Abstract
This study investigated whether and how irrigation regimes interact with nitrogen (N) application rates to mediate the grain yield, N use efficiency (NUE) and water use efficiency (WUE) in rice and to understand the underlying mechanism. A field experiment was conducted with two irrigation regimes, continuously flooded (CF) and alternate wetting and moderate drying (AWMD), and three N application rates, 120 kg ha−1 N (a low N rate, LN), 240 kg ha−1 N (a medium N rate, MN) and 360 kg ha−1 N (a high N rate, HN) in 2021 and 2022. The results showed that the grain yield exhibited the lowest values at the LN, regardless of the irrigation regime, while it was the highest at the MN when the CF regime was adopted. The grain yield was comparable between the MN and HN regarding the AWMD regime. AWMD significantly increased the grain yield, NUE and WUE compared to CF at the same N rate, which was attributed to a higher photosynthetic rate, improved population quality, enhanced nonstructural carbohydrate remobilization from stems to grains during grain filling, and elevated activities of enzymes involved in N assimilation in the roots. The results suggest that an AWMD regime combined with MN treatment could pronounce a synergistic interaction on the grain yield, NUE and WUE in rice by improving root and shoot physiological performances.
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Claims 9
Claim · model-written summary
Low nitrogen produced the lowest grain yield under either irrigation regime.
- Taxon
- rice
Oryza sativat0 - Treatment
- LNe0
- Outcome
- grain yielde0
- Direction
- loweste0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the grain yield exhibited the lowest values at the LN, regardless of the irrigation regime”
t0“Rice”
Claim · model-written summary
Under continuous flooding, medium nitrogen produced the highest grain yield.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the grain yield exhibited the lowest values at the LN, regardless of the irrigation regime, while it was the highest at the MN when the CF regime was adopted”
t0“Rice”
Claim · model-written summary
Under AWMD, grain yield was comparable at medium and high nitrogen.
- Taxon
- RiceOryza sativat0
- Treatment
- MNe0
- Outcome
- grain yielde0
- Direction
- comparablee0
- Qualifier
- AWMD regimee0
- Comparator
- HNe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The grain yield was comparable between the MN and HN regarding the AWMD regime”
t0“Rice”
Claim · model-written summary
AWMD increased grain yield versus continuous flooding at the same nitrogen rate.
- Taxon
- RiceOryza sativat0
- Treatment
- AWMDe0
- Outcome
- grain yielde0
- Direction
- increasede0
- Qualifier
- same N ratee0
- Comparator
- CFe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“AWMD significantly increased the grain yield, NUE and WUE compared to CF at the same N rate”
t0“Rice”
Claim · model-written summary
AWMD increased nitrogen use efficiency versus continuous flooding at the same nitrogen rate.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“AWMD significantly increased the grain yield, NUE and WUE compared to CF at the same N rate”
t0“Rice”
Claim · model-written summary
AWMD increased water use efficiency versus continuous flooding at the same nitrogen rate.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“AWMD significantly increased the grain yield, NUE and WUE compared to CF at the same N rate”
t0“Rice”
Claim · model-written summary
The authors attribute AWMD benefits to higher photosynthesis and improved population quality.
- Taxon
- RiceOryza sativat0
- Outcome
- higher photosynthetic rate, improved population qualitye0
- Qualifier
- attributed toe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“which was attributed to a higher photosynthetic rate, improved population quality”
t0“Rice”
Claim · model-written summary
The authors attribute AWMD benefits to greater stem to grain carbohydrate remobilization.
- Taxon
- RiceOryza sativat0
- Organ / stage
- stems to grainse0
- Outcome
- nonstructural carbohydrate remobilizatione0
- Direction
- enhancede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“enhanced nonstructural carbohydrate remobilization from stems to grains during grain filling”
t0“Rice”
Claim · model-written summary
The authors attribute AWMD benefits to elevated root nitrogen assimilation enzyme activities.
- Taxon
- RiceOryza sativat0
- Organ / stage
- rootse0
- Outcome
- activities of enzymes involved in N assimilatione0
- Direction
- elevatede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“elevated activities of enzymes involved in N assimilation in the roots”
t0“Rice”
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