Physiological differences of different rice materials in response to salt stress at seedling stage

In order to investigate physiological characteristics of salt-tolerance rice HD96-1 at seedling stage, indica rice HD96-1 (strong salt-tolerant) and 93-11 (weak salt-tolerant) were used as experimental materials in this study. Three NaCl concentrations (0, 60, 120 mmol·L-1) was set to treat 3-leaf rice seedlings for 7 d. The growth, physiological and biochemical indexes of two rice cultivars were measured and analyzed. The results were as follows: (1) The plant height and the pseudostem width of two cultivars decreased, and the root-shoot ratio increased under salt stress; compared with 93-11, the decrease of plant height and pseudostem width of HD96-1 was lower, and the increase of root-shoot ratio was higher under salt stress; in addition, the dry weight of aboveground and root of HD96-1 increased under salt stress, while that of 93-11 decreased. (2) The malonaldehyde (MDA), superoxide anion (O2-) and hydrogen peroxide (H2O2) contents in rice seedlings increased after salt stress, of which the increase of HD96-1 was lower than that of 93-11. (3) The activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX), the contents of ascorbic acid (AsA), glutathione (GSH), proline, soluble sugar and soluble protein in rice seedlings were increased under salt stress, of which the increase of HD96-1 was higher than that of 93-11. In conclusion, the physiological mechanisms of two rice seedlings responding to salt stress are similar, but the difference is that HD96-1 with strong salt-tolerance is stronger antioxidant and osmotic regulation ability than 93-11 in response to salt stress, so that growth and development of HD96-1 are less inhibited than 93-11.