Plant growing agent, plant cultivating composition, and method of cultivating plant

Abstract

To provide a plant growing agent capable of accelerating growth of a plant and having high biodegradability, a plant cultivating composition containing the plant growing composition, and a plant cultivation method using the plant growing agent.SOLUTION: A plant growing agent includes at least one kind of polyaspartic acid compound selected from the group consisting of polyaspartic acid, a derivative of polyaspartic acid, and salt thereof. A plant cultivating composition contains: the polyaspartic acid compound selected from the group consisting of polyaspartic acid, a derivative of polyaspartic acid, and salt thereof; and a plant cultivating medium. A method of cultivating a plant uses the plant growing composition.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a plant growth promoter, a composition for plant cultivation, and a method for cultivating plants.

Background Art

[0002] In plant cultivation, it is important to appropriately manage moisture and nutrients. In order to retain the moisture necessary for plant growth, for example, it has been proposed to use a polyacrylic acid-based water-absorbing resin (Patent Document 1). However, since the polyacrylic acid-based water-absorbing resin has low biodegradability, its residue in the environment becomes a problem.

[0003] Polyaspartic acid has water retention properties and is expected to be used as a water-absorbing resin. For example, Patent Document 2 describes a water-absorbing resin containing a cross-linked polyaspartic acid.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] A plant growth material that can promote plant growth and has high biodegradability is useful for plant cultivation. By using such a material, it becomes possible to efficiently cultivate plants without causing adverse effects on the environment.

[0006] Therefore, an object of the present invention is to provide a plant growth promoter that can promote plant growth and has high biodegradability, a composition for plant cultivation containing the plant growth promoter, and a method for cultivating plants using the plant growth promoter.

Means for Solving the Problems

[0007] The present invention includes the following aspects. [1] A plant growth agent comprising at least one polyaspartic acid compound selected from the group consisting of polyaspartic acid, derivatives of polyaspartic acid, and salts thereof. [2] The plant growth agent according to [1], which is used by being mixed with a plant cultivation medium. [3] The plant growth agent according to [2], which is used to maintain the water retention of the plant cultivation medium. [4] The plant growth agent according to [2] or [3], which is used to supply a fertilizer component to the plant cultivation medium. [5] The plant growth agent according to any one of [2] to [4], which is mixed with the plant cultivation medium so that the polyaspartic acid compound is 0.1 to 10 parts by mass with respect to 100 parts by mass of the plant cultivation medium. [6] The plant growth agent according to any one of [2] to [5], wherein the plant cultivation medium is soil. [7] The plant growth agent according to any one of [1] to [6], wherein the polyaspartic acid compound is synthesized from a raw material produced by an organism. [8] The plant growth agent according to any one of [1] to [7], wherein the derivative of polyaspartic acid is a cross-linked product of polyaspartic acid. [9] A plant cultivation composition containing at least one polyaspartic acid compound selected from the group consisting of polyaspartic acid, derivatives of polyaspartic acid, and salts thereof, and a plant cultivation medium.

[10] The plant cultivation composition according to [9], which contains 0.1 to 10 parts by mass of the polyaspartic acid compound with respect to 100 parts by mass of the plant cultivation medium.

[11] The plant cultivation composition according to [9] or

[10] , wherein the plant cultivation medium is soil.

[12] A method for cultivating a plant using the plant growth agent according to any one of [1] to [8].

[13] A method for cultivating a plant according to

[12] , comprising a step of cultivating a plant using a plant cultivation composition containing at least one polyaspartic acid compound selected from the group consisting of polyaspartic acid, derivatives of polyaspartic acid, and salts thereof, and a plant cultivation medium.

[14] The method for cultivating a plant according to

[13] , wherein the plant cultivation composition contains 0.1 to 10 parts by mass of the polyaspartic acid compound with respect to 100 parts by mass of the plant cultivation medium.

Advantages of the Invention

[0008] According to the present invention, there are provided a plant growth promoter, a plant cultivation composition containing the plant growth promoter, and a plant cultivation method using the plant growth promoter, which can promote plant growth and have high biodegradability.

Brief Description of the Drawings

[0009]

Figure 1

Modes for Carrying Out the Invention

[0010] <Plant Growth Promoter> The first aspect of the present invention is a plant growth promoter. In one embodiment, the plant growth promoter contains at least one polyaspartic acid compound selected from the group consisting of polyaspartic acid, derivatives of polyaspartic acid, and salts thereof.

[0011] (Polyaspartic Acid Compound) The "polyaspartic acid compound" is a compound selected from the group consisting of polyaspartic acid, derivatives of polyaspartic acid, and salts thereof.

[0012] Polyaspartic acid is a polymer of aspartic acid and contains at least a monomer unit represented by the following formula (1). In addition to the monomer unit of the following formula (1), it may contain a monomer having a succinimide skeleton or the like.

[0013]

Chemical formula

[0014] In the formula (1), n represents the number of repetitions of the aspartic acid monomer unit. n is an integer of 2 or more, for example, an integer of 10 to 10,000.

[0015] Polyaspartic acid may be in the form of a salt. In one embodiment, the salt of polyaspartic acid has one or more carboxy groups in the side chain of polyaspartic acid in the form of a salt. Examples of the salt include alkali metal salts (sodium salt, potassium salt, etc.), alkaline earth metal salts (calcium salt, magnesium salt, etc.), ammonium salts, amine salts (trimethylamine salt, triethylamine salt, etc.), etc. Among them, the potassium salt is particularly preferred.

[0016] Polyaspartic acid or its salt may be dried as needed and physically pulverized to form particles of polyaspartic acid or its salt. The drying method is not particularly limited, and for example, known methods such as heat drying, freeze drying, reduced pressure (vacuum) drying, and reduced pressure heat drying can be arbitrarily implemented. In the case of heat drying, the drying temperature is usually in the temperature range of 60°C to 250°C, preferably 80°C to 220°C, more preferably 100°C to 200°C. In the case of reduced pressure heat drying, the drying temperature is usually in the temperature range of 50°C to 200°C, preferably 60°C to 150°C, more preferably 70°C to 120°C. The particle size (average particle diameter) of polyaspartic acid or its salt is preferably 1 to 5000 μm, more preferably 10 to 2000 μm, still more preferably 200 to 2000 μm, and particularly preferably 500 to 2000 μm. The particle size of the polyaspartic acid cross-linked particles may be adjusted by performing operations such as particle size adjustment using classification by a sieve.

