Cd Uptake And Transportation In Ramie Under Zn And Fe Deficiency And Combined Contaminations Of Cd And As

Ramie has relatively strong tolerance and absorptive capacity of heavy metals. It's a potential target plant in remediation of heavy metal contaminated soil. Based on the greenhouse of ramie in Hunan Agricultural University, this study selected Zhongzhu-1, Xiangzhu-3, Tri-1 and Xiangzhu-7 as experiment materials. The pot experiment was performed to study the effects of zinc and iron deficiency and combined contaminations of cadmium and arsenic on growth and cadmium uptake and transportation in ramie. The main results are as follows:The effects of zinc and iron deficiency on cadmium concentrations and distribution in Zhongzhu-1 and Xiangzhu-3 were carried out in hydroponic conditions test. Supply of zinc and iron can promote the growth of ramie under cadmium stress. Compared with the CK, plant height, biomass of stem and leaf, biomass of root for ramie in zinc and/or iron deficiency treatments were significantly reduced by 10.24%?21.64%,1.02%?6%, 2.04%?12.24% respectively. Zinc and iron significantly affects the cadmium content in ramie, treatments with Zinc or iron-deficient promoted cadmium concentration and accumulation in ramie. Compared with the CK, the cadmium concentrations in roots, stems and leaves of Zhongzhu-1 were increased by 4.98%?14.41%,16.17%?20.06%, 5.45%?21.48% respectively. Xiangzhu-3 were also increased by 10.65%-27.04%, 27.41%?34.13%,14.32%?28.05%, respectively. The cadmium accumulation in ramie was maximum appeared in zinc-deficiency treatments that the cadmium accumulation in root of zhongzhu-1 and Xiangzhu-3 were increased by 9.73% and 21.97%, the cadmium accumulation in stem and leaf of Zhongzhu-1 and Xiangzhu-3 were increased by 21.84% and 28.83%, respectively. Zinc and/or iron deficiency increased TFroot to leaf and TFroot to stem-The TFroot to leaf and TFroot to stem of Zhongzhu-1 and Xiangzhu-3 were increased by 4%?24% in zinc and/or iron deficiency treatments. Zinc and iron has inhibitory effect on ramie running cadmium. Zinc and/or iron deficiency will increase cadmium from root to stem and leave.The effects of combined contaminations of cadmium and arsenic on growth and cadmium uptake and transportation in Zhongzhu-1, Xiangzhu-3, Tri-1 and Xiangzhu-7 were carried out in hydroponic conditions test. Combined contaminations of cadmium and arsenic inhibit the growth of ramie and increased plant height, stem diameter and biomass of root, stem and leave. Under 50 mg/kg arsenic stress, the cadmium concentrations in root of Zhongzhu-1 and Xiangzhu-3 were increased; the cadmium concentrations in stem of Zhongzhu-1, Xiangzhu-3 and Xiangzhu-7 were reduced; the cadmium concentrations in leave of 4 ramie cultivars were increased. Under 100 mg/kg arsenic stress, the cadmium concentrations in root, stem and leave of 4 ramie cultivars were reduced. The cadmium accumulation in root and stem were reduced along with the arsenic concentration increased in treatments, but the cadmium accumulation in leave was increased under 50 mg/kg arsenic stress and reduced under 100 mg/kg arsenic stress. Under the combined contaminations of cadmium and arsenic, the arsenic accumulation in roots was 23-27 times more than in stems and leaves. The cadmium concentration and accumulation in leave were increased under 50 mg/kg arsenic stress, it may be because combined contaminations of cadmium and arsenic increase cadmium from root to stem and leave. The 100 mg/kg arsenic stress has significantly inhibitory effect on ramie growth and physiological activity, that the cadmium concentration and accumulation in 4 ramie cultivars and the arsenic concentration in Xiangzhu-7 were reduced. Under the combined contaminations of cadmium and arsenic, the tolerance was Zhongzhu-1>Tri-1>Xiangzhu-3>Xiangzhu-7.From what has been discussed above, cadmium stress has significantly effect on ramie growth. Zinc and iron can promote the growth, inhibiting the uptake and transportation of cadmium and alleviate the toxicity of cadmium on ramie. Combined contaminations of cadmium and arsenic have significant impact on growth of ramie. Under the combined contaminations of cadmium and arsenic, the cadmium concentration and accumulation in different ramie cultivars have genotypic differences. The cadmium concentration and accumulation in root, stem and leave of 4 ramie cultivars were reduced and the growth of ramie has been severely affected by 100 mg/kg arsenic stress.