Windmill-shaped alpha-Fe2O3 / Ag nano hybrid material, preparation method thereof and application of windmill-shaped alpha-Fe2O3 / Ag nano hybrid material in relieving plant salt stress

Abstract

The invention discloses a windmill-shaped alpha-Fe2O3 / Ag nano hybrid material and a preparation method and application thereof in relieving plant salt stress, and the method comprises the following steps: mixing fusiform alpha-Fe2O3 prepared by a forced hydrolysis method with silver acetate, then carrying out ball milling treatment, and then carrying out a high-temperature calcination process to obtain the windmill-shaped alpha-Fe2O3 / Ag nano hybrid material. And the windmill-shaped alpha-Fe2O3 / Ag hybrid structure formed by assembling the fusiform alpha-Fe2O3 and the Ag nanoparticles is obtained. The nano hybrid material has high specific surface area, excellent dispersity and remarkable leaf surface adhesion performance, when the nano hybrid material is applied to plant cultivation, the material can effectively relieve growth inhibition caused by salt stress, can regulate and control plant hormone signals, terpene and carbohydrate metabolism, sulfur metabolism, protein homeostasis and the like, realizes multi-channel comprehensive regulation, and has a wide application prospect. Therefore, the plant stress resistance and quality are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of plant stress regulation and nano-agriculture technology, and particularly relates to a windmill-shaped alpha-Fe2O3 / Ag nano-hybrid material, a preparation method thereof and application thereof in relieving salt stress of plants. BACKGROUND

[0002] Since the 21st century, with the intensification of global climate change and soil degradation, soil salinization has become a major problem restricting agricultural production and ecological environment safety. Salt stress not only leads to water absorption obstruction and ion toxicity of plants, but also causes cell membrane lipid peroxidation, photosynthetic system damage, and growth and quality decline, which seriously threatens the stable yield of food crops and the accumulation of effective components of medicinal plants. Traditional methods for relieving salt stress mainly include breeding salt-tolerant varieties, applying chemical modifiers and regulators, etc., but they generally have the disadvantages of long cycle, high cost or ecological risk, which are difficult to meet the sustainable development needs of modern agriculture.

[0003] In recent years, nano-agriculture technology as a new means has attracted widespread attention. Some metal oxide nanomaterials such as SiO2, ZnO and CeO2 have been proved to be able to improve the stress resistance of plants to some extent and regulate nutrient utilization. However, existing nanomaterials are often single in structure, which is difficult to meet the needs of efficient adsorption, leaf adhesion and multi-pathway regulation at the same time, and their action mechanisms are mostly superficial, lacking systematic explanation.

[0004] Therefore, it is of great significance to develop a new type of nanomaterial with unique structure, multiple functions and easy application, and to clarify its multi-level regulation mechanism in relieving salt stress of plants, for improving the quality of medicinal plants and realizing green development of agriculture. SUMMARY

[0005] In view of the shortcomings and deficiencies of the prior art, the purpose of the present application is to provide a windmill-shaped alpha-Fe2O3 / Ag nano-hybrid material, which can be used as a foliar spray agent for plants to effectively relieve the inhibition of salt stress on plant growth. Through this technology, not only the growth and development of plants can be significantly improved, but also the physiological and metabolic processes at multiple levels can be regulated, thereby enhancing the stress resistance and quality of plants.

[0006] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0007] A windmill-shaped alpha-Fe2O3 / Ag nano-hybrid material, the material has unique structural characteristics, with silver nanospheres as the core, uniform loading of spindle-shaped alpha-Fe2O3 nanoparticles on the periphery to form a windmill-shaped morphology, Fe, O and Ag elements are uniformly distributed in the material matrix, Ag element is in the form of Ag 0Primarily, Ag is present at the junction of α-Fe2O3 and silver nanospheres. + The O element exists in three different coordination environments. This structure endows the material with a large specific surface area, good dispersibility and excellent leaf adhesion properties, which is conducive to its efficient delivery and action in plants.

