ارزيابي درجه حرارت هاي حداقل، بهينه و حداكثر جوانه زني كرامب

Investigations on the cardinal temperatures for germination of Crambe kotschyana

Cramb is an important medicinal and industrial plant which distribute in a vast area of Khorasan Razvi rangeland. A laboratory study was conducted to investigate the effect of different temperatures on seed germination of Crambe kotschyana in a randomized design with four replications of 25 seeds. Various constant temperatures (2, 5, 10, 15, 20, 25, 30, 35 and 40°C) were considered. The characteristics such as percentage of seed germination, rate of seed germination, the time of reaching 50% seed germination were recorded. The effect of temperature on rate and percentage of germination was significant. Maximum seed germination (100%) occurred in all temperatures except 2, 35 and 40°C. In All temperatures except of 2, 35 and 40°C, there was no significant difference in rate of seed germination. However, the highest rate of seed germination was obtained in 20 °C. Based on linear regression between germination rate and temperature in both species, the cardinal temperatures: minimum (Tmin), optimum (T0) and maximum (Tmax) were determined which were: 1.7, 18 and 43 °C for Crambe abyssinsca, respectively.