Record Display for the EPA National Library Catalog


OLS Field Name OLS Field Data
Main Title Leaf Photosynthetic and Water Relations Responses for 'Valencia' Orange Trees Exposed to Oxidant Air Pollution.
Author Olszyk, D. M. ; Takemoto, B. K. ; Poe., M. ;
CORP Author Corvallis Environmental Research Lab., OR. ;California Univ., Riverside. Statewide Air Pollution Research Center.
Publisher c1991
Year Published 1991
Report Number EPA/600/J-92/092;
Stock Number PB92-153857
Additional Subjects Photosynthesis ; Air pollution effects(Plants) ; Citrus trees ; Leaves(Botany) ; Water ; Fruit crops ; Oxidants ; Seasonal variations ; Pigments ; Starches ; Transpiration ; Reprints ;
Library Call Number Additional Info Location Last
NTIS  PB92-153857 Most EPA libraries have a fiche copy filed under the call number shown. Check with individual libraries about paper copy. 08/28/1992
Collation 11p
Leaf responses were measured to test a hypothesis that reduced photosynthetic capacity and/or altered water relations were associated with reductions in yield for 'Valencia' orange trees (Citrus sinensis (L.), Osbeck) exposed to ambient oxidant air pollution. Exposures were continuous for 4 years to three levels of oxidants (in charcoal-filtered, half-filtered, and non-filtered air). Oxidants had no effect on net leaf photosynthetic rates or on photosynthetic pigment concentrations. A single set of measurements indicated that oxidants increased leaf starch concentrations (24%) prior to flowering, suggesting a change in photosynthate allocation. Leaves exposed to oxidants had small, but consistent, changes in water relations over the summer growing season, compared to trees growing in filtered air. Other changes included decreased stomatal conductance (12%) and transpiration (9%) rates, and increased water pressure potentials (5%). While all responses were subtle, their cumulative impact over 4 years indicated that 'Valencia' orange trees were subject to increased ambient oxidant stress.