Abstract
Adding far-red (FR) photons to a constant photosynthetic photon flux density (PPFD) alters photosynthesis, leaf morphology, and biomass accumulation of horticultural plants. However, the influences of partially substituting PPFD with FR photons under the same extended PPFD (ePPFD) on the growth of greenhouse lettuce ( Lactuca sativa L.) is still unknown. In this study, loose-leaf lettuce (‘Dasusheng’) grown in a greenhouse in the fall was implemented using six supplementary light treatments including white plus red (WR) LEDs with substitutive FR photon flux density at 0, 10, 30, 50, 70, and 90 µmol·m −2 ·s −1 under the same ePPFD (WR139, WR129+FR10, WR109+FR30, WR89+FR50, WR69+FR70, and WR49+FR90, respectively). Lettuce grown with natural light only was designated as NL. The results indicated that supplementary light led to lower plant height, thicker leaves, higher biomass accumulation, higher vitamin C content, higher starch content, and higher total soluble sugar content in lettuce compared with those of lettuce grown under NL. Lettuce grown under WR139 resulted in a 40.0% decrease in plant height, 66.8% increase in leaf thickness, and 34.1% increase in shoot fresh weight compared with those of lettuce grown under NL. No significant differences were observed in leaf width, specific leaf area, shoot fresh weight, root fresh weight, shoot dry weight, root dry weight, soil plant analysis development value, apparent quantum yield, soluble protein content, and light use efficiency of lettuce among the WR139, WR129+FR10, and WR109+FR30 treatments. Furthermore, decreased trends were observed in the biomass accumulation and maximum net photosynthetic rate of lettuce with the increased substituted FR photon flux density. However, an opposite trend was found in the maximum photochemical quantum yield. In conclusion, partially substituting PPFD with FR photons at 10 to 30 μmol·m −2 ·s −1 had similar effects on the biomass accumulation and nutritional quality of greenhouse lettuce. The FR photons should be applied with the consideration of photon flux density because the results also demonstrated negative effects of excess substituted FR photons for PPFD.
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Claims 13
Claim · model-written summary
Supplementary light lowered lettuce height relative to natural light.
- Taxon
- lettuce
Lactuca sativae0 - Treatment
- supplementary lighte0
- Outcome
- plant heighte0
- Direction
- lowere0
- Comparator
- NLe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“supplementary light led to lower plant height, thicker leaves, higher biomass accumulation, higher vitamin C content, higher starch content, and higher total soluble sugar content in lettuce compared with those of lettuce grown under NL.”
Claim · model-written summary
Supplementary light made lettuce leaves thicker than natural light.
- Taxon
- lettuceLactuca sativae0
- Treatment
- supplementary lighte0
- Outcome
- leavese0
- Direction
- thickere0
- Comparator
- NLe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“supplementary light led to lower plant height, thicker leaves, higher biomass accumulation, higher vitamin C content, higher starch content, and higher total soluble sugar content in lettuce compared with those of lettuce grown under NL.”
Claim · model-written summary
Supplementary light increased lettuce biomass accumulation relative to natural light.
- Taxon
- lettuceLactuca sativae0
- Treatment
- supplementary lighte0
- Outcome
- biomass accumulatione0
- Direction
- highere0
- Comparator
- NLe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“supplementary light led to lower plant height, thicker leaves, higher biomass accumulation, higher vitamin C content, higher starch content, and higher total soluble sugar content in lettuce compared with those of lettuce grown under NL.”
Claim · model-written summary
Supplementary light increased lettuce vitamin C, starch, and total soluble sugar content relative to natural light.
- Taxon
- lettuceLactuca sativae0
- Treatment
- supplementary lighte0
- Outcome
- vitamin C content, higher starch content, and higher total soluble sugar contente0
- Direction
- highere0
- Comparator
- NLe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“supplementary light led to lower plant height, thicker leaves, higher biomass accumulation, higher vitamin C content, higher starch content, and higher total soluble sugar content in lettuce compared with those of lettuce grown under NL.”
Claim · model-written summary
WR139 reduced lettuce height by 40.0% relative to natural light.
