LAUSR

This study aimed to examine the effects of NaCl on Cd tolerance of two halophytes with contrasting salt-tolerance ability: the euhalophyte Suaeda glauca and the recretohalophyte Limonium aureum. Plant growth, photosynthesis and physiological responses of two halophytes were measured in a pot experiment treated with 0, 3 and 6 mg kg−1 Cd in combination with 0 and 0.3% NaCl. Both halophytes exhibited fair-level (moderate level) Cd tolerant ability. NaCl mitigated Cd-induced toxicity on the growth and photosynthesis of S. glauca, particularly under low Cd level, while a negative effect of NaCl was observed in L. aureum. Moreover, activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) in leaves of S. glauca were boosted by Cd and/or salinity treatment. Although similar responses were observed, the overall increase of enzymatic activities in L. aureum was lower than in S. glauca. The soluble protein content in two species showed an opposite trend among treatments, whereas the proline accumulation in L. aureum was exceptionally higher than that in S. glauca under saline conditions. The nutrient concentrations of these two halophytes were only slightly affected by Cd excess, and NaCl significantly enhanced their Na accumulation, regardless of the plant’s organ and Cd level. In addition, Cd absorption and translocation were greatly enhanced by NaCl in the two halophytes. Salt-induced alleviation of Cd toxicity in S. glauca might be mainly attributed to salt-triggered secondary metabolic strategy, which deffers from the energy-consuming adaptive strategy employed by L. aureum.