Abstract
Abstract Modern compared with older maize ( Zea mays L.) hybrids tolerate more plant density stress, but more information is required on how modern hybrids interact with plant density. Field experiments were established in 1991 (warm‐dry) and 1992 (cool‐wet) to evaluate whole‐plant physiological, dry matter (DM), and grain yield responses of four commercial hybrids at low (4.5 plants m −2 ), medium (6.75), and high (9.0) plant densities. As plant density increased, leaf CO 2 exchange rates (CER) declined 10 to 20% under mild and 20 to 30% under warm dry conditions. Compared with the high plant density, the low plant density had a 40% lower leaf area index from midvegetative to early grain filling, which offset higher photosynthetic efficiency, resulting in lower crop growth rates during vegetative development and 25% less DM accumulation at silking. When averaged across hybrids, the low plant density averaged 15% lower DM and grain yields than the high plant density. Hybrid ✕ plant density interactions were observed for DM and grain yields. The more prolific hybrid showed mostly linear DM and grain yield responses to plant density, whereas a single‐eared hybrid showed quadratic responses in both years. Another single‐eared hybrid, which did not respond to density, had low leaf CER at all densities, a reduction in kernels per plant at the medium density, and increased barrenness at the high plant density in 1991. Apparently, modern hybrids interact with plant density, regardless of growing conditions, and some modern hybrids do not tolerate density stress in dry years.
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Claims 16
Claim · model-written summary
As plant density increased, leaf CO 2 exchange rates declined 10 to 20% under mild conditions
- Treatment
- plant densitye2
- Outcome
- leaf CO 2 exchange rates (CER)e2
- Direction
- declinede2
- Value
- 10 to 20%e2
- Qualifier
- under milde2
- Setting
- Field experimentse1
Zea maysNot reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Modern compared with older maize ( Zea mays L.) hybrids tolerate more plant density stress, but more information is required on how modern hybrids interact with plant density”
e1“Field experiments were established in 1991”
e2“As plant density increased, leaf CO 2 exchange rates (CER) declined 10 to 20% under mild and 20 to 30% under warm dry conditions”
Claim · model-written summary
As plant density increased, leaf CO 2 exchange rates declined 20 to 30% under warm dry conditions
- Treatment
- plant densitye2
- Outcome
- leaf CO 2 exchange rates (CER)e2
- Direction
- declinede2
- Value
- 20 to 30%e2
- Qualifier
- under warm dry conditionse2
- Setting
- Field experimentse1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Modern compared with older maize ( Zea mays L.) hybrids tolerate more plant density stress, but more information is required on how modern hybrids interact with plant density”
e1“Field experiments were established in 1991”
e2“As plant density increased, leaf CO 2 exchange rates (CER) declined 10 to 20% under mild and 20 to 30% under warm dry conditions”
Claim · model-written summary
Low plant density had a 40% lower leaf area index than high plant density from midvegetative to early grain filling
- Treatment
- low plant densitye3
- Outcome
- leaf area indexe3
- Direction
- lowere3
- Value
- 40%e3
- Qualifier
- from midvegetative to early grain fillinge3
- Comparator
- high plant densitye3
- Setting
- Field experimentse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Modern compared with older maize ( Zea mays L.) hybrids tolerate more plant density stress, but more information is required on how modern hybrids interact with plant density”
e1“Field experiments were established in 1991”
e3“Compared with the high plant density, the low plant density had a 40% lower leaf area index from midvegetative to early grain filling, which offset higher photosynthetic efficiency, resulting in lower crop growth rates during vegetative development and 25% less DM accumulation at silking”
Claim · model-written summary
Low plant density had higher photosynthetic efficiency than high plant density
- Treatment
- low plant densitye3
- Outcome
- photosynthetic efficiencye3
- Direction
- highere3
- Comparator
- high plant densitye3
- Setting
- Field experimentse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Modern compared with older maize ( Zea mays L.) hybrids tolerate more plant density stress, but more information is required on how modern hybrids interact with plant density”
e1“Field experiments were established in 1991”
e3“Compared with the high plant density, the low plant density had a 40% lower leaf area index from midvegetative to early grain filling, which offset higher photosynthetic efficiency, resulting in lower crop growth rates during vegetative development and 25% less DM accumulation at silking”
Claim · model-written summary
Low plant density had lower crop growth rates during vegetative development than high plant density
- Treatment
- low plant densitye3
- Outcome
- crop growth rates during vegetative developmente3
- Direction
- lowere3
- Comparator
- high plant densitye3
- Setting
- Field experimentse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Modern compared with older maize ( Zea mays L.) hybrids tolerate more plant density stress, but more information is required on how modern hybrids interact with plant density”
e1“Field experiments were established in 1991”
e3“Compared with the high plant density, the low plant density had a 40% lower leaf area index from midvegetative to early grain filling, which offset higher photosynthetic efficiency, resulting in lower crop growth rates during vegetative development and 25% less DM accumulation at silking”
Claim · model-written summary
Low plant density had 25% less dry matter accumulation at silking than high plant density
- Treatment
- low plant densitye3
- Outcome
- DM accumulation at silkinge3
- Direction
- lesse3
- Value
- 25%e3
- Comparator
- high plant densitye3
- Setting
- Field experimentse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Modern compared with older maize ( Zea mays L.) hybrids tolerate more plant density stress, but more information is required on how modern hybrids interact with plant density”
e1“Field experiments were established in 1991”
