Fertilizer composition

Abstract

The purpose of the present invention is to provide: a fertilizer composition which is absorbed into a cultivated plant to promote the growth thereof and which is capable of emitting fluorescence from the cultivated plant by irradiation with light; and a method for efficiently cultivating a plant using the fertilizer composition. The fertilizer composition comprises 100 parts by mass of nitrogen-containing carbon oxide quantum dots, 0.1-1000 parts by mass of a phosphorus compound, and 0.1-100 parts by mass of a potassium salt. A cultivation method according to the present invention comprises a step for supplying such a fertilizer composition to a plant and / or a culture medium. The nitrogen-containing carbon oxide quantum dots are preferably graphene quantum dots having nitrogen-containing functional groups and carbonyl groups. It is preferable that the content of nitrogen atoms and / or oxygen atoms per 100 parts by mass is 0.1-60 parts by mass.

Description

Technical Field

[0001] The present invention relates to a fertilizer composition containing carbon quantum dots and a cultivation method using the fertilizer composition. Background Art

[0002] In recent years, from the perspective of agricultural efficiency and environmental protection, nanocarbon materials such as carbon nanotubes (CNTs) have attracted attention. Fertilizers have been used to cultivate and grow crops, but general fertilizers are not necessarily efficiently absorbed by the plants to be cultivated. For example, most general-purpose natural fertilizers must be decomposed by microorganisms before they can be absorbed by plants. Although chemical fertilizers such as ammonium sulfate and / or ammonium nitrate do not require microbial decomposition, their osmotic pressure will be greatly increased if dissolved in water. Therefore, they cannot be used as high-concentration liquid fertilizers, nor can they be directly applied to roots and / or leaves. There are also reports that the amount of fertilizers applied to the soil that is actually absorbed by plants is less than about 50% (for example, Non-Patent Document 1). As a result, fertilizers that are not absorbed by plants are not utilized.

[0003] Unused fertilizers are not only a waste, but also sometimes cause environmental pollution by outflowing and / or being discharged into the atmosphere due to rainfall etc. Other pesticides such as insecticides, herbicides, antimicrobials etc. are also the same. Here, it is believed that if pesticides such as fertilizers are nano-sized, they easily pass through between the cells of plants, even if they do not accept the decomposition of microorganisms, they are easily absorbed into the plants. Moreover, they can enter the plants not only from the roots but also from the leaves. In this way, if fertilizers are taken into plants before diffusion disappears, the utilization rate of nutrients can be improved and the harvest amount can be increased. For such consideration, various nano-carbon materials, particularly carbon quantum dots, have recently been applied to the research of agricultural purposes (for example, non-patent literature 1, 2).

[0004] Here, quantum dots are nanoscale materials that follow quantum chemistry and quantum mechanics, and are usually microparticles with an average diameter of about 0.5nm to 100nm. Due to their unique optical properties, they are studied as fluorescent materials and are used in light-emitting elements and / or displays, and even battery materials (Patent Documents 1 to 5). In the agricultural field, they are also studied as elements that convert infrared light and / or ultraviolet light into visible light suitable for photosynthesis, and research cases of their use as fertilizers have recently been reported. Carbon quantum dots are also studied as carriers of pesticides such as fungicides and / or mineral components such as zinc, copper, and iron, and recombinant genes. Furthermore, due to their fluorescent properties, they are also considered to be a powerful candidate material that can be used in the following new cultivation method, in which the state of fluorescence from the plant body is observed each time, and the appropriate cultivation environment is adjusted based on this (Non-Patent Documents 1 and 2).

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Re-publication No. WO2016 / 129441

[0008] Patent Document 2: Japanese Patent Application Laid-Open No. 2017-43539

[0009] Patent Document 3: Japanese Patent Application Laid-Open No. 2017-165633

[0010] Patent Document 4: Japanese Patent Application No. 2017-538041

[0011] Patent Document 5: Japanese Patent Application Laid-Open No. 2021-111574

[0012] Non-patent literature

[0013] Non-patent literature 1: L. Zhu, et al., Plants, 2022, 11, 511

[0014] Non-patent literature 2: J. Peralta-Videa, et al., Processes, 2020, 8,445 Summary of the Invention

[0015] Technical problem to be solved by the invention

[0016] However, the application of this nano-carbon material in agriculture is in the early stages of research, and even from the reported examples, it is difficult to say that the effect and reproducibility have been fully confirmed. For example, non-patent literature 2 records the research examples of using carbon quantum dots as fertilizers to increase the harvest amount and the examples of reducing the total weight of organisms. Most of the reported examples are based on short-term discussions in the laboratory, and what kind of nano-carbon material is actually useful as a fertilizer is still in the exploratory stage. The fluorescence of carbon quantum dots taken into organisms, etc., also stays at the stage of observing organisms such as fungi under a microscope. As for the examples of visually observing the fluorescence in cultivated plants, it seems that no report has yet been made.

[0017] To address the above-mentioned problems, the present invention aims to provide a fertilizer composition that, when ingested into cultivated plants, promotes their growth and can emit fluorescence from the cultivated plants upon irradiation with light. Another object of the present invention is to provide a method for efficiently cultivating plants by supplying such a fertilizer composition to cultivated plants to promote their growth and controlling the cultivation environment based on the fluorescence state.

