温度与NaCl处理对甜高粱种子萌发及幼苗抗氧化酶活性的影响

为探讨温度与盐胁迫及其交互作用对甜高粱种子萌发及幼苗生长的影响，以‘辽甜1号’甜高粱种子为试验材料，设置15/5、20/10、25/15、30/20和35/25 ℃共5个变温处理及0、50、100、200、300 mmol·L-1 5个NaCl浓度处理，研究不同处理的甜高粱种子萌发、早期幼苗生长及幼苗抗氧化酶活性的差异及规律。结果表明，相同温度条件下，高浓度NaCl处理显著抑制甜高粱的种子萌发，其种子残留干重随着NaCl浓度的增加呈升高趋势，其余萌发指标和种苗转化指标则随着NaCl浓度的增加呈降低趋势。相同浓度NaCl处理下，温度对甜高粱种子萌发和幼苗生长影响显著，其种子萌发指标、种苗转化指标（除种子残留干重）随着温度的上升均呈先升高后下降的趋势；低温（≤20/10 ℃）条件下，抗氧化酶活性均随着NaCl浓度的升高呈降低趋势，而高温（>25/15 ℃）条件下，随着NaCl浓度的升高，酶活性均呈先升高后下降的趋势。双因素方差分析显示，盐分、温度及二者互作均显著影响甜高粱种子的萌发和早期幼苗的抗氧化物酶活性，其中，盐分对种子发芽率、活力指数、种苗转化指标（除种子残留干重）、超氧化物歧化酶、过氧化物酶、过氧化氢酶活性的影响更大，而温度对发芽势、发芽指数、种子残留干重、抗坏血酸过氧化物酶活性的影响较大。在NaCl胁迫下，甜高粱种子萌发最适温度为30/20 ℃。

Effects of Temperature and NaCl on Seed Germination and Seedling Antioxidant Enzyme Activities of Sweet Sorghum

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.