Abstract
The spectral composition of some light-emitting diodes (LEDs) reportedly results in higher crop yield, prevents wilting, and reduces thermal damage to plants. The use of LEDs for postharvest storage and shelf-life extension has been limited, but the potential of this technology will allow for greater applications in horticulture and the food industry. In this experiment, ‘Winterbor’ kale (Brassica oleracea) and ‘Melody’ spinach (Spinacia oleracea) plants were measured for the light compensation point and stomatal response under 14 different wavelengths of light ranging from 405 to 661 nm. Data collected from these measurements were used to select two different wavelengths of LEDs and determine the proper irradiance levels for an LED irradiance storage test on spinach and kale. Treatments comprising blue, red, and amber lights were effective at increasing the stomatal opening, while the green light resulted in reduced stomatal opening. For spinach, the light response curve showed that light compensation points at 500 nm and 560 nm were 65.3 and 64.7 μmol m−2 s−1, respectively. For kale, the light compensation points at 500 nm and 560 nm were 50.8 and 44.1 μmol m−2 s−1, respectively. For the storage test experiment at room temperature, kale and spinach were stored under four different treatments: dark treatment (control), standard white fluorescent light, 500 nm, and 560 nm LED wavelengths. For spinach, the moisture content was 70.1% at 560 nm and 53.7% for dark, moisture losses of 41.5% under the 560-nm treatment and 52.0% for the dark treatment. The fresh basis moisture content was 74.6% at 560 nm and 59.3% in the dark. Moisture loss under the 560 nm treatment was 39.6% while the dark treatment had a 54.0% moisture loss. A visual assessment scale was monitored, 560 nm resulted in the top visual quality for kale compared to the other treatments with the lowest visual quality under the dark treatment at day 4. For spinach, the visual quality for 560 nm treatment was statistically the standard white fluorescent light and 500 nm, with poor-quality product occurring by day 4 and the lowest-quality product occurring at day 5. The LED treatments improved the shelf life of spinach and kale, likely as a result of stomatal aperture closure, photosynthetic rate near the light compensation point and stability of the atmospheric moisture content. This study provides valuable information on the extension of the shelf life of leafy greens during storage. Reducing fresh produce waste in grocery stores will increase revenue, thereby benefiting the Canadian economy while providing social and environmental benefits that entail increased food security and reduced food waste.
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Claims 14
Claim · model-written summary
Blue, red and amber light increased stomatal opening in spinach and kale.
- Taxon
- spinach and kale
Spinacia oleracea
Brassica oleracea var. viridist0 - Treatment
- blue, red, and amber lightse0
- Outcome
- stomatal openinge0
- Direction
- increasinge0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Treatments comprising blue, red, and amber lights were effective at increasing the stomatal opening”
t0“spinach and kale”
Claim · model-written summary
Green light reduced stomatal opening in spinach and kale.
- Taxon
- spinach and kaleSpinacia oleraceaBrassica oleracea var. viridist0
- Treatment
- green lighte0
- Outcome
- stomatal openinge0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the green light resulted in reduced stomatal opening”
t0“spinach and kale”
Claim · model-written summary
Spinach had a light compensation point of 65.3 μmol m−2 s−1 at 500 nm.
- Taxon
- spinachSpinacia oleraceae0
- Outcome
- light compensation pointse0
- Value
- 65.3e0
- Qualifier
- 500 nme0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“For spinach, the light response curve showed that light compensation points at 500 nm and 560 nm were 65.3 and 64.7 μmol m−2 s−1, respectively”
Claim · model-written summary
Spinach had a light compensation point of 64.7 μmol m−2 s−1 at 560 nm.
- Taxon
- spinachSpinacia oleraceae0
- Outcome
- light compensation pointse0
- Value
- 64.7 μmol m−2 s−1e0
- Qualifier
- 560 nme0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“For spinach, the light response curve showed that light compensation points at 500 nm and 560 nm were 65.3 and 64.7 μmol m−2 s−1, respectively”
Claim · model-written summary
Kale had a light compensation point of 50.8 μmol m−2 s−1 at 500 nm.
- Taxon
- kaleBrassica oleracea var. viridise0
- Outcome
- light compensation pointse0
- Value
- 50.8e0
- Qualifier
- 500 nme0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“For kale, the light compensation points at 500 nm and 560 nm were 50.8 and 44.1 μmol m−2 s−1, respectively”
Claim · model-written summary
Kale had a light compensation point of 44.1 μmol m−2 s−1 at 560 nm.
