JPH0576922B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a dusting agent used to coat seeds for the purpose of improving germination and growth of directly sown rice seeds. [Conventional technology] In recent years, there has been an increasing demand for the development of labor-saving and cost-reducing techniques in rice cultivation. One of these is the direct seeding cultivation technique for rice. This technology eliminates the need for raising seedlings and planting rice, which is required in conventional technology, and thus greatly contributes to labor reduction and cost reduction, and various studies are being conducted to perfect this technology. The biggest problem with direct-seeding rice cultivation is that the rice seeds lack oxygen in the soil, making germination and seedling establishment (the development of true leaves and establishment of viable plants) unstable. As a countermeasure against this problem, rice seeds have traditionally been coated with a powder containing calcium peroxide as an active ingredient to supply oxygen in the soil. [Problems to be Solved by the Invention] However, conventional seed dressings mainly containing calcium peroxide do not necessarily supply a sufficient amount of oxygen to obtain good germination and seedling establishment. Particularly under low temperature conditions, germination and seedling establishment are often poor even when the above-mentioned seed coating agents are used. For this reason, with conventional techniques, it is difficult to popularize direct sowing cultivation in cold regions such as Tohoku and Hokkaido, and the sowing period is currently limited even in warm regions. On the other hand, in fields prone to strong reducing conditions such as wet rice fields, germination and seedling establishment are even more unstable, and the spread of direct sowing cultivation is limited due to soil conditions. In order to disseminate direct seeding, which is a promising low-cost rice cultivation technology, to a wide area, it is most important to improve the instability of germination and seedling establishment under unfavorable conditions in conventional techniques. In order to solve the above-mentioned problems, the present invention aims to provide a seed dressing that has a significantly higher oxygen supply ability than conventional seed dressings and improves the temperature environment around the seeds through the heat of reaction in the water-containing soil. That is. The purpose of the present invention is to provide a method that is particularly effective under adverse environmental conditions such as low temperatures and strong reduction conditions, and which enables the spread of direct sowing cultivation even in areas under such conditions. [Means for Solving the Problems] As a means for achieving the above-mentioned objects, the present invention has developed a seed coating agent characterized in that an iron compound is blended with calcium peroxide. The iron compound used in the present invention is one selected from the group of iron oxide, iron sulfate, iron phosphate, and organic acid iron, or a mixture of two or more of these iron compounds. These iron compounds may be either ferrous salts or ferric salts, and may be insoluble in water. Specifically, the iron oxide mentioned above includes hydrated iron oxide, which is precipitated by adding an alkaline agent to an aqueous solution of naturally occurring loess, limonite, and iron salts, but hydrated iron oxide is produced by drying and firing at high temperatures. More preferred.
In addition, the above-mentioned iron sulfate includes ferrous sulfate and ferric sulfate.
Examples include iron or basic ferric sulfate, and ferrous salts are preferred, and those containing less water of crystallization are preferred in view of the storage stability of the dressing. In addition to the above-mentioned iron oxide and iron sulfate, compounds of phosphoric acid and iron such as ferric phosphate and ferric pyrophosphate, and organic acids and iron such as ferric citrate and iron fumarate are also used. (hereinafter referred to as "organic acid iron") can be used. Furthermore, any two or more of these may be mixed and blended. The blending ratio of this iron compound is 5 to 100 parts by weight as Fe in the iron compound per 100 parts by weight of calcium peroxide. This is because if the blending ratio of the iron compound is less than 5 parts by weight, there is almost no effect on promoting germination, and if it is more than 100 parts by weight, the effect is lower than that, and it is difficult to uniformly coat the seeds with the entire amount. Calcium peroxide referred to here refers to CaO ₂ 100
