JP2013146266A - Propagated body coating, cultivation method, and method of manufacturing the propagated body coating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coated seed superior in water resistance, and a method of manufacturing the same.SOLUTION: Provided is a method of manufacturing a propagated body coating that includes the following: a step of mixing polyvinyl alcohol as a granular solid whose saponification degree is 78 mol.% or more with functional materials without being substantially melted, and forming, by using a liquid, a coating layer containing the polyvinyl alcohol, functional materials, and liquid on the surface of the propagated body coating; and a step of drying the coating layer.

Description

  The present invention relates to a propagation material coating excellent in water resistance, a cultivation method, and a production method of the propagation material coating.

  Rice is one of the three largest crops in the world, and rice is an important crop with the largest acreage in Japan. In general rice cultivation in Japan today, seedlings grown in seedling boxes are planted in Honda, which is more expensive than rice cultivation in other countries, and cost reduction is desired. . Farmers are also aging and labor saving is required. Thus, from the viewpoint of realizing cost reduction and labor saving of rice cultivation, direct sowing in which rice seeds are directly sown in Honda has been attracting attention.

  However, in direct sowing, direct seeding sowing seeds in paddy fields after paddy and paddling tends to make seedling establishment unstable, and the cause is generally considered to be lack of oxygen. Further, Non-Patent Document 1 describes that the cause is soil reduction in which a substance that receives electrons instead of oxygen is consumed after oxygen in the soil disappears.

  Accordingly, in direct sowing of flooded water, for the purpose of improving seedling establishment, a method of covering the seed surface with a material that stabilizes seedling establishment such as an oxygen generating agent is prevalent before sowing (Non-Patent Document 2). ).

  In addition, in order to avoid the occurrence of bird damage and floating seedlings, a method of sowing seeds coated with iron or the like on the surface of soil where oxygen deficiency does not occur has been attempted (Patent Document 1).

JP 2005-192458 (released July 21, 2005)

Motoyuki Sugawara, Special Research Report No. 20 of Ishikawa Prefectural Agricultural College, “Study on seedling emergence and seedling in direct sowing of paddy rice in flooded soil”, March 1993 Ministry of Agriculture, Forestry and Fisheries Ninth Review Meeting Document 1, “Current status of direct sowing technology for rice”, p. 13, March 2008 (http://www.maff.go.jp/j/study/kome_sys/09/pdf/data1.pdf) Furuhata et al. 2008, Effects of different paste components in iron oxide-coated seeds on the emergence and seedling establishment of flooded direct sowing rice, Hokuriku Crop Science Report 43, 15-18

  However, in the method using a material such as an oxygen generating agent, the cost for the material to be coated is high, and the amount of the material necessary for the seed is large, so that it takes time and effort for the coating.

  In addition, in the method using iron or the like, seeds must be sown in the first place, and if seeds are submerged in the soil, seedling reduction occurs.

  As a result of the study by the present inventor, one of the causes of both the fact that seedling establishment is not stable unless a large amount of oxygen generator or the like is coated, and that the seedling establishment in soil decreases when iron is coated Was also found to be due to gypsum used as a binder.

  Furthermore, in the coating using iron, a hard coating layer is formed by the bonding effect by the oxidation of reduced iron promoted by gypsum in addition to the bonding effect by gypsum, but heat generation is large in the oxidation process of reduced iron, and cooling work And the need for seed deterioration due to heat.

  However, gypsum is an inexpensive, strong and water-stable binder, and no alternative binder is found. For example, seed coatings using PVA (polyvinyl alcohol) or CMC (carboxymethyl cellulose), which are other typical binders, have been studied. If put in, the coating will collapse. For this reason, there is a problem that the evaluation of holding the material on the seed in the flooded soil is poor and is not practical (Non-patent Document 3).

  In addition, although there is PVA to which water resistance is imparted, since such PVA is inferior in water solubility, it is necessary to prepare a highly viscous solution by dissolving PVA in water under heating (80 to 90 ° C.) in advance. Don't be. Therefore, heating work is required and workability is poor. Moreover, there is a concern that seeds are damaged by using a high-temperature solution.

  The present invention has been made in view of the problems of the above-described conventional techniques, and the object thereof is to provide a propagation material coating (coated seeds, etc.) excellent in water resistance using PVA, and its simplicity. Is to provide a simple manufacturing method.

  The inventors of the present application have made extensive studies to solve the above problems. As a result, it has been found that by using polyvinyl alcohol (PVA) having a predetermined saponification degree or more as a solid, it is possible to easily produce a propagation material coating (coated seeds, etc.) excellent in water resistance, and arrived at the present invention. It came to do.

That is, the present invention provides one of the following as one aspect thereof.
(1) A polyvinyl alcohol which is a particulate solid and has a saponification degree of 78 mol% or more is mixed with a functional material without being substantially dissolved, and using the liquid, the polyvinyl alcohol, the functional material, and A method for producing a propagation material covering, comprising the steps of: forming a coating layer containing a liquid on the surface of a plant propagation material; and drying the coating layer.
(2) The step of forming the coating layer on the surface of the plant propagation body is as follows: 1) Contacting the plant propagation body with a suspension obtained by suspending the polyvinyl alcohol and the functional material in the liquid, or 2) The production method according to (1), wherein the polyvinyl alcohol and the functional material are mixed in a dry state, and then the obtained mixture is adhered to the surface of the plant propagation body via the liquid.
(3) The production method according to (1) or (2), wherein the saponification degree of the polyvinyl alcohol is in a range exceeding 90 mol%.
(4) The production method according to any one of (1) to (3), wherein the degree of saponification of the polyvinyl alcohol is in the range of more than 90 mol% and less than 98 mol%.
(5) The production method according to any one of (1) to (4), wherein the degree of polymerization of the polyvinyl alcohol is in the range of 1000 or more and 5000 or less.
(6) The production method according to any one of (1) to (5), wherein the degree of polymerization of the polyvinyl alcohol is in the range of 1500 or more and 3500 or less.
(7) The production method according to any one of (1) to (6), wherein a particle diameter of the polyvinyl alcohol is 150 μm or less.
(8) The polyvinyl alcohol according to any one of (1) to (7), which is used within a range of 0.02% by weight to 10% by weight with respect to the weight of the functional material. Production method.
(9) The production according to any one of (1) to (8), wherein the functional material is at least one selected from the group consisting of molybdenum material, tungsten material, iron material, oxygen generator, and clay. Method.
(10) The molybdenum material is at least one selected from the group consisting of molybdenum metal, molybdenum oxide, molybdic acid and its salt, molybdophosphoric acid and its salt, molybdosilicate and its salt, and the tungsten material is tungsten It is at least one selected from the group consisting of metal, tungstophosphoric acid and its salt, tungstosilicic acid and its salt, tungsten oxide, and tungstic acid and its salt, and the iron material is at least one of iron oxide and reduced iron And the oxygen generator is a material containing calcium peroxide (CaO ₂ ) as a functional component.
(11) The manufacturing method according to (9) or (10), wherein the iron material includes iron oxide having a particle size of 1 μm or less in a proportion of 5 wt% or more and 50 wt% or less.
(12) The production method according to any one of (1) to (11), wherein the plant propagation material is a seed.
(13) A propagation material covering produced by the production method according to any one of (1) to (12) above.
(14) A method for cultivating a plant, comprising a planting step for planting the propagation material covering according to (13).
(15) The method for cultivating a plant according to (14), wherein the plant has a period in which at least a part of the plant body is in a flooded state between the planting step and the seedling establishment period.

  ADVANTAGE OF THE INVENTION According to this invention, the propagation body coating | coated (coated seed) excellent in water resistance using PVA can be provided, and its simple manufacturing method can be provided.

It is a figure which shows the result of the water resistance test in Example 1. It is a figure which shows the result of the water resistance test in Example 7-1. It is a figure which shows the result of the water resistance test in Example 8-2.

[1. (Producing method of breeding material covering)
In the method for producing a propagation material covering according to the present invention, a polyvinyl alcohol which is a particulate solid and has a saponification degree of 78 mol% or more is mixed with a functional material without substantially dissolving it, and a liquid is used. The method includes a step of forming a coating layer containing polyvinyl alcohol, a functional material, and a liquid on the surface of the plant propagation body (covering layer forming step), and a step of drying the coating layer (drying step). It is.

  The coating layer is formed by attaching a mixture of PVA and a functional material to the outer surface of the plant propagation body by the coating layer forming process, and appropriately adjusting the liquid content of the coating layer on the plant propagation body by the drying process. Can be stabilized. In the production method according to the present invention, generally, PVA having low water solubility, which is required to be preheated and melted at a high temperature such as 70 ° C. to 90 ° C., is mixed with a functional material in the form of a particulate solid to propagate plants. One of the features is that a covering layer is formed on the body.

  One of the functions of the liquid is to make PVA and a functional material adhere to and adhere to the seed surface. Various liquids can be used as the liquid if it is difficult to damage the plant propagation body. Specifically, for example, water or a hydrophilic solvent can be used to sterilize the seed surface, and fast drying ethanol is exemplified. Of these, water is preferable from the viewpoint of cost. Functional materials and PVA will be described later.

