Impact of Abiotic Stresses on Seed Germination of Two Quinoa Cultivars Differ in Salinity Tolerance: Implications for Cultivation in Arid Climates

Global climate change leads to increasingly frequent and severe abiotic stresses, posing major challenges to food production and agricultural sustainability. This study examined the effects of drought, temperature, and light conditions—and their interactions—on the final germination percentage (FGP), germination rate index (GRI), and germination recovery (GR) of two quinoa (Chenopodium quinoa Willd.) varieties differing in salinity tolerance. Seeds were treated with five concentrations of polyethylene glycol (PEG 6000) to simulate osmotic potentials of 0, −0.5, −1.0, −1.5, and −2.0 MPa, and then incubated at 15/25 °C, 20/30°C, and 25/35°C under both 12-hour dark/12-hour light cycles and continuous darkness. The results showed significant effects of osmotic potential, temperature, and their interactions on seed germination in both quinoa accessions. The salt-tolerant accession ICBA-Q3 exhibited higher FGP and GRI under stress conditions than the less salt-tolerant accession ICBA-Q5. Germination was substantially reduced at higher PEG concentrations and elevated temperatures, particularly in ICBA-Q5. The ability of seeds to recover germination after transfer from different osmotic solutions into distilled water was greater under cooler and illuminated conditions. Significant differences in GR were also observed between accessions under different temperature and osmotic stress levels. These findings provide valuable insights into quinoa germination responses under diverse environmental stresses and contribute to the development of effective cultivation strategies in arid and saline environments.