Preparation method and application of lignin chelated zinc rice seed coating agent

Abstract

The invention discloses a preparation method and application of a lignin chelated zinc rice seed coating agent, and the preparation method comprises the following steps: weighing a certain amount of lignin powder, dissolving the powder, adding a zinc salt solution according to a certain proportion, carrying out a chelation reaction, filtering the chelate after the reaction is finished, washing the chelate, standing, filtering, and drying to obtain the lignin chelated zinc; heating and uniformly stirring a lignin chelated zinc sample, a composite film-forming agent and a plasticizer, then adding nano silicon dioxide, mixing to obtain a coating solution, and preserving heat for later use; and weighing a certain amount of rice seeds, immersing the rice seeds into the coating solution, stirring, fishing out, and air-drying to obtain the lignin chelated zinc coated rice seeds. The invention further discloses application of the lignin chelated zinc rice seed coating agent, and the lignin chelated zinc rice seed coating agent can improve the seed germination ability, promote seedling survival and relieve stress resistance. The rice seed coating agent provided by the invention is environment-friendly, can improve the drought tolerance of seeds, can also effectively protect the seeds, and meanwhile, ensures a relatively high germination rate of the seeds.

Description

Technical Field

[0001] This invention relates to the field of seed coating agent technology, and in particular to a method for preparing and applying a lignin-chelated zinc rice seed coating agent. Background Technology

[0002] With global population growth and increasing constraints on arable land resources, seed coating technology, as a key measure to improve agricultural production efficiency and ensure food security, is undergoing a transformation from traditional chemical treatment to green and functional methods. This presents both opportunities and challenges for the development of seed coating technology in my country.

[0003] Rice plays a vital role in the food structure and human life, and its yield and quality directly affect food security. However, traditional rice cultivation often faces problems such as low seedling survival rates and inefficient nutrient utilization, which severely limit the sustainable development of the rice industry. Rice is one of the most zinc-sensitive crops. Zinc, as a cofactor for many enzymes, participates in photosynthesis, protein synthesis, and hormone metabolism. Zinc deficiency in rice seedlings can lead to poor root development and albino seedlings, seriously affecting later yield formation. Statistics show that about 50% of paddy soil in my country has potential zinc deficiency, especially in calcareous soils and flooded paddy fields, where zinc availability is lower and the deficiency is more widespread. Traditional soil-applied zinc fertilizers are easily fixed by the soil, while seed-coated zinc can be directly absorbed by seedlings, improving nutrient utilization efficiency. Therefore, precise zinc supplementation can be achieved through seed coating technology, providing zinc nutrition during the most sensitive germination period of rice, laying the foundation for high yields. Lignin, as the second most abundant natural polymer material, has good biocompatibility and biodegradability. Studies have found that lignin molecules contain abundant active groups such as phenolic hydroxyl and carboxyl groups, which can form stable chelates with zinc ions. This chelate structure has the following advantages when applied to seed germination: First, it improves the stability of zinc and reduces soil fixation; second, it controls the release rate of zinc and prolongs the fertilizer effect period; third, it enhances the transport efficiency of zinc in plants; and fourth, lignin itself also promotes seed germination.

[0004] Furthermore, a growing body of research has confirmed the crucial role of zinc in seed germination. Zinc initiation is a key technology for low-cost, high-efficiency activation of seed metabolism and alleviating zinc deficiency stress. Zinc promotes seed germination and seedling growth through a triple mechanism of metabolic activation, stress enhancement, and nutrient supply. However, among currently disclosed seed coating technologies, CN101665383B partially addresses the problem of trace element loss through physical encapsulation and slow-release membrane technology, but compared to modern chelation technologies, it still has significant shortcomings in terms of chemical stability, targeted element release, and long-term effectiveness. CN111771454A discloses a slow-release seed coating agent based on papermaking black liquor, but it has not been specifically optimized for zinc. In particular, regarding the chelation process between lignin and zinc, existing technologies still suffer from technical bottlenecks such as low chelation rates and poor coating adhesion.

