Barnes J D, Pfirrmann T
Department of Agricultural & Environmental Science, Ridley Building, The University, Newcastle upon Tyne NE1 7RU, UK.
GSF München, Ingolstädter Landstraße 1, D-8042, Neuherberg, Germany.
New Phytol. 1992 Jul;121(3):403-412. doi: 10.1111/j.1469-8137.1992.tb02940.x.
Five days after emergence radish (Raphanus sativus L. ev. Cherry Belle) plants were transferred to a phytotron at the GSF München, where they were exposed in four large controlled climate chambers to two atmospheric concentrations of CO , ('ambient', daily means of ∼ 385 μmol ; elevated, daily means of ∼ 765 μmol mol ) and two O regimes ('non-polluted' air, 24 h mean of 20 nmol mol ; polluted air, 24 h mean of 73 nmol mol ). Leaf gas-exchange measurements were made at intervals, and visible O damage, effects on growth, dry matter partitioning and mineral composition were assessed at a final whole-plant harvest after 27 d. In 'non-polluted air' CO enrichment resulted in a progressive stimulation in A , whilst there was a decline in g which decreased E (i.e. improved WUE ). The extra carbon fixed in elevated CO stimulated growth of the root (+ hypocotyl) by 43 %, but there was no significant effect on shoot growth or leaf area. Moreover, a decline in SLA and LAR in CO -enriched plants suggested that less dry matter was invested in leaf area expansion. Tissue concentrations of N, S, P, Mg and Ca were lower (particularly in the root + hypocotyl) in elevated CO , indicating that total uptake of these nutrients was not affected by CO , and there was an increase in the C:N ratio in root (+ hypocotyl) tissue. In contrast, O depressed A , (∼ 26%) and induced slight stomatal closure, with the result that WUE, declined. All plants exposed to 'polluted' air developed typical visible symptoms of O injury, and effects on carbon assimilation were reflected in reduced growth, with shoot growth maintained at the expense of the root. In addition, O increased the P and K concentration in shoot and root (+ hypocotyl) tissue, indicating enhanced uptake of these nutrients from the growth medium. However, there was no affect of O on tissue concentrations of N, S, Mg and Ca. Interactions between the gases were complex, and often subtle. In general, elevated CO counteracted (at least in part) the detrimental effects of phytotoxic concentrations of O , whilst conversely, O reduced the impact of elevated CO . Moreover, there were indications that cumulative changes in source: sink relations in O -exposed plants may limit plant response to CO -enrichment to an even greater extent in the long-term. The future ecological significance of interactions between CO and O are discussed.
萝卜（Raphanus sativus L. ev. Cherry Belle）出苗5天后，被转移至慕尼黑GSF的人工气候室，在四个大型可控气候箱中，使其暴露于两种大气CO₂浓度（“环境浓度”，日均值约385 μmol/mol；升高浓度，日均值约765 μmol/mol）和两种O₃处理（“未污染”空气，24小时均值为20 nmol/mol；污染空气，24小时均值为73 nmol/mol）下。每隔一段时间进行叶片气体交换测量，并在27天后最终整株收获时评估可见的O₃损伤、对生长、干物质分配和矿物质组成的影响。在“未污染空气”中，CO₂富集导致光合速率（A）逐渐增加，而气孔导度（g）下降，蒸腾速率（E）降低（即水分利用效率提高）。在升高的CO₂浓度下固定的额外碳使根（+下胚轴）生长增加了43%，但对地上部生长或叶面积没有显著影响。此外，CO₂富集植株的比叶面积（SLA）和叶面积比（LAR）下降，表明用于叶面积扩展的干物质减少。在升高的CO₂浓度下，N、S、P、Mg和Ca的组织浓度较低（特别是在根+下胚轴中），这表明这些养分的总吸收不受CO₂影响，且根（+下胚轴）组织中的碳氮比增加。相比之下，O₃降低了光合速率（约26%）并诱导轻微气孔关闭，结果水分利用效率下降。所有暴露于“污染”空气的植株都出现了典型的可见O₃损伤症状，对碳同化的影响表现为生长减少，地上部生长得以维持但以根为代价。此外，O₃增加了地上部和根（+下胚轴）组织中P和K的浓度，表明从生长介质中对这些养分的吸收增强。然而，O₃对N、S、Mg和Ca的组织浓度没有影响。气体之间的相互作用很复杂，而且往往很微妙。一般来说，升高的CO₂抵消了（至少部分抵消了）植物毒性浓度的O₃的有害影响，反之，O₃降低了升高的CO₂的影响。此外，有迹象表明，长期来看，暴露于O₃的植株中源 - 库关系的累积变化可能在更大程度上限制植株对CO₂富集的响应。讨论了CO₂和O₃之间相互作用的未来生态意义。
