Drought-resistant and saline-alkaline-tolerant corn seed coating agent and preparation method thereof

Abstract

The invention relates to the technical field of seed coating agents, in particular to a drought-resistant and saline-alkaline-tolerant corn seed coating agent and a preparation method thereof, and the drought-resistant and saline-alkaline-tolerant corn seed coating agent comprises the following raw materials: nano polyacrylamide, polyvinyl alcohol, Mo-coated ZIF-8, modified MgAl-LDH, gibberellin, proline, citric acid, sodium carboxymethyl cellulose and bacillus subtilis. According to the method, the drought resistance and saline-alkaline tolerance of the corn seeds are synergistically improved through Mo and ZIF-8 and modified MgAl-LDH, Na < + > is prevented from entering epidermis cells of the seeds by adsorbing Na < + >, saline-alkaline stress is relieved, the modified MgAl-LDH and water molecules form a hydration layer, water is effectively reserved, dynamic water regulation is achieved through surface grafted polydopamine, the drought resistance of the corn seeds is enhanced, and the drought resistance of the corn seeds is improved. The catalytic activity of the Mo-ZIF-8 is enhanced through a photothermal effect, Cl <-> is promoted to be oxidized into Cl2 to be released, and imidazole molecules gradually released by the Mo-ZIF-8 reduce the alkalinity of a rhizosphere environment, improve a seed germination environment, optimize a rhizosphere microbial environment and promote the growth of a crop root system.

Description

Technical Field

[0001] The invention relates to the technical field of seed coating agents, in particular to a drought-resistant and salt-alkali-tolerant corn seed coating agent and a preparation method thereof. Background Art

[0002] Corn is one of the most important food crops in the world, and its yield directly affects the agricultural economy and food security. However, global climate change and unreasonable farming methods have caused the gradual degradation of arable land, and drought and salinity stress have become the main environmental factors affecting corn yields. In a drought environment, the soil moisture is seriously insufficient, and the seed water absorption is limited, resulting in a reduced germination rate and difficulty in seedling emergence. In addition, salinity stress also hinders seed germination through osmotic stress and ion poisoning, and even causes plant death. Seed coating agent is a film-forming preparation used for seed pre-sowing treatment. Traditional seed coating agents are mainly used to improve seed sowing adaptability and disease control. They often contain pesticides, fungicides, viscosity enhancers and trace elements. They are still insufficient in enhancing seed drought resistance and salt-alkali resistance. Traditional seed coating agents cannot effectively absorb and retain soil moisture, have poor water retention, and are difficult to maintain the water environment required for seed germination under drought conditions. They cannot effectively alleviate salt damage, and seed germination and seedling growth are still inhibited. In addition, traditional seed coating agents have a single function and focus more on disease control, without fully considering enhancing the ability of seeds to adapt to adversity. In recent years, nanotechnology has been increasingly used in the agricultural field. Nanomaterials, due to their ultra-high specific surface area, slow-release capacity and multifunctionality, can effectively improve the resistance of seeds to adversity. They can not only improve the seed germination environment and promote early growth, but also increase the survival rate of plants under adversity, providing more reliable protection for corn planting. Therefore, developing a nano seed coating agent that can enhance the drought and salt-alkali resistance of seeds and at the same time have a growth-promoting function is of great significance for the high and stable yield of corn. Summary of the invention

[0003] (1) Technical issues to be resolved The invention aims to provide a drought-resistant and salt-alkali-tolerant corn seed coating agent and a preparation method thereof, which can significantly improve the drought resistance of corn seeds by optimizing the formula of the corn seed coating agent and combining modern nanotechnology, thereby ensuring the water absorption and germination of seeds in a drought environment, and at the same time enhancing the salt-alkali resistance of seeds, reducing the inhibition of seed germination by salt-alkali stress, improving the seed germination rate, promoting seedling growth, and enhancing stress resistance, thereby providing effective guarantee for the stable growth and high yield of corn in a drought and salt-alkali stress environment.

[0004] (2) Technical solution To achieve the above object, on the one hand, the present invention provides a drought-resistant and salt-alkali-tolerant corn seed coating agent, comprising the following raw materials in parts by weight: 10-20 parts of nano-polyacrylamide, 5-10 parts of polyvinyl alcohol, 15-25 parts of modified magnesium aluminum layered double hydroxide (modified MgAl-LDH), 0.2-1 parts of gibberellin, 0.1-0.5 parts of proline, 1-3 parts of citric acid, 10-20 parts of sodium carboxymethyl cellulose, 6-10 parts of Bacillus subtilis, and 50-60 parts of purified water; The drought-resistant and salt-alkali-tolerant corn seed coating agent also includes: Mo@ZIF-8; The weight ratio of Mo@ZIF-8 to modified MgAl-LDH is 5:(15-25); The nanometer size of Mo@ZIF-8 is 85-125 nm, and the specific surface area is 1300-1400 m 2 / g.

[0005] Furthermore, the preparation method of Mo@ZIF-8 comprises: S11. Under nitrogen protection and stirring, zinc nitrate is dissolved in methanol to obtain a zinc nitrate solution, and 2-methylimidazole and ammonium molybdate are dissolved in methanol together and stirred for 1-2 hours, and then the zinc nitrate solution is slowly added, and the temperature is raised to 35-45°C, and the stirring reaction is continued for 24-26 hours, and the pH value is controlled to 10.5-11 with ammonia water, and the first mixed solution is obtained after standing for 15-18 hours; S12. The first mixed solution is subjected to high-speed centrifugation at a speed of 8000-10000 rpm for 10-15 min. The separated solid is washed alternately with methanol and purified water for 3 times and then vacuum dried at a drying temperature of 135-145° C. After drying for 6-8 h, Mo@ZIF-8 is obtained and ground into powder for later use.

[0006] Furthermore, the molar ratio of the zinc nitrate, 2-methylimidazole and ammonium molybdate is 1:(8-10):(0.02-0.04).

[0007] Furthermore, the preparation method of the modified MgAl-LDH comprises: S21. Dissolve magnesium nitrate and aluminum nitrate in purified water under stirring, and control Mg 2+ and Al 3+ The molar ratio of is 3:1, and a 0.2 mol / L metal ion mixed solution is prepared; S22. Slowly add 1 mol / L sodium hydroxide solution to the metal ion mixed solution under nitrogen protection and stirring until the pH value rises to 9.5-10.5, and raise the temperature to 65-75°C, continue stirring and reacting for 4-6 hours, and then stand for 12-15 hours to obtain a second mixed solution; S23. The second mixed solution was separated by vacuum filtration, and the separated precipitate was washed three times with purified water and then vacuum dried at a drying temperature of 55 to 65 ° C. After drying for 12 to 15 hours, MgAl-LDH was obtained and ground into a powder for later use; S24. Dissolve dopamine hydrochloride in phosphate buffered saline under nitrogen protection and stirring, slowly add MgAl-LDH powder after stirring for 0.5-1h, raise the temperature to 35-45°C, and control the pH value to 8.5-9 with 0.1 mol / L sodium hydroxide solution, continue stirring for 14-16h to obtain a third mixed solution; S25. The third mixed solution is subjected to high-speed centrifugation at a speed of 8000-10000 rpm for 10-15 min. The separated solid is washed three times with purified water and then vacuum dried at a drying temperature of 65-75° C. After drying for 12-15 h, the modified MgAl-LDH is obtained and ground into powder for later use.

