Document Detail

Foliar delta(13)C and delta(18)O reveal differential physiological responses of canopy foliage to pre-planting weed control in a young spotted gum (Corymbia citriodora subsp. Variegata) plantation.
MedLine Citation:
PMID:  18708335     Owner:  NLM     Status:  MEDLINE    
Weed control may improve the growth of forest plantations by influencing soil water and nutrient availability, but our knowledge of leaf-level physiological responses to weed control at different within-canopy positions is limited for tropical and subtropical plantations. Foliar carbon (delta(13)C) and oxygen (delta(18)O) isotope compositions, gas exchange, and nitrogen (N(mass)) and phosphorus (P(mass)) concentrations at four canopy positions were assessed in a young spotted gum (Corymbia citriodora subsp. Variegata (F. Muell.) A.R. Bean & M.W. McDonald) plantation subjected to either weed control or no weed control treatment, to test if leaves at different positions within the tree canopy had the same physiological responses to the weed control treatment. Weed control increased foliar delta(13)C but lowered delta(18)O in the upper-outer and upper-inner canopy, indicating that weed control resulted in a higher foliar photosynthetic capacity at upper-canopy positions, a conclusion confirmed by gas exchange measurements. The increased photosynthetic capacity resulting from weed control can be explained by an increase in foliar N(mass). In the lower-outer canopy, weed control reduced foliar delta(13)C while lowering delta(18)O even more than in the upper-canopy, suggesting strong enhancement of the partial pressure of CO(2) in the leaf intercellular spaces and of foliar stomatal conductance in lower-canopy foliage. This conclusion was supported by gas exchange measurements. Foliar photosynthesis in the lower-inner canopy showed no significant response to weed control. The finding that leaves at different canopy positions differ in their physiological responses to weed control highlights the need to consider the canopy position effect when examining competition for soil nutrient and water resources between weeds and trees.
Zhiqun Huang; Zhihong Xu; Timothy J Blumfield; Ken Bubb
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Tree physiology     Volume:  28     ISSN:  0829-318X     ISO Abbreviation:  Tree Physiol.     Publication Date:  2008 Oct 
Date Detail:
Created Date:  2008-08-18     Completed Date:  2008-12-11     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100955338     Medline TA:  Tree Physiol     Country:  Canada    
Other Details:
Languages:  eng     Pagination:  1535-43     Citation Subset:  IM    
Griffith School of Environment, Griffith University, Nathan, QLD 4111, Australia.
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MeSH Terms
Carbon / metabolism*
Carbon Isotopes
Herbicides / pharmacology*
Myrtaceae / anatomy & histology,  drug effects,  physiology*
Nitrogen / metabolism
Oxygen / metabolism*
Oxygen Isotopes
Photosynthesis / drug effects
Plant Leaves / metabolism*
Trees / anatomy & histology,  drug effects,  physiology
Reg. No./Substance:
0/Carbon Isotopes; 0/Herbicides; 0/Oxygen Isotopes; 7440-44-0/Carbon; 7727-37-9/Nitrogen; 7782-44-7/Oxygen

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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