Smeulders S M, Gorissen A, Joosten N N, VAN Veen J A
DLO-Research Institute for Agrobiology and Soil Fertility (AB-DLO), P.O. Box 14, 6700 A A Wageningen, The Netherlands.
New Phytol. 1995 Jan;129(1):45-53. doi: 10.1111/j.1469-8137.1995.tb03008.x.
Effects of short-term ozone exposure of mature trees were compared with those of seedlings. Both 25-yr-old Douglas firs [Pseudotsuga menziesii (Mirb.) Franco] and 3-yr-old Douglas fir seedlings were exposed to 0, 200 and 400 μgm ozone for about 1.5 wk and then labelled with CO to study the effect on net photosynthesis, translocation and partitioning of assimilates. In the seedling experiment, two identical growth cabinets with separated shoot and root compartments were used for ozone fumigation and C-labelling. Seedlings were harvested and C contents in the needles (subdivided into starch, ethanol-soluble and residue fractions), branches, roots, root/soil respiration and soil residue were determined, together with the total starch content of the needles. Ozone increased the retention of C-photosynthates in the needles. Translocation of carbon to the branches and roots seemed to be inhibited by the highest ozone treatment. The increased C-retention was mainly recovered in the residue fraction of the needles. Total starch content of the needles decreased in the highest ozone treatment. In the experiment with mature trees, terminal shoots were fumigated with ozone and labelled with C using three small branch chambers. Carbon distribution was studied after harvest of the branches. Total C contents in the needle fractions and the branches were determined, together with the total starch content of the needles. Ozone was found to inhibit net CO assimilation as well as translocation of C-labelled assimilates from exposed needles to the branch. No effects of ozone were found on the partitioning of C among the starch, ethanol-soluble, and residue fractions of the needles, although amounts in the ethanol-soluble fraction tended to increase after exposure to ozone. The results indicate that mature and juvenile Douglas firs respond in a similar way to short-term ozone exposure with regard to carbon translocation. If this similarity also applies to other species, then results from phytotron experiments on ozone and translocation of carbon might gain importance with respect to extrapolation to forest ecosystems.
将成熟树木短期暴露于臭氧环境下的影响与幼苗的情况进行了比较。25年生的花旗松[北美黄杉（Pseudotsuga menziesii (Mirb.) Franco）]和3年生的花旗松幼苗都被暴露于0、200和400微克/立方米的臭氧环境中约1.5周，然后用¹⁴CO₂进行标记，以研究对净光合作用、同化物的转运和分配的影响。在幼苗实验中，使用两个带有分隔的地上部和根部隔室的相同生长箱进行臭氧熏蒸和¹⁴C标记。收获幼苗后，测定针叶（细分为淀粉、乙醇可溶性和残渣部分）、树枝、根部、根/土壤呼吸和土壤残渣中的¹⁴C含量，以及针叶的总淀粉含量。臭氧增加了¹⁴C光合产物在针叶中的滞留。向树枝和根部的碳转运似乎受到最高臭氧处理的抑制。增加的¹⁴C滞留主要在针叶的残渣部分中恢复。在最高臭氧处理下，针叶的总淀粉含量下降。在成熟树木的实验中，使用三个小树枝室对顶梢进行臭氧熏蒸并用¹⁴C进行标记。收获树枝后研究碳分布。测定针叶部分和树枝中的总¹⁴C含量，以及针叶的总淀粉含量。发现臭氧抑制净CO₂同化以及¹⁴C标记的同化物从暴露的针叶向树枝的转运。尽管暴露于臭氧后乙醇可溶性部分的量有增加的趋势，但未发现臭氧对针叶中淀粉、乙醇可溶性和残渣部分之间的碳分配有影响。结果表明，在碳转运方面，成熟和幼年花旗松对短期臭氧暴露的反应相似。如果这种相似性也适用于其他物种，那么关于臭氧和碳转运的植物生长箱实验结果对于推断森林生态系统可能会变得更加重要。
