Dormant or non-dormant seeds: different germination strategies used by common aquatic plants in Mediterranean temporary ponds

Abstract In temporary ponds, the re-establishment of aquatic plant assemblages after desiccation mainly depends on seed germination. We analysed the seed germination dynamics of common aquatic plants in Mediterranean temporary ponds to evaluate how the ponds’ dry phase could affect the persistence of plant populations. We collected seeds of Callitriche brutia Petagna, Ranunculus peltatus Schrank, and Myriophyllum alterniflorum DC. For each species, one half of the seeds were used in germination trials one day after collection, and the other half were kept in a dry after ripening treatment for two months before being used in germination trials. We placed the seeds in inundated wells kept at 20 °C and 12L:12D; we recorded the number of germinated seeds per well and the time to germination. For C. brutia , both treatments led to a high percentage of germination. For R. peltatus and M. alterniflorum , only the dry after ripening treatment led to a high percentage of germination. Most C. brutia seeds are non-dormant; thus, only its late-produced seeds would germinate in subsequent germination cycles. In contrast, most R. peltatus and M. alterniflorum seeds seem to go through a dormancy period, which is broken during the dry phase, allowing germination during future inundation cycles.