Abstract
The development of vertical canopy gradients of leaf N has been regarded as an adaptation to the light gradient that helps to maximize canopy photosynthesis. In this study we report the dynamics of vertical leaf N distribution during vegetative growth of wheat in response to changes in N availability and sowing density. The question of to what extent the observed vertical leaf N distribution maximized canopy photosynthesis was addressed with a leaf layer model of canopy photosynthesis that integrates N-dependent leaf photosynthesis according to the canopy light and leaf N distribution. Plants were grown hydroponically at two amounts of N, supplied in proportion to calculated growth rates. Photosynthesis at light saturation correlated with leaf N. The vertical leaf N distribution was associated with the gradient of absorbed light. The leaf N prole changed during crop development and was responsive to N availability. At high N supply, the leaf N proles were constant during crop development. At low N supply, the leaf N proles uctuated between more uniform and steep distributions. These changes were associated with reduced leaf area expansion and increasing N remobilization from lower leaf layers. The distribution of leaf N with respect to the gradient of absorbed irradiance was close to the theoretical optimum maximizing canopy photosynthesis. Sensitivity analysis of the photosynthesis model suggested that plants maintain an optimal vertical leaf N distribution by balancing the capacity for photosynthesis at high and low light.
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Claims 9
Claim · model-written summary
Light saturated photosynthesis correlated with leaf nitrogen.
- Taxon
- Wheat
Triticum aestivumt0 - Compound
- leaf Ne0
- Outcome
- Photosynthesis at light saturatione0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Photosynthesis at light saturation correlated with leaf N”
t0“Wheat”
Claim · model-written summary
Vertical leaf nitrogen distribution was associated with absorbed light gradient.
- Taxon
- WheatTriticum aestivumt0
- Outcome
- vertical leaf N distributione0
- Setting
- gradient of absorbed lighte0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The vertical leaf N distribution was associated with the gradient of absorbed light”
t0“Wheat”
Claim · model-written summary
Leaf nitrogen profiles changed during crop development and responded to nitrogen availability.
- Taxon
- WheatTriticum aestivumt0
- Treatment
- N availabilitye0
- Outcome
- leaf N prolee0
- Qualifier
- during crop developmente0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The leaf N prole changed during crop development and was responsive to N availability”
t0“Wheat”
Claim · model-written summary
At high nitrogen supply, leaf nitrogen profiles stayed constant during crop development.
- Taxon
- WheatTriticum aestivumt0
- Treatment
- high N supplye0
- Outcome
- leaf N prolese0
- Direction
- constante0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At high N supply, the leaf N proles were constant during crop development”
t0“Wheat”
Claim · model-written summary
At low nitrogen supply, leaf nitrogen profiles fluctuated between uniform and steep distributions.
- Taxon
- WheatTriticum aestivumt0
- Treatment
- low N supplye0
- Outcome
- leaf N prolese0
- Direction
- uctuatede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At low N supply, the leaf N proles uctuated between more uniform and steep distributions”
t0“Wheat”
Claim · model-written summary
These profile changes were associated with reduced leaf area expansion.
- Taxon
- WheatTriticum aestivumt0
- Organ / stage
- leafe0
- Outcome
- leaf area expansione0
- Direction
- reducede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“These changes were associated with reduced leaf area expansion”
t0“Wheat”
Claim · model-written summary
These profile changes were associated with increasing nitrogen remobilization from lower leaf layers.
- Taxon
- WheatTriticum aestivumt0
- Organ / stage
- lower leaf layerse0
- Outcome
- N remobilizatione0
- Direction
- increasinge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“These changes were associated with reduced leaf area expansion and increasing N remobilization from lower leaf layers”
t0“Wheat”
Claim · model-written summary
Leaf nitrogen distribution relative to absorbed light was close to the theoretical photosynthesis optimum.
- Taxon
- WheatTriticum aestivumt0
- Outcome
- distribution of leaf Ne0
- Direction
- close toe0
- Comparator
- theoretical optimume0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The distribution of leaf N with respect to the gradient of absorbed irradiance was close to the theoretical optimum maximizing canopy photosynthesis”
t0“Wheat”
Claim · model-written summary
Model sensitivity analysis suggested plants maintain optimal vertical leaf nitrogen distribution by balancing photosynthetic capacity at high and low light.
- Taxon
- WheatTriticum aestivumt0
- Outcome
- optimal vertical leaf N distributione0
- Qualifier
- balancing the capacity for photosynthesis at high and low lighte0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Sensitivity analysis of the photosynthesis model suggested that plants maintain an optimal vertical leaf N distribution by balancing the capacity for photosynthesis at high and low light”
t0“Wheat”