Botany Department, Washington State University, 99164-4238, Pullman, WA, USA.
Photosynth Res. 1993 Aug;37(2):89-102. doi: 10.1007/BF02187468.
Analysis is made of the energetics of CO2 fixation, the photochemical quantum requirement per CO2 fixed, and sinks for utilising reductive power in the C4 plant maize. CO2 assimilation is the primary sink for energy derived from photochemistry, whereas photorespiration and nitrogen assimilation are relatively small sinks, particularly in developed leaves. Measurement of O2 exchange by mass spectrometry and CO2 exchange by infrared gas analysis under varying levels of CO2 indicate that there is a very close relationship between the true rate of O2 evolution from PS II and the net rate of CO2 fixation. Consideration is given to measurements of the quantum yields of PS II (φ PS II) from fluorescence analysis and of CO2 assimilation ([Formula: see text]) in maize over a wide range of conditions. The[Formula: see text] ratio was found to remain reasonably constant (ca. 12) over a range of physiological conditions in developed leaves, with varying temperature, CO2 concentrations, light intensities (from 5% to 100% of full sunlight), and following photoinhibition under high light and low temperature. A simple model for predicting CO2 assimilation from fluorescence parameters is presented and evaluated. It is concluded that under a wide range of conditions fluorescence parameters can be used to predict accurately and rapidly CO2 assimilation rates in maize.
对玉米这种 C4 植物固定 CO2 的能量学、每固定 1 个 CO2 所需的光化学量子数以及还原力的利用进行了分析。CO2 同化是光化学能量的主要汇，而光呼吸和氮同化则是相对较小的汇，尤其是在成熟叶片中。通过质谱法测量 O2 交换和红外气体分析测量 CO2 交换，在不同 CO2 水平下的结果表明，PS II 真实的 O2 释放速率与净 CO2 固定速率之间存在非常密切的关系。本文还考虑了在广泛的条件下，通过荧光分析测量 PS II 的量子产率（φ PS II）和玉米 CO2 同化（[Formula: see text]）的测量。在成熟叶片中，在不同的生理条件下，[Formula: see text] 比值保持相当稳定（约 12），温度、CO2 浓度、光强（从 5%到 100%全日照）以及高光低温下的光抑制都有变化。本文提出并评估了一种从荧光参数预测 CO2 同化的简单模型。结论认为，在广泛的条件下，荧光参数可用于准确快速地预测玉米的 CO2 同化速率。
