JP7253165B2 - Coating treatment method for plant seeds for direct seeding cultivation, coated plant seeds for direct seeding cultivation, and direct seeding cultivation method for plant seeds - Google Patents

Description

TECHNICAL FIELD The present invention relates to a coating treatment method for plant seeds for direct sowing cultivation, a coated plant seed for direct sowing cultivation, and a direct sowing cultivation method for plant seeds.

Currently, the number of farmers in Japan is decreasing and the number of farmers is aging. In order to cope with this situation, there is a demand for the development of new agricultural technologies that can save labor, reduce costs, and increase scale. ing.

Especially for paddy rice, which is the main crop, the decrease in the number of bearers in the snowy areas such as northern Japan, which is the main production area, and the aging population are remarkable and serious. , labor-saving, cost-saving, and scale-up are urgent issues compared to warmer regions.

Conventionally, as shown in FIG. 1A, paddy rice cultivation has been carried out by "transplant cultivation" in which seedlings grown to a certain size in greenhouses in early spring are transplanted into flooded paddy fields. However, since the time required for raising seedlings and transplanting occupies a large part of the labor time in the spring work of rice cultivation, there is a problem that it competes with the spring work in the cultivation of other crops.

Therefore, in recent years, in order to reduce the burden of agricultural work in spring, "direct seeding cultivation", which makes it possible to omit the above seedling raising and transplanting operations by directly sowing rice seeds in paddy fields, has been attracting attention as a promising cultivation technique. Direct seeding can be broadly divided into ``dry field direct seeding,'' in which seeds are sown in dry paddy fields before they are irrigated, and ``flooded direct seeding,'' in which seeds are sown in watered paddy fields. As shown in Fig. 1 (B), seeding is carried out in the spring after the snow melts (spring sowing) in both cases of "direct sowing in flooded fields" and "direct sowing in dry fields". It is characterized by germination and growth of seed rice in dry fields until around the 1.5 to 2.5 leaf stage, and then flooding. On the other hand, in "submerged direct seeding," seeds are sown in pre-filled paddy fields, but it is necessary to bring the topsoil of the paddy fields into contact with the seeds. Normally, seed rice floats on the surface of water due to its low specific gravity, and not only does it not settle in the topsoil of paddy fields, but there is also the risk of it being eaten by birds and the like. Therefore, for the purpose of increasing the specific gravity of seed rice, a method of sowing seed rice with an "iron coating" that coats the surface with iron powder is widespread (see, for example, Non-Patent Document 1 and Patent Document 1). .

Non-Patent Document 1 describes a method of direct seeding with iron-coated water, in which rice seeds are soaked in water at 15 to 20 ° C for 3 to 4 days to absorb water, then iron powder and calcined gypsum (calcium sulfate, 0 .5 hydrate, CaSO _4.1 /2 H ₂ O) mixture is coated on the surface of the seed rice, the heat generated by the oxidation reaction of iron is allowed to cool, and then the surface is further coated with calcined gypsum for finishing. Characterized by In this method, since the outermost layer of the seed rice is covered with a thin layer of calcined gypsum, it is said that the coating is less likely to break even if it receives a mechanical impact from a seeding machine. In addition, since the heat generated by the oxidation reaction of iron dries the soaked rice seeds that have absorbed water, it is also possible to store the coated rice seeds for a long period of time.

The method for producing iron powder-coated rice seeds described in Patent Document 1 includes adding iron powder to paddy rice seeds, and 0.5 to 2% by mass of sulfate (excluding calcium sulfate) and / Or add a chloride, further add water to granulate, supply water and oxygen, and cause the rust generated by the oxidation reaction of the metal iron powder to adhere and solidify the iron powder to the seed rice of paddy rice. Characterized by drying. In this method, the use of sulfates, chlorides or mixtures thereof is said to enable the seed rice to be effectively and economically coated with metallic iron powder without the use of binders such as gypsum of Paris. . In addition, it is said that the seed rice can be coated with a small amount of iron powder, and the iron powder solidified on the surface of the seed rice does not easily collapse even by mechanical impact.

Patent No. 4441645

Iron-coated Flooded Direct Seeding Manual 2010 (National Agriculture and Food Research Organization, Kinki Chugoku-Shikoku Agricultural Research Center, March 2010) Effect of early winter sowing and direct seeding of paddy rice in cold regions on growth and yield Shimono et al.

In snowy regions where the snow melts slowly, the period during which rice can be sown directly in the spring is short, and the topsoil of the field is in a state of excessive moisture around March, immediately after the snow melts. It was difficult to get the seedlings into the field, which limited the types of agricultural work that could be done.

In the methods described in Non-Patent Document 1 and Patent Document 1, in both cases, seeding is limited to the spring season after the snow melts (spring seeding), making it difficult to solve the above problems. .

In addition, in the methods described in Non-Patent Document 1 and Patent Document 1, the iron coating is intended to increase the specific gravity of the seed rice, prevent the seed rice from floating on the surface of the water during direct sowing, and bring it into contact with the topsoil of the paddy field. However, it was still difficult to solve the above problems.

Therefore, as shown in FIG. 1 (C), the present inventors directly sowed seed rice in dry fields from late autumn to early winter in the year before harvest, which is the off-season (early winter sowing), and allowed the seed rice to overwinter under snow. We have been conducting intensive tests and research on cropping patterns that sprout from April to May after the snow melts. Among them, it is clear that when untreated dry seed rice is sown in dry fields from late autumn to early winter the year before the harvest, the germination rate of the seed rice after the snow melts in the following year is about 5%, which is not a level that can withstand practical use. became (Non-Patent Document 2).

In order to improve the germination rate of plant seeds, which are extremely low, it is necessary that directly sown plant seeds remain dormant during the winter without absorbing water under snow cover, and start absorbing water in the spring after the snow melts. However, so far, no such control method has been found.

The present invention has been made in view of the above circumstances. A coating treatment method for plant seeds for direct sowing, which can improve the yield, eliminate competition in farming after the snow melts, and reduce the labor burden on producers, coated plant seeds and An object of the present invention is to provide a direct sowing method for cultivating coated plant seeds.

The inventors of the present invention have made intensive studies to solve the above problems, and found that plant seeds, especially seed rice of paddy rice, are not allowed to absorb water in advance, and the surface of the seed rice is coated with iron. In the period from late autumn to early winter, specifically around October to December before snowfall, when the seeds are directly sown in drained dry rice fields and allowed to overwinter, the germination rate is approximately It was found that it was improved by about 4 to 30 times. The present invention has been completed based on such findings. i.e.
(1) The method of coating plant seeds for direct sowing cultivation of the present invention is characterized by coating the surfaces of plant seeds in a dry state with a coating material without subjecting the plant seeds to germination treatment.

(2) In the method of coating plant seeds for direct sowing cultivation of the present invention, it is preferably considered that the coating material contains iron.