[0008] Furthermore, the nanometer size of the modified MgAl-LDH is 100-120 nm, and the specific surface area is 120-150 m 2 / g.

[0009] Furthermore, the mass ratio of the MgAl-LDH to dopamine hydrochloride is 1:(0.1-0.3).

[0010] On the other hand, based on the same inventive concept, the present invention also provides a method for preparing a drought-resistant and salt-alkali-tolerant corn seed coating agent, which is applied to the drought-resistant and salt-alkali-tolerant corn seed coating agent, comprising the following steps: S31. Add polyvinyl alcohol to purified water in a container and stir well, while heating to 75~85°C, stirring for 1~2h and then cooling to 30~40°C, then adding sodium carboxymethyl cellulose and stirring for 1~2h, controlling the stirring speed to 300~400 rpm, cooling to room temperature, and stirring at room temperature for 0.5~1h to obtain a fourth mixed solution; S32. Nano-polyacrylamide, Mo@ZIF-8 and modified MgAl-LDH were added to the fourth mixed solution in sequence under stirring, and the mixture was stirred evenly at a stirring speed of 400-600 rpm and a stirring temperature of 45-55° C. After stirring for 0.5-1 h, ultrasonic treatment was performed at a frequency of 40-50 kHz for 0.5-1 h to obtain a fifth mixed solution; S33. Proline and citric acid were added to the fifth mixed solution under stirring and stirred for 0.5 to 1 h, while the pH value was controlled at 6.5 to 7.5 with phosphate buffered saline, followed by the addition of gibberellin, and stirring was continued for 0.5 to 1 h to obtain a sixth mixed solution; S34. Slowly add the Bacillus subtilis solution to the sixth mixed solution under low-speed stirring, control the stirring speed to 200-250 rpm, continue stirring at room temperature for 10-20 minutes, and then filter through a 0.22 μm filter membrane to obtain the drought-resistant and salt-alkali-resistant corn seed coating agent.

[0011] Furthermore, the method for using the drought-resistant and salt-alkali-tolerant corn seed coating agent is as follows: take corn seeds, coat them at a ratio of 1 kg of corn seeds: 20-30 mL of seed coating agent, use a drum seed coating machine to evenly coat at a speed of 50-100 rpm, and then place the coated seeds in a ventilated environment to air-dry until the surface is dry and not sticky.

[0012] The mechanism of action of the above raw material components is as follows: Nano-polyacrylamide is a high molecular polymer with super water absorption and water retention capacity. It can absorb hundreds of times its own weight of water through a nano-scale three-dimensional network structure, form a hydrogel film on the surface of seeds, reduce the evaporation rate of water, maintain a moist environment around the seeds, ensure the water absorption needs of seeds under drought conditions, and improve the germination rate. It can also adsorb and slowly release water-soluble nutrients to maintain the nutrient supply required for seed germination and early growth of seedlings, and improve the germination rate of corn seeds. Polyvinyl alcohol is a water-soluble polymer material with good film-forming and adhesion properties. It can form a hydrophilic film on the surface of seeds to protect seeds from the influence of adverse external environments, prolong the action time of active substances, and at the same time enhance the binding force between seed coating agents and seeds, ensuring that other active ingredients are firmly coated to avoid falling off. Gibberellic acid is a plant growth regulator that can promote cell division, elongation and seed germination, while enhancing salt tolerance, improving root growth, increasing water and nutrient absorption, alleviating the inhibitory effect of salt-alkali stress on seedlings, and improving seedling growth. Proline is a natural amino acid with osmotic regulation and antioxidant functions. It can improve the tolerance of plant cells to drought, salinity and other adversities. It can balance the osmotic pressure inside and outside the cell, reduce water loss, protect the cell membrane structure, maintain cell activity, protect seeds and seedlings from osmotic stress damage, and remove reactive oxygen species produced by salinity stress, reduce oxidative damage, and enhance plant resistance. Citric acid is a natural organic acid that can chelate the , It can reduce the toxicity of salt ions to seeds and seedlings, relieve saline-alkali stress, and improve the root environment of crops. It can adjust soil pH, promote the reproduction of rhizosphere microorganisms, release trace elements, improve the early nutrient supply of seeds, and enhance the absorption capacity of corn seeds for nutrients and water. Sodium carboxymethyl cellulose is a natural polymer binder with the dual functions of water absorption and moisturizing and slow release. It can enhance the adhesion of seed dressing agents to seeds and prevent the loss of active ingredients. At the same time, it absorbs moisture in the environment, maintains moisture around seeds, helps seeds germinate, and can also slow-release active substances to prolong the action time of seed dressing agents. Bacillus subtilis is a probiotic microorganism that can secrete biologically active substances such as organic acids and extracellular polymers, improve the soil environment, inhibit harmful bacteria, enhance the disease resistance of seeds and seedlings, and increase the field seedling rate.

[0013] In the drought-resistant and salt-alkali-tolerant corn seed coating agent, Mo@ZIF-8 and modified MgAl-LDH synergistically improve the drought resistance and salt-alkali resistance of corn seeds. Mo@ZIF-8 is a metal-organic framework material prepared by loading molybdenum nanoparticles on the surface of ZIF-8. It has a highly ordered nanoscale pore structure and its pore size (about 3.4Å) is suitable for selective screening of small ions. In the soil environment, Mo@ZIF-8 has a strong affinity for Na + Has strong adsorption capacity. The selectivity is low, and Mo@ZIF-8 will preferentially adsorb Na + , thereby reducing Entering corn seed epidermal cells, alleviating salt-alkali stress and maintaining concentration, so that / Ratio increases, high / The ratio helps maintain cell osmotic pressure, prevent water loss, reduce dehydration caused by salt stress, and also helps maintain enzyme activity, maintain intracellular protein synthesis and energy metabolism, and promote seed growth. Magnesium aluminum layered double hydroxide (MgAl-LDH) is a layered nanomaterial with ion exchange and slow release properties. It is composed of positively charged Mg 2+ and Al 3+ Laminates, and OH sandwiched between the layers - 、NO3 - PO4 3-The modified MgAl-LDH is composed of exchangeable anions such as MgAl-LDH, and the surface of the modified MgAl-LDH is grafted with polydopamine, which can effectively alleviate salt-alkali stress and promote water retention. In a drought environment, the -OH between the modified MgAl-LDH layers and water molecules form a stable hydration layer through physical adsorption and chemical combination, effectively retaining water and maintaining the local high humidity environment around the corn seeds. The surface of the modified MgAl-LDH grafted with polydopamine helps to achieve dynamic water regulation. When the light is strong during the day, polydopamine absorbs solar energy and converts it into local heat energy, raising the temperature around the seeds, promoting the release of bound water between the modified MgAl-LDH layers, and effectively replenishing the water required for the growth of corn seeds; when the temperature drops at night, polydopamine reduces the photothermal effect, and the -OH between the modified MgAl-LDH layers can reabsorb moisture in the air to form a dynamic water recovery system, enhancing the water retention capacity of the environment around the seeds, thereby enhancing the drought resistance of corn seeds and promoting seed germination and root extension. At the same time, polydopamine enhances the catalytic activity of Mo nanoparticles in Mo@ZIF-8 through the photothermal effect, promoting Cl - Oxidized to Cl2 release, enhancing the Cl - The conversion efficiency can effectively reduce Cl in saline-alkali environment - Toxic to corn seeds. At the same time, the modified MgAl-LDH can also slowly release Mg 2+ 、Al 3+ 、NO3 - PO4 3- nutrients required for crop growth, and exchange ions with the soil Competitive adsorption effectively inhibits The accumulation of Mg can reduce its toxicity to the cell membrane and metabolic enzyme activity of corn seeds, and enhance the salt-alkali resistance of corn seeds. In addition, the pH value of saline-alkali soil is usually high, above 8.5, which makes Mg 2+ 、Al 3+ 、NO3 - PO4 3- Nutrients such as Mo@ZIF-8 form insoluble compounds under alkaline conditions, which reduce nutrient availability, affect cell physiological metabolism, inhibit root development, and affect rhizosphere microbial communities, reducing the activity of rhizosphere growth-promoting bacteria, thereby affecting crop health. However, in the high pH environment of saline-alkali soil, the framework structure of Mo@ZIF-8 will gradually dissociate and slowly release Mo. 6+ 、Zn 2+ and imidazole molecules, Mo 6+ It is a cofactor of nitrate reductase, which can improve the utilization rate of nitrogen in corn seeds, help crop seedlings maintain nitrogen metabolism homeostasis in saline-alkali environments, provide crops with amino acids, and enhance crop stress resistance; Zn 2+It is an essential element for chlorophyll synthesis, which can ensure that corn seeds can still efficiently synthesize organic matter under adverse conditions and enhance the growth momentum of corn under adverse conditions; while imidazole molecules are amphiphilic molecules and will absorb , reduce the alkalinity of the rhizosphere environment, improve the seed germination environment, improve nutrient absorption, optimize the rhizosphere microbial environment, and promote crop root growth. In short, Mo@ZIF-8 and modified MgAl-LDH synergistically improve the drought resistance and salt-alkali tolerance of corn seeds, increase seed germination rate, promote seedling growth, enhance stress resistance, and provide effective guarantee for the stable growth and high yield of corn under drought and saline-alkali stress environments.

