Long-term Blue Light Effects on the Histology of Lettuce and Soybean Leaves and Stems

Dougher, Tracy A. O.; Bugbee, Bruce

doi:10.21273/jashs.129.4.0467

Cited by 97 publications

(63 citation statements)

References 13 publications

(23 reference statements)

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“…These results support earlier evidence that increasing the ratio of R to B light increases the hypocotyl length in lettuce [45]. The lower leaf LA and plant height in treatments with high B/R light ratios may be associated with a B light-mediated inhibition of cell expansion [46]. A similar result was reported by Samuoliene et al [47], who showed that an optimal combination of B/R light ratios enhances the plant growth rate in controlled conditions.…”

Section: Lettuce Morphology Characteristics Are Affected By the B/r Lsupporting

confidence: 91%

The Evaluation of Growth Performance, Photosynthetic Capacity, and Primary and Secondary Metabolite Content of Leaf Lettuce Grown under Limited Irradiation of Blue and Red LED Light in an Urban Plant Factory

et al. 2020

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Plant production in urban areas is receiving much attention due to its potential role in feeding the rapidly growing population of city dwellers. However, higher energy demands in urban plant factories are among the key challenges that need to be addressed. Artificial lighting is responsible for the most significant levels of energy consumption in plant factories; therefore, lighting systems must be modulated in consideration of the sustainable food–energy nexus. In this context, low light irradiation using blue (B) and red (R) LED was applied in a plant factory for the growth of red leaf lettuce (Lactuca sativa L. var Lollo rosso) to evaluate the growth performance and functional quality. The tested B (450 nm) and R (660 nm) light ratios were B/R = 5:1; 3:1; 1:1; 1:3, and 1:5, with a photosynthetic photon flux density (PPFD) of 90 ± 3 µmol m−2 s−1. In the plant factory, the photoperiod, temperature, RH, and CO2 conditions were 16 h d−1, 20 ± 0.5 °C, 65% ± 5%, and 360 ± 10 μL L−1, respectively. The lettuce was harvested 10 and 20 days after the commencement of LED light treatment (DAT). In this study, normal photosynthetic activity and good visual quality of the lettuce were observed. The results show that a higher fraction of R (B/R = 1:5) significantly increased plant growth parameters such as plant height, leaf area, specific leaf area, plant fresh and dry weight, and carbohydrate content. By contrast, a higher fraction of B (B/R = 5:1) significantly increased the photosynthetic parameters and contents of pigment and phenolic compounds. The rate of photosynthetic performance, carbohydrates (except starch), and content of phenolic compounds were highest after 10 DAT, whereas the pigment contents did not significantly differ at the different growth stages. It is concluded that high R fractions favor plant growth and carbohydrate content, while high B fractions favor photosynthetic performance and the accumulation of pigments and phenolic compounds in red leaf lettuce under limited lighting conditions. This study will help in designing artificial lighting conditions for plant factory production to reduce energy demands.

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Section: Lettuce Morphology Characteristics Are Affected By the B/r Lsupporting

confidence: 91%

The Evaluation of Growth Performance, Photosynthetic Capacity, and Primary and Secondary Metabolite Content of Leaf Lettuce Grown under Limited Irradiation of Blue and Red LED Light in an Urban Plant Factory

et al. 2020

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“…However, these responses to higher blue light do not correspond with the literature, which reports a blue light-induced reduction in lettuce leaf area and SLA [5,9]. Smaller, thicker leaves under higher blue light have been associated with a decrease in the size and number of leaf epidermal cells, which tend to reduce overall plant growth due to a reduction in radiation capture [3]. Although we did find a general growth (shoot dry mass) reduction in response to blue light, it cannot be attributed to a decrease in light interception from smaller, thicker leaver ( Figure 2D).…”

Section: Growth Parameterscontrasting

confidence: 65%

“…Increasing blue light (400 nm to 500 nm) often inhibits cell division and expansion, reducing leaf area and stem elongation, and increasing leaf thickness in most plant species; compact plants with smaller, thicker leaves typically result in higher photosynthetic rate per unit of leaf area, but reduced radiation capture [3]. This reduction in radiation capture is believed to be the primary reason for reduced growth (dry mass gain) in response to higher blue light [4].…”