[0008] This invention also provides a method for preparing windmill-shaped α-Fe2O3 / Ag nanohybrid materials. This method involves a combined process of forced hydrolysis, ball milling, and high-temperature calcination to prepare the windmill-shaped α-Fe2O3 / Ag nanohybrid materials. The specific steps are as follows: First, spindle-shaped α-Fe2O3 nanoparticles are synthesized using forced hydrolysis; then, the α-Fe2O3 nanoparticles are mixed with silver acetate and added to agate balls of different sizes, and ball-milled in a planetary ball mill at a speed of 500-600 Hz for 20-40 minutes; subsequently, the ball-milled product is transferred to a tube furnace and calcined at 150-250℃ for 1-3 hours under a nitrogen or argon atmosphere to obtain a windmill-shaped hybrid structure consisting of a silver nanosphere core and a spindle-shaped α-Fe2O3 periphery.

[0009] As a preferred embodiment of the present invention, the α-Fe2O3 nanoparticles have an average length of 115.79 nm and an average diameter of 36.33 nm, and the silver nanospheres have a diameter of 50-70 nm.

[0010] As a preferred embodiment of the present invention, the mass ratio of the α-Fe2O3 nanoparticles to Ag is (0.05-0.20):1.

[0011] As a preferred embodiment of the present invention, the agate balls of different sizes include large balls and small balls, wherein the diameter of the large balls is 1.0 cm and the diameter of the small balls is 0.608 cm, and there are 10 large balls and 10 small balls.

[0012] This invention, by applying this nano-hybrid material to plants under salt stress conditions, can significantly increase root length and biomass, reduce membrane lipid peroxidation and electrolyte leakage, restore chlorophyll content, and restore antioxidant enzyme activity to a steady-state level; therefore, it can be used as a plant growth regulator to alleviate plant salt stress.

[0013] As a preferred embodiment of the present invention, when the windmill-shaped α-Fe2O3 / Ag nano-hybrid material is used as a plant growth regulator to alleviate plant salt stress, the specific method of use is as follows: the prepared windmill-shaped α-Fe2O3 / Ag nano-hybrid material is dispersed in deionized water to prepare a foliar spray solution with a concentration range of 50-200 mg / L, and sprayed evenly on the leaves during the leaf expansion period of the plant, once every 7-10 days.

[0014] The application collects ginseng root samples of different treatment groups, and performs LC-MS / MS metabolomics detection, research shows that the pinwheel-shaped alpha-Fe2O3 / Ag nano hybrid material can regulate ginseng metabolites (terpene synthesis, carbohydrate metabolism and glutathione metabolism); therefore, it can be applied in the preparation of a medicament for regulating ginseng metabolites.

[0015] As a preferred embodiment of the application, the ginseng metabolites include primary metabolites and secondary metabolites, the primary metabolites include carbohydrates and glutathione, and the secondary metabolites include terpenes and lignin.

[0016] The application collects ginseng root samples of different treatment groups, and performs RNA-Seq transcriptome sequencing, research shows that the pinwheel-shaped alpha-Fe2O3 / Ag nano hybrid material can also regulate plant hormone signal transduction, effectively activate the signal pathways related to ABA (abscisic acid), IAA (indole acetic acid) and JA (jasmonic acid), and therefore, it can be applied as an activator in the activation of the plant hormone signal pathways related to ABA, IAA and JA.

[0017] Advantages and beneficial effects of the application:

[0018] 1. Improve the salt tolerance of plants. The pinwheel-shaped alpha-Fe2O3 / Ag nano hybrid material provided by the application has a high specific surface area, excellent dispersibility and significant leaf surface adhesion performance. By spraying the pinwheel-shaped alpha-Fe2O3 / Ag nano hybrid material on the leaves, the adverse effects of salt stress on plant growth are significantly alleviated. Compared with the control group, the plants in the treatment group exhibit stronger salt tolerance under salt stress, and the root length, chlorophyll content and biomass are effectively restored, and the oxidative damage and electrolyte leakage are significantly reduced.

[0019] 2. Regulate plant multi-level metabolism and signal pathways. The novel nano hybrid material provided by the application can comprehensively alleviate salt stress by regulating the metabolic process and signal pathways of plants. Metabolomics and transcriptomics analysis shows that the nano hybrid material can activate the hormone signal transduction (ABA, JA, IAA) of plants, promote terpene and carbohydrate metabolism, enhance sulfur metabolism and protein homeostasis regulation, coordinate the growth and stress response of plants, and play a comprehensive regulation role, thereby improving the overall stress resistance and quality of plants, and overcoming the limitations of existing nano materials with single function and unclear regulation mechanism.