[0018] Solutions to Problems

[0019] To address the above-mentioned issues, the inventors conducted intensive research and discovered that by using nitrogen-containing carbon oxide quantum dots as nanocarbon materials and combining them with specific amounts of phosphorus compounds and potassium salts, a fertilizer composition useful for cultivating cultivated plants can be obtained. The inventors also discovered that plants cultivated and grown using these fertilizer compositions internally incorporate the carbon quantum dots, which, in turn, emit fluorescence upon exposure to light, leading to the completion of the present invention.

[0020] That is, the present invention provides the following (1) to (8).

[0021] (1) A fertilizer composition comprising 100 parts by mass of nitrogen-containing carbon oxide quantum dots, 0.1 to 1000 parts by mass of a phosphorus compound, and 0.1 to 100 parts by mass of a potassium salt.

[0022] (2) The fertilizer composition according to (1) above, wherein the nitrogen-containing carbon oxide quantum dots are graphene-based quantum dots having a nitrogen-containing functional group and a carbonyl group.

[0023] (3) The fertilizer composition according to (1) or (2) above, wherein the content of nitrogen atoms in 100 parts by mass of the nitrogen-containing oxidized carbon quantum dots is 0.1 parts by mass to 60 parts by mass.

[0024] (4) The fertilizer composition according to any one of (1) to (3) above, wherein the content of oxygen atoms in 100 parts by mass of the nitrogen-containing oxidized carbon quantum dots is 0.1 parts by mass to 60 parts by mass.

[0025] (5) The fertilizer composition according to any one of (1) to (4) above, wherein the phosphorus compound is a derivative of phosphoric acid.

[0026] (6) An aqueous fertilizer comprising the fertilizer composition according to any one of (1) to (5) above at a solid content concentration of 0.001% by mass to 90% by mass.

[0027] (7) A cultivation method comprising the step of supplying the fertilizer composition according to any one of (1) to (5) above to a plant and / or a culture medium.

[0028] (8) A cultivation method comprising:

[0029] a step of supplying the fertilizer composition according to any one of (1) to (5) above to the plant and / or culture medium; and

[0030] A process of irradiating the plants with light having a wavelength of 200 nm to 900 nm and controlling the cultivation environment according to the light emission state of the plants at that time.

[0031] Effects of the Invention

[0032] The fertilizer composition of the present invention can be effectively incorporated into cultivated plants to promote their growth. This results in improved nutrient utilization, which in turn increases harvest yields, thereby making it possible to increase agricultural efficiency. It can also reduce environmental pollution caused by the loss or dissipation of unused fertilizer. Furthermore, after being incorporated into cultivated plants, the fluorescein emits fluorescence upon exposure to light. This fluorescence allows the plant's condition to be monitored at all times and the cultivation environment to be controlled accordingly, thus enabling efficient plant cultivation. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 These are photographs showing the growth states of the cultivated plants in Example 1 and Comparative Examples 1 and 2.

[0034] Figure 2 These are photographs showing the fluorescence state of cultivated plants when irradiated with ultraviolet light in Example 2 and Comparative Example 2. DETAILED DESCRIPTION

[0035] Representative embodiments of the present invention will be described in detail below, but the present invention is not limited thereto.

[0036] <<Fertilizer Composition>>

[0037] The present embodiment relates to a fertilizer composition comprising 100 parts by mass of nitrogen-containing carbon oxide quantum dots, 0.1 to 1000 parts by mass of a phosphorus compound, and 0.1 to 100 parts by mass of a potassium salt.

[0038] The fertilizer composition of this embodiment contains nitrogen, phosphorus, and potassium, also known as the three elements of fertilizer, and is therefore useful for cultivating cultivated plants. Furthermore, since nitrogen is a component of carbon quantum dots, it has nanoscale dimensions even when not decomposed by microorganisms. Therefore, it can easily pass through plant cells and be absorbed. Furthermore, since it is not a salt like ammonium sulfate, it does not significantly increase the osmotic pressure of liquid fertilizers. Therefore, it can be applied to cultivated plants as a high-concentration fertilizer and can be taken up not only through the roots but also through the leaves. Furthermore, since it exhibits the optical properties of carbon quantum dots, after being taken up by plants, it will react to external light and emit fluorescence. Utilizing this property, the real-time status of cultivated plants can be determined by the fluorescence state, and the cultivation environment can be adjusted accordingly. As described above, the fertilizer composition of this embodiment can significantly contribute to improving agricultural efficiency. The main components of the fertilizer composition are described below.

[0039] <Nitrogen-Containing Carbon Oxide Quantum Dots>

[0040] Nitrogen-containing carbon oxide quantum dots are carbon quantum dots containing nitrogen and oxygen atoms. They typically have a diameter of approximately 0.5 nm to 100 nm and exhibit luminescence properties derived from π bonds. Nitrogen-containing carbon oxide quantum dots can be purchased from companies such as Fuji Pigments Co., Ltd. and GS Alliance Co., Ltd. They can also be produced using top-down methods based on oxidation and nitridation of carbon quantum dots and graphite, or bottom-up methods involving synthesis from low-molecular-weight compounds such as nitrogen compounds and oxygen-containing organic compounds through hydrothermal reactions.

