The concentrations of Zn and other mineral elements and in situ spatial distribution patterns were analyzed by combing ICPMS with synchrotron radiation Xray fluorescence (SRXRF). The results showed that SRXRF was a reliable technique to investigate the element microdistribution in rice grains. Significantly positive correlations between elemental distribution of Zn, Fe, Cu and Mn were observed in rice grains, while there was no such pronounced correlation for K and Ca. Among the minerals, potassium is of the highest concentration and mobility in rice grains, being up to 52.6-90.6% in polished rice of that in the hulls. Highest Ca concentration was observed in the hulls, while the other five elements were preferentially distributed in the outer layer, such as embryo and aleuronic layer. The contents of Zn and other mineral elements in the endosperm decreased rapidly from the outer layers to the central parts. Both XRF mapping and ICPMS analysis showed that Zn level in rice grains of Zninefficient genotype (Erjiufeng) was significantly higher than that in grains of Znefficient genotype (IR8192). This indicated that the Znefficient genotype IR8192 was not able to accumulate higher Zn in grains when exposed to sufficient Zn levels, despite of its high efficient uptake and utilization of Zn under Zn deficient conditions.
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