Ecophysiological responses of Glycine max L. under single and combined cadmium and salinity stresses

Abstract

Soil contamination by cadmium (Cd) and degradation by salinity are likely to become one of the most important problems hindering food production and human health. However, their combined effect on crops is still ambiguous. A hydroponic study was made to investigate the separate and combined exposure of 100 µM Cd and 150 µM NaCl on soybeans (Glycine max L.) growth, photosynthetic pigment, and antioxidant systems for 7 days. Both Cd and NaCl, applied separately decreased the seedlings growth, chlorophyll contents and caused oxidative stress. However, the toxic effects of salinity applied alone were more pronounced. Interestingly, combined exposure of Cd and NaCl induced higher decreases in all growth parameters and lipid peroxidation than single exposure suggesting synergistic effects. The results implicate that the phytotoxicity of both stressors can be associated with redox status imbalance. Our finding may provide insight into the physiological mechanisms of heavy metal exposure and salinity stress tolerance in soybeans and suggest that saline stress changes the effects of Cd toxicity on crops in Cd-salt-polluted soils.

Keywords: Antioxidant system; Cadmium; Co-exposure; Glycine max; Oxidative stress; Salinity.