A model for intercropping restoration of heavy metal contaminated soil with hyperaccumulator plants and low-accumulator crops and its construction method

Abstract

The present invention provides a model for intercropping restoration of heavy metal contaminated soil between hyperaccumulators and low-accumulator crops and a construction method thereof, and belongs to the technical field of heavy metal contaminated soil restoration models. The invention comprises the following steps: planting hyperaccumulators and low-accumulator crops according to the intercropping pattern of hyperaccumulators and low-accumulator crops; collecting parameter information, performing regression analysis, constructing a heavy metal low-accumulator crop yield model and a heavy metal contaminated soil restoration efficiency model; and verifying the heavy metal low-accumulator crop yield model and the heavy metal contaminated soil restoration efficiency model by trial and error. The establishment of the intercropping competition yield model and the restoration efficiency model between low-accumulator crops and hyperaccumulator plants clarifies the competitive relationship between intercropped plants, provides a theoretical basis for evaluating the restoration effect of the intercropping pattern, helps to demonstrate and promote the intercropping restoration technology, and is of great significance to the social, economic, and ecological benefits of the restoration area.

Description

Technical Field

[0001] The present invention relates to the technical field of heavy metal contaminated soil remediation models, and in particular to a heavy metal contaminated soil intercropping remediation model with hyperaccumulator plants and low-accumulator crops and a construction method thereof. Background Art

[0002] In recent years, heavy metal pollution in farmland in my country has become increasingly serious, causing great harm to the quality of agricultural products and human health. The safe utilization and restoration of heavy metal polluted farmland is imminent. In heavy metal polluted farmland, intercropping of farmland crops with heavy metal hyperaccumulators, harvesting the aboveground parts of the hyperaccumulators after they mature, and centralized processing can ensure agricultural production while repairing the heavy metal pollution in farmland soil, gradually reducing the risk of excessive heavy metals in crops. However, in actual planting, there is a lack of quantitative models that can accurately characterize the relationship between farmland crops and hyperaccumulators in intercropping systems to guide practical applications. Summary of the invention

[0003] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0004] The present invention provides a method for constructing an intercropping restoration model of heavy metal contaminated soil hyperaccumulator plants and low-accumulator crops, comprising the following steps:

[0005] (1) Planting superaccumulators and low-accumulator crops in an intercropping pattern;

[0006] (2) The number of hyperaccumulators, the amount of heavy metals extracted from the aboveground parts of low-accumulator crops, and the amount of heavy metals extracted from the aboveground parts of hyperaccumulators were collected as independent variables, and the yield of low-accumulator crops was used as the dependent variable for regression analysis to construct a yield model for low-accumulator crops;

[0007] (3) Collect the number of hyperaccumulators, the amount of heavy metals extracted from the aboveground parts of hyperaccumulators, the aboveground biomass of hyperaccumulators, and the grain yield of low-accumulator crops as independent variables, or collect the number of hyperaccumulators, the amount of heavy metals extracted from the aboveground parts of hyperaccumulators, the aboveground biomass of hyperaccumulators, and the aboveground biomass of low-accumulator crops as independent variables, and use the restoration years as the dependent variable to conduct regression analysis and construct a heavy metal contaminated soil restoration efficiency model;

[0008] (4) The trial-and-error method was used to verify the heavy metal low accumulation crop yield model and the heavy metal contaminated soil remediation efficiency model.

[0009] Preferably, the heavy metal includes one of arsenic, cadmium, lead, zinc and copper.

[0010] Preferably, the hyperaccumulator plants include one or more of centipede grass, nightshade, grain amaranth, pennisetum, Indian mustard, Bidens pilosa, amaranth and Dipsacus asper.

[0011] Preferably, the low accumulation crops include one or more of corn, wheat, soybean, sorghum, millet and cotton.

[0012] Preferably, the intercropping pattern is: planting low-accumulation crops in wide and narrow rows, and intercropping wide rows with single-row super-accumulator plants; or planting low-accumulation crops in wide and narrow rows, and intercropping wide rows with double-row super-accumulator plants; or planting low-accumulation crops with equal-width row spacing, and intercropping single-row super-accumulator plants; or planting low-accumulation crops with equal-width row spacing, and intercropping double-row super-accumulator plants; or intercropping low-accumulation crops and super-accumulator plants with equal-row spacing.

