镉胁迫对小型西瓜幼苗生长及脂膜过氧化的影响

Effect of Cadmium Stress on Growth and Membrane- lipid Peroxidation of Small Watermelon Seedlings

以小型西瓜为材料,研究了土壤中不同浓度镉对其幼苗生长及脂膜过氧化的影响。结果表明:Cd2+浓度小于15mg.kg-1时,对根系的生长有一定的促进作用;当浓度大于45mg.kg-1时,开始对根系的生长有明显的抑制作用。相关分析表明:土壤中Cd2+浓度与西瓜幼苗叶片叶绿素总量间极限著负相关。H2O2含量、MDA含量随着土壤中Cd2+浓度的升高而增加,且与Cd2+浓度间极限著正相关。在低浓度Cd2+胁迫条件下,SOD、POD活性变化不显著,而CAT活性变化显著,且CAT活性变化与H2O2含量、MDA含量极显著负相关。镉胁迫引起保护酶活性降低,是引发脂膜过氧化进而导致西瓜幼苗生长受到影响的重要原因。

Small watermelon seedlings growth and membrane lipid peroxidation were studied under Cadmium stress which was different concentration in the soil. The results showed that the root growth was improved by Cadmium concentration which was less than 15mg·kg^-1 and it was reduced markably when it was more than 45mg· kg^-l.The negative correlation was significant at P 〈0.01 level between Cd^2＋ coneentration in the soil and total chlorophyll content of the watermelon leaves, and the positive correlation was significant at P 〈 0.01 level between Cd^2＋ concentration in the soil and H2O2 content and MDA content. As well as the positive correlation was significant at P 〈 0.01 level between CAT activity and H2O2 content and MDA content. With the Cd^2＋ concentration increasing in the soil, H2O2 content and MDA content of watermelon leaves were increasing. SOD and POD activity changed similarly, but CAT activity changed differently under lower Cd^2＋ concentration stress. It was an important factor that antioxidative enzymes activity was reduced lead to membrane lipid peroxidation taken place and growth suffered.