Abstract
ABSTRACT The biological nitrogen fixation (BNF) process in grasses is caused by diazotrophic bacteria, particularly Azospirillum brasilense. However, studies are lacking on BNF efficiency to define how much mineral nitrogen (N) can be applied to achieve more sustainable high yields. Furthermore, there should be an analysis of whether urea with the urease enzyme inhibitor NBPT is less harmful, benefiting BNF in grasses. The objective of this study was to evaluate the effect of N sources and N rates associated with inoculation with Azospirillum brasilense regarding foliar diagnosis and leaf chlorophyll index (LCI), agronomic efficiency (AE), and corn grain yield in the Cerrado (Brazilian tropical savanna) region. The experiment was conducted in a no-tillage system in a Latossolo Vermelho Distroférrico (Oxisol). A randomized block experimental design was used with four replications in a 2 × 5 × 2 factorial arrangement as follows: two N sources - urea and Super N, urea with urease enzyme inhibitor NBPT [N - (n-butyl thiophosphoric triamide)]; five N rates (0, 50, 100, 150, and 200 kg ha-1) applied in topdressing; and two seed inoculation treatments, one with and one without A. brasilense. N rate positively influenced the LCI and concentrations of N, S, and Mn in leaves, and may increase the concentrations of P, Cu, and Fe; however, higher N rates can reduce AE. The N sources had similar effects, and therefore urea is recommended for N fertilization. Inoculation with A. brasilense decreased leaf concentration of Fe and increased LCI, leaf concentration of P, AE, and corn grain yield; the use of this diazotrophic bacterium is therefore viable even when high rates of N are applied.
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Claims 10
Claim · model-written summary
Higher N rates increased leaf chlorophyll index and N, S, and Mn concentrations.
- Taxon
- Corn
Zea mays subsp. mayst0 - Treatment
- N ratee0
- Outcome
- LCI and concentrations of N, S, and Mn in leavese0
- Direction
- positively influencede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“N rate positively influenced the LCI and concentrations of N, S, and Mn in leaves”
t0“Corn”
Claim · model-written summary
Higher N rates may increase leaf P, Cu, and Fe concentrations.
- Taxon
- CornZea mays subsp. mayst0
- Treatment
- N ratee0
- Outcome
- concentrations of P, Cu, and Fee0
- Direction
- increasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“N rate positively influenced the LCI and concentrations of N, S, and Mn in leaves, and may increase the concentrations of P, Cu, and Fe”
t0“Corn”
Claim · model-written summary
Higher N rates can reduce agronomic efficiency.
- Taxon
- CornZea mays subsp. mayst0
- Treatment
- higher N ratese0
- Outcome
- AEe0
- Direction
- reducee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“higher N rates can reduce AE”
t0“Corn”
Claim · model-written summary
The two N sources had similar effects.
- Taxon
- CornZea mays subsp. mayst0
- Treatment
- N sourcese0
- Outcome
- similar effectse0
- Direction
- similare0
- Comparator
- urea and Super Ne1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The N sources had similar effects”
e1“urea and Super N”
t0“Corn”
Claim · model-written summary
The authors recommended urea for nitrogen fertilization.
- Taxon
- CornZea mays subsp. mayst0
- Outcome
- urea is recommended for N fertilizatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“urea is recommended for N fertilization”
t0“Corn”
Claim · model-written summary
Azospirillum inoculation decreased leaf Fe concentration.
- Taxon
- CornZea mays subsp. mayst0
- Treatment
- Inoculation with A. brasilensee0
- Interactor
- A. brasilense
Azospirillum brasilensee0symbiont - Outcome
- leaf concentration of Fee0
- Direction
- decreasede0
- Comparator
- without A. brasilensee2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Inoculation with A. brasilense decreased leaf concentration of Fe”
t0“Corn”
e2“one with and one without A. brasilense”
Claim · model-written summary
Azospirillum inoculation increased LCI and leaf P concentration.
- Taxon
- CornZea mays subsp. mayst0
- Treatment
- Inoculation with A. brasilensee1
- Interactor
- A. brasilenseAzospirillum brasilensee1symbiont
- Outcome
- LCI, leaf concentration of Pe0
- Direction
- increasede0
- Comparator
- without A. brasilensee2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increased LCI, leaf concentration of P”
e1“Inoculation with A. brasilense decreased leaf concentration of Fe and increased LCI”
e2“one with and one without A. brasilense”
t0“Corn”
Claim · model-written summary
Azospirillum inoculation increased agronomic efficiency.
- Taxon
- cornZea mays subsp. mayse0
- Treatment
- Inoculation with A. brasilensee1
- Interactor
- A. brasilenseAzospirillum brasilensee1symbiont
- Outcome
- AEe0
- Direction
- increasede0
- Comparator
- without A. brasilensee2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increased LCI, leaf concentration of P, AE, and corn grain yield”
e1“Inoculation with A. brasilense decreased leaf concentration of Fe”
e2“one with and one without A. brasilense”
Claim · model-written summary
Azospirillum inoculation increased corn grain yield.
- Taxon
- cornZea mays subsp. mayse0
- Treatment
- Inoculation with A. brasilensee1
- Interactor
- A. brasilenseAzospirillum brasilensee1symbiont
- Outcome
- corn grain yielde0
- Direction
- increasede0
- Comparator
- without A. brasilensee2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increased LCI, leaf concentration of P, AE, and corn grain yield”
e1“Inoculation with A. brasilense decreased leaf concentration of Fe”
e2“one with and one without A. brasilense”
Claim · model-written summary
The authors considered Azospirillum inoculation viable even with high N rates.
- Taxon
- cornZea mays subsp. mayse1
- Interactor
- A. brasilenseAzospirillum brasilensee2symbiont
- Outcome
- use of this diazotrophic bacterium is therefore viable even when high rates of N are appliede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“use of this diazotrophic bacterium is therefore viable even when high rates of N are applied”
e1“AE, and corn grain yield; the use of this diazotrophic bacterium”
e2“Inoculation with A. brasilense decreased leaf concentration of Fe”
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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.