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Stomatal Conductance, Fleck Injury, and Growth of Tobacco Cultivars Varying in Ozone Tolerance. Neil C. Turner, The Connecticut Agricultural Experiment Station, P. O. Box 1106, New Haven 06504; Saul Rich(2), and Harley Tomlinson(3). (2)(3)The Connecticut Agricultural Experiment Station, P. O. Box 1106, New Haven 06504. Phytopathology 62:63-67. Accepted for publication 26 July 1971. DOI: 10.1094/Phyto-62-63.

Four tobacco (Nicotiana tabacum) cultivars that vary in ozone sensitivity were grown in the field and in two greenhouses, one with charcoal-filtered air and one with unfiltered air. The plants were compared for stomatal conductance, stomatal frequency, height, oven-dry weight, leaf area, and amount of fleck injury. The total leaf conductance, measured with a ventilated diffusion porometer, of the ozone-sensitive cultivars was greater than that of the ozone-tolerant cultivars; both adaxial and abaxial conductances were greater. However, the differences in stomatal conductance were not sufficient to account completely for the differences in fleck damage. In ozone-free air, the two ozone-sensitive cultivars grew more than did the two ozone-tolerant cultivars. The converse was true when the plants were grown in unfiltered air. The reduction of dry weight in the unfiltered air accompanied a reduction in the green leaf area caused by flecking and early senescence of damaged leaves.