  The method for performing the coating layer forming step is not particularly limited. Specifically, for example, 1) The particulate functional material and the particulate PVA are sufficiently mixed, and a plant propagation body such as a seed is added thereto. In addition, a method of forming a plastic coating layer on the surface of a plant propagation body while adding an appropriate amount of liquid (water, etc.) using a sprayer or the like, 2) a particulate functional material, particulate PVA, and Mix the liquid in suspension, stir it, add plant propagation material such as seeds to it, and add additional materials other than liquid to reduce the water content relatively, and the plastic coating layer 3) Until suspension and stirring, the same as 2), and then with heat, ventilation, and / or leaving (other storage and transport work, etc. as time passes) The process of gradually lowering the moisture content is also included in the category of neglected) The method of forming the plastic covering layer is as follows. 4) The process is the same as in 2) until it is suspended and stirred. Then, the plant propagation material is removed from the liquid, and the plastic coating layer is removed from the plant propagation material. 5) Method of forming on the surface 5) Preliminarily apply a liquid to the surface or the inside of the plant propagation body (for example, let the plant propagation body absorb water), and then spray the particulate functional material and the particulate PVA And a method of forming a plastic covering layer on the surface of a plant propagation material. However, the plant propagation material may be mixed with a functional material from the beginning, or may be mixed with the functional material after the plant propagation material is sufficiently moistened in advance. These may be mixed at the same time, or the order may be appropriately changed.

  In addition, although the kind of materials other than the liquid used in said 2) is not specifically limited, For example, at least one (preferably both) of particulate functional material and particulate PVA is mentioned.

  In the coating layer forming step, “without substantially dissolving PVA” is synonymous with the fact that PVA remains in the form of particulate solid (note that the form of particulate solid is maintained). And a state in which the surface of the PVA particles is partially dissolved is also included). Specifically, for example, it is intended not to expose PVA under a temperature at which PVA having a saponification degree of 78 mol% or more is sufficiently dissolved, and more specifically, for example, not to be exposed to a high temperature of 70 ° C. or more. Intended. In addition, it is preferable not to expose PVA to the temperature of 50 degreeC or more, and it is more preferable not to expose to the temperature of 40 degreeC or more.

  In the coating layer forming process, it is not necessary to dissolve PVA in a liquid under heating to form a highly viscous solution, and it is a method of using it as a particulate solid. It is simple. However, since the PVA to be used is originally melted at a high temperature, it may be preferable to use the functional material to be coated, the plant propagation material, or the liquid without cooling, and the work is not hindered. It may be preferable that the functional material, the plant propagation material, or the liquid is preheated to (for example, about 30 ° C.).

  The drying step is performed simultaneously with the coating layer forming step or after the coating layer forming step. Although the method of performing a drying process is not specifically limited, For example, the method of evaporating a liquid from the coating layer formed at the coating layer formation process by forced drying or natural drying is mentioned, for example. The drying step may also be a step of gradually reducing the liquid content of the coating layer with the passage of time in combination with other operations such as storage or transportation. The drying step may also be a step of reducing the liquid content of the coating layer by moisture absorption by the plant propagation material.

(Types of plant propagation material, etc.)
The kind of “plant propagation body” constituting the propagation material covering according to the present invention is not particularly limited, and examples thereof include vegetative propagation organs such as seeds and baskets, seedlings (seedlings), etc. Among them, seeds are preferable.
Specifically, the plant propagation material is, for example, seeds of gramineous plants such as rice, barley, and wheat; seeds of leguminous plants such as soybean, broad bean, and kidney bean; cruciferous plants such as rape, Chingsai, Komatsuna, and radish. Seeds of buckwheat plants such as buckwheat.

  The “seed” may be a seed after removing a structure that is not essential for germination (eg, rice husk, outer seed coat, inner seed coat, etc.).

(PVA)
PVA used in the method for producing a propagation material covering according to the present invention has a saponification degree of 78 mol% or more and is a particulate solid. If the degree of saponification of PVA is 78 mol% or more, a certain level of water resistance can be imparted to the coating layer, but the degree of saponification preferably exceeds 90 mol% from the standpoint of superior water resistance. The degree of saponification of PVA affects the water resistance of PVA, for example, and the water resistance tends to increase as the degree of saponification increases.

  On the other hand, the upper limit of the degree of saponification of PVA is not particularly limited, but is less than 98 mol% from the viewpoint of imparting sufficient resistance to the rubbing in the dry state (for example, rubbing between the propagation material coatings) by the coating layer. It is preferable that

  That is, from the viewpoint of being excellent in both resistance to rubbing in a dry state and water resistance, the saponification degree of PVA is preferably in the range of more than 90 mol% and less than 98 mol%, and 93 mol%. More preferably, it is within the range of less than 98 mol%, more preferably more than 95 mol% and less than 98 mol%.

  However, a dry state (not immersed in water) by using a particulate solid having a saponification degree of 98 mol% or more as PVA and a binder that is more water-soluble than PVA having a saponification degree of 98 mol%. It is also possible to produce coated seeds that are excellent in both resistance to rubbing in the state) and water resistance. As the binder to be mixed, particulate solid PVA having a saponification degree in the range of 78 mol% or more and 90 mol% or less is preferable, but other PVA or carboxymethyl cellulose (CMC) may be used.

  In the present invention, “degree of saponification (mol%) of PVA” is used in a general meaning in the technical field of chemistry, that is, when producing PVA by saponifying polyvinyl acetate, The percentage of vinyl repeat units is intended to be saponified to a hydroxyl group.

  Further, the degree of polymerization of PVA is not particularly limited, but from the viewpoint of being superior in the retention of functional materials, the degree of polymerization is preferably in the range of 1000 or more and 5000 or less, preferably in the range of 1500 or more and 3500 or less. More preferably, it is more preferably 1500 or more and 2500 or less, and particularly preferably 1700 or more and 2400 or less. The degree of polymerization of PVA affects the viscosity of PVA, for example, and the viscosity tends to increase as the degree of polymerization increases. And if this polymerization degree is 1000 or more, a functional material can be made to adhere to a seed more reliably. On the other hand, if the degree of polymerization is 5000 or less, the functional material and PVA can be mixed more easily and substantially uniformly.

  In the present invention, “degree of polymerization of PVA” is used in a general sense in the technical field of chemistry, and when vinyl acetate is saponified to produce PVA, a vinyl acetate repeating unit constituting a polymer chain Refers to the number of

  In the method according to the present invention, PVA is used as a particulate solid (particulate solid). As an example of the form of PVA as a particulate solid, a powdery form or a granular form obtained by solidifying a powder can be given. The size of the particulate solid is not particularly limited as long as it is a size that can be mixed with a functional material and used for coating the surface of a plant propagation material. In addition, even if the particle size is larger than the powder, functional materials can be retained by increasing the amount of solvent added to coat the plant propagation material and temporarily lowering the viscosity of the coating layer. is there. However, the PVA particle size is 150 μm from the viewpoint that it is easy to mix more uniformly with the functional material and from the viewpoint that the vicinity of the surface easily dissolves when the coating layer is formed using water or the like. The following is more preferable. The preferable lower limit of the particle size of PVA is not particularly limited, but is, for example, 0.1 μm or more, or 1 μm or more. Powdered PVA is more preferable than granular PVA.

  In the method according to the present invention, there is an advantage in that workability is excellent because PVA is used as a particulate solid rather than as a highly viscous solution. In addition, in order to eliminate the hassle of dissolving the binder, compared to the case where a binder that is not soluble in water is dissolved in advance and distributed as a solution (water-resistant PVA, latex suspension, etc.) Since the weight is low, the distribution cost can be reduced. However, regarding the propagation material covering before being planted, the state in which the covering layer contains moisture and a part of the PVA is viscous is within the scope of the present invention.

(Functional materials)
The type of functional material (material that imparts a predetermined function to the propagation material covering) used in the method for producing the propagation material covering according to the present invention is not particularly limited. Specifically, for example, molybdenum material, tungsten material, etc. , Iron materials, oxygen generators, clay, or slow-acting agricultural chemicals that do not require rapid release in water. From the viewpoint of easy mixing with PVA which is a particulate solid, these functional materials are also preferably a particulate solid such as a powder form or a granular form obtained by solidifying a powder. The particle size of the functional material is not particularly limited, but from the viewpoint of the workability of the coating, for example, it is in the range of 0.1 μm to 150 μm. In addition, only 1 type may be used for a functional material and you may use multiple types together.

  Among the functional materials exemplified above, the molybdenum material and the tungsten material generate oxoanions, thereby suppressing the generation of sulfide ions in the plant growth environment. Furthermore, these oxoanions suppress the activity of microorganisms such as spoilage in the plant growth environment. Therefore, by using a molybdenum material or a tungsten material, it is possible to suppress plant seedling and a decrease in growth.

  When molybdenum material and tungsten material are compared, molybdenum material may be more preferable. More specifically, molybdenum materials have a sufficient track record of application to plants. In addition, the molybdenum material has a stronger anti-corrosion effect than the tungsten material. Tungsten is not highly toxic to plants and animals, and is highly safe.

  The type of the molybdenum material is not particularly limited, and various substances are included in its category, but it is preferable to select a material or a simple substance that supplies molybdate ions and has high safety to the target plant. Therefore, the molybdenum material is a group consisting of metal molybdenum (simple substance), molybdenum oxide (molybdic anhydride), molybdic acid and its salt, molybdophosphoric acid (phosphomolybdic acid) and its salt, molybdosilicic acid (silicomolybdic acid) and its salt It is preferable that it is at least one selected from more. Inexpensive and commercially available metal molybdenum, molybdenum oxide, molybdate, calcium molybdate, magnesium molybdate, ammonium molybdate (ammonium phosphomolybdate), potassium molybdate (potassium phosphomolybdate), ammonium molybdate, It is preferably at least one selected from the group consisting of sodium molybdate, potassium molybdate, molybdophosphoric acid, sodium molybdophosphate (sodium phosphomolybdate), and molybdosilicate. In addition, these functional materials are not limited to the case where they are actually included in the breeding material covering, but also include the case of raw materials used for the production of the breeding material covering. That is, by adding another material that reacts with these functional materials before or at the time of coating on the plant propagation material, it may be changed to a different compound in the propagation material coating.

