Patterns of stable carbon isotope discrimination (. delta. sup 13 C) in pinus taeda as a function of ozone stress

Journal Article · Sat Apr 01 04:00:00 EST 1989 · Plant Physiology, Supplement; (USA)

OSTI ID:6936449

Taylor, Jr, G E; Gunderson, C A; Edwards, N T ^[1]

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1. Oak Ridge National Lab., TN (USA)

This research tested the hypothesis that ozone stress shifts the isotopic composition of carbon ({delta}{sup 13}C) in needles of Pinus taeda L. (loblolly pine) seedlings grown under realistic field conditions using open top chambers. Three different ozone exposure regimes were maintained for two growing seasons. At the end of the second year, foliage exhibited two statistically significant patterns in {delta}{sup 13}C values: (1) a decrease (more negative) from -24.86 to -28.16 per mil with needle age and (2) an increase from -27.15 to -25.95 per mil with increasing ozone stress. Whereas all needle age classes exhibited the same response as a function of ozone stress, the most pronounced shift in {delta}{sup 13}C was in the youngest age class. In conjunction with intensive gas-exchange studies, the direction and magnitude of the shift in response to ozone indicates that the pollutant's effects on foliar gas-exchange processes are greater on stomatal physiology than on carbon dioxide assimilation. Consequently, it is proposed that one of the seasonally integrated effects of elevated levels of ozone stress on foliage of P. taeda is lower stomatal conductance to water vapor and thus more efficient water use. An untested corollary is that seedlings grown at ambient levels of ozone stress are more susceptible to drought than their counterparts grown at elevated levels of ozone.

• OSTI ID: 6936449
• Journal Information: Plant Physiology, Supplement; (USA), Journal Name: Plant Physiology, Supplement; (USA) Vol. 89:4; ISSN PPYSA; ISSN 0079-2241
• Country of Publication: United States
• Language: English

Related Subjects

560300* -- Chemicals Metabolism & Toxicology
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
CARBON 13
CARBON ISOTOPES
CONIFERS
DROUGHTS
EVEN-ODD NUCLEI
EXPOSURE CHAMBERS
ISOTOPES
LEAVES
LIGHT NUCLEI
NUCLEI
OPENINGS
OZONE
PINES
PINOPHYTA
PLANTS
SEEDLINGS
STABLE ISOTOPES
STOMATA
TOXICITY
TREES