Plant and Soil

, Volume 300, Issue 1–2, pp 127–136

Toxic effects of Pb2+ on the growth and mineral nutrition of signal grass (Brachiaria decumbens) and Rhodes grass (Chloris gayana)

  • P. M. Kopittke
  • C. J. Asher
  • F. P. C. Blamey
  • N. W. Menzies
Regular Article

Abstract

Although grasses are commonly used to revegetate sites contaminated with lead (Pb), little is known regarding the Pb-tolerance of many of these species. Using dilute solution culture to mimic the soil solution, the growth of signal grass (Brachiaria decumbens Stapf cv. Basilisk) and Rhodes grass (Chloris gayana Kunth cv. Pioneer) was related to the mean activity of Pb2+ {Pb2+} in solution. There was a 50% reduction in fresh mass of signal grass shoots at 5 μM {Pb2+} and at 3 μM {Pb2+} for the roots. Rhodes grass was considerably more sensitive to Pb in solution, with shoot and root fresh mass being reduced by 50% at 0.5 μM {Pb2+}. The higher tolerance of signal grass to Pb appeared to result from the internal detoxification of Pb, rather than from the exclusion of Pb from the root. At toxic {Pb2+}, an interveinal chlorosis developed in the shoots of signal grass (possibly a Pb-induced Mn deficiency), whilst in Rhodes grass, Pb2+ caused a bending of the root tips and the formation of a swelling immediately behind some of the root apices. Root hair growth did not appear to be reduced by Pb2+ in solution, being prolific at all {Pb2+} in both species.

Keywords

Root and shoot growth Root hairs Chlorosis Tolerance 

Abbreviations

AMF

Arbuscular mycorrhizal fungi

DAP

Days after planting

EC

Electrical conductivity

FIA

Flow injection analysis

ICP-MS/OES

Inductively coupled plasma-mass spectrometry/optical emission spectrometry

XPS

X-ray photoelectron spectroscopy

Copyright information

© Springer Science+Business Media B.V. 2007

Authors and Affiliations

  • P. M. Kopittke
    • 1
    • 2
  • C. J. Asher
    • 1
  • F. P. C. Blamey
    • 1
  • N. W. Menzies
    • 1
    • 2
  1. 1.School of Land, Crop and Food SciencesThe University of QueenslandSt. Lucia, QldAustralia
  2. 2.Cooperative Research Centre for Contamination Assessment and Remediation of the EnvironmentThe University of QueenslandSt. Lucia, QldAustralia

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