Distribution of Mineral Elements in Green and Chlorotic Leaf Tissue of Eucalyptus obliqua L'hérit., Determined With a Scanning Proton Microprobe

Abstract

A scanning proton microprobe was used to compare the relative concentrations and the localizations of various elements in green and chlorotic leaf tissue of E. obliqua. Proton Induced X-ray Emission (PIXE) has a high sensitivity for detecting trace elements. Chlorosis develops in those genotypes of E. obliqua which are native to acidic soils and which are transplanted to alkaline, calcareous soils. The chlorosis was correlated with high internal levels of P, S, K and Ca. Levels of the trace elements Mn, Fe, Cu and Zn were either higher than or similar to levels in those genotypes native to, and grown in, the calcareous soils, and it is suggested that chlorosis is related primarily to an imbalance of elements, particularly the ratio of P to Fe. There was no evidence of phosphate-induced precipitation of Fe in veins or other localized areas in leaves.