Morphological and physiological responses of barley plants grown on soils characterised by metal toxicity and metal deficiency.

Aim of this work was to investigate which are the effects on barley crops grown on two different soils: a soil lacking in Cu, an essential micronutrient (A) and a naturally polluted soil rich in lead, zinc, copper (B). In particular we investigated the relationship between some ecophysiological parameters such as biomass, chlorophyll concentration and guaiacolo peroxidase activity and the chemical-physical properties of the soils like pH, organic matter and heavy metal content. Because metals uptake by plants is strongly correlated with the bioavailable fraction rather then their total amount in a soil, we have measured also metal exchangeable forms, using a single extraction method (MgCl2 as extractant). Plants grown on soil B showed a metal content higher than background limits, whereas plants grown on soil A were characterised by a background Fe and Zn concentrations and by a tolerant Pb concentration. Conversely, Cu content in tissues of plants grown in soil A is found to be under the background limits. Copper-deficiency plants present chlorotic leaves followed by a reduced clorophyll content, while plants grown on metals contaminated soil showed an increase of peroxidase activity.