WO2022196216A1

WO2022196216A1 - Seed coating method

Info

Publication number: WO2022196216A1
Application number: PCT/JP2022/005739
Authority: WO
Inventors: 一道佐志; 繁宇波
Original assignee: Ｊｆｅスチール株式会社
Priority date: 2021-03-16
Filing date: 2022-02-14
Publication date: 2022-09-22

Abstract

Provided is a seed coating method with which it is possible to obtain high-quality coated seeds formed into single grains, said coated seeds being obtained in a short and straightforward step in iron-based seed coating art.　In the seed coating method according to the present invention, the surfaces of seeds are coated using a seed coating agent that contains an iron-based powder, wherein the method comprises: a step for depositing the seed coating agent on the surfaces of the seeds; and a step for supplying water and air while fluidizing the seeds to which the seed coating agent have been deposited, thereby oxidizing the iron-based powder and forming a coating layer on the surfaces of the seeds.

Description

Seed coating method

The present invention relates to a seed coating method for coating seeds with a seed coating agent containing iron powder.

With the aging of agricultural workers and the globalization of agricultural product distribution, labor saving in agricultural work and the reduction of agricultural product production costs have become issues that must be resolved. In order to solve these problems, for example, in paddy rice cultivation, the direct sowing method of sowing seeds directly in a field is becoming popular for the purpose of saving labor for raising seedlings and transplanting. Among them, the method of using seeds coated with iron powder to increase the specific gravity of the seeds is attracting attention because it has the advantage of preventing floating and outflow of seeds in paddy fields and preventing bird damage.

As a method of coating seeds with iron powder, for example, in Patent Document 1, coated rice seeds are spread thinly, and while humidified air is blown, the oxidation reaction of the iron powder is continued at room temperature of 25 ° C. for 12 hours. A method of drying at 0° C. is disclosed.

Further, Patent Document 2 discloses a method for producing single-grained iron-powder-coated rice seeds by using silica gel on rice seeds on which an iron-powder coating layer is formed to suppress aggregation of the coated seeds. ing. In Patent Document 2, the oxidation reaction of the iron powder is advanced by passing humidified air at a relative humidity of 80% or more and a temperature of 10 to 30° C. through the seeds.

Furthermore, Patent Document 3 discloses a method of covering seeds by spraying a spray liquid having a pH of 3.0 or more and 6.5 or less and oxidizing iron-based powder at an ambient temperature of 31 ° C. or more and 45 ° C. or less. It is In Patent Document 3, in order to prevent heat generation, the seeds are spread thinly on a vat or the like to accelerate the oxidation reaction, and the oxidation treatment can be completed in about 2 hours.

JP 2005-192458 A Japanese Unexamined Patent Application Publication No. 2014-221009 JP 2019-213465 A

Patent document 1 requires about 12 to 24 hours for oxidation, and there is a problem that the decay rate increases if the oxidation is inappropriate.

In Patent Document 2, the amount of water sprayed to oxidize the iron powder is supposed to be an appropriate amount, but it takes a long time of about 8 hours to oxidize the iron powder. There is a problem that the coating is peeled off without sufficiently progressing.

In Patent Document 3, it is necessary to strictly control the pH and atmospheric temperature of the spray solution in order to prevent the seeds from dying. Agglomeration between seeds is likely to occur, making seeding difficult. There is a problem in single granulation in exchange for shortening the time.

The present invention has been made to solve the above problems, and provides a seed coating method capable of obtaining single-grained, high-quality coated seeds in a short time and in a simple process in iron-based seed coating technology. It is intended to

In order to solve the above problems, the inventor obtained the following findings as a result of intensive research.

As a result of investigating the promotion of oxidation reaction by coating various coated seeds, the oxidation reaction progressed and single grains were formed when water and air were supplied to the seeds that were flowing during and/or after coating. Seeds were found to be obtained. In addition, it was found that when air of a specific temperature or higher is supplied, the oxidation reaction proceeds further, and good coated seeds that are single grains can be obtained in a short period of time without incurring damage to the seeds.