[0014] (3) Beneficial effects Compared with the prior art, the present invention has the following beneficial effects: 1. Mo@ZIF-8 and modified MgAl-LDH synergistically improve the drought resistance and salt-alkali tolerance of corn seeds. Mo@ZIF-8 preferentially adsorbs ,reduce Entering corn seed epidermal cells, alleviating salt-alkali stress and maintaining concentration, so that / The ratio increases, maintaining cell osmotic pressure, maintaining protein synthesis and energy metabolism in cells, and promoting seed growth; 2. The -OH between the modified MgAl-LDH layers and water molecules form a stable hydration layer through physical adsorption and chemical bonding, effectively retaining moisture and maintaining a local high humidity environment around the corn seeds. The polydopamine grafted on its surface helps achieve dynamic moisture regulation and enhances the drought resistance of corn seeds. 3. Polydopamine on the surface of modified MgAl-LDH enhances the catalytic activity of Mo nanoparticles in Mo@ZIF-8 through photothermal effect, promoting Cl - Oxidized to Cl2 release, enhancing the Cl - The conversion efficiency can effectively reduce Cl in saline-alkali environment - poisoning of corn seeds; 4. Modified MgAl-LDH slowly releases Mg 2+ 、Al 3+ 、NO3 - PO4 3- The nutrients needed for crop growth are exchanged with the soil Competitive adsorption is used to inhibit its accumulation and enhance the salt-alkali tolerance of corn seeds; 5. Mo@ZIF-8 gradually and slowly releases Mo in saline-alkali soil 6+ 、Zn 2+ and imidazole molecules, Mo 6+ Helps crop seedlings maintain nitrogen metabolism homeostasis, Zn2+ Enhance the growth power of corn. Imidazole molecules reduce the alkalinity of the rhizosphere environment, improve the seed germination environment, optimize the rhizosphere microbial environment, and promote the growth of crop roots. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is the SEM image of Mo@ZIF-8 in Example 1 of the present invention; Figure 2 This is the SEM image of the modified MgAl-LDH in Example 1 of the present invention. DETAILED DESCRIPTION

[0016] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0017] The experimental equipment and preparations of the embodiments described below are as follows: electronic balance (Sartorius, Germany), electric constant temperature water bath (Jiangsu Kedao), magnetic stirrer (Shanghai Meiyingpu), high-speed centrifuge (Guangzhou Jidi), vacuum drying oven (Shanghai Jiecheng), ultrasonic instrument (Shanghai Yixin), scanning electron microscope (Zeiss, Germany), specific surface area analyzer (Beijing Best Instrument Technology), seed coating machine (Shijiazhuang Sanli Grain), handheld chlorophyll SPAD instrument (Qingdao Corede), leaf area meter (Shandong Laiyin); chemicals and reagents were purchased from Sigma-Aldrich.

[0018] Example 1: This example discloses a drought-resistant and salt-alkali-tolerant corn seed coating agent, comprising the following raw materials in parts by weight: 15 parts of nano-polyacrylamide, 7.5 parts of polyvinyl alcohol, 20 parts of modified MgAl-LDH, 0.6 parts of gibberellin, 0.3 parts of proline, 2 parts of citric acid, 15 parts of sodium carboxymethyl cellulose, 8 parts of Bacillus subtilis, and 55 parts of purified water. The drought-resistant and salt-alkali-tolerant corn seed coating agent also includes Mo@ZIF-8, wherein the weight ratio of Mo@ZIF-8 to modified MgAl-LDH is 5:20, and the nanometer size of Mo@ZIF-8 is 90 nm, and the specific surface area is 1380 m 2 / g.

