Plant growth improving agent, plant cultivation kit, biochar, and bacterial flora improving agent

Abstract

The present disclosure relates to a plant growth improving agent that contains silica particles (100), wherein the central particle diameter of particles (101) having a particle diameter of at least 100 nm, among the silica particles, is 120-800 nm in a particle size distribution of the particles (101) having a particle diameter of at least 100 nm. The present disclosure provides a plant growth improving agent capable of also improving the growth of plants other than Poaceae. The present disclosure further relates to: biochar that can absorb carbon dioxide (CO2) and improve plant growth; a plant cultivation kit that can favorably grow a plant even when moisture is not sufficiently supplied during the growth period of the plant; and a bacterial flora improving agent that can improve bacterial flora without directly adding bacteria.

Description

Plant growth improvers, plant cultivation kits, biochar and bacterial flora improvers

[0001] The present disclosure relates to a plant growth improver, a plant cultivation kit, biochar, and a microbial flora improver.

[0002] Patent Document 1 discloses a silicic acid absorption promoter that promotes the absorption of silicic acid by grass plants.

[0003] Patent Document 2 discloses a plant growth promoter containing an extract of a fungus of the genus Pectinella.

[0004] Patent Document 3 discloses a composition for improving plant productivity in soil, which contains a bacterium belonging to the order Rhizobiales.

[0005] JP 2017-214368 A JP 2023-138203 A International Publication No. 2021 / 066115

[0006] The silicic acid absorption promoter described in Patent Document 1 can easily improve the growth and quality of grasses that absorb a large amount of silicic acid, but the effect is less pronounced in plants that have difficulty absorbing silicic acid.

[0007] The growth-promoting agent described in Patent Document 2 requires the supply of water during the plant's growing period, in the same manner as when no growth-promoting agent is used. Even if a plant is grown using the growth-promoting agent described in Patent Document 2, if sufficient water is not supplied during the plant's growing period, the effect of promoting plant growth will not be exerted.

[0008] The composition described in Patent Document 3 adds bacteria directly to soil, which may impair the diversity of bacterial flora in the soil.

[0009] An object of the present disclosure is to provide a plant growth improver that can also improve the growth of plants other than grasses.

[0010] Another object of the present disclosure is to provide a method for the production of carbon dioxide (CO ２ The present invention aims to provide biochar that can absorb carbon dioxide and improve plant growth.

[0011] Another object of the present disclosure is to provide a plant cultivation kit that allows plants to grow well even when sufficient water is not supplied to the plants during their growing period.

[0012] Still another object of the present disclosure is to provide a bacterial flora improver that can improve bacterial flora without directly adding bacteria.

[0013] A plant growth improver according to a first embodiment of the present disclosure includes silica particles, the median particle size of which is 120 nm or more and 800 nm or less in the particle size distribution of the silica particles having a particle size of 100 nm or more.

[0014] The biochar according to the second embodiment of the present disclosure is a biochar supporting silica particles, in which the median particle size of the silica particles having a particle size of 100 nm or more is 120 nm or more and 800 nm or less in the particle size distribution of the particles having a particle size of 100 nm or more.

[0015] A plant cultivation kit according to a third embodiment of the present disclosure includes a container, a cover for covering the container, and a culture medium. The culture medium includes silica particles and soil. The silica particles having a particle size of 100 nm or more have a median particle size of 120 nm to 800 nm in the particle size distribution of the particles having a particle size of 100 nm or more.

[0016] A bacterial flora improver according to a fourth embodiment of the present disclosure is a bacterial flora improver containing silica particles, wherein the median particle size of the silica particles having a particle size of 100 nm or more is 120 nm or more and 800 nm or less in the particle size distribution of the particles having a particle size of 100 nm or more.

[0017] According to a first embodiment of the present disclosure, a plant growth improver capable of improving the growth of plants other than those of the Gramineae family can be provided. ２It is possible to provide biochar that can absorb water and improve plant growth. According to a third embodiment of the present disclosure, it is possible to provide a plant cultivation kit that allows plants to grow well even when water is not supplied sufficiently during the plant's growth period. According to a fourth embodiment of the present disclosure, it is possible to provide a bacterial flora improver that can improve bacterial flora without directly adding bacteria.

[0018] FIG. 1 is a schematic cross-sectional view illustrating an example of silica particles. FIG. 2 is a schematic flowchart illustrating an example of a method for producing silica particles. FIG. 3 is a scanning electron microscope image of silica particles. FIG. 4 is a scanning electron microscope image of silica particles. FIG. 5 is a composite map (Si and N) of silica particles obtained by energy dispersive X-ray spectroscopy. FIG. 6 is a scanning electron microscope image of silica particles immersed in water for one year. FIG. 7 is a diagram illustrating a method for applying silica particles to soil in an example. FIG. 8 is a diagram showing holes for placing seeds in the culture medium in an example. FIG. 9 is a diagram comparing the growth results of harvested spinach. FIG. 10 is a diagram comparing the growth conditions of komatsuna. FIG. 11 shows the results of analyzing the silicon content in the edible parts and roots of harvested komatsuna and the amount of available silicic acid in the culture medium. FIG. 12 is a scanning electron microscope image of the silica particles of Example 3, the silicate-based vitality agent of Comparative Example 3, and the nanoparticles of Comparative Example 4. FIG. 13 is a diagram comparing germination rates. FIG. 14 is a diagram showing the growth results of cherry tomatoes in Example 6. FIG. 15 is a diagram showing the growth results of cherry tomatoes in Comparative Example 7. FIG. 16 is a diagram comparing the sugar content of cherry tomatoes. FIG. 17 is a diagram comparing the growth conditions of aquatic plants. FIG. 18 is a diagram comparing the growth results of aquatic plants. FIG. 19 is a diagram comparing the degree to which aquatic plants are removed after water replacement. FIG. 20 is a schematic cross-sectional view illustrating a method for growing Japanese yam. FIG. 21 is a diagram showing the appearance of a biomass material and biochar. FIG. 22 is a diagram showing a scanning electron microscope image of biochar. FIG. 23 is a diagram showing a scanning electron microscope image of biochar. FIG. 24 is a diagram showing the growth results of spinach grown using a plant cultivation kit. FIG. 25 is a diagram showing the growth results of spinach grown using a plant cultivation kit. FIG. 26 is a diagram showing the growth results of spinach grown without using a plant cultivation kit. FIG. 27 is a diagram comparing the yield of komatsuna (Japanese mustard spinach). Fig. 28 is a diagram comparing spinach harvest yields. Fig. 29 is a diagram showing temperature changes in the culture medium during the growth period. Fig. 30 is a diagram showing changes in moisture content in the culture medium during the growth period. Fig. 31 is a bar chart showing the abundance rate of each type of bacteria.Figure 32 is a bar chart showing the abundance rate of bacteria A rearranged from left to right in ascending order. Figure 33 is a diagram showing a rarefaction curve of Observed_features. Figure 34 is a diagram showing a box plot of Observed_features. Figure 35 is a diagram showing the results of Jaccard principal coordinate analysis. Figure 36 is a diagram showing the results of Unweighted_Unifrac principal coordinate analysis. Figure 37 is a diagram showing the results of Weighted_Unifrac principal coordinate analysis.

[0019] <First embodiment> [Growth improver] A plant growth improver according to a first embodiment is a plant growth improver containing silica particles. The silica particles having a particle size of 100 nm or more (hereinafter also referred to as first particles) have a median particle size of 120 nm or more and 800 nm or less in the particle size distribution of the first particles.

[0020] The content of silica particles in the growth improver may be, for example, 99% by mass or more. The growth improver may consist solely of silica particles. The content of silica particles in the growth improver may be less than 99% by mass, as long as the effects of the present disclosure are obtained.

[0021] The silica particles are aggregates of multiple silica particles. The silica particles may be substantially spherical particles. The silica particles include first particles. The silica particles may include multiple first particles. The content of the first particles in the silica particles (when the first particles include second particles described below, the content of the first particles including the second particles) may be, for example, 40% by mass or more, 60% by mass or more, 80% by mass or more, 90% by mass or more, 95% by mass or more, or 100% by mass. Silica particles will be described with reference to FIG. 1. The silica particles 100 include first particles 101. The median particle diameter of the first particles 101 is 120 nm or more and 800 nm or less in the particle size distribution of the first particles 101. In this specification, the median particle diameter refers to the median value of the particle diameter in the particle size distribution, and is the median diameter (D50). In FIG. 1, the particle diameter of the first particles 101 is the length D. In this specification, the particle size refers to the longest particle size (longest diameter). In this specification, the particle size distribution of the first particles refers to the particle size distribution obtained from the longest diameters measured for 25 or more particles (first particles) having a particle size of 100 nm or more in an image of the silica particles observed at 50,000 magnification using a scanning electron microscope (SEM), and the central particle size of the first particles refers to the median value calculated from the particle size distribution.

[0022] As shown in FIG. 1 , the silica particles may have particles 102 with a particle size of less than 100 nm on the surface of the first particles 101. In this specification, the particles 102 with a particle size of less than 100 nm that are included in the first particles 101 are also referred to as second particles. The median particle size of the second particles 102 is 10 nm or more and less than 100 nm in the particle size distribution of the second particles 102. The first particles may have multiple second particles. Having second particles on the surface of the first particles tends to increase the specific surface area of ​​the silica particles. The silica particles may include at least one of first particles with multiple second particles and first particles without second particles, or may include only first particles with multiple second particles and first particles without second particles, or may include only first particles with multiple second particles or first particles without second particles. The presence of second particles 102 in the first particles 101 can be confirmed, for example, by observation at 200,000x magnification using an SEM. The particle size distribution of the second particles is a particle size distribution obtained from the longest diameter measured for 25 or more particles (second particles) having a particle size of less than 100 nm in an SEM image of the silica particles observed at 200,000 magnification, and the central particle size of the second particles is the median value calculated from the particle size distribution.

[0023] When the silica particles contain second particles, the second particles may be attached to most or all of the first particles. When the second particles are attached to the outer surfaces of the first particles, the contact area of ​​the silica particles as a whole with the soil tends to be larger, and as a result, plant growth due to the silica particles tends to be improved. In this specification, "attached" means, for example, that the first particles 101 and the second particles 102 are integrated to such an extent that they do not fall off when water is poured over the silica particles 100. A chemical bond, such as a covalent bond, may exist between the first particles 101 and the second particles 102.

[0024] As shown in FIG. 1 , the first particle 101 may have voids 103 therein. The second particle 102 may also have voids 103 therein. When the porosity of a single particle is defined as the ratio of the area occupied by voids to the cross-sectional area of ​​a single silica particle in the cross section of the particle, the porosity of a single particle may be, for example, 0.2% to 6.0%, or 2.5% to 6.0%, or 0.2% to 2.0%, for example, 1.2%. The ratio of the voids 103 in the first particle 101 may be less than 0.2% or greater than 6.0%. The porosity of a single particle can also be measured, for example, by analyzing images captured by a transmission electron microscope (TEM).

[0025] The first particles 101 and the second particles 102 may be secondary particles (aggregated particles) composed of a plurality of primary particles. The average particle size of the primary particles may be, for example, 50 nm or less, 1 nm or more and 50 nm or less, or 10 nm or more and 40 nm or less. Furthermore, the fact that the first particles 101 and the second particles 102 are secondary particles composed of a plurality of primary particles can be confirmed by the following procedure. First, silica particles are immersed in an alkaline solution for 5 days. The alkaline solution may be a strong alkaline solution. Then, the surface or cross section of the silica particles removed from the alkaline solution is observed using SEM or TEM. This allows the presence of a primary particle or a boundary between multiple primary particles to be confirmed.

[0026] The first particles 101 may have cracks. The term "cracks" refers to a general term for linear images on the surfaces of the first particles 101 observed in an image observed at 150,000 magnifications using an SEM. The cracks may be groove-like depressions, linear scratches, steps, or the like that occur on the surfaces of the first particles 101.

[0027] The specific surface area of ​​the silica particles 100 is, for example, 15 m ２ / g or more 200m ２ / g or less, and ２ / g. The specific surface area is the value of the surface area per unit weight. The specific surface area of ​​silica particles is measured, for example, by a gas adsorption measurement method using the BET method. The BET method is a method for measuring the surface area of ​​particles by adsorbing a gas with a known adsorption occupation area onto the surface of the particles. The specific surface area of ​​silica particles 100 is 15 m within the range in which the effects of the present disclosure can be obtained. ２ / g or less than 200m ２ / g or more.

[0028] The silica particles may be amorphous. The crystallinity of the silica particles is confirmed by X-ray diffraction (XRD). Both the first particles and the second particles may be amorphous.

[0029] The coefficient of variation of the silica particles may be, for example, 0.30 or less. The coefficient of variation is the value obtained by dividing the standard deviation of the particle diameter of the silica particles by the average particle diameter of the silica particles. The coefficient of variation may be greater than 0.30 as long as the effects of the present disclosure are achieved.

[0030] The silica particles may not contain particles having a particle size of less than 100 nm other than the first particles and the second particles contained in the first particles, or may contain only a very small amount of particles having a particle size of less than 100 nm compared to the amount of the first particles 101. When the silica particles contain particles having a particle size of less than 100 nm, the number of particles having a particle size of less than 100 nm may be 1 / 100 or less of the number of the first particles 101.

[0031] Silica particles are SiO ２ As used herein, the term "main component" refers to the component with the largest content in terms of mass among the constituent components, and may be, for example, 90 mass % or more, 95 mass % or more, or 99 mass % or more based on the total mass of all constituent components. The first particles and the second particles may be particles containing SiO as the main component. ２ The SiO in the silica particles may be ２ The content of is measured by X-ray fluorescence analysis. In this specification, the remaining constituent components other than the main component are also referred to as minor components.

