Cultivation method of selenium-rich rice crops

Abstract

The invention discloses a cultivation method of selenium-rich rice crops in the technical field of selenium-rich rice cultivation, provides the cultivation method of the selenium-rich rice crops, aims to solve the problem of poor effect of simply applying selenium fertilizer, and provides a mode of preparing slow-release selenium-rich fertilizer, so that effective improvement of soil is realized, and the yield of the selenium-rich rice crops is improved. Meanwhile, the pesticide is packaged by an organic metal framework and combined into the fertilizer, so that the fertilizer has a long-term disease-resistant effect while providing nutrients, the application frequency of the selenium fertilizer and the pesticide is reduced, the planting method is simplified, the planting difficulty is reduced, and the technical effect of reducing the production cost of the selenium-enriched rice is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of selenium-enriched rice cultivation, and specifically refers to a cultivation method of selenium-enriched rice crops. Background Art

[0002] Selenium is an essential trace element for the human body. It has many physiological functions such as anti-oxidation, enhancing immunity, and preventing cancer. However, the selenium content in the soil in most areas is low, resulting in a general lack of selenium in agricultural products, which is difficult to meet the daily needs of the human body. Selenium-rich rice refers to rice that converts inorganic selenium into organic selenium during its growth and accumulates it in large quantities in rice grains. The development of the selenium-rich rice industry is of great significance to improving the dietary structure of residents and improving people's health. The research on selenium-rich rice began in the 1980s and is currently focused on the following aspects: 1. The absorption, transportation and accumulation mechanism of selenium in rice: studying the absorption of selenium by rice roots, the transportation and distribution of selenium in the body, and the key genes and metabolic pathways that affect selenium accumulation; 2. Breeding of selenium-rich rice varieties: breeding selenium-rich rice varieties with excellent traits through traditional breeding and molecular breeding techniques; 3. Selenium-rich rice cultivation technology: studying the effects of different cultivation measures on the selenium content of rice, and establishing a high-yield and efficient selenium-rich rice cultivation technology system.

[0003] The cultivation method of selenium-enriched rice is basically the same as that of ordinary rice, but some special cultivation measures need to be taken according to the characteristics of selenium to improve the absorption and accumulation efficiency of rice. Current research focuses on the following aspects:

[0004] 1. Soil improvement: Apply more selenium fertilizer. Before sowing or during the growth period of rice, apply an appropriate amount of selenium fertilizer to the soil or spray it on the leaves to increase the absorption of rice;

[0005] 2. Water and fertilizer management: Reasonable irrigation, scientific fertilization, and reasonable combination of nutrients such as nitrogen, phosphorus, and potassium can improve the absorption and utilization efficiency of selenium by rice;

[0006] 3. Pest and disease control: timely prevent and control pests and diseases to reduce the impact on rice growth, improve rice's ability to absorb and accumulate selenium, use biological pesticides, reduce the use of chemical pesticides, and avoid pollution to the soil and environment.

[0007] The existing technologies currently have the following main problems: simply applying selenium fertilizers is difficult to effectively utilize selenium, the planting method is cumbersome, the planting is difficult, the cost is high and it is easy to destroy the soil balance. Summary of the invention

[0008] In view of the above situation, in order to overcome the defects of the prior art, the present invention provides a method for cultivating selenium-rich rice crops. In order to solve the problem of poor effect of simply increasing the application of selenium fertilizer, the present invention proposes to prepare a slow-release selenium-rich fertilizer to achieve effective improvement of the soil. At the same time, the pesticide is encapsulated in an organic metal framework and combined with the fertilizer, so that it has a long-term anti-disease effect while providing nutrients. At the same time, the number of applications of selenium fertilizers and pesticides is reduced, the planting method is simplified, and the difficulty of planting is reduced, thereby achieving the technical effect of reducing the production cost of selenium-rich rice.

