© 2001 Heron Publishing—Victoria, Canada
Atmospheric carbon dioxide, irrigation, and fertilization effects on phenolic and nitrogen concentrations in loblolly pine
(Pinus taeda) needles
Fitzgerald L. Booker (1) and Christopher A. Maier (2)
1. U.S. Department of Agriculture, Agricultural Research Service, Air Quality – Plant Growth and Development Research Unit, and
Department of Crop Science, North Carolina State University, 3908 Inwood Road, Raleigh, NC 27603, USA / 2. U.S. Department of Agriculture, Forest Service, Southern Research Station, PO Box 12254, Research Triangle Park, NC 27709,
USA / Received April 7, 2000
Summary
Concentrations of total soluble phenolics, catechin, proanthocyanidins (PA), lignin and nitrogen (N) were measured in loblolly
pine (Pinus taeda L.) needles exposed to either ambient CO2 concentration ([CO2]), ambient plus 175 or ambient plus 350 μmol CO2 mol–1 in branch chambers for 2 years. The CO2 treatments were superimposed on a 2 × 2 factorial combination of irrigation and fertilization treatments. In addition, we
compared the effects of branch chambers and open-top chambers on needle chemistry. Proanthocyanidin and N concentrations were
measured in needles from branch chambers and from trees in open-top chambers exposed concurrently for 2 years to either ambient
[CO2] or ambient plus 200 μmol CO2 mol–1 in combination with a fertilization treatment. In the branch chambers, concentrations of total soluble phenolics in needles
generally increased with needle age. Concentrations of total soluble phenolics, catechin and PA in needle extracts increased
about 11% in response to the elevated [CO2] treatments. There were no significant treatment effects on foliar lignin concentrations. Nitrogen concentrations were about
10% lower in needles from the elevated [CO2] treatments than in needles from the ambient [CO2] treatments. Soluble phenolic and PA concentrations were higher in the control and irrigated soil treatments in about half
of the comparisons; otherwise, differences were not statistically significant. Needle N concentrations increased 23% in response
to fertilization. Treatment effects on PA and N concentrations were similar between branch and open-top chambers, although
in this part of the study N concentrations were not significantly affected by the CO2 treatments in either the branch or open-top chambers. We conclude that elevated [CO2] and low N availability affected foliar chemical composition, which could in turn affect plant–pathogen interactions, decomposition
rates and mineral nutrient cycling.
Keywords:
catechin, CO2 enrichment, lignin, nutrition, proanthocyanidins, secondary compounds, tannins.
