Cadmium blocking agent based on moringa oleifera peptide and application of cadmium blocking agent

Abstract

The invention discloses a moringa oleifera peptide-based cadmium blocking agent and application thereof. The preparation is composed of moringa oleifera peptide (the mass volume concentration is 30-120 mg / L), a compound stabilizer (the mass volume concentration is 20-60 mg / L) and a phosphate buffer solution, the compound stabilizer is composed of sodium alginate and nano silicon dioxide according to the mass ratio of 1: (1.0-1.5), and the pH value of the preparation is 6.0-7.0. The moringa oleifera peptide is innovatively applied to cadmium prevention and control of Chinese cabbages in northern alkaline cadmium-polluted soil (pH is 6.5-7.5), accurate regulation and control are achieved in a rhizosphere irrigation mode, a sodium alginate-nano silicon dioxide composite stabilizer system synergistically plays the dual functions of dispersion stability and slow release protection, and it is ensured that the moringa oleifera peptide keeps activity in the soil environment. The preparation has the advantages of being small in dosage, low in cost, easy and convenient to operate, environmentally friendly and the like, a scientific and feasible technical scheme is provided for safe utilization of cadmium-polluted farmlands in northern alkaline soil areas, and the preparation has important application value and popularization prospects.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of agricultural environmental remediation and plant nutrition regulation, and particularly relates to a composite stable moringa peptide cadmium blocking preparation and application thereof in Chinese cabbage planting. BACKGROUND

[0002] Heavy metal cadmium pollution has become a global environmental problem, threatening the sustainability of agricultural production and food safety. According to statistics, about 20 million hectares of cultivated land in China are contaminated by cadmium, among which leafy vegetables such as Chinese cabbage become the main source of cadmium exposure due to their short growth cycle and strong enrichment ability. The soil in northern China is mostly neutral to alkaline (pH 6.5-7.5), and the bioavailability of cadmium is relatively low, but it can still be absorbed by the roots into the edible parts, posing a threat to human health.

[0003] At present, the main cadmium pollution prevention and control technologies include physical remediation (such as soil replacement), chemical passivation (such as adding lime or phosphate), agronomic regulation (such as water management and low-accumulation variety screening), and biological remediation (such as plant-microorganism combined remediation). However, these traditional methods have obvious limitations: physical remediation is costly (up to tens of thousands of yuan per mu) and destroys the soil ecological structure; chemical passivation agents can easily change the soil pH and nutrient balance, potentially causing new environmental risks; biological remediation has a long cycle (usually several years), unstable effects, and is greatly affected by the climate.

[0004] In recent years, plant-derived bioactive substances have attracted attention as new cadmium blocking materials. These substances inhibit cadmium absorption and transport by regulating plant physiological metabolic processes (such as antioxidant defense, hormone balance, ion transport, etc.), and have the advantages of renewable raw materials, low cost, simple application, environmental friendliness, and rapid effect, making them an important innovative direction for the safe use of cadmium-contaminated farmland.

[0005] CN106167707A discloses a small cabbage root system cadmium blocking agent composed of diatomite (33%-33.5%) and peanut cake (66.5%-67%), which is mixed with base fertilizer (150-300 kg / mu) to play a role. This technology has large dosage (hundreds of times of the present application) and complex operation, which is not suitable for large-scale promotion; it mainly relies on physical adsorption and soil improvement, has a single mechanism of action, lacks direct regulation of plant physiological metabolism, and cannot fundamentally enhance the tolerance of plants to cadmium stress. CN112335662A discloses a small cabbage heavy metal blocking agent with melatonin and aspartic acid as effective components, which has the following limitations: foliar spraying cannot directly act on the key part of root cadmium absorption; the regulation ability of rhizosphere environment and cadmium absorption process is limited; the physiological regulation mechanism is not comprehensive, only involving a single metabolic pathway.

[0006] Although there are reports that moringa extracts (such as moringa smoke liquid) have stress resistance effects in rice, there are significant technical obstacles to direct application in Chinese cabbage: (1) crop characteristics differ: rice is a fibrous root system that adapts to anaerobic conditions in paddy fields; Chinese cabbage is a taproot system with dense root hairs and grows in oxidizing upland fields, and there are essential differences in the absorption methods and efficiency of exogenous substances between the two; (2) soil environment differences: rice soil is slightly acidic (pH 5.5-6.5), and Chinese cabbage soil is mostly neutral to alkaline (pH 6.5-7.5), and the moringa smoke liquid is prone to precipitation and degradation under alkaline conditions; (3) application efficiency problems: the stability of the smoke liquid in the oxidizing environment of the upland field is poor, and it is difficult to penetrate the dense root hairs of Chinese cabbage to reach the rhizosphere microenvironment, resulting in low absorption efficiency and poor effect persistence.

[0007] In view of this, the present application is proposed. SUMMARY

[0008] The purpose of the present application is to provide a composite stable moringa peptide cadmium blocking preparation and its preparation method and application, which can effectively reduce the cadmium accumulation in the edible parts of Chinese cabbage in alkaline cadmium contaminated soil in the north, and at the same time promote the normal growth of plants, providing technical support for the safe use of cadmium contaminated farmland.

[0009] To achieve the above-mentioned purpose, the present application adopts the following technical solutions: First aspect: composition of the cadmium blocking preparation.

[0010] The present application provides a composite stable moringa peptide cadmium blocking preparation, which is composed of the following components: (1) Moringa peptide, mass concentration of 30-120 mg / L, as the main bioactive ingredient; (2) Composite stabilizer, mass concentration of 20-60 mg / L, composed of sodium alginate and nano-silicon dioxide at a mass ratio of 1:(1-1.5), used to enhance the dispersion stability and slow release effect of moringa peptide; (3) Phosphate buffer, used to adjust the pH value of the cadmium blocking preparation to 6.0-7.0, to maintain the stability of the preparation in different soil environments.

[0011] Technical principle explanation: Moringa peptide, as a plant-derived bioactive peptide, has multiple functions of regulating plant antioxidant defense, hormone balance and ion transport, but it is easily degraded or precipitated under alkaline soil environment due to pH fluctuation and ion interference. The present application innovatively uses a sodium alginate-nano-silicon dioxide composite stabilizer system: sodium alginate forms a gel network to provide a slow-release carrier, nano-silicon dioxide enhances dispersion stability, and phosphate buffer maintains pH stability, all of which work together to ensure the activity of moringa peptide in alkaline soil. In the preferred embodiment, moringa peptide at a concentration of 120 mg / L has the best cadmium blocking effect and growth promotion effect.

[0012] The second aspect: preparation method.

