are shown in Table 2.

When strains B3, D1-1 and F25 were used as in Example 2, a strong germination inhibitory effect was obtained, with an average germination inhibition rate of 100%, while no germination inhibitory effect was observed when strain E5 was used. The three bacterial strains that showed a germination inhibitory effect contained large amounts of fatty acids such as acetic acid and butyric acid in the culture medium. In addition, the concentrations of acetic acid and butyric acid in the culture medium were roughly correlated.

As with the results above, other bacteria also showed a strong germination inhibitory effect in bacterial strains with high concentrations of acetic acid or butyric acid in the culture medium (C. zeae (CSC2 strain) and C. diolis (SGC10 strain)). On the other hand, bacterial strains with low concentrations of these acids did not show a strong germination inhibitory effect.

The nucleotide identities of the 16S rDNA sequences of C. zeae (CSC2 strain) and C. diolis (SEQ ID NO:5 and 6, respectively) to the 16S rDNA sequences of the B3 strain and D1-1 strain shown in SEQ ID NO:1 were 99.7% for C. zeae (CSC2 strain) and 89.0% for C. diolis. Furthermore, the mutual nucleotide identity of the 16S rDNA sequences of C. zeae (CSC2 strain) and C. diolis was 89.0%.

<Example 7. Verification 2 of fatty acid concentration in culture solution and germination inhibitory effect on Monochoria vaginalis (comparison of fatty acid concentration)>
(the purpose)
This study aims to clarify the relationship between the fatty acid concentration after incubation in rice bran and the germination inhibitory effect on Monochoria vaginalis when a specific bacterial strain is used.

(method)
Basically, rice bran culture and Monochoria vaginalis germination tests were carried out in the same manner as in Example 2, and volatile components were analyzed in the same manner as in Example 4 to measure fatty acid concentrations.
The bacteria used were D1-1 and F25 strains.
In order to verify the relationship between fatty acid concentration and germination inhibition effect in each bacterial strain, fatty acid concentration and germination inhibition effect were measured not only when the culture period was 7 days (1 week) but also when it was 3 days.
The number of bacteria was also counted under each condition.
The number of bacteria was counted according to the following procedure.
After the above-mentioned incubation period, 100 μL of the culture solution was diluted with sterile distilled water and layer-cultured on 1/10 Nutrient Agar medium under anaerobic conditions at 30° C. Colonies were counted one week after the start of layer culture, and the number of bacteria per mL was calculated.

(result)
The results are shown in Table 3.

When the F25 strain was used, the fatty acid concentration was high even in the culture medium on the third day of culture, and the average germination inhibition rate was 100%, similar to that on the seventh day of culture, resulting in a strong germination inhibitory effect.
On the other hand, when the D1-1 strain was used, sufficient bacterial growth was not observed on the third day of culture, and the fatty acid concentration was low. In addition, the germination inhibitory effect was not observed in the culture medium on the third day of culture. However, by the seventh day of culture, the number of bacteria had increased until a sufficient amount of fatty acid was produced, and a strong germination inhibitory effect was obtained, similar to Example 6.
These results indicate that although the growth rate and amount of fatty acids produced per unit cell number differ depending on the type of bacteria, the germination inhibitory effect depends on the fatty acid concentration.

Furthermore, the results of Examples 6 and 7 with respect to the fatty acid concentration and the germination inhibitory effect are summarized in FIG.
In the figure, black circles indicate the results for acetic acid, and white circles indicate the results for butyric acid. For each fatty acid, results for cases where the concentration was below the detection limit were excluded. In particular, it was found that a high germination inhibition rate of 90% was obtained at a concentration of 1.8 mM acetic acid.
The results in FIG. 4 show that, for any fatty acid, when a rice bran culture solution containing that fatty acid at a certain concentration or higher was used, a stable and excellent germination inhibitory effect was obtained.

Example 8: Verification of weed suppression effect against weeds other than Monochoria vaginalis
(the purpose)
The weed-suppressing effect against weeds other than Monochoria vaginalis will be clarified.