Calculated on the basis of pure content. Calcium peroxide CaO ₂ is a relatively stable peroxide, hardly soluble in water, and gradually decomposes in water and soil, generates oxygen, and becomes slaked lime. CaO ₂ +H ₂ O→Ca(OH) ₂ + 1/2O ₂ The decomposition rate in soil is slow, and when mixed with soil, it decomposes approximately 30% in one month with soil alone, and approximately 70% with water. Although there is decomposition, it is about 20 to 40% during 1 to 2 weeks, which is considered to be the budding period. It is usually sold as a dry powder containing 7 to 11% effective oxygen, and powders containing calcium sulfate and the like are also commercially available for use in dressing directly sown rice seeds. In the present invention, these commercially available products can be used as the calcium peroxide agent. The seed dressing of the present invention accelerates the decomposition of calcium peroxide, significantly increases the amount of oxygen generated than conventional seed dressings, and releases heat associated with the reaction, improving the temperature environment around the seeds. It is characterized by the fact that it does so (see experimental examples). These points promote germination and subsequent growth under low temperature conditions and significantly improve seedling establishment rate. In addition, an increase in the amount of oxygen generated affects not only the seeds but also the surrounding soil, improving the oxidative state around the seeds in highly reduced soils and improving seed germination and seedling establishment. Furthermore, in order to stably maintain the above-mentioned effects, in the present invention, water-soluble iron compounds, such as iron sulfate, are treated by coating the surface of the powder with a high-molecular organic polymer that is sparingly soluble in water. A method of suppressing dissolution in water and sustaining oxygen release (slow release), a method of adding a reducing organic compound to iron sulfate powder, or a method of using both of these methods were used. A specific example of such a high-molecular organic polymer is paraffin, but it is not limited thereto, and other high-molecular organic polymers that are poorly soluble in water and have a film-forming function may be used. When coating with paraffin, the amount of solid paraffin film is such that it can moderately prevent contact between the substance of the present invention and water, that is, iron compound 100%
It is preferably 3 to 15 parts by weight. When iron compounds coated with these high-molecular organic polymers are used, wasteful release of oxygen during dressing can be suppressed, but the effect decreases little during the storage period after dressing, and sustained release is not practical. more effective. Sustaining the oxygen release rate (sustained release) of the powder coating of the present invention
Effects can also be obtained by adding reducing organic compounds, such as ascorbic acid, to the iron compound (see experimental examples). In this case, the amount of ascorbic acid added is preferably 2 to 10 parts by weight per 100 parts by weight of the iron compound. The lower limit is 2 parts by weight if the amount added is 2 parts by weight.
This is because if it is less than 10 parts by weight, there will be no sustained effect, and if it is more than 10 parts by weight, the suppressing effect will be too strong and oxygen release will stop in a short time. A spreading agent may be added to the substance of the present invention if necessary. Depending on the type of iron compound in the material of the present invention, a strong coating layer may be formed without the addition of a spreading agent, but in the case of other iron compounds, a hydraulic material such as calcined gypsum may be added. It is preferable to leave it there. The effects of the present invention can also be obtained by using magnesium peroxide instead of calcium peroxide.
It is expected that something similar to that obtained with calcium peroxide can be obtained. Next, the present invention will be explained in more detail with reference to the following experimental examples and examples. Experimental Example 1 Calcium peroxide as a reagent, mixed with the materials shown in Table 1, mixed with sand, placed in a container, further layered with sand on top of the mixture, and sealed the container. 200ml of water was added and the amount of gas generated was measured. 10 minutes after adding water and
The amount of gas generated after 60 minutes was as shown in Table 1. In the table, "ferrous sulfate" refers to one containing one molecule of crystal water.