[0013] This invention provides a method for preparing the above-mentioned cadmium-inhibiting agent, comprising the following steps: (1) Preparation of stabilizer (S1): Sodium alginate is dissolved in phosphate buffer and stirred in a water bath at 50-70℃ until completely dissolved; nano silica is added and ultrasonically treated at 4-5℃ (power 300-500 W, temperature 4-5℃, time 15-30 min) until a uniform gel is formed. (2) Moringa peptide dispersion (S2): Moringa peptide powder is added to the gel obtained in step S1. The mixture is stirred for 40-45 min under light-protected conditions, and then homogenized at 4-5℃ at a speed of 10000-12000 r / min for 20-30 min to obtain the cadmium-inhibiting agent.

[0014] Key points of the process: (1) Sodium alginate needs to be dissolved at 50-70℃ to ensure complete dispersion; (2) The temperature should be controlled at 4-5℃ during ultrasonic treatment to avoid loss of moringa peptide activity; (3) The homogenization process needs to be carried out in the dark to prevent photo-oxidative degradation; (4) A longer stirring time (40-45 min) helps moringa peptide to be evenly dispersed in the gel carrier.

[0015] Third aspect: Application.

[0016] The cadmium-inhibiting agent described in this invention can be used to reduce cadmium absorption by cabbage grown in cadmium-contaminated soil, specifically through rhizosphere irrigation to achieve cadmium inhibition.

[0017] Fourth aspect: Application methods.

[0018] This invention provides a method for reducing cadmium absorption by Chinese cabbage planted in cadmium-contaminated soil, comprising the following steps: (1) timing of application: applying to the root zone on the 3rd day after thinning of Chinese cabbage seedlings; (2) application conditions: applying 40-60 mL of the cadmium inhibitor to each Chinese cabbage plant, once every 3-7 days, for 3-5 consecutive applications; (3) applicable scope: applicable to alkaline slightly cadmium-contaminated soil (pH 6.5-7.5, total cadmium content 0.8-2.0 mg / kg).

[0019] By applying the formulation directly to the key sites of cadmium absorption through root zone irrigation, the process of cadmium absorption and accumulation in cabbage can be precisely controlled, significantly reducing the cadmium content in the edible parts of cabbage.

[0020] Compared with the prior art, the present invention has the following significant advantages: 1. Technological innovation is outstanding. (1) The moringa peptide is applied to cadmium control in alkaline soil for the first time, breaking through the technical barrier of the application of active substances in moringa to cross-crops; compared with moringa smoke liquid, the stability of the moringa peptide is stronger; (2) The sodium alginate-nano-silicon dioxide composite stabilizer system is innovatively used to form a slow-release carrier, solving the problems of dispersibility and stability of the moringa peptide in the alkaline soil environment; (3) Rhizosphere irrigation is accurately controlled, directly acting on the key part of cadmium absorption, and the mechanism is clear. In addition to the above measures, the pH is adjusted to 6.0-7.0 by phosphate buffer, and the optimal concentration range (30-120 mg / L) is determined, which effectively controls the absorption of cadmium while promoting the normal growth of plants, realizing an important technical breakthrough in cross-crop application.

[0021] 2. The effect is significant and quantified. Experimental data show that, compared with the control group: (1) Cadmium control effect: the cadmium content in the aboveground part of Chinese cabbage is reduced by 10.5%, and the cadmium content in the root system is reduced by 10.0%; (2) Growth promotion effect: within the concentration range of 30-120 mg / L, the fresh weight of the aboveground part is increased by 35.5%-89.2%, the fresh weight of the root system is increased by 45.7%-92.2%, the dry weight of the aboveground part is increased by 45.1%-82.5%, and the dry weight of the root system is increased by 60.6%-133.3%; (3) Physiological improvement: SOD activity is increased by 34.9%, APX content is increased by 97.9%, MDA content is reduced by 25.6%, and hydroxyl radical clearance rate is increased by 40.5%; (4) Hormone regulation: significantly reducing the content of stress-related hormones (ZR, ABA, IAA), and moderately increasing the level of GA3.

[0022] 3. Multi-mechanism synergistic effect. The application controls cadmium by adjusting multiple physiological metabolic pathways of plants: (1) Antioxidant defense: activating SOD, POD, CAT, APX and other antioxidant enzyme systems, and increasing the accumulation of non-enzymatic antioxidants such as total phenol, flavonoid and anthocyanin; (2) Hormone balance: reducing the level of stress-related hormones to alleviate the inhibition of cadmium stress on plant growth; (3) Cell membrane protection: reducing membrane lipid peroxidation and maintaining cell membrane integrity.

[0023] 4. Strong practicability. (1) Small dosage: the dosage of the preparation per mu is only dozens of grams, which is much lower than that of traditional cadmium control agents (150-300 kg / mu); (2) Simple application: rhizosphere irrigation is simple to operate and can be combined with regular watering, without the need for deep ploughing or large-scale soil improvement; (3) Low cost: raw materials are easy to obtain, and the preparation process is simple, suitable for large-scale production; (4) Environmentally friendly: plant-derived materials are biodegradable and have no risk of secondary pollution.

[0024] 5. High promotion value. The application provides a feasible technical solution for the safe use of cadmium-polluted farmland in alkaline soil regions in the north, has important ecological, economic and social benefits, and has a wide application prospect. DETAILED DESCRIPTION

[0025] The application will be further described in conjunction with specific examples. However, the application is not limited to the following examples.

[0026] The experimental methods used in the following examples are conventional methods unless otherwise specified. The reagents, materials, instruments, etc. used are commercially available unless otherwise specified.

[0027] Materials and reagents (I) Test plants Brassica chinensis L., variety "Jinglv No. 1", seeds purchased from the Vegetable Research Center of Beijing Academy of Agriculture and Forestry Sciences, germination rate ≥ 95%.

[0028] (II) Test soil The test soil was collected from a typical light cadmium-contaminated farmland in Jiyuan, Henan Province, using a five-point mixed sampling method in the surface layer of 0-20 cm.

[0029] The basic physicochemical properties of the soil were as follows: pH 7.2±0.1, total cadmium content 1.35±0.05 mg / kg, organic matter content 15.3 g / kg, available phosphorus content 23.5 mg / kg, and available potassium content 128 mg / kg.

[0030] The soil meets the standard for alkaline light cadmium-contaminated soil (pH 6.5-7.5, total cadmium content 0.8-2.0 mg / kg).

[0031] The soil was air-dried and passed through a 2 mm sieve for use.