[0032] Silica particles are composed of carbon (C), diphosphorus pentoxide (P２ O ５ ), sulfur trioxide (SO ３ The silica particles may further contain one or more elements or compounds selected from the group consisting of chlorine (Cl), sodium (Na), and nitrogen (N) as minor components. Since Na, Cl, phosphorus (P), and sulfur (S) are nutrients for plant growth, the inclusion of the above elements or compounds in the silica particles as minor components tends to be advantageous for plant growth. The silica particles may further contain Na, Cl, P within a range in which the effects of the present disclosure can be obtained. ２ O ５ , S.O. ３ The content may not necessarily be any of the above, and is not limited to the examples of the content shown below.

[0033] When the silica particles contain C, the C content in the silica particles may be, for example, 5.0 mass% or less, 1.5 mass% or more, or even 1.5 mass%. The C content in the silica particles can be measured using a carbon-sulfur analyzer (CS analyzer). In carbon measurement using a CS analyzer, the silica particles are dissolved in a high-frequency heating furnace in an oxygen stream. At this time, the C component contained in the silica particles is dissolved in CO, CO ２ The carbon-derived gas is then measured using an infrared detector. This quantifies the amount of carbon contained in the silica particles. From the quantification results, the carbon content in the silica particles is calculated. The carbon content in the silica particles may be less than 1.5% or more than 5.0%, as long as the effects of the present disclosure are achieved.

[0034] Silica particles are P ２ O ５ When the silica particles contain ２ O ５ The content of may be, for example, 0.1 mass % or less, or may be 0.01 mass %. ３ When the silica particles contain ３The content of may be, for example, 0.1% by mass or less, or may be 0.04% by mass. When the silica particles contain Cl, the content of Cl in the silica particles may be, for example, 0.05% by mass or less, or may be 0.02% by mass. When the silica particles contain Na, the content of Na in the silica particles may be, for example, less than 0.01% by mass, or may be 0.01% by mass or more as long as the effects of the present disclosure are obtained. P in the silica particles ２ O ５ , S.O. ３ The Cl content is measured by, for example, X-ray fluorescence analysis, and the Na content is measured by, for example, emission spectroscopy.

[0035] When the silica particles contain N, the N content in the silica particles may be, for example, 1.0 mass% or less, 0.8 mass% or less, or 0.73 mass% or less. The N content in the silica particles is measured, for example, by an inert gas fusion method.

[0036] N is ammonia nitrogen (NH ４ N may exist as ammonia nitrogen (NH ４ When present as ammonia nitrogen (NH ４ The content of nitrate nitrogen (NO -N) may be, for example, 5.0 mg / 100 g or less, 4.0 mg / 100 g or less, 3.0 mg / 100 g or less, 1.6 mg / 100 g or less, or 1.5 mg / 100 g or less. ３ The silica particles may contain, for example, less than 0.1 mg / 100 g of nitrate nitrogen (NO -N), or less than 0.05 mg / 100 g of nitrate nitrogen (NO ３-N). The contents of ammonia nitrogen and nitrate nitrogen in silica particles are measured, for example, in accordance with the method described in "Soil Environmental Analysis Methods" (Soil Environmental Analysis Methods Editorial Committee, 1997). The content of ammonia nitrogen in silica particles can be measured, for example, by the indophenol method using potassium chloride solution as the extraction solution. The content of nitrate nitrogen in silica particles can be measured, for example, by extracting with potassium chloride solution, followed by alkali reduction, and then by the diazo dye method.

[0037] The content of available silicic acid in silica particles may be, for example, 30 mg / 100 g or less, 26.0 mg / 100 g or less, or 25.8 mg / 100 g. When the content of available silicic acid in silica particles is within the above range, they tend to be insoluble in water. The content of available silicic acid in silica particles is measured, for example, in accordance with the method described in "Soil, Water Quality and Plant Analysis Method" (Japan Soil Association, 2001). The content of available silicic acid in silica particles can be measured, for example, by the molybdenum blue method after extraction with a pH 6.2 phosphoric acid extract.

[0038] The silica particles may have a base exchange capacity (CEC) (also known as fertilizer retention capacity) of, for example, 1.0 meq / 100 g or less, 0.6 meq / 100 g or less, or 0.5 meq / 100 g or less. The CEC of the silica particles is measured, for example, in accordance with the method described in "Soil Environmental Analysis Methods" (Soil Environmental Analysis Methods Editorial Committee, 1997). The CEC of the silica particles can be measured, for example, by the indophenol method after extraction using the modified Schollenberger method.

[0039] Silica particles may be hardly dissolved in water, or may be insoluble in water.Therefore, silica particles are less likely to dissolve in the water contained in the culture soil, and are less likely to produce silicic acid.For example, when about 0.27g of silica particles are added per 1L of soil, a portion of the silica particles dissolves in water, and the silicic acid concentration in the culture soil can increase by about 21ppm compared to before the silica particles dissolve.Incidentally, silicic acid refers to orthosilicic acid (H ４ SiO ４), metasilicic acid (H ２ SiO ３ In soil, silicic acid refers to water-soluble compounds containing SiOH, such as calcium silicate (Ca ２ SiO ４ Silica may also exist as silicates such as silicate silica (e.g., silica sulphite ...

[0040] The growth improver can be produced, for example, by using commercially available silica particles. Alternatively, the growth improver can be produced, for example, by a production method (hereinafter also referred to as the first production method) using silica particles produced during the production of electronic components, as described below.

[0041] FIG. 2 shows a flowchart of the first manufacturing method. In the laminate preparation step S11, a laminate, which is a rectangular parallelepiped element body, is prepared. For example, a plurality of ceramic sheets that will serve as the element body are prepared. The ceramic sheets may be thin plates. A conductive paste that will serve as electrodes and wiring is laminated on the ceramic sheets. A ceramic sheet that will serve as the element body is laminated on the laminated conductive paste. In this way, the ceramic sheets and the conductive paste are laminated. Then, an unfired laminate is formed by cutting to a predetermined size. The unfired laminate is then fired at a high temperature to prepare the laminate.

[0042] Next, a solvent introduction step S12 is performed. In the solvent introduction step S12, a solvent is introduced into the reaction vessel. The solvent may be any liquid that can disperse the metal alkoxide appropriately, such as 2-propanol.

[0043] Next, a catalyst introduction step S13 is performed. In the catalyst introduction step S13, first, stirring of the solvent in the reaction vessel is started. Then, ammonia water is introduced into the reaction vessel as an aqueous solution containing a catalyst. The catalyst is a hydroxide ion, and functions as a catalyst for promoting the hydrolysis of the metal alkoxide, which will be described later.

[0044] Next, an object introduction step S14 is performed. In the object introduction step S14, a plurality of element bodies formed in advance in the laminate preparation step S11 described above are introduced into the reaction vessel as objects.

[0045] Next, a polymer introduction step S15 is carried out. In the polymer introduction step S15, polyvinylpyrrolidone is introduced into the reaction vessel as a polymer. As a result, the polymer introduced into the reaction vessel is adsorbed onto the outer surface of the element body.

[0046] Next, a metal alkoxide introduction step S16 is performed. In the metal alkoxide introduction step S16, liquid tetraethyl orthosilicate is introduced into the reaction vessel as the metal alkoxide. Note that tetraethyl orthosilicate is also called tetraethoxysilane.

[0047] Next, the film-forming step S17 is performed. In the film-forming step S17, the stirring of the solvent, which began in the solvent-feeding step S12 described above, is continued for a predetermined time after the metal alkoxide is fed into the reaction vessel in the metal alkoxide-feeding step S16. As a result, the metal alkoxide is hydrolyzed by the hydroxide ions serving as a catalyst. When the metal alkoxide is hydrolyzed, the hydrolyzed metal alkoxide adheres to the surface of the element body. Then, the metal alkoxides attached to the surface of the element body dehydrate and condense with each other to form a glass film. Therefore, in the film-forming step S17, a sol-like glass film is formed by a liquid-phase reaction in the reaction vessel. Furthermore, the dehydration and condensation reaction between the metal alkoxides also progresses in the solution. As a result, sol-like silica particles are produced as a by-product.

[0048] Next, an element removal step S18 is performed. In this step, the element is removed from the reaction vessel. The element is then dried and fired to obtain an electronic component having a glass film formed on the outer surface of the element.

[0049] Next, a recovery step S19 is performed. In the recovery step S19, silica particles present in the solution in the reaction vessel are recovered. Specifically, the solvent in the reaction vessel is evaporated to recover the silica particles remaining in the reaction vessel. As described above, this solution contains sol-like silica particles. Note that tetraethyl orthosilicate and polyvinylpyrrolidone adhere to the outer surfaces of the recovered silica particles.

[0050] Next, a drying step S20 is performed. In the drying step S20, the sol-state silica particles recovered in the recovery step S19 are dried. This removes most of the liquid components, such as 2-propanol and water, from the recovered sol-state silica particles. Through this drying step S20, first particles having a particle size of 100 nm or more are generated as silica particles. The median particle size of the generated first particles is 120 nm or more and 800 nm or less in the particle size distribution of the first particles. The particle size of the generated first particles can be controlled, for example, by adjusting the time of the film-forming step S17.

[0051] Next, the baking step S21 is performed. In the baking step S21, the silica particles that have undergone the drying step S20 are baked at a temperature of 300°C to 450°C for 5 to 40 minutes. Specifically, the baking is performed at a temperature of 400°C for 30 minutes. As a result, the gel-like silica particles contained in the solution harden as the moisture and polymer evaporate. Through this baking step S21, second particles with a particle size of less than 100 nm are generated as silica particles. The median particle size of the generated second particles is 10 nm to 100 nm in the particle size distribution of the second particles. Furthermore, the generated second particles that are in contact with the first particles are sintered together with the first particles during the baking step S21. Therefore, the second particles adhere to the surfaces of the first particles. The particle size of the generated second silica particles can be controlled by adjusting the baking temperature and time in the baking step S21. In this manner, silica particles are produced that include first silica particles having a median particle size of 120 nm or more and 800 nm or less and second silica particles having a median particle size of 10 nm or more and less than 100 nm.

[0052] As described above, the growth improver can be produced using a solution containing silica particles, which is an industrial by-product. This eliminates the need to dispose of the solution containing silica particles. It is also environmentally friendly because it reduces the energy required for this process.

[0053] The growth improver may be produced during the process of forming a glass film on the object, and may not be produced during the process of manufacturing the electronic component. In other words, the object introduced into the reaction vessel 11 in the object introduction step S14 does not have to be an element of an electronic component.

[0054] The solvent introduction step S12 may be performed after the catalyst introduction step S13 or the object introduction step S14. The solvent introduction step S12 may be performed before at least one of the metal alkoxide introduction step S16 and the catalyst introduction step S13. The solvent introduction step S12 may also be omitted. In this case, for example, if the amount of water contained in the aqueous solution containing the catalyst is appropriately large, the metal alkoxide will react in the liquid phase. Alternatively, the aqueous solution containing the catalyst may be introduced in a state where it is mixed with an organic solvent as a solvent.

[0055] Although the catalyst has been described as being added as an aqueous solution containing the catalyst, a solid compound containing the catalyst and water may be added separately to the reaction vessel, in which case the catalyst can be considered to have been added to the reaction vessel when it is produced in the reaction vessel. Alternatively, for example, a solid compound containing the catalyst may be added to the reaction vessel, and moisture in the air may be used as the water required for hydrolysis.

[0056] The object introduction step S14 may be performed before the catalyst introduction step S13. Furthermore, when the object introduction step S14 is performed before the catalyst introduction step S13, the metal alkoxide introduction step S16 may be performed before the catalyst introduction step S13 or the object introduction step S14. The object introduction step S14 may be performed before at least one of the metal alkoxide introduction step S16 and the catalyst introduction step S13.

[0057] In the metal alkoxide introduction step S16, the metal alkoxide may be generated in the reaction vessel, instead of being introduced into the reaction vessel after being generated outside the reaction vessel. For example, the metal alkoxide may be generated by reacting a metal salt with an alcohol. Therefore, even when a metal salt and an alcohol, which are metal alkoxide precursors, are introduced into the reaction vessel and reacted to generate the metal alkoxide, the metal alkoxide can be considered to have been introduced into the reaction vessel.

[0058] The metal alkoxide is not limited to tetraethyl orthosilicate. The alkoxy group of the metal alkoxide may be a methoxy group, a propoxy group, or the like, or may be modified with a functional group such as a long-chain alkyl group or an epoxy group, as in a coupling agent. Furthermore, the coordination number for the metal contained in the metal alkoxide is not limited to tetracoordination, but may be 3 or 2.

[0059] The element removal step S18 may be omitted. That is, the recovery step S19 may be performed while the element remains in the reaction vessel.

[0060] In the calcination step S21, the temperature at which the sol- or gel-like particles are calcined may be less than 300° C. or more than 450° C. The calcination time may be less than 5 minutes or more than 40 minutes. For example, even if the temperature is higher than 450° C., calcination for less than 5 minutes may be sufficient as long as silica particles having a median particle size of 120 nm to 800 nm can be produced.

[0061] In the recovery step S19, the silica particles may be recovered by, for example, evaporating the solvent by drying under reduced pressure. The particle size of the first silica particles generated in the drying step S20 and the firing step S21 may be controlled by the concentration of the materials in each step, etc.

