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 degrees C was tested on the South American grain species quinoa. A po sitive linear relationship was shown between temperature and germination ra te 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 m aximal germination rate. At temperatures higher than T-o(G) there was a neg ative relationship between temperature and germination rate up to the maxim al temperature for germination, T-m(G). T-b(G) was estimated to be constant ly 3 degrees C, while T-o(G) showed variation within populations, so that 8 0% of the seeds in the population bad T-o(G) values from 30 to 35 degrees C , The results suggest a maximal germination temperature T-m(G) to be 50 deg rees C. It was shown that it is possible to define a line, describing germi nation of quinoa in the range from 10 to 80% as a function of thermal time, which is independent of germination temperature. The requirement of therma l time to germination, defined as root protrusion, was 30 degrees Cd.