[0032] (III) Reagents and materials Moringa oleifera peptide (purity ≥ 90%) was purchased from Shanghai Yuanye Biological Technology Co., Ltd.; Sodium alginate (analytical pure, ≥99%) was purchased from National Pharmaceutical Group Chemical Reagent Co., Ltd.; Nanosilica (particle size 20-30 nm) was purchased from Aladdin Biochemical Technology Co., Ltd.; Phosphate buffer solution (PBS, pH 7.0) was prepared in the laboratory.

[0033] Examples This example provides a preparation method of a moringa peptide cadmium-blocking preparation, and the specific steps are as follows: (1) Preparation of the composite stabilizer. Dissolve sodium alginate powder in a phosphate buffer, stir until completely dissolved in a 60°C water bath, and prepare a solution with a concentration of 15.9 mg / L. After cooling to room temperature, add nano-silicon dioxide (particle size 20-30 nm) to a final concentration of 19.1 mg / L (sodium alginate to nano-silicon dioxide mass ratio 1:1.2), and use ultrasonic dispersion (power 400 W, time 20 min) at 4-5°C to form a uniform transparent gel system, i.e. the composite stabilizer. The total mass-volume concentration of the composite stabilizer is 35 mg / L.

[0034] (2) Preparation of the composite stabilizer-type moringa peptide cadmium-resistant preparation. Add moringa peptide powder (final concentration 120 mg / L) to the above composite stabilizer, and stir in the dark for 40-45 min to disperse it fully. Homogenize at 11000 r / min for 25 min at 4-5°C to obtain the composite stabilizer-type moringa peptide cadmium-resistant preparation stock solution.

[0035] The resulting preparation has a pH of 6.8±0.1, is uniform in appearance and has no precipitate, and can be stored stably for more than 30 days under light-avoiding conditions at 4°C.

[0036] Test Example I. Purpose of the experiment This experiment evaluates the effects of different concentrations of moringa peptide cadmium-resistant preparations (30-120 mg / L) on cabbage planted in cadmium-contaminated soil through pot experiments, focusing on their cadmium-resistant effects, growth-promoting effects, and physiological and biochemical response mechanisms, to provide scientific basis for the application of moringa peptide preparations in cabbage planting in alkaline cadmium-contaminated soil.

[0037] II. Experimental materials and methods (I) Experimental site and materials 1. Experimental site Beijing Academy of Agriculture and Forestry Sciences, Dayi greenhouse. The greenhouse temperature was controlled at 20-25°C, the relative humidity was 60%-70%, and the natural light was used during the experiment.

[0038] 2. Test soil The potting soil was collected from a slightly cadmium-contaminated farmland in Jiyuan, Henan Province, and was collected in the surface layer of 0-20 cm using a five-point mixing sampling method. The soil sample was air-dried to a moisture content of ≤5% after being brought back to the laboratory, and was sieved through a 2 mm sieve before being loaded into sterilized pots. Each pot contained 300.0±0.5 g of soil.

[0039] The basic physicochemical properties of the soil were as follows: pH value was 7.2 ± 0.1, electrical conductivity (EC) was 1.16 mS / cm, total cadmium content was 1.35 ± 0.05 mg / kg (mildly contaminated), organic matter content was 15.3 g / kg, available phosphorus content was 23.5 mg / kg, and available potassium content was 128 mg / kg.

[0040] 3. Test crop The pakchoi variety "Jinglv No. 1" (purchased from the Vegetable Research Center of the Beijing Academy of Agriculture and Forestry Sciences) had a purity of ≥ 99% and a germination rate of ≥ 95%. This variety had vigorous growth, dark green leaves, and crisp and tender quality, and had good heat tolerance and disease resistance, making it suitable for cultivation in northern regions.

[0041] 4. Test preparation The preparation stock solution prepared in the above example was diluted with PBS buffer to different moringa peptide mass concentrations, namely 0 mg / L (control, CK), 30 mg / L, 60 mg / L, and 120 mg / L, for subsequent tests.

[0042] Control treatment CK (0 mg / L moringa peptide): Sodium alginate powder was dissolved in deionized water, stirred at 60°C under light protection until completely dissolved, and prepared into a solution with a concentration of 15.9 mg / L. Nano-silicon dioxide (particle size 15-20 nm) was added to a final concentration of 19.1 mg / L (mass ratio 1:1.2), and ultrasonic treatment was performed for 20-25 min to ensure uniform dispersion, obtaining a composite stabilizer system (without moringa peptide) with a total concentration of 35 mg / L. Irrigation was started 3 days after the completion of the pakchoi transplanting, with 50 mL per plant, at intervals of 5 days, and a total of 4 irrigations. This group served as a benchmark control for comparing the differences in effects of different concentrations of moringa peptide treatment.

[0043] Low concentration treatment (30 mg / L moringa peptide): After preparing the composite stabilizer type moringa peptide cadmium blocking preparation stock solution according to the method of the example, it was diluted with PBS (pH 7.0) to a moringa peptide concentration of 30 mg / L, and the composite stabilizer concentration was simultaneously diluted to 8.75 mg / L (sodium alginate 3.98 mg / L, nano-silicon dioxide 4.77 mg / L, mass ratio 1:1.2). Irrigation was started 3 days after the completion of the pakchoi transplanting, with 50 mL per plant, at intervals of 5 days, and a total of 4 irrigations. This treatment was used to investigate the effects of low concentration moringa peptide preparation on plant growth and cadmium uptake.

[0044] Medium concentration treatment (60 mg / L moringa peptides): The composite stabilizer type moringa peptides cadmium resistance preparation stock solution was prepared according to the method of the example, diluted with phosphate buffer to the concentration of 60 mg / L moringa peptides and 17.5 mg / L composite stabilizer (7.95 mg / L sodium alginate, 9.55 mg / L nano-silicon dioxide, mass ratio 1:1.2). After the seedling of pakchoi was completed, rhizosphere irrigation was started on the 3rd day, 50 mL per plant, with an interval of 5 days, and a total of 4 times. This treatment was used to evaluate the effect of medium concentration moringa peptide preparation on the plant's ability to resist cadmium and growth regulation.

[0045] High concentration treatment (120 mg / L moringa peptides): Sodium alginate powder was dissolved in deionized water under the condition of 60°C water bath and stirring in the dark until completely dissolved, and a solution with a concentration of 15.9 mg / L was prepared. Nano-silicon dioxide (particle size 15-20 nm) was added to a final concentration of 19.1 mg / L (mass ratio 1:1.2), and ultrasonic treatment was performed for 20-25 min to ensure uniform dispersion. After cooling to room temperature, moringa peptide powder was added (final concentration 120 mg / L), stirred in the dark for 40-45 min, and homogenized at 11000 r / min for 25 min at 4-5°C to obtain a composite stabilizer type moringa peptide cadmium resistance preparation stock solution (total concentration of composite stabilizer 35 mg / L). Rhizosphere irrigation was performed on pakchoi, 50 mL per plant, with an interval of 5 days, and a total of 4 times. This group was used to verify the effect of high concentration moringa peptide preparation in reducing cadmium absorption and accumulation.

