Effects Of Two Rhizosphere Conditions On The Uptake Of Several Micronutrient Elements By Eucalyptus

The effects of Low-molecular-weight organic acids (LMWOAs) and arbuscular mycorrhizal fungi (AMF) on the uptake copper (Cu), zinc (Zn), manganese (Mn), molybdenum (Mo) and ferrum (Fe) by eucalyptus and on the interactions between Cu and Zn were investigated in pot experiments. Eucalyptus was cultured in artificial soil contaminated with increasing Cu (0,10,25,50mg/kg) and/or Zn (0,50,100,200,300,500mg/kg), Mn, Mo, Fe (0,100,200,300,500,700mg/kg) respectively. With added LMWOAs or inoculated with AMF, eucalyptus was harvested after8weeks. The data about the biomass of eucalyptus, the colonization rate of root, content of micronutrient elements in eucalyptus were determined. Exogenous LMWOAs comprised of formic acid, acetic acid, citric acid and malic acids (molar ratio=2:2:1:1) were added to soil in the experiment. AMF of Glomus mosseae (G. m), Glomus intraradice (G. i) and Glomus etunicatum (G. e) were inoculated respectively.The results indicated that the biomass of shoots and roots were increased by lower concentrations of micronutrient elements while decreased by high concentrations of micronutrient elements. The concentrations of micronutrient elements in eucalyptus were increased with micronutrient elements content increasing in soil. Increasing Zn in soil could decrease the concentrations of Cu in shoots while increase concentrations of Cu in roots firstly and then decrease it last. Increasing Cu in soil had little influence on the uptake of Zn in eucalyptus shoots, but increase Zn concentrations in eucalyptus roots. LMWOAs could increase the biomass of eucalyptus shoots and roots, decrease the concentration of Cu and Zn in eucalyptus shoots and roots, change the interactions between Cu and Zn. Root colonization rates of G. m were higher than G. i on the conditions of Cu and Zn, root colonization rates of G. e were higher on the condition of Mn than on the condition of Mo or Fe. G. m and G. i could increased eucalyptus biomass on the condition of Cu and Zn, G. e could increased eucalyptus biomass on the condition of Mn and Mo while G e had little influence to eucalyptus biomass on the condition of Fe. With no Cu in soil, G. m and G. i could enhance eucalyptus uptake Cu, however, G. m and G. i could restrain eucalyptus uptake Cu and Zn when Cu and Zn added in soil together. G. m and G. i could change the interactions between Cu and Zn. G.e could decrease the concentration of Mn、Mo and Fe in eucalyptus shoots, restrained eucalyptus roots uptake Mn and Fe, inhanced eucalyptus roots uptake Mo.