[0009] In order to achieve the above object, the present invention proposes a cultivation method of selenium-enriched rice crops, which specifically comprises the following steps:

[0010] (1) Soil treatment: Before planting, test the soil, apply commercially available organic selenium fertilizer, spread it evenly and till it into the soil to ensure that the soil selenium content is 0.3-0.4 mg / kg;

[0011] Furthermore, in step (2), the commercially available organic selenium fertilizer is commercially available Anmuxi organic selenium fertilizer;

[0012] (2) Seed treatment: Select rice varieties that are suitable for the local climate, have strong disease resistance and high selenium enrichment capacity, soak the seeds in a 0.1% sodium selenite solution for 12 hours, remove them from the water, rinse them with clean water, and dry them for later use;

[0013] Preferably, in step (2), the rice variety is one of Huazhongyou 9326, Yixiangyou 2115, Qunyou 2, and Jingliangyou 5348;

[0014] Furthermore, in step (2), the rice variety is Yixiangyou 2115;

[0015] (3) Seedling raising and transplanting: Seedlings are raised in seedling trays. During the seedling raising period, diluted compound microbial agents are sprayed to promote the healthy growth of seedlings. During transplanting, the seedlings are planted at a spacing of 15 cm × 20 cm. Seven days after transplanting, 8-12 kg of slow-release selenium-rich fertilizer is applied per mu. During the tillering stage, 3-4 kg of slow-release selenium-rich fertilizer is applied again. At the same time, 2-4 mg / L sodium selenite solution is sprayed on the leaves during the heading stage, with a dosage of 20-25 kg per mu, to increase selenium absorption.

[0016] Preferably, in step (3), the composite microbial agent is obtained by mixing lactic acid bacteria, nitrogen-fixing bacteria, and phosphate-solubilizing bacteria in a ratio of 1:2:1;

[0017] Furthermore, in step (3), the lactic acid bacteria have a strain number of CICC20766; the nitrogen-fixing bacteria have a strain number of CICC21686; and the phosphate-solubilizing bacteria have a strain number of CICC22681.

[0018] Preferably, the method for preparing the slow-release selenium-rich fertilizer specifically comprises the following steps:

[0019] S1, adding montmorillonite to a hydrochloric acid solution, stirring in a water bath, filtering and washing with water until the pH value of the residual liquid is 7, and vacuum drying to obtain modified montmorillonite;

[0020] S2, dispersing sodium selenite into the sodium alginate solution, stirring evenly, adding ethylene glycol dimethacrylate, stirring for 2 h, and adding 3-aminopropyltriethoxysilane in an amount of 0.5 mg / mL to obtain a mixed solution;

[0021] S3, adding the modified montmorillonite obtained in S1 and the mixed solution obtained in S2 into ethanol respectively, ultrasonically dispersing for 5 minutes, adding glutaraldehyde, and reacting at 40°C for 6 hours under nitrogen protection to obtain a degradable coating solution;

[0022] S4, adding sodium selenite, dipotassium hydrogen phosphate and urea into water at a mass ratio of 1:4-4.3:5-5.6, mixing, heating and stirring until completely dissolved, and drying to obtain inorganic fertilizer particles;

[0023] S5, dissolving zinc nitrate and 2-methylimidazole in methanol in a molar ratio of 1:4, adding imidacloprid, the mass ratio of pesticide to ZIF-8 is 1:10-15, stirring and reacting at room temperature for 24 hours, collecting the precipitate by centrifugation, washing with methanol 3 times, and vacuum drying to obtain ZIF-8 encapsulated pesticide;

[0024] S6. The inorganic fertilizer particles obtained in S4 are coated with the degradable coating liquid obtained in S3, and the ZIF-8 encapsulated pesticide obtained in S5 is sprayed to form a three-layer slow-release structure with the inorganic fertilizer particles as the core, the coating layer loaded with the selenium source, and the outer layer encapsulating the pesticide, so as to obtain a slow-release selenium-rich fertilizer.

[0025] Preferably, in S1, the volume fraction of the hydrochloric acid solution is 10-15%, the amount of montmorillonite added is 0.03-0.05 g / mL, the water bath temperature is 30-50° C., the stirring rate is 250-400 rpm, and the time is 2-4 h.

