A rare earth coating agent for establishing alfalfa in suoda saline land and a preparation method thereof

Abstract

This application belongs to the field of seed treatment technology and provides a rare earth coating agent for establishing alfalfa in Soda saline-alkali land and its preparation method. The coating agent is a cerium nitrate solution containing a film-forming agent, emulsifier, dispersant, defoamer, and wetting agent. The coating agent of this application can significantly overcome the ion toxicity and high pH stress in Soda saline-alkali land after seed coating, improve the germination rate and emergence rate of alfalfa in Soda saline-alkali land, increase plant height and root length, enhance the activity of antioxidant enzymes in the plant, and improve the establishment efficiency of alfalfa in Soda saline-alkali land.

Description

Technical Field

[0001] This application belongs to the field of seed treatment technology. Specifically, this application provides a rare earth coating agent for the establishment of alfalfa in saline-alkali land and its preparation method. Background Technology

[0002] Soil salinization is a pressing problem in global agricultural production and environmental protection. It is a common abiotic stress faced by crops during growth, severely impacting their growth and development. Saline land can be divided into saline soil and alkaline soil. Saline soil generally refers to soil with a relatively high content of neutral salts, ranging from 0.1% to 0.3%, and a pH value generally not exceeding 8.0. Alkaline soil shares most characteristics with saline soil, but a key difference is the presence of higher levels of alkaline salts, Na₂CO₃ and NaHCO₃, with an alkalinity exceeding 15%. It also contains a high amount of exchangeable sodium in its colloids, exhibiting a strongly alkaline reaction, with a pH often greater than 8.5. Stress caused by neutral salts is typically referred to as salt stress, while stress caused by alkaline salts is called soda stress or alkali stress.

[0003] Alfalfa (Medicago sativa L.) is an important perennial leguminous forage crop, known as the "King of Forages" due to its high yield, high quality, and tolerance to cutting. It plays a vital role in ensuring the sustainable development of agriculture and animal husbandry in my country. Currently, the alfalfa planting area in my country is approximately 3.77 × 10⁻⁶. 6 hm 2 Alfalfa is the most widely planted forage grass and the preferred crop for improving saline-alkali land under the "grain-to-feed" policy in arid and semi-arid regions of northern my country. The germination period is the most vulnerable and stress-sensitive stage in the alfalfa life cycle. The main difficulties in establishing alfalfa in saline-alkali land are low seed germination rates and poor seedling growth. Salt-alkali stress significantly inhibits alfalfa seed germination. Different types of salt-alkali stress have varying degrees of damage to alfalfa's physiological metabolism; alkali stress has a significantly greater inhibitory effect than salt stress, and it also has a greater inhibitory and damaging effect on alfalfa root growth. Alfalfa is a relatively alkali-tolerant species and can survive in soil environments with a pH < 8.5, but excessively high concentrations of alkali stress will still significantly inhibit its seed germination and seedling growth.

[0004] Seed coating is a seed processing technology that involves uniformly coating the surface of seeds with special functional agents to promote seed germination and enhance seed resistance. It is characterized by low cost, rapid effect, and good efficacy. Currently, various forage seed coating agents are available on the market, but their ingredients are mostly concentrated in chemical fertilizers, insecticides, fungicides, or single growth promoters, posing risks of environmental pollution and potential negative impacts on soil microecology. Furthermore, their effects on promoting alfalfa seed germination and seedling growth are limited, especially lacking a coating formula specifically designed for alfalfa seeds under alkaline stress. Therefore, developing a low-cost, environmentally friendly, synergistically formulated seed coating agent that can significantly improve the germination rate and seedling growth of alfalfa seeds in soda soils is of great significance for promoting alfalfa cultivation in soda saline-alkali lands. Summary of the Invention

[0005] On the one hand, this application provides a coating agent for establishing alfalfa in saline-alkali land, wherein the coating agent is a cerium nitrate solution containing a film-forming agent, an emulsifier, a dispersant, an antifoaming agent, and a wetting agent.

[0006] Cerium nitrate is the active ingredient in the coating agent.

[0007] Furthermore, the concentration of the cerium nitrate solution is 300-500 μM.

[0008] Furthermore, the concentration of the cerium nitrate solution is 400-500 μM.