[0005] Therefore, developing a highly efficient and environmentally friendly lignin-chelated zinc seed coating agent is of significant research importance. The lignin-chelated zinc coating technology for rice seeds provided by this invention not only significantly improves rice seed germination rate and seedling uniformity but also achieves precise zinc supply, reducing fertilizer usage and possessing significant economic and ecological value. This invention is highly efficient, low in toxicity, simple to produce, and inexpensive, and it significantly improves zinc utilization, slow-release performance, and coating stability. Summary of the Invention

[0006] The present invention aims to provide a method for preparing and applying a lignin-chelated zinc rice seed coating agent to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A method for preparing a lignin-chelated zinc rice seed coating agent, comprising the following steps:

[0009] S1: Weigh a certain amount of soluble zinc salt reagent, add it to water and stir to dissolve it, thus obtaining a zinc-containing solution;

[0010] S2: Accurately weigh a certain amount of lignin powder, dissolve the powder in water, add it to a zinc-containing solution, and place it in a reaction vessel to carry out a chelation reaction;

[0011] S3: After the reaction is complete, filter the chelate, then wash, let stand, filter, and dry the chelate to obtain the lignin chelated zinc sample;

[0012] S4: The lignin-chelated zinc sample was mixed with the composite film-forming agent and plasticizer by heating and stirring until homogeneous. Then a small amount of nano-silica was added and mixed to obtain a coating solution, which was kept warm for later use.

[0013] S5: Weigh a certain amount of rice seeds, immerse them in the coating solution, stir for a certain period of time, take them out, spread them out in a low-temperature environment to quickly gel, and then air dry them to obtain lignin chelated zinc coated rice seeds.

[0014] Preferably, the soluble zinc salt reagent in S1 includes, but is not limited to, one or more of zinc chloride, zinc sulfate, and zinc nitrate;

[0015] The zinc ions in the zinc-containing solution account for 5-8% of the lignin mass, and the water is secondary water or ultrapure water;

[0016] The stirring conditions are 180~250 rpm, temperature 25~40 ℃, and stirring time 15~25 min.

[0017] Preferably, the lignin in S2 is one or more of alkali lignin, sulfate lignin, sulfonate lignin, and enzymatically hydrolyzed lignin.

[0018] The dissolved lignin has a mass of 1~8 g / L, and the water is secondary water or ultrapure water.

[0019] The preferred chelation reaction conditions are 400 rpm, 70 ℃, and 40 min.

[0020] Preferably, the drying temperature in S3 is 50 °C.

[0021] Preferably, the composite film-forming agent in S4 comprises one or more of polyvinyl alcohol, sodium carboxymethyl cellulose, sodium alginate, chitosan, xanthan gum, carrageenan, gelatin, pectin, and gum arabic, and the amount used is 2% to 6% of the total mass by weight.

[0022] The plasticizer comprises one or two of polyethylene glycol, propylene glycol, and glycerol, and is used in an amount of 1% to 4% of the total mass by weight.

[0023] The stirring conditions were 400 rpm, 70 ℃, and 1 h.

[0024] The amount of nano-silica used is 0.2% to 0.5% by mass.

[0025] The mixing conditions were 400 rpm, 40 ℃, and 15~20 min.

[0026] The insulation condition is 40 ℃.

[0027] Preferably, the mass ratio of the coating solution to the rice seeds in S5 is 1:100~300;

[0028] The stirring conditions are 100~200 rpm, temperature 25~40 ℃, and stirring time 5~10 min.

[0029] The low-temperature environment is 0~5℃, and the air-drying time is 48 h.

[0030] Preferably, the coating agent prepared by a method for preparing a lignin-chelated zinc rice seed coating agent is used to improve seed germination ability, promote seedling survival, and alleviate stress resistance.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) The seed coating agent of the present invention is environmentally friendly and green, and its main raw material is industrial waste lignin, which realizes the reuse of waste.

[0033] (2) The seed coating agent of the present invention has a simple preparation process and low cost, and is suitable for large-scale promotion in agricultural production;

[0034] (3) The seed coating agent of the present invention has obvious effects, plays a slow-release role of zinc, prolongs the fertilizer effect, and can improve the seed germination rate, promote seedling growth and accelerate root elongation.