(3) In the coating treatment method of plant seeds for direct sowing cultivation of the present invention, at least iron powder in an amount of 0.5 to 1.9 times the dry weight of the plant seed is included as the iron, and the iron powder weight The surface of the plant seed is coated with the coating material containing 0.1 to 0.15 times the amount of calcined gypsum, and the coating material is coated with 0.025 to 0.075 times the weight of the iron powder. It is preferably considered to further coat the surface of the layer and oxidize the iron powder.
(4) In addition, in the method of coating a plant seed for direct sowing cultivation of the present invention, the plant seed is the seed of at least one plant selected from the group consisting of gramineous grains, vegetables and flowers. preferably considered.

(5) The coated plant seed for direct sowing of the present invention is characterized by being a dried plant seed whose surface is covered with a coating material without undergoing a germination treatment.
(6) In addition, in the coated plant seed for direct sowing of the present invention, the coating material contains at least iron powder in an amount of 0.5 to 1.9 times the dry weight of the plant seed and the weight of the iron powder The iron powder contains 0.1 to 0.15 times the amount of calcined gypsum, and is attached to the surface of the coating material layer and is 0.025 to 0.075 times the weight of the iron powder. The coated plant seed for direct sowing according to claim 5, characterized in that the is oxidized.

(7) The method for direct sowing of plant seeds of the present invention is characterized by sowing coated plant seeds in a field before snowfall in the year before harvest.

(8) In the method for direct sowing of plant seeds of the present invention, in the method for direct sowing of plant seeds according to (7), after seeding in the field, the soil surface is compressed to displace the plant seeds below the soil surface. It is preferably considered to be buried in.

According to the coating treatment method of plant seeds for direct sowing cultivation, the coated plant seeds for direct sowing cultivation, and the direct sowing method of the plant seeds of the present invention, the germination rate in early spring is so low that it cannot be used practically. In addition, in the direct sowing of plant seeds by sowing in early winter the year before harvest, the germination rate can be improved, and competition in farm work after the snow melt can be eliminated, making it possible to reduce the labor burden on producers.

(A) It is a schematic diagram showing work periods in conventional transplant cultivation of paddy rice. (B) It is a schematic diagram showing working periods in conventional direct seeding cultivation of paddy rice. (C) It is a schematic diagram showing the operation time in the direct sowing cultivation of the plant seed of the present invention. (a) is a graph showing the temperature, ground temperature, and deepest snowfall in a field in Takizawa City, Iwate Prefecture during a cultivation test period by early winter sowing of coated plant seeds and untreated seeds in the 2016/17 season. A graph with circles on the broken line indicates the temperature, and a graph with triangles on the solid line indicates the ground temperature. The solid line graph without markers indicates the maximum snowfall amount. (b) A graph showing the temperature, ground temperature, and deepest snowfall in a field in Takizawa City, Iwate Prefecture during a cultivation test period by early winter sowing of iron-coated plant seeds and untreated seeds in the 2017/18 season. 1 is a graph showing the germination rate after overwintering of paddy rice seeds of Example 1 and Comparative Example 1 sown in dry fields in early winter (before snow cover) the year before harvest. The test variety was "Hitomebore" produced in Takizawa, Iwate Prefecture. (a) is a graph showing the germination rate of dug seeds after early winter sowing of iron-coated plant seeds and untreated seeds in the 2016/17 season. (b) is a graph showing the germination rate of dug seeds after early winter sowing of iron-coated plant seeds and untreated seeds in the 2017/18 season. (c) is a graph showing the germination rate of dug seeds after early winter sowing of iron-coated plant seeds and untreated seeds in the 2016/17 season. (d) A graph showing the germination rate of dug seeds after early winter sowing of iron-coated plant seeds and untreated seeds in the 2017/18 season. It is a graph which showed the air temperature, the ground temperature, and the deepest snowfall amount of the field in each place during the cultivation test period by the early winter sowing of the iron-coated plant seed and the untreated seed in the 2017/18 season. (a) is Takizawa City, Iwate Prefecture, (b) is Kuroishi City, Aomori Prefecture, (c) is Sapporo City, Hokkaido, (d) is Daisen City, Akita Prefecture, and (e) is Tsu City, Mie Prefecture. there is (a) Graph showing the germination rate of dug seeds after early winter sowing (1 month after sowing) of iron-coated plant seeds and untreated seeds at 5 sites in the 2017/18 season. . (b) Graph showing germination of dug seeds after early winter sowing (1 month after sowing) of iron-coated plant seeds and untreated seeds at 5 sites in the 2017/18 season. . (c) Graph showing the germination rate of dug seeds after early winter sowing (4 months after sowing) of iron-coated plant seeds and untreated seeds at 5 sites in the 2017/18 season. . (d) Graph showing germination of dug seeds after early winter sowing (4 months after sowing) of iron-coated plant seeds and untreated seeds at 5 sites in the 2017/18 season. .

The coating treatment method for plant seeds for direct sowing cultivation of the present invention, the coated plant seeds for direct sowing cultivation by this treatment method, and the direct sowing cultivation method for plant seeds using the coated plant seeds are described below in detail. .

In this specification, the term "early winter sowing" is a so-called late autumn to early winter period from October of the year before harvest to around January of the following year, although it may vary slightly depending on the geographical conditions and weather conditions of the production area. and direct sowing of plant seeds in the field during the period before snowfall. That is, the period of "early winter sowing" includes the period of autumn sowing of seeds of general crops and a longer period than that.
In the present specification, the term "germination rate" means a numerical value indicating the ratio of plant sprouts emerging from the soil with respect to the total number of sown plant seeds, and the term "germination rate" , means a numerical value indicating the ratio of sprouts germinated from plant seeds to the total number of sown plant seeds, regardless of the presence or absence of soil. Therefore, the results of germination tests aimed at evaluating the original germination rate of plant seeds, and the results of digging up plant seeds once sown in a field and conducting germination tests in an indoor laboratory We use the term “rate”.

The coating treatment method for plant seeds for direct sowing cultivation of the present invention is characterized by coating the surfaces of dry plant seeds with a coating material without subjecting the seeds to germination treatment.

Any seeds of annual herbaceous plants, perennial herbaceous plants and woody plants can be used without particular limitation, as long as they are seeds of varieties that are usually used as cultivars. In the coating treatment method of plant seeds for direct sowing cultivation of the present invention, it is preferably considered that the plant seeds are seeds of at least one plant selected from the group consisting of gramineous grains, vegetables and flowers. Examples of such plants include Poaceae, Brassicaceae, Solanaceae, Legumes, Apiaceae, Allium, Liliaceae, Asteraceae, Rosaceae, Convolvulaceae, and Iridaceae.

One of the characteristics of the coating treatment method for plant seeds for direct sowing of the present invention is that the plant seeds in a dry state are not subjected to a sprouting treatment.

In general, a treatment for artificially germinating plant seeds before they are sown is called a germination treatment. Propulsive treatment can uniformize the germination state of plants, prevent feeding damage by birds and the like, and exterminate weeds by making target plants grow faster than competing weeds.

Suitable treatment for such sprouting treatment differs depending on the type of plant seed. Examples include gas treatment with acetylene, ether, hydrogen gas, etc., and chemical methods such as treatment with auxin and gibberellin, which are a type of plant hormone. In the case of woody plants, for example, it is known that dormant buds of lilac can be induced by low-temperature treatment, and that buds of cherry and forsythia can be induced by warm bath treatment.

