Pulsed Light at Lower Duty Ratios with Lower Frequencies is Less Advantageous than Continuous Light for CO&lt;sub&gt;2&lt;/sub&gt; Uptake in Cos Lettuce

Jishi, Tomohiro; Fujiwara, Kazuhiro; Nishino, Kazumi; Yano, Akira

doi:10.2150/jlve.ieij120000482

Cited by 14 publications

(9 citation statements)

References 4 publications

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“…The amount of stored PI should not approach saturation during short light periods at high frequencies, and PI synthesis cannot be performed with high efficiency. Similar results were obtained with lettuce leaves (Jishi et al, 2013).…”

Section: Photosynthesis Mechanism Under Pulsed Lightsupporting

confidence: 87%

Time-varying Photosynthetic Photon Flux Density and Relative Spectral Photon Flux Density Distribution to Improve Plant Growth and Morphology in Plant Factories with Artificial Lighting

Jishi

Fujiwara

2021

Hort. J.

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In contrast to fluorescent lamps and high-power sodium lamps, the use of light-emitting diode (LED) lamps enables the control of not only photosynthetic photon flux density (PPFD) at the plant level, but also the relative spectral photon flux density distribution (RSPD) of light because of the variety, even at different times of day, of producible light emitted by LEDs of different types. Effects of the spectral photon flux density on plant growth and morphology have been investigated using several types of LEDs and plant species. However, few studies on lighting methods with time-varying PPFD or RSPD have been published to date. In this paper, we summarize the effects of time-varying PPFD on the net photosynthetic rate (P n) and those of time-varying RSPD on plant growth and morphology. Detailed modeling studies have been conducted on the reactions of the photosynthetic pathway under time-varying PPFD at a cycle of milliseconds to seconds. The results of these modeling studies and actual measurements of P n under pulsed light clearly indicate that pulsed light is not advantageous to improve P n. Although the integrated PPFD of blue and red light was unchanged, the growth of leaf lettuce was promoted by asynchronous irradiation with blue light and red light compared with growth under simultaneous irradiation. We think that blue-light monochromatic irradiation promotes leaf elongation through leaf expansion as a primary factor in the enhancement of plant growth. In addition, changes in leaf photosynthetic capacity caused by blue-light monochromatic irradiation may be involved in plant growth promotion. An increasing number of studies have investigated the effects of time-varying RSPD on plants. However, the mechanisms underlying these effects remain to be elucidated.

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Section: Photosynthesis Mechanism Under Pulsed Lightsupporting

confidence: 87%

Time-varying Photosynthetic Photon Flux Density and Relative Spectral Photon Flux Density Distribution to Improve Plant Growth and Morphology in Plant Factories with Artificial Lighting

Jishi

Fujiwara

2021

Hort. J.

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“…In the pulsed light technique for growing tomato plants, low frequencies (0.1, 1, 10 Hz) had higher quantum efficiency in PSII than higher frequencies (50, 100 kHz) and continuous light, but the electron transport rate decreased when the frequency of pulse increased [11]. On the other hand, pulsed light of lower duty ratios, combined with lower frequencies, makes the CO 2 uptake rate of cos lettuce lower than that attained in continuous light, inferring that pulsed illumination with such a condition is less advantageous than continuous light for photosynthesis [12].…”

Section: Introductionmentioning

confidence: 93%

Growth and Photosynthesis under Pulsed Lighting

Kanechi¹

2018

Photosynthesis - From Its Evolution to Future Improvements in Photosynthetic Efficiency Using Nanomaterials

