Effect of heavy metals combined stress on growth and metals accumulation of three Salix species with different cutting position

ABSTRACT

This study aimed to compare growth performance and heavy metal (HM) accumulation at different cutting positions of Salix species grown in multi-metal culture. Three Salix species stems cut at different positions (apical to basal) were grown hydroponically for four weeks. The plants were then treated for three weeks with 0, 5, 10, and 20 μM Cd, Cu, Pb, and Zn, resulting in total metal concentrations of 0, 20, 40, and 80 μM. The growth parameters and HM content in shoots and initial cutting were measured. Results showed that, compared with S. fragilis, S. matsudana grew more poorly in uncontaminated condition but grew better and accumulated lower metal in shoots under mixed HM treatment. In addition, cuttings from apical parent stem position exhibited poorer growth performance before and after treatment, as well as greater metal content in shoots than base parts under the HM treatment. These results suggest that S. matsudana may undergo a special mechanism to hinder metals in the initial cutting, thus mitigating growth damage. The apical portion also showed poor resistance against the invasion of mixed HMs because of the immature structure. Therefore, in the selection of phytoremediation plants, metal accumulation ability is not proportional to growth performance.

KEYWORDS:

• cutting position
• growth performance
• phytoremediation

Funding

This work was financially supported by the Sanxin Forestry Project in Jiangsu Province (LYSX[2012]02), Major Science and Technology Program for Water Pollution Control and Treatment (No. 2012ZX07204–004–003), Ph.D. Programs Foundation of the Ministry of Education of China (No. 20110091110018), Strategic Priority Research Program-Climate Change: Carbon Budget and Related Issues of the Chinese Academy of Sciences (XDA05050204), the specimen platform of China, and the teaching specimens sub-platform (2005DKA21403-JK).