Physiological Responses of Amaranthus hybridus L. under Salinity Stress

Soil salinity is an abiotic factor that adversely affects growth and development of plants. To evaluate the physiological responses of Amaranthus hybridus L. under salinity stress, seedlings were exposed to 0, 0.1 and 0.2M NaCl for a period of 6 weeks. Whole plant dry weight, relative water content (RWC), total chlorophyll, lipid peroxidation, protein level and antioxidant enzymes activities were evaluated after the treatment period. The results of the study showed that salinity caused a significant decrease in whole plant dry weight, relative water content, total chlorophyll and protein content while an increase in malondialdehyde content, catalase and ascorbate peroxidase activities were observed. The severity of these effects was concentration dependent. The biomass accumulation of the control plants was 11.67±0.39 g, while those that received 0.1 and 0.2 M NaCl had 9.22±0.28 and 6.94±0.07 g respectively. The increase in malondialdehyde content and antioxidant enzymes activities were indications that salinity stress induced the production of reactive oxygen species (ROS) which caused oxidative damage to macromolecules in living cells.