TROPICAL GEOGRAPHY ›› 2016, Vol. 36 ›› Issue (4): 710-716.doi: 10.13284/j.cnki.rddl.002764

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Estimation Model for Litchi Leaf SPAD-Reading Based on Hyper-Spectral Data

LI Dan1,PENG Zhiping2,HAN Liusheng1,HUANG Jichuan2,LIU Wei1,HUANG Siyu1,CHEN Shuisen1   

  1. (1.Guangzhou Institute of Geography,Guangzhou 510070,China;2.Institute of Agricultural Resources and Environment,Guangdong Academy of Agricultural Sciences,Guangzhou 510640,China)
  • Received:2015-03-25 Online:2016-07-05 Published:2016-07-05


The aim of this study was to analyze the relationship between spectral characteristics of litchi leaf spectra and SPAD reading and to explore the capacity of hyper-spectral data in litchi leaf SPAD value estimation.The relationship between four types of spectral variables and the SPAD values were investigated. The first type was the spectral indices proposed in literature for estimating chlorophyll content. The second was the optimized spectral indices derived by band iteration. The third was the area, location and the slope derived by the red-edge, blue-edge and yellow-edge of the first derivative spectra. The last was the spectral feature variables constructed by the peaks and valleys of the second derivative spectra. The results showed that the slope of blue-edge and the sum of the second derivative spectra in 490-520 nm presented high correlation with SPAD values (the correlation coefficients were -0.834 and -0.856, respectively). For the standard normal variate spectra (SNV), the first derivative spectra (FD) and the second derivative spectra (SD), the four band double difference indices presented the best relationship with SPAD values. The correlation coefficient between (FD516-FD474)-(FD684-FD660) and SPAD values was the highest, which was 0.875. The determination coefficient and RMSE of the prediction model developed by this variable and SPAD values were 0.747 and 2.375, respectively. The result indicated that taking advantage of hyper-spectral data for monitoring of litchi SPAD values would be effective.

Key words: SPAD value, leaf spectra, spectral variable, litchi