[0017] The particles of polyaspartic acid or its salt may be cross-linked on the surface portion (surface cross-linking). By performing surface cross-linking, it is easy to control the water retention characteristics of the particles of polyaspartic acid or its salt. Surface cross-linking is preferably performed at the timing when the polyaspartic acid cross-linked particles have a specific moisture content. As the cross-linking agent (surface cross-linking agent) for performing surface cross-linking, for example, a known cross-linking agent can be used. The surface cross-linking agent may be used alone or in combination of two or more. After surface cross-linking, particles that are surface-cross-linked dry products can be obtained by distilling off water or a water-containing solvent by a known method.

[0018] ≪Derivatives of Polyaspartic Acid≫ Examples of the derivative of polyaspartic acid include polymers in which one or more functional groups possessed by polyaspartic acid are modified. Examples of the derivative of polyaspartic acid include polyaspartic acid cross-linked products.

[0019] The polyaspartic acid cross-linked product is a polymer in which one or more of the side chains of polyaspartic acid are cross-linked. The polyaspartic acid cross-linked product is, for example, a polymer containing a cross-linked structure represented by the following general formula (2).

[0020]

Chemical formula

[0021] As a method for producing a crosslinked polyaspartic acid, for example, a method of reacting poly(succinimide) with a crosslinking agent to partially crosslink it and then subjecting the uncrosslinked imide ring portion to alkaline hydrolysis; a method of reacting polyaspartic acid with a crosslinking agent to partially crosslink it, etc. can be mentioned. The crosslinking agent is not particularly limited, and a known crosslinking agent can be used. Examples of the crosslinking agent include basic polyamine compounds, polyfunctional epoxy compounds, etc. The crosslinking agent may be used alone or in combination of two or more.

[0022] Examples of the crosslinked polyaspartic acid include a crosslinked polyaspartic acid (see International Publication No. 2023 / 155523) which is a reaction product of poly(succinimide) (PSI), a compound (A) having a first functional group (a1) and a second functional group (a2), and a polyfunctional epoxy compound (B). The crosslinked polyaspartic acid includes a PSI-a1(A) bond formed by an addition reaction of the first functional group (a1) and poly(succinimide) (PSI), and a B-a2(A) bond formed by a reaction of the second functional group (a2) and the polyfunctional epoxy compound (B). The crosslinked polyaspartic acid includes a crosslinked structure (PABAP) represented by PSI-a1-A1-a2-B-a2-A1-a1-PSI. A part of the crosslinked structure (PABAP) (for example, an unreacted portion of PSI) may be hydrolyzed. The second functional group of the compound (A) does not react with poly(succinimide) (PSI) or has a lower reactivity with poly(succinimide) (PSI) than the first functional group.

[0023] Compound (A): The first functional group (a1) of the compound (A) is preferably an amino group (NH2-). The amino group of the first functional group (a1) is more preferably the amino group of NH2-CH2-.

[0024] The second functional group (a2) of the compound (A) is preferably an amino group (NH2-) or a phosphonooxy group ((OH)2P(=O)-O-), and more preferably an amino group (NH2-). When the second functional group (a2) is an amino group (NH2-), the amino group of the second functional group (a2) is preferably the amino group in the structure represented by the following formula (3).

[0025]

Chemical formula

[0026] When G is a carboxylate group, it may form a salt with a cation. Examples of such salts include alkali metal salts such as sodium salt and potassium salt; alkaline earth metal salts such as calcium salt and magnesium salt; organic base salts such as amine salts; basic amino acid salts such as lysine salt and arginine salt. Among them, alkali metal salts are preferred, and sodium salt or potassium salt is more preferred.

[0027] When both the first functional group (a1) and the second functional group (a2) of the compound (A) are amino groups (NH2-), the amino group of the second functional group of the compound (A) is preferably less reactive with poly(succinimide) (PSI) than the amino group of the first functional group. Examples of such a compound (A) include diamines having different terminal structures containing each amino group. For example, asymmetric diamines and the like can be mentioned.

[0028] Examples of the compound (A) in which the first functional group (a1) is an amino group of NH2-CH2- and the amino group of the second functional group (a2) is the amino group in the structure represented by the above formula (1) include the compound represented by the following formula (4).

[0029]

Chemical formula

[0030] In the above formula (4), n is preferably an integer of 2 to 8, more preferably an integer of 3 to 5.

[0031] The carboxy group of the compound (A) represented by the above formula (4) may form a salt. In that case, examples of the salt include alkali metal salts such as sodium salt and potassium salt; alkaline earth metal salts such as calcium salt and magnesium salt; organic base salts such as amine salts; basic amino acid salts such as lysine salt and arginine salt. Among them, alkali metal salts are preferred, and sodium salt or potassium salt is more preferred.

[0032] When the first functional group (a1) is an amino group and the second functional group (a2) is also an amino group, examples of the compound (A) in which the first functional group (a1) is an amino group of NH2-CH2- and the amino group of the second functional group (a2) is the amino group in the structure represented by the above formula (1) include compounds represented by the following formula (5).

[0033] [Chemical formula] [In the formula, L represents a divalent linking group.]

[0034] In the above formula (5), examples of the divalent linking group in L include a linear or branched alkylene group, a combination of a linear or branched alkylene group and an ether bond, a combination of a methylene group and an ester bond, and the like. L is preferably a linear alkylene group, and the number of carbon atoms of the linear alkylene group is preferably 1 to 10, more preferably 2 to 8, and even more preferably 2 to 5.

[0035] The carboxy group of the compound (A) represented by the above formula (5) may form a salt. Examples of the salt include alkali metal salts such as sodium salt and potassium salt; alkaline earth metal salts such as calcium salt and magnesium salt; organic base salts such as amine salts; basic amino acid salts such as lysine salt and arginine salt. Among them, alkali metal salts are preferred, and sodium salt or potassium salt is more preferred.