The present invention is based on the above findings, and its configuration is as follows.
(1) A seed coating method according to 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, wherein the seed coating agent is adhered to the surface of the seed. and forming a coating layer on the surface of the seed by oxidizing the iron-based powder by supplying water and air while flowing the seeds to which the seed coating agent has adhered. is.
(2) In the method described in (1) above, air is supplied in the step of adhering the seed coating agent to the seed surface.
(3) In addition, a seed coating method according to the second aspect of the present invention is a method of coating the surface of a seed with a seed coating agent containing iron-based powder, wherein the seed is fluidized while the seed is coated. By supplying the coating agent, water and air, the seed coating agent is adhered to the surface of the seed, and the iron-based powder is oxidized to form a coating layer on the surface of the seed.
(4) In any one of (1) to (3) above, air is supplied so that the ambient temperature is 46° C. or higher.
(5) In addition, in any one of the above (1) to (4), the seed coating agent contains at least one type of carboxylic acid having two or more carboxyl groups in one molecule and/or the seed It is added at the time of coating.
(6) In the powder described in (5) above, the amount of the carboxylic acid is 0.01% by mass or more and 6% by mass or less with respect to the mass of metallic iron in the iron-based powder.

In the seed coating method of the present invention, the step of attaching the seed coating agent to the surface of the seed, and supplying water and air to the seed to which the flowing seed coating agent is attached, oxidizes the iron-based powder. and the step of forming a coating layer on the surface of the seed, it is possible to shorten the oxidation treatment time and realize the single seeding of the coated seed.

A seed coating method according to an embodiment of the present invention is to coat the surface of a seed with a seed coating agent containing an iron-based powder. Therefore, the seeds to be coated with the seed coating agent in the present invention and the seed coating agent will be described first. Hereinafter, % by mass is described as %.
<seed>
Rice (rice plant) is preferably applied as the target seed in the present invention. The rice variety is not particularly specified, and any of Japonica rice, Indica rice, and Javanica rice can be applied. Since rice is often cultivated in paddy fields in hot and humid regions, the effects of the present invention can be exhibited more remarkably.
<Seed coating agent>
The seed coating agent used in the present embodiment contains iron-based powder, and iron powder, iron oxide powder, and a mixture of iron powder and iron oxide powder can be used as the iron-based powder. Also, the seed coating may further comprise binders, separating agents, carboxylic acids and other ingredients.
≪Iron powder≫
In the present embodiment, the iron-based powder used for the seed coating agent contains iron powder, and a mixture of iron powder, iron oxide powder, and other metal powder can also be applied. As the iron powder, pure iron, ferroalloy powder, partial iron oxide powder, and mixtures thereof can be applied. In addition, it is preferable that the metallic iron in the iron-based powder is 20% by mass or more, more preferably 40% by mass or more, from the viewpoint of rust generation in the coating layer when the seed is coated.

Examples of methods for producing iron powder include a reduction method in which mill scale and iron ore are reduced to produce iron powder, and an atomization method in which water or gas is injected into molten steel at high speed to produce iron powder.
≪Iron oxide powder≫
Iron oxides include Fe ₃ O ₄ (magnetite), Fe ₂ O ₃ (α-Fe ₂ O ₃ (hematite), β-Fe ₂ O ₃ , γ-Fe ₂ O ₃ (maghemite), ε-Fe ₂ O ₃ etc.), FeO (wustite), Fe(OH) ₂ (iron (II) hydroxide), Fe(OH) ₃ (iron (III) hydroxide, iron (III) hydroxide oxide), FeOOH (iron oxyhydroxide , α-FeOOH, β-FeOOH, γ-FeOOH, δ-FeOOH, etc.) and those that are amorphous (iron oxides, hydroxides, etc.). Each ratio is not particularly limited as long as it is within the scope of the present invention. However, powders such as mill scale and iron ore can be preferably applied from the viewpoint of economy.

Although the amount of iron-based powder used is not particularly specified, it is preferably 5% or more and 800% or less, more preferably 10% or more and 500% or less, based on the seeds (dry rice).

