Effects of NaCl stress on morphology and related physiological indexes of Carex subpediformis

Using Carex subpediformis as the experimental material, potted plants were used to study the effects of different concentrations of NaCl stress on their growth, development, and physiological index changes, and the salt tolerance threshold was calculated. The results showed that with increasing NaCl concentration, the plant height and crown width of C. subpediformis decreased, as did the dry weight content of the leaves. Under salt stress conditions, the plasma membrane permeability and malondialdehyde content of C. subpediformis leaves increased, changes in superoxide dismutase and peroxidase activities first increased and then decreased, free proline and soluble sugar content first increased and then decreased, and free proline content was significantly different between treatments (P < 0.05). The chlorophyll content of C. subpediformis first increased and then decreased. However, there was no significant difference in the chlorophyll a/b values between the treatments (P > 0.05). Taking a 50% decrease in the biomass of C. subpediformis as the standard, a regression equation was established to obtain the salt tolerance threshold of C. subpediformis at 169 mmol·L⁻¹. In conclusion, C. subpediformis is considered to have a certain tolerance to salt stress and can grow normally in a certain range of salt-stress environments. These results provide data support for follow-up studies on the salt tolerance mechanisms of C. subpediformis.