[0062] The first particle 101 may be a multilayer particle having a core portion and an outer layer. A first particle that is a multilayer particle is also referred to as a first multilayer particle. The core portion is approximately spherical and includes the center of gravity of the silica particle. The core portion may have a void 103 therein. The outer layer is a portion that covers the core portion from the outside and includes the outer surface of the first particle 101. The first particle 101 has an outer layer on the surface side including the outer surface. The silica particle 100 may contain polyvinylpyrrolidone. When the silica particle 100 contains polyvinylpyrrolidone, the outer layer may contain polyvinylpyrrolidone. When the outer layer contains polyvinylpyrrolidone, the concentration of polyvinylpyrrolidone is higher than the concentration of polyvinylpyrrolidone in the portion of the silica particle excluding the outer layer, i.e., the core portion. Furthermore, when the silica particle is imaged using, for example, a field emission transmission electron microscope (FE-TEM), a substantially clear interface may be observed between the outer layer and the portion of the silica particle excluding the outer layer. The first multilayer particle may or may not have a second particle.

[0063] The ratio of the thickness T of the outer layer to the particle diameter D of the first particles 101 (also referred to as the T / D ratio) may be, for example, 2% or more. For example, when the particle diameter D of the first particles 101 is approximately 260 nm and the thickness T of the outer layer 105 is approximately 15 nm, the T / D ratio is approximately 5.2%. Polyvinylpyrrolidone has various properties, such as high hygroscopicity and viscosity increasing properties. Therefore, when the outer layer contains polyvinylpyrrolidone, it tends to be more effective in improving plant growth, such as preventing soil from drying out and sustained release of active ingredients.

[0064] The thickness T of the outer layer is defined as follows. First, an image of the first particle 101 is taken using an FE-TEM or the like. In the image, the dimension of the outer layer at an arbitrary point on the outer surface of the first particle 101 in a direction perpendicular to the outer surface is defined as the thickness T of the outer layer at that point. More specifically, "a direction perpendicular to the outer surface at an arbitrary point on the outer surface of the mother particle" refers to a direction perpendicular to a tangent line drawn to the first particle 101 with the arbitrary point as a contact point. The thickness of the outer layer is the distance from the arbitrary point to the interface in the perpendicular direction.

[0065] The first multilayer particles are produced, for example, by recovering silica particles from a solution after the steps from the laminate preparation step S11 to the drying step S20 in the first production method. That is, the first multilayer particles can be silica particles after the drying step S20 and before the firing step S21 in the first production method.

[0066] The silica particles may have an outer layer having a polyvinylpyrrolidone concentration equal to or lower than that of the core, and the ratio of the thickness T of the outer layer to the particle diameter D of the silica particles may be less than 2%. Even in these cases, the effects of the present disclosure can be obtained.

[0067] The first particles may have a T / D ratio of less than 2% or may not have an outer layer, i.e., the silica particles may not have a clear boundary between the core and the outer layer.

[0068] The silica particles may include both first particles having no multilayer structure and first multilayer particles. In other words, the silica particles may include both silica particles after the firing step S21 and silica particles after the drying step S20 without the firing step S21.

[0069] The plant to which the growth improver is applied may be a dicotyledonous plant or a monocotyledonous plant. The growth improver is suitable for growing agricultural crops. The agricultural crops may be, for example, edible plants such as vegetables and fruits. The growth improver is suitable for growing plants that are expensive to grow or difficult to grow. The growth improver is suitable for growing, for example, agricultural crops that become luxury foodstuffs.

[0070] Examples of edible plants include plants from the Brassicaceae family, Amaranthaceae family, Solanaceae family, and Dioscorea family. Examples of Brassicaceae plants include komatsuna (Japanese mustard spinach) and daikon radish. Examples of Amaranthaceae plants include spinach. Examples of Solanaceae plants include tomatoes (tomatoes, cherry tomatoes). Examples of Dioscorea plants include Japanese yam and Chinese yam.

[0071] The growth improver is also suitable for the growth of non-edible plants. Examples of non-edible plants include ornamental plants (such as aquatic plants), plants for livestock feeding, and plants for biomass power generation (fuel). The growth improver is suitable for the growth of plants used as feedstock for mass-produced biomass materials, fast-growing plants, and plants with high power generation efficiency.

[0072] Examples of non-edible plants include plants from the families Flycatcher family, Utricularia family, Poaceae, and Asteraceae. Examples of plants from the Flycatcher family include Miniglossostigma. Examples of plants from the Utricularia family include water lawn. Examples of plants from the Poaceae family include dent corn. Examples of plants from the Asteraceae family include sunflower.

[0073] Furthermore, the growth improver can be applied not only to plants that absorb a relatively large amount of silicic acid, but also to plants that absorb a relatively small amount of silicon (for example, tomatoes).

[0074] The plant to which the growth improver is applied is preferably at least one selected from the group consisting of komatsuna, spinach, cherry tomatoes, yams, aquatic plants, and dent corn, and more preferably at least one selected from the group consisting of spinach, cherry tomatoes, yams, aquatic plants, and dent corn.

[0075] By applying a growth improver to plant growth, plant growth can be improved regardless of the plant's ability to absorb silica. Improving plant growth includes, for example, at least one selected from the group consisting of promoting plant growth (also referred to as growth promotion), preventing salt damage to plants (also referred to as salt damage prevention), improving the eating quality of plants (also referred to as eating quality improvement), repelling plant pests (also referred to as pest repellent), improving plant root development (also referred to as root development improvement), and controlling the growth direction of plants (also referred to as growth direction control).

[0076] From the viewpoint of promoting plant growth, the plants to which the growth improver is applied are preferably Brassicaceae, Amaranthaceae, Solanaceae, Dioscoreaceae, and Poaceae, more preferably Komatsuna, spinach, cherry tomatoes, yams, and dent corn, and even more preferably spinach, cherry tomatoes, yams, and dent corn. The growth improver may be, for example, a growth promoter that promotes plant growth, and is preferably a growth promoter for Komatsuna, spinach, cherry tomatoes, yams, and dent corn. It is believed that the reason for promoting plant growth is that the inclusion of silica particles activates bacteria useful for promoting plant growth in the culture soil.

[0077] The application of a growth promoter to plant growth tends to increase the yield of the plant. The yield may be, for example, the fresh weight, number of plants, or number of plants harvested. When a growth promoter is applied to the growth of spinach, the yield (fresh weight) can be increased, for example, by about 1.5 to 3 times. When a growth promoter is applied to the growth of dent corn, the yield (number of plants) can be increased, for example, by about 2 to 3 times.

[0078] By applying a growth promoter to the growth of plants, the content of vitamin components and mineral components in the plants tends to be easily increased. When the growth promoter is applied to the growth of spinach, for example, the content of vitamin B1 and total vitamin C tends to be easily increased. When the growth promoter is applied to the growth of cherry tomatoes, the content of potassium, vitamin A, and total vitamin C tends to be easily increased. The content of vitamin components and mineral components is measured according to the method described in the Examples section below.

[0079] The application of a growth promoter to the growth of plants tends to improve the germination rate of the plants. For example, when the growth promoter is applied to the growth of spinach, the germination rate can be increased by about 1.4 to 2.0 times.

[0080] The application of a growth promoter to the growth of plants tends to make it easier to suppress damage caused by continuous cropping. When the growth promoter is applied to the growth of yams, damage caused by continuous cropping can be suppressed.

[0081] The plant to which the growth improver is applied is preferably a plant of the Brassicaceae or Amaranthaceae family, more preferably spinach, from the viewpoint of preventing salt damage to the plant. The growth improver may be, for example, a salt damage inhibitor that prevents salt damage to the plant, and is preferably a salt damage inhibitor for spinach. Note that the reason why salt damage to the plant can be prevented is thought to be that the inclusion of silica particles allows excess salt in the culture soil to be adsorbed by the silica particles.

[0082] By applying a salt damage inhibitor to plant growth, the effects of salt on plant germination can be reduced. For example, salt damage can be suppressed in the parts of the plant that are in direct contact with the soil. Furthermore, since plants can grow even in highly saline soil, cultivating edible plants in highly saline soil can impart a salty taste to the plants. This allows edible plants to be cultivated using seawater or brackish water as spray water. When a salt damage inhibitor is applied to the growth of spinach, the decrease in germination rate can be suppressed in saltwater cultivation compared to pure water cultivation.

[0083] From the viewpoint of improving the taste of the plant, the plant to which the growth improver is applied is preferably a plant of the Solanaceae family, more preferably a tomato, and even more preferably a cherry tomato. The growth improver may be, for example, a taste improver that improves the taste of the plant, and is preferably a taste improver for cherry tomatoes. Improving the taste of the plant includes, for example, reducing sourness, increasing umami, and increasing sugar content. The reason why the plant taste can be improved is thought to be that the inclusion of silica particles activates bacteria in the culture soil that affect the plant's ability to absorb taste components.

[0084] Applying a taste improver to a plant can facilitate reducing the sourness (citric acid) of the plant. Applying a taste improver to a plant can facilitate increasing the umami of the plant. Applying a taste improver to a plant can facilitate increasing the sugar content of the plant. When a taste improver is applied to growing cherry tomatoes, it can reduce the sourness (citric acid) of the cherry tomatoes while increasing the umami and sugar content. In this specification, taste is evaluated according to the method described in the Examples section below.

[0085] From the viewpoint of repelling plant pests, the plants to which the growth improver is applied are preferably plants of the Solanaceae, Brassicaceae, and Poaceae families, more preferably cherry tomatoes, Japanese mustard spinach, and dent corn. The growth improver may be, for example, a pest repellent that repels plant pests, preferably a pest repellent for cherry tomatoes, Japanese mustard spinach, and dent corn. Repelling pests includes, for example, keeping pests away from plants, suppressing pest eating by pests, and suppressing the occurrence of pest-related diseases. It is presumed that the reason for plant pest repelling is that the inclusion of silica particles facilitates the enhancement of the activity of microorganisms that repel pests.

[0086] Applying a pest repellent to a plant tends to make it easier to repel pests from the plant, and tends to make it easier to suppress the occurrence of pest-eaten or disease caused by pests. When a pest repellent is applied to growing komatsuna, it can suppress the occurrence of pest-eaten komatsuna. Furthermore, when a pest repellent is applied to growing cherry tomatoes and dent corn, it can make it easier to repel pests.

[0087] From the viewpoint of improving root establishment, the plants to which the growth improver is applied are preferably aquatic plants, more preferably plants of the Diptera and Utricularia families, and even more preferably Miniglossostigma and Waterloo. The growth improver may be, for example, a root establishment improver that improves root establishment of plants, and is preferably a root establishment improver for aquatic plants. When the root establishment improver is applied to the growth of aquatic plants, root establishment in the culture soil is improved, and for example, when the water in an aquarium is changed, the roots tend to be more likely to be prevented from floating up from the soil even if the water is vigorously stirred.

[0088] The plant to which the growth improver is applied is preferably a plant of the Dioscoreaceae family, more preferably a yam, from the viewpoint of controlling the growth direction of the plant. The yam may be, for example, a yam or a Chinese yam. The growth improver may be, for example, a growth direction regulator that controls the growth direction of the plant, and is preferably a growth direction regulator for yams. The value of vegetables and fruits may be affected by their shape. By applying a growth direction regulator to the growth of plants, it is possible to easily control the shape of the vegetables and fruits so as not to impair their value. By applying a growth direction regulator to the growth of yams, it is possible to improve straightness.

[0089] Furthermore, when the growth improver contains silica particles that have a low content of available silica and are insoluble in water, it is possible to grow plants with reduced silica content. For example, when the growth improver is applied to the growth of rice, a plant that absorbs a relatively large amount of silica, it is possible to reduce the silica content in the rice. As a result, it tends to be easier to obtain soft rice and rice straw.

[0090] The growth improver is also expected to be applicable to the growth of non-plant species such as mushrooms, for example, matsutake mushrooms.

[0091] The growth improver can be applied to the growth of plants according to the growth method described below.

[0092] [Growth Method] The growth method of the present disclosure is a method for growing plants using the above-mentioned growth improver. The growth method includes, for example, a culture soil preparation step of preparing culture soil by mixing the growth improver with soil. The growth method can further include, for example, a sowing step of planting seeds or seedlings of a plant to be grown in the culture soil, and a growth step of spraying water.

[0093] The culture medium can be prepared by blending soil with a growth improver. The soil may be, for example, sandy loam, loam, clay loam, or other soil suitable for growing crops. The soil may be soil from farmland such as fields, or commercially available soil. The soil may contain, for example, Akadama soil, Kanuma soil, compost, and coconut shell materials. The soil alone may have, for example, a pH of 6.5±0.5 and an electrical conductivity of 1.0 mS / cm, and the pH and electrical conductivity can be adjusted appropriately to suit the crop being grown.

[0094] The growth improver can be mixed with the soil by, for example, creating a depression in the soil placed in a container, spraying the growth improver into the depression, and then covering it with soil. The shape, size, and depth of the depression can be determined appropriately depending on, for example, the shape, size, and depth of the container, the type of plant being grown, and other factors. For example, when using a planter with a rectangular opening, a linear depression of a predetermined depth is created in the center of the soil along the long side of the opening, and a predetermined amount of growth improver is uniformly sprayed onto the bottom surface of the depression (Figure 7). Next, soil is placed into the depression on top of the growth improver, and the soil surface is smoothed to allow the growth improver and soil to be mixed. The container for the soil can be, for example, a pot, planter, plug tray, or pot. The container can be made of, for example, plastic, ceramic, wood, paper, or glass. The growth improver can also be mixed directly with the soil in the field, as described below.

[0095] The amount of growth improver to be mixed into the soil (hereinafter also referred to as the mixing amount) may be, for example, 0.2 g to 1.5 g, preferably 0.2 g to 0.4 g, per 1 L of soil. The amount of soil previously placed in the container, the amount of growth improver to be mixed, the amount of soil to be placed in the depression where the growth improver has been sprayed, and the amount of soil or potting soil to be placed in the hole or trench where the seeds or seedlings are planted can be adjusted so that the ratio of soil to growth improver placed in the container satisfies the above mixing amount.