[0026] Preferably, in S2, the mass concentration of the sodium alginate solution is 5-7%, the mass ratio of sodium selenite to sodium alginate is 1:25-35; and the mass ratio of ethylene glycol dimethacrylate to sodium selenite is 1:1.8-2.2.

[0027] Preferably, in S3, the mass ratio of modified montmorillonite to the mixed solution is 1:2-2.5.

[0028] Preferably, in S6, the mass ratio of the degradable coating liquid to the inorganic fertilizer particles is 1:10-13, and the spraying amount of the ZIF-8 encapsulated pesticide is 1-3% of the total mass of the fertilizer.

[0029] The beneficial effects achieved by the present invention are as follows: sodium alginate and modified montmorillonite are used as coating materials, sodium selenite is used as a selenium source, and the selenium source is stored in the fertilizer core and the coating layer, thereby realizing multiple slow release of selenium fertilizer. The slow-release coating can effectively control the release rate of selenium fertilizer. Two applications can ensure that rice obtains a stable supply of selenium throughout the entire growth cycle, and a large amount of selenium is converted and enriched in rice grains. Compared with traditional fertilization methods, the utilization rate of selenium fertilizer is improved, the application amount and application frequency of selenium fertilizer are significantly reduced, and the labor intensity and planting cost are reduced. At the same time, imidacloprid is encapsulated by ZIF-8 to realize the slow release of pesticides, and pesticides can be accurately released during the high-incidence period of pests and diseases, such as the entire stage of heading period, to effectively prevent and control rice pests and diseases. Compared with traditional pesticide application methods , reducing the use of pesticides, avoiding environmental pollution caused by excessive use, and meeting the development requirements of green agriculture. The zinc element released during the decomposition of ZIF-8 can synergize with selenium to reduce the adverse effects of heavy metals such as mercury on rice growth, and at the same time reduce the enrichment of heavy metals such as mercury in grains; in the soil treatment stage, the selenium content in the soil was improved. In the seed treatment stage, sodium selenite seed soaking effectively promoted the germination of rice seeds, increased the germination rate, and increased rice yield. In the seedling and transplanting stages, the use of composite microbial agents can promote the reproduction of beneficial microorganisms, enhance nutrient conversion capacity, improve the utilization rate of selenium fertilizer, and enhance rice resistance. The synergistic effect of soil improvement, seed treatment and composite microbial agents can significantly improve rice yield and quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The results of the test of the dissolution rate of fertilizer in water in Examples 1-3 and Comparative Example 1 are shown in FIG.

[0031] Figure 2 The results of the fertilizer soil dissolution rate test of Examples 1-3 and Comparative Example 1 are shown;

[0032] Figure 3 The results of the water dissolution test of imidacloprid in Examples 1-3 and Comparative Example 2 are shown in FIG.

[0033] Figure 4 The results of the imidacloprid soil dissolution rate test of Examples 1-3 and Comparative Example 2 are shown in FIG.

[0034] Figure 5 This is a graph showing the results of the culture experiments of Example 1-3 and Comparative Example 1-2 of the present invention.

[0035] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0037] Unless otherwise defined, all professional and scientific terms used herein have the same meanings as those familiar to those skilled in the art. In addition, any methods and materials similar or equivalent to those described herein may be applied to the present invention. The preferred implementation methods and materials described herein are for demonstration purposes only and are not intended to limit the content of this application.

[0038] The experimental methods in the following examples are conventional methods unless otherwise specified; the experimental materials used in the following examples are purchased from commercial channels unless otherwise specified.

[0039] Example 1

[0040] A method for cultivating selenium-rich rice crops, comprising the following steps:

[0041] (1) Soil treatment: Before planting, test the soil, apply commercially available organic selenium fertilizer, spread it evenly and till it into the soil to ensure that the soil selenium content is 0.3 mg / kg;

[0042] (2) Seed treatment: Use Yixiangyou 2115 and soak the seeds in a 0.1% sodium selenite solution for 12 hours. Take them out and rinse them with clean water, then dry them for later use.

