Abstract
Amid the growing global demand for sustainable crop production, plant factories with artificial lighting (PFALs) have gained attention as the systems provide stable, optimal growth environments for crops, and are largely unaffected by climate change. However, a limitation of widely used light-emitting diodes (LEDs) in PFALs is their decreased energy conversion efficiency at high output levels, prompting the search for more efficient light sources. This study focused on laser diodes (LDs), which has shown superior energy conversion efficiency, as an alternative. We developed an LD lighting system capable of mixing red and blue light at arbitrary ratios and mounted it onto a commercial gas-exchange measurement system. Using this system, photosynthetic parameters in rice were obtained under conditions of red light alone and as well as combined red and blue light illumination. Under red LD illumination alone, steady-state CO 2 assimilation rate, stomatal conductance, and transpiration rate in rice were significantly higher than those under red LED illumination, whereas intrinsic water-use efficiency decreased due to a relatively greater increase in stomatal conductance. Notably, stomatal conductance and transpiration rate exhibited pronounced temporal oscillations with a period of approximately 900 s, which closely corresponded to oscillations in stomatal aperture confirmed by microscopic observations. Under combined red and blue LD illumination, steady-state photosynthetic parameters did not differ significantly from those under LED illumination; however, the dominant oscillatory frequency observed under red LD alone was not detected, and some photosynthetic capacity parameters tended to decline. Furthermore, CO 2 response analyses revealed that, despite lower CO 2 assimilation, stomatal conductance responded more strongly to changes in intercellular CO 2 concentration under combined red and blue LD illumination. Taken together, these results demonstrate that LD lighting, particularly red LD, enhances stomatal dynamics and induces characteristic oscillatory behavior compared with LED lighting. While red LD appears to be a promising cultivation light source for PFALs capable of maintaining high photosynthetic activity, the physiological impacts associated with blue LD, including potential reductions in photosynthetic capacity, require further study to optimize blue-light proportions for rice cultivation.
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Claims 12
Claim · model-written summary
Red LD raised steady-state CO 2 assimilation rate relative to red LED in rice.
- Taxon
- rice
Oryza sativae0 - Treatment
- red LD illumination alonee0
- Outcome
- steady-state CO 2 assimilation ratee0
- Direction
- highere0
- Comparator
- red LED illuminatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Under red LD illumination alone, steady-state CO 2 assimilation rate, stomatal conductance, and transpiration rate in rice were significantly higher than those under red LED illumination”
Claim · model-written summary
Red LD raised stomatal conductance relative to red LED in rice.
- Taxon
- riceOryza sativae0
- Treatment
- red LD illumination alonee0
- Outcome
- stomatal conductancee0
- Direction
- highere0
- Comparator
- red LED illuminatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Under red LD illumination alone, steady-state CO 2 assimilation rate, stomatal conductance, and transpiration rate in rice were significantly higher than those under red LED illumination”
Claim · model-written summary
Red LD raised transpiration rate relative to red LED in rice.
- Taxon
- riceOryza sativae0
- Treatment
- red LD illumination alonee0
- Outcome
- transpiration ratee0
- Direction
- highere0
- Comparator
- red LED illuminatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Under red LD illumination alone, steady-state CO 2 assimilation rate, stomatal conductance, and transpiration rate in rice were significantly higher than those under red LED illumination”
Claim · model-written summary
Intrinsic water-use efficiency decreased under red LD.
- Taxon
- riceOryza sativat0
- Treatment
- red LDe1
- Outcome
- intrinsic water-use efficiencye0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“intrinsic water-use efficiency decreased due to a relatively greater increase in stomatal conductance.”
t0“transpiration rate in rice were significantly higher”
e1“Under red LD illumination alone, steady-state CO 2 assimilation rate, stomatal conductance, and transpiration rate in rice were significantly higher than those under red LED illumination”
Claim · model-written summary
Stomatal conductance oscillated with an approximately 900 s period.
