芝麻苗期生长和生理特性对铜胁迫的响应

Response of Physiological and Ecological Characteristics to Cu Stress of Gingili in Seedling

采用水培试验方法,研究不同质量浓度外源Cu2+处理对苗期芝麻生长、叶绿素和丙二醛(MDA)含量、超氧化物歧化酶(SOD)活性和过氧化物酶(POD)活性的影响。结果显示,低质量浓度、短时间Cu2+胁迫对芝麻幼苗苗长有刺激效应,而高质量浓度、长时间Cu2+胁迫对其有抑制效应;Cu2+胁迫对幼苗根长有极显著的抑制效应(P<0.01),并在Cu2+质量浓度为1.0 mg.L-1时,开始使其发生退化;Cu2+胁迫总体上使幼苗叶绿素合成受到抑制,但在胁迫时间较短时其含量随Cu2+质量浓度的升高表现出先升后降的变化趋势;Cu2+胁迫使SOD活性在处理初期低质量浓度下受到刺激而在高质量浓度和较长时间胁迫下受到抑制;POD活性在Cu2+胁迫下随处理质量浓度的升高不断增强;尽管SOD、POD活性的激发能削弱细胞膜脂过氧化作用,但Cu2+胁迫下幼苗体内MDA含量的逐渐增加却表明,芝麻幼苗本身的抗氧化酶系统不足以抵挡Cu2+污染的危害。

The growth processes of gingili plants under the stress of different Cu2＋concentrations and the changes of chlorophyll contents,MDA（malondialdehyde） contents,SOD（superoxide dismutase） activities and POD（peroxidase） activities in their leaves during the seedling period were studied through solution culture experiments.The results showed that（i） short treatment of lower concentration Cu2＋ stimulated the seedling length,but longer treatment of higher concentration Cu2＋ inhibited growth of the seedlings.Root length was sensitive to the Cu2＋ treatment and inhibition effect on root length was detected above the 1.0 mg·L-1 of Cu2＋.（ii） In general,Cu2＋ stress restrained chlorophyll synthesis of the gingili leaves.However,in the short-time treatment,the content of chlorophyll increased first and then decreased with the increase of Cu2＋ concentration.（iii） Cu2＋ stress can stimulate SOD activity in the lower concentrations at the initial stage,but the activity turned to be restrained with the increase of Cu2＋ concentrations.POD activity increased gradually with the Cu2＋ increase of concentrations.（iv） Although SOD activities and POD activities can decrease the peroxidation degree of membrane,the antioxidant enzyme system of gingili itself can not resist the harm of Cu2＋ pollution,so the MDA content was increasing gradually.