【作者】 孙刚；

【导师】 金研铭；

【作者基本信息】 吉林农业大学 ， 园林植物与观赏园艺， 2013， 硕士

【摘要】 本研究采用盆栽的方法研究了Cd、Pb胁迫对千屈菜(Lythrum salicaria Linn)种子萌发、幼苗生长及生理生化的影响,探讨千屈菜对Cd、Pb耐受能力的大小,并分析这一园林植物是否为修复重金属污染的优良植物,从而为修复土壤污染和水污染的树种选择提供理论依据,并为镉的污染毒理研究与植物抗重金属胁迫机制等研究提供参考。经此次试验得出以下结论：1.种子发芽试验：低浓度Cd胁迫对千屈菜种子的发芽势、发芽率、发芽指数与活力指数的影响均不显著；当胁迫浓度高于50mg/L时,显著降低了种子的发芽率与发芽指数；当Cd浓度高达200mg/L时,千屈菜种子的活力指数极低,幼苗很可能死亡；低浓度镉胁迫对千屈菜种子根的伸长生长有促进作用,而高浓度镉胁迫对千屈菜种子根的生长有抑制作用。Pb胁迫对千屈菜种子也具有一定的影响,当Pb胁迫浓度≥100mg/L时,千屈菜种子的发芽率、发芽势、发芽指数和活力指数均显著降低；处理水平为500mg/L的千屈菜种子的发芽势、发芽指数与对照相比显著下降；且芽长随胁迫的加剧而减小。2. Cd, Pb胁迫对千屈菜幼苗外部形态的影响：低浓度的Cd、Pb对千屈菜幼苗的生长有促进作用,而高浓度胁迫对幼苗的生长有抑制作用。同时,发现镉胁迫后的植株根系也受到一定损害,且随Pb浓度的升高损害程度越发严重,表现为主根伸长生长受到不同程度的抑制、侧根稀少。3.Cd、Pb胁迫对千屈菜幼苗渗透调节物质的影响：Cd、Pb胁迫的千屈菜叶片脯氨酸含量明显高于对照。低浓度Cd、Pb胁迫可使植株叶片的可溶性糖含量升高,高浓度胁迫则使其含量降低。千屈菜叶片可溶性蛋白含量随Cd胁迫浓度的升高和时间的延长呈递增趋势。在Pb胁迫开始阶段可溶性蛋白含量随Pb浓度的增大而增大；而随着胁迫时间的延长,各处理水平的植株叶片可溶性蛋白含量逐渐下降。4.Cd、Pb胁迫对千屈菜幼苗保护酶系统的影响：低浓度的镉胁迫对千屈菜幼苗的SOD、POD活性有促进作用,且SOD变化比POD变化明显。低浓度Pb胁迫下的SOD活性总体呈上升趋势,但与对照相比差异不显著；而POD活性随Pb浓度的升高,呈先上升、后下降的趋势。5.Cd、Pb胁迫对千屈菜幼苗细胞膜的影响：随着Cd、Pb胁迫的加剧,千屈菜幼苗的相对电导率显著升高,说明细胞膜遭到一定程度的破坏。低浓Cd、Pb胁迫的相对电导率在一定时间内变化比较平稳,与对照相比差异不显著,表明千屈菜植株对Cd、Pb胁迫具有一定的耐受性。MDA含量随镉、铅胁迫浓度的提高与处理时间的延长逐渐增大。6.Cd、Pb胁迫对千屈菜幼苗叶绿素总含量的影响：千屈菜叶片的叶绿素总含量随Cd、Pb胁迫浓度的升高和处理时间的延长总体呈下降趋势。更多还原

【Abstract】 With gardening plant lythrum salicaria being cultured through flowerpot, this experiment makes a systematic study of the impact of Cd and Pd stress on such facets as the seed germination,and the physiology, biochemistry and growth of lythrum salicairia seedlings. It is also analyzed in the study whether lythrum salicairia is a fine plant easing heavy metal contamination, which will further provide theoretical foundation for the selection of the variety of trees to easing both soil and water pullotion. It can also provide reference for the study of pollution toxicology of Cd and the resistance mechanism to heavy metal contamination of plants. The following conclusions can be drawn from this experiment:1.The seed germination experiment manifests that low concentration of Cd stress has non-significant impact on germination rate, germination potential, germination index and vigor index. When Cd concentration is greater than or equal to50milligram per liter, the Cd stress reduces the germination rate and index significantly. When the concentration reaches200milligram per liter, the seed vigor index is so low that the seedlings are liable to death. Low concentration of Cd stress can advance the elongation and growth of the roots of lythrum salicaria seeds; while high concentration of Cd stress may suppress the growth of the roots. When the concentration of Pb stress is greater than or equal to100milligram per liter, there is a dramatically decrease in the germination rate and vigor index. When the concentration of Pb stress is500milligram per liter, the germination potential and germination index decrease distinctively compared to pure water. The germinal length decreases with the rising of stress concentration.2.This experiment reveals the impact of Cd and Pb stress on the osmotic adjustment substances of lythrum salicacia seedlings. Cd and Pb stress makes the proline content significantly higher than the comparison. Low concentration of Cd and Pb stress leads the soluble sugar content to a higher degree, and vice versa. The soluble protein of lythrum salicacia leaf is generally slow and incremental under various levels of treatment.3.It is also studied in the experiment that the impact of Cd and Pb stress on the enzymes of protective system of lythrum salicacia seedlings. Low concentration of Cd stress can promote SOD and POD activity of the seedlings, with a more apparent change of SOD than POD. SOD activity is on the rise under the stress of low Pb concentration, but not very significantly. However, with the rise of Pb concentration, POD activity obtains a momentum of ascendance and then decline. 4.The experiment studies as well the impact of Cd and Pb stress on the cell membrane of lythrum salicacia seedlings. The experimental results show that the relative conductivity of the seedlings rises dramatically with the intensification of Cd and Pb stress, which illustrates that the cell membrane is destroyed to a certain extent. However, if the relative conductivity of the level of Cd and Pb stress remains stable in a certain period of time, or the difference is not very significant, it is manifested that the plant is tolerant to Cd and Pb stress. With the elevation of Cd and Pb stress and the prolonging of treatment time, MDA content increases gradually.5.The impact of Cd and Pb stress on the photosynthesis of lythrum salicacia seedlings is also studied. Conclusions can be drew that the total content of chlorophyll of the leaf maintains a trend of declining with the increasing of Cd and Pb concentration and the treatment time, thus the chlorophyll is weakened. The external behavior includes a reduction of leaves, lesion of leaves and a shrink of leaf area.6.The experiment studies the impact of Cd and Pb stress on lythrum salicacia seedlings’ external forms. Low concentration of Cd and Pb stress plays a positive role in promoting the growth of seedlings, while high concentration functions the opposite. The experiment shows after removing the dirt, the roots are damaged as a result of Cd stress, and the degree of damage worsens with the rising of Cd concentration.更多还原