Application of nano-manganese ferrite in reducing fat content and increasing yield of tea

Abstract

The present invention discloses the application of nano-manganese ferrite in reducing fat components and increasing yield in tea leaves, belonging to the field of new pesticides. The application of nano-manganese ferrite in reducing fat components and increasing yield in tea leaves described in the present invention is to prepare nano-manganese ferrite into a nano-manganese ferrite solution, which is then applied to tea leaves as a fertilizer by foliar spraying; wherein the nano-manganese ferrite has a particle size of 20-60 nm, an average size of 2.3±14.6 nm, a hydraulic diameter of 538.6±27.2 nm, and a zeta potential of 21.7±1.5 mV; and the concentration of the nano-manganese ferrite solution is 1-50 mg / L. The present invention increases the yield and fat-reducing component content of tea leaves by foliar application of the nano-manganese ferrite solution.

Description

Technical Field

[0001] The invention relates to the application of nano manganese ferrite in reducing fat content and increasing yield of tea, and belongs to the field of new pesticides. Background Art

[0002] Tea, a popular non-alcoholic beverage, is now widely consumed in many countries. Studies have shown that long-term tea consumption can lead to the ingestion of active compounds such as theanine, tea polyphenols, and caffeine. These compounds can inhibit the expression of enzymes involved in fat synthesis, promote fatty acid oxidation, suppress appetite, and inhibit nutrient absorption, thereby contributing to fat loss and weight loss. Therefore, increasing the content of fat-reducing compounds such as theanine, tea polyphenols, and caffeine in green tea provides support for the development of healthy and effective fat-reduction methods.

[0003] Traditional tea garden management primarily relies on the large-scale application of nitrogen (urea, ammonium bicarbonate, ammonium sulfate, ammonia water, ammonium chloride, ammonium nitrate, and calcium nitrate), phosphorus (normal calcium phosphate and double superphosphate, calcium magnesium phosphate, steel slag phosphate, phosphate rock powder, and ammonium phosphate), potassium, magnesium, and sulfur fertilizers, as well as the spraying of pesticides, to improve tea quality and yield and mitigate pest and disease infestations. However, the application of large amounts of chemical fertilizers and pesticides does not correlate with tea yield. Excessive nutrient input can even lead to severe soil acidification, accelerating the loss of nutrients like P, Mg, and K, and the accumulation of harmful metals like Al, leading to an imbalance in soil nutrient structure and deterioration of soil properties.

[0004] Currently, nanomaterials are widely used to improve the quality and yield of crops due to their unique physical and chemical properties. They can improve the yield and quality of crops by enhancing antioxidant capacity and secondary metabolism levels, improving carbon and nitrogen metabolism, and upregulating genes related to abiotic and biotic stresses.

[0005] At present, some researchers use nano-selenium to promote the yield of tea trees (the effect of foliar selenium spraying on the photosynthetic characteristics and yield of tea leaves), use chitosan functionalized nano-selenium composite bacterial enzyme system to improve tea yield and quality (CN111848303A), and some researchers use polymer magnetic materials to increase the content of polysaccharides, brass, and theanine in tea (CN113519334A); however, some of these methods are soil applications, which inevitably reduce the efficiency of the materials, while others are applied at too high a concentration, which increases the cost; therefore, there is an urgent need to find new materials that can be used in small quantities and efficiently to improve the yield and quality of tea. Summary of the Invention

[0006] [Technical Issues]

[0007] Current methods for improving tea quality and yield suffer from high material consumption and costs. Furthermore, it remains unclear whether synthetic MnFe2O4 NMs can effectively increase tea yield or enhance the fat-reducing properties of tea. What is the optimal concentration?

[0008] [Technical solution]

[0009] In order to solve the above problems, the present invention prepares nano manganese ferrite into a solution, which is applied to tea trees through the leaves as a fertilizer for cultivation, so as to increase tea yield and improve the fat-reducing component.