Although the particle size of the iron-based powder is not particularly specified, it is preferable for uniform coating that the iron-based powder having a particle size of 150 μm or less accounts for 80% or more of the total iron-based powder mass. The particle size distribution of the iron-based powder can be evaluated by sieving using the method specified in JIS Z2510-2004.

As the iron-based powder, a mixture of the above iron powder, iron oxide powder, and mixture of iron powder and iron oxide powder with other metal powder can also be applied. However, from the viewpoint of rust generation, the metallic iron component in the iron-based powder is preferably 20% or more, more preferably 40% or more.
≪Binder≫
Binders are composed of sulfates and/or chlorides that function as pro-oxidants. Sulfates are calcium sulfate, potassium sulfate, magnesium sulfate and their hydrates. Chlorides are sodium chloride, potassium chloride, calcium chloride, magnesium chloride and hydrates thereof. Especially preferred are calcined gypsum (calcium sulfate.1/2 hydrate) and gypsum (calcium sulfate.2 hydrate). The calcined gypsum and gypsum may be a mixture or mixture. Anhydrides can also be used for each binder.

Although the mass ratio of the binder to the iron-based powder is not specified, it is preferably 0.1 to 33% in order to facilitate the progress of rust.

However, since the function of the binder is to facilitate the progress of rust, it is possible to obtain the effects of the present invention without adding a binder if it is not necessary to speed up the progress of rust. is.

Although the average particle size of the binder is not specified, it is preferably in the range of 1 to 150 μm. If the average particle size of the binder is less than 1 μm, a large amount of agglomerated particles are generated during the coating operation, resulting in a significant decrease in workability. On the other hand, if the average particle size of the binder exceeds 150 μm, the adhesion to the iron-based powder is reduced, the strength of the coating layer is reduced, and the coating layer tends to peel off from the seeds.
≪Separating agent≫
The separating agent (finishing agent) coats the seeds as the outermost layer and prevents the seeds from fusing together when the seed coating agent is oxidized. However, since the seed coating method of the present embodiment has the effect of suppressing fusion between seeds, the use of a separating agent is not essential.

When a separating agent is used to further prevent the seeds from sticking together during the oxidation treatment, gypsum of Paris, silica gel, etc. can be preferably applied.
<<Carboxylic acid having two or more carboxy groups in one molecule>>
In the seed coating method according to the present embodiment, it is preferable that one or more carboxylic acids having two or more carboxyl groups in one molecule are contained in the seed coating agent and/or added during seed coating.

The form of carboxylic acid is not particularly limited as long as it has two or more carboxy groups in one molecule, and carboxylic acid and/or salts thereof, and anhydrides, hydrates and isomers thereof are used. can do. Two or more carboxylic acids can also be used in combination.

Carboxylic acids include citric acid, tartaric acid, malic acid, succinic acid, and ethylenediaminetetraacetic acid.

Carboxylate includes trisodium citrate, disodium hydrogen citrate, tripotassium citrate, potassium dihydrogen citrate, diammonium hydrogen citrate, triammonium citrate, sodium tartrate, sodium hydrogen malate, sodium malate, disodium succinate, mono- to tetra-sodium salts of ethylenediaminetetraacetic acid, and the like.

Carboxylic acid metal salts include iron citrate, calcium citrate, iron ammonium citrate, and iron ammonium ethylenediaminetetraacetate. However, metal salts other than iron are also applicable and within the scope of the present invention. Anhydrides and hydrates of these carboxylic acids, carboxylic acid salts and carboxylic acid metal salts are also included.

The reason why the coating layer is smoothed when a carboxylic acid having two or more carboxyl groups in one molecule is contained or added is that the acid dissolves iron powder and the chelate effect causes a large amount of divalent iron. It is thought that it has the effect of generating, stabilizing, spreading over the entire seed surface, and then changing to trivalent iron and fixing it. The occurrence of the above reaction is also due to the fact that when the seed coating agent of the present embodiment is used, the coated seeds take on a green to black color tone and then change to a red to brown color tone. can be estimated. In addition, it is also possible to stop supplying water and air when the color tone is green to black, spread it on a tray or the like, and change the color tone to red to brown while drying. be.

