Osmond C B, Ludlow M M, Davis R, Cowan I R, Powles S B, Winter K
Department of Environmental Biology, Research School of Biological Sciences, Australian National University, PO Box 475, 2601, Canberra City, ACT.
Cunningham Laboratory, CSIRO Division of Tropical Crops and Pastures, Mill Road, 4067, St Lucia, Queensland, Australia.
Oecologia. 1979 Jul;41(1):65-76. doi: 10.1007/BF00344837.
At constant cladode temperature the stomatal resistance of O. inermis increased when the cladode-air vapor pressure difference was increased and stomatal resistance decreased when the cladode-air vapor pressure difference was lowered. Net CO fixation in the dark was very responsive to these humidity dependent changes in stomatal resistance. Net CO fixation and stomatal resistance in the light did not respond to changes in cladode-air vapor pressure differences in the light under the conditions tested. When temperature response functions for dark CO fixation were examined at constant ambient humidity, the reduction in dark CO fixation at higher temperatures was largely due to stomatal closure in response to the increased vapor pressure difference. The water requirement for net CO fixation in the dark at typical nocturnal vapor pressure differences was about 10 times lower than that of net CO fixation in the light at vapor pressure differences typical of the late afternoon. The role of the stomatal responses to humidity in determining the patterns and rates of net CO exchange in the light or dark, and its possible ecological significance is discussed.
在茎枝温度恒定的情况下，当茎枝-空气蒸汽压差增大时，无刺仙人掌的气孔阻力增加；当茎枝-空气蒸汽压差降低时，气孔阻力减小。黑暗中净二氧化碳固定对这些依赖湿度的气孔阻力变化非常敏感。在所测试的条件下，光照下的净二氧化碳固定和气孔阻力对茎枝-空气蒸汽压差的变化没有反应。当在恒定的环境湿度下检查黑暗中二氧化碳固定的温度响应函数时，较高温度下黑暗中二氧化碳固定的减少主要是由于气孔关闭以响应蒸汽压差的增加。在典型的夜间蒸汽压差下，黑暗中净二氧化碳固定的需水量比下午晚些时候典型蒸汽压差下光照下净二氧化碳固定的需水量低约10倍。讨论了气孔对湿度的响应在决定光照或黑暗中净二氧化碳交换的模式和速率方面的作用及其可能的生态意义。