[0041] [Carbon Quantum Dots]

[0042] Here we will explain carbon quantum dots, which are a kind of hexagonal lattice structure (SP 2 Nanoscale materials (primarily composed of carbon with carbon atoms linked to carbon atoms). Examples include, but are not limited to, graphene (in the narrow sense), carbon nanotubes (CNTs), fullerenes, carbon nanohorns, and carbon nanofibers. It should be noted that these carbon materials all have a graphene structure and are therefore included in the broader definition of graphene. Hereinafter, unless otherwise specified, "graphene" is used in a broad sense that also includes CNTs, fullerenes, and the like.

[0043] Carbon quantum dots can also be purchased from Sigma-Aldrich, Fuji Pigments Co., Ltd., GS Alliance Co., Ltd., Funakoshi Co., Ltd., Kishida Chemical Co., Ltd., etc. In addition, they can also be produced by the following methods: chemical vapor deposition (CVD), a method of chemically treating a carbon target by laser ablation, a method of chemically treating coal, carbon fiber, graphite oxide, etc., and a bottom-up method as described above using a low molecular weight compound.

[0044] Top-down approach

[0045] Nitrogen-containing oxidized carbon quantum dots can be manufactured, for example, by the above-mentioned top-down method of oxidizing and nitriding carbon quantum dots. As a starting material, cheaper graphite can also be used. For example, as described in Patent Document 3, graphene oxide can be prepared first by oxidizing graphite to introduce oxygen-containing functional groups such as carboxyl, hydroxyl, epoxy, and carbonyl groups, and then exfoliating the layers. Oxidation can be performed using oxidants such as concentrated nitric acid, sodium chlorate / fuming nitric acid, potassium permanganate / concentrated sulfuric acid, potassium dichromate / concentrated sulfuric acid, ozone, and hydrogen peroxide. It should be noted that oxidized carbon quantum dots are carbon quantum dots having oxygen-containing functional groups such as these carboxyl groups. In addition to the above, as described in Patent Document 4, graphene oxide can also be manufactured by electrochemically oxidizing and cutting carbon fibers.

[0046] Next, the graphene oxide obtained as described above is reacted with a nitrogen compound to produce nitrogen-containing carbon oxide quantum dots. For example, as described in Patent Document 3, graphene oxide is dispersed in an aqueous solution containing a nitrogen compound and treated under pressure at a temperature of about 100°C to 200°C. Examples of nitrogen compounds include, but are not limited to, urea, ammonia, thiourea, hydrazine, nitrate esters, sodium nitrate, sodium nitrite, hydroxylamine, pyridine N-oxide, N-hydroxyalkylene imine, sodium azide, sodium amide, carboxylic acid azide; alkylamines such as methylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine, tert-butylamine, n-pentylamine, and n-hexylamine, and their halides; and diamines such as ethylenediamine and propylenediamine.

[0047] Bottom-up approach

[0048] Nitrogen-containing carbon oxide quantum dots can also be produced by a bottom-up method such as the above-mentioned hydrothermal synthesis. The bottom-up method is a production method in which molecules are assembled using low-molecular compounds as raw materials. It has the advantages of being able to synthesize the target compound in high yield, good reproducibility and simplicity. The raw materials, methods and conditions used in the production of nitrogen-containing carbon oxide quantum dots are not particularly limited. For example, the methods described in Patent Documents 1 and 2 can be used. These patent documents describe a production method in which an oxygen-containing organic compound and a nitrogen compound are heated to high temperature and high pressure to react.

[0049] (oxygenated organic compounds)

[0050] There are no particular limitations on the oxygen-containing organic compound used as a raw material; any compound containing an oxygen atom can be used. Preferred examples include the various organic acids and sugars described in Patent Documents 1 and 2. Most of these organic compounds are biosafe and suitable as raw materials for fertilizer composition components. Furthermore, nitrogen-containing carbon oxide quantum dots can be efficiently produced through hydrothermal synthesis. Multiple oxygen-containing organic compounds can also be used in combination.

[0051] The type of organic acid is also not particularly limited. Examples include aliphatic hydroxycarboxylic acids such as glycolic acid, lactic acid, tartronic acid, glyceric acid, hydroxybutyric acid, 2-hydroxybutyric acid, 3-hydroxybutyric acid, γ-hydroxybutyric acid, malic acid, tartaric acid, citramalic acid, citric acid, isocitric acid, leucic acid, mevalonic acid, pantoic acid, ricinoleic acid, ricinoleic acid, cerebronic acid, quinic acid, glyceric acid, gluconic acid, glucuronic acid, and shikimic acid; salicylic acid, creosote acid, and styryl acid; Aromatic hydroxycarboxylic acids such as hydroxybenzoic acid, vanillic acid, syringic acid, 2,3-dihydroxybenzoic acid, 2,4-dihydroxybenzoic acid, protocatechuic acid, 2,5-dihydroxybenzoic acid, 2,4-dihydroxy-6-methylbenzoic acid, tannic acid, mandelic acid, benzilic acid, 2-(2-hydroxyphenyl)propionic acid, cinnamic acid, 3-(2-hydroxyphenyl)propionic acid, 3-(4-hydroxyphenyl)propionic acid, coumaric acid, 2,4-dihydroxycinnamic acid, caffeic acid, ferulic acid, and sinapic acid; polycarboxylic acids such as oxalic acid, malonic acid, succinic acid, fumaric acid, and itaconic acid; and ascorbic acid, etc., but not limited thereto. Among the above, nitrogen-containing carbon oxide quantum dots can be particularly easily produced from hydroxypolycarboxylic acids such as citric acid, malic acid, and tartaric acid.

