Photosynthetic characteristics in wheat exposed to elevated O{sub 3} and CO{sub 2}
- Brazilian National Inst. for Space Research, Sao Jose dos Campos (Brazil)
- Univ. of Maryland, College Park, MD (United States)
- USDA Beltsville Agricultural Research Center, MD (United States)
Tropospheric trace gases such as CO{sub 2} and O{sub 3} have progressively increased over the past century and are predicted to increase to levels at which they may have a significant impact on agricultural production. The effects of CO{sub 2} enrichment and O{sub 3} air pollution on leaf photosynthesis (P{sub n}) and stomatal conductance (g{sub s}) were investigated. Two soft red winter wheat cultivars, Massey in 1991 and Saluda in 1992, were studied in field experiments at Beltsville, MD, by means of open-top chambers to mimic atmospheric environments predicted for the first half of the 21st century. Plants were exposed to two levels of O{sub 3} (charcoal filtered air and ambient air + an average of 40 nmol O{sub 3} mol{sup {minus}1} from Monday-Friday of every week). Ozone treatments were superimposed on two CO{sub 2} treatments (350 {mu}mol CO{sub 2} mol{sup {minus}1} and 500 {mu}mol CO{sub 2} mol{sup {minus}1}). Averaged over O{sub 3} treatments, P{sub n} was stimulated during the early and late growing season under enriched CO{sub 2}. Averaged over CO{sub 2} treatments, high O{sub 3} exposure had a negative impact on P{sub n} early in the season of 1992 and a major impact late in the season of 1991 and 1992 due to premature senescence. Decreases in g{sub s} occurred under the enrichment CO{sub 2} environment and to a lesser extent with high O{sub 3}. Interactive effects on P{sub n} and g, were mostly absent. It is likely that if CO{sub 2} and O{sub 3} concentrations continue to increase, the beneficial effect of CO{sub 2} enrichment on P{sub n} may be partially negated by O{sub 3}-induced stress. Conversely, damaging effects of O{sub 3} on P{sub n} may be compensated by elevated atmospheric CO{sub 2}. 39 refs., 1 fig., 6 tabs.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 508592
- Journal Information:
- Crop Science, Journal Name: Crop Science Journal Issue: 5 Vol. 36; ISSN 0011-183X; ISSN CRPSAY
- Country of Publication:
- United States
- Language:
- English
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