title: Accumulation and precipitation of magnesium, calcium, and sulfur in two Acacia (Leguminosae; Mimosoideae) species grown in different substrates proposed for mine-site rehabilitation.
abstract: OBJECTIVE
  Few studies have investigated the effects of substrates on the accumulation and precipitation of magnesium, calcium, and sulfur in plants. Acacia stipuligera and A. robeorum growing in their natural habitats with different substrates show different accumulation and precipitation patterns of these elements. Here, we compared the accumulation and precipitation of magnesium, calcium, and sulfur in A. stipuligera and A. robeorum grown in different substrates proposed for mine-site rehabilitation and expected the differences in substrates to have significant effects on the accumulation and precipitation of these elements in the two species.
  
  
  METHODS
  Saplings were grown in sandy topsoil or in a topsoil-siltstone mixture in a glasshouse. Phyllode magnesium, calcium, and sulfur concentrations of 25-wk-old plants were measured. Precipitation of these elements in phyllodes and branchlets was investigated by means of scanning electron microscopy and energy-dispersive x-ray spectroscopy.
  
  
  RESULTS
  Phyllode magnesium, calcium, and sulfur concentrations were generally significantly greater in A. robeorum than in A. stipuligera. The two species responded in unique ways to the substrate, with A. stipuligera having similar phyllode magnesium and calcium concentrations in both substrates, but greater sulfur concentration in the topsoil-siltstone mixture, while A. robeorum showed lower phyllode magnesium, calcium, and sulfur concentrations in the topsoil-siltstone mixture. For both substrates, mineral precipitates were observed in both species, with A. robeorum having more mineral precipitates containing magnesium, calcium, and sulfur in its phyllodes than A. stipuligera did.
  
  
  CONCLUSIONS
  The accumulation and precipitation patterns of magnesium, calcium, and sulfur are more species-specific than substrate-affected.
authors: School of Plant Biology, The University of Western Australia, 35 Stirling Highway, Crawley (Perth), WA 6009, Australia State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Northwest A&F University, Yangling, Shaanxi 712100, China.
authors: Honghua
authors: H
authors: He
authors: Centre for Microscopy, Characterisation & Analysis, The University of Western Australia, 35 Stirling Highway, Crawley (Perth), WA 6009, Australia.
authors: Yaowanuj
authors: Y
authors: Kirilak
authors: Centre for Microscopy, Characterisation & Analysis, The University of Western Australia, 35 Stirling Highway, Crawley (Perth), WA 6009, Australia.
authors: John
authors: J
authors: Kuo
authors: School of Plant Biology, The University of Western Australia, 35 Stirling Highway, Crawley (Perth), WA 6009, Australia.
authors: Hans
authors: H
authors: Lambers
mesh_terms: D000045:Acacia / Q000145:classification / Q000378:metabolism*; D001673:Biodegradation, Environmental; D002118:Calcium / Q000378:metabolism*; D017753:Ecosystem; D008274:Magnesium / Q000378:metabolism*; D008855:Microscopy, Electron, Scanning; D008903:Minerals / Q000378:metabolism*; D008906:Mining; D018547:Plant Stems / Q000378:metabolism*; D012987:Soil / Q000737:chemistry*; D013045:Species Specificity; D013455:Sulfur / Q000378:metabolism*
chemical_list: D008903:Minerals; D012987:Soil; D013455:Sulfur; D008274:Magnesium; D002118:Calcium
keywords: Acacia; Leguminosae; Mimosoideae; alkaline-earth metal; calcium; magnesium; mine-site rehabilitation; mineral precipitation; phyllode; siltstone; sulfur