Abstract: In order to investigate the adaptability and physiological characteristics of Amaranthus australis to Cd stress during germination and seedling stage,the effects of different Cd concentration (0,10,20,40 mg·kg^-1) on the seed germination,seedling growth and physiology were studied. Results showed that Cd stress had less effect on the seed germination rate,germination potential and germination index,but significantly reduced vigor index. The growth significantly declined along with the increasing Cd concentration,as indicated by the reduced length of radicle and germ,plant height as well as the declined dry biomass of above- and underground part,whereas had no significant changes in the radicle/germ ratio and root/shoot ratio. The leaf electrolyte leakage and malondialdehyde (MDA) content significantly increased and catalase (CAT) activity decreased with increasing the Cd concentration,while the superoxide dismutase (SOD) and peroxidase (POD) activity increased at the initial treatment and then decreased. The content of non-protein thiols (NPTs),phytochelatins (PCs),glutathione (GSH),above and underground part Cd content,translocation factor and bioaccumulation factor significantly enhanced with increasing the Cd concentration. Those results indicated that the increased NPTs,PCs and GSH contributed to the better Cd stress tolerance and the capability of Cd translocation and bioaccumulation in Amaranthus australis.

Key words: Amaranthus australis, Cadmium stress, Seed germination, Physiological characteristics, Translocation factor, Bioaccumulation factor

摘要： 为揭示南方苋(Amaranthus australis)萌发和幼苗期对镉胁迫的适应性及生理特征,研究了不同镉浓度(0,10,20,40 mg·kg^-1) 对其种子萌发、幼苗生长及生理特征的影响。结果表明:镉对南方苋种子的发芽率、发芽势和发芽指数影响不显著,但显著降低了活力指数;随着镉胁迫浓度的升高,生长量显著下降,表现为胚根和胚芽长度下降,株高降低,地上部和地下部干重减少,叶片电导率和丙二醛含量均显著增加,超氧化物歧化酶(Superoxide dismutase,SOD)和过氧化物酶(Peroxidase,POD)活性先升高后下降,过氧化氢酶(Catalase,CAT)活性显著下降,非蛋白巯基(Non-protein thiols,NPTs)、植物螯合肽(Phytochelatins,PCs)、谷胱甘肽(Glutathione,GSH)、地上和地下部镉含量以及转移系数和富集系数均显著升高。研究结果表明,南方苋具有较强的耐镉、镉转运和富集能力,并能通过提高细胞内的NPT,PCs和GSH等重金属络物来缓解镉对细胞的毒害作用。

关键词: 南方苋, 镉胁迫, 种子萌发, 生理特性, 转运系数, 富集系数