Continuous Irradiation with Alternating Red and Blue Light Enhances Plant Growth While Keeping Nutritional Quality in Lettuce

Ohtake, Noriko; Ishikura, Masaharu; Suzuki, Hiroshi; Yamori, Wataru; Gotō, Eiji

doi:10.21273/hortsci13469-18

Cited by 60 publications

(60 citation statements)

References 47 publications

(55 reference statements)

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“…During the initial stages of our experiment (late November–early December), the natural light intensity was low, and the natural photoperiod is short, thus, supplemental lighting had the largest effect. Similar to results in Ohtake et al (2018) using lettuce, during this period, plants grown under CL had a larger leaf area and taller stem height than plants grown under 12 h lighting. Since day-time NCER are similar between the two treatments, it is likely that elevated NCER between 18:00–06:00 from the CL treatment allocated more carbon for vegetative growth ( Figure 4 ).…”

Section: Discussionsupporting

confidence: 79%

“…In our study, wavelength specific LEDs were utilized to create an alternating spectrum CL regime which produced injury-free tomato plants. The utilization of LEDs to produce an alternating spectrum during CL has been previously documented in lettuce (Ohtake et al, 2018). In this study using lettuce, an alternating CL spectrum with red light during the day (12 h) and blue light during the night (12 h) produced the highest dry weight and leaf area compared to a CL with a constant red/blue spectrum and a CL provided by fluorescent lights (Ohtake et al, 2018).…”

Section: Discussionmentioning

confidence: 99%

“…Continuous light (CL) means a constant flux of energy into photosynthesis, theoretically leading to increased growth and the potential for higher yield. In lettuce, low irradiance CL has already been shown to increase plant growth (Kitaya et al, 1998; Ohtake et al, 2018). However, in plants such as tomato, potato, and eggplant, CL has been associated with negative responses in growth traits (Velez-Ramirez et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

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Alternating Red and Blue Light-Emitting Diodes Allows for Injury-Free Tomato Production With Continuous Lighting

et al. 2019

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Plant biomass is largely dictated by the total amount of light intercepted by the plant [daily light integral (DLI) — intensity × photoperiod]. Continuous light (CL, 24 h lighting) has been hypothesized to increase plant biomass and yield if CL does not cause any injury. However, lighting longer than 18 h causes leaf injury in tomato characterized by interveinal chlorosis and yield is no longer increased with further photoperiod extension in tomatoes. Our previous research indicated the response of cucumbers to long photoperiod of lighting varies with light spectrum. Therefore, we set out to examine greenhouse tomato production under supplemental CL using an alternating red (200 µmol m−2 s−1, 06:00–18:00) and blue (50 µmol m−2 s−1, 18:00–06:00) spectrum in comparison to a 12 h supplemental lighting treatment with a red/blue mixture (200 µmol m−2 s−1 red + 50 µmol m−2 s−1 blue, 06:00–18:00) at the same DLI. Our results indicate that tomato plants grown under supplemental CL using the red and blue alternating spectrum were injury-free. Furthermore, parameters related to photosynthetic performance (i.e., Pnmax, quantum yield, and Fv/Fm) were similar between CL and 12 h lighting treatments indicating no detrimental effect of growth under CL. Leaves under CL produced higher net carbon exchange rates (NCER) during the subjective night period (18:00–06:00) compared to plants grown under 12 h lighting. Notably, 53 days into the treatment, leaves grown under CL produced positive NCER values (photosynthesis) during the subjective night period, a period typically associated with respiration. At 53 days into the growth cycle, it is estimated that leaves under CL will accumulate approximately 800 mg C m−2 more than leaves under 12 h lighting over a 24 h period. Leaves grown under CL also displayed similar diurnal patterns in carbohydrates (glucose, fructose, sucrose, and starch) as leaves under 12 h lighting indicating no adverse effects on carbohydrate metabolism under CL. Taken together, this study provides evidence that red and blue spectral alternations during CL allow for injury-free tomato production. We suggest that an alternating spectrum during CL may alleviate the injury typically associated with CL production in tomato.