[0019] In the drought-resistant and salt-alkali-tolerant corn seed coating agent, Mo@ZIF-8 and modified MgAl-LDH synergistically improve the drought resistance and salt-alkali resistance of corn seeds. Mo@ZIF-8 is a metal-organic framework material prepared by loading molybdenum nanoparticles on the surface of ZIF-8. Figure 1This is the SEM image of Mo@ZIF-8. It can be seen that Mo@ZIF-8 has a highly ordered nanoscale pore structure with a pore size of about 3.4Å, which is suitable for selective screening of small ions. Therefore, in the soil environment, Mo@ZIF-8 can effectively screen and preferentially adsorb Na + , thereby reducing Entering the epidermal cells of corn seeds, it alleviates salt-alkali stress, and for larger radius The selectivity of Mo@ZIF-8 is relatively low. The strong adsorption effect can effectively reduce the free concentration, so that corn seeds can preferentially absorb , thereby maintaining high intracellular / Ratio, high / The ratio is crucial to the osmotic regulation of cells. / The ratio helps maintain cell osmotic pressure, prevent water loss, reduce dehydration caused by salt stress, and also helps maintain enzyme activity, maintain intracellular protein synthesis and energy metabolism, enhance cell vitality, and promote seed growth. MgAl-LDH is a layered nanomaterial with ion exchange and slow release properties. It is composed of positively charged Mg 2+ and Al 3+ Laminates, and OH sandwiched between the layers - 、NO3 - PO4 3- The modified MgAl-LDH was obtained by grafting polydopamine on its surface, which can effectively alleviate salt-alkali stress and promote water retention. Figure 2The SEM image of modified MgAl-LDH shows that the modified MgAl-LDH has a distinct layered structure. In arid environments, the large number of nanoscale pores between the modified MgAl-LDH layers have strong capillary adsorption capacity for water molecules and can absorb moisture from the air. The -OH between the modified MgAl-LDH layers forms hydrogen bonds with water molecules, which enhances the fixation capacity for water molecules. That is, the modified MgAl-LDH forms a stable hydration layer with water molecules through physical adsorption and chemical bonding, effectively retaining moisture. This dual effect can effectively maintain the local high humidity environment around corn seeds. The surface grafting of polydopamine on the modified MgAl-LDH helps to achieve dynamic moisture regulation. Polydopamine is a A chemical substance with excellent photothermal conversion and biocompatibility. When the light is strong during the day, polydopamine absorbs solar energy and converts it into local heat energy, raising the temperature around the seeds, prompting the release of bound water between the modified MgAl-LDH layers, and effectively replenishing the water needed for corn seed growth; when the temperature drops at night, polydopamine reduces the photothermal effect, and the -OH between the modified MgAl-LDH layers can reabsorb moisture from the air and restore its hydration state, forming a dynamic water recovery system, enhancing the water retention capacity of the environment around the seeds, thereby enhancing the drought resistance of corn seeds, ensuring that corn seeds effectively absorb water under drought conditions, reducing water loss, improving water use efficiency, and promoting seed germination and root extension. At the same time, polydopamine enhances the oxidation catalytic activity of Mo nanoparticles in Mo@ZIF-8 through the photothermal effect, promoting Cl in the soil and rhizosphere environment. - Oxidized to volatile Cl2 release, enhancing the Cl - The conversion efficiency can effectively reduce Cl in saline-alkali environment - Toxic to corn seeds. At the same time, the modified MgAl-LDH can also slowly release Mg 2+ 、Al 3+ 、NO3 - PO4 3- nutrients required for crop growth, and exchange ions with the soil Competitive adsorption to prevent Entering corn seed epidermal cells, reducing The accumulation of Mg on the cell membrane reduces its toxicity to the cell membrane and metabolic enzyme activity of corn seeds and enhances the salt-alkali resistance of corn seeds. In addition, the pH value of saline-alkali soil is usually high, above 8.5, which makes Mg 2+ 、Al 3+ 、NO3 - PO4 3-Nutrients such as chlorinated molybdenum and chlorinated molybdenum tend to form insoluble compounds under alkaline conditions, which makes it impossible for crops to effectively absorb these nutrients necessary for growth, reduces nutrient availability, affects cell physiological metabolism, inhibits root development, and also affects the rhizosphere microbial community and reduces the activity of rhizosphere growth-promoting bacteria, thereby affecting crop health. However, in the high pH environment of saline-alkali soil, the organic framework structure of Mo@ZIF-8 will gradually dissociate and slowly release Mo. 6+ 、Zn 2+ and imidazole molecules, Mo 6+ It is an important cofactor of nitrate reductase, which can improve the utilization rate of nitrogen in corn seeds, help crop seedlings maintain nitrogen metabolism homeostasis in saline-alkali environments, provide crops with amino acids and proteins, help seedlings quickly adapt to adverse environments, and enhance stress resistance; Zn 2+ It is an essential element for chlorophyll synthesis, which can ensure that corn seeds can still efficiently synthesize organic matter under adverse conditions and enhance the growth momentum of corn under adverse conditions; while imidazole molecules are amphiphilic molecules and will absorb , reduce the alkalinity of the rhizosphere environment, improve the seed germination environment, prevent nutrient solidification, and enhance Mg 2+ 、Al 3+ 、NO3 - PO4 3- In summary, Mo@ZIF-8 and modified MgAl-LDH synergistically improve the drought resistance and salt-alkali tolerance of corn seeds, increase seed germination rate, promote seedling growth, enhance stress resistance, and provide effective guarantee for the stable growth and high yield of corn under drought and salt-alkali stress environments.

[0020] The preparation method of Mo@ZIF-8 comprises: S11. Dissolve zinc nitrate in methanol under nitrogen protection and stirring to obtain a zinc nitrate solution, then dissolve 2-methylimidazole and ammonium molybdate in methanol and stir for 1.5 hours, then slowly add the zinc nitrate solution, raise the temperature to 40°C, continue stirring and react for 25 hours, and control the pH value to 10.8 with aqueous ammonia, and stand for 16 hours to obtain a first mixed solution; S12. The first mixed solution was subjected to high-speed centrifugation at a speed of 9000 rpm for 12 min. The separated solid was washed alternately with methanol and purified water for 3 times and then vacuum dried at a drying temperature of 140° C. After drying for 7 h, Mo@ZIF-8 was obtained and ground into powder for later use.

[0021] The molar ratio of the zinc nitrate, 2-methylimidazole and ammonium molybdate is 1:9:0.03.

[0022] The preparation method of the modified MgAl-LDH comprises: S21. Dissolve magnesium nitrate and aluminum nitrate in purified water under stirring, and control Mg 2+ and Al 3+ The molar ratio of is 3:1, and a 0.2 mol / L metal ion mixed solution is prepared; S22. Slowly add 1 mol / L sodium hydroxide solution to the metal ion mixed solution under nitrogen protection and stirring until the pH value rises to 10, and raise the temperature to 70° C., continue stirring and reacting for 5 h, and then stand for 14 h to obtain a second mixed solution; S23. The second mixed solution was separated by vacuum filtration, and the separated precipitate was washed three times with purified water and then vacuum dried at a drying temperature of 60 ° C. After drying for 14 h, MgAl-LDH was obtained and ground into a powder for later use; S24. Dissolve dopamine hydrochloride in phosphate buffered saline under nitrogen protection and stirring, slowly add MgAl-LDH powder after stirring for 0.8 h, raise the temperature to 40° C., and control the pH value to 8.8 with 0.1 mol / L sodium hydroxide solution, and continue stirring for 15 h to obtain a third mixed solution; S25. The third mixed solution was subjected to high-speed centrifugation at a speed of 9000 rpm for 12 min. The separated solid was washed three times with purified water and then vacuum dried at a drying temperature of 70° C. After drying for 14 h, the modified MgAl-LDH was obtained and ground into powder for later use.

[0023] The nanometer size of the modified MgAl-LDH is 105 nm and the specific surface area is 145 m 2 / g.

[0024] The mass ratio of the MgAl-LDH to dopamine hydrochloride is 1:0.2.

[0025] A method for preparing a drought-resistant and salt-alkali-tolerant corn seed coating agent, which is applied to the drought-resistant and salt-alkali-tolerant corn seed coating agent, comprises the following steps: S31. Add polyvinyl alcohol to purified water in a container and stir well, while heating to 75~85°C, stirring for 1~2h and then cooling to 30~40°C, then adding sodium carboxymethyl cellulose and stirring for 1~2h, controlling the stirring speed to 300~400 rpm, cooling to room temperature, and stirring at room temperature for 0.5~1h to obtain a fourth mixed solution; S32. Nano-polyacrylamide, Mo@ZIF-8 and modified MgAl-LDH were added to the fourth mixed solution in sequence under stirring and stirred evenly at a stirring speed of 500 rpm and a stirring temperature of 50°C. After stirring for 0.8 h, ultrasonic treatment was performed at an ultrasonic frequency of 45 kHz for 0.8 h to obtain a fifth mixed solution. S33. Proline and citric acid were added to the fifth mixed solution under stirring and stirred for 0.8h, while the pH value was controlled at 7.0 with phosphate buffered saline, followed by the addition of gibberellins, and stirring was continued for 0.8h to obtain a sixth mixed solution; S34. Slowly add the Bacillus subtilis solution to the sixth mixed solution under low-speed stirring, control the stirring speed to 225 rpm, continue stirring at room temperature for 15 minutes, and then filter through a 0.22 μm filter membrane to obtain the drought-resistant and salt-alkali-resistant corn seed coating agent.

