Abstract: Alfalfa seeds were primed with different concentrations (0,0.5,1.0,2.0,4.0 and 8.0 mmol·L^-1) of sodium selenite solutions for 0,3,6,9 and 12 h,to explore the effect of exogenous selenium priming on antioxidant capacity of the seeds. And then we analyzed the changes in germination percentage,malondialdehyde (MDA) contents,superoxide dismutase (SOD),peroxidase (POD),catalase (CAT) and aseorbate peroxidase (APX) activities. The results showed that germination percentage and antioxidant capacity of alfalfa seeds were closely related to the selenium concentration and its priming time. Germination percentage of alfalfa seeds was improved by priming with low concentration (0.5~1.0 mmol·L^-1) of sodium selenite,and their SOD,POD,CAT and APX activities were also increased,but their MDA content was decreased. However,the opposite results were found by priming with high concentration of sodium selenite. The best treatment was 0.5 mmol·L^-1 of sodium selenite solutions for 12 h in the production of selenium-rich alfalfa by seed priming.

Key words: Selenium, Seed priming, Antioxidant enzymes, Lipid peroxidation, Alfalfa

摘要： 为探索外源硒引发对紫花苜蓿(Medicago sativa)种子抗氧化性能的影响，本试验用不同浓度(0，0.5，1.0，2.0，4.0和8.0 mmol·L^-1)的亚硒酸钠溶液引发0，3，6，9和12 h后，分析其发芽率、丙二醛(malondialdehyde，MDA)含量、超氧化物歧化酶(superoxide dismutase，SOD)、过氧化物酶(peroxidase，POD)、过氧化氢酶(catalase，CAT)及抗坏血酸过氧化物酶(aseorbate peroxidase，APX)活性的变化规律。结果表明：硒引发对紫花苜蓿种子发芽率及其抗氧化能力的影响与其浓度和引发时间有密切关系；低浓度(0.5和1.0 mmol·L^-1)硒引发会提高紫花苜蓿种子的发芽率，增强其SOD，CAT，APX及POD活性，并降低其MDA含量，而高浓度硒引发则相反。浓度为0.5 mmol·L^-1的硒引发12 h可能是富硒紫花苜蓿生产的最佳处理。

关键词: 硒, 种子引发, 抗氧化酶, 脂质过氧化作用, 紫花苜蓿