Abstract
Abstract Water deficit and insufficient N supply are important constraints to the productivity of rainfed lowland rice ( Oryzu sativa L.). To determine the effects of water deficit and urea application timing on yield and N accumulation of lowland rice, a field experiment was conducted for 2 yr on an Andaqueptic Haplaquoll in the Philippines. Water regimes imposed in the dry season were continuously flooded, not flooded or irrigated from 15 to 35 d after transplanting (DT), and not flooded or irrigated from 41 to 63 DT. Urea treatments in factorial combination with the water regimes were no applied N, early N (80 kg N ha −1 , one‐half basal incorporated and one‐half broadcast at 37 DT), and late N (80 kg N ha −1 , one‐half broadcast at 11 DT and onehalf broadcast at 65 DT). Water deficit at 15 to 35 DT significantly reduced mean grain yield (26%), straw yield (21%), grain N accumulation (31%), and straw N accumulation (31%). Water deficit at 41 to 63 DT, which ended before panicle emergence, decreased yield and N uptake, but less than water deficit at 15 to 35 DT. Nitrogen application consistently increased grain yield even when the rice crop was exposed to water deficit. Mean grain yields were greater ( P < 0.05) for early N (5.7 Mg ha −1 ) than late N (3.7 Mg ha −1 ) in 1986 but not in 1987 (4.1 and 3.8 Mg ha −1 , respectively). Water‐by‐N interactions were not significant for grain or straw yields and grain or straw N accumulations. The N timing most effective for continuously irrgated rice was also most effective for rice exposed to moderate water deficit before flowering.
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Claims 11
Claim · model-written summary
Water deficit at 15 to 35 days after transplanting reduced rice grain yield by 26%.
- Taxon
- rice
Oryza sativat0 - Treatment
- Water deficit at 15 to 35 DTe0
- Outcome
- grain yielde0
- Direction
- reducede0
- Value
- 26%e0
- Setting
- Philippinese1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Water deficit at 15 to 35 DT significantly reduced mean grain yield (26%)”
t0“Rice Yield”
t1“Rice Yield”
e1“a field experiment was conducted for 2 yr on an Andaqueptic Haplaquoll in the Philippines”
Claim · model-written summary
The same water deficit reduced straw yield by 21%.
- Taxon
- RiceOryza sativat0
- Treatment
- Water deficit at 15 to 35 DTe0
- Outcome
- straw yielde0
- Direction
- reducede0
- Value
- 21%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Water deficit at 15 to 35 DT significantly reduced mean grain yield (26%), straw yield (21%)”
t0“Rice Yield”
t1“Rice Yield”
Claim · model-written summary
The same deficit reduced grain nitrogen accumulation by 31%.
- Taxon
- RiceOryza sativat0
- Treatment
- Water deficit at 15 to 35 DTe0
- Outcome
- grain N accumulatione0
- Direction
- reducede0
- Value
- 31%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Water deficit at 15 to 35 DT significantly reduced mean grain yield (26%), straw yield (21%), grain N accumulation (31%)”
t0“Rice Yield”
t1“Rice Yield”
Claim · model-written summary
The same deficit reduced straw nitrogen accumulation by 31%.
- Taxon
- RiceOryza sativat0
- Treatment
- Water deficit at 15 to 35 DTe0
- Outcome
- straw N accumulatione0
- Direction
- reducede0
- Value
- 31%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Water deficit at 15 to 35 DT significantly reduced mean grain yield (26%), straw yield (21%), grain N accumulation (31%), and straw N accumulation (31%)”
t0“Rice Yield”
t1“Rice Yield”
Claim · model-written summary
Water deficit at 41 to 63 days after transplanting decreased yield and nitrogen uptake less than earlier deficit.
- Taxon
- RiceOryza sativat0
- Treatment
- Water deficit at 41 to 63 DTe0
- Outcome
- yield and N uptakee0
- Direction
- decreasede0
- Qualifier
- before panicle emergencee0
- Comparator
- water deficit at 15 to 35 DTe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Water deficit at 41 to 63 DT, which ended before panicle emergence, decreased yield and N uptake, but less than water deficit at 15 to 35 DT.”
t0“Rice Yield”
t1“Rice Yield”
Claim · model-written summary
Nitrogen application consistently increased grain yield despite water deficit.
- Taxon
- riceOryza sativae0
- Treatment
- Nitrogen applicatione0
- Outcome
- grain yielde0
- Direction
- increasede0
- Qualifier
- even when the rice crop was exposed to water deficite0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nitrogen application consistently increased grain yield even when the rice crop was exposed to water deficit.”
Claim · model-written summary
In 1986 early nitrogen produced greater mean grain yield than late nitrogen, 5.7 versus 3.7 Mg ha −1.
- Taxon
- RiceOryza sativat0
- Treatment
- early Ne0
- Outcome
- grain yieldse0
- Direction
- greatere0
- Value
- 5.7 Mg ha −1e0
- Qualifier
- 3.7 Mg ha −1e0
- Comparator
- late Ne0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Mean grain yields were greater ( P < 0.05) for early N (5.7 Mg ha −1 ) than late N (3.7 Mg ha −1 ) in 1986”
t0“Rice Yield”
t1“Rice Yield”
Claim · model-written summary
In 1987 early and late nitrogen grain yields did not differ significantly, at 4.1 and 3.8 Mg ha −1 respectively.
- Taxon
- RiceOryza sativat0
- Treatment
- early Ne1
- Outcome
- grain yieldse1
- Value
- 4.1 and 3.8 Mg ha −1e0
- Comparator
- late Ne1
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“but not in 1987 (4.1 and 3.8 Mg ha −1 , respectively)”
t0“Rice Yield”
t1“Rice Yield”
e1“Mean grain yields were greater ( P < 0.05) for early N (5.7 Mg ha −1 ) than late N (3.7 Mg ha −1 ) in 1986”
Claim · model-written summary
Water-by-nitrogen interactions were not significant for grain or straw yields.
- Taxon
- RiceOryza sativat0
- Treatment
- Water‐by‐N interactionse0
- Outcome
- grain or straw yieldse0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Water‐by‐N interactions were not significant for grain or straw yields and grain or straw N accumulations.”
t0“Rice Yield”
t1“Rice Yield”
Claim · model-written summary
Water-by-nitrogen interactions were not significant for grain or straw nitrogen accumulation.
- Taxon
- RiceOryza sativat0
- Treatment
- Water‐by‐N interactionse0
- Outcome
- grain or straw N accumulationse0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Water‐by‐N interactions were not significant for grain or straw yields and grain or straw N accumulations.”
t0“Rice Yield”
t1“Rice Yield”
Claim · model-written summary
The nitrogen timing most effective under continuous irrigation was also most effective with moderate preflowering deficit.
- Taxon
- riceOryza sativae0
- Treatment
- N timinge0
- Outcome
- most effectivee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The N timing most effective for continuously irrgated rice was also most effective for rice exposed to moderate water deficit before flowering.”
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