Abstract
A field experiment was conducted to investigate the interaction of nitrogen (N) status, sowing date, and water depth on rice yield in the Murray Valley, New South Wales, where low minimum temperatures often lead to pollen sterility and low yield in high N status crops. The experiment combined 4 N rates (0, 75, 125, 250 kg N/ha) applied as urea just before permanent flood; 3 cultivars (Jarrah, early maturing; Amaroo and Doongara, midseason); 2 sowing dates (26 September, 31 October 1991); and 2 water depths (5, 20 cm) at the microspore stage. The early-sown crops and the later sown Jarrah crop encountered minimum air temperatures of 19¦C at the cold-sensitive microspore stage, compared with 15¦C for the other 2 later sown crops. Total dry matter production was little affected by either water depth or sowing date, but increased from 16 to 22 t/ha with N application. Shallow water depth and delayed sowing date affected yield through reduced harvest index. Grain yield response to N fertiliser was dependent on sowing date, water depth, and variety. For the early-sown crops grown in deep water, yields of Amaroo and Jarrah-increased from 7 to 13 t/ha with increasing N supply, while the yield response of Doongara plateaued at 9 t/ha. With shallow water, the yields of all varieties decreased from 7 to 3 t/ha with increasing N. For the later sowing date, Jarrah growing in deep water yielded up to 13 t/ha at high N, but yields of Amaroo and Doongara decreased from 7 to 2 t/ha with increasing N supply. For the later sowing date, yields of all varieties growing in shallow water decreased to <2 t/ha with applied N. In the deep water crops, developing microspores were submerged or partially submerged and so avoided low air minimum temperatures. In the early-sown crops, the microspore stage occurred during a period of relatively warm nights. Harvest index was successfully modelled using panicle temperature and N content at early pollen microspore. The experiment shows that high N applications can lead to high rice yields provided the microspores are protected from low temperatures by the use of deep water at the stage of microspore development. As a result, recommendations for N fertiliser application need to be adjusted for sowing date and expected water depth at early pollen microspore
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Claims 14
Claim · model-written summary
Rice dry matter rose from 16 to 22 t/ha with N application.
- Treatment
- N applicatione0
- Outcome
- Total dry matter productione0
- Direction
- increasede0
- Value
- 16 to 22 t/hae0
Not reportedTaxonComparator
Verbatim
e0“Total dry matter production was little affected by either water depth or sowing date, but increased from 16 to 22 t/ha with N application”
t0“rice crops”
Claim · model-written summary
Water depth and sowing date had little effect on rice dry matter.
- Taxon
- rice
Oryza sativat0 - Treatment
- water depth or sowing datee0
- Outcome
- Total dry matter productione0
- Direction
- little affectede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Total dry matter production was little affected by either water depth or sowing date, but increased from 16 to 22 t/ha with N application”
t0“rice crops”
Claim · model-written summary
Shallow water and delayed sowing reduced harvest index.
- Taxon
- riceOryza sativat0
- Treatment
- Shallow water depth and delayed sowing datee0
- Outcome
- harvest indexe0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Shallow water depth and delayed sowing date affected yield through reduced harvest index”
t0“rice crops”
Claim · model-written summary
Early-sown deep-water Amaroo yield rose from 7 to 13 t/ha with N.
- Taxon
- riceOryza sativat0
- Material
- Amarooe0
- Treatment
- increasing N supplye0
- Outcome
- yieldse0
- Direction
- increasede0
- Value
- 7 to 13 t/hae0
- Qualifier
- early-sown crops grown in deep watere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“For the early-sown crops grown in deep water, yields of Amaroo and Jarrah-increased from 7 to 13 t/ha with increasing N supply”
t0“rice crops”
Claim · model-written summary
Early-sown deep-water Jarrah yield rose from 7 to 13 t/ha with N.
- Taxon
- riceOryza sativat0
- Material
- Jarrahe0
- Treatment
- increasing N supplye0
- Outcome
- yieldse0
- Direction
- increasede0
- Value
- 7 to 13 t/hae0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“For the early-sown crops grown in deep water, yields of Amaroo and Jarrah-increased from 7 to 13 t/ha with increasing N supply”
t0“rice crops”
Claim · model-written summary
Early-sown deep-water Doongara yield plateaued at 9 t/ha.
Not reportedTreatmentComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“while the yield response of Doongara plateaued at 9 t/ha”
t0“rice crops”
Claim · model-written summary
In shallow water all rice varieties declined from 7 to 3 t/ha with N.
- Taxon
- riceOryza sativat0
- Treatment
- increasing Ne0
- Outcome
- yields of all varietiese0
- Direction
- decreasede0
- Value
- 7 to 3 t/hae0
- Qualifier
- shallow watere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“With shallow water, the yields of all varieties decreased from 7 to 3 t/ha with increasing N”
t0“rice crops”
Claim · model-written summary
Later-sown Jarrah in deep water yielded up to 13 t/ha at high N.
- Taxon
- riceOryza sativat0
- Material
- Jarrahe0
- Outcome
- yieldede0
- Value
- up to 13 t/hae0
- Qualifier
- later sowing datee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“For the later sowing date, Jarrah growing in deep water yielded up to 13 t/ha at high N”
t0“rice crops”
Claim · model-written summary
Later-sown Amaroo in deep water declined from 7 to 2 t/ha as N increased.
- Taxon
- riceOryza sativat0
- Material
- Amarooe0
- Treatment
- increasing N supplye0
- Outcome
- yieldse0
- Direction
- decreasede0
- Value
- 7 to 2 t/hae0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“but yields of Amaroo and Doongara decreased from 7 to 2 t/ha with increasing N supply”
t0“rice crops”
Claim · model-written summary
Later-sown Doongara in deep water declined from 7 to 2 t/ha as N increased.
- Taxon
- riceOryza sativat0
- Material
- Doongarae0
- Treatment
- increasing N supplye0
- Outcome
- yieldse0
- Direction
- decreasede0
- Value
- 7 to 2 t/hae0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“but yields of Amaroo and Doongara decreased from 7 to 2 t/ha with increasing N supply”
t0“rice crops”
Claim · model-written summary
Later-sown shallow-water varieties yielded under 2 t/ha with N.
- Taxon
- riceOryza sativat0
- Treatment
- applied Ne0
- Outcome
- yields of all varietiese0
- Direction
- decreasede0
- Value
- <2 t/hae0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“For the later sowing date, yields of all varieties growing in shallow water decreased to <2 t/ha with applied N”
t0“rice crops”
Claim · model-written summary
Deep water submerged developing microspores, avoiding low air temperature.
- Taxon
- riceOryza sativat0
- Organ / stage
- developing microsporese0
- Treatment
- deep watere0
- Outcome
- avoided low air minimum temperaturese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In the deep water crops, developing microspores were submerged or partially submerged and so avoided low air minimum temperatures”
t0“rice crops”
Claim · model-written summary
Harvest index was modeled using panicle temperature and N content.
- Taxon
- riceOryza sativat0
- Outcome
- Harvest indexe0
- Qualifier
- panicle temperature and N content at early pollen microsporee0
Not reportedComparatorValue
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Harvest index was successfully modelled using panicle temperature and N content at early pollen microspore”
t0“rice crops”
Claim · model-written summary
The authors recommend adjusting N fertilizer recommendations to sowing date and expected water depth.
- Taxon
- riceOryza sativat0
- Outcome
- N fertiliser application need to be adjusted for sowing date and expected water depth at early pollen microsporee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“recommendations for N fertiliser application need to be adjusted for sowing date and expected water depth at early pollen microspore”
t0“rice crops”
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