JP7459831B2 - Seed coating agent, coated seed, and seed coating method - Google Patents

Description

The present invention relates to a seed coating agent, coated seeds, and a seed coating method, and particularly to a seed coating agent, coated seeds, and a seed coating method for coating seeds with a coating layer containing an iron element.

With the aging of agricultural workers and the globalization of agricultural product distribution, labor-saving agricultural work and reducing agricultural production costs have become issues that need to be resolved. In order to solve these problems, for example, in wet rice cultivation, a direct sowing method in which seeds are directly sown in a field is becoming popular in order to save the labor of raising seedlings and transplanting. Among these, a technique that uses seeds coated with iron powder to increase the specific gravity of the seeds is attracting attention because it has the advantage of preventing seeds from floating or being washed away in rice fields and preventing damage from birds.
Examples of seeds coated with iron powder as described above are disclosed in Patent Documents 1 and 2, for example.

JP 2005-192458 A JP 2017-153427 Publication

The coated seeds as described above are required to be uniformly coated without exposing the surface of the seeds.
In contrast, Patent Document 2 states with regard to the iron powder that "the particle size is not particularly specified, but it is preferable for the iron powder to be 150 μm or less in size and that the iron powder should account for 80% or more of the total iron powder mass in order to achieve uniform coating" (see paragraph [0022]).

However, even when the coating is uniform, the surface will have an uneven appearance depending on the particle shape of the iron powder. In addition, when relatively coarse iron powder is used, for example, when iron powder with a size between 63 μm and 150 μm accounts for 25% or more of the total iron powder mass, the coating will be uneven, and the seed surface will be exposed and the uneven shape will be noticeable. If the coating is uneven or the surface is noticeably uneven, there is a concern that the flow of seeds in the seed drill will be deteriorated, hindering uniform sowing. For this reason, improvements were required in the uniformity of the seed coating and the smoothness of the surface.

The present invention was made to solve such problems, and an object of the present invention is to provide a seed coating agent, coated seeds, and a seed coating method that improve coating uniformity and surface smoothness in iron-based seed coating technology. shall be.

The inventors conducted intensive research to solve the above problems and obtained the following findings.
As a result of conducting seed coating experiments and investigations, it was found that when relatively coarse iron powder was used, the coating became uneven, and there were areas where the seeds were exposed, and the surface unevenness tended to become more pronounced. In such cases, even if water-spraying was used to cause rusting, the rust from the unevenly distributed iron powder did not spread to the surrounding areas, and the areas where the seeds were exposed during coating remained almost completely exposed even after rusting, although the surface turned reddish brown due to a small amount of rust fluid.

On the other hand, when a specific amount of carboxylic acid having two or more carboxy groups in one molecule is used, it dissolves the unevenly distributed iron powder and fills the exposed part of the seed, thereby changing its shape. It can be made gentle. It has been found that this has the effect of providing a uniform and smooth coating layer.
The present invention is based on the above knowledge and consists of the following configuration.

(1) The seed coating agent according to the present invention is a seed coating agent containing an iron-based powder and used to coat the surface of seeds, characterized in that it contains one or more types of carboxylic acid having two or more carboxy groups in one molecule and/or is added during seed coating, and 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.

(2) Moreover, the coated seed according to the present invention is characterized in that the surface of the seed is coated with the seed coating agent described in (1) above.

(3) Furthermore, the seed coating method according to the present invention is characterized in that seeds are coated using the seed coating agent described in (1) above.

In the present invention, a seed coating agent containing iron-based powder and used to coat the surface of seeds, which contains one or more types of carboxylic acids having two or more carboxy groups in one molecule, and/or which is used to coat the surface of seeds. Uniform and smooth coated seeds can be obtained by adding the carboxylic acid at the time of coating, and by setting the amount of the carboxylic acid to the mass of metallic iron of the iron-based powder to be 0.01% by mass or more and 6% by mass or less. be able to.

