Germination improvement and α-amylase and β-1,3-glucanase activity in dormant and non- dormant seeds of Oregano (Origanum vulgare)

Oregano plays a primary role among temperate culinary herbs in world trade. It is native of Southern Europe and is one of the most popular herbs in Mediterranean cooking. The germination response of this species to various germination improvement treatments including mechanical, physical and chemical scarification, were studied. Mechanical and chemical scarification of seed coat improved seed germination parameters and suggesting that O. vulgare seeds have an exogenous dormancy. Moreover, seed germination of oregano affected by other treatments such as moist chilling and chemicals, and proposing that oregano seeds also have endogenous dormancy. Standard germination test showed that germination percentage of untreated seeds is 25.8% while after chilling treatment at 4 C for 7 days germination percentage reached to 39%. Soaking seeds in 100 ppm of GA3 for 36 h resulted in 48% germination. The highest value of germination parameters detected by soaking seeds in -10 bar polyethylene glycol solution at 20 C for 72 h. Total germination percentage reached to 60% in this treatment. Combination of chilling and PEG improved seed germination significantly, but was not as effective as PEG solely. Enzyme activity of alpha-amylase and beta-1,3-glucanase in germinating seeds at 12 h after start of imbibition were assayed. Dormant seeds showed lower enzyme activity and enzyme activity in treated seeds increased significantly.