Abstract
Conflicting reports have led to a renewed interest in the effects of narrow row spacing and high plant population densities on maize (Zea mays L.) grain yield. Field experiments were conducted to evaluate maize response to row spacing and N fertility over a 4-yr period (1997–2000). A randomized complete block design, arranged in a split plot was used with four replications each year with modifications of treatments over years. Row spacings of 0.51 m, 0.76 m and 0.76 m paired row alone or in combination with hybrid were tested in the subplot whereas combination of fertilizer N by population density (1997 and 1998) or N alone was assigned to the main plot. In 1997 and 1998, combinations of N by density consisted of 0 , 60, 120, 180 and 240 kg N ha -1 at 89 000 plants ha -1 , and 60 and 180 kg N ha -1 at 69 000 plants ha -1 using a single hybrid, Pioneer 3893. In 1999 and 2000, N fertility levels of 0, 80 and 180 kg N ha -1 >were the main plots and six combinations of hybrids (Pioneer 3893 and Pioneer 38P06 Bt) by row spacing were grown in the subplots at 69 000 plants ha -1 . Row spacing and fertility levels showed no significant interaction for any parameter at any developmental stage. In both 1997 and 1998, row spacing had no significant effect on yield (yield differed by 5% among row spacing treatments) or harvest index (varied from 0.45 to 0.53). For Pioneer 38P06 Bt in 1999, grain yield of the 0.51 m row spacing with the 80 kg N ha -1 fertilizer rate was 14.6% higher than the conventional 0.76 m row spacing. In 2000, the substantially lower (11%) yield of the 0.76 m paired row spacing than the other row spacing treatments was more likely the result of an exceptionally cool and wet season. In 1997 and 1998, plant density showed no effect on shoot or root DM. The lower density (69 000 plants ha -1 ) did, however, show a higher root to shoot ratio than the higher density. Shoot DM, root DM and root to shoot ratio did not differ between the 60 and 180 kg N ha -1 fertility treatments. While higher N levels increased above- and below-ground crop N contents, row spacing showed no consistent effects on maize plants at the early stages. Under the conditions of this study, narrow rows did not result in higher yield or N use efficiency even plant density and N fertility varied. Key words: Maize (Zea mays L.), nitrogen use, population density, root/shoot ratio, row spacing
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Claims 13
Claim · model-written summary
Row spacing and fertility had no significant interaction for measured parameters.
- Treatment
- Row spacing and fertility levelse0
- Outcome
- interaction for any parametere0
- Direction
- no significant interactione0
Zea maysOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Row spacing and fertility levels showed no significant interaction for any parameter at any developmental stage.”
t0“maize”
Claim · model-written summary
Row spacing had no significant yield effect in 1997–1998.
- Treatment
- row spacinge0
- Outcome
- yielde0
- Direction
- no significant effecte0
- Value
- 5%e0
- Comparator
- row spacing treatmentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In both 1997 and 1998, row spacing had no significant effect on yield (yield differed by 5% among row spacing treatments) or harvest index (varied from 0.45 to 0.53).”
t0“maize”
Claim · model-written summary
Row spacing had no significant harvest index effect in 1997–1998.
- Treatment
- row spacinge0
- Outcome
- harvest indexe0
- Direction
- no significant effecte0
- Value
- 0.45 to 0.53e0
- Comparator
- row spacing treatmentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In both 1997 and 1998, row spacing had no significant effect on yield (yield differed by 5% among row spacing treatments) or harvest index (varied from 0.45 to 0.53).”
t0“maize”
Claim · model-written summary
Pioneer 38P06 Bt in 0.51 m rows with 80 kg N yielded 14.6% more than 0.76 m rows in 1999.
- Material
- Pioneer 38P06 Bte0
- Treatment
- 0.51 m row spacing with the 80 kg N ha -1 fertilizer ratee0
- Outcome
- grain yielde0
- Direction
- highere0
- Value
- 14.6%e0
- Comparator
- conventional 0.76 m row spacinge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“For Pioneer 38P06 Bt in 1999, grain yield of the 0.51 m row spacing with the 80 kg N ha -1 fertilizer rate was 14.6% higher than the conventional 0.76 m row spacing.”
t0“maize”
Claim · model-written summary
The paired 0.76 m rows yielded 11% less than other row spacings in 2000.
- Treatment
- 0.76 m paired row spacinge0
- Outcome
- yielde0
- Direction
- lowere0
- Value
- 11%e0
- Qualifier
- exceptionally cool and wet seasone0
- Comparator
- other row spacing treatmentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In 2000, the substantially lower (11%) yield of the 0.76 m paired row spacing than the other row spacing treatments was more likely the result of an exceptionally cool and wet season.”
t0“maize”
Claim · model-written summary
Plant density had no effect on shoot or root dry matter in 1997–1998.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In 1997 and 1998, plant density showed no effect on shoot or root DM.”
t0“maize”
Claim · model-written summary
Lower plant density produced a higher root-to-shoot ratio.
- Treatment
- lower density (69 000 plants ha -1 )e0
- Outcome
- root to shoot ratioe0
- Direction
- highere0
- Comparator
- higher densitye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The lower density (69 000 plants ha -1 ) did, however, show a higher root to shoot ratio than the higher density.”
t0“maize”
Claim · model-written summary
Shoot and root dry matter did not differ between 60 and 180 kg N treatments.
- Treatment
- 60 and 180 kg N ha -1 fertility treatmentse0
- Outcome
- Shoot DM, root DMe0
- Direction
- did not differe0
- Comparator
- 60 and 180 kg N ha -1 fertility treatmentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Shoot DM, root DM and root to shoot ratio did not differ between the 60 and 180 kg N ha -1 fertility treatments.”
t0“maize”
Claim · model-written summary
Root-to-shoot ratio did not differ between 60 and 180 kg N treatments.
- Treatment
- 60 and 180 kg N ha -1 fertility treatmentse0
- Outcome
- root to shoot ratioe0
- Direction
- did not differe0
- Comparator
- 60 and 180 kg N ha -1 fertility treatmentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Shoot DM, root DM and root to shoot ratio did not differ between the 60 and 180 kg N ha -1 fertility treatments.”
t0“maize”
Claim · model-written summary
Higher nitrogen increased above- and below-ground crop nitrogen content.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“While higher N levels increased above- and below-ground crop N contents, row spacing showed no consistent effects on maize plants at the early stages.”
Claim · model-written summary
Row spacing showed no consistent early-stage effect on maize plants.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“While higher N levels increased above- and below-ground crop N contents, row spacing showed no consistent effects on maize plants at the early stages.”
Claim · model-written summary
Narrow rows did not increase yield under the study conditions.
- Treatment
- narrow rowse0
- Outcome
- yielde0
- Direction
- did not result in highere0
- Qualifier
- plant density and N fertility variede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Under the conditions of this study, narrow rows did not result in higher yield or N use efficiency even plant density and N fertility varied.”
t0“maize”
Claim · model-written summary
Narrow rows did not improve nitrogen use efficiency.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Under the conditions of this study, narrow rows did not result in higher yield or N use efficiency even plant density and N fertility varied.”
t0“maize”
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