[0036] When the first functional group (a1) of the compound (A) is an amino group and the second functional group (a2) is a phosphonooxy group ((OH)2P(=O)-O-), the compound represented by the following formula (6) can be mentioned.

[0037] [Chemical formula] [In the formula, L represents a divalent linking group.]

[0038] Examples of the divalent linking group in L in the formula (6) are the same as those of the divalent linking group in L in the formula (5). L in the formula (6) is preferably a linear alkylene group, and the number of carbon atoms of the linear alkylene group is preferably 1 to 10, more preferably 2 to 8, and even more preferably 3 to 5.

[0039] In the compound (A), the phosphonooxy group of the compound represented by the formula (6) may form a salt. Examples of the salt include alkali metal salts such as sodium salt and potassium salt; alkaline earth metal salts such as calcium salt and magnesium salt; organic base salts such as amine salt; basic amino acid salts such as lysine salt and arginine salt. Among them, alkali metal salts are preferred, and sodium salt or potassium salt is more preferred.

[0040] Specific examples of the compound (A) include lysine, ornithine, arginine, phosphorylethanolamine, etc.

[0041] When the compound (A) contains an amino group, the acidic salt of the compound (A) may be used as a raw material. Examples of the acidic salt of the compound (A) include hydrochlorides such as lysine hydrochloride, ornithine hydrochloride, and arginine hydrochloride, and similar sulfates.

[0042] As the compound (A), a dipeptide can be used. Examples of the dipeptide include dipeptides having a basic amino acid residue at the C-terminus such as glycine-lysine (isopeptide bond), alanine-lysine (isopeptide bond), glycine-lysine-ornithine (isopeptide bond), alanine-ornithine (isopeptide bond); dipeptides having a basic amino acid residue at the N-terminus such as lysine-glycine, lysine-alanine, ornithine-glycine, ornithine-alanine, etc.

[0043] Polyfunctional epoxy compound (B): The polyfunctional epoxy compound is a compound containing two or more epoxy groups. Examples of the polyfunctional epoxy compound include polyglycidyl ethers of alkane polyols (e.g., having 2 to 6 carbon atoms) or poly(alkylene glycols) (e.g., having 2 to 6 carbon atoms) such as ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, propylene glycol diglycidyl ether, butanediol diglycidyl ether; polyglycidyl ethers of alkane polyols (e.g., having 2 to 6 carbon atoms) and poly(alkylene glycols) (e.g., having 2 to 6 carbon atoms) such as sorbitol polyglycidyl ether, pentaerythritol polyglycidyl ether, erythritol polyglycidyl ether, trimethylolethane polyglycidyl ether, trimethylolpropane polyglycidyl ether; diepoxyalkanes (e.g., having 4 to 8 carbon atoms) such as 1,2,3,4-diepoxybutane, 1,2,4,5-diepoxypentane, 1,2,5,6-diepoxyhexane, 1,2,7,8-diepoxyoctane, 1,4- and 1,3-divinylbenzene epoxide; polyphenol polyglycidyl ethers (e.g., having 6 to 15 carbon atoms) such as 4,4'-isopropylidenediphenol diglycidyl ether (bisphenol A diglycidyl ether) and hydroquinone diglycidyl ether, etc. Examples of commercially available polyfunctional epoxy compounds include Nagase ChemteX's polyfunctional epoxy compounds EX-810, EX-861, EX-313, EX-614B, EX-512, etc. The polyfunctional epoxy compound is preferably a bifunctional epoxy compound, more preferably an alkylene glycol diglycidyl ether, and even more preferably ethylene glycol diglycidyl ether.

[0044] Examples of the polyaspartic acid crosslinked product, which is a reaction product of poly(succinimide) (PSI), compound (A), and polyfunctional epoxy compound (B), include polymers containing a crosslinked structure represented by the following formula (7).

[0045] [Chemical formula] [In the formula, L 1 and L 2 are each independently a divalent linking group. * represents a bond connecting to adjacent aspartic acid monomer units. The carboxy group in the formula may form a salt.]

[0046] Examples of the divalent linking group in L 1 in the formula (7) are the same as those of the divalent linking group in L in the formula (5). L 1 is preferably a linear alkylene group, and the number of carbon atoms of the linear alkylene group is preferably 1 to 10, more preferably 2 to 8, and even more preferably 2 to 5.

[0047] Examples of the divalent linking group in L 2 in the formula (7) are the same as those of the divalent linking group in L in the formula (5). L 2 is preferably a polyalkyleneoxy group, more preferably a polyethyleneoxy group or a polypropyleneoxy group, and even more preferably a polyoxyethylene group. The number of carbon atoms of the polyalkyleneoxy group is preferably 1 to 10, more preferably 2 to 8, and even more preferably 2 to 4.

[0048] The carboxy group in the formula (7) may form a salt. Examples of the salt include the same ones as described above. As the salt formed by the carboxy group in the formula (7), an alkali metal salt is preferable, and a sodium salt or a potassium salt is more preferable.

[0049] Examples of the polyaspartic acid crosslinked product, which is a reaction product of poly(succinimide) (PSI), compound (A), and polyfunctional epoxy compound (B), include a polyaspartic acid crosslinked product that is a reaction product of poly(succinimide) (PSI), L-lysine, and ethylene glycol diglycidyl ether; a polyaspartic acid crosslinked product that is a reaction product of poly(succinimide) (PSI), ornithine, and ethylene glycol diglycidyl ether; a polyaspartic acid crosslinked product that is a reaction product of poly(succinimide) (PSI), phosphorylethanolamine, and ethylene glycol diglycidyl ether, and the like.

[0050] Examples of the polyaspartic acid crosslinked product, which is a reaction product of poly(succinimide) (PSI), L-lysine, and ethylene glycol diglycidyl ether, include polymers containing a crosslinked structure represented by the following formula (8).

[0051] [Chemical formula] [In the formula, * represents a bond that binds to an adjacent aspartic acid monomer unit. The carboxy group in the formula may form a salt. ]

[0052] The carboxy group in the formula (8) may form a salt. Examples of the salt include the same ones as described above. As the salt formed by the carboxy group in the formula (7), an alkali metal salt is preferable, and a sodium salt or a potassium salt is more preferable.

