Field C, Chiariello N, Williams W E
Department of Biological Sciences, Stanford University, 94305, Stanford, CA, USA.
Oecologia. 1982 Dec;55(3):414-420. doi: 10.1007/BF00376931.
Leaf energy balance and gas-exchange characteristics were studied in Mimulus cardinalis at 400 m and Mimulus lewisii at 2,700 m in the Sierra Nevada of central California. In contrast to previous observations, leaf temperatures were not near 30° C at air temperatures from 20 to 40° C but were coupled quite closely to air temperature. Stomatal conductance in both species decreased in response to increases in the water vapor concentration gradient, a response opposite that required to establish 30°C leaf temperatures over a wide range of air temperatures. The temperature optima for photosynthesis were broad in both species but 5° C higher for M. cardinalis than for M. lewisii. The direct or indirect effects of altitude did not contribute significantly to the maintenance of constant leaf temperatures. For both species, maintaining constant leaf temperatures appears to be less important than avoiding inhibitory water stress or diffusion limitation of photosynthesis.
在加利福尼亚州中部内华达山脉海拔400米处的红花沟酸浆和海拔2700米处的刘易斯沟酸浆中，对叶片能量平衡和气体交换特性进行了研究。与之前的观察结果相反，在20至40°C的气温下，叶片温度并非接近30°C，而是与气温紧密相关。随着水汽浓度梯度的增加，这两个物种的气孔导度均下降，这一反应与在广泛的气温范围内维持30°C叶片温度所需的反应相反。两个物种光合作用的最适温度范围都很宽，但红花沟酸浆比刘易斯沟酸浆高5°C。海拔的直接或间接影响对维持恒定的叶片温度贡献不大。对于这两个物种来说，维持恒定的叶片温度似乎不如避免抑制性水分胁迫或光合作用的扩散限制重要。