[0020] 3. Optimize the application concentration and use conditions. The nano material described in the application has good concentration adaptability. By adjusting the spraying concentration (50-200 mg / L) and application frequency (once every 7-10 days), the best alleviation effect can be obtained under different environmental conditions, which not only helps to improve the growth performance and production performance of plants in saline environments, but also facilitates flexible promotion in actual agricultural production.

[0021] 4. The unique structure and superior performance. The nanohybrid material provided by the application has a windmill-like hierarchical structure composed of a silver nanosphere core and an alpha-Fe2O3 nanospine periphery, has a large surface area, good dispersity, and strong leaf surface adhesion (a surface energy test value of 65.48 mN / m), is conducive to efficient action on plant leaves, improves the utilization rate, and reduces the application dose.

[0022] 5. Environmental friendliness and wide application prospect. The material described in the application is synthesized by using common compounds, has simple process and low cost, and has good biological compatibility and environmental friendliness. The technology has good economy and scalability, is suitable not only for the cultivation of medicinal plants (such as ginseng), but also can be popularized to the improvement of saline-alkali land and green yield increase of other crops, has a wide agricultural application prospect, and provides effective technical support for sustainable agricultural development.

[0023] 6. The alpha-Fe2O3 / Ag nanohybrid material provided by the application not only can effectively improve the salt tolerance of medicinal plants and crops, but also provides a new idea for the application of nanomaterials in plant multi-level metabolic regulation, and overcomes the shortcomings of single regulation mechanism and limited relief effect in the prior art.

[0024] 7. The alpha-Fe2O3 / Ag nanohybrid material provided by the application effectively regulates the primary metabolism (such as carbohydrate metabolism and sulfur metabolism) and secondary metabolism (such as terpenoid and lignin synthesis) of ginseng. The primary metabolism regulation is not only conducive to promoting the biomass accumulation of medicinal parts, but also can enhance the stress resistance; in the secondary metabolism regulation, the synthesis of lignin can also optimize the cell wall structure, block the invasion of pathogenic bacteria, reduce the loss of water and nutrients, and improve the adaptability of ginseng in infertile soil. The regulation of the terpenoid synthesis pathway can promote the biosynthesis of ginsenosides, increase the total amount or optimize the proportion of rare ginsenosides, thereby providing a material basis for improving the pharmacological activities such as immune regulation, anti-fatigue and anti-tumor of ginseng, and ensuring the quality stability. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 Structure characterization diagram of the windmill-like alpha-Fe2O3 / Ag nanohybrid material prepared in the embodiments of the application. (A) Schematic diagram of the preparation process; (B) XRD spectrum; (C, D) Transmission electron microscope images; (E) High-resolution transmission electron microscope image; (F) Dark field scanning transmission electron microscope image and corresponding element distribution diagram; (G) Fe element distribution; (H) O element distribution; (I) Ag element distribution.

[0026] Figure 2XPS photoelectron spectrum of the α-Fe2O3 / Ag nanohybrid material prepared in the embodiment of the present application. (A) full spectrum; (B) high-resolution energy spectrum of Fe element; (C) high-resolution energy spectrum of Ag element; (D) high-resolution energy spectrum of O element.

[0027] Figure 3 Effects of the α-Fe2O3 / Ag nanohybrid material on plant growth and physiological indexes under salt stress. (A) overall growth state of the plant; (B) determination results of growth indexes; (C) antioxidant enzyme activity; (D) malondialdehyde content; (E) electrolyte leakage rate; (F) soluble sugar content; (G) proline content; (H) chlorophyll content.

[0028] Figure 4 Analysis results of plant root metabolome under the treatment of the α-Fe2O3 / Ag nanohybrid material. (A) classification and composition of metabolites; (B) principal component analysis; (C) comparison results of differential metabolites; (D) KEGG pathway enrichment analysis of differential metabolites.

[0029] Figure 5 Analysis results of plant root transcriptome under the treatment of the α-Fe2O3 / Ag nanohybrid material. (A) comparison results of differential genes; (B) GO annotation analysis of differential genes; (C) KEGG pathway enrichment analysis of differential genes.

