CN106535613B

CN106535613B - Coated rice seed and preparation method thereof

Info

Publication number: CN106535613B
Application number: CN201580039319.8A
Authority: CN
Inventors: 住田智子
Original assignee: Sumitomo Chemical Co Ltd
Current assignee: Sumitomo Chemical Co Ltd
Priority date: 2014-07-25
Filing date: 2015-07-17
Publication date: 2020-03-24
Anticipated expiration: 2035-07-17
Also published as: CN106535613A; PH12017500150A1; JP6830815B2; KR20170039188A; JPWO2016013506A1; WO2016013506A1; TW201613461A; KR102409814B1

Abstract

Disclosed is a coated rice seed having a coating layer on the surface of a rice seed, wherein the coating layer comprises iron oxide and at least one copolymer selected from the group consisting of a styrene-butadiene copolymer and a methyl methacrylate-butadiene-styrene copolymer, and the content of the iron oxide is 30-90% by weight relative to 100% by weight of the coated rice seed. Thus, it is possible to provide a coated seed which is less susceptible to bird damage and which does not have the problem of a reduced germination rate as in conventional iron coatings.

Description

Coated rice seed and preparation method thereof

Technical Field

The present invention relates to coated rice seeds and a method for producing the same.

Background

Direct rice seeding cultivation means a cultivation method by directly seeding rice seeds to a rice field, which has an advantage of saving agricultural labor because the method does not require some labor for raising seedlings and transplanting rice. However, this method has the disadvantage of being susceptible to feeding hazards (i.e., bird damage) by birds such as ducks and sparrows. A reduction in the seedling rate (estralishment percent) caused by bird damage decreases income, and thus strategies for avoiding bird damage are required. As a conventional strategy for avoiding bird damage, a method for preventing bird damage using water management has been proposed. However, the method is required to change the management system according to the type of bird (see, for example, non-patent document 1).

Further, iron-coated direct-irrigation seeding is known as a technical means for preventing feeding damage caused by sparrows by coating (coating) rice seeds with iron powder to suppress floating of the seeds in seeding on the soil surface (see, for example, non-patent document 2). However, since this technical means utilizes solidification of iron powder (due to its oxidation), there are some problems of burdensome tasks of managing the coated rice seeds such as the need to release heat generated by oxidation and some reduction in germination rate unless management is sufficient. A known solution to this problem is a coating method of rice seeds using polyvinyl alcohol having a high saponification value and a coating material such as iron oxide (see, patent document 1).

Reference list

Patent document

Patent document 1: JP 2013-146266A 1

Non-patent document

Non-patent document 1: nagao SAKAI and three other people, "Prevention of bird damage in direct sowing cultivation of flowable rice", The Hokuriku Crop Science, The Crop Science Society of Japan, 3.31.1999, Vol.34, p.59-61.

Non-patent document 2: minoru YAMAUCHI, "Amanual for direct watering of iron-coated rice a flood Paddy field 2010," The National Agriculture and Food Research Organization, Western RegionAgricural Research Center, 3 months 2010.

Summary of the invention (problems to be solved by the invention)

It is an object of the present invention to provide coated rice seeds that solve the problem of reduced germination rate in conventional iron coated rice seeds, which are less susceptible to bird damage.

(means for solving the problems)

The inventors of the present invention have intensively studied to find such a coated rice seed, and thus found a coated rice seed having a coating layer containing iron oxide and at least one copolymer selected from the group consisting of a styrene-butadiene copolymer and a methyl methacrylate-butadiene-styrene copolymer, and having an iron oxide content of 30 to 90% by weight with respect to 100% by weight of the coated rice seed, which is less susceptible to bird damage.

The present invention includes the following embodiments.

[1] A coated rice seed having a coating layer on a surface of a rice seed, wherein the coating layer contains iron oxide and at least one copolymer selected from the group consisting of a styrene-butadiene copolymer and a methyl methacrylate-butadiene-styrene copolymer, and the content of the iron oxide is 30 to 90% by weight with respect to 100% by weight of the coated rice seed.

[2] The coated rice seed as described in [1], wherein the glass transition point of the copolymer is 10 ℃ or less.

[3] A method for preparing coated rice seeds, comprising the steps of;

(1) adding iron oxide and at least one copolymer latex selected from the group consisting of styrene-butadiene copolymer latex and methyl methacrylate-butadiene-styrene copolymer latex to rice seeds while moving and rolling the seeds to attach the iron oxide to the surface of the rice seeds, and (2) drying the seeds obtained in the previous step.