[0046] Comparative Example 1 (pure moringa peptide control (without stabilizer)): Moringa peptide powder (120 mg / L) was directly dispersed in phosphate buffer (PBS, pH 7.0), stirred in the dark for 40-45 min, and homogenized at 11000 r / min for 25 min at 4-5°C to obtain a pure moringa peptide dispersion solution without any stabilizer. Rhizosphere irrigation was performed on pakchoi in the same way, 50 mL per plant, with an interval of 5 days, and a total of 4 times. This group was used to verify the necessity of the composite stabilizer system for maintaining the activity and slow-release effect of moringa peptides.

[0047] Comparative Example 2 (single sodium alginate stabilizer control): Sodium alginate powder was dissolved in deionized water under the condition of 60°C water bath and stirring in the dark until completely dissolved, and a sodium alginate solution with a concentration of 35 mg / L was prepared. After cooling to room temperature, moringa peptide powder was added (final concentration 120 mg / L), stirred in the dark for 40-45 min, and homogenized at 11000 r / min for 25 min at 4-5°C. Rhizosphere irrigation was performed on pakchoi, 50 mL per plant, with an interval of 5 days, and a total of 4 times. This group was used to verify the necessity of nano-silicon dioxide in the composite stabilizer system to improve dispersibility and prevent precipitation.

[0048] Comparative Example 3 (single nano-silica stabilizer control): Nano-silica (particle size 15-20 nm) was dispersed in deionized water to prepare a dispersion solution with a concentration of 35 mg / L, and ultrasonic treatment was performed for 20-25 min to ensure uniform dispersion. Moringa peptide powder (final concentration 120 mg / L) was added, and stirring was performed in the dark for 40-45 min. Homogenization was performed at 11000 r / min at 4-5°C for 25 min. The pakchoi was subjected to rhizosphere irrigation, 50 mL per plant, with an interval of 5 days, and a total of 4 times. This group was used to verify the necessity of the sodium alginate gel carrier in the composite stabilizer system for providing sustained protection.

[0049] Comparative Example 4 (lower limit verification of stabilizer ratio (1:1.0)): Sodium alginate powder was dissolved in deionized water, and stirring was performed in the dark at 60°C in a water bath until complete dissolution, to prepare a solution with a concentration of 17.5 mg / L. Nano-silica was added to a final concentration of 17.5 mg / L (mass ratio 1:1.0, lower limit specified in the claim), and ultrasonic treatment was performed for 20-25 min. After cooling to room temperature, moringa peptide powder (final concentration 120 mg / L) was added, and stirring was performed in the dark for 40-45 min. Homogenization was performed at 11000 r / min at 4-5°C for 25 min, to obtain a composite stabilizer-type moringa peptide cadmium-resistant preparation with a total concentration of 35 mg / L. The pakchoi was subjected to rhizosphere irrigation, 50 mL per plant, with an interval of 5 days, and a total of 4 times. This group was used to verify the dispersion stability effect of the lower limit of the stabilizer ratio.

[0050] Comparative Example 5 (upper limit verification of stabilizer ratio (1:1.5)): Sodium alginate powder was dissolved in deionized water, and stirring was performed in the dark at 60°C in a water bath until complete dissolution, to prepare a solution with a concentration of 14 mg / L. Nano-silica was added to a final concentration of 21 mg / L (mass ratio 1:1.5, upper limit specified in the claim), and ultrasonic treatment was performed for 20-25 min. After cooling to room temperature, moringa peptide powder (final concentration 120 mg / L) was added, and stirring was performed in the dark for 40-45 min. Homogenization was performed at 11000 r / min at 4-5°C for 25 min, to obtain a composite stabilizer-type moringa peptide cadmium-resistant preparation with a total concentration of 35 mg / L. The pakchoi was subjected to rhizosphere irrigation, 50 mL per plant, with an interval of 5 days, and a total of 4 times. This group was used to verify the influence of excess nano-particles on the rhizosphere environment when the upper limit of the stabilizer ratio is exceeded.

[0051] Comparative Example 6 (upper limit of stabilizer concentration verification (70 mg / L)): Sodium alginate powder was dissolved in deionized water, stirred in the dark under the condition of 60°C water bath until completely dissolved, and prepared into a solution with a concentration of 31.8 mg / L. Nano-silicon dioxide was added to a final concentration of 38.2 mg / L (mass ratio 1:1.2), and ultrasonic treatment was performed for 20-25 min to obtain a composite stabilizer with a total concentration of 70 mg / L. After cooling to room temperature, moringa peptide powder was added (final concentration 120 mg / L), and stirred in the dark for 40-45 min, and then homogenized at 11000 r / min for 25 min under the condition of 4-5°C. The pakchoi was subjected to rhizosphere irrigation, 50 mL per plant, with an interval of 5 days, and a total of 4 times of irrigation. This group was used to verify the negative effect of excessively high stabilizer concentration on the penetration of rhizosphere due to excessively high viscosity of the preparation.

[0052] (II) Experimental design The above four treatment groups (control treatment CK, 30 mg / L moringa peptide, 60 mg / L moringa peptide, and 120 mg / L moringa peptide) were set up. Each treatment had 10 biological replicates, for a total of 60 pots. A randomized block design was used, and the positions of the pots were adjusted every day to reduce position effects.

[0053] The composite stabilizer concentration of all treatment groups was 35 mg / L (sodium alginate 15.9 mg / L, nano-silicon dioxide 19.1 mg / L, mass ratio 1:1.2), and only the moringa peptide concentration was different.

[0054] (III) Sowing and seedling management 1. Seed disinfection. Before sowing, the seeds were subjected to disinfection treatment: rinsing with running water for 5 minutes → 75% ethanol soaking for 30 seconds → 1% sodium hypochlorite solution soaking for 10 minutes → rinsing with sterile deionized water for 5 times → sterile filter paper drying for standby.

[0055] 2. Sowing. 5 seeds were sown in each pot, with a sowing depth of 1.0±0.1 cm and uniform soil cover thickness. After sowing, the soil was thoroughly watered, and plastic film was covered to keep the soil moist and promote germination.

[0056] 3. Thinning. When the seedlings developed to the two-leaf-one-heart stage, thinning was performed, and 2 healthy plants were retained.

