Salt tolerance of salt marsh plants of Otago, New Zealand

Abstract

The salt tolerance of 31 species — 29 halophytes constituting a large proportion of the more important species in salt marshes of Otago, and 2 glycophytes — was examined in water culture. The effects of salinity on growth and survival were the main parameters measured. There were considerable differences between species; most could not grow in sea water (3.5% NaCl), although a small number could grow in hypersaline conditions of up to 7.5% NaCl. Some species had a salt requirement for maximum growth, the greatest being 1.5% NaCl, but most grew best in freshwater. No species required saline solutions to survive. In general, the salt tolerance of species decreased from the lower to the upper marsh, which generally parallels field salinities. There were, however, important differences between the shapes of the salt tolerance growth curves, these being related to habitat and, in particular, to the variability of salinity.

Keywords:

• salt tolerance
• halophytes
• salinity
• salt marsh
• Otago