[0053] The polyaspartic acid crosslinked product, which is a reaction product of poly(succinimide) (PSI), compound (A), and polyfunctional epoxy compound (B), can be produced by the method described in International Publication No. 2023 / 155523. For example, the polyaspartic acid crosslinked product can be produced by reacting poly(succinimide) (PSI), compound (A), and polyfunctional epoxy (B) in water or a water-containing solvent to form a crosslinked product. The reaction order of poly(succinimide) (PSI), compound (A), and polyfunctional epoxy (B) is not particularly limited. For example, the following three production methods can be mentioned. (i) A production method including a step of reacting poly(succinimide) (PSI) and compound (A) to obtain a reaction product (P1) of poly(succinimide) (PSI) and compound (A), and a step of reacting the reaction product (P1) with a polyfunctional epoxy compound. (ii) A production method in which poly(succinimide) (PSI) and compound (A) are first mixed and reacted, and then a polyfunctional epoxy compound is added at a constant rate. (iii) A production method in which poly(succinimide) (PSI), compound (A), and a polyfunctional epoxy compound are mixed and then reacted.

[0054] The crosslinking degree (the ratio of crosslinked units to all units) of the polyaspartic acid crosslinked product is not particularly limited. For example, in the case of a polyaspartic acid crosslinked product that is a reaction product of poly(succinimide) (PSI), compound (A), and polyfunctional epoxy compound (B), in poly(succinimide) (PSI), the ratio (addition rate) of the units to which compound (A) is added is preferably 1 to 20% with respect to all units, more preferably 3 to 15%, and still more preferably 5 to 10%. The addition rate can be measured by NMR.

[0055] One or more of the carboxy groups of the uncrosslinked aspartic acid monomer units in the polyaspartic acid crosslinked product may be in the form of a salt. Examples of the salt include alkali metal salts (sodium salt, potassium salt, etc.), alkaline earth metal salts (calcium salt, magnesium salt, etc.), ammonium salts, amine salts (trimethylamine salt, triethylamine salt, etc.), and the like.

[0056] The polyaspartic acid crosslinked product may be dried if necessary and physically pulverized to obtain particles of the polyaspartic acid crosslinked product. The drying method is not particularly limited, and for example, known methods such as heat drying, freeze drying, reduced pressure (vacuum) drying, and reduced pressure heat drying can be arbitrarily implemented. In the case of heat drying, the drying temperature is usually in the range of 60°C to 250°C, preferably 80°C to 220°C, more preferably 100°C to 200°C. In the case of reduced pressure heat drying, the drying temperature is usually in the range of 50°C to 200°C, preferably 60°C to 150°C, more preferably 70°C to 120°C. The size (average particle diameter) of the polyaspartic acid crosslinked product particles is preferably 1 to 5000 μm, more preferably 10 to 2000 μm, still more preferably 200 to 2000 μm, and particularly preferably 500 to 2000 μm. The size of the polyaspartic acid crosslinked product particles may be adjusted by performing operations such as particle size adjustment using classification by a sieve.

[0057] The surface of the polyaspartic acid crosslinked product particles may be crosslinked (surface crosslinked). By performing surface crosslinking, it is easy to control the water retention characteristics of the polyaspartic acid crosslinked product particles. Surface crosslinking is preferably performed at the timing when the polyaspartic acid crosslinked product particles have a specific moisture content. As the crosslinking agent (surface crosslinking agent) for performing surface crosslinking, for example, known crosslinking agents can be used. The surface crosslinking agent may be used alone or in combination of two or more. After surface crosslinking, crosslinked product particles that are surface crosslinked dried products can be obtained by distilling off water or a water-containing solvent by a known method.

[0058] The polyaspartic acid compound may be used alone or in combination of two or more.

[0059] The polyaspartic acid compound may be synthesized from a raw material produced by a living organism. For example, succinic acid, which is a raw material of the polyaspartic acid compound, may be produced using aspartic acid produced by a living organism as a raw material.

[0060] Examples of organisms that produce aspartic acid include microorganisms such as archaea, cyanobacteria, bacteria, and fungi. Since they are easy to culture, it is preferable to use bacteria as the organisms that produce aspartic acid. Examples of aspartic acid-producing bacteria include bacteria belonging to the genus Escherichia (e.g., Escherichia coli), the genus Bacillus (e.g., Bacillus subtilis), the genus Lactobacillus (e.g., Lactobacillus acidophilus), the genus Clostridium (e.g., Clostridium thermocellum, Clostridium acetobutylicum), the genus Rhodopseudomonas (e.g., Rhodopseudomonas palustris), the genus Rhodobacter (Rhodobacter capsulatus), and bacteria belonging to the genus Corynebacterium. Examples of Corynebacterium include bacteria belonging to the genus Corynebacterium, the genus Brevibacterium, the genus Arthrobacter, the genus Mycobacterium, the genus Micrococcus, the genus Microbacterium, etc.

[0061] For example, aspartic acid-producing bacteria can be cultured, and the cells can be removed from the culture broth by centrifugation or filtration, etc., and the culture supernatant can be recovered, and aspartic acid can be obtained by performing a purification treatment of aspartic acid. For the purification treatment of aspartic acid, methods generally used for separation and purification treatments such as concentration, isoelectric point crystallization, recrystallization, activated carbon treatment, and washing can be used.

[0062] (Other components) The plant growth promoter of the present embodiment may contain other components in addition to the polyaspartic acid compound. The other components are not particularly limited, and examples include water, fertilizer components, vitality agents, soil conditioners, pH adjusters, insect repellents, antibacterial agents, herbicides, etc.

[0063] (Usage method) The plant growth agent of this embodiment can be mixed and used in a cultivation medium for plants. The cultivation medium for plants is a composition used for cultivating plants and serves as a support for plant growth. Nutrients and moisture necessary for plant growth are supplied to the plants through the cultivation medium for plants. Specific examples of the cultivation medium for plants include soil, synthetic resin foam medium, liquid medium, etc. The cultivation medium for plants preferably contains nutrients necessary for plant growth. As the cultivation medium for plants, soil is preferred.

