The Role of Seed Dormancy Breaking Treatments on Germination and Alpha-Amylase and Beta 1,3-Glucanase Activity in Different Ecotypes of Origanum vulgare

Seed dormancy is a temporary failure of a viable seed to germinate. Various methods are used for breaking seed dormancy, depending on plant species and type of dormancy. Three seed populations originated from Esfahan, Semnan and Fars provinces were exposed to different seed dormancy breaking treatments such as mechanical and chemical scarification, humid chilling, GA3 and polyethylenglycol 6000 in order to break dormancy and improve seed germination. Unlike Semnan and Fars populations, Isfahan population did not show a significant positive reaction to treatments. Applying polyethyleneglycol solution of -10 bar for Semnan population and combination of moist chilling and polyethyleneglycol solution for Fars population resulted in the highest germination parameters. Germination percentage reached to 47.97% in Semnan and 64% in Fars population and mean germination time reached to 1.55 and 2.26 days, respectively. Activity of α- amylase and β-1,3-glucanase enzymes in seeds of oregano showed that non-dormant seeds exhibited significantly higher activity than dormant seeds. Different responses of oregano populations to applied treatments showed that intensity of dormancy is related to climate and origin of seeds and differs considerably among populations.