Cd胁迫对大豆各发育阶段生长及生理指标的影响

采用土壤盆栽试验方法,研究了不同浓度Cd胁迫下,大豆幼苗期、花荚期和成熟期植株的生长及叶片叶绿素含量、超氧化物歧化酶(SOD)活性、过氧化物酶(POD)活性和丙二醛(MDA)含量的变化.结果表明,大豆植株的生长在3个生长期均表现为低浓度Cd(￡0.50mg/kg)下的刺激效应和高浓度Cd(31.00mg/kg)下的抑制效应;随着Cd胁迫浓度的累积,大豆生长整体上受到抑制.在幼苗期,大豆植株的叶绿素含量下降、SOD活性受到抑制、POD活性迅速激活,共同缓解Cd毒性;在花荚期,大豆植株的防御系统得到有效激发,保护性酶POD、SOD的活性急剧升高,叶绿素含量呈上升趋势;在成熟期,因为长时间的Cd毒害,尤其是Cd浓度较高的情况下,大豆植株的SOD、POD活性和叶绿素含量急剧下降.在Cd胁迫下,大豆植株的生长发育以及生理生化指标在大豆的3个生长期的变化模式差异显著,且大豆植株的生物量和株高与SOD活性在整个生长期均表现出显著的相关性.

Effects of Cd stress on physiological and ecological indicators and their differences of soybean plants at different growth stages

A pot experiment was conducted to study effects of different Cd concentrations on growth of soybean plants, (Glycine max), and changes of chlorophyll contents, SOD (superoxide dismutase) activities, POD (peroxidase) activities and MDA (malondialdehyde) contents in the leaves of this plant at seedling stage, flowering-poding stage, and mature stage. Growth of soybean plants at three growth stages showed that the stimulating effects at low Cd concentrations (￡0.50mg/kg) and the inhibitory effects at high Cd concentrations(31.00mg/kg) under Cd stress; however, growth of plants was inhibited with increase in Cd concentrations. At the seedling stage, chlorophyll contents and SOD activities decreased obviously, POD activities increased rapidly, and these processes relieved Cd phyto-toxicity. At the flowering-poding stage, the antioxidant defense systems inside soybean plants were excited effectively by Cd stress; resulting in increases of POD and SOD activities rapidly with chlorophyll contents increasing. At the mature stage, SOD and POD activities and chlorophyll contents of soybean plants decreased sharply due to a long-term toxicity of Cd, especially under Cd stress with high concentrations. Changes in physiological indicators of soybean plants at seedling stage, flowering-poding stage, and mature stage indicated complete different modes with increase in Cd concentrations at three stages. Growth indicators (biomass and height of plants) of the plants were remarkably correlated to SOD activities in the whole growth period.