[0013] Preferably, in the wide-row and narrow-row planting of the low-accumulating crops, the row spacing width of the wide rows is 80-120 cm, and the row spacing width of the narrow rows is 30-50 cm; the row spacing width of the low-accumulating crops in the equal-width row planting is 80-120 cm; the row spacing width of the single-row super-accumulator plants is 40-60 cm, and the row spacing width of the double-row super-accumulator plants is 25-40 cm; the row spacing width of the equal-row intercropping of the low-accumulating crops and the super-accumulator plants is 40-60 cm.

[0014] Preferably, the yield model of crops with low heavy metal accumulation includes: an aboveground biomass model of crops with low heavy metal accumulation and / or a grain yield model of crops with low heavy metal accumulation.

[0015] Preferably, the aboveground biomass model of crops with low heavy metal accumulation is: aboveground biomass model of crops with low heavy metal arsenic accumulation; the grain yield model of crops with low heavy metal accumulation is: grain yield model of crops with low heavy metal cadmium accumulation;

[0016] The aboveground biomass model of the heavy metal arsenic low accumulation crop is:

[0017] Y = 0.072X1 + 16.224X2 - 15.994X3 + 0.893, where:

[0018] Y, aboveground biomass of low-accumulation crops, kg / m 2 ;

[0019] X1, number of hyperaccumulating plants, plants / m 2 ;

[0020] X2, Arsenic extraction from aboveground parts of low-accumulation crops, mg / m 2 ;

[0021] X3, Arsenic extraction from aboveground parts of hyperaccumulator plants, g / m 2 ;

[0022] The grain yield model of the crop with low accumulation of heavy metal cadmium is:

[0023] Y = -0.111X1-28.907X2-0.400X3+2.034, where:

[0024] Y, grain yield of low-accumulation crops, kg / m 2 ;

[0025] X1, number of hyperaccumulating plants, plants / m 2 ;

[0026] X2, cadmium extraction from aboveground parts of low-accumulation crops, mg / m 2 ;

[0027] X3, Cadmium extraction from aboveground parts of hyperaccumulator plants, g / m 2 .

[0028] Preferably, the heavy metal contaminated soil remediation efficiency model includes: a heavy metal arsenic contaminated soil remediation efficiency model and / or a heavy metal cadmium contaminated soil remediation efficiency model;

[0029] The heavy metal arsenic contaminated soil remediation efficiency model is:

[0030] R=1.89X1-35.088X2+48.639X3+7.378X4+4.017, where:

[0031] R, restoration period, 100 years;

[0032] X1, number of hyperaccumulating plants, plants / m 2 ;

[0033] X2, Arsenic extraction from the aboveground parts of hyperaccumulator plants, g / m 2 ;

[0034] X3, aboveground biomass of hyperaccumulators, kg / m 2 ;

[0035] X4, aboveground biomass of low-accumulation crops, kg / m 2 ;

[0036] The heavy metal cadmium contaminated soil remediation efficiency model is:

[0037] R=1.03X1-17.983X2+31.351X3+9.940X4-8.374, where:

[0038] R, restoration period, 100 years;

[0039] X1, number of hyperaccumulating plants, plants / m 2 ;

[0040] X2, cadmium extraction from the aboveground parts of hyperaccumulators, g / m 2 ;

[0041] X3, aboveground biomass of hyperaccumulators, kg / m 2 ;

[0042] X4, grain yield of low-accumulation crops, kg / m 2 .

[0043] The present invention also provides a heavy metal low accumulation crop yield model and a heavy metal contaminated soil remediation efficiency model constructed according to the above construction method.

[0044] The present invention focuses on heavy metal contaminated soil in drylands in the north and south, designs intercropping structure configurations of different types of low-accumulation crops and hyper-accumulator plants, determines key parameters such as temperature, precipitation, plant planting intensity, and row belt types, and establishes an ecological competition model in the intercropping technology system by studying the ecological competition relationship between low-accumulation crop varieties and hyper-accumulator plants, providing a theoretical basis for clarifying the competition relationship between intercropping plants and evaluating the restoration effect of the intercropping pattern. The establishment of the intercropping competition yield model and the restoration efficiency model between low-accumulation crops and hyper-accumulator plants is helpful for the demonstration and promotion of intercropping restoration technology, which not only has important scientific value for the restoration and utilization of heavy metal contaminated soil in drylands in the north and south, but also has important significance for the social, economic, and ecological benefits of the restoration areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 is the aboveground biomass of low-accumulation crops in the Shaoguan test site, kg / mu;