  A slightly soluble molybdenum material that is slightly soluble in water is particularly preferable from the viewpoint of safety with respect to the target plant. The slightly soluble molybdenum material is a material or a simple substance having a water soluble ratio of 10% or less by weight, for example, metal molybdenum, molybdenum oxide, molybdate, calcium molybdate, magnesium molybdate, ammonium molybdophosphate, and Examples thereof include potassium molybdate. In addition, polyacids and heteroacids condensed with oxoanions, salts thereof, and materials containing them are not particularly easily supplied with molybdate ions, and are particularly preferable from the viewpoint of safety with respect to the target plant.

  Among these, ammonium molybdophosphate and potassium molybdophosphate are salts of heteroacids that are slightly soluble in water and do not easily supply molybdate ions, and suppress the deterioration of plant seedling and growth. Excellent effect. Moreover, since these materials are colored yellow, it is preferable also from the point which can prevent accidental ingestion of the seed which carried out the coating process.

  Similarly, the type of the tungsten material is not particularly limited, and various substances are included in its category. However, it is possible to select a material or a simple substance that supplies tungstate ions and has high safety to the target plant. preferable. Therefore, the tungsten material includes metal tungsten, tungsten oxide (anhydrous tungstic acid), tungstic acid and its salt, tungstophosphoric acid (phosphotungstic acid) and its salt, and tungstosilicic acid (silicotungstic acid) and its salt. It is preferable that at least one selected. Of those that are inexpensive and commercially available, slightly soluble metal tungsten, tungsten oxide, tungstic acid, ammonium paratungstate, or ammonium tungstate phosphate (ammonium phosphotungstate) is preferred.

  As in the case of molybdenum materials, tungsten materials are preferably slightly soluble, and materials in the form of polyacids or heteroacids that are difficult to supply tungstate ions are preferred. In addition, the compounds specifically exemplified by the above compound names are all slightly soluble. In addition, ammonium tungstophosphate and potassium tungstate phosphate are salts of hetero acids that are slightly soluble in water and do not easily supply tungstate ions.

  In addition, although the usage-amount of molybdenum material and tungsten material is not specifically limited, For example, when the object of coating | cover is a seed, it is 0.01 mol or more and 10 mol or less as molybdenum element or tungsten element with respect to 1 kg of air-dried seed weight. From the viewpoint of exerting sufficient efficacy while suppressing material costs, it is preferably 0.01 mol or more and 0.2 mol or less as molybdenum element or tungsten element with respect to 1 kg of air-dried seed weight. It may be within the range.

  The iron material as a functional material is used, for example, for the purpose of increasing the weight or bulk of the seed. In addition, when seeds are covered with a coating layer containing iron material, the increase in sulfide ions can be suppressed by iron insolubilization of sulfide ions around the seeds, thus suppressing the seedling decline in seeds. be able to. Furthermore, by covering the seed with an iron material, a hard coating layer can be formed and made inconspicuous with respect to the soil, so that bird damage can be avoided.

The iron material is not particularly limited, specifically, for example, reduced iron (Fe), iron oxide _{(III) (Fe 2 O 3} ), iron oxide _{(II, III) (Fe 3} O 4), oxide Iron (II) (FeO) etc. are mentioned, These compositions may be sufficient. Various iron oxides are more preferable from the viewpoint that there is no possibility of heat generation.

  Reduced iron is usually mixed with gypsum, and a method of strengthening the bond to seeds (plant propagation body) by rust caused by oxidation promoted by gypsum is performed. However, since it takes time until rust is generated, the coating layer is maintained by the bonding action of gypsum together with the surface tension of water. For this reason, when a substance that does not have a binding action and merely promotes oxidation is used instead of gypsum, the coating layer until rust is generated is weak and the workability of the coating is reduced. For this reason, it has been difficult to substitute gypsum containing sulfur which causes growth failure with another substance. However, if PVA is used, the coating layer can be maintained until rust is generated, and it contributes to the maintenance of the coating layer along with rust after the rust is generated. Also, when iron-coated seeds made from reduced iron are sown in water, the rust slowly softens and the surrounding water is suspended. Therefore, even when the reduced iron is coated, water resistance can be improved by using completely saponified or intermediate saponified PVA. From the above, it is preferable to use PVA also in coating using reduced iron.

  The iron material may be a combination of iron materials having different particle sizes. An iron material having a relatively large particle size (for example, a particle size in the range of more than 10 μm and 100 μm or less) has an advantage that the material is less likely to scatter and is excellent in workability of coating work. On the other hand, an iron material having a relatively small particle size (for example, a particle size of 10 μm or less) can further reduce the required amount of PVA, and can be rubbed in a dry state (a state in which it is not immersed in water) even when a small amount of PVA is used. There is an advantage that resistance to is particularly improved. This combination includes not only simple mixing of different materials but also covering the seeds separately in different orders. For example, by coating a material having a relatively small particle size as an outer layer, the amount of the material having a relatively small particle size for smoothing the surface of the coated seed can be reduced. Therefore, if iron materials having different particle sizes are used in combination, it is possible to realize coating with an iron material that can enjoy all of these advantages.

  In one example in which iron materials having different particle diameters are used in combination, the ratio of iron oxide having a particle diameter of 1 μm or less in the iron materials may be in the range of 5 wt% to 50 wt%. At this time, the remaining 50 wt% or more and 95 wt% or less of the iron material only needs to have a particle size of more than 1 μm, more preferably 10 μm or more and 150 μm or less, more preferably 20 μm or more and about 100 μm or less. Are more preferred.

  In addition, the required amount of PVA can be further reduced, and the particle size of the iron material is within the range of 0.1 μm or more and 1 μm or less from the viewpoint that the resistance to rubbing in the dry state is particularly improved even with the use of a small amount of PVA. It may be preferable to be.

The amount of the iron material used is not particularly limited. For example, when the object to be coated is seeds, the amount may be within the range of 5% to 200% by weight of the air-dried seed weight. It is preferable to be within the range of 5% weight or more and 50% weight or less.
The oxygen generator as a functional material, for example, suppresses an increase in sulfide ions in the vicinity of seeds (plant propagation bodies), and suppresses seedling establishment (initial growth of plant propagation bodies). Used in The oxygen generator may be any material as a supply source of oxygen, and examples thereof include calcium peroxide (CaO ₂ ), magnesium peroxide and the like, and compositions containing these as active ingredients (functional ingredients). In these illustrations, the material which uses calcium peroxide as an active ingredient is preferable.

  Currently, oxygen generators are bonded to seeds using gypsum, but as drying progresses, there is a problem that cracks are likely to occur in the coating layer, making long-term storage difficult. Use of PVA instead of gypsum is preferable because it not only eliminates sulfur that is harmful to seeds, but also improves water resistance and makes cracks less likely to occur.

  The amount of oxygen generator used is not particularly limited. For example, when the target of coating is seeds, the active ingredient (for example, calcium peroxide) is within a range of 1% to 50% by weight of the air-dried seed weight. ).

  The above-mentioned clay as a functional material is used for the purpose of increasing the weight or bulk of seeds (plant propagation material), for example, as with iron materials. The amount of clay used is not particularly limited. For example, when the object to be coated is seeds, it may be within a range of 5% to 200% by weight of the air-dried seed weight.

(Coating layer)
In the propagation material coverings (coated seeds, etc.) obtained by the production method according to the present invention, the coating layer covering the outer surface of the plant propagation material is a layer composed of a composition containing the above PVA and a functional material. It is. The covering layer only needs to cover at least a part of the outer surface of the plant propagation material. However, when the plant propagation material is a seed, the entire outer surface of the seed must be coated substantially uniformly. preferable.

  The mixing ratio of the PVA and the functional material constituting the coating layer is not particularly limited as long as the functional material can be attached to the plant propagation material. In one example, PVA is used in a range of 0.02% to 10% by weight, and in a range of 0.1% to 5% by weight with respect to the weight of the functional material. More preferably, it is used within the range of 0.5% weight or more and 5% weight or less, more preferably 0.5% weight or more and 3% weight or less. .

  The coating layer may further contain a binder or other materials used for coating the plant propagation material. However, it is preferable that a sulfur component such as sulfate or sulfate ion is not substantially contained. Here, “does not contain a sulfur component” means that a component containing a sulfur atom is not substantially contained. The component containing a sulfur atom refers to, for example, a sulfate or sulfate ion, and examples of specific compound names include calcium sulfate, magnesium sulfate, potassium sulfate, and ammonium sulfate. That is, in this invention, it is preferable that the component which comprises a coating layer does not contain the gypsum etc. which have a calcium sulfate as a main component, for example.

  When the coating layer does not substantially contain a sulfur component, the sulfate ion concentration around the plant propagation material is not increased. Therefore, when oxygen is insufficient and the reduction conditions are satisfied, the generation of sulfide ions that reduce seedling establishment can be suppressed. In addition, when the functional material included in the coating layer is a material that can reduce the concentration of sulfide ions around the plant propagation material (for example, the above-described oxygen generator, iron material, molybdenum material, tungsten material, etc.) The required amount of functional materials can be reduced and the manufacturing cost can be reduced.

  Note that gypsum is a representative example of a water-resistant and inexpensive binder, and until now, there has been virtually no material that can replace gypsum in terms of water resistance, handling properties, and cost. However, according to the present invention, a functional material can be bound to a plant propagation body in a state of having water resistance, using a relatively small amount of inexpensive PVA without using gypsum having a seedling-inhibiting effect. it can.

  More specifically, the following can be realized by using PVA having predetermined properties as in the present invention. (1) Since PVA does not contain sulfur and does not promote the generation of sulfide ions, it can contribute to the reduction of the required amount of oxygen generating agent by using it for coating of the oxygen generating agent. (2) Similarly, since PVA does not promote the generation of sulfide ions, it is expected to lead to stabilization of seedling establishment in soil in iron-coated seeds. (3) By using PVA, it is possible to cover only with iron oxide that does not generate heat without using reduced iron that generates heat. Therefore, it is possible to eliminate damage to the plant propagation body due to heat generation. (4) Various functional materials such as molybdenum or clay can be attached. Compared to gypsum, PVA is considered to be widely available in place of gypsum because it requires less and is less expensive.

