Nielsen Søren Laurentius, Sand-Jensen Kaj
Freshwater Biological Laboratory, University of Copenhagen, 51 Helsingørsgade, DK-3400, Hillerød, Denmark.
Oecologia. 1989 Nov;81(3):364-368. doi: 10.1007/BF00377085.
Fourteen temperate, submerged macrophytes were cultivated in the laboratory at high DIC levels (3.3-3.8 mM), 10.4-14.4 mol photons (PAR) m d and 15°C. Photosynthesis at photosaturation ranged between 0.59 and 17.98 mg O g DW h at ambient pH (8.3) and were markedly higher between 1.76 and 47.11 mg O g DW h at pH 6.5 under elevated CO concentrations. Photosynthetic rates were significantly related to both the relative surface area and the chlorophyll content of the leaves. Consequently, the photosynthetic rate was much less variable among the species when expressed per surface area and chlorophyll content instead of dry mass. The chlorophyll content was probably a main predictor of photosynthesis of submerged leaves because of the direct relationship of chlorophyll to the light harvesting capacity and/or a coupling to the capacity for photosynthetic electron transport and carboxylation. A comparison with terrestrial leaves characterized the submerged leaves by their low chlorophyll concentrations and low photosynthetic rates per surface area due to the thin leaves. Photosynthetic rates per chlorophyll content in submerged leaves at CO saturation, however, were at the same level as photosynthesis in terrestrial leaves measured at ambient CO when appropriate corrections were made for differences in incubation temperature.
在实验室中，14种温带沉水大型植物在高溶解无机碳（DIC）水平（3.3 - 3.8 mM）、10.4 - 14.4摩尔光子（PAR）·m⁻²·d⁻¹以及15°C的条件下进行培养。在环境pH值（8.3）时，光合饱和时的光合作用速率在0.59至17.98毫克氧气·克干重·小时之间，而在升高的二氧化碳浓度下，pH值为6.5时，光合作用速率显著更高，在1.76至47.11毫克氧气·克干重·小时之间。光合速率与叶片的相对表面积和叶绿素含量均显著相关。因此，当以单位表面积和叶绿素含量而非干重来表示时，不同物种间的光合速率变化要小得多。叶绿素含量可能是沉水叶片光合作用的主要预测指标，因为叶绿素与光捕获能力直接相关，和/或与光合电子传递及羧化能力相关联。与陆生叶片相比，沉水叶片由于叶片较薄，叶绿素浓度较低且单位表面积光合速率较低。然而，在二氧化碳饱和时，对培养温度差异进行适当校正后，沉水叶片单位叶绿素含量的光合速率与在环境二氧化碳浓度下测量的陆生叶片光合速率处于同一水平。