[0046] Figure 2 Arsenic extraction from the aboveground parts of low-accumulation crops in the Shaoguan test site, g / mu;

[0047] Figure 3 Arsenic extraction from the aboveground parts of hyperaccumulator plants in the Shaoguan test site, g / mu;

[0048] Figure 4 is the available arsenic content in the soil of the Shaoguan test site, mg / kg;

[0049] Figure 5 is the aboveground biomass of superaccumulators in the Shaoguan test site, kg / mu;

[0050] Figure 6 is the grain yield of low-accumulation crops in the Shenyang test site, kg / mu;

[0051] Figure 7 The cadmium extraction amount of the aboveground parts of low-accumulation crops in the Shenyang test site, mg / mu;

[0052] Figure 8is the cadmium extraction amount of the aboveground parts of the hyperaccumulator plants in the Shenyang test site, mg / mu;

[0053] Fig. 9 is the available cadmium content in the soil of the Shenyang test site, mg / kg;

[0054] Fig.10 is the aboveground biomass of superaccumulators in the Shenyang test site, kg / mu;

[0055] Fig.11 The aboveground biomass model validation results of low-accumulation crops in the Shaoguan test site;

[0056] Fig.12 The results of the remediation efficiency model for arsenic-contaminated soil in the Shaoguan test site were verified;

[0057] Fig.13 The results of the grain yield model validation of low-accumulation crops in the Shenyang test site;

[0058] Fig.14 This is the verification result of the cadmium-contaminated soil remediation efficiency model in the Shenyang test site. DETAILED DESCRIPTION

[0059] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0060] Example 1

[0061] 1. Intercropping patterns of hyperaccumulators and low-accumulator crops

[0062] 1. Select the sample plot

[0063] The sample plots were selected in Kuanchang Village, Liaozhong District, Shenyang City and Wengyuan County, Shaoguan City, Guangdong Province. Cadmium (Cd)-contaminated farmland was selected in Kuanchang Village, Liaozhong District, Shenyang City, and arsenic (As)-contaminated farmland was selected in Wengyuan County, Shaoguan City, Guangdong Province. A corn (Dongdan 118) / grain amaranth intercropping restoration system was set up in the Cd-contaminated farmland in Kuanchang Village, Liaozhong District, Shenyang City; a corn (Wancai Tiannuo 118) / centipede grass intercropping restoration system was set up in the As-contaminated farmland in Wengyuan County, Shaoguan City, Guangdong Province. Among them, corn is a low-accumulation crop, and grain amaranth and centipede grass are hyperaccumulators. Water and fertilizer management in each regional test site was carried out according to local traditional customs.

[0064] 2. Trial period: 2018, 2019.

[0065] 3. Arrange intercropping pattern

[0066] The planting structure patterns of each plot were divided into 7 categories: low-accumulation crop monoculture (CK1); super-accumulation plant monoculture (CK2); low-accumulation crop wide (intercropped with single-row super-accumulation plant) narrow row (T1); low-accumulation crop wide (intercropped with double-row super-accumulation plant) narrow row (T2); low-accumulation crop equal row spacing (intercropped with single-row super-accumulation plant) (T3); low-accumulation crop equal row spacing (intercropped with double-row super-accumulation plant) (T4); low-accumulation crop / super-accumulation plant equal row spacing (T5). Each planting pattern was repeated three times. The specific planting structure is shown in Table 1. A total of 21 planting plots were set up, and the area of ​​each plot was 50m 2 .

[0067] Table 1 Experimental design of intercropping pattern

[0068]

[0069] 4. Sample Collection and Processing

[0070] (1) Two complete low-accumulation crops (corn) were randomly collected from each plot of CK1 and T1-T5 at the seedling stage, jointing stage, tasseling stage and maturity stage of the low-accumulation crop (corn). The low-accumulation crop was divided into four parts: root, stem, leaf and grain (maturity stage). The root, stem and leaf were rinsed with tap water, then cleaned with distilled water and dried. They were put into envelope bags and placed in an oven at 105°C for 0.5 h. They were then dried at 70°C to constant weight. They were taken out and crushed with a 100-mesh crusher, mixed and bagged to obtain the aboveground biomass samples of the low-accumulation crops in the two test sites in Shaoguan and Shenyang. The grain samples were threshed manually, then naturally air-dried, and then washed, dried and crushed according to the above steps to obtain the grain samples of the low-accumulation crops in the two test sites in Shaoguan and Shenyang.

