Method and system for in-situ detection of cadmium chelates in plants

A system for the in-situ detection of cadmium chelates in a plant, comprising:

• a first preparation module configured to prepare cadmium chloride samples with different concentrations and PC 2 samples with different concentrations;
• a THz reflection image determination module configured to use THz-TDS to determine a THz reflection image for the cadmium chloride samples and the PC 2 samples;
• a cadmium chloride content detection model building module configured to build a cadmium chloride content detection model according to first spectral data of the THz reflection images of the cadmium chloride samples;
• a PC 2 content detection model building module configured to build a PC 2 content detection model according to second spectral data of the THz reflection images of the PC 2 samples;
• an optimal mixed sample determination module configured to determine an optimal mixed sample according to the cadmium chloride content detection model and the PC 2 content detection model, wherein, the optimal mixed sample is a mixed sample of a cadmium chloride sample and a PC 2 sample and has the lowest cadmium chloride and PC 2 contents;
• a Cd—PC2 content detection model building module configured to build a Cd—PC2 content detection model according to the optimal mixed sample;
• and
• a cadmium chelate content determination module configured to use the Cd—PC2 content detection model to determine a cadmium chelate content in a to-be-tested plant;
• wherein
• the using the Cd—PC2 content detection model to determine a cadmium chelate content in a to-be-tested plant specifically comprises:
• uniformly dissolving every 100 mg of CdCl2 in every 5 L of soil to form a Cd2+ stress rhizosphere environment at 20 mg/L, and sowing and cultivating three different varieties of Brassica chinensis (You Donger, Shanghai Green, and Suzhou Green) in the soil;
• after the plants grow for 40 days, harvesting leaves, drying the leaves in an air dry oven at 35° C. for 12 h and then fixing on a sample carrier for scanning to obtain THz spectra;
• using the average spectral data of Brassica chinensis leaves of the same variety growing under the same growth conditions without Cd2+ stress as the background spectrum;
• subtracting the average spectrum from the spectrum of each pixel of a sample image to obtain independent variable data according to the characteristic frequencies of the Cd(PC2)2 chelate, and substituting results into the Cd—PC2 content detection model to calculate the dilution factor x of the chelate in each pixel and an average value of all pixels;
• calculating a Cd(PC2)2 content in the leaves according to the formula
• C
• =
• X
• ×
• P
• 1
• ⁢
• 5
• ×
• 1
• ⁢
• 5
• ×
• t
• ;
• importing a data matrix composed of the chelate dilution factor x and a pixel coordinate in each pixel into the software Origin 2018, and reconstructing a distribution image by contour mapping, wherein C is a Cd(PC2)2 content in scanned leaves;
• X is a dilution factor of the Cd(PC2)2 chelate in each pixel of scanned leaves;
• P is the total pixels of a scanned area, and t is a constant, namely, the content of a chelate in its 1× standard sample solution.