82 results about "Soil cadmium" patented technology

The invention belongs to the technical field of biology, and particularly relates to plant growth promoting performance of two alkali-producing strains, namely, Plutalophilous rhizobium and Pseudomonas moorsei, and application of the two alkali-producing strains to cadmium fixation and fertility increase of soil. The invention provides a multifunctional alcaligenes, which is any one of the following strains: Pentazobacterium mionense WW22, the preservation number of which is CGMCC (China General Microbiological Culture Collection Center) No. 27718, and the preservation number of which is CGMCC No. 27718. The invention discloses pseudomonas mohnii WW2, and the preservation number of the pseudomonas mohnii WW2 is CGMCC (China General Microbiological Culture Collection Center) No.27716. The invention also provides application of the strain for fixing cadmium and increasing fertility. The strain disclosed by the invention can promote the reduction of the effectiveness of cadmium in soil and increase the nutrient content in the soil, provides a technical basis for ensuring the safe production and utilization of crops in a cadmium-polluted farmland, and has a wide application prospect.

The invention relates to the technical field of microorganisms, and particularly discloses a nitrogen-fixing and cadmium-reducing microbial agent as well as a preparation method and application thereof. The microbial agent consists of bacillus pseudomycoides, lactococcus lactis, azotobacter chroococcum and biochar, wherein the biochar is obtained by pyrolyzing and carbonizing rice straws. The bacillus pseudomycoides can reduce the bio-availability of soil cadmium; lactococcus lactis can secrete a large number of biological active substances such as exopolysaccharides and enzymes, and the activity of other microorganisms is stimulated and improved; azotobacter chroococcum converts nitrogen in air into ammonium, amino acid and peptide which can be utilized by plants and promotes plant growth, and released metallothionein contains free sulfydryl which is combined with Cd ions, so that a stable sulfide compound is formed. The biological carbon adsorbs and fixes the three bacteria, so that the microorganisms can continuously and effectively play a role and have a mutual synergistic effect, the fixation of Cd in the soil is further enhanced, the availability of nitrogen is improved, and the plant growth is effectively promoted.

The invention relates to the technical field of soil cadmium remediation, in particular to a soil Cd recognition and remediation method based on mulberry root exudates and microorganisms. According to the method, spatial microscopic image frames of rhizosphere microflora are divided through a community structure, community node increment updating calculation of adjacent time sequences is executed, the transition recombination frequency of the rhizosphere microflora is obtained, and the transition color of the actual concentration content of root exudates is rendered based on a metal pollution level system and the transition recombination frequency. Generating a stress level heat model of the soil cadmium gradient in the target restoration area; and according to the stress level popularity model, carrying out popularity color analysis and identification on the soil cadmium pollution of the target restoration area, and generating a global stress identification result of the soil cadmium. According to the method, rapid identification of cadmium pollution enrichment can be realized by utilizing the synergistic response between mulberry root exudates and rhizosphere microorganisms, and a repair regulation and control plan is made, so that the cadmium pollution degree is reduced, the soil structure and fertility are optimized, and a safer and healthier environment is provided for plant growth.

The present invention discloses a method for analyzing sources of Cd / Pb combined polluted farmland soil using bimetallic isotopes (Cd—Pb), comprising the following steps: collecting respectively a soil sample and risk source samples through a sample collection device; determining respectively Cd isotope ratio and Pb isotope ratio of the soil sample and the risk source samples; plotting by using the Cd isotope ratio and the Pb isotope ratio of the soil sample and the risk source samples as coordinates, to obtain a projection plot of the isotope ratios; recognizing a pollution end-member polluting farmland soil through the projection plot of the isotope ratios to obtain a recognition result for the pollution end-member, and then confirming the pollution end-member; and calculating a relative contribution rate of the pollution end-member, to obtain an analysis result for the source of isotopes. The present invention uses the two metal isotopes of Cd—Pb to mutually restrict and confirm each other to solve the problem of poor analytical accuracy caused by similar or overlapping isotope values of samples and isotope fractionation, and realizes accurate recognition and quantitative analysis for the source of heavy metals Cd / Pb pollution of farmland soil.