[0035] (4) The seed coating agent of the present invention can alleviate stress and, in particular, improve the drought resistance of seeds;

[0036] (5) The seed coating agent of the present invention has good film-forming properties and is not easy to fall off, which can effectively protect seed germination and facilitate transportation and storage. Attached Figure Description

[0037] Figure 1 Diagram showing the rice seed coating process;

[0038] Figure 2 Figure (a) shows the growth status of rice seeds 10 days after germination in Application Example 1; Figure (b) shows a comparison of seed germination rate results.

[0039] Figure 3 The swelling rate (a); water retention rate (b); and growth status of rice seeds 7 days after germination are shown in Example 2.

[0040] Figure 4 This is a flowchart of a method for preparing a lignin-chelated zinc rice seed coating agent. Detailed Implementation

[0041] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments:

[0042] Unless otherwise specified, all methods described herein are conventional methods, and all materials described herein are commercially available. The lignin used in these embodiments was purchased from Shandong Xinglong Paper (Group) Co., Ltd., and the zinc sulfate used was purchased from Tianjin Huasheng Chemical Reagent Co., Ltd.

[0043] like Figure 1 and Figure 4 The method for preparing a lignin-chelated zinc rice seed coating agent provided by the present invention includes the following steps:

[0044] S1: Weigh a certain amount of soluble zinc salt reagent, add it to water and stir to dissolve it, thus obtaining a zinc-containing solution;

[0045] S2: Accurately weigh a certain amount of lignin powder, dissolve the powder in water, add it to a zinc-containing solution, and place it in a reaction vessel to carry out a chelation reaction;

[0046] S3: After the reaction is complete, filter the chelate, then wash, let stand, filter, and dry the chelate to obtain the lignin chelated zinc sample;

[0047] S4: The lignin-chelated zinc sample was mixed with the composite film-forming agent and plasticizer by heating and stirring until homogeneous. Then a small amount of nano-silica was added and mixed to obtain a coating solution, which was kept warm for later use.

[0048] S5: Weigh a certain amount of rice seeds, immerse them in the coating solution, stir for a certain period of time, take them out, spread them out in a low-temperature environment to quickly gel, and then air dry them to obtain lignin chelated zinc coated rice seeds.

[0049] The specific implementation process is as follows:

[0050] Example 1

[0051] S1: Accurately weigh 0.1 part of zinc sulfate, dissolve it in deionized water, and stir for 20 min at 200 rpm and 25 ℃ to obtain a zinc-containing solution with a zinc concentration of 0.1 g / L;

[0052] S2: Accurately weigh 1.5 parts of lignin powder and dissolve the powder in deionized water. The lignin content is 1.5 g / L. Then add zinc-containing solution and place in a reaction vessel. React at 400 rpm and 70 ℃ for 40 min.

[0053] S3: After the reaction is complete, filter the chelate, then wash, let stand, filter, and dry in a 50 ℃ oven to obtain the lignin chelated zinc sample;

[0054] S4: A composite film-forming agent and plasticizer were added to the lignin-chelated zinc sample. The amounts of carrageenan 1.2%, xanthan gum 0.5%, sodium alginate 0.15%, polyvinyl alcohol 0.25%, and glycerol 2% by mass percentage. The mixture was stirred at 400 rpm and 70 ℃ for 1 h. Then, 0.25% nano silica was added and mixed at 400 rpm and 40 ℃ for 15 min to obtain the coating solution. The solution was kept at 40 ℃ for later use.

[0055] S5: Weigh 100 parts of rice seeds and immerse them in 1 part of coating solution. Stir at 200 rpm and 25 ℃ for 5 min, then remove the seeds and spread them out at 0~5 ℃ for rapid gelation. Then air dry for 48 h to form a thin film on the surface of the rice seeds, thus obtaining lignin chelated zinc coated rice seeds (LSZn-CR0.1).