[0030] Figure 6 Schematic diagram of typical metabolic pathways regulated by the α-Fe2O3 / Ag nanohybrid material in the plant root. (A) unsaturated fatty acid biosynthesis related pathway; (B) ubiquitin-mediated protein degradation related pathway; (C) sulfur metabolism related pathway.

[0031] Figure 7 Schematic diagram of the effect of the α-Fe2O3 / Ag nanohybrid material on enhancing plant salt tolerance through multiple pathways. (A) Wayne analysis of differential metabolites; (B) Wayne analysis of differential genes; (C) expression profile of hormone signal transduction related genes; (D) expression profile of terpenoid biosynthesis related genes; (E) expression profile of carbohydrate metabolism related genes.

[0032] Figure 8 Schematic diagram of the effect of the α-Fe2O3 / Ag nanohybrid material on regulating plant root homeostasis under salt stress. (A) Wayne analysis of differential metabolites; (B) Wayne analysis of differential genes; (C) expression profile of lignin synthesis related genes; (D) expression profile of glutathione metabolism related genes; (E) expression profile of fatty acid synthesis and degradation related genes.

[0033] Figure 9The schematic diagram of the effects of the pinwheel-like α-Fe2O3 / Ag material and the Fe2O3 material alone on the plant growth and physiological responses under salt stress. (A) Comparison of root fresh weight, root length and plant height; (B) Change of MDA content. DETAILED DESCRIPTION

[0034] In order to better understand the purpose, structure and function of the present application, the preparation method and application of a pinwheel-like α-Fe2O3 / Ag nano-hybrid material for regulating plant growth and relieving salt stress will be further described in detail below in combination with the drawings.

[0035] Example 1: Preparation and characterization of the pinwheel-like α-Fe2O3 / Ag nano-hybrid material

[0036] In this example, the pinwheel-like α-Fe2O3 / Ag nano-hybrid material was prepared by a forced hydrolysis, ball milling and high-temperature calcination combined process. First, spindle-like α-Fe2O3 nanoparticles were prepared by a forced hydrolysis method (referring to the existing method); then 0.078 g of α-Fe2O3 and 0.78 g of silver acetate were mixed and added to a marver jar, and a certain amount of marver balls of different sizes (10 large balls and 10 small balls, size: large ball diameter 1.0 cm, small ball diameter 0.608 cm) were added, and the mixture was ball milled in a planetary ball mill at a speed of 500-600 Hz for 20-40 minutes (in this example, the ball milling was carried out at a speed of 550 Hz for 30 minutes); the ball milled product was transferred to a tube furnace and calcined at 150-250℃ for 1-3 hours under a nitrogen or argon atmosphere (in this example, the calcination was carried out at about 200℃ for 2 hours), obtaining a pinwheel-like hybrid structure material with silver nanoballs as the core and spindle-like α-Fe2O3 uniformly loaded on the periphery.

[0037] In this example, the average length of the spindle-like α-Fe2O3 nanoparticles was 115.79 nm, the average diameter was 36.33 nm, the diameter of the silver nanoballs was 50-70 nm, and the mass ratio of the α-Fe2O3 nanoparticles to Ag was (0.05-0.20):1.

[0038] Transmission electron microscopy (TEM) showed that the material had a pinwheel-like appearance Figure 1 A-E); scanning transmission electron microscopy combined with energy dispersive spectroscopy (STEM-EDS) results showed that the elements Fe, O and Ag were uniformly distributed in the matrix of the material Figure 1 F-I). X-ray photoelectron spectroscopy (XPS) further confirmed the valence state and coordination chemical environment of the elements Fe, Ag and O in the material Figure 2 A-D), in which the peak position of Fe was at 710.63 eV and 724.44 eV, corresponding to Fe 2p 3 / 2 and Fe 2p 1 / 2 , both of which were Fe in α-Fe2O3.3+ The characteristic peaks of Ag. The high-resolution XPS peak position of Ag is at 367.68 eV and 373.68 eV, which is attributed to metallic silver element (Ag 0 ); the peak position binding energy is at 368.58 eV and 374.48 eV, which is attributed to the characteristic peak of Ag + species; the two peaks at 366.88 eV and 372.88 eV correspond to the electron-rich silver, which is derived from the interface charge transfer of Fe2O3 and Ag. The XPS results show that Ag 0 and Ag + coexist, which indicates the reconstruction of the interface of the hybrid material and the strong interaction existing in the interface. There are three different coordination environments of O element, and the characteristic peak binding energy is at 529.52 eV, 530.93 eV and 532.18 eV, which corresponds to the grain boundary oxygen of α-Fe2O3, the surface oxygen species adsorbed by the catalyst and the adsorbed water molecules. It shows that the structure of the hybrid material is stable and successfully constructed.