[0096] The amount of growth improver contained in the culture medium may be more than 1.5 g per 1 L of soil, as long as the effects of the present disclosure are obtained. Analysis of harvested plants has confirmed that even if the soil contains a large amount of growth improver, there is no direct excess damage to the plants caused by the growth improver, and no direct adverse effects on the plants.

[0097] The content of ammonia nitrogen in the culture soil may be, for example, 3.3 mg / 100 g or more, or 3.7 mg / 100 g or more.

[0098] The content of nitrate nitrogen in the culture soil may be, for example, 0.2 mg / 100 g or more, 0.5 mg / 100 g or more, or 0.8 mg / 100 g or more.

[0099] The voltage generated by microbial power generation using culture soil can be, for example, 0.7 V or higher. If the voltage generated by microbial power generation in the culture soil is within the above range, microbial activity is vigorous, making the culture soil suitable for plant cultivation. Furthermore, the microorganisms tend to decompose nitrate nitrogen in the culture soil, increasing the amount of ammonia nitrogen that can be absorbed by plants. The voltage generated by microbial power generation can be measured as follows. Specifically, the culture soil was placed into a measuring device (microbial fuel cell experimental device, product number: MudWatt, Kenis). Then, two weeks after placement, the voltage generated between the electrodes of the microbial power generation measuring device was measured. Note that the voltage generated by microbial power generation may be less than 0.7 V as long as the effects of the present disclosure can be obtained.

[0100] The content of available silicon in the culture medium may be, for example, 164 mg / 100 g or less, or 161 mg / 100 g or less. Even if the culture medium has a relatively low content of available silicon within the above range, the growth method of the present disclosure tends to improve plant growth.

[0101] In the cultivation method, the culture soil may have a multi-layer structure (soil layer / growth improver layer / soil layer) in which the soil and growth improver are not completely mixed in a container or field, or may be a mixture of soil and growth improver.

[0102] In order to facilitate the promotion of the growth of microorganisms living in the soil, the culture medium may contain microbial materials.

[0103] In the sowing process, for example, holes or trenches can be made in the prepared potting soil, and the seeds or seedlings of the plants to be grown can be placed in the holes or trenches. The holes or trenches can be made at regular intervals on the surface of the potting soil. For example, if a growth improver is sprayed along the long side of the opening of a planter, holes can be made in the potting soil at regular intervals along the long side (FIG. 8). If the growth improver is sprayed into depressions made in the soil in the potting soil preparation process, holes or trenches can be made shallower than the depth of the depressions. The size and location of the holes or trenches can be appropriately determined depending on the size and shape of the container, the type of plant to be grown, etc. After the seeds or seedlings are planted, the holes or trenches can be covered with potting soil or soil.

[0104] During the growing process, water may be sprayed. Fertilizer may also be added to the culture soil. The amount and frequency of water and fertilizer to be sprayed can be determined taking into account the type of plant, the growing environment, the growth level, etc.

[0105] In a variation of the growing method, the growth improver can be applied to the surface of the soil. For example, in a field, the growth improver can be applied directly to the surface of the soil. The growth improver can also be applied after planting seeds or seedlings in the soil. When the growth improver is applied to the surface of the soil, for example, 1 m of soil. ２The growth improver can be applied at a rate of 5 to 100 g per 10 cm2 of surface area of ​​the potting soil. ２ The silica particles may be sprayed in an amount such that the concentration of silica particles in 1 L of culture soil collected from the area where the silica particles are present, including the surface, is, for example, 0.2 g to 1.5 g, preferably 0.2 g to 0.4 g. The concentration of silica particles in the culture soil can be measured as follows. First, the amount of available silicic acid in the culture soil is measured. Available silicic acid can be measured by the method described in "Method for evaluating available silicic acid in paddy field soil by phosphate buffer solution extraction method" (Japanese Journal of Soil Science and Plant Nutrition, 2002, Vol. 73, No. 4, pp. 383-390). Next, the silica content in the culture soil is measured. The silica content refers to the SiO2 content including insoluble silica and water-soluble silica (available silicic acid). ２ The silica content refers to the content of all components derived from the soil. The silica content can be calculated by measuring the amount of silica eluted when silica in the soil is eluted with a high concentration of alkali using ICP atomic emission spectroscopy or atomic absorption spectroscopy. The amount of silica particles is calculated by subtracting the amount of available silicic acid from the silica content.

[0106] In yet another method, a potting mix may be prepared by mixing a predetermined amount of growth improver with soil, and then the potting mix may be placed in a container (e.g., a clever pipe) for growing the plant. Alternatively, the potting mix may be prepared and then spread on the field.

[0107] The growth method may be a method for improving plant growth using the above-mentioned taste improver, pest repellent, root expansion improver, and growth direction regulator. The growth method may be at least one selected from the group consisting of a method for promoting plant growth, a method for preventing salt damage to plants, a method for improving the taste of plants, a method for repelling pests from plants, a method for improving root expansion of plants, and a method for controlling the growth direction of plants.

[0108] From the viewpoint of promoting plant growth, the growing method is preferably a method for promoting the growth of Japanese mustard spinach, spinach, cherry tomatoes, yams, and dent corn.

[0109] The growing method is preferably a method for preventing salt damage to spinach from the viewpoint of preventing salt damage to plants.

[0110] The growing method is preferably a method for improving the eating taste of cherry tomatoes, from the viewpoint of improving the eating taste of the plant.

[0111] The growing method is preferably a method for repelling pests from cherry tomatoes, Japanese mustard spinach, and dent corn, from the viewpoint of repelling pests from plants.

[0112] The growing method is preferably a method for improving the root growth of aquatic plants from the viewpoint of improving the root growth of plants.

[0113] The growing method is preferably a method for controlling the growth direction of yams from the viewpoint of controlling the growth direction of plants.

[0114] Second Embodiment [Biochar] The biochar according to the second embodiment is a biochar supporting silica particles (hereinafter also referred to as the present biochar). The median particle size of the silica particles having a particle size of 100 nm or more is 120 nm or more and 800 nm or less in the particle size distribution of particles having a particle size of 100 nm or more. The same description of the silica particles in the first embodiment applies to the silica particles.

[0115] According to this biochar, CO ２ As a result, plant growth tends to improve.

[0116] Biochar is CO ２ Biochar can be a carbonized material produced, for example, by heating a biomass material in an environment with a low oxygen concentration. The biomass material may be a biological material, such as rice husks, bamboo, wood, rice straw, livestock manure, or paper sludge generated during the production of recycled paper. Biochar can be a carbonized material of at least one material selected from the group consisting of rice husks, bamboo, and wood.

[0117] The biochar may have pores, which increases the surface area and allows for CO ２ This tends to make it easier for the absorbency of

[0118] The silica particles may be attached entirely or partially to the surface of the biochar, or may be attached within the pores of the biochar. When the silica particles are present in the pores of the biochar, the silica particles are less likely to be washed away even when the biochar is used for growing plants outdoors or in a field, and the effects of the silica particles tend to be more likely to last for a long period of time.

[0119] The silica particles may include first particles having a plurality of second particles. Silica particles including first particles having a plurality of second particles tend to be less likely to peel off from the surface of the biochar. As a result, the outflow of the silica particles is suppressed, and the effects of the silica particles tend to be more likely to be sustained for a long period of time.

[0120] This biochar can be produced by, for example, immersing biochar in a solution in which sol-like silica particles are produced as a by-product in the film-forming step S17 of the first production method in the first embodiment, removing the biochar with the sol-like silica particles attached from the solution, drying it, and then calcining it. The drying conditions can be the same as those in the drying step S20 described above. The calcination conditions can be the same as those in the calcination step S21 described above.

[0121] The size of each biochar particle may be, for example, several microns to several centimeters. Biochar may be in the form of a powdered char produced by finely crushing the raw material, or may be used in the form of a char produced from coarsely crushed raw material.

[0122] In the method for growing plants, biochar can be used by mixing it with soil to prepare a potting compost, or by spreading it on the surface of the soil.

[0123] <Third embodiment> [Plant cultivation kit] A plant cultivation kit according to a third embodiment includes a container, a cover for covering the container, and a culture medium. The culture medium includes silica particles and soil. The median particle size of the silica particles having a particle size of 100 nm or more is 120 nm or more and 800 nm or less in the particle size distribution of the particles having a particle size of 100 nm or more.

[0124] The description of the silica particles in the first embodiment applies to the silica particles. Even when silica particles, which tend to be poorly soluble in water and have poor water absorption, are used, plants can grow well without providing sufficient water during growth. This is thought to be because the silica particles increase bacteria in the soil that are beneficial to plant growth, making it easier for plants to grow well even without providing sufficient water.

[0125] The amount of moisture in the culture medium may be, for example, volumetric water content (VWC). Volumetric water content is the volume of water relative to the total volume of the soil. The volumetric water content of the culture medium during the growing period may be, for example, 70% or less, 60% or less, 50% or less, 40% or less, or 25% or less. The volumetric water content can be measured by a soil sensor capable of measuring temperature and moisture content. The plant cultivation kit may further include a soil sensor capable of measuring temperature and moisture content.

[0126] The plant cultivation kit includes a container and a cover. Potting soil may be contained in the container. The potting soil includes silica particles and soil. The description of the first embodiment applies to the soil and the container.

[0127] The cover functions to protect the plants from bad weather such as strong winds, snowfall, and heavy rain, as well as from pests and external impacts. The cover may be of a size and shape that can cover the opening of the container, or may be of a size and shape that can cover the entire container. The plant cultivation kit requires fewer waterings during plant growth. Therefore, even if the cover is provided, the work of removing and moving the cover to water the plants during growth tends to be reduced, making plant growth easier.

[0128] The cover may be, for example, a thermoplastic resin sheet. Examples of thermoplastic resins include soft polyvinyl chloride, polyester, and polyolefin. Examples of polyolefins include polyethylene and polypropylene. The sheet may be a commercially available agricultural sheet, such as a sheet for greenhouses. From the viewpoint of plant growth, the sheet may preferably be a light-transmitting sheet, more preferably a transparent sheet.

[0129] The culture medium may further contain a water-retaining polymer. By including a water-retaining polymer, moisture in the atmosphere can be easily absorbed into the culture medium, making it easier for plants to grow even when water is not supplied to the culture medium during the plant growth period. Examples of water-retaining polymers include acrylic polymers. The water-retaining polymer may be in the form of particles, sheets, or the like.

[0130] In the plant cultivation kit, the culture soil may be a mixture of soil and silica particles, or may have a multi-layer structure (soil layer / silica particles / soil layer) in which the soil and silica particles are not completely mixed.

[0131] For example, if the container is a planter with a rectangular opening, the culture medium may be placed in a linear depression along the center of the opening, with silica particles scattered in the depression and then covered with soil. The amount of silica particles scattered may be, for example, 0.2 g to 1.5 g per 1 L of soil, preferably 0.2 g to 0.4 g. The components and properties of the culture medium are the same as those described in the first embodiment.

[0132] The plant cultivation kit can grow plants by planting plant seeds or seedlings in the culture soil. The plant cultivation kit may further include plant seeds or seedlings. When the plant cultivation kit further includes plant seeds or seedlings, the plant seeds or seedlings may be planted in the culture soil. The plants grown using the plant cultivation kit may be, for example, plants that are difficult to grow if they are not watered normally during growth, such as Japanese mustard spinach and spinach. Supplying water normally during growth may mean, for example, supplying water at least once a day, daily, or at least once a week.

[0133] The plant cultivation kit may be used indoors or outdoors. When the plant cultivation kit is used outdoors, the diversity of the bacterial flora in the soil tends to be improved.

[0134] By using a plant cultivation kit, plants can be grown even when water is not supplied sufficiently. Watering can be performed, for example, only once after planting the plant seeds or seedlings, or once after planting the plant seeds or seedlings, and then once every 10 days, once every 50 days, or once every 100 days. The watering method can be determined depending on the size of the plant to be grown and the container. Watering can be performed, for example, by spraying with a ladle or watering can, or by spraying from the nozzle of a hose connected to a water source.

[0135] A plant cultivation kit according to another embodiment includes a culture medium and a water-retaining polymer. The culture medium includes silica particles and soil. The median particle size of silica particles having a particle size of 100 nm or more is 120 nm or more and 800 nm or less in the particle size distribution of particles having a particle size of 100 nm or more. The culture medium may include a water-retaining polymer. The above descriptions of the culture medium, water-retaining polymer, silica particles, and soil apply. By including a water-retaining polymer in the culture medium, the moisture content in the culture medium is easily maintained without the need to supply water during plant growth, which tends to facilitate plant growth.

[0136] <Fourth embodiment> [Bacterial flora improver] A bacterial flora improver according to a fourth embodiment contains silica particles. The median particle size of the silica particles having a particle size of 100 nm or more is 120 nm or more and 800 nm or less in the particle size distribution of particles having a particle size of 100 nm or more. The same description of the silica particles in the first embodiment applies to the silica particles.

[0137] The content of silica particles in the bacterial flora improver may be, for example, 99% by mass or more. The bacterial flora improver may consist solely of silica particles. The content of silica particles in the bacterial flora improver may be less than 99% by mass, as long as the effects of the present disclosure are obtained.

[0138] The bacterial flora improved by the bacterial flora improver can be soil bacterial flora. By using culture soil containing the bacterial flora improver for growing plants, plant growth tends to be improved.

[0139] The bacterial flora improver can improve the diversity of the bacterial flora. The bacterial flora improver can improve the diversity of the bacterial flora in the soil. In general, the more diverse the bacterial species in the soil, the better the soil is, for example, because the soil is more resistant to environmental changes. The diversity of the bacterial flora can be confirmed, for example, by the type and abundance of bacteria. Furthermore, the diversity of the bacterial flora may be α-diversity and β-diversity. The bacterial flora improver can improve at least one of α-diversity and β-diversity.