[4] The method described in [3], wherein the step (1) is performed to repeat the step of adding iron oxide and the step of adding the copolymer latex while moving and rolling rice seeds to attach iron oxide to the surfaces of the rice seeds.

[5] The method described in [4], wherein a single addition amount (single addition amount) of the iron oxide is 1 to 1/20 of the weight of the rice seed, and the single addition amount of the copolymer latex is 1/10 to 1/1000 of the weight of the rice seed when converted to the weight of the copolymer.

[6] The method described in [4], wherein the single addition amount of the iron oxide is 5 to 100 parts by weight relative to 100 parts by weight of the rice seeds, and the single addition amount of the copolymer latex is 0.1 to 10 parts by weight relative to 100 parts by weight of the rice seeds when converted to the weight of the copolymer.

[7] The method described in any one of [3] to [6], which uses 100 to 1200 parts by weight of iron oxide with respect to 100 parts by weight of rice seeds.

[8] A coated rice seed produced by the method described in any one of [3] to [7 ].

[9] A method for cultivating rice, comprising the step of directly sowing the coated rice seed as described in [1], [2] or [8] to a paddy field.

Brief Description of Drawings

FIG. 1 is a schematic view for illustrating a procedure for preparing a test sample for determining the hardness of coated rice seeds of the present invention.

FIG. 2 is a schematic view for illustrating a procedure for determining the hardness of coated rice seeds of the present invention.

FIG. 3 is a schematic view illustrating a simple seed coater for coating rice seeds in examples.

Modes for carrying out the invention

The coated rice seed of the present invention (hereinafter, referred to as "coated rice seed of the present invention") has a coating layer containing iron oxide and at least one copolymer selected from the group consisting of a styrene-butadiene copolymer and a methyl methacrylate-butadiene-styrene copolymer (hereinafter, referred to as "copolymer of the present invention") on the surface of the rice seed.

As used herein, rice seed is intended to mean the seed of a rice variety that is commonly cultivated. Examples of the varieties include species such as Japonica (Japonica) subspecies and Indica (Indica) subspecies, and varieties having high lodging resistance (lodgingresistance) and germination rate are preferred.

As used herein, iron oxide is meant to contain iron consisting of Fe₂O₃Expressed as a substance containing an oxide of iron as a main component, and preferably as a substance containing α -Fe in a content of 70% or more (wt% based on the whole iron oxide)₂O₃Can be determined by XRD (X-ray diffraction method) α -Fe as used herein can be determined₂O₃The content of (a). Further, iron oxide is generally used as a powder of iron oxide, and is preferably used as iron oxide having a particle size distribution of 40% or less of particles having a size of 150 μm or more. As used herein, the particle size distribution of iron oxide means the distribution of particles as determined by sieving. The expression "a particle size distribution of 40% or less of particles having a size of 150 μm or more" means that the weight ratio of the remaining amount on a screen having a 150 μm mesh to the total amount of the powdery iron oxide used is 40% or less. The particle size distribution of the iron oxide can be determined by: 10g of iron oxide was placed in a containerThe iron oxide on the sieving device (e.g., Ro-Tap shaker) was vibrated on a sieve having a 150 μm mesh opening (defined by JIS Z8801-1), and then the weight amount of the iron oxide remaining on the sieve was weighed and then calculated according to the following formula.

The remaining amount on the screen (%) ((weight (g) of iron oxide remaining on the screen))/(weight (g) of iron oxide placed on the screen at the start of measurement)) × 100

The content of iron oxide is in the range of 30 to 90% by weight with respect to 100% by weight of the coated rice seeds of the present invention. An effect less susceptible to bird damage can be achieved by the above iron oxide content of 30 wt% or more. Meanwhile, the content of the iron oxide is preferably in the range of 50 to 90 wt%, 60 to 90 wt%, and 70 to 90 wt%. As used herein, the weight of the coated rice seed of the present invention means the total weight of the dried rice seed before coating, iron oxide, the copolymer of the present invention, and any optional components to be contained, wherein any optional components to be contained include the pesticidal active ingredient (pesticidal active ingredient) mentioned below, a colorant, and a surfactant.

Styrene-butadiene copolymers are copolymers composed of styrene and 1, 3-butadiene and are abbreviated to SBR, which is commonly referred to as synthetic rubber. Methyl methacrylate-butadiene-styrene copolymers are also generally known and are terpolymers composed of methyl methacrylate, 1, 3-butadiene and styrene, abbreviated to MBS. As used herein, the SBR may be used as an SBR having a carboxyl group (-COOH) in a molecule (hereinafter, referred to as "carboxyl-modified SBR"), and the MBS may be used as an MBS having a carboxyl group (-COOH) in a molecule (hereinafter, referred to as "carboxyl-modified MBS"), respectively. Further, the glass transition point (Tg) of the copolymer of the present invention is usually in the range of 10 ℃ or less, preferably-50 ℃ to 10 ℃, more preferably-30 ℃ to 0 ℃.