[0039] Example 2: Leaf spraying of windmill-shaped α-Fe2O3 / Ag nanohybrid material

[0040] The nanohybrid material obtained in Example 1 was dispersed in deionized water to prepare a leaf spraying solution with a concentration of 100 mg / L. During the leaf expansion period of the ginseng seedlings, the solution was uniformly sprayed on the leaves of the ginseng seedlings once every 7-10 days.

[0041] Salt stress simulation: Under greenhouse conditions, a salt stress model was established by gradually increasing the concentration of NaCl. Specifically, the concentration of NaCl in the soil was increased to 200 mM within three days, and the salt stress state was maintained. The control group, the salt stress group, the α-Fe2O3 / Ag treatment group and the salt stress + α-Fe2O3 / Ag treatment group were set up for comparison. The results are shown in Figure 3 A-B, under salt stress (NaCl group), the growth of plants was significantly inhibited, and the root fresh weight, root length and plant height were significantly lower than those of the CK group; the plants in the treatment group (NaCl + Fe-Ag group, i.e. spraying the nanohybrid material of the present example under salt stress) showed growth recovery, and the root length, plant height and root fresh weight (biomass) were significantly improved compared with the untreated salt stress group, indicating that the nanohybrid material of the present example can alleviate the inhibition of salt stress on plant growth and improve the growth of plants under salt stress; there was no significant difference in root fresh weight, root length and plant height between the Fe-Ag group and the control group (CK), indicating that the nanohybrid material of the present example has no obvious inhibition or promotion effect on the normal growth of plants, and is safe to use.

[0042] The physiological indexes of each group of plants were detected after salt stress treatment, including chlorophyll content, membrane lipid peroxidation product (MDA), electrolyte leakage rate (REL), antioxidant enzyme activity (SOD, POD, CAT), proline and soluble sugar content, etc., to investigate the regulation effect of the nano hybrid material of the example on the physiological indexes. The results are as follows Figure 3 As shown by C-H, under the condition of salt stress (NaCl group), the antioxidant enzyme activity (SOD, POD, CAT) was significantly higher than the normal level, the membrane lipid peroxidation product (MDA) and electrolyte leakage rate (REL) were significantly increased, at the same time, the proline and soluble sugar content were also significantly increased, and the chlorophyll content was significantly reduced; after spraying the feathery α-Fe2O3 / Ag (NaCl+Fe-Ag group), the antioxidant enzyme activity (SOD, POD, CAT) returned to the steady state level, the chlorophyll content was restored, and at the same time, the membrane lipid peroxidation product (MDA), electrolyte leakage rate (REL), proline and soluble sugar content were also significantly reduced compared with the salt stress. Thus, it is shown that the material of the application can maintain the redox balance, improve the oxidative damage, enhance the osmotic regulation ability, improve the salt tolerance of plants, and help the plants to survive and grow better in the salt stress environment.

[0043] Example 3: Regulation effect on plant root metabolism

[0044] LC-MS / MS metabolomics detection and RNA-Seq transcriptome sequencing were performed. KEGG pathway enrichment analysis was performed on the differential metabolites and differential genes, focusing on key pathways such as hormone signal transduction, terpenoid and carbohydrate metabolism, sulfur metabolism, protein homeostasis and lipid metabolism.

