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| Monitoring model of SPAD value of winter wheat canopy based on ″three-edge″ parameters |
| LIN Shaozhe1,2, PENG Zhigong2*, WANG Chuntang1,ZHANG Baozhong2, WEI Zheng2, ZHANG Qian1, HAN Nana2, LIU Lu2 |
| 1. College of Water Conservancy and Civil Engineering, Shandong Agricultural University, Tai′an, Shandong 271018, China; 2. State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, China Institute of Water Resources and Hydropower Research, Beijing 100038, China |
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Abstract In order to provide theoretical basis and technical support for hyperspectral diagnosis of the SPAD value of winter wheat canopy, the hyperspectral estimation model between ″three-edge″ parameters and SPAD value was established. Based on the correlation between canopy reflectance and canopy SPAD value of winter wheat, the linear regression model and principal component regression model of canopy SPAD value of winter wheat based on ″three-edge″ parameters were constructed. The results showed that the correlation coefficients of red valley location,(SDr-SDb)/(SDr+SDb), red valley amplitude,(SDr-SDy)/(SDr+SDy)were the highest at jointing stage, heading stage, filling stage and whole growth period, respectively, and all had statistical significance(P<0.01);compared with the same linear regression model, the spectral model constructed by principal component method increased the determinant coefficients R2 by 49.6%, 54.3%, 14.3%, 8.6% at jointing stage, heading stage, filling stage and whole growth stage, and the root mean square error RMSE and relative error RE decreased by 9.0%, 12.4%, 13.5% and 13.6%, respectively. Therefore, the principal component regression model based on comprehensive spectral information has a high estimation accuracy for the SPAD value of winter wheat canopy in each growth period and the whole growth period, which can provide a basis for monitoring and diagnosing the SPAD value of winter wheat.
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Received: 22 May 2019
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