Seed coating for increasing calcium content in peanuts and application of seed coating

Abstract

The invention relates to a seed coating for increasing calcium content in peanuts and application thereof, the coating comprises a calcium fertilizer, a film forming substance, a synergist and a dispersant, the raw materials comprise, by mass, 1-3 parts of the calcium fertilizer, 0.1-0.3 part of the synergist, 0.03-0.06 part of the dispersant, and 2-4 parts of the film forming substance. By coating the peanut seeds, the content of endogenous calcium in the peanuts is enhanced, and the requirement of the peanuts for calcium in the early growth stage is reduced, so that cadmium entering peanut bodies through root calcium ion channels is reduced, and the content of cadmium in harvested peanut seeds is reduced. Field trials prove that the cadmium content in the harvested peanuts can be reduced by about 39% when the coated seeds are sown in the acid cadmium-polluted soil; the method is easy and convenient to operate and low in cost, overcomes the defects of the traditional complex cadmium reduction technology of applying a passivating agent to the soil and the like in the field, is not prone to causing the soil environment risk, has the good peanut cadmium reduction rate and is suitable for large-area application and popularization.

Description

Technical Field

[0001] The invention belongs to the technical field of peanut planting and heavy metal contaminated soil remediation, and in particular relates to a seed coating for increasing the calcium content in peanuts and an application thereof. Background Art

[0002] Peanuts are an important oil and cash crop in my country, and an important source of edible vegetable oil and protein for Chinese residents. my country is a major producer and consumer of peanuts in the world. With the increasing demand for direct consumption and food processing of peanuts, the international community is paying more and more attention to the problem of excessive heavy metals in peanuts. In recent years, food safety issues such as excessive heavy metal content in peanuts, especially cadmium content, have become one of the main constraints on my country's peanut export trade. Investigations have found that peanuts have a strong ability to accumulate cadmium in the soil.

[0003] At present, the research on heavy metal pollution control technology at home and abroad is mainly focused on crops such as rice and wheat. There are relatively few studies on the control measures for cadmium migration and transport in the soil-peanut system. They are mainly based on rice, wheat and other crops, focusing on low accumulation variety screening, lime application, biochar passivation and activation, etc. Low cadmium accumulation varieties are often difficult to take into account both yield and quality at the same time, and actual large-scale promotion and application are rare; many passivators have been developed, including lime, organic fertilizer, biochar, sepiolite, hydroxyapatite, etc., which can reduce the absorption of cadmium by crops to a certain extent by increasing soil pH, changing the form of cadmium, and reducing the effective cadmium content in the soil, but most of them are expensive, and long-term application is likely to have an adverse effect on the physical and chemical properties of the soil. For example, long-term application of lime is likely to cause soil compaction, resulting in reduced fertility and affecting crop yields. It is urgent to develop targeted control technologies based on the physiological characteristics of peanuts.

[0004] Calcium (Ca) is a secondary element necessary for plant growth and development. It has important physiological functions. It is not only a structural material of cells, but also a second messenger in cells. It plays an important role in the plant's resistance to adversity. Ca can not only reduce the absorption of cadmium by plants by competing with Cd for ion channels, but also reduce the transport of cadmium between cells by forming pectin calcium complexes with pectin in cell walls and participating in regulating the activity of enzymes related to cell wall metabolism, and increase the retention of cadmium in plant roots, thereby reducing the cadmium content in edible parts such as rice, wheat, and sorghum. Peanut is a calcium-loving crop with a large demand for calcium. Calcium is the third essential element after nitrogen and potassium. When peanuts are calcium deficient, seed development is hindered, the shell tissue is loose, and the number of empty, blighted, and rotten fruits increases, and the yield and quality are significantly reduced. In peanut production, fertilization is mostly done once before sowing, especially calcium fertilizer. At present, the types of calcium fertilizers commonly used for peanuts in the field include lime, gypsum, superphosphate, calcium magnesium phosphate, etc. Lime is often used to supplement calcium sources on acidic soils.