As used herein, the copolymers of the present invention are used in the form of a latex (latex). The latex is an aqueous dispersion of polymer microparticles, and the average particle size of the microparticles is usually 1 μm or less. As used herein, the average particle size of polymer microparticles in, for example, latex is determined using a laser diffraction/scattering type particle size distribution analyzer, and means the particle size thereof reaching a cumulative frequency of 50% in a frequency distribution on a volume basis. The content of polymer in the latex (solids content) is generally from about 40 to 70% (wt% relative to the latex). Commercially available SBR latex and MBS latex may be used as the copolymer latex of the present invention, and examples of the commercially available SBR latex and MBS latex include NALSTAR SR103 (carboxyl-modified SBR latex, Tg; 7 ℃ C., manufactured by NIPPON A & L INC.) and NALSTAR SR140 (carboxyl-modified SBR latex, Tg; 12 ℃ C., manufactured by NIPPON A & L INC.).

The content of the copolymer of the present invention is generally in the range of 0.1 to 6% by weight, and preferably 0.25 to 6% by weight, 1 to 6% by weight, and 3 to 4% by weight, relative to 100% by weight of the coated rice seed of the present invention.

The coating layer may contain an agrochemical active ingredient. Examples of the pesticidal active ingredient include an insecticidal active ingredient, a bactericidal active ingredient, a herbicidal active ingredient and a plant growth regulating active ingredient.

Examples of the pesticidal active ingredient include clothianidin (clothianidin), imidacloprid (imidacloprid), and thiamethoxam (thiamethoxam).

Examples of bactericidal active ingredients include isotianil (isotianil) and furametpyr (furametpyr).

Examples of the herbicidal active ingredient include imazosulfuron (imazosulfuron) and beflufenamid (bromobutamide).

Examples of plant growth regulating active ingredients include uniconazole p (uniconazole p).

As used herein, the pesticidal active ingredient may be used directly as such, or may be mixed with a solid carrier such as clay, and optionally ground with a grinder such as a dry mill to be used as a ground powder. The particle size of the pesticidal active ingredient is usually 200 μm or less, preferably 100 μm or less. As used herein, the particle size of the pesticidal active ingredient means a particle size determined using a laser diffraction/scattering type particle size distribution analyzer, reaching 100% of its cumulative frequency in a frequency distribution based on volume. When the pesticidally active ingredient is mixed with a solid carrier, the particle size of the pesticidally active ingredient means the particle size of the mixture. Examples of the laser diffraction/scattering type particle size distribution analyzer include LA-950V2 (manufactured by HORIBA, ltd.), and this analyzer is used to determine the particle size by dispersing particles of the pesticidal active ingredient into water, i.e., a wet measurement method.

When the coating layer contains a pesticidal active ingredient, the total content of the pesticidal active ingredient is generally in the range of 0.01 to 10% by weight, preferably 0.05 to 5% by weight, relative to 100% by weight of the coated rice seed of the present invention.

The coating layer may contain a coloring agent. Examples of the colorant include pigments, dyes and tints, and particularly, pigments are preferable. The pigment is preferably a red or blue pigment such as Nubix G-58 (blue pigment, manufactured by nubiola inc.) and TODACOLOR-300R (red pigment, manufactured by TODAKOGYO corp).

When the coating layer contains a colorant, the total content of the coating agent is generally in the range of 0.01 to 10% by weight, preferably 0.5 to 5% by weight, more preferably 1 to 5% by weight, relative to 100% by weight of the coated rice seed of the present invention.

In addition, a surfactant may be attached to the surface of the coating layer. The surfactant is preferably a nonionic surfactant, and the nonionic surfactant is preferably polyoxyethylene styrylphenyl ether. When the coated rice seed of the present invention is a coated rice seed in which a surfactant is attached to the surface of the coating layer of the coated rice seed of the present invention, the total content of the surfactant is usually in the range of 0.001 to 3% by weight, preferably 0.01 to 1% by weight, relative to 100% by weight of the coated rice seed of the present invention.

The coating layer may be prepared by: iron oxide and the copolymer latex of the present invention are added to rice seeds in a moving and rolling state to attach the iron oxide to the surface of the rice seeds, and the seeds are dried.

