Chronic Ozone Exposure and Photosynthate Partitioning into Starch in Soybean Leaves

Photosynthesis, photosynthate partitioning, and translocation are reportedly affected by ozone (O3), but the sensitivity of these processes in relation to other potential targets is not known. In this study, rates of net photosynthetic CO2 assimilation (Pn) and carbohydrate accumulation in fully expanded leaves in soybean canopies in the field were examined following season-long exposure either to low-O3 conditions (20-30 nL L(-1) 7-h daily average, charcoal-filtered air) or to chronic midlevel concentrations (50-60 nL L(-1), ambient air plus supplemental O3).