Starving for oxygen: the effect of hypoxia on seed germination and secondary dormancy induction in Mediterranean temporary ponds plant species

Abstract

Mediterranean temporary ponds (MTPs) are dynamic habitats where low levels of dissolved oxygen can significantly impact plant life. This study investigated the effect ofhypoxia and near-anoxia on seed germination and the induction of secondary dormancy in 14 plant species, characteristic of this habitat.• Imbibed seeds were subjected to various oxygen concentrations (0.1, 5, 10, or 21%O2), in both light and darkness. We also tested seed ability to recover germination bymoving them to aerobic conditions. We measured embryo growth after hypoxic treatments and during recovery in three species with morpho-physiological dormancy, ararely investigated response in this dormancy class.• Our findings revealed a wide range of species-specific responses. Hypoxia did notinhibit germination in half of the tested species in the light, while near-anoxiacompletely inhibited germination in all species. However, most seeds fully recoveredgermination ability once aerobic conditions were restored. Interestingly, hypoxia indarkness reduced or prevented germination in some species and specifically inducedsecondary dormancy in Juncus bufonius. Surprisingly, seeds of Bulliarda vaillantii losttheir light requirement for germination under hypoxia. In three Ranunculus specieswith morpho-physiological dormancy, hypoxia slowed embryo growth, which delayedgermination recovery.• This study reveals that MTPs species have evolved adaptations, ranging from toleranceto hypoxic conditions, to the ability to trigger secondary dormancy, which are crucialto surviving and reproducing in these unique environments. The results offer newinsights into the germination ecophysiology of MTPs species and their regenerationniche in temporary wetlands.