[2. (Propagation cover)
The propagation material covering according to the present invention is obtained in accordance with the method for producing a propagation material covering described in the section [1.].

  That is, the propagation material covering is provided with a coating layer containing PVA having a saponification degree of 78 mol% or more and a functional material on the surface of the plant propagation material. A particularly specific example of the propagation material coating is a coated seed in which the seed is coated with these coating layers. Here, although PVA does not need to hold | maintain the initial particle shape, it has the external characteristic that the ratio of PVA which maintained particle shape increases as the saponification degree increases. In addition, a coating layer may contain the liquid used in the manufacturing process of a propagation body coating.

  The propagation material covering which concerns on this invention is excellent in the water resistance of a coating layer, and can fully hold | maintain a functional material also in water. Therefore, the propagation material covering may be a plant having a period in which at least a part of the plant body (concept including the seed itself) is in a flooded state between the planting step and the seedling establishment period. . In other words, the propagation material covering may be planted and / or budding at least temporarily under the condition of being inundated. Examples of such propagation material coverings include, for example, seeds cultivated by direct sowing in flooded paddy fields, those cultivated by hydroponics, those planted in soil with poor drainage or soil substitutes, and planting There are those that may be hit by heavy rain immediately before or after, and a more specific example is rice seeds.

[3. Plant cultivation method)
The present invention also provides a method for cultivating a plant by planting the obtained propagation material covering. That is, the propagation material covering which concerns on this invention is cultivated until it becomes a plant body of the size which can be used after planting (planting process).

  The method for planting the propagation material cover is not particularly limited. For example, in the case of coated seeds, seeding may be performed on farmland using a seeding machine such as a spot seeder, a streaker, or a seeder. You may sow directly by hand. Moreover, what is necessary is just to plant by a planting machine or a hand, when the propagation body covering is the young plant (seedling) to which the functional material was made to adhere.

  Planting of the propagation material covering is performed, for example, on soil or soil substitute. Here, the soil substitute refers to a medium capable of growing plants instead of soil, such as artificial soil (peat moss, etc.), a medium for hydroponics, and the like.

  The propagation material covering which concerns on this invention is excellent in the water resistance of a coating layer. Therefore, in the plant cultivation method according to the present invention, even when the plant material has a period in which at least a part of the plant body is flooded during the seedling establishment period after the planting step, the functional material is detached from the seed. There is little possibility to do.

  That is, in an example of the cultivation method according to the present invention, the propagation material covering is planted and / or budding at least temporarily under the condition of being flooded. The conditions for at least temporarily flooding include not only long-term flooding such as paddy fields and hydroponics, but also the case of temporary flooding due to heavy rain.

  Moreover, in this invention, the said planting process may be performed with the form of flooded direct seeding. Here, flooded direct sowing means direct sowing (direct sowing) on flooded soil or soil substitutes. The submerged soil or soil substitute is, for example, a paddy field after substitution, a hydroponic medium, a field submerged by rain, a hydroponic culture medium, or the like. The “paddy field” is not limited to the cultivated land where rice is cultivated, but may be any cultivated land where water is drawn to grow the crop.

[4. More specific examples of coated seeds)
Hereinafter, more specific structural examples of the coated seeds which are one form of the propagation material covering according to the present invention will be shown.

Coated seed (1)
PVA: The degree of polymerization is in the range of 1500 to 2500, and the saponification degree is in the range of more than 90 mol% and less than 98 mol%. The particle size of PVA is not limited, but is preferably 150 μm or less. Mixed with functional materials within the range of 0.5% to 3% by weight of functional materials.
Functional material: At least one selected from molybdenum trioxide, potassium molybdophosphate, or ammonium molybdophosphate. The functional material is used in a range of 0.01 mol or more and 0.2 mol or less of molybdenum element per kg of air-dried seeds.
In addition, the kind of seed is not limited. The outer surface of the seed is coated with a composition in which PVA and a functional material are mixed.

Coated seed (2)
PVA: The degree of polymerization is in the range of 1500 to 2500, and the degree of saponification is in the range of more than 90 mol% and less than 98 mol%. The particle size of PVA is 150 μm or less. Mixed with functional materials within the range of 0.5% to 3% by weight of functional materials.
Functional material: Iron oxide. The particle size is preferably 1 μm or less. The functional material is used within a range of 5% to 50% by weight of the weight of the air-dried seed.
The kind of seed is not limited. The outer surface of the seed is coated with a composition in which PVA and a functional material are mixed.
In addition, as the functional material, at least one selected from molybdenum trioxide, potassium molybdophosphate, ammonium molybdophosphate, molybdophosphoric acid, or sodium molybdophosphate is used. You may add within the range of 2 mol or less.

Coated seed (3)
PVA: The degree of polymerization is in the range of 1500 to 2500, and the saponification degree is in the range of more than 90 mol% and less than 98 mol%. The particle size is 150 μm or less. Mixed with functional materials within the range of 0.5% to 3% by weight of functional materials.
Functional material: at least one selected from iron oxide, reduced iron, or clay. The functional material is used within a range of 5% to 50% by weight of the weight of the air-dried seed.
The kind of seed is not limited. The outer surface of the seed is coated with a composition in which PVA and a functional material are mixed.
In addition, as the functional material, at least one selected from molybdenum trioxide, potassium molybdophosphate, ammonium molybdophosphate, molybdophosphoric acid, or sodium molybdophosphate is used. You may add within the range of 2 mol or less.

Coated seed (4)
PVA: The degree of polymerization is in the range of 1500 to 2500, and the saponification degree is in the range of more than 90 mol% and less than 98 mol%. The particle size is 150 μm or less. Mixed with functional materials within the range of 0.5% to 3% by weight of functional materials.
Functional materials: Materials containing calcium peroxide (a kind of oxygen generator). The functional material is used in a range where the calcium peroxide contained is 2% or more and 20% or less of the weight of the air-dried seed.
The kind of seed is not limited. The outer surface of the seed is coated with a composition in which PVA and a functional material are mixed.
In addition, as the functional material, at least one selected from molybdenum trioxide, potassium molybdophosphate, ammonium molybdophosphate, molybdophosphoric acid, or sodium molybdophosphate is used. You may add within the range of 2 mol or less.

Coated seed (5)
Iron oxide powder (Morishita Bengar Kogyo Co., Ltd., product name: No. 1094, iron oxide (III) (99% by weight), average particle size 0.57 μm) is added to 0.5% weight of the iron oxide powder. Polyvinyl alcohol powder corresponding to 3% weight (preferably 1% weight) (product name: JM-17S, product name: JM-17S, degree of saponification: 95.5-97.5 mol%, degree of polymerization: about 1700, particle size: 150 μm or less). This mixture is used in such an amount that the iron oxide powder weight is 5 to 50% of the air-dried seed weight.
In addition, as the functional material, at least one selected from molybdenum trioxide and ammonium molybdophosphate may be added within a range of 0.01 mol to 0.2 mol of molybdenum element per kg of air-dried seed. .

  Hereinafter, examples will be shown and the embodiment of the present invention will be described in more detail. However, the present invention is not limited to the following examples.

  First, evaluation methods of “peeling ratio before immersion”, “water resistance”, and “workability” evaluated in Examples will be described together.

  “Peeling ratio before immersion” is about 30 seconds with a test tube mixer (SCIENTIFIC INDUSTRIES G-560, maximum strength) after putting about 2.5 g of the coated seed to be evaluated, which is naturally dried at room temperature, into a plastic centrifuge tube (45 mL). Or shake for 60 seconds. Thereafter, the powder peeled off from the coated seeds was weighed, and the ratio of the weight of the peeled material to the weight of the adhered material was defined as a peel ratio before immersion (0% for no peeling and 100% for all peeling). Here, the “material” indicates a functional material when PVA is not used, and indicates a functional material and PVA when PVA is used.

  For the “water resistance” of the coated seeds, 10 (or 5) of the coated seeds to be evaluated were placed in a test tube and 10 mL (or 5 mL) of distilled water was added. Next, tape the test tube to the test tube stand, add water, and after a predetermined number of days, hold the test tube stand with both hands so that water does not spill, shake vigorously in a horizontal circle, The situation was observed immediately after that. And, depending on the degree of water turbidity at the time of observation, the water resistance of the coating layer is ○ (almost turbid), △ (slightly turbid = most of the functional materials remain attached to the seed), × (remarkably turbid = functional The majority of the materials were classified and evaluated as peeling from seeds.

  “Workability” for producing coated seeds means that when the coated seeds are produced, the seeds are not substantially bound to each other, and the seeds are bound to each other. The case where separation was possible by placing and shaking) was evaluated by classifying the cases where the seeds were strongly bonded to each other, were difficult to separate after drying, and it took time and effort to separate.

[Example 1: Effect of saponification degree of PVA on seed coating strength]
For air-dried rice seeds (variety: Nikomaru), iron oxide (hematite, ferric trioxide) powder (DOWA IP Creation Co., Ltd., hematite # 32, average particle size around 90 μm, 50% of air-dried seed weight, Hereinafter referred to as “coarse iron oxide”: an example of a functional material) and potassium molybdophosphate equivalent to 0.2 mmol Mo / g air-dried seed (3.3% weight of air-dried seed weight) (manufactured by Nippon Shin Metal Co., Ltd.) : An example of a functional material). It should be noted that potassium molybdophosphate also functions as a sulfide ion production inhibitor under flooding conditions.

  Next, the mixture of functional materials and seeds are stirred together while adding water by spraying at room temperature. After the functional material mixture is adhered to the seed surface, it is naturally dried at room temperature for reference. Coated seeds were produced.