The invention belongs to the technical field of heavy metal pollution treatment, and relates to preparation of a weakly alkaline soil cadmium passivator and a method for passivating soil lead. The alkalescent soil cadmium passivating agent mainly comprises the following components in parts by weight: 20 to 30 parts of graphene oxide modified biochar, 5 to 10 parts of montmorillonite, 5 to 10 parts of bentonite and 5 to 10 parts of a microbial agent, the microbial agent is a composite microbial agent formed by mixing bacillus subtilis, bacillus amyloliquefaciens, bacillus thuringiensis and pseudomonas nitroreducens. The alkalescent soil cadmium passivator has a very good remediation effect on cadmium and lead in polluted soil, can remarkably improve the physicochemical properties of the cadmium and / or lead polluted soil, increase the content of organic matters in the soil, reduce the migration of the soil in the environment and reduce the content of cadmium in crops, and has a great market popularization value.

The invention relates to the technical field of data processing, and provides a comprehensive intelligent evaluation method and system for a soil conditioning effect, and the method comprises the steps: obtaining the soil cadmium content, the crop cadmium content and the soil acidity and alkalinity of a plurality of soil samples of a plurality of soil types after multiple times of conditioning, and the conditioner cost of each time of conditioning; dividing the soil sample to obtain a plurality of pollution categories; according to the soil cadmium content change and change difference of the same soil sample after adjacent conditioning, the soil passivation degree of each soil sample under the soil cadmium content after each conditioning is obtained; the conditioning response degree of each soil sample under the soil cadmium content is obtained; the remediation contribution degree of each pollution category under the soil cadmium content is obtained; and obtaining the grey correlation degree of each evaluation index and other evaluation indexes in each pollution category, so as to construct a conditioning evaluation model. The invention aims to solve the problem of inaccurate evaluation caused by the fact that the influence of soil quality and pollution degree is not considered in the evaluation process of the soil conditioning effect.

The invention discloses a heavy metal blocking agent special for rice and a method for reducing the cadmium content of rice grains by using the heavy metal blocking agent, and belongs to the technical field of agricultural environment protection and polluted soil remediation. The heavy metal blocking agent special for rice comprises the following raw materials: 20-30% of molybdenum disulfide, 10-20% of diammonium hydrogen phosphate, 5-10% of disodium magnesium ethylene diamine tetraacetate, 5-10% of zinc ethylene diamine tetraacetate, 10-20% of a silicon fertilizer, 1-2% of a cosolvent, 1-2% of a solubilizer, 1-2% of ethanol and the balance of water. The special heavy metal blocking agent for the rice can effectively inhibit heavy metal cadmium from being transferred into rice grains, obviously reduce the cadmium content of the rice grains, obviously improve the yield of the rice grains, and can obviously reduce the cadmium content in the rice and ensure that the cadmium content in the rice grains meets the national food hygiene standard when being applied to the rice planted in a rice field with soil polluted by cadmium.

The invention relates to the technical field of cadmium-reducing soil conditioners, in particular to an acid soil cadmium-reducing conditioner and intelligent production device.The acid soil cadmium-reducing conditioner comprises a supporting assembly and a tank body, a groove is formed in one side of the tank body, a discharging valve is arranged at the bottom end of the tank body, a tank cover is arranged at the upper end of the tank body, a material overturning assembly is arranged in the tank body, and a vertical filter press is arranged on one side of the tank body; a flash dryer is arranged on one side of the vertical filter press, the vertical filter press is connected with a discharging valve at the bottom end of the tank body through a connecting pipe, a material conveying mechanism is arranged on one side of the tank body, a fixing block is arranged in the material conveying mechanism, a fixing cylinder is arranged at the bottom end of the fixing block, a through hole is formed in one side of the fixing cylinder, a material conveying pipe is arranged on one side of the fixing cylinder, and a feeding hopper is arranged on the material conveying pipe; a fixing block is arranged in the tank body, an auxiliary gear is arranged on the fixing block, a screw rod is arranged on the auxiliary gear, a mixing mechanism is arranged in the tank body, a limiting ring is arranged in the mixing mechanism, a servo motor is arranged in the mixing mechanism, a stirring assembly is arranged at the output end of the servo motor, and a transmission rod is arranged in the stirring assembly.

