镉处理对乌麦种子萌发幼苗生长及抗氧化酶的影响

采用室内培养分析测试方法，研究了不同浓度外源镉处理对乌麦及小麦种子萌发、幼苗生长状况及抗氧化酶系统的影响。结果表明，(1)镉处理对乌麦及小麦的种子萌发具有低浓度下的激活效应和高浓度下的抑制效应；对幼苗苗长具有胁迫初期低浓度下的激活效应，随着胁迫时间的延长，转而表现为抑制效应；对幼苗根长具有极显著的抑制效应。幼苗的生长状况比种子萌发更能体现镉毒性的大小，尤其根长的变化是一个重要的指示植物受重金属毒性影响的指标。(2)镉处理对乌麦及小麦幼苗的过氧化物酶(POD)具有激活效应，且随着镉浓度的增加激活效应逐渐增强；对过氧化氢酶(CAT)存在胁迫初期的激活效应，随着胁迫时间的延长，转而表现为抑制效应，且随着镉浓度的增加抑制效应逐渐增强。对超氧化物歧化酶(SOD)存在胁迫初期低浓度下的激活效应，随着镉浓度的增加及胁迫时间的延长，转而表现为抑制效应，且随着镉浓度的增加抑制效应逐渐增强。三种抗氧化酶均可被激活以抵抗镉的胁迫，但过氧化物酶(POD)起关键作用。

Effects of Cadmium on Seed Germination,Growth of Seedling and Antioxidant Enzymes of Rye and Wheat

Effects of seed germination,seedl ing growth and antioxidant enzymes o f rye and wheat under cadmiumstress was studied.The results showed that(1)Cd 2+ is capable of stimulating the seed ge rmination at lower concentrations a nd inhibiting the seed ger-mination at higher concentrations.At the initial stage,Cd 2+ stimulated the seedling length at lo wer concentrations,but with the extent of stress and increase of Cd 2+ concentration,the inhibition turn ed to restrained and the action incre ased gradually.And Cd 2+ inhibited plant root length remarkably.It has been found that seedling g rowth was more affected by Cd 2+ treatment than was the seed germination,while the root was the most sensitive to the Cd 2+ treatment.(2)Cd 2+ can stimulate POD activity and the ac tivity in-creased gradually with the increase of Cd 2+ concentrations.In terms of the stim ulation of the SOD and CAT activities,at the initial stage of stress the both activities were stimulated at lower concentrations,but with the extent of stress and increase of Cd 2+ concen-trations,the activities turned to r estrained and the effect increased g radually.It can be concluded that PO Dplays an important role in combating the stress from the heavy metal among the three antioxidant enzymes.