A kinetic model for estimating net photosynthetic rates of cos lettuce leaves under pulsed light

Abstract

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.

Effects of Irradiation Patterns and Light Quality of Red and Blue Light-Emitting Diodes on Growth of Leaf Lettuce (<I>Lactuca sativa</I> L.&ldquo;Greenwave&rdquo;)

“…The cultivation experiment examining the effect of red and blue LED lights on cos lettuce growth demonstrated that the pattern containing single irradiation with blue light caused the stem extension and the longer cycle of alternating irradiations with red and blue light also led to promote stem extension (Jishi et al, 2015). Thus, day length and single irradiation time of blue light are strongly associated with growth acceleration, factors that we intend to focus on in future experiments in order to establish the optimal irradiation pattern.…”

Growth and Photosynthesis under Pulsed Lighting

“…A kinetic model to estimate Pn was developed by considering that photosynthetic intermediates were pooled during light periods and then consumed by partial photosynthetic reactions during dark periods [25]. According to this model, they quantitatively estimated the effects of pulsed light frequency and duty ratio on photosynthetic rates of cos lettuce leaves.…”

Flashing LEDs for Microalgal Production

“…Flashing light studies on single leaves of land plants or microalgal cultures with low light attenuation potential can identify the biological boundary, and may be described as a function of frequency (f) and duty cycle (ø), i.e. f(ø,f) [17,18]. For example, Jishi et al [17] identified such function of the flashing light effect for lettuce (Lactuca sativa).…”

“…f(ø,f) [17,18]. For example, Jishi et al [17] identified such function of the flashing light effect for lettuce (Lactuca sativa). Interestingly, their model also fits the photosynthetic performances of microalgal cultures with low biomass concentrations (< 0.1 g L -1 ) or short light path lengths (<1-2 cm) and for land plants (e.g.…”