Effects of pH and heavy metal concentrations in solution culture on the proton release, growth and elemental composition ofAlyssum murale andRaphanus sativus L.

Abstract

The proton release by a species that can hyperaccumulate nickel (Alyssum murale) and by a non-accumulator (Raphanus sativus L.) was studied at different pH and heavy metal concentrations in solution culture. Both factors influenced the growth and composition of the plants.A. murale was more sensitive than radish to a decrease of pH from 7.0 to 6.0 in the growth medium; plant yield and proton production diminished with decreasing pH. However, yields and proton production of radish only decreased at pH 5.5. The differences in the amounts of protons produced between the hyperaccumulator species and radish were not large enough to conclude that decreasing pH in the rhizosphere ofA. murale is a mechanism for heavy metal solubilization.