The invention relates to the technical field of planting environment detection, in particular to a pepper planting environment anomaly detection method based on data analysis. Comprising the following steps: obtaining a soil root system coupling characterization value based on the time span difference between a soil cadmium ion concentration fluctuation sequence and a soil pH value fluctuation sequence and the time span difference between a zanthoxylum bungeanum root system cadmium ion concentration fluctuation sequence and a zanthoxylum bungeanum root system pH value fluctuation sequence and the same sequence subsequence, a soil root system propagation direction characterization value is obtained based on a starting moment difference and a range difference between a soil cadmium ion concentration fluctuation sequence and a pepper root system cadmium ion concentration fluctuation sequence, and a fixed experience lag order is adjusted based on a soil root system coupling characterization value and the soil root system propagation direction characterization value to obtain an optimized lag order. And performing anomaly detection on the soil cadmium content of the pepper planting detection area based on the ARMA model with the order being the optimized lag order. Moreover, the method can improve the detection accuracy of the abnormality of the pepper planting environment.

The invention relates to the technical field of fertilizers, in particular to a fertilizer for relieving soil cadmium pollution and a preparation method thereof. The fertilizer for slowing down cadmium pollution of soil comprises the following raw materials in parts by weight: 30-50 parts of a modified charcoal-based carrier, 10-20 parts of a compound microbial agent, 15-25 parts of a nano mineral passivator, 5-10 parts of a chelated trace element compound fertilizer and 10-15 parts of potassium humate. Through a specific cascade domestication method, the compound bacterial system gradually adapts in a cadmium-containing environment and generates a synergistic metabolism mechanism, then the compound bacterial system is combined with the nano mineral modified by organic intercalation, and the nano mineral not only has strong adsorption capacity to cadmium, but also has strong adsorption capacity to cadmium. And the organic groups modified on the surface can also provide colonization sites and nutrition signals for the domesticated functional bacteria to form a triple barrier of'nano mineral physical passivation-functional bacteria biological resistance and control-metabolite complexing and curing ', so that the long-term effect and stress resistance of passivation are remarkably improved.

The invention belongs to the technical field of heavy metal pollution treatment, and discloses a method for reducing soil cadmium activity and wheat grain cadmium content. According to the method, the low-cadmium-accumulation wheat variety is selected, the composite conditioner is applied, the low-cadmium-accumulation wheat variety is Jimai 22, and the composite conditioner is composed of mineral source potassium fulvate and zinc fertilizer. The complex passivation effect of humic acid components in mineral source potassium fulvate on soil heavy metal is utilized, the ion antagonism effect of zinc and cadmium and the low cadmium accumulation characteristic of Jimai 22 are combined, the cadmium content of wheat grains is synergistically reduced to 0.1 mg / kg or below, meanwhile, the cadmium content of the soil can be remarkably reduced, and the soil with cadmium exceeding the standard can be repaired. The treatment method provided by the invention has the advantages of simple operation, easily available raw materials, low cost, stable synergistic cadmium reduction effect and the like.