- Taxon
- riceOryza sativat0
- Treatment
- red LDe1
- Outcome
- stomatal conductancee0
- Value
- approximately 900 se0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“stomatal conductance and transpiration rate exhibited pronounced temporal oscillations with a period of approximately 900 s”
t0“transpiration rate in rice were significantly higher”
e1“Under red LD illumination alone, steady-state CO 2 assimilation rate, stomatal conductance, and transpiration rate in rice were significantly higher than those under red LED illumination”
Claim · model-written summary
Transpiration rate oscillated with an approximately 900 s period.
- Taxon
- riceOryza sativat0
- Treatment
- red LDe1
- Outcome
- transpiration ratee0
- Value
- approximately 900 se0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“stomatal conductance and transpiration rate exhibited pronounced temporal oscillations with a period of approximately 900 s”
t0“transpiration rate in rice were significantly higher”
e1“Under red LD illumination alone, steady-state CO 2 assimilation rate, stomatal conductance, and transpiration rate in rice were significantly higher than those under red LED illumination”
Claim · model-written summary
Stomatal aperture oscillations corresponded to gas-exchange oscillations.
- Taxon
- riceOryza sativat0
- Organ / stage
- stomatal aperturee0
- Outcome
- oscillations in stomatal aperturee0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“which closely corresponded to oscillations in stomatal aperture confirmed by microscopic observations.”
t0“transpiration rate in rice were significantly higher”
Claim · model-written summary
Combined red and blue LD did not significantly change steady-state photosynthetic parameters versus LED.
- Taxon
- riceOryza sativat0
- Treatment
- combined red and blue LD illuminatione0
- Outcome
- steady-state photosynthetic parameterse0
- Direction
- did not differe0
- Comparator
- LED illuminatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Under combined red and blue LD illumination, steady-state photosynthetic parameters did not differ significantly from those under LED illumination”
t0“transpiration rate in rice were significantly higher”
Claim · model-written summary
Combined red and blue LD eliminated the dominant oscillatory frequency seen under red LD.
- Taxon
- riceOryza sativat0
- Treatment
- combined red and blue LDe0
- Outcome
- dominant oscillatory frequencye0
- Direction
- not detectede0
- Comparator
- red LD alonee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Under combined red and blue LD illumination, steady-state photosynthetic parameters did not differ significantly from those under LED illumination; however, the dominant oscillatory frequency observed under red LD alone was not detected”
t0“transpiration rate in rice were significantly higher”
Claim · model-written summary
Some photosynthetic capacity parameters tended to decline with combined red and blue LD.
- Taxon
- riceOryza sativat0
- Treatment
- combined red and blue LDe0
- Outcome
- photosynthetic capacity parameterse0
- Direction
- declinee0
- Qualifier
- tended toe0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Under combined red and blue LD illumination, steady-state photosynthetic parameters did not differ significantly from those under LED illumination; however, the dominant oscillatory frequency observed under red LD alone was not detected, and some photosynthetic capacity parameters tended to decline.”
t0“transpiration rate in rice were significantly higher”
Claim · model-written summary
Under combined red and blue LD, stomatal conductance responded more strongly to intercellular CO2 changes.
- Taxon
- riceOryza sativat0
- Treatment
- combined red and blue LD illuminatione0
- Compound
- CO 2e0
- Outcome
- stomatal conductancee0
- Direction
- more stronglye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“stomatal conductance responded more strongly to changes in intercellular CO 2 concentration under combined red and blue LD illumination.”
t0“transpiration rate in rice were significantly higher”
Claim · model-written summary
The authors propose red LD as a promising cultivation light source.
- Taxon
- riceOryza sativat0
- Treatment
- red LDe0
- Outcome
- promising cultivation light source for PFALse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“red LD appears to be a promising cultivation light source for PFALs capable of maintaining high photosynthetic activity”
t0“transpiration rate in rice were significantly higher”
The same questions in other papers
light · physiology: photosynthesis · Oryza sativa (rice)Results differ
23 papers in the same direction as this paper · 23 in the opposite direction
- negative
- negative
- negative
43 papers more in this group
See all 47 papers →light · physiology: gas exchange · Oryza sativa (rice)Positive and negative results
2 papers in the same direction as this paper · 1 in the opposite direction
- negative
- positive
- positive
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.