[0043] (3) Seedling raising and transplanting: Seedlings were raised in seedling trays. During the seedling raising period, a diluted composite microbial agent consisting of lactic acid bacteria, nitrogen-fixing bacteria and phosphate-solubilizing bacteria in a ratio of 1:2:1 was sprayed to promote the healthy growth of the seedlings. During transplanting, the seedlings were planted at a spacing of 15 cm × 20 cm. Seven days after transplanting, 8 kg of slow-release selenium-rich fertilizer was applied per mu. During the tillering stage, 3 kg of slow-release selenium-rich fertilizer was applied again. At the same time, 2 mg / L sodium selenite solution was sprayed on the leaves during the heading stage, with a dosage of 20 kg per mu, to increase selenium absorption.

[0044] The preparation method of the slow-release selenium-rich fertilizer specifically comprises the following steps:

[0045] S1. Add montmorillonite at 0.03 g / mL into a 10% hydrochloric acid solution, stir in a water bath, filter and wash with water until the pH of the residual liquid is 7, and vacuum dry to obtain modified montmorillonite;

[0046] S2, dispersing sodium selenite into a sodium alginate solution with a mass concentration of 5%, the mass ratio of sodium selenite to sodium alginate being 1:25, stirring evenly, adding ethylene glycol dimethacrylate, the mass ratio of ethylene glycol dimethacrylate to sodium selenite being 1:1.8, stirring for 2h, adding 3-aminopropyltriethoxysilane in an amount of 0.5mg / mL to obtain a mixed solution;

[0047] S3, adding the modified montmorillonite obtained in S1 and the mixed solution obtained in S2 into ethanol respectively, with the mass ratio of modified montmorillonite to the mixed solution being 1:2, performing ultrasonic dispersion for 5 minutes, adding glutaraldehyde, and reacting at 40°C for 6 hours under nitrogen protection to obtain a degradable coating solution;

[0048] S4, adding sodium selenite, dipotassium hydrogen phosphate and urea into water in a mass ratio of 1:4:5, mixing, heating and stirring until completely dissolved, and drying to obtain inorganic fertilizer particles;

[0049] S5, dissolving zinc nitrate and 2-methylimidazole in methanol in a molar ratio of 1:4, adding imidacloprid, the mass ratio of pesticide to ZIF-8 is 1:10, stirring and reacting at room temperature for 24 hours, collecting the precipitate by centrifugation, washing with methanol 3 times, and vacuum drying to obtain ZIF-8 encapsulated pesticide;

[0050] S6. The inorganic fertilizer particles obtained in S4 are coated with the degradable coating liquid obtained in S3, the mass ratio of the coating liquid to the inorganic fertilizer particles is 1:10, and the ZIF-8 encapsulated pesticide obtained in S5 is sprayed, and the spraying amount of the ZIF-8 encapsulated pesticide is 1% of the total mass of the fertilizer, forming a three-layer slow-release structure with the inorganic fertilizer particles as the core, the coating layer loaded with the selenium source, and the outer layer encapsulating the pesticide, to obtain a slow-release selenium-rich fertilizer.

[0051] Example 2

[0052] A method for cultivating selenium-rich rice crops, comprising the following steps:

[0053] (1) Soil treatment: Before planting, test the soil, apply commercially available organic selenium fertilizer, spread it evenly and till it into the soil to ensure that the soil selenium content is 0.4 mg / kg;

[0054] (2) Seed treatment: Use Yixiangyou 2115 and soak the seeds in a 0.1% sodium selenite solution for 12 hours. Take them out and rinse them with clean water, then dry them for later use.

[0055] (3) Seedling raising and transplanting: Seedlings were raised in seedling trays. During the seedling raising period, a diluted composite microbial agent consisting of a mixture of lactic acid bacteria, nitrogen-fixing bacteria, and phosphate-solubilizing bacteria in a ratio of 1:2:1 was sprayed to promote the healthy growth of the seedlings. During transplanting, the seedlings were planted at a spacing of 15 cm × 20 cm. Seven days after transplanting, 12 kg of slow-release selenium-rich fertilizer was applied per mu. During the tillering stage, 4 kg of slow-release selenium-rich fertilizer was applied again per mu. At the same time, 4 mg / L sodium selenite solution was sprayed on the leaves during the heading stage, with a dosage of 25 kg per mu, to increase selenium absorption.

