Department of Biological and Environmental Engineering, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo, Tokyo, 113-8657, Japan.
Photosynth Res. 2018 Jun;136(3):371-378. doi: 10.1007/s11120-017-0470-z. Epub 2017 Dec 13.
Square-wave pulsed light is characterized by three parameters, namely average photosynthetic photon flux density (PPFD), pulsed-light frequency, and duty ratio (the ratio of light-period duration to that of the light-dark cycle). In addition, the light-period PPFD is determined by the averaged PPFD and duty ratio. We investigated the effects of these parameters and their interactions on net photosynthetic rate (P ) of cos lettuce leaves for every combination of parameters. Averaged PPFD values were 0-500 µmol m s. Frequency values were 0.1-1000 Hz. White LED arrays were used as the light source. Every parameter affected P and interactions between parameters were observed for all combinations. The P under pulsed light was lower than that measured under continuous light of the same averaged PPFD, and this difference was enhanced with decreasing frequency and increasing light-period PPFD. A mechanistic model was constructed to estimate the amount of stored photosynthetic intermediates over time under pulsed light. The results indicated that all effects of parameters and their interactions on P were explainable by consideration of the dynamics of accumulation and consumption of photosynthetic intermediates.
方波脉冲光的特点由三个参数决定，分别是平均光合光子通量密度（PPFD）、脉冲光频率和占空比（光周期持续时间与光暗周期之比）。此外，光周期的 PPFD 由平均 PPFD 和占空比决定。我们研究了这些参数及其相互作用对每一种组合参数下生菜叶片净光合速率（P）的影响。平均 PPFD 值为 0-500µmol m-2 s-1。频率值为 0.1-1000Hz。使用白色 LED 阵列作为光源。所有参数都影响 P，并且观察到所有组合参数之间的相互作用。在脉冲光下的 P 低于相同平均 PPFD 下连续光下测量的值，并且这种差异随着频率的降低和光周期 PPFD 的增加而增强。构建了一个机械模型来估计在脉冲光下随时间积累的光合中间产物的数量。结果表明，通过考虑光合中间产物的积累和消耗的动力学，可以解释参数及其相互作用对 P 的所有影响。