[0009] Furthermore, the coating agent contains 1.5-2.5 w / v% of a film-forming agent, 0.2-0.4 w / v% of an emulsifier, 0.05-0.15 w / v% of a dispersant, 0.04-0.06 w / v% of an antifoamer, and 0.1-0.3 w / v% of a wetting agent.

[0010] Further, the film-forming agent is polyvinyl alcohol, and / or the emulsifier is OP-10, the dispersant is sodium methylene dimethylnaphthalene sulfonate, the defoamer is NXZ, and the wetting agent is PE-100.

[0011] Furthermore, the coating agent also includes a colorant.

[0012] Preferably, the coating agent preparation process includes: dissolving cerium nitrate in distilled water; sequentially adding a film-forming agent, emulsifier, dispersant, defoamer, wetting agent, thickener, and colorant to the cerium nitrate aqueous solution, and ultrasonically vibrating (e.g., for 30 minutes).

[0013] On the other hand, this application provides a method for improving the salt and alkali stress tolerance of plants, wherein the above-mentioned coating agent is used to coat plant seeds.

[0014] Furthermore, the plant is a plant of the genus *Alfalfa*, preferably *Alfalfa purpurea*.

[0015] Furthermore, the method uses the aforementioned coating agent to perform suspension coating on plant seeds.

[0016] Preferably, suspension coating is performed using a coating machine at a speed of 600-800 r / min (e.g., 700 r / min); or other spraying methods are used; the weight-to-volume ratio of plant seeds and coating agent is 1:1-2 (e.g., 1:1.5).

[0017] Furthermore, in the method, the above-mentioned coating agent is used to perform suspension coating on plant seeds before pelleting coating.

[0018] Granulation coating involves pouring the suspended coated alfalfa seeds into a drum. The drum speed is adjusted to 600-650 rpm to ensure uniform rolling of the seeds within the drum, allowing for thorough contact between the filler, binder, and seeds. The atomizing disc is fixed in place, and a small amount of binder is added to the disc to moisten the seed surface and prevent seed sticking. The speed is slightly reduced, filler is added, and as the seeds resume uniform rolling, small amounts of binder are added again. This process is repeated until all filler is added. During the coating process, binder and filler should be added alternately, following the principle of adding small amounts multiple times.

[0019] Preferably, the binder used in the pelleting coating is a 1.5% sodium carboxymethyl cellulose aqueous solution; the three coating materials, from the innermost layer to the outermost layer, are: superabsorbent resin and talc in a mass ratio of 1:1, magnesium stearate, sodium bentonite and talc in a mass ratio of 1:1:2, and talc.

[0020] Furthermore, the improvement of plant tolerance to salt and alkali stress includes one or more of the following effects:

[0021] (1) Improve the germination potential and germination rate of plants under salt and alkali stress;

[0022] (2) Increase plant height, root length and antioxidant enzyme activity in plants under salt stress.

[0023] The coating agent provided by this invention, used for suspension or pelleting coating of alfalfa seeds, can significantly improve the seedling establishment rate of alfalfa in saline-alkali soil. The cost of cerium nitrate per 1 kg of coated alfalfa seeds is only 1.57 yuan, with a total cost not exceeding 10 yuan. Using the coating agent provided by this invention for soaking, suspension coating, and pelleting of alfalfa seeds can significantly overcome the ion toxicity and high pH stress under soda saline-alkali stress (NaCl:NaHCO3 molar ratio 1:1, pH=8.5), improving the germination and emergence rates of alfalfa in soda saline-alkali soil, increasing plant height and root length, enhancing the activity of antioxidant enzymes in the plant, and improving the establishment efficiency of alfalfa in soda saline-alkali soil. Attached Figure Description

[0024] Figure 1The phenotype of "Xinmu No. 4" seedlings under different intensities of alkali stress is shown.

[0025] Figure 2A Displays 80 mM Na + Phenotypic results of “Xinmu No. 4” seedlings treated with different concentrations of Ce(NO3)3 under salt-alkali stress at pH=8.5.

[0026] Figure 2B Displays 90 mM Na + Phenotypic results of “Xinmu No. 4” seedlings treated with different concentrations of Ce(NO3)3 under salt-alkali stress at pH=8.5.