[0056] The preparation method of the slow-release selenium-rich fertilizer specifically comprises the following steps:

[0057] S1. Add montmorillonite at a concentration of 0.05 g / mL into a 15% hydrochloric acid solution, stir in a water bath, filter and wash with water until the pH of the residual liquid is 7, and dry in vacuum to obtain modified montmorillonite;

[0058] S2, dispersing sodium selenite into a sodium alginate solution with a mass concentration of 7%, the mass ratio of sodium selenite to sodium alginate being 1:35, stirring evenly, adding ethylene glycol dimethacrylate, the mass ratio of ethylene glycol dimethacrylate to sodium selenite being 1:2.2, stirring for 2h, adding 3-aminopropyltriethoxysilane in an amount of 0.5mg / mL to obtain a mixed solution;

[0059] S3, adding the modified montmorillonite obtained in S1 and the mixed solution obtained in S2 into ethanol respectively, with the mass ratio of modified montmorillonite to the mixed solution being 1:2.5, performing ultrasonic dispersion for 5 minutes, adding glutaraldehyde, and reacting at 40°C for 6 hours under nitrogen protection to obtain a degradable coating solution;

[0060] S4, adding sodium selenite, dipotassium hydrogen phosphate and urea in a mass ratio of 1:4.3:5.6 into water, mixing, heating and stirring until completely dissolved, and drying to obtain inorganic fertilizer particles;

[0061] S5, dissolving zinc nitrate and 2-methylimidazole in methanol in a molar ratio of 1:4, adding imidacloprid, the mass ratio of pesticide to ZIF-8 is 1:15, stirring and reacting at room temperature for 24 hours, collecting the precipitate by centrifugation, washing with methanol 3 times, and vacuum drying to obtain ZIF-8 encapsulated pesticide;

[0062] S6. The inorganic fertilizer particles obtained in S4 are coated with the degradable coating liquid obtained in S3, the mass ratio of the coating liquid to the inorganic fertilizer particles is 1:13, and the ZIF-8 encapsulated pesticide obtained in S5 is sprayed, and the spraying amount of the ZIF-8 encapsulated pesticide is 3% of the total mass of the fertilizer, forming a three-layer slow-release structure with the inorganic fertilizer particles as the core, the coating layer loaded with the selenium source, and the outer layer encapsulating the pesticide, to obtain a slow-release selenium-rich fertilizer.

[0063] Example 3

[0064] A method for cultivating selenium-rich rice crops, comprising the following steps:

[0065] (1) Soil treatment: Before planting, test the soil, apply commercially available organic selenium fertilizer, spread it evenly and till it into the soil to ensure that the soil selenium content is 0.35 mg / kg;

[0066] (2) Seed treatment: Use Yixiangyou 2115 and soak the seeds in a 0.1% sodium selenite solution for 12 hours. Take them out and rinse them with clean water, then dry them for later use.

[0067] (3) Seedling raising and transplanting: Seedlings were raised in seedling trays. During the seedling raising period, a diluted composite microbial agent consisting of lactic acid bacteria, nitrogen-fixing bacteria and phosphate-solubilizing bacteria in a ratio of 1:2:1 was sprayed to promote the healthy growth of the seedlings. During transplanting, the seedlings were planted at a spacing of 15 cm × 20 cm. Seven days after transplanting, 10 kg of slow-release selenium-rich fertilizer was applied per mu. During the tillering stage, 3.5 kg of slow-release selenium-rich fertilizer was applied again. At the same time, 3 mg / L sodium selenite solution was sprayed on the leaves during the heading stage, with a dosage of 22.5 kg per mu, to increase selenium absorption.