[0056] Example 2

[0057] S1: Accurately weigh 0.2 parts of zinc sulfate, dissolve it in deionized water, and stir for 20 min at 200 rpm and 25 ℃ to obtain a zinc-containing solution with a zinc concentration of 0.2 g / L;

[0058] S2: Accurately weigh 3 portions of lignin powder and dissolve the powder in deionized water. The lignin content is 3 g / L. Then add zinc-containing solution and place in a reaction vessel. React at 400 rpm and 70 ℃ for 40 min.

[0059] S3: After the reaction is complete, filter the chelate, then wash, let stand, filter, and dry in a 50 ℃ oven to obtain the lignin chelated zinc sample;

[0060] S4: A composite film-forming agent and plasticizer were added to the lignin-chelated zinc sample. The amounts of carrageenan 1.2%, xanthan gum 0.5%, sodium alginate 0.15%, polyvinyl alcohol 0.25%, and glycerol 2% by mass percentage. The mixture was stirred at 400 rpm and 70 ℃ for 1 h. Then, 0.25% nano silica was added and mixed at 400 rpm and 40 ℃ for 15 min to obtain the coating solution. The solution was kept at 40 ℃ for later use.

[0061] S5: Weigh 100 parts of rice seeds and immerse them in 1 part of coating solution. Stir at 200 rpm and 25 ℃ for 5 min, then remove the seeds and spread them out at 0~5 ℃ for rapid gelation. Then air dry for 48 h to form a thin film on the surface of the rice seeds, thus obtaining lignin chelated zinc coated rice seeds (LSZn-CR0.2).

[0062] Example 3

[0063] S1: Accurately weigh 0.3 parts of zinc sulfate, dissolve it in deionized water, and stir for 20 min at 200 rpm and 25 ℃ to obtain a zinc-containing solution with a zinc concentration of 0.3 g / L;

[0064] S2: Accurately weigh 4.5 parts of lignin powder and dissolve the powder in deionized water. The lignin content is 4.5 g / L. Then add zinc-containing solution and place in a reaction vessel. React at 400 rpm and 70 ℃ for 40 min.

[0065] S3: After the reaction is complete, filter the chelate, then wash, let stand, filter, and dry in a 50 ℃ oven to obtain the lignin chelated zinc sample;

[0066] S4: A composite film-forming agent and plasticizer were added to the lignin-chelated zinc sample. The amounts of carrageenan 1.2%, xanthan gum 0.5%, sodium alginate 0.15%, polyvinyl alcohol 0.25%, and glycerol 2% by mass percentage. The mixture was stirred at 400 rpm and 70 ℃ for 1 h. Then, 0.25% nano silica was added and mixed at 400 rpm and 40 ℃ for 15 min to obtain the coating solution. The solution was kept at 40 ℃ for later use.

[0067] S5: Weigh 100 parts of rice seeds and immerse them in 1 part of coating solution. Stir at 200 rpm and 25 ℃ for 5 min, then remove the seeds and spread them out at 0~5 ℃ for rapid gelation. Then air dry for 48 h to form a thin film on the surface of the rice seeds, thus obtaining lignin chelated zinc coated rice seeds (LSZn-CR0.3).

[0068] Example 4

[0069] S1: Accurately weigh 0.4 parts of zinc sulfate, dissolve it in deionized water, and stir for 20 min at 200 rpm and 25 ℃ to obtain a zinc-containing solution with a zinc concentration of 0.4 g / L;

[0070] S2: Accurately weigh 6 portions of lignin powder and dissolve the powder in deionized water. The lignin content is 6 g / L. Then add zinc-containing solution and place in a reaction vessel. React at 400 rpm and 70 ℃ for 40 min.

[0071] S3: After the reaction is complete, filter the chelate, then wash, let stand, filter, and dry in a 50 ℃ oven to obtain the lignin chelated zinc sample;

[0072] S4: A composite film-forming agent and plasticizer were added to the lignin-chelated zinc sample. The amounts of carrageenan 1.2%, xanthan gum 0.5%, sodium alginate 0.15%, polyvinyl alcohol 0.25%, and glycerol 2% by mass percentage. The mixture was stirred at 400 rpm and 70 ℃ for 1 h. Then, 0.25% nano silica was added and mixed at 400 rpm and 40 ℃ for 15 min to obtain the coating solution. The solution was kept at 40 ℃ for later use.