On the other hand, a carboxylic acid having only one carboxy group in one molecule, such as acetic acid, does not have the ability to form a chelate complex, so although it promotes the generation of rust, it does not stabilize divalent iron and does not stabilize in the air. The effect expected in the present invention is insufficient because it is easily changed to trivalent iron with oxygen. Moreover, it is not preferable because it generates odor due to its high volatility and further oxidizes surrounding metallic iron and iron oxide (wustite, magnetite, etc.).

Further, the amount of the carboxylic acid in the seed coating agent is preferably 0.01% by mass or more and 6% by mass or less with respect to the mass of metallic iron in the iron-based powder. This is because if the amount is less than 0.01% by mass, the effects of the present invention are reduced, and if the amount exceeds 6% by mass, the chelate effect tends to hinder the progress of rust.

Note that the amount of carboxylic acid is converted into the form of a carboxyl group (COOH), excluding water of hydration and cationic components.

In the seed coating method according to the present embodiment, the carboxylic acid having two or more carboxy groups in one molecule may be contained in advance in the seed coating agent, or may be added at the time of coating. It can be anything. Specifically, the carboxylic acid may be mixed in advance with other seed coating agents such as iron-based powder before coating the seeds, or an aqueous solution of the carboxylic acid may be sprayed at the time of coating the seeds. Both can be suitably employed, and both can be used in combination. However, some carboxylic acids are irritating to the skin and eyes, and some are deliquescent, so from the viewpoint of improving workability when using them and uniform mixing, it is better to add them in advance at the time of seed coating. may be valid.
≪Other ingredients≫
Other components can be contained to such an extent that the effects of the present invention are not impaired. Other ingredients include unavoidable impurities and additives intentionally added for the purpose of some effect, and in any case, the amount of other ingredients contained is 30% by weight based on the seed coating agent. % is preferable.
≪Coating amount≫
The amount of the seed coating agent to coat the seeds is not particularly specified, but it can be 5 to 800 parts by mass with respect to 100 parts by mass of dry seeds. In order to obtain a sufficient anchoring effect, it may be adjusted as appropriate, and the coating amount is preferably about 10 to 500 parts by mass.
<Seed covering method>
Next, the seed covering method according to this embodiment will be specifically described.

The seed coating method according to the present embodiment is a method of coating the surface of seeds using a seed coating agent containing iron-based powder. Specifically, the seed coating method according to the present embodiment comprises the steps of: attaching the seed coating agent to the surface of the seed; and supplying water and air to the flowing seeds attached with the seed coating agent. and forming a coating layer on the surface of the seed by oxidizing the iron-based powder.

In the step of attaching the seed coating agent to the surface of the seed (hereinafter also referred to as "coating"), there is no specific limitation on the method. For example, as shown in "Iron Coating Flooded Direct Seeding Manual 2010 (National Agriculture and Food Research Organization Kinki Chugoku-Shikoku Agricultural Research Center)" Any method such as a method using a mixer may be used.

Mixers include, for example, agitating blade type mixers (e.g. Henschel mixers, concrete mixers, etc.) and container rotary mixers (e.g. V-type mixers, double cone mixers, inclined rotary pan type mixers, rotary hoe type mixers, etc.). can be used. Also, a concrete mixer from which the stirring blade is removed can be preferably applied.

When applying a seed coating agent using these mixers, iron-based powder and seeds, and if necessary, a binder, a separating agent, and an additive are put into the mixer, and water and / Alternatively, the mixer may be rotated while spraying the processing liquid mainly composed of water.

In the step of forming a coating layer, water and air are supplied to oxidize the iron-based powder while the seeds to which the seed coating agent is adhered are in motion, thereby forming a coating layer (coating) on the surface of the seeds. . Here, the coating layer refers to a state in which a part or most of the metallic iron in the iron-based powder contained in the seed coating agent adhering to the surface of the seed is oxidized to form a rust layer.

