NaCl differently interferes with Cd and Zn toxicities in the wetland halophyte species Kosteletzkya virginica (L.) Presl.

Hydroponic experiments were carried out using seedlings of the wetland halophyte species Kosteletzkya virginica (L.) Presl. exposed to 10 μM Cd or 100 μM Zn in the absence or presence of 50 mM NaCl. Interaction between salinity and heavy metals was analysed in relation to plant growth, water status and tissue ion contents (Na, K and Ca). Results showed a strong inhibition effect of Cd on leaf emergence, lateral branch development and leaf expansion. Heavy metals induced a significant decrease in plant dry weight, water content, osmotic potential (Ψ S) and leaf water potential (Ψ w). Cadmium and Zn accumulated to higher extent in the roots than in the shoots. Cadmium increased the leaf K concentration while Zn had an opposite effect. Salinity strongly reduced Cd uptake and translocation from roots to shoots: it mitigated the Cd impact on lateral branch emergence but had no effects on plant dry weight and water status. Cadmium drastically reduced Na translocation in salt-treated plants while Zn increased it. It is concluded that complex interactions exist between heavy metals and monovalent cations in salt conditions and that Cd and Zn display contrasting behaviour in this respect. Stress-induced modification of ion content did not fully explain growth inhibition in Kosteletzkya virginica