Impacts of smoke treatments on germination of cold-stratified seeds in medicinal-rangeland plant Ferula ovina (Apiaceae)

Ferula ovina (Apiaceae) is a perennial rangeland medicinal plant found in the mountainous area of Iran. Due to seed dormancy at maturity and dispersal as well as climate changes in the area, the population of this species has been reduced. Accordingly, in the present study the effects of smoke treatments (aerosol smoke and two methods of smoke extract preparation) on seed germination characteristics of this plant were investigated. Treatments with smoke from the burning of wheat straw were applied after varying periods of cold stratification. Cold stratification changed the level of seed dormancy and increased the rate and percentage of seed germination. Furthermore, aerosol smoke applied after cold stratification significantly increased the rate and percentage of seed germination. The greatest increase (20%) in germination percentage compare to control was observed in seeds that had been cold-stratified for 7 days and exposed to aerosol smoke for two minutes. Smoke extracts with concentrations (1: 1000 - 1: 100 v/v) prepared by the two methods also increased the germination of cold stratified seeds. Hence, the maximum percentage of germination (80%) was obtained for seeds cold stratified for 30 days and treated with 1:1000 dilution of charred straw solution. However, undiluted smoke water decreased the percentage of seed germination after 0 and 30 days of cold stratification and led to abnormal seedling development. In general, the results of this study demonstrated that smoke treatments improve seed germination of cold stratified Ferula ovina seeds.