Journal article
Growth efficiency increases as relative growth rate increases in shoots and roots of Eucalyptus globulus deprived of nitrogen or treated with salt
Tree Physiology, Vol.25(5), pp.571-582
2005
Abstract
We used calorimetry to test whether there is a single general relationship between growth and respiration in shoots and roots of Eucalyptus globulus Labill. seedlings when stressed, irrespective of the type or severity of stress. We found that nitrogen (N) deprivation and salt treatment had no effect on the relationship between growth and respiration and little effect on absolute rates of respiration. Carbon-conversion efficiency (εC) ranged from 0.7 to 0.9 for specific growth rates (RSG) greater than 0.3 day-1. Above an RSG of 0.1 day-1, εC decreased gradually with decreasing RSG and between an RSG of 0-0.1 day-1, εC decreased rapidly. We conclude that the relationship between εC and RSG is not greatly affected by salt or N-deprivation stresses. Relationships between gross productivity and εC may be generally applicable, in which case they could improve on the "flat-tax" approach to modeling net primary productivity from gross productivity while avoiding the complexity of more explicit models of plant respiration. However, the relationship between gross productivity and εC was sensitive to temperature and the effect of temperature on εC thus requires further investigation. Nitrogen deprivation caused large decreases in leaf area and shoot to root ratio, and mature leaves of N-deprived plants had lower intrinsic water-use efficiencies than leaves of plants well supplied with nutrients. Nitrogen deprivation increased apical dominance and most of the reduction in leaf area was the result of fewer secondary branches, although leaf size was also reduced. Our results suggest that N deprivation reduces productivity primarily by reducing sink size, rather than sink activity, and that apical dominance may be an important mechanism for maintaining adequate εC in resource-limited conditions.
Details
- Title
- Growth efficiency increases as relative growth rate increases in shoots and roots of Eucalyptus globulus deprived of nitrogen or treated with salt
- Authors
- Craig MacFarlane (Author) - University of Western AustraliaLee D Hansen (Author) - Brigham Young University, United StatesJustine Edwards (Author) - University of Western AustraliaDonald A White (Author) - CSIRO Forestry and Forest ProductsMark A Adams (Author) - University of Western Australia
- Publication details
- Tree Physiology, Vol.25(5), pp.571-582
- Publisher
- Oxford University Press
- Date published
- 2005
- DOI
- 10.1093/treephys/25.5.571
- ISSN
- 0829-318X
- Organisation Unit
- University of the Sunshine Coast, Queensland; Forest Industries Research Centre; Forest Research Institute
- Language
- English
- Record Identifier
- 99451193002621
- Output Type
- Journal article
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