On the other hand, paddy rice, which is one of the major crops in Japan, can be forced to germinate by allowing the seed paddy to absorb sufficient water. Specifically, a method in which seed rice is soaked in water for several days to absorb water necessary for germination and then placed overnight at 30 to 32°C, which is the optimum germination temperature, to promote germination is widely used.

In the present invention, it is important that the physical method, chemical method, low temperature treatment, warm bath treatment and water absorption treatment exemplified above are not performed. That is, in the present invention, such hypnotic treatment technically prevents plant seeds from breaking dormancy early after sowing and germinating, and dying due to being unable to withstand low temperatures under snow cover. It is one of the features.

In the present invention, it is preferable to use plant seeds with a high germination rate. As a method for selecting plant seeds with a high germination rate, various methods commonly used before sowing can be applied. For example, a method of performing a germination test in advance to calculate the germination rate, a method of salt water selection, and the like are exemplified. It is preferable to screen the plant seeds in this way and apply the coating treatment to the seeds with a high germination rate. One of the criteria for judging that the germination rate is high is, for example, a germination rate of about 75 to 95% in a germination test. By applying a coating treatment to such plant seeds with a high germination rate, the germination rate of the plant seeds after wintering can also be improved.

In the present invention, as the coating material for coating the surface of the plant seed, various coating materials conventionally used for seed coating can be used as long as they exhibit the function of preventing the water supply to the plant seed and can prevent the invasion of germs. can be applied without any particular limitation. Examples thereof include iron powder, a mixture of iron powder and calcined gypsum, silicone agents, and food additive materials containing starch. These coating materials may be used singly or in combination of two or more as a multi-coating material.

The food additive material, silicone agent, or the like as described above can be applied to the surface of the plant seed by a conventionally known method such as spraying.

In the method of coating plant seeds for direct sowing cultivation of the present invention, it is preferably considered that the coating material contains iron. In addition, in the method of coating plant seeds for direct sowing cultivation, at least iron powder containing 0.5 to 1.9 times the dry weight of the plant seed as iron, and 0.1 to 0.1 times the weight of the iron powder The surface of the plant seed is coated with the coating material containing 15 times the amount of calcined gypsum, and the surface of the layer of the coating material is further coated with 0.025 to 0.075 times the weight of the iron powder. and oxidizing the iron powder. In the present invention, the iron coating is not intended to increase the specific gravity of plant seeds, unlike the methods described in Non-Patent Document 1 and Patent Document 1, and as described above, plant seeds during wintering. It is intended to prevent the invasion of various bacteria and to prevent the water supply to the body.

Coating materials containing iron include, for example, those using only iron powder, those using a mixture of iron powder and calcined gypsum, and after coating the surface of plant seeds with starch, coating the surface of the starch layer with iron powder. Examples include those further coated with a mixture of calcined gypsum. Among them, it is preferable to use a mixture of iron powder and calcined gypsum because it is resistant to mechanical impact, acts to prevent water supply to plant seeds until after the snow melts, and exhibits an effect of preventing invasion of various bacteria. In a mixture of iron powder and gypsum of Paris, the gypsum of Paris is believed to act as a binder or adhesive. As for the mixture of iron powder and gypsum of Paris, it is also considered to use a commercially available premix mixture in which iron powder and gypsum of Paris are mixed in advance.

By supplying moisture to the coating material containing iron in this way, the oxidation reaction of iron proceeds and heat is generated. In the iron oxidation reaction, the temperature of the seeds may reach 100°C due to heat accumulation, but in that case, the plant seeds will die, so the overall work should be done so that the temperature of the plant seeds is 40°C or less. It is desirable to control the temperature to It is permissible for the plant seeds to be temporarily exposed to heat of about 50°C.

Examples of the iron powder include metallic iron powder such as reduced iron powder and atomized iron powder, iron oxide iron powder, and a mixture of metallic iron powder and iron oxide iron powder produced as industrial waste from shot blasting processes and the like. , agricultural iron powder, and the like. Regarding the mixture of metallic iron powder and iron oxide iron powder, it is preferable to increase the proportion of metallic iron powder from the viewpoint of reactivity. The degree of heat generation differs depending on the type of iron powder, but it is necessary to adjust the type, composition, mixing ratio, etc. of the iron powder so that the temperature of the plant seed does not exceed 40°C.

Among these iron powders, iron powders for agriculture are preferably used in consideration of production costs and ingestion of harvested products as food. The particle size distribution, particle shape, cross-sectional structure, and the like of these iron powders are not particularly limited. In addition, it is preferable because the iron powder easily adheres to the surface of the plant seed, and the coating operation using a granulator, which will be described later, can be completed in a short time.

The mixing ratio of the iron powder and the calcined gypsum in the coating material is, for example, as described above, the iron powder is 0.5 to 1.9 times the dry weight of the plant seed, and the calcined gypsum is the iron powder weight. A range of 0.1 to 0.15 times the amount is exemplified. Also, it is preferable to consider an embodiment in which the surface of the coating material layer containing iron powder and gypsum of Paris is further coated with finishing gypsum of 0.025 to 0.075 times the weight of iron powder. By coating plant seeds with a coating material containing iron powder and calcined gypsum in this way, the iron powder in the coating material can be oxidized, preventing water absorption of plant seeds and infection of pathogens by iron oxide. , can be prevented.
A specific example is preferably about 5 kg of iron powder and about 0.75 kg of calcined gypsum (including finishing gypsum) per 10 kg of plant seeds. If the mixing ratio of the iron powder and the calcined gypsum is within the above range, the resulting coated plant seeds are resistant to mechanical impact and exhibit the function of preventing moisture supply to the plant seeds until after the snow melts. , It is possible to prevent the invasion of various bacteria.

The coating layer formed by the coating material is preferably one layer or more, and may have a multilayer structure of two or more layers. When the coating layer has a multilayer structure, the composition and type of the coating material may be the same for all layers, or different compositions and types of coating materials may be used for each layer.

In addition to the above components intended for coating plant seeds, the coating material may preferably contain agricultural chemicals such as fertilizers and insecticides and fungicides. Examples of fertilizers include ammonium sulfate, urea, and coated urea fertilizers, which are nitrogen fertilizers. Examples of agricultural chemicals include fungicides such as thiuram agents and benlate agents. In this way, by blending fertilizers and pesticides in advance with the coating material, the fertilizers and pesticides can be reliably applied to the vicinity of the plant seeds. environmental load can also be reduced. Fertilizers and pesticides may be used by blending them with the coating material, or a layer consisting of only the fertilizers and pesticides may be formed and the surface of the layer may be covered with the coating material.

A working process for coating a plant seed with such a coating material will be described in detail below.

(1) Seed preparation step Dried plant seeds are sterilized. In the present invention, since it is necessary to avoid water absorption by the plant seeds, for example, a method of directly applying a disinfectant prepared to a working concentration to the surface of the plant seeds and drying immediately is exemplified. Any disinfectant that is commonly used for seed disinfection can be used without particular limitation.

After immersing the disinfected dry plant seeds in water for about 1 to 2 seconds, they are taken out of the water and immediately dehydrated with a dehydrator.

