The germination process and seedling growth are crucial stages in the life history of a plant that are severely affected in the face of salinity, osmotic, and extreme temperature conditions. Therefore, this study aimed to investigate the efficacy of osmopriming with calcium chloride (CaCl2) on the tolerance responses of biological parameters of germination to the combined temperature (T) and sodium chloride (NaCl)-induced osmotic potential (Ψ) conditions using a developed hydrotime model. The germination behavior of Ca2+-primed and non-primed seeds was analyzed at different T (1, 5, 10, 15, 20, and 25 °C) and NaCl-induced Ψ (0, − 0.4, − 0.8, − 1.2, − 1.6, − 2, and − 2.4 MPa) conditions. According to the hydrotime model, Ca2+-primed seeds demonstrated a higher tolerance to the joint impacts of chilling and NaCl-induced osmotic conditions than those of non-primed ones. Generally, the priming treatment significantly ameliorated the extent, timing, uniformity of germination, and seedling vigor index at all examined hydro-thermal conditions compared with control seeds. This significance was associated with shifted ecophysiological parameters regarding hydrotime (ϴH), base water potential (Ψb), time taken for germination of a specific percentile (t(g)), and standard deviation of hydrotime (σϴ) toward the lower values following Ca2+-priming treatment, indicating a greater salinity tolerance. Hence, the presented biological parameters can easily be used to predict the physiological changes of germination under environmental factors over time. Also, results suggest that recommended Ca2+-priming treatment could be a time- and cost-effective method for improving quinoa cultivation in salt agriculture, especially in arid lands.
