investigating the germination characteristics of poterium sanguisorba seeds under the influence of thermal treatments for pasture establishment

common burnet (poterium sanguisorba) is a perennial herb from rose family (rosaceae) which is used to construct pastures. the studied plant can resist against freezing, cool and drought. the present study was conducted to study the seed germination parameters of common burnet in different thermal treatments as completely randomized design in 4 replications in 2013. treatments involved the effects of constant temperature including 5, 10, 15, 20, 30, 35 and 45°c on germination parameters of 25 seeds which were used at each replication. the results showed that the effects of different thermal treatments on seed germination of common burnet were significant so that the lowest germination speeds at 5 and 10°c were 0 and 2.78 seeds a day and the highest germination speeds at 35 and 30°c were 8.95 and 7.77 seeds a day, respectively. the longest plume lengths were observed at temperatures of 10 (4.94 cm) and 15 °c (4.47 cm) and the shortest plume lengths were 35 and 45° (1.28 and 0 cm, respectively). the longest radicle lengths also were observed at 10 (5.13 cm) and 15 °c (5.05 cm) and the shortest ones occurred at 35 and 45 °c (0.88 and 0 cm, respectively). according to the fitted regression models between germination speed and temperature, minimum, optimum and maximum values of temperature were obtained at the ranges of 3.38-6.65, 26.82-34.5 and 45-46.78°c, respectively. according to the seed germination of studied plant at maximum and minimum temperatures, it can be used in constructing the pastures in arid and semi-arid areas.