Quantifying seed germination response of quinoa (Chenopodium quinoa Willd) under temperature and drought stress regimes

Quinoa (Chenepodium quinoa Willd) is a grain-like crop with high nutritional values and resistant to abiotic stresses such as salinity, drought, cold and heat. In order to study germination characteristics of quinoa seeds underdrought stress conditions at different temperatures, an experiment was conducted. Seeds were incubated on four water potential levels (0, -4, -8 and -12 bar) of PEG and germinated at constant temperatures ranging from 5 to 35°C (5, 10, 15, 20, 25, 30, and 35 °C) in Petridishes. Results showed that germination didn’t occur with decreasing water potential to -12 Bar at low temperatures, but germination percentage achieved to %85 in -12 Bar with gradual increase in temperature from 5 to 30°C. Seed germination rate decreased with decreasing water potential at all levels of temperature. Cardinal temperatures at all levels of water potential were calculated by using two nonlinear regression models (beta and dent-like), and then their accurate predictions and performances were compared by root mean square error (RMSE) and coefficient of determination (R2). With decreasing water potential, the permissive temperature range for germination was limited. To sum up, base temperature at (0, -4, -8 & -12) Bar increased to (1, 1, 2.5 & 15°C) and regarding for ceiling temperature decreased to (54, 41, 41 and 36°C), respectively.