镉胁迫对矮生四季豆种子萌发和幼苗生长发育的影响

Effects of Cadmium Stress on Seed Germination and Seedling Growth of Dwarf Beans

为比较系统地探讨Cd2+的生物毒性,作者以水培法研究了不同浓度的Cd2+溶液对四季豆种子萌发和幼苗生长发育过程中植物外部生长指标及内部生理生化变化的影响。结果表明:当Cd2+浓度较低时,Cd2+对种子萌发及幼苗生长发育毒害作用较小,一定浓度范围内(0.05～0.5mg/L)还有促生作用,高浓度Cd2+(5～100mg/L)能严重抑制四季豆幼苗根及下胚轴的生长;Cd2+胁迫对四季豆幼苗体内过氧化物酶(POD),超氧化物歧化酶(SOD),过氧化氢酶(CAT)活性存在低浓度激活和高浓度抑制的效应,且同一浓度的Cd2+对四季豆幼苗POD、CAT活性的抑制作用表现为根系大于下胚轴,Cd2+浓度>0.5mg/L时,根系SOD活性大于下胚轴中的活性;Cd2+胁迫下,四季豆下胚轴和根的丙二醛(MDA)含量增加,且根部含量大于下胚轴的量。Cd2+对矮生四季豆种苗生长发育的影响因Cd2+浓度及幼苗部位的不同而异。

In order to explore the biological toxicity of Cd^2＋ more systematically, the effects of Cd^2＋ on the external and internal physiological and biochemical changes in the process of dwarf beans seed germination and seedling growth were studied with hydroponic culture experiments. The results showed that when the concentration of Cd^2＋ at low level, the effects of Cd^2＋ on the seed germination and seedling growth were not signifi cant. Seeds germination were activated at a certain extent when Cd^2＋ concentration ranged from 0.05mg/L to 0.5 mg/L concentrations. The roots and Hypocotyls of seedling exhibited a significant decrease in growth at higher level of Cd^2＋ concentrations （5-100mg/L）.The activities of peroxidase （POD）, superoxide dismutase （SOD）, catalase （CAT） could be enhanced at low Cd^2＋concentrations but inhibited at higher concentration. The activities of POD, CAT were more inhibited in roots than in Hypocotyls at the same Cd^2＋ concentrations, while that of SOD was higher in roots than in Hypocotyls when the concentration of Cd^2＋ was more than 0.5mg/L. The malondialdehyde （MDA） contents were continuously increased with Cadmium exposure in both roots and Hypocotyls. The effects of Cd^2＋on the dwarf beans＇ growth were varied with the concentration of Cd^2＋ and the parts of plants.