[0064] The plant growth agent of this embodiment is preferably mixed into the cultivation medium for plants so that the polyaspartic acid compound is 0.1 to 10 parts by mass with respect to 100 parts by mass of the cultivation medium for plants. By setting the ratio of the plant growth agent within the above range, the growth of plants is more likely to be better. The polyaspartic acid compound is preferably 0.5 to 10 parts by mass, and more preferably 0.6 to 10 parts by mass with respect to 100 parts by mass of the cultivation medium for plants.

[0065] For the cultivation medium for plants mixed with the plant growth agent of this embodiment, seeds of the plant are sown, bulbs of the plant are planted, or the plant body (seedling, etc.) is planted. The sowing method, planting method, and planting method can be appropriately selected according to the type of plant. Thereafter, the plants can be cultivated by a cultivation method according to the type of plant.

[0066] The plants to which the plant growth agent of this embodiment is applicable are not particularly limited. Examples of plants include vegetables, fruit trees, grains, beans, flowers, foliage plants, trees, etc. As plants, vegetables are preferred. Examples of vegetables include Brassicaceae (Komatsuna, broccoli, cabbage, Chinese cabbage, Mizuna, daikon, etc.), Solanaceae (eggplant, tomato, potato, pepper, capsicum, etc.), Asteraceae (Shungiku, lettuce, burdock, butterbur, etc.), Cucurbitaceae (cucumber, melon, watermelon, pumpkin, zucchini, winter melon, etc.), Alliaceae (onion, chives, garlic, Japanese leek, etc.).

[0067] Since the plant growth agent of this embodiment contains a polyaspartic acid compound, it has good water retention. In addition, the polyaspartic acid compound has good decomposability and is considered to be supplied to plants as a fertilizer component when decomposed. Therefore, by cultivating plants using a plant cultivation medium mixed with the plant growth agent of this embodiment, the plants can be grown well. The plant growth agent of this embodiment can be used to maintain the water retention of the plant cultivation medium. In addition, the plant growth agent of this embodiment can be used to supply fertilizer components to the plant cultivation medium.

[0068] Uncrosslinked polyaspartic acid or polyaspartate can be dissolved in water and used as an aqueous solution. Therefore, it may be used by dissolving it in water when watering plants. Polyaspartic acid or polyaspartate has better decomposability and is easily utilized by plants as a fertilizer component after decomposition. Therefore, the nutrients (especially nitrogen components) contained in the plant cultivation medium can be reduced.

[0069] The polyaspartic acid crosslinked product has better water retention. Therefore, the number of times of watering plants can be reduced. The polyaspartic acid crosslinked product can be utilized by plants as a slow-acting fertilizer component (especially nitrogen component).

[0070] <Plant cultivation composition> The second aspect of the present invention is a plant cultivation composition. In one embodiment, the plant cultivation composition contains at least one polyaspartic acid compound selected from the group consisting of polyaspartic acid, derivatives of polyaspartic acid, and salts thereof, and a plant cultivation medium.

[0071] The polyaspartic acid compound is the same as that described in the section of <Plant growth agent> above. The polyaspartic acid compound may be used alone or in combination of two or more.

[0072] Uncrosslinked polyaspartic acid or polyaspartate may be prepared as an aqueous solution and mixed with a plant cultivation medium. Alternatively, a powder of polyaspartic acid or polyaspartate may be mixed with the plant cultivation medium.

[0073] It is preferable to use particulate polyaspartic acid crosslinked products. It is preferable to mix the polyaspartic acid crosslinked product particles with the plant cultivation medium. The polyaspartic acid crosslinked product particles may be dry particles or hydrogel particles.

[0074] The plant cultivation medium is the same as that described in the section of <Plant growth promoter>. Soil is preferable as the plant cultivation medium. The plant cultivation medium preferably contains nutrients necessary for plant growth such as nitrogen, phosphorus, potassium, calcium, manganese, and sulfur. When the plant cultivation medium is soil, the soil may contain inorganic fertilizers containing nitrogen, phosphorus, potassium, etc.; organic fertilizers such as oil cakes, fish meal, chicken manure, and bone meal; soil conditioners such as compost, leaf mold, peat moss, vermiculite, zeolite, and perlite.

[0075] The plant cultivation composition of this embodiment preferably contains 0.1 to 10 parts by mass of the polyaspartic acid compound with respect to 100 parts by mass of the plant cultivation medium. By setting the ratio of the polyaspartic acid compound to 100 parts by mass of the plant cultivation medium within the above range, the growth of plants is more likely to be good. The polyaspartic acid compound is preferably 0.5 to 10 parts by mass, more preferably 0.6 to 10 parts by mass, with respect to 100 parts by mass of the plant cultivation medium.

[0076] (Usage method) The plant cultivation composition of this embodiment can be used for cultivating plants. Seeds of plants are sown, bulbs of plants are planted, or plants (seedlings, etc.) are planted in the plant cultivation composition. The sowing method, planting method, and planting method can be appropriately selected according to the type of plant. Thereafter, the plants can be cultivated by a cultivation method according to the type of plant.

[0077] Since the composition for plant cultivation of the present embodiment contains a polyaspartic acid compound, it has good water retention. Further, during plant cultivation, the polyaspartic acid compound decomposes and is supplied to plants as a fertilizer component (particularly a nitrogen component), so that the growth of plants is good.

[0078] <Method for Cultivating Plants> A third aspect of the present invention is a method for cultivating plants using the plant growth promoter according to the first aspect.

[0079] The method of using the plant growth promoter according to the first aspect is not particularly limited, but the plant growth promoter according to the first aspect may be mixed with a medium for plant cultivation to prepare a composition for plant cultivation. As the medium for plant cultivation, the same ones as described above can be used. The medium for plant cultivation is preferably soil. The composition for plant cultivation preferably contains 0.1 to 10 parts by mass of the polyaspartic acid compound with respect to 100 parts by mass of the medium for plant cultivation.

[0080] In one embodiment, the plant cultivation method includes a step of cultivating a plant with a composition for plant cultivation containing a polyaspartic acid compound selected from the group consisting of polyaspartic acid, derivatives of polyaspartic acid, and salts thereof, and a medium for plant cultivation.