[0027] Figure 2C Displays 100 mM Na + Phenotypic results of “Xinmu No. 4” seedlings treated with different concentrations of Ce(NO3)3 under salt-alkali stress at pH=8.5.

[0028] Figure 2D Displays 80 mM Na + Phenotypes of “Xinmu No. 4” seedlings treated with different concentrations of KNO3 under salt-alkali stress at pH=8.5.

[0029] Figure 2E shows 90 mM Na + Phenotypes of “Xinmu No. 4” seedlings treated with different concentrations of KNO3 under salt-alkali stress at pH=8.5.

[0030] Figure 3 Showing examples of suspension coating and pellet coating.

[0031] Figure 4A This shows the emergence of "Xinmu No. 4" seedlings treated with different concentrations of Ce(NO3)3 suspension coating under mild (2‰, w / w) saline-alkali stress.

[0032] Figure 4B This shows the emergence of "Xinmu No. 4" seedlings treated with different concentrations of Ce(NO3)3 pelleting coating under mild (2‰, w / w) saline-alkali stress.

[0033] Figure 4C This study shows the germination potential and emergence rate of "Xinmu No. 4" seedlings under two coating treatments with different concentrations of Ce(NO3)3 under mild (2‰, w / w) saline-alkali stress.

[0034] Figure 4D The phenotypes of “Xinmu No. 4” seedlings treated with different concentrations of Ce(NO3)3 suspension coating under mild (2‰, w / w) salt-alkali stress are shown.

[0035] Figure 4E The phenotypes of "Xinmu No. 4" seedlings treated with different concentrations of Ce(NO3)3 pelleting coating under mild (2‰, w / w) salt-alkali stress are shown.

[0036] Figure 4F The plant height of “Xinmu No. 4” seedlings under two coating treatments with different concentrations of Ce(NO3)3 under mild (2‰, w / w) saline-alkali stress is shown.

[0037] Figure 5A This shows the emergence of "Xinmu No. 4" seedlings treated with different concentrations of Ce(NO3)3 suspension coating under (4‰, w / w) salt-alkali stress.

[0038] Figure 5B This shows the emergence of "Xinmu No. 4" seedlings treated with different concentrations of Ce(NO3)3 pelleting coating under mild (4‰, w / w) saline-alkali stress.

[0039] Figure 5C This study shows the germination potential and emergence rate of "Xinmu No. 4" seedlings under two coating treatments with different concentrations of Ce(NO3)3 under mild (4‰, w / w) saline-alkali stress.

[0040] Figure 5D The phenotypes of "Xinmu 4" seedlings under mild (4‰, w / w) salt-alkali stress and two coating treatments with 400 μM Ce(NO3)3 were shown.

[0041] Figure 5E This shows the antioxidant enzyme status of "Xinmu No. 4" under two coating treatments with 400 μM Ce(NO3)3 under mild (4‰, w / w) salt-alkali stress.

[0042] Figure 5F The root length of “Xinmu No. 4” seedlings under two coating treatments with 400 μM Ce(NO3)3 under mild (4‰, w / w) salt-alkali stress is shown.

[0043] Figure 6A This shows the emergence of "Xinmu No. 4" seedlings treated with different concentrations of Ce(NO3)3 suspension coating under moderate (6‰, w / w) saline-alkali stress.

[0044] Figure 6B This shows the emergence of "Xinmu No. 4" seedlings treated with different concentrations of Ce(NO3)3 pelleting coating under moderate (6‰, w / w) saline-alkali stress.

[0045] Figure 6C This shows the germination potential and emergence rate of "Xinmu No. 4" seedlings under two coating treatments with different concentrations of Ce(NO3)3 under moderate (6‰, w / w) saline-alkali stress.

[0046] Figure 6D The phenotypes of "Xinmu No. 4" seedlings under two coating treatments with 400 μM Ce(NO3)3 under moderate (6‰, w / w) salt-alkali stress are shown.

[0047] Figure 6EThis shows the antioxidant enzyme activity of "Xinmu No. 4" under two coating treatments with 400 μM Ce(NO3)3 under moderate (6‰, w / w) salt-alkali stress.

