Abstract
Appropriate plant density could optimize light distribution within canopy and improve light use efficiency (LUE). However, most cotton studies have merely focused on whole canopy, and lacking in-depth exploration of the underlying mechanisms by which plant density regulates LUE as well as the gene expression. A two-year field experiment was conducted to assess the effect of plant density (low density, LD; moderate density, MD; high density, HD) on canopy light distribution, photosynthesis and its relevant gene expression, LUE, and cotton yield in upper, middle and lower canopy. The results showed that cotton responded to an increase in plant density by enhancing leaf area index at upper canopy, which subsequently led to higher fractional interception of photosynthetically active radiation (FIPAR) and a decrease of FIPAR at middle and lower canopy both in 2024 and 2025. Furthermore, HD caused a decline in photosynthetic rate ( A N ), chlorophyll content, leaf area, and specific leaf weight, which were significantly lower than those under MD. More importantly, LD and MD consistently achieved the maximum biomass and yield in 2024 and 2025, and biomass-based light use efficiency (LUE B ) in each canopy under MD was higher than that under LD and HD. Meanwhile, random forest model showed that FIPAR played a dominant role in regulating the variation in LUE B , with A N coming second, and these variations were supported by regulating photosynthetic genes expression at different canopy layers under different densities. The partial least squares model indicated that yield is mainly influenced by LUE B and leaf photosynthesis. Overall, MD optimized canopy light distribution, fully exploited the photosynthetic productivity at middle and upper canopy, thereby enhancing LUE and yield potential. • Divide canopy into three layers by height to observe their responses to density. • Combine physiological measurements with gene expression level. • Random forest model and partial least squares model were used. • Canopy light distribution is key to regulating light use efficiency.
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Claims 14
Claim · model-written summary
Increasing cotton density enhanced upper-canopy leaf area index.
- Taxon
- cotton
Gossypium hirsutume0 - Organ / stage
- upper canopye0
- Treatment
- increase in plant densitye0
- Outcome
- leaf area indexe0
- Direction
- enhancinge0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“cotton responded to an increase in plant density by enhancing leaf area index at upper canopy”
Claim · model-written summary
Increased upper-canopy leaf area index led to higher upper-canopy FIPAR.
- Outcome
- fractional interception of photosynthetically active radiation (FIPAR)e0
- Direction
- highere0
- Qualifier
- enhancing leaf area index at upper canopye0
Not reportedTaxon
Verbatim
e0“enhancing leaf area index at upper canopy, which subsequently led to higher fractional interception of photosynthetically active radiation (FIPAR)”
Claim · model-written summary
Increased density decreased FIPAR in middle and lower canopies in both years.
Not reportedTaxonTreatmentComparator
Verbatim
e0“a decrease of FIPAR at middle and lower canopy both in 2024 and 2025”
Claim · model-written summary
High density lowered photosynthetic rate, chlorophyll content and leaf area relative to moderate density.
- Treatment
- HDe0
- Outcome
- photosynthetic rate ( A N ), chlorophyll content, leaf areae0
- Direction
- declinee0
- Comparator
- MDe0
Not reportedTaxon
Verbatim
e0“HD caused a decline in photosynthetic rate ( A N ), chlorophyll content, leaf area, and specific leaf weight, which were significantly lower than those under MD”
Claim · model-written summary
High density lowered specific leaf weight relative to moderate density.
Not reportedTaxon
Verbatim
e0“HD caused a decline in photosynthetic rate ( A N ), chlorophyll content, leaf area, and specific leaf weight, which were significantly lower than those under MD”
Claim · model-written summary
Low and moderate density achieved maximum biomass in both years.
Not reportedTaxonComparator
Verbatim
e0“LD and MD consistently achieved the maximum biomass and yield in 2024 and 2025”
Claim · model-written summary
Low and moderate density achieved maximum yield in both years.
Not reportedTaxonComparator
Verbatim
e0“LD and MD consistently achieved the maximum biomass and yield in 2024 and 2025”
Claim · model-written summary
Moderate density had higher biomass-based light use efficiency in each canopy than low and high density.
- Treatment
- MDe0
- Outcome
- biomass-based light use efficiency (LUE B )e0
- Direction
- highere0
- Comparator
- LD and HDe0
Not reportedTaxon
Verbatim
e0“biomass-based light use efficiency (LUE B ) in each canopy under MD was higher than that under LD and HD”
Claim · model-written summary
FIPAR was the dominant predictor of variation in biomass-based light use efficiency.
Not reportedTaxonMaterialDirection
Verbatim
e0“random forest model showed that FIPAR played a dominant role in regulating the variation in LUE B”
Claim · model-written summary
Photosynthetic rate ranked second in predicting biomass-based light use efficiency variation.
Not reportedTaxonMaterialDirection
Verbatim
e0“FIPAR played a dominant role in regulating the variation in LUE B , with A N coming second”
Claim · model-written summary
Photosynthetic gene expression varied across canopy layers and planting densities in support of the light-use-efficiency pattern.
- Organ / stage
- different canopy layerse0
- Treatment
- different densitiese0
- Outcome
- photosynthetic genes expressione0
Not reportedTaxon
Verbatim
e0“these variations were supported by regulating photosynthetic genes expression at different canopy layers under different densities”
Claim · model-written summary
The partial least squares model identified biomass-based light use efficiency and leaf photosynthesis as principal influences on yield.
Not reportedTaxonMaterialDirection
Verbatim
e0“The partial least squares model indicated that yield is mainly influenced by LUE B and leaf photosynthesis”
Claim · model-written summary
Moderate density optimized canopy light distribution and photosynthetic productivity in middle and upper canopies.
- Treatment
- MDe0
- Outcome
- canopy light distribution, fully exploited the photosynthetic productivitye0
- Direction
- optimizede0
Not reportedTaxonComparator
Verbatim
e0“MD optimized canopy light distribution, fully exploited the photosynthetic productivity at middle and upper canopy”
Claim · model-written summary
Moderate density enhanced light use efficiency and yield potential.
Not reportedTaxonTreatmentComparator
Verbatim
e0“thereby enhancing LUE and yield potential”
The same questions in other papers
density · growth · Gossypium hirsutum (cotton)Positive and negative results
38 papers in the same direction as this paper · 7 in the opposite direction
- positive
- no effect
- no effect
42 papers more in this group
See all 46 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.