In the case of purchasing commercially available disinfected plant seeds, the step of seed disinfection can be omitted.

(2) Coating step In the step (1), the plant seeds that are slightly moistened only on the surface by the dehydrator and the coating material are put into a granulator and sprayed with a small amount of water. At that time, the amount of the coating material to be added is preferably about ⅓ of the total prepared amount. After confirming that the coating material has adhered to the surface of the plant seed, add the coating material, spray a small amount of water again, and apply the coating material until the coating layer formed by the coating material reaches the desired thickness described later. Repeat the process of applying the coating material to the seed surface.

At this time, if the coating material adheres to the rotating disk of the granulator, it is desirable to scrape off the coating material using a spatula or the like. If the coating material cannot be scraped off, spraying a very small amount of water on the coating material adhering to the rotating disk to soften it is considered so that the seeds do not absorb water.

As a granulator, any device that is commonly used for coating plant seeds can be used without any particular restrictions. Since heat is generated, it is preferable to use a plate-type rotary granulator open to the atmosphere, a pot mixer, a baby mixer, a concrete mixer from which stirring blades are removed, or the like for the purpose of dissipating heat. In other words, although there is heat generation due to the oxidation reaction, since the contents such as the plant seeds and the iron-containing coating material are rotationally mixed in the granulator, the heat release increases, so heat accumulation in the plant seeds is hardly recognized. do not have. Therefore, the temperature of the plant seeds does not reach 40° C. or higher, and it is considered that the plant seeds are hardly deteriorated or killed by heat.

After all of the prepared coating material has been applied to the plant seeds, a very small amount of water is sprayed to prevent the seeds from sticking together and forming clumps, and to prevent the seeds from adhering to the inner wall of the granulator. . At this time, it is desirable to adjust the amount so that the seeds do not absorb water, as in the case of spraying onto the rotating disk of the granulator.

In addition, in order to prevent the coating layer formed from the prepared coating material from peeling off, it is preferable to coat the surface of the coating layer with a finishing plaster of Paris, but not necessarily the surface of the coating layer. The step of covering with gypsum is not an essential step.

When the surface of the coating layer is coated with the finishing calcined gypsum, for example, the plant seeds to which the prepared coating material is completely adhered are not taken out from the granulator, and the finishing calcined gypsum is put into the granulator. and rotate for several minutes. At that time, water is sprayed when the surface of the plant seed coated with the prepared coating material has little moisture and the finishing plaster of Paris is difficult to adhere to, or when the surface of the plant seed is powdery. is considered. In this case, since the surface of the plant seed is coated with the already prepared coating material, it is considered that the seed hardly absorbs water. By coating the surface of the coating layer with the finishing gypsum of Paris in this way, it is possible to suppress the collapse of the coating layer due to mechanical impact when seeds are sown using a sowing machine. In addition, during wintering, the effect of preventing water supply to plant seeds and the effect of preventing invasion of various bacteria can be enhanced.

As soon as it is confirmed that the entire surface of the plant seed is sufficiently covered with the coating material, the rotation of the granulator is stopped, and the plant seed is immediately taken out and allowed to cool. The thickness of the coating layer formed of the coating material is not particularly limited as long as the coating layer does not collapse due to mechanical impact when seeding using a seeding machine.

(3) Cooling/drying process When a material containing iron is used as a coating material, the oxidation reaction between water and iron generates high heat. Therefore, in order to avoid high heat due to heat accumulation, the plant seeds obtained in step (2) should be spread thinly in a box with a wide bottom, instead of being left in a lump or immediately packed in a bag. is desirable. As such a box with a wide bottom, for example, a seedling box for raising rice seedlings can be suitably used. Also, when stacking seedling boxes, put square lumber between the boxes, use a seedling shelf or a container for transporting seedlings to secure air passages between the boxes and prevent heat from accumulating.・Drying is considered. When plant seeds are left in a lump, bagged immediately, or spread in nursery boxes and stacked without gaps between boxes, the temperature of the seeds may reach 100 ° C. due to heat accumulation. In such a case, the plant seeds will die, so it is permissible for the plant seeds to be temporarily exposed to heat of about 50 ° C., but the plant seeds should be kept at a temperature of 40 ° C. or less throughout the work. Temperature control is desirable.

When a coating material containing iron is used, as the drying progresses due to the heat generated by the oxidation reaction, the water content decreases and the reaction slows down, resulting in less heat generation. Cooling and drying of plant seeds can be completed in a short time by blowing air using an air blower or the like between boxes stacked at intervals. It is desirable to cool the plant seeds at least overnight.

In overnight plant seeds, the coating layer dries and turns brown mottled to light brown. This indicates that the iron contained in the coating was converted to iron oxide to some extent. The coating of iron oxide is relatively strong, and it is possible to sow seeds as they are using a seeding machine. However, depending on the seeding machine, the coating may be damaged or peeled off due to the mechanical impact, so it is preferable to further promote the oxidation of the coating.

Specifically, plant seeds that have been left overnight are sprayed with water while being placed in a nursery box or the like. At this time, if water is sprayed while the plant seeds are still in the granulator, the plant seeds may be rapidly heated and die. Therefore, it is necessary to spread it out thinly in a box with a wide bottom, just like when cooling.

As a guideline for the amount of water to be sprayed, it is desirable that the water does not accumulate in the seedling box or the like. If there is too much water, the plant seeds may absorb water and be forced to germinate, making it impossible to survive the winter.

With the plant seeds sprayed with water in this way spread out in seedling boxes, square lumber is sandwiched between the boxes, and air passages are secured between the boxes by using seedling racks or containers for transporting seedlings. Cool and dry again, making sure that no dust remains. By cooling and drying for at least one night, the coated plant seeds are discolored to rusty brown all over, but it is desirable to allow the coated plant seeds to dry completely by leaving them for about a week after discoloration. . This completely converts the iron powder in the coating into iron oxide. After confirming that the coated plant seeds are completely dry, they can be directly stacked or bagged, such as seedling boxes. Coated plant seeds can be stored until sowing in the same manner as ordinary plant seeds.

The thus-obtained coated plant seed for direct sowing of the present invention is characterized in that it is a dried plant seed whose surface is covered with a coating material without undergoing a germination treatment. .

As described above, the coated plant seeds are not subjected to germination treatment, and the plant seeds absorb little water and remain dry, so they do not germinate immediately and can be stored for a long period of time. be. In addition, in the coated plant seed of the present invention, collapse of the coating layer due to mechanical impact is suppressed when seeding using a sowing machine. Furthermore, during overwintering, it exerts a function to prevent water supply to plant seeds and an effect to prevent invasion of various germs.

Coated seeds must be subjected to a germination test before sowing. The germination test can be carried out by the same method as the usual germination test of plant seeds. For example, put about 100 coated plant seeds in a plastic petri dish with a diameter of 9 cm, and pour about 20 mL of water. An example of a method is to leave this in a constant temperature room controlled at 25° C. to 30° C. for one week, count germinated seeds and non-germinated seeds, and calculate the germination rate. By sowing coated plant seeds with good germination test results in actual fields, it is possible to increase the growth and yield of crops.

