||Leaf Photosynthetic and Water Relations Responses for 'Valencia' Orange Trees Exposed to Oxidant Air Pollution.
Olszyk, D. M. ;
Takemoto, B. K. ;
Poe., M. ;
||Corvallis Environmental Research Lab., OR. ;California Univ., Riverside. Statewide Air Pollution Research Center.
Air pollution effects(Plants) ;
Citrus trees ;
Fruit crops ;
Seasonal variations ;
||Most EPA libraries have a fiche copy filed under the call number shown. Check with individual libraries about paper copy.
||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.
||Pub. in Environmental and Experimental Botany, v31 n4 p427-436 1991. See also PB90-115148. Prepared in cooperation with California Univ., Riverside. Statewide Air Pollution Research Center.
|NTIS Title Notes
||Reprint: Leaf Photosynthetic and Water Relations Responses for 'Valencia' Orange Trees Exposed to Oxidant Air Pollution.
||68A; 98D; 57C
||PC A03/MF A01