Barnes C, Tibbitts T, Sager J, Deitzer G, Bubenheim D, Koerner G, Bugbee B
Department of Plants, Soils, and Biometeorology, Utah State University, Logan 84322-4820.
HortScience. 1993 Dec;28(12):1197-200.
Photosynthesis is fundamentally driven by photon flux rather than energy flux, but not all absorbed photons yield equal amounts of photosynthesis. Thus, two measures of photosynthetically active radiation have emerged: photosynthetic photon flux (PPF), which values all photons from 400 to 700 nm equally, and yield photon flux (YPF), which weights photons in the range from 360 to 760 nm according to plant photosynthetic response. We selected seven common radiation sources and measured YPF and PPF from each source with a spectroradiometer. We then compared these measurements with measurements from three quantum sensors designed to measure YPF, and from six quantum sensors designed to measure PPF. There were few differences among sensors within a group (usually <5%), but YPF values from sensors were consistently lower (3% to 20%) than YPF values calculated from spectroradiometric measurements. Quantum sensor measurements of PPF also were consistently lower than PPF values calculated from spectroradiometric measurements, but the differences were <7% for all sources, except red-light-emitting diodes. The sensors were most accurate for broad-band sources and least accurate for narrow-band sources. According to spectroradiometric measurements, YPF sensors were significantly less accurate (>9% difference) than PPF sensors under metal halide, high-pressure sodium, and low-pressure sodium lamps. Both sensor types were inaccurate (>18% error) under red-light-emitting diodes. Because both YPF and PPF sensors are imperfect integrators, and because spectroradiometers can measure photosynthetically active radiation much more accurately, researchers should consider developing calibration factors from spectroradiometric data for some specific radiation sources to improve the accuracy of integrating sensors.
光合作用从根本上是由光子通量而非能量通量驱动的，但并非所有被吸收的光子都能产生等量的光合作用。因此，出现了两种光合有效辐射的测量方法：光合光子通量（PPF），它对400至700纳米的所有光子给予同等的数值；以及产量光子通量（YPF），它根据植物的光合反应对360至760纳米范围内的光子进行加权。我们选择了七种常见的辐射源，并用分光辐射计测量了每个源的YPF和PPF。然后，我们将这些测量结果与三个设计用于测量YPF的量子传感器以及六个设计用于测量PPF的量子传感器的测量结果进行了比较。同一组内的传感器之间差异很小（通常< 5%），但传感器的YPF值始终低于分光辐射测量计算得出的YPF值（3%至20%）。PPF的量子传感器测量值也始终低于分光辐射测量计算得出的PPF值，但除了发光二极管外，所有源的差异均< 7%。这些传感器对宽带源的测量最准确，对窄带源的测量最不准确。根据分光辐射测量，在金属卤化物灯、高压钠灯和低压钠灯下，YPF传感器的准确性明显低于PPF传感器（差异> 9%）。在发光二极管下，两种传感器类型都不准确（误差> 18%）。由于YPF和PPF传感器都是不完善的积分器，并且由于分光辐射计能够更准确地测量光合有效辐射，研究人员应考虑针对某些特定辐射源从分光辐射数据中开发校准因子，以提高积分传感器的准确性。
