Abstract
SUMMARY Two years with contrasting weather, 1976 and 1977, were used to investigate the effects of nitrogen fertilizer on the uptake of nitrogen by crops of winter wheat and on the rate of photosynthesis of flag leaves. The studies involved a number of crops which received various amounts of nitrogen fertilizer at various stages of growth. Weekly measurements were made of the amount of nitrogen in the crops and its distribution within the plant, while a mobile gas exchange system measured the photosynthesis of individual flag leaves. While the treatments imposed in 1976 resulted in different concentrations of nitrogen in the flag leaves, the maximum rate of photosynthesis and its efficiency in dull light were both unaffected when leaves of the same age were compared. The 2 years gave contrasting results in terms of the amounts of nitrogen taken up during grain growth: in the very dry summer of 1976 it could account for only 25% of the nitrogen in the ear at harvest while in 1977 it could account for almost 50%. These different amounts of translocation to the grain were accompanied by different photosynthetic behaviours of the flag leaves and our analysis shows that, in all treatments, the maximum rate of photosynthesis after anthesis was related to the fractional loss of nitrogen from the leaves. The implications of these results for farming practice and for techniques used to investigate the effects of nitrogen on photosynthesis are discussed.
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Claims 6
Claim · model-written summary
Nitrogen treatments changed flag-leaf nitrogen concentrations in 1976.
- Taxon
- winter wheat
Triticum aestivumt0 - Treatment
- treatments imposed in 1976e0
- Outcome
- concentrations of nitrogen in the flag leavese0
- Direction
- differente0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the treatments imposed in 1976 resulted in different concentrations of nitrogen in the flag leaves”
t0“winter wheat”
Claim · model-written summary
Maximum flag-leaf photosynthetic rate was unaffected by 1976 nitrogen treatments for same-age leaves.
- Taxon
- winter wheatTriticum aestivumt0
- Treatment
- nitrogen fertilizere1
- Outcome
- maximum rate of photosynthesise0
- Direction
- unaffectede0
- Comparator
- leaves of the same agee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the maximum rate of photosynthesis and its efficiency in dull light were both unaffected when leaves of the same age were compared”
t0“winter wheat”
e1“effects of nitrogen fertilizer”
Claim · model-written summary
Photosynthetic efficiency in dull light was unaffected by 1976 nitrogen treatments for same-age leaves.
- Taxon
- winter wheatTriticum aestivumt0
- Treatment
- nitrogen fertilizere1
- Outcome
- efficiency in dull lighte0
- Direction
- unaffectede0
- Comparator
- leaves of the same agee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the maximum rate of photosynthesis and its efficiency in dull light were both unaffected when leaves of the same age were compared”
t0“winter wheat”
e1“effects of nitrogen fertilizer”
Claim · model-written summary
Uptake during grain growth accounted for only 25% of ear nitrogen at harvest in dry 1976.
- Taxon
- winter wheatTriticum aestivumt0
- Outcome
- nitrogen in the ear at harveste0
- Value
- 25%e0
- Qualifier
- very dry summer of 1976e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“in the very dry summer of 1976 it could account for only 25% of the nitrogen in the ear at harvest”
t0“winter wheat”
Claim · model-written summary
Uptake during grain growth accounted for almost 50% of ear nitrogen at harvest in 1977.
- Taxon
- winter wheatTriticum aestivumt0
- Outcome
- nitrogen in the ear at harveste1
- Value
- almost 50%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“while in 1977 it could account for almost 50%”
t0“winter wheat”
e1“nitrogen in the ear at harvest”
Claim · model-written summary
Post-anthesis maximum photosynthesis was related to fractional nitrogen loss from flag leaves across treatments.
- Taxon
- winter wheatTriticum aestivumt0
- Organ / stage
- leavese0
- Compound
- nitrogene0
- Outcome
- maximum rate of photosynthesis after anthesise0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“in all treatments, the maximum rate of photosynthesis after anthesis was related to the fractional loss of nitrogen from the leaves”
t0“winter wheat”
The same questions in other papers
fertilization · physiology: photosynthesis · Triticum aestivum (wheat)Positive and negative results
6 papers in the same direction as this paper · 126 reporting no difference from an alternative
- negative
- positive
- positive
129 papers more in this group
See all 133 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.