  Separately, a mixture of coarse iron oxide and potassium molybdophosphate (a mixture of functional materials) is used by thoroughly mixing 1% PVA of the total weight of the mixture as a particulate solid. In the same manner as in the above case in which PVA is not mixed, except that water is added, the mixture of functional materials and PVA are adhered to the surface of the air-dried rice seed, and then naturally dried at room temperature to cover the seed. Manufactured.

  The PVA used has four types with different degrees of saponification having a degree of polymerization of about 1,500 to 1,800 (1. Wako Pure Chemical Industries, Ltd., reagent special grade, degree of saponification 78 to 82 mol%, hereinafter, PVA varieties are abbreviated as “Wako.” 2. Made by Nippon Vinegar-Poval Co., Ltd., Variety: JP-18S, Saponification Degree 86-90 mol% 3. Made by Nippon Vinegar-Poval Inc., Variety: JM -17S, degree of saponification 95.5-97.5 mol%, 4. Japanese Vinegar Pival Co., Ltd., cultivar: JF-17S, degree of saponification 98-99 mol%). The properties of these PVA are shown in Table 1 together with the PVA used in other examples. JP-18S, JP-20S, JP-24S, JM-17S, JF-17S, and V-S08 are fine powders having a particle size of 150 μm or less (# 100 pass product) and are particularly finer than others.

  Next, the five kinds of coated seeds thus obtained were evaluated for “peeling ratio before immersion (shaking for 30 seconds)” and “water resistance (10 seeds / 10 mL of water)”. The obtained results are shown in FIG.

  As shown in Table 2, the peeling ratio before immersion was nearly half when PVA was not mixed, and was significantly reduced when PVA was added. Further, the use of another PVA than the completely saponified JF-17S (degree of saponification 98 to 99 mol%) further reduced the peeling rate before dipping.

  Moreover, as shown in FIG. 1, the water resistance of the coated seeds was large when the PVA was not added, and the material peeled off and the water became cloudy. On the other hand, when JF-17S (saponification degree 98-99 mol%) and JM-17S (saponification degree 95.5-97.5 mol%) having a higher saponification degree were used, other PVA Compared to when used, the water was much less turbid, the material hardly peeled off in water, and the water resistance was extremely high (Table 2).

  Based on the above results, PVA is preliminarily treated with water, including completely saponified (JF-17S) and intermediate saponified (JM-17S) PVA, which is low in water solubility and generally used by heating and dissolving in advance. It was confirmed that the coating strength of iron oxide was sufficiently increased even when it was mixed with iron oxide and / or seeds in the form of a particulate solid without being dissolved in, and water was used to form a coating layer. That is, it is possible to use the powder as it is, which is low in water solubility, and is easy to work for the completely saponified and intermediate saponified PVA, which is generally dissolved by heating at a high temperature. It turned out.

  Furthermore, from the viewpoint of imparting sufficient resistance to rubbing between coated seeds before sowing in paddy fields (in view of reducing the peeling ratio before immersion), it is more preferable to use PVA having a saponification degree lower than that of a completely saponified type. It was considered preferable. On the other hand, it was considered desirable to use PVA with a higher degree of saponification from the viewpoint of preventing separation of functional materials after sowing in flooded paddy fields. That is, it was considered that the intermediate saponification type (JM-17S, saponification degree 95.5-97.5 mol%) was particularly preferable as PVA excellent in both conditions.

[Example 2: Effects of saponification degree and polymerization degree of PVA on seed coating strength (1)]
A mixture of coarse iron oxide and potassium molybdate in the same manner as in Example 1 when no PVA was added and when nine types of PVA made by Nihon Vinegar Poval Co., Ltd. shown in Table 1 were used. And PVA (in the case of using PVA) were produced. And according to the method similar to Example 1, the peeling ratio before immersion and water resistance were investigated. However, in the water resistance test, 5 coated seeds and 5 mL of water were put in each test tube, and the test tube was shaken 4 days after the addition of water.

  As shown in Table 3, the peeling ratio before immersion is decreased by the addition of PVA, and PVA of the partially saponified type (saponification degree less than 90 mol%) ≦ intermediate saponification type (saponification degree 90 to 98 mol%). Of PVA <completely saponified type (saponification degree: 98 mol% or more). It is presumed that the lower the degree of saponification of PVA, the higher the hydrophilicity and the easier it is to dissolve in water at room temperature, making it easier to obtain viscosity.

  Furthermore, the powdered PVA tended to have a lower peel rate before immersion than the granular PVA. It was estimated that this was because powdered PVA was more easily mixed with a functional material such as iron oxide more uniformly, and because the specific surface area was large, the surface was partially dissolved. In particular, when granular PVA is used, the degree of polymerization is within a predetermined range (1000 or more and 5000 or less, preferably 1500 or more and 3500 or less, more preferably 1500 or more and 2500 or less, more preferably 1700 or more. 2400 or less), the peeling ratio before immersion tended to be low.

  In addition, as shown in Table 3, the results of the water resistance test show that the saponification type (saponification degree is 98 mol% or more) and intermediate saponification type compared to the partially saponified type (saponification degree less than 90 mol%) PVA. There was a tendency that the PVA having a saponification type (saponification degree: 90 to 98 mol%) was less turbid and water was less likely to peel off the functional material. Moreover, the tendency for water resistance to increase more was seen, so that the polymerization degree of PVA was large.

  From the above results, intermediate saponification type (saponification degree: 90 to 98 mol%) PVA is more preferable from the viewpoint of having a low peeling ratio of the functional material before immersion and water resistance, and among them, JM-17S (saponification). A degree of polymerization of 95.5 to 97.5 mol% and a degree of polymerization of 1,700) was considered particularly preferred.

[Example 3: Effect of saponification degree and polymerization degree of PVA on seed coating strength (2)]
Instead of coarse iron oxide (average particle size around 90 μm), iron oxide with an average particle size of about 0.2 μm (manufactured by Wako Pure Chemical Industries, Ltd., iron oxide (III) (diiron trioxide), Wako first grade, Except for the point of using “fine-grained iron oxide”), a mixture of fine-grained iron oxide and potassium molybdate and PVA (with different polymerization degrees and saponification degrees) was used according to the method described in Example 2. Coated seeds coated with PVA) were prepared, and the peeling rate before immersion and water resistance (5 seeds / 5 mL of water, 4 days after adding water and shaking the test tube) were examined. The iron oxide used in this example is usually used as a pigment (bengala) or an industrial material, and is not widely used as an agricultural material.

  Compared to the case of using coarse iron oxide, the use of fine iron oxide significantly reduced the peeling ratio before immersion (see Table 4). When partially saponified PVA (saponification degree less than 90 mol%) and intermediate saponification type (saponification degree 90 to 98 mol%) PVA are used, complete saponification type (saponification degree of 98 mol% or more) Compared with the case of using PVA, the peeling ratio before immersion was lower.

  With respect to water resistance, a tendency to be superior to water resistance was obtained when coarse iron oxide was used (Example 2) rather than fine iron oxide (results not shown). Further, as shown in Table 4, when fine-grained iron oxide is used, from the viewpoint of being particularly excellent in water resistance, intermediate saponification type (JM-17S, JM-33, saponification degree 90 to 98 mol%) and complete saponification are used. PVA (JF-17S) is preferable, and intermediate saponification type is more preferable.

  From the above results, it can be seen that even with fine-grained iron oxide, PVA is not dissolved in advance and can be coated with seeds by directly mixing with functional materials while remaining in a particulate solid form. Moreover, when using fine-grain iron oxide as a functional material, PVA is preferably an intermediate saponification type (saponification degree: 90 to 98 mol%), and particularly JM-17S (saponification degree: 95.5 to 97.5 mol%). The degree of polymerization 1,700) was considered more preferable.

[Example 4: Effect of PVA mixing ratio on seed coating strength (1)]
Except that only the amount of JM-17S described later as PVA was used in the form of a particulate solid, in the same manner as in Example 2, coarse iron oxide (functional material) of 50% weight of air-dried rice seed weight and 0 A coated seed coated with a mixture of potassium molybdophosphate (functional material) of .2 mmol Mo / g air-dried seed and PVA (when PVA was used) was prepared. Here, the usage amount of PVA (JM-17S) was 0 to 10% weight (hereinafter referred to as “PVA ratio”) with respect to the total weight of the mixture of functional materials.
Next, the obtained coated seeds were examined in the same manner as in Example 2 for the peeling ratio before immersion and the water resistance (5 seeds / 5 mL water). However, in the water resistance test, 5 coated seeds and 5 mL of water were placed in each test tube, and the test tube was shaken 3 days after the addition of water. In addition, “workability” for producing coated seeds was also evaluated, and Table 5 shows the evaluation results.

  As shown in Table 5, the results of the water resistance test showed that when the coated seeds were immersed in water, even when the PVA ratio was 0.5% weight, the water was hardly turbid and there was a tendency to exhibit sufficient water resistance. .

  Moreover, the tendency for the peeling ratio before immersion to fall was seen, so that the PVA ratio became high. And when the PVA ratio is 3% weight or more, since the peeling ratio before immersion is reduced to about 1%, the PVA ratio is 2% to 3 from the viewpoint of the stability of the coated seed before being immersed in water. % Weight or more was considered preferable.

  On the other hand, as the PVA ratio is lower, the binding between the seeds is suppressed, and the efficiency (workability) of the covering work is more improved. Moreover, the tendency for water to become difficult to become cloudy was also obtained, so that the PVA ratio became low. The tendency for water to become less turbid and the water resistance to improve as the PVA ratio becomes lower reflects that the workability improves as the PVA ratio becomes lower and it becomes easier to coat the seeds more uniformly. The possibility was also considered. More specifically, when the PVA ratio is less than 5% weight, the seeds hardly adhere to each other, and the covering operation can be performed relatively efficiently (see Table 5).

