Enhancing Salt Stress Tolerance in Portulaca oleracea L. Using Ascophyllum nodosum Biostimulant

Salinity stress is a major constraint on agricultural productivity, particularly in arid and semi-arid regions. This study evaluated the potential of Ascophyllum nodosum extract (ANE) in mitigating salinity-induced stress and enhancing the growth and physiological performance of Portulaca oleracea L. under NaCl concentrations of 0, 50, 70, and 100 mM for 50 days. A two-way ANOVA assessed the effects of NaCl concentration, ANE treatment, and their interaction. The results showed that ANE significantly increased plant height at 50 mM NaCl ( (p = 0.0011) but had no effect at higher salinity levels ( (p > 0.05). Shoot dry weight was significantly influenced by the interaction of NaCl and ANE ( (p = 0.0064), with ANE increasing biomass at 0 mM but decreasing it at 100 mM NaCl. However, ANE did not significantly affect root dry weight ( (p > 0.05). Physiological responses indicated a significant increase in proline content at 50 mM NaCl ( (p = 0.0011), supporting improved osmotic adjustment. Total soluble protein was significantly enhanced at all salinity levels except 100 mM NaCl ( (p < 0.01). Regarding ionic regulation, ANE had no significant effect on leaf sap pH ( (p > 0.05) but increased electrical conductivity (EC) at 70 and 100 mM NaCl ( (p < 0.01), suggesting a role in ion homeostasis under high salinity. Photosynthetic pigments responded positively to ANE, with significant increases in chlorophyll " "a "a" ( (p < 0.0001) and carotenoid content ( (p < 0.0001), while chlorophyll " "b "b" remained unchanged ( (p > 0.05). These findings highlight ANE's potential as a sustainable biostimulant for improving salinity tolerance, particularly at moderate NaCl levels. Future research should focus on molecular mechanisms and long-term field applications to optimize ANE's role in enhancing soil and crop productivity under salinity stress.