[0048] Figure 6F The root length of “Xinmu No. 4” seedlings under two coating treatments with 400 μM Ce(NO3)3 under moderate (6‰, w / w) salt-alkali stress is shown. Detailed Implementation

[0049] Example 1: Determination of Coating Solution Formulation

[0050] A base solution was prepared containing 1.5-2.5 w / v% film-forming agent, 0.2-0.4 w / v% emulsifier, 0.05-0.15 w / v% dispersant, 0.04-0.06 w / v% defoamer, and 0.1-0.3 w / v% wetting agent. Acacia senegal, polyvinyl alcohol, methyl cellulose, and sodium carboxymethyl cellulose were selected as film-forming agents. Considering the film-forming time, film-forming properties, water solubility, and swelling ratio (as shown in Table 1), 1.5-2.5% polyvinyl alcohol was ultimately chosen as the film-forming agent for this study.

[0051] Table 1 Physical property test results of various film-forming agents

[0052]

[0053] Example 2: Tolerance of "Xinmu No. 4" under different salt and alkali stresses.

[0054] Seed disinfection

[0055] Select "Xinmu No. 4" seeds harvested that year that are plump and free from mechanical damage. Surface disinfect with a 5% sodium hypochlorite solution for 5 minutes, rinse 3-5 times with sterile water, and air dry on sterile filter paper. Vernalize in a 4℃ refrigerator for 2 days before use.

[0056] Seedling stress treatment

[0057] Based on Hoagland nutrient solution, prepare 70, 80, 90, 100, and 110 mM alkaline solutions (NaCl:NaHCO3 molar ratio 1:1, pH=8.5, Na... +The concentrations were 70, 80, 90, 100, and 110 mM. The treated seeds were evenly placed in square, transparent plastic petri dishes (90 mm on each side) lined with double-layered sterile filter paper, with 30 seeds per dish. A blank control was prepared by adding water to the petri dishes, while the other petri dishes were prepared with different concentrations of saline-alkali solution, for a total of six treatments. 6 mL of solution was added to each petri dish, and the solution was weighed. Daily evaporation was replenished with purified water. Each treatment was replicated three times. The petri dishes were placed in a light incubator under the following conditions: temperature (25 / 22±1)℃ (light / dark), 14h / 10h (light / dark), light intensity 8000 Lx, and relative humidity 60%. The incubation lasted for 10 days. Germination potential was measured on day 4, and germination rate was measured on day 10. Germination was defined as the radicle being the same length as the seed and the plumule being 50% the length of the seed.

[0058] Phenotypic analysis

[0059] like Figure 1 As shown, at pH=8.5, 70 mM Na + Salt-alkali stress did not significantly affect the germination rate of alfalfa 'Xinmu No. 4' (p > 0.05). At other Na concentrations... + Under salt-alkali stress, the germination potential and germination rate of 'Xinmu No. 4' alfalfa were significantly reduced (p < 0.01). + Under salt-alkali stress, the germination potential and germination rate of "Xinmu No. 4" alfalfa were reduced by 48.84% and 60.47% respectively compared with the control (p < 0.01). + Under salt-alkali stress, the germination potential and germination rate of "Xinmu No. 4" alfalfa decreased by 53.49% and 60.47% respectively compared with the control (p < 0.01). + Salt and 110 mM Na + Under salt-alkali stress, only a very small percentage (<5%) of alfalfa seeds germinated. (80 mM-90 mM Na) + It can be used as a screening concentration for "Xinmu No. 4" alfalfa under salt-alkali stress.

[0060] Example 2: Tolerance of “Xinmu No. 4” under different concentrations of alkali stress and different concentrations of Ce(NO3)3 treatment.