[0068] The preparation method of the slow-release selenium-rich fertilizer specifically comprises the following steps:

[0069] S1. Add montmorillonite at 0.04 g / mL into a 12% hydrochloric acid solution, stir in a water bath, filter and wash with water until the pH of the residual liquid is 7, and vacuum dry to obtain modified montmorillonite;

[0070] S2, dispersing sodium selenite into a sodium alginate solution with a mass concentration of 6%, the mass ratio of sodium selenite to sodium alginate being 1:30, stirring evenly, adding ethylene glycol dimethacrylate, the mass ratio of ethylene glycol dimethacrylate to sodium selenite being 1:2, stirring for 2h, and adding 3-aminopropyltriethoxysilane in an amount of 0.5mg / mL to obtain a mixed solution;

[0071] S3, adding the modified montmorillonite obtained in S1 and the mixed solution obtained in S2 into ethanol respectively, with the mass ratio of modified montmorillonite to the mixed solution being 1:2.2, performing ultrasonic dispersion for 5 minutes, adding glutaraldehyde, and reacting at 40°C for 6 hours under nitrogen protection to obtain a degradable coating solution;

[0072] S4, adding sodium selenite, dipotassium hydrogen phosphate and urea into water in a mass ratio of 1:4.2:5.3, mixing, heating and stirring until completely dissolved, and drying to obtain inorganic fertilizer particles;

[0073] S5, dissolving zinc nitrate and 2-methylimidazole in methanol in a molar ratio of 1:4, adding imidacloprid, the mass ratio of pesticide to ZIF-8 is 1:12.5, stirring and reacting at room temperature for 24 hours, collecting the precipitate by centrifugation, washing with methanol 3 times, and vacuum drying to obtain ZIF-8 encapsulated pesticide;

[0074] S6. The inorganic fertilizer particles obtained in S4 are coated with the degradable coating liquid obtained in S3, the mass ratio of the coating liquid to the inorganic fertilizer particles is 1:12.5, and the ZIF-8 encapsulated pesticide obtained in S5 is sprayed, and the spraying amount of the ZIF-8 encapsulated pesticide is 2% of the total mass of the fertilizer, forming a three-layer slow-release structure with the inorganic fertilizer particles as the core, the coating layer loaded with the selenium source, and the outer layer encapsulating the pesticide, to obtain a slow-release selenium-rich fertilizer.

[0075] Comparative Example 1

[0076] Compared with Example 1, the only difference is that the fertilizer components used do not contain sodium alginate and montmorillonite, that is, no degradable coating liquid is used for coating, and the other components and component contents are the same as those in Example 1.

[0077] Comparative Example 2

[0078] Compared with Example 1, the only difference is that the fertilizer components used do not contain zinc nitrate and 2-methylimidazole, that is, ZIF-8 encapsulated imidacloprid is not prepared, and imidacloprid is simply sprayed on the fertilizer surface. The other components and component contents are the same as in Example 1.

[0079] Comparative Example 3

[0080] Compared with Example 1, the only difference is that no composite microbial agent is used in step (3).

[0081] Comparative Example 4

[0082] Compared with Example 1, the only difference is that in step (3), the fertilizer applied 7 days after transplanting and during the tillering period is a commercially available organic selenium fertilizer with an equal selenium content.

[0083] Experimental example

[0084] 1. Rice Selenium Content Test

[0085] The experimental groups were the rice obtained in Examples 1-3 and Comparative Examples 1-4, and the blank group was the rice obtained in Comparative Example 4. The selenium content was measured respectively, and the selenium content improvement rate was calculated by the following formula:

[0086] Selenium content increase rate = (selenium content in the experimental group - selenium content in the blank group) / selenium content in the blank group.

[0087] Figure 1 This is a result diagram of the increase rate of selenium content in rice of Example 1-3 of Comparative Example 1-3 of the present invention. As shown in the figure, the increase rate of selenium content in Example 1-3 is significantly higher than that in Comparative Example 1-3. The use of slow-release selenium-rich fertilizer and composite microbial agent effectively increases the selenium content of rice.

[0088] 2. Fertilizer release test

[0089] Under a constant temperature of 15° C., the fertilizers obtained in Examples 1-3 and Comparative Example 1 were placed in nylon bags and immersed in 300 mL of distilled water. The immersion liquid was taken out on the 1st, 5th, 10th, 15th and 20th days, the selenium content in the solution was determined, and the dissolution rate of the fertilizer in water was calculated by the following formula: dissolution rate of the fertilizer in water = selenium content in the solution / total amount of selenium in the fertilizer × 100%.

