Aluminum, Lead And Cadmium In Different Parts Of The Oat Grain Enrichment

Cadmium (Cd) and lead (Pb) are among those heavy metals of most concern. Cd is easy to be absorbed by plants and then enriched in human bodies through the food chains. Pb is the metal element which has attained the largest polluting area, because of its diverse use. Aluminium (Al) is the metal element of the highest content in the earth crust, and it was once generally utilized in armament, industry, medicine and everyday life. However, since 1970s, people have gradually come to acknowledge that it is of great toxicity to human body.Oats (Avena sativa L.) are a kind of herbaceous plants belonging to A. vena L. Of Aveneae Dumort in Gramineae. Compared with other grains, oats are fairly unique because of their being one of the best full-value nutriment food of the grains, and also because of the generally accepted medicinal properties as well as the health-care effects.Currently there have been plenty of researches on the effects of Al, Pb, and Cd on the major food crops like rice and wheat, but only few reports on their enrichment in different parts of oat grains, their reciprocal relations with one another and with other elements have come forth. Using environmental scanning telescope together with X-ray electron probe analysis, 22 sorts of oat grains possessing different genetic types which were produced out of the same fields were measured, their relative contents of Al, Pb, Cd in each parts respectively determined, and the distributing rule in grains and the correlation between them and other elements, i.e. Ca, K, Mg, P, S and Si were discussed. The main results are as follows:1. Al, Pb, and Cd spread over every parts of oat grains, and the relative contents in the same or different parts from grains of variant genetic types vary largely, probably owing to hereditary differences.2. In different parts of the oat grains (the cortex, the aleurone layer, the sub-aleurone layer and the central albumen ), the relative contents of Al, Pb, Cd turned out distinct values. All of these elements' contents were the highest in the aleurone layer, in the central albumen there were relatively less Al and Cd, and in the cortex Pb showed the least concentration. The aleurone layer might show impact on the Al content in the central albumen through controlling that value in the sub-aleurone layer. Oat sub-aleurone layer plays a key role in the Pb, Cd transport inside the grain, suggesting that sub-aleuronxe layer in oat grain may take partial place of the aleurone layer in rice.3. The Al content and the Cd content in various parts of oat grain seemingly showed no obvious correlative dependency. In the central albumen, on the other side, Al and Pb accumulation were related to each other remarkably. Cd content and Pb content showed significantly non-linear relationship that might be explained by the mutual promoting of these two elements.4. Al content in oat grain was well correlated with the content of Ma, P, S, and Si. The contents of Cd and Pb were both correlated with those of K, Ca, Mg, P, S, and Si of oat grain, showing notable influence of the accumulation of Cd and Pb on the absorption of mineral elements into oat plants.