[0010] The first object of the present invention is to provide an application of nano manganese ferrite in reducing fat content and increasing yield of tea. The application is to prepare nano manganese ferrite into a nano manganese ferrite solution, which is then applied as a fertilizer on tea leaves by foliar spraying.

[0011] In one embodiment of the present invention, the particle size of the nano manganese ferrite is 20-60 nm, the average size is 2.3±14.6 nm, the hydraulic diameter is 538.6±27.2 nm, and the Zeta potential is -21.7±1.5 mV.

[0012] In one embodiment of the present invention, the nano-manganese ferrite solution is a nano-manganese ferrite aqueous solution with a concentration of 1-50 mg / L.

[0013] In one embodiment of the present invention, the amount of the nano manganese ferrite solution applied is 200-300 mL / (time·m 2 ), spray once every 2-3 days, spray 1-4 times in total; spray time is selected from 9:00 to 11:00 in the morning, and try to ensure that the leaves are sprayed evenly on the back.

[0014] In one embodiment of the present invention, the application period is before the spring buds germinate, generally 20-30 days before the regular picking time.

[0015] In one embodiment of the present invention, it is ensured that there is no rain for 4 hours after the nano-manganese ferrite solution is applied.

[0016] In one embodiment of the present invention, the tea tree is a Fuding Dabaicha tea tree.

[0017] In one embodiment of the present invention, the preparation method of nano manganese ferrite comprises the following steps:

[0018] Manganese (II) chloride tetrahydrate (MnCl2·4H2O, AR, 99%) and iron (III) chloride hexahydrate (FeCl3·6H2O, AR) were stirred in ethylene glycol (CH2OH)2 until completely dissolved to obtain a mixed solution of manganese ions and iron ions;

[0019] Dissolve NaOH in water to obtain NaOH solution;

[0020] NaOH solution was added to the mixed solution to adjust the pH to 11; after sufficient stirring, the mixture with a pH of 11 was heated at 200°C for 12 hours, cooled, and freeze-dried in a vacuum to obtain nano-manganese ferrite (MnFe2O4 NMs);

[0021] The molar ratio of manganese (II) chloride tetrahydrate to iron (III) chloride hexahydrate is 1:2;

[0022] The usage ratio of manganese (II) chloride tetrahydrate, iron (III) chloride hexahydrate and ethylene glycol is 3.968 g:10.8 g:40 mL.

[0023] A second object of the present invention is a method for increasing the content of polyphenols, catechins, flavonols, anthocyanins, purine alkaloids, non-protein amino acids and some volatile aromatic products in tea leaves by improving photosynthesis, wherein the method comprises preparing nano-manganese ferrite into a nano-manganese ferrite solution, which is then applied to tea leaves as a fertilizer by foliar spraying;

[0024] Among them, the particle size of nano-manganese ferrite is 20-60nm, the average size is 2.3±14.6nm, the hydraulic diameter is 538.6±27.2nm, and the Zeta potential is -21.7±1.5mV;

[0025] The nano manganese ferrite solution is a nano manganese ferrite aqueous solution with a concentration of 1-50 mg / L;

[0026] The application amount of nano manganese ferrite solution is 200-300mL / (time·m 2 ), spray once every 2-3 days, a total of 1-4 times; spraying time is 9:00-11:00 in the morning;

[0027] The application period is before the spring buds germinate, generally 20-30 days before the regular picking time.

[0028] A third object of the present invention is to provide a method for improving tea quality and yield by increasing the relative abundance of Proteobacteria, Acidobacteria, and Actinobacteria, wherein the method comprises preparing a nanomanganese ferrite solution and applying the solution as a fertilizer to tea leaves by foliar spraying.