The method for preparing the coated rice seed of the present invention (hereinafter, referred to as "the preparation method of the present invention") includes a step of adding iron oxide and the copolymer latex of the present invention while moving and rolling the rice seed to attach the iron oxide to the surface of the rice seed (hereinafter, referred to as "step 1"), and a step of drying the seed obtained in the foregoing step (hereinafter, referred to as "step 2").

In the preparation method of the present invention, the seeds are usually soaked before performing step 1. In detail, dry rice seeds are put into a bag such as a rice seed bag and soaked in water. The seeds are preferably soaked in water at 15 to 20 ℃ for three to four days to prepare coated rice seeds having a high germination rate. The rice seeds are recovered from the water and typically left to stand or spin dry to remove excess water on the surface.

The obtained rice seeds were used to perform step 1. Step 1 includes a step of adding iron oxide (hereinafter, referred to as "step 1-1") to rice seeds (1-1) in a moving and rolling state and a step of adding the copolymer latex of the present invention (hereinafter, referred to as "step 1-2") to (1-2). Step 1-1 may be performed followed by step 1-2, and the order of step 1-1 and step 1-2 may be switched without any difficulty. Step 1-1 and step 1-2 may be performed simultaneously.

The device for moving and rolling the rice seeds may be a known device such as a coater. The total addition amount of iron oxide is usually 100 to 1,200 parts by weight relative to 100 parts by weight of dry rice seeds, and preferred ranges include 200 to 1,200 parts by weight and 400 to 1,000 parts by weight. The total addition amount of the copolymer latex of the present invention is generally 1 to 100 parts by weight with respect to 100 parts by weight of the dried rice seeds, and preferred ranges include 10 to 50 parts by weight and 16 to 40 parts by weight. In addition, the weight ratio of the copolymer of the present invention to iron oxide is usually in the range of 1: 10 to 1: 100, preferably 1: 25 to 1: 50.

Step 1 is described in detail. For step 1-1, iron oxide is added to the rice seeds in a moving and rolling state to spray the iron oxide on the rice seeds. For steps 1-2, the copolymer latex of the present invention is diluted with water as necessary and added to rice seeds in a moving and rolling state to spray the copolymer latex of the present invention on the rice seeds. When the copolymer latex of the present invention is diluted with water, the latex is diluted so that the solid content of the latex may be in the range of 20 to 65%, preferably 30 to 60%, more preferably 30 to 40%. The method for adding the copolymer latex of the present invention includes dropping and spraying. Further, the preparation method of the present invention allows a uniform coating layer to be formed on the surface of rice seeds by repeating steps 1-1 and 1-2 while moving and rolling the rice seeds. When step 1 is a step of attaching iron oxide to the surface of rice seeds by repeating steps 1-1 and 1-2 while moving and rolling the rice seeds, the copolymer latex of the present invention and iron oxide are separately added. In this case, the single addition amount of iron oxide is usually about 1 to 1/20, that is, an amount equivalent to about 1/20, preferably about 1/2 to 1/6, based on the weight of the dried rice seeds, and the single addition amount of the copolymer latex of the present invention is usually about 1/10 to 1/1,000, preferably about 1/10 to 1/200, more preferably about 1/50 to 1/150, based on the weight of the copolymer of the present invention. That is, the single addition amount of iron oxide is generally about 5 to 100 parts by weight, preferably about 16.7 to 50 parts by weight, relative to 100 parts by weight of the dry rice seed, and when converted to the weight of the copolymer of the present invention, the single addition amount of the copolymer latex of the present invention is generally 0.1 to 10 parts by weight, preferably 0.5 to 10 parts by weight, more preferably 0.67 to 2 parts by weight, relative to 100 parts by weight of the dry rice seed. Here, as used herein, the single addition amount of the copolymer latex of the present invention means the total addition amount for attaching the single addition amount of iron oxide to rice seeds. Any one of the step 1-1 and the step 1-2 may be performed according to the state of the coating without alternately performing the step 1-1 and the step 1-2. In a preferred embodiment of the production method of the present invention, step 1-1 and step 1-2 are repeatedly performed in the range of 16 to 40 times. In the production method of the present invention, water alone may be added as necessary. The total amount (by weight) of water added is generally in the range of 1/2 to 1/100, preferably 1/3 to 1/30, of the total amount (by weight) of iron oxide added. Meanwhile, the total added amount of water contains the amount of water used for diluting the copolymer latex of the present invention.