[0005] Coating is an important drug treatment method to greatly improve seed quality before planting. It uses seeds as carriers and seed coating agents as raw materials. Pesticides, fertilizers, growth regulators and other active ingredients and various adjuvants are evenly mixed and adhered to the seeds to form a drug film. After sowing, the active ingredients of the seed coating agent are absorbed by the plant to various parts, ultimately achieving the purpose of preventing and controlling pests and diseases, protecting seedlings, promoting growth and increasing yields. At present, most peanut seed coating agents in my country are composed of insecticides and fungicides, and are mainly used to prevent and control pests and diseases. There is no application of seed coating to reduce the cadmium content in peanuts. Summary of the invention

[0006] Technical problem to be solved: In view of the shortcomings of the above background technology, the present invention provides a seed coating for increasing the calcium content in peanuts and its application. The method of the present invention is easy to operate and low in cost, overcomes the drawbacks of cumbersome cadmium reduction technology in the field, and has good peanut cadmium reduction efficiency, and is suitable for large-scale promotion and application.

[0007] Technical solution: A coating for increasing the calcium content in peanut seeds, the coating comprising calcium fertilizer, film-forming substance, synergist and dispersant. The raw materials are calculated by weight: the content of calcium fertilizer is 1-3 parts, the content of synergist is 0.1-0.3 parts, the content of dispersant is 0.03-0.06 parts, and the content of film-forming substance is 2-4 parts.

[0008] Preferably, the content of the calcium fertilizer is 3 parts, the content of the synergist is 0.2 parts, the content of the dispersant is 0.05 parts, and the content of the film-forming substance is 3 parts.

[0009] Preferably, the calcium fertilizer is calcium nitrate, EDTA chelated calcium or sugar alcohol chelated calcium.

[0010] Preferably, the film-forming substance is methyl cellulose, carboxymethyl cellulose, sodium alginate, gum arabic, polyvinyl alcohol or polyvinyl pyrrolidone.

[0011] Preferably, the above-mentioned synergist is a water-soluble azone or thiazone.

[0012] Preferably, the dispersant is sodium dodecyl sulfate, sodium dodecylbenzene sulfonate or Tween 80.

[0013] The application of the above coating in increasing the calcium content of peanut seeds.

[0014] The specific application scheme is to prepare a seed coating agent containing calcium fertilizer, place the peanut seeds in the coating agent and shake them continuously until the seeds are evenly coated.

[0015] The preparation method of the above coating agent is: place the calcium fertilizer in water and stir until it is completely dissolved, then add the synergist and dispersant while constantly stirring, add the film-forming substance after it is completely dissolved and stir continuously, and let it stand for 15-25 minutes after stirring evenly to obtain the desired coating agent.

[0016] The coating is used to reduce the cadmium content of peanuts by increasing the calcium content of peanut seeds.

[0017] In the prior art, cadmium reduction in peanuts relies on the application of alkaline calcium fertilizers, which can provide exogenous calcium. The principle of cadmium reduction is mainly to increase soil pH, reduce the effectiveness of cadmium in the soil, and then reduce the absorption of cadmium by the root system, that is, to play a role by regulating the soil environment. The present invention mainly coats peanut seeds to strengthen the endogenous calcium content of peanuts, reduce the calcium demand of peanuts in the early growth period, thereby reducing the entry of cadmium into the peanut body through the root calcium ion channel, and reducing the cadmium content of peanut kernels after harvest, that is, through plant physiological pathways, without affecting the soil environment.

