Dormancy classes and seed germination niches in two Ranunculus species from Mediterranean temporary ponds

Mediterranean temporary ponds (MTPs) are small water bodies characterised by alternating phases of drought and flooding. They harbour a unique flora conditioned by an annual life cycle. Thus, the understanding of seed germination ecophysiology in the MTPs plant communities is crucial to their conservation. Ranunculus lateriflorus and Ranunculus ophioglossifolius are two species commonly occurring in MTPs, whose germination biology remains elusive. In the present study, we characterised their germination niche and defined their seed dormancy type by examining the effect of temperature, light and dry after-ripening. Fresh seeds germinated preferably in the presence of light. Dry after-ripening widened the temperature range and fastened the completion of germination, highlighting the presence of a conditional physiological dormancy. Type 1 non-deep physiological dormancy allows R. lateriflorus to avoid seed germination upon dispersal while Type 3 non-deep physiological of R. ophioglossifolius is indicative of an adaptation to more temperate climate. Both species possess differentiated but underdeveloped embryos whose growth begin once the physiological component of seed dormancy is broken. Even though both species show non-deep morphophysiological dormancy, their different germination strategies describe specific germination niches within the MTPs' habitat.