[0052] The sugars are not particularly limited, and examples thereof include monosaccharides such as aldoses such as glyceraldehyde, erythrose, threose, ribose, lyxose, xylose, arabinose, allose, talose, gulose, glucose, altrose, mannose, galactose, and idose; ketoses such as dihydroxyacetone, erythrulose, xylulose, ribulose, psicose, fructose, sorbose, and tagatose; and disaccharides such as sucrose, disucrulose, lactose, maltose, trehalose, and cellobiose, but are not limited thereto.

[0053] (Nitrogen compounds)

[0054] The type of nitrogen compound is also not particularly limited. Nitrogen compounds such as urea, ammonia, and sodium nitrate, which are raw materials for the top-down method described above, can be used. Multiple nitrogen compounds can also be used in combination. Organic compounds having amino groups are preferred. For example, by using organic amine compounds and / or amino acids, nitrogen-containing carbon oxide quantum dots can be produced that have a significant effect on plant growth or exhibit strong fluorescence in plants.

[0055] The type of organic compound having an amino group is not particularly limited. Examples include, but are not limited to, aliphatic monoamines such as hexylamine and N,N-dimethylethylenediamine; aliphatic diamines such as ethylenediamine and hexamethylenediamine; aromatic amines such as phenylenediamine; and amino-containing polyethylene glycols and amino-containing polypropylene glycols.

[0056] Here, considering the possibility that the raw materials may remain in the nitrogenous carbon oxide quantum dots produced, it is preferred to use amino acids as nitrogen compounds. In the case of amino acids, even if they remain in the product without reaction, the possibility of harming cultivated plants and the surrounding environment is also very low. The types of amino acids are not particularly limited, such as glycine, alanine, valine, phenylalanine, threonine, lysine, asparagine, arginine, tryptophan, serine, glutamic acid, aspartic acid, ornithine, thyroxine (thyroxine), cysteine, cystine, leucine, isoleucine, proline, tyrosine, glutamine, histidine, methionine, threonine, etc.

[0057] (Hydrothermal reaction)

[0058] Nitrogen-containing carbon oxide quantum dots can be produced by reacting the above-described oxygen-containing organic compound with a nitrogen compound. The reaction can also be carried out at normal pressure, and the solvent used is not particularly limited. However, a hydrothermal synthesis method, in which the reaction is carried out in water under high temperature and high pressure conditions, is preferred. This hydrothermal reaction allows for the simple synthesis of nitrogen-containing carbon oxide quantum dots with higher yields and good reproducibility.

[0059] The conditions for the hydrothermal reaction are not particularly limited. For example, it is preferred to use an autoclave at a temperature of 100°C to 500°C, particularly 120°C to 300°C, and particularly 150°C to 200°C, and a pressure of approximately 200 kPa to 2 MPa, particularly 500 kPa to 1 MPa, for a period of 1 minute to 72 hours, particularly 1 hour to 12 hours. Alternatively, an acid catalyst may be added, as described in Patent Document 1. Examples of acid catalysts include, but are not limited to, inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid; organic acids such as sulfonic acids represented by p-toluenesulfonic acid; and solid acid catalysts such as cationic ion exchange resins and ion exchange membranes. As solid acid catalysts, for example, commercially available products listed in Patent Document 1 may be used. Alternatively, phosphoric acid may be used as the catalyst, omitting the mixing step of the phosphorus compound described below.

[0060] [Morphology of Nitrogen-Containing Carbon Oxide Quantum Dots]

[0061] As described above, the nitrogen-containing carbon oxide quantum dots are not particularly limited in type, as long as they are carbon nanomaterials containing nitrogen and oxygen atoms. For example, they may be graphene, carbon nanotubes (CNTs), fullerenes, carbon nanohorns, carbon nanofibers, etc., containing nitrogen and oxygen atoms (in the narrow sense). The chemical forms of the nitrogen and oxygen atoms are also not particularly limited.

[0062] From the perspective of promoting the growth of cultivated plants, nitrogen-containing carbon oxide quantum dots are preferably graphene-type quantum dots having nitrogen-containing functional groups and carbonyl groups. Here, "graphene-type" refers to the above-mentioned broad graphene, which includes CNTs, carbon nanofibers, etc. in addition to (narrowly defined) graphene. In addition, "carbonyl" also has a broad meaning, including not only carbonyl groups in ketones and aldehydes, but also all functional groups with a C=O structure such as carboxyl groups, ester groups, anhydride groups, and amide groups in derivatives such as carboxylic acids and their salts. Nitrogen-containing carbon oxide quantum dots are more preferably graphene and / or CNTs (narrowly defined) having nitrogen-containing functional groups and carbonyl groups, in particular graphene in a narrow sense.

