关键词: 甜高粱, 温度, 盐胁迫, 种子萌发, 抗氧化物酶活性

Abstract: In order to investigate the effects of temperature, salt stress and their interaction on seed germination and seedling growth of sweet sorghum, ‘Liaotian 1’ was selected as material; treatments of five variable temperature including 15/5, 20/10, 25/15, 30/20 and 35/25 ℃, and five NaCl concentrations including 0, 50, 100, 200 and 300 mmol·L-1 were set up; the seed germination indexes, early growth and antioxidant enzyme activities of sweet sorghum seedlings under different treatments were investigated. The results showed that under the same temperature, high concentration of NaCl significantly inhibited seed germination of sweet sorghum. The residual dry weight of seeds increased with the increase of NaCl concentration, while the other germination indexes and seedling transformation indexes generally decreased with the increase of NaCl concentration. Under treatments with the same NaCl concentration, temperature had a significant effect on the seed germination and seedling growth of sweet sorghum. The seed germination indexes and seedling transformation indexes (except for seed residual dry weight) of sweet sorghum increased first and then decreased with the increase of temperature. Under the condition of low temperature (≤20/10 ℃), the antioxidant enzymes activity showed a decrease trend with the increase of NaCl concentration. However under the condition of high temperature (>25/15 ℃), the enzyme activities showed a trend of rise first and then decrease with the increase of NaCl concentration. Two-factor ANOVA analysis show that salinity, temperature and their interaction all significantly influence the sweet sorghum seed germination, seedling growth and seedling antioxidant enzyme activity. Comparatively, the influences of salt on seed germination rate, vigor index, seedling transformation index (except for seed residual dry weight), superoxide dismutase (SOD), peroxidase (POD), catalase(CAT) activity were more than those of temperature, however the influence of temperature on germination potential, germination index, seed residual dry weight, ascorbate peroxidase activity were much more than those of salt. It was suggested that the optimal temperature for sweet sorghum seed germination was 30/20 ℃ under NaCl stress.

Key words: sweet sorghum, temperature, salt stress, seed germination, antioxidant enzyme activity