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This article in JEQ

  1. Vol. 14 No. 1, p. 55-60
     
    Received: Mar 5, 1984


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doi:10.2134/jeq1985.00472425001400010010x

Cotton Yield Responses to Ozone as Mediated by Soil Moisture and Evapotranspiration1

  1. Patrick J. Temple,
  2. O. Clifton Taylor and
  3. Lawrence F. Benoit2

Abstract

Abstract

A 2-yr field study was conducted to determine injury and yield responses of normally irrigated and water-stressed cotton (Gossypium hirsutum L.) to a gradient of ozone (O3) concentrations. Cotton (cv. SJ-2), grown in open-top chambers in the Central Valley of California, was exposed to six O3 treatments ranging from charcoal-filtered (CF) to ambient plus 0.10 µL L−1 O3 (1981) or twice ambient O3 concentrations (1982) for the growing seasons of 1981 and 1982. Half the plots were irrigated optimally and the other half were provided with 25% (1981) or 20% (1982) less irrigation water (water-stressed treatment). During the typically hot, dry growing season of 1981, cotton yield in normally irrigated treatments was reduced 20% by ambient levels of O3 in nonfiltered chambers (NF) relative to CF controls. Doubling ambient O3 concentration reduced yield 45%. Water-stressed plants showed almost no response to O3. In 1982, the weather was cooler and cloudier than normal and potential evapotranspiration during the growing season averaged 20% less and ambient O3 concentrations averaged 39% lower than in 1981. Under these conditions, cotton yields at both levels of soil moisture treatments responded similarly to O3. Yields in NF chambers were reduced 15% relative to CF chambers. Doubling ambient O3 concentrations reduced yields 65%. The greater relative response of cotton to O3 in 1982 may have resulted from the cooler, more humid growing conditions, which increased the susceptibility of cotton to O3.

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