| Resumo: |
The effects of different salinities on the germination of Spartina ciliata seeds were tested during 40 days in the laboratory, using six concentrations of NaCl (0,45, 80, 130, 170 and 215 mM) besides three concentrations of seawater (25,30 and 35‰). In addition, the survival and growth of seedlings were tested in five constant salinity regimes (0,45, 80 and 170 mM NaCl) as well as in five regimes of simulating seawater overwash. The results showed that seeds possed a high germination capacity over a wide range of salinities (0 to 215 mM NaCl). Although concentrations close to full-strength seawater completely inhibited seed germination, the transfer of the ungerminated seeds to freshwater immediately stimulated this. The effects of salinity on seedling growth showed that shoot height and root length were the variables most sensitive to salt stress. Frequent overwash with seawater significantly reduced the survival and growth of Spartina ciliata seedlings. The success in seed germination, survival, and growth of Spartina ciliata in salinities above those normally found in the natural environment could explain the species being distributed throughout salt-stressed foredune habitats in southern Brazil.
|