- Taxon
- kaleBrassica oleracea var. viridise0
- Outcome
- light compensation pointse0
- Value
- 44.1 μmol m−2 s−1e0
- Qualifier
- 560 nme0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“For kale, the light compensation points at 500 nm and 560 nm were 50.8 and 44.1 μmol m−2 s−1, respectively”
Claim · model-written summary
At 560 nm, spinach moisture content was 70.1%, versus 53.7% in darkness.
- Taxon
- spinachSpinacia oleraceae0
- Treatment
- 560 nme0
- Outcome
- moisture contente0
- Direction
- higherinferrede0
- Value
- 70.1%e0
- Qualifier
- 53.7%e0
- Comparator
- darke0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“For spinach, the moisture content was 70.1% at 560 nm and 53.7% for dark”
Claim · model-written summary
At 560 nm, spinach moisture loss was 41.5%, versus 52.0% in darkness.
- Taxon
- spinachSpinacia oleraceat0
- Treatment
- 560-nm treatmente0
- Outcome
- moisture lossese0
- Direction
- lowerinferrede0
- Value
- 41.5%e0
- Qualifier
- 52.0%e0
- Comparator
- dark treatmente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“moisture losses of 41.5% under the 560-nm treatment and 52.0% for the dark treatment”
t0“spinach”
Claim · model-written summary
At 560 nm, kale fresh basis moisture content was 74.6%, versus 59.3% in darkness.
- Taxon
- kaleBrassica oleracea var. viridist0
- Treatment
- 560 nme0
- Outcome
- fresh basis moisture contente0
- Direction
- higherinferrede0
- Value
- 74.6%e0
- Qualifier
- 59.3%e0
- Comparator
- darke0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The fresh basis moisture content was 74.6% at 560 nm and 59.3% in the dark”
t0“kale”
Claim · model-written summary
At 560 nm, kale moisture loss was 39.6%, versus 54.0% in darkness.
- Taxon
- kaleBrassica oleracea var. viridist0
- Treatment
- 560 nm treatmente0
- Outcome
- Moisture losse0
- Direction
- lowerinferrede0
- Value
- 39.6%e0
- Qualifier
- 54.0%e0
- Comparator
- dark treatmente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Moisture loss under the 560 nm treatment was 39.6% while the dark treatment had a 54.0% moisture loss”
t0“kale”
Claim · model-written summary
At day 4, kale under 560 nm had the best visual quality and darkness the worst.
- Taxon
- kaleBrassica oleracea var. viridise0
- Treatment
- 560 nme0
- Outcome
- visual qualitye0
- Direction
- tope0
- Qualifier
- day 4e0
- Comparator
- dark treatmente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“560 nm resulted in the top visual quality for kale compared to the other treatments with the lowest visual quality under the dark treatment at day 4”
Claim · model-written summary
Spinach under 560 nm had visual quality statistically similar to white fluorescent light and 500 nm, with poor quality by day 4 and the lowest quality on day 5.
- Taxon
- spinachSpinacia oleraceae0
- Outcome
- visual qualitye0
- Qualifier
- poor-quality product occurring by day 4 and the lowest-quality product occurring at day 5e0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“For spinach, the visual quality for 560 nm treatment was statistically the standard white fluorescent light and 500 nm, with poor-quality product occurring by day 4 and the lowest-quality product occurring at day 5”
Claim · model-written summary
LED treatments improved the shelf life of spinach.
- Taxon
- spinachSpinacia oleraceae0
- Treatment
- LED treatmentse0
- Outcome
- shelf lifee0
- Direction
- improvede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The LED treatments improved the shelf life of spinach and kale”
Claim · model-written summary
LED treatments improved the shelf life of kale.
- Taxon
- kaleBrassica oleracea var. viridise0
- Treatment
- LED treatmentse0
- Outcome
- shelf lifee0
- Direction
- improvede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The LED treatments improved the shelf life of spinach and kale”
The same questions in other papers
light · physiology: gas exchange · Brassica oleracea (wild cabbage)Positive and negative results
1 paper in the same direction as this paper · 1 in the opposite direction
- no effect
- positive
light · physiology: gas exchange · Spinacia oleracea (spinach)Positive and negative results
1 paper in the same direction as this paper · 1 reporting no difference from an alternative
- no effect
- positive
light · quality: postharvest · Spinacia oleracea (spinach)Positive and negative results
2 papers in the same direction as this paper · 1 in the opposite direction
- positive
- positive
- negative
light · quality: postharvest · Brassica oleracea (wild cabbage)Positive and negative results
7 papers in the same direction as this paper · 3 in the opposite direction
- no effect
- no effect
- negative
7 papers more in this group
See all 11 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.