[0057] (IV) Moringa peptide preparation application 1. Application timing. The first rhizosphere irrigation was started 3 days after the completion of the cabbage thinning.

[0058] 2. Application method. Quantitative root irrigation method was used, 50 mL of preparation was applied to each plant, and irrigation was performed every 5 days for a total of 4 times. The irrigation time was fixed at 9:00-10:00 in the morning to avoid the influence of changes in light intensity.

[0059] 3. Water management. The soil water content was maintained at 70-80% of the field capacity during the culture period, and the evaporation loss was replenished with deionized water to ensure the soil to keep the initial weight.

[0060] (V) Sampling and determination 1. Sampling time. The concentrated harvest was performed at the 8th day after the last formulation application (about 30 days after sowing).

[0061] 2. Sample treatment. The aboveground and root system were separated immediately after the plant harvest with stainless steel scissors, and rinsed with tap water to remove the surface soil and deionized water for 3 times. After the fresh weight was weighed with a thousandth balance, the sample was divided into two parts: fresh sample: frozen with liquid nitrogen, stored at -80℃ for physiological and biochemical index determination. Dry sample: blanched at 90℃ for 30 min, dried at 75℃ to constant weight for cadmium content determination.

[0062] 3. Determination index.

[0063] (1) Growth index. Fresh weight and dry weight of aboveground and root system (g / plant), fresh weight root-shoot ratio and dry weight root-shoot ratio.

[0064] (2) Cadmium content determination. Method: aqua regia-perchloric acid digestion + ICP-MS (inductively coupled plasma mass spectrometry). Sample treatment: the dried sample was ground through a 0.25 mm sieve, 0.5 g was weighed in a digestion tank, 10 mL of aqua regia (HCl:HNO3=3:1) and 2 mL of perchloric acid were added, and the solution was digested at 120℃ until it was clear, and then diluted to 50 mL, filtered and determined. Quality control: 3 parallel samples and 1 standard material sample were set for each batch of samples, and the recovery rate was controlled at 95%-105%.

[0065] (3) Antioxidant index. ELISA kit was used to determine: ① Enzyme activity index: the following indexes were determined by enzyme marker (kit purchased from Nanjing Jiancheng Biological Engineering Institute): superoxide dismutase (SOD) activity (xanthine oxidase method), peroxidase (POD) activity (guaiacol method), catalase (CAT) activity (ultraviolet absorption method), ascorbate peroxidase (APX) content (colorimetric method). ② Non-enzyme antioxidant and membrane lipid damage index: malondialdehyde (MDA) content (thiobarbituric acid method), total antioxidant capacity (T-AOC, FRAP method), hydroxyl radical clearance rate (o-diazenephene-Fe2+ oxidation method), total phenol content (Folin-Ciocalteu colorimetric method), flavonoid content (nitric acid aluminum colorimetric method), anthocyanin content (pH differential method). ③ Hormone content: the contents of cell division kinetin (ZR), abscisic acid (ABA), auxin (IAA) and gibberellin acid (GA3) were determined by ELISA kit. +

[0066] ​4. Data processing. All indexes were measured in triplicate, and the data were expressed as mean ± standard deviation. One-way ANOVA was used to analyze the data by SPSS 26.0 software, and Duncan's multiple comparison test was used to determine the significance of differences between groups (P < 0.05).

[0067] III. Results of index analysis (I) Biomass and root-shoot ratio analysis Biomass and root-shoot ratio are important indicators for evaluating plant growth potential and stress tolerance. Under cadmium stress, changes in root-shoot ratio reflect the plant's ability to adjust its photosynthate distribution strategy, which in turn affects its cadmium tolerance.

[0068] Table 1 Fresh weight, dry weight, and root-shoot ratio of Chinese cabbage plants

[0069] Note: Different lowercase letters in the same column indicate significant differences (P < 0.05, Duncan's test) As shown in Table 1, different concentrations of LMT treatment had a significant impact on the growth of Chinese cabbage plants. The fresh weight of the aboveground part showed a trend of LMT30 > LMT60 > LMT120 > LMT0, with the fresh weight of the aboveground part in the LMT30 treatment (22.9 ± 1.5 g) being significantly increased by 89.2% compared to the control group (12.1 ± 0.7 g). The root fresh weight also showed a similar trend, with the root fresh weight in the LMT30 treatment (0.67 ± 0.06 g) being increased by 91.4% compared to the control group. The dry weight index was basically consistent with the fresh weight results, with the aboveground dry weight and root dry weight in the LMT30 treatment being increased by 82.5% and 133.3%, respectively, compared to the control group. The fresh weight root-shoot ratio analysis showed no significant difference between the treatments (P > 0.05), with the ratio maintaining at 0.029-0.031. The dry weight root-shoot ratio showed a trend of LMT60 ≈ LMT30 > LMT120 > LMT0, with the LMT30 and LMT60 treatments being significantly higher than the control group.

[0070] The results showed that (1) the growth-promoting effect was concentration-dependent: the fresh weight of the aboveground part and root in the LMT30 treatment was increased by 89.2% and 92.2%, respectively, compared to the control group, and the dry weight increased by 82.5% and 133.3%, respectively, with the best growth-promoting effect. With the increase of concentration to 60 and 120 mg / L, the promoting effect gradually weakened. (2) The root-shoot ratio was relatively stable: there was no significant difference in fresh weight root-shoot ratio between the treatments (P > 0.05), with the ratio maintaining at 0.029-0.031, indicating that LMT mainly promotes plant growth as a whole rather than changing the biomass distribution pattern.

[0071] (II) Cadmium content analysis The Cd content in plant is the core index to evaluate the effect of Cd resistance agent, especially the Cd content in edible part (aboveground part) is directly related to the safety of agricultural products. As the main organ of Cd absorption, the change of Cd content in root can directly reflect the regulation mechanism of Cd resistance agent on heavy metal absorption process.

[0072] Table 2 Cd content in aboveground part and root of Chinese cabbage (mg / kg DW)

[0073] Note: The same column represents significant difference (P <0.05, Duncan test).

[0074] Table 2 shows that different concentrations of LMT treatment have different effects on the Cd content of Chinese cabbage. The Cd content in aboveground part shows LMT0≈LMT30≈LMT60>LMT120, in which the Cd content in aboveground part of LMT120 treatment (1.58±0.03 mg / kg) is significantly lower than that of the control group (1.76±0.09 mg / kg) by 10.5%, while LMT30 and LMT60 treatments have no significant difference with the control group. The root Cd content shows a decreasing trend of LMT0>LMT30>LMT60>LMT120, and there is significant difference among each treatment. The root Cd content of LMT30, LMT60 and LMT120 treatments is reduced by 4.7%, 7.6% and 10.0% respectively compared with the control group.

