Heavy Metal Enrichment In Different Genotypes Of Rice And Wheat Grain

Heavy-metals means the metal elements with the density above the 5.0 (g/cm3), they are the main inorganic pollutants, having a risk of terrestrial ecosystems access to water, soil and atmosphere through the use of sludge, metal smelting residues, chemical waste, pesticides and chemical fertilizers, and application of solid waste incineration, automobile exhaust and other pollution sources. Which even more serious is heavy-metal contamination of soil, the mobility of heavy-metals in soil is relatively small, mainly accumulated in the 0~20cm layer of soil in farming, few moved to the 40 cm below, and only a very small part to the ground has been removed as part of crop harvest, so as soon as soil or plants subjected to heavy-metal contamination, it will continue to accumulate, it is not easy to restore governance. The nature of heavy-metals is the stability and not easy metabolism in the environment. They make easily modified organisms and biological enrichment amplification because plant roots, stems, leaves and grain accumulated large quantities of heavy metals, not only affecting plant growth and development seriously, and will enter the food chain, have crisis against human healthy.Through environmental scanning electron microscopy combined with X-ray electron probe microanalysis techniques, 10 kinds of metal content (Al, Cd, Cr, Pb, Mg, P, S, K , Ca, Si) were determined respectively in 6 sites of 23 kinds of different genotypes rice grain including inside and outside surface of the glume, caryopsis surface, aleurone layer, sub-aleurone layer, center of endosperm and in 7 sites of 20 kinds of different genotypes of wheat grain including cortex, aleurone layer, scutellum, plumule, hypocotyl, radicle and center of endosperm. The results show that:①the content of heavy-metal elements in the rice grain and wheat grain of different parts are significant differences, which content are the highest in aleurone layer, relatively small in center of endosperm. The reseach reflect heavy-metals elements of Al and Cd, Cr, Pb mainly enriched in aleurone layer (as measured by the experimental samples content of Cr were very low, so not the main analysis in this article).②Enrichment capacity of heavy-metals exist genetic diversity between the different genotypes of rice-wheat grain, this difference reflected in the relative content of different elements between the same location and different parts of the rice-wheat grains.③Al and Cd, Pb relative content among in different parts of different genotypes rice-wheat grain exist the highly significant linear relationship, on the one hand, it reflects the cumulant of Al, Cd, Pb among in different parts of different genotypes rice-wheat grain are the mutual regulation, in other words, there is the same regulation and control mechanisms; on the other hand, it reveals that enrichment capacity of Al, Cd, Pb among in different parts of different genotypes rice-wheat grain are different, and this genotype difference exist the linear law.In addition, the study found that there is relatively significant linear relationship between the content of Al, Cd, Pb among in different parts of different genotypes rice-wheat grain and mineral elements Mg, P, S, K, Ca, Si. Through researching the distribution of Al, Cd, Pb in rice-wheat in grain, and the differences in various aspects such as mechanism of impact with other elements, it is the description of the absorption of nutrients has the synergistic or antagonistic role on the accumulation of heavy metal ions. This paper provide the theoretical foundation for the development of low-Al, Cd, Pb accumulation, high-nutrition rice and wheat, and provide a new direction for safety breeding.