外源柠檬酸对3种观赏植物吸收和转运镉的影响

Effect of citric acid amendment on cadmium uptake and translocation by three ornamental plants

为了探究柠檬酸与植物联合修复镉污染土壤的效果,采用盆栽试验,研究外源柠檬酸的添加对萱草(Hemerocallis fulva)、鸢尾(Iris tectorum Maxim.)和美人蕉(Canna indica L.)3种观赏植物修复镉污染土壤的影响。结果表明:(1)与CK和未添加柠檬酸处理组相比,柠檬酸添加显著降低了土壤的pH值。(2)柠檬酸的添加显著改善了萱草、鸢尾和美人蕉的生长状况,植物的株高、根长和生长量最大值均出现在添加柠檬酸中浓度镉污染(Tm)处理中,其单株生物量最高值分别为13.97、23.92和56.95g。(3)在CK和未添加柠檬酸处理组中,萱草、鸢尾和美人蕉的地上部分镉含量低于地下部分,其差值变化范围分别为-5.09~-41.06、-6.44~-49.77和-15.35~-53.80 mg·kg^(-1);而柠檬酸的添加促进了地下部分镉向地上部分的转移,使地上部分镉含量高于地下部分,其差值变化范围分别为9.98~42.50、9.51~44.93和16.10~47.59 mg·kg^(-1)。(4)萱草、鸢尾和美人蕉3种观赏植物在添加柠檬酸处理组中的转运系数大于1,显著增加了植株地上部分的镉积累量,且美人蕉的地上部分和地下部分镉积累量明显高于萱草和鸢尾,其最高值分别为7603.39和1545.60μg·株^(-1)。综上所述,萱草、鸢尾和美人蕉3种观赏植物均可作为土壤镉污染修复植物使用,添加柠檬酸可有效提高3种观赏植物对镉污染土壤的修复效率。美人蕉由于植株高大和块状根茎的特性,使其表现出比萱草和鸢尾更强大的镉修复能力。

In order to explore the effect of citric acid and plants on remediation of cadmium contaminated soil.In the study,we used Hemerocallis fulva,Iris tectorum and Canna indica as the experimental materials to the pot experiment.To study the effects of exogenous citric acid on the remediation of cadmium contaminated soil by three ornamental plants.Three species were treated with various concentrations of cadmium pollution.Control group(CK);not added citric acid group(Wz:1 mg·kg^(-1),Wm:5 mg·kg^(-1),Wg:10 mg·kg^(-1));added citric acid group(Tz:1 mg·kg^(-1),Tm:5 mg·kg^(-1),Tg:10 mg·kg^(-1)).The results showed that:(1)Compared with CK and the treatment group without citric acid,the addition of citric acid significantly reduced the pH value of the soil.(2)The addition of citric acid significantly improved the growth of three ornamental plants(Hemerocallis fulva,Iris tectorum and Canna indica).The maximum plant length,root length and growth amount of plants all appeared in the cadmium pollution(Tm)treatment with citric acid,and the maximum biomass per plant was 13.97 g,23.92 g and 56.95 g,respectively.(3)In CK and citric acid free treatment groups,the cadmium content in the overground part of the three ornamental plants was lower than that in the underground part.The different ranges were-5.09--41.06,-6.44--49.77 and-15.35--53.80 mg kg^(-1),respectively.However,the addition of citric acid promoted the transfer of cadmium from the underground part to the overground part,making the cadmium content in the overground part higher than that in the underground part.The difference ranges are 9.98-42.50,9.51-44.93 and 16.10-47.59 mg kg^(-1),respectively.(4)The transport coefficient of the three ornamental plants in the citric acid treatment group was greater than 1,which significantly increased the cadmium accumulation in the overground part of the plants.Moreover,the cadmium accumulation in the overground and underground parts of Canna indica was significantly higher than that of Hemerocallis fulva and Iris tectorum,with the highest values of 7603.39 and 1545.60μg·plant^(-1),respectively.In summary,all three ornamental plants can be used as remediation plants for cadmium contaminated soil,and citric acid can effectively improve the remediation efficiency of the three ornamental plants for cadmium contaminated soil.Canna indica has stronger cadmium remediation ability than Hemerocallis fulva and Iris tectorum due to its tall and massive rhizome.