A method for directly sowing and cultivating such coated plant seeds will be described in detail below.

The method for direct sowing plant seeds of the present invention is characterized by sowing coated plant seeds in a field before snow cover in the year before harvest.

Conventionally, when plant seeds, especially seed rice of paddy rice, are directly sown, uncoated seed rice is sown in dry fields, or as described in Patent Document 1 and Non-Patent Document 1, seed rice that has been subjected to sprouting treatment is iron-fermented. After the coating process, "flooded seeding" is carried out, in which seed rice coated with iron is sown in water-filled paddy fields. However, as described above, all conventional direct seeding cultivation methods are based on the premise of spring sowing after the snow melts. In both cases, the uncoated seed rice was sown before snowfall the year before the harvest, and the iron-coated seed rice was sown before the snowfall the year before the harvest, after the seed rice was sufficiently water-absorbed to induce germination. , the germination rate after the snow melted was about 5%, which did not reach a level that could withstand practical use.

In the method for direct sowing of plant seeds of the present invention, as described above, dry plant seeds that have not undergone germinating treatment and that have hardly absorbed water are coated and sown in a field before snow cover in the year before harvest. As a result, the sprouting rate after the snow melts is improved by about 4 to 30 times as compared with the conventional method. The method of sowing paddy rice in early winter using such coated seeds has not been studied at all, and is a completely novel plant cultivation method discovered by the present inventors.

The term "before snow cover in the year before harvest" specifically means around October to December. However, depending on the region and climate, seeds may be sown around January of the harvest year. In any of the above seasons, if the topsoil of the field is in a non-frozen state and before snow cover, directly sown coated plant seeds have an improved germination rate after the snow melts.

On the other hand, even within the above period, if the field is covered with snow and the plant seeds that have been coated are sown on top of the snow, the germination rate after the snow melts is low, and it is at a level that can withstand practical use. does not reach Also, when the topsoil in the field is completely frozen, the germination rate after the snow melts is low and does not reach a level that can withstand practical use.

Even in such a case, when the topsoil of the field is plowed and the topsoil becomes unfrozen, the directly sown coated plant seeds have an improved germination rate after the snow melts. do.

In addition, if there is plant residue such as rice straw on the topsoil, the seeds will fall on the rice straw during sowing and will not be buried in the soil. , the rate of germination after snowmelt is low, and does not reach a level that can withstand practical use. When the rice straw is plowed into the soil, the seeds are buried in the soil, and the stable soil temperature reduces damage caused by freezing and thawing, which improves the germination rate.

When sowing coated plant seeds, in addition to manual seeding, various types of equipment commonly used for direct seeding, such as power sprayers, radio-controlled helicopters, dedicated direct seeders, multi-purpose rice transplanters, and side row fertilizers for rice transplanters, are used. A seeding machine or the like can be used as appropriate.

In the method for direct sowing plant seeds of the present invention, in the method for directly sowing plant seeds described above, it is preferred that after seeding in a field, the surface of the soil is compressed and the coated plant seeds are buried under the surface of the soil. considered. The depth at which the plant seeds are buried can be appropriately changed according to the temperature and snow depth of the region, and is exemplified in the range of about 2 to 3 cm, for example. If the depth is within the above range, the germination rate of coated plant seeds can be improved. Also, it is preferable to consider embedding the plant seeds under the surface of the soil by covering the surface of the coated plant seeds sown in the field with culture soil.

When the coated plant seeds are directly sown in a field, it is preferable to form grooves in the field in advance and perform row sowing.

When burying coated plant seeds under the surface of the soil, workers may step on the soil to bury it, trampling with a tractor, or crushing with smooth rollers, spiral rollers, packer rollers, etc. A machine or the like may be used to cover the surface of the plant seed with soil. Actually, it is more efficient and preferable to use a working machine than to manually bury the coated plant seeds in the soil.

When the plant seeds are rice seeds of paddy rice, the coated plant seeds (seeds) directly sown in the field as described above germinate and grow to about the 3-leaf stage. It is desirable to As for the method of cultivating paddy rice after flooding, the same method as in transplant cultivation can be applied.

The seeding amount of coated plant seeds is not particularly limited, but for example, a range of about 2 to 5 times the seeding amount when directly sown in the field in spring without coating treatment is exemplified. be done. More specifically, for example, when the plant seeds are seeds of paddy rice, it is preferable to sow about 12 kg/10a to 30 kg/10a. If the amount of seeding is within the above range, the same level of yield can be expected as in existing transplanted cultivation or cultivation directly sown in the field in spring.

Examples are shown below, but the coating treatment method of plant seeds for direct sowing cultivation, the coated plant seeds, and the direct sowing cultivation method of the coated plant seeds of the present invention are in no way limited by these examples. not a thing

<A. Direct sowing test of coated plant seeds in Iwate Prefecture>
(Example 1)
(1) Seed preparation process Harvested in 2016, the dried seed rice of Hitomebore produced in Takizawa, Iwate Prefecture, before threshing, was immersed in water for about 1 to 2 seconds, then pulled out of the water and immediately dehydrated with a dehydrator.

(2) Iron coating process For 10 kg of dry seed rice, 5 kg of commercially available agricultural iron powder (DOWA IP Creation Co., Ltd., Okayama) and 0.5 kg of calcined gypsum (Mutsumi Kagaku Kogyo, Mie) are well mixed. A mixture was prepared. About 1/3 of the iron powder mixture was weighed out, and put into a baby mixer (Koyo Kikai Sangyo Co., Ltd., Osaka) together with seed rice whose surface was slightly moistened by a dehydrator in step (1), and then sprayed. was used to spray a small amount of water. After confirming that the iron powder mixture adhered to the surface of the seed rice, the iron powder mixture was added, and a small amount of water was sprayed again using the atomizer to adhere the iron powder mixture to the surface of the seed rice.

At this time, if the iron powder mixture adhered to the rotating disk of the baby mixer, it was scraped off using a spatula or the like. In addition, when the iron powder mixture could not be scraped off, the iron powder mixture adhering to the rotating disc was sprayed with a very small amount of water to soften it and then scraped off so that the seeds would not absorb water.

After all of the prepared iron powder mixture is attached to the seed rice, add a very small amount of water to the extent that the seeds do not absorb water so that the seed rice does not stick to each other and become clumpy or adhere to the inner wall of the baby mixer. was sprayed.

The finishing plaster of Paris was put into a baby mixer, sprayed with a small amount of water, and spun for a few minutes to form a layer of plaster of Paris on top of the iron powder mixture coating layer. As soon as it was confirmed that all the charged calcined gypsum for finishing had adhered to the surface of the seed rice, the rotation of the baby mixer was stopped, and the rice seed was immediately taken out and allowed to cool. In addition, it was confirmed that the total thickness of the coating layer formed on the surface of the removed rice seed was about 3 mm.

(3) Cooling/drying process The seed rice coated with the iron powder mixture obtained in the process (2) is spread in seedling boxes for raising rice seedlings, and rectangular timbers are sandwiched between the boxes for air passage. It was stacked on top of each other, and cooled and dried overnight while avoiding heat build-up. If necessary, air was blown between the seedling boxes stacked at intervals using an air blower or the like.