The invention discloses a rice-shrimp co-cropping-based cadmium-polluted rice field safe utilization method, which comprises the following steps that 1, a cadmium-polluted rice field to be treated is selected, the cadmium content in the cadmium-polluted rice field to be treated is 0.40-1.50 mg / kg, and the pH range of the cadmium-polluted rice field is 5.5-6.5; 2, a compound fertilizer containing urea, diammonium phosphate and potassium sulfate is applied to the cadmium-polluted rice field to be treated, and rice seedlings are transplanted according to the line spacing of 20-25 cm and the plant spacing of 10-15 cm after ploughing and uniform mixing; 3, after the seedlings turn green, young Australian freshwater lobsters with the body length of 2-5 cm are put in; 4, harvesting rice and lobsters in the rice mature period. The invention aims to significantly reduce the cadmium content in rice through the rice-shrimp co-cropping system and reduce the effectiveness of soil cadmium.

The invention belongs to the technical field of heavy metal repair, and particularly relates to a soil heavy metal passivator containing selenium modified charcoal and a preparation method and application of the soil heavy metal passivator. According to the soil heavy metal passivator based on the selenium-modified biochar, the biochar is modified through the selenium element, the selenium element loaded on the biochar achieves effective adsorption of mercury, arsenic and cadmium in soil through the synergistic effect of the selenium element loaded on the biochar and organic functional groups of the biochar, and the selenium element loaded on the biochar and the biochar achieve the synergistic effect; effective adsorption of part of cadmium, arsenic and mercury is realized, effective fixation of arsenic, mercury and cadmium in soil is finally realized, and the fixation efficiency is high. The invention further provides application of the selenium modified charcoal soil heavy metal passivator obtained by the scheme or the selenium modified charcoal soil heavy metal passivator obtained by the preparation method in remediation of soil mercury pollution, soil arsenic pollution and soil cadmium pollution. The selenium modified charcoal soil heavy metal passivator disclosed by the invention can be directly added into soil to effectively fix arsenic, mercury and cadmium.

The invention discloses a phosphate-solubilizing bacterium with dual functions of phosphate solubilizing and passivation, a microbial agent prepared from the phosphate-solubilizing bacterium and application of the phosphate-solubilizing bacterium, the phosphate-solubilizing bacterium is Bacillus sp and is preserved in Guangdong Microbial Culture Collection Center, and the preservation number of the phosphate-solubilizing bacterium is GDMCC NO: 66609. Through multiple rounds of screening, the strain capable of dissolving phosphorus, producing urease, IAA and siderophore, promoting corn growth and improving cadmium and lead tolerance of plants is obtained, the strain can greatly improve underground biomass of corn, meanwhile, urease, IAA and siderophore are produced, effectiveness of soil cadmium is reduced, and soil fertility is improved. The fertilizer can increase the yield of corn, improve the soil fertility and improve the market competitiveness of agricultural products. The phosphate-solubilizing bacterium disclosed by the invention is easy to culture and apply on a large scale, simple and convenient to operate, easy to accept and apply by agricultural producers, and relatively high in practicability. The strain and the preparation have relatively high agricultural application prospects and economic values.

The invention belongs to the technical field of soil heavy metal pollution remediation, and discloses an acid soil cadmium-reducing modifier, a preparation method, a use method and application, the modifier is formed by mixing sulfydryl minerals, biochar and a compound organic fertilizer according to a certain configuration, the sulfydryl mineral is prepared from calcium carbonate, bentonite and 3-mercaptopropyl triethoxy silane. When the soil conditioner is used, the soil conditioner is uniformly applied to a soil plough layer by 0-20 cm manually or mechanically, and the applied soil conditioner accounts for 1-5% of the mass of soil or is 180-220 kg / mu. The soil cadmium-reducing modifier can obviously reduce the effective state content of heavy metal cadmium in the soil, so that the cadmium content in planted rice grains is obviously reduced, the organic matter content of the soil is obviously increased, the ecological environment of polluted farmland soil is improved, the growth of the rice is promoted, and the yield of the rice is increased. The soil conditioner disclosed by the invention is simple to prepare and environment-friendly to soil, and safe utilization of cadmium-polluted farmland soil can be realized.