(method)
The F25 strain was inoculated into tryptic soy broth containing additives and cultured at 30°C for 18 days. After the culture, the culture was centrifuged at 5,000 rpm (equivalent to 2,300 x g) for 5 minutes at 4°C, and the bacterial cells were collected as a precipitate. The bacterial cells were washed twice with sterile distilled water, and then refrigerated at 4°C with the addition of sterile water until they were used in the weed suppression test.
The weed control test was carried out as follows.
First, the soil for the test was prepared. Soil collected from a paddy field (Tsukubamirai City, Ibaraki Prefecture) was filled into a Wagner pot (area division: 1/10,000a), water was added, and the pot was stirred. After leaving the pot to stand for a while, the soil volume was adjusted so that the soil surface was 6 cm below the edge of the pot.
The prepared soil was inoculated with the stored fungus and rice bran. A control group was used in which neither the fungus nor rice bran was inoculated. Plants were grown in a water level that was always kept 3-5cm above the soil surface. 20 days after inoculation, the type, number and dry weight of the weeds that had grown were measured. Dry weight was measured for only the above-ground parts of each plant.
The experiment was performed in triplicate.

(result)
In the control group, where neither the bacteria nor rice bran was inoculated, an average of 4,200 weeds per square ^meter were observed, including Monochoria vaginalis and other weeds such as Cyperus persica, and the average total dry weight of the aboveground parts was 2.87 g per square ^meter .
On the other hand, in the group inoculated with both the bacterial cells and rice bran, an average of 267 weeds/ ^m2 and an average of 0.2g/ ^m2 were observed, and there were no weeds/ ^m2 .
This demonstrates that the herbicide of the present invention inhibits the germination and growth of a wide range of weeds other than Monochoria vaginalis.

Claims (15)

A herbicide consisting of Clostridium bacteria that uses organic matter as a resource to produce one or more compounds selected from the group consisting of fatty acids, alcohols with 1 to 10 carbon atoms, and aromatic aldehydes, and that inhibits the germination and/or growth of target plants in organic flooded cultivation. The herbicide of claim 1, wherein the fatty acid includes butyric acid. The herbicide of claim 1, wherein the aromatic aldehyde comprises methylbenzaldehyde. 2. The herbicide according to claim 1, wherein the 16S rDNA of the Clostridium bacterium has the following base sequence:
(1) The base sequence shown in SEQ ID NO: 1 or 6. (2) A base sequence having 90% or more base identity to the base sequence shown in SEQ ID NO: 1 or 6. (3) A base sequence in which one or more bases have been deleted, substituted or added to the base sequence shown in SEQ ID NO: 1 or 6. The herbicide of claim 1, wherein the organic matter includes bran. The herbicide according to claim 1, wherein the target plant includes Monochoria vaginalis. A weed suppression composition for organic flooded cultivation, comprising the weed suppressant according to claim 1. A control composition for controlling the germination and/or growth of a target plant in organic flooded cultivation, comprising a culture of Clostridium bacteria that uses organic matter as a resource to produce one or more selected from the group consisting of fatty acids, alcohols having 1 to 10 carbon atoms, and aromatic aldehydes. A composition for controlling target plants in organic flooded cultivation, comprising the herbicide according to claim 1 and an organic matter as active ingredients. A method for controlling a target plant in an organic flooded cultivation, comprising:
A herbicide application step of applying one or more herbicides according to any one of claims 1 to 6 and/or a herbicide composition according to claim 7 to an application site, and an organic matter application step of applying an organic matter to the application site.
The method. The control method according to claim 10, wherein the organic flooded cultivation is transplant cultivation. The control method according to claim 10, wherein the step of administering the herbicide or the like is carried out at or before the establishment of the target crop. The control method according to claim 10, wherein the step of administering the herbicide or the like is carried out simultaneously with or after the step of administering the organic matter. A method for controlling a target plant in an organic flooded cultivation, comprising:
The method comprises administering one or more control compositions according to claim 8 or 9 to a site of application.
The method. The method according to claim 14, wherein the administration step is carried out at and/or before the establishment of a target crop.

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