CN-122004237-A - PH-bionic trigger type multilayer intelligent seed coating agent for improving salt tolerance of crops and preparation method and application thereof

CN122004237ACN 122004237 ACN122004237 ACN 122004237ACN-122004237-A

Abstract

The invention belongs to the technical field of salt-resistant planting of coastal saline-alkali soil crops, and provides a pH response bionic triggering three-layer intelligent seed coating agent and preparation and application thereof, aiming at the problem of difficult emergence of crops such as saline-alkali soil corn and the like. The invention adopts the idea of 'using the soil as a suitable place', takes the soil acid-base condition as a response signal, constructs a three-layer cooperative coating structure on the surface of the seeds, and improves the salt tolerance of the seeds by regulating the release process by the outer layer. The coating comprises a melatonin-nano selenium active core layer, a pectin-sodium carboxymethyl cellulose-monosaccharide slow release adhesion layer, a water retention buffer layer, a pH response regulating layer, a silk fibroin and chitosan or carboxymethyl chitosan, wherein the melatonin-nano selenium active core layer is used for enhancing antioxidation and defense and promoting ion steady state, the pectin-sodium carboxymethyl cellulose-monosaccharide slow release adhesion layer is used for forming a water retention buffer layer and delaying salt diffusion and continuously releasing active components, and the pH response regulating layer is formed by silk fibroin and chitosan or carboxymethyl chitosan, so that permeability is regulated along with acid-base change, and release according to needs is realized. The three-layer coating maintains Na + /K + balance through the effects of salt resistance, water retention and pH response, and promotes the stable germination and growth of crops in the saline-alkali soil.

Inventors

Li Peichong
ZHENG HAO
LI FENGMIN
LUO XIANXIANG
LIU QIANG
ZHANG HONGYU

Assignees

中国海洋大学

Dates

Publication Date: 20260512
Application Date: 20260130

Claims (10)

