Short-Term Pre-Harvest Supplemental Lighting with Different Light Emitting Diodes Improves Greenhouse Lettuce Quality

Hooks, Triston; Sun, Ling; Kong, Yun; Masabni, Joseph; Niu, Genhua

doi:10.3390/horticulturae8050435

Cited by 13 publications

(10 citation statements)

References 34 publications

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“…Although the above-recommended UV dose is not higher than the usual outside UV intensity, care must be taken for the safety of greenhouse staff with supplemental UV lighting. Nighttime supplemental lighting in red lettuce was more effective than daytime supplemental lighting, as it resulted in better crop quality [31]. In addition, the application of shortduration supplemental blue LED light may become more effective in the pigmentation of red lettuce if applied during night breaks [32].…”

Section: Discussionmentioning

confidence: 99%

Ultraviolet Radiation Management in Greenhouse to Improve Red Lettuce Quality and Yield

et al. 2022

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The intensity of ultraviolet (UV) radiation affects the yield and quality of red lettuce. The current study aimed to develop a UV management system in a greenhouse to achieve high yield and quality in red lettuce production. The study consisted of two experiments. In the first experiment, the effects of the different UV transparencies of the plastic materials covering the greenhouse on plant growth and the concentration of antioxidants in red lettuce were studied. For this purpose, two greenhouses were covered with polyethene of different transparencies to UV radiation. One greenhouse was covered with a common type of polyethene transparent in a large spectrum of UV radiation (UV-open), while the second greenhouse was covered with polyethene untransparent to ultraviolet radiation (UV-block). The plants were grown in a deep flotation hydroponic system. At the end of the cultivation, plant growth measurements, leaf colour measurements, and the determination of antioxidant components’ concentration were carried out. Red lettuce plants harvested 42 days after planting had an average head weight 42% greater in the UV-block greenhouse compared to plants grown in the UV-open greenhouse. However, the red leaf colour of plants in the UV-block greenhouse lagged significantly compared to that in the UV-open greenhouse. Moreover, the total phenolic content, the total flavonoid content, and the antioxidant capacity of the lettuce leaves in the UV-block greenhouse were significantly lower compared to the corresponding values of the plants in the UV-open greenhouse. During the second experiment, a new cultivation system of red lettuce, which combined a UV-block polyethene film as a greenhouse cover and a pre-harvested supplemental UV light, was tested. For this purpose, various doses of supplemental UV lighting were tested in the UV-block greenhouse for ten days prior to harvest. From these tests, it emerged that applying supplemental UV lighting with a dose of 425 kJ m−2 d−1 for ten days before harvest produces red lettuces of the same quality as those produced in a UV-open greenhouse. This technique of growing red lettuce increases its yield by 30% without a negative effect on the quality of the product.

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Section: Discussionmentioning

confidence: 99%

Ultraviolet Radiation Management in Greenhouse to Improve Red Lettuce Quality and Yield

et al. 2022

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“…In addition, adding UVA (5-7% of photosynthetic photon flux density) to blue-LEDs reduced plant height for some microgreen species [14]. Our recent study found that short-term preharvest lighting treatment with UVA/Blue LEDs (containing both UVA and blue wavelengths) increased the antioxidant concentrations of greenhouse-grown lettuce plants without compromising plant growth and biomass [15,16]. To the best of our knowledge, the effects of adding UVA to W-LEDs on the growth and quality of indoor microgreens, for either the whole production period or at the end, remain unknown.…”

Section: Introductionmentioning

confidence: 99%

Adding UVA and Far-Red Light to White LED Affects Growth, Morphology, and Phytochemicals of Indoor-Grown Microgreens

