Laser & Optoelectronics Progress, Volume. 59, Issue 23, 2300005(2022)

Research Progress on the Application of Terahertz Time Domain Spectroscopy in Agriculture

Hongtao Zhang, Yongsheng Cai*, Yu Wang, Yueyao Guo, and Hongrui Li
Author Affiliations
  • Institute of Electric Power, North China University of Water Resources and Electric Power, Zhengzhou 450045, Henan , China
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    Figures & Tables(5)
    Schematic of THz-TDS system in transmission model
    • Table 1. Data statistics of plant physiological detection

      View table

      Table 1. Data statistics of plant physiological detection

      Physical signsTarget objectFrequency /THzMethodResultReference
      Water contentSoybean leaf0.2-1.6

      PCA

      MLR

      BPNN

      LS-SVM

      RMSEP is 0.046531
      Scindapsus leaf0.5-1.4MLR

      RP=0.9891

      RMSEP is 0.0244

      32
      Soybean leaf0.6-1.8

      PLS

      MLR

      RP=0.9153

      RMSEP is 0.0526

      33
      ChlorophyllPine needles of pinus massoniana1.0-4.0DFT

      Characteristic absorption peak location

      1.05,1.6,2.25,2.8,3.5 THz

      35
    • Table 2. Data statistics of soil testing

      View table

      Table 2. Data statistics of soil testing

      Target objectFrequency /THzMethodLimit of detectionResultReference
      Trichlorfon0.9-2.1PLSR10%

      R>0.99304

      RMSEC<0.0219

      RMSEP<0.0246

      36
      Glyphosate0.2-1.5FFT0.18%Characteristic absorption peak location is 0.79,0.89,1.19,1.31,1.43 THz37

      Chlortetracycline

      hydrochloride and tetracycline hydrochloride

      0.5-1.0

      PCA

      PLSR

      1%

      R>0.9089

      RMSECV<0.1689

      RMSEC<0.0623

      RMSEP<0.1280

      38
      Heavy metal lead0.1-2.0

      PLS

      iPLS

      GA-PLS

      30 mg/kgRp=0.81,RMSEP is 39.52 mg/kg40
      Heavy metal lead0.075-2.0

      PLS

      SVM

      BPNN

      50 mg/kg

      PH is 8.5, Rp=0.9946,RMSEP is 22.70 mg∙kg-1

      PH is 7.0, Rp=0.9757,RMSEP is 33.04 mg∙kg-1

      PH is 5.5, Rp=0.9744,RMSEP is 55.03 mg∙kg-1

      41
    • Table 3. Data statistics of quality detection of agricultural products

      View table

      Table 3. Data statistics of quality detection of agricultural products

      ApplicationTarget objectFrequency /THzMethodResultReference
      Qualitative analysisGerminated wheat grains0.2-2.5

      PLSR

      LS-SVM

      BPNN

      Accuracy is 93.57%55
      Moldy wheat0.2-1.6

      SVM

      PLSR

      BPNN

      Accuracy is 100%(none),

      86.67%(slight), 84%(moderate),and 100%(serious)

      56
      Worm-eaten wheat0.2-3.0

      Otsu

      GA-Otsu

      Improved GA-Otsu

      Error is 4.17%57
      Quantitative analysisWater content of apple and mango0.75-1.1

      SVM

      KNN

      D-Tree

      Apple:Day1,Day2,Day3,Day4, accuracy is 100%

      Mango:Day1,Day4, accuracy is 100%,Day2 accuracy is 98.8%,Day3 accuracy is 93.3%

      60

      Purple rice,

      dyed rice,

      dyed black rice

      0.5-2.5

      PLS-DA

      PLS

      LS-SVM

      Purple rice mixed with dyed rice Rp=0.979,RMSEP is 0.091;purple rice mixed with

      dyed black rice Rp=0.948, RMSEP is 0.093

      61
      Plumpness for sunflower0.5-2.0Otsu

      RMSEP is 4%

      Rp=0.91

      64
      Shell contaminations from walnut kernels0.3-0.8PCALimit of detection 4%66
    • Table 4. Data statistics of breeding quality control

      View table

      Table 4. Data statistics of breeding quality control

      Target objectFrequency /THzMethodResultReference
      Transgenic cotton seed0-1.5GA-SVMAccuracy is 96.67%69
      Wheat varieties0.2-2.0

      PLS

      iPLS

      R=0.992

      RMSECV is 0.967

      71
      Soybean varieties0.05-2.0

      DT

      BPNN

      SVM

      Accuracy is 89.29%72

      Hybrid purity verification of

      rice seeds

      0.3-1.4

      ELM

      PLSR

      ELoo=2.005×10-5

      R2=96.75%

      73
      Transgenic rice seeds0-5

      PCA

      BPNN

      RF

      Accuracy is 96.67%75
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    Hongtao Zhang, Yongsheng Cai, Yu Wang, Yueyao Guo, Hongrui Li. Research Progress on the Application of Terahertz Time Domain Spectroscopy in Agriculture[J]. Laser & Optoelectronics Progress, 2022, 59(23): 2300005

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    Paper Information

    Category: Reviews

    Received: Oct. 12, 2021

    Accepted: Nov. 8, 2021

    Published Online: Oct. 31, 2022

    The Author Email: Yongsheng Cai (1252230766@qq.com)

    DOI:10.3788/LOP202259.2300005

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