On the surface of the overnight seed rice, we confirmed that the coating layer had dried and changed color from brown mottled to light brown. Water was sprayed while still in the seedling box. The seedling boxes in which the water-sprayed seed rice was spread were housed in each shelf of the seedling-raising rack, and air passages were secured between the boxes to prevent heat buildup, and the seedlings were cooled and dried again. By cooling and drying overnight, it was confirmed that the iron-coated rice seeds were entirely discolored to a brown rust color, and the iron-coated rice seeds were left as they were for about a week to dry completely. . After confirming that the iron-coated seed rice was completely dry, the seedling boxes were directly stacked and stored in a dry place away from direct sunlight and humidity until seeding.

(4) Direct sowing process of coated seed rice to field was cultivated in an experimental paddy field (39°46′N, 141°7′E) of Takizawa Farm attached to Iwate University in Takizawa City, Iwate Prefecture.

After harvesting the previous paddy rice on October 10, 2016, sowing was carried out by plowing to a depth of 15 cm with a rotary, and making a 2 cm deep groove (2 cm wide) in the field that had been leveled with a paddy harrow. (30 cm between furrows, 30 cm in length), 30 grains of iron-coated seed rice were sown on November 25, 2016 and covered with culture soil (non-fertilizer culture soil, manufactured by Aikei Co., Ltd., Akita). After June 13, 2017, the flooded conditions were set.
In addition, in order to investigate the survival rate of seeds during wintering by the germination test of the extracted seeds described later, the sowing of iron-coated seed rice was done with a polyethylene draining net (net type draining net, DCM Holdings Co., Ltd.). Thirty seeds were placed, sown in the groove, and covered with non-fertilizer culture soil to a depth of 2 to 3 cm.

(5) Measurement of meteorological data Of the meteorological data during the cultivation test period, for soil temperature, a temperature sensor (TR52S, manufactured by T&D Corporation) was installed at the same depth of 2 to 5 cm as the seeds in the test area, It was recorded at intervals of 30 minutes, and the daily average soil temperature was calculated. Daily average temperature and daily snowfall data were obtained from the Japan Meteorological Agency website. The number of days covered with snow and the cumulative amount of snowfall were calculated from the sowing date of each test site to the end date of snow cover/snowfall. The number of days covered with snow was the total number of days when snow was observed. For meteorological data from Takizawa Farm attached to Iwate University, data from Morioka Meteorological Observatory (Iwate Prefecture), the nearest municipal observatory, was used.
As shown in Fig. 2(a), the lowest temperature in the field in Takizawa City, Iwate Prefecture between November 25, 2016 and June 13, 2017 was -6.8°C (January 14, 2017). ) and the lowest soil temperature was 0°C. In addition, the deepest snowfall amount in a field in Takizawa City, Iwate Prefecture between November 25, 2016 and June 13, 2017 was 24 cm (February 20, 2017).
(Example 2)
Iron-coated seed rice was produced in the same manner as in Example 1, except that the dried seed rice of "Hitomebore" from Takizawa, Iwate Prefecture, which was harvested in 2017 and was threshed before hulling, was used. and cultivated under the same conditions as in the example.
For early winter sowing in 2017, seeds were sown on December 6, 2017 and covered with potting soil. After June 20, 2018, the flooded conditions were set.
As shown in Figure 2(b), the lowest temperature in the field in Takizawa City, Iwate Prefecture between December 6, 2017 and June 20, 2018 was -7.2°C (January 24, 2018). ), and the lowest ground temperature was around 0°C. In addition, the deepest snowfall in a field in Takizawa City, Iwate Prefecture between December 6, 2017 and June 20, 2018 was 47 cm (February 14, 2018).
(Example 3)
Iron-coated seed rice was produced in the same manner as in Example 2, except that "Masshigura" from Hirosaki, Aomori Prefecture was used as the dry seed rice, and sown in a field in Takizawa City, Iwate Prefecture. Cultivation was carried out in the same manner as in Examples.
(Example 4)
Iron-coated seed rice was produced in the same manner as in Example 2 except that ``Akitakomachi'' produced in Takizawa, Iwate Prefecture was used as the dry seed rice, and sown in a field in Takizawa City, Iwate Prefecture. Cultivation was carried out in the same manner as in Examples.
(Example 5)
Iron-coated seed rice was produced in the same manner as in Example 2, except that "Moeminori" from Takizawa, Iwate Prefecture was used as the dry seed rice, and sown in a field in Takizawa City, Iwate Prefecture. was cultivated in the same manner as in Examples.

(Comparative example 1)
Cultivation was carried out under the same conditions as in Example 1 except that the dry seed rice of "Hitomebore" from Takizawa, Iwate Prefecture, harvested in 2016 and threshed before hulling, was not subjected to iron coating treatment.
(Comparative example 2)
Cultivation was carried out under all the same conditions as in Example 1, except that the Culper treatment was performed instead of the iron coating treatment.
Culper treatment was performed according to the following steps. That is, as in the seed preparation process for the iron coating treatment, the dried rice seeds were immersed in water for about 1 to 2 seconds, pulled out of the water, and immediately dehydrated with a dehydrator. For 10 kg of dehydrated seed rice, weigh the same amount of Culper powder granules (manufactured by Mitsui Chemicals Agro Co., Ltd.), put it in a baby mixer together with the dehydrated seed rice, and spray a small amount of water using a sprayer to remove the seed rice. The surface was coated with Kalper granules.
(Comparative Example 3)
Cultivation was carried out under all the same conditions as in Example 1, except that the treatment with Inagel, which is a starch material, was performed instead of the iron coating treatment.
The inagel treatment was performed according to the following steps. That is, as in the seed preparation process for the iron coating treatment, the dried rice seeds were immersed in water for about 1 to 2 seconds, pulled out of the water, and immediately dehydrated with a dehydrator. Weigh 2.3 times the amount of Inagel (Inagel gum arabic A granules, manufactured by Ina Food Industry Co., Ltd.) for 10 kg of dehydrated seed rice, and dissolve it in distilled water so as to obtain a 30% (w/w) solution. rice field. The dehydrated rice seeds were placed in a plastic bag, and the aqueous Inagel solution was sprayed using a sprayer to coat the surface of the rice seeds with the aqueous solution of Inagel, followed by air drying.
(Comparative Example 4)
Cultivation was carried out under the same conditions as in Example 1 except that the dry seed rice of "Masshigura" from Hirosaki, Aomori Prefecture, harvested in 2016 and threshed before hulling, was not subjected to iron coating treatment. .
(Comparative Example 5)
Cultivation was carried out under the same conditions as in Example 2 except that the dry seed rice of "Hitomebore" from Takizawa, Iwate Prefecture, harvested in 2017 and threshed before hulling, was not subjected to iron coating treatment.
(Comparative Example 6)
Cultivation was carried out under the same conditions as in Example 2 except that the dry seed rice of Hirosaki, Aomori Prefecture, harvested in 2017 and threshed, was not subjected to iron coating treatment. .
(Comparative Example 7)
Cultivation was carried out under the same conditions as in Example 2 except that the dry seed rice of "Akitakomachi" from Takizawa, Iwate Prefecture, harvested in 2017 and threshed before hulling, was not subjected to iron coating treatment.
(Comparative Example 8)
Cultivation was carried out under the same conditions as in Example 2 except that the dry seed rice of "Moe Minori" from Takizawa, Iwate Prefecture, harvested in 2017 and threshed, was not subjected to iron coating treatment.
For the seeds of Examples and Comparative Examples, the germination rate was investigated and the germination test of dug seeds was conducted by the following methods.
(6) Investigation of germination rate The investigation of the germination rate in the 2016/17 season was conducted a total of 7 times during the period from May 19th to June 9th in order to compare the transition of germination. The survey of the germination rate in the 2017/18 season was conducted seven times in total during the period from May 25 to June 28 in early winter seeding cultivation. The germination rate was defined as the ratio of germinated seeds to the number of sown seeds. The start of budding and the uniformity of budding were defined as the days when the germinating rate reached 20% and 80%, respectively, and the number of days of budding was defined as the period between the beginning of budding and the uniformity of budding.
(7) Germination Test of Digged Seeds Seeds were dug up about every other month after sowing, and a germination test was performed at a maximum of 5 times. The dug-up seeds were removed from the draining net to remove the adhering soil, placed in a petri dish lined with wet filter paper, and placed in a thermostatic chamber (IC402, Yamato Scientific Co., Ltd.) at 25° C. in the dark. The germination rate was investigated on the 4th day, 7th day and 14th day after placing. The germination ability was defined as the ratio of the number of germinated seeds to the total number of seeds cultured in a constant temperature machine set at 25°C. In addition, as an index of germination vigor, the horizontal axis is the number of days after placement and the vertical axis is the germination rate, and the number of days until the germination rate reaches 50% of the final germination rate is determined by a linear regression formula as D50. rice field. A smaller D50 indicates stronger germination, and a larger D50 indicates weaker germination.
(8) Statistical Analysis Statistical analysis was performed on the survey results of the germination rate and the results of the germination test of dug seeds by the following methods. That is, the t-test was performed using statistical analysis software (Excel statistics Bellcurve for Excel 2.15) for the effect of the coating treatment on the germination rate. In addition, the effect of the coating treatment on the germination rate and D50 in the multipoint digging survey was statistically analyzed by Fisher's least significant difference method using the statistical analysis software.