In step 1, when iron oxide adheres to the inner wall of the apparatus, approximately the entire amount of the added iron oxide may be adhered to the surface of the rice seeds by scraping the iron oxide with a scraper. When the pesticidal active ingredient and the colorant are added, iron oxide is usually added together with them in step 1. Further, by adding a surfactant to the rice seeds in a moving and rolling state after a given amount of iron oxide is attached to the surface of the rice seeds, the surfactant can be attached to the surface of the coating layer formed on the surface of the rice seeds.

After step 1, step 2 is performed. Specifically, after step 1, the rice seeds are recovered from the apparatus, placed in a seedling box to thinly spread therein and left to dry. Rice seeds are typically dried to a water content of less than 20% (wt.% relative to the coated rice seeds). As used herein, the water content of the coated rice seeds means a value measured by using an infrared hygrometer after 10g of the sample is dried at 105 ℃ for one hour. FD-610 manufactured by Kett Electric Laboratory may be used as an infrared hygrometer. In step 2, a grass mat or a vinyl sheet may be used instead of the seedling box to thinly spread thereon and left to dry.

The above prepared coated layer of the coated rice seed produces an effect less susceptible to bird damage in direct seeding of rice on a irrigated paddy field because the coated layer has a certain hardness in a wet state. The hardness of the coating layer of the coated rice seeds of the present invention in a wet state can be determined using the following procedure.

(I) The coated rice seeds in a dry state (water content of 20% or less) were cut in half with a cutter. At this time, the rice seeds b are cut along the arrows a as shown in fig. 1.

(II) removing a brown rice portion from the half-cut coated rice seeds to obtain a test piece consisting of only the coating layer and the rice hulls.

(III) the test piece was put in a Petri dish (petri dish) to be completely soaked in water, left to stand for 30 minutes in a completely soaked state, and recovered from the water, followed by wiping off the water adhered to the surface of the test piece, to obtain a test piece c in a wet state.

(IV) for test piece c in a wet state, hardness was measured using a simple particle hardness tester manufactured by Tsutsui scientific Instrument co., ltd, according to the following procedure, provided that a tapered pressure bar was used in the measurement used herein.

(IV-I) As shown in FIG. 2, the test piece c is placed on the sample stage d so that the cut section can be placed in a downward direction, and the pressing lever e is removed with the pressing handle turned to position the test piece c in the middle portion.

(IV-II) record the hardness indicated by the pointer when the test piece c was crushed and then the pointer was returned by slowly turning the handle.

(IV-III) six more test pieces c were measured as described above, and the arithmetic mean value calculated from five points excluding the maximum value and the minimum value was defined as the hardness of the coating layer.

The hardness of the coating layer of the coated rice seed of the present invention determined by the above method is generally 500g or more, and preferably 500 to 2,500g and 700 to 1,500 g.

The method for cultivating rice of the present invention (hereinafter, referred to as "the cultivation method of the present invention") is performed by directly sowing the coated rice seeds of the present invention to a rice field. As used herein, a paddy field means any one of a flooded paddy field and a drained paddy field. Specifically, sowing was carried out according to The method described in Minoru Yamauchi, "A manual for direct soil of iron-coated rice a flood Paddy field 2010," The national agricultural and Food Research Organization, Western Region agricultural Research Center, 3 months 2010. At this time, a direct seeder for iron coating such as tetsumakiichan (product name) (manufactured by Kubota Corporation) may be used. After sowing, good cultivation is achieved by maintaining standard cultivation conditions.

In the cultivation method of the present invention, pesticides and fertilizers may be applied before, simultaneously with or after sowing. Pesticides include fungicides, insecticides, herbicides, and the like.

Examples

The present invention is described in more detail by examples.

First, the preparation examples and comparative preparation examples are described.

For the following preparations and comparative preparation, as rice seeds, seeds of the hindhikari variety were used, and α -Fe was used₂O₃Iron oxide containing 78% and having a ratio of particles having a size of 150 μm or more of 18.0%. Unless otherwise stated, the preparation is carried out at room temperature (about 15 ℃).

Further, trade names used in the preparation examples and comparative preparation examples are as follows.

NALSTAR SR 140: carboxyl modified SBR latex, Tg; -12 ℃, solids content; 48.5%, manufactured by NIPPON A & LINC.

NALSTAR SR103, 103: carboxyl modified SBR latex, Tg; 7 ℃, solid content; 48.2%, manufactured by NIPPON A & LINC.

SHOKOZAN clamp S: agalmatolite (talc), manufactured by SHOKOZAN minising co.

KURARAY POVAL PVA 117S: polyvinyl alcohol, degree of saponification; 98.0 to 99.0 mol%, manufactured by KURARAY co.

