Fig. 2.

PLS regression model for total protein content in single wheat kernels (n = 3150 for calibration set and n = 1000 for validation set), by using the NIR spectral region ∼1060–2500 nm (pre-treatments used: SNV and first derivative calculated using Savitzky-Golay smoothing). Black: calibration dataset; yellow: external validation dataset (prediction); red: average batch values. For the colour identification please refer to the online colour version. R_c² = 0.916; R_cv² = 0.856; RMSEC = 0.876%; RMSECV = 0.507% for the batch; the other calibration performances are reported in Table 2.