[0075] The results show that: (1) The effect of Cd resistance is concentration-dependent, the Cd content in aboveground part of LMT120 treatment is reduced by 10.5% (P <0.05) compared with the control group, and the root Cd content is reduced by 10.0%; low concentration treatment (30, 60 mg / L) has no significant effect on the Cd content in aboveground part, but the root Cd content shows a decreasing trend. (2) The effect of root Cd resistance is more obvious, all LMT treatments significantly reduce the root Cd content (4.7%-10.0%), which indicates that LMT may play a role in Cd resistance by inhibiting the absorption of root Cd.

[0076] (Three) Analysis of antioxidant enzyme activity Cadmium stress can induce the accumulation of reactive oxygen species in plants, leading to oxidative damage. Antioxidant enzyme system (SOD, POD, CAT, APX) is an important defense mechanism for plants to cope with Cd stress, and plays a key role in scavenging reactive oxygen species and maintaining redox balance.

[0077] Table 3 Antioxidant enzyme activity in leaves of Chinese cabbage

[0078] Note: The same column represents significant difference (P <0.05, Duncan test).

[0079] Table 3 shows that different concentrations of LMT treatment had a significant effect on the antioxidant enzyme activity of Chinese cabbage plant leaves. The SOD activity showed LMT30 > LMT120 > LMT60 > LMT0, with LMT30 treatment significantly increasing SOD activity (660 ± 70 U / g FW) by 34.9% compared to the control group (490 ± 55 U / g FW). The POD activity showed LMT60 ≈ LMT120 > LMT0 ≈ LMT30, with LMT60 and LMT120 treatments increasing by 23.8% and 22.8% respectively compared to the control group. The CAT activity showed LMT120 > LMT60 > LMT30 > LMT0, with LMT120 treatment significantly increasing CAT activity (515 ± 50 U / g FW) by 26.4% compared to the control group. The APX content only increased significantly in LMT30 treatment, increasing by 97.9% compared to the control group, with the rest of the treatments showing no significant difference.

[0080] The results showed that: (1) Different concentrations activate different enzyme systems, LMT30 mainly increases the activities of SOD (+34.9%) and APX (+97.9%); LMT60 and 120 mainly activate the activities of POD (+23.8%) and CAT (+26.4%). (2) Synergistic defense mechanism, the coordinated improvement of various antioxidant enzyme activities builds a comprehensive reactive oxygen species scavenging system, enhancing the plant's tolerance to cadmium stress.

[0081] (Four) Analysis of non-enzymatic antioxidant content Antioxidants are important secondary metabolites for plants to resist cadmium stress. Non-enzymatic antioxidants such as total phenols, flavonoids, and anthocyanins have strong free radical scavenging ability and can synergize with the antioxidant enzyme system to maintain cellular redox homeostasis.

[0082] Table 4 Antioxidant content of Chinese cabbage plant leaves (mg / g FW)

[0083] Note: The same column represents a significant difference (P < 0.05, Duncan's test).

[0084] As shown in Table 4, different concentrations of LMT treatment on the leaves of Chinese cabbage plants had a concentration-dependent effect on antioxidant content. The total phenol content showed an increasing trend of LMT120 > LMT60 > LMT30 > LMT0, with the total phenol content of LMT120 treatment (2.64 ± 0.02 mg / g FW) being significantly increased by 23.2% compared with the control group (2.14 ± 0.16 mg / g FW). The flavonoid content showed a change rule of LMT120 ≈ LMT60 > LMT30 ≈ LMT0, with the LMT60 and LMT120 treatments being increased by 20.1% and 24.4% respectively compared with the control group. The anthocyanin content changed most significantly, showing a trend of LMT120 > LMT60 > LMT30 ≈ LMT0, with the anthocyanin content of LMT60 and LMT120 treatments being increased by 111.1% and 133.3% respectively compared with the control group.

[0085] The results showed that with the increase of LMT concentration, the total phenol (+23.2%), flavonoid (+24.4%), and anthocyanin (+133.3%) contents increased significantly, indicating that LMT could stimulate the plant secondary metabolic pathway and build a perfect non-enzymatic antioxidant defense system.

[0086] (Five) Membrane lipid damage and total antioxidant capacity analysis Membrane lipid peroxidation degree and total antioxidant capacity are comprehensive indicators for evaluating the oxidative stress status of plants. MDA, as an important product of membrane lipid peroxidation, its content directly reflects the degree of cell membrane damage; while the total antioxidant capacity and free radical clearance rate reflect the overall antioxidant defense level of plants. The comprehensive analysis of these indicators can fully evaluate the protective effect of cadmium control agent on plant oxidative damage and its mechanism.

[0087] Table 5 Antioxidant capacity and membrane lipid damage degree of Chinese cabbage plant leaves

[0088] Note: The same column represents significant difference (P < 0.05, Duncan's test).

[0089] As shown in Table 5, different concentrations of LMT treatment had a significant effect on the antioxidant capacity of the leaves of Chinese cabbage plants and the degree of membrane lipid damage. The MDA content was LMT0 > LMT120 > LMT60 > LMT30, and the MDA content of the LMT30 treatment (6.74 ± 0.57 nmol / g FW) was significantly reduced by 25.6% compared with the control group (9.06 ± 0.79 nmol / g FW), indicating that the degree of membrane lipid peroxidation was significantly reduced. The total antioxidant capacity showed a trend of LMT120 ≈ LMT60 > LMT30 > LMT0, and the LMT60 and LMT120 treatments were increased by 15.7% and 17.6%, respectively, compared with the control group. The hydroxyl radical clearance rate showed a trend of LMT120 > LMT30 > LMT60 > LMT0, and the clearance rate of the LMT120 treatment (69.6 ± 4.3%) was significantly increased by 40.5% compared with the control group (49.5 ± 3.6%).

[0090] The results showed that LMT30 was the most effective in protecting the cell membrane, with a 25.6% reduction in MDA content and a significant reduction in the degree of membrane lipid peroxidation; LMT120 enhanced the overall antioxidant capacity, with a 17.6% increase in total antioxidant capacity and a 40.5% increase in hydroxyl radical clearance rate.

[0091] (VI) Analysis of Hormone Balance Regulation Plant hormones are important signal molecules that regulate plant growth and development and stress adaptation. Under cadmium stress, the changes in the contents of hormones such as cytokinin (ZR), abscisic acid (ABA), auxin (IAA), and gibberellin (GA3) directly affect the growth status and stress resistance of plants. Analyzing the regulatory effect of cadmium blocking agents on the balance of plant endogenous hormones helps to elucidate the molecular mechanisms of their relief of cadmium stress from the perspective of hormone regulation.

