Combined effects of aluminium and nitrogen forms on root growth of ten ecologically distinct plant species
1991
Rode, M.W. | Runge, M.
Single and combined effects of Al and nitrogen forms on the root growth of ten plant species, distributed on soils with different acidity, were examined in nutrient solutions. Al-tolerance corresponds to the distribution of species within the natural range of soil acidity. Species from acid soils are very Al-tolerant, species from medium acid to alkaline soils are more or less Al-sensitive. Most Al-tolerant species grow equally well with mixed N-forms and with NO3-supply. Al-sensitive species prefer a NO3-supply. This different reaction can be explained by different H(+)-tolerance, Al-tolerant species being at the same time H(+)-tolerant. OH(-)-excretion, caused by NO3-assimilation, leads to an Al-precipitation at the root surface and in the free root space, but this does not enhance Al-tolerance. The Ca-content of the roots of all species is diminished by Al as well as by NH4-addition to the substrate. A concluding hypothesis is derived, stating that the specific Ca-demand of the plasmalemma is of decisive importance to the H(+)- and Al-tolerance of individual species.
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