Prediction of Brown Rice Protein Content based on Leaf Nitrogen Concentration for Chinese Rice Varieties at the Ripening Stage

－Application of Portable Leaf Nitrogen Concentration Measuring Device－

Abstract

 A portable leaf nitrogen measuring device is a valuable tool used for accurate and efficient field measurements of leaf nitrogen concentration for Japanese rice varieties. However, the calibration curve, obtained for Japanese rice varieties, needs to be corrected before it can be effectively applied for Chinese rice varieties, at panicle formation stage. This report further confirmed that the instrument also provides accurate measurements for Chinese rice varieties, at the ripening stage. In addition, the measured leaf nitrogen concentrations during the ripening stage enabled the estimation of the protein content of brown rice at harvest time. There is a strong correlation between the protein content of brown rice and eating quality. Therefore, it is possible to estimate the eating quality of harvested rice based on the measured leaf nitrogen concentration during the ripening period. This makes it possible to differentiate the products by processing according to the level of eating quality at the drying facility.  Note, if the leaf nitrogen concentration is not measured at the appropriate time, the correlation with the brown rice protein content will not be obtained.