The development of absorption and transport systems in the corn root: structural and experimental evidence
1991
Danilova, M.F. | Mazel, Yu.A. | Jitneva, N.N. | Telepova, M.N.
The root structure of the 1- and 2-week-old corn seedlings was studied by means of light and electron microscopy. In the different root zones the potassium (86Rb) and calcium (45Ca) absorption was measured. The results of the study are as follows: (1) Ca uptake was most intensive in the apical root segment (0-2mm); (2) the highest rate of K uptake was found at the base of the root (6-8mm from the grain); Ca and K are absorbed at similar rates by all other root segments from the zone root hairs up to the root base; (4) the significant part of absorbed K is transported to the root tip as well as to the other parts of the root and to the grain and the shoot; (5) Ca is not transported into the apical part of the root from other zones; (6) Ca transport from the apical segment occurs over a shorter distance (several millimeters) and at a lower rate compared with K; (7) the bulk of Ca absorbed by all segments (except the most apical) is transported upward and a considerable part of it is accumulated in the grain and shoot. Data on the absorption and transport of ions are compared with the results of the anatomical studies. It was shown, that both the absorption and transport of ions are determined mostly by structural features of root tissues in different root zones (the mucilage layer on the root surface, gradual maturation of vascular elements, cell wall secondary changes in different tissue layers, lateral root initiation etc).
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