[0071] (2) During the maturity period of hyperaccumulators (centipede grass or grain amaranth), two complete hyperaccumulators were randomly collected from each plot at CK2 and T1-T5, and divided into aboveground and underground parts. The aboveground parts were then washed, dried, crushed, sieved, mixed, and bagged according to the same processing steps as the low-accumulation crop samples to obtain the aboveground biomass samples of hyperaccumulators in the two experimental sites of Shaoguan and Shenyang.

[0072] (3) Soil surface samples: The rhizosphere soil of low-accumulating crops was collected by the shaking-off method in each plot of CK1 and T1-T5 during the seedling, jointing, tasseling and maturity stages of low-accumulating crops; the rhizosphere soil of super-accumulating plants was collected by the shaking-off method in each plot of CK2 and T1-T5 during the maturity stage of super-accumulating plants; the non-rhizosphere soil of the plot was collected by the diagonal method in each plot during the sowing and maturity stages of low-accumulating crops, and the soil layer was 0-10 cm. All soil samples were mixed and bagged, brought back to the laboratory and air-dried naturally, then sieved (100 mesh), and finally put into envelopes. Arsenic-contaminated soil samples from the Shaoguan test site and cadmium-contaminated soil samples from the Shenyang test site were obtained and prepared for testing.

[0073] 2. Construction of a heavy metal contaminated soil remediation model

[0074] 1. Establishment of a model for intercropping corn and centipede grass to restore soil contaminated by heavy metal arsenic in Shaoguan

[0075] 1.1 Construction of the aboveground biomass model of low-accumulation crops intercropped with arsenic-contaminated maize and centipede grass in Shaoguan area

[0076] ① Calculate the aboveground biomass of low-accumulation crops: weigh the aboveground biomass samples of low-accumulation crops in the Shaoguan test site, calculate the aboveground biomass of low-accumulation crops per plant, and multiply it by the number of low-accumulation crops in the Shaoguan test site to obtain the aboveground biomass of low-accumulation crops. The result is as follows: Figure 1 shown.

[0077] ② According to Table 1, the number of super-accumulator plant centipede grass in the Shaoguan test field under each intercropping mode can be obtained.

[0078] ③ Calculate the arsenic extraction amount of the aboveground part of low-accumulation crops: Take the aboveground biomass samples of low-accumulation crops in the Shaoguan test site, determine the arsenic content in the samples, calculate the arsenic content of each plant in the aboveground part of the low-accumulation crops, and multiply it by the number of low-accumulation crops in the Shaoguan test site to obtain the arsenic extraction amount of the aboveground part of the low-accumulation crops. The results are as follows: Figure 2 shown.

[0079] ④ Calculate the arsenic extraction amount of the aboveground parts of hyperaccumulators: Take samples of the aboveground parts of hyperaccumulators from the Shaoguan test site, determine the arsenic content in the samples, calculate the arsenic content of the aboveground parts of the hyperaccumulators, and multiply it by the number of hyperaccumulators in the Shaoguan test site to obtain the arsenic extraction amount of the aboveground parts of the hyperaccumulators. The results are as follows: Figure 3 shown.

[0080] According to the above data, the number of hyperaccumulators, the arsenic extraction of the aboveground parts of low-accumulator crops, and the arsenic extraction of the aboveground parts of hyperaccumulators were used as independent variables, and the aboveground biomass of low-accumulator crops (as the yield of heavy metal low-accumulator crops) was used as the dependent variable for regression analysis. The regression equation is as follows:

[0081] Y = 0.072X1 + 16.224X2 - 15.994X3 + 0.893, where:

[0082] Y, aboveground biomass of low-accumulation crops, kg / m 2 ;

[0083] X1, number of hyperaccumulating plants, plants / m 2 ;

[0084] X2, Arsenic extraction from aboveground parts of low-accumulation crops, mg / m 2 ;

[0085] X3, Arsenic extraction from aboveground parts of hyperaccumulator plants, g / m 2 .