[0018] Beneficial effects: The method proposed by the present invention uses calcium fertilizer seed coating to reduce the cadmium content of peanuts in cadmium-contaminated soil. By using coating technology to wrap calcium fertilizer on the surface of peanut seeds, it will not affect the normal germination of seeds and the later growth of peanuts, and can strengthen the accumulation of calcium in seedlings; the method described in the present invention is the same as the peanut disease and pest resistance seed coating process commonly used in field production. On the basis of not affecting the normal growth of peanuts, it will not increase labor and production costs, nor will it cause harm to the soil and the environment. In addition, a synergist that promotes the penetration of calcium fertilizer into the seeds and a dispersant that improves the dispersion of components and coating uniformity are added, which can effectively improve the utilization rate of calcium fertilizer, and each component can obviously produce a synergistic effect, thereby reducing the accumulation of cadmium in peanut kernels. Field experiments have confirmed that the coated seeds sown on acidic cadmium-contaminated soil can reduce the cadmium content in the harvested peanuts by about 39%; the method is simple to operate and low in cost, overcomes the disadvantages of traditional soil application of passivators and other cumbersome cadmium reduction technologies in the field, and is not easy to cause soil environmental risks. At the same time, it has a good peanut cadmium reduction rate and is suitable for large-scale promotion and application. DETAILED DESCRIPTION

[0019] The invention provides a method for reducing the cadmium content in peanuts by using a calcium fertilizer seed coating agent and application thereof. The method comprises the following steps: 1) preparing a calcium fertilizer seed coating agent; 2) placing peanut seeds in the calcium fertilizer coating agent for coating; and 3) sowing the coated peanut seeds in cadmium-contaminated soil and cultivating them until maturity.

[0020] The present invention uses seed coating technology to coat calcium fertilizer on the surface of peanut seeds. The present invention has no special requirements on the variety and other parameters of the peanut seeds, and the seeds of conventional peanut varieties in the field can be used. When the seeds are coated in the present invention, conventional coating machines or manual coating can be used according to actual conditions.

[0021] The type of calcium fertilizer in the calcium fertilizer-containing seed coating agent described in the present invention is not specifically limited, as long as it can provide calcium and does not affect the normal germination of peanut seeds. In the specific implementation of the present invention, the calcium fertilizer is preferably calcium nitrate tetrahydrate.

[0022] During the preparation of the coating agent described in the present invention, a synergist and a dispersant are added, wherein the synergist is used to promote the calcium fertilizer to penetrate the seed coat into the interior of the seed and improve the utilization rate of the calcium fertilizer; the dispersant is used to improve the dispersibility of each component in water and make the outer coating of the seed evenly attached and not easy to fall off.

[0023] The seed coating method of the present invention will not affect the germination and normal growth of peanut seeds, and calcium can maintain the integrity of cell structure and function, and promote the growth and flowering of peanuts. The principle of reducing cadmium in the method of the present invention is as follows: calcium-containing fertilizer seed coating agents are used to increase the calcium content in coated seeds, which strengthens the calcium content in the peanut root system after seed germination. Calcium in plant cells mainly exists in the cell wall, and can form a pectin calcium complex with pectin in the cell wall. Since pectin contains a large number of negatively charged carboxyl groups, it can be electrostatically combined with cadmium, blocking cadmium in the cell wall, reducing the transport of cadmium from the plant body to the peanut kernel, and thus reducing the accumulation of cadmium in the peanut kernel; at the same time, since cadmium can enter the root system through calcium ion channels, calcium fertilizer seed coating increases the calcium content in peanut seeds, that is, strengthens "endogenous" calcium, reduces the demand for calcium in the early stage of peanut growth, and thus reduces the entry of cadmium into the peanut body through the root calcium ion channel. The principle of applying alkaline calcium fertilizer or calcium-containing conditioner on acidic soil to reduce the cadmium content in peanuts by providing "exogenous" calcium is mainly to increase soil pH, reduce the effectiveness of cadmium in the soil and thus reduce the absorption of cadmium by the roots. Therefore, the cadmium reduction principle of the method described in the present invention is obviously different from that.

[0024] After obtaining the coated seeds, the present invention sows the peanut seeds in cadmium-contaminated soil and cultivates them until they are mature. The present invention has no special requirements for the sowing and cultivation methods, and conventional peanut sowing and cultivation management methods in the art can be used.