1. A pH-bionic trigger type multi-layer intelligent seed coating agent for improving salt tolerance of crops is characterized in that the seed coating agent is covered on the surface of seeds and sequentially comprises a first active core layer, a second slow release adhesion layer and a third pH response type regulating layer from inside to outside, wherein the pH response type regulating layer takes a soil acid-base condition as a response trigger signal, and regulates and controls the release process of an inner salt resistant active component by regulating self permeability.
2. The pH-bionic trigger type multi-layer intelligent seed coating agent for improving salt tolerance of crops according to claim 1, wherein the first active core layer is composed of a melatonin-nano selenium composite material, and melatonin is loaded on the surface of nano selenium in an adsorption, coordination or coating mode to form a stable nano composite system.
3. The pH-bionic trigger type multi-layer intelligent seed coating agent for improving salt tolerance of crops according to claim 1, wherein the second layer of slow release attachment layer is a composite solution composed of pectin, sodium carboxymethyl cellulose and monosaccharide, and a slow release network structure is constructed by ionic crosslinking and is used for realizing slow release of active ingredients and enhancing attachment to the surface of seeds.
4. The pH-bionic trigger type multi-layer intelligent seed coating agent for improving salt tolerance of crops according to claim 1, wherein the third layer of pH response type regulating layer is composed of chitosan or carboxymethyl chitosan serving as a pH response functional component, silk fibroin serving as a structural support material and the chitosan or carboxymethyl chitosan form a composite network, and the composite network is used for regulating swelling property and permeability of the coating layer along with the change of acid-base environment of soil, so that the on-demand regulation and control of the release of inner-layer active components are realized.
5. The pH-triggered multi-layered intelligent seed coating agent for improving salt tolerance of crops according to claim 1, wherein the first active core layer further comprises functional nanoparticles or carbon-based nanoparticles; the functional nano particles are nano magnesium oxide.
6. The method for preparing a pH-biomimetic trigger type multi-layered intelligent seed coating agent for improving salt tolerance of crops according to any one of claims 1 to 5, comprising the steps of sequentially constructing an active core layer, a slow release adhesion layer and a pH responsive regulation layer on the surface of the seeds, wherein the third layer regulates the release process of the inner active ingredient by constructing a composite network structure having pH response characteristics, characterized in that: (1) Preparation of the first active core layer: 1) Taking sodium selenite aqueous solution as a selenium precursor, adding melatonin solution into the sodium selenite aqueous solution, dissolving the melatonin solution by a small amount of ethanol, and diluting to obtain the product; 2) Slowly adding an ascorbic acid solution as a reducing agent under the stirring condition to generate nano-selenium particles, forming a melatonin-nano-selenium composite system at the same time, continuously stirring and reacting for 30-60 min, and regulating the pH value of the system to 6-7 to obtain a stably dispersed melatonin-nano-selenium composite nano-material dispersion; 3) Immersing the seeds into the melatonin-nano selenium composite nano material dispersion liquid to ensure that the seeds are completely immersed into the solution, taking out the seeds after 5-30 min, and drying the seeds in the shade for 2-12 h at a ventilated and dried place to obtain a first seed coating; (2) Preparing a second slow release adhesive layer: 1) Preparing a compound polysaccharide solution by taking pectin and sodium carboxymethyl cellulose as raw materials; 2) Adding a mixed monosaccharide solution into the composite polysaccharide solution, and fully stirring to completely dissolve the mixed monosaccharide solution; 3) Adding calcium chloride solution to regulate the mechanical strength of the hydrogel, standing for 12-h, adding 2-M NaOH solution with 70% pectin molar weight for 24-48 h, immersing the first layer of seed coating obtained in the step (1) into the system to form a hydrogel structure on the surface of the seed, immersing 5-min after the hydrogel is formed, taking out, and performing air drying treatment for 24-48 h to obtain a second layer of hydrogel seed coating with a slow release attachment function; (3) Preparation of a third pH responsive regulatory layer: 1) Preparing a silk fibroin-polysaccharide composite solution according to a required proportion, dissolving polysaccharide by taking an acetic acid aqueous solution with the volume fraction of 0.5% -1.5% as a solvent, and regulating the pH value of the solution to 5.0-5.5; 2) Immersing the second layer coated seed obtained in the step (2) into the silk fibroin-polysaccharide composite solution to enable the surface of the seed to be deposited and form a third layer of outer coating structure, and adding sodium tripolyphosphate into the silk fibroin-polysaccharide composite solution in the coating process or after coating is completed to enable an ion crosslinking or covalent crosslinking network to be formed between silk fibroin and chitosan or carboxymethyl chitosan molecules, so that the silk fibroin-polysaccharide composite regulation layer structure with pH response characteristic is constructed.
7. The method for preparing the pH-bionic trigger type multi-layer intelligent seed coating agent for improving salt tolerance of crops according to claim 6, which is characterized in that: The concentration of the sodium selenite aqueous solution in the step (1) is 0.5-5 mM, the concentration of melatonin is 0.15 mg mL -1 , and the molar ratio of the ascorbic acid to the sodium selenite is 4:1; Or, the functional nano material or the carbon-based nano material is also added into the melatonin-nano selenium composite nano material dispersion liquid in the step (1), wherein the concentration of the functional nano material in the melatonin-nano selenium composite nano material dispersion liquid is 10-100 mg L -1 .
8. The method for preparing the pH-bionic trigger type multi-layer intelligent seed coating agent for improving salt tolerance of crops according to claim 6, which is characterized in that: In the step (2), the mass ratio of pectin to sodium carboxymethylcellulose is 1:1, and the total mass fraction of the compound polysaccharide system is 5-10%; or, in the step (2), the mixed monosaccharide comprises D- (+) -xylose, L- (+) -arabinose, DL-arabinose and L-rhamnose, the molar ratio of the mixed monosaccharide is 30:9:9:14, and the total mass fraction of the monosaccharide is 2-5%; or (2) the final concentration of calcium chloride is 5 mM.
9. The method for preparing the pH-bionic trigger type multi-layer intelligent seed coating agent for improving salt tolerance of crops according to claim 6, which is characterized in that: in the step (3), the polysaccharide is chitosan or carboxymethyl chitosan, and the mass ratio of the silk fibroin to the polysaccharide is 1:3, 3:1 or 1:1; Or, in the above (3), the final concentration of sodium tripolyphosphate is 5 mM.
10. Use of a pH-biomimetic trigger type multi-layer intelligent seed coating agent for improving salt tolerance of crops according to any one of claims 1 to 5, wherein the seed coating agent is used for pre-sowing treatment of crops in saline-alkali soil conditions, and the release of salt-resistant active components is regulated and controlled by responding to the change of the acid-alkali environment of the soil, so that the germination rate of seeds is improved and the salt tolerance of seedlings is enhanced.

