Abstract
High planting density is essential to increasing maize grain yield. However, single plants suffer from insufficient light under high planting density. Ammonium (NH4+) assimilation consumes less energy converted from radiation than nitrate (NO3−). It is hypothesized that a mixed NO3−/NH4+ supply is more important to improving plant growth and population productivity under high vs. low planting density. Maize plants were grown under hydroponic conditions at two planting densities (low density: 208 plants m−2 and high density: 667 plants m−2) and three nitrogen forms (nitrate only, 75/25NO3−/NH4+ and ammonium only). A significant interaction effect was found between planting density and N form on plant biomass. Compared to nitrate only, 75/25NO3−/NH4+ increased per-plant biomass by 44% under low density, but by 81% under high density. Treatment with 75/25NO3−/NH4+ increased plant ATP, photosynthetic rate, and carbon amount per plant by 31, 7, and 44% under low density, respectively, but by 51, 23, and 95% under high density. Accordingly, carbon level per plant under 75/25NO3−/NH4+ was improved, which increased leaf area, specific leaf weight and total root length, especially for high planting density, increased by 57, 17 and 63%, respectively. Furthermore, under low density, 75/25NO3−/NH4+ increased nitrogen uptake rate, while under high density, 75/25NO3−/NH4+ increased nitrogen, phosphorus, copper and iron uptake rates. By increasing energy use efficiency, an optimum NO3−/NH4+ ratio can improve plant growth and nutrient uptake efficiency, especially under high planting density. In summary, an appropriate supply of NH4+ in addition to nitrate can greatly improve plant growth and promote population productivity of maize under high planting density, and therefore a mixed N form is recommended for high-yielding maize management in the field.
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Claims 15
Claim · model-written summary
Plant biomass showed a significant interaction between planting density and nitrogen form.
Zea maysNot reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A significant interaction effect was found between planting density and N form on plant biomass”
t0“maize seedlings”
Claim · model-written summary
Mixed nitrate/ammonium increased per-plant biomass by 44% at low density versus nitrate only.
- Treatment
- 75/25NO3−/NH4+e0
- Outcome
- per-plant biomasse0
- Direction
- increasede0
- Value
- 44%e0
- Qualifier
- low densitye0
- Comparator
- nitrate onlye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Compared to nitrate only, 75/25NO3−/NH4+ increased per-plant biomass by 44% under low density”
t0“maize seedlings”
Claim · model-written summary
Mixed nitrate/ammonium increased per-plant biomass by 81% at high density versus nitrate only.
- Treatment
- 75/25NO3−/NH4+e0
- Outcome
- per-plant biomasse0
- Direction
- increasede0
- Value
- 81%e0
- Qualifier
- high densitye0
- Comparator
- nitrate onlye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Compared to nitrate only, 75/25NO3−/NH4+ increased per-plant biomass by 44% under low density, but by 81% under high density”
t0“maize seedlings”
Claim · model-written summary
Mixed nitrogen increased plant ATP by 31% at low density.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Treatment with 75/25NO3−/NH4+ increased plant ATP, photosynthetic rate, and carbon amount per plant by 31, 7, and 44% under low density, respectively”
t0“maize seedlings”
Claim · model-written summary
Mixed nitrogen increased photosynthetic rate by 7% at low density.
- Treatment
- 75/25NO3−/NH4+e0
- Outcome
- photosynthetic ratee0
- Direction
- increasede0
- Value
- 7e0
- Qualifier
- low densitye0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Treatment with 75/25NO3−/NH4+ increased plant ATP, photosynthetic rate, and carbon amount per plant by 31, 7, and 44% under low density, respectively”
t0“maize seedlings”
Claim · model-written summary
Mixed nitrogen increased carbon per plant by 44% at low density.