  From the above, in the coating of coarse iron oxide, it was considered that the lower limit of the PVA ratio is preferably about 2-3% weight, and the upper limit of the PVA ratio is preferably about 5% weight. The PVA ratio is more preferably in the range of 2% weight to 4% weight, and particularly preferably in the range of 2% weight to 3% weight.

[Example 5: Effect of PVA mixing ratio on seed coating strength (2)]
50% weight of air-dried rice seed weight in the same manner as in Example 3 except that only the amount of JM-17S described later as PVA was used as a particulate solid and potassium molybdophosphate was not used. Coated seeds coated with fine iron oxide and PVA (when PVA was used) were prepared. Here, the amount of PVA (JM-17S) used was also referred to the results of Example 3 and was 0 to 1% weight (hereinafter referred to as “PVA ratio”) of the weight of iron oxide as a functional material.

  Subsequently, the obtained coated seeds were examined in the same manner as in Example 3 for the peeling ratio before immersion and the water resistance (10 seeds / 10 mL of water). However, in the water resistance test, 10 coated seeds and 10 mL of water were put in each test tube, and the test tube was shaken 10 days after the addition of water.

  As shown in Table 6, within the range of the tested PVA ratio, the peeling ratio before immersion decreased more as the PVA ratio increased. Moreover, since the peeling ratio before immersion falls to 1% or less, it was considered that the PVA ratio is preferably 0.4% weight or more.

  In addition, as shown in Table 6, when the coated seeds were immersed in water, the results of the water resistance test confirmed that even when the PVA ratio was 0.05% weight, the water was not easily turbid, and the PVA ratio was 0. More than 2% weight, the turbidity of water disappeared and much better water resistance was obtained.

  From the above results, it can be seen that fine iron oxide may have a lower PVA ratio used for coating than coarse iron oxide, more specifically, in order to provide sufficient coating strength, the PVA ratio is 0. It was suggested that a range of about 4% weight or more and 1% weight or less is sufficient.

[Example 6A-1: Effect of mixture of functional materials having different particle diameters on seed coating strength (1)]
Coated seed in the same manner as in Example 5 except that the PVA ratio was fixed at 1% weight as the amount of JM-17S used, and fine-grained iron oxide and coarse-grained iron oxide were appropriately mixed and used as a functional material. Was prepared, and the peeling rate before immersion of the coated seeds (however, shaking for 60 seconds instead of shaking for 30 seconds) and water resistance (10 seeds / 10 mL of water) were examined. In addition, "workability" for producing coated seeds was also evaluated. The mixing ratio of the fine-grained iron oxide and the coarse-grained iron oxide was the weight ratio as shown in Table 7 for the fine-grained ratio and the coarse-grained ratio, and the total amount was always 50% weight of the air-dried rice seed weight. However, in the water resistance test, 10 coated seeds and 10 mL of water were put in each test tube, and the test tube was shaken 6 days after the addition of water.

  As shown in Table 7, the peeling ratio before immersion decreased as the mixing ratio of fine iron oxide increased. For example, when the coarse-grained iron oxide and the fine-grained iron oxide were mixed by half, the peeling ratio before immersion decreased to about 1%.

  Further, as shown in Table 7, the results of the water resistance test showed that the water resistance was very high under any condition. Moreover, when the ratio of the fine-grain iron oxide was less than 80%, the adhesion between the seeds was very small, and the workability of the coating work was particularly excellent.

  Coarse-grained iron oxide has the advantage of less scattering compared to fine-grained iron oxide, while a higher PVA ratio is required to ensure a pre-immersion peeling ratio equivalent to fine-grained iron oxide. However, from the results of this example, it was suggested that sufficient coating strength can be secured with a relatively low PVA ratio by using coarse iron oxide mixed with fine iron oxide as necessary.

[Example 6A-2: Effect of mixture of functional materials having different particle diameters on seed coating strength (2)]
Similar to Example 5 except that the PVA ratio was fixed at 2% weight or 3% weight as the amount of JM-17S used, and fine iron oxide and coarse iron oxide were mixed appropriately and used as a functional material. Then, coated seeds were prepared, and the peeling rate of the coated seeds before immersion (however, shaking for 60 seconds instead of shaking for 30 seconds) and water resistance (10 seeds / 10 mL of water) were examined. In addition, "workability" for producing coated seeds was also evaluated. The mixing ratio of the fine-grained iron oxide and the coarse-grained iron oxide was the weight ratio as shown in Table 8 for the fine-grained ratio and the coarse-grained ratio, and the total amount was always 50% weight of the air-dried rice seed weight. However, in the water resistance test, 10 coated seeds and 10 mL of water were put in each test tube, and the test tube was shaken 6 days after the addition of water.

  As shown in Table 8, as compared with the case where the PVA ratio is 1% weight (see Table 7), the peeling ratio before immersion tends to decrease. However, when the PVA ratio was 2% weight, seeds were less likely to adhere to each other than when the ratio was 3% weight, and the workability was even better.

  Moreover, when fine-grained iron oxide was mixed with coarse-grained iron oxide, it was clearly confirmed by visual observation that the coating unevenness became smaller and the surface of the coating layer became smoother (data not shown). The exfoliation of the functional material before being immersed in water is considered to contribute greatly to the rubbing between the seeds. Therefore, mixing fine-grain iron oxide with coarse-grain iron oxide to smooth the surface of the coating layer is an effective means for suppressing the occurrence of coating unevenness and reducing exfoliation of functional materials.

  From the results of Examples 6A-1 and 6A-2, when coating plant seeds with iron oxide, by adding fine iron oxide to coarse iron oxide, while maintaining the workability of the coating in a good range, The occurrence of coating unevenness can be suppressed, the surface of the coating layer can be smoothed, and the coating strength can be ensured. At this time, an example of the PVA ratio is particularly preferably used within the range of 1% weight or more and 3% weight or less.

[Example 6B: Effect of PVA addition on coating strength of various iron oxide materials of rice seed]
Iron oxide with 50% weight of air-dried rice seed weight is the same as Example 5 except that the type of iron oxide is changed as a functional material and the PVA ratio is 1-5% weight as the amount of JM-17S used. Coated seeds coated with the above were prepared, and the peeling rate before immersion of the coated seeds (however, shaking for 30 seconds) and water resistance (10 seeds / 10 mL of water, 13 days after adding water) were examined. Iron oxide is (1) fine-grain iron oxide shown in Example 3 [abbreviated as Fe ₂ O ₃ (w)], (2) iron oxide (diiron trioxide, manufactured by JFE Chemical Co., Ltd., JC-CPW) Average particle diameter of about 0.9 μm) [abbreviated as Fe ₂ O ₃ (js)], (3) coarse-grained iron oxide shown in Example 1 [abbreviated as Fe ₂ O ₃ (d)], (4) powder Ore fine powder (ferric trioxide, manufactured by JFE Steel Co., Ltd., 75 μm or less collected with a sieve) [abbreviated as Fe ₂ O ₃ (jl)], (5) ferrous oxide (molecular formula FeO, Hanai Chemicals Co., Ltd. )) [Abbreviated as Fe ₁ O ₁ (n)], (6) Mill scale fine powder (manufactured by JFE Steel Corporation, mixture with ferric trioxide mainly composed of ferrous oxide) [Fe ₁ O ₁ (J) and abbreviation], (7) triiron tetroxide (manufactured by Wako Pure Chemical Industries, Ltd., abbreviated to iron trioxide) [abbreviated as Fe ₃ O ₄ (w)], and the above seven types.

As shown in Table 9, the peeling ratio before immersion decreased as the PVA ratio increased. Moreover, the peeling ratio before immersion without using PVA depends on the type of iron oxide, and diiron trioxide (Fe ₂ O ₃ (w) and Fe ₂ O ₃ (js)) and triiron tetroxide ( Fe ₃ O ₄ (w)) had a PVA ratio of about 1% and a peel ratio before immersion of less than 2%. On the other hand, ferric trioxide (Fe ₂ O ₃ (d) and Fe ₂ O ₃ (jl)) and ferrous oxide (Fe ₁ O ₁ (n)) having a large particle size have a PVA ratio of about 5%, The peeling ratio before immersion was less than 2%. The peeling ratio before immersion of the mixture of ferrous oxide and ferric trioxide (Fe ₁ O ₁ (j)) was about 2% PVA, and the peeling ratio before immersion was less than 2%. All materials obtained sufficient water resistance when 1% PVA was added.

[Example 6C: Effect of PVA addition on reduced iron coating strength of rice seed]
Except for using reduced iron as a functional material, the same as in Example 6B, the amount of JM-17S used was 1 to 5% by weight of PVA, and 50% by weight of reduced dry iron seed weight was coated. Coated seeds were made (no gypsum added with a common iron coating). When the seed is coated with reduced iron, the coating strength increases in the process of reducing iron rusting. However, considering that one of the roles of PVA is to maintain the strength up to the formation of rust, the coating strength was investigated under conditions where the formation of rust was not sufficiently advanced. That is, after the coated seeds are made, without additional addition of water, immediately dried by ventilation, and without any discoloration to rust color, the peel rate before immersion of the coated seeds (but shaking for 30 seconds) and water resistance ( 10 seeds / 10 mL of water, but 3 days after adding water) were examined. Reduced iron is (1) reduced iron (manufactured by Wako Pure Chemical Industries, Ltd., Wako first grade, particle size smaller than Fe (j) shown below from appearance and touch) [Fe (w) is abbreviated], (2 ) Reduced iron (manufactured by JFE Steel Co., Ltd., iron powder (J6), average particle size of about 65 μm) [abbreviated as Fe (j)], and the above two types.

  As shown in Table 10, the peeling ratio before immersion decreased as the PVA ratio increased. In addition, when PVA was not added, water suspension was observed when seeded, but when PVA was added, suspension was lost and high water resistance was obtained.

