Se(Ⅳ)和Se(Ⅵ)对小白菜生长及生理效应的影响

Effects of different concentrations of selenate and selenite on growth and physiology of Chinese cabbage

用盆栽试验研究了不同含量Se(Ⅳ)和Se(Ⅵ)对小白菜生长和生理效应的影响.结果表明,不同含量Se(Ⅳ)和Se(Ⅵ)对小白菜体生长和生理代谢的影响不尽相同.低含量硒(Se(Ⅳ)<10.0mg·kg-1、Se(Ⅵ)<5.0mg·kg-1)能够促进小白菜的生长,使其根变粗,诱导脯氨酸的产生,阻止丙二醛(MDA)的合成,增强白菜的抗逆性,使其生物量明显提高;高含量硒会抑制小白菜的生长,导致植物体内脯氨酸合成下降,MDA含量增加,叶及根系生长受到抑制,地上和地下部干重显著急速下降(p<0.01).小白菜根长、叶面积等生长指标均随Se(Ⅳ)和Se(Ⅵ)含量的增大而显著下降(p<0.01);抑制小白菜根系生长的Se(Ⅳ)含量为60mg·kg-1,明显高于Se(Ⅵ)含量(20.0mg·kg-1).相同硒含量下,Se(Ⅳ)处理的小白菜地上部干重为Se(Ⅵ)的1.1～3.0倍,说明本试验条件下Se(Ⅵ)的生物有效性和毒性均大于Se(Ⅳ).Se(Ⅵ)处理小白菜地上部分的硒含量显著高于地下部分,而Se(Ⅳ)处理小白菜地下部分的硒含量显著高于地上部分,小白菜地上和地下部分对Se(Ⅵ)的吸收量均显著高于Se(Ⅳ).综合生长和生理因子分析表明,地上部分生物量是反映Se(Ⅳ)及Se(Ⅵ)处理土壤上小白菜生长状况的理想指标.

Chinese cabbage grown in pots was exposed to different concentrations of selenate （Se（Ⅵ）） and selenite （Se（Ⅳ）） to determine the effects of selenium species and concentration on plant growth and physiological metabolism. Lower selenium concentration （Se （Ⅳ） 〈10.0 mg·kg^-1 and Se （Ⅵ） 〈5.0 mg·kg^-1） stimulated the plant growth. The roots of the cabbage thickened,proline content rose and malondialdehyde （MDA） content dropped,enhancing the anti-adveristy of the plant. In contrast,higher selenium concentrations inhibited plant growth. Proline content decreased and MDA content rose while dry weight of shoots and roots declined significantly as selenate and selenite concentrations increased（p〈 0.01）. The selenium concentration which induced inhibition of root growth was 60.0 mg·kg^-1 for Se（Ⅳ） and 20.0 mg·kg^-1 for Se（Ⅵ）. At the same selenium concentration,cabbage biomass after selenite treatment was 1.1 to 3.0 fold greater than that after selenate treatment. Therefore,both the bioavailability and toxicity of selenate were greater than those of selenite under these experimental conditions. Plants grown in the presence of Se （Ⅵ） accumulated higher amounts of selenium in shoots in comparison to plants grown in the presence of Se （Ⅳ）. For selenate exposed plants,the selenium concentration was higher in shoots than in roots,while for selenite exposed plants,the selenium concentration was higher in roots than shoots. Analysis of the factors which affected growth and physiology of Chiense cabbage showed that shoot biomass was an ideal indicator for cabbage growth on selenate and selenite polluted soil.