[0081] (Step of Cultivating Plants) For plant cultivation, a cultivation method suitable for the plant can be selected according to the type of the plant. Examples of the type of the plant include the same ones as described above. Vegetables are preferable as the plant. Among vegetables, the Brassicaceae family is preferable. Examples of Brassicaceae vegetables include, but are not limited to, Komatsuna, broccoli, cabbage, sprout cabbage, cauliflower, kale, mustard spinach, turnip, Chinese cabbage, arugula, daikon radish, wasabi, cress, mizuna, and pak choi.

[0082] Plants can start cultivation by sowing seeds, planting bulbs, or transplanting plant bodies into a plant cultivation composition containing a polyaspartic acid compound and a plant cultivation medium.

[0083] Alternatively, seeds can be sown, bulbs can be planted, or plant bodies can be transplanted into a plant cultivation medium that does not contain a polyaspartic acid compound, and then, a plant growth agent according to the first aspect can be added to the plant cultivation medium. Since uncrosslinked polyaspartic acid and polyaspartate are water-soluble, an aqueous solution of polyaspartic acid and / or polyaspartate can be used for watering. The polyaspartic acid crosslinked product may be scattered as dry particles or hydrogel particles on the plant cultivation medium in which plants are sown, planted, or transplanted.

[0084] Alternatively, after sowing seeds, planting bulbs, or transplanting plant bodies into a plant cultivation composition containing a polyaspartic acid compound and a plant cultivation medium, the polyaspartic acid compound can be additionally added at any time.

[0085] In the plant cultivation method of this embodiment, since the plant growth agent according to the first aspect is used, plants can grow well.

[0086] As described above, the specific embodiments of the present invention have been described in detail, but the present invention is not limited to the above-described embodiments. Various modifications, corrections, and combinations can be adopted for each component, element, and feature without departing from the gist of the present invention. The terms "comprising" and "having" do not exclude the existence of elements other than the elements referred to as the object, respectively, unless otherwise specified, and these terms are used interchangeably. A numerical range represented by "~" means a range including the numerical values described before and after "~" as the lower limit value and the upper limit value. The content of each document referred to in this specification is incorporated herein as part of this specification.

Examples

[0087] Hereinafter, the present invention will be described by way of examples, but the present invention is not limited to the following examples.

[0088] <Raw materials> Aspartic acid: manufactured by YIXING QIANCHENG BIO-ENGINEERING, 99.97% purity Phosphoric acid: manufactured by Kanto Chemical Co., Inc., 85% purity L-Lysine: manufactured by Tokyo Chemical Industry Co., Ltd., 97% purity Polyfunctional epoxy compound: manufactured by Nagase ChemteX Corporation, EX-810

[0089] <Measurement of weight average molecular weight of polysuccinimide> The weight average molecular weight of polysuccinimide was determined as a polystyrene equivalent value by the GPC method (differential refractometer). For the measurement, G1000HHR column, G4000HHR column, and GMHHR-H column (TSKgel (registered trademark), Tosoh Corporation) were used. As the eluent, dimethylformamide containing 10 mM lithium bromide was used.

[0090] <Synthesis example 1: Synthesis of polysuccinimide> 160 parts of aspartic acid and 83 parts of 85 wt% phosphoric acid were mixed in a mortar, transferred to a tray, and reacted at 190 °C and 1.3 kPa for 6 hours. After pulverizing the reaction mixture, it was washed with distilled water until the filtrate became neutral, and vacuum dried at 80 °C to obtain 115 parts of polysuccinimide having a weight average molecular weight of 80,000.

[0091] <Synthesis example 2: Synthesis of potassium polyaspartate> 30 parts of the polysuccinimide obtained in Synthesis example 1 was added to 60 parts of distilled water and dispersed. To the obtained dispersion, 35.4 parts of a 48 wt% KOH aqueous solution was added dropwise with stirring at room temperature. After completion of the dropwise addition, the mixture was further stirred at room temperature for 10 hours. The obtained reaction solution was filtered through a 59 μm nylon mesh to obtain an aqueous solution of potassium polyaspartate (solid content: 39 wt%).

[0092] <Synthesis example 3: Synthesis of crosslinked polyaspartic acid (1)> 2.23 parts of L-lysine was added to 20 parts of distilled water and stirred until dissolved. Next, 10 parts of the poly(succinimide) obtained in Synthesis Example 1 was added to the resulting aqueous L-lysine solution. While adjusting the pH to 10 - 11, 9.75 parts of a 36 wt% aqueous NaOH solution was added dropwise with stirring at room temperature. After completion of the dropwise addition, stirring was continued at room temperature for an additional 15 hours. The resulting reaction solution was filtered through a 59 μm nylon mesh to obtain a sodium lysine-added polyaspartate solution (43% by solid content). From the NMR analysis results, the ratio of the units to which lysine was added was 9.2% with respect to all units.

[0093] 4.64 parts of the sodium lysine-added polyaspartate solution obtained above and 0.106 part of a polyfunctional epoxy compound EX-810 (ethylene glycol diglycidyl ether; manufactured by Nagase ChemteX) were mixed, and a heating reaction was carried out at 60 °C to obtain a crosslinked polyaspartic acid (1).

[0094] Also, the gel composition obtained at a reaction time of 180 minutes was freeze-dried, the dried composition was pulverized in a mortar, and passed through a mesh to be 150 - 710 μm using a stainless steel sieve (JIS Z-8801).

[0095] <Synthesis Example 4: Synthesis of crosslinked polyaspartic acid (2)> 10 parts of the poly(succinimide) obtained in Synthesis Example 1 was mixed with 40 parts of dimethylformamide and stirred at 60 °C for 5 hours until dissolved. While warming the solution to 40 °C, a solution prepared by mixing 0.375 part of L-lysine monohydrochloride, 0.535 part of a 22.4% aqueous sodium hydroxide solution, and 0.375 part of ion-exchanged water was added dropwise, and the reaction was carried out for 8 hours while maintaining the temperature at 40 °C. The resulting gel was added to 500 parts of ion-exchanged water and pulverized with a mixer. After filtration, it was washed with 150 parts of methanol for 1 hour and vacuum-dried at 60 °C to obtain 10.3 parts of crosslinked poly(succinimide). 3.0 parts of the obtained crosslinked poly(succinimide) was dispersed in 20 parts of methanol and 10 parts of ion-exchanged water. A solution prepared by mixing 2.4 parts of a 48% aqueous sodium hydroxide solution and 2.4 parts of methanol was added dropwise, followed by reacting for 15 hours. The reaction solution was poured into 400 parts of methanol, and the precipitate was collected by filtration and further washed with 100 parts of methanol. It was dried under vacuum at 60 °C. The dried product was pulverized and passed through a stainless steel sieve (JIS Z-8801) to obtain a particle size of 150 - 710 μm.

