The wheat of "Xihan 1" is employed to study changes of seed germination, seedling growth and physiological properties in response to Cd(NO3)2 stress. Low concentrations of Cd2+ promote seed germination while high concentrations inhibite. The length, fresh and dry weight and relative water content of root and shoot decreases remarkably under each Cd2+ concentration in comparison with the control; meanwhile, high concentrations of Cd2+ inhibite the growth of root cell elongation and induce lipid peroxidation. Chlorophyll a content decreases with the increase of Cd2+ concentration, but total chlorophyll reduces significantly only at 0. 6 mmol·L-1 of Cd2+. Analysis of antioxidant enzymes shows significant elevations in the activities of CAT, POD and APX in the leaves of "Xihan 1" wheat exposed to Cd2+ stress. In addition, H2O2 content of wheat leaves reduces observably at 0. 2 mmol·L-1 of Cd2+ , but MDA content in leaves does not show remarkable change under Cd2+ stress. In conclusion, Cd2+ stress inhibites the growth of wheat seedlings, cell elongation inhibition and strong oxidative damage in root tip may be associated with Cd-inhibitory effect on root growth in wheat seedlings. Additionally, increased activities of antioxidant enzymes in wheat leaves may be involved in scavenging H2O2 generation in response to Cd2+ treatment.%以“西旱一号”小麦为材料,研究了镉胁迫对小麦种子萌发、幼苗生长以及丙二醛含量、抗氧化酶活性等的影响.结果显示,低浓度Cd2+处理促进种子萌发,高浓度抑制萌发；小麦根和茎的长度、鲜重、干重和相对含水量在Cd2+处理下较对照均显著降低；高浓度Cd2处理抑制根细胞伸长生长,诱导膜脂过氧化.小麦叶片叶绿素a含量随Cd2+处理浓度的升高而降低,叶绿素总量在Cd2+处理浓度达到0.6 mmol· L－时较对照显著降低.此外,Cd2+胁迫诱导“西旱一号”小麦叶片CAT、POD和APX活性升高,但不影响叶片中MDA含量,而H2 O2含量在0.2 mmol·L－1 Cd2+处理下显著降低.结果表明Cd2+胁迫抑制“西旱一号”幼苗的生长,根伸长区细胞伸长生长的抑制和膜脂过氧化程度的增强可能与镉抑制根生长有关;此外,小麦叶片在镉胁迫下可通过提高抗氧化酶的活性来清除H2O2的产生、降低膜脂过氧化损害.
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