研究目的
Investigating the potential of UAV-based hyperspectral pushbroom scanner data for estimating leaf area index (LAI) and chlorophyll (CHL) in winter wheat, and indirectly deriving grain yield to assess the effects of different nitrogen fertilization levels.
研究成果
The UAV-based hyperspectral pushbroom system provided high-quality data for reliable estimation of LAI and CHL using PLSR, which enabled accurate grain yield prediction via MLR. Results showed that beyond a certain nitrogen level, additional fertilization does not significantly increase yield, supporting precision farming for efficient nitrogen use. Future work should test on larger scales and homogeneous conditions.
研究不足
The study was conducted on a small-scale field trial, which may not represent larger or more heterogeneous agricultural areas. The hyperspectral data had noise beyond 900 nm, limiting spectral range. Sample size was small (48 for LAI/CHL, 24 for yield), and variability in treatments could affect generalizability. The method requires field spectra for radiometric correction, adding to operational complexity.
1:Experimental Design and Method Selection:
A controlled field experiment with eight nitrogen treatments on winter wheat was conducted. Hyperspectral imagery was acquired using a UAV-mounted pushbroom camera. Partial least-squares regression (PLSR) was used to estimate LAI and CHL from spectral data, and multiple linear regression (MLR) was used for yield prediction.
2:Sample Selection and Data Sources:
48 samples (LAI, CHL, reflectance spectra) were collected from plots with different nitrogen treatments. Grain yield data were obtained from harvesting.
3:List of Experimental Equipment and Materials:
UAV (DJI S1000+), hyperspectral camera (Resonon Pika-L), IMU (Ellipse-N from SBG Systems), gimbal, chlorophyll meter (SPAD-502 Plus from Konica Minolta), plant canopy analyzer (LAI-2200C from Li-Cor), field spectrometer (SVC HR-1024i), reference panels, and software (R statistical environment).
4:Experimental Procedures and Operational Workflow:
Hyperspectral data were acquired at 100 m flight height, preprocessed (orthorectification, radiometric correction, noise reduction), spectra were extracted from image, PLSR models calibrated and validated for LAI and CHL, MLR model calibrated for yield, and spatial predictions made.
5:Data Analysis Methods:
Statistical analysis included R2, RMSE, t-tests for residuals, and leave-one-out cross-validation for model validation.
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