Eight Bush Blue Lake type snap bean (Phaseolus vulgaris L.) lines and cultivars with similar genetic backgrounds were container-grown to green-pod maturity in open-top field chambers while being exposed to chronic doses of 03 for 7 hours·day-1 for 42 consecutive days. Treatments included charcoal-filtered air, nonfltered air, and 0.02, 0.04, or 0.08 ppm O3 added to nonfiltered air. Visible injury was estimated during the 2nd week of exposure and compared to the green pod yield data. The presence of four yield response groups, as determined via regression analysis, indicated the presence of variation for 03 sensitivity in the germplasm pool, but all eight lines were O3 - sensitive with yield losses at 03 levels exceeding a 7-hour daily mean of 0.085 ppm. Foliar injury may be a good indicator of general yield loss; however, estimates of visible injury lack the precision necessary to distinguish subtle differences among a collection of O3-sensitive snap bean lines.
Foliage of field-grown muskmelon (Cucumis melo L. var. reticulatus Ser.) is susceptible to injury induced by ambient concentrations of ozone. Foliar injury symptoms consisted of interveinal chlorosis of the adaxial surface of the leaf tissue followed by bleaching of the foliage and necrosis. Fully mature leaves were affected more than younger leaves. Controlled fumigations of muskmelon plants with known concentrations of ozone produced foliar symptoms identical to those observed in the field. A differential cultivar response to ozone is reported and potentially tolerant genotypes are identified.
Foliage of watermelon [Citrullus lanatus (Thunb.) Matsum & Nakai] is susceptible to injury induced by ambient concentrations of ozone. Injury symptoms consisted of a premature chlorotic mottle of leaf tissue, followed by stippling and bleaching of the foliage, and necrosis. Older, more mature leaves were more affected than younger leaves. There was a differential cultivar response to ozone, which identified potential insensitive genotypes.