Since it is essential to flow the seeds and supply water and air to the flowing seeds in the step of forming the coating layer of the present invention, this point will be specifically described below.
<flow>
Flow includes rolling, rocking, vibration, etc. Essentially, it is necessary that the seeds are not stationary.

As a method for fluidizing the seeds, it is preferable to use the granulator or mixer used in the step of attaching the seed coating agent to the surface of the seeds because the work can be simplified, but another mixer may be used. Alternatively, a step of applying the seed coating agent to the surface of the seeds with a mixer and then transferring the seeds to a vibrator to form a coating layer while shaking the seeds may be performed. By fluidizing the seeds during the oxidation treatment, it is possible to prevent the seeds from colliding with each other and separating from each other to prevent the seeds from agglomerating, thereby obtaining single-grained seeds.
<Water>
The method of supplying water may be either a method of directly adding it to the seeds or a method of incorporating it into the air. For example, there are a method of adding it to the inside of the seed or mixer in a container such as a spray, a mister, or a cup, and a method of supplying it as steam, mist, or humidified air containing water droplets. From the viewpoint of rust progress, it is preferable that the seeds to be coated are in a wet state during the oxidation treatment.

Although the water content is not particularly defined as long as the effects of the present invention can be obtained, it is preferably 10 to 1000%, more preferably 20 to 500%, and even more preferably 50 to 200% relative to the iron-based powder. If it is less than 10%, rusting will be insufficient and this will cause peeling of the coating layer. If it exceeds 1000%, it takes a long time to dry, and there is a problem that the working time becomes long.

In addition, if a large amount of water is supplied at once, the seeds will clump together. It is preferable to divide and supply a plurality of times while maintaining a stable state.

The pH of the water to be sprayed is not particularly defined as long as the effects of the present invention can be obtained, but strong acidity and strong alkalinity should be avoided since seeds may be damaged.
<Air>
Air blowers, fans, various dryers, hot air blowers, etc. can be used as a method of supplying air.

The temperature of the supplied air is not particularly defined as long as the effect of the present invention is obtained, but -20 to 200°C is preferably applicable, more preferably 0 to 150°C, and even more preferably 46 to 100°C. In the present invention, since water is supplied together with air, even when high-temperature air is supplied, the seed temperature does not rise due to the heat of evaporation, and the seed temperature can be kept lower than the temperature of the supplied air.

However, from the viewpoint of promoting the oxidation of the iron-based powder, it is preferable that the ambient temperature is high, and it is preferable to supply air so that the ambient temperature is 46°C or higher.

Here, the atmospheric temperature is the temperature of the air supplied toward the seed near the seed, and refers to the temperature of the air at a distance of about 1 to 15 cm from the seed.

However, in order to maintain germination, the seed temperature should be 60°C or lower, preferably 50°C or lower, and more preferably 40°C or lower. Also, the temperature of the seeds should be 0°C or higher, more preferably 10°C or higher so that the seeds do not freeze and the rusting progresses.

The wind speed of the supplied air is not particularly defined as long as the effects of the present invention can be obtained, but it is preferably 0.1 to 15 m/sec, more preferably 0.5 m/sec to 10 m/sec. If it is less than 0.1 m/sec, the oxidation reaction and cooling do not proceed, and the effects of the present invention cannot be obtained. If it exceeds 15 m/sec, the seeds and seed coating will scatter.

The wind speed can be measured using a hot-wire anemometer near the seeds. In the case of a pan-type granulator, a pot mixer, etc., the measurement can be performed in the vicinity of the position where the seeds stay during mixing while the granulator and mixer are in a stationary state. Although it is preferable to perform the measurement with seeds as a dummy, it may be performed without seeds as long as the positional relationship is the same. It is also possible to substitute a method of measuring at the outlet of the air duct of the hot air fan. In the case of a closed-space apparatus such as a V-type mixer, the air duct to be supplied is temporarily removed and the measurement is performed at the outlet of the air duct.

By the way, when water and air are supplied to the iron-based powder for oxidation treatment, the iron-based powder generates heat due to the oxidation reaction and the seed temperature rises. For example, if water and air are supplied to the seeds while the seeds are stacked and kept still, the temperature of the seeds may rise too much, resulting in poor germination.

