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An Ozone-Low Temperature Interaction in Loblolly Pine (Pinus taeda L.)
Arthur H. Chappelka, John S. Kush, Ralph S. Meldahl and B. Graeme Lockaby
The New Phytologist
Vol. 114, No. 4 (Apr., 1990), pp. 721-726
Stable URL: http://www.jstor.org/stable/2556844
Page Count: 6
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Loblolly pine (Pinus taeda L.) seedlings from two families differing in ozone sensitivity, were exposed to ozone and acidic precipitation in modified open-top chambers, beginning in May of 1988. Visible injury (bleached needle tips) occurred after a late-season frost in April, 1989 on newly emerging (length ⩽ 5 cm) needles. After one week, needle tips turned brown and necrotic. Incidence of injury was recorded in April, May and June, 1989. Injury only occurred on trees exposed to ozone at above-ambient concentrations (1.7 and 2.5 x ambient), and was significantly greater in the ozone-sensitive family (GAKR 15-91) suggesting that this response is under some genetic control. Incidence of injury decreased with time and was more noticeable in the ozone-tolerant family (GAKR 15-23). There was no effect of acid rain, or interaction between ozone and acid rain, revealed by visible injury. In addition, experiments were conducted to determine if ozone and/or freezing temperatures enhanced electrolyte leakage. There were no differences observed in diffusate conductivity among treatments. These findings suggest that the observed injury was due to photo-oxidation induced by an ozone-low temperature interaction, and represent the first report of this type of injury in loblolly pine.
The New Phytologist © 1990 New Phytologist Trust