[0140] Alpha diversity is an index that indicates the diversity of species within a certain sample, for example. This index indicates the diversity inherent to the sample, and a higher value indicates a higher diversity of species within the sample. In this specification, alpha diversity is an index that indicates the number of species actually observed in the sample, where Observed_features is the number of species. Observed_features directly reflects the diversity of the bacterial flora. A high value of Observed_features means that many species are observed in the sample. Generally, a high value indicates a diverse ecosystem or a healthy microbial environment, while a low value indicates a hostile environment or effective sterilization results.

[0141] β diversity is an index that indicates the degree of difference in species diversity between two samples. This index expresses the difference in composition between samples as the distance between two points, and the greater the distance, the more different the bacterial flora compositions of the two samples. β diversity can be evaluated using Jaccard principal coordinate analysis, Unweighted_Unifrac principal coordinate analysis, and Weighted_Unifrac principal coordinate analysis. β diversity can be evaluated for similarities and differences between samples using Jaccard distance, Bray-Curtis distance, and phylogenetic-based UniFrac distance.

[0142] Jaccard principal coordinate analysis is a method that does not consider abundance but relies on the number of common species. This method calculates distance based on the proportion of species that are commonly present between two samples. The more common species there are, the shorter the distance between the samples will be, and conversely, the fewer common species there are, the longer the distance will be.

[0143] Unweighted_Unifrac principal coordinate analysis is a method that weights only the phylogenetic tree distance. This method evaluates the evolutionary distance between different bacterial species by calculating the phylogenetic distance between samples. Based on the phylogenetic tree, the length of the common evolutionary branch is compared, and the distance is calculated based on the proportion of shared evolutionary history.

[0144] Weighted_Unifrac principal coordinate analysis is a method that uses weighting based on both phylogenetic distance and abundance. This method simultaneously considers the phylogenetic distance between samples and the relative abundance of each species. This allows for the evaluation of differences in species richness, not just phylogenetic differences.

[0145] The bacterial flora improver can increase, for example, bacteria of bacterial genera that promote plant growth, such as the genera Lysobacter and Planomicrobium.

[0146] The bacterial flora improver can increase, for example, bacteria of bacterial genera that have organic matter decomposition activity, such as the genera Hydrogenophaga and Sphingopyxis.

[0147] The bacterial flora improver can increase bacteria of bacterial genus that have biological control activities such as antifungal activity. Examples of bacterial genus that have biological control activities such as antifungal activity include the genus Janthinobacterium.

[0148] The bacterial flora improver can reduce, for example, bacteria of a phytopathogenic genus, such as the genus Agrobacterium.

[0149] The microflora improver can increase bacteria of at least one bacterial genus selected from the group consisting of Lysobacter, Planomicrobium, Hydrogenophaga, Sphingopyxis, and Janthinobacterium. The microflora improver can decrease bacteria of the genus Agrobacterium.

[0150] Using a culture medium containing a microflora improver can facilitate improved plant growth. This is thought to be due to the fact that the addition of the microflora improver changes the soil environment, increasing beneficial bacterial groups (e.g., Lysobacter and Planomicrobium) and suppressing plant pathogens such as Agrobacterium. The microflora improver also enhances plant disease resistance, contributing to the reduction of Agrobacterium. The addition of silica may also favor the dominance of other bacterial genera (e.g., Lysobacter and Janthinobacterium, bacteria that contribute to biological control), resulting in the decline of pathogens such as Agrobacterium. Furthermore, the microflora improver may directly affect bacteria, or it may be indirectly affected by metabolites produced by silica acting on plants.

[0151] The bacterial flora of the culture medium can be improved using a bacterial flora improver. A method for improving the bacterial flora of the culture medium can include, for example, a step of blending the bacterial flora improver into soil. The description of the soil in the first embodiment applies to the soil.

[0152] A culture medium can be prepared by mixing a bacterial flora improver with soil. The method for mixing a bacterial flora improver with soil is the same as that for mixing a growth improver (silica particles) with soil in the first embodiment. The amount of bacterial flora improver mixed with soil (hereinafter also referred to as the mixing amount) may be, for example, 0.2 g to 1.5 g, preferably 0.2 g to 0.4 g, per 1 L of soil. The amount of bacterial flora improver contained in a culture medium containing a bacterial flora improver and soil may be more than 1.5 g per 1 L of soil, as long as the effects of the present disclosure are obtained. When the bacterial flora improver is sprayed on the surface of the soil, the bacterial flora improver should be applied to a surface of the culture medium with an area of ​​10 cm2 or more. ２ The silica particles can be sprayed in an amount such that the concentration of silica particles in 1 L of culture soil collected from the area where the silica particles are present is, for example, 0.2 g to 1.5 g, preferably 0.2 g to 0.4 g.

[0153] The compost may, for example, contain bacteria of a plant growth promoting genus, preferably at least one species of bacteria of a genus selected from the group consisting of Lysobacter and Planomicrobium.

[0154] The culture medium may contain, for example, bacteria of a bacterial genus having organic matter decomposition activity, and preferably contains at least one bacterium of a bacterial genus selected from the group consisting of the genera Hydrogenophaga and Sphingopyxis.

[0155] The compost may contain bacteria of a bacterial genus that has a biocontrol, e.g. antifungal, activity, and preferably contains bacteria of the genus Janthinobacterium.

[0156] The culture medium may contain, for example, bacteria of the genus Bacteria having phytopathogenicity, but preferably does not contain bacteria of the genus Bacteria having phytopathogenicity.The culture medium may contain, for example, bacteria of the genus Agrobacterium, but preferably does not contain bacteria of the genus Agrobacterium.

[0157] The culture medium may contain bacteria of at least one bacterial genus selected from the group consisting of Lysobacter, Planomicrobium, Hydrogenophaga, Sphingopyxis, Janthinobacterium, and Agrobacterium. From the viewpoint of plant growth, the culture medium preferably contains bacteria of at least one bacterial genus selected from the group consisting of Lysobacter, Planomicrobium, Hydrogenophaga, Sphingopyxis, and Janthinobacterium.

[0158] The content of ammonia nitrogen in the culture soil may be, for example, 3.3 mg / 100 g or more, or 3.7 mg / 100 g or more.

[0159] The content of nitrate nitrogen in the culture soil may be, for example, 0.2 mg / 100 g or more, 0.5 mg / 100 g or more, or 0.8 mg / 100 g or more.

[0160] The voltage generated by microbial power generation using culture soil can be 0.7 V or higher. If the voltage generated by microbial power generation in the culture soil is within the above range, microbial activity is vigorous, which is suitable for improving the diversity of the microbial flora. The voltage generated by microbial power generation can be measured as follows: The culture soil was placed in a measuring device (microbial fuel cell experimental device, product number: MudWatt, Kenis). Then, two weeks after placement, the voltage generated between the electrodes of the microbial power generation measuring device was measured. Note that the voltage generated by microbial power generation may be less than 0.7 V as long as it is within a range in which the effects of the present disclosure can be obtained.

[0161] The content of available silicon in the culture soil may be, for example, 164 mg / 100 g or less, or 161 mg / 100 g or less. Even if the culture soil has a relatively low content of available silicon within the above range, by using the culture soil containing the bacterial flora improver of the present disclosure, plant growth tends to be improved.

[0162] In the method for improving the bacterial flora of culture soil, the culture soil may have a multi-layer structure (soil layer / microbial flora improver layer / soil layer) in which the bacterial flora improver and soil are not completely mixed in the container or field, and the soil and bacterial flora improver may be mixed after the culture soil is prepared.

[0163] In order to facilitate the promotion of the growth of microorganisms living in the soil, the culture medium may contain microbial materials.

[0164] The bacterial flora improver is suitable for improving the diversity of bacterial flora in soil, and can also be used for bacterial culture and as a bacterial research reagent.

[0165] The present invention will be described in more detail below with reference to examples.

[0166] Example 1 Preparation of Silica Particles Silica particles were prepared according to the first production method described above. 2-Propanol was used as the solvent in the solvent introduction step S12. The sol-like silica particles obtained in the recovery step S19 were dried in the drying step S20, and then calcined at 400°C for 30 minutes in the calcination step S21 to obtain silica particles.

[0167] The silica particles were silica particles having particles (second particles) with a particle size of less than 100 nm on the surface of particles (first particles) with a particle size of 100 nm or more. The median particle size of the first particles in the particle size distribution of the first particles was 251 nm. Furthermore, the median particle size of the second particles in the particle size distribution of the second particles was 16 nm. The particle size distributions and median particle sizes of the first particles and second particles were determined as follows using SEM images of the silica particles at 50,000 and 200,000 magnifications. First, the particle size distribution was determined from the longest diameters measured for 25 or more first particles and second particles in each SEM image. Next, the median values ​​of the determined particle size distributions were determined to be the median particle sizes of the first particles and second particles.

[0168] The specific surface area of ​​the silica particles measured by the BET method is 163 m ２ The specific surface area of ​​the particles after drying and before calcination was 18.3 m2 as measured by the BET method. ２ / g.

[0169] The crystallinity of the silica particles was confirmed to be amorphous by X-ray diffraction (XRD). Scanning electron microscope (SEM) images of the silica particles are shown in Figures 3 and 4. A composite map (Si and N) of the silica particles obtained by energy dispersive X-ray spectroscopy (EDX) is shown in Figure 5. It was confirmed that the silica particles had multiple fine particles attached to the surface of the base particle. Furthermore, the results of component analysis of the silica particles are shown in Table 1. No heavy metals (arsenic, lead, cadmium, mercury, chromium, cyanide) were detected in the silica particles.

[0170] After immersing silica particles in a strong alkali for 5 days, the surfaces or cross sections of the silica particles removed from the alkali solution were examined using an SEM. The presence of multiple primary particles was confirmed in the first and second silica particles. The sizes of two of the multiple primary particles were measured in the SEM observation image and found to be 26 nm and 29 nm.

[0171]

[0172] Furthermore, an SEM image of the surface of silica particles (silica particles used in the evaluation of Example 6 described below) after immersion in water for one year is shown in Fig. 6. Although some areas where the second particles attached to the surfaces of the first particles had peeled off were observed, no change in the particle size of the first particles was observed, and no evidence of dissolution in water was observed.

[0173] [Culture soil preparation process] The silica particles obtained by the above-mentioned silica particle preparation were used as a growth improver. Soil (manufactured by Togawa Heiwa Noen Co., Ltd.) and a planter (depth 30 cm, width 63 cm, height 33 cm) were prepared. The soil used contained Akadama soil, Kanuma soil, compost, and coconut shell material (trade name "COCOYUKI" (registered trademark)). The soil was placed in the planter, and the container was tapped to remove air.

[0174] As shown in Figure 7, a linear depression was made in the center of the planter opening at a depth of 9 cm from the soil surface along the long side, and the growth improver was sprayed onto the surface of the bottom of the depression in an amount such that the mass ratio of soil to growth improver was soil:growth improver = 25 L:6.5 g, and the depression was then covered with soil to form a culture medium.

[0175] [Seeding Step] As shown in Figure 8, 16 holes were made in the culture soil to a depth of 2 cm from the surface. Two spinach seeds were placed in each hole, and soil was then placed on top of them.

[0176] [Growth process] Then, 1 L of pure water was sprayed on the surface of the culture soil. During the growth, 2 L of pure water was sprayed every day except on days when rainfall was confirmed or when the surface of the culture soil was confirmed to be wet. The yield and components of the harvested spinach were analyzed. The yield was measured as the fresh weight immediately after harvest. The components were analyzed by HPLC. The results are shown in Table 2 and Figure 9.

[0177] Comparative Example 1 Spinach was grown in the same manner as in Example 1, except that the soil was used as is without adding the growth improver in the culture soil preparation step. The results are shown in Table 2 and FIG.

[0178]

[0179] As shown in Table 2, Example 1, in which the growth improver was used, showed a significant increase in yield, and increased vitamin components and nitrate nitrogen compared to Comparative Example 1, in which the growth improver was not used. It can also be seen that the spinach of Example 1, shown on the right in Figure 9, grew larger overall than Comparative Example 1, shown on the left. It can also be seen that the plant growth improver of the present disclosure functions as a growth promoter. Furthermore, the silicon content of Example 1 was lower than that of Comparative Example 1. Because the plant growth improver of the present disclosure is insoluble, it can also be seen that it has little effect on the silicon content of plants.

[0180] Example 2 Komatsuna was grown in the same manner as in Example 1, except that komatsuna seeds were sown instead of spinach seeds. Figure 10 shows the growth status on the day the komatsuna seeds were sown (day 1), day 8, day 29, and day 38. Table 3 shows the results of analysis of the culture soil after growth (day 38). Figure 11 shows the results of analysis of the silicon content in the edible parts and roots of the komatsuna and the amount of available silicic acid in the culture soil.

[0181] Example 3 Komatsuna was grown in the same manner as in Example 1, except that industrial silica particles ("KE-S50" manufactured by Nippon Shokubai Co., Ltd., average particle size: 0.5 μm) were used instead of the growth improver used in Example 2. The results are shown in Figure 10. An SEM image of the industrial silica particles is shown in Figure 12. No fine particles were observed adhering to the surface of the industrial silica particles. The results of analysis of the silicon content in the edible parts and roots of the komatsuna and the amount of available silicic acid in the culture medium are shown in Figure 11. Furthermore, the results of analysis of the culture medium after growth (38 days) are shown in Table 3.