[0025] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0026] Embodiment 1:

[0027] Seed coating experiments were conducted in the laboratory using the peanut variety Wanhua No. 4.

[0028] The seed coating agent uses water as solvent and includes the following components by mass: 3 parts of methylcellulose, 0.2 parts of rhodamine, 1 part, 2 parts, 3 parts, 4 parts and 5 parts of calcium nitrate tetrahydrate (respectively expressed as Ca1, Ca2, Ca3, Ca4, Ca5), 0.2 parts of water-soluble azone, and 0.05 parts of sodium dodecyl sulfate.

[0029] Test example: Prepare 30g of seed coating agent. In the first step, add 0.3g, 0.6g, 0.9g, 1.2g, and 1.5g of calcium nitrate tetrahydrate into a beaker, then add 28mL of water and stir thoroughly to completely dissolve the calcium nitrate tetrahydrate; in the second step, add 0.06g of rhodamine, 0.06mL of water-soluble azone, and 0.015g of sodium dodecyl sulfate and shake well; in the third step, add 0.9g of methylcellulose and shake well, let it stand for 15 minutes until the coating agent becomes viscous before coating the seeds. Put the seeds into the coating agent at a ratio of coating agent weight: seed mass = 1:30, stir continuously until the surface of the peanut seeds is evenly coated, and after drying, obtain peanut seeds coated with calcium fertilizer. The obtained peanut seeds were tested for calcium content, and placed in a culture dish covered with absorbent cotton for 7 days to determine their germination rate and root length.

[0030] The comparative example is peanut seeds coated with a seed coating agent without adding calcium nitrate tetrahydrate and with other components unchanged. The calcium content, germination rate and root length of the obtained peanut seeds are measured simultaneously.

[0031] Table 1 Calcium content, germination rate and root length of coated seeds

[0032] Calcium content (mg / kg) Germination rate (%) Root length (cm) Comparative Example 709.4±12.3f 98.9±1.9a 1.50±0.02b Test Example-Ca1 1060±20.4e 100±0.0a 1.68±0.01a Test Example-Ca2 1414±23.7d 98.9±1.9a 1.90±0.02a Test Example-Ca3 1752±35.2c 98.9±1.9a 1.82±0.06a Test Example-Ca4 2019±43.8b 85.7±2.0b 0.48±0.09c Test Example-Ca5 2352±64.5a 50.2±3.4c 0.35±0.02c

[0033] The data in Table 1 show that the calcium content of peanut seeds coated with calcium fertilizer coating agents Ca2 and Ca3 is approximately 2.0 times and 2.5 times that of the control group, and does not affect seed germination, and has the best effect on promoting root growth.

[0034] Embodiment 2:

[0035] A field verification test was conducted in acidic cadmium-contaminated soil in Ganzhou, Jiangxi Province with a pH value of 5.84 and a total cadmium content of 0.55 mg / kg. The peanut variety was Wanhua No. 4.

[0036] The specific ingredients of the seed coating agent are the same as those of Ca3 in Example 1.

[0037] Test example: Prepare 300g of seed coating agent. The first step is to add 9g of calcium nitrate tetrahydrate into a beaker, then add 280mL of water and stir thoroughly to completely dissolve the calcium nitrate tetrahydrate; the second step is to add 0.6g of rhodamine, 0.6mL of water-soluble azone, and 0.15g of sodium dodecyl sulfate and shake well; the third step is to add 9g of methyl cellulose and shake well, let it stand for 15 minutes until the coating agent becomes viscous to obtain the desired peanut seed coating agent. Manually coat the selected plump peanut seeds for about 15-30 seconds until the seeds are evenly coated, and dry them in the sun to obtain peanut seeds coated with calcium fertilizer. Sow the coated seeds according to the conventional peanut sowing method.

[0038] Comparative Example 1 is peanut seeds coated with a seed coating agent without adding calcium nitrate tetrahydrate and keeping other components unchanged, and sowing is carried out according to a conventional peanut sowing method.