- Treatment
- 75/25NO3−/NH4+e0
- Outcome
- carbon amount per plante0
- Direction
- increasede0
- Value
- 44%e0
- Qualifier
- low densitye0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Treatment with 75/25NO3−/NH4+ increased plant ATP, photosynthetic rate, and carbon amount per plant by 31, 7, and 44% under low density, respectively”
t0“maize seedlings”
Claim · model-written summary
Mixed nitrogen increased plant ATP by 51% at high density.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Treatment with 75/25NO3−/NH4+ increased plant ATP, photosynthetic rate, and carbon amount per plant by 31, 7, and 44% under low density, respectively, but by 51, 23, and 95% under high density”
t0“maize seedlings”
Claim · model-written summary
Mixed nitrogen increased photosynthetic rate by 23% at high density.
- Treatment
- 75/25NO3−/NH4+e0
- Outcome
- photosynthetic ratee0
- Direction
- increasede0
- Value
- 23e0
- Qualifier
- high densitye0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Treatment with 75/25NO3−/NH4+ increased plant ATP, photosynthetic rate, and carbon amount per plant by 31, 7, and 44% under low density, respectively, but by 51, 23, and 95% under high density”
t0“maize seedlings”
Claim · model-written summary
Mixed nitrogen increased carbon per plant by 95% at high density.
- Treatment
- 75/25NO3−/NH4+e0
- Outcome
- carbon amount per plante0
- Direction
- increasede0
- Value
- 95%e0
- Qualifier
- high densitye0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Treatment with 75/25NO3−/NH4+ increased plant ATP, photosynthetic rate, and carbon amount per plant by 31, 7, and 44% under low density, respectively, but by 51, 23, and 95% under high density”
t0“maize seedlings”
Claim · model-written summary
Mixed nitrogen increased leaf area by 57% especially at high density.
- Treatment
- 75/25NO3−/NH4+e0
- Outcome
- leaf areae0
- Direction
- increasede0
- Value
- 57e0
- Qualifier
- high planting densitye0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“75/25NO3−/NH4+ was improved, which increased leaf area, specific leaf weight and total root length, especially for high planting density, increased by 57, 17 and 63%, respectively”
t0“maize seedlings”
Claim · model-written summary
Mixed nitrogen increased specific leaf weight by 17% especially at high density.
- Treatment
- 75/25NO3−/NH4+e0
- Outcome
- specific leaf weighte0
- Direction
- increasede0
- Value
- 17e0
- Qualifier
- high planting densitye0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“75/25NO3−/NH4+ was improved, which increased leaf area, specific leaf weight and total root length, especially for high planting density, increased by 57, 17 and 63%, respectively”
t0“maize seedlings”
Claim · model-written summary
Mixed nitrogen increased total root length by 63% especially at high density.
- Treatment
- 75/25NO3−/NH4+e0
- Outcome
- total root lengthe0
- Direction
- increasede0
- Value
- 63%e0
- Qualifier
- high planting densitye0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“75/25NO3−/NH4+ was improved, which increased leaf area, specific leaf weight and total root length, especially for high planting density, increased by 57, 17 and 63%, respectively”
t0“maize seedlings”
Claim · model-written summary
Mixed nitrogen increased nitrogen uptake rate at low density.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“under low density, 75/25NO3−/NH4+ increased nitrogen uptake rate”
t0“maize seedlings”
Claim · model-written summary
Mixed nitrogen increased nitrogen, phosphorus, copper and iron uptake rates at high density.
- Treatment
- 75/25NO3−/NH4+e0
- Outcome
- nitrogen, phosphorus, copper and iron uptake ratese0
- Direction
- increasede0
- Qualifier
- high densitye0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“under high density, 75/25NO3−/NH4+ increased nitrogen, phosphorus, copper and iron uptake rates”
t0“maize seedlings”
Claim · model-written summary
The authors recommend mixed nitrogen for high-yielding maize field management.
- Outcome
- mixed N form is recommended for high-yielding maize management in the fielde0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a mixed N form is recommended for high-yielding maize management in the field”
The same questions in other papers
ammonium · physiology: photosynthesis · Zea mays (maize)Positive and negative results
1 in the opposite direction
- negative
ammonium · nutrient: content · Zea mays (maize)Positive and negative results
1 paper in the same direction as this paper · 2 in the opposite direction
- negative
- no effect
- positive
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.