The invention discloses a method for cultivating low-cadmium accumulation rice through CRISPRCas9 saturated editing of an OsHMA3 promoter, and belongs to the technical field of crop molecular breeding. According to the method, gene editing is carried out on an upstream 500bp region of an OsHMA3 gene of a rice variety ZH11 through an agrobacterium-mediated transformation method, and on the premise that the agronomic traits of rice are not affected, the cadmium interception capacity of a root system is enhanced, the cadmium accumulation amount in overground parts and grains is reduced, and the yield of the rice is improved. The HMA3-Pro3 mutant does not influence the absorption and accumulation of necessary elements such as zinc, manganese, iron and the like. The invention provides an efficient and safe non-transgenic low-cadmium rice cultivation technology, provides technical support and excellent varieties for safe utilization of cadmium-polluted farmland, and provides a new solution for solving the food safety problem caused by soil cadmium pollution.

This invention belongs to the field of heavy metal pollution remediation technology, and relates to the preparation and application of a cadmium passivating agent for weakly alkaline soil. The weakly alkaline soil cadmium passivating agent mainly comprises the following components by weight: 30-50 parts of a mineral complex, 40-60 parts of a bioactive component, and 5-15 parts of an auxiliary stabilizer. The mineral complex includes natural sepiolite, calcium-based bentonite, and a polyether-polyester diblock copolymer; the bioactive component includes microbial agents, phosphorus-modified biochar, lecithin, and phosphatidylserine; and the auxiliary stabilizer includes nano-hydroxyapatite and a chitosan-grafted polyaspartic acid complex. This weakly alkaline soil cadmium passivating agent exhibits excellent remediation effects on cadmium in contaminated soil, effectively preventing or reducing the entry of cadmium and other heavy metals into the food chain, and has significant market potential.

The present application belongs to the field of agricultural pest control, and particularly relates to a method for improving the content and insecticidal activity of exogenous insecticidal protein of insect-resistant transgenic cotton. The method is realized by the following steps: maintaining the soil cadmium concentration at 1-5 mg / kg when the cotton is at the three-leaf stage; and maintaining the soil cadmium concentration at 1-4 mg / kg when the cotton is at the five-leaf stage. The method provided by the present application can significantly improve the content and insecticidal effect of exogenous insecticidal protein of insect-resistant transgenic cotton, and enhance the insecticidal activity against cotton bollworms. The method provided by the present application can improve the control effect on pests while controlling cadmium pollution when planting transgenic insect-resistant cotton on land contaminated by a certain concentration of cadmium, and reduce the use of insecticides. Therefore, the present application provides an effective reference for improving the control effect on pests when planting insect-resistant transgenic cotton on land contaminated by cadmium, and has important practical value and significance.

The invention relates to an in-situ preparation method and application of an earthworm cast-based blocking and controlling agent for soil Cd pollution, and the preparation method comprises the following steps: (1) uniformly mixing cow dung, a bulking agent and biochar, and adjusting the water content to 55-75% to obtain a mixture; (2) performing primary fermentation on the mixture obtained in the step (1) to obtain an earthworm bed base material; (3) spreading the earthworm bed base material obtained in the step (2) in a strip shape, putting a plurality of adult earthworms, and culturing to obtain earthworm raw manure; and (4) carrying out secondary fermentation, drying, crushing and sieving, stirring, heating and granulating, cooling, secondary sieving, packaging and inspecting on the earthworm cast collected in the step (3) to obtain the target earthworm cast-based blocking and controlling agent. The earthworm cast-based blocking and controlling agent is prepared through multi-step process optimization in-situ production, multiple functions of earthworm cast in soil Cd pollution remediation, nutrient improvement and plant growth promotion are achieved, and then the goals of soil heavy metal pollution relief treatment and high-yield and high-quality production are achieved.