[0090] The fertilizers obtained in Examples 1-3 and Comparative Example 1 were put into non-woven bags and placed in soil at a depth of about 5 cm and a relative humidity of 25%. The bags were taken out on the 1st, 5th, 10th, 15th and 20th days respectively, the soil adhering to the bags was cleaned and then dried and weighed, and the fertilizer soil dissolution rate was calculated by the following formula: fertilizer soil dissolution rate = (mass before experiment - mass after experiment) / mass before experiment × 100%.

[0091] Figure 2 This is the result diagram of the dissolution rate of fertilizer in water in Examples 1-3 and Comparative Example 1. Figure 3 The results of the fertilizer soil dissolution rate of Examples 1-3 and Comparative Example 1 are shown in the figure; as shown in the figure, the dissolution rate of the fertilizer obtained in Examples 1-3 in water and soil is significantly lower than that in Comparative Example 1.

[0092] 3. Imidacloprid Release Test

[0093] Take the fertilizers obtained in Examples 1-3 and Comparative Example 2, put them into nylon bags at room temperature, immerse them in 300 mL of distilled water, take out the immersion liquid on the 1st, 3rd, 5th, 7th and 9th days, determine the imidacloprid content in the solution, and calculate the imidacloprid dissolution rate by the following formula: imidacloprid dissolution rate in water = imidacloprid content in the solution / total amount of imidacloprid in the fertilizer × 100%.

[0094] The fertilizers obtained in Examples 1-3 and Comparative Example 2 were put into non-woven bags at room temperature and placed in soil at a depth of about 5 cm and a relative humidity of 25%. The bags were taken out on the 3rd, 6th, 9th, 12th and 15th days respectively, and the imidacloprid content in the solution was dissolved and determined. The soil dissolution rate of the fertilizer was calculated by the following formula: soil dissolution rate of imidacloprid = (imidacloprid content in fertilizer - imidacloprid content in solution) / imidacloprid content in fertilizer × 100%.

[0095] Figure 4 The results of the dissolution rate of imidacloprid in water of Examples 1-3 and Comparative Example 2 are shown in FIG. Figure 5 The results of imidacloprid soil dissolution rate of Examples 1-3 and Comparative Example 2 are shown in the figure; as shown in the figure, the dissolution rate of imidacloprid in water and soil in the fertilizer obtained in Examples 1-3 is significantly lower than that in Comparative Example 2.

[0096] While the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that many changes, modifications, substitutions and variations can be made to the embodiments without departing from the principles and spirit of the invention.

[0097] The present invention and its implementation methods are described above, which is not restrictive. The drawings are only one of the implementation methods of the present invention, and the actual application is not limited thereto. In short, if ordinary technicians in the field are inspired by it and design methods and embodiments similar to the technical solution without creativity without departing from the purpose of the invention, they should all fall within the protection scope of the present invention.

Claims

1. A method for cultivating selenium-rich rice crops, characterized in that: The specific steps include: (1) Soil treatment: Before planting, test the soil, apply commercially available organic selenium fertilizer, spread it evenly and till it into the soil to ensure that the soil selenium content is 0.3-0.4 mg / kg; (2) Seed treatment: Select rice varieties that are suitable for the local climate, have strong disease resistance and high selenium enrichment capacity, soak the seeds in a 0.1% sodium selenite solution for 12 hours, remove them from the water, rinse them with clean water, and dry them for later use; (3) Seedling raising and transplanting: Seedlings are raised in seedling trays. During the seedling raising period, diluted compound microbial agents are sprayed to promote the healthy growth of seedlings. During transplanting, the seedlings are planted at a spacing of 15 cm × 20 cm. Seven days after transplanting, 8-12 kg of slow-release selenium-rich fertilizer is applied per mu. During the tillering stage, 3-4 kg of slow-release selenium-rich fertilizer is applied again. At the same time, 2-4 mg / L sodium selenite solution is sprayed on the leaves during the heading stage, with a dosage of 20-25 kg per mu, to increase selenium absorption.