[Example 7-1: Effect of addition of PVA on seed coating strength]
For air-dried rice seeds (variety: Nikomaru), various molybdenum materials (functional materials) equivalent to 0.2 mmol Mo / g air-dried seeds and PVA (JM-17S, PVA ratio 1% weight, used as particulate solid) In the same manner as in Example 1, using molybdenum), molybdenum material and PVA were attached to the surface of the seed while adding water by spraying, and the seed was naturally dried at room temperature to produce a coated seed. Moreover, according to the same conditions as described above except that PVA was not used for reference, a coated seed for reference was produced.

  The molybdenum materials used were slightly soluble molybdenum trioxide (manufactured by Nippon Inorganic Chemical Industry Co., Ltd., hereinafter abbreviated as “MoO”), ammonium molybdate (manufactured by Nippon Shin Metals Co., Ltd., hereinafter “MoPNH”). Or potassium molybdophosphate (manufactured by Nippon Shin Metals Co., Ltd., hereinafter abbreviated as “MoPK”).

  Next, in the same manner as in Example 1, the peel rate before immersion (shaking for 30 seconds) and water resistance (10 grains / 10 mL) of the obtained coated seeds were examined. In addition, water resistance was evaluated in the state immediately after shaking by adding water and shaking the test tube 4 days later (synonymous with 4 days after sowing).

  Since all the molybdenum materials used have the property of being cured by the addition of water, the peeling ratio before immersion was relatively low without using PVA. However, with the addition of PVA, the peeling ratio before immersion was extremely low at less than 1% (see Table 11). Moreover, as shown in FIG. 2 and Table 11, in the seed coated with PVA, the turbidity of water was suppressed in the water resistance test, and the water resistance was further improved as compared with the coated seed for reference.

[Example 2-2: Effect 2 of PVA addition on seed coating strength 2]
For air-dried rice seeds (variety: Nikomaru), various tungsten materials (functional materials) equivalent to 10% weight of air-dried seed weight and PVA (JM-17S, PVA ratio 10% weight, used as particulate solid) In the same manner as in Example 7-1, a tungsten seed and PVA were attached to the surface of the seed while spraying water, and the seed was naturally dried at room temperature to produce a coated seed. Moreover, according to the same conditions as described above except that PVA was not used for reference, a coated seed for reference was produced.

  The tungsten materials used are slightly soluble tungsten trioxide (WO), tungstic acid (WH), and ammonium tungstate phosphate (WPNH). These materials are manufactured by Wako Pure Chemical Industries, Ltd. is there.

  Next, in the same manner as in Example 1, the peel rate before immersion (shaking for 30 seconds) and water resistance (10 grains / 10 mL) of the obtained coated seeds were examined. The water resistance was evaluated in a state immediately after shaking by adding water and shaking the test tube 13 days later (synonymous with 13 days after sowing).

  Since all the tungsten materials used have the property of being cured by the addition of water, the peeling ratio before immersion was relatively low without using PVA. However, the addition of PVA lowered the peeling ratio before immersion to 2% or less (see Table 12). Further, in the coated seeds to which PVA was added, the occurrence of water turbidity was reduced in the water resistance test, and the water resistance was further improved compared to the coated seeds for reference (see Table 12).

[Example 8-1: Effect of mixing ratio of PVA on seed coating strength (3)]
For air-dried rice seeds (variety: Nikomaru), 50% heavier calcium peroxide material (Wako Pure Chemical Industries, Ltd., 25% calcium peroxide-containing product: functional material) or clay ( Neolite Kosan Co., Ltd., Ohira DL clay: functional material) and PVA (JM-17S, PVA ratio changed within the range of 0 to 10% weight, used as a particulate solid) and Example 1 Similarly, a functional seed and PVA were adhered to the surface of the seed while adding water by spraying, and the seed was naturally dried at room temperature to produce a coated seed.

  Next, in the same manner as in Example 1, the peel ratio before immersion (shaking for 30 seconds) and water resistance (10 grains / 10 mL) of the obtained reduced seeds were examined. In addition, water resistance was evaluated in a state immediately after shaking after adding water and shaking the test tube 1 day after (synonymous with 1 day after sowing).

  As shown in Table 13, in the coating of calcium peroxide material, the peeling rate before immersion exceeded 30% when PVA was not added, but when PVA was added at a PVA ratio of 1% weight, the peeling rate before immersion was 1%. Remarkably low. In addition, the calcium peroxide material can be coated with seeds without adding PVA, but cracking occurred and peeling was likely to occur. However, when PVA was added, cracks did not occur and peeling was difficult.

  In addition, as a result of the water resistance test, the calcium peroxide material showed little collapse when immersed in water without adding PVA, but the addition of PVA further suppresses the collapse when immersed in water. Thus, the water resistance was further increased (see also Table 13).

  On the other hand, in the case of coating with clay, the coating strength is remarkably weak unless PVA is added, and as the PVA ratio increases, the peeling ratio before immersion and the turbidity during immersion decrease and the coating strength tends to increase (see Table 13). ).

[Example 8-2 Rice Seed Coating by Mixing Partially Saponified PVA and Completely Saponified PVA]
For air-dried rice seed (variety: Nikomaru), coarse iron oxide (similar to Example 1: functional material) and potassium molybdophosphate (0.2 mmol Mo / g air-dried seed: 50% weight of air-dried seed weight: By using a mixture of functional materials) and PVA, in the same manner as in Example 1, the functional materials and PVA are adhered to the surface of the seeds while adding water by spraying, and naturally dried at room temperature. Coated seeds were produced.

  As PVA, in addition to the case where JF-17S, JP-18S, or JM-17S is used at a PVA ratio of 1% weight, a mixture of JF-17S and JP-18S with a PVA ratio of 1% weight is used. I examined the case.

  And according to the method similar to Example 1, the peeling ratio before immersion and water resistance were investigated. However, in the water resistance test, 10 coated seeds and 10 mL of water were put in each test tube, and the test tube was shaken 8 days after the addition of water.

  As shown in Table 14, the peeling ratio before immersion is 11% or less when JP-18S, JM-18S, or a mixture of JP-18S and JF-17S is used, and when JF-17S is used alone ( 46%). Moreover, water resistance was remarkably high when JF-17S or JM-17S was used, and when only JP-18S was used, the suspension of the coating material in water was slightly observed (FIG. 3). From the above, the intermediate saponified PVA can be used alone to prevent peeling before being immersed in water and to have water resistance. However, by using partially saponified PVA, peeling before immersion in water is prevented, and by using completely saponified PVA, water resistance is obtained, and when both are used in combination, prevention of peeling before immersion in water and water resistance are achieved. It can have sex.

[Example 9: Coating with a mixture of iron oxide and molybdenum material]
For air-dried rice seeds (variety: Nikomaru), fine iron oxide (functional material) 50% heavier than air-dried seed weight, various molybdenum materials (functional materials), and PVA (JM-17S, PVA ratio 1) In the same manner as in Example 1, the functional material and PVA are adhered to the seed surface while adding water by spraying, and air-dried at room temperature. The coated seeds were produced by

  The molybdenum material used was molybdenum trioxide (manufactured by Nippon Inorganic Chemical Co., Ltd.), ammonium molybdophosphate (manufactured by Nippon Shin Metal Co., Ltd.), or potassium molybdophosphate (manufactured by Nippon Shin Metal Co., Ltd.). . Moreover, the usage-amount of various molybdenum materials is an amount equivalent to 0, 0.02, 0.05, 0.1, 0.2, 0.5, 1 and 2 mmol Mo / g air-dried seeds.

  In any of the coated seeds, the functional material was not peeled off and did not disintegrate even when placed in water.

[Example 10: Coating of paddy rice seed with molybdenum material or tungsten material]
Implemented on air-dried rice seeds (variety: Nikomaru) using various molybdenum materials or tungsten materials (functional materials) and PVA (JM-17S, PVA ratio 1% weight, used as a particulate solid) In the same manner as in Example 1, a functional seed and PVA were adhered to the surface of the seed while adding water by spraying, and the seed was naturally dried at room temperature to produce a coated seed.

  Molybdenum material or tungsten material used is 0.1, 0.2, 0.5, and 1 mmol Mo or molybdenum metal powder in an amount equivalent to W / g air-dried seeds (Mo-H manufactured by Nippon Shin Metal Co., Ltd.) Or it is a tungsten metal powder (Nippon Shin Metal Co., Ltd. product, WH).

  In any of the coated seeds, the functional material was not peeled off and did not disintegrate even when placed in water.

[Example 11: Coating of wheat and buckwheat seeds with molybdenum material or tungsten material]
Air-dried wheat seeds (variety: Chikugoizumi), air-dried barley seeds (variety: Nishino Chikara), and air-dried buckwheat seeds (variety: Sachiizumi), various molybdenum materials or tungsten materials (functional materials), PVA (JM-17S, In the same manner as in Example 1, the functional material and PVA were adhered to the surface of the seed while adding water by spraying, using the PVA ratio 1% weight, used as a particulate solid). Coated seeds were produced by drying.

  The molybdenum materials or tungsten materials used were molybdenum trioxide (manufactured by Nippon Inorganic Chemical Industry Co., Ltd.), ammonium molybdate (Nippon Shin-Metal Co., Ltd.) in an amount equivalent to 0.1 or 0.2 mmol Mo or W / g air-dried seeds. Co., Ltd.), potassium molybdophosphate (manufactured by Nippon Shin Metals Co., Ltd.), and ammonium tungstate phosphate (manufactured by Wako Pure Chemical Industries, Ltd.).

  In any of the coated seeds, the functional material was not peeled off and did not disintegrate even when placed in water.

[Example 12: Coating of soybean seed with molybdenum material or tungsten material]
Example using various molybdenum materials or tungsten materials (functional materials) and PVA (JM-17S, PVA ratio 2% weight, used as a particulate solid) for air-dried soybean seeds (variety: Fukuyutaka) In the same manner as in No. 1, coated seeds were produced by adhering a functional material and PVA to the surface of the seeds while adding water by spraying and naturally drying at room temperature.

