Uptake of chromate in sulfate deprived wheat plants

Terrestrial plants have been proposed for the removal of chromate from waste waters. Since chromate seems to be absorbed in roots by the same transport system as sulfate, sulfate-deprivation pretreatment and sulfate absence during chromate uptake were tested in wheat in order to increase chromium uptake efficiency. At 1 and 5 mu g CrO42- ml(-1) the highest chromate uptake was observed when plants suffered 5 days of sulfate deprivation pretreatment and absence of sulfate during chromate uptake. However, only at the lower concentration chromate net uptake was rapidly replaced by net efflux presumably due to toxic effects. At 5 mu g CrO42- ml(-1), the uptake of chromate was also enhanced by sulfate-deprivation pretreatment alone or lack of sulfate-competition. We conclude that sulfate is a strong inhibitor of chromate uptake, and when plants are going to be used to remove chromate from waste waters, sulfate-chromate interaction should be considered. (C) 1997 Elsevier Science Ltd.