2. The method for cultivating selenium-rich rice crops according to claim 1, characterized in that: In step (2), the rice variety is one of Huazhongyou 9326, Yixiangyou 2115, Qunyou 2, and Jingliangyou 5348.

3. The method for cultivating selenium-rich rice crops according to claim 2, characterized in that: In step (2), the rice variety is Yixiangyou 2115.

4. The method for cultivating selenium-enriched rice crops according to claim 3, characterized in that: In step (3), the composite microbial agent is obtained by mixing lactic acid bacteria, nitrogen-fixing bacteria, and phosphate-solubilizing bacteria in a ratio of 1:2:

1.

5. The method for cultivating selenium-enriched rice crops according to claim 4, characterized in that: In step (3), the lactic acid bacteria have a strain number of CICC20766; the nitrogen-fixing bacteria have a strain number of CICC21686; and the phosphate-solubilizing bacteria have a strain number of CICC22681.

6. The method for cultivating selenium-rich rice crops according to claim 5, characterized in that: The preparation method of the slow-release selenium-rich fertilizer specifically comprises the following steps: S1, adding montmorillonite to a hydrochloric acid solution, stirring in a water bath, filtering and washing with water until the pH value of the residual liquid is 7, and vacuum drying to obtain modified montmorillonite; S2, dispersing sodium selenite into the sodium alginate solution, stirring evenly, adding ethylene glycol dimethacrylate, stirring for 2 h, and adding 3-aminopropyltriethoxysilane in an amount of 0.5 mg / mL to obtain a mixed solution; S3, adding the modified montmorillonite obtained in S1 and the mixed solution obtained in S2 into ethanol respectively, ultrasonically dispersing for 5 minutes, adding glutaraldehyde, and reacting at 40°C for 6 hours under nitrogen protection to obtain a degradable coating solution; S4, adding sodium selenite, dipotassium hydrogen phosphate and urea into water at a mass ratio of 1:4-4.3:5-5.6, mixing, heating and stirring until completely dissolved, and drying to obtain inorganic fertilizer particles; S5, dissolving zinc nitrate and 2-methylimidazole in methanol in a molar ratio of 1:4, adding imidacloprid, the mass ratio of pesticide to ZIF-8 is 1:10-15, stirring and reacting at room temperature for 24 hours, collecting the precipitate by centrifugation, washing with methanol 3 times, and vacuum drying to obtain ZIF-8 encapsulated pesticide; S6. The inorganic fertilizer particles obtained in S4 are coated with the degradable coating liquid obtained in S3, and the ZIF-8 encapsulated pesticide obtained in S5 is sprayed to form a three-layer slow-release structure with the inorganic fertilizer particles as the core, the coating layer loaded with the selenium source, and the outer layer encapsulating the pesticide, so as to obtain a slow-release selenium-rich fertilizer.

7. The method for cultivating selenium-rich rice crops according to claim 6, characterized in that: In S1, the volume fraction of the hydrochloric acid solution is 10-15%, the amount of montmorillonite added is 0.03-0.05 g / mL, the water bath temperature is 30-50°C, the stirring rate is 250-400 rpm, and the time is 2-4 h.

8. The method for cultivating selenium-enriched rice crops according to claim 7, characterized in that: In S2, the mass concentration of the sodium alginate solution is 5-7%, the mass ratio of sodium selenite to sodium alginate is 1:25-35; and the mass ratio of ethylene glycol dimethacrylate to sodium selenite is 1:1.8-2.

2.

9. The method for cultivating selenium-enriched rice crops according to claim 8, characterized in that: In S3, the mass ratio of modified montmorillonite to the mixed solution is 1:2-2.

5.

10. The method for cultivating selenium-enriched rice crops according to claim 9, characterized in that: In S6, the mass ratio of the degradable coating liquid to the phosphate mixed fertilizer particles is 1:10-13, and the spraying amount of the ZIF-8 encapsulated pesticide is 1-3% of the total mass of the fertilizer.

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