e3“Compared with the high plant density, the low plant density had a 40% lower leaf area index from midvegetative to early grain filling, which offset higher photosynthetic efficiency, resulting in lower crop growth rates during vegetative development and 25% less DM accumulation at silking”
Claim · model-written summary
Averaged across hybrids, low plant density had 15% lower dry matter and grain yields than high plant density
- Treatment
- low plant densitye4
- Outcome
- DM and grain yieldse4
- Direction
- lowere4
- Value
- 15%e4
- Qualifier
- When averaged across hybridse4
- Comparator
- high plant densitye4
- Setting
- Field experimentse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Modern compared with older maize ( Zea mays L.) hybrids tolerate more plant density stress, but more information is required on how modern hybrids interact with plant density”
e1“Field experiments were established in 1991”
e4“When averaged across hybrids, the low plant density averaged 15% lower DM and grain yields than the high plant density”
Claim · model-written summary
Plant density interacted with hybrid for dry matter and grain yields
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Modern compared with older maize ( Zea mays L.) hybrids tolerate more plant density stress, but more information is required on how modern hybrids interact with plant density”
e5“plant density interactions were observed for DM and grain yields”
Claim · model-written summary
The more prolific hybrid showed mostly linear dry matter and grain yield responses to plant density
- Material
- more prolific hybride6
- Treatment
- plant densitye6
- Outcome
- DM and grain yield responsese6
- Qualifier
- mostly lineare6
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Modern compared with older maize ( Zea mays L.) hybrids tolerate more plant density stress, but more information is required on how modern hybrids interact with plant density”
e6“The more prolific hybrid showed mostly linear DM and grain yield responses to plant density, whereas a single‐eared hybrid showed quadratic responses in both years”
Claim · model-written summary
A single-eared hybrid showed quadratic dry matter and grain yield responses to plant density in both years
- Material
- single‐eared hybride6
- Treatment
- plant densitye6
- Outcome
- DM and grain yield responsese6
- Qualifier
- quadratice6
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Modern compared with older maize ( Zea mays L.) hybrids tolerate more plant density stress, but more information is required on how modern hybrids interact with plant density”
e6“The more prolific hybrid showed mostly linear DM and grain yield responses to plant density, whereas a single‐eared hybrid showed quadratic responses in both years”
Claim · model-written summary
Another single-eared hybrid did not respond to plant density
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Modern compared with older maize ( Zea mays L.) hybrids tolerate more plant density stress, but more information is required on how modern hybrids interact with plant density”
e7“Another single‐eared hybrid, which did not respond to density, had low leaf CER at all densities, a reduction in kernels per plant at the medium density, and increased barrenness at the high plant density in 1991”
Claim · model-written summary
Another single-eared hybrid had low leaf CER at all densities
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Modern compared with older maize ( Zea mays L.) hybrids tolerate more plant density stress, but more information is required on how modern hybrids interact with plant density”
e7“Another single‐eared hybrid, which did not respond to density, had low leaf CER at all densities, a reduction in kernels per plant at the medium density, and increased barrenness at the high plant density in 1991”
Claim · model-written summary
Medium plant density reduced kernels per plant in another single-eared hybrid
- Material
- Another single‐eared hybride7
- Treatment
- medium densitye7
- Outcome
- kernels per plante7
- Direction
- reductione7
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Modern compared with older maize ( Zea mays L.) hybrids tolerate more plant density stress, but more information is required on how modern hybrids interact with plant density”
e7“Another single‐eared hybrid, which did not respond to density, had low leaf CER at all densities, a reduction in kernels per plant at the medium density, and increased barrenness at the high plant density in 1991”
Claim · model-written summary
High plant density increased barrenness in another single-eared hybrid in 1991
- Material
- Another single‐eared hybride7
- Treatment
- high plant densitye7
- Outcome
- barrennesse7
- Direction
- increasede7
- Setting
- 1991e7
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Modern compared with older maize ( Zea mays L.) hybrids tolerate more plant density stress, but more information is required on how modern hybrids interact with plant density”
e7“Another single‐eared hybrid, which did not respond to density, had low leaf CER at all densities, a reduction in kernels per plant at the medium density, and increased barrenness at the high plant density in 1991”
Claim · model-written summary
Modern hybrids interact with plant density regardless of growing conditions
- Material
- modern hybridse7
- Treatment
- plant densitye7
- Outcome
- interact with plant densitye7
- Qualifier
- regardless of growing conditionse7
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Modern compared with older maize ( Zea mays L.) hybrids tolerate more plant density stress, but more information is required on how modern hybrids interact with plant density”
e7“Apparently, modern hybrids interact with plant density, regardless of growing conditions, and some modern hybrids do not tolerate density stress in dry years”
Claim · model-written summary
Some modern hybrids do not tolerate plant density stress in dry years
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Modern compared with older maize ( Zea mays L.) hybrids tolerate more plant density stress, but more information is required on how modern hybrids interact with plant density”
e7“Apparently, modern hybrids interact with plant density, regardless of growing conditions, and some modern hybrids do not tolerate density stress in dry years”
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