Abstract
Abstract Nitrogen deficiency can severely limit sunflower ( Helianthus annuus L.) grain yield and quality. Our objective was to evaluate N diagnosis methods based on: (a) pre‐plant soil nitrate‐nitrogen (NO 3 – –N) test (PPSNT) and soil N mineralized in short‐term anaerobic incubation (Nan), (b) Greenness index (G I ) and the normalized difference vegetation index (NDVI) measured at 6 (V 6 ) and 12 (V 12 ) leaves, and (c) grain nitrogen concentration (N c ). Seventeen experiments were carried out between 2010 and 2019 in Argentina, evaluating nine N rates (0, 30, 40, 60, 80, 90, 120, 150, and 160 kg N ha –1 ). The G I , NDVI, N sufficiency index and relative normalized difference vegetation index (NDVIr) were determined at V 6 and V 12 growth stages. On average, yield response to N was 492 kg ha –1 and N c response was 0.25% in 9 and 11 responsive experiments, respectively. The inclusion of Nan improved the PPSNT diagnosis method. The critical N availability (PPSNT + fertilizer N) threshold was 115 kg N ha –1 for experiments with low Nan (<60 mg kg –1 ), and 90 kg N ha –1 for experiments with high Nan (>60 mg kg –1 ). The NDVIr at V 12 allowed monitoring the crop N status with a 0.95 critical threshold. The N c adequately diagnosed N deficiencies and the critical threshold was 2.26%. Also, N c was predicted from the ratio between N availability and grain yield ( R 2 = .39). Our results would allow to better estimate N availability to recommend adequate N fertilizer rates for sunflower aiming to optimize grain yield and quality, and minimize the economic and environmental cost of fertilization.
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Claims 8
Claim · model-written summary
Nitrogen increased yield by an average of 492 kg ha –1 in nine responsive experiments.
- Taxon
- sunflower
Helianthus annuuse1 - Treatment
- Ne0
- Outcome
- yield responsee0
- Direction
- increaseinferrede0
- Value
- 492 kg ha –1e0
- Qualifier
- 9 and 11 responsive experiments, respectivelye0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“On average, yield response to N was 492 kg ha –1 and N c response was 0.25% in 9 and 11 responsive experiments, respectively.”
e1“sunflower ( Helianthus annuus L.)”
Claim · model-written summary
Nitrogen increased grain nitrogen concentration by an average of 0.25% in eleven responsive experiments.
- Taxon
- sunflowerHelianthus annuuse1
- Treatment
- Ne0
- Outcome
- grain nitrogen concentration (N c )e2
- Direction
- increaseinferrede0
- Value
- 0.25%e0
- Qualifier
- 11 responsive experimentse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“On average, yield response to N was 492 kg ha –1 and N c response was 0.25% in 9 and 11 responsive experiments, respectively.”
e1“sunflower ( Helianthus annuus L.)”
e2“grain nitrogen concentration (N c )”
Claim · model-written summary
Including Nan improved the preplant soil nitrate diagnostic method.
- Taxon
- sunflowerHelianthus annuuse1
- Outcome
- PPSNT diagnosis methode0
- Direction
- improvede0
- Comparator
- PPSNTe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The inclusion of Nan improved the PPSNT diagnosis method.”
e1“sunflower ( Helianthus annuus L.)”
Claim · model-written summary
Critical nitrogen availability was 115 kg N ha –1 with low Nan.
- Taxon
- sunflowerHelianthus annuuse1
- Outcome
- critical N availability (PPSNT + fertilizer N) thresholde0
- Value
- 115 kg N ha –1e0
- Qualifier
- low Nan (<60 mg kg –1 )e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The critical N availability (PPSNT + fertilizer N) threshold was 115 kg N ha –1 for experiments with low Nan (<60 mg kg –1 ), and 90 kg N ha –1 for experiments with high Nan (>60 mg kg –1 ).”
e1“sunflower ( Helianthus annuus L.)”
Claim · model-written summary
Critical nitrogen availability was 90 kg N ha –1 with high Nan.
- Taxon
- sunflowerHelianthus annuuse1
- Outcome
- critical N availability (PPSNT + fertilizer N) thresholde0
- Value
- 90 kg N ha –1e0
- Qualifier
- high Nan (>60 mg kg –1 )e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The critical N availability (PPSNT + fertilizer N) threshold was 115 kg N ha –1 for experiments with low Nan (<60 mg kg –1 ), and 90 kg N ha –1 for experiments with high Nan (>60 mg kg –1 ).”
e1“sunflower ( Helianthus annuus L.)”
Claim · model-written summary
NDVIr at V12 monitored crop nitrogen status with threshold 0.95.
- Taxon
- sunflowerHelianthus annuuse1
- Organ / stage
- V 12e0
- Outcome
- monitoring the crop N statuse0
- Value
- 0.95e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The NDVIr at V 12 allowed monitoring the crop N status with a 0.95 critical threshold.”
e1“sunflower ( Helianthus annuus L.)”
Claim · model-written summary
Grain nitrogen concentration adequately diagnosed deficiencies with threshold 2.26%.
- Taxon
- sunflowerHelianthus annuuse1
- Outcome
- diagnosed N deficienciese0
- Value
- 2.26%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The N c adequately diagnosed N deficiencies and the critical threshold was 2.26%.”
e1“sunflower ( Helianthus annuus L.)”
Claim · model-written summary
The availability to yield ratio predicted grain nitrogen concentration with R2 of .39.
- Taxon
- sunflowerHelianthus annuuse1
- Outcome
- N c was predictede0
- Value
- R 2 = .39e0
- Qualifier
- ratio between N availability and grain yielde0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“N c was predicted from the ratio between N availability and grain yield ( R 2 = .39).”
e1“sunflower ( Helianthus annuus L.)”
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See all 196 papers →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.