镉胁迫对向日葵幼苗生长和生理特性的影响

采用溶液培养方法,研究了不同浓度镉(0、0.05、0.1、0.5和1 mg/L)处理7 d对向日葵幼苗生长和生理特性的影响。结果表明：随着镉处理浓度的增加，向日葵幼苗对镉的吸收显著增加。1 mg/L镉浓度处理时，叶、茎和根中镉浓度分别为0.05 mg/L镉处理时的16.3、19.2和581倍；根中积累的镉含量明显高于叶和茎, 各浓度根部积累的镉分别为叶和茎的37.8～63倍和29.4～41倍。镉胁迫显著抑制向日葵幼苗生长和叶绿素合成，当镉浓度达1 mg/L时，整株植物生物量和总叶绿素含量分别为对照的55.9%和52.6%。镉胁迫下向日葵幼苗游离脯氨酸和丙二醛（MDA）含量显著增加，1 mg/L镉浓度时，根中含量分别为对照的4和5.8倍。向日葵幼苗可溶性蛋白含量和过氧化物酶(POD)活性变化与镉胁迫浓度呈明显的倒U字型关系，可溶性蛋白含量在0.05 mg/L镉浓度时达到最大值，叶、茎、根中的POD活性分别在0.1、0.1和0.05 mg/L镉浓度时达到最大值。

Effects of cadmium on the growth and physiological characteristics of sunflower seedlings

A hydroponic culture experiment was conducted to study the effects of different concentrations of cadmium on the growth and physiological characteristics of sunflower seedlings. The seedlings were treated with 0,0. 05,0. 1,O. 5 and 1 mg/L cadmium for periods of 7 days. The results showed that the cadmium absorbed by sunflower seedlings significantly increased with the augmenting of cadmium concentrations. Specifically,the cadmium accumulated in leaves,stems and roots at 1 mg/L cadmium was 16. 3,19.2 and 581 times as much as at 0. 05 mg/L cadmium,respectively. In addition,cadmium concentrations in roots were 37.8～63 and 29.4～41 times more than that in leaves and stems. The growth and chlorophyll contents of sunflower seedlings were sig-nificantly inhibited by cadmium stress. As compared with control,when cadmium concentration reached 1 mg/L,the biomass of whole plants and total chlorophyll contents dropped to 55.9% and 52. 6%. However,cadmium addition increased the malonyldialdehyde (MDA) and free proline contents,and at 1 mg/L cadmium the contents in roots raised 3 and 4. 8 times as against the control. The inverted U-shaped dose-response effects of cadmium on soluble protein contents and the activities of peroxidase (POD) were observed,with maximum effects of soluble protein contents at 0. 05 mg/L cadmium,and at 0. 1,0. 1,0. 05 mg/L cadmium POD in leav-es,stems,roots attained maximum activities,respectively.