Common burnet (Poteriumsanguisorba) is a perennial herb from rose family (Rosaceae) which is used to construct natural and synthetic pastures. This perennial herb has erected stems. The root system of the plan is able to penetrate 70-100 cm deep in soil. The studied plant can resist against freezing, cool and drought. The present study was conducted to study the seed germination parameters of common burnet under different thermal treatments as completely randomized design in 4 repetitions in 1392. Treatments involved the effects of constant temperature of 5, 10, 15, 20, 25, 30, 35, 40 and 45° C on germination parameters of seeds 25 of which were used at each repetition. Results showed that the effects of different thermal treatments on seed germination of common burnet were significant with the lowest germination speed of 2.26 seeds a day was obtained at 5°C and the highest germination speeds of 8.3 and 5.63 were obtained at 5 and 10°C. The longest plunume lengths occurred at constant temperatures of 10° (4.94 cm) and 15° (4.47 cm) and those of shortest ones occurred at 35 and 45° (1.28 and 0 cm respectively). The longest radicle lengths also were observed at 10° (5.13 cm) and 15° (5.05 cm) and those of the shortest ones occurred at 35 and 45° (0.88 and 0 cm respectively). According to fitted regression models between germination speed and temperature, the values of minimum, optimum and maximum temperatures were obtained at ranges of 3.38-6.65, 26.82- 34.5 and 45- 46.78°C respectively. According to the seed germination of the studied plant at maximum and minimum temperatures, it can be used in constructing pastures in arid and semi arid areas.

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