Alleviation of arsenic stress in cardoon plants via the supply of a low cadmium concentration

Abstract

The effect of As (0–80μM) and of As+Cd (0–80μM+5μM) combinations on plant growth, toxicological variables and As and Cd bioaccumulation was studied in cardoon plants under controlled conditions. Plants grown in the presence of As alone showed less reduction in overall root and shoot development than those exposed to As+Cd, although the main root was shorter than in the latter plants. The effective added concentrations of As that reduced shoot or root dry weight by 50% (EC50) and the critical toxic concentration that caused a 10% reduction in plant growth (CTC10%) were higher in plants grown with As alone. In both treatments (As and As+Cd), the CTC10% was higher in the roots, but the root EC50 was lower than the shoot EC50. The presence of Cd increased the accumulation of As in the shoot, but ≥20μM As reduced the shoot bioaccumulation of Cd. Thus, the presence of 5μM Cd with As appears to reduce the tolerance of cardoon plants to the latter element, but it increases their As phytoextraction capacity. Cardoon plants could be used as excluders in As-contaminated sites and as accumulators in those co-contaminated with As and Cd.