Wohlfahrt G, Bahn M, Cernusca A
Institut fur Botanik, Universitat Innsbruck, Sternwartestr. 15, Innsbruck, 6020, Austria.
J Theor Biol. 1999 Sep 21;200(2):163-81. doi: 10.1006/jtbi.1999.0985.
Recent models of photosynthesis have adopted the close correlation between the main photosynthetic component processes, the maximum rate of carboxylation and the potential rate of RuBP (ribulose-1, 5-bisphosphate) regeneration, at a reference temperature of 20 degrees C. When using the ratio between these two processes in models of photosynthesis, assumptions though have to be made about the temperature response of the potential rate of RuBP regeneration, which varies with growth conditions and among species. In order to assess the effects of deviations from the real temperature response of the potential rate of RuBP regeneration on photosynthesis, a sensitivity analysis, scaling up photosynthesis from the leaf to the canopy level, is applied in the present paper. No changes are predicted to occur for sunlit leaves, which receive both direct and diffuse radiation, as long as incident radiation does not cause carboxylation to shift from RuBP saturation to RuBP limitation, which, depending on incident radiation and canopy structure, might occur deeper down in the canopy. Carboxylation of shaded leaves, which receive solely diffuse radiation, is generally limited by the regeneration of RuBP, and is thus prone to be affected by changes in the temperature response of the potential rate of RuBP regeneration. Due to the saturation type response of the RuBP-limited rate of carboxylation to temperature at light intensities below saturation, the impact of deviations from the real temperature response is negligible at high leaf temperatures, but may become significant when leaf temperatures are low and photosynthetically active radiation incident on shaded leaves is comparably high, as in the upper canopy layers. The largest effects on whole canopy photosynthesis will therefore occur under cool conditions and a completely overcast sky, when all leaves receive diffuse radiation only. Copyright 1999 Academic Press.
近期的光合作用模型采用了在20摄氏度参考温度下，主要光合组成过程、羧化作用的最大速率与核酮糖-1,5-二磷酸（RuBP）再生的潜在速率之间的紧密关联。在光合作用模型中使用这两个过程的比率时，必须对RuBP再生潜在速率的温度响应做出假设，而该响应会因生长条件和物种不同而有所变化。为了评估RuBP再生潜在速率的实际温度响应偏差对光合作用的影响，本文进行了一项从叶片尺度扩展到冠层尺度的光合作用敏感性分析。对于接受直射和漫射辐射的向阳叶片，只要入射辐射不会导致羧化作用从RuBP饱和状态转变为RuBP限制状态（这取决于入射辐射和冠层结构，可能发生在冠层更深的位置），预计不会发生变化。仅接受漫射辐射的遮荫叶片的羧化作用通常受RuBP再生的限制，因此容易受到RuBP再生潜在速率温度响应变化的影响。由于在低于饱和光强下，RuBP限制的羧化速率对温度呈饱和型响应，在高叶片温度下，与实际温度响应的偏差影响可忽略不计，但当叶片温度较低且入射到遮荫叶片上的光合有效辐射相对较高时，如在冠层上层，这种偏差影响可能会变得显著。因此，在凉爽条件和完全阴天时，当所有叶片仅接受漫射辐射时，对整个冠层光合作用的影响最大。版权所有1999年学术出版社。