Mowinyl 180E: copolymer latex consisting of vinyl acetate and ethylene, Tg; -15 ℃, solids content; 55%, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.

Mowinyl 987B: acrylic resin latex, Tg; -2 ℃, solids content; 42%, manufactured by Nippon synthetic chemical industries, Ltd.

Preparation example 1

First, 33g of NALSTAR SR140 and 16g of water were mixed to obtain 49g of NALSTAR SR140 aqueous diluted solution.

About 1L of water was poured into a beaker made of polypropylene having a capacity of 2L, and 100g of dried rice seeds were added thereto, followed by soaking for 10 minutes. The rice seeds were then recovered from the water, excess water adhered to the surface was removed, and then the rice seeds were loaded into a drum of a seed coater (KC-151, manufactured by keibussa-Seisakusyo co., Ltd). The drum is adjusted so that the tilt angle (elevation angle) can be 45 degrees. The seed coater was rotated at 21.9rpm (constant speed), after which about 1/16 (about 25g) of 400g of iron oxide was added to attach the iron oxide to the rice seeds while about 1/16 (about 3g) of the solution was diluted with 49g of NALSTAR SR140 water sprayed with an atomizer. When iron oxide adheres to the inner wall of the drum, the iron oxide is scraped with a dustpan (dustpan) so as to adhere to the rice seeds by approximately the entire amount of the iron oxide added at a single time. The procedure of adding about 25g of iron oxide was repeated a total of 16 times while spraying 3g of NALSTAR SR140 aqueous dilution solution with an atomizer under rolling the seed coater to attach 400g of iron oxide to the surface of the rice seeds. Thereafter, the coated rice seeds were then spread on stainless steel trays so as not to overlap and dried at room temperature for 2 days, obtaining coated rice seeds 1 (hereinafter, referred to as "coated rice seeds 1 of the present invention"). The respective contents of iron oxide and the copolymer of the present invention were 77.5% by weight and 3.1% by weight, respectively, with respect to 100% by weight of the coated rice seed 1 for comparison, and the hardness of the coating layer in the coated rice seed 1 of the present invention was 830 g.

Preparation example 2

First, a simple seed coater for coating a small amount of rice seeds used was constructed. As shown in fig. 3, a simple seed coater was constructed by: a cup 2 made of polyethylene having a capacity of 500mL is fixed to the tip of a shaft 1, inserted into a driving shaft of a vibrator 3 (three-motor, manufactured by Shinto Scientific co., ltd.) and fixed on a base 4 so that the vibrator 3 can be opened at an elevation angle of 45 degrees.

Seventy-point zero (70.0) parts by weight of (E) -1- (2-chloro-1, 3-thiazol-5-yl-methyl) -3-methyl-2-nitroguanidine (nitroguanidine) and 30.0 parts by weight of SHOKOZAN CLAY S were mixed and ground with a centrifugal grinder to obtain a ground pesticide a. The particle size of the ground pesticide a was 68.0 μm as measured by a wet method using LA-950V2 (manufactured by HORIBA, ltd.). Zero point eight six (0.086) g of ground pesticide a and 80g of iron oxide were mixed to obtain 80.086g of mixture a.

Further, 6.6g of NALSTAR SR140 and 3g of water were mixed to obtain 9.6g of NALSTAR SR140 aqueous diluted solution.

To a cup made of polyethylene having a capacity of 200mL, about 100mL of water was poured, and 20g of dried rice seeds were added thereto, followed by soaking for 10 minutes. The rice seeds were then recovered from the water, excess water adhered to the surface was removed, and then the rice seeds were loaded into the polyethylene-made cup 2 fixed to the constructed simple seed coater. The simple seed coater was operated at a rotation speed ranging from 130 to 140rpm in the vibrator 3, and then about 1/16 (about 5g) of 80.086g of the iron oxide mixture a was added to the surface of the rice seeds while about 1/16 (about 0.6g) of NALSTARSR140 aqueous diluted solution was added dropwise to the surface of the rice seeds using a dropper to attach iron oxide to the rice seeds. When the iron oxide mixture a was attached to the inner wall of the cup 2 made of polyethylene, the iron oxide mixture a was scraped with a spatula to attach approximately the entire amount of the iron oxide mixture a by a single addition to the rice seeds. While about 0.6g of NALSTAR SR140 aqueous diluted solution was added dropwise to the rice seeds using a dropper under the condition of rolling the simple seed coater, the procedure of adding about 5g of iron oxide mixture a was repeated a total of 16 times to attach 80.086g of iron oxide mixture a to the surface of the rice seeds. The coated rice seeds were spread on a stainless steel tray so as not to overlap and dried overnight, thereby obtaining coated rice seeds 2 of the present invention (hereinafter, referred to as "coated rice seeds 2 of the present invention"). The content of each of iron oxide and the copolymer of the present invention was 77.5% by weight and 3.1% by weight, respectively, with respect to 100% by weight of the coated rice seed 2 of the present invention, and the hardness of the coating layer in the coated rice seed 2 of the present invention was 980 g.