[0029] Among them, the particle size of nano-manganese ferrite is 20-60nm, the average size is 2.3±14.6nm, the hydraulic diameter is 538.6±27.2nm, and the Zeta potential is -21.7±1.5mV;

[0030] The nano manganese ferrite solution is a nano manganese ferrite aqueous solution with a concentration of 1-50 mg / L;

[0031] The application amount of nano manganese ferrite solution is 200-300mL / (time·m 2 ), spray once every 2-3 days, a total of 1-4 times; spraying time is 9:00-11:00 in the morning;

[0032] The application period is before the spring buds germinate, generally 20-30 days before the regular picking time.

[0033] [Beneficial Effects]

[0034] (1) The present invention increases tea yield and fat-reducing ingredient content by applying nano-manganese ferrite solution to the leaves. Treatment with 10 mg / LMnFe2O4 NMs increased fresh weight (FW) by 34.3%, dry weight (DW) by 121.1%, total yield by 27.8% in fresh weight determination, and soluble content by 38.1%. The fat-reducing ingredients theanine, EGCG, total catechins, and caffeine in tea buds increased by 21.9%, 55.3%, 77.8%, and 10.1%, respectively. The contents of Mg, P, S, and K in tea buds increased by 20.0%, 9.9%, 6.8%, and 8.3%, respectively.

[0035] (2) The addition of MnFe2O4 NMs changed certain specific bacterial groups. At the genus level, the relative abundance of Acidibacter, Roseiarcus, Acidipila, Subgroup-13, Bryobacter, and Acidothermus increased significantly. These bacteria can promote soil nitrogen fixation and the utilization of soil available phosphorus, and exert plant-microorganism interactions to improve the utilization efficiency of nutrients.

[0036] (3) The addition of MnFe2O4 NMs caused the contents of 23 metabolites related to the quality of Fuding Dabai tea to change with significant differences. The differential metabolites included 8 amino acids, 2 alkaloids, 8 polyphenols and 5 organic acids (citric acid, malic acid, fumaric acid, succinic acid pyruvic acid), of which 19 metabolites were up-regulated and 4 metabolites were down-regulated. This was mainly due to the fact that the application of MnFe2O4 NMs significantly improved the photosynthesis of plants, increased the photosynthetic products, and enabled plants to utilize more glucose for subsequent glycolysis, thereby further promoting the synthesis of subsequent amino acids (glutamic acid, arginine, tryptophan, theanine, etc.) and antioxidant active substances (caffeine, catechin compounds). BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 TEM image (A) and XRD pattern (B) of nano-manganese ferrite (MnFe2O4 NMs) in Example 1.

[0038] Figure 2 Properties of tea leaves treated with different concentrations of MnFe2O4 NMs aqueous solutions; (A) fresh weight (FW) and dry weight (DW) of 100 buds of Fuding Dabai tea; (B) total tea yield; (C) soluble sugar content of tea leaves.

[0039] Figure 3 The properties of tea leaves treated with MnFe2O4 NMs aqueous solutions at different concentrations; (A) changes in theanine, EGCG, and caffeine contents; (B) changes in the contents of ester and non-ester catechins.

[0040] Figure 4 The performance comparison between Example 2 and Comparative Examples 1-3 shows (A) changes in theanine, EGCG, and caffeine content; and (B) changes in the ester and non-ester catechin content.

[0041] Figure 5 This figure shows the changes in the metabolic profile of Fuding Dabaicha tea buds after application of MnFe2O4 NMs in Example 2. The abbreviations in the figure represent the following: GAP: glyceraldehyde-3-phosphate; PEP: phosphoenolpyruvate; PRPP: ribose phosphate pyrophosphate; 2-OG: 2-oxoglutarate; TCA: tricarboxylic acid cycle; Gs: glutamine; Glu: glutamate; EGCG: epigallocatechin gallate; ECG: epicatechin gallate. Up and down arrows next to the boxes indicate metabolites with significantly increased / decreased levels after MnFe2O4 NM treatment compared to CK treatment.

