Effects of Cd2+ and EDTA on young sugar beets (Beta vulgaris). II. Net uptake and distribution of Mg2+, Ca2+ and Fe2+/Fe3+ |
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Authors: | Maria Greger Sylvia Lindberg |
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Affiliation: | Dept of Botany, Univ. of Stockholm, S-106 91 Stockholm, Sweden;Dept of Plant Physiology, Swedish Univ. of Agricultural Sciences, S-750 07 Uppsala, Sweden. |
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Abstract: | Levels of Mg2+, Ca2+ and Fe2+/Fe3+ were determined in roots and shoots of sugar beet seedlings (Beta vulgaris L. cv. Monohill) cultured for 5 weeks in a complete nutrient solution to which either Cd2+ (0, 5 or 50 μM), EDTA (0, 10 or 100 μM) or a combination of both was added. The plants subjected to the various treatments showed a variety of deficiency symptoms. Leaves of the Cd2+-treated plants became thin and chlorotic (Mg- and Fe-deficiency symptoms). The plants showed reduced growth and developed only a few brownish roots with short laterals (Ca-deficiency symptoms). EDTA treatment resulted in green, stunted, hard leaves and reduced growth (Ca-deficiency symptoms). The deficiency symptoms observed correspond well with the observed uptake rates and distributions of Mg2+, Ca2+ and Fe2+/Fe3+. Increases in either Cd2+, EDTA or a combination of both in the growth medium, were correlated with increasing Mg2+ levels in the roots and with decreasing Mg2+ levels in the shoots. Cd2+ alone or in combination with EDTA had little influence on Ca2+ levels in the shoots but decreased Ca2+ levels in the roots. Thus, Cd2+ affects Mg2+ and Ca2+ transport in opposite ways: Mg2+ transport to the shoots is inhibited while that of Ca2+ is facilitated. Treatment with EDTA alone did not affect Ca2+ concentrations in either the shoots or the roots. Treatment with Cd2+ lowered Fe2+ concentrations in both roots and shoots. |
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Keywords: | Deficiency symptoms nutrition |
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