Therefore, in the past, the seeds were spread thinly on a vat or tray to a thickness of about 1 cm or less, and water was sprinkled in a state where the heat of the seeds can be sufficiently dissipated to perform oxidation treatment. Alternatively, it is necessary to pack the coated seeds in a mesh bag and to cool the seeds by aerating while sprinkling water or by circulating humidified air.

In addition, supplying high-temperature air promotes oxidation, but in that case as well, there is concern that the rise in seed temperature will reduce germination and cause the seeds to clump together.

In this regard, in the present embodiment, water and air are supplied to the flowing seeds for oxidation treatment. It was possible to keep the seed temperature rise low enough that the rate did not decrease.

Furthermore, as described above, even when high-temperature air is supplied, water is supplied at the same time as the air, so the seed temperature does not rise due to the heat of evaporation, and the seed temperature can be kept lower than the temperature of the supplied air. . Therefore, there is very little adverse effect on germination in this embodiment.

In the present embodiment, a granulator or mixer is used to attach the seed coating agent to the surface of the seeds, and the granulator or mixer used in the step is continuously used to produce the seeds with the seed coating agent attached. Water and air were supplied to the fluidized seeds.

After the water and air were supplied, the air was continued to be supplied in the mixer, and the seeds were taken out after drying to some extent. After that, the seeds were transferred to a tray or the like, spread out, and dried after removing excess water for seed storage. At this time, a small amount of non-adhered powder may come out, but it can be removed by lightly sieving, and the removed powder can be used for the next coating. In addition, when the seeds generate heat, measures to cool the seeds may be taken, such as setting the layer thickness of the seeds spread on the tray to about 1 cm or less for cooling.

According to the present embodiment, single grained seeds could be obtained without the seeds aggregating. In addition, the strength of the coating layer and the germination of seeds were also good.

Furthermore, the time required for the mixing work (oxidation treatment time) required for the process of forming the coating layer was reduced to less than 1 hour.

The above is an example of performing the step of oxidizing the iron-based powder (forming the coating layer) after the step of attaching the seed coating agent to the surface of the seed, but the present invention is not limited to this, and the seed coating agent In the step of adhering the agent to the surface of the seed, air may be supplied to advance the oxidation of the iron-based powder in advance, and the iron-based powder may be further oxidized to form a coating layer. Moreover, the step of adhering the seed coating agent to the surface of the seed and the step of oxidizing the iron-based powder may be performed at the same time.

For example, when the mixer into which the seed coating agent and seeds are put is rotated, air is supplied together with water to simultaneously carry out the step of adhering the seed coating agent to the surface of the seeds and the step of oxidizing the iron-based powder. be able to. In this case, it can be considered that part of the amount of water fed into the mixer is used for the step of adhering the seed coating agent to the surface of the seeds, and part is used for the step of oxidizing the iron-based powder. can.

Since the effect of the present invention can be obtained in the above case, it is within the scope of the present invention. It is more preferable to perform the steps because the work can be separated.

An experiment was conducted to confirm the effect of the present invention, which will be explained below.

In the experiment, rice seeds were coated with a seed coating agent using the seed coating method according to the present invention, and an evaluation test was conducted on the coated seeds.

The step of attaching the seed coating agent to the surface of the seeds in the invention examples and comparative examples was performed according to the method described in the above-mentioned "Iron Coating Flooded Direct Sowing Manual 2010". Specifically, it is as follows.

First, we prepared the seeds (dry rice) and the seed coating.

Next, the seed coating agent was applied to 100 g of seeds (dry rice) in several batches while spraying an appropriate amount of water using a tilt-rotating pan-type granulator or the like.

In the process of oxidizing the iron-based powder (forming the coating layer) in the invention example, the apparatus used in the above process is continued to be used, and the flowing seeds are sprayed while supplying air with a hot air fan. supplied water. Tap water was used unless otherwise specified. The temperature of the supplied air is the temperature of the supplied air in the vicinity of the blowout nozzle of the hot air blower, and was measured at a position 5 cm from the seed.

