Adams William W, Martin Craig E
Department of Botany, University of Kansas, 66045, Lawrence, Kansas, USA.
Oecologia. 1986 Sep;70(2):298-304. doi: 10.1007/BF00379255.
The heterophyllous epiphyte Tillandsia deppeana exhibits an atmospheric habit as a juvenile and a tank form as an adult. Both juveniles and adults utilize C photosynthesis. This is the first report of an atmospheric form of Tillandsia which does not exhibit CAM. Photosynthetic saturation occurred at approximately 10% of full sunlight in both forms, but the adults exhibited greater rates of photosynthesis at all levels of irradiance. The adults also had a higher and broader photosynthetic temperature optimum than did the juveniles. The adults transpired at greater rates than the juveniles; however, the water use efficiencies of both forms were similar and were high for C plants. In both forms the photosynthetic rate decreased in response to a decrease in humidity. After 8 days without water the juveniles were able to fix CO throughout the day. The adults, however, exhibited a net loss of CO on the second day without water and thereafter. These results indicate that the water-conservative atmospheric juvenile of T. deppeana is well adapted to establishment in the epiphytic habitat.
异叶附生植物德氏铁兰在幼年时呈现气生习性，成年时则为莲座状。幼年和成年植株均进行C3光合作用。这是关于铁兰属植物气生形态不表现景天酸代谢（CAM）的首次报道。两种形态的光合饱和点均出现在全日照的约10%处，但成年植株在所有光照强度下的光合速率更高。成年植株的光合温度最适值也比幼年植株更高且更宽泛。成年植株的蒸腾速率高于幼年植株；然而，两种形态的水分利用效率相似，且对于C3植物来说都很高。在两种形态中，光合速率均随湿度降低而下降。在无水状态下8天后，幼年植株仍能全天固定CO2。然而，成年植株在无水状态的第二天及之后则表现出CO2的净损失。这些结果表明，德氏铁兰保守水分的幼年气生形态非常适合在附生生境中定殖。
