玉米根系Cr^(6+)吸收动力学特征及幼苗生长的反应

Kinetics of Cr^(6+) Uptake by Maize Roots and Cr^(6+) Stress on Growth of Maize Seedling

通过水培方法,研究了玉米根系对以K2Cr2O7形式添加的Cr6+的吸收特征及其不同浓度Cr6+对玉米根系和幼苗生长的影响。结果表明,玉米植株Cr6+含量随溶液中Cr6+浓度的增加而增加,吸收动态符合Michaelich-Menten模拟曲线方程特征,根系Cr6+含量明显高于地上部Cr6+含量,富集系数也极显著高于地上部。Cr6+对玉米形态生长的影响表现为"低促高抑"特征,低浓度Cr6+(<1.00 mg/L)促进玉米根系形态发育,根长、根表面积、根体积及生物量明显增加;高浓度Cr6+(≥1.00 mg/L)抑制玉米根系发育,当Cr6+浓度达到2.00 mg/L时,即可极显著降低玉米幼苗的根长和根表面积。不同浓度的Cr6+处理使玉米幼苗叶绿素含量较不添加Cr6+的对照均有所下降,表现出"脉间失绿"症状,其中低浓度Cr6+处理因玉米生物量的增加造成的稀释作用使得这种"失绿"症状尤为明显。

This paper describes an experiment of hydroponic culture of maize, with Cr6＋ （hexavalent chromium）added to the nutrient solution in different concentrations in order to study the effects of Cr6＋ stress on maize roots and seedling growth. The results showed that Cr6＋ content in maize seedling went up with the increase of Cr6＋ in the solution medium, and the uptake kinetics of Cr6＋ absorbed in maize root system fit in with the dynamic equation of Michaelich-Menten, and it was evident that Cr6＋ content in roots was much higher than that in the plants＇ other parts above the ground. As to the effects of Cr6＋ on the morphological development of maize, Cr6＋ with lower concentrations （〈1.0 mg/L）tended to boost roots growing, but then Cr6＋ in higher concentrations inhibited roots growth, even remarkably when concentrations went up to 2.0 mg/L in the nutrient solution. Compared with the normally growing maize seedling without hexavalent chromium added, Cr6＋ affected seedling had lower chlorophyll content in leaves, i.e., the symptom called ＂inter-venial chlorosis＂ which could be more apparently seen for the maize treated with low concentration Cr6＋ due to the dilution effect attributed to the biomass increases of the plants.