[0096] <Cultivation Test (1)> (Example 1) Komatsuna seeds (Kaneko Seedling Co., Ltd.) were sown in a rock wool block containing sufficient water, and grown for several days at 25 °C to germinate. To the culture soil (manufactured by Hyponex Japan Co., Ltd., trade name "Soil for Sprouting, Sowing, and Seedling Raising"), an aqueous potassium polyaspartate solution obtained in Synthesis Example 2 was added and mixed so that the solid content was 0.625 g per 100 g of the culture soil. 100 g of the mixed culture soil was put into a resin pot (outer diameter 10.5 cm, bottom diameter 7.5 cm, height 9 cm), and the surface was leveled. Then, the komatsuna germinated in the rock wool was transplanted. Appropriate irrigation was carried out at 25 °C to grow the komatsuna. 30 days after sowing, the number of leaves was counted and the length of each leaf was measured.

[0097] (Example 2) Komatsuna was grown in the same manner as in Example 1, except that the addition amount of the aqueous potassium polyaspartate solution was adjusted so that the solid content was 3.75 g per 100 g of the culture soil. 30 days after sowing, the number of leaves was counted and the leaf length was measured.

[0098] (Comparative Example 1) Komatsuna was grown in the same manner as in Example 1, except that the aqueous potassium polyaspartate solution was not added to the culture soil. 30 days after sowing, the number of leaves was counted and the leaf length was measured.

[0099] The results are shown in Table 1.

[0100]

Table 1

[0101] As shown in Table 1, in Examples 1 and 2, the growth of Komatsuna was good compared with that in Comparative Example 1. Regarding the addition amount of potassium polyaspartate, the larger the amount, the better the growth of Komatsuna was.

[0102] <Measurement of Soil Water Retention> To the culture soil (manufactured by Hyponex Japan Co., Ltd., trade name "Soil for Sprouting, Sowing, and Seedling Raising"), the aqueous potassium polyaspartate solution obtained in Synthesis Example 2, the cross-linked potassium polyaspartate (1) obtained in Synthesis Example 3, or the cross-linked potassium polyaspartate (2) obtained in Synthesis Example 4 was added and mixed so that the solid content was in a ratio of 3.75% with respect to 100 g of the culture soil. 100 g of the mixed culture soil was put into a resin pot (outer diameter 10.5 cm, bottom diameter 7.5 cm, height 9 cm), and water was added sufficiently until water came out from the bottom hole of the pot. The weight after standing for 30 minutes was measured, and the difference from the added culture soil was defined as the initial water content W0. This pot was subjected to a drying treatment in a natural convection dryer set at 60°C. It was taken out after 5 hours and the weight was measured, and the difference from the added culture soil was defined as the water content W1 after 5 hours. Based on the following formula, the soil water retention (i.e., the water retention rate after 5 hours) was calculated. Soil water retention (%) = 100 - (W0 - W1) / W0 × 100

[0103] The results are shown in Table 2 as the "water retention rate". Note that the water retention rate of the blank with only the culture soil was 28%.

[0104] <Measurement of Soil Degradability> The soil degradabilities of the aqueous potassium polyaspartate solution obtained in Synthesis Example 2, the cross-linked potassium polyaspartate (1) obtained in Synthesis Example 3, and the cross-linked potassium polyaspartate (2) obtained in Synthesis Example 4 were evaluated by determining the biodegradability by the following biodegradability measurement method.

[0105] The soil used was collected from the Oshinotsuka Citizen's Farm (near Oshinotsuka, Sakura City, Chiba Prefecture). Method for measuring biodegradability: Soda lime (carbon dioxide absorbent) and a pressure sensor (manufactured by WTW, OxiTop-IDS (registered trademark)) were attached to a test bottle, and BOD (biochemical oxygen demand) was measured under the following conditions to calculate the biodegradability. Amount of soil: 30 g Amount of sample: 100 mg Cultivation temperature: 27 °C, in the dark Cultivation period: 60 days Calculation of biodegradability: The biodegradability of the sample was calculated based on the following formula. Biodegradability (%) = (BOD0 - BODB) / ThOD × 100 BOD0: Biochemical oxygen demand of the sample (measured value: mg) BODB: Average biochemical oxygen demand of the blank test (measured value: mg) ThOD: Theoretical oxygen demand required when the sample is completely oxidized (calculated value: mg)

[0106] The biodegradability obtained by the above biodegradability measurement method was evaluated based on the following evaluation criteria. The results are shown in Table 2 as "soil degradability". Evaluation criteria: A: Biodegradability is 50% or more B: Biodegradability is 40% or more and less than 50% C: Biodegradability is 24% or more and less than 40% D: Biodegradability is 15% or more and less than 24% E: Biodegradability is less than 15%

[0107]

Table 2

[0108] As shown in Table 2, in all cases where any additive was used, the water retention rate was improved compared to the blank without additive. The water retention rates, in descending order, were polyaspartic acid cross-linked product (1), polyaspartic acid cross-linked product (2), and potassium polyaspartate. The soil decomposability of potassium polyaspartate was better than that of the polyaspartic acid crosslinked product (1) and the polyaspartic acid crosslinked product (2).

[0109] <Cultivation test (2)> (Example 3) Komatsuna was grown in the same manner as in Example 1, except that the polyaspartic acid crosslinked product (1) obtained in Synthesis Example 3 was used instead of the aqueous potassium polyaspartate solution, and the solid content thereof was adjusted to a ratio of 0.625 g per 100 g of the culture soil. Thirty days after sowing, the number of leaves was counted and the leaf length was measured.

