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作 者 ：陈刚,刘爱平,周卫东,孙国荣,杜坤,张彪

期 刊 ：生态学报 2007年 27卷 12期 页码：5318~5324

关键词：水稻籽粒；Ca；X射线电子探针显微分析；富集；

Keywords:rice grain, calcium, X-ray electron probe microanalysis, accumulation,

摘 要 ：通过环境扫描电镜结合X射线电子探针显微分析技术，对21种不同基因型的水稻籽粒颖壳内、外表面以及颖果表面、糊粉层、近糊粉层和米中部的Ca含量进行测定。结果表明，Ca元素在水稻籽粒不同部位的含量有明显差异, 颖壳内外表面和颖果表面Ca含量较高，近糊粉层和颖果中部含量较低，在颖果中Ca主要富集在糊粉层中；而且不同基因型水稻籽粒同一部位或不同部位Ca的积累量也有较大差异，这可能是由遗传差异引起的。糊粉层中的Ca含量影响着颖壳外表面、颖果表面、近糊粉层和米中部的Ca含量。另外，籽粒不同部位Ca含量与P、Mg、K、Si、Al、Cd含量之间存在显著或极显著的非线性关系，与Pb含量之间不存在显著的非线性关系。说明Ca在水稻籽粒中富集的同时也影响着P、Mg、K、Si、Al、Cd等元素的富集。

Abstract:As one of the essential nutrient elements in plant, calcium, accounting for about 2 percent of body weight in rice plant, is the important component in cell wall formation, and participates in the most of metabolism process, such as growth, pollination and fertilization, regulation of enzyme activity, stress resistance, and the signal conduction. However, the precise distribution of calcium, and its relationship with some heavy metals in rice grain are largely unexplored. In the present study, the Ca levels of 21 rice genotypes in 6 different grain parts were determined by environmental scanning electron microscopy combining with X-ray electron probe microanalysis (the inner and outer surface of rice glume, surface of caryopsis, center of caryopsis, near aleuronic layer and aleuronic layer), and its relevancy with the contents of other metals in whole a rice grain, including P, Mg, K, Si, Cd, Al and Pb , were investigated. The results showed that there was remarkable difference in Ca levels among different portions of rice grain, with higher Ca levels in the inner and outer surface of rice glume, and the surface of caryopsis, while less Ca amounts in the near aleuronic layer and center of caryopsis, implying that Ca predominantly located in the aleuronic layer for a whole rice caryopsis. Moreover, the considerable differences in Ca level were also existed among the different rice genotypes, with a comparison of the same similar portion of different rice cultivars, suggesting that rice genotypes had a dominant effect on Ca accumulation. Ca content in aleuronic layer was closely related to those in outer surface of rice glume, surface and center of caryopsis and near aleuronic layer of rice grains. In addition, there were significant non-linear correlations between the content of Ca and that of P, Mg, K, Si, Al, Cd in different parts of rice grains, but no significant non-linear correlations existed between the content of Ca and Pb. That was, the Ca accumulation could facilitate the accumulation of P, Mg, K and Si. However, Ca might also enhance Al and Cd accumulation in rice grains, which have potential toxicity to human beings.

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