[0026] Example 2: This example discloses a drought-resistant and salt-alkali-tolerant corn seed coating agent, comprising the following raw materials in parts by weight: 15 parts of nano-polyacrylamide, 7.5 parts of polyvinyl alcohol, 20 parts of modified MgAl-LDH, 0.6 parts of gibberellin, 0.3 parts of proline, 2 parts of citric acid, 15 parts of sodium carboxymethyl cellulose, 8 parts of Bacillus subtilis, and 55 parts of purified water. The drought-resistant and salt-alkali-tolerant corn seed coating agent also includes Mo@ZIF-8, and the weight ratio of Mo@ZIF-8 to modified MgAl-LDH is 5:20. The nanometer size of Mo@ZIF-8 is 115 nm, and the specific surface area is 1335 m 2 / g.

[0027] The preparation method of Mo@ZIF-8 comprises: S11. Dissolve zinc nitrate in methanol under nitrogen protection and stirring to obtain a zinc nitrate solution, then dissolve 2-methylimidazole and ammonium molybdate in methanol and stir for 1 hour, then slowly add the zinc nitrate solution, raise the temperature to 35° C., continue stirring and react for 24 hours, and control the pH value to 10.5 with aqueous ammonia, and stand for 15 hours to obtain a first mixed solution; S12. The first mixed solution was subjected to high-speed centrifugation at a speed of 8000 rpm for 10 min. The separated solid was washed alternately with methanol and purified water for 3 times and then vacuum dried at a drying temperature of 135° C. After drying for 6 h, Mo@ZIF-8 was obtained and ground into powder for later use.

[0028] The molar ratio of the zinc nitrate, 2-methylimidazole and ammonium molybdate is 1:8:0.02.

[0029] The preparation method of the modified MgAl-LDH comprises: S21. Dissolve magnesium nitrate and aluminum nitrate in purified water under stirring, and control Mg 2+ and Al 3+ The molar ratio of is 3:1, and a 0.2 mol / L metal ion mixed solution is prepared; S22. Slowly add 1 mol / L sodium hydroxide solution to the metal ion mixed solution under nitrogen protection and stirring until the pH value rises to 9.5, and raise the temperature to 65° C., continue stirring and reacting for 4 hours, and then stand for 12 hours to obtain a second mixed solution; S23. The second mixed solution was separated by vacuum filtration, and the separated precipitate was washed three times with purified water and then vacuum dried at a drying temperature of 55 ° C. After drying for 12 h, MgAl-LDH was obtained and ground into a powder for later use; S24. Dissolve dopamine hydrochloride in phosphate buffered saline under nitrogen protection and stirring, slowly add MgAl-LDH powder after stirring for 0.5 h, raise the temperature to 35° C., and control the pH value to 8.5 with 0.1 mol / L sodium hydroxide solution, and continue stirring for 14 h to obtain a third mixed solution; S25. The third mixed solution was subjected to high-speed centrifugation at a speed of 8000 rpm for 10 min. The separated solid was washed three times with purified water and then vacuum dried at a drying temperature of 65° C. After drying for 12 h, the modified MgAl-LDH was obtained and ground into powder for later use.

[0030] The nanometer size of the modified MgAl-LDH is 110 nm and the specific surface area is 135 m 2 / g.

[0031] The mass ratio of the MgAl-LDH to dopamine hydrochloride is 1:0.1.

[0032] A method for preparing a drought-resistant and salt-alkali-tolerant corn seed coating agent, which is applied to the drought-resistant and salt-alkali-tolerant corn seed coating agent, comprises the following steps: S31. Add polyvinyl alcohol to purified water in a container and stir well, while heating to 75~85°C, stirring for 1~2h and then cooling to 30~40°C, then adding sodium carboxymethyl cellulose and stirring for 1~2h, controlling the stirring speed to 300~400 rpm, cooling to room temperature, and stirring at room temperature for 0.5~1h to obtain a fourth mixed solution; S32. Nano-polyacrylamide, Mo@ZIF-8 and modified MgAl-LDH were added to the fourth mixed solution in sequence under stirring and stirred evenly at a stirring speed of 400 rpm and a stirring temperature of 45°C. After stirring for 0.5 h, ultrasonic treatment was performed at a frequency of 40 kHz for 0.5 h to obtain a fifth mixed solution. S33. Proline and citric acid were added to the fifth mixed solution under stirring and stirred for 0.5h, while the pH value was controlled at 6.5 with phosphate buffered saline, followed by the addition of gibberellins, and stirring was continued for 0.5h to obtain a sixth mixed solution; S34. Slowly add the Bacillus subtilis solution to the sixth mixed solution under low-speed stirring, control the stirring speed to 200 rpm, continue stirring at room temperature for 10 minutes, and then filter through a 0.22 μm filter membrane to obtain the drought-resistant and salt-alkali-resistant corn seed coating agent.

[0033] Example 3: This example discloses a drought-resistant and salt-alkali-tolerant corn seed coating agent, comprising the following raw materials in parts by weight: 15 parts of nano-polyacrylamide, 7.5 parts of polyvinyl alcohol, 20 parts of modified MgAl-LDH, 0.6 parts of gibberellin, 0.3 parts of proline, 2 parts of citric acid, 15 parts of sodium carboxymethyl cellulose, 8 parts of Bacillus subtilis, and 55 parts of purified water. The drought-resistant and salt-alkali-tolerant corn seed coating agent also includes Mo@ZIF-8, and the weight ratio of Mo@ZIF-8 to modified MgAl-LDH is 5:20. The nanometer size of Mo@ZIF-8 is 120 nm, and the specific surface area is 1300 m 2 / g.

[0034] The preparation method of Mo@ZIF-8 comprises: S11. Dissolve zinc nitrate in methanol under nitrogen protection and stirring to obtain a zinc nitrate solution, then dissolve 2-methylimidazole and ammonium molybdate in methanol and stir for 2 hours, then slowly add the zinc nitrate solution, raise the temperature to 45°C, continue stirring and react for 26 hours, and control the pH value to 11 with aqueous ammonia, and stand for 18 hours to obtain a first mixed solution; S12. The first mixed solution was subjected to high-speed centrifugation at a speed of 10,000 rpm for 15 min. The separated solid was washed alternately with methanol and purified water for 3 times and then vacuum dried at a drying temperature of 145° C. After drying for 8 h, Mo@ZIF-8 was obtained and ground into powder for later use.

[0035] The molar ratio of the zinc nitrate, 2-methylimidazole and ammonium molybdate is 1:10:0.04.