Hooks¹,

Sun²,

Kong³

et al. 2022

Sustainability

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White light emitting diodes (LED) have commonly been used as a sole light source for the indoor production of microgreens. However, the response of microgreens to the inclusion of ultraviolet A (UVA) and/or far-red (FR) light to white LED light remains unknown. To investigate the effects of adding UVA and FR light to white LEDs on plant biomass, height, and the concentrations of phytochemicals, four species of microgreens including basil, cabbage, kale, and kohlrabi were grown under six light treatments. The first three treatments were white LED (control) and two UVA treatments (adding UVA to white LED for the whole growth period or for the last 5 days). Another three treatments consisted of adding FR to the first three treatments. The total photon flux density (TPFD) for all six light treatments was the same. The percentages of UVA and FR photons in the TPFD were 23% and 32%, respectively. Compared to white LEDs, adding UVA throughout the growth period did not affect plant height in all the species except for basil, where 9% reduction was observed regardless of the FR light. On the contrary, the addition of FR light increased plant heights by 9–18% for basil, cabbage, and kohlrabi, regardless of the UVA treatment, compared to white LED. Furthermore, regardless of UVA, adding FR to white LEDs reduced the plant biomass, total phenolic contents, and antioxidant concentrations for at least one species. There was no interaction between FR and UVA on all the above growth and quality traits for all the species. In summary, microgreens were more sensitive to the addition of FR light compared to UVA; however, the addition of FR to white LEDs may reduce yields and phytochemicals in some species.

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“…Pre-harvest is a practical method that can help to improve the quality and shelf-life of vegetables and reduce their risk before harvest [9][10][11]. For example, Gil [9] studied pre-harvest related to agricultural practices, including type and rate of fertilization, irrigation, and salinity, which affect fresh-cut quality, and found that pre-harvest factors increased the quality of fresh-cut lettuce and baby leaves.…”

Section: Introductionmentioning

confidence: 99%

Effect of Pre-harvest Periods by Replacing Nutrient Solution with Tap Water on Nitrate and Quality in Hydroponic Lettuce

Ruangrak

Salaemae

Sornnok

et al. 2023

ASEAN Sci Tech Rept

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Lettuce (Lactuca sativa L.) is a high-value nutritional food for human consumption, rich in minerals and vitamins. However, people are still concerned about the residues of nitrate content in hydroponic lettuce. Pre-harvesting by replacing nutrient solution with tap water is one of several factors that can help to reduce nitrate content and improve the quality of hydroponic lettuce. Therefore, this study focused on the effect of pre-harvest periods by replacing nutrient solution with tap water on nitrate and quality in hydroponic lettuce. This experiment was performed by replacing nutrient solution with tap water in a hydroponic system for 0 h, 24 h, 48 h, and 72 h before harvesting the lettuce product. Nitrate, vitamin C, phenolic, and soluble sugar contents were determined. The results showed that nitrate content was lowest under pre-harvest conditions for 72 h (19 mg/g dry weight, 63% reduction), but it was not significantly different for 48 h (20 mg/g dry weight, 61% reduction). The vitamin C content was significantly decreased after pre-harvesting for 72 h (5.3 µg/100 g, 30% reduction). The soluble sugar content was significantly increased and reached its highest content after pre-harvest for 48 h (3.3 mg/100 g, 105% increase), but there was no significant difference at 72 h (3.2 mg/100 g, 98% increase). Although the phenolic content decreased slightly, there was no significant difference among the treatments. In conclusion, nitrate contents were reduced the lowest, and soluble sugar contents were increased the highest after pre-harvest for 48 h. Vitamin C and phenolic contents were slightly decreased after pre-harvest periods by replacing the nutrient solution with tap water.

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Short-Term Pre-Harvest Supplemental Lighting with Different Light Emitting Diodes Improves Greenhouse Lettuce Quality

Cited by 13 publications

References 34 publications

Ultraviolet Radiation Management in Greenhouse to Improve Red Lettuce Quality and Yield

Ultraviolet Radiation Management in Greenhouse to Improve Red Lettuce Quality and Yield

Adding UVA and Far-Red Light to White LED Affects Growth, Morphology, and Phytochemicals of Indoor-Grown Microgreens

Effect of Pre-harvest Periods by Replacing Nutrient Solution with Tap Water on Nitrate and Quality in Hydroponic Lettuce

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