Section: Introductionmentioning

confidence: 99%

Growth, Water-Use Efficiency, Stomatal Conductance, and Nitrogen Uptake of Two Lettuce Cultivars Grown under Different Percentages of Blue and Red Light

2018

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The objective of this study was to characterize growth, water-use efficiency (WUE), stomatal conductance (g s ), SPAD index values, and shoot nitrogen uptake of two lettuce cultivars grown under different percentages of blue and red light. The treatments evaluated were 100% red; 7% blue + 93% red; 26% blue + 74% red; 42% blue + 58% red; 66% blue + 34% red; and 100% blue. Broad-spectrum (19% blue, 43% green, and 38% red) light was used to observe the effects of wavelength interactions. All of the treatments provided an average daily light integral (DLI) of 17.5 mol·m -2 ·d -1 (270 ± 5 µmol·m -2 ·s -1 over an 18-h photoperiod). The experiment was replicated three times over time; each terminated 21 days after treatment initiation. Leaf area, specific leaf area (SLA), and SPAD index had a similar response in that all of the parameters increased with up to 66% blue light, and slightly decreased or remained constant with 100% blue light. In contrast, leaf number, shoot dry mass, and WUE generally decreased in response to blue light. Conversely, for every 10% increase in blue light, g s increased by 10 mmol·m -2 ·s -1 . Nitrogen uptake was unaffected by light quality. Our findings indicate that when grown under different blue and red photon flux ratios, the WUE of lettuce significantly decreases under higher blue light, which could be attributed to a reduction in plant growth (leaf number and dry mass), and an increase in g s . However, green light within broad-spectrum lamps might counteract blue-light mediated effects on g s and WUE in lettuce.

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“…First, green light can penetrate deeper into the plant canopy and, therefore, drive more photosynthesis. Second, reducing the amount of blue reduces the restriction on leaf expansion imposed by plant photoreceptors (Dougher and Bugbee ), thus increasing leaf area, light capture and growth. Research to date suggests that addition of green light to the growth spectrum does not enhance crop performance in all cases.…”

Section: The Influence Of Light Quality On Plant Growthmentioning

confidence: 99%

Photobiology in protected horticulture

Davis

Burns

2016

Food and Energy Security

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The introduction of high power LED lighting systems for horticulture has stimulated substantial interest from both the research community and the protected horticulture industry. LED lighting systems have the potential to reduce electrical energy consumption compared to conventional high pressure sodium lights and their energy efficiency continues to improve. In addition to the potential of LEDs to reduce carbon footprints and reduce running costs, LED lighting also provides considerable opportunities to exploit the wealth of photobiological knowledge to produce horticultural benefits. The narrow emission spectra of LEDs allows lighting systems to be tightly designed to stimulate specific plant photoreceptors, allowing plants to be manipulated to produce desirable characteristics. Lighting systems can be designed to maximize growth, control morphology, and optimize flavor and pigmentation. This review outlines how the light spectrum influences photosynthesis and how plant photoreceptors sense light and control growth. The review then discusses the ways in which this knowledge is being implemented in commercial horticulture to improve factors such as yield, flavor, color, plant growth, and flowering as well as pest and pathogen management and control. Research in this area is moving rapidly as the LED systems improve and increase in efficiency and as the range of novel horticultural applications expands.

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Long-term Blue Light Effects on the Histology of Lettuce and Soybean Leaves and Stems

Cited by 97 publications

References 13 publications

The Evaluation of Growth Performance, Photosynthetic Capacity, and Primary and Secondary Metabolite Content of Leaf Lettuce Grown under Limited Irradiation of Blue and Red LED Light in an Urban Plant Factory

The Evaluation of Growth Performance, Photosynthetic Capacity, and Primary and Secondary Metabolite Content of Leaf Lettuce Grown under Limited Irradiation of Blue and Red LED Light in an Urban Plant Factory

Growth, Water-Use Efficiency, Stomatal Conductance, and Nitrogen Uptake of Two Lettuce Cultivars Grown under Different Percentages of Blue and Red Light

Photobiology in protected horticulture

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