[0061] Seed disinfection

[0062] Same as Example 1

[0063] Seedling stress and Ce(NO3)3 treatment

[0064] Based on Hoagland nutrient solution, prepare 80, 90, and 100 mM Na +Salt-alkali solution (NaCl:NaHCO3 molar ratio 1:1, pH = 8.5, Na + The concentrations were 80, 90, and 100 mM. The corresponding weights of Ce(NO3)3 were accurately weighed and added to the alkaline solution to prepare 300, 400, 500, and 600 μM Ce(NO3)3 compound saline-alkali solutions. For each treatment, 1 g of alfalfa seeds were weighed, and 1.5 mL of the corresponding compound saline-alkali solution was added. The solutions were placed in a dark environment at 25°C for 6 hours. Excess moisture on the seed surface was absorbed with filter paper. The treated seeds were then evenly arranged in square transparent plastic petri dishes (90 mm on each side) lined with double-layered sterile filter paper, with 50 seeds per dish. Untreated seeds and petri dishes with added water served as blank controls (CK1), and untreated seeds and petri dishes with added saline-alkali solution served as positive controls (CK2), for a total of 16 treatments (see Table 2). To verify the effectiveness of NO3... - To further enhance the effect, 12 additional treatments were added (see Table 3). 6 mL of solution was added to each petri dish, and the dish was weighed. Daily evaporation was replenished with deionized water. Each treatment was replicated three times. The petri dishes were placed in a light incubator under the same incubation conditions as in Example 1.

[0065] Table 2 Ce(NO3)3 treated solutions

[0066]

[0067] Table 3 KNO3-treated solutions

[0068]

[0069] Phenotypic analysis

[0070] like Figure 2A As shown, 80mM Na + Under saline-alkali stress, soaking in 300 and 400 μM Ce(NO3)3 significantly improved the germination potential of alfalfa (p<0.01), while soaking in 500 μM Ce(NO3)3 had no effect on the germination potential (p>0.05). Soaking in 600 μM Ce(NO3)3 amplified the effect of alkaline stress on the germination potential of alfalfa (p<0.01). Soaking in 300 and 400 μM Ce(NO3)3 significantly improved the germination rate of alfalfa (p < 0.01), while soaking in 500 μM Ce(NO3)3 had no effect on the germination rate (p > 0.05), and soaking in 600 μM Ce(NO3)3 significantly reduced the germination rate of alfalfa (p < 0.01).

[0071] like Figure 2B As shown, 90mM Na +Under salt-alkali stress, soaking in 400 and 500 μM Ce(NO3)3 significantly increased the germination potential of alfalfa (p < 0.01), while soaking in 300 and 600 μM Ce(NO3)3 had no effect on the germination potential (p > 0.05). The germination rate results were similar to the germination potential results.

[0072] like Figure 2C As shown, 100 mM Na + Under saline-alkali stress, soaking seeds in 400 and 500 μM Ce(NO3)3 greatly alleviated the damage caused by alkali stress to "Xinmu No. 4" and significantly improved the germination potential and germination rate of alfalfa (p < 0.01), while soaking seeds in 300 and 600 μM Ce(NO3)3 had no effect on the germination potential and germination rate of alfalfa (p > 0.05).

[0073] like Figure 2D , Figure 2E As shown, 80 and 90 mM Na + Under salt-alkali stress, soaking in 300, 400, 500 and 600 μM KNO3 did not alleviate the damage caused by alkali stress to "Xinmu No. 4" and had no effect on the germination potential and germination rate of alfalfa (p > 0.05).

[0074] Example 3: The effects of two coating treatments with different Ce(NO3)3 concentrations on 2‰ (mild) salt-alkali stress in "Xinmu No. 4" seedlings.

[0075] Seed treatment

[0076] Same as Example 1.

[0077] Seed suspension coating (SC)

[0078] Materials: Uncoated alfalfa seeds of "Xinmu No. 4";

[0079] Equipment: Hyn-wlhj type suspension coating machine (Qingdao Huiyinong Agricultural Technology Co., Ltd.);

[0080] The formulation of the suspension coating agent is shown in Table 4:

[0081] Table 4 Suspension Coating Agent Formulation

[0082]

[0083] Seed suspension coating was performed using a Hyn-wlhj type suspension coating machine (Qingdao Huiyinong Agricultural Technology Co., Ltd.). 300, 400, 500, and 600 μM Ce(NO3)3 solutions were prepared. 2% polyvinyl alcohol (polyvinyl alcohol) as a film-forming agent, 0.3% OP-10 as an emulsifier, 0.1% sodium methylene dimethylnaphthalene sulfonate (MF) as a dispersant, 0.05% NXZ as an antifoaming agent, 0.2% PE-100 as a wetting agent, and 0.1% carmine / indigo (w / v) as a colorant were added to the solutions to prepare the suspension coating agent carrier.

