Effects of Ozone or Sulfur Dioxide on Pitch Pine Seedlings
1989
Scherzer, Amy J. | McClenahen, James R.
Pitch pine seedlings (Pinus rigida Mill.) were fumigated with O₃ or SO₂ to determine their effects on growth and symptom expression. Seedlings fumigated twice with 0.20 µL O₃ L⁻¹ for 4 hr at age 14 and 22 wk had significantly greater shoot weight than those fumigated with 0.30 µL O₃ L¹; 0, 0.08, 0.10, and 0.15 µL L¹ were intermediate and not significantly different. Root starch content tended to decrease with increasing O₃ with control seedlings being significantly higher than the 0.15, 0.20, and 0.30 µL O₃ L⁻¹ treatments. Root starch of seedlings treated with 0.20, 0.50, 0.60, 0.70, and 0.90 µL SO₂ L⁻¹ was significantly lower than the controls. Seedlings from six families fumigated for 5 wk starting at age 6 wk differed in direction and degree of growth response when exposed to 0.08 and 0.30 µL O₃ L¹. Significant differences exited among families for needle weight, shoot weight, and total weight. No differences were found among O₃ treatments within a family, but patterns suggest some pitch pine individuals may be sensitive to low O₃ while others are stimulated. Visible injury consisted of light chlorotic mottle on oldest needles. Discriminant function analysis indicated that growth responses were indistinguishable among families receiving no treatment; however, treated seedlings could be classified based on various height measurements and/or shoot weight. Differences in visible injury were apparent among families of seedlings treated with 0.40 µL O₃ L¹, indicating some pitch pine families are more sensitive to O₃ than others. Salaries and research support provided by state and federal funds appropriated to the Ohio State Univ., and by a grant from Am. Electric Power Corp., Columbus, OH. Journal article no. 23-88.
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