Visser A J, Tosserams M, Groen M W, Magendans G W, Rozema J
Department of Ecology and Ecotoxicology, Vrije Universiteit, Amsterdam, The Netherlands.
Plant Cell Environ. 1997;20(2):189-99. doi: 10.1046/j.1365-3040.1997.d01-64.x.
The response of faba bean seedlings to the combined effects of increased atmospheric CO2 concentrations ([CO2]) and solar UV-B irradiance was studied using open-top chambers transparent to UV-B radiation. The purpose of the study was to determine whether effects of increased [CO2] on growth and physiology are modified by the present solar UV-B fluence rate in the Netherlands. Seedlings were exposed to 350 or 700 micromoles mol-1 CO2. At both [CO2], solar UV-B irradiance was either present or reduced using polyester foil opaque to UV-B radiation. To obtain information on the time dependence of increased [CO2] and UV-B radiation effects, three harvests were performed during the experiment. CO2 enrichment resulted in increased biomass production at all harvests. At the final harvest, UV-B radiation did not affect biomass production but a significant decrease was observed after 14 d of treatment. A reduction of the UV-B fluence increased shoot length at both [CO2] throughout the experiment. UV-B radiation slightly altered biomass allocation. Plants grown at reduced levels of UV-B radiation invested less biomass in flowers and more in stem material compared to plants grown at ambient UV-B levels. CO2 enrichment resulted in a stimulation of net photosynthesis after 26 and 38 d of treatment. UV-B reduction did not alter this response. After 26 d of treatment, photosynthetic acclimation to CO2 enrichment was observed, which was probably the result of accumulation of carbohydrates in the leaves. After 38 d, photosynthetic acclimation was no longer present. The UV absorbance of methanolic leaf extracts was increased by CO2 enrichment only. Both CO2 enrichment and solar UV-B reduced the transmittance of radiation through intact attached leaves. Interaction between [CO2] and UV-B radiation was limited to UV-A transmittance of leaves. Under prevalent experimental conditions, UV-B radiation did not affect the measured physiological parameters. Most open-top chambers used for climate change research are constructed of materials which do not transmit UV-B radiation. Our results indicate that part of the 'chamber effects' on plant height often described in the literature might be explained by the absence of solar UV-B radiation in these chambers.
利用对UV-B辐射透明的开顶式气室，研究了蚕豆幼苗对大气CO2浓度（[CO2]）升高和太阳UV-B辐照度综合作用的响应。该研究的目的是确定在荷兰当前的太阳UV-B通量率下，[CO2]升高对生长和生理的影响是否会发生改变。幼苗暴露于350或700微摩尔每摩尔的CO2浓度下。在这两种[CO2]浓度下，太阳UV-B辐照度要么保持自然水平，要么使用对UV-B辐射不透明的聚酯薄膜进行削减。为了获取有关[CO2]升高和UV-B辐射效应的时间依赖性信息，在实验过程中进行了三次收获。CO2浓度升高导致在所有收获期生物量产量增加。在最终收获时，UV-B辐射并未影响生物量产量，但在处理14天后观察到显著下降。在整个实验过程中，削减UV-B通量均增加了两种[CO2]浓度下植株的茎长。UV-B辐射略微改变了生物量分配。与在自然UV-B水平下生长的植株相比，在较低UV-B辐射水平下生长的植株在花上投入的生物量较少，而在茎干物质上投入的较多。CO2浓度升高导致在处理26天和38天后净光合作用增强。UV-B辐射削减并未改变这种响应。处理26天后，观察到光合作用对CO2浓度升高的适应性变化，这可能是叶片中碳水化合物积累的结果。38天后，不再存在光合作用适应性变化。仅CO2浓度升高增加了甲醇叶提取物的紫外线吸收率。CO2浓度升高和太阳UV-B辐射均降低了通过完整附着叶片的辐射透过率。[CO2]和UV-B辐射之间的相互作用仅限于叶片的UV-A透过率。在普遍的实验条件下