[0084] Turn on the coating machine and adjust the speed to 700 r / min. Coat the alfalfa seeds with a 1:1.5 (w / v) ratio of suspension coating agent carrier. Add the coating agent in small amounts multiple times. After all the agent has been added, continue running the coating machine for 3-5 minutes to ensure that the carrier is evenly coated on the seeds. After coating, place the coated seeds in a clean bench to air dry naturally for 3 hours before use.

[0085] Seed Pelletization (SP) Coating

[0086] Materials: 5g of "Xinmu No. 4" suspension-coated alfalfa seeds;

[0087] Adhesive: 1.5% sodium carboxymethyl cellulose aqueous solution;

[0088] Powder: The powder formulation is shown in the table below;

[0089] Equipment: Hyn-wlhj seed pelleting and coating machine (Qingdao Huiyinong Agricultural Technology Co., Ltd.).

[0090] Table 3 Formulation of pelleting coating agent

[0091]

[0092] Table 4 Coating Costs

[0093]

[0094] Granulation and coating were performed using a Hyn-wlhj-shaped seed pelleting and coating machine (Qingdao Huiyinong Agricultural Technology Co., Ltd.), based on suspension-coated seeds. The specific steps are as follows: Start the coating machine, pour 5g of alfalfa seeds into the drum, and begin wetting the seeds with a 0.5mL binder sprayer, repeating this process three times until the seed surface is completely wetted but no liquid drips. Add the first layer of coating agent evenly to the coating pan, run for 2 minutes until the added powder completely adheres to the seed surface, then add 3mL of binder, followed by the second layer of coating agent. Run for another 3 minutes until the second layer of coating agent is completely adhered to the seed surface, then add 1.5mL of binder, followed by the third layer of coating agent. After all the coating agent and solution have been added, continue running the coating machine for another 5 minutes. After granulation, place the pelleted seeds indoors to air dry naturally for 3 days. The physical properties of the pelleted seeds are shown in the table below.

[0095] Table 5 Performance Evaluation of Alfalfa Pelletized Seeds

[0096]

[0097] sowing

[0098] Alfalfa seeds coated with suspension coating and pellet coating were sown in 11cm diameter and 10cm high flowerpots containing 400g of high-temperature sterilized and dried constant weight substrate (non-saline soil: vermiculite: peat moss = 8:1:1, w / w / w) at a depth of 1cm, with 20 seeds sown per pot.

[0099] Soil salinity stress

[0100] Prepare a 0.132 M saline-alkali solution (NaCl:NaHCO3 molar ratio 1:1, pH=8.5), and pour 85 mL of the solution into each pot (soil compound salt content is about 4‰ (w / w), relative humidity is 17.52%). Weigh the solution and replenish the daily evaporation with distilled water. CK1 is uncoated seeds watered with plain water, and CK2 is uncoated seeds watered with saline-alkali solution.

[0101] Indicator Testing

[0102] Observe the germination rate 4–10 days after sowing, and assess biomass and root indicators during the seedling stage (30 days).

[0103] Phenotypic analysis

[0104] like Figures 4A-4CAs shown, 2‰ soil salinity significantly reduced the germination potential and germination rate of 'Xinmu 4' alfalfa (p < 0.01). Under salinity stress, 300 μM Ce(NO3)3 suspension and pellet coating significantly increased the germination potential of 'Xinmu 4' alfalfa (p < 0.05), while 400 μM Ce(NO3)3 suspension and pellet coating significantly increased the germination potential (p < 0.01). 300 μM Ce(NO3)3 pellet coating significantly increased the germination potential (p < 0.01), and 400 μM Ce(NO3)3 suspension and pellet coating significantly increased the germination rate (p < 0.01). 500 and 600 μM... Ce(NO3)3 suspension and pellet coating had no effect on alleviating the germination potential and germination rate of "Xinmu No. 4" alfalfa under salt-alkali stress (p > 0.05). At the same concentration of Ce(NO3)3, neither coating method showed significant differences (p > 0.05).

