关键词: 蒙桑, 盐胁迫, 种子萌发, 幼苗生理

Abstract: In order to study the effects of salt stress on seed germination and seedling growth of Morus mongolica, the salt stress experiments on M. mongolica seeds and seedlings were carried out with 0, 20, 30, 50, 70, 100 mmol·L-1 NaCl solutions. The germination indexes of seeds and the physiological indexes of M. mongolica seedlings were detected to reflect the response characteristics of salt stress. The results showed that: ① the germination rate and germination index of M. mongolica decreased significantly with the increase of NaCl concentration; the radicle length and germ length were inhibited over 20 mmol·L-1, and the radicle growth rate was inhibited from 30 mmol·L-1. At the same time, the activity index and salt tolerance index showed a downward trend under salt stress conditions, and when the NaCl concentration was 20 mmol·L-1, both decreased to about 50% of the control. ② Correlation and regression analysis results of seed germination index, vigor index, seedling growth index and salt concentration showed that the salt tolerance thresholds of germination rate, vigor index, radicle length and radicle growth rate of M. mongolica seed were 2.55, 59.71, 2.42, 0.67 mmol·L-1, respectively. ③ With the increase of NaCl concentration, malondialdehyde (MDA) content, soluble protein (SP) content, free proline (Pro) content and relative conductivity were all observed significantly increased. Superoxide dismutase (SOD) activity decreased significantly at 50 mmol·L-1 NaCl concentration. Soluble sugar (SS) content showed a tendency of volatility. Therefore, under salt stress, seed germination and seedling growth of M. mongolica were inhibited to some extent, but the seedlings could adapt to the adversity by regulating their own organic penetrating substances and improving the protective enzyme activity, showing strong salt tolerance. The present research provided a basic theory for the promotion of seedlings of M. mongolica in saline-alkali areas, and provided a scientific basis for the cultivation and protection of salt-tolerant plant resources and the reconstruction of plant populations in saline-alkali areas.

Key words: Morus mongolica, salt stress, seed germination, seedling physiology