[0042] Figure 6 The relative abundance of the phylum level of the dominant bacterial community in the rhizosphere of Fuding Dabai tea after the application of MnFe2O4 NMs in Example 2 (A) and the relative abundance of the genus level of the dominant bacterial community in the rhizosphere (B). DETAILED DESCRIPTION

[0043] The following describes preferred embodiments of the present invention. It should be understood that the embodiments are for better explanation of the present invention and are not intended to limit the present invention.

[0044] Test method:

[0045] 1. TEM test:

[0046] The size and morphology of NMs were observed using TEM (JEM-2100, Nippon Electronics co, JPN, accelerating voltage 200 kV).

[0047] 2. Test of hydrodynamic diameter and analytical zeta potential:

[0048] The fluid was ultrapure water as measured by Zetasizer (Nano-ZS90, Malvern Instruments, UK).

[0049] 3. XRD test:

[0050] The elemental composition and proportion of Mn, Fe and O were identified by XRD (D8 Advance, AXS, GER).

[0051] 4. Test of fat-reducing ingredient content:

[0052] HPLC-MS / MS was used to determine the targeted determination of fat-reducing ingredients (theanine, catechins, and alkaloids) in tea. The sample extract was diluted 5 times with ultrapure water before injection. The details are as follows:

[0053] (1) Experimental setup:

[0054] Liquid phase conditions: A Waters HSS T3 column was selected; the column temperature was maintained at 35°C, the injection volume was 5 μL, and the flow rate was 0.35 mL / min; the mobile phases were A = 0.01% formic acid / water, B = 0.01% formic acid / acetonitrile; the elution gradient was as follows: 0 min, 5% B; 1 min, 5% B; 11 min, 95% B; 12 min, 95% B; 12.1 min, 5% B; 14 min, 5% B;

[0055] Mass spectrometry conditions: Mass Q EXTATIVE (Thermo Fisher, Germany) mass spectrometry MS / MS acquisition mode was PRM (Parallel Reaction Monitoring), theanine and tea polyphenols were detected by ESI - (NEG) mode, caffeine using ESI +(POS) mode test, MS 2 The resolution was 17500. The isolation window and collision energy were 3.0 m / z and nce: 15, 30, 45, respectively.

[0056] Preparation of the standard curve: Theanine and catechin standards (HPLC ≥ 98%) were obtained from Solebao (Beijing, China), and caffeine standards (purity 98-99%) were purchased from Zhongke Quality Inspection Biological Co., Ltd. (China). The standards were serially diluted to a concentration gradient of 5, 50, 100, 200, 250, 500, and 1000 μg / L. -1 .

[0057] (2) Sample extraction:

[0058] Theanine extraction: First, fresh tea samples were ground into powder using liquid nitrogen. Then, 0.1 g of sample was added to 50 mL of deionized water, heated in a 100°C water bath for 30 minutes, cooled to room temperature, and the volume was filled to 50 mL with deionized water. The mixture was then passed through a 0.22 μm water membrane into an autosampler vial for theanine analysis.

[0059] Tea polyphenols and caffeine extraction: Grind the tea sample into powder, take 0.1g of the sample and add it to 10mL of 70% methanol solution (make sure to preheat it in a 70℃ water bath for 10 minutes), shake the test tube for 2 minutes (vortex), and continue heating in a 70℃ water bath for 15 minutes. Centrifuge the mixture at 6000rpm for 5 minutes and retain the supernatant. Use the same method to extract it again, and then combine all the supernatants. Finally, filter it with a 0.22μm filter into an automatic injection bottle for liquid chromatography analysis of caffeine and tea polyphenols.

[0060] 5. Testing of rhizosphere microorganisms:

[0061] Fourteen days after spraying, the rhizosphere soil of the tea trees was collected, quickly frozen in liquid nitrogen, and then sent to Paisonno Biotechnology Co., Ltd. (China) for high-throughput sequencing.