[0182] Comparative Example 2 Komatsuna was grown in the same manner as in Example 1, except that the soil was used as is without adding the growth improver in the culture medium preparation step. The results are shown in Figure 10. Furthermore, the analysis results of the silicon content in the edible parts and roots of the komatsuna and the available silicic acid content in the culture medium are shown in Figure 11. Furthermore, the analysis results of the culture medium after growth (38 days) are shown in Table 3.

[0183] Comparative Example 3 Komatsuna was grown in the same manner as in Example 1, except that a powdered silicate-based vitality agent (T.A. Silicate manufactured by Tera Actica) was used instead of the growth improver used in Example 2. The results are shown in Figure 10. An SEM image of the silicate-based vitality agent is shown in Figure 12. It was confirmed to be flaky. Figure 11 shows the results of analysis of the silicon content in the edible parts and roots of the komatsuna and the amount of available silica in the culture medium. Furthermore, the results of analysis of the culture medium after growth (38 days) are shown in Table 3.

[0184] Comparative Example 4 Komatsuna was grown in the same manner as in Example 1, except that nanosilica (CAB-O-SIL (registered trademark) M-5 manufactured by Cabot) was used instead of the growth improver used in Example 2. The results are shown in Figure 10. An SEM image of the nanosilica is shown in Figure 12. Fine particles of 10 to 20 nm were observed. The results of analysis of the silicon content in the edible parts and roots of the komatsuna and the amount of available silicic acid in the culture soil are shown in Figure 11. Furthermore, the results of analysis of the culture soil after growth (38 days) are shown in Table 3.

[0185]

[0186] The analytical items in Table 3 other than available silica were analyzed according to the method described in "Soil Environmental Analysis Methods" (Soil Environmental Analysis Methods Editorial Committee, 1997), and available silica was analyzed according to the method described in "Soil, Water Quality and Plant Body Analysis Methods" (Japan Soil Association, 2001).

[0187] 10, good growth results were obtained in Examples 2 and 3. It is clear that the growth improver of the present disclosure acts as a growth promoter.

[0188] In Example 2, almost no insect damage was observed compared to Example 3 and Comparative Examples 2 to 4. Furthermore, pest infestation was confirmed on the undersides of leaves in Example 3 and Comparative Examples 2 to 4, but no pests were observed in Example 2. It can be seen that the growth improver of the present disclosure functions as a pest repellent. This is presumed to be due to the following. As shown in Table 3, the culture media of Examples 2 and 3 contained relatively high amounts of ammonia nitrogen, while Example 2 contained relatively high amounts of nitrate nitrogen. Considering the nitrate nitrogen content of the silica particles used in Example 2, this is presumed to be due to microorganisms breaking down ammonia nitrogen so that the nitrate nitrogen could be absorbed by plants as nutrients. In other words, it is presumed that microbial activity was enhanced in Example 2. As a result, it can be presumed that the activity of microorganisms effective in pest repellency was also enhanced in Example 2, resulting in a pest repellent effect.

[0189] From Figure 11, it can be seen that the amount of silicon absorbed by komatsuna (edible part) tends to be low, and the effect of available silicic acid in the culture soil is not being obtained.

[0190] Example 4 Culture Soil Preparation Step The silica particles prepared in Example 1 were prepared as a growth improver. The soil used in Example 1 (manufactured by Togawa Heiwa Farm Co., Ltd.) was placed in a plug tray with 72 cells (4 cm long x 4 cm wide x 4.9 cm deep) and tapped to remove air.

[0191] A depression was made in the soil at a depth of 4 cm from the soil surface for each cell, and the growth improver was added so that the amount of growth improver was 0.020 g per depression, and then soil was placed on top of it.

[0192] [Seeding Step] Holes were made in each cell at a depth of 2 cm from the surface of the soil, and two spinach seeds were placed in each hole, which were then covered with soil.

[0193] [Growth Step] Then, 1 L of pure water was sprayed. Spinach was grown for 42 days. During growth, 100 mL of pure water was sprayed every day except on days when rainfall was confirmed or when the surface of the culture soil was confirmed to be wet. The number of germinated cells was counted on days 11, 22, and 42, and the ratio of the number of germinated cells to the total number of cells was defined as the germination rate. The results are shown in Table 4 and Figure 13.

[0194] Example 5 Spinach was grown in the same manner as in Example 4, except that salt water (salt concentration: 1% by mass) was sprayed instead of pure water in the growth step of Example 4. The results are shown in Table 4 and FIG.

[0195] Comparative Example 5 Spinach was grown in the same manner as in Example 4, except that the growth improver was not used in the culture soil preparation step. The results are shown in Table 4 and FIG.

[0196] Comparative Example 6 Spinach was grown in the same manner as in Example 5, except that the growth improver was not used in the culture soil preparation step. The results are shown in Table 4 and FIG.

[0197]

[0198] An improved germination rate was observed in Example 4 compared to Comparative Example 5. An improved germination rate was observed in Example 5 compared to Comparative Example 6. It can be seen that the growth improver of the present disclosure functions as a growth promoter. Furthermore, Comparative Example 6, in which salt water was sprayed, showed a lower germination rate than Comparative Example 5, in which pure water was sprayed, whereas Example 5, in which salt water was sprayed, and Example 4, in which pure water was sprayed, both had a germination rate of 100% on the 42nd day. Therefore, it can be seen that the growth improver of the present disclosure functions as a salt damage inhibitor.

[0199] Example 6: The soil preparation process and growth improver blending process were carried out in the same manner as in Example 1. Holes were then dug 15 cm deep from the soil surface, and cherry tomato seedlings were planted. The soil was then replaced in the holes and 1 L of water was sprinkled. 100 mL of pure water was sprayed daily, and during growth, 2 to 6 L of water was sprayed daily except on days when rainfall was confirmed or when the surface of the potting soil was confirmed to be moist. After 38 days, fertilizer (2 L of a 500x diluted solution of Biol and 2 L of a 1000x diluted solution of Arafesta) was sprayed, and the cherry tomatoes were grown. The results are shown in Figure 14. The potassium content of the cherry tomatoes was measured using atomic absorption spectrometry. The components of the cherry tomatoes were analyzed by high-performance liquid chromatography. The average hardness of the cherry tomatoes was determined by measuring the hardness of the cherry tomatoes 10 times using a creep meter and averaging the results. The results are shown in Table 5. Furthermore, the sugar content (Refbrix) of cherry tomatoes was measured using a refractometer. The results are shown in Table 6 and Figure 16 . Taste evaluation was performed according to the following procedure. First, an equal volume of water was added to the crushed sample, and the mixture was stirred in a food mill for 1 minute and filtered through filter paper to prepare a test solution. Next, the taste of the sample (initial taste: sourness, bitterness, astringency, umami, and saltiness; aftertaste: bitterness, astringency, and umami richness) was analyzed at room temperature using a taste recognition device (TS-5000Z: Intelligent Sensor Technology Co., Ltd.) equipped with five taste sensors (CA0, C00, AE1, AAE, CT0). The potential output values ​​from the five taste sensors were converted to each taste category, and the difference between Example 1 and Comparative Example 1 was calculated, with Comparative Example 8 set as the reference (0). A difference of 1.0 was set as the value at which humans can detect a difference in taste. The results are shown in Table 7. The component analysis, firmness measurement, sugar content analysis and taste evaluation of the cherry tomatoes were carried out immediately after harvesting at each stage where growth was complete to avoid any changes over time from harvesting.

[0200] Comparative Example 7 Cherry tomatoes were grown in the same manner as in Example 6, except that the growth improver blending step was not carried out. The results are shown in Figure 14. The component analysis results, sugar content analysis results, and taste evaluation results of the cherry tomatoes are shown in Tables 5, 6, and 7, respectively.

[0201]

[0202]

[0203]

[0204] 14 and 15 show that a large amount of pests (scale insects) emerged in Comparative Example 7, whereas almost no pests emerged in Example 6. It can be seen that the growth improver of the present disclosure functions as a pest repellent.

[0205] As can be seen from Table 5, in Example 6, the mineral component (potassium) and vitamin component (vitamin A and vitamin C) were increased compared to Comparative Example 7. It is clear that the growth improver of the present disclosure functions as a growth promoter. Furthermore, as can be seen from Tables 5, 6, 7 and FIG. 16, in Example 6, the acid component (citric acid) was reduced, the sugar content increased, and the sourness was reduced. It is clear that the growth improver of the present disclosure functions as a taste improver.

[0206] Example 7: 270 g of soil was placed in a glass pot, and 0.54 g (0.2 wt%) of a growth improver was sprinkled on the soil surface. After lightly mixing only the soil surface, the soil was leveled, and 110 cc of water was slowly poured into the glass pot using a dropper, along the wall of the pot. Aquatic plant (mini glossostigma) seeds were sown on top of the soil, ensuring that they did not overlap. The soil was misted to prevent the surface from drying out until the plants germinated. After the plants germinated, water was slowly poured into the glass pot to a depth of half. On the 29th day, half of the water in the glass pot was replaced with fresh water. The growth results are shown in Figure 17. Several aquatic plants were pulled out and their growth was monitored. The results are shown in Figure 18. After the water was replaced, the degree of plant removal was checked. The results are shown in Figure 19.

[0207] Comparative Example 8 Aquatic plants were grown in the same manner as in Example 7, except that the growth improver was not applied. The growth of the aquatic plants and the degree to which the plants fell out after the water change were checked. The results are shown in Figures 17, 18 and 19.

[0208] 17 and 18 confirm that root growth was better in Example 7 than in Comparative Example 8, and that the roots had a greater ability to retain soil. Furthermore, as shown in Figure 19, in Example 7, after water exchange, the roots in Comparative Example 8 were observed to have lifted up from the soil, whereas in Example 7 the roots did not lift up from the soil and rooting was improved. Therefore, it can be seen that the growth improver of the present disclosure functions as a rooting improver.

[0209] Example 8 First, to investigate the effects of continuous crop damage, soil previously collected from yam plants was prepared. This soil was mixed with a growth improver at a mass ratio of soil:growth improver = 25 L:6.5 g to prepare a potting soil. The potting soil was placed in a clever pipe measuring 105 cm in length. A hole 30-40 cm deep and 25 cm wide was dug in the field, and the clever pipe was buried therein.

[0210] As shown in Figure 20, a seed yam (Dioscorea japonica) 202 was planted in the tray of a clever pipe 201 buried in the soil, and a marker support 203 was erected. After about six months, the clever pipe 201 was removed, and new potatoes 204 that had grown inside the clever pipe 201 were harvested.

[0211] The total length of the harvested new potatoes was measured with a tape measure, and the shortest distance between the tips of the new potatoes was measured to evaluate their straightness. The longer the shortest distance, the better the straightness. The results are shown in Table 8.

[0212] Comparative Example 9 Except for not adding the growth improver to the soil, yam was grown in the same manner as in Example 8. The results are shown in Table 8.

[0213]

[0214] As shown in Table 8, Example 8 showed better straightness than Comparative Example 9. It can be seen that the growth improver of the present disclosure functions as a growth direction regulator. Furthermore, in Example 8, growth was good and no continuous crop damage was observed. Therefore, it can be seen that the growth improver of the present disclosure functions as a growth promoter.

[0215] Example 9: A growth improver was applied to the surface of the soil in the field to a depth of 1 m. ２After applying 5 to 100 g of silica particles per 1000 m² of soil, dent corn seeds were sown. During growth, 1 L of pure water was applied daily except on days when rainfall was confirmed or when the surface of the soil was confirmed to be moist. The yield of the dent corn and the presence or absence of pest damage are shown in Table 9.

[0216] Comparative Example 10 Dent corn was grown in the same manner as in Example 9, except that the growth improver was not sprayed. Table 9 shows the yield and the presence or absence of pest damage.

[0217]

[0218] In Example 9, the yield of dent corn was higher than in Comparative Example 10. This indicates that the growth improver of the present disclosure functions as a growth direction regulator. Furthermore, no pest damage was observed in Example 9. This indicates that the growth improver of the present disclosure functions as a pest repellent.

[0219] Example 10: 10 mL of rice husk biochar was placed in a disposable cup. Next, the solution containing sol-like silica particles from recovery step S19 in the preparation of silica particles in Example 1 was thoroughly mixed using the suction nozzle of a pump and poured into a separate disposable cup at least 300 mL. After thorough mixing until the solution became opaque, it was poured into the disposable cup containing the biochar and diluted to 100 mL. The mixture was left overnight in an organic fume hood until completely dried. It was then placed in a crucible (with a lid) and fired at 400°C for 30 minutes. This produced biochar supporting silica particles. A photograph of the appearance of the biochar after treatment, along with a photograph of the biochar before treatment, is shown in Figure 21 . SEM images of the surfaces of the biochar before and after treatment (observed at 500x magnification for the pre-treatment example in Example 11 and 2000x for the other examples) are shown in Figure 22 . FIG. 23 shows SEM observation images (left column, 2000x magnification) and FE-SEM observation images (right column, 100,000x magnification) of the surface of the biochar after the treatment in FIG.

[0220] Example 11 Biochar supporting silica particles was produced in the same manner as in Example 10, except that the type of biochar was changed to bamboo and the biochar was crushed into small pieces before being placed in a disposable cup. The surface observation results are shown in Figures 21, 22, and 23.

[0221] Example 12 Biochar supporting silica particles was produced in the same manner as in Example 10, except that the type of biochar was changed to wood and the biochar was crushed into small pieces before being placed in a disposable cup. The surface observation results are shown in Figures 21, 22, and 23.

[0222] As shown in Figures 21 to 23, it was confirmed that silica particles were supported on the surface of the biochar. It was also confirmed that the silica particles had a plurality of second particles attached to the surface of the first particle. By using the biochar supported with silica particles of the present disclosure for plant growth, CO ２ It can be seen that this can easily absorb water and improve plant growth.