The application belongs to the field of soil remediation, and discloses a preparation method of selenium-rich biochar capable of reducing soil cadmium bioavailability and application of the selenium-rich biochar, the preparation method of the selenium-rich biochar comprising the following steps: taking biomass grown in a selenium-rich area, air-drying and grinding, and then calcining at 400-800 DEG C for 1-3 hours to obtain the selenium-rich biochar; and application of the selenium-rich biochar in soil cadmium pollution treatment is disclosed.The preparation method of the selenium-rich biochar is simple, the reaction is mild, the safety is high, the environmental pollution is small, and the selenium-rich biochar contains a certain amount of selenium and can reduce soil cadmium bioavailability to a certain extent.

The invention discloses a cadmium and arsenic combined pollution plant response dynamic monitoring system based on time sequence image analysis. The system comprises a multi-temporal image acquisition module, a self-adaptive registration engine, a response feature decoupling extraction module, an illumination environment normalization module and a pollution early warning decision module. View angle offset is eliminated through timing sequence image accurate registration, and pollution response and natural growth are separated through response feature decoupling. Non-pollution interference is eliminated through illumination environment normalization, an early warning system can recognize pollution signals when the soil cadmium and arsenic concentration is lower than the national standard limit value 50% through pollution early warning decision, the monitoring accuracy rate reaches 95% or above, the pollution risk is found 3-5 weeks ahead of time compared with a traditional method, and an effective technical means is provided for soil heavy metal pollution prevention and control.

The invention relates to the technical field of woody peat humus compositions, in particular to an iron-modified woody peat humus composition and application thereof in synchronous passivation of cadmium and arsenic in soil, and the iron-modified woody peat humus composition comprises the following raw materials: woody peat, a composite iron modifier, ammonium sulfate, monopotassium phosphate and microbial fermentation liquor. The composite iron modifier overcomes the problem that free iron is easy to precipitate in acid soil, and ensures stable release and efficient utilization of iron ions; secondly, iron ions can be subjected to complex reaction with carboxyl, phenolic hydroxyl and other functional groups in humic acid to form a stable organic-inorganic compound; zeolite can remarkably improve the cadmium adsorption capacity and enhance the dispersity of iron active components through ion exchange, and cadmium and arsenic are synchronously and efficiently passivated.

The application relates to the cross field of photocatalytic composite materials and soil environment remediation technology, and specifically discloses a three-dimensional graphene aerogel loaded cadmium sulfide quantum dot composite material, a preparation method and application of the composite material in soil cadmium pollution remediation, the composite material is composed of a three-dimensional interconnected porous sulfur-doped graphene aerogel skeleton and in-situ anchored cadmium sulfide quantum dots, the cadmium sulfide quantum dots have a particle size of 2-10 nm, a loading amount of 10 wt%-25 wt%, a surface sulfur vacancy density of 5%-8%, the skeleton has a sulfur atom content of 2 at%-5 at%, and the two are connected through a carbon-sulfur-cadmium covalent bridge; the material has a hierarchical porous structure with longitudinal through macropores of 20-80 mu m and intrawall mesopores of 2-20 nm, the material is prepared by adopting a three-stage programmed hydrothermal method, and a sulfur source is released in stages by 30%-50% excess thioacetamide to drive the formation of an epoxy group nucleophilic ring-opening anchor point, in-situ nucleation of quantum dots and generation of surface sulfur vacancies.

The present invention belongs to the field of soil environmental remediation technology, and specifically relates to the application of biochar in simultaneously reducing the cadmium content and methane emissions in cadmium-containing paddy fields. The application of biochar in the treatment of soil cadmium pollution and methane emission reduction, wherein the specific surface area of ​​the biochar is greater than 200m 2 g ‑1 . The biochar of the present invention has the advantages of rich pore structure, large specific surface area, small pore size, etc., and can adsorb DOC in the soil that can be absorbed and utilized by methanogenic microorganisms. The H / C and O / C of biochar are low, and the ash content is increased, which changes the physical and chemical properties of the soil and plays the role of a soil conditioner; at the same time, the number and types of hydroxyl, carboxyl and carbonyl oxygen-containing functional groups are reduced, the stability is increased, and the adsorption capacity is strong, which can increase the content of residual cadmium in the soil that is not easily absorbed and utilized by plants, and reduce the content of exchangeable cadmium in the soil.