[0073] S5: Weigh 100 parts of rice seeds and immerse them in 1 part of coating solution. Stir at 200 rpm and 25 ℃ for 5 min, then remove the seeds and spread them out at 0~5 ℃ for rapid gelation. Then air dry for 48 h to form a thin film on the surface of the rice seeds, thus obtaining lignin chelated zinc coated rice seeds (LSZn-CR0.4).

[0074] Example 5

[0075] S1: Accurately weigh 0.5 parts of zinc sulfate, dissolve it in deionized water, and stir for 20 min at 200 rpm and 25 ℃ to obtain a zinc-containing solution with a zinc concentration of 0.5 g / L;

[0076] S2: Accurately weigh 7.5 parts of lignin powder and dissolve the powder in deionized water. The lignin content is 7.5 g / L. Then add zinc-containing solution and place in a reaction vessel. React at 400 rpm and 70 ℃ for 40 min.

[0077] S3: After the reaction is complete, filter the chelate, then wash, let stand, filter, and dry in a 50 ℃ oven to obtain the lignin chelated zinc sample;

[0078] S4: A composite film-forming agent and plasticizer were added to the lignin-chelated zinc sample. The amounts of carrageenan 1.2%, xanthan gum 0.5%, sodium alginate 0.15%, polyvinyl alcohol 0.25%, and glycerol 2% by mass percentage. The mixture was stirred at 400 rpm and 70 ℃ for 1 h. Then, 0.25% nano silica was added and mixed at 400 rpm and 40 ℃ for 15 min to obtain the coating solution. The solution was kept at 40 ℃ for later use.

[0079] S5: Weigh 100 parts of rice seeds and immerse them in 1 part of coating solution. Stir at 200 rpm and 25 ℃ for 5 min, then remove the seeds and spread them out at 0~5 ℃ for rapid gelation. Then air dry for 48 h to form a thin film on the surface of the rice seeds, thus obtaining lignin chelated zinc coated rice seeds (LSZn-CR0.5).

[0080] Comparative Example 1

[0081] S1: Weigh the composite film-forming agent and plasticizer, and the amounts are as follows (by mass percentage): carrageenan 1.2%, xanthan gum 0.5%, sodium alginate 0.15%, polyvinyl alcohol 0.25%, and glycerol 2%. Stir at 400 rpm and 70 ℃ for 1 h. Then add 0.25% nano silica and mix at 400 rpm and 40 ℃ for 15 min to obtain the coating solution. Keep it at 40 ℃ for later use.

[0082] S2: Weigh 100 parts of rice seeds and immerse them in 1 part of coating solution. Stir at 200 rpm and 25 ℃ for 5 min, then remove the seeds and spread them out at 0~5 ℃ for rapid gelation. Then air dry for 48 h to form a thin film on the surface of the rice seeds, thus obtaining lignin chelated zinc coated rice seeds (LSZn-CR).

[0083] Comparative Example 2

[0084] S1: Accurately weigh 0.3 parts of zinc sulfate, dissolve it in deionized water, and stir for 20 min at 200 rpm and 25 ℃ to obtain a zinc-containing solution with a zinc concentration of 0.3 g / L;

[0085] S2: Add a composite film-forming agent and plasticizer to a zinc-containing solution. The amounts of carrageenan 1.2%, xanthan gum 0.5%, sodium alginate 0.15%, polyvinyl alcohol 0.25%, and glycerol 2% by mass percentage. Stir at 400 rpm and 70 ℃ for 1 h. Then add 0.25% nano silica and mix at 400 rpm and 40 ℃ for 15 min to obtain a coating solution. Keep it at 40 ℃ for later use.

[0086] S3: Weigh 100 parts of rice seeds and immerse them in 1 part of coating solution. Stir at 200 rpm and 25 ℃ for 5 min, then remove the seeds and spread them out at 0~5 ℃ for rapid gelation. Then air dry for 48 h to form a thin film on the surface of the rice seeds, thus obtaining lignin chelated zinc coated rice seeds (ZnSO4-CR0.3).

