In the present study, the effects of foliar application of salicylic acid (100 μM), cerium oxide (50 mg L−1), and cerium oxide:salicylic acid nanoparticles (CeO2: SA-nanoparticles, 50 mg L−1 + 100 μM) on the growth and physiological responses of purslane (Portulaca oleracea L.) were examined in non-saline and saline conditions (50 and 100 mM NaCl salinity). Foliar applications mitigated salinity-induced adverse effects, and the highest plant height and N, P, Mg, and Mn content were recorded in the variant with non-saline × foliar use of CeO2: SA-nanoparticles. The highest values of fresh and dry weight were noted in the treatment with no-salinity × foliar use of CeO2:SAnanoparticles. The highest number of sub-branches was observed in the foliar treatments with CeO2-nanoparticles and CeO2:SA-nanoparticles without salinity stress, while the lowest number was noted in the 100 mM NaCl treatment. Moreover, the foliar application of CeO2:SA-nanoparticles and cerium-oxide nanoparticles improved the total soluble solid content, K, Fe, Zn, Ca, chlorophyll a, and oil yield in the plants. The salinity of 0 and 50 mM increased the K content, 1000-seed weight, total soluble solid content, and chlorophyll b content. The use of 100 mM NaCl with no-foliar spray increased the malondialdehyde, Na, and H2O2 content and the Na+/K+ ratio. No-salinity and 50 mM NaCl × CeO2: SA-nanoparticle interactions improved the anthocyanin content in plants. The phenolic content was influenced by NaCl100 and the foliar use of CeO2:SA-nanoparticles. The study revealed that the foliar treatment with CeO2:SA-nanoparticles alleviated the side effects of salinity by improving the physiological responses and growth-related traits of purslane plants.
