Testa imposed dormancy in Vallisneria americana seeds from the Mississippi Gulf Coast

In response to hurricane and oil-spill environmental impacts along the northern Gulf of Mexico, coastal and marine habitat restoration has become a priority. In particular, restoration of submerged aquatic plants is vital for ecosystem health. To facilitate restoration, developing propagation protocols for Gulf coast plants is necessary, but challenging due to the lack of information on many species. Previous seed germination research of Vallisneria americana, a submerged aquatic species with declining abundance in coastal habitats, from northern latitudinal populations reported germination percentages between 80-90%. Germination experiments using Mississippi Gulf coast plants revealed unexpected outcomes. Less than 8% germination occurred when seeds were germinated in a 16 hr photoperiod or 24 hr dark period at 10, 20, 30 or 40 degrees C. To enhance germination, cold stratification and gibberellic acid soak treatments were conducted, but germination was below 10%. A subsequent seed scarification experiment was conducted that resulted in 90% germination when incubated at 30 degrees C. In addition, an imbibition experiment revealed that both scarified and non-scarified seeds imbibed water. Due to this imbibition, V. americana seeds used in this study were considered to be physiologically dormant. Refining existing seed-based propagation protocols is recommended to ensure the success of revegetation in restoration projects.