نکته کلیدی برای محاسبه دقیق سرعت جوانه‏زنی و دماهای کاردینال

Accurate estimation of the parameters is one of the necessary conditions to achieve an accurate output of the crop simulation models. Cardinal temperatures are most widely used in the models. Whit an accurate estimate of the germination rate can be calculated the real cardinal temperatures. The common method of germination rate calculating was evaluated in this study. So, two sets of germination data (in 0 and -6 bar salinity) of yellow sweet clover at 0, 5, 10, 15, 20, 25, 30° C were used. In this study, two methods were used to calculate the germination rate I) reverse time until fifty percent of the seeds germinated (as common method) (1/D50M)II) reverse time until fifty percent of the total seed (1/D50A). For treatment of 0 bar that all temperatures germination were more than 90%, cardinal temperatures derived from 1/D50M and 1/D50A had no difference. But, in -6 bar salinity that the seed germination at temperatures close to the ceiling and base temperature were dramatically reduced, the ceiling temperature of the yellow sweet clover was estimated more than the actual amount by using 1/D50M. But, it was close to actual amount when 1/D50A was used to estimate cardinal temperature.