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Diurnal and seasonal comparisons of assimilation, phyllode conductance and water potential of three Acacia and one Eucalyptus species in the wet-dry tropics of Australia

Eamus, Derek and Cole, Stephen P. (1997). Diurnal and seasonal comparisons of assimilation, phyllode conductance and water potential of three Acacia and one Eucalyptus species in the wet-dry tropics of Australia. Australian Journal of Botany,45(2):275-290.

Document type: Journal Article
Citation counts: Scopus Citation Count Cited 57 times in Scopus Article | Citations

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Title Diurnal and seasonal comparisons of assimilation, phyllode conductance and water potential of three Acacia and one Eucalyptus species in the wet-dry tropics of Australia
Author Eamus, Derek
Cole, Stephen P.
Journal Name Australian Journal of Botany
Publication Date 1997
Volume Number 45
Issue Number 2
ISSN 0067-1924   (check CDU catalogue  open catalogue search in new window)
Scopus ID 2-s2.0-0030970363
Start Page 275
End Page 290
Total Pages 16
Place of Publication Melbourne
Publisher CSIRO Publishing
HERDC Category C1 - Journal Article (DEST)
Abstract Four species of tropical tree (Acacia auriculiformis Cunn. ex Benth., A. mangium Willd., A. crassicarpa Cunn. ex Benth. and Eucalyptus pellita F.Muell.) were studied at a site on Melville Island, off the north coast of the Northern Territory of Australia, in the wet–dry tropics. Rates of light-saturated assimilation were measured every 2 months, in the morning and afternoon, concurrently with gs (stomatal conductance) and microclimate (air temperature, relative humidity and photosynthetic photon flux density). Phyllodes were also sampled for subsequent nitrogen determination. Pre-dawn and diurnal phyllode water potentials were measured at the end of the wet and dry seasons. Tree height and canopy area were recorded at the end of 50 months of growth. Assimilation was found to decline substantially in the afternoon compared with the morning in the dry season but not the wet season. This was not due to diurnal declines in phyllode water potential but was attributed partially to decreased gs resulting from increased leaf-to-air vapour pressure difference. However, an interpretation of the Ci/Ca (ratio of internal to ambient CO2 concentrations) data suggested that additional factors, other than gs, may be involved in causing the afternoon decline in assimilation rate. There was a linear relationship between pre-dawn water potential and Amax (maximum assimilation) and an inverse relationship between Amax and tree height, a result attributed to differences between species in allocation of carbon within the tree.
DOI http://dx.doi.org/10.1071/BT96020   (check subscription with CDU E-Gateway service for CDU Staff and Students  check subscription with CDU E-Gateway in new window)
 
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