Jishi Tomohiro, Matsuda Ryo, Fujiwara Kazuhiro
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. 2015 Apr;124(1):107-16. doi: 10.1007/s11120-015-0107-z. Epub 2015 Mar 4.
Time-averaged net photosynthetic rate (P n) under pulsed light (PL) is known to be affected by the PL frequency and duty ratio, even though the time-averaged photosynthetic photon flux density (PPFD) is unchanged. This phenomenon can be explained by considering that photosynthetic intermediates (PIs) are pooled during light periods and then consumed by partial photosynthetic reactions during dark periods. In this study, we developed a kinetic model to estimate P n of cos lettuce (Lactuca sativa L. var. longifolia) leaves under PL based on the dynamics of the amount of pooled PIs. The model inputs are average PPFD, duty ratio, and frequency; the output is P n. The rates of both PI accumulation and consumption at a given moment are assumed to be dependent on the amount of pooled PIs at that point. Required model parameters and three explanatory variables (average PPFD, frequency, and duty ratio) were determined for the simulation using P n values under PL based on several combinations of the three variables. The model simulation for various PL levels with a wide range of time-averaged PPFDs, frequencies, and duty ratios further demonstrated that P n under PL with high frequencies and duty ratios was comparable to, but did not exceed, P n under continuous light, and also showed that P n under PL decreased as either frequency or duty ratio was decreased. The developed model can be used to estimate P n under various light environments where PPFD changes cyclically.
已知在脉冲光（PL）下，尽管时间平均光合光子通量密度（PPFD）不变，但时间平均净光合速率（Pn）会受到PL频率和占空比的影响。这种现象可以通过考虑光合中间产物（PIs）在光照期间积累，然后在黑暗期间被部分光合反应消耗来解释。在本研究中，我们基于积累的PIs量的动态变化，开发了一个动力学模型来估算生菜（Lactuca sativa L. var. longifolia）叶片在PL下的Pn。模型输入为平均PPFD、占空比和频率；输出为Pn。假定给定时刻PI的积累和消耗速率均取决于该时刻积累的PIs量。基于这三个变量的几种组合，利用PL下的Pn值确定了模拟所需的模型参数和三个解释变量（平均PPFD、频率和占空比）。对具有广泛时间平均PPFD、频率和占空比的各种PL水平进行的模型模拟进一步表明，高频和高占空比PL下的Pn与连续光照下的Pn相当，但不超过连续光照下的Pn，并且还表明，随着频率或占空比的降低，PL下的Pn也会降低。所开发的模型可用于估算PPFD周期性变化的各种光照环境下的Pn。
