Cadmium accumulation and growth response to cadmium stress of eighteen plant species.

This study investigated the cadmium (Cd) accumulation and growth response to Cd stress of 18 plant species. After growth for 30 days in the sand containing 0, 2, or 10 mg Cd kg-1, seedlings were evaluated for growth parameters, specific root length, and Cd accumulation. The 18 species differ greatly in Cd accumulation and resistance to Cd stress, depending on Cd concentrations in the sand. Under high Cd condition (10 mg kg-1), the 18 species were classified into two groups: (1) Indian mustard and rapeseed having high Cd tolerance and increased accumulation capacity in shoots could be considered as Cd accumulators, and (2) the remaining 16 non-accumulators constitute a species continuum from the indicators to excluders. Shoot Cd concentration showed exponential decay relationships with biomass production, absolute growth rate, and growth ratio, indicating that biomass production negatively relates to the shoot Cd concentration in non-accumulators via dilution or concentration effect. Species with high biomass generally accumulate low Cd in the shoots and display high Cd-tolerant capacity. Indian mustard and rapeseed are promising species for long-term phytoextraction of Cd-contaminated farmlands for bioenergy production.