[0086] 1.2 Establishment of intercropping efficiency model for remediation of soil contaminated by heavy metal arsenic in Shaoguan

[0087] ① The available arsenic content in the arsenic-contaminated soil samples from the Shaoguan test site (from Section 4. Sample collection and processing) was measured. The results are as follows: Figure 4 As shown;

[0088] ② According to Table 1, the number of super-accumulator plant centipede grass in the Shaoguan test site under each intercropping mode can be obtained;

[0089] ③ The arsenic extraction amount of the aboveground parts of hyperaccumulator plants is directly calculated using the result of step ④ in 1.1 ( Figure 3 );

[0090] ④ Calculate the aboveground biomass of superaccumulators: weigh the aboveground biomass samples of superaccumulators in the Shaoguan test site, calculate the aboveground biomass of a single superaccumulator, and multiply it by the number of superaccumulators in the Shaoguan test site to obtain the aboveground biomass of the superaccumulators. The result is as follows: Figure 5 shown.

[0091] ⑤ The aboveground biomass of low-accumulation crops is directly calculated using the result of step ① in 1.1 ( Figure 1 ).

[0092] According to the above data, the number of hyperaccumulators, arsenic extraction from the aboveground parts of hyperaccumulators, aboveground biomass of hyperaccumulators, and aboveground biomass of low-accumulator crops were used as independent variables, and the restoration years were used as dependent variables for regression analysis. The regression equation is as follows:

[0093] R=1.89X1-35.088X2+48.639X3+7.378X4+4.017, where:

[0094] R, restoration period, 100 years;

[0095] X1, number of hyperaccumulating plants, plants / m 2 ;

[0096] X2, Arsenic extraction from the aboveground parts of hyperaccumulator plants, g / m 2 ;

[0097] X3, aboveground biomass of hyperaccumulators, kg / m 2 ;

[0098] X4, aboveground biomass of low-accumulation crops, kg / m 2 .

[0099] The restoration period R in the above restoration efficiency model refers to: based on the national standard of soil As secondary pollution of 30 mg / kg (GB 15618-2018), calculated according to the soil tillage layer of 20 cm, the restoration period required to reduce soil arsenic pollution to a level below the national standard with the current extraction efficiency (arsenic extraction amount of the aboveground parts of hyperaccumulator plants × aboveground biomass of hyperaccumulator plants, mg / year).

[0100] Method for determining total arsenic in soil: nitric acid-hydrochloric acid digestion, atomic fluorescence spectrometry (GB / T22105.2-2008).

[0101] As content in low-accumulation crops and hyperaccumulators: digested with nitric acid + perchloric acid and measured with an atomic fluorescence spectrophotometer.

[0102] 2. Constructing a model for intercropping corn / amaranth in soils contaminated by heavy metal cadmium in Shenyang

[0103] 2.1 Construction of a yield model for low-accumulation crops in intercropping of cadmium-contaminated maize and grain amaranth in Shenyang

[0104] ① Calculate the grain yield of low-accumulation crops: weigh the weight of the grain samples of low-accumulation crops in the Shenyang test site and determine the moisture content. Then calculate the theoretical single-plant grain yield of low-accumulation crops according to the 14% moisture content. Multiply it by the number of low-accumulation crops in the Shenyang test site to obtain the grain yield of low-accumulation crops. The result is as follows: Figure 6 shown.

[0105] ② According to Table 1, the number of plants of the hyperaccumulator Amaranthus can be obtained under each intercropping pattern.

[0106] ③ Calculate the cadmium extraction amount of the aboveground part of low-accumulation crops: Take the aboveground biomass samples of low-accumulation crops in the Shenyang test site, determine the cadmium content in the samples, calculate the cadmium content of each plant in the aboveground part of the low-accumulation crops, and multiply it by the number of low-accumulation crops in the Shenyang test site to obtain the cadmium extraction amount of the low-accumulation crops. The results are as follows: Figure 7 shown.

[0107] ④ Calculate the cadmium extraction amount of the aboveground parts of hyperaccumulators: Take samples of the aboveground parts of hyperaccumulators from the Shenyang test site, determine the cadmium content in the samples, calculate the cadmium content of each plant in the aboveground parts of the hyperaccumulators, and multiply it by the number of plants in the Shenyang test site to obtain the cadmium extraction amount of the aboveground parts of the hyperaccumulators. The results are as follows: Figure 8 shown.