[0063] (Particle size)

[0064] The average particle size (diameter) of the nitrogen-containing carbon oxide quantum dots is not particularly limited, and for example, it can be the average size of conventional carbon quantum dots, that is, about 0.5 nm to 100 nm. It should be noted that when it is expressed as "diameter", it means the diameter from one end to the other end of the nitrogen-containing carbon oxide quantum dot particle, rather than the diameter from the center of the particle to one end. That is, the nitrogen-containing carbon oxide quantum dots may not be spherical, for example, they may be disc-shaped, spheroidal, or even irregular polygonal shapes. From the viewpoint of being easily ingested into cultivated plants, the average particle size of the nitrogen-containing carbon oxide quantum dots is preferably about 1.0 nm to 50 nm, preferably about 1.5 nm to 20 nm, and particularly preferably about 2.0 nm to 10 nm.

[0065] (Forms of nitrogen and oxygen)

[0066] There is no particular restriction on the form of nitrogen atoms and oxygen atoms in the nitrogen-containing carbon oxide quantum dots. From the viewpoint of promoting the growth of cultivated plants, it is preferred that at least a portion of the nitrogen atoms and oxygen atoms are contained in the form of nitrogen-containing functional groups and carbonyl groups, respectively, as described above. The nitrogen-containing functional group is not particularly limited, and may be, for example, an amino group, an imino group, an amide group, etc., and may also be incorporated into the graphene structure. As described above, the carbonyl group may also be in any form such as a ketone group, an aldehyde group, a carboxyl group, an ester group, an acid anhydride group, an amide group, etc. In particular, when in the form of an amino group, an imino group, a carboxyl group and / or an amide group, the nitrogen-containing carbon oxide quantum dots have the advantage of having a better affinity for water and being easily absorbed by cultivated plants.

[0067] (Nitrogen and oxygen content)

[0068] The nitrogen and oxygen content of the nitrogen-containing carbon oxide quantum dots is not particularly limited. For example, a structure similar to melamine can be formed with a nitrogen content exceeding 60 parts by mass per 100 parts by mass of the nitrogen-containing carbon oxide quantum dots. A higher nitrogen content increases the nitrogen fertilizer's effectiveness.

[0069] If the characteristics of carbon quantum dots and the ease of synthesis are taken into account, the content of nitrogen atoms in 100 parts by mass of nitrogen-containing oxidized carbon quantum dots is preferably 0.1 to 60 parts by mass, wherein preferably 0.5 to 40 parts by mass, and particularly preferably about 2 to 25 parts by mass. Similarly, the content of oxygen atoms in 100 parts by mass of nitrogen-containing oxidized carbon quantum dots is also preferably 0.1 to 60 parts by mass, wherein preferably 0.3 to 30 parts by mass, and particularly preferably about 0.5 to 15 parts by mass. It should be noted that, from the viewpoint of showing the optical characteristics of carbon quantum dots, the total amount of nitrogen atoms and oxygen atoms relative to 100 parts by mass of nitrogen-containing oxidized carbon quantum dots is preferably about 1 to 60 parts by mass, wherein preferably about 2 to 40 parts by mass, and particularly preferably about 10 to 30 parts by mass.

[0070] The nitrogen and oxygen atom contents described above can be adjusted by varying the raw material ratios and reaction conditions during the production of nitrogen-containing carbon oxide quantum dots. For example, as described in Patent Documents 1 and 2, nitrogen-containing carbon oxide quantum dots having desired nitrogen and oxygen atom contents can be produced by varying the ratio of oxygen-containing organic compound to nitrogen compound within a range of approximately 10:1 to 1:10, more preferably 5:1 to 1:5, and particularly 3:1 to 1:3.

[0071] <Phosphorus compounds>

[0072] The fertilizer composition of this embodiment contains 0.1 to 1000 parts by mass of a phosphorus compound per 100 parts by mass of nitrogen-containing carbon oxide quantum dots. As mentioned above, phosphorus is one of the three essential elements of fertilizer, along with nitrogen and potassium. The inclusion of a phosphorus compound significantly improves plant growth.

[0073] The form of the phosphorus compound is not particularly limited. Examples include, but are not limited to, phosphoric acid, phosphorous acid, hypophosphorous acid, hypophosphorous acid, pyrophosphoric acid, trimetaphosphoric acid, tetrametaphosphoric acid, pyrophosphorous acid, polymetaphosphorous acid, monosuperphosphoric acid, and disuperphosphoric acid, as well as their metal salts, ammonium salts, esters, and compounds with nitrogen. A variety of phosphorus compounds may also be used. A phosphoric acid derivative can particularly enhance the growth-promoting effect on cultivated plants. Orthophosphoric acid, its salts, and its derivatives are particularly preferred.

[0074] Furthermore, these phosphorus compounds can partially or completely react with functional groups in nitrogen-containing carbon oxide quantum dots, or can be doped or supported on the nitrogen-containing carbon oxide quantum dots. Doping with phosphorus compounds can also alter the optical properties of nitrogen-containing carbon oxide quantum dots. For example, nitrogen-containing carbon oxide quantum dots that typically emit blue to bluish-violet fluorescence upon irradiation with ultraviolet light can be modified to emit, for example, red fluorescence upon irradiation with ultraviolet light or light of a longer wavelength.

