Growth Performance and Osmotic Adjustment of Purslane under Various NaCl Salt Stresses

Abstract

Salinity is one of the most severe abiotic stresses limiting agricultural productivity and plant growth worldwide, particularly in arid and semi-arid regions where salt accumulation in soils adversely affects crop performance (Munns & Tester, 2008). The present study investigated the growth performance and osmotic adjustment mechanisms of purslane (Portulaca oleracea L.) under various NaCl-induced salinity stresses. Laboratory germination and net-house pot experiments were conducted at the Institute of Plant Sciences, University of Sindh, Jamshoro, using five salinity treatments: 0, 50, 100, 150, and 200 mM NaCl. The experiments were arranged in a Complete Randomized Design (CRD) with four replications to evaluate germination behavior, vegetative growth, physiological responses, and osmotic adaptation under saline conditions. The results demonstrated that increasing NaCl concentrations significantly reduced germination percentage, plant height, leaf number, fresh and dry biomass, and chlorophyll contents. Severe salinity stress at 150 and 200 mM NaCl markedly inhibited plant growth and photosynthetic pigments, indicating the negative effects of osmotic stress and ion toxicity. However, purslane exhibited substantial physiological adaptation through enhanced accumulation of compatible osmolytes and ionic regulation mechanisms. Proline and soluble carbohydrate concentrations increased progressively with increasing salinity levels, suggesting their important role in osmotic adjustment and stress protection. Similarly, sodium and chloride accumulation increased significantly in plant tissues under higher salinity, whereas potassium concentration declined, resulting in altered ionic balance. Overall, the study revealed that purslane possesses effective osmotic adjustment and physiological defense mechanisms that enable survival under moderate to high salinity conditions. These findings highlight the potential of purslane as a salt-tolerant vegetable crop suitable for cultivation in saline and marginal soils, contributing to sustainable agriculture and improved utilization of salt-affected lands.