Growth and germination experiments were conducted on two plant species belonging to genus Artemisia, A. fukudo, a biennial salt marsh plant, and A. stelleriana, a perennial coastal hind-dune plant, to investigate factor(s) determining difference between their salt tolerance. Growth experiments revealed that salinity (100 and 300 mM NaCl) inhibited relative growth rate (RGR) in A. stelleriana significantly but not in A. fukudo. These specific differences in salt-tolerance were attributed mainly to differential responses of net assimilation rate (NAR). That is, the reduction in RGR in A. stelleriana was mainly due to the reduction in NAR, whereas no significant reduction in NAR was observed in A. fukudo. The reduction in RGR in A. stelleriana in the salt treatment was also attributable to the reduced leaf area ratio (LAR). Specific leaf area (SLA) in the two species decreased in the 300 mM treatment. The decrease in SLA in A. fukudo was, however, compensated partly by the increase in leaf weight ratio (LWR). Germination experiments also showed that A. fukudo has higher salt tolerance than A. stelleriana. These results are consistent with the differences in the salinity conditions between the native habitats of the two species.

Key words: germination; growth analysis; halophytes; relative growth rate; salt-tolerance.