[0045] Plant root samples of different treatment groups were collected, and UHPLC-MS / MS was used for metabolite detection of plant roots. KEGG pathway enrichment analysis was performed on the differential metabolites. The results showed that the treatment group sprayed with feathery α-Fe2O3 / Ag and the salt stress group were significantly separated in the metabolic profile. The differential metabolites were mainly concentrated in the pathways of terpenoid synthesis, carbohydrate metabolism and glutathione metabolism, suggesting that the material could coordinate the growth and stress response of plants by regulating the accumulation of key metabolites, and improve the metabolic balance of plants under salt stress (see Figure 4 ).

[0046] Example 4: Regulation effect on plant gene expression

[0047] The root samples of plants in different treatment groups are collected, and the gene expression of the ginseng roots under different treatments is analyzed by using RNA-Seq transcriptome sequencing, and KEGG pathway enrichment analysis is performed on the differential genes. The results show that the genes related to hormone signals under salt stress are generally down-regulated, and are obviously recovered after the windmill-shaped alpha-Fe2O3 / Ag treatment. The signal pathways related to ABA, JA and IAA are effectively activated, which indicates that the material can regulate the hormone signal pathway, coordinate the growth and stress response of the plant, and improve the salt tolerance (see Figure 5 ).

[0048] Example 5: Multi-pathway regulation mechanism

[0049] Further analysis shows that the windmill-shaped alpha-Fe2O3 / Ag material can regulate the pathways of lignin synthesis, glutathione metabolism, unsaturated fatty acid metabolism, ubiquitin-mediated protein degradation and sulfur metabolism under salt stress. The expression of related genes changes obviously, which helps to maintain the stability of cell membrane and the redox homeostasis, thereby enhancing the adaptability of the plant under salt stress (see Figure 6-8 ).

[0050] Through the experiments of the above examples, the excellent performance of the windmill-shaped alpha-Fe2O3 / Ag nanohybrid material in plant growth regulation and salt tolerance improvement is verified, and the mechanism thereof involves the improvement of redox balance, the accumulation of osmotic adjustment substances, the regulation of metabolic pathways and the activation of plant hormone signal system. Therefore, the alpha-Fe2O3 / Ag nanohybrid material provided by the present application can be widely applied in the research and application of plant growth regulators and salt-resistant materials.

[0051] In this embodiment, Figure 1 The structural characterization results of the windmill-shaped alpha-Fe2O3 / Ag nanohybrid material are shown. Figure (A) is a schematic diagram of the preparation of the nanohybrid material, which illustrates the synthesis steps and formation process. Figure (B) is an XRD spectrum, which proves the crystal structure of the material. Figures (C) and (D) are transmission electron microscope (TEM) images, which show the windmill-shaped morphology of the nanoparticles. Figure (E) is a high-magnification TEM image, which reveals the fine structural features of the nanoparticles. Figure (F) is a scanning transmission electron microscope (STEM) image, and Figures (G), (H) and (I) are the energy spectrum mapping results of Fe, O and Ag elements, respectively, which verify the uniformity of the element distribution in the material.

[0052] Figure 2 The photoelectron spectroscopy characterization of the alpha-Fe2O3 / Ag nanohybrid material is shown. Figure (A) is a full spectrum, which shows the element composition on the surface of the material. Figures (B), (C) and (D) are high-resolution XPS spectra of Fe, Ag and O elements, respectively, which further reveal the valence state and binding state of each element in the material.

[0053] Figure 3 The effect of the α-Fe2O3 / Ag nanohybrid material on the growth and physiological response of plants under salt stress conditions is shown. Figure (A) is the overall growth of the plants, which shows that the growth state of the plants in the treatment group is obviously improved compared with the salt stress group. Figure (B) is the growth index, such as plant height and root length. Figure (C) shows the antioxidant enzyme activity, and the enzyme activity in the treatment group returns to the steady state level. Figure (D) is the content of malondialdehyde (MDA), which is reduced after treatment. Figure (E) is the electrolyte leakage rate (REL), which is reduced after treatment. Figures (F) and (G) are the contents of soluble sugar and proline, respectively, which are reduced in the treatment group. Figure (H) is the chlorophyll content, which is higher in the treatment group than in the salt stress group.

