Abstract
"Haying-off" was studied by comparing wheat responses to applied nitrogen (N) at 3 sites in southern New South Wales, which differed in the amount and timing of rainfall during crop growth. At a site where the crops encountered little water deficit, dry grain yield increased from 607 g/m2 for a low-N control crop to 798 g/m2 for a high-N crop. At a site with severe terminal drought, dry grain yield decreased 24% from 374 g/m2 for the control, to 284 g/m2 for the highest N crop. At the third site, yields increased with small applications of N, whereas greater applications resulted in a negative yield response. At the 2 latter sites, the crops that showed decreased yield with applied N had clearly hayed-off. At all sites, irrespective of water status, N application resulted in increases in biomass at anthesis, spike density, kernels per spike, and kernel number. Kernel weight decreased in response to additional N at all sites, but most markedly at the haying-off sites, where it decreased by up to 38%. Harvest index increased in response to N at the high-rainfall site, but decreased in crops that hayed-off. Grain protein increased in response to N at all sites, with a range from 9% to 18% at the haying-off sites. The apparent retranslocation of assimilates to grain contributed 37-39% of grain yield (depending on N supply) at the high-rainfall site, compared with 75-100% at the haying-off sites. In contrast, when apparent retranslocation was expressed in relation to biomass at anthesis, it remained relatively constant, amounting to 23-26% at the high-rainfall site and 24-28% when crops hayed-off. By anthesis, high-N crops extracted more soil water than the low-N crops. By maturity the most severely hayed-off crop had extracted 10 mm less soil water than a low-N crop, but at the high rainfall site the high-N crops extracted 20 mm more soil water than the control crops. The weather conditions between anthesis and physiological maturity were relatively mild, with no daily maximum temperatures above 30ºC and no sudden increases in evaporative demand. Thus, there appeared to be 3 processes leading to haying-off. Firstly, the results confirm previous studies showing that haying-off was associated with reduced post-anthesis assimilation in response to a lack of soil water. The water deffcit was due to vigorous vegetative growth stimulated by a high level of soil N and was not associated with heat shocks or sudden increases in evaporation. Secondly, the most severely hayed-off crop failed to extract soil water fully, leading to a further reduction in post-anthesis assimilation. Thirdly, there was inadequate apparent retranslocation of pre-anthesis reserves to compensate for the lack of post-anthesis assimilation.
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Claims 20
Claim · model-written summary
At the site with little water deficit, high nitrogen increased dry grain yield from 607 to 798 g/m2.
- Taxon
- wheat
Triticum aestivumt0 - Treatment
- high-N crope0
- Outcome
- dry grain yielde0
- Direction
- increasede0
- Value
- 798 g/m2e0
- Qualifier
- 607 g/m2e0
- Comparator
- low-N control crope0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At a site where the crops encountered little water deficit, dry grain yield increased from 607 g/m2 for a low-N control crop to 798 g/m2 for a high-N crop.”
t0“wheat”
Claim · model-written summary
Under severe terminal drought, highest nitrogen decreased grain yield 24% from 374 to 284 g/m2.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- highest N crope0
- Outcome
- dry grain yielde0
- Direction
- decreasede0
- Value
- 24%e0
- Qualifier
- severe terminal droughte0
- Comparator
- controle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At a site with severe terminal drought, dry grain yield decreased 24% from 374 g/m2 for the control, to 284 g/m2 for the highest N crop.”
t0“wheat”
Claim · model-written summary
At the third site, small nitrogen applications increased yield.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- small applications of Ne0
- Outcome
- yieldse0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At the third site, yields increased with small applications of N”
t0“wheat”
Claim · model-written summary
At the third site, greater nitrogen applications reduced yield.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- greater applicationse0
- Outcome
- yield responsee0
- Direction
- negativee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“greater applications resulted in a negative yield response.”
t0“wheat”
Claim · model-written summary
Nitrogen increased biomass at anthesis at all sites.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- N applicatione0
- Outcome
- biomass at anthesise0
- Direction
- increasese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At all sites, irrespective of water status, N application resulted in increases in biomass at anthesis, spike density, kernels per spike, and kernel number.”
t0“wheat”
Claim · model-written summary
Nitrogen increased spike density, kernels per spike, and kernel number at all sites.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- N applicatione0
- Outcome
- spike density, kernels per spike, and kernel numbere0
- Direction
- increasese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At all sites, irrespective of water status, N application resulted in increases in biomass at anthesis, spike density, kernels per spike, and kernel number.”
