Seedling response of three Eucalyptus species to copper and zinc toxic concentrations

Human activities have continuously increased the level of heavy metal ions circulating in the environment. It is important to understand the tolerance of plant species to high concentrations of heavy metals. Very little is known on the response of Eucalyptus species to Zn and Cu toxic concentrations Eucalyptus camaldulensis, E. microtheca, and E. occidentalis seeds were grown in silt and irrigated by nutrient solution. Forty two days old seedlings were exposed to ten Zn and Cu treatments for ten months. The tolerance order of the species to toxic concentrations of Cu was Eucalyptus camaldulensis> E. occidentalis> E. microtheca and the tolerance order of the species to toxic concentrations of Zn was E. occidentalis> E. microtheca> E. camaldulensis. Tissue concentration increased as Zn and Cu concentration increased for the species. Root tissue concentrations regards to Zn and Cu concentrations were higher than shoot tissue concentration at all solution. These results provided the first quantified metals in Eucalyptus species and the second explored relationships between concentrations of metals in nutrient solution and plant organs.