[0054] Figure 4 The regulation of the α-Fe2O3 / Ag material on the metabolic profile of the plant root system is shown. Figure (A) is the classification and composition of metabolites; Figure (B) is the principal component analysis (PCA), which shows the differences in the metabolic profile of different treatment groups; Figure (C) is the comparison result of the differential metabolites, which shows that, by comparing Fe-Ag vs. CK, after Fe-Ag treatment, 114 are significantly up-regulated, and 146 are significantly down-regulated, indicating that the nanohybrid material of the application can obviously interfere with the metabolism of plants; by comparing NaCl vs. CK, it can be seen that the salt stress (NaCl) has a strong disturbance on the metabolism, and the change range of the metabolites is larger; by comparing NaCl+Fe-Ag vs. NaCl, it can be seen that the nanohybrid material of the application can obviously change the influence of salt stress on the metabolic level of plants; Figure (D) is the KEGG pathway enrichment analysis of the differential metabolites, which shows that the α-Fe2O3 / Ag mainly affects the terpenoid, carbohydrate and glutathione metabolic pathways.

[0055] Figure 5 The regulation of the α-Fe2O3 / Ag material on the transcriptional profile of the plant root system is shown. Figure (A) is the comparative analysis of the differential genes, which reveals the differences in gene expression among different treatment groups. Figure (B) is the GO annotation analysis, which shows that the differential genes are involved in various biological processes. Figure (C) is the KEGG enrichment analysis, which shows that the α-Fe2O3 / Ag treatment significantly affects the hormone signal and metabolic pathways.

[0056] Figure 6 The role of the α-Fe2O3 / Ag material in specific metabolic and signal pathways is shown. Figure (A) is the related pathway of unsaturated fatty acid biosynthesis; Figure (B) is the ubiquitin-mediated protein degradation pathway; Figure (C) is the sulfur metabolic pathway. The results show that the α-Fe2O3 / Ag treatment can regulate these key pathways to enhance salt tolerance.

[0057] Figure 7The mechanism of α-Fe2O3 / Ag material in enhancing plant salt tolerance through multiple pathways is demonstrated. Figures (A) and (B) are the Wayne analysis of differential metabolites and differential genes, respectively, showing the molecules that are down-regulated under NaCl stress but restored after α-Fe2O3 / Ag treatment. Figure (C) is the expression profile of hormone signal transduction-related genes; Figure (D) is the expression profile of terpenoid biosynthesis-related genes; Figure (E) is the expression profile of carbohydrate metabolism-related genes; it is illustrated that the material plays a role in multiple pathways.

[0058] Figure 8 The effect of α-Fe2O3 / Ag material on plant root homeostasis regulation is demonstrated. Figures (A) and (B) are the Wayne analysis of differential metabolites and differential genes, respectively, revealing its recovery effect under NaCl stress. Figure (C) is the expression profile of lignin synthesis-related genes; Figure (D) is the expression profile of glutathione metabolism-related genes; Figure (E) is the expression profile of fatty acid synthesis and degradation-related genes; it is illustrated that the material can maintain cell membrane stability and improve antioxidant capacity.

[0059] Figure 9 The effects of windmill-shaped α-Fe2O3 / Ag material and Fe2O3 alone on the growth and physiological response of ginseng plants under salt stress are demonstrated. Figure (A) shows the changes in root fresh weight, root length, and plant height, and the results show that, compared with Fe2O3 material alone, the windmill-shaped α-Fe2O3 / Ag material significantly promotes the root growth and overall growth of the plants, and the root fresh weight, root length, and plant height are all increased. Figure (B) demonstrates the malondialdehyde (MDA) content, and the windmill-shaped α-Fe2O3 / Ag material effectively reduces the MDA content, significantly reducing oxidative damage, while the antioxidant effect of Fe2O3 material alone is relatively weak. These data show that the windmill-shaped α-Fe2O3 / Ag material has significant advantages over Fe2O3 material alone in promoting plant growth, reducing oxidative damage, and improving osmotic regulation capacity, thereby effectively improving the salt tolerance of plants.