[0062] The analysis involved high-throughput 16S rRNA gene sequencing of bacteria using the Illumina MiSeq platform (Personal Biotechnology Co., Ltd., Shanghai, China) to analyze the diversity and composition of the rhizosphere soil bacterial community following the application of MnFe2O4 NMs. Briefly, bacterial DNA was extracted from soil microorganisms, and the V3–V4 region was amplified using a quantitative PCR system (ABI, 2729, USA). Sequencing libraries were constructed using the Illumina TruSeq Nano DNA LT library system, and the libraries were selected and purified using 2% agarose gel electrophoresis.

[0063] Prior to high-throughput sequencing, library quality was assessed using the Agilent High Sensitivity DNA Kit and quantified using the Quant-It PicoGreen dsDNA Analysis Kit.

[0064] Finally, paired reads of 250 bp were sequenced on the Illumina MiSeq platform using the MiSeq Reagent Kit v3 (Personal Biotechnology Co., Ltd. Shanghai, China).

[0065] 6. Metabolite testing:

[0066] First, 100 mg of fresh tea tissue sample was weighed and homogenized with liquid nitrogen. The sample was then placed in a 2 mL centrifuge tube and vortexed with 1.5 mL of a 4:1 methanol-water solution containing 0.1% formic acid. The mixture was then ultrasonically extracted (30 min, 35 kHz) in an ice-water bath. After extraction, the mixture was centrifuged at 4°C and 12,000 rpm for 15 minutes. The supernatant was pipetted into a new 2 mL centrifuge tube and dried in a rotary evaporator at 4°C under vacuum. After drying, 200 μL of a 4:4:2 methanol-acetonitrile solution (with 2-chloro-L-phenylalanine as an internal standard) was added. The sample was vortexed and ultrasonicated on ice to ensure redissolution. Finally, the supernatant was centrifuged again at 12,000 rpm and 4°C for 10 minutes.

[0067] After the sample extraction is completed, 100 μL of the extract solution is pipetted into 1.5 mL of the sample, and 5 μL of each sample is pipetted and mixed to prepare the quality control sample.

[0068] Metabolites were separated and identified using ultra-high performance liquid chromatography (UHPLC) and tandem mass spectrometry (MS / MS). The chromatographic column used was an Acquity UPLC HSS T3; the mobile phases consisted of an aqueous phase (A) consisting of 0.01% formic acid in water and an organic phase (B) consisting of 0.1% formic acid in acetonitrile; the mobile phase flow rate was 0.35 mL / min, and the injection volume was 5 μL. The column temperature was maintained at 35°C; the elution gradient was as follows: 0 min, 5% B; 1.5 min, 5% B; 10 min, 100% B; 11 min, 100% B; 11.5 min, 5% B; and 14 min, 5% B.

[0069] Example 1

[0070] A method for preparing nano manganese ferrite comprises the following steps:

[0071] 3.968 g of manganese (II) chloride tetrahydrate (MnCl2·4H2O, AR, 99%) and 10.8 g of iron (III) chloride hexahydrate (FeCl3·6H2O, AR) (molar ratio of 1:2) were stirred in 40 mL of ethylene glycol (CH2OH)2 until completely dissolved to obtain a mixed solution of manganese ions and iron ions;

[0072] Dissolve NaOH in water to obtain a 5 mol / L NaOH solution;

[0073] NaOH solution was added to the mixed solution to adjust the pH to 11; after sufficient stirring, the mixture with a pH of 11 was transferred to a hydrothermal synthesizer, heated at 200° C. for 12 hours, taken out and cooled, and then vacuum freeze-dried to obtain nano-manganese ferrite (MnFe2O4NMs).

[0074] The obtained nano manganese ferrite was subjected to performance testing, and the test results are as follows:

[0075] Table 1 shows the hydrodynamic diameter and Zeta potential of nanomanganese ferrite (MnFe2O4 NMs).

[0076] Table 1

[0077]

[0078] Figure 1 TEM image (A) and XRD pattern (B) of nano manganese ferrite (MnFe2O4 NMs). Figure 1It can be seen that the size of nano-manganese ferrite (MnFe2O4 NMs) is between 20 and 60 nm, with an average size of 62.3±14.6 nm; the material was analyzed by XRD, and the results showed that the peak shape of the sample conforms to the standard MnFe2O4.

