Abstract
Eight rice experiments were established at two sites in the Riverina district of south-eastern Australia in the 2012–13 and 2013–14 seasons. Two semi-dwarf rice varieties were drill-sown and nitrogen (N) fertiliser (urea) was applied at different rates at the 4-leaf stage before permanent water (pre-PW) and at panicle initiation (PI). The research assessed the impact of timing of N application on grain yield, compared the apparent N recovery of N fertiliser applied at the two stages, and determined an application strategy for N to obtain consistently high grain yields for current, semi-dwarf rice varieties when drill-sown. The apparent N recoveries achieved were 59% for N applied pre-PW and 25% for N applied at PI, averaged across years, sites, varieties and N rates. Grain yield increased significantly with increased rate of N applied at both stages, but the rate of increase from N applied at PI decreased as the rate of N applied pre-PW increased. The grain yield increase for N applied pre-PW was due to increased number of panicles at maturity and increased number of florets per panicle. Nitrogen applied at PI increased dry matter at maturity and number of florets per panicle. Application of N at PI increased grain yield over that when no N was applied; however, at low PI N-uptake levels, application of N at PI is not enough to achieve high grain yields. Therefore, sufficient N should be available to the crop from a combination of soil- and pre-PW-applied N for the crop to reach a level of N uptake at PI whereby high yields can be achieved. Nitrogen applied at PI did not appear to increase the potential for cold-induced floret sterility as much as pre-PW-applied N. Further research is required to confirm this in other seasons and for other rice varieties.
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Claims 9
Claim · model-written summary
Apparent N recovery was 59% before permanent water.
- Taxon
- rice
Oryza sativat0 - Treatment
- N applied pre-PWe0
- Outcome
- apparent N recoveriese0
- Value
- 59%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The apparent N recoveries achieved were 59% for N applied pre-PW and 25% for N applied at PI”
t0“Nitrogen rate and timing effects on growth and yield of drill-sown rice”
Claim · model-written summary
Apparent N recovery was 25% at panicle initiation.
- Taxon
- riceOryza sativat0
- Treatment
- N applied at PIe0
- Outcome
- apparent N recoveriese0
- Value
- 25%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The apparent N recoveries achieved were 59% for N applied pre-PW and 25% for N applied at PI”
t0“Nitrogen rate and timing effects on growth and yield of drill-sown rice”
Claim · model-written summary
Grain yield increased significantly with greater N rates at both stages.
- Taxon
- riceOryza sativat0
- Treatment
- increased rate of N applied at both stagese0
- Outcome
- Grain yielde0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Grain yield increased significantly with increased rate of N applied at both stages”
t0“Nitrogen rate and timing effects on growth and yield of drill-sown rice”
Claim · model-written summary
The yield response to PI nitrogen weakened as pre-PW nitrogen rose.
- Taxon
- riceOryza sativat0
- Treatment
- N applied at PIe0
- Outcome
- rate of increasee0
- Direction
- decreasede0
- Comparator
- N applied pre-PWe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the rate of increase from N applied at PI decreased as the rate of N applied pre-PW increased”
t0“Nitrogen rate and timing effects on growth and yield of drill-sown rice”
Claim · model-written summary
Pre-PW nitrogen increased panicle number and florets per panicle.
- Taxon
- riceOryza sativat0
- Treatment
- N applied pre-PWe0
- Outcome
- number of panicles at maturity and increased number of florets per paniclee0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The grain yield increase for N applied pre-PW was due to increased number of panicles at maturity and increased number of florets per panicle”
t0“Nitrogen rate and timing effects on growth and yield of drill-sown rice”
Claim · model-written summary
PI nitrogen increased dry matter at maturity and florets per panicle.
- Taxon
- riceOryza sativat0
- Treatment
- Nitrogen applied at PIe0
- Outcome
- dry matter at maturity and number of florets per paniclee0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nitrogen applied at PI increased dry matter at maturity and number of florets per panicle”
t0“Nitrogen rate and timing effects on growth and yield of drill-sown rice”
Claim · model-written summary
PI nitrogen increased grain yield over no nitrogen.
- Taxon
- riceOryza sativat0
- Treatment
- Application of N at PIe0
- Outcome
- grain yielde0
- Direction
- increasede0
- Comparator
- when no N was appliede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Application of N at PI increased grain yield over that when no N was applied”
t0“Nitrogen rate and timing effects on growth and yield of drill-sown rice”
Claim · model-written summary
Low PI nitrogen uptake was insufficient for high yield even with PI nitrogen application.
- Taxon
- riceOryza sativat0
- Outcome
- high grain yieldse0
- Qualifier
- at low PI N-uptake levelse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“at low PI N-uptake levels, application of N at PI is not enough to achieve high grain yields”
t0“Nitrogen rate and timing effects on growth and yield of drill-sown rice”
Claim · model-written summary
PI nitrogen appeared less likely than pre-PW nitrogen to increase cold-induced floret sterility.
- Taxon
- riceOryza sativat0
- Treatment
- Nitrogen applied at PIe0
- Outcome
- potential for cold-induced floret sterilitye0
- Direction
- did not appear to increasee0
- Comparator
- pre-PW-applied Ne0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nitrogen applied at PI did not appear to increase the potential for cold-induced floret sterility as much as pre-PW-applied N”
t0“Nitrogen rate and timing effects on growth and yield of drill-sown rice”
The same questions in other papers
nitrogen · yield · Oryza sativa (rice)Positive and negative results
1,802 papers in the same direction as this paper · 193 in the opposite direction · 49 reporting no difference from an alternative
- no effect
- no effect
- no effect
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