Matyssek R, Günthardt-Goerg M S, Maurer S, Keller T
Swiss Federal Institute of Forest, Snow and Landscape Research, Zürcherstrasse 111, CH-8903 Birmensdorf ZH, Switzerland.
Tree Physiol. 1995 Mar;15(3):159-65. doi: 10.1093/treephys/15.3.159.
For 20 weeks during the growing season, cuttings of one birch clone (Betula pendula Roth.) were exposed in the Birmensdorf fumigation chambers to O(3)-free air (control) or 75 nl O(3) l(-1). Ozone was supplied either from 1900 until 0700 h (nighttime regime), from 0700 until 1900 h (daylight regime), or all day (24-h regime). By autumn, reductions in whole-plant biomass production, root/shoot biomass and stem weight/length ratios were evident in all three O(3) regimes. The reductions in cuttings receiving the 24-h O(3) treatment were about twofold larger than in cuttings receiving the daylight O(3) treatment. Stomata were open at night, and stomatal conductance was about 50% of its maximum daytime value. We calculated that the rate of O(3) uptake into leaves in the dark approached 4 nmol m(-2) s(-1). Whole-plant production and carbon allocation were more sensitive to O(3) during the night than during the day; however, O(3) exposure caused similar visible leaf injury in both of the 12-h regimes, although the leaves exposed to O(3) at night exhibited delayed O(3)-induced shedding. Overall, changes in production and carbon allocation were determined by the external O(3) dose rather than by the kind of O(3) exposure, indicating that, at the seasonal scale, the internal dose of ozone that was physiologically effective was a constant fraction of the external O(3) dose. We conclude that nighttime O(3) exposures should be included in the daily time period for determining critical concentrations of O(3) causing injury in trees.
在生长季节的20周内，将一个桦树无性系（垂枝桦Betula pendula Roth.）的插条置于比尔门斯多夫熏蒸室内，分别暴露于无臭氧空气（对照）或75 nl O₃ l⁻¹的环境中。臭氧供应时间为1900至0700时（夜间模式）、0700至1900时（白天模式）或全天（24小时模式）。到秋季时，在所有三种臭氧模式下，整株植物的生物量生产、根/茎生物量以及茎重/长度比均明显下降。接受24小时臭氧处理的插条生物量下降幅度比接受白天臭氧处理的插条大约大一倍。气孔在夜间开放，气孔导度约为白天最大值的50%。我们计算得出，黑暗中叶片对臭氧的吸收速率接近4 nmol m⁻² s⁻¹。整株植物的生产和碳分配在夜间比白天对臭氧更敏感；然而，在两种12小时模式下，臭氧暴露均导致了类似的可见叶片损伤，尽管夜间暴露于臭氧的叶片出现臭氧诱导的落叶延迟现象。总体而言，生产和碳分配的变化取决于外部臭氧剂量，而非臭氧暴露的类型，这表明在季节尺度上，生理上起作用的臭氧内部剂量是外部臭氧剂量的一个恒定比例。我们得出结论，在确定导致树木损伤的臭氧临界浓度时，应将夜间臭氧暴露纳入每日时间段的考量范围。
