[Seed germination, bud growth and heavy-metal accumulation of Suaeda salsa]

Nickel and copper, as high toxic heavy metals (HMs), are the most serious contaminants in Jinchuan mining area, China. In this paper, the influence of combined HMs stress on the growth of widespread plant-S. salsa has been studied. The stress gradient of combined Ni-Cu was set based on the local environment and pre-experiment. Seed germination, growth, physiological characteristics of S. salsa were investigated by the control test, and its heavy metal bioaccumulation capacity was investigated by samples collected from field platform. The growth of S. salsa was promoted at lower concentration (≤40 mg/L) and inhibited at higher concentration (≥80 mg/L) under the single HMs stress and combined HMs stress (Cu20/Ni20). The malondialdehyde (MDA) content was increased with increasing concentration, and the soluble protein and free proline content in stress group were higher than that of in control group. Under single HMs stress, the peroxidase (POD) activity increased with increasing concentration; while under combined HMs stress, the POD activity increased initially and then reduced. Cu320 and Ni320 combined HMs stress inhibited the growth of S. salsa at all concentrations. The average translocation factors (TF) of S. salsa were greater than 1.00, and higher in leaves compared to stems. The results of bio-concentration factors (BCF) of S. salsa show that BCF of leaves were larger than that of roots and stems. At lower concentration, the combined HMs stress promoted the growth of S. salsa in comparison to single HMs stress, however, opposite results were obtained at higher concentration. Overall, S. salsa showed high tolerance to Cu and Ni and stronger capabilities of HMs uptake and translocation, and therefore, it can be used as an alternative plant for the bioremediation of heavy metal pollution in mining area.