Artificial seed germination and seedling production of Zostera marina L. by salinity manipulation

Vast declines in Zostera marina seagrass beds demand effective methods of rehabilitation. In this study, we developed a practical method by reducing salinity to induce seed germination followed with recovering salinity to facilitate seedling production of Z. marina. The results showed that Z. marina seeds collected from natural seawater (salinity 30) were induced to germinate at reduced salinities. Percent germination (GR) was higher and mean-time-to-germinate (MTG) was shorter at lower salinities. The highest GR and shortest MTG occurred at salinity 0 (deionized freshwater). After germination in freshwater, seeds could develop into seedlings at salinities 5-30 and continue the growth. Viability or development of germinated seeds was not significantly different during the 40 d of post-germination incubation at salinities 5-15 after 1-20 d of germination in freshwater. However, during the process of translating germinated seeds from salinity 0 and 5 to salinity 30, reducing the gradients of post-germination acclimation facilitated more seeds forming seedlings in less time. On average, after 60 d of static incubation, including 20 d in freshwater for germination followed with immediate shift to salinity 5 and increasing to salinity 30 at increment of 5 every two days until cultivation at constant salinity 30, 33% of Z. marina seeds produced healthy seedlings. The results indicate that the salinity-manipulation based method of artificial germination and seedling production is practical and effective in supporting rehabilitation of Z. marina bed.