[0087] Application Example 1

[0088] Application of lignin-chelated zinc coating agent in promoting rice seed germination and seedling growth

[0089] The experimental design included eight treatments: LSZn-CR, LSZn-CR0.1, LSZn-CR0.2, LSZn-CR0.3, LSZn-CR0.4, LSZn-CR0.5, ZnSO4-CR0.3, and CK (uncoated rice seed control). Each treatment was replicated three times, with each replicate containing 100 seeds. (See Table 1 and...) Figure 2As shown in the figure, the filter paper germination method was used. Rice seeds were cultured in petri dishes with a diameter of 9 cm. The seeds were evenly placed in the petri dishes, and water was added to keep the filter paper moist. The dishes were placed in an artificial climate chamber with a temperature of 27±1 ℃, a relative humidity of 65±5%, and a photoperiod of L:D=10:14. The water lost from the petri dishes was replenished regularly. The day of seed implantation was taken as the first day. The germination of rice seeds was observed and recorded every day (germination standard was radicle ≥2 mm). Germination potential was counted on the 4th day, and germination rate was counted on the 6th day. On the 7th day, 10 seedlings with similar growth were randomly selected from each replicate to measure root length and shoot length. On the 10th day, the treatments were compared and photographed.

[0090] Germination potential and germination rate both refer to the percentage of germinated seeds out of the total number of seeds tested, and are calculated using the formula [(100 - number of ungerminated seeds) / 100] × 100%;

[0091] Table 1. Effects of lignin-chelated zinc coating agent on rice seed germination and seedling growth.

[0092]

[0093] Application Example 2

[0094] Application of lignin-chelated zinc coating agent to enhance drought resistance in rice seeds

[0095] Prepare rice seed coating materials LSZn-CR, LSZn-CR0.1, LSZn-CR0.2, LSZn-CR0.3, LSZn-CR0.4, LSZn-CR0.5, and ZnSO4-CR0.3. Characterize the materials, including swelling rate and water retention rate tests. The specific procedure for the swelling rate test is as follows: Cut the dried material into squares with a side length of 1 cm, weigh and record the initial weight W0, and then soak it in phosphate buffer solution at 25 ℃ and neutral pH. After a certain time (5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55 min), remove the material with tweezers, wipe off the surface moisture, and weigh and record the weight Ws after swelling. Calculate the swelling rate (%) using the formula: Swelling rate (%) = [(Ws) / ( ... The swelling rate of the rice seed coating material was calculated by multiplying [W0) / W0] by 100%. The specific results are shown in Table 2 below.

[0096] Table 2. Swelling rate of rice seed coating materials after soaking in water for 55 min.

[0097]

[0098] The specific process for water retention rate testing is as follows:

[0099] Cut the dried material into squares with sides of 1 cm and weigh them, recording the initial weight W0. Then, place them in water to swell for 24 hours, remove them, spread them evenly in a petri dish, and place them in an environment with a temperature of 25 ℃ and a humidity of 60%. After a certain period of time (1, 2, 4, 6, 8, 10, 12, 24, 48 h), use tweezers to pick them up, wipe off the surface moisture, weigh them again, and record the weight as W. t According to the calculation formula: Water retention rate (%) = [(W t The water retention rate of rice seed coating material was calculated by multiplying W0) / W0] by 100%; the specific results are shown in Table 3 below.

[0100] Table 3. Water retention rate of rice seed coating materials after standing for 48 h.

