The Effects of NaCl Stress on Germination and Early Vegetative Growth in Floricultural Asteraceae Plants

Abstract

The effects of NaCl stress on germination and early vegetative growth of 20 floricultural Asteraceae species and a wild halophyte species, sea aster (Aster tripolium L., Asteraceae) were studied to evaluate the possibility of selecting salt-tolerant species. Cluster analysis with the germination percentages relative to non-salinized control on the 10th day after sowing in 50 to 300 mM NaCl classified safflower (Carthamus tinctorius L. 'Roundish Leaf') as the most salt-tolerant. Although the germination percentage of sea aster decreased as salinity increased, its ability to germinate at 300 mM NaCl was next to that of safflower. To evaluate salt tolerance during the early vegetative growth of three species, sea aster, safflower, and Chrysanthemum paludosum Poir., plants were grown hydroponically at 25 and 50 mM NaCl for safflower and C. paludosum and at 150 and 300 mM NaCl for sea aster. Sea aster was much more tolerant of high salinity than were the other two species, and C. paludosum was more tolerant than was safflower. In conclusion, these three species differed in their sensitivities to salinity between germination and early vegetative growth. Therefore, selecting for salt-tolerant species is difficult because tolerance is genetically determined at the germination stage.