钴在油菜中的积累分布及其对光合作用的影响

Accumulation and Distribution of Cobalt in Rape and the Effects of Cobalt on the Photosynthesis of Rape Leaves

以甘蓝型油菜(Brassica napus L.)幼苗为材料,分别采用不同浓度的钴(0、10、25、50、100mg.kg-1)土培处理7d,研究钴在油菜体内的分布规律及钴对叶片光合色素含量、光合气体交换参数和叶绿素荧光参数的影响。结果表明:(1)油菜的根、茎、叶均可以吸收积累一定量的钴,油菜对钴的富集量与土壤中的钴含量呈显著正相关,不同器官对钴的积累量存在显著差异,表现为:根>茎>叶,且老叶>嫩叶。(2)土壤中钴浓度为10mg.kg-1时,油菜叶片的色素含量和净光合速率、气孔导度、胞间CO2浓度、蒸腾速率等光合气体交换参数比对照均显著增加,此后随着钴浓度的增加各参数均显著下降,即钴对油菜光合作用的影响表现出低浓度促进高浓度显著抑制的效应。(3)叶绿素荧光分析表明,钴处理显著影响了油菜叶片光系统Ⅱ(PSⅡ)的结构和功能,高浓度钴处理显著抑制了PSⅡ反应中心的活性。

Soil pot experiment was used to investigate the accumulation and distribution of cobalt in rape（Brassica napus L.）and the effects of cobalt on the photosynthesis of rape leaves.Rape seedlings at the six-leaf stage were treated with different concentration cobalt（0,10,25,50,100mg.kg-1）,and the cobalt content in roots,stems and leaves,pigment content,photosynthetic gas exchange parameters and chlorophyll fluorescence characteristics of leaf were investigated on the 7th day after the cobalt treatment.The results showed that：（1）The roots,stems,leaves of rape could absorb and accumulate a certain amount of cobalt,and rape cobalt content and soil cobalt content was a significant positive correlation;there were significant differences in cobalt distribution between the different organs,and the distribution law of cobalt content in rape was：rootsstemsleaves,and old leavesyoung leaves.（2）When the soil cobalt content is 10 mg.kg-1,compared with the control,both of the pigment content of leaf,net photosynthetic rate（Pn）,stomatal conductance（Gs）,intercellular CO2concentration（Ci）,transpiration rate（Tr）significantly increased,after that with the increase of cobalt concentration all of the parameters were significantly decreased,it showed that low concentrations of cobalt could promote the photosynthesis of rape and high concentrations of cobalt significantly inhibit the photosynthesis of rape.（3）Chlorophyll fluorescence analysis showed that the cobalt significantly affected the structure and function of photosystem Ⅱ（PSⅡ）in rape leaves,and high concentrations of cobalt significantly inhibited the activity of the PSⅡreaction center.