  The molybdenum or tungsten material used was molybdenum trioxide, molybdate, ammonium molybdate, potassium molybdate, tungsten trioxide, tungstic acid, or ammonium tungstophosphate in an amount equivalent to 0.5 mmol Mo / g air-dried seeds. And ammonium molybdophosphate. As for these materials, only potassium molybdate is manufactured by Nippon Shin Metal Co., Ltd., and others are manufactured by Wako Pure Chemical Industries, Ltd.

  In any of the coated seeds, the functional material was not peeled off and did not disintegrate even when placed in water.

[Example 13: Coating of iron oxide on a large amount of paddy rice seed]
3 kg of air-dried rice seed (variety: Nikomaru) was placed in a net bag and immersed in water at room temperature for 1 day. The paddy rice seeds were dehydrated with a dehydrator (Kubota SW-11) for 30 seconds. 10%, 20%, 30%, 40%, or 50% of iron-dried powder (Morishita Benzai Kogyo Co., Ltd., product name: No. 1094) with respect to 3 kg of air-dried seeds. , Iron (III) oxide (99% by weight), average particle size 0.57 μm) and PVA (JM-17S) corresponding to 1% weight of the iron oxide powder were sufficiently mixed. Into a seed coating machine (Kebunsha Seisakusho KC-151), 3 kg of air-dried dehydrated seeds were put, and the above mixed powder was added little by little while rotating the drum of the coating machine. When the amount of the mixed powder increases, a mixed powder that does not adhere to the seeds is produced. At that time, water was added to the seeds by spraying to adhere the mixed powder to the seeds. Furthermore, the operation of adding the mixed powder little by little and adding water by spraying was repeated, and all the mixed powder was able to adhere to the seeds.

  Also, the number of days of immersion in water was changed from 1st to 3rd (no germinating seeds were seen) and 20% or 50% of the air-dried seed weight was the above iron oxide powder (Morishita Bengal Kogyo Co., Ltd. ), Product name: No. 1094) was mixed with the PVA (JM-17S) corresponding to 1% weight of the iron oxide powder, and a coated seed was prepared in the same manner as described above. . Similarly, 20% or 50% of the air-dried seed weight is added to the above iron oxide powder (manufactured by Morishita Bengar Kogyo Co., Ltd., product name: No. 1094) in an amount equivalent to 0.05 mmol Mo / g air-dried seed. Coated seeds were also made with a mixed powder to which ammonium acid was added and the above PVA (JM-17S) corresponding to 1% weight of the total weight of iron oxide powder and ammonium molybdophosphate was added.

  After preparation of the coated seeds, they were spread to a thickness of about 3 cm and dried overnight at room temperature. Under either condition, peeling at the time of drying and peeling in water were hardly observed, and germination was normal.

[Reference Example 1: Effect of gypsum on rice seedling establishment]
The effect of gypsum on rice seedling establishment was investigated.

A paddy wet soil (collected in a paddy field in Chikugo City, Fukuoka Prefecture, stored refrigerated while wet) in an amount equivalent to 100 g of dry soil was collected in a container (cylindrical shape having a diameter of about 7 cm). To this was added an aqueous solution corresponding to 1.5 times the weight of dry soil (dissolving potassium chloride to 0.1 molK / m ^{2 in} terms of 100 kg / m ^{2 of} dry soil so that the soil would not disperse). The container was covered and shaken at room temperature for about 1 hour, and then allowed to stand at 4 ° C. for 2 days to prepare a flooded soil. The produced flooded soil had a soil layer of about 3.5 cm and a water layer on the soil surface of about 1 cm.

  Disinfection of air-dried seeds of paddy rice (variety: Hinohikari) for 10 minutes each in 70% ethanol and 5-fold diluted solution of sodium hypochlorite solution (purchased from Wako Pure Chemical Industries) It was immersed in water for 5 days and in water at 30 ° C. for about 1 day and allowed to germinate slightly. To this sprouting seed, calcined gypsum (chemical condition) of 0.00, 0.02, 0.05, 0.1, 0.2, 0.5, 1, 2 times the weight (8 conditions), respectively, with respect to the air-dried seed weight Baked gypsum, purchased from Wako Pure Chemical Industries, Ltd.) was mixed little by little while adding water by spraying, and gypsum (gypsum amount 8 conditions) was adhered to the germinated seeds. In addition, gypsum (gypsum amount 8 conditions) was also attached to air-dried seeds in the same manner as the germinated seeds.

  These treated seeds (presence / absence of sprouting × gypsum amount 8 conditions = 16 treatments) were sown on the flooded soil described above. In one container, eight seeds subjected to the same treatment were sown at a depth of 15 mm and at an interval of about 2 cm, and lightly shaken to close the seeding hole. Six containers were used for each treatment. The seeded container was left in a 30 ° C. incubator with a fluorescent lamp lit for only half a day without covering (hereinafter referred to as “30 ° C. germinated seed” or “30 ° C. air-dried seed”). ).

  Furthermore, for air-dried seeds, calcined gypsum (chemical conditions) of 0.00, 0.005, 0.01, 0.02, 0.05, 0.1, 0.2, 0.5 times weight (8 conditions), respectively. Baked gypsum, purchased from Wako Pure Chemical Industries, Ltd.), and the seeded container was placed in a 20 ° C. incubator similar to the above-described incubator (hereinafter referred to as “20 ° C. air-dried seed”). To do).

  Then, when the water on the soil surface decreased due to evaporation, the distilled water was supplemented. About 3 weeks after sowing (5 weeks for air-dried seeds at 20 ° C), the seedling establishment ratio (the ratio of the number of 3rd leaf extract individuals) of each container was investigated, and the average and standard error of the seedling establishment ratio by treatment were calculated. Asked.

  The rate of seedling establishment of paddy rice was highest when gypsum was not attached (the amount of calcined gypsum was 0 times the weight) regardless of the presence of sprouting and the treatment temperature, and the tendency was lower as the amount of gypsum attached was larger. The seedling establishment rate is 10% when 20% air-dried seeds are applied with a calcined gypsum more than 0.02 times the weight, 30 ° C air-dried seeds are more than 0.1 times the weight, and 30 ° C germinated seeds more than 1 time the weight. Less than.

Separately, these treated seeds were sown on the side surface of the glass container, and the vicinity of the seeds was observed through the glass. As the amount of gypsum attached increased, the vicinity of the seeds became darker. This black substance is considered to be iron sulfide (FeS) and suggests the generation of harmful sulfide ions (S ²⁻ ). From this result, it was considered that sulfate ions (SO ₄ ²⁻ ) contained in gypsum (CaSO ₄ · nH ₂ O) were reduced to sulfide ions (S ²⁻ ) in flooded soil. In other words, gypsum was considered to be one of the causes that deteriorated the seedling establishment of paddy rice.

  The present invention can be widely used in the agricultural field where crops are cultivated, particularly in rice cultivation.

Claims (15)

A polyvinyl alcohol having a saponification degree of 78 mol% or more, which is a particulate solid, is mixed with a functional material without substantially dissolving it, and using the liquid, the polyvinyl alcohol, the functional material, and the liquid are mixed. Forming a covering layer including the surface of the plant propagation body;
And a step of drying the coating layer. The above process of forming the coating layer on the surface of the plant propagation body is as follows:
1) A suspension obtained by suspending the polyvinyl alcohol and the functional material in the liquid is brought into contact with a plant propagation body, or
2) After mixing the polyvinyl alcohol and the functional material in a dry state, the obtained mixture is attached to the surface of the plant propagation body via the liquid.
The manufacturing method of Claim 1 performed by.   The production method according to claim 1 or 2, wherein the saponification degree of the polyvinyl alcohol is in a range exceeding 90 mol%.   The production method according to any one of claims 1 to 3, wherein the saponification degree of the polyvinyl alcohol is in the range of more than 90 mol% and less than 98 mol%.   The manufacturing method according to any one of claims 1 to 4, wherein the degree of polymerization of the polyvinyl alcohol is in the range of 1000 or more and 5000 or less.   The production method according to any one of claims 1 to 5, wherein the degree of polymerization of the polyvinyl alcohol is in the range of 1500 or more and 3500 or less.   The manufacturing method of any one of Claim 1 to 6 whose particle size of the said polyvinyl alcohol is 150 micrometers or less.   The said polyvinyl alcohol is a manufacturing method of any one of Claim 1 to 7 used within the range of 0.02% weight or more and 10% weight or less with respect to the weight of the said functional material.   The manufacturing method according to any one of claims 1 to 8, wherein the functional material is at least one selected from the group consisting of molybdenum material, tungsten material, iron material, oxygen generator, and clay. The molybdenum material is at least one selected from the group consisting of molybdenum metal, molybdenum oxide, molybdic acid and its salt, molybdophosphoric acid and its salt, molybdosilicic acid and its salt,
The tungsten material is at least one selected from the group consisting of tungsten metal, tungstophosphoric acid and its salt, tungstosilicic acid and its salt, tungsten oxide, and tungstic acid and its salt,
The iron material is at least one of iron oxide and reduced iron,
The oxygen generator is a material containing calcium peroxide (CaO ₂ ) as a functional component.
The manufacturing method according to claim 9.   The said iron material is a manufacturing method of Claim 9 or 10 which contains the iron oxide of a particle size of 1 micrometer or less in the ratio of 5 to 50 weight%.   The method according to any one of claims 1 to 11, wherein the plant propagation material is a seed.   The propagation material covering manufactured with the manufacturing method of any one of Claims 1-12.   The cultivation method of a plant including the planting process which plants the propagation body covering of Claim 13.   The cultivation method of the plant of Claim 14 which has a period when at least one part of a plant body is in a flooded state after the planting process and the seedling establishment period.