[0075] The amount of the phosphorus compound in the fertilizer composition is preferably 1 to 500 parts by mass, more preferably 10 to 200 parts by mass, further preferably 20 to 150 parts by mass, and particularly preferably 30 to 100 parts by mass, per 100 parts by mass of the nitrogen-containing carbon oxide quantum dots. Furthermore, the molar ratio of carbon atoms to phosphorus atoms in the nitrogen-containing carbon oxide quantum dots is preferably, for example, 1:10 to 100:1, preferably 1:2 to 50:1, further preferably 1:1 to 20:1, and particularly preferably 3:1 to 10:1.

[0076] <Potassium Salt>

[0077] The fertilizer composition of this embodiment further contains 0.1 to 100 parts by mass of potassium salt relative to 100 parts by mass of nitrogen-containing carbon oxide quantum dots. Potassium salt can also significantly improve plant growth effects.

[0078] The type of potassium salt is not particularly limited, and various known potassium salts can be used. Examples include, but are not limited to, inorganic salts such as potassium chloride, potassium nitrate, potassium sulfate, potassium hydrogen sulfate, potassium carbonate, potassium hydrogen carbonate, and potassium sodium carbonate; and organic salts such as potassium acetate, potassium propionate, potassium oxalate, potassium tartrate, long-chain potassium carboxylates such as potassium stearate, potassium benzoate, potassium salicylate, and potassium sulfonate. Potassium phosphate and potassium hydrogen phosphate can also be combined with the above-mentioned phosphorus compounds. In addition, salts can be formed with the carboxyl group or phosphoric acid in the nitrogen-containing carbon oxide quantum dots. Although it depends on the type of nitrogen-containing carbon oxide quantum dots and phosphorus compounds used in combination, weak acid salts such as potassium carbonate and potassium carboxylate are preferred from the perspective of adjusting the pH of the fertilizer composition to approximately 6 to 7.

[0079] The amount of potassium salt in the fertilizer composition is preferably 1 to 80 parts by mass, more preferably 2 to 50 parts by mass, and particularly preferably 5 to 30 parts by mass, per 100 parts by mass of the nitrogen-containing carbon oxide quantum dots. Furthermore, the molar ratio of carbon atoms to potassium atoms in the nitrogen-containing carbon oxide quantum dots is preferably, for example, 1:1 to 100:1, preferably 10:1 to 50:1, and particularly preferably 20:1 to 30:1.

[0080] <Preparation of Fertilizer Composition>

[0081] The fertilizer composition of this embodiment can be prepared by mixing the nitrogen-containing carbon oxide quantum dots, phosphorus compounds and potassium salts as described above in specified amounts. There is no particular limitation on the mixing method. For example, the components can be dry-blended or dispersed or dissolved in water before mixing. In particular, in the case of a hydrothermal synthesis method, the nitrogen-containing carbon oxide quantum dots can be obtained in the form of an aqueous dispersion. Therefore, it is sufficient to mix the phosphorus compound, potassium salt or its aqueous solution therein. As described above, by using phosphoric acid as a catalyst during hydrothermal synthesis, it is also possible to introduce a phosphorus compound into the fertilizer composition. Similarly, potassium salt can be pre-blended from the stage of hydrothermal synthesis. It should be noted that potassium salt, like phosphorus compound, can be doped or supported on nitrogen-containing carbon oxide quantum dots.

[0082] The present invention is not limited by a specific theory, but it is believed that the reason why this embodiment works effectively is as follows: while being able to contain the three elements of fertilizer, such as nitrogen, phosphorus, and potassium, in a good balance, the nitrogen component is contained in the nano-sized carbon material such as nitrogen-containing carbon oxide quantum dots. Because it is nano-sized, it is easy to pass through the cells of the plant and be taken up. In addition, because it does not significantly increase the osmotic pressure like ammonium sulfate, it is also easy to absorb from the roots. Moreover, it is in the form of a dispersion rather than a solution, so it is also possible to suppress the waste of fertilizer attached to the culture medium due to loss due to rainfall, etc. In particular, when phosphorus compounds and potassium salts are doped or supported in nitrogen-containing carbon oxide quantum dots, these components are also easily taken up into the plant together with the nitrogen component. It can be absorbed not only from the roots of the cultivated plants, but also from the leaves. Therefore, it is also possible to reduce the waste and environmental pollution caused by the loss of fertilizer.

[0083] <Other ingredients>

[0084] In addition to the aforementioned ingredients, the fertilizer composition of this embodiment may also contain common natural and chemical fertilizers, such as ammonium sulfate, ammonium nitrate, ammonium phosphate, superphosphate lime, and molten phosphate fertilizers; mineral components such as calcium, magnesium, iron, manganese, copper, zinc, nickel, and boron; pesticides other than fertilizers, such as herbicides, insecticides, fungicides, antimicrobials, rodenticides, and pH adjusters; and additional components such as recombinant genes. These additional components may also be supported on nitrogen-containing carbon oxide quantum dots.