After the coated seeds were spread on a tray and dried, they were lightly sieved with a sieve with an opening of 2 mm and subjected to evaluation.

In addition, in the step of oxidizing the iron-based powder in the comparative example, the seeds to which the seed coating agent was attached were spread in a vat and allowed to stand still, and the treatment liquid was sprayed thereon.

In this example, an experiment was conducted by changing the types and amounts of the iron powder, iron oxide powder, binder, finishing agent (separating agent), and carboxylic acid that are the raw materials of the seed coating agent.

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 Table 5: Binders and Finishes, Table 6: Carboxylic Acids).

In invention examples 1 to 49 shown in Tables 1 and 2, a coating layer was formed on the seed surface according to the seed coating method according to the present invention. Among them, in Examples 1 to 22, the step of forming a coating layer by oxidizing the iron-based powder was performed after the step of attaching the seed coating agent to the surface of the seed.

Further, in Invention Examples 23 to 25, 42, and 44, air is supplied from the beginning in the step of attaching the seed coating agent to the surface of the seed, the oxidation of the iron-based powder is advanced in advance, and the iron-based powder is further oxidized. Then, a step of forming a coating layer was performed.

Furthermore, in Invention Examples 26-28, the step of adhering the seed coating agent to the surface of the seed and the step of oxidizing the iron-based powder were carried out at the same time. In Invention Examples 26 to 28, while supplying air to the flowing seeds, the seed coating agent and the total amount of water required for adhesion of the seed coating agent and oxidation of the iron-based powder were alternately and/or simultaneously added. Then, the adhesion of the seed coating agent and the oxidation of the iron-based powder proceeded at the same time.

In addition, in Invention Examples 29 to 49, one or more carboxylic acids having two or more carboxy groups in one molecule are contained in the seed coating agent and/or added during seed coating. Among these, Invention Examples 29 to 46 are those in which the carboxylic acids shown in Table 6 are pre-mixed with the seed coating agent, and Invention Example 47 is one in which a carboxylic acid aqueous solution is added during seed coating and seed oxidation. In Invention Examples 48 and 49, the oxidation treatment time was shortened, and the seeds were spread on a tray at the time when the seed coating had a green to black color tone.

In addition, in all of Invention Examples 29 to 49, 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.

On the other hand, Comparative Examples 1 to 6 and Invention Examples 1 to 28 contain no carboxylic acid.

For the coated seeds coated with the seed coating agent under the respective conditions of the invention examples and comparative examples shown in Tables 1 and 2, the oxidation treatment time was measured as shown below, and evaluation was performed from each viewpoint.
<Oxidation treatment time>
In each invention example, after the step of adhering the seed coating agent to the surface of the seeds, air and water were supplied, and at the time when sufficient generation of red rust was visually confirmed on the surface of the seed coating agent, air and water were supplied. was terminated, and the period up to this termination time was taken as the oxidation treatment time. In addition, in each comparative example, after the step of attaching the seed coating agent to the surface of the seed, the time required to visually confirm sufficient generation of red rust on the surface of the seed coating agent (time until oxidation treatment is completed). was taken as the oxidation treatment time. In addition, in invention examples 23 to 28, the seed covering time is considered to be included in the oxidation treatment time because air is supplied. In invention examples 48 and 49, the oxidation treatment time is until sufficient red rust generation is confirmed.
<Single-grain property>
Among the coated seeds, the coated seeds in which the seeds were agglomerated together, that is, the multiple grains were separated by a sieve of φ7.3 mm, and the single grain property was evaluated from the weight ratio according to the following criteria.

As the evaluation of single-grain property, the weight ratio of aggregated grains (multiple grains) was judged as ⊚ when 5% or less, ∘ when more than 5% and 10% or less, Δ when more than 10% and 50% or less, and x when more than 50%. .

If the weight ratio of the aggregated grains exceeds 50%, the coated seeds cannot be practically seeded from the viewpoint of uniform seeding. It is. On the other hand, when the seed is 5% or less, the seeds are substantially single grains, so that it is easy to control the sowing in all of the sowing, row sowing, and dot sowing, and is good as a coated seed.
<Coating smoothness>
The coating state of the seed surface during powder coating was visually evaluated.

