Near Infrared Spectroscopy to Measure Maize Grain Composition on Plot Combine Harvesters: Evaluation of Calibration Techniques,Mathematical Transformations and Scatter Corrections

Near infrared spectroscopy on combine harvesters (NOCH) and choppers (NOC) is used successfully in maize breeding programmes for both grain and forage in central Europe. However, it requires the development of accurate and reliable calibration models. The objectives of our study were to assess the effects of (i) calibration techniques, (ii) mathematical transformations and (iii) scatter corrections on the development of calibration models based on NOCH spectra for determination of dry matter, crude protein and starch content of maize grain. Plot combine harvesters equipped with diode-array spectrometers were used. The calibration technique was the most important factor affecting prediction ability. The importance of spectral data pre-treatment depended on the particular constituent considered. It provided no benefits for dry matter and had variable effects on crude protein and starch.