[0060] In summary, the present application provides a plant growth regulator that utilizes windmill-shaped α-Fe2O3 / Ag nanohybrid material to regulate plant growth and improve salt tolerance. By applying the hybrid material to plants, their growth performance under salt stress can be significantly improved, the chlorophyll level is restored, the oxidation-reduction balance is maintained, and the accumulation of osmotic regulation substances is promoted. The application of the material effectively regulates the primary metabolism (such as carbohydrate metabolism and sulfur metabolism) and secondary metabolism (such as terpenoid and lignin synthesis) of plants, and activates the hormone signal pathway (such as ABA, JA, and IAA), thereby enhancing the overall salt tolerance and adaptability of plants. The present application provides a new and efficient regulator for the cultivation of medicinal plants and crops in saline-alkali environments.

[0061] It can be understood that the present application is illustrated by several embodiments, but those skilled in the art can modify, replace or equivalent transform the embodiments without departing from the spirit and scope of the present application. Under the guidance of the present application, relevant parameters, material proportions and application methods can be adjusted and optimized according to different plant species and growth environments, without affecting the core idea of the present application. Therefore, the protection scope of the present application is not limited to the specific embodiments, and any implementation scheme meeting the claims of the present application should be covered within the protection scope of the present application.

Claims

1. A windmill-shaped α-Fe2O3 / Ag nanohybrid material, characterized in that, The material takes silver nanospheres as core, and peripherally uniformly loads spindle-shaped a-Fe2O3 nanoparticles to form windmill-shaped morphology, Fe, O and Ag elements are uniformly distributed in the material matrix, Ag element is mainly in the form of Ag 0 , O element exists in three different coordination environments. + ​ 2. The method for preparing the windmill-shaped α-Fe2O3 / Ag nanohybrid material of claim 1, characterized in that, The method comprises the following steps: firstly, spindle-shaped α-Fe2O3 nanoparticles are synthesized by forced hydrolysis method; then, the α-Fe2O3 nanoparticles are mixed with silver acetate, and then added into different size agate balls, and then ball-milled in a planetary ball mill at a rotating speed of 500-600 Hz for 20-40 minutes; then, the ball-milled product is transferred to a tube furnace, and calcined at 150-250 ℃ for 1-3 hours under nitrogen or argon atmosphere, to obtain a windmill-shaped hybrid structure with a silver nanosphere core and a spindle-shaped α-Fe2O3 periphery.

3. The method for preparing the windmill-shaped α-Fe₂O₃ / Ag nano-hybrid material according to claim 2, characterized in that, The average length of the α-Fe2O3 nanoparticles is 115.79 nm, and the average diameter is 36.33 nm, and the diameter of the silver nanospheres is 50-70 nm.

4. The method for preparing the windmill-shaped α-Fe₂O₃ / Ag nanohybrid material according to claim 2, characterized in that, The mass ratio of the α-Fe2O3 nanoparticles to Ag is (0.05-0.20):

1.

5. The method for preparing the windmill-shaped α-Fe₂O₃ / Ag nanohybrid material according to claim 2, characterized in that, The different size agate balls include large balls and small balls, wherein the diameter of the large balls is 1.0 cm, and the diameter of the small balls is 0.608 cm, and there are 10 large balls and 10 small balls.

6. The windmill-shaped α-Fe2O3 / Ag nanohybrid material prepared by the method of any one of claims 2 to 5 is used as a plant growth regulator to relieve plant salt stress.

7. Use according to claim 6, characterized in that, When the windmill-shaped α-Fe2O3 / Ag nanohybrid material is used as a plant growth regulator to relieve plant salt stress, the specific use method is as follows: the prepared windmill-shaped α-Fe2O3 / Ag nanohybrid material is dispersed in deionized water to prepare a foliar spraying solution, and the concentration is 50-200 mg / L, and the foliar spraying is uniformly carried out on the plant leaves during the leaf expansion period, and the spraying is carried out once every 7-10 days.

8. The windmill-shaped α-Fe2O3 / Ag nanohybrid material prepared by the method of any one of claims 2 to 5 is used in the preparation of a medicament for regulating ginseng metabolites.

9. Use according to claim 8, characterized in that, The ginseng metabolites include primary metabolites and secondary metabolites, the primary metabolites include carbohydrates and glutathione, and the secondary metabolites include terpenoids and lignin.

10. The windmill-shaped α-Fe2O3 / Ag nanohybrid material prepared by the method of any one of claims 2 to 5 is used as an activator to activate the plant hormone signal pathways related to ABA, IAA and JA.

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