[0079] Example 2

[0080] The application of nano manganese ferrite in reducing fat content and increasing yield of tea includes the following steps:

[0081] Select a tea tree area (Fuding Dabai tea tree) with flat terrain, good drainage and irrigation conditions, uniform growth and no buds. Use a tape measure to measure 2m 2 The tea garden quadrats were marked with quadrats poles and strings;

[0082] Before spring buds sprout (25 days before the regular picking period), tea garden plots were selected and foliar sprays of 500 mL of a 10 mg / L MnFe2O4 NMs aqueous solution were applied every two days for a total of four times. The spraying time was selected between 9:00 and 11:00 in the morning. The weather was sunny and mild, ensuring that the spraying was even on the leaves and back, and that there was no rain within four hours after the foliar spraying.

[0083] During the test period when the tea trees were growing normally, no other tea garden management measures were taken to eliminate other possible interference factors. 14 days after the spraying was completed, samples were taken according to the industry standard of one bud and one leaf.

[0084] Example 3

[0085] The concentration of the MnFe2O4 NMs aqueous solution in Example 2 was adjusted to 1 and 50 mg / L, and the other contents remained the same as in Example 2.

[0086] Comparative Example 1 (CK)

[0087] The MnFe2O4 NMs in Example 2 was omitted and replaced with pure water. Other conditions remained the same as in Example 2.

[0088] The results are as follows Figure 2-Figure 4 .

[0089] Figure 2 The properties of tea leaves treated with different concentrations of MnFe2O4 NMs aqueous solutions; (A) fresh weight (FW) and dry weight (DW) of 100 buds of Fuding Dabai tea; (B) total tea yield; (C) soluble sugar content of tea leaves. Figure 2It can be seen that compared with the CK treatment, the 10 mg / L MnFe2O4 NMs aqueous solution treatment had the best improvement effect, among which the fresh weight (FW) increased by 34.3% and the dry weight (DW) increased by 121.1%. At the same time, the application of MnFe2O4 NMs increased the total yield of one bud and one leaf, among which the 10 mg / L concentration had the best effect, and the total yield increased by 27.8% under fresh weight determination; the determination of the content of soluble sugar in photosynthetic products showed that the soluble sugar content increased significantly under the MnFe2O4 NMs treatment, among which the 10 mg / L MnFe2O4 NMs treatment had the best improvement effect, and the soluble content increased by 38.1% compared with the CK treatment.

[0090] Figure 3 The performance of NMs treated with different concentrations of MnFe2O4 aqueous solution; (A) the changes in the content of theanine, EGCG, and caffeine; (B) the changes in the content of ester and non-ester catechins. Figure 3 It can be seen that compared with the CK treatment, the EGCG content in the Fuding Dabai tea buds was significantly increased after foliar application of 10 mg / L and 50 mg / L MnFe2O4 NMs. Moreover, compared with the CK treatment, the foliar application of different concentrations of MnFe2O4 NMs significantly improved the contents of ester-type and non-ester-type catechins in the tea buds. In particular, the 10 mg / L MnFe2O4 NMs treatment showed the most significant increase in the contents of total catechins, ester-type catechins, and non-ester-type catechins in the tea buds (p < 0.05). Specifically, 10 mg / L MnFe2O4 NMs increased the fat-reducing ingredients theanine, EGCG, total catechins, and caffeine in tea buds by 21.9%, 55.3%, 77.8%, and 10.1%, respectively. The tea plant also increased its absorption of nutrients, with the Mg, P, S, and K contents in tea buds increasing by 20.0%, 9.9%, 6.8%, and 8.3%, respectively.

[0091] In summary, after spraying different concentrations of MnFe2O4 NMs on the surface of Fuding Dabai tea leaves, the fat-reducing components in the tea leaves increased to varying degrees; among them, 10 mg / L MnFe2O4 NMs had the best effect on improving the yield and fat-reducing components of Fuding Dabai tea.

