Effect of temperature on seed germination characteristics of Doremaammoniacum

Doremaammoniacum D. Don of Apiaceae family is an industrial, medicinal, and forage species that its gum is used in industry and medicine. In recent years, two factors, inappropriate exploitation and change of use of its growing habitats has faced this plant species to extinction risk. On the other hand, due to dormancy, the seed of D.ammoniacum has low germination rate. An experiment was carried out with seven temperature levels 2, 4, 6, 8, 10, 13 and 15 (Degrees Celsius). In a completely randomized design with four replications in seed technology laboratory of Jihad-Agriculture Education Center, Mashhad/Iran. Results showed that the effect of temperature on germination characteristics was significant (P>%1). The maximum rate of germination percentage, germination rate, radicle length, Plumule length, root to shoot ratio & seed vigor index were obtained from 6°C and the lowest amount of them were observed for 2 or 15 degrees Celsius. All germination characteristics were decreased when the temperature increases to more than 6°C too. The result of linear regression between temperature and germination rate for D.ammoniacum seed showed that the minimum, optimum and maximum temperatures for germination of this species were: 1.53°C, 5.9°C and 15.9°C, respectively.