Abstract
Competition mechanisms among adjacent plants are not well understood. This study compared corn growth and yield responses to water, N, and shade at 74,500 plants ha −1 (1×) with responses to water and N when planted at 149,000 plant ha −1 . Plant biomass, leaf area, chlorophyll content, reflectance, and enzyme expression (transcriptome analysis) were measured at V‐12. Grain and stover yields were measured with grain analyzed for 13 C isotopic discrimination (Δ) and N concentration. At V‐12, 60% shade plants had increased chlorophyll and reduced leaf area and height compared to full sun plants. In the 2× treatment, plants had 11% less chlorophyll than 1× plants with leaf area and height similar to 60% shade plants. At harvest, plants in the 2× treatment were smaller, had increased water and N use efficiency, and an 11% per hectare yield increase compared with the 1× unstressed treatment. Per‐plant yields from 60% shade and 2× treatments were 50% less than 1× unstressed treatment. Yield reduction in shaded plants was attributed to light stress. Lower yield in the 2× treatment was attributed to a population‐density induced 20% decrease in the red/near‐infrared (NIR) ratio, which resulted in downregulation of C 4 carbon metabolism enzymes (phosphoenolpyruvate carboxykinase, phosphoenolpyruvate carboxylase, and pyruvate orthophosphate dikinase). Although the net impact of high plant density and shade stress on per‐plant yield were similar, the stress compensation mechanisms differed.
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Claims 13
Claim · model-written summary
Sixty percent shade increased corn chlorophyll relative to full sun.
Not reportedTaxon
Verbatim
e0“At V‐12, 60% shade plants had increased chlorophyll and reduced leaf area and height compared to full sun plants.”
Claim · model-written summary
Sixty percent shade reduced corn leaf area and height relative to full sun.
Not reportedTaxon
Verbatim
e0“At V‐12, 60% shade plants had increased chlorophyll and reduced leaf area and height compared to full sun plants.”
Claim · model-written summary
Double density plants had 11% less chlorophyll than single density plants.
Not reportedTaxon
Verbatim
e0“In the 2× treatment, plants had 11% less chlorophyll than 1× plants with leaf area and height similar to 60% shade plants.”
Claim · model-written summary
Double density plants had leaf area and height similar to shaded plants.
Not reportedTaxon
Verbatim
e0“In the 2× treatment, plants had 11% less chlorophyll than 1× plants with leaf area and height similar to 60% shade plants.”
Claim · model-written summary
Double density plants were smaller at harvest.
Not reportedTaxon
Verbatim
e0“At harvest, plants in the 2× treatment were smaller, had increased water and N use efficiency, and an 11% per hectare yield increase compared with the 1× unstressed treatment.”
Claim · model-written summary
Double density increased water and nitrogen use efficiency.
- Treatment
- 2× treatmente0
- Outcome
- water and N use efficiencye0
- Direction
- increasede0
- Comparator
- 1× unstressed treatmente0
Not reportedTaxon
Verbatim
e0“At harvest, plants in the 2× treatment were smaller, had increased water and N use efficiency, and an 11% per hectare yield increase compared with the 1× unstressed treatment.”
Claim · model-written summary
Double density increased yield per hectare by 11%.
- Treatment
- 2× treatmente0
- Outcome
- per hectare yielde0
- Direction
- increasee0
- Value
- 11%e0
- Comparator
- 1× unstressed treatmente0
Not reportedTaxon
Verbatim
e0“At harvest, plants in the 2× treatment were smaller, had increased water and N use efficiency, and an 11% per hectare yield increase compared with the 1× unstressed treatment.”
Claim · model-written summary
Sixty percent shade reduced yield per plant by 50%.
- Treatment
- 60% shadee0
- Outcome
- Per‐plant yieldse0
- Direction
- lesse0
- Value
- 50%e0
- Comparator
- 1× unstressed treatmente0
Not reportedTaxon
Verbatim
e0“Per‐plant yields from 60% shade and 2× treatments were 50% less than 1× unstressed treatment.”
Claim · model-written summary
Double density reduced yield per plant by 50%.
- Treatment
- 2× treatmentse0
- Outcome
- Per‐plant yieldse0
- Direction
- lesse0
- Value
- 50%e0
- Comparator
- 1× unstressed treatmente0
Not reportedTaxon
Verbatim
e0“Per‐plant yields from 60% shade and 2× treatments were 50% less than 1× unstressed treatment.”
Claim · model-written summary
The authors attributed shaded plant yield reduction to light stress.
Not reportedTaxon
Verbatim
e0“Yield reduction in shaded plants was attributed to light stress.”
Claim · model-written summary
High density was associated with a 20% decrease in red to near infrared ratio.
Not reportedTaxonComparator
Verbatim
e0“the 2× treatment was attributed to a population‐density induced 20% decrease in the red/near‐infrared (NIR) ratio”
Claim · model-written summary
The authors linked the density induced ratio decrease to downregulation of three carbon metabolism enzymes.
Not reportedTaxon
Verbatim
e0“which resulted in downregulation of C 4 carbon metabolism enzymes (phosphoenolpyruvate carboxykinase, phosphoenolpyruvate carboxylase, and pyruvate orthophosphate dikinase).”
Claim · model-written summary
High density and shade had similar per plant yield impact but different compensation mechanisms.
Not reportedTaxon
Verbatim
e0“Although the net impact of high plant density and shade stress on per‐plant yield were similar, the stress compensation mechanisms differed.”