Factors controlling seed germination of the Iberian critically endangered Pseudomisopates (Antirrhinaceae)

Many seeds are dormant when shed from the mother plant. This unique characteristic of plants poses challenges in conservation and many different treatments have traditionally been used to break dormancy. When germination only occurs under certain circumstances, recruitment may be insufficient and the viability of plant populations may be threatened. A marked dormancy was previously identified in the Iberian critically endangered species Pseudomisopates rivas-martinezii. The present study aimed to determine the magnitude of dormancy by estimating seed viability under different germination treatments: heat, ash, stratification, gibberellin addition, and darkness. Our results indicate that there were significant differences in viability across plant populations and treatments. Maximum seed germination was obtained under ash addition, although cold stratification alone gave a considerable enhancement. However, gibberellic acid did not improve germination and darkness had a diminishing effect. In conclusion, a cold period is required for the species to germinate, coupled with the effects of fire: (1) ash, (2) vegetation clearings, and (3) resprouting, which are major factors triggering seed germination. Although these conditions are widely found in the field, we hypothesize that a more dramatic situation may have tackled this species before the increase of human-mediated fires in the past millennia.