The seed coating agent according to the embodiment of the present invention contains iron-based powder used to coat the surface of dry rice (seed rice) as an example of seeds, and contains two or more carboxylic acid powders in one molecule. containing one or more types of carboxylic acids having groups and/or added at the time of seed coating, and the amount of the carboxylic acid based on the mass of metallic iron of the iron-based powder is 0.01% by mass or more and 6% by mass. These are as follows.
Note that rice is preferably used as the seeds to be coated with the seed coating agent according to the present embodiment. 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 more clearly exhibited.

Next, the structure of the seed coating agent according to the present embodiment will be specifically explained.
<Iron-based powder>
The iron-based powder used in the seed coating agent according to the present embodiment contains iron powder, and mixtures of iron powder, iron oxide powder, and other metal powders can also be used. As the iron powder, pure iron, alloyed iron, or partial iron oxide powder can be used. Note that it is preferable that the amount of metallic iron in the iron-based powder be 20% by mass or more, more preferably 40% by mass or more from the viewpoint of rust formation in the coating layer when coated on seeds.

Examples of iron powder include those produced by the reduction method, in which mill scale, iron ore, etc. are reduced, and those produced by the atomization method, in which water or gas is sprayed at high speed into molten steel.

Examples of iron oxide include magnetite (Fe ₃ O ₄ ), hematite (Fe ₂ O ₃ ), wustite (FeO), and amorphous. The respective ratios are not particularly limited as long as they fall within the scope of the present invention. Note that from the viewpoint of economic efficiency, powders such as mill scale and iron ore are preferably used.

The seed coating agent according to this embodiment does not specify the amount of iron-based powder to be used, but the weight ratio to the seeds (dry rice grains) is preferably 5% or more and 800% or less, and more preferably 10% or more and 500% or less.

In addition, although the particle size of the iron-based powder is not particularly determined, by making the iron-based powder with a particle size of 150 μm or less account for 80% or more of the total iron-based powder mass, the surface of the seeds can be uniformly coated. It is preferable because it can form a layer. Note that the particle size distribution of the iron-based powder can be evaluated by sieving using the method specified in JIS Z2510-2004.

<Carboxylic Acid Having Two or More Carboxy Groups in One Molecule>
As described above, the seed coating agent according to the present embodiment contains one or more types of carboxylic acids having two or more carboxy groups in one molecule and/or is added during seed coating.
The form of the carboxylic acid is not particularly limited as long as it has two or more carboxy groups in one molecule, and carboxylic acids and/or their salts, anhydrides, hydrates, and isomers can be used. Two or more kinds of carboxylic acids can also be used in combination.

Examples of the carboxylic acid include citric acid, tartaric acid, malic acid, succinic acid, and ethylenediaminetetraacetic acid.
Examples of carboxylates 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 mono- to tetrasodium salts of ethylenediaminetetraacetic acid.
Examples of the metal carboxylate include iron citrate, calcium citrate, ammonium iron citrate, and ammonium iron ethylenediaminetetraacetate. However, metal salts other than iron can also be used and are within the scope of the present invention. In addition, these carboxylic acids, carboxylates, and metal carboxylates include anhydrides and hydrates.

When a carboxylic acid having two or more carboxyl groups in one molecule is contained or added, the reason why the coating layer becomes smooth is because the acid dissolves iron powder and because of its chelating effect, it contains a large amount of divalent iron. It is thought that iron is generated, stabilized, and spread over the entire seed surface, and then converts to trivalent iron and fixes it. The reason why the above reaction occurs is that when the seed coating agent of this embodiment is used, the coated seeds take on a green to black tone and then change from red to brown. It can be estimated.

On the other hand, carboxylic acids that have only one carboxy group in one molecule, such as acetic acid, do not have the ability to form chelate complexes, so although they promote the formation of rust, they do not stabilize divalent iron and are The expected effect of the present invention is insufficient because it is easily converted to trivalent iron by oxygen. It is also undesirable because it generates odor due to its high volatility and further oxidizes surrounding metal iron and iron oxides (wustite, magnetite).

