Modeling cardinal temperatures and germination behavior of seeds of Parrotia persica C.A. Meyer as affected by temperature and breaking dormancy treatments

Information regarding germination and dormancy of Parrotia persica seeds is very limited and there are no reports on cardinal temperatures and type of dormancy of this tree species. Thus, the purpose of this study was to determination of type of dormancy and cardinal temperature of seeds of P. persica and to identify the best way(s) to overcome seed dormancy in P. persica. In order to investigate the dormancy in P. persica, a factorial experiment was conducted based on a completely randomized design with four replications at the seed technology laboratory of Aburaihan Campus, University of Tehran, Iran, during 2018. In order to investigate the effect of after-ripening on breaking dormancy and germination, seeds were treated with four different treatments (control or distilled water, 100 mg gibberellin, melatonin at 50 and 100 µM concentrations).  After collecting seeds, the germination test was carried out at different temperatures (5, 10, 20 and 30°C), and the percentage and seed germination rate were recorded until 26 days. The result of this experiment showed that, fresh seeds had conditional dormancy and germinated in a narrow range of temperature conditions. The lower and upper temperature limits for fresh seeds were 5 and 20°C, respectively. The application of after-ripening and gibberellic treatments resulted in increasing germination percentage and temperature range. Among treatments, after-ripened seeds and those treated with gibberellic had the highest germination percentage while control and 50 mg melatonin had the lowest.