[0092] Comparative Example 2 Equal amounts of ions

[0093] 3.968 g of manganese (II) chloride tetrahydrate (MnCl2·4H2O, AR, 99%) and 10.800 g of iron (III) chloride hexahydrate (FeCl3·6H2O, AR) (molar ratio of 1:2) were stirred in 40 mL of ethylene glycol (CH2OH)2 until completely dissolved to obtain a mixed solution of manganese ions and iron ions; the concentrations of iron ions and manganese ions in the mixed solution were equivalent to the concentration of 10 mg / LMnFe2O4 NMs and were marked as 10 mg / L (MnCl2·4H2O+FeCl3·6H2O).

[0094] Then, the mixture was applied to tea leaves according to the application method of Example 2.

[0095] Comparative Example 3 Iron Fertilizer + Manganese Fertilizer

[0096] Manganese (II) chloride tetrahydrate (MnCl2·4H2O, AR, 99%) and iron (III) chloride hexahydrate (FeCl3·6H2O, AR) are dissolved in water to obtain a mixed solution of iron fertilizer and manganese fertilizer; wherein the mass fractions of manganese (II) chloride tetrahydrate and iron (III) chloride hexahydrate in water are both 0.1%; marked as 0.1% (MnCl2·4H2O+FeCl3·6H2O); 0.1% is the concentration of iron fertilizer and manganese fertilizer commonly used in agriculture.

[0097] Then, the mixture was applied to tea leaves according to the application method of Example 2.

[0098] The performance test of Example 2 and Comparative Examples 1-3 was carried out, and the test results are as follows:

[0099] Figure 4 The performance comparison between Example 2 and Comparative Examples 1-3 is shown. Figure 4 It can be seen that compared with CK (Comparative Example 1), the same amount of ions (Comparative Example 2), and iron fertilizer + manganese fertilizer (Comparative Example 3), the content of theanine and caffeine in tea buds under the treatment of 10 mg / L MnFe2O4 NMs is the highest, and the promoting effect is the most obvious, that is, the application of 10 mg / L MnFe2O4 NMs has the best effect on improving the fat-reducing components of tea buds.

[0100] Tea beverages have a rich taste and numerous health benefits, which are attributed to the fact that fresh tea leaves are rich in more than 700 different metabolites, including polyphenols, catechins, flavonols and anthocyanins, purine alkaloids, non-protein amino acids and some volatile aromatic products. These natural products are significantly accumulated in tea leaves, giving tea its unique efficacy. After the application of MnFe2O4 NMs, the content of 23 metabolites related to the quality of Fuding Dabai tea was detected to change and there were significant differences. The differential metabolites included 8 amino acids, 2 alkaloids, 8 polyphenols and 5 organic acids (citric acid, malic acid, fumaric acid, succinic acid pyruvic acid). Among them, 19 metabolites were up-regulated and 4 metabolites were down-regulated ( Figure 5 ), which is mainly due to the fact that the application of MnFe2O4 NMs significantly improves the photosynthesis of plants, increases the photosynthetic products, and enables plants to use more glucose for subsequent glycolysis, thereby further promoting the synthesis of subsequent amino acids (glutamic acid, arginine, tryptophan, theanine, etc.) and antioxidant active substances (caffeine, catechin compounds).