As an evaluation of the smoothness of the coating, ⊚ indicates that almost all the seeds are smooth, ○ indicates that there are some non-smooth coated seeds but there is no problem, and the non-smooth covered seeds are conspicuous and the effect of the coating is judged to be insufficient. The seeds were evaluated as Δ, and those with a large number of non-smooth coated seeds were evaluated as ×.
<Coating strength>
Using a sieve with an opening of 2 mm, 100 g of seeds were shaken for 15 minutes with a low-tap sieve shaker, and the weight loss rate was measured.

As the evaluation of the coating strength, the weight reduction ratio was evaluated as ⊚ when it was 1% or less, ∘ when it was over 1% and 5% or less, Δ when it was more than 5% and 20% or less, and x when it was over 20%.

If the weight reduction rate exceeds 20%, the coating agent attached to the seed is greatly peeled off, and the working environment is deteriorated, so it cannot be used as a coated seed. There is something. On the other hand, when it is 1% or less, the adhesiveness is good, the specific gravity of the seed is maintained, and the work environment is less likely to deteriorate, so it is good as a coated seed.
<Germination>
50 seeds were placed on wet filter paper in a Petri dish, covered and stored in a constant temperature bath at 30°C, and germination was observed daily. Germination rate was investigated for the rate of germination after 1 week and was evaluated based on the rate of germination (96%) of uncoated seeds (corresponding to Comparative Example 1).

The germination rate was evaluated as ◎ when the germination rate was 90% or more, ○ when 80% or more and less than 90%, △ when 60% or more and less than 80%, and x when less than 60%.

If the germination rate is less than 60%, the seeds are damaged and cause a drop in seedling establishment. If it is less than 85%, the seedling stability will be similarly lowered.

Tables 1 and 2 above summarize the oxidation treatment time and the results of each evaluation.

As shown in Tables 1 and 2, in Invention Examples 1 to 49 using the seed coating method according to the present invention, all evaluations of single grain property, coating smoothness, coating strength, and germination are good. got the results.

In addition, in Invention Examples 1 to 49, the oxidation treatment time was shorter than in Comparative Examples 1 to 6.

Furthermore, one or more carboxylic acids having two or more carboxyl groups in one molecule are contained in the seed coating agent and/or added during seed coating, and the amount of carboxylic acid is 0.01% by mass relative to the mass of metallic iron. As described above, in Invention Examples 29 to 49 in which the content was 6% by mass or less, the uniformity of the coating layer was improved compared to other Invention Examples 1 to 28, and coated seeds excellent in coating smoothness were obtained.

As described above, according to the seed coating method according to the present invention, it is possible to greatly shorten the oxidation time compared to the conventional method without reducing the germination rate, and the coated seed that has a sufficient coating layer strength and is made into a single seed. It has been demonstrated that it is possible to create

Claims

A seed coating method for coating the surface of a seed with a seed coating agent containing iron-based powder,
a step of adhering the seed coating to the surface of the seed;
and supplying water and air while fluidizing the seeds to which the seed coating agent has adhered, thereby oxidizing the iron-based powder to form a coating layer on the surface of the seeds.
The seed coating method according to claim 1, wherein air is supplied in the step of attaching the seed coating agent to the seed surface.
A seed coating method for coating the surface of a seed with a seed coating agent containing iron-based powder,
By supplying the seed coating agent, water, and air while the seeds are fluidized, the seed coating agent is adhered to the surface of the seed, and the iron-based powder is oxidized to form a coating layer on the surface of the seed. seed coating method.
The seed covering method according to any one of claims 1 to 3, wherein air is supplied so that the ambient temperature is 46°C or higher.
The seed coating method according to any one of claims 1 to 4, wherein one or more carboxylic acids having two or more carboxy groups in one molecule are contained in the seed coating agent and/or added during seed coating.
The seed coating method according to claim 5, wherein the amount of the 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.