Temporal Changes in Biochemical Responses to Salt Stress in Three Species.

Halophytes adapt to salinity using different biochemical response mechanisms. Temporal measurements of biochemical parameters over a period of exposure to salinity may clarify the patterns and kinetics of stress responses in halophytes. This study aimed to evaluate short-term temporal changes in shoot biomass and several biochemical variables, including the contents of photosynthetic pigments, ions (Na, K, Ca, and Mg), osmolytes (proline and glycine betaine), oxidative stress markers (HO and malondialdehyde), and antioxidant enzymes (superoxide dismutase, peroxidase, catalase, and ascorbate peroxidase) activities of three halophytic species (, , and ) in response to non-saline, moderate (300 mM NaCl), and high (500 mM NaCl) salinity treatments at three sampling times. plants showed maximum shoot biomass under moderate salinity conditions. The results indicated that high Na accumulation in the shoots, coupled with the relative retention of K and Ca under salt stress conditions, contributed significantly to ionic and osmotic balance and salinity tolerance in the tested species. Glycine betaine accumulation, both constitutive and salt-induced, also seems to play a crucial role in osmotic adjustment in plants subjected to salinity treatments. species possess an efficient antioxidant enzyme system that largely relies on the ascorbate peroxidase and peroxidase activities to partly counteract salt-induced oxidative stress. The results also revealed that exhibited higher salinity tolerance than and , as shown by better plant growth under moderate and high salinity. This higher tolerance was associated with higher peroxidase activities and increased glycine betaine and proline accumulation in Taking all the data together, this study allowed the identification of the biochemical mechanisms contributing significantly to salinity tolerance of through the maintenance of ion and osmotic homeostasis and protection against oxidative stress.