[0036] The preparation method of the modified MgAl-LDH comprises: S21. Dissolve magnesium nitrate and aluminum nitrate in purified water under stirring, and control Mg 2+ and Al 3+ The molar ratio of is 3:1, and a 0.2 mol / L metal ion mixed solution is prepared; S22. Slowly add 1 mol / L sodium hydroxide solution to the metal ion mixed solution under nitrogen protection and stirring until the pH value rises to 10.5, and raise the temperature to 75° C., continue stirring and reacting for 6 hours, and then stand for 15 hours to obtain a second mixed solution; S23. The second mixed solution was separated by vacuum filtration, and the separated precipitate was washed three times with purified water and then vacuum dried at a drying temperature of 65 ° C. After drying for 15 h, MgAl-LDH was obtained and ground into a powder for later use; S24. Dissolve dopamine hydrochloride in phosphate buffered saline under nitrogen protection and stirring, slowly add MgAl-LDH powder after stirring for 1 hour, raise the temperature to 45°C, and control the pH value to 9 with 0.1 mol / L sodium hydroxide solution, and continue stirring for 16 hours to obtain a third mixed solution; S25. The third mixed solution was subjected to high-speed centrifugation at a speed of 10,000 rpm for 15 min. The separated solid was washed three times with purified water and then vacuum dried at a drying temperature of 75° C. After drying for 15 h, the modified MgAl-LDH was obtained and ground into powder for later use.

[0037] The nanometer size of the modified MgAl-LDH is 118 nm and the specific surface area is 125 m 2 / g.

[0038] The mass ratio of the MgAl-LDH to dopamine hydrochloride is 1:0.3.

[0039] A method for preparing a drought-resistant and salt-alkali-tolerant corn seed coating agent, which is applied to the drought-resistant and salt-alkali-tolerant corn seed coating agent, comprises the following steps: S31. Add polyvinyl alcohol to purified water in a container and stir well, while heating to 75~85°C, stirring for 1~2h and then cooling to 30~40°C, then adding sodium carboxymethyl cellulose and stirring for 1~2h, controlling the stirring speed to 300~400 rpm, cooling to room temperature, and stirring at room temperature for 0.5~1h to obtain a fourth mixed solution; S32. Nano-polyacrylamide, Mo@ZIF-8 and modified MgAl-LDH were added to the fourth mixed solution in sequence under stirring and stirred evenly at a stirring speed of 600 rpm and a stirring temperature of 55°C. After stirring for 1 hour, ultrasonic treatment was performed at an ultrasonic frequency of 50 kHz. After 1 hour of ultrasonic treatment, a fifth mixed solution was obtained. S33. Proline and citric acid were added to the fifth mixed solution under stirring and stirred for 1h, while the pH value was controlled at 7.5 with phosphate buffered saline, followed by the addition of gibberellin, and stirring was continued for 1h to obtain a sixth mixed solution; S34. Slowly add the Bacillus subtilis solution to the sixth mixed solution under low-speed stirring, control the stirring speed to 250 rpm, continue stirring at room temperature for 20 minutes, and then filter through a 0.22 μm filter membrane to obtain the drought-resistant and salt-alkali-resistant corn seed coating agent.

[0040] Example 4: This example discloses a drought-resistant and salt-alkali-tolerant corn seed coating agent, comprising the following raw materials in parts by weight: 10 parts of nano-polyacrylamide, 5 parts of polyvinyl alcohol, 15 parts of modified MgAl-LDH, 0.2 parts of gibberellin, 0.1 parts of proline, 1 part of citric acid, 10 parts of sodium carboxymethyl cellulose, 6 parts of Bacillus subtilis, and 50 parts of purified water. The drought-resistant and salt-alkali-tolerant corn seed coating agent also includes Mo@ZIF-8, and the weight ratio of Mo@ZIF-8 to modified MgAl-LDH is 5:15. The nanometer size of Mo@ZIF-8 is 90 nm, and the specific surface area is 1380 m 2 / g. The preparation methods of Mo@ZIF-8 and modified MgAl-LDH in this embodiment are consistent with those in Example 1. The preparation method of a drought-resistant and salt-alkali-tolerant corn seed coating agent in this embodiment is consistent with that in Example 1.

[0041] Example 5: This example discloses a drought-resistant and salt-alkali-tolerant corn seed coating agent, comprising the following raw materials in parts by weight: 10 parts of nano-polyacrylamide, 5 parts of polyvinyl alcohol, 15 parts of modified MgAl-LDH, 0.2 parts of gibberellin, 0.1 parts of proline, 1 part of citric acid, 10 parts of sodium carboxymethyl cellulose, 6 parts of Bacillus subtilis, and 50 parts of purified water. The drought-resistant and salt-alkali-tolerant corn seed coating agent also includes Mo@ZIF-8, and the weight ratio of Mo@ZIF-8 to modified MgAl-LDH is 5:15. The nanometer size of Mo@ZIF-8 is 115 nm, and the specific surface area is 1335 m 2 / g. The preparation methods of Mo@ZIF-8 and modified MgAl-LDH in this embodiment are consistent with those in Example 2. The preparation method of a drought-resistant and salt-alkali-tolerant corn seed coating agent in this embodiment is consistent with that in Example 2.

[0042] Example 6: This example discloses a drought-resistant and salt-alkali-tolerant corn seed coating agent, comprising the following raw materials in parts by weight: 10 parts of nano-polyacrylamide, 5 parts of polyvinyl alcohol, 15 parts of modified MgAl-LDH, 0.2 parts of gibberellin, 0.1 parts of proline, 1 part of citric acid, 10 parts of sodium carboxymethyl cellulose, 6 parts of Bacillus subtilis, and 50 parts of purified water. The drought-resistant and salt-alkali-tolerant corn seed coating agent also includes Mo@ZIF-8, and the weight ratio of Mo@ZIF-8 to modified MgAl-LDH is 5:15. The nanometer size of Mo@ZIF-8 is 120 nm, and the specific surface area is 1300 m 2 / g. The preparation methods of Mo@ZIF-8 and modified MgAl-LDH in this embodiment are consistent with those in Example 3. The preparation method of a drought-resistant and salt-alkali-tolerant corn seed coating agent in this embodiment is consistent with that in Example 3.

[0043] Example 7: This example discloses a drought-resistant and salt-alkali-tolerant corn seed coating agent, comprising the following raw materials in parts by weight: 20 parts of nano-polyacrylamide, 10 parts of polyvinyl alcohol, 25 parts of modified MgAl-LDH, 1 part of gibberellin, 0.5 parts of proline, 3 parts of citric acid, 20 parts of sodium carboxymethyl cellulose, 10 parts of Bacillus subtilis, and 60 parts of purified water. The drought-resistant and salt-alkali-tolerant corn seed coating agent also includes Mo@ZIF-8, and the weight ratio of Mo@ZIF-8 to modified MgAl-LDH is 5:25. The nanometer size of Mo@ZIF-8 is 90 nm, and the specific surface area is 1380 m 2 / g. The preparation methods of Mo@ZIF-8 and modified MgAl-LDH in this embodiment are consistent with those in Example 1. The preparation method of a drought-resistant and salt-alkali-tolerant corn seed coating agent in this embodiment is consistent with that in Example 1.

[0044] Example 8: This example discloses a drought-resistant and salt-alkali-tolerant corn seed coating agent, comprising the following raw materials in parts by weight: 20 parts of nano-polyacrylamide, 10 parts of polyvinyl alcohol, 25 parts of modified MgAl-LDH, 1 part of gibberellin, 0.5 parts of proline, 3 parts of citric acid, 20 parts of sodium carboxymethyl cellulose, 10 parts of Bacillus subtilis, and 60 parts of purified water. The drought-resistant and salt-alkali-tolerant corn seed coating agent also includes Mo@ZIF-8, and the weight ratio of Mo@ZIF-8 to modified MgAl-LDH is 5:25. The nanometer size of Mo@ZIF-8 is 115 nm, and the specific surface area is 1335 m 2 / g. The preparation methods of Mo@ZIF-8 and modified MgAl-LDH in this embodiment are consistent with those in Example 2. The preparation method of a drought-resistant and salt-alkali-tolerant corn seed coating agent in this embodiment is consistent with that in Example 2.

