Assessing germination characteristics of Australian native plant species in metal/metalloid solution

This study investigated tolerance of Australian native grass species Astrebla lappacea, Themeda australis, and Austrostipa scabra and a tree species Acacia harpophylla to different concentrations of arsenic As(V) (13.34-667.36 mu M), Cu2+ (0.5-200 mu M), Zn2+ (9-500 mu M), Mn2+ (8-10240 mu M) and Pb2+ (240-9600 mu M) in single solutions in germination experiments. Metalloid tolerance indicators used were maximum germination percentage (G(max)), mean germination time (MGT), radicle and shoot tolerance indexes (RTI & STI). Radicle tolerance index was the most sensitive indicator of metal tolerance in germinating seeds. All native species were highly tolerant to the metalloids tested, however, they showed different metal toxicity thresholds and levels of tolerance based on RTI as a metal tolerance indicator during germination. Overall, all four species could be classified as metallophytes, confirming their current suitability for and established use in mine site rehabilitation. This work may also serve as a basis for future studies on metalloid tolerance of other plant species during germination.