The utility model discloses a screening device for soil cadmium pollution detection, which comprises a device main body, an assembling groove is arranged at the center of the device main body, a lifting frame is assembled in the assembling groove, a driving mechanism in transmission connection with the lifting frame is assembled in an inner cavity of the device main body, and a screening cylinder is assembled in the lifting frame. A sealing cover assembly is assembled between the lifting frame and the screening barrel. The soil screening device is used for screening soil in a laboratory when cadmium pollution of the soil is detected, the driving mechanism is arranged, the lifting frame is driven by the driving mechanism to move up and down in a reciprocating mode, the screening barrel is made to complete screening operation on the soil, and compared with traditional manual screening, the labor intensity of operators can be relieved, and meanwhile the screening efficiency is improved.

This invention discloses a methylbacterium XC1 strain screened from the rhizosphere soil of contaminated paddy fields. Methylbacterium XC1 can stably survive in cadmium-contaminated soil and effectively fix available cadmium in the soil, thereby reducing the content of available cadmium in the soil and achieving effective remediation of cadmium pollution in the soil.

This invention discloses a combined microbial agent and its method for promoting plant growth and soil remediation. The combined microbial agent comprises an inoculum of the arbuscular mycorrhizal fungus *Gloydius juvenilee* and a fermentation broth and / or suspension of *Methylobacterium XC1*. The combined microbial agent can increase rice seedling height, root length, and biomass accumulation, inhibit the migration of cadmium from cadmium-contaminated soil to the aboveground parts of rice seedlings, and simultaneously promote the conversion of soil cadmium to a stable / residual state with low bioavailability.

The application discloses a soil cadmium environmental ecological toxicity data screening processing method and application, and comprises the following steps: S1, obtaining ecological toxicity data, S2, screening data, S3, processing data, the screening processing method can obtain high-quality data, and the data is processed to a uniform level, which is more convenient for analysis and calculation; through the simulation of the species sensitivity distribution model by using the screened data, fitting parameters can be obtained, and the sensitivity distribution of ecological species to pollutants can be mastered to a large extent according to limited ecological toxicity data.

The invention relates to a method for repairing cadmium-polluted soil by using hyperaccumulator nightshade, which comprises the following steps: S1, experimental design: transplanting nightshade seedlings into polluted soil with different cadmium concentrations, setting a plurality of cadmium concentration gradients, and applying nitric oxide (NO) solutions with different concentrations in the growth period of nightshade; s2, data processing and analysis: measuring biomass, cadmium content and stress resistance index of each organ of the black nightshade and soil cadmium content, and carrying out statistical analysis. Compared with a traditional contaminated soil treatment method, the technical scheme has the advantages of being low in treatment cost, small in work amount, high in operability, easy to popularize in a large area and the like.

Provided are Citrobacter freundii and the use thereof. The Citrobacter freundii has a high cadmium tolerance and the function of enhancing selenium bioavailability. The strain is classified as and named Citrobacter freundii DS, which has been deposited in the CCTCC on 26 May 2022. The strain has a high tolerance to the heavy metal cadmium. The strain can still grow under the conditions of a Cd2+ concentration of 6 mM, reaching the maximum biomass at 40 h. By means of applying the strain to cadmium-contaminated soil, the proportion of exchangeable cadmium and the content of available cadmium in the soil can be significantly decreased, while significantly increasing the content of soluble selenium and available selenium in the soil. By means of performing a rice pot experiment, the cadmium bioaccumulation factor in various parts of rice is further reduced, while increasing the selenium bioaccumulation factor and translocation factor. The strain has significant effects in the applications of remediating cadmium-contaminated soil, enhancing the bioavailability of selenium and promoting crop growth.