[0101]

[0102] Germination experiment of coated rice seeds under drought conditions: The experimental soil was arid soil (45% soil moisture content). Eight treatments were designed, including LSZn-CR, LSZn-CR0.1, LSZn-CR0.2, LSZn-CR0.3, LSZn-CR0.4, LSZn-CR0.5, ZnSO4-CR0.3, and CK (uncoated rice seed control). Each treatment was replicated three times, with each replicate containing 100 seeds. Specifically, the experiment was conducted under controlled conditions. Soil moisture content was controlled by weighing. After adding an appropriate amount of arid soil to a petri dish, rice seeds were evenly spread on the soil, and then a thin layer of soil was sprinkled on top to cover the seeds. The dishes were then placed in an artificial climate chamber with a temperature of 27±1 ℃, a relative humidity of 65±5%, and a photoperiod L:D=10:14. The day of seed implantation was considered day one, and the number of germinating rice seeds after 7 days was recorded (germination was defined as a radicle ≥2 mm). Specific results are shown below. Figure 3 As shown in Table 4.

[0103] Table 4. Effects of lignin-chelated zinc coating agent on rice seed germination under drought conditions.

[0104]

[0105] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A method for preparing a lignin-chelated zinc rice seed coating agent, characterized in that: The preparation steps include: S1: Weigh a certain amount of soluble zinc salt reagent, add it to water and stir to dissolve it, thus obtaining a zinc-containing solution; S2: Accurately weigh a certain amount of lignin powder, dissolve the powder in water, add it to a zinc-containing solution, and place it in a reaction vessel to carry out a chelation reaction; S3: After the reaction is complete, filter the chelate, then wash, let stand, filter, and dry the chelate to obtain the lignin chelated zinc sample; S4: The lignin-chelated zinc sample was mixed with the composite film-forming agent and plasticizer by heating and stirring until homogeneous. Then a small amount of nano-silica was added and mixed to obtain a coating solution, which was kept warm for later use. S5: Weigh a certain amount of rice seeds, immerse them in the coating solution, stir for a certain period of time, take them out, spread them out in a low-temperature environment to quickly gel, and then air dry them to obtain lignin chelated zinc coated rice seeds.

2. The method for preparing a lignin-chelated zinc rice seed coating agent according to claim 1, characterized in that: The soluble zinc salt reagent in step S1 is one or more of zinc chloride, zinc sulfate, and zinc nitrate. The zinc ions in the zinc-containing solution account for 5-8% of the lignin mass, and the water is secondary water or ultrapure water; The stirring conditions are 180~250 rpm, temperature 25~40 ℃, and stirring time 15~25 min.

3. The method for preparing a lignin-chelated zinc rice seed coating agent according to claim 1, characterized in that: In step S2, the lignin is one or more of alkali lignin, sulfate lignin, sulfonate lignin, and enzymatically hydrolyzed lignin. The dissolved lignin has a mass of 1~8 g / L, and the water is secondary water or ultrapure water; The chelation reaction conditions were 400 rpm, 70 ℃, and 40 min.

4. The method for preparing a lignin-chelated zinc rice seed coating agent according to claim 1, characterized in that: The drying temperature in S3 is 50 ℃.

5. The method for preparing a lignin-chelated zinc rice seed coating agent according to claim 1, characterized in that: The composite film-forming agent in step S4 includes one or more of the following: polyvinyl alcohol, sodium carboxymethyl cellulose, sodium alginate, chitosan, xanthan gum, carrageenan, gelatin, pectin, and gum arabic, and the amount used is 2% to 6% of the total mass by weight. The plasticizer comprises one or two of polyethylene glycol, propylene glycol, and glycerol, and is used in an amount of 1% to 4% of the total mass by weight. The stirring conditions were 400 rpm, 70 ℃, and 1 h. The amount of nano-silica used is 0.2% to 0.5% by mass. The mixing conditions were 400 rpm, 40 ℃, and 15~20 min. The insulation condition is 40 ℃.

6. The method for preparing a lignin-chelated zinc rice seed coating agent according to claim 1, characterized in that: In step S5, the mass ratio of coating solution to rice seeds is 1:100~300; The stirring conditions are 100~200 rpm, temperature 25~40 ℃, and stirring time 5~10 min; The preferred low-temperature environment is 0~5℃, and the preferred air-drying time is 48 h.

7. A coating agent prepared by a method for preparing a lignin-chelated zinc rice seed coating agent, characterized in that: The application of the lignin-chelated zinc rice seed coating agent in improving seed germination ability, promoting seedling survival, and alleviating stress.

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