Anten N P R, Hirose T, Onoda Y, Kinugasa T, Kim H Y, Okada M, Kobayashi K
Department of Ecology and Evolutionary Biology, Graduate School of Life Sciences, Tohoku University, Aoba, Sendai 980-8578.
Chair Group of Production Systems, Wageningen University, Haarweg 333 6709 R2, The Netherlands.
New Phytol. 2004 Feb;161(2):459-471. doi: 10.1046/j.1469-8137.2003.00943.x. Epub 2003 Dec 1.
• Here we analysed the effects of CO (C ) elevation and nitrogen availability on canopy structure, leaf area index (LAI) and canopy photosynthesis of rice (Oryza sativa). • Rice was grown at ambient and elevated C (c. 200 µmol mol above ambient, using the free-air CO enrichment, FACE) and at two N availabilities. We measured leaf area, area-based leaf N contents and leaf photosynthesis, and calculated net daily canopy photosynthesis. • FACE plants had higher light-saturated rates of photosynthesis (P ) and apparent quantum yields than ambient plants, when measured at their own growth CO . C elevation reduced the total leaf N in the canopy (N ) but had no effect on LAI, and the average leaf N content (N /LAI) was therefore reduced by 8%. This reduction corresponded well with our model predictions. Leaf area index increased strongly with N availability, which was also consistent with our model. • Calculated canopy photosynthesis increased more strongly with N under elevated than under ambient C . This indicates that there is an N × C interactive effect on canopy carbon gain. This interaction was caused by the increase in LAI with N availability, which enhanced the positive effect of the higher quantum yield under C elevation.
• 在此，我们分析了二氧化碳（CO₂）浓度升高和氮素有效性对水稻（Oryza sativa）冠层结构、叶面积指数（LAI）和冠层光合作用的影响。
• 水稻在环境CO₂浓度和升高的CO₂浓度（比环境浓度高约200 μmol mol⁻¹，采用自由空气CO₂富集法，即FACE）以及两种氮素有效性条件下种植。我们测量了叶面积、基于面积的叶片氮含量和叶片光合作用，并计算了每日冠层净光合作用。
• 当在其自身生长的CO₂浓度下测量时，FACE处理的植株比环境CO₂浓度处理的植株具有更高的光饱和光合速率（Pmax）和表观量子产率。CO₂浓度升高降低了冠层总叶氮含量（Nt），但对LAI没有影响，因此平均叶氮含量（Nt/LAI）降低了8%。这种降低与我们的模型预测非常吻合。叶面积指数随氮素有效性的增加而强烈增加，这也与我们的模型一致。
• 计算得出，在升高的CO₂浓度下，冠层光合作用随氮素增加的幅度比在环境CO₂浓度下更大。这表明在冠层碳积累方面存在氮×CO₂的交互作用。这种相互作用是由叶面积指数随氮素有效性增加而增加引起的，这增强了CO₂浓度升高时较高量子产率的积极效应。
