Seed Germination Strategies in Salicornia perennans Willd. subsp. perennans: The Role of Salinity, Seed Morphology, and Ecotype

Irene Ventura ¹, Mario Fontana ¹, Tiziana Lombardi ¹

University of Pisa ¹

Halophytes are natural salt-tolerant plants, which have evolved a variety of physiological and morphological adaptations to survive in saline environments. The mechanisms of salinity tolerance vary among halophyte species but typically include efficient ion regulation, osmotic adjustment, succulence and the sequestration of excess salts in vacuoles to prevent ion toxicity. Halophytes lives and complete their live cycle in habitats, such as salt marshes, inland deserts, salt flats and steppes, where soil are characterized by high sodium chloride content, even higher than seawater. In these habitats, soil surface becomes more saline due to rapid evaporation of water, particularly, during the summer. The success of halophyte populations in these habitats depends on the germination response of seeds, one of the most critical stages in life cycle of halophytes in arid and semi-arid regions. In these regions seed germination usually occurs after the rainy season, which reduced soil salinity surface. Seed germination can be influenced by several factor such as salinity, light, temperature, seed morphotype, but the knowledges about germination of halophytes are still poor. For this work, the germination of Salicornia perennans Willd. subsp. perennans seeds, an annual wild halophyte, was investigated to evaluate the effects of three variables and their interaction on germination parameters: salinity levels, seed morphology, ecotype. Two local ecotypes of S. perennans were selected from salt marshes in Central Italy, Tuscany, and two seed morphotypes—large and small—were separated for the analysis. The experiment exposed seeds to five different salinity levels (0, 88, 176, 350, and 532 mM NaCl), in controlled condition of light and temperature, to assess their impact on germination parameters, including germination percentage (GP), germination index (GI), and time to 50% germination (T50). The results showed that salinity significantly affects the germination percentage of both ecotypes. Higher salinity levels led to a marked decrease in the number of seeds that successfully germinated, according to the literature and the ecological growth conditions of this species. Interestingly, while no significant differences were found in germination rates between the two ecotypes, seed morphology emerged as a critical factor. Larger seeds exhibited a higher germination percentage than smaller seeds, regardless of salt concentration, suggesting that seed size may confer a competitive advantage in germination success under saline stress. These findings align with broader trends observed in other halophyte species, such as Soda inermis Fourr., which also exhibit reduced germination under increasing salinity due to osmotic stress and ion toxicity. The ability of halophytes to tolerate such conditions is an adaptive advantage in saline environments, but extreme salinity levels may still limit germination success. Additionally, these results also demonstrate how seed morphology plays a key role in the germination of this species. the seeds morphology these findings underscore the importance of salinity as a key determinant of germination in S. perennans, while also highlighting the potential influence of seed morphology. Understanding these dynamics is crucial for the conservation and management of saline habitats, as well as for optimizing the cultivation of S. perennans in saline agricultural systems.

Main author career stage: PhD student

Contribution type: Talk

First choice session: 2. Ecology

Second choice session: 3. Biodiversity and global change