[0223] Examples 13 to 20 A plant cultivation kit was prepared containing the silica particles obtained in the preparation of silica particles in Example 1 and soil (manufactured by Togawa Heiwa Noen Co., Ltd.). The soil used contained Akadama soil, Kanuma soil, compost, and coconut shell material (trade name "Cocoyuki").

[0224] Furthermore, the influence of bacteria in the soil is thought to be a factor in the successful growth of plants even with minimal moisture content in the culture medium. To investigate this, sterilized soil was prepared. The sterilized soil was prepared by irradiating the soil prepared above with 30 kGy gamma rays. A bioburden measurement test was conducted according to the following procedure, and the bacterial count in the sterilized soil was confirmed to be 0 cfu / g. [Bioburden Test] (1) A suspension of the sterilized soil and its diluted solution were smeared onto a plate medium, and aerobic and anaerobic cultures were performed. (2) 1 g of the sample was weighed and suspended in a Falcon tube containing 10 mL of PTS recovery solution to prepare a stock solution. (3) 1 mL of the stock solution was taken and diluted 10-fold with 9 mL of PTS recovery solution. This process was repeated six times. (4) 100 μL each from the 100-fold, 10,000-fold, and 1,000,000-fold diluted solutions was taken and smeared on an SCDA plate medium. After culturing aerobic bacteria for 7 days, the aerobic bacterial count was measured. (5) 100 μL each from the original solution and the 100-fold diluted solution was taken and smeared on an SCDA plate medium. After culturing anaerobic bacteria for 7 days, the anaerobic bacterial count was measured.

[0225] A total of 25 L of sterilized soil and non-sterilized soil were placed in a planter outdoors, with the mass ratio shown in Table 10. After tapping the container to remove air, a linear depression was created in the center of the planter, 9 cm deep from the soil surface, along the long side of the opening, as in Example 1 (FIG. 7). A soil sensor capable of measuring temperature and moisture content was installed in the culture medium, and silica particles were then spread on the surface of the bottom of the depression so that the mass ratio of soil to silica particles (soil:silica particles) was 25 L:6.5 g. This was then covered with soil to prepare the culture medium.

[0226] Sixteen holes were made in the same potting soil as in Figure 8, each 2 cm deep from the surface. Two seeds of the plants shown in Table 10 were placed in each hole, and soil was then placed over them.

[0227] After that, 1 L of pure water was sprayed on the surface of the culture soil. The planter was covered with a transparent polyethylene sheet. The sheet was left open when there was no snowfall or strong winds, and the planter was covered with the sheet in other weather conditions. Growth was continued for 3.5 months. During the growth period, no water was sprayed except for a spray on the soil surface 8 days after sowing. Figures 24 and 25 show the growth conditions of Example 13 (100% sterilized soil) and Example 16 (0% sterilized soil), respectively. Measurement results of fresh weight (yield) after harvest are shown in Table 11, Figure 27 (komatsuna), and Figure 28 (spinach). The right-hand vertical axes of Figures 27 and 28 represent the mean and standard deviation (average value line graph with standard deviation) of the komatsuna yield (g) and spinach yield (g) divided by the number of harvested bunches, respectively, and the left-hand vertical axis represents the total yield (bar graph). 29 and 30 show the temperature and moisture content in the culture soil measured by the soil sensor during the growing period in Examples 13, 15 and 16.

[0228] Comparative Examples 11 to 18 Plants were grown in the same manner as in Examples 13 to 20, except that silica particles were not added to the sterilized and non-sterilized soil. The growth condition of Comparative Example 11 (100% sterilized soil) is shown in Figure 26. The results of measuring the fresh weight (yield) after harvest are shown in Figure 27 (Komatsuna) and Figure 28 (Spinach). Furthermore, the temperature and moisture content in the culture soil measured by a soil sensor during the growth period of Comparative Examples 11, 13, and 14 are shown in Figures 29 and 30.

[0229]

[0230] 27 and 28 show that in Examples 13, 14, and 16 to 20, which used culture soil containing silica particles, the yield was higher than that of the corresponding Comparative Examples 11, 12, and 14 to 18. It can be seen that when culture soil containing silica particles is used, the yield tends to be higher than when culture soil without silica particles is used, even if sufficient water is not supplied.

[0231] As shown in FIG. 29, no significant difference was observed in the temperature in the culture medium regardless of whether or not silica particles were added to the culture medium.

[0232] As shown in Figure 30, variations in the moisture content of the culture medium occurred despite the same growth conditions except for the presence or absence of silica particles and the proportion of sterilized soil. In a comparison (d1) between Example 13 and Comparative Example 11, Example 13 had less moisture than Comparative Example 11. In a comparison (d2) between Example 15 and Comparative Example 13, Example 15 had less moisture than Comparative Example 13. On the other hand, in a comparison (d3) between Example 16 and Comparative Example 14, Example 16 had a higher moisture content in the culture medium during the growth period than Comparative Example 14. These results demonstrate that when silica particles are added, plants can grow regardless of the moisture content in the culture medium.

[0233] 28, the effect of the plant cultivation kit of the present disclosure on the growth of spinach tended to be greater as the proportion of sterilized soil increased. This is presumably because the greater the proportion of sterilized soil, the greater the room for bacterial growth in the culture medium, and the silica particles allowed bacteria that are beneficial to plant growth to grow in relatively large numbers in the culture medium.

[0234] From the above, it can be seen that the reason plants can grow even without providing sufficient moisture to the culture soil is because the silica particles allow bacteria that are beneficial to plant growth to multiply, and as a result, plants can grow regardless of the amount of moisture in the culture soil.

[0235] In Examples 13 to 20 and Comparative Examples 11 to 18, bacterial flora analysis was performed on samples taken from the culture medium at the start of growth (germination), the culture medium on the periphery of the planter at harvest, and the culture medium attached to the plant roots (rhizosphere). The bacterial flora analysis was performed according to the following procedure.

[0236] 1) Plant harvest and soil collection: The soil surface of the komatsuna and spinach was collected, and the komatsuna and spinach were harvested. Some of the soil adhering to the komatsuna and spinach was removed, and the rhizosphere (the soil space influenced by plant root secretions and soil bacteria) was collected with a brush. The collected soil was spread on aluminum foil, and 40 g of the soil alone, avoiding the fertilizer (yellow and white) and wood chips, was dispensed into a tube containing ceramic beads from a DNA extraction kit.

[0237] 2) The DNA extraction beads were mixed with the soil and cell lysis solution and then vigorously shaken. This caused the beads to detach microorganisms (bacteria) adhering to the soil, lyse the microorganisms, and release their DNA.

[0238] 3) Quantification of total DNA The amount of DNA contained in the solution obtained in the DNA extraction process (total DNA solution) was confirmed. A fluorescent dye that specifically binds to DNA was added, and the amount of DNA was quantified by measuring the fluorescence intensity. The experiment was performed using 3 μL of total DNA and 197 μL of staining solution, and it was confirmed that approximately 40 ng / μL had been extracted. The amount of reagents for the first PCR was determined based on the confirmed concentration.

[0239] 4) 1st PCR PCR was carried out by performing one cycle of thermal denaturation, annealing and extension reaction in this order.

[0240] 5) DNA Purification After removing unnecessary substances other than DNA (such as enzymes used in PCR) using magnetic beads, the magnetic beads and a solution for separating DNA were added.

[0241] 6) Gel preparation and electrophoresis A 2% agarose gel was prepared, and the agarose was dissolved in hot water and cooled to solidify. Electrophoresis confirmed that the target DNA region had been amplified by 1st-PCR.

[0242] 7) 2nd PCR: The same procedure as 1st PCR was performed, and an adapter sequence was added to the amplified target DNA region (creating a library). By adding the adapter sequence to the end of the DNA in each amplified sample, DNA amplification and sequence analysis were performed using a next-generation sequencer (a machine that analyzes DNA sequences). The adapter sequence contains a unique sequence that can distinguish sample numbers.

[0243] 8) Sequencing: First, the library concentration was measured using a Synergy H1 (Agilent Technologies) and a QuantiFluor dsDNA System. Next, the quality of the prepared library was confirmed using a Fragment Analyzer and a dsDNA 915 Reagent Kit (Agilent Technologies). Then, sequencing was performed using a MiSeq system and MiSeq Reagent Kit v3 (Illumina) at 2x300 bp.

[0244] 9) 16S rRNA data analysis First, reads that matched the primer sequence were extracted using FASTX-Toolkit (ver. 0.0.14). Next, the reads were combined using the paired-end read combination script FLASH (ver. 1.2.11). After removing chimeric sequences and noise sequences using Qiime2 (ver. 2024.2), a representative sequence was obtained, and the feature-classifier plugin was used to compare the obtained representative sequence with 97% OTU of Greengene (ver. 13_8) to estimate the phylogeny. The phylogenetic tree was created using the Alignment and phylogeny plugins.

[0245] Figure 31 shows a bar chart for each sample showing the abundance of each bacterial species collected from each sample. Figure 32 shows a bar chart in which the abundance of bacteria A (genus Rhodanobacter) in Figure 31 is rearranged from left to right in ascending order. In Figures 31 and 32, the abbreviations have the following meanings: An odd number at the beginning indicates a culture medium containing silica particles; an even number indicates a culture medium without silica particles. Furthermore, when the first number is 1 or 2, the ratio of sterilized soil is 100%, when it is 3 or 4, the ratio of sterilized soil is 76%, when it is 5 or 6, the ratio of sterilized soil is 50%, and when it is 7 or 8, the ratio of sterilized soil is 0% (100% non-sterilized soil). Furthermore, S and O represent the culture medium at the start of growth (germination) and the culture medium around the planter at harvest, respectively. K and H represent komatsuna and spinach. The numbers at the end indicate the level of samples taken from the culture medium (n=3).

[0246] As a result of the α diversity analysis, the rarefaction curve of Observed_features is shown in Figure 33. Also, a box plot of Observed_features is shown in Figure 34.

[0247] Principal coordinate analysis (PCoA) was used to visualize beta diversity. In PCoA, each plot represents one sample, and the closer the plots are to each other, the more similar the bacterial flora composition between the samples is. Figure 35 shows the results of Jaccard principal coordinate analysis. Figure 36 shows the results of Unweighted_Unifrac principal coordinate analysis. Figure 37 shows the results of Weighted_Unifrac principal coordinate analysis.

[0248] (Bar chart analysis) Figure 31 shows bar charts sorted by sample number. Tests were performed at each level (n = 3), and equivalent bacterial flora bar charts were obtained at the same conditions. This confirmed the reproducibility of the experiment.

[0249] Figure 32 shows a bar chart sorted from left to right by the abundance of bacteria A. The sample was divided into three sections (initial bacterial flora, 100% sterilized soil, and a group containing non-sterilized soil), each with a similar bacterial flora pattern. The "initial bacterial flora" section had a high bacterial flora diversity, with various bacterial species evenly distributed. The "100% sterilized soil" section showed significant changes in the composition of the bacterial flora over the period from sterilization to plant cultivation. Furthermore, the dominance of several specific bacterial species (e.g., bacteria B [Pseudomonas genus] and bacteria C [Flavobacterium genus]) increased, resulting in a decrease in bacterial flora diversity. The "group containing non-sterilized soil" section showed an increase in bacterial flora diversity. Furthermore, the plant-pathogenic genus Agrobacterium was detected as the top bacterial species when silica particles were not added, but was less likely to be detected when silica particles were added to 100% sterilized soil or non-sterilized soil. Furthermore, the addition of silica particles was confirmed to increase the number of bacteria in the genera Lysobacter, Planomicrobium, Hydrogenophaga, Sphingopyxis, and Janthinobacterium. These analytical results demonstrate that soil sterilization and subsequent plant cultivation have a significant impact on the bacterial flora.

[0250] (Analysis of α diversity) Figure 33 shows the rarefaction curve of bacterial flora diversity (Observed_features). Since the gene reading was performed to the point where the number of detected bacterial species did not change even when the number of gene readings was increased, it was confirmed that the amount of data to be analyzed in the analysis of α diversity was sufficient.

[0251] In Figure 34, the box plots show the distribution of bacterial flora diversity (Observed_features) for each sample. The vertical axis shows the number of observed species, which is used to evaluate bacterial flora diversity. It can be seen that bacterial flora diversity was significantly reduced at the 100% sterilized soil level. It was also confirmed that the addition of silica particles at the 100% sterilized soil level increased the number of bacterial species, tending to restore diversity. On the other hand, no effect of silica particles on diversity was observed at the 76% sterilized soil, 50% sterilized soil, and non-sterilized soil levels.

[0252] (Analysis of β diversity) (1) Jaccard principal coordinate analysis Jaccard principal coordinate analysis is a method that does not consider the abundance of each species, but rather depends on the number of common species. The Jaccard distance used in Jaccard principal coordinate analysis is expressed such that the greater the number of species commonly present between samples, the shorter the distance between samples, and conversely, the fewer common species, the longer the distance.

[0253] In Figure 35, the bacterial flora at the start of the experiment was separated into coordinates with distances corresponding to the degree of mixing of sterilized and non-sterilized soil. Regarding the soil bacterial flora at harvest, the specimen with 100% sterilized soil was shown to have the most significantly different bacterial flora from the start compared to the specimens harvested under the other conditions. Furthermore, clusters (i.e., bacterial flora with different compositions) were formed and separated at different coordinates depending on whether or not silica particles were added. These results indicate that soil that was 100% sterilized soil at the start formed unique bacterial flora at harvest, and that the presence or absence of silica particles significantly affected the formation of the bacterial flora.