Preparation example 3

Coated rice seeds 3 of the present invention (hereinafter, referred to as "coated rice seeds 3 of the present invention") were obtained according to a procedure similar to that of preparation example 2, except that NALSTAR SR103 was used in place of NALSTAR SR140 and 80g of iron oxide was used in place of 80.086g of mixture A. The content of each of iron oxide and the copolymer of the present invention was 77.5% by weight and 3.1% by weight, respectively, with respect to 100% by weight of the coated rice seeds 3 of the present invention, and the hardness of the coating layer in the coated rice seeds 3 of the present invention was 588 g.

Preparation example 4

Thirteen-point two (13.2) NALSTAR SR140 were mixed with 6g of water to obtain 19.2g of a NALSTARSR140 aqueous diluted solution.

Coated rice seeds 4 of the present invention (hereinafter, referred to as "coated rice seeds 4 of the present invention") were obtained according to a procedure similar to that of preparation example 2, except that 19.2g of the above NALSTAR SR140 aqueous diluted solution was used instead of 9.6g of the NALSTAR SR140 aqueous diluted solution, and 160g of iron oxide was used instead of 80.086g of mixture a. However, in addition, while about 1/32 (about 0.6g) of 19.2g of NALSTAR SR140 aqueous diluted solution was added dropwise to the surface of the rice seeds using a dropper under the condition of rolling the simple seed coater, the operation of about 1/32 (about 5g) to which 160g of iron oxide was added was repeated a total of 32 times to attach 160g of iron oxide to the surface of the rice seeds. The content of each of iron oxide and the copolymer of the present invention was 85.8% by weight and 3.4% by weight, respectively, with respect to 100% by weight of the coated rice seeds 4 of the present invention, and the hardness of the coating layer in the coated rice seeds 4 of the present invention was 1,100 g.

Preparation example 5

Sixteen point five (16.5) NALSTAR SR140 were mixed with 8g of water to obtain 24.5g of a NALSTARSR140 aqueous diluted solution.

Coated rice seeds 5 of the present invention (hereinafter, referred to as "coated rice seeds 5 of the present invention") were obtained according to a procedure similar to that of preparation example 2, except that 24.5g of the above NALSTAR SR140 aqueous diluted solution was used instead of 9.6g of the NALSTAR SR140 aqueous diluted solution, and 200g of iron oxide was used instead of 80.086g of mixture a. However, in addition, while about 1/40 (about 0.6g) of NALSTAR SR140 aqueous diluted solution of 24.5g was added dropwise to the surface of the rice seeds using a dropper under the condition of rolling the simple seed coater, the operation of about 1/40 (about 5g) to which 200g of iron oxide was added was repeated a total of 40 times to attach 200g of iron oxide to the surface of the rice seeds. The content of each of iron oxide and the copolymer of the present invention was 87.7% by weight and 3.5% by weight, respectively, with respect to 100% by weight of the coated rice seeds 5 of the present invention, and the hardness of the coating layer in the coated rice seeds 5 of the present invention was 2,060 g.

Comparative preparation example 1

Ten (10) g of iron oxide and 0.1g of KURAAY POVAL PVA117S were mixed to obtain 10.1g of mixture B.

About 100mL of water was poured into a cup made of polyethylene having a capacity of 200mL, and 20g of dried rice seeds were added thereto, followed by soaking for 10 minutes. Thereafter, rice seeds were recovered from the water, excessive water attached to the surface was removed, and then the rice seeds were loaded into the cup 2 made of polyethylene fixed to the build simple seed coater constructed in preparation example 2. The simple seed coater was operated at a rotation speed ranging from 130 to 140rpm in the vibrator 3, and then 10.1g of about 1/4 (about 2.5g) of the mixture B was added while spraying water with the atomizer to attach the mixture B to the rice seeds. When the mixture B was attached to the inner wall of the cup 2 made of polyethylene, the mixture B was scraped with a spatula so as to be attached to the rice seeds by about the entire amount of the mixture B added at a single time. The operation of adding about 2.5g of the mixture B was repeated a total of 4 times while spraying water with the atomizer under the condition of rolling the simple seed coater to attach 10.1g of the mixture B to the surface of the rice seeds. A total of 1.1g of water was used. The coated rice seeds were then spread on stainless steel trays so as not to overlap and dried overnight, to obtain coated rice seeds 1 for comparison (hereinafter, referred to as "comparative coated rice seeds 1"). The contents of iron oxide and PVA were 99.0 wt% and 1.0 wt%, respectively, with respect to 100 wt% of the comparative coated rice seed 1, and the hardness of the coating layer in the comparative coated rice seed 1 was 70 g.

