The morphophysiological dormancy of Ferula ovina seeds is alleviated by low temperature and hydrogen peroxide

Ferula ovina is a perennial Apiaceae with great medicinal and economic value. This study was conducted to better understand the dormancy and germination behaviour of its seeds. Experiments included temperature requirements for both embryo growth and germination under field and laboratory conditions, the effects of warm stratification, gibberellic acid (GA(3)), dry after-ripening, exogenous hydrogen peroxide (H2O2) and diphenyleneiodonium (DPI) on dormancy, localizing the accumulation of superoxide (O-2(-)) and measuring endogenous contents of H2O2 in embryos during cold and warm stratification. Embryos were underdeveloped and did not germinate within one month at temperatures higher than 10 degrees C. Among all treatments, cold stratification and exogenous H2O2 could break dormancy. However, the application of DPI reduced growth and the germination of the embryo at 3 degrees C. During cold stratification, the embryonic axes elongated more than the cotyledons, which coincided with earlier production of O-2(-) in the axes. Only these embryos could eventually complete growth and germinate. Moreover, such asymmetric growth between the axes and cotyledons was also observed when seeds were treated with exogenous H2O2. On the other hand, both axes and cotyledons displayed the same growth over treatments with warm stratification and DPI. Overall, seeds of F. ovina exhibit the characteristics of deep complex morphophysiological dormancy. Moreover, the embryos solely require cold to complete growth and to germinate, and this process seems to be mediated by reactive oxygen species. Under natural conditions, seeds germinate during winter in cold soil, and shoots emerge in spring.