DeLucia E H, Thomas R B
Department of Plant Biology, University of Illinois, Urbana, IL 61801, USA e-mail:
Department of Biology, West Virginia University, Morgantown, WV 26506, USA, , , , , , US.
Oecologia. 2000 Jan;122(1):11-19. doi: 10.1007/PL00008827.
We compared the CO- and light-dependence of photosynthesis of four tree species (Acer rubrum, Carya glabra, Cercis canadensis, Liquidambar styraciflua) growing in the understory of a loblolly pine plantation under ambient or ambient plus 200 µl l CO. Naturally-established saplings were fumigated with a free-air CO enrichment system. Light-saturated photosynthetic rates were 159-190% greater for Ce. canadensis saplings grown and measured under elevated CO. This species had the greatest CO stimulation of photosynthesis. Photosynthetic rates were only 59% greater for A. rubrum saplings under CO enrichment and Ca. glabra and L. styraciflua had intermediate responses. Elevated CO stimulated light-saturated photosynthesis more than the apparent quantum yield. The maximum rate of carboxylation of ribulose-1,5-bisphosphate carboxylase, estimated from gas-exchange measurements, was not consistently affected by growth in elevated CO. However, the maximum electron transport rate estimated from gas- exchange measurements and from chlorophyll fluorescence, when averaged across species and dates, was approximately 10% higher for saplings in elevated CO. The proportionately greater stimulation of light-saturated photosynthesis than the apparent quantum yield and elevated rates of maximum electron transport suggests that saplings growing under elevated CO make more efficient use of sunflecks. The stimulation of light-saturated photosynthesis by CO did not appear to correlate with shade-tolerance ranking of the individual species. However, the species with the greatest enhancement of photosynthesis, Ce. canadensis and L. styraciflua, also invested the greatest proportion of soluble protein in Rubisco. Environmental and endogenous factors affecting N partitioning may partially explain interspecific variation in the photosynthetic response to elevated CO.
我们比较了生长在火炬松人工林林下的四种树种（红花槭、光滑山核桃、加拿大紫荆、胶皮糖香树）在环境二氧化碳浓度或环境二氧化碳浓度加200 μl/L二氧化碳条件下光合作用对二氧化碳和光照的依赖性。利用自由空气二氧化碳富集系统对自然生长的树苗进行熏蒸处理。在高二氧化碳浓度下生长并测定的加拿大紫荆树苗的光饱和光合速率比对照高159% - 190%。该树种对光合作用的二氧化碳刺激最为显著。在二氧化碳富集条件下，红花槭树苗的光合速率仅提高了59%，光滑山核桃和胶皮糖香树的响应介于两者之间。高二氧化碳浓度对光饱和光合作用的刺激大于表观量子产额。根据气体交换测量估算的核酮糖-1,5-二磷酸羧化酶的最大羧化速率并未因高二氧化碳浓度下的生长而受到一致影响。然而，综合各物种和各日期的数据来看，根据气体交换测量和叶绿素荧光估算的最大电子传递速率，在高二氧化碳浓度下生长的树苗约高10%。光饱和光合作用比表观量子产额受到更大比例的刺激以及最大电子传递速率升高，这表明在高二氧化碳浓度下生长的树苗能更有效地利用光斑。二氧化碳对光饱和光合作用的刺激似乎与各物种的耐荫性排名无关。然而，光合作用增强最大的物种，即加拿大紫荆和胶皮糖香树，在核酮糖-1,5-二磷酸羧化酶中投入的可溶性蛋白比例也最大。影响氮分配的环境和内在因素可能部分解释了光合作用对高二氧化碳浓度响应的种间差异。