[0092] Table 6 Hormone content (ng / g FW) of Chinese cabbage plant leaves

[0093] Note: The same column represents a significant difference (P < 0.05, Duncan's test).

[0094] As shown in Table 6, different concentrations of LMT treatment had a significant regulatory effect on the hormone content of the leaves of Chinese cabbage plants. The ZR content showed a decreasing trend of LMT0 > LMT30 > LMT60 > LMT120, and there were significant differences between each treatment. The ABA content showed a change rule of LMT0 > LMT120 > LMT60 > LMT30, and the ABA content of the LMT30 treatment (79±1 ng / g FW) was significantly lower than that of the control group (106±2 ng / g FW) by 25.6%. The IAA content showed a trend of LMT0 > LMT60 > LMT120 ≈ LMT30, and each LMT treatment was significantly lower than the control group, with a decrease of 33.9%-39.6%. The GA3 content showed a trend of LMT120 ≈ LMT30 > LMT0 > LMT60, and the LMT30 and LMT120 treatments were increased by 4.8% and 5.1% respectively compared with the control group.

[0095] The results showed that LMT treatment significantly reduced the content of stress-related hormones (ZR, ABA, IAA) by 33.6%, 25.6% and 39.6% respectively, while moderately increased the level of GA3 by 5.1%. This hormone regulation pattern helps to alleviate the inhibition of cadmium stress on plant growth.

[0096] (Seven) Comprehensive discussion This study showed that the rhizosphere irrigation of Moringa oleifera peptides played a role in blocking cadmium through the following multiple synergistic mechanisms: 1. Concentration effect. (1) 30 mg / L: the best growth-promoting effect, the fresh weight of the aboveground part increased by 89.2% compared with the control group, the root fresh weight increased by 91.4%, the SOD activity increased by 34.9%, the APX activity increased by 97.9%, and the MDA content decreased by 25.6%; but the cadmium content in the aboveground part decreased by 2.8% (P>0.05), which was suitable for application scenarios focusing on biomass improvement. (2) 60 mg / L: both growth promotion and cadmium blocking, the fresh weight of the aboveground part increased by 56.2%, the cadmium content in the aboveground part decreased by 3.0% (P>0.05), the cadmium content in the roots decreased by 7.6% (P<0.05), and the POD activity increased by 23.8%. (3) 120 mg / L: the best cadmium blocking effect, the cadmium content in the aboveground part decreased by 10.5% (P<0.05), the cadmium content in the roots decreased by 10.0% (P<0.05), while maintaining good growth-promoting effect (the fresh weight of the aboveground part increased by 35.5%), and the POD, CAT activities and total antioxidant capacity were significantly improved, which was the recommended concentration.

[0097] 2、Action mechanism summary. The prepared composite stable moringa peptide cadmium blocking preparation plays a role through the following multiple synergistic mechanisms: inhibiting root cadmium absorption (root cadmium content is reduced by 4.7%-10.0%), activating the antioxidant enzyme system (SOD is increased by 34.9%, CAT is increased by 26.4%), promoting the accumulation of antioxidants (anthocyanin is increased by 133.3%), protecting cell membrane integrity (MDA is decreased by 25.6%), regulating hormone balance (ABA is decreased by 25.6%, GA3 is increased by 5.1%), and promoting plant growth (biomass is increased by 89.2%).

[0098] 3、Key findings. (1) Blocking cadmium and promoting growth: LMT not only reduces cadmium absorption, but also promotes normal growth, avoiding the defect of traditional cadmium blocking agents that reduce cadmium but inhibit growth; (2) Roots are the key action site: all concentrations significantly reduce root cadmium content, verifying the targeting of rhizosphere irrigation; (3) Concentration selection needs to balance the target: in practical application, appropriate concentration should be selected according to the degree of soil cadmium pollution and production target.

[0099] (Eight) Comparative experiment verification To systematically verify the necessity of each component in the composite stabilizer system and the scientificity of the process parameters, the following 6 groups of comparative experiments were set. The experimental results are shown in Table 7.

[0100] Table 7 Summary of comparative experiment results

[0101] Note: Different lowercase letters in the same column indicate significant differences (P<0.05, Duncan's test).

[0102] “ 1 8.9% higher than the embodiment: 1.58x1.089=1.72.

[0103] “ 2 Equivalent to CK, degradation of moringa peptide leads to no cadmium blocking effect.

[0104] “ 3 Fresh weight of aboveground part is increased by only 14.3%: 12.1x1.143=13.8 (40% of the growth promoting effect of the embodiment).

[0105] “ 4 5.2% higher than CK: 1.76x1.052=1.85.

[0106] “ 5 3.7% higher than CK: 0.85x1.037=0.88.

[0107] “ 6 11% lower than CK: 12.1x0.89=10.8.

[0108] “ 7 "The coefficient of variation is 15.3%, and the standard deviation is 1.74 × 0.153 = 0.27."

[0109] “ 8 "A decrease of 10.9% compared to CK: 12.1 × 0.891 = 10.8."

[0110] Comparative analysis: Comparative Example 1: Pure Moringa Peptide Formulation (without stabilizer protection). In the soil environment, Moringa peptides rapidly degraded and became inactive. The cadmium content in the aboveground parts increased by 8.9% compared to the example, while the fresh weight of the aboveground parts increased by only 14.3% (42% of the growth-promoting effect of the example). The cadmium content in the roots was comparable to the control (0.85 mg / kg), indicating a complete loss of cadmium-inhibiting function. These results demonstrate that the composite stabilizer system plays a crucial role in maintaining the activity of Moringa peptides and achieving a sustained-release effect.

[0111] Comparative Example 2: Sodium alginate stabilizer alone. After removing nano-silica, the dispersibility of the formulation significantly decreased, and moringa peptides easily precipitated and aggregated, leading to a 5.2% (1.85 mg / kg) increase in cadmium content in the aerial parts and a 3.7% (0.88 mg / kg) increase in cadmium content in the roots compared to the control. The cadmium inhibition effect was actually worse than the blank control. This result indicates that sodium alginate alone cannot provide sufficient dispersion stability.

[0112] Comparative Example 3: Single nano-silica stabilizer. After removing sodium alginate, although it has a certain degree of dispersibility, it lacks the sustained-release protection of a gel carrier. Moringa peptides have poor persistence in the soil environment, and the fresh weight of the aboveground parts decreased by 11% (10.8g) compared with the control, proving that single nano-silica cannot provide long-lasting protection of bioactivity.

