Launaea sarmentosa is a valuable medicinal plant with adaptability in saline areas, but it is still unclear how it responds to salinity. For the first time, the present study examined the plant’s changes under different soil salinities generated by 50, 100, 200, and 400 mM NaCl in order to elucidate its responses in terms of growth, photosynthesis, water uptake, osmotic adjustment, ion homeostasis, and oxidative stress defense to salinity. The results showed that the plant’s growth was enhanced by 50 mM NaCl with an 18.07% increase in dry biomass compared to the control, whereas higher salinity levels reduced its growth with a 6.39–54.85% decrease in dry biomass. The plant’s growth response indicates that it had tolerance to salinity levels up to 400 mM NaCl. The accumulation of photosynthetic pigments, including chlorophylls (a + b) and carotenoids, was enhanced under salinity, except for a reduced accumulation under 400 mM NaCl. Relative water content decreased while proline content increased in the salt-stressed plants. Moreover, the salt-stressed plants reduced their K⁺ and NO₃⁻ content along with increases in Na⁺ and Cl⁻ content. The high salt stress level also caused oxidative stress in the plants, which was revealed through the accumulation of malondialdehyde and hydrogen peroxide content. In addition, the salt-stressed plants had increased total phenolic content and the activities of antioxidant enzymes such as catalase, peroxidase, and superoxide dismutase. These physiological and biochemical changes suggest that L. sarmentosa evolved adaptive mechanisms in photosynthesis, osmotic adjustment, ion homeostasis, and antioxidant defense for growing under salt stress.

Common purslane (Portulaca oleracea) is a halophyte, consumed not only as an edible vegetable but also as a traditional medicine. This plant can adapt to extreme salinity and drought conditions and their effects on plant growth, yield and quality were elucidated, but the effects on seed germination was still unclear. Seed germination is an important stage for establishing P. oleracea seedlings that contribute to plant yield and productivity. Thus, the objective of the present study was to examine the individual effects of salinity and drought stress at different levels on the characteristics of seed germination, which the seeds suffered from −0.22, −0.45, −0.89, and −1.78 MPa osmotic stresses induced by polyethylene glycol (PEG), or from 50, 100, 200, and 400 mM NaCl stresses with equivalent osmotic pressures. The seeds sown in petri dishes containing filter paper layers that were flooded with NaCl or PEG-6000 solutions for the treatments and germination parameters were determined daily for 15 days. Data showed that germination percentage (GP), germination rate (GR), germination energy (GE), and mean germination time (MGT) were significantly decreased with increasing levels of salt and osmotic stresses, suggesting that the salinity and drought stress reduced the germination capability of seeds. Moreover, the seeds maintained germination with PEG osmotic pressure above −0.22 MPa, but not with NaCl concentration greater than 50 mM that induced a similar osmotic pressure, suggesting that the ion toxicity effect on the seed germination might be higher than the osmotic effects.

Phyla nodiflora is a valuable medicinal plant growing in coastal areas, hypothesizing its adaptability to salinity; however, it has not been investigated. This study, for the first time, elucidated responses in the growth of the shoots and its physiology to different soil salinity of 50–400 mM NaCl. The data showed that the shoot’s dry biomass was not affected by the salinity levels up to 100 mM, and it only decreased 33.50–56.33% compared to the control under 200–400 mM NaCl, indicating that P. nodiflora is a salt-tolerant plant that could survive under high salinity. In addition, the plant also had physiological responses which indicated its salt-induced injuries and adaptation to the salt stress. The chlorophyll a content was increased while the chlorophyll b remained unchanged under the salt stress. The proline and salt accumulation increased under the salinity, but the K⁺ and NO₃⁻ accumulation decreased. Moreover, increases in malondialdehyde and electrolyte leakage were observed, indicating salt-induced membrane damages. These responses suggested that the plant might evolve adaptive mechanisms to salinity. Our findings are useful information for further research in order to elucidate the salt-tolerant mechanisms and develop this plant for saline agriculture.