Easy and Rapid Detection of Iron in Rice Grain

ABSTRACT: In this study, we show how a preliminary determination of grain Fe in rice may be made with reaction to Perls ’ Prussian blue, a stain for Fe (III). Differential localization of Fe in grain parts was indicated by the intensity of reaction of tissue Fe to the dye. The blue colour reaction was most intense in the embryo, weak in the aleurone layer of the pericarp and invisible in the endosperm. The staining intensity also varied with the region of the embryo, generally being strongest in the scutellum, intermediate in the coleorhiza and weakest in the coleoptile. Variation in the reaction to Perls ’ Prussian blue was observed among eleven rice genotypes with varying grain Fe contents. The intensity of the blue colour reaction in the embryo of different rice genotypes was indicative of their grain Fe contents for both brown and white (polished) rice. Those with high grain Fe,>14 mg Fe kg-1, were clearly distinguishable from those with <10 mg Fe kg-1 with Perls’ Prussian blue. We suggest that this simple staining procedure may be used to quickly screen for high Fe contents in large germplasms containing hundreds of rice entries, using reactions in genotypes with known grain contents as standards