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The effects of pulsed irradiation based-LEDs on the growth and photosynthetic light utilization efficiency of lettuce leaves were studied. Plants were grown under different pulse-cycled irradiations of 0.5-500 Hz, and 1-20 kHz frequencies, at PPFD of 200 μmolm À2 s À1 with 50% duty ratio (illuminated duration/cycle). The photosynthetic rate (Pn) was maintained relatively constant over the range of measurements at pulsed light at 80 PPFD. At 200 PPFD, Pn gradually decreased by lowering frequency below 2.5 Hz of pulsed light. Pn under pulsed light was slightly higher than that under continuous light. Chlorophyll fluorescence (Fv/Fm, Fv'/Fm 0 , qP) showed no significant difference between under pulsed light and continuous light except at the lowest frequency (0.2 Hz). The similar quantum yield (ØPSII) and electron transport rate (ETR) of PSII were obtained in a wide range of frequency of pulsed light, which might be an effective illumination strategy for cultivating leaf lettuce by using LEDs. Flashing irradiation did not significantly change chlorophyll content. Results suggested the effectiveness of pulsed light at 50% duty ratio on the growth of leafy vegetables that were richly cultivated in a closed type plant factory with the possibility of saving electricity by using intermittent illumination system with LEDs.

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“…Previous studies estimated that the photosynthetic rate for various crops responded differently to pulsed lighting and highly depended on the frequency and duty ratio of pulsed light [ 21 ]. For instance, Jishi et al [ 22 ] explored the effects of pulsed LEDs at different frequencies (0.1, 0.2, 0.4, 0.8, 1.6, 3.2, 6.4, 12.8 kHz; 75% duty ratio) on romaine lettuce and did not find a significant effect on net photosynthesis compared to continuous light. Kanechi [ 12 ] found that photosynthetic rate of lettuce under pulsed light (0.5–500 Hz, 1–20 kHz, 50% duty ratio) was slightly higher than that under continuous light, and this is consistent with our results.…”

Section: Discussionmentioning

confidence: 99%

Effect of Multispectral Pulsed Light-Emitting Diodes on the Growth, Photosynthetic and Antioxidant Response of Baby Leaf Lettuce (Lactuca sativa L.)

Miliauskienė

Karlicek

Kolmos

2021

Plants

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The effect of multicolor pulsed light-emitting diode (LED) irradiation on lettuce “Defender” growth, photosynthetic performance and antioxidant properties was studied. The experiments were designed to compare the continuous and pulsed lighting (0.5, 1 kHz; 50% duty ratio) effects of B450, G520, R660 and FR735 lighting components, maintaining total diurnal integral light quantity (DLI 14.4 mol m−2 day−1) constant during the 16-h photoperiod. The results showed that lettuce grown under pulsed irradiation displayed superior growth performance, including a significant enhancement of fresh (~32%) and dry biomass (~36%) and leaf area (~48%). Lettuce cultivated in both pulsed light treatments was characterized by the higher photosynthetic rate, chlorophyll (a,b) and carotenoid concentration. However, the total phenol and antioxidant properties in lettuce were more dependent on the specific pulsed light frequency. Only treatment with 1 kHz frequency was effective for higher phenol content, 2,20-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) free radical scavenging activity and Fe2+ reducing antioxidant power (FRAP). Thus, our results propose the role of pulsed LED light in improving the photosynthetic efficiency and antioxidative properties of lettuce plants cultivated indoors. In the future, pulsed lighting techniques should be included in the development of artificial lighting systems in controlled environment agriculture (CEA) to produce high-quality crops with the possibility to save electricity.

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Pulsed Light at Lower Duty Ratios with Lower Frequencies is Less Advantageous than Continuous Light for CO<sub>2</sub> Uptake in Cos Lettuce

Cited by 14 publications

References 4 publications

Time-varying Photosynthetic Photon Flux Density and Relative Spectral Photon Flux Density Distribution to Improve Plant Growth and Morphology in Plant Factories with Artificial Lighting

Time-varying Photosynthetic Photon Flux Density and Relative Spectral Photon Flux Density Distribution to Improve Plant Growth and Morphology in Plant Factories with Artificial Lighting

Growth and Photosynthesis under Pulsed Lighting

Effect of Multispectral Pulsed Light-Emitting Diodes on the Growth, Photosynthetic and Antioxidant Response of Baby Leaf Lettuce (Lactuca sativa L.)

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