Further, the amount of the carboxylic acid in the seed coating agent is 0.01% by mass or more and 6% by mass or less based on the mass of metallic iron in the iron-based powder. If it is less than 0.01% by mass, the effect of the present invention will be reduced, and if it exceeds 6% by mass, the chelate effect will make it more difficult for rust to progress, and the coating layer will become brittle due to the increase in components other than iron. Because it will be.
Note that the amount of carboxylic acid is calculated as a form of carboxy group (COOH) excluding water of hydration and cation components.

In addition, the seed coating agent in this embodiment may be one that already contains the above-mentioned carboxylic acid having two or more carboxy groups in one molecule, or one that is added at the time of coating. Specifically, the carboxylic acid may be mixed with other components of the seed coating agent, such as iron-based powder, before seed coating, or an aqueous solution of the carboxylic acid may be sprayed and added at the time of seed coating. Either method can be used. However, some carboxylic acids are irritating to the skin or eyes, or deliquescent, so it may be more effective to add them at the time of seed coating from the viewpoint of improving workability when using them and uniform mixing.

Furthermore, the seed coating agent according to the present invention may contain a binder and a third component described below.

<Binder>
The binder contained in the seed coating agent according to the present invention is preferably a sulfate and/or chloride that functions as an oxidation promoter. Sulfates are calcium sulfate, potassium sulfate, magnesium sulfate, and hydrates thereof. Furthermore, chlorides include potassium chloride, calcium chloride, magnesium chloride, and hydrates thereof.
In the seed coating agent according to the present invention, it is particularly preferable to use calcined gypsum (calcium sulfate, hemihydrate) or gypsum (calcium sulfate, dihydrate) as the binder. A mixture or mixture of calcined gypsum and plaster may be used.

The amount of binder used is not particularly specified, but in order to facilitate the progression of rust when the binder is applied to the seeds, it is preferable that the mass ratio of the binder to the iron powder contained in the seed coating agent be 0.1 to 33 mass%.
However, since the function of the binder is to facilitate the progression of rust, if there is no need to speed up the progression of rust, it is possible to obtain the effects of the present invention without adding a binder.

Further, the average particle size of the binder is not particularly limited, but 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 number of aggregated particles will be generated during the coating operation with a seed coating agent containing the binder, and the workability of removing these particles will be significantly reduced. On the other hand, when the average particle size of the binder exceeds 150 μm, the adhesion to iron powder decreases, the strength of the coating layer decreases, and peeling off from the seeds becomes noticeable.

<Third component>
The seed coating agent according to the present invention may contain a third component to an extent that does not impair the effects of the present invention, and the content of the third component is up to about 30% of the seed coating agent. is preferred.

<Coating Amount>
The amount of the seed coating agent to be applied to the seeds is not particularly limited, but may be 5 to 800 parts by mass per 100 parts by mass of dry seeds. In order to sink the coated seeds to the bottom of the water, it is more preferable to apply about 10 to 500 parts by mass.

<Separating agent>
In addition, a separating agent (finishing agent) may be used to prevent the seeds from fusing together during oxidation. Although a separating agent is not essential, when a separating agent is used, gypsum, silica gel, etc. can be preferably used.

<Seed coating method>
Next, a seed coating method using the seed coating agent according to the present embodiment will be described below.
The seed coating method according to the present embodiment uses the seed coating agent according to the present invention described above, and there is no particular limitation on the means for coating the seeds with the seed coating agent. For example, as shown in "Iron-Coated Flooded Direct Seeding Manual 2010 (compiled by Kinki Chugoku Shikoku Agricultural Research Center, National Agriculture and Food Research Organization)", any method may be used, including manual coating and the use of a conventionally known mixer.

Furthermore, when using a mixer to coat the seed coating agent, a mixer of impeller type (e.g., Henschel mixer, concrete mixer, etc.) or a container rotation type mixer (e.g., V-type mixer, double cone mixer, tilt rotation type pan mixer, rotary hoe type mixer, etc.) can be used. In addition, a concrete mixer with the impeller removed can be preferably used.

