Abstract
Nitrogen is often a limiting factor in pearl millet [ Pennisetum glaucum (L.) R. Br.] production. Genotypes are known that differ their response to N. In this study four pearl millet genotypes, which were previously identified as extremes in N use efficiency (total above ground biomass/unit of N absorbed) in the field, were compared in nutrient solution culture for their response to N supply and the instantaneous measurement of photosynthetic N efficiency (μmol CO 2 g −1 N s −1 ). The latter component possibly contributes to N use efficiency. N‐efficient genotypes, ‘Souna B’ and 700112, and N‐inefficient genotypes, ‘BK560’ and ‘BJ104’, were grown at four N levels containing 60, 120, 180, and 240 mg N plant −1 . Specific leaf area (cm 2 g −1 ) was calculated from an accompanying growth analysis. Leaf CO 2 exchange rate was measured on several leaves as they became fully expanded. Photosynthetic N efficiency was derived using values of leaf N concentration. Nitrogen‐efficient genotypes maintained thicker leaves (316.1 vs. 332.5 cm 2 g −1 ) and were generally less responsive in terms of leaf N concentrations and leaf CO 2 exchanger ate (CER) to the N available in solution as compared to the N‐inefficient genotypes. Souna B, the most efficient genotype, maintained a stable CER across all N levels. Photosynthetic N efficiency was similar for all genotypes except BK560, which was 10 to 15% less efficient. The small difference in photosynthetic N efficiency among genotypes coupled with relatively high photosynthetic N efficiency values of BJ104 (N‐inefficient genotype) suggests that differences in instantaneous measures of N use efficiency occurring during photosynthesis offer little explanation for overall differences in N use efficiency among these genotypes in a previous field study. Nitrogen use efficiency was more related to the partitioning of N resources available into additional leaf area.
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Claims 7
Claim · model-written summary
Nitrogen efficient genotypes had thicker leaves than inefficient genotypes.
- Taxon
- Pearl Millet
Cenchrus americanust0 - Material
- Nitrogen‐efficient genotypese0
- Outcome
- thicker leavese0
- Direction
- thickere0
- Value
- 316.1 vs. 332.5 cm 2 g −1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Pearl Millet”
e0“Nitrogen‐efficient genotypes maintained thicker leaves (316.1 vs. 332.5 cm 2 g −1 )”
Claim · model-written summary
Nitrogen efficient genotypes were less responsive in leaf nitrogen concentration to solution nitrogen.
- Taxon
- Pearl MilletCenchrus americanust0
- Treatment
- N available in solutione0
- Outcome
- leaf N concentrationse0
- Direction
- less responsivee0
- Comparator
- N‐inefficient genotypese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Pearl Millet”
e0“were generally less responsive in terms of leaf N concentrations and leaf CO 2 exchanger ate (CER) to the N available in solution as compared to the N‐inefficient genotypes”
Claim · model-written summary
Nitrogen efficient genotypes were less responsive in leaf CO2 exchange rate to solution nitrogen.
- Taxon
- Pearl MilletCenchrus americanust0
- Treatment
- N available in solutione0
- Outcome
- leaf CO 2 exchanger ate (CER)e0
- Direction
- less responsivee0
- Comparator
- N‐inefficient genotypese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Pearl Millet”
e0“were generally less responsive in terms of leaf N concentrations and leaf CO 2 exchanger ate (CER) to the N available in solution as compared to the N‐inefficient genotypes”
Claim · model-written summary
Souna B maintained stable leaf CO2 exchange rate across nitrogen levels.
- Taxon
- Pearl MilletCenchrus americanust0
- Material
- Souna Be0
- Outcome
- CERe0
- Direction
- stablee0
- Qualifier
- across all N levelse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Pearl Millet”
e0“Souna B, the most efficient genotype, maintained a stable CER across all N levels”
Claim · model-written summary
BK560 had 10 to 15% lower photosynthetic nitrogen efficiency than the other genotypes.
- Taxon
- Pearl MilletCenchrus americanust0
- Material
- BK560e0
- Outcome
- Photosynthetic N efficiencye0
- Direction
- less efficiente0
- Value
- 10 to 15%e0
- Comparator
- all genotypes except BK560e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Pearl Millet”
e0“Photosynthetic N efficiency was similar for all genotypes except BK560, which was 10 to 15% less efficient”
Claim · model-written summary
Instantaneous photosynthetic nitrogen use efficiency explained little of prior field differences in overall nitrogen use efficiency.
- Taxon
- Pearl MilletCenchrus americanust0
- Outcome
- overall differences in N use efficiencye0
- Qualifier
- little explanatione0
- Comparator
- instantaneous measures of N use efficiencye0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Pearl Millet”
e0“differences in instantaneous measures of N use efficiency occurring during photosynthesis offer little explanation for overall differences in N use efficiency among these genotypes in a previous field study”
Claim · model-written summary
Nitrogen use efficiency was more related to nitrogen partitioning into extra leaf area.
- Taxon
- Pearl MilletCenchrus americanust0
- Organ / stage
- leaf areae0
- Outcome
- Nitrogen use efficiencye0
- Qualifier
- partitioning of N resources available into additional leaf areae0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Pearl Millet”
e0“Nitrogen use efficiency was more related to the partitioning of N resources available into additional leaf area”