Abstract
Light-emitting diodes (LEDs) of short wavelength ranges are being developed as light sources in closed-type plant production systems. Among the various wavelengths, red and blue lights are known to be effective for enhancing plant photosynthesis. In this study, we determined the effects of blue and red LED ratios on leaf shape, plant growth, and the accumulation of antioxidant phenolic compounds of a red leaf lettuce ( Lactuca sativa L. ‘Sunmang’) and a green leaf lettuce ( Lactuca sativa L. ‘Grand Rapid TBR’). Lettuce seedlings grown under normal growth conditions (20 °C, fluorescent lamp + high-pressure sodium lamp 177 ± 5 μmol·m −2 ·s −1 , 12-hour photoperiod) for 18 days were transferred into growth chambers that were set at 20 °C and equipped with various combinations of blue (456 nm) and red (655 nm) LEDs [blue:red = 0:100 (0 B), 13:87 (13 B), 26:74 (26 B), 35:65 (35 B), 47:53 (47 B) or 59:41 (59 B)] under the same light intensity and photoperiod (171 ± 7 μmol·m −2 ·s −1 , 12-hour photoperiod). Leaf width, leaf length, leaf area, fresh and dry weights of shoots and roots, chlorophyll content (SPAD value), total phenolic concentration, total flavonoid concentration, and antioxidant capacity were measured at 2 and 4 weeks after the onset of LED treatment. The leaf shape indices (leaf length/leaf width) of the two lettuce cultivars subjected to blue LEDs treatment were similar to the control, regardless of the blue-to-red ratio during the entire growth stage. However, 0 B (100% red LED) induced a significantly higher leaf shape index, which represents elongated leaf shape, compared with the other treatments. Increasing blue LED levels negatively affected lettuce growth. Most growth characteristics (such as the fresh and dry weights of shoots and leaf area) were highest under 0 B for both cultivars compared with all other LED treatments. For red and green leaf lettuce cultivar plants, shoot fresh weight under 0 B was 4.3 and 4.1 times higher compared with that under 59 B after 4 weeks of LED treatment, respectively. In contrast, the accumulation of chlorophyll, phenolics (including flavonoids), and antioxidants in both red and green leaf lettuce showed an opposite trend compared with that observed for growth. The SPAD value (chlorophyll content), total phenolic concentration, total flavonoid concentration, and antioxidant capacity of lettuces grown under high ratios of blue LED (such as 59 B, 47 B, and 35 B) were significantly higher compared with 0 B or control conditions. Thus, this study indicates that the ratio of blue to red LEDs is important for the morphology, growth, and phenolic compounds with antioxidant properties in the two lettuce cultivars tested.
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Claims 7
Claim · model-written summary
Blue LED treatments had leaf shape indices similar to the control in both lettuce cultivars.
- Taxon
- Lettuce
Lactuca sativat0 - Treatment
- blue LEDs treatmente0
- Outcome
- leaf shape indicese0
- Direction
- similare0
- Comparator
- controle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The leaf shape indices (leaf length/leaf width) of the two lettuce cultivars subjected to blue LEDs treatment were similar to the control”
t0“Lettuce Cultivars”
Claim · model-written summary
The 0 B treatment produced a significantly higher, elongated leaf shape index than other treatments.
- Taxon
- LettuceLactuca sativat0
- Treatment
- 0 B (100% red LED)e0
- Outcome
- leaf shape indexe0
- Direction
- highere0
- Comparator
- the other treatmentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“0 B (100% red LED) induced a significantly higher leaf shape index, which represents elongated leaf shape, compared with the other treatments”
t0“Lettuce Cultivars”
Claim · model-written summary
Increasing blue LED levels negatively affected lettuce growth.
- Taxon
- lettuceLactuca sativae0
- Treatment
- blue LED levelse0
- Outcome
- lettuce growthe0
- Direction
- negativelye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Increasing blue LED levels negatively affected lettuce growth”
Claim · model-written summary
Shoot fresh and dry weights and leaf area were highest under 0 B in both cultivars.
- Taxon
- LettuceLactuca sativat0
- Treatment
- 0 Be0
- Outcome
- fresh and dry weights of shoots and leaf areae0
- Direction
- higheste0
- Comparator
- all other LED treatmentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Most growth characteristics (such as the fresh and dry weights of shoots and leaf area) were highest under 0 B for both cultivars compared with all other LED treatments”
t0“Lettuce Cultivars”
Claim · model-written summary
Under 0 B, shoot fresh weight was 4.3 times higher than under 59 B for red leaf lettuce after four weeks.
- Taxon
- lettuceLactuca sativae0
- Material
- rede0
- Treatment
- 0 Be0
- Outcome
- shoot fresh weighte0
- Direction
- highere0
- Value
- 4.3e0
- Comparator
- 59 Be0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“For red and green leaf lettuce cultivar plants, shoot fresh weight under 0 B was 4.3 and 4.1 times higher compared with that under 59 B after 4 weeks of LED treatment, respectively”
Claim · model-written summary
Under 0 B, shoot fresh weight was 4.1 times higher than under 59 B for green leaf lettuce after four weeks.
- Taxon
- lettuceLactuca sativae0
- Material
- greene0
- Treatment
- 0 Be0
- Outcome
- shoot fresh weighte0
- Direction
- highere0
- Value
- 4.1 timese0
- Comparator
- 59 Be0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“For red and green leaf lettuce cultivar plants, shoot fresh weight under 0 B was 4.3 and 4.1 times higher compared with that under 59 B after 4 weeks of LED treatment, respectively”
Claim · model-written summary
High blue LED ratios produced significantly higher chlorophyll content, phenolics, flavonoids and antioxidant capacity than 0 B or control.
- Taxon
- lettucesLactuca sativae0
- Treatment
- high ratios of blue LEDe0
- Outcome
- SPAD value (chlorophyll content), total phenolic concentration, total flavonoid concentration, and antioxidant capacitye0
- Direction
- highere0
- Comparator
- 0 B or control conditionse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The SPAD value (chlorophyll content), total phenolic concentration, total flavonoid concentration, and antioxidant capacity of lettuces grown under high ratios of blue LED (such as 59 B, 47 B, and 35 B) were significantly higher compared with 0 B or control conditions”
The same questions in other papers
light · physiology: pigments · Lactuca sativa (garden lettuce)Positive and negative results
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See all 52 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.