Root potassium and hydrogen flux rates as potential indicators of plant response to zinc, copper and nickel stress

Differences in the short-term induction of increased K+ efflux and decreased H+ influx from the roots among the four species were reflective of the long-term declines in photosynthetic capacity and growth observed in poplar and willow, but not in hemp. Tissue degradation patterns and increased K+ efflux in poplar, willow and alfalfa due to heavy metal stress are consistent with reports in the literature of an imbalance in ROS and efficient scavenging of hydroxyl radicals. Taken together, results indicate that ion flux measurements can predict heavy metal stress sensitivity and support their potential use for describing root-level responses to the combined contaminant conditions often observed in sites selected for phytoremediation.