- Taxon
- LettuceLactuca sativae0
- Treatment
- WR139e0
- Outcome
- plant heighte0
- Direction
- decreasee0
- Value
- 40.0%e0
- Comparator
- NLe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Lettuce grown under WR139 resulted in a 40.0% decrease in plant height, 66.8% increase in leaf thickness, and 34.1% increase in shoot fresh weight compared with those of lettuce grown under NL.”
Claim · model-written summary
WR139 increased lettuce leaf thickness by 66.8% relative to natural light.
- Taxon
- LettuceLactuca sativae0
- Treatment
- WR139e0
- Outcome
- leaf thicknesse0
- Direction
- increasee0
- Value
- 66.8%e0
- Comparator
- NLe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Lettuce grown under WR139 resulted in a 40.0% decrease in plant height, 66.8% increase in leaf thickness, and 34.1% increase in shoot fresh weight compared with those of lettuce grown under NL.”
Claim · model-written summary
WR139 increased lettuce shoot fresh weight by 34.1% relative to natural light.
- Taxon
- LettuceLactuca sativae0
- Treatment
- WR139e0
- Outcome
- shoot fresh weighte0
- Direction
- increasee0
- Value
- 34.1%e0
- Comparator
- NLe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Lettuce grown under WR139 resulted in a 40.0% decrease in plant height, 66.8% increase in leaf thickness, and 34.1% increase in shoot fresh weight compared with those of lettuce grown under NL.”
Claim · model-written summary
The three lowest far-red treatments did not differ significantly in listed morphology and biomass measures.
- Taxon
- lettuceLactuca sativae0
- Outcome
- leaf width, specific leaf area, shoot fresh weight, root fresh weight, shoot dry weight, root dry weighte0
- Direction
- No significant differencese0
- Comparator
- WR139, WR129+FR10, and WR109+FR30e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“No significant differences were observed in leaf width, specific leaf area, shoot fresh weight, root fresh weight, shoot dry weight, root dry weight, soil plant analysis development value, apparent quantum yield, soluble protein content, and light use efficiency of lettuce among the WR139, WR129+FR10, and WR109+FR30 treatments.”
Claim · model-written summary
The three lowest far-red treatments did not differ significantly in listed physiological measures.
- Taxon
- lettuceLactuca sativae0
- Outcome
- soil plant analysis development value, apparent quantum yield, soluble protein content, and light use efficiencye0
- Direction
- No significant differencese0
- Comparator
- WR139, WR129+FR10, and WR109+FR30e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“No significant differences were observed in leaf width, specific leaf area, shoot fresh weight, root fresh weight, shoot dry weight, root dry weight, soil plant analysis development value, apparent quantum yield, soluble protein content, and light use efficiency of lettuce among the WR139, WR129+FR10, and WR109+FR30 treatments.”
Claim · model-written summary
Greater far-red substitution was associated with declining lettuce biomass accumulation.
- Taxon
- lettuceLactuca sativae0
- Treatment
- substituted FR photon flux densitye0
- Outcome
- biomass accumulatione0
- Direction
- decreasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“decreased trends were observed in the biomass accumulation and maximum net photosynthetic rate of lettuce with the increased substituted FR photon flux density.”
Claim · model-written summary
Greater far-red substitution was associated with declining lettuce maximum net photosynthetic rate.
- Taxon
- lettuceLactuca sativae0
- Treatment
- substituted FR photon flux densitye0
- Outcome
- maximum net photosynthetic ratee0
- Direction
- decreasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“decreased trends were observed in the biomass accumulation and maximum net photosynthetic rate of lettuce with the increased substituted FR photon flux density.”
Claim · model-written summary
Lettuce maximum photochemical quantum yield showed the opposite, increasing trend.
- Taxon
- lettuceLactuca sativat0
- Outcome
- maximum photochemical quantum yielde0
- Qualifier
- opposite trende0
Not reportedTreatmentDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“However, an opposite trend was found in the maximum photochemical quantum yield.”
t0“Greenhouse Lettuce”
Claim · model-written summary
The authors advise considering photon flux density when applying far-red photons because excess substitution had negative effects.
- Taxon
- LettuceLactuca sativat0
- Outcome
- FR photons should be applied with the consideration of photon flux densitye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The FR photons should be applied with the consideration of photon flux density because the results also demonstrated negative effects of excess substituted FR photons for PPFD.”
t0“Greenhouse Lettuce”
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