The influence of temperature on seed germination rate in quinoa (Chenopodium quinoa Willd.

The relationship between germination and constant temperatures in the range 8-35°C was tested on the South American grain species quinoa. A positive linear relationship was shown between temperature and germination rate for different germination fractions (G) from a base temperature, T b (G), at which germination rate is zero, to an optimal temperature, T o (G), of maximal germination rate. At temperatures higher than T o (G) there was a negative relationship between temperature and germination rate up to the maximal temperature for germination, T m (G). T b (G) was estimated to be constantly 3°C, while T o (G) showed variation within populations, so that 80% of the seeds in the population had T o (G) values from 30 to 35°C. The results suggest a maximal germination temperature T m (G) to be 50°C. It was shown that it is possible to define a line, describing germination of quinoa in the range from 10 to 80% as a function of thermal time, which is independent of germination temperature. The requirement of thermal time to germination, defined as root protrusion, was 30°Cd.