Abstract
The energy costs for artificial lighting in plant factories are very high, but may be decreased by introducing more efficient light sources. Light absorption in plants takes place in the order of a femtosecond, while the chemical reactions for carbon fixation of 5 milliseconds are limiting the processing of photons by the photosystems. In this article, the ShowwxTM scanning laser projector (0.1 W) was tested as an energy-efficient lighting source for cultivating lettuce (Lactuca sativa L. cv. Frillice). This projector uses a mirror where three laser beams are combined and scanned in diverging bi-directional pattern. The average pixel scan time is 20 nanoseconds, while the scanning of the complete projection takes 17 milliseconds. The laser projector was used for artificial lighting of lettuce seedlings (1 week after sowing) and bigger crops (4 weeks after sowing). The light levels were very low (10–20 μmol m−2 s−1) in order to adapt the illumination area of the laser projector to the plant area. A fluorescent lamp (8 W) was used as a reference light source and was mounted on a height, where an equal PPFD was measured at plant height. No differences in relative growth rate were observed in both experiments between the two light sources. A higher final fresh weight was observed for the seedlings illuminated using the scanning laser projector. This particular projector was considered to be not suitable as an artificial light source, but an improved scanning laser projector (with higher laser powers) provides opportunities to improve light efficiency and decrease production costs greatly.
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Claims 4
Claim · model-written summary
Relative growth rate did not differ between light sources in either experiment.
- Taxon
- lettuce
Lactuca sativae1 - Treatment
- two light sourcese0
- Outcome
- relative growth ratee0
- Direction
- No differencese0
- Comparator
- two light sourcese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“No differences in relative growth rate were observed in both experiments between the two light sources.”
e1“cultivating lettuce (Lactuca sativa L. cv. Frillice)”
Claim · model-written summary
Laser-illuminated seedlings had higher final fresh weight.
- Taxon
- lettuceLactuca sativae1
- Treatment
- scanning laser projectore0
- Outcome
- final fresh weighte0
- Direction
- highere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A higher final fresh weight was observed for the seedlings illuminated using the scanning laser projector.”
e1“cultivating lettuce (Lactuca sativa L. cv. Frillice)”
Claim · model-written summary
The tested projector was considered unsuitable as an artificial light source.
- Taxon
- lettuceLactuca sativae1
- Outcome
- not suitable as an artificial light sourcee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This particular projector was considered to be not suitable as an artificial light source”
e1“cultivating lettuce (Lactuca sativa L. cv. Frillice)”
Claim · model-written summary
An improved higher-power projector was proposed to increase light efficiency and reduce production cost.
- Taxon
- lettuceLactuca sativae1
- Outcome
- improve light efficiency and decrease production costs greatlye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“an improved scanning laser projector (with higher laser powers) provides opportunities to improve light efficiency and decrease production costs greatly.”
e1“cultivating lettuce (Lactuca sativa L. cv. Frillice)”
The same questions in other papers
light · growth · Lactuca sativa (garden lettuce)Positive and negative results
56 papers in the same direction as this paper · 243 reporting no difference from an alternative
- positive
- positive
- positive
296 papers more in this group
See all 300 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.