[0254] On the other hand, just like with 100% sterilized soil, changes in the bacterial flora from the start of the experiment to harvest were observed in non-sterilized soil, and different bacterial flora compositions were formed depending on whether or not silica particles were added at that time, but the differences were closer than in the case of 100% sterilized soil. In the cases of 76% and 50% sterilized soil, the bacterial flora coordinates at the start and at harvest were located between those of 100% sterilized soil and non-sterilized soil, but the differences due to the presence or absence of added silica particles were small.

[0255] It can be seen that soil that was 100% sterilized at the start had formed its own unique bacterial flora by the time plant cultivation was completed, and that the bacterial flora formation was significantly affected by the presence or absence of silica particles added. Considering that the effect of the addition of silica on plant growth was greatest in 100% sterilized soil, was equal to or lower in non-sterilized soil than in 100% sterilized soil, and was far lower in 76% and 50% sterilized soil than non-sterilized soil (Examples 13-20, Comparative Examples 11-18), it can be seen that differences in bacterial flora reflect differences in plant growth.

[0256] (2) Unweighted Unifrac Principal Coordinate Analysis Unweighted Unifrac principal coordinate analysis is a method for evaluating the evolutionary distance between different bacterial species by calculating the phylogenetic distance (UniFrac distance) between samples and weighting them only by the phylogenetic tree distance.

[0257] Figure 36 shows that only the 100% sterilized soil level was significantly different from the coordinate range of the other samples. Furthermore, the 76% sterilized soil, 50% sterilized soil, and non-sterilized soil levels showed only small changes in the bacterial flora between the start and end of plant cultivation. These results suggest that the 100% sterilized soil level has bacterial flora that are phylogenetically very different. Furthermore, the 76% sterilized soil, 50% sterilized soil, and non-sterilized soil levels have bacterial flora composed of phylogenetically similar bacterial species.

[0258] (3) Weighted Unifrac Principal Coordinate Analysis Weighted Unifrac Principal Coordinate Analysis is a method of analysis that uses the phylogenetic distance between samples (UniFrac distance) and the distance indicating species abundance (Bray-Curtis distance) to weight both the phylogenetic tree distance and the abundance rate, and takes into account not only phylogenetic differences but also differences in species abundance in the evaluation.

[0259] As shown in Figure 37, differences were observed in the bacterial flora after plant cultivation in 100% sterilized soil depending on whether silica was added or not. Differences were also observed in the bacterial flora of the rhizosphere soil between cultivated plants. In the 76%, 50% sterilized, and non-sterilized soil levels, the bacterial flora at the start and end of plant cultivation were separated by Weighted Unifrac principal coordinate analysis, but the distances were very close, and there was little difference between the presence and absence of silica particles.

[0260] The 100% sterilized soil level had a microbial flora composed of significantly different species compared to the other conditions, and these differences were also confirmed to be significantly different in terms of phylogenetic development from the microbial flora under other conditions. This suggests that the soil, which had lost its microbial flora due to sterilization, acquired a new microbial flora and changed uniquely during the plant cultivation process. Furthermore, it was suggested that the presence of silica particles significantly affected the formation of the microbial flora during this process. Furthermore, the difference in the microbial flora with the addition of silica particles was significant between the 100% sterilized soil and the non-sterilized soil levels, and the difference in plant growth promotion effect was also significant at these levels. Conversely, when the 76% and 50% sterilized soil levels, where the two were mixed to start the experiment, the difference in both the microbial flora and plant growth promotion between the presence and absence of silica particles was small. This suggests that the effect of silica particles on the diversity of the microbial flora is strongly correlated with the plant growth promotion effect.

[0261] It was found that the bacterial flora improver of the present disclosure can directly or indirectly affect the formation of bacterial flora in soil during plant cultivation, and it was also suggested that the formation of bacterial flora may be correlated with the plant growth improvement effect.

[0262] In the above-described embodiments, configurations that can be combined may be combined with each other.

[0263] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0264] It will be appreciated by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0265] (Item 1) A plant growth improver according to an embodiment of the present disclosure includes silica particles, wherein the median particle size of the silica particles having a particle size of 100 nm or more is 120 nm or more and 800 nm or less in the particle size distribution of the particles having a particle size of 100 nm or more.

[0266] (Item 2) In the plant growth improver according to item 1, the content of ammonia nitrogen in the silica particles is 2.0 mg / 100 g or less.

[0267] (Item 3) The plant growth improver according to item 1 or 2 has an available silicic acid content in the silica particles of 30 mg / 100 g or less.

[0268] (Item 4) In the plant growth improver according to any one of items 1 to 3, the content of nitrate nitrogen in the silica particles is less than 0.1 mg / 100 g.

[0269] (Item 5) In the plant growth improver according to any one of items 1 to 4, the CEC of the silica particles is 1.0 meq / 100 g or less.

[0270] (Item 6) In the plant growth improver according to any one of items 1 to 5, the plant is at least one plant selected from the group consisting of Brassicaceae, Amaranthaceae, Solanaceae, Dioscoreaceae, Dioscoreaceae, Utriculariaceae, and Poaceae.

[0271] (Item 7) In the plant growth improver according to any one of Items 1 to 5, the plant is at least one selected from the group consisting of Japanese mustard spinach, spinach, cherry tomatoes, yams, aquatic plants, and dent corn.

[0272] (Item 8) In the plant growth improver according to any one of items 1 to 5, the plant is a plant with a low silicon absorption amount.

[0273] (Item 9) The plant growth improver according to any one of items 1 to 8 is at least one selected from the group consisting of growth promoters, salt damage inhibitors, taste improvers, pest repellents, root improvement agents, and growth direction regulators.

[0274] (Item 10) The plant growth improver according to any one of items 1 to 5 is a growth promoter for at least one plant selected from the group consisting of spinach, cherry tomatoes, yams, and dent corn.

[0275] (Item 11) The plant growth improver according to any one of items 1 to 5 is an agent for preventing salt damage in spinach.

[0276] (Item 12) The plant growth improver according to any one of items 1 to 5 is an agent for improving the taste of cherry tomatoes.

[0277] (Item 13) The plant growth improver according to any one of items 1 to 5 is a pest repellent for cherry tomatoes, Japanese mustard spinach, and dent corn.

[0278] (Item 14) The plant growth improver according to any one of items 1 to 5 is an agent for improving root growth of aquatic plants.

[0279] (Item 15) The plant growth improver according to any one of items 1 to 5 is a growth direction regulator for yams.

[0280] (Item 16) A method for growing plants using the growth improver according to any one of Items 1 to 15, the method comprising a culture soil preparation step of preparing culture soil by mixing the growth improver with soil.

[0281] (Item 17) In the method for growing a plant according to Item 16, the content of ammonia nitrogen in the culture soil is 3.3 mg / 100 g or more.

[0282] (Item 18) In the method for growing a plant according to item 16 or 17, the content of nitrate nitrogen in the culture soil is 0.2 mg / 100 g or more.

[0283] (Item 19) In the method for growing a plant according to any one of Items 16 to 18, the content of available silicon in the culture soil is 164 mg / 100 g or less.

[0284] (Item 20) Another embodiment of the biochar of the present disclosure is biochar carrying silica particles, wherein the median particle size of the silica particles having a particle size of 100 nm or more is 120 nm or more and 800 nm or less in the particle size distribution of the particles having a particle size of 100 nm or more.

[0285] (Item 21) The biochar according to Item 20 is a carbonized material of at least one material selected from the group consisting of rice husks, bamboo, and wood.

[0286] (Item 22) A plant cultivation kit according to another embodiment of the present disclosure includes a container, a cover for covering the container, and a culture medium. The culture medium includes silica particles and soil. The silica particles having a particle size of 100 nm or more have a median particle size of 120 nm or more and 800 nm or less in the particle size distribution of the particles having a particle size of 100 nm or more.

[0287] (Item 23) In the plant cultivation kit according to item 22, the culture soil further contains a water-retaining polymer.

[0288] (Item 24) The plant cultivation kit according to item 22 or 23 further includes a soil sensor capable of measuring temperature and water content.

[0289] (Item 25) A bacterial flora improver according to yet another embodiment of the present disclosure includes silica particles, wherein the median particle size of the silica particles having a particle size of 100 nm or more is 120 nm or more and 800 nm or less in the particle size distribution of particles having a particle size of 100 nm or more.

[0290] (Item 26) In the bacterial flora improver according to item 25, the bacterial flora is a soil bacterial flora.

[0291] (Item 27) The bacterial flora improver according to item 25 or 26 improves the diversity of bacterial flora.

[0292] (Item 28) The bacterial flora improver according to any one of items 25 to 27 increases bacteria of at least one bacterial genus selected from the group consisting of the genera Lysobacter, Planomicrobium, Hydrogenophaga, Sphingopyxis, and Janthinobacterium.

[0293] (Item 29) The bacterial flora improver according to any one of Items 25 to 28 reduces bacteria of the genus Agrobacterium.

[0294] (Item 30) A method for improving a bacterial flora, comprising the step of incorporating the bacterial flora improver according to any one of Items 25 to 29 into soil.

[0295] (Item 31) A culture soil containing the bacterial flora improver according to any one of Items 25 to 29.

[0296] 100 Silica particles, 101 First particles, 102 Second particles, 103 Voids, 201 Clever pipe, 202 Seed potatoes, 203 Supports, 204 New potatoes.

Claims

1. A plant growth improver comprising silica particles, wherein the median particle size of the silica particles having a particle size of 100 nm or more is 120 nm or more and 800 nm or less in the particle size distribution of the particles having a particle size of 100 nm or more.

2. The plant growth improver according to claim 1, wherein the content of ammonia nitrogen in the silica particles is 2.0 mg / 100 g or less.

3. A plant growth improver according to claim 1 or 2, wherein the content of available silicic acid in the silica particles is 30 mg / 100 g or less.

4. A plant growth improver according to any one of claims 1 to 3, wherein the content of nitrate nitrogen in the silica particles is less than 0.1 mg / 100 g.

5. A plant growth improver according to any one of claims 1 to 4, wherein the silica particles have a CEC of 1.0 meq / 100 g or less.

6. A plant growth improver according to any one of claims 1 to 5, wherein the plant is at least one plant selected from the group consisting of Brassicaceae, Amaranthaceae, Solanaceae, Dioscoreaceae, Scutellariae, Utriculariaceae and Poaceae.

7. A plant growth improver according to any one of claims 1 to 5, wherein the plant is at least one selected from the group consisting of komatsuna, spinach, cherry tomatoes, yams, aquatic plants and dent corn.

8. A plant growth improver according to any one of claims 1 to 5, wherein the plant is a plant with a low silicon absorption rate.

9. The plant growth improver according to any one of claims 1 to 8, which is at least one selected from the group consisting of growth promoters, salt damage prevention agents, taste improvers, pest repellents, root improvement agents, and growth direction regulators.

10. The plant growth improver according to any one of claims 1 to 5, which is a growth promoter for at least one plant selected from the group consisting of spinach, cherry tomatoes, yams, and dent corn.

11. The plant growth improver according to any one of claims 1 to 5, which is an agent for preventing salt damage in spinach.

12. The plant growth improver according to any one of claims 1 to 5, which is a taste improver for cherry tomatoes.

13. The plant growth improver according to any one of claims 1 to 5, which is a pest repellent for cherry tomatoes, Japanese mustard spinach, and dent corn.

14. The plant growth improver according to any one of claims 1 to 5, which is a root improver for aquatic plants.

15. A plant growth improver according to any one of claims 1 to 5, which is a growth direction regulator for yams.

16. A method for growing plants using the growth improver according to any one of claims 1 to 15, comprising a culture soil preparation step of preparing culture soil by mixing the growth improver with soil.

17. The method for growing plants according to claim 16, wherein the content of ammonia nitrogen in the culture soil is 3.3 mg / 100 g or more.

18. A method for growing plants according to claim 16 or 17, wherein the content of nitrate nitrogen in the culture soil is 0.2 mg / 100 g or more.

19. A method for growing plants according to any one of claims 16 to 18, wherein the content of available silicon in the culture soil is 164 mg / 100 g or less.

20. Biochar carrying silica particles, wherein the median particle size of the silica particles having a particle size of 100 nm or more is 120 nm or more and 800 nm or less in the particle size distribution of the particles having a particle size of 100 nm or more.

21. The biochar of claim 20, wherein the biochar is a carbonized material of at least one material selected from the group consisting of rice husk, bamboo, and wood.

22. A plant cultivation kit comprising a container, a cover for covering the container, and culture soil, wherein the culture soil contains silica particles and soil, and wherein the median particle size of the silica particles having a particle size of 100 nm or more is 120 nm or more and 800 nm or less in the particle size distribution of the particles having a particle size of 100 nm or more.

23. The plant cultivation kit according to claim 22, wherein the potting soil further contains a water-retaining polymer.

24. The plant cultivation kit according to claim 22 or 23, further comprising a soil sensor capable of measuring temperature and moisture content.

25. A bacterial flora improver containing silica particles, wherein the median particle size of the silica particles having a particle size of 100 nm or more is 120 nm or more and 800 nm or less in the particle size distribution of the particles having a particle size of 100 nm or more.

26. The bacterial flora improver according to claim 25, wherein the bacterial flora is a soil bacterial flora.

27. A bacterial flora improver according to claim 25 or 26, which improves the diversity of the bacterial flora.

28. The bacterial flora improver according to any one of claims 25 to 27, which increases bacteria of at least one bacterial genus selected from the group consisting of Lysobacter, Planomicrobium, Hydrogenophaga, Sphingopyxis, and Janthinobacterium.

29. A bacterial flora improver according to any one of claims 25 to 28, which reduces bacteria of the genus Agrobacterium.

30. A method for improving the bacterial flora of culture soil, comprising the step of blending the bacterial flora improver according to any one of claims 25 to 29 into soil.

31. A culture soil containing the bacterial flora improver according to any one of claims 25 to 29.

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