t0“wheat”
Claim · model-written summary
Additional nitrogen decreased kernel weight at all sites, by up to 38% at haying-off sites.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- additional Ne0
- Outcome
- Kernel weighte0
- Direction
- decreasede0
- Value
- up to 38%e0
- Qualifier
- haying-off sitese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Kernel weight decreased in response to additional N at all sites, but most markedly at the haying-off sites, where it decreased by up to 38%.”
t0“wheat”
Claim · model-written summary
Nitrogen increased harvest index at the high-rainfall site.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- Ne0
- Outcome
- Harvest indexe0
- Direction
- increasede0
- Setting
- high-rainfall sitee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Harvest index increased in response to N at the high-rainfall site”
t0“wheat”
Claim · model-written summary
Harvest index decreased in crops that hayed-off.
- Taxon
- wheatTriticum aestivumt0
- Outcome
- Harvest indexe0
- Direction
- decreasede0
- Qualifier
- crops that hayed-offe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Harvest index increased in response to N at the high-rainfall site, but decreased in crops that hayed-off.”
t0“wheat”
Claim · model-written summary
Nitrogen increased grain protein at all sites, reaching 9% to 18% at haying-off sites.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Grain protein increased in response to N at all sites, with a range from 9% to 18% at the haying-off sites.”
t0“wheat”
Claim · model-written summary
Apparent retranslocation contributed 37-39% of grain yield at the high-rainfall site.
- Taxon
- wheatTriticum aestivumt0
- Outcome
- apparent retranslocation of assimilates to graine0
- Value
- 37-39%e0
- Setting
- high-rainfall sitee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The apparent retranslocation of assimilates to grain contributed 37-39% of grain yield (depending on N supply) at the high-rainfall site”
t0“wheat”
Claim · model-written summary
Apparent retranslocation contributed 75-100% of grain yield at haying-off sites.
- Taxon
- wheatTriticum aestivumt0
- Outcome
- apparent retranslocatione0
- Value
- 75-100%e0
- Setting
- haying-off sitese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The apparent retranslocation of assimilates to grain contributed 37-39% of grain yield (depending on N supply) at the high-rainfall site, compared with 75-100% at the haying-off sites.”
t0“wheat”
Claim · model-written summary
Relative to anthesis biomass, apparent retranslocation was 23-26% at the high-rainfall site.
- Taxon
- wheatTriticum aestivumt0
- Outcome
- apparent retranslocatione0
- Value
- 23-26%e0
- Setting
- high-rainfall sitee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“when apparent retranslocation was expressed in relation to biomass at anthesis, it remained relatively constant, amounting to 23-26% at the high-rainfall site”
t0“wheat”
Claim · model-written summary
Relative to anthesis biomass, apparent retranslocation was 24-28% in haying-off crops.
- Taxon
- wheatTriticum aestivumt0
- Outcome
- apparent retranslocatione0
- Value
- 24-28%e0
- Qualifier
- crops hayed-offe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“when apparent retranslocation was expressed in relation to biomass at anthesis, it remained relatively constant, amounting to 23-26% at the high-rainfall site and 24-28% when crops hayed-off.”
t0“wheat”
Claim · model-written summary
By anthesis, high-nitrogen crops extracted more soil water than low-nitrogen crops.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- high-N cropse0
- Outcome
- soil watere0
- Direction
- moree0
- Comparator
- low-N cropse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“By anthesis, high-N crops extracted more soil water than the low-N crops.”
t0“wheat”
Claim · model-written summary
By maturity, the most severely hayed-off crop extracted 10 mm less soil water than a low-nitrogen crop.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- most severely hayed-off crope0
- Outcome
- soil watere0
- Direction
- lesse0
- Value
- 10 mme0
- Comparator
- low-N crope0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“By maturity the most severely hayed-off crop had extracted 10 mm less soil water than a low-N crop”
t0“wheat”
Claim · model-written summary
At the high rainfall site, high-nitrogen crops extracted 20 mm more soil water than controls.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- high-N cropse0
- Outcome
- soil watere0
- Direction
- moree0
- Value
- 20 mme0
- Comparator
- control cropse0
- Setting
- high rainfall sitee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“at the high rainfall site the high-N crops extracted 20 mm more soil water than the control crops.”
t0“wheat”
Claim · model-written summary
Haying-off was associated with reduced post-anthesis assimilation due to lack of soil water.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- haying-offe0
- Outcome
- post-anthesis assimilatione0
- Direction
- reducede0
- Qualifier
- lack of soil watere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“haying-off was associated with reduced post-anthesis assