Seed coating method

Abstract

Provided is a seed coating method that enables obtaining single-seeded high-quality coated seeds in a short time and with a simplified process in an iron-based seed coating technique. The seed coating method according to the present invention is a method for coating the surface of a seed with a seed coating agent containing an iron-based powder, and comprises: a process of causing the seed coating agent to adhere to the surface of the seed; and a process of causing the iron-based powder to oxidize by supplying water and air while causing the seed to which the seed coating agent has adhered to flow, thereby forming a coating layer on the surface of the seed.

Description

Technical Field

[0001] This invention relates to a seed coating method using a seed coating agent containing iron powder to coat seeds. Background Technology

[0002] With the aging of agricultural workers and the globalization of agricultural product distribution, reducing labor costs in farming and lowering agricultural production costs have become pressing issues. To address these issues, for example, in rice cultivation, direct sowing—where seeds are sown directly into the field to save time on seedling raising and transplanting—is gaining popularity. Among these methods, the use of seeds coated with iron powder to increase seed density has attracted attention due to its advantages in preventing seed floating and flowing out of paddy fields, as well as protecting against bird damage.

[0003] As a method for coating seeds with iron powder, for example, Patent Document 1 discloses a method of spreading coated rice seeds thinly, allowing the oxidation reaction of the iron powder to continue for 12 hours at room temperature of 25°C while blowing humidified air, and then drying at 40°C.

[0004] Furthermore, Patent Document 2 discloses a method for producing single-grain iron-coated rice seeds by using silica gel to inhibit the aggregation of the coated rice seeds. In Patent Document 2, the iron powder is oxidized by ventilating the seeds with humidified air at a relative humidity of 80% or higher and a temperature of 10–30°C.

[0005] Furthermore, Patent Document 3 discloses a method for coating seeds by oxidizing iron-based powders in an atmosphere temperature of 31°C to 45°C by dispersing a dispersing solution with a pH of 3.0 or higher and 6.5 or lower. In Patent Document 3, to prevent overheating, the oxidation reaction is promoted by thinly spreading the seeds on a mat or similar material, and the oxidation treatment can be completed in about 2 hours.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2005-192458

[0009] Patent Document 2: Japanese Patent Application Publication No. 2014-221009

[0010] Patent Document 3: Japanese Patent Application Publication No. 2019-213465 Summary of the Invention

[0011] The problem that the invention aims to solve

[0012] In Patent Document 1, the oxidation time is about 12 to 24 hours, which has the problem that the disintegration rate increases if the oxidation is not done properly.

[0013] In Patent Document 2, although the amount of water dispersed to oxidize the iron powder is set to be appropriate, it takes about 8 hours for the iron powder to oxidize, which results in the coating peeling off because the oxidation is not fully completed in a short time.

[0014] In Patent Document 3, strict management of the pH and ambient temperature of the dispersing solution is required to prevent seed death. Although rusting occurs within a relatively short period of about 2 hours, the rapid oxidation reaction easily causes the seeds to aggregate and bind together, making sowing difficult. While the time is shortened, the trade-off is the challenge of achieving single-seed formation.

[0015] This invention was made to solve the above-mentioned problems, and its purpose is to provide a seed coating method that can obtain high-quality coated seeds with single grains in a short time and simplified process in iron-based seed coating technology.

[0016] Methods for solving problems

[0017] In order to solve the above problems, the inventors of this application conducted in-depth research and obtained the following insights.

[0018] Various coating methods were applied to the seeds, and the effects on promoting the oxidation reaction were studied. The results showed that if water and air were supplied to the flowing seeds during and / or after coating, the oxidation reaction proceeded, resulting in single-seed formation. Furthermore, when air was supplied at a specific temperature above a certain level, the oxidation reaction proceeded further without damaging the seeds, and good single-seed formation of coated seeds could be obtained in a short time.

[0019] This invention is based on the above insights and is structured as follows.

[0020] (1) The seed coating method of the first aspect of the present invention is a method of coating the surface of a seed with a seed coating agent containing iron-based powder. The seed coating method includes: a step of attaching the seed coating agent to the surface of the seed; and a step of oxidizing the iron-based powder to form a coating layer on the surface of the seed by supplying water and air while the seed with the attached seed coating agent is flowing.

[0021] (2) In addition, air is supplied during the process of attaching the aforementioned seed coating agent to the surface of the seed as described in (1) above.

[0022] (3) In addition, the second aspect of the present invention relates to a seed coating method that uses a seed coating agent containing iron-based powder to coat the surface of a seed. In the aforementioned seed coating method, the seed coating agent, water and air are supplied while the aforementioned seed is being circulated, thereby causing the aforementioned seed coating agent to adhere to the surface of the seed and causing the aforementioned iron-based powder to oxidize, thereby forming a coating layer on the surface of the aforementioned seed.

[0023] (4) In addition, in any of the contents described in (1) to (3) above, air is supplied in such a way that the ambient temperature is 46°C or higher.

[0024] (5) In addition, in any of the contents described in (1) to (4) above, the seed coating agent contains one or more carboxylic acids having two or more carboxyl groups in one molecule, and / or one or more carboxylic acids having two or more carboxyl groups in one molecule are added during seed coating.

[0025] (6) In addition, in the contents described in (5) above, the amount of the aforementioned carboxylic acid relative to the mass of metallic iron in the aforementioned iron-based powder is 0.01% by mass or more and 6% by mass or less.

[0026] Invention Effects

[0027] In the seed coating method of the present invention, by including a step of attaching a seed coating agent to the surface of the seed, and a step of supplying water and air to flowing seeds with the aforementioned seed coating agent attached, thereby oxidizing iron-based powder to form a coating layer on the surface of the aforementioned seeds, it is possible to shorten the oxidation treatment time and achieve single-grain coating of the seeds. Detailed Implementation

[0028] The seed coating method according to embodiments of the present invention is a method of coating the surface of seeds with a seed coating agent containing iron-based powder. Hereinafter, the seeds and the seed coating agent that are the objects of the seed coating agent in the present invention will be described first. Hereinafter, mass % is referred to as %.

[0029] <seed>

[0030] Rice (paddy rice) is preferably used as the seed in this invention. There is no particular limitation on the variety of rice; any of the following can be used: japonica rice, indica rice, or Javanese rice. Since rice is mostly cultivated in paddy fields in hot and humid regions, the effects of this invention can be more significantly realized.

[0031] Seed coating agent

[0032] The seed coating agent used in this embodiment contains iron-based powder, which can be iron powder, iron oxide powder, or a mixture of iron powder and iron oxide powder. Additionally, the seed coating agent may also contain a binder, a separating agent, a carboxylic acid, and other components.

[0033] Iron Fan

[0034] In this embodiment, the iron-based powder used in the seed coating agent includes iron powder, and mixtures of iron powder, iron oxide powder, and other metal powders can also be used. As the iron powder, pure iron, alloy iron powder, partially iron oxide powder, and mixtures thereof can be used. It should be noted that, from the viewpoint of preventing rusting in the coating layer when applied to seeds, it is preferable that the metallic iron in the iron-based powder is 20% by mass or more, and more preferably 40% by mass or more.

[0035] Examples of methods for manufacturing iron powder include reduction methods, which involve reducing rolled mill scale or iron ore, and atomization methods, which involve spraying water or gas at high speed into molten steel.

[0036] Iron oxide powder

[0037] Examples of iron oxides include Fe3O4 (magnetite), Fe2O3 (α-Fe2O3 (hematite), β-Fe2O3, γ-Fe2O3 (magnesite), ε-Fe2O3, etc.), FeO (hemite), Fe(OH)2 (ferric hydroxide (II)), Fe(OH)3 (ferric hydroxide (III), oxidized ferric hydroxide (III)), FeOOH (ferric hydroxides, α-FeOOH, β-FeOOH, γ-FeOOH, δ-FeOOH, etc.), and amorphous substances (iron oxides, hydroxides, etc.). The ratios of each are not particularly limited as long as they are within the scope of this invention. However, from an economic point of view, powders made from rolled oxide scale, iron ore, etc., are preferred.

[0038] There are no specific regulations on the amount of iron-based powder used, but it is preferably 5% or more and 800% or less relative to the seeds (dry rice), and more preferably 10% or more and 500% or less.

[0039] Furthermore, there is no specific specification for the particle size of the iron-based powder. For uniform coating, it is preferable that the iron-based powder with a particle size of 150 μm or less accounts for more than 80% of the total iron-based powder mass. It should be noted that the particle size distribution of the iron-based powder can be evaluated by sieving using the method specified in JIS Z2510-2004.

[0040] For iron-based powders, it is also possible to apply the powders obtained by mixing other metal powders into the aforementioned iron powder, iron oxide powder, and mixtures of iron powder and iron oxide powder. However, from the viewpoint of rusting, it is preferable that the metallic iron content in the iron-based powder is 20% or more, and more preferably 40% or more.

[0041] Binder

[0042] The binder consists of sulfates and / or chlorides that function as pro-oxidants. Sulfates refer to calcium sulfate, potassium sulfate, magnesium sulfate, and their hydrates. Chlorides refer to sodium chloride, potassium chloride, calcium chloride, magnesium chloride, and their hydrates. Calcined gypsum (calcium sulfate 1 / 2 hydrate) and gypsum (calcium sulfate dihydrate) are particularly preferred. Calcined gypsum and gypsum can be mixtures or blends. Acid anhydrides can also be used for each binder.

[0043] There is no particular limitation on the mass ratio of binder to iron-based powder, but it is preferred to be between 0.1% and 33% to facilitate rust formation.

[0044] Originally, the function of the binder was to facilitate the rusting process. Therefore, even without adding a binder, the effects of this invention can be achieved without accelerating the rusting process.

[0045] The average particle size of the binder is not particularly limited, but is preferably in the range of 1 to 150 μm. This is because when the average particle size of the binder is less than 1 μm, more aggregated particles are generated during the coating operation, thus significantly reducing operability. On the other hand, when the average particle size of the binder is greater than 150 μm, the adhesion to iron-based powders decreases, the strength of the coating layer decreases, and it tends to peel off easily from the seeds.

[0046] Separating Agent

[0047] A separating agent (finishing agent) is applied as the outermost layer to the seeds to prevent them from fusing together when the seed coating agent is oxidized. However, since the seed coating method of this embodiment has the effect of inhibiting seed fusing, the use of a separating agent is not necessary.

[0048] When using a separating agent to further prevent seeds from merging together during oxidation treatment, calcined gypsum, silica gel, etc., are preferred.

[0049] Carboxylic acids having two or more carboxyl groups in one molecule

[0050] In the seed coating method of this embodiment, it is preferable that the seed coating agent contains one or more carboxylic acids having two or more carboxyl groups in one molecule, and / or one or more carboxylic acids having two or more carboxyl groups in one molecule are added during seed coating.

[0051] As a form of carboxylic acid, there are no particular limitations as long as it has two or more carboxyl groups in one molecule. Carboxylic acids and / or their salts, as well as their anhydrides, hydrates, and isomers, can be used. In addition, it is also possible to use a combination of two or more carboxylic acids.

[0052] Examples of carboxylic acids include citric acid, tartaric acid, malic acid, succinic acid, and ethylenediaminetetraacetic acid.

[0053] Examples of carboxylate salts include trisodium citrate, disodium hydrogen citrate, tripotassium citrate, potassium dihydrogen citrate, diammonium hydrogen citrate, triammonium citrate, sodium tartrate, sodium hydrogen malate, sodium malate, disodium succinate, and monosodium to tetrasodium salts of ethylenediaminetetraacetic acid.

[0054] Examples of carboxylic acid metal salts include ferric citrate, calcium citrate, ferric ammonium citrate, and ferric ammonium ethylenediaminetetraacetate. However, metal salts other than iron can also be used within the scope of this invention. Furthermore, these carboxylic acids, carboxylic acid salts, and carboxylic acid metal salts also include acid anhydrides and hydrates.

[0055] When a carboxylic acid containing or added to a molecule having two or more carboxyl groups is present, the following effects are believed to contribute to smoothing the coating layer: it acts as an acid to dissolve iron powder; and it generates and stabilizes a large amount of ferrous iron due to its chelating effect, allowing it to spread throughout the seed surface, and then becomes ferric iron and is fixed. When using the seed coating agent of this embodiment, the above-described reaction can be inferred from the fact that the coated seeds, after having a greenish-black hue, change to a reddish-brown hue. Furthermore, by stopping the supply of moisture and air when the seeds have a greenish-black hue and drying them on trays or the like, the seeds can also change to a reddish-brown hue, which is a preferred method as it shortens the process.

[0056] On the other hand, carboxylic acids, such as acetic acid, which have only one carboxyl group in one molecule, do not have the ability to form chelates. Therefore, although they promote rusting, they do not stabilize ferrous iron and are easily converted to ferric iron by oxygen in the air. Thus, the desired effect in this invention is insufficient. In addition, the high volatility produces an odor, which further oxidizes the surrounding metallic iron and iron oxides (hemispherite, magnetite, etc.), making it undesirable.

[0057] Furthermore, relative to the mass of metallic iron in the iron-based powder, the amount of the aforementioned carboxylic acid in the seed coating agent is preferably 0.01% by mass or more and 6% by mass or less. This is because when it is less than 0.01% by mass, the effect of the present invention tends to decrease, and when it is greater than 6% by mass, it tends to be less prone to rusting due to the chelation effect.

[0058] It should be noted that the amount of carboxylic acid is calculated using the form of carboxyl groups (COOH), excluding hydrated water and cationic components.

[0059] It should be noted that in the seed coating method described in this embodiment, the carboxylic acid having two or more carboxyl groups per molecule can be pre-included in the seed coating agent or added during coating. Specifically, for other substances constituting the seed coating agent, such as iron-based powder, the carboxylic acid can be pre-mixed before seed coating or added by spraying an aqueous solution of the carboxylic acid during seed coating; both methods are suitable and can be used in combination. However, carboxylic acids can contain substances that are irritating to the skin and eyes or are deliquescent. Therefore, from the viewpoint of improving operability and uniform mixing during use, pre-adding them during seed coating is sometimes effective.

[0060] Other Ingredients

[0061] Other components may be included as long as they do not impair the effects of the invention. Other components include unavoidable impurities and additives intentionally added for a certain effect. In any case, the amount of other components is preferably about 30% by weight relative to the seed coating agent.

[0062] "Amount of coverage"

[0063] There is no particular limitation on the amount of seed coating agent relative to the seeds; it can be 5 to 800 parts by weight relative to 100 parts by weight of dry seeds. Adjustments can be made appropriately to obtain a sufficient anchoring effect, with approximately 10 to 500 parts by weight being preferred as the coating amount.

[0064] <Seed Covering Methods>

[0065] Next, the seed coating method involved in this embodiment will be described in detail.

[0066] The seed coating method of this embodiment involves coating the surface of seeds with a seed coating agent containing iron-based powder. Specifically, the seed coating method of this embodiment includes: a step of adhering the aforementioned seed coating agent to the surface of the seeds; and a step of supplying water and air to flowing seeds with the aforementioned seed coating agent adhering to them, thereby oxidizing the aforementioned iron-based powder to form a coating layer on the surface of the aforementioned seeds.

[0067] There are no restrictions on the specific method used in the process of applying a seed coating agent to the surface of the seed (hereinafter also referred to as "coating"). For example, as shown in "Iron Coating and Water Spraying Manual 2010 (compiled by the Kinki-Chūgoku-Shikoku Agricultural Research Center of the National Research Institute of Agriculture and Food Science and Technology)," any of the previously known methods using a mixer, such as hand-operated coating, can be used.

[0068] As a mixer, for example, agitator-type mixers (e.g., Henschel mixers, concrete mixers, etc.) and container rotary mixers (e.g., V-type mixers, double cone mixers, tilting rotary disc mixers, rotary plow mixers, etc.) can be used. In addition, a concrete mixer with the agitator removed can be preferred.

[0069] When using these mixers to apply seed coating agents, simply add the iron-based powder and seeds, along with the required binder, separator, and additives, into the mixer, and rotate the mixer while spraying water and / or a water-based treatment solution.

[0070] In the process of forming the coating layer, while the seeds coated with the seed coating agent are in a flowing state, water and air are supplied to oxidize the iron-based powder, forming a coating layer (film) on the surface of the seeds. Here, the coating layer refers to the state in which part or most of the metallic iron in the iron-based powder contained in the seed coating agent attached to the seed surface is oxidized to form a rust layer.

[0071] In the process of forming the coating layer of the present invention, it is necessary to make the seeds flow and to supply water and air to the flowing seeds, and therefore this point will be specifically described below.

[0072] <Flow>

[0073] Flow can be exemplified by rotation, shaking, and vibration, but it essentially requires that the seed is not stationary.

[0074] As a method for seed flow, using a granulator or mixer, which is also used in the process of adhering the seed coating agent to the seed surface, simplifies the operation and is therefore preferred; however, other mixers may also be used. Alternatively, after adhering the seed coating agent to the seed surface using a mixer, the seeds can be transferred to a vibrator and the coating layer formed while the seeds are shaken. By flowing the seeds during oxidation treatment, they can collide and separate, preventing seed aggregation and resulting in single-seedled seeds.

[0075] <Water>

[0076] The method of supplying water can be either by adding it directly to the seeds or by containing it in the air. Examples include adding water to the seeds or the interior of the mixer using containers such as sprayers, atomizers, or cups, or supplying humidified air containing steam, mist, or water droplets. From the viewpoint of rust formation, it is preferable that the covered seeds are in a moist state during the oxidation treatment.

[0077] The amount of moisture is not particularly limited as long as the desired effect of the present invention is achieved. It is preferably 10-1000% relative to iron-based powders, further preferably 20-500%, and even more preferably 50-200%. At less than 10%, insufficient rusting occurs, leading to coating peeling. At more than 1000%, drying time is required, resulting in longer operating times.

[0078] In addition, if a large amount of water is supplied at once, the seeds will clump together. Therefore, it is preferable to suppress the water supply to the point where the seeds can flow individually or to the point where they can dissociate even if they temporarily clump together. Furthermore, the water should be supplied in multiple portions while keeping the seeds moist.

[0079] The pH of the dispersing water is not particularly limited as long as the desired effect of this invention can be achieved, but strong acidity or alkalinity may damage the seeds, so it is best to avoid it.

[0080] <Air>

[0081] As a method of supplying air, blowers, fans, various dryers, hot air blowers, etc. can be used.

[0082] The temperature of the supplied air is not particularly limited as long as the desired effect of the present invention is achieved. Preferably, it is -20 to 200°C, more preferably 0 to 150°C, and even more preferably 46 to 100°C. In the present invention, water is supplied simultaneously with the air. Therefore, even when high-temperature air is supplied, the seed temperature does not rise due to heat of vaporization, and the seed temperature can be maintained at a lower temperature than the supplied air.

[0083] However, from the viewpoint of promoting the oxidation of iron-based powders, a high atmosphere temperature is preferred, and air is preferably supplied in a manner where the atmosphere temperature is 46°C or higher.

[0084] Here, ambient temperature refers to the temperature of the air supplied to the seed from its vicinity, specifically the air temperature at a distance of approximately 1 to 15 centimeters from the seed.

[0085] However, to maintain germination, the seed temperature can be set below 60°C, preferably below 50°C, and more preferably below 40°C. Additionally, to prevent the seeds from freezing and rusting, the seed temperature can be set above 0°C, and more preferably above 10°C.

[0086] The wind speed of the supplied air is not particularly limited as long as the effects of the present invention are achieved; 0.1 to 15 m / s is preferred, and 0.5 to 10 m / s is even more preferred. At speeds less than 0.1 m / s, the oxidation reaction and cooling do not occur, and the effects of the present invention are not achieved. At speeds greater than 15 m / s, the seeds and seed coating agent will be dispersed.

[0087] Wind speed can be measured near the seeds using a hot-wire anemometer. In the case of disc granulators, tank mixers, etc., the measurement can be taken near the location where the seeds are retained during mixing, while the granulator or mixer is stationary. Measurement is preferably performed with seeds as a dummy, but even without seeds, as long as the positional relationship is equal, it is acceptable. Alternatively, the measurement can be taken at the outlet of the air duct of a hot air blower. In the case of enclosed space devices such as V-type mixers, the air supply duct can be temporarily removed, and the measurement can be taken at the outlet of the air duct.

[0088] Here, when water and air are supplied to iron-based powders for oxidation treatment, the powders generate heat due to the oxidation reaction, causing the seed temperature to rise. For example, if water and air are supplied for oxidation treatment while the seeds are stacked and stationary, the seed temperature may rise excessively, reducing germination rates.

[0089] Therefore, in the past, seeds were thinly spread on pads, trays, etc., to a thickness of about 1 cm or less, and water was released to allow for sufficient heat dissipation during oxidation treatment. Alternatively, the covered seeds were placed in a mesh bag, and ventilation was provided while releasing water, or humidified air was circulated while ventilation was provided to cool the seeds.

[0090] In addition, oxidation is promoted when hot air is supplied, but in this case, as mentioned above, germination may decrease and seeds may clump together due to the increased seed temperature.

[0091] In this respect, in this embodiment, water and air are supplied to the flowing seeds for oxidation treatment, so even when measured using a contact thermometer, the seed temperature is at most around 50°C, and the rise in seed temperature can be suppressed to a low level so as not to reduce the germination rate.

[0092] Furthermore, as mentioned earlier, water is supplied simultaneously with the high-temperature air supply, so the seed temperature does not rise due to heat of vaporization and can be maintained at a temperature lower than that of the supplied air. Therefore, the adverse effects on germination performance in this embodiment are minimal.

[0093] In this embodiment, a granulator or mixer is used to attach the seed coating agent to the surface of the seeds. The granulator or mixer used in this process is then used to make the seeds with the seed coating agent attached flow, and water and air are supplied to the flowing seeds.

[0094] After supplying water and air, continue supplying air in this state within the mixer until the seeds are dried to a certain extent. Then, transfer and spread them on trays or similar containers, and remove excess moisture and dry them to preserve the seeds. At this point, a small amount of unattached powder may sometimes appear, but this can be easily removed by light sifting; the removed powder can be used for subsequent coating. Additionally, to prevent the seeds from heating up, ensure the layer thickness of the seeds on the trays is approximately 1 cm or less beforehand, and take measures to cool the seeds.

[0095] According to this embodiment, seeds that are individually separated and do not aggregate can be obtained. Furthermore, the strength of the seed coat and the germination rate of the seeds are also good.

[0096] Furthermore, the mixing time (oxidation treatment time) required for the process of forming the film layer can be set to less than 1 hour.

[0097] The above example describes a process of oxidizing iron-based powder (forming a coating layer) after the step of adhering the seed coating agent to the seed surface. However, the present invention is not limited to this. The following steps can also be performed: during the step of adhering the seed coating agent to the seed surface, air is supplied to pre-oxidize the iron-based powder, thereby further oxidizing the iron-based powder to form a coating layer. Alternatively, the steps of adhering the seed coating agent to the seed surface and oxidizing the iron-based powder can be performed simultaneously.

[0098] For example, by supplying air along with water while rotating a mixer containing a seed coating agent and seeds, it is possible to simultaneously perform the process of adhering the seed coating agent to the surface of the seeds and the process of oxidizing the iron-based powder. In this case, it is assumed that a portion of the water added to the mixer can be used for the process of adhering the seed coating agent to the surface of the seeds, and a portion can be used for the process of oxidizing the iron-based powder.

[0099] The effects of the present invention can also be obtained under the above circumstances, and therefore within the scope of the present invention, but when the step of oxidizing iron-based powder (forming a coating layer) is performed after the step of attaching the seed coating agent to the surface of the seed, the operation can be separated, and therefore it is more preferable.

[0100] Experiments were conducted to confirm the effectiveness of the present invention, and therefore will be described below.

[0101] In the experiment, the seed coating method of the present invention was used to coat rice seeds with a seed coating agent, and the coated seeds were evaluated.

[0102] The process of attaching the seed coating agent to the surface of the seed in the invention examples and comparative examples is performed according to the method described in the aforementioned "Iron Coating Water-Soaked Seed Direct Seeding Manual 2010". Specifically, as follows.

[0103] First, prepare the seeds (dry rice) and seed coating agent.

[0104] Next, using a tilting rotary disc granulator, while spraying an appropriate amount of water, apply seed coating agent to 100g of seeds (dry rice) in multiple applications.

[0105] In the step of oxidizing the iron-based powder in the invention example (forming a coating layer), the apparatus used in the above-described steps is continued to be used, and water is supplied to the flowing seeds simultaneously using a hot air blower and a sprayer. Unless otherwise specified, tap water is used. The temperature of the supplied air is the temperature of the supplied air near the blow nozzle of the hot air blower, but is measured at a distance of 5 cm from the seeds.

[0106] After the covered seeds were laid on a tray and dried, they were lightly sieved using a sieve with a 2mm mesh opening for evaluation.

[0107] In addition, the process of oxidizing iron-based powder in the comparative example is carried out by spreading the treatment liquid while the seeds coated with seed coating agent are laid on a pad and left to stand.

[0108] In this embodiment, experiments were conducted by changing the types and amounts of iron powder, iron oxide powder, binder, finishing agent (separating agent), and carboxylic acid used as raw materials for seed coating.

[0109] Tables 1 and 2 show the types and amounts of each raw material contained in the seed coating agent used in the experiment, and Tables 3 to 6 show the types of each raw material used in the seed coating agent (Table 3: iron powder, Table 4: iron oxide powder, Table 5: binder and finishing agent, Table 6: carboxylic acid).

[0110] Examples 1 to 49 of the invention shown in Tables 1 and 2 are examples of forming a coating layer on the surface of seeds according to the seed coating method of the present invention. Among them, Examples 1 to 22 are examples of forming a coating layer by oxidizing iron-based powder after the step of adhering the seed coating agent to the surface of the seed.

[0111] In addition, Examples 23-25, 42, and 44 describe a process in which air is supplied from the beginning of the process of attaching a seed coating agent to the surface of the seed, iron-based powder is oxidized in advance, and the iron-based powder is further oxidized to form a coating layer.

[0112] Furthermore, Examples 26-28 are examples of simultaneously performing the process of attaching a seed coating agent to the surface of the seed and the process of oxidizing the iron-based powder. In Examples 26-28, while supplying air to the flowing seeds, water is added alternately and / or simultaneously in amounts required for the attachment of the seed coating agent and the oxidation of the iron-based powder, so that the attachment of the seed coating agent and the oxidation of the iron-based powder occur simultaneously.

[0113] Furthermore, in Invention Examples 29-49, the seed coating agent contains one or more carboxylic acids having two or more carboxyl groups per molecule, and / or one or more carboxylic acids having two or more carboxyl groups per molecule are added during seed coating. Invention Examples 29-46 are examples of pre-mixing the carboxylic acids shown in Table 6 into the seed coating agent; Invention Example 47 is an example of adding an aqueous solution of carboxylic acids during seed coating and seed oxidation; and Invention Examples 48 and 49 are examples of shortening the oxidation treatment time and placing the seeds on trays at a point when the seed coating appearance has a greenish-black hue.

[0114] Furthermore, in Examples 29 to 49 of the invention, the amount of carboxylic acid relative to the mass of metallic iron is 0.01% by mass or more and 6% by mass or less.

[0115] In contrast, Comparative Examples 1-6 and Invention Examples 1-28 do not contain carboxylic acids.

[0116] [Table 1]

[0117]

[0118] [Table 2]

[0119]

[0120] [Table 3]

[0121] serial number name Product Name Manufacturer A1 Reduced iron powder JIP K-100T JFE Steel A2 Reduced iron powder DSP317 DOWA IP A3 Reduced iron powder JIP 255M JFE Steel A4 Atomized iron powder JIP 300A JFE Steel

[0122] [Table 4]

[0123] serial number name Product name, specifications Manufacturer B1 Rolled Oxide Scale JIP S-100 JFE Steel B2 Iron oxide (III) hematite Premium Reagent Wako Pure Medicine

[0124] [Table 5]

[0125]

[0126] [Table 6]

[0127] serial number name Specification Manufacturer D1 Citric acid reagents Fujifilm and Kojun Pharmaceutical D2 L(+)-Tartaric acid reagents Fujifilm and Kojun Pharmaceutical D3 DL-malic acid reagents Fujifilm and Kojun Pharmaceutical D4 Succinic acid reagents Fujifilm and Kojun Pharmaceutical D5 EDTA-1,000 reagents Fujifilm and Kojun Pharmaceutical

[0128] For the seeds coated with seed coating agents according to the respective conditions of the inventive examples and comparative examples shown in Tables 1 and 2, the oxidation treatment time was measured as follows, and an evaluation was conducted based on various viewpoints.

[0129] <Oxidation treatment time>

[0130] In each of the invention examples, air and water are supplied after the step of adhering the seed coating agent to the seed surface. The supply of air and water is stopped at the point when sufficient red rust formation can be visually confirmed on the surface of the seed coating agent, and the time up to this point is defined as the oxidation treatment time. In contrast, in each comparative example, the oxidation treatment time is defined as the time after the step of adhering the seed coating agent to the seed surface when sufficient red rust formation can be visually confirmed on the surface of the seed coating agent (up to the end of the oxidation treatment). It should be noted that in invention examples 23-28, air is also supplied during the seed coating time, and therefore is considered to be included in the oxidation treatment time. In invention examples 48 and 49, the time up to the point before sufficient red rust formation is confirmed is defined as the oxidation treatment time.

[0131] <Single-grain property>

[0132] The covered seeds, which are clustered together, are sieved through a 7.3 mm sieve. The single-seed quality is evaluated based on their weight ratio using the following criteria.

[0133] As an evaluation of single-particle characteristics, the weight percentage of aggregates (multiple particles) is 5% or less and is marked as ◎, greater than 5% but less than 10% and is marked as ○, greater than 10% but less than 50% and is marked as △, and greater than 50% and is marked as ×.

[0134] From the perspective of uniform sowing, when the weight proportion of the aforementioned aggregated grains is greater than 50%, the seeds cannot be used as covering seeds for sowing in practice. From the same point of view, when it is greater than 10%, the yield of the finished product as covering seeds is greatly reduced. On the other hand, when it is less than 5%, the seeds are essentially single-grained, so sowing is easy to control in broadcasting, row sowing, and spot sowing, making them good as covering seeds.

[0135] <Coating Smoothness>

[0136] The coating state of the seed surface during the powder coating process is evaluated visually.

[0137] As an evaluation of the smoothness of the coating, the case of almost complete smoothness is judged as ◎, the case of finding uneven coating seeds but not a problem is judged as ○, the case of obvious uneven coating seeds and judging that the coating effect is insufficient is judged as △, and the case of many uneven coating seeds and judging that the coating effect is low is judged as ×.

[0138] <Coating strength>

[0139] Using a sieve with a 2mm mesh opening, 100g of seeds were vibrated for 15 minutes using a rotary tapping vibrating sieve, and the weight reduction rate was measured.

[0140] As an evaluation of coating strength, a weight reduction of less than 1% is judged as ◎, greater than 1% but less than 5% as ○, greater than 5% but less than 20% as △, and greater than 20% as ×.

[0141] When the weight reduction is greater than 20%, a large amount of the coating agent attached to the seed peels off, worsening the operating environment, and therefore it cannot be provided as coated seed. When it is greater than 5%, from the same point of view, there are problems with using it as coated seed. On the other hand, when it is less than 1%, the adhesion is good, the seed weight is maintained, and it is difficult to worsen the operating environment, so it is good as coated seed.

[0142] Germination ability

[0143] Fifty seeds were placed on moistened filter paper in a petri dish, covered, and stored in a constant temperature bath at 30°C. Germination was observed daily. The germination rate was investigated after one week, and the germination rate was evaluated based on the germination rate of uncovered seeds (equivalent to Comparative Example 1) (96%).

[0144] As an evaluation of germination rate, a germination rate of 90% or higher is marked as ◎, 80% or higher but less than 90% is marked as ○, 60% or higher but less than 80% is marked as △, and less than 60% is marked as ×.

[0145] When the germination rate is less than 60%, seed damage occurs, leading to a decrease in seedling survival. Similarly, a germination rate less than 80% results in reduced seedling stability.

[0146] The oxidation treatment times and evaluation results are summarized in Tables 1 and 2 above.

[0147] As shown in Tables 1 and 2, in Invention Examples 1 to 49 of the present invention, good results were obtained in the evaluation of single-seed performance, smoothness of coating, strength of coating, and germination performance using the seed coating method of the present invention.

[0148] Furthermore, in Invention Examples 1 to 49, the oxidation treatment time was shorter than that in Comparative Examples 1 to 6.

[0149] Furthermore, in Invention Examples 29 to 49, where the seed coating agent contains one or more carboxylic acids having two or more carboxyl groups in one molecule, and / or one or more carboxylic acids having two or more carboxyl groups in one molecule are added during seed coating, and the amount of carboxylic acid relative to the mass of metallic iron is 0.01% by mass or more and 6% by mass or less, compared with other Invention Examples 1 to 28, coated seeds with improved uniformity of coating layer and excellent coating smoothness can be obtained.

[0150] The above confirms that the seed coating method according to the present invention can significantly shorten the oxidation time compared to the past without reducing the germination rate, and can produce single-grain coated seeds with sufficient coating strength.

Claims

1. Seed covering methods, among which, The seed coating method comprises coating the surface of seeds with a seed coating agent containing iron-based powder, wherein: The process of applying the seed coating agent to the surface of the seed; and The process of forming a coating layer on the surface of seeds by oxidizing the iron-based powder by supplying water and air while the seeds with the seed coating agent are flowing, wherein the air is supplied at an atmosphere temperature of 46°C or higher.

2. The seed coating method as described in claim 1, wherein, Air is supplied during the process of adhering the seed coating agent to the surface of the seed.

3. Seed covering methods, among which, The seed coating method involves coating the surface of seeds with a seed coating agent containing iron-based powder. By supplying the seed coating agent, water, and air while the seeds are flowing, the seed coating agent is attached to the surface of the seeds, and the iron-based powder is oxidized to form a coating layer on the surface of the seeds, wherein the air is supplied at an ambient temperature of 46°C or higher.

4. The seed coating method according to any one of claims 1 to 3, wherein, The seed coating agent contains one or more carboxylic acids having two or more carboxyl groups in one molecule, and / or one or more carboxylic acids having two or more carboxyl groups in one molecule are added during seed coating.

5. The seed coating method as described in claim 4, wherein, The amount of carboxylic acid relative to the mass of metallic iron in the iron-based powder is 0.01% by mass or more and 6% by mass or less.

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