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Table 4 Statistics of the calibration and validation results for estimating leaf nitrogen concentration (LNC, g kg -1 ) and SPAD with color index b * , SPAD and days after transplanting (DAT)

From: Estimating rice chlorophyll content and leaf nitrogen concentration with a digital still color camera under natural light

Models α β γ RMSEa R2 NMBb
Calibration       
Model 1 LNC = αSPAD + βDAT + γ 1.02 ± 0.07 -0.31 ± 0.01 7.01 ± 2.95 3.07 g kg-1 0.78  
Model 2 LNC = αb* + βDAT + γ -0.67 ± 0.06 -0.29 ± 0.01 69.27 ± 2.10 3.36 g kg-1 0.71  
Model 3 SPAD = αb* + βDAT + γ -0.60 ± 0.04 0.024 ± 0.007 59.66 ± 1.14 1.62 0.55  
Model 4 SPAD = αb* + γ -0.60 ± 0.04   60.70 ± 1.12 1.62 0.53  
Validation       
Model 1     2.43 g kg-1 0.75 1.19%
Model 2     2.59 g kg-1 0.62 -1.32%
Model 3     2.01 0.46 -1.94%
Model 4     1.89 0.47 -2.00%
  1. The dataset in 2011 was used for model calibration and the dataset in 2010 used for model validation.
  2. aRoot mean square error.
  3. bNormalized mean bias.