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Abstract
We tested the effect of daytime chronic moderate ozone (O
3) exposure, short-term acute exposure, and both chronic and acute O
3 exposure combined on nocturnal transpiration in California black oak and blue oak seedlings. Chronic O
3 exposure (70 ppb for 8 h/day) was implemented in open-top chambers for either 1 month (California black oak) or 2 months (blue oak). Acute O
3 exposure (~1 h in duration during the day, 120–220 ppb) was implemented in a novel gas exchange system that supplied and maintained known O
3 concentrations to a leaf cuvette. When exposed to chronic daytime O
3 exposure, both oaks exhibited increased nocturnal transpiration (without concurrent O
3 exposure) relative to unexposed control leaves (1.8× and 1.6×, black and blue oak, respectively). Short-term acute and chronic O
3 exposure did not further increase nocturnal transpiration in either species. In blue oak previously unexposed to O
3, short-term acute O
3 exposure significantly enhanced nocturnal transpiration (2.0×) relative to leaves unexposed to O
3. California black oak was unresponsive to (only) short-term acute O
3 exposure. Daytime chronic and/or acute O
3 exposures can increase foliar water loss at night in deciduous oak seedlings.
Citation
Grulke, N. E.; Paoletti, E.; Heath, R. L. 2007. Chronic
vs. Short-Term Acute O
3 Exposure Effects on Nocturnal Transpiration in Two Californian Oaks . The Scientific World JOURNAL. 7: 134-140. https://doi.org/10.1100/tsw.2007.33.