A specific method for coating seeds with the seed coating agent of this embodiment involves putting the seeds, iron-based powder, a carboxylic acid having two or more carboxy groups in one molecule (an organic acid capable of forming a chelate complex), and, if necessary, a binder and additives into the mixer described above, and coating the seeds while spraying water and/or a treatment liquid mainly composed of water.
In the above method, the seed coating is carried out by incorporating a required amount of carboxylic acid in the seed coating agent in advance. However, the carboxylic acid may be added by spraying it as an aqueous solution at the time of seed coating without mixing it in advance.
In addition, when seeds are coated using a seed coating agent that already contains a carboxylic acid, an aqueous solution of the carboxylic acid may be further added.

<Oxidation method>
There is no limit to the method of oxidizing the seed coating agent of this embodiment coated on seeds, but for example, "Iron Coating Direct Sowing Manual 2010" (edited by National Agriculture and Food Research Organization, Kinki-Chugoku-Shikoku Agricultural Research Center) ), a method of spreading seeds in a seedling box and sprinkling with water, or an oxidation method using an oxidation regulator may be applied.

Alternatively, a method may be used in which the seeds are fluidized and oxidized while water and air are supplied to a mixer (hereinafter referred to as the mixed oxidation method). The mixed oxidation method is more preferable because it can generate more divalent iron. The requirements for the mixed oxidation method are explained below.

For supplying air, a blower, a fan, various types of dryers, a hot air blower, etc. can be used.
The temperature of the air to be supplied is not particularly limited, but is preferably -20 to 200°C, more preferably 0 to 150°C, and even more preferably 46 to 100°C.
However, in order to maintain germination, the seed temperature should be kept below 50° C., more preferably below 40° C. Also, to prevent the seeds from freezing and to promote rusting, the seed temperature should be kept above 0° C., more preferably above 10° C.

There is no particular restriction on the speed of the air supplied, but 0.1 to 15 m/sec is preferred, and 0.5 to 10 m/sec is even more preferred. If it is less than 0.1 m/sec, oxidation and cooling will not proceed smoothly, and if it exceeds 15 m/sec, there is a risk that the seeds and seed coating agent will be scattered.

Water can be supplied either by adding it directly to the seeds or by adding it to the air. Examples include a method of spraying, atomizing, adding to seeds or the inside of a mixer using a container such as a cup, and a method of supplying as humidified air.

Although the moisture content is not particularly defined, it is preferably 10 to 1000% by mass, more preferably 20 to 500% by mass, and even more preferably 50 to 200% by mass based on the seed coating agent. If it is less than 10% by mass, rusting will be insufficient and the coating layer will peel off. If it exceeds 1000% by mass, there is a problem that the time required for drying becomes longer.
In addition, if a large amount of water is supplied at once, the seeds will clump together, so it is possible to keep the seeds flowing in the mixer, and to feed the seeds in multiple batches while keeping them wet. preferable.

The oxidation treatment by the mixed oxidation method described above is preferably carried out after the seeds are coated with the seed coating agent, but air is supplied together with water to the flowing seeds in the process of coating the seeds with the seed coating agent, and the coating treatment and oxidation treatment are carried out. You can do both at the same time.
After water and air are supplied, air is supplied directly inside the mixer, and the seeds are taken out after they have dried to some extent. Then, transfer it to a tray, spread it out, remove excess moisture, and dry it for storage.

As described above, according to the seed coating agent and seed coating method according to the present embodiment, coated seeds with improved coating layer uniformity and surface smoothness can be obtained.

An experiment was carried out to confirm the effect of the present invention, and the experiment will be described below.
In the experiment, rice seeds were coated with the seed coating agent according to the present invention, and an evaluation test of the coating layer was carried out.
The coating of the seed coating agent was carried out according to the method described in the above-mentioned "Iron-Coated Direct Seeding Manual 2010." In addition, two methods, a mixed oxidation method and a tray oxidation method, were used to oxidize the seed coating agent. Specifically, they are as follows.

For the mixed oxidation method, first, a seed coating agent was prepared by mixing the seeds in advance, and then, using an inclined rotating pan mixer, 100 g of seeds were coated with the seed coating agent in several batches while spraying an appropriate amount of water (or aqueous carboxylic acid solution). Next, the seeds were sprayed with about 40 to 50 g of water while air at about 60°C was supplied to the seeds using a hot air blower. Unless otherwise specified, tap water was used. The coated seeds were then spread out on a tray and allowed to dry naturally.

