Analysis of protein, starch and oil content of single intact kernels by near infrared reflectance spectroscopy (NIRS) in maize (Zea mays L.)

Maize samples (n = 309) containing 3090 single intact kernels from a broad variety of breeding materials were scanned by Near Infrared Reflectance Spectroscopy (NIRS) to develop non-destructive determination calibrations for crude protein, starch and oil content in kernels. Calibration equations of single kernels were developed by partial least square regression (PLS). Regression parameters between the chemical values, determined by reference methods, and the predicted values, determined by Near Infrared Reflectance Spectroscopy, were verified by cross validation and external validation. It was found that embryo position had a significant influence on the effect of calibrations. Reliable calibrations were developed for the prediction of protein and starch contents with the embryo upwards, whereas the oil content required the embryo to be downwards. The cross validation and external validation coefficients for protein were 0.91 and 0.94, for starch 0.90 and 0.89 and for oil 0.94 and 0.95, respectively. The data suggested that NIRS could be successfully used in breeding programmes, as an accurate and non-destructive tool to predict protein, starch and oil contents at the level of single kernels.