(result)
As shown in the graph of FIG. 3, the germination rate of Comparative Example 1, which was not subjected to the iron coating treatment, was about 2%, which did not reach a level that could withstand practical use. On the other hand, it was confirmed that the iron-coated Hitomebore seed rice of Example 1 had a germination rate of about 25%, which was more than 10 times higher than that of Comparative Example 1.

In addition, as shown in Table 1, improvement in the germination rate of "Hitomebore" seed rice was observed in the culper treatment in Comparative Example 2 and the coating treatment using Inagel in Comparative Example 3, which are agricultural materials for coating other than iron. I couldn't.
Furthermore, as a result of the iron coating treatment on rice varieties other than "Hitomebore", it was confirmed that the germination rate of "Akitakomachi" improved at least four times from the comparison between Example 4 and Comparative Example 7. It was confirmed from the comparison between Example 3 and Comparative Example 6 that the rate of germination was improved up to about 20 times for "Mashigura".
In Iwate Prefecture, the germination rate of untreated seeds in spring sowing cultivation, which is the customary law, is 57-77% for 'Hitomebore', 59-67% for 'Mashigura', 71% for 'Akitakomachi', and 71% for 'Moeminori'. It was confirmed that there was no problem with the germination rate of the seed rice itself used in the cultivation test.
In the 2016/17 season, when early winter sowing cultivation was performed in Aomori Prefecture, the germination rate of seeds without iron coating treatment was higher than the result of early winter sowing cultivation in Iwate Prefecture, but iron coating treatment was performed. In plots, the germination rate was even higher. Therefore, although the germination rate of plant seeds itself varies depending on environmental factors such as the cultivation site and annual weather conditions, it was confirmed that the iron coating treatment of the present invention can increase the germination rate regardless of environmental factors. .

As shown in Table 2, the start of germination was May 20-22 in the spring sowing cultivation, whereas it was May 21-22 in the early winter sowing cultivation, which was delayed by about one day. The number of days from the beginning of budding to the uniformity of budding is several days longer in the early winter sowing cultivation. Specifically, in the spring sowing cultivation, budding was completed in 4 to 8 days, whereas in the early winter sowing cultivation, it took 7 to 9 days. . Looking at the effect of the iron coating, no significant difference was observed in the 2016/17 season, but in the 2017/18 season, the iron coating reduced the number of days from the beginning of budding to 3 days from the beginning of budding. It was confirmed that the germination period was shortened by 3 to 9 days as a result of ∼5 days earlier and 4 to 10 days earlier for the uniformity of germination.

FIGS. 4A, 4B, 4C, and 4D are graphs showing the germination rate and germination vigor of dug seeds. Seeds sown in the early winter sowing cultivation were periodically dug up from the field, and the germination rate was evaluated as the germination ability under culture conditions of 25°C.
First, looking at Comparative Example 1 without treatment, as shown in FIG. Although it was relatively stable, it decreased further after the snow melted, and decreased to 12% 4 months after sowing. In the 2017/18 season when snow fell early, the untreated Comparative Example 7 showed a high germination rate of 74% even one month after sowing, as shown in FIG. 4(c). However, the germination rate dropped sharply two months after sowing, and decreased to 6% five months after sowing. As shown in Example 1 of FIG. 4A and Example 3 of FIG. and maintained a germination rate of 30% or more even after 5 months after sowing.
On the other hand, D50, which is an index of germination, is about 2 days in the 2016/17 season, and varies from 2 to 6 days in the 2017/18 season, as shown in FIGS. 4(b) and 4(d). , was not affected by the iron coating.

