Physiological Adaptations of Purslane to NaCl-Induced Salinity Stress

Abstract

Salinity is one of the major abiotic stresses limiting plant growth, productivity, and physiological performance worldwide. Purslane (Portulaca oleracea L.), a nutritious leafy vegetable and medicinal plant, is considered relatively tolerant to saline conditions compared to many conventional vegetable crops. The present study investigated the physiological adaptations of purslane under different levels of NaCl-induced salinity stress. Two experiments were conducted under laboratory and net-house conditions using varying concentrations of sodium chloride (0, 50, 100, 150, and 200 mM NaCl). Germination, growth attributes, chlorophyll contents, ion accumulation, proline, phenols, and non-structural carbohydrates were evaluated to determine the plant’s adaptive responses to salinity stress. The results demonstrated that increasing salinity levels significantly reduced germination percentage, plant height, leaf number, fresh biomass, and chlorophyll contents. However, purslane showed considerable tolerance to moderate and high salinity by activating several physiological defense mechanisms. Accumulation of proline, phenols, and non-structural carbohydrates increased markedly under severe salinity stress, indicating their role in osmotic adjustment and stress protection. Similarly, sodium and chloride accumulation increased in plant tissues under higher NaCl concentrations, while potassium regulation contributed to ionic balance. The study revealed that purslane possesses effective physiological and biochemical adaptations that enable survival and growth under saline conditions. These findings highlight the potential of purslane as a salt-tolerant vegetable crop suitable for cultivation in salt-affected soils, particularly in arid and semi-arid regions. Furthermore, the study provides valuable insights into plant adaptive mechanisms that may support future research on salinity tolerance and sustainable agricultural production.