[0105] like Figures 4D-4F As shown, soil salinity stress of 2‰ significantly reduced the plant height of "Xinmu No. 4" alfalfa (p < 0.01). Except for 600 μM Ce(NO3)3 suspension coating, other treatments significantly improved plant growth (p < 0.01).

[0106] Example 4: The effects of two coating treatments with different cerium nitrate concentrations on 4‰ (moderate) salt-alkali stress in "Xinmu No. 4" seedlings.

[0107] Seed treatment

[0108] Same as Example 1.

[0109] Seed suspension coating (SC)

[0110] Same as Example 3.

[0111] Seed pelleting (SP) coating

[0112] Same as Example 3.

[0113] sowing

[0114] Same as Example 3.

[0115] Salt stress

[0116] Prepare a 0.264M saline-alkali solution (NaCl:NaHCO3 molar ratio 1:1, pH=8.5), and pour 85mL of the solution into each pot (the soil compound salt content is about 4‰ (w / w), and the relative humidity is 17.52%). Weigh the solution and replenish the daily evaporation with distilled water. CK1 is uncoated seeds watered with clean water, and CK2 is uncoated seeds watered with the alkaline solution.

[0117] Indicator Testing

[0118] Emergence rate was observed 4–10 days after sowing. Biomass, root indicators, and antioxidant enzyme activity were assessed during the seedling stage (30 days). Peroxidase (POD) activity was detected using the guaiacol assay. Superoxide dismutase (SOD) activity was determined using the nitroblue tetrazolium colorimetric method. Catalase (CAT) activity was detected using the UV-Vis colorimetric method. Ascorbate peroxidase (APX) activity was detected using UV spectrophotometry. Glutathione reductase (GR) activity was detected using the NADPH method.

[0119] Phenotypic analysis

[0120] like Figures 5A-5C As shown, soil salinity stress of 4‰ significantly reduced the germination potential and germination rate of 'Xinmu 4' alfalfa (p < 0.01). Under salinity stress, 400 μM Ce(NO3)3 suspension and pellet coating significantly increased the germination potential of 'Xinmu 4' alfalfa (p < 0.01), while 500 μM Ce(NO3)3 suspension and pellet coating significantly increased the germination potential of 'Xinmu 4' alfalfa (p < 0.05). Notably, 600 μM Ce(NO3)3 suspension coating significantly reduced the germination potential of 'Xinmu 4' alfalfa (p < 0.01), while 400 μM Ce(NO3)3 suspension and pellet coating, and 500 μM Ce(NO3)3 suspension coating significantly increased the germination rate of 'Xinmu 4' alfalfa (p < 0.05). At the same Ce(NO3)3 concentration, neither coating method showed a significant difference (p > 0.01).

[0121] like Figures 5D-5FAs shown, soil salinity stress of 4‰ significantly reduced alfalfa plant height, root length, and plant weight (p < 0.01). Compared with uncoated salinity stress (CK2), suspension and pellet coating significantly increased alfalfa plant height, root length, and plant weight under salinity stress. Soil salinity stress of 4‰ significantly reduced plant CAT activity (p < 0.01), significantly increased plant POD activity (p < 0.01), and significantly increased plant GR activity (p < 0.05), but had no significant effect on SOD, APX, and MDHAR activities (p > 0.05). Compared with uncoated salinity stress (CK2), suspension coating (SC) significantly increased plant SOD activity (p < 0.05) and significantly increased plant APX activity (p < 0.01), but significantly decreased plant MDHAR activity (p < 0.05). Except for a significant increase in plant POD activity (p < 0.05), the pellet coating (SP) showed extremely significant increases in all other activities (p < 0.01).

[0122] Example 5: The effects of two coating treatments with different cerium nitrate concentrations on 6‰ (medium salt) salt-alkali stress in "Xinmu No. 4" seedlings.

[0123] Seed treatment

[0124] Same as Example 1.

[0125] Seed suspension coating (SC)

[0126] Same as Example 3.

[0127] Seed pelleting (SP) coating

[0128] Same as Example 3.

[0129] sowing

[0130] Same as Example 3.