[0045] Example 9: This example discloses a drought-resistant and salt-alkali-tolerant corn seed coating agent, comprising the following raw materials in parts by weight: 20 parts of nano-polyacrylamide, 10 parts of polyvinyl alcohol, 25 parts of modified MgAl-LDH, 1 part of gibberellin, 0.5 parts of proline, 3 parts of citric acid, 20 parts of sodium carboxymethyl cellulose, 10 parts of Bacillus subtilis, and 60 parts of purified water. The drought-resistant and salt-alkali-tolerant corn seed coating agent also includes Mo@ZIF-8, and the weight ratio of Mo@ZIF-8 to modified MgAl-LDH is 5:25. The nanometer size of Mo@ZIF-8 is 120 nm, and the specific surface area is 1300 m 2 / g. The preparation methods of Mo@ZIF-8 and modified MgAl-LDH in this embodiment are consistent with those in Example 3. The preparation method of a drought-resistant and salt-alkali-tolerant corn seed coating agent in this embodiment is consistent with that in Example 3.

[0046] Control group 1: This embodiment differs from embodiment 1 in that Mo@ZIF-8 is not contained. This embodiment discloses a drought-resistant and salt-alkali-tolerant corn seed coating agent, comprising the following raw materials in parts by weight: 15 parts of nano-polyacrylamide, 7.5 parts of polyvinyl alcohol, 20 parts of modified MgAl-LDH, 0.6 parts of gibberellin, 0.3 parts of proline, 2 parts of citric acid, 15 parts of sodium carboxymethyl cellulose, 8 parts of Bacillus subtilis, and 55 parts of purified water. The preparation method of the modified MgAl-LDH in this embodiment is consistent with that in embodiment 1. The preparation method of a drought-resistant and salt-alkali-tolerant corn seed coating agent in this embodiment is consistent with that in embodiment 1.

[0047] Control group 2: The difference between this embodiment and embodiment 1 is that modified MgAl-LDH is not contained. This embodiment discloses a drought-resistant and salt-alkali-tolerant corn seed coating agent, comprising the following raw materials in parts by weight: 15 parts of nano-polyacrylamide, 7.5 parts of polyvinyl alcohol, 0.6 parts of gibberellin, 0.3 parts of proline, 2 parts of citric acid, 15 parts of sodium carboxymethyl cellulose, 8 parts of Bacillus subtilis, and 55 parts of purified water. The drought-resistant and salt-alkali-tolerant corn seed coating agent also includes Mo@ZIF-8, and the Mo@ZIF-8 is parts, and the nano size of the Mo@ZIF-8 is 90 nm and the specific surface area is 1380 m 2 / g. The preparation method of Mo@ZIF-8 in this embodiment is consistent with that in Example 1. The preparation method of a drought-resistant and salt-alkali-tolerant corn seed coating agent in this embodiment is consistent with that in Example 1.

[0048] Control group 3: This embodiment differs from embodiment 1 in that it does not contain Mo@ZIF-8 and modified MgAl-LDH. This embodiment discloses a drought-resistant and salt-alkali-tolerant corn seed coating agent, comprising the following raw materials in parts by weight: 15 parts of nano-polyacrylamide, 7.5 parts of polyvinyl alcohol, 0.6 parts of gibberellin, 0.3 parts of proline, 2 parts of citric acid, 15 parts of sodium carboxymethyl cellulose, 8 parts of Bacillus subtilis, and 55 parts of purified water. The preparation method of a drought-resistant and salt-alkali-tolerant corn seed coating agent in this embodiment is consistent with that in embodiment 1.

[0049] Effect evaluation: Corn seedling growth experiment: Select mature and healthy corn seeds, and coat and dry them according to the method of use of the corn seed coating agent. The blank group does not undergo coating treatment. Set up 13 seedling trays, fill the seedling trays with an equal amount of sterilized soil, and the number of corn seeds in each experimental group is 30, the seed spacing is 3 cm, and the soil thickness is 2 cm. During the cultivation process, a unified irrigation and topdressing system is adopted to ensure that the other planting and management conditions are completely consistent. After 7 days of cultivation, the plant height and root length are measured with a ruler, the chlorophyll content is measured using a SPAD instrument, and the leaf area is measured using a leaf area meter. All values ​​are recorded as the average value of each experimental group and are statistically shown in Table 1.

[0050]

[0051] Table 1 shows the statistical results of corn seed growth in each experimental group. Plant height is an important indicator for measuring crop growth, reflecting the overall growth potential and growth rate of the crop; root length reflects the development status and growth ability of the crop root system. A longer root system usually means that the crop has a better ability to absorb water and nutrients; chlorophyll content is a direct reflection of the crop's photosynthetic capacity. A high chlorophyll content usually means that the crop has a high photosynthetic efficiency and can produce nutrients more effectively; leaf area reflects the crop's photosynthetic potential. Crops with a larger leaf area usually have a stronger photosynthetic capacity and can synthesize more organic matter. As can be seen from Table 1, there are obvious differences in the growth of corn seeds in each experimental group. The growth index values ​​of the corn seeds in the blank group are the lowest. By comparing the growth of corn seeds in Example 1, Example 2 and Example 3, it can be found that different preparation conditions also have a certain effect on the growth of corn seeds. By comparing the growth of corn seeds in Example 1, Example 4 and Example 7 with the growth of corn seeds in the control group 1 to 3, it can be found that, overall, the growth of corn seeds in Example 1, Example 4 and Example 7 is better, among which the growth of corn seeds in Example 1 is the best, with a plant height of 12.7 cm, a root length of 11.2 cm, a chlorophyll content of 34.6, and a leaf area of ​​28.5 cm 2 When Mo@ZIF-8 and modified MgAl-LDH are added simultaneously in the preparation of drought-resistant and salt-alkali-tolerant corn seed coating agent, the nutrients provided by the seed coating agent can effectively promote the growth of seedlings.

[0052] Salt-alkali drought stress experiment: Preparation of salt-alkali solution: Use purified water to prepare a salt-alkali mixed solution with a concentration of 100mM NaCl+50mM NaHCO3. Select mature and healthy corn seeds, and coat and dry them according to the method of use of the corn seed coating agent. The blank group does not undergo coating treatment. Thirteen seedling trays were set up and filled with an equal amount of sterilized soil. The soil moisture content was controlled at about 30%. The number of corn seeds in each experimental group was 30, the seed spacing was 3 cm, and the soil thickness was 2 cm. At the beginning of cultivation, the saline-alkali mixed solution was evenly sprayed on the seedling tray to simulate the saline-alkali environment. The spraying amount was 10 mL and it was sprayed once every 7 days. During the cultivation process, all experimental groups were not watered to simulate soil drought conditions, ensuring that the other planting and management conditions were completely consistent. This lasted for 21 days. The plant height was measured with a ruler on the 7th, 14th, and 21st days. After the experiment, the root length of the seedlings was measured with a ruler. The chlorophyll content was measured using a SPAD instrument, and the leaf area was measured using a leaf area meter. All values ​​were recorded as the average value of each experimental group and statistically reported in Table 2.