Comparative preparation example 2

Five eighty (5.8) g of Mowinyl180E and 5.1g of water were mixed to obtain a 10.9g aqueous diluted solution of Mowinyl 180E.

Coated rice seed 2 for comparison (hereinafter, referred to as "comparative coated rice seed 2") was obtained according to a procedure similar to that of preparation example 2, except that 10.9g of the above Mowinyl180E aqueous diluted solution was used instead of 9.6g of NALSTAR SR140 aqueous diluted solution, and 80g of iron oxide was used instead of 80.086g of mixture a. The respective contents of iron oxide and the copolymer of the present invention were 77.5 wt% and 3.1 wt%, respectively, with respect to 100 wt% of the comparative coated rice seed 2, and the hardness of the coating layer in the comparative coated rice seed 2 was 258 g.

Comparative preparation example 3

Seven and six (7.6) g of Mowinyl987B and 4.1g of water were mixed to obtain 11.7g of an aqueous diluted solution of Mowinyl 987B.

Coated rice seeds 3 for comparison (hereinafter, referred to as "comparative coated rice seeds 3") were obtained according to a procedure similar to that of preparation example 2, except that 11.7g of the above aqueous diluted solution of Mowinyl987B was used instead of 9.6g of the NALSTAR SR140 aqueous diluted solution, and 80g of iron oxide was used instead of 80.086g of mixture a. The respective contents of iron oxide and the copolymer of the present invention were 77.5% by weight and 3.1% by weight, respectively, with respect to 100% by weight of the comparative coated rice seed 3, and the hardness of the coating layer in the comparative coated rice seed 3 was 95 g.

Next, test examples are shown.

Test example 1

A nursery box (inner diameter of 57.0x 34.5x 6.0cm) was filled with soil and irrigated, followed by sowing 100 coated rice seeds. And standing the seedling raising box in a farmland. The number of coated rice seeds remaining three days after sowing was counted, and then the remaining rate was calculated according to the following formula.

Remaining rate (%) — number of coated rice seeds remaining three days after sowing/100 × 100

The results are shown in table 1. Rice seeds (as a control) represent uncoated rice seeds and the remaining rate is less than 10% due to feeding hazards caused by birds such as sparrows.

[ Table 1]

	Residual ratio (%)
		Coated rice seed 1 of the invention	92
Coated rice seed 3 of the invention	84
		Coated rice seed 4 of the invention	100
Coated rice seed 5 of the invention	100
		Comparative coated Rice seed 1	<10
Comparative coated Rice seed 2	<10
		Comparative coated rice seed 3	<10
Rice seed (as control)	<10

Description of the reference numerals

a arrow head

b rice seeds

c test piece

d sample stage

e pressure bar

1 axle

2 cup made of polyethylene

3 vibrator

4 base

Claims

1. A method for preparing coated rice seeds, comprising the steps of;

(1) adding iron oxide and at least one copolymer latex selected from the group consisting of styrene-butadiene copolymer latex and methyl methacrylate-butadiene-styrene copolymer latex to rice seeds while moving and rolling the seeds to attach the iron oxide to the surface of the rice seeds, and (2) drying the seeds obtained in the previous step,

wherein the step (1) is performed to repeat the step of adding iron oxide and the step of adding the copolymer latex while moving and rolling rice seeds to attach iron oxide to the surfaces of the rice seeds, and

the single addition amount of iron oxide is 1 to 1/20 of the weight of rice seeds, and when converted to the weight of the copolymer, the single addition amount of the copolymer latex is 1/10 to 1/1000 of the weight of rice seeds.

2. The method of claim 1, which uses 100 to 1200 parts by weight of iron oxide with respect to 100 parts by weight of rice seeds.

3. The method of claim 1, wherein the copolymer has a glass transition point of 10 ℃ or less.

4. A method for cultivating rice, comprising the step of directly sowing the coated rice seeds prepared according to the method of claim 1 to a paddy field.