For the tray oxidation method, a seed coating agent was first prepared by mixing the seeds in advance, and then, using an inclined rotating pan mixer, the seed coating agent was coated in several batches per 100 g of seeds while spraying an appropriate amount of water, and finally, a separating agent (finishing agent) was applied. The coated seeds were then spread on a tray, and watered six times to allow for sufficient oxidation, after which they were allowed to dry naturally.

In this example, experiments were conducted by changing the types and amounts of iron powder, iron oxide powder, binder, and carboxylic acid, which are the raw materials of the seed coating agent.
Table 1 shows the type and content of each raw material contained in the seed coating agent used in the experiment, and Tables 2 to 5 show the type of each raw material used in the seed coating agent (Table 2: iron powder, Table 3: iron oxide, Table 4: binder, Table 5: carboxylic acid).

In Table 1, in Examples 1 to 21, seeds were coated using the seed coating agent according to the present invention. In Examples 1 to 21, except for Example 19, the carboxylic acid shown in Table 5 was mixed in advance with the seed coating agent, and in Example 19, the carboxylic acid aqueous solution was added during seed coating.
In addition, in all of Examples 1 to 21, the amount of carboxylic acid relative to the mass of metallic iron is 0.01 mass % or more and 6 mass % or less.

Furthermore, for comparison, seeds were coated using the seed coating agents of Comparative Examples 1 to 4 shown in Table 1.
Comparative Examples 1, 3 and 4 do not contain a carboxylic acid, and Comparative Example 2 contains a carboxylic acid, but the content is outside the range of the present invention.

The seeds coated with the seed coating agents according to the above-mentioned invention examples 1 to 21 and comparative examples 1 to 4 were subjected to evaluation tests for coating smoothness and coating strength. These evaluation tests were carried out as follows.

<Coating smoothness>
The coating state of the seed surface during dressing was visually evaluated.
As for coating smoothness evaluation, ◎ indicates that almost all of the coating is smooth, ○ indicates that some coated seeds are not smooth but there is no problem, and ○ indicates that coated seeds that are not smooth are noticeable and the coating effect is judged to be insufficient. The results were evaluated as △, and the results were evaluated as × when there were many coated seeds that were not smooth and the coating effect was judged to be low.

<Covering strength>
100 g of seeds were shaken for 1 minute using a sieve with a 2 mm opening and a low-tap sieve shaker, and the weight loss rate was measured.
As for evaluation of coating strength, a weight reduction rate of 1% or less was judged as ◎, more than 1% and less than 5% was judged as ○, more than 5% and less than 20% was judged as △, and more than 20% was judged as bad.

Table 1 shows that by using the seed coating agent of the present invention, the uniformity of the coating layer is improved compared to the comparative example, and coated seeds with excellent coating smoothness can be obtained. Furthermore, it can be seen that coated seeds with excellent coating strength can be obtained by setting the ratio of carboxylic acid to metal iron to be 0.01% by mass or more and 6% by mass or less.

As described above, it has been demonstrated that the seed coating agent, coated seeds, and seed coating method according to the present invention improve coating uniformity and surface smoothness and have excellent coating strength. This stabilizes the flow of seeds in the seeding machine and improves workability, making it possible to stabilize and improve rice cultivation.

Claims (3)

A seed coating agent containing an iron-based powder and used to coat a seed surface,
A seed coating agent comprising one or more types of carboxylic acids having two or more carboxy groups in one molecule and/or added during seed coating, characterized in that the amount of the carboxylic acids relative to the mass of metallic iron in the iron-based powder is 0.01 mass% or more and 6 mass% or less, the metallic iron in the iron-based powder is 20 mass% or more, and the particle size of the iron-based powder is such that iron-based powder having a particle diameter of 150 μm or less accounts for 80% or more of the total iron-based powder mass . A coated seed, the surface of which is coated with the seed coating agent according to claim 1. A method for coating seeds, which comprises coating seeds using the seed coating agent according to claim 1.