[Table] Experimental Example 2 Regarding the amount of oxygen generated after seed dressing, commercially available seed dressings (containing 35% calcium peroxide, 65% calcium carbonate, calcium sulfate, etc.),
The same applies hereafter) and sustained-release iron sulfate (ferrous sulfate [with one molecule of water of crystallization] coated with paraffin at a weight ratio of 5%, and further added with L-ascorbic acid at a weight ratio of 5%) , hereinafter the same)), the following experiment was conducted for the purpose of seeing how different the seed coating agent of the present invention is based on temperature conditions. 2,000 glass beads with a diameter of approximately 3 mm are coated with a seed dressing containing the proportions shown in Table 2.
120 tablets were placed in a special sealed container. This was carried into a constant temperature water tank set at each temperature condition (15°C, 20°C, 25°C), and the amount of oxygen generated was calculated from the change in gas volume inside the container. The results are shown in Figure 1. Under all temperature conditions, the seed dressing containing slow-release iron sulfate produced more oxygen than commercially available seed dressings, and the generation took longer. It was found to last for a long time.

[Table] Experimental Example 3 The following experiment was conducted for the purpose of measuring the reaction heat generated after dressing the seed dressing of the present invention. A commercially available seed dressing (dry paddy equivalent) and a seed dressing of the present invention containing iron sulfate, etc. in the ratio shown in Table 3 to calcium peroxide in the commercially available seed dressing are powdered. Each 100 coated paddy grains were placed in 20 ml of pure water and sealed, and the amount of heat generated under constant temperature conditions of 25°C was compared with pure water using a microbial calorimeter (TMC-8307 manufactured by Nippon Medical Instruments Manufacturing Co., Ltd.). ) for 100 hours. The results are shown in Figure 2. All seed dressings containing iron sulfate, etc. generate more heat than commercially available seed dressings, especially seed dressings containing slow-release iron sulfate. It was observed that the fever persisted for a long time. Example 1 A commercially available seed dressing (dry paddy equivalent) and a seed dressing containing various iron compounds in the proportions shown in Table 4 relative to the calcium peroxide in the commercially available seed dressing.

[Table] Coat the seedlings with powder, fill with paddy soil, and sow at a depth of 1 in a flooded deep-bottomed shear (diameter 9.5 cm, height 10 cm).
Seed in cm. After covering soil, each constant temperature (20
The seeds were placed in an indoor thermostat with artificial lighting set at 16°C and cultivated for 3 to 4 weeks. Table 4 shows the effects of seed dressings containing various iron compounds on germination and seedling establishment. 1 iron, ferric phosphate, ferric citrate
It was iron, iron fumarate. The effects of promoting sprouting and seedling establishment by blending various iron compounds tended to become more pronounced under the low temperature conditions of 16°C, and the effects of ferrous sulfate and ferric phosphate were particularly large. In addition, "emergence rate" in the table is the percentage of germinated individuals on the 6th day after sowing for 20℃, and on the 12th day for 16℃, and "seedling establishment rate" is the percentage of germination after sowing for 20℃. Regarding the third week and 16°C, it is the percentage of individuals whose second leaves have developed in the fourth week.

【table】

[Table] Example 2 Commercially available seed dressings (dry paddy equivalent) and calcium peroxide in commercially available seed dressings were mixed with iron oxide and ferrous sulfate ( Crystal water is 1
A seed coating agent containing ferric phosphate (with crystal water of 5.5 molecules) and ferric phosphate (with 5.5 molecules of water of crystallization) was coated on germinated rice, and the method was applied in accordance with Example 1 (however, the test temperature was 16°C). Cultivated for a week. The results are shown in Table 5. When used as a single agent, ferric phosphate had the highest germination promoting effect, followed by ferrous sulfate and iron oxide. When mixing two drugs,
In the case of the combination of ferrous sulfate and ferric phosphate, the same degree of effect as in the case of ferric phosphate alone was observed, and in the case of the combination of iron oxide and ferrous sulfate, and the combination of iron oxide and ferric phosphate. showed intermediate efficacy compared to each single agent.

[Table] Example 3 Ferrous sulfate (crystal water A seed coating agent containing 1 molecule of 1 molecule) was coated on sprouting rice grains, and the effects on germination and seedling establishment were compared using a method similar to Example 1 (however, the test temperature was 20°C). The result is the 6th
As shown in the table, the effect of promoting germination by adding ferrous sulfate was observed at all mixing ratios;
If Fe in ferrous sulfate is mixed at a ratio of 100 parts by weight or more to parts by weight, it is difficult to uniformly coat the seeds with the entire amount, and the effectiveness is lower than when it is less than 100 parts by weight. There was a tendency to Example 4 The following experiment was conducted to examine the effect of the seed dressing of the present invention on germination and seedling establishment under reduced soil conditions. Fill 2.5 kg of paddy soil mixed with 6 g or 12 g of wheat straw powder into a 1/5000-a pot.

[Table] The samples were left for 13 days after flooding and puddling to achieve strong reducing conditions. A commercially available seed dressing (dry paddy equivalent) and a seed dressing containing sustained release iron sulfate in the ratio shown in Table 7 to the calcium peroxide in the commercially available seed dressing were used for germination. The paddy was coated with flour, and 20 grains were sown in each pot at a seeding depth of 2 cm. After that, about 2
The plants were submerged in water to a depth of 1.5 cm and cultivated in a screened room with light shielding. The average temperature during the test period was approximately 23°C. The results are shown in Table 7, whereas commercially available seed dressings had low germination and seedling establishment rates.
In the case of a seed dressing containing slow-release iron sulfate, germination was promoted and a relatively high number of seedlings was obtained even under such poor conditions. In the table, "emergence rate" is the percentage of individuals with visible eyes on the 15th day after sowing, and "seedling establishment rate" is the percentage of individuals with developed second leaves on the same day. Example 5 The purpose of verifying the effect of the seed dressing of the present invention on germination and seedling establishment under low temperature conditions in the field

