Enrichment of Al in Rice Grains of Different Genotypes

By environmental scanning electron microscopy and X-ray electron probe microanalysis, Al content was studied in the grains of 21 genotypes of rice. The Al content differed as follows: inner surface of glume > aleurone layer > outer surface of glume > surface of caryopsis > sub-aleurone layer > centre of caryopsis. There were genetic differences in Al enrichment among the 21 genotypes, with differences in distribution of Al within the grain and hence differences among genotypes in the Al content of each part of the grain. There were significant non-linear correlations as follows: Al content in the centre with that in the surface and the sub-aleurone layer; Al content in the aleurone layer with that in the centre and sub-aleurone layer; and Al content in the inner surface of the glume with that in the aleurone layer. The results indicated that the Al enrichment in the centre of the caryopsis is regulated by the glume and the aleurone layer.