[0131] Salt stress

[0132] Prepare a 0.396M saline-alkali solution (NaCl:NaHCO3 molar ratio 1:1, pH=8.5), and pour 85mL of the solution into each pot (soil compound salt content is about 4‰ (w / w), relative humidity is 17.52%). Weigh the solution and replenish the daily evaporation with distilled water. CK1 is uncoated seeds watered with water, and CK2 is uncoated seeds watered with the alkaline solution.

[0133] Indicator Testing

[0134] Same as Example 4.

[0135] Phenotypic analysis

[0136] like Figures 6A-6CAs shown, soil salinity stress of 6‰ significantly reduced the germination potential and germination rate of 'Xinmu 4' alfalfa (p < 0.01). Under salinity stress, 400 μM Ce(NO3)3 suspension and pellet coating, and 300 and 500 μM Ce(NO3)3 pellet coating significantly improved the germination potential of 'Xinmu 4' alfalfa (p < 0.01), while 500 μM Ce(NO3)3 suspension coating significantly improved the germination potential of 'Xinmu 4' alfalfa (p < 0.05). 400 and 500 μM Ce(NO3)3 suspension and pellet coating, and 300 μM Ce(NO3)3 pellet coating significantly improved the germination rate of 'Xinmu 4' alfalfa (p < 0.01).

[0137] Figure 6.D- Figure 6F As shown, soil salinity stress of 6‰ significantly reduced alfalfa plant height, plant weight, and root length (p < 0.01). Compared with uncoated salinity stress (CK2), suspension coating significantly increased alfalfa plant height and plant weight under salinity stress (p < 0.05), and significantly increased root length (p < 0.01). Granulated coating significantly increased plant height, root length, and plant weight (p < 0.01). Soil salinity stress of 6‰ significantly reduced plant CAT activity (p < 0.01), significantly increased plant GR and MDHAR activities (p < 0.01), and significantly reduced plant SOD activity (p < 0.05), while having no significant effect on POD and APX activities (p > 0.05). Compared with uncoated salt-alkali stress (CK2), suspension-coated (SC) significantly increased the activities of SOD, GR (p < 0.001), and POD (p < 0.01) in plants, while having no significant effect on CAT, APX, and MDHAR activities (p > 0.05). Granulated coating (SP), except for a highly significant decrease in MDHAR activity, significantly or highly significantly increased the activities of other enzymes in plants.

Claims

1. A coating agent for establishing alfalfa in Suda saline land, characterized by, The coating agent is a cerium nitrate solution containing a film-forming agent, emulsifier, dispersant, defoamer, and wetting agent.

2. The coating agent according to claim 1, wherein the active ingredient in the coating agent is cerium nitrate, and the concentration of the cerium nitrate solution is 300-500 μM.

3. The concentration of the cerium nitrate solution in the coating agent according to claim 2 is 400-500 μM.

4. The coating agent according to claim 3, wherein the coating agent contains 1.5-2.5 w / v% of a film-forming agent, 0.2-0.4 w / v% of an emulsifier, 0.05-0.15 w / v% of a dispersant, 0.04-0.06 w / v% of an antifoamer, and 0.1-0.3 w / v% of a wetting agent.

5. The coating agent according to claim 4, wherein the film-forming agent is polyvinyl alcohol, and / or the emulsifier is OP-10, the dispersant is sodium methylene dimethylnaphthalene sulfonate, the defoamer is NXZ, and the wetting agent is PE-100; optionally, the coating agent further includes a colorant.

6. A method for improving the salt and alkali stress tolerance of plants, characterized in that, The method uses the coating agent according to any one of claims 1-5 to coat plant seeds.

7. The method according to claim 6, wherein the plant is an alfalfa plant, preferably alfalfa.

8. The method according to claim 6 or 7, wherein the method uses the coating agent according to any one of claims 1-5 to perform suspension coating on plant seeds.

9. The method according to claim 6 or 7, wherein the plant seeds are suspended and coated with the coating agent according to any one of claims 1-5 before being pelletized.

10. The method according to claim 6, wherein the improvement of plant tolerance to salt and alkali stress includes one or more of the following effects: (1) Improve the germination potential and germination rate of plants under salt and alkali stress; (2) Increase plant height, root length and antioxidant enzyme activity in plants under salt stress.

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