Sea-level rising derived from hurricanes frequently brings salt stress in combination with soil flooding, and disrupts wetland forests consisting of glycophytic woody plants. We investigated effects of rapid salt stress in combination with flooding on growth, photosynthetic activity and stem anatomy of T. distichum seedlings that dominant species in wetland forests.

Experiments were carried out from July 15 to September 15, 2006, using 2-year-old T. distichum seedlings in nursery of Tottori University. The seedlings were submerged with water having three different salt concentrations: 0 ppm, 4000 ppm, and 8000 ppm. All seedlings in each treatment were submerged totally in one tank (52 × 65 × 50 cm). As control, 7 seedlings were not submerged, watered daily and well drained. Replication in each treatment was 7 seedlings. The submergence treatments were continued for 7 days. Then, the submerged seedlings were pulled out from water and flooded with tap water at the soil surface.

All T. distichum seedlings survived total submergence with saline water in every salt concentration. However, the total submergence with/without salt temporally inhibited shoot elongation and stem growth of T. distichum seedlings. On the 7th day after submergence treatment, photosynthetic rates and stomatal conductance decreased. Then, the seedlings submerged with 8000 ppm NaCl shed all leaves and showed dieback phenomena.