[0039] Comparative Example 2 is peanut seeds coated with a seed coating agent without adding water-soluble azone and sodium dodecyl sulfate, and other ingredients remain unchanged, and sowing is carried out according to a conventional peanut sowing method.

[0040] The conventional peanut cultivation and management methods in the field were followed until maturity. After maturity, plant samples were collected, and the yield and cadmium and calcium contents in roots, stems, leaves, shells and kernels were determined. Soil samples were collected to determine pH and effective (EDTA extracted) cadmium content. The results are shown in Tables 2 and 3.

[0041] Table 2 Peanut yield and cadmium and calcium content in each part

[0042]

[0043] Table 3 Soil pH and available cadmium content

[0044] pH Effective cadmium content (mg / kg) Comparative Example 1 5.79±0.12a 0.32±0.01a Comparative Example 2 5.69±0.15a 0.30±0.02a Test example 5.73±0.10a 0.31±0.01a

[0045] From the test results, it can be seen that in the soil with excessive cadmium in Ganzhou, Jiangxi, the peanut yield after the calcium fertilizer seed coating treatment in the test example was slightly higher than that in the comparative examples 1 and 2, the cadmium content in the peanut root system was significantly reduced by 44.9% and 16.3% compared with the comparative examples 1 and 2, the cadmium content in the peanut kernel was significantly reduced by 38.7% and 18.4% compared with the comparative examples 1 and 2, and the calcium content in the peanut root system was significantly increased by 30.9% and 19.8% compared with the comparative examples 1 and 2, and the calcium content in other parts of the peanut was not significantly changed compared with the comparative examples 1 and 2. The soil pH and available cadmium content of the test example did not change significantly compared with the comparative example.

[0046] The results of Examples 1-2 show that the calcium content of peanut seeds is significantly increased after the seeds are coated with calcium-containing fertilizer, and the cadmium content in the peanut kernels harvested after sowing is significantly reduced. The components of the coating agent can produce a significant synergistic effect.

[0047] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A coating for increasing calcium content in peanut seeds, characterized in that: The coating comprises calcium fertilizer, film-forming substance, synergist and dispersant. The raw materials are calculated by weight: the content of calcium fertilizer is 1-3 parts, the content of synergist is 0.1-0.3 parts, the content of dispersant is 0.03-0.06 parts, and the content of film-forming substance is 2-4 parts.

2. The coating according to claim 1, characterized in that The content of the calcium fertilizer is 3 parts, the content of the synergist is 0.2 parts, the content of the dispersant is 0.05 parts, and the content of the film-forming substance is 3 parts.

3. The coating according to claim 1, characterized in that The calcium fertilizer is calcium nitrate, EDTA chelated calcium or sugar alcohol chelated calcium.

4. The coating according to claim 1, characterized in that The film-forming substance is methyl cellulose, carboxymethyl cellulose, sodium alginate, gum arabic, polyvinyl alcohol or polyvinyl pyrrolidone.

5. The coating according to claim 1, characterized in that The synergist is a water-soluble azone or thiazone.

6. The coating according to claim 1, characterized in that The dispersant is sodium dodecyl sulfate, sodium dodecylbenzene sulfonate or Tween 80.

7. Use of the coating according to any one of claims 1 to 6 in increasing the calcium content of peanut seeds.

8. The use according to claim 5, characterized in that: Prepare a seed coating agent containing calcium fertilizer, place the peanut seeds in the coating agent and shake them continuously until the seeds are evenly coated.

9. The use according to claim 8, characterized in that: The preparation method of the coating agent is as follows: placing the calcium fertilizer in water and stirring until it is completely dissolved, then adding the synergist and the dispersant while continuously stirring, adding the film-forming substance after it is completely dissolved and continuously stirring, and standing for 15-25 minutes after stirring evenly to obtain the desired coating agent.

10. Use of the coating according to any one of claims 1 to 6 in reducing the cadmium content of peanuts by increasing the calcium content of peanut seeds.

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