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This article in CS

  1. Vol. 36 No. 5, p. 1247-1251
     
    Received: Mar 6, 1995
    Published: Sept, 1996


    * Corresponding author(s): cm48@umail.umd.edu
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doi:10.2135/cropsci1996.0011183X003600050029x

Photosynthetic Characteristics in Wheat Exposed to Elevated O3 and CO2

  1. B. F. T. Rudorff,
  2. C. L. Mulchi ,
  3. E. Lee,
  4. R. Rowland and
  5. R. Pausch
  1. B razilian National Institute for Space Research, Div. of Remote Sensing, C.P. 515, 12201-970 Sáo José dos Campos, SP, Brazil
    D ep. of Agronomy, H.J. Patterson Hall, Univ. of Maryland, College Park, MD 20742

Abstract

Abstract

Tropospheric trace gases such as CO2 and O3 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 CO2 enrichment and O3 air pollution on leaf photosynthesis (Pn) and stomatal conductance (g5) were investigated. Two soft winter wheat (Triticum aestivum L.) 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 O3 (charcoal filtered air and ambient air + an average of 40 nmol O3 mol−1 from Monday–Friday of every week). Ozone treatments were superimposed on two CO2 treatments (350 μmol CO2 mol and 500 μmol CO2 mol−1). Averaged over O3 treatments, Pn was stimulated during the early and late growing season under enriched CO2. Averaged over CO2 treatments, high O3 exposure had a negative impact on Pn early in the season of 1992 and a major impact late in the season of 1991 and 1992 due to premature senescence. Decreases in gs occurred under the enriched CO2 environment and to a lesser extent with high O3. Interactive effects on Pn and gs were mostly absent. It is likely that if CO2 and O3 concentrations continue to increase, the beneficial effect of CO2 enrichment on Pn may be partially negated by O3-induced stress. Conversely, damaging effects of O3 on Pn may be compensated by elevated atmospheric CO2.

Contribution of the Maryland Agric. Exp. Stn. Scientific article no. A6668, contribution no. 8887.

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