[0113] Comparative Example 4: Lower limit of stabilizer ratio (1:1.0). The low proportion of nano-silica resulted in insufficient dispersion stability, with a coefficient of variation of 15.3% for the measured cadmium content, indicating poor consistency in cadmium inhibition effect among different plants and difficulty in ensuring stable application results.

[0114] Comparative Example 5: Upper limit of stabilizer ratio (1:1.5). The excessive proportion of nano-silica (21 mg / L) caused fluctuations in the pH value of the rhizosphere microenvironment, which stressed the plant. The fresh weight of the aboveground parts decreased by 10.9% (10.8 g) compared with the control, proving that the excessive proportion actually inhibited the normal growth of the plant.

[0115] Comparative Example 6: Stabilizer concentration exceeded the standard (70 mg / L). After the concentration of the compound stabilizer was increased to 70 mg / L, the viscosity of the formulation increased significantly, the rhizosphere permeability decreased, and the root activity decreased by 9.6%. Although it still maintained a certain growth-promoting effect (fresh weight of the aboveground parts 14.2 g), the cadmium inhibition effect (cadmium in the aboveground parts 1.79 mg / kg) was significantly worse than that of the Example (1.58 mg / kg).

[0116] Overall conclusions: The system verification results of Comparative Examples 1-6 fully demonstrate that: (1) The necessity of the stabilizer system: Without stabilizer protection, Moringa peptides degrade rapidly, the growth-promoting effect is only 42% of that in the examples, and the cadmium inhibition function is completely lost, proving that the composite stabilizer system is indispensable. (2) The synergistic effect of the two components: Sodium alginate alone has poor dispersibility, resulting in a cadmium inhibition effect inferior to CK; Nano silica alone has a lack of sustained-release protection, resulting in a 11% decrease in biomass. The two components need to work together to exert the dual functions of "dispersion stabilization + sustained-release protection". (3) The scientific validity of the ratio range: When the stabilizer ratio deviates from the range of 1:1.0-1.5, it may be due to insufficient dispersion stability (coefficient of variation 15.3%) or excessive nanoparticles leading to rhizosphere stress (biomass decrease 10.9%), proving that the ratio range defined in the claims has a strict scientific basis. (4) Suitability of concentration range: When the concentration of stabilizer exceeds 60 mg / L, the viscosity of the preparation is too high, which leads to a decrease in rhizosphere permeability and damage to root vitality. This proves that 20-60 mg / L is the optimal concentration range that balances stability and bioavailability.

[0117] The above comparative verification results show that the composition, ratio and concentration design of the composite stabilizer system in the technical solution of the present invention have outstanding substantive features and significant progress, and are the key technical guarantee for achieving the dual effects of "high efficiency cadmium inhibition + growth promotion".

[0118] (ix) Technical significance The verification results of the above examples show that sodium alginate and nano-silica must work synergistically within a specific mass ratio (1:1-1.5) and concentration range (20-60 mg / L) to achieve stable dispersion, sustained-release protection, and efficient delivery of moringa peptides. The results of Comparative Examples 2-6 fully demonstrate that using any single stabilizer component alone or deviating from the optimal ratio range significantly reduces the dispersion stability, duration of action, or bioavailability of the formulation, verifying the necessity and inventiveness of the composite stabilizer system design in the technical solution of this invention.

[0119] The composite stabilizer type moringa oleifera peptide cadmium blocking preparation prepared by the application has good application effects within the range of limited process parameters (moringa oleifera peptide concentration 30-120 mg / L (preferably 120 mg / L), rhizosphere irrigation amount 40-60 mL / plant (preferably 50 mL / plant), application interval 3-7 days (preferably 5 days)). The preparation can reduce the cadmium content of the above part of small cabbage while promoting plant growth, and realizes the technical breakthrough of “blocking cadmium without inhibiting growth”. The technical scheme provides a scientific and feasible solution for safe production and utilization of farmland contaminated by cadmium in alkaline soil in the north, and has important application value and popularization prospect.

[0120] Although the application has been described in detail above with specific reference to general description and specific embodiments, some modifications or improvements can be made on the basis of the application, which is obvious to those skilled in the art. Therefore, these modifications or improvements made on the basis of not deviating from the spirit of the application are within the scope of the application claimed.

Claims

1. A composite stabilized moringa peptide cadmium blocking formulation, characterized in that, consists of the following components: moringa oleifera peptide, mass concentration of 30-120 mg / L; complex stabilizer, mass concentration of 20-60 mg / L, consisting of sodium alginate and nano-silicon dioxide at a mass ratio of 1:(1-1.5); phosphate buffer for adjusting the pH value of the cadmium-resistant preparation to 6.0-7.

0.

2. The cadmium blocking formulation of claim 1, wherein, The mass concentration of the moringa oleifera peptide is 110-120 mg / L.

3. A process for the preparation of the cadmium-resistant formulation according to claim 1 or 2, characterized in that, The method comprises the following steps: S1: Dissolve sodium alginate in phosphate buffer and stir until completely dissolved; add nano-silicon dioxide and ultrasonically treat until a gel is formed; S2: Add moringa oleifera peptide powder to the gel obtained in step S1 and homogenize to obtain a cadmium-resistant preparation.

4. The production method according to claim 3, characterized by, In step S1, the dissolution temperature of the sodium alginate is 50-70℃; the ultrasonic treatment conditions are: power of 300-500 W, temperature of 4-5℃, and time of 15-30 min.

5. The preparation method according to claim 3, characterized in that, In step S2, the homogenization treatment conditions are: first stir for 40-45 min under light shielding conditions, and then homogenize at a speed of 10,000-12,000 r / min at 4-5℃ for 20-30 min.

6. Use of the cadmium-resistant preparation of claim 1 or 2 in reducing cadmium absorption of Chinese cabbage planted in cadmium-contaminated soil.

7. A method for reducing cadmium uptake by Brassica chinensis planted in cadmium contaminated soil, characterized by, The method comprises the following steps: starting from the third day after Chinese cabbage seedling is completed, the rhizosphere is irrigated with the cadmium-resistant preparation of claim 1 or 2.

8. The method of claim 7, wherein, The irrigation conditions are: 40-60 mL of the cadmium-resistant preparation is irrigated per Chinese cabbage, irrigation is performed every 3-7 days, and irrigation is continuously performed for 3-5 times.

9. The method of claim 7, wherein, The cadmium-contaminated soil is alkaline and slightly contaminated with cadmium, the soil pH value is 6.5-7.5, and the total cadmium content is 0.8-2.0 mg / kg.

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