[Table] A demonstration test was conducted at the Agricultural Research Center's Taniwahara paddy field. Starting from early April under low temperature conditions, at least one month earlier than the conventional suitable sowing time, seed dressings containing conventional commercially available seed dressings (equivalent to dry paddy) and slow-release iron sulfate are applied every 10 days. (Slow-release iron sulfate was mixed at a ratio of 40 parts by weight to 100 parts by weight of a commercially available seed dressing for the equivalent amount of dry rice), and the germinated paddy was sown. Regarding the sowing method, 15cm
Dot sowing was carried out at a density of 15 cm x 15 cm and 4 seeds per plant at a seeding depth of 1 cm or 2 cm. The results are shown in Table 8. Except for the 2cm sowing depth section on May 22nd, the seedling establishment rate was significantly improved by the seed dressing containing sustained-release iron compound regardless of the sowing period, sowing depth, and variety. Improvement was observed. In addition, "seedling establishment rate" in the table is for April 10th, 21st, and 5th.
This is the percentage of individuals that developed the third leaf after 4 weeks for sowing on May 1st, and after 3 weeks for sowing on May 12th and 22nd.

[Table] Example 6 With commercially available seed dressings, it is said that it is desirable to dry the seeds in the shade after dressing and sow the seeds on the same day or the next day after dressing. However, when directly seeding cultivation is actually carried out in agriculture, it is thought that in many cases the seeds are stored for several days after dressing due to weather and other operational circumstances. Therefore, it is necessary to prevent deterioration of the sprouting promoting effect during this storage period. This point is especially important for substances that promote oxygen generation, such as this drug. Therefore, 100 parts by weight of a commercially available seed dressing was coated with ferrous sulfate and paraffin at a weight ratio of 5% to the ferrous sulfate, or L- Seed coating agent containing ascorbic acid added at a ratio of 12 parts by weight of Fe (test numbers 1, 2, and 3 in order)
2 days and 7 days after coating,
After being stored in a sealed incubator at 20°C for 1 day, a method similar to Example 1 was used (however, the temperature condition was 20°C).
Cultivated for 10 days. The results are shown in Figure 3. Paraffin coating,
Alternatively, in the case of a seed dressing containing ferrous sulfate that has been treated with L-ascorbic acid to provide sustained release properties, there is almost no decrease in the effect even after 7 days of storage, and the germination promoting effect is shown. was confirmed to be maintained.

[Brief explanation of the drawing]

Figure 1 is a graph showing a comparison of the amount of oxygen generated by each seed dressing under different temperature conditions, and Figure 2 is
Figure 3 is a graph showing a comparison of the heat release amount of each seed dressing after dressing the seeds, and Figure 3 is a graph showing changes in the germination promoting effect of each seed dressing depending on the length of the storage period after dressing the seeds. be.

Claims (1)

[Claims] 1. Direct-seeded rice comprising calcium peroxide, 5 to 100 parts by weight of an iron compound as Fe per 100 parts by weight of calcium peroxide, and a spreading agent if necessary. A powder coating agent that improves seed germination and growth. 2. The powder for improving sprouting and growth of directly sown rice seeds according to claim 1, wherein the iron compound is one or a mixture of two or more selected from the group of iron oxide, iron sulfate, iron phosphate, and organic acid iron. Clothing. 3 Calcium peroxide is mixed with 5 to 100 parts by weight of iron compound as Fe per 100 parts by weight of calcium peroxide, and if necessary, a spreading agent, and the iron compound is resistant to water. Direct seeding that is coated with a soluble high-molecular organic polymer and optionally has a reducing organic compound added to it, or is coated with a low-molecular-weight organic polymer that is poorly soluble in water and has a reducing organic compound added thereto. A powder coating agent that improves the germination and growth of rice seeds. 4. The powder coating agent for improving sprouting and growth of directly sown rice seeds according to claim 3, wherein the high-molecular organic polymer is a solid paraffin film in an amount of 3 to 15 parts by weight per 100 parts by weight of the iron compound. 5. The dressing for improving sprouting and growth of directly sown rice seeds according to claim 3, wherein the reducing organic compound is ascorbic acid in an amount of 2 to 10 parts by weight per 100 parts by weight of the iron compound.