Copper, lead, and zinc tolerance and accumulation in the <scp>Australian</scp> rattle pods <i>Crotalaria novae‐hollandiae</i> , <i>C. medicaginea,</i> and <i>C. mitchellii</i>

Abstract Crotalaria is a genus of ~600 species of legumes predominantly found in (sub)tropical regions of Africa and Australia. Crotalaria novae‐hollandiae from Australia is a polymetallic zinc (Zn)‐cadmium(Cd)‐copper(Cu) hyperaccumulator, but only when growing in metalliferous soils. This study aimed to test metal tolerance in Australian Crotalaria species to establish whether metal tolerance is a trait shared between Crotalaria species not known to occur on metalliferous soils. The hyperaccumulator Crotalaria novae‐hollandiae and two non‐metallophytes, Crotalaria mitchellii and Crotalaria medicaginea, were exposed to different treatments containing Cu‐lead(Pb)‐Zn in the form of spiked soils. Foliar samples were analyzed for total elemental concentrations and spectrophotometric analysis was undertaken to assess photosynthetic pigments (chlorophyll a + b and carotenoids) as indicators of stress and polyphenols as an indicator of tolerance. No significant differences in metal accumulation were found in the Crotalaria species, and all exhibited a high level of tolerance toward Zn. However, C. novae‐hollandiae exhibited the greatest tolerance toward Zn but had low tolerance toward Cu, while none accumulated foliar Pb. Tolerance to Zn appears to be a trait shared between the Crotalaria species tested. None of the tested Crotalaria species exhibited tolerance toward Cu, and none accumulated Pb.