Accumulation Of Cadmium In Datura Stramonium L. And Related Mechanisms

The investigation on 56 wild species in 23 families of was conducted around lead-zinc smelting enterprises and the local abandoned mines,which was focused on differences in growth and cadmium(Cd)absorption.We discussed the tolerance of Datura stramonium L toward Cd strss,accumulation and translocation of Cd,to explore the potential of Datura S for phytoremediation of Cd contaminated soil and related mechanisms.This study includes two parts:field-experiment and mechanism research.Selected Datura S were used for pot-experiment(Cd absorption and chelator regulation,and for sand-culture experiment(physiology and accumulation mechanisms).The objectives were to give an insight into the growth status of Datura S,subcellular distribution and chemical forms of Cd under different levels of Cd stress.The main results are as follows:1.The investigations showed that,the herbaceous plants were flouris,mainly with asteraceae and gramineae families more than other families.Among 56 species of wild plants,Datura S carried the most of Cd,suggesting its potential for phytoremediation of contaminated soil induced by Cd.Further investigation indicated that,the specie varieties decreased with the aggravation of soil pollution,but Datura S with strong ability to accumulate Cd could still grow normally.The Cd carrying amount in leaves reached 47 mg?kg-1.In addition,Cd carrying amount in aboveground part could account for more than 90% of the whole plant.The results showed the aboveground part of Datura S had strong ability to accumulate and translocate Cd,in the surrounding soil of lead-zinc smelting enterprises.This plant could be used as potential option to remediate contaminated soil.2.In sand-culture experiment,Cd carrying in the root was larger than that in the aboveground part during seedling stage for Datura S.For Cd form,the Cd in root was primarily actived ethanol-extraction,and its proportion increased with increase of Cd level.When Cd concentration in medium increased,the proportion of ethanol-extraction in addition with water-extraction Cd decreased,the proportion of less-actived Cd as sodium chloride extraction increased in stems and leaves.For Cd subcellular distribution,Cd were mainly distributed in cell wall and cell sap(soluble components),and rarely in organelles for seedlings of Datura S.With the increase of Cd level,the absorption amount of Cd in cell walls reached saturation,and the complexation of Cd was obviously increased in cell sap components.In addition,the proline and soluble sugar under Cd stress in leaves increased to different extents,which may play a role in osmoregulation toalleviate the water stress.3.In pot-experiment,the response of Datura S to chelating agent in Cd contaminated soil showed that,with the increase of stress time,only leaves decreased in later-period in contaminated soil,the Cd carrying amount of each part of Datura S were all showed a decrease trend,which may be related to increase in its biomass.After chelating agents applied into the soil,both EDTA(5 mmol?kg-1)and citric acid(10 mmol?kg-1)could enhance Cd carrying in each part of Datura S.The effect of EDTA on Cd carrying was significant(root 53%,stem 46% and leaf 46%)but with certain inhibitory effect on leave growth.