Quantifying water stress and temperature effects on quinoa seed germination using hydrothermal-time-to-event models

Abstract Quinoa (Chenopodium quinoa Willd.), exhibits considerable tolerance to abiotic stresses, and its grains are rich in essential minerals, vitamins, and protein. Therefore, this study was conducted to evaluate the effect of water potential (ψ) and temperature (T) on quinoa germination behavior using the most efficient models (hydrothermal-time-to-event models) as the first study in this case. One of the advantages of these models is that their parameters accurately represent the cardinal Ts, eliminating the need to use additional non-linear equations. For this purpose, quinoa seeds were incubated at a factorial arrangement of eight Ts (5, 10, 15, 20, 25, 30, 35, and 40 ◦C) and four ψs (0, − 4, − 8, and − 12 bar). The detailed regression analysis results revealed that T × ψ interaction was synergistic, rather than additive, especially at warmer Ts and lower ψs. The ψb value remained constant at Ts ≤ 22.7 ◦C (− 18.68 bar), afterward it increased (shifted to positive values) linearly to − 9.12 bar at 40 ◦C. The thermal-time-to-event model accurately (R² > 0.97) showed that the ψ levels increased Tb, but decreased Tc; however, the Topt remained statistically constant at different ψs. Cardinal Ts for quinoa germination at zero bar were estimated to be 2.2 ◦C for Tb, 31.86 ◦C for Topt, and 44.33 ◦C for Tc. Consequently, quinoa could be categorized as a cold-tolerant and suitable for cultivation in arid regions because of its high resistance to low ψs.