Title
Novel Combined Spectral Indices Derived from Hyperspectral and Laser-Induced Fluorescence LiDAR Spectra for Leaf Nitrogen Contents Estimation of Rice.
Abstract
Spectra of reflectance (S-r) and fluorescence (S-f) are significant for crop monitoring and ecological environment research, and can be used to indicate the leaf nitrogen content (LNC) of crops indirectly. The aim of this work is to use the S-r-S-f features obtained with hyperspectral and laser-induced fluorescence LiDAR (HSL, LIFL) systems to construct novel combined spectral indices (NCIH-F) for multi-year rice LNC estimation. The NCIH-F is in a form of FWs*Phi + GSIs*Phi, where Phi is the S-r-S-f features, and FWs and GSIs are the feature weights and global sensitive indices for each characteristic band. In this study, the characteristic bands were chosen in different ways. Firstly, the S-r-S-f characteristics which can be the intensity or derivative variables of spectra in 685 and 740 nm, have been assigned as the Phi value in NCIH-F formula. Simultaneously, the photochemical reflectance index (PRI) formed with 531 and 570 nm was modified based on a variant spectral index, called PRIfraction, with the S-f intensity in 740 nm, and then compared its potential with NCIH-F on LNC estimation. During the above analysis, both NCIH-F and PRIfraction values were utilized to model rice LNC based on the artificial neural networks (ANNs) method. Subsequently, four prior bands were selected, respectively, with high FW and GSI values as the ANNs inputs for rice LNC estimation. Results show that FW- and GSI-based NCIH-F are closely related to rice LNC, and the performance of previous spectral indices used for LNC estimation can be greatly improved by multiplying their FWs and GSIs. Thus, it can be included that the FW- and GSI-based NCIH-F constitutes an efficient and reliable constructed form combining HSL (S-r) and LIFL (S-f) data together for rice LNC estimation.
Year
DOI
Venue
2020
10.3390/rs12010185
REMOTE SENSING
Keywords
DocType
Volume
hyperspectral LiDAR,laser-induced fluorescence LiDAR,combined spectral index,leaf nitrogen content
Journal
12
Issue
Citations 
PageRank 
1
0
0.34
References 
Authors
0
8
Name
Order
Citations
PageRank
Lin Du1247.43
Jian Yang200.34
Bowen Chen300.68
Jia Sun452.49
Biwu Chen501.01
Shuo Shi6156.21
Shalei Song7176.75
Wei Gong810432.67