Nondestructive assessment of protein content in single seeds of rapeseed (Brassica napus L.) by near-infrared reflectance spectroscopy

The potential of near-infrared reflectance spectroscopy (NIRS) to detect within-plant differences for seed protein content was investigated. Four hundred and fifty-one single seeds were scanned by NIRS using a special adapter. After non-destructive NIRS scanning, the seeds were analysed for protein content by the Dumas combustion method and a calibration equation was developed. A validation set of 117 additional seeds from three individual plants from the cultivars Bristol, Lirajet and Maplus was analysed for protein content both by NIRS and combustion. The coefficient of determination between NIRS and combustion values in the validation set was 0.94, with a standard error of performance (SEP) of 0.77% and a ratio of the SEP to the standard deviation (SD) of the validation set of 0.28. The coefficient of variation (CV) for seed protein content in individual plants. as determined by the combustion method, was 11.7% for Bristol, 8.9% for Lirajet, and 9.5% for Maplus. The comparison of such variation with the standard error (SE) of NIRS analysis, defined as the combination of the SE of the combustion method and the SEP of NIRS calibration equation, revealed that the maximum explainable variance within individual plants that can be detected using NIRS analysis of protein content in single seeds was 0.86 for Bristol, 0.83 for Lirajet, and 0.85 for Maplus. These results demonstrated that NIRS is a powerful tool for non-destructive assessment of within-plant variation for seed protein content in rapeseed.