镉对小麦种子萌发、幼苗生长及抗氧化酶活性的影响

为了防止重金属毒害的发生和在环境监测中对重金属的评价,以小麦为试验对象,采用室内培养方法,研究了不同浓度镉胁迫对小麦种子萌发和幼苗生长、丙二醛及抗氧化酶系统的影响,结果表明,较低浓度镉胁迫对种子发芽率、发芽势、芽生长的抑制效应较小.随着镉胁迫浓度的提高,发芽指数、活力指数及根生长明显受抑制,且镉胁迫浓度越大,抑制作用越大.随着镉浓度的增加,幼苗根、芽中的MDA含量、G-POD明显增加,SOD活性呈现先增加后降低的趋势,其中根的SOD活性在1 000 μmol/L Cd胁迫下略低于对照,而CAT、APX活性总体呈下降趋势,且浓度越高下降幅度越大,表明遭受了氧化胁迫和膜脂过氧化损伤,这可能是镉胁迫下小麦幼苗根生长受阻的重要原因.

Effect of Cadmium Stress on Seed Germination,Seedling Growth and the Activities of Antioxidant Enzymes of Wheat

Cadmium ( Cd ) was a highly toxic and persistent environmental poison, its increasing level in soil environ-ment exerted a wild range of adverse effects on plants and even the healthy of human beings by food chains. In the study, the effects of Cd at different concentrations on wheat seeds germination, seedlings growth and the activities of antioxidant enzymes were studied. The results showed the germination percentage, germination potential and shoot growth were not sig-nificantly inhibited by cadmium, especially at low Cd concentrations. However, germination index, vigor index, root growth were restrained evidently with the increase of Cd stress. The content of MDA and activities of G-POD in root and shoot in-creased significantly with the increasing of Cd concentration. The activities of SOD first increased and then decreased as the Cd concentration increased and it was slight lower than that of control in root under 1 000 μmol/L Cd stress. Howev-er, the activities of CAT and APX were decreased with concentration-dependent manner, ie, the higher concentration of cadmium, the greater changes the enzyme activities, suggesting oxidative damage and membrane lipid peroxidation oc-curred in seedlings, and it might be the important reason for the growth inhibition of roots subjected to cadmium stress.