DeJong T M, Drake B G, Pearcy R W
Smithsonian Radiation Biology Laboratory, 12441 Parklawn Drive, 29852, Rockville, MD, USA.
Department of Botany, University of California, 95616, Davis, CA, USA.
Oecologia. 1982 Jan;52(1):5-11. doi: 10.1007/BF00349004.
Laboratory and field gas exchange measurements were made on C (Scirpus olneyi Gray) and C (Spartina patens (Ait.) Mahl., Distichlis spicata (L.) Green) species from an irregularly flooded tidal marsh on the Chesapeake Bay. Laboratory measurements were made on plants grown from root stocks that were transplanted to a greenhouse and grown under high light and high nutrient conditions. The two C species were similar in their laboratory gas exchange characteristics: both had higher net carbon exchange rates, higher mesophyll conductances, higher photosynthetic temperature optima and lower leaf conductances than the C species. The laboratory photosynthetic water use efficiency of the C species was approximately three times that of the C species.Field gas exchange responses of the above species were measured in situ a Chesapeake Bay tidal marsh. Despite differences in biological potential measured in the laboratory, all three species had similar in situ carbon exchange rates on a leaf area basis. On a dry weight basis, leaves of the two C species had about 1.4 times higher light saturated CO assimilation rates than the C species. Light saturation of CO exchange occurred at photosynthetic photon flux densities of 80 n Einstein cms, compared with 160 n Einstein cm s in the laboratory grown plants. Spartina patens and Scirpus olneyi had similar daily CO assimilation rates, but the daily transpiration rate of the C species was almost twice that of the C species. Spartina patens showed greater seasonal decrease in photosynthesis than Distichlis spicata and Scirpus olneyi. The two C grass species maintained higher mesophyll conductances and photosynthetic water use efficiencies than the C sedge.
对切萨皮克湾一处不定期被洪水淹没的潮汐沼泽中的C4植物（窄叶藨草，Scirpus olneyi Gray）和C3植物（互花米草，Spartina patens (Ait.) Mahl.；盐沼草，Distichlis spicata (L.) Green）进行了实验室和野外气体交换测量。实验室测量是针对从根茎培育出的植株进行的，这些根茎被移植到温室中，并在高光和高养分条件下生长。这两种C4植物在实验室气体交换特征方面相似：与C3植物相比，二者均具有更高的净碳交换率、更高的叶肉导度、更高的光合最适温度以及更低的叶片导度。C4植物在实验室中的光合水分利用效率约为C3植物的三倍。在切萨皮克湾潮汐沼泽原位测量了上述物种的野外气体交换响应。尽管在实验室中测量的生物潜力存在差异，但基于叶面积，所有这三个物种的原位碳交换率相似。以干重为基础，两种C4植物叶片的光饱和CO2同化率比C3植物高约1.4倍。CO2交换的光饱和发生在光合光子通量密度为80 n爱因斯坦·厘米-2·秒-1时，而在实验室种植的植物中为160 n爱因斯坦·厘米-2·秒-1。互花米草和窄叶藨草的日CO2同化率相似，但C4物种的日蒸腾速率几乎是C3物种的两倍。互花米草的光合作用季节性下降幅度比盐沼草和窄叶藨草更大。这两种C4禾本科植物比C3莎草科植物保持更高的叶肉导度和光合水分利用效率。
