Affiliations: State Key Laboralory for Biological Control and School
of Life Science, Zhongshan University, Guangzhou 510275, China | Department of Biology, Hong Kong Baptist University,
Kowloon Tong, Hong Kong
Abstract: Responses of Sesbania rostrata and S. cannabina to Pb, Zn, Cu and Cd
toxicities were assessed by a seed-suspending seedbed (SSS) approach. The
results showed that the SSS approach was suitable for testing the tolerance of
a plant to the stress of toxic metals. The endpoints include seed germination
success, straightened radicle and hypocotyl of the seedlings from the seeds.
The measurements could be done easily and accurately. It was found that the
elongation of radicle was the most sensitive indicator to the stress of heavy
metals among the endpoints. When exposure to Iower or medium concentrations of
Pb, Zn, and Cd, the development of the lateral roots were favorable. Species of
S. rostrata was more tolerant than S. cannabina to the heavy metals, especially
to Zn and Cd. The ED_{50} of Pb, Zn, Cu and Cd were 32.90,
5.32, 4.40 and 12.00 μg/ml for S. rostrata,respectively, and.they were
30.11, 2.87, 4.05 and 4.94 μg/ml respectively for S. cannabina.
Keywords: Sesbania rostrata, Sesbania cannabina, heavy metal tolerance, testing method, root elongation, Pb/Zn tailings