[0085] The fertilizer composition of this embodiment can also be a liquid dispersed or dissolved in water, glycerin, or the like. Aqueous fertilizers primarily containing water as the solvent are particularly preferred. The present invention also includes aqueous fertilizers containing the above-mentioned fertilizer composition at a solids concentration of 0.001% to 90% by mass. The solids concentration in the aqueous fertilizer is preferably 0.01% to 50% by mass, particularly preferably 0.1% to 30% by mass. As described above, the fertilizer composition of this embodiment can also be absorbed by plants through their leaves, but in this case, the solids concentration is preferably slightly reduced to 0.01% to 20% by mass, particularly preferably 0.1% to 10% by mass.

[0086] <<Cultivation Method>>

[0087] When using the fertilizer composition of the above embodiment, as described above, it is possible to improve agricultural efficiency and reduce environmental pollution. The present invention also includes a cultivation method comprising the step of supplying the above fertilizer composition to a plant and / or a culture medium. The fertilizer composition of the above embodiment can be supplied to a culture medium such as soil in the form of a solid or powdered fertilizer. Alternatively, it can be directly supplied to a culture medium, a nutrient solution for hydroponics, or even a plant in the form of an aqueous fertilizer. For example, the aqueous fertilizer can be applied to the periphery of the leaves of the cultivated plant so that almost all of the nutrients in the fertilizer are absorbed by the plant.

[0088] As described above, the fertilizer composition according to the above embodiment is easily absorbed by cultivated plants, and thus the nitrogen-containing carbon oxide quantum dots, one of the main components, are easily incorporated into the plants. Consequently, when plants cultivated using the above embodiment are irradiated with light from the outside, they emit fluorescence caused by the quantum dots. For example, irradiation with ultraviolet light sometimes produces blue to bluish-violet fluorescence. Therefore, fertilizer absorption can be assessed by irradiating cultivated plants with light of a specific wavelength and observing the resulting fluorescence.

[0089] Here, the wavelength of the irradiation light with which the quantum dots react and the wavelength of the fluorescence emitted depend on the type of nitrogen-containing carbon oxide quantum dots and the condition of the plant that ingests them. For example, nitrogen-containing carbon oxide quantum dots doped with a large amount of phosphorus compounds sometimes emit red fluorescence when irradiated with ultraviolet light or light of a longer wavelength. In addition, if the cultivated plants are stressed due to malnutrition, abnormal temperature and humidity conditions, etc., hydrogen peroxide, nitric oxide, etc. will be produced in the plant body, which sometimes combines with nitrogen-containing carbon oxide quantum dots to weaken the fluorescence or change the wavelength of the fluorescence (non-patent document 1). This phenomenon can also be applied to increase the harvest and improve the efficiency of agriculture. For example, by monitoring the state of the cultivated plants each time by the fluorescence state and controlling the cultivation environment accordingly, the cultivated plants can also be effectively cultivated.

[0090] The present invention also includes a cultivation method comprising: supplying the aforementioned fertilizer composition to plants and / or a culture medium; and irradiating the plants with light having a wavelength of 200 to 900 nm, particularly 250 to 500 nm, and controlling the cultivation environment based on the luminescence of the plants at that time. The wavelength of the irradiated light can be selected based on the type of nitrogen-containing carbon oxide quantum dots used as components. For example, nitrogen-containing carbon oxide quantum dots that are rarely doped with phosphorus compounds typically react with ultraviolet light to emit fluorescence. Therefore, irradiation with light having a wavelength of 280 to 460 nm, particularly 320 to 400 nm, can be sufficient. As an example, a general-purpose commercially available ultraviolet lamp emitting light at a wavelength of approximately 365 nm can be used. Furthermore, for nitrogen-containing carbon oxide quantum dots doped with a large amount of phosphorus, for example, approximately 0.1 to 30.0 mass%, irradiation with light having a wavelength of 320 to 480 nm, particularly 340 to 440 nm, can be sufficient.

[0091] When using the fertilizer composition of the above embodiment to cultivate plants, genes for recombination, etc., can also be loaded onto nitrogen-containing carbon oxide quantum dots and delivered into the plants. In this way, the fertilizer composition and cultivation method of the present invention can increase crop yields and improve agricultural efficiency by improving nutrient utilization in the fertilizer, adjusting the cultivation environment based on fluorescence, and modifying the cultivated plants. Furthermore, it can suppress environmental pollution caused by the runoff and loss of unused fertilizer.

[0092] Example

[0093] The present invention will be described in more detail below based on examples. It should be noted that these examples are provided to facilitate understanding of the concept and scope of the present invention disclosed in this specification or described in the appended claims. Their description is intended only to illustrate specific schemes and implementation methods, and the present invention is not limited in any way by these examples.

[0094] [Example 1]

[0095] A fertilizer composition was prepared using GS QD Graphene-Fin Water (an aqueous dispersion of nitrogen-containing graphene oxide obtained by hydrothermal synthesis using a phosphoric acid catalyst, with a C:N:P2O5 mass ratio of approximately 46:14:40 and a C:N:P molar ratio of approximately 72:18:10, with a solids content of approximately 20%) from GS Alliance Co., Ltd. as nitrogen-containing carbon oxide quantum dots. 1.00 g of GS QD Graphene-F in Water was diluted to 100 ml, and 12 mg of K2CO3 was added to the solution, dissolved, and stirred thoroughly to produce an aqueous fertilizer (the molar ratio of carbon atoms:phosphorus atoms:potassium atoms in the nitrogen-containing carbon oxide quantum dots was approximately 100:14:4).

