Variation among Fraxinus families in foliar response to ozone

Abstract

Seedlings representing 10 open-pollinated families of Fraxinuspennsylvanica Marsh, and 2 of F. americana L. were exposed to 490 μg/m³ ozone (0.25 ppm) for 6 h at 24 °C and 75% relative humidity. At time of exposure, the seedlings were approximately 2 months old from seed and had three or four pairs of primary leaves. Both percentage of leaf surface injury and kind of injury varied significantly among families of the same and different species and between pairs of leaves at different nodal positions. Results reveal that total foliar ozone injury may be a complex of genetically independent symptom responses that should be distinguished in future studies of the genetics of ozone resistance.