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Section: Discussionsupporting

confidence: 79%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Alternating Red and Blue Light-Emitting Diodes Allows for Injury-Free Tomato Production With Continuous Lighting

et al. 2019

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“…2), and the largest leaves were observed under the 1-h treatment; larger leaves capture more light energy to increase the net photosynthetic rate, resulting in the highest biomass of two-leaf-color pak choi under the 1-h treatment (Table 2). According to previous research, compared with simultaneous irradiation with red and blue light, alternating red and blue light promotes the growth of lettuce, especially at 22 to 31 d (Ohtake et al, 2018), suggesting a significant effect of alternating irradiation on plants in the later cultivation period. In addition, it was shown that with the exception of consistent irradiation with red and blue light, the fresh and dry weights of lettuce under alternating red and blue light exposure were highest with an interval of 1 h vs. 2, 4, and 8 h (Chen et al, 2019), which was consistent with the results of the present study.…”

Section: Plant Typementioning

confidence: 76%

“…The length of the petiole and the stem length of lettuce reached their maximum levels under intermittent red and blue light exposure with intervals of 6 and 1 h (Shimokawa et al, 2014). Red and blue light promote leaf expansion, and alternating red and blue light exposure contributes to elongating the leaves of lettuce (Ohtake et al, 2018). The results showed that the leaves of both cultivars of pak choi were larger under supplemental alternating red and blue light than they were at 0 h (Fig.…”

Section: Plant Typementioning

confidence: 84%

Improvement of the Growth and Nutritional Quality of Two-leaf-color Pak Choi by Supplemental Alternating Red and Blue Light

Huang¹,

Xu²,

Duan³

et al. 2021

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The aim of the present study was to evaluate the effects of alternating red (660 nm) and blue (460 nm) light on the growth and nutritional quality of two-leaf-color pak choi (Brassica campestris L. ssp. chinensis var. communis). Four light treatments (supplemental alternating red and blue light with intervals of 0, 1, 2, and 4 hours, with a monochromatic light intensity of 100 μmol·m−2·s−1 and a cumulative lighting time of 16 hours per day) were conducted in a greenhouse under identical ambient light conditions (90 to 120 μmol·m−2·s−1 at 12:00 am) for 10 days before green- and red-leaf pak choi were harvested. The results showed that the two-leaf-color pak choi receiving alternating red and blue light exhibited more compact canopies and wider leaves than those under the control treatment, which was attributed to the shade avoidance syndrome of plants. The present study indicated that the biomass of green-leaf pak choi was much higher than that of red-leaf pak choi, but the nutritional quality of green-leaf pak choi was lower than that of red-leaf pak choi, and seemingly indicating that the regulation of metabolism for pak choi was species specific under light exposure. The trends of both biomass and the soluble sugar content were highest under the 1-hour treatment. The contents of chlorophyll a and total chlorophyll in both cultivars (green- and red-leaf pak choi) were significantly increased compared with control, without significant differences among the 1-, 2-, and 4-hour treatments, whereas chlorophyll b exhibited no significant difference in any treatment. Alternating red- and blue-light treatment significantly affected the carotenoid content, but different trends in green- and red-leaf pak choi were observed, with the highest contents being detected under the 1-hour and 4-hour treatments, respectively. With increasing time intervals, the highest soluble protein contents in two-leaf-color pak choi were observed in the 4-hour treatment, whereas nitrate contents were significantly decreased in the 4-hour treatment. Compared with 0 hours, the contents of vitamin C, phenolic compounds, flavonoids, and anthocyanins in two-leaf-color pak choi were significantly increased, but no significant differences were observed in vitamin C, phenolic compounds, and flavonoids among the 1-, 2-, and 4-hour treatments, similar to what was found for the anthocyanin content of green-leaf pak choi. However, the content of anthocyanins in red-leaf pak choi gradually increased with increasing time intervals, with the highest content being found in the 4-hour treatment. Supplemental alternating red and blue light slightly increased the antioxidant capacity [1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging rate and antioxidant power], but no significant differences were observed after 1, 2, and 4 hours of treatment. Taken together, treatment with an interval of 1 hour was the most effective for increasing the biomass of pak choi in this study, but treatment with a 4-hour interval should be considered to enhance the accumulation of health-promoting compounds.

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Blue and red light upregulate α-expansin 1 (EXPA1) in transgenic Brassica rapa and its overexpression promotes leaf and root growth in Arabidopsis

et al. 2020

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Continuous Irradiation with Alternating Red and Blue Light Enhances Plant Growth While Keeping Nutritional Quality in Lettuce

Cited by 60 publications

References 47 publications

Alternating Red and Blue Light-Emitting Diodes Allows for Injury-Free Tomato Production With Continuous Lighting

Alternating Red and Blue Light-Emitting Diodes Allows for Injury-Free Tomato Production With Continuous Lighting

Improvement of the Growth and Nutritional Quality of Two-leaf-color Pak Choi by Supplemental Alternating Red and Blue Light

Blue and red light upregulate α-expansin 1 (EXPA1) in transgenic Brassica rapa and its overexpression promotes leaf and root growth in Arabidopsis

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