[0108] According to the above data, the number of hyperaccumulators, the cadmium extraction of the aboveground parts of low-accumulator crops, and the cadmium extraction of the aboveground parts of hyperaccumulators were used as independent variables, and the grain yield of low-accumulator crops (as the yield of heavy metal low-accumulator crops) was used as the dependent variable for regression analysis. The regression equation is as follows:

[0109] Y = -0.111X1-28.907X2-0.400X3+2.034, where:

[0110] Y, grain yield of low-accumulation crops, kg / m 2 ;

[0111] X1, number of hyperaccumulating plants, plants / m 2 ;

[0112] X2, cadmium extraction from aboveground parts of low-accumulation crops, mg / m 2 ;

[0113] X3, Cadmium extraction from aboveground parts of hyperaccumulator plants, g / m 2 .

[0114] 2.2 Establishment of intercropping efficiency model for remediation of soil contaminated by heavy metal cadmium between corn and grain amaranth in Shenyang, Liaoning

[0115] ① The organic cadmium in the cadmium-contaminated soil samples from the Shenyang test site (from Section 4. Sample collection and processing) was determined. The results are as follows: Fig. 9 As shown;

[0116] ② According to Table 1, the number of super-accumulator Amaranthus oleraceus plants under each intercropping pattern can be obtained;

[0117] ③ The cadmium extraction amount of the aboveground parts of hyperaccumulator plants is directly calculated using the result of step ④ in 2.1 ( Figure 8 );

[0118] ④ Calculate the aboveground biomass of superaccumulators: weigh the aboveground biomass samples of superaccumulators in the Shenyang test site, calculate the aboveground biomass of a single superaccumulator, and multiply it by the number of superaccumulators in the Shenyang test site to obtain the aboveground biomass of the superaccumulators. The result is as follows: Fig.10 .

[0119] ⑤ The grain yield of low-accumulation crops is directly calculated using the result of step ① in 2.1 ( Figure 6 ).

[0120] According to the above data, the number of hyperaccumulators, cadmium extraction from the aboveground parts of hyperaccumulators, biomass of the aboveground parts of hyperaccumulators, and yield of low-accumulation crops were used as independent variables, and the restoration years were used as dependent variables for regression analysis. The regression equation is as follows:

[0121] R=1.03X1-17.983X2+31.351X3+9.940X4-8.374, where:

[0122] R, Restoration period, 100 years

[0123] X1, number of hyperaccumulating plants, plants / m 2 ;

[0124] X2, cadmium extraction from the aboveground parts of hyperaccumulators, g / m 2 ;

[0125] X3, aboveground biomass of hyperaccumulators, kg / m 2 ;

[0126] X4, grain yield of low-accumulation crops, kg / m 2 .

[0127] The restoration period R in the above restoration efficiency model refers to: based on the national standard of 0.3 mg / kg for secondary soil Cd pollution (GB 15618-2018), calculated according to the soil tillage layer of 20 cm, the restoration period required to reduce soil cadmium pollution to a level below the national standard at the current extraction efficiency (cadmium extraction amount of the aboveground part of hyperaccumulator plants × aboveground biomass of hyperaccumulator plants, mg / year).

[0128] The method for determining the total cadmium content in soil is as follows: hydrofluoric acid-nitric acid-perchloric acid digestion (GB / T17141-1997); the method for determining the available Cd content in soil is as follows: DTPA-TEA extraction method (GB / T23739-2009).

[0129] Cd content in low-accumulation crops and hyperaccumulators: Plant samples were digested with nitric acid-perchloric acid, and the Cd content in the digestate and extract was determined by ICP-OES.

[0130] The independent variables in the four models provided in this embodiment are based on the APISM model. According to the data collection of the sample plot layout, the main parameters of the meteorological parameter module, the soil attribute parameter module and the crop attribute parameter module are collected (Table 2). Through principal component analysis, partial regression and other methods, combined with the positioning experiment of the test plot, the module parameters are screened and corrected, and the crop parameter module is established. Some sensitive parameters are preliminarily screened, and regression analysis and Pearson correlation analysis are performed on the obtained sensitive parameters, thereby screening the independent variable parameters provided by the present invention, and further obtaining a heavy metal contaminated soil remediation model by intercropping hyperaccumulators and low-accumulation crops.