[0101] Increased photosynthesis allows more carbohydrates to be transported to the roots. Root carbohydrates, through glycolysis, provide substrates for the synthesis of root exudates. Plants then use these exudates to selectively recruit soil microorganisms, facilitating nutrient absorption and improving crop quality and yield. A total of 22 phyla, 45 classes, 95 orders, 149 families, 172 genera, and 48 species were identified under the MnFe2O4 NMs treatment. By analyzing the relative abundance of the main bacterial phyla in the soil samples, it was found that the phylum with the highest content in the samples was Proteobacteria, followed by Acidobacteria and Actinobacteria, while the proportion of other fungi was relatively low, with a relative abundance of less than 10%. In addition, the addition of MnFe2O4NMs changed certain specific bacterial groups. At the genus level, the relative abundance of Acidibacter, Roseiarcus, Acidipila, Subgroup-13, Bryobacter and Acidothermus increased significantly. These bacteria can promote soil nitrogen fixation and the utilization of soil available phosphorus, and play a role in plant-microorganism interactions to improve the utilization efficiency of nutrients ( Figure 6 ).

[0102] Comparative Example 4

[0103] The MnFe2O4 NMs in Example 2 was adjusted to nano-selenium, and the other aspects remained the same as in Example 2;

[0104] Among them, the average size of nanoselenium is 62.3±9.9nm;

[0105] The preparation method of nano-selenium is as follows:

[0106] The mixture of raisin extract (pH=5.9) and 4×10 -5 M of selenious acid (H2SeO3, ≥95%, Sinopsin Group Chemical Agent, Ltd.) was mixed and heated under reflux conditions to obtain a mixture; the mixture was then centrifuged at 17280g for 20 minutes to obtain a paste-like sediment; and finally, it was freeze-dried to obtain nano-selenium.

[0107] The test results are as follows:

[0108] After the application of 10 mg / L Se NMs, the total yield and 100-bud weight (fresh weight) of tea buds increased by 21.9% and 24.3%, respectively; the net photosynthetic rate, transpiration rate, stomatal conductance and intercellular carbon dioxide concentration of tea leaves increased; the contents of theanine, EGCG, total catechins and caffeine in tea buds increased by 36.2%, 53.9%, 67.1% and 30.9%, respectively; the contents of Mg, P, S, K, Mn and other nutrients increased by 17.1%, 18.5%, 9.0% and 15.4%, respectively.

[0109] Although the present invention has been disclosed above in terms of preferred embodiments, it is not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the definition of the claims.

Claims

1. A method for improving tea quality and yield based on increasing the relative abundance of Acidibacter, Roseiarcus, Acidipila, Subgroup-13, Bryobacter and Acidothermus, characterized in that: The method comprises the steps of preparing nano manganese ferrite into a nano manganese ferrite solution, which is then applied as a fertilizer on tea leaves by foliar spraying.

2. The method according to claim 1, characterized in that The particle size of the nano manganese ferrite is 20-60 nm, the average size is 2.3±14.6 nm, the hydraulic diameter is 538.6±27.2 nm, and the Zeta potential is -21.7±1.5 mV.

3. The method according to claim 1, characterized in that The nano manganese ferrite solution is a nano manganese ferrite aqueous solution with a concentration of 1-50 mg / L.

4. The method according to claim 1, wherein The amount of the nano manganese ferrite solution applied is 200-300 mL / (time·m 2 ), spray once every 2-3 days, a total of 1-4 times; spray time is 9:00-11:00 in the morning.

5. The method according to claim 1, characterized in that The application period is before spring buds sprout.

6. The method according to claim 1, characterized in that The tea tree is the Fuding Dabaicha tea tree.

7. The method according to claim 1, characterized in that The preparation method of nano manganese ferrite comprises the following steps: Manganese (II) chloride tetrahydrate and iron (III) chloride hexahydrate are stirred in ethylene glycol until completely dissolved to obtain a mixed solution of manganese ions and iron ions; Dissolve NaOH in water to obtain NaOH solution; NaOH solution was added to the mixed solution to adjust the pH to 11; after sufficient stirring, the mixture with a pH of 11 was heated at 200° C. for 12 hours, taken out for cooling, and vacuum freeze-dried to obtain nano-manganese ferrite.

8. The method according to claim 7, characterized in that The usage ratio of manganese (II) chloride tetrahydrate, iron (III) chloride hexahydrate and ethylene glycol is 3.968 g:10.8 g:40 mL.

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