土壤容重改变对锌/镉超累积植物遏兰菜根系特征及吸镉的影响

为了探讨土壤容重的变化对锌/镉超累积植物遏兰菜(Thlaspi caerulescens)根系形态特征及吸收土壤中镉、锌的影响,采用土壤盆栽方法,研究了土壤结构改良剂(EB.a)对镉污染土壤(2.12 mg.kg-1)的容重和遏兰菜提取镉/锌效率的影响.EB.a用量分别为0、0.1%和2%,植物种植100 d后收获.结果表明,EB.a可有效地降低土壤容重,2%EB.a处理土壤容重从1.27g.cm-3降至1.09 g.cm-3;土壤容重的降低,促进了遏兰菜根系和地上部的生长;植物的总根长、根毛长、根冠比均显著提高(p0.05).随着植物根长的增加,遏兰菜地上部提取镉/锌总量均显著提高(p0.05).与对照相比,2%EB.a处理致使遏兰菜总根长增加了2.6倍,植物地上部镉浓度和提取总量分别提高了20%和30%,镉提取效率由15%提高至19%;但遏兰菜的地上部锌浓度和提取总量并没有显著变化.研究结果证实了改善土壤结构可以促进遏兰菜根系的生长从而提高植物对镉的提取效率.

Effect of the Soil Bulk Density on the Root Morphology and Cadmium Uptake by Thlaspi caerulescens Grown on Cd Contaminated Soil

A pot experiment was conducted using a soil contaminated with 2.12mg·kg^-1 Cd to study the effect of the variety of the soil bulk density on the Zn/Cd uptake by the hyperaccumulator Thlaspi caerulescens and the removal of Cd and Zn from the soil. The contaminated soil received 0,0.1%,2% of soil conditioner and the plants were harvested after 100 days. The results showed that soil amendment with the soil conditioner (EB.a) significantly decreased the soil bulk density. Compared to the control,the bulk density value decreased from 1.27g·cm^-3to 1.09g·cm^-3 at the level of 2% soil conditioner. The increased biomass of shoot and root was observed at the treatment of EB.a amendment. The total root length,root hair length and root/shoot ratio were all significantly enhanced (p<0.05) by the addition of EB.a. The significant positive relationships between the total root length and the removed Cd/Zn from soil were determined (p<0.05). Compared with the control,the total root length was increased by 2.6 folds at the addition of 2% soil conditioner; the Cd concentration and removal of Cd from soil were significantly elevated by 20% and 30% respectively. The phytoextraction efficiency of Cd was improved from 15% to 19%. However,the Zn concentration and removal of Zn were not significantly elevated by the addition of soil conditioner. The present results demonstrate that the decreased soil bulk density may improve the root system of T. caerulescens and enhance the phytoextraction efficiency of Cd.