[0110] (Example 4) Komatsuna was grown in the same manner as in Example 1, except that the polyaspartic acid crosslinked product (1) obtained in Synthesis Example 3 was used instead of the aqueous potassium polyaspartate solution, and the solid content thereof was adjusted to a ratio of 3.75 g per 100 g of the culture soil. Thirty days after sowing, the number of leaves was counted and the leaf length was measured.

[0111] (Example 5) Komatsuna was grown in the same manner as in Example 1, except that the polyaspartic acid crosslinked product (2) obtained in Synthesis Example 4 was used instead of the aqueous potassium polyaspartate solution, and the solid content thereof was adjusted to a ratio of 0.625 g per 100 g of the culture soil. Thirty days after sowing, the number of leaves was counted and the leaf length was measured.

[0112] (Example 6) Komatsuna was grown in the same manner as in Example 1, except that the polyaspartic acid crosslinked product (2) obtained in Synthesis Example 4 was used instead of the aqueous potassium polyaspartate solution, and the solid content thereof was adjusted to a ratio of 3.75 g per 100 g of the culture soil. Thirty days after sowing, the number of leaves was counted and the leaf length was measured.

[0113] The results are shown in Table 3.

[0114]

Table 3

[0115] As shown in Table 3, in Examples 3 to 4, the growth of Komatsuna was good. The larger the addition amount of the polyaspartic acid crosslinked product, the better the growth of Komatsuna. When the polyaspartic acid crosslinked product (1) was added, the growth of Komatsuna was better than that when the polyaspartic acid crosslinked product (2) was added. This result indicates that when using the above-mentioned compound (A) and the polyfunctional epoxy compound as the crosslinking agent, a polyaspartic acid crosslinked product with higher performance as a plant growth agent can be obtained compared with the case of using only the polyfunctional amine compound.

[0116] In Examples 3 to 6, the growth of Komatsuna was good compared with Examples 1 and 2 shown in Table 1. This result indicates that the polyaspartic acid crosslinked product has higher performance as a plant growth agent compared with the polyaspartic acid salt.

[0117] <Cultivation Test (3)> (Example 7) The seeds of Komatsuna (Kaneko Seedling Co., Ltd.) were sown in a rock wool block containing sufficient water, and grown for several days in an environment at 25°C to germinate. To the culture soil (manufactured by Hyponex Japan Co., Ltd., trade name "Soil for sowing, seeding, and raising seedlings") added with a nutrient agent (Rainbow Chemical Co., Ltd., Green Ample; 33 ml / 100 g of soil), the polyaspartic acid crosslinked product (1) obtained in Synthesis Example 3 was added and mixed so that the solid content was at a ratio of 3.75 g per 100 g of the culture soil. After putting 100 g of the mixed culture soil into a resin pot (outer diameter 10.5 cm, bottom diameter 7.5 cm, height 9 cm) and leveling the surface, the Komatsuna germinated in the rock wool was transplanted. Appropriate irrigation was carried out in an environment at 25°C to grow Komatsuna. After 15 days from sowing, no water was given. After growing for one week without giving water, the appearance of Komatsuna was observed.

[0118] (Comparative Example 2) Komatsuna was grown in the same manner as in Example 7, except that the polyaspartic acid cross-linked product (1) was not added to the culture soil. Starting 15 days after sowing, it was grown for one week without watering, and the appearance of the komatsuna was observed.

[0119] The results are shown in Table 4. A photograph of the komatsuna is shown in Figure 1.

[0120]

Table 4

[0121] As shown in Table 4 and Figure 1, in Example 1, the komatsuna did not wither and maintained large leaves. On the other hand, in Comparative Example 2, the komatsuna withered and could not maintain large leaves. These results confirmed that the polyaspartic acid cross-linked product (1) has good water retention, and that by using the polyaspartic acid cross-linked product (1) as a plant growth promoter, the labor of watering can be reduced.

Industrial Applicability

[0122] According to the present invention, there are provided a plant growth promoter, a plant cultivation composition containing the plant growth promoter, and a plant cultivation method using the plant growth promoter, which can promote the growth of plants and have high biodegradability.

Claims

1. A plant growth agent comprising at least one polyaspartic acid compound selected from the group consisting of polyaspartic acid, derivatives of polyaspartic acid, and salts thereof.

2. The plant growth agent according to claim 1, which is used by being mixed with a plant cultivation medium.

3. The plant growth agent according to claim 2, which is used to maintain the water retention of the plant cultivation medium.

4. The plant growth agent according to claim 2 or 3, which is used to supply a fertilizer component to the plant cultivation medium.

5. The plant growth agent according to claim 2 or 3, which is mixed with the plant cultivation medium such that the polyaspartic acid compound is 0.1 to 10 parts by mass with respect to 100 parts by mass of the plant cultivation medium.

6. The plant growth agent according to claim 2 or 3, wherein the plant cultivation medium is soil.

7. The plant growth agent according to claim 1 or 2, wherein the polyaspartic acid compound is synthesized from a raw material produced by an organism.

8. The plant growth agent according to claim 1 or 2, wherein the derivative of polyaspartic acid is a cross-linked product of polyaspartic acid.

9. A plant cultivation composition containing at least one polyaspartic acid compound selected from the group consisting of polyaspartic acid, derivatives of polyaspartic acid, and salts thereof, and a plant cultivation medium.

10. The plant cultivation composition according to claim 9, which contains 0.1 to 10 parts by mass of the polyaspartic acid compound with respect to 100 parts by mass of the plant cultivation medium.

11. The plant cultivation composition according to claim 9 or 10, wherein the plant cultivation medium is soil.

12. A method for cultivating a plant using the plant growth agent according to any one of claims 1 to 3.

13. A method for cultivating a plant, comprising the step of cultivating the plant with a plant cultivation composition containing at least one polyaspartic acid compound selected from the group consisting of polyaspartic acid, derivatives of polyaspartic acid, and salts thereof, and a plant cultivation medium. The method for cultivating a plant according to claim 12.

14. The method for cultivating a plant according to claim 13, wherein the plant cultivation composition contains 0.1 to 10 parts by mass of the polyaspartic acid compound with respect to 100 parts by mass of the plant cultivation medium.

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