[0096] The paper was immersed in the obtained aqueous fertilizer and placed on a petri dish. Mizuna was sown on it and left at room temperature. After 48 hours, it was observed and photographed. The photographic results are shown in Figure 1 It can be seen that the mizuna has germinated and grown smoothly.

[0097] [Comparative Example 1]

[0098] Using tap water instead of water-based fertilizer, the same operation as in Example 1 was carried out. After 48 hours of sowing, the water spinach sprouted but had almost no growth ( Figure 1 ).

[0099] [Comparative Example 2]

[0100] A commercially available fertilizer containing nitrogen, phosphorus, and potassium (compound fertilizer for home gardening manufactured by Kiyo Pyrethrum Co., Ltd.) was used as a water-based fertilizer and diluted to 1 / 500. The same operation as in Example 1 was carried out. After 48 hours of sowing, the mizuna sprouted and grew smoothly ( Figure 1 ).

[0101] It should be noted that Example 1 and Comparative Examples 1 and 2 were implemented simultaneously under the same environment, and photos were taken ( Figure 1 ). Figure 1 It is shown that the fertilizer composition of the present invention promotes the growth of cultivated plants, and its effect is better than that of commercially available general-purpose fertilizers.

[0102] [Example 2]

[0103] As nitrogen-containing carbon oxide quantum dots, GS QD Graphene in Water manufactured by GS Alliance Co., Ltd. (nitrogen-containing graphene oxide obtained by hydrothermal synthesis based on a phosphoric acid catalyst, C:N:P2O5 mass ratio ≈43:16:41, C:N:P molar ratio ≈68:21:11, an aqueous dispersion with a solid content of approximately 20%) was used, and an aqueous fertilizer (fertilizer composition) was prepared in the same manner as in Example 1 (the molar ratio of carbon atoms:phosphorus atoms:potassium atoms in the nitrogen-containing carbon oxide quantum dots was ≈100:16:4).

[0104] (Cultivation Test)

[0105] When the same operation as in Example 1 was carried out using the obtained aqueous fertilizer, it was observed that mizuna germinated and grew smoothly.

[0106] (Fluorescence test)

[0107] One of the mizuna plants was collected 48 hours after sowing, placed on a piece of paper, and irradiated with a 365 nm wavelength UV lamp from above. Figure 2 (right side) As can be seen from this figure, the mizuna grown using the fertilizer composition of the present invention reacts to ultraviolet light and produces fluorescence. It should be noted that the emitted fluorescence is blue light.

[0108] Figure 2 Figure 2 shows the fluorescence test results for mizuna samples obtained in Example 2 and Comparative Example 2 (left). These examples and comparative examples were conducted simultaneously under the same conditions as Example 1. The sample from Comparative Example 2 (left), placed side by side and irradiated with ultraviolet light under the same conditions, did not fluoresce, indicating that the fluorescence in Example 2 originated from nitrogen-containing carbon oxide quantum dots incorporated into the mizuna.

[0109] The experimental results above demonstrate that the fertilizer composition of the present invention can significantly promote the growth of cultivated plants. Furthermore, it was shown that nitrogen-containing carbon oxide quantum dots can be incorporated into cultivated plants, and that fluorescence from the quantum dots can be visually observed. This demonstrates that the fluorescence of plants cultivated using quantum dots can be used to assess the degree of fertilizer uptake and the condition of the cultivated plants, allowing for real-time adjustments to cultivation conditions. This highly efficient cultivation method is feasible. This method can promote plant growth, increase harvest yield, and reduce environmental pollution caused by fertilizer loss, demonstrating significant benefits.

Claims

1. A fertilizer composition, wherein contain: 100 parts by mass of nitrogen-containing carbon oxide quantum dots, 0.1 to 1000 parts by mass of a phosphorus compound, and 0.1 to 100 parts by mass of potassium salt.

2. The fertilizer composition according to claim 1, wherein The nitrogen-containing carbon oxide quantum dots are graphene-based quantum dots having nitrogen-containing functional groups and carbonyl groups.

3. The fertilizer composition according to claim 1 or 2, wherein In 100 parts by mass of the nitrogen-containing carbon oxide quantum dots, the content of nitrogen atoms is 0.1 parts by mass to 60 parts by mass.

4. The fertilizer composition according to claim 1 or 2, wherein In 100 parts by mass of the nitrogen-containing carbon oxide quantum dots, the content of oxygen atoms is 0.1 parts by mass to 60 parts by mass.

5. The fertilizer composition according to claim 1 or 2, wherein The phosphorus compound is a derivative of phosphoric acid.

6. An aqueous fertilizer comprising the fertilizer composition according to claim 1 or 2 at a solid content concentration of 0.001% by mass to 90% by mass.

7. A cultivation method, wherein: Provides a supply of The process of preparing the fertilizer composition according to claim 1 or 2.

8. A cultivation method, wherein: have: A step of supplying the fertilizer composition according to claim 1 or 2 to plants and / or culture medium, and The step of irradiating the plant with light having a wavelength of 200 nm to 900 nm and controlling the cultivation environment according to the light emission state of the plant at that time.

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