Department of Vegetable Crops, Cornell University, Ithaca, New York 14850.
Plant Physiol. 1976 Apr;57(4):465-8. doi: 10.1104/pp.57.4.465.
The response of several leaf gas exchange parameters were monitored with decreasing leaf water potential in Phaseolus vulgaris L. leaflets. These included photosynthesis, transpiration, CO(2) compensation point, ribulose 1,5-diphosphate carboxylase activity, boundary layer plus stomatal, and mesophyll resistance to diffusion of CO(2). Mesophyll resistance was calculated under two assumptions: (a) the CO(2) concentration at the chloroplast was zero, and (b) it was equal to the CO(2) compensation point.Contrary to some reports on bean, the estimates of mesophyll resistance (both models) increased with decreasing leaf water potential. Concurrently, the CO(2) compensation point increased and ribulose 1,5-diphosphate carboxylase activity decreased as internal water stress increased.It is suggested that the mesophyll resistance term has been too liberally interpreted in the past and that future use be verified by an indicator of biochemical response to environmental stress such as the assay for ribulose 1,5-diphosphate carboxylase activity.
在 Phaseolus vulgaris L. 叶片中，随着叶片水势的降低，监测了几种叶片气体交换参数的响应。这些参数包括光合作用、蒸腾作用、CO2 补偿点、核酮糖 1,5-二磷酸羧化酶活性、边界层加气孔以及 CO2 扩散的胞间阻力。在两种假设下计算了胞间阻力：(a) 叶绿体中的 CO2 浓度为零，和 (b) 它等于 CO2 补偿点。与一些关于豆类的报告相反，随着叶片水势的降低，胞间阻力（两种模型）的估计值都增加了。同时，随着内部水胁迫的增加，CO2 补偿点增加，核酮糖 1,5-二磷酸羧化酶活性降低。建议过去对胞间阻力项的解释过于自由，将来应通过对环境胁迫的生化反应的指标（如核酮糖 1,5-二磷酸羧化酶活性测定）进行验证。
