A COMPARISON OF INDICATORS OF SUBLETHAL SALINITY STRESS IN THE SALT-MARSH GRASS, SPARTINA PATENS (AIT) MUHL

Wetland plant communities in coastal Louisiana are degrading, resultin g in the loss of live emergent vegetation and subsequent succession to open water. Saltwater intrusion has resulted from the construction of navigation canals through the marshes; the subsequent salinity increa se is one of the potential sources of sublethal stress on plants. Gree nhouse experiments were conducted on Spartina patens (Ait.) Muhl. to c ompare the usefulness of several indicators for the detection of salin ity stress. CO2 uptake, leaf expansion, proline concentration and live aboveground biomass displayed significant responses to the salinity l evels employed as treatments (0, 7, 14, 21 and 28 ppt.). CO2 exchange was the only indicator showing a significant response within 7 days of the initiation of treatments (measurements were made at 7, 14 and 42 days).