Abstract
Nitrogen (N) and potassium (K) are two important mineral nutrients in regulating leaf photosynthesis. Studying the interactive effects of N and K on regulating N allocation and photosynthesis (P n ) of rice leaves will be of great significance for further increasing leaf P n , photosynthetic N use efficiency (PNUE) and grain yield. We measured the gas exchange of rice leaves in a field experiment and tested different kinds of leaf N based on N morphology and function, and calculated the interactive effects of N and K on N allocation and the PNUE. Compared with N0 (0 kg N ha − 1 ) and K0 (0 kg K 2 O ha − 1 ) treatments, the P n was increased by 17.1 and 12.2% with the supply of N and K. Compared with N0K0 (0 kg N and 0 kg K 2 O ha − 1 ), N0K120 (0 kg N and 120 kg K 2 O ha − 1 ) and N0K180 (0 kg N and 180 kg K 2 O ha − 1 ), N supply increased the absolute content of photosynthetic N (N psn ) by 15.1, 15.5 and 10.5% on average, and the storage N (N store ) was increased by 32.7, 64.9 and 72.7% on average. The relative content of N psn was decreased by 5.6, 12.1 and 14.5%, while that of N store was increased by 8.7, 27.8 and 33.8%. Supply of K promoted the transformation of N store to N psn despite the leaf N content (N a ) was indeed decreased. Compared with N0K0, N180K0 (180 kg N and 0 kg K 2 O ha − 1 ) and N270K0 (270 kg N and 0 kg K 2 O ha − 1 ), K supply increased the relative content of N psn by 17.7, 8.8 and 7.3%, and decreased the relative content of N store by 24.2, 11.4 and 8.7% respectively. This study indicated the mechanism that K supply decreased the N a but increased the N psn content and then increased leaf P n and PNUE from a new viewpoint of leaf N allocation. The supply of K promoted the transformation of N store to N psn and increased the PNUE. The decreased N store mainly resulted from the decrease of non-protein N. Combined use of N and K could optimize leaf N allocation and maintain a high leaf N psn content and PNUE.
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Claims 14
Claim · model-written summary
Nitrogen supply raised rice leaf photosynthesis by 17.1%.
- Taxon
- rice
Oryza sativat0 - Treatment
- supply of Ne0
- Outcome
- P ne0
- Direction
- increasede0
- Value
- 17.1e0
- Comparator
- N0e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Compared with N0 (0 kg N ha − 1 ) and K0 (0 kg K 2 O ha − 1 ) treatments, the P n was increased by 17.1 and 12.2% with the supply of N and K.”
t0“rice leaves”
Claim · model-written summary
Potassium supply raised rice leaf photosynthesis by 12.2%.
- Taxon
- riceOryza sativat0
- Treatment
- supply of N and Ke0
- Outcome
- P ne0
- Direction
- increasede0
- Value
- 12.2%e0
- Comparator
- K0e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Compared with N0 (0 kg N ha − 1 ) and K0 (0 kg K 2 O ha − 1 ) treatments, the P n was increased by 17.1 and 12.2% with the supply of N and K.”
t0“rice leaves”
Claim · model-written summary
N supply increased absolute photosynthetic N by 15.1%, 15.5% and 10.5% across listed K backgrounds.
- Taxon
- riceOryza sativat0
- Treatment
- N supplye0
- Outcome
- absolute content of photosynthetic N (N psn )e0
- Direction
- increasede0
- Value
- 15.1, 15.5 and 10.5%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“N supply increased the absolute content of photosynthetic N (N psn ) by 15.1, 15.5 and 10.5% on average”
t0“rice leaves”
Claim · model-written summary
N supply increased storage N by 32.7%, 64.9% and 72.7%.
- Taxon
- riceOryza sativat0
- Treatment
- N supplyt1
- Outcome
- storage N (N store )e0
- Direction
- increasede0
- Value
- 32.7, 64.9 and 72.7%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the storage N (N store ) was increased by 32.7, 64.9 and 72.7% on average.”
t0“rice leaves”
t1“N supply increased the absolute content”
Claim · model-written summary
N supply decreased relative photosynthetic N by 5.6%, 12.1% and 14.5%.
- Taxon
- riceOryza sativat0
- Treatment
- N supplyt1
- Outcome
- relative content of N psne0
- Direction
- decreasede0
- Value
- 5.6, 12.1 and 14.5%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The relative content of N psn was decreased by 5.6, 12.1 and 14.5%”
t0“rice leaves”
t1“N supply increased the absolute content”
Claim · model-written summary
N supply increased relative storage N by 8.7%, 27.8% and 33.8%.
- Taxon
- riceOryza sativat0
- Treatment
- N supplyt1
- Outcome
- N storee0
- Direction
- increasede0
- Value
- 8.7, 27.8 and 33.8%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“that of N store was increased by 8.7, 27.8 and 33.8%.”
t0“rice leaves”
t1“N supply increased the absolute content”
Claim · model-written summary
K supply promoted conversion of storage N to photosynthetic N.
- Taxon
- riceOryza sativat0
- Treatment
- Supply of Ke0
- Outcome
- transformation of N store to N psne0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Supply of K promoted the transformation of N store to N psn”
t0“rice leaves”
Claim · model-written summary
K supply decreased leaf N content.
- Taxon
- riceOryza sativat0
- Treatment
- Supply of Kt1
- Outcome
- leaf N content (N a )e0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“leaf N content (N a ) was indeed decreased.”
t0“rice leaves”
t1“Supply of K promoted the transformation”
Claim · model-written summary
K increased relative photosynthetic N by 17.7%, 8.8% and 7.3%.
- Taxon
- riceOryza sativat0
- Treatment
- K supplye0
- Outcome
- relative content of N psne0
- Direction
- increasede0
- Value
- 17.7, 8.8 and 7.3%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“K supply increased the relative content of N psn by 17.7, 8.8 and 7.3%”
t0“rice leaves”
Claim · model-written summary
K decreased relative storage N by 24.2%, 11.4% and 8.7%.
- Taxon
- riceOryza sativat0
- Treatment
- K supplyt1
- Outcome
- relative content of N storee0
- Direction
- decreasede0
- Value
- 24.2, 11.4 and 8.7%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“decreased the relative content of N store by 24.2, 11.4 and 8.7% respectively.”
t0“rice leaves”
t1“K supply increased the relative content”
Claim · model-written summary
K supply increased leaf photosynthesis and PNUE through photosynthetic N allocation.
- Taxon
- riceOryza sativat0
- Treatment
- K supplye0
- Outcome
- leaf P n and PNUEe0
- Qualifier
- increased the N psn contente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“K supply decreased the N a but increased the N psn content and then increased leaf P n and PNUE”
t0“rice leaves”
Claim · model-written summary
K supply increased PNUE.
- Taxon
- riceOryza sativat0
- Treatment
- supply of Ke0
- Outcome
- PNUEe0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The supply of K promoted the transformation of N store to N psn and increased the PNUE.”
t0“rice leaves”
Claim · model-written summary
Reduced storage N primarily reflected reduced non-protein N.
- Taxon
- riceOryza sativat0
- Outcome
- decreased N storee0
- Qualifier
- decrease of non-protein Ne0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The decreased N store mainly resulted from the decrease of non-protein N.”
t0“rice leaves”
Claim · model-written summary
Combined N and K use could optimize leaf N allocation and maintain high photosynthetic N and PNUE.
- Taxon
- riceOryza sativat0
- Outcome
- Combined use of N and Ke0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Combined use of N and K could optimize leaf N allocation and maintain a high leaf N psn content and PNUE.”
t0“rice leaves”
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