Relationships among nitrogen, silicon, and heavy metal uptake by plants
1989
Because vegetative parts of grass species are generally high in Si, monocot and dicot plants were grown in steam-sterilized soil to further test the hypothesis that there is competition between N and Si for plant uptake. Silicon uptake by dicots is low, so the species tested in this study was not sensitive to changes in Si with N differences. With monocots, N decreased Si uptake, but NH4-N decreased it more than did NO3-N in wheat. In contrast, the NH4 increased uptake of Fe, Al, Cu, and Zn, but not Mn. The results were explainable, at least in part, on the effects of exchange of NO3 for OH, and NH4 for H in the uptake process. With corn and barley, a high P application resulted in increased Si in shoots of plants only at low N levels. Leaf concentrations of Si, Fe, Al, Cu, and Ti were generally higher in barley than in corn.
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