Abstract
Maize ( Zea mays L.) plant‐to‐plant variability at different plant densities and N fertilizer rates has been studied previously, but little attention has been devoted to consequences of different N placement and tillage management on plant variability in kernel number (KN) and grain yield. This study investigated effects of pre‐plant N placement relative to intended maize rows on the origin and magnitude of plant‐to‐plant variability in per‐plant grain weights (GW). Field studies compared two “shallow” anhydrous ammonia (NH 3 ) placement directions (diagonal to future row vs. parallel but 15‐cm offset from the row) in both no‐till and conventional tillage systems at two N rates (145 and 202 kg N ha −1 ). Maize was planted with starter fertilizer (20 kg N ha −1 ) within 6 d following NH 3 application. Aboveground growth and development was monitored on bar‐coded plants from seedling emergence to maturity. Plant‐to‐plant uniformity in GW and KN was not improved by parallel NH 3 placement, conventional tillage, or a higher N rate; however, all three factors resulted in a slight shift towards higher mean GW and KN. Within‐row plant spacing and relative seedling emergence time had little influence on relative GW. Within‐row differences in silk emergence timing and estimated stem volumes were the most highly correlated parameters to per‐plant GW. Regression models confirmed that either of these mid‐silking factors explained >50% of such GW variations within most treatment combinations. Even in management systems with conventional tillage and precision N fertilizer placements, precision seed placement alone will not guarantee low variability in per‐plant GW.
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Claims 12
Claim · model-written summary
Parallel ammonia placement did not improve GW and KN uniformity.
- Treatment
- parallel NH 3 placemente0
- Outcome
- Plant‐to‐plant uniformity in GW and KNe0
- Direction
- not improvede0
Zea maysNot reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Plant‐to‐plant uniformity in GW and KN was not improved by parallel NH 3 placement, conventional tillage, or a higher N rate; however, all three factors resulted in a slight shift towards higher mean GW and KN.”
t0“Maize”
Claim · model-written summary
Conventional tillage did not improve GW and KN uniformity.
- Treatment
- conventional tillagee0
- Outcome
- Plant‐to‐plant uniformity in GW and KNe0
- Direction
- not improvede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Plant‐to‐plant uniformity in GW and KN was not improved by parallel NH 3 placement, conventional tillage, or a higher N rate; however, all three factors resulted in a slight shift towards higher mean GW and KN.”
t0“Maize”
Claim · model-written summary
Higher nitrogen did not improve GW and KN uniformity.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Plant‐to‐plant uniformity in GW and KN was not improved by parallel NH 3 placement, conventional tillage, or a higher N rate; however, all three factors resulted in a slight shift towards higher mean GW and KN.”
t0“Maize”
Claim · model-written summary
Parallel ammonia placement slightly raised mean GW and KN.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Plant‐to‐plant uniformity in GW and KN was not improved by parallel NH 3 placement, conventional tillage, or a higher N rate; however, all three factors resulted in a slight shift towards higher mean GW and KN.”
t0“Maize”
Claim · model-written summary
Conventional tillage slightly raised mean GW and KN.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Plant‐to‐plant uniformity in GW and KN was not improved by parallel NH 3 placement, conventional tillage, or a higher N rate; however, all three factors resulted in a slight shift towards higher mean GW and KN.”
t0“Maize”
Claim · model-written summary
Higher nitrogen slightly raised mean GW and KN.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Plant‐to‐plant uniformity in GW and KN was not improved by parallel NH 3 placement, conventional tillage, or a higher N rate; however, all three factors resulted in a slight shift towards higher mean GW and KN.”
t0“Maize”
Claim · model-written summary
Within-row spacing had little influence on relative GW.
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Within‐row plant spacing and relative seedling emergence time had little influence on relative GW”
t0“Maize”
Claim · model-written summary
Seedling emergence time had little influence on relative GW.
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Within‐row plant spacing and relative seedling emergence time had little influence on relative GW”
t0“Maize”
Claim · model-written summary
Silk emergence timing was highly correlated with per-plant GW.
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Within‐row differences in silk emergence timing and estimated stem volumes were the most highly correlated parameters to per‐plant GW”
t0“Maize”
Claim · model-written summary
Estimated stem volume was highly correlated with per-plant GW.
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Within‐row differences in silk emergence timing and estimated stem volumes were the most highly correlated parameters to per‐plant GW”
t0“Maize”
Claim · model-written summary
Either mid-silking factor explained over half of GW variation.
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“either of these mid‐silking factors explained >50% of such GW variations within most treatment combinations”
t0“Maize”
Claim · model-written summary
Precision seed placement alone will not guarantee low GW variability.
- Outcome
- precision seed placement alone will not guarantee low variability in per‐plant GWe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“precision seed placement alone will not guarantee low variability in per‐plant GW”
t0“Maize”
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