研究目的
To examine whether prediction equations using hyperspectral image data can lead to better predictive performance for grain yield than what can be achieved using vegetation indices (VIs), and to evaluate alternative estimation methods and the benefits of combining data from multiple time points.
研究成果
Hyperspectral image data provide higher prediction accuracy for maize grain yield compared to vegetation indices, with the Bayesian shrinkage and variable selection method (BayesB) performing best. Combining data from multiple time points further improves accuracy, highlighting the benefits of using whole-spectrum data and advanced statistical methods for high-throughput phenotyping.
研究不足
The study assumes uncorrelated errors within plots and does not account for spatial correlations or heterogeneous error variances. The regression coefficients may vary with traits and environmental conditions, requiring calibration for specific cases.
1:Experimental Design and Method Selection:
The study used linear regression models with inputs from hyperspectral data or VIs, employing ordinary least squares (OLS), partial least squares (PLS), and a Bayesian shrinkage and variable selection method (BayesB).
2:Sample Selection and Data Sources:
Data consisted of 467 maize hybrids from 11 yield trials conducted in 2014 under heat and drought stress at CIMMYT's experiment station in Mexico.
3:List of Experimental Equipment and Materials:
Hyperspectral camera (VNIR Headwall Photonics Micro-Hyperspec ARS3), aircraft (Piper PA-16 Clipper), GPS receiver (Trimble R4), integrating sphere (CSTM-USS-2000C Uniform Source System), sun photometer (Micro-Tops II).
4:Experimental Procedures and Operational Workflow:
Hyperspectral images were collected at five time points post-sowing, processed to exclude soil pixels, calibrated, and used to derive reflectance values and VIs. Regression models were fitted and evaluated using leave-one-trial-out cross-validation.
5:Data Analysis Methods:
Prediction accuracy was assessed using within-trial correlation coefficients, with bootstrap methods for standard errors and comparisons.
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