[0131] Table 2 Model parameter data list

[0132] Meteorological parameters Soil property parameters Crop attribute parameters Monthly temperature changes pH Low-accumulation crop varieties Monthly changes in precipitation Test weight Growth cycle (hyperaccumulators / low-accumulator crops) Sunshine hours Soil background nutrient (NPK) content Planting intensity (spacing, row spacing, number of plants) Effective accumulated temperature Fertilizer (NPK) amount Plant height, plant weight - Total Cd content in rhizosphere soil Grain yield per plant of low accumulation crops - Available Cd content in rhizosphere soil Grain yield per mu of low accumulation crops - Total Cd content in non-rhizosphere soil Per-acre yield of aboveground parts of hyperaccumulator plants - Available Cd content in non-rhizosphere soil 100-grain weight of low-accumulation crops - - Cd content in roots, stems, leaves and grains of low-accumulation crops - - Cd extraction per mu from aboveground parts of low-accumulation crops - - Cd content in aboveground and underground parts of hyperaccumulator plants - - Cd extraction per mu from the aboveground parts of hyperaccumulator plants

[0133] Example 2

[0134] The independent variable data of the number of hyperaccumulators, heavy metal extraction from the aboveground parts of low-accumulation crops, heavy metal extraction from the aboveground parts of hyperaccumulators, aboveground biomass of hyperaccumulators, grain yield of low-accumulation crops, and aboveground biomass of low-accumulation crops in the two test sites of Shaoguan and Shenyang in 2019 were counted. The yield of heavy metal low-accumulation crops and restoration years were used as dependent variables to verify the four fitting equations obtained in Example 1: The results are as follows: Figures 11 to 14 shown.

[0135] Fig.11 and Fig.13 The correlation between the simulated and measured values ​​of low-accumulation crop yield (aerial biomass and grain yield) in Shaoguan area ( Fig.11 )R 2 is 0.8021, Shenyang area ( Fig.13 )R 2 The ΔE and D values ​​are 0.7614 and 0.92 and 0.89 respectively, which indicates that the simulated and measured yield data of the two regions are in good agreement and can accurately simulate the yield changes of the intercropping pattern between the two regions.

[0136] Fig.12 and Fig.14 To repair the correlation between the simulated value and the measured value of efficiency, Shaoguan area ( Fig.12 )R 2 is 0.7669, Shenyang area ( Fig.14 )R 2 The ΔE and D values ​​were 0.8475 and 0.87, respectively, indicating that the simulated and measured restoration efficiency data of the two regions were highly consistent, and the restoration efficiency changes of the intercropping patterns between the two regions could be simulated more accurately.

[0137] There is no intercropping ecological competition model for low-accumulation crops and super-accumulation plants in heavy metal-contaminated farmland at present, to guide the practical application of intercropping to repair heavy metal-contaminated soil. The present invention is aimed at the characteristics of heavy metal pollution in soil in different regions, and the intercropping planting pattern of low-accumulation crops and super-accumulation plants is arranged. Through two consecutive years of fixed-point and regular monitoring, the monitoring data of relevant indicators such as meteorology, soil, and crops are obtained, and the influence of factors such as temperature, precipitation, water and fertilizer management, and time and space configuration on the competition effect of resource utilization such as light, heat, water, and fertilizer in the intercropping system is comprehensively analyzed, and the interaction relationship between each factor and the yield of low-accumulation crops and the accumulation of heavy metals is analyzed. Using the first year (2018) test data, the farmland production system APSIM model is adopted to construct a regression model with crop yield, heavy metal extraction, planting structure and planting intensity as driving variables, and low-accumulation crop yield and heavy metal repair efficiency as dependent variables. Using the multivariate regression analysis method, the plant parameter regression model is optimized with the goal of high crop yield, the lowest heavy metal content of agricultural products and the highest heavy metal absorption of super-enriched plants. Using the experimental data from the second year (2019), the ecological competition model of intercropping between low-accumulation crop varieties and hyperaccumulator plants was verified and improved to clarify the competitive relationship between intercropped plants, improve the restoration effect of the intercropping pattern, and provide technical support for the safe use of heavy metal contaminated farmland.