Description

PH-bionic trigger type multilayer intelligent seed coating agent for improving salt tolerance of crops and preparation method and application thereof Technical Field The invention belongs to the technical field of coastal saline-alkali soil planting, and particularly relates to a pH-bionic trigger type multi-layer intelligent seed coating agent for improving salt tolerance of crops, and a preparation method and application thereof. Background Along with the increase of global population and the trend of tightly cultivated land resources, the development and utilization of marginal lands such as saline-alkali lands and the like have important strategic significance for guaranteeing national grain safety. The salinized soil in China is widely distributed, for example, coastal areas (such as yellow river delta) are affected by seawater invasion and climatic factors, high-concentration salt (mainly Na+, cl-) in the soil and the frequently-accompanying extreme pH environment can cause serious osmotic stress, ion poisoning and oxidative stress, so that the water absorption of seeds is blocked, the cell metabolism is disordered, the radicle elongation is inhibited, and finally, the emergence rate and the crop yield are seriously reduced. The 'suitable land' is to adapt to the saline-alkali environment by improving the stress resistance of the seeds, and is a key path for sustainable development of the current agriculture. The seed coating technology is used as an important pretreatment means before sowing, and aims to improve the seed germination microenvironment and enhance the early stress resistance by constructing a functional film layer or gel layer on the surface of the seed. However, the existing seed coating technology has obvious limitations in coping with saline-alkali adversity, namely, the existing seed coating technology has single function and insufficient environmental adaptability, the traditional chemical pesticide type coating is mainly used for pest control, has limited improvement on abiotic stress such as salt, drought and the like and has environmental residue risks, and the nutrient element type coating can supplement trace elements, but often has the problems of unstable form of active ingredients, too fast release, asynchronism with seedling demands and the like. Secondly, the film layer has insufficient adhesive force and mechanical stability, and partial coating is easy to be pulverized and fall off in the processes of storage, transportation and mechanical sowing, so that the function is invalid and dust pollution is possibly caused. Thirdly, the intelligent response and controllable slow release mechanism is lacking, the release of active components in most biopolymer coatings mainly depends on simple diffusion, time sequence and on-demand supply are difficult to realize according to the pH value change of soil or the growth stage of seedlings, and the pH fluctuation of saline-alkali soil is large, so that the necessity of environment response regulation is more highlighted. Notably, some mucinous seeds in nature adapt to drought or lean water environments, and their seed coats release polysaccharide mucilage and expand rapidly after water absorption, forming a gelatinous outer layer surrounding the seeds, thereby creating a "seed microenvironment" around the seeds that is conducive to germination. The microenvironment has the functions of preserving water, buffering external solute changes, regulating nutrient migration and the like, and provides a bionic indication for the design of seed coating materials under adverse conditions, and the water and solute conditions around seeds can be improved in a low water potential and high salt environment by constructing a polysaccharide hydrogel layer with water absorption expansion capacity on the surfaces of the seeds, so that the stability of germination and seedling establishment is improved. In the prior study, hydrophilic polysaccharide such as pectin, sodium carboxymethyl cellulose and the like can form a three-dimensional network structure under the ion crosslinking condition, has the characteristics of gelling, water retention and adhesion, is suitable for constructing a coating layer with both slow release and adhesion functions, but the regulation and control of the polysaccharide layer on the release of active ingredients are dependent on a diffusion process, lack of response to external environment signals, and are difficult to realize response release. On the other hand, chitosan and carboxymethyl chitosan are used as natural aminopolysaccharide materials, have good film forming property, adhesiveness and certain bioactivity, are widely applied to agricultural coatings, and meanwhile, show the differences of swelling degree, permeability and network density under different pH conditions due to the protonation and deprotonation behaviors of amino groups and carboxyl groups in molecular chains, and have the material foundation for