You are here:
LEAF PHOTOSYNTHETIC AND WATER RELATIONS RESPONSES FOR "VALENCIA" ORANGE TREES EXPOSED TO OXIDANT AIR POLLUTION
Citation:
Olszyk, D., B. Takemoto, AND M. Poe. LEAF PHOTOSYNTHETIC AND WATER RELATIONS RESPONSES FOR "VALENCIA" ORANGE TREES EXPOSED TO OXIDANT AIR POLLUTION. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-92/093.
Description:
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 exposed to ambient oxidant air pollution. xposures were continuous for four years to three levels of oxidants. xidants had no effect on net leaf photosynthetic rates or on photosynthetic pigment concentrations. ingle set of measurements indicated that oxidants increased leaf starch concentrations (24%) prior to flowering, suggesting a change in photosynthate allocation. eaves exposed to oxidants had small, but consistent, changes in water relations over the summer growing season, compared to trees growing in filtered air. ther changes included decreased stomatal conductance (12%) and transpiration (9%) rates, and increased water pressure potentials (5%). hile all responses were subtle, their cumulative impact over, four years indicated that "Valencia" orange trees were subject to increased ambient oxidant stress.