Abstract

Laser-induced fluorescence technology provides a nondestructive and rapid method for monitoring leaf nitrogen concentration (LNC) based on its optical characteristics. Crop growth status can be efficiently diagnosed and quality evaluated by monitoring LNC. In this study, the first-derivative fluorescence spectrum (FDFS) was proposed and calculated based on the fluorescence spectra excited by 355, 460, and 556 nm excitation lights for rice LNC estimation. Then, the performance of each band FDFS characteristics and the FDFS ratio for LNC estimation were comprehensively discussed using principal component analysis and backpropagation neural network (BPNN). We analyzed the number of FDFS characteristics’ influence on the accuracy of LNC monitoring. Results showed that $R^2$ does not clearly improve for the LNC monitoring based on the BPNN model when the number of extracted FDFS features exceeds 4 or 5. Therefore, the FDFS optimal band combination of different excitation light wavelengths mentioned was selected for LNC monitoring. The selected band combinations contained the majority of FDFS characteristics and could effectively be applied in monitoring LNC (for 355, 460, and 556 nm excitation lights, with $R^2$ of 0.764, 0.625, and 0.738, respectively) based on the BPNN model.

© 2019 Optical Society of America

Analyzing the performance of the first-derivative fluorescence spectrum for estimating leaf nitrogen concentration

Jian Yang, Lin Du, Wei Gong, Shuo Shi, Jia Sun, and Biwu Chen
Opt. Express 27(4) 3978-3990 (2019)

Effect of fluorescence characteristics and different algorithms on the estimation of leaf nitrogen content based on laser-induced fluorescence lidar in paddy rice

Jian Yang, Jia Sun, Lin Du, Biwu Chen, Zhenbing Zhang, Shuo Shi, and Wei Gong
Opt. Express 25(4) 3743-3755 (2017)

Assessing different regression algorithms for paddy rice leaf nitrogen concentration estimations from the first-derivative fluorescence spectrum

Jian Yang, Lin Du, Yinjia Cheng, Shuo Shi, Chengzhi Xiang, Jia Sun, and Biwu Chen
Opt. Express 28(13) 18728-18741 (2020)

Estimating the leaf nitrogen content of paddy rice by using the combined reflectance and laser-induced fluorescence spectra

Jian Yang, Lin Du, Jia Sun, Zhenbing Zhang, Biwu Chen, Shuo Shi, Wei Gong, and Shalei Song
Opt. Express 24(17) 19354-19365 (2016)

Potential of spectral ratio indices derived from hyperspectral LiDAR and laser-induced chlorophyll fluorescence spectra on estimating rice leaf nitrogen contents

Lin Du, Shuo Shi, Jian Yang, Wei Wang, Jia Sun, Biwu Cheng, Zhenbing Zhang, and Wei Gong
Opt. Express 25(6) 6539-6549 (2017)