Abstract:

In this study， we determined the effects of salt stress on the seed germination， seedling growth， and physiological characteristics of carnation （Dianthus chinensis）. The results showed that 50 mmol·L^–1 NaCl had no significant effect on the germination of carnation seeds， while NaCl at 100， 150， 200 and 250 mmol·L^–1 significantly inhibited the germination of carnation seeds， and the inhibition became stronger with increasing NaCl concentrations. The stem diameter was significantly increased in the 50， 100 and 150 mmol·L^–1 NaCl treatments， unaffected in the 200 mmol·L^–1 treatment， and significantly decreased in the 250 mmol·L^–1 NaCl treatment， compared with the control. The leaf length， leaf width， root length， and dry weight per plant were not affected by NaCl at 50 mmol·L^–1， but were significantly inhibited by NaCl at higher concentrations. The contents of free proline， soluble protein， and malondialdehyde increased with increasing NaCl concentrations. The contents of soluble sugars and hydrogen peroxide and the activity of peroxidase first increased and then decreased with increasing NaCl concentrations. The highest soluble sugars content was in the 100 mmol·L^–1 NaCl treatment， and the highest hydrogen peroxide content and peroxidase activity were in the 150 mmol·L^–1 NaCl treatment. All the NaCl treatments significantly inhibited superoxide dismutase activity. Our results indicated that D. chinensis is partially salt tolerant. It can germinate and grow normally under 50 mmol·L^–1 NaCl stress， but NaCl at higher concentrations inhibits its seed germination and seedling growth.

Key words: salt stress, Dianthus chinensis, seed, germination characteristics, seedling growth, physiological characteristics