[0138] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for constructing a restoration model of heavy metal contaminated soil intercropping with hyperaccumulator plants and low-accumulator crops, characterized in that: The steps include: (1) Planting superaccumulators and low-accumulator crops in an intercropping pattern; (2) The number of hyperaccumulators, the amount of heavy metals extracted from the aboveground parts of low-accumulator crops, and the amount of heavy metals extracted from the aboveground parts of hyperaccumulators were collected as independent variables, and the yield of low-accumulator crops was used as the dependent variable for regression analysis to construct a yield model for low-accumulator crops; (3) Collect the number of hyperaccumulators, the amount of heavy metals extracted from the aboveground parts of hyperaccumulators, the aboveground biomass of hyperaccumulators, and the grain yield of low-accumulator crops as independent variables, or collect the number of hyperaccumulators, the amount of heavy metals extracted from the aboveground parts of hyperaccumulators, the aboveground biomass of hyperaccumulators, and the aboveground biomass of low-accumulator crops as independent variables, and use the restoration years as the dependent variable to conduct regression analysis and construct a heavy metal contaminated soil restoration efficiency model; (4) Use trial and error method to verify the heavy metal low accumulation crop yield model and heavy metal contaminated soil remediation efficiency model; The yield model of crops with low heavy metal accumulation is: an aboveground biomass model of crops with low heavy metal accumulation or a grain yield model of crops with low heavy metal accumulation; When the heavy metal is arsenic, the aboveground biomass model of crops with low accumulation of heavy metal arsenic is: Y=0.072X1+16.224X2-15.994X3+0.893, where: Y, aboveground biomass of low-accumulation crops, kg / m 2 ; X1, Number of super-rich plants, plants / m 2 ; X2, Arsenic extraction from aboveground parts of low-accumulation crops, mg / m 2 ; X3, Arsenic extraction from aboveground parts of hyperaccumulator plants, g / m 2 ; The remediation efficiency model of heavy metal arsenic contaminated soil is: R=1.89X1-35.088X2+48.639X3+7.378X4+4.017, where: R, restoration period, 100 years; X1, Number of super-rich plants, plants / m 2 ; X2, Arsenic extraction from the aboveground parts of hyperaccumulator plants, g / m 2 ; X3, aboveground biomass of hyperaccumulators, kg / m 2 ; X4, aboveground biomass of low-accumulation crops, kg / m 2 ; When the heavy metal is cadmium, the grain yield model of crops with low accumulation of heavy metal cadmium is: Y=-0.111X1-28.907X2-0.400X3+2.034, where: Y, grain yield of low-accumulation crops, kg / m 2 ; X1, Number of super-rich plants, plants / m 2 ; X2, cadmium extraction from aboveground parts of low-accumulation crops, mg / m 2 ; X3, Cadmium extraction from aboveground parts of hyperaccumulator plants, g / m 2 The remediation efficiency model of heavy metal cadmium contaminated soil is: R=1.03X1-17.983X2+31.351X3+9.940X4-8.374, where: R, restoration period, 100 years; X1, Number of super-rich plants, plants / m 2 ; X2, cadmium extraction from the aboveground parts of hyperaccumulators, g / m 2 ; X3, aboveground biomass of hyperaccumulators, kg / m 2 ; X4, grain yield of low-accumulation crops, kg / m 2 .

2. The construction method according to claim 1, characterized in that: The heavy metal also includes one of lead, zinc and copper.

3. The construction method according to claim 2, characterized in that: The hyperaccumulator plants include one or more of centipede grass, nightshade, grain amaranth, pennisetum, Indian mustard, Bidens pilosa, amaranth and Dipsacus asper.

4. The construction method according to claim 3, characterized in that: The low accumulation crops include one or more of corn, wheat, soybean, sorghum, millet and cotton.

5. The construction method according to claim 4, characterized in that: The intercropping pattern is: planting low-accumulating crops in wide and narrow rows, and intercropping wide rows with a single row of super-accumulating plants; or planting low-accumulating crops in wide and narrow rows, and intercropping wide rows with two rows of super-accumulating plants; or planting low-accumulating crops with equal row spacing, and intercropping a single row of super-accumulating plants; or planting low-accumulating crops with equal row spacing, and intercropping two rows of super-accumulating plants; or intercropping low-accumulating crops and super-accumulating plants with equal row spacing.

6. The construction method according to claim 5, characterized in that: In the wide-row and narrow-row planting of the low-accumulating crops, the row spacing width of the wide rows is 80-120 cm, and the row spacing width of the narrow rows is 30-50 cm; the row spacing width of the low-accumulating crops in the equal-width row planting is 80-120 cm; the row spacing width of the single-row super-accumulating plants is 40-60 cm, and the row spacing width of the double-row super-accumulating plants is 25-40 cm; the row spacing width of the equal-row intercropping of the low-accumulating crops and the super-accumulating plants is 40-60 cm.

7. A heavy metal low accumulation crop yield model and a heavy metal contaminated soil remediation efficiency model constructed by the construction method according to any one of claims 1 to 6.

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