<B. Direct sowing test in multiple areas of iron-coated plant seeds>
In the 2017/18 season, a direct sowing test of iron-coated plant seeds was conducted at five sites in Japan, and the results were compared.
Specifically, in addition to Takizawa City, Iwate Prefecture, Sapporo City, Hokkaido (Faculty of Agriculture, Hokkaido University, 43.1 ° N, 141.3 ° E), Kuroishi City, Aomori Prefecture (Aomori Industrial Technology Center Agriculture and Forestry Research Institute, 40. 7°N, 140.6°E), Daisen City, Akita Prefecture (Tohoku Agricultural Research Center Daisen Base, 39.5°N, 140.5°E), Tsu City, Mie Prefecture (Faculty of Bioresources, Mie Prefecture, FSC affiliated farm, A cultivation test was conducted at 34.7°N, 136.5°E).
(Example 6)
Iron-coated seed rice was produced in the same manner as in Example 2, except that "Akitakomachi" from Takizawa, Iwate Prefecture, which was harvested in 2017 and was threshed before hulling, was used as the dry seed rice. All the conditions were the same as in Example 2, and early winter sowing cultivation was carried out. In addition, in Sapporo City, November 28, 2017 was set as the sowing date.
(Example 7)
Iron-coated seed rice was produced in the same manner as in Example 2, except that "Akitakomachi" from Takizawa, Iwate Prefecture, which was harvested in 2017 and was threshed before hulling, was used as the dry seed rice. The seeds were sown in a field in the city, and all the conditions were the same as in Example 2, and early winter sowing cultivation was carried out. In Kuroishi City, November 30, 2017 was set as the sowing date.
(Example 8)
Iron-coated seed rice was produced in the same manner as in Example 2, except that "Akitakomachi" from Takizawa, Iwate Prefecture, harvested in 2017 and threshed before hulling, was used as the dry seed rice, and Daisen, Akita Prefecture. The seeds were sown in a field in the city, and all the conditions were the same as in Example 2, and early winter sowing cultivation was carried out. In Daisen City, December 1, 2017 was set as the sowing date.
(Example 9)
Iron-coated seed rice was produced in the same manner as in Example 2, except that "Akitakomachi" from Takizawa, Iwate Prefecture, harvested in 2017 and threshed before hulling, was used as the dry seed rice. The seeds were sown in a field in the city, and all the conditions were the same as in Example 2, and early winter sowing cultivation was carried out. In Tsu City, November 28, 2017 was set as the sowing date.
(1) Measurement of meteorological data Of the meteorological data during the cultivation test period, the soil temperature was recorded at intervals of 30 minutes by installing a temperature sensor at the same depth of 2 to 5 cm as the seeds in the test area. Daily average soil temperature was calculated. Daily average temperature and daily snowfall data were obtained from the Japan Meteorological Agency website. The number of days covered with snow and the cumulative amount of snowfall were calculated from the sowing date of each test site to the end date of snow cover/snowfall. The number of days covered with snow was the total number of days when snow was observed. The data acquisition sites for each test site are the observatories of the municipalities where the test sites are located or the nearest municipal observatories, Sapporo Meteorological Observatory (Hokkaido), Hirosaki AMeDAS (Aomori Prefecture), Kakunodate AMeDAS (Akita Prefecture), and Tsu Meteorological Observatory. (Mie Prefecture) was used. The results are shown in FIG.
(2) Germination test of dug-up seeds In Hokkaido, Aomori, Akita and Mie prefectures, seeds sown in early winter were dug up in two periods (one month and four months after sowing), and the dug-up seeds were collected at each site. After transportation and storage (4°C, dark conditions) to the laboratory of Iwate University by refrigerated delivery, the seeds at all points were subjected to a germination test at the same time. The results are shown in FIG.
(3) Statistical Analysis Statistical analysis was performed by Fisher's least significant difference method using the statistical analysis software described above for the effect of the coating treatment and cultivation site on the germination rate and D50 in the multipoint digging survey.

(result)
Figure 5 (a), (b), (c), (d), and (e) are graphs showing the temperature, ground temperature, and snowfall in Iwate, Aomori, Hokkaido, Akita, and Mie prefectures in the 2017/18 season, respectively. be.
As shown in Fig. 5(a), changes in air temperature, soil temperature, and snowfall from seeding to germination show that in Iwate Prefecture, where there is snow, the seeding season from late November to early December is The ground temperature was 10 to 12°C, but then decreased almost linearly to 0°C in January, and stabilized at around 0°C under snow cover. Ground temperature rose after snowmelt.
From the point of view of soil temperature, which directly affects the seed environment, it can be divided into three periods: (1) the period from sowing to snow cover, (2) the period of stable snow cover, and (3) the period from snowmelt to germination. can. In periods (1) and (3), most of the ground temperature fluctuations were explained by air temperature. was This tendency was common in Hokkaido, Aomori Prefecture, and Akita Prefecture where there is snow, as shown in FIGS.
The number of days in period (2) varies by region, with Hokkaido, Akita, and Aomori having longer snow cover periods than Iwate. The number of snow days was 119 in Hokkaido, 109 in Aomori, 86 in Iwate, and 117 in Akita. Also, the cumulative amount of accumulated snow was 403 cm in Hokkaido, 484 cm in Aomori Prefecture, 205 cm in Iwate Prefecture, and 649 cm in Akita Prefecture. On the other hand, as shown in Fig. 5(e), in Mie Prefecture, where there is no snow cover, even in December to February, which corresponds to the period (2) in which ground temperature fluctuations were small in cold regions such as the above four prefectures, A large variation in soil temperature was observed.

In the 2017/18 season, iron-coated seed rice was sown in early winter at a total of 5 locations in Hokkaido, Aomori, Akita, and Mie prefectures in addition to Iwate Prefecture. The excavation test was performed at two times. One month after sowing, when comparing the iron-coated seeds of the example and the untreated seeds of the comparative example, as shown in FIG. 74% and 64% of the germination rate of Example 6 which is an example of Hokkaido is high, Example 7 which is an example of Aomori Prefecture, Example 8 which is an example of Akita Prefecture and Example of Mie Prefecture Implementation which is an example Example 9 followed with a germination rate of 46-56%.
Four months after sowing, as shown in FIG. 6(c), the germination rate decreased at all sites, but there were regional differences. The germination rate of Example 7, which is an example in Aomori Prefecture, was maintained at an extremely high level of about 55%, but the germination rate of Example 8, which is an example in Akita Prefecture, was about 25%. . On the other hand, for untreated seeds, the germination rate of comparative seeds in Aomori Prefecture was the highest at 22%, and it was confirmed that the germination rates of comparative examples at other locations decreased to 2 to 12%. rice field.

Therefore, from the results of FIGS. 6(a) and (c), the iron coating treatment has a significant positive effect on the germination rate at both the 1st and 4th months after sowing and at any point. was recognized. Averaging the effects, the iron coating treatment was thought to increase the germination rate of plant seeds grown in early winter sowing by about 26%. On the other hand, as shown in FIGS. 6(b) and 6(d), the D50, which is an index of the vigor of budding, shows clear regional differences and time periods, except for Example 8, which is an example of iron coating treatment in Akita Prefecture. No differences and inter-treatment differences were observed.

Claims (3)

A direct seeding cultivation method for improving the germination rate of seeds of gramineous cereals in early winter sowing,
Coated plant seeds obtained by coating dry grass seeds with a coating material containing either iron powder or a mixture of iron powder and calcined gypsum without subjecting the seeds to germination treatment,
A method for direct sowing and cultivating plant seeds, characterized by sowing seeds in a field during the period from late autumn to early winter of the year before harvest. The coating material comprises a mixture of iron powder and plaster of Paris,
At least, the coating material containing 0.5 to 1.9 times the dry weight of the plant seed iron powder and 0.1 to 0.15 times the weight of the iron powder gypsum 0.025 to 0.075 times the weight of the iron powder, further coating the surface of the layer of the coating material with 0.025 to 0.075 times the weight of the iron powder, and oxidizing the iron powder. 1. The direct seeding cultivation method according to 1. 3. The direct seeding cultivation method according to claim 1 or 2 , wherein after sowing the seeds in the field, the soil surface is compressed to bury the plant seeds under the soil surface.

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