[0053]

[0054] Table 2 shows the statistical results of corn seed growth in each experimental group under saline-alkali drought stress. It can be seen from Table 2 that under saline-alkali drought stress, the growth of corn seeds in the blank group was poor, and was obviously affected. , The stress of ions was affected. The plant height of corn seedlings in each experimental group on the 7th day was compared with the plant height of corn seedlings in the corn seedling growth experiment. The plant height values ​​showed a decreasing trend, but they were still at a relatively high level. After the experiment, the growth of corn seeds in Example 1, Example 4 and Example 7 was compared with that in the control group 1-3. It can be found that the growth of corn seeds in Example 1, Example 4 and Example 7 was better than that in the control group 1-3. Among them, the growth of corn seeds in Example 1 was the best, with a plant height of 19.5 cm, a root length of 10.8 cm, a chlorophyll content of 26.6, and a leaf area of ​​33.5 cm 2 Therefore, the drought-resistant and salt-alkali-tolerant corn seed coating agent prepared in Example 1 was used to coat corn seeds, and the corn seeds showed excellent drought resistance and salt-alkali resistance.

[0055] Through the above limited experiments, the application effect of a drought-resistant and salt-alkali-tolerant corn seed coating agent of Example 1 of the present invention is significant. By optimizing the formula of the corn seed coating agent and combining modern nanotechnology to add Mo@ZIF-8 and modified MgAl-LDH during the production process, the two synergistically improve the drought resistance and salt-alkali resistance of corn seeds, ensure the water absorption and germination of seeds in a drought environment, reduce the inhibition of seed germination by salt-alkali stress, increase the seed germination rate, promote seedling growth, enhance stress resistance, and provide effective guarantee for the stable growth and high yield of corn in drought and salt-alkali stress environments.

[0056] Finally, it should be noted that: Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A drought-resistant and salt-alkali-tolerant corn seed coating agent, characterized in that: The invention comprises the following raw materials in parts by weight: 10-20 parts of nano-polyacrylamide, 5-10 parts of polyvinyl alcohol, 15-25 parts of modified MgAl-LDH, 0.2-1 parts of gibberellin, 0.1-0.5 parts of proline, 1-3 parts of citric acid, 10-20 parts of sodium carboxymethyl cellulose, 6-10 parts of Bacillus subtilis, and 50-60 parts of purified water; The drought-resistant and salt-alkali-tolerant corn seed coating agent also includes: Mo@ZIF-8; The weight ratio of Mo@ZIF-8 to modified MgAl-LDH is 5:(15-25); The nanometer size of Mo@ZIF-8 is 85-125 nm, and the specific surface area is 1300-1400 m 2 / g.

2. The drought-resistant and salt-alkali-tolerant corn seed coating agent according to claim 1, characterized in that: The preparation method of Mo@ZIF-8 comprises: S11. Under nitrogen protection and stirring, zinc nitrate is dissolved in methanol to obtain a zinc nitrate solution, and 2-methylimidazole and ammonium molybdate are dissolved in methanol together and stirred for 1-2 hours, and then the zinc nitrate solution is slowly added, and the temperature is raised to 35-45°C, and the stirring reaction is continued for 24-26 hours, and the pH value is controlled to 10.5-11 with ammonia water, and the first mixed solution is obtained after standing for 15-18 hours; S12. The first mixed solution is subjected to high-speed centrifugation at a speed of 8000-10000 rpm for 10-15 min. The separated solid is washed alternately with methanol and purified water for 3 times and then vacuum dried at a drying temperature of 135-145° C. After drying for 6-8 h, Mo@ZIF-8 is obtained and ground into powder for later use.

3. The drought-resistant and salt-alkali-tolerant corn seed coating agent according to claim 2, characterized in that: The molar ratio of the zinc nitrate, 2-methylimidazole and ammonium molybdate is 1:(8-10):(0.02-0.04).

4. The drought-resistant and salt-alkali-tolerant corn seed coating agent according to claim 1, characterized in that: The preparation method of the modified MgAl-LDH comprises: S21. Dissolve magnesium nitrate and aluminum nitrate in purified water under stirring, and control Mg 2+ and Al 3+ The molar ratio of is 3:1, and a 0.2 mol / L metal ion mixed solution is prepared; S22. Slowly add 1 mol / L sodium hydroxide solution to the metal ion mixed solution under nitrogen protection and stirring until the pH value rises to 9.5-10.5, and raise the temperature to 65-75°C, continue stirring and reacting for 4-6 hours, and then stand for 12-15 hours to obtain a second mixed solution; S23. The second mixed solution was separated by vacuum filtration, and the separated precipitate was washed three times with purified water and then vacuum dried at a drying temperature of 55 to 65 ° C. After drying for 12 to 15 hours, MgAl-LDH was obtained and ground into a powder for later use; S24. Dissolve dopamine hydrochloride in phosphate buffered saline under nitrogen protection and stirring, slowly add MgAl-LDH powder after stirring for 0.5-1h, raise the temperature to 35-45°C, and control the pH value to 8.5-9 with 0.1 mol / L sodium hydroxide solution, continue stirring for 14-16h to obtain a third mixed solution; S25. The third mixed solution is subjected to high-speed centrifugation at a speed of 8000-10000 rpm for 10-15 min. The separated solid is washed three times with purified water and then vacuum dried at a drying temperature of 65-75° C. After drying for 12-15 h, the modified MgAl-LDH is obtained and ground into powder for later use.

5. The drought-resistant and salt-alkali-tolerant corn seed coating agent according to claim 4, characterized in that: The nanometer size of the modified MgAl-LDH is 100-120 nm, and the specific surface area is 120-150 m 2 / g.

6. The drought-resistant and salt-alkali-tolerant corn seed coating agent according to claim 4, characterized in that: The mass ratio of the MgAl-LDH to dopamine hydrochloride is 1:(0.1-0.3).

7. A method for preparing a drought-resistant and salt-alkali-tolerant corn seed coating agent, which is used to prepare the drought-resistant and salt-alkali-tolerant corn seed coating agent as claimed in any one of claims 1 to 6, characterized in that: The method comprises the following steps: S31. Add polyvinyl alcohol to purified water in a container and stir well, while heating to 75~85°C, stirring for 1~2h and then cooling to 30~40°C, then adding sodium carboxymethyl cellulose and stirring for 1~2h, controlling the stirring speed to 300~400rpm, cooling to room temperature, and stirring at room temperature for 0.5~1h to obtain a fourth mixed solution; S32. Nano-polyacrylamide, Mo@ZIF-8 and modified MgAl-LDH were added to the fourth mixed solution in sequence under stirring, and the mixture was stirred evenly at a stirring speed of 400-600 rpm and a stirring temperature of 45-55° C. After stirring for 0.5-1 h, ultrasonic treatment was performed at a frequency of 40-50 kHz for 0.5-1 h to obtain a fifth mixed solution; S33. Proline and citric acid were added to the fifth mixed solution under stirring and stirred for 0.5 to 1 h, while the pH value was controlled at 6.5 to 7.5 with phosphate buffered saline, followed by the addition of gibberellin, and stirring was continued for 0.5 to 1 h to obtain a sixth mixed solution; S34. Slowly add the Bacillus subtilis solution to the sixth mixed solution under low-speed stirring, control the stirring speed to 200-250 rpm, continue stirring at room temperature for 10-20 minutes, and then filter through a 0.22 μm filter membrane to obtain the drought-resistant and salt-alkali-resistant corn seed coating agent.

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