Kytöviita Minna-Maarit, Le Thiec Didier, Dizengremel Pierre
Department of Biology, Oulu University, PL 3000, FIN-90401 Oulu, Finland; Laboratoire de Biologie Forestière, Associé INRA, Université Henri Poincaré-Nancy I, BP 239, F-54506 Vandoeuvre-lès-Nancy, France; INRA-Centre de Recherches Forestières, Unité Ecophysiologie Forestière-Laboratoire de Pollution Atmosphérique, F-54280 Champenoux, France.
Physiol Plant. 2001 Mar;111(3):305-312. doi: 10.1034/j.1399-3054.2001.1110307.x.
The effects of 700 µmol mol-1 CO2 and 200 nmol mol-1 ozone on photosynthesis in Pinus halepensis seedlings and on N translocation from its mycorrhizal symbiont, Paxillus involutus, were studied under nutrient-poor conditions. After 79 days of exposure, ozone reduced and elevated CO2 increased net assimilation rate. However, the effect was dependent on daily accumulated exposure. No statistically significant differences in total plant mass accumulation were observed, although ozone-treated plants tended to be smaller. Changes in atmospheric gas concentrations induced changes in allocation of resources: under elevated ozone, shoots showed high priority over roots and had significantly elevated N concentrations. As a result of different shoot N concentration and net carbon assimilation rates, photosynthetic N use efficiency was significantly increased under elevated CO2 and decreased under ozone. The differences in photosynthesis were mirrored in the growth of the fungus in symbiosis with the pine seedlings. However, exposure to CO2 and ozone both reduced the symbiosis-mediated N uptake. The results suggest an increased carbon cost of symbiosis-mediated N uptake under elevated CO2, while under ozone, plant N acquisition is preferentially shifted towards increased root uptake.
在营养贫瘠条件下，研究了700微摩尔每摩尔二氧化碳和200纳摩尔每摩尔臭氧对阿勒颇松幼苗光合作用以及从其菌根共生体卷缘桩菇的氮转运的影响。暴露79天后，臭氧降低而二氧化碳升高使净同化率提高。然而，该效应取决于每日累积暴露量。尽管经臭氧处理的植株往往较小，但未观察到植株总质量积累有统计学显著差异。大气气体浓度的变化引起资源分配的改变：在臭氧浓度升高时，地上部分相对于根系具有更高优先级，且氮浓度显著升高。由于地上部分氮浓度和净碳同化率不同，二氧化碳浓度升高时光合氮利用效率显著提高，而臭氧浓度升高时则降低。光合作用的差异反映在与松树苗共生的真菌生长上。然而，暴露于二氧化碳和臭氧均降低了共生介导的氮吸收。结果表明，在二氧化碳浓度升高时，共生介导的氮吸收的碳成本增加，而在臭氧浓度升高时，植物氮获取优先转向增加根系吸收。
