seed dormancy-breaking and germination requirements of

dormancy breaking and germination requirements were investigated in seeds of ferula ovina and ferula gummosa. seeds of rather species were collected from north and eastern-north rangelands of iran. seeds of each of the species were subjected to different treatments including various levels of ga3, chilling and combination of ga3 and chilling (ga-chilling). in contrast to treated seeds, non-treated seeds did not germinate. germination of both species increased at higher concentration of ga3. in the case of ferula ovina the highest germination percentage was obtained when the seeds were treated with 1000 ppm ga-chilling with 76% of germination. for ferula gummosa seeds, the highest germination percentage was found when exposed to 1500 ppm ga-chilling with 53% germination. both species well responded to different periods of cold stratification (30/60 days), especially f. ovina with 36% and 55% germination, respectively. the results suggest that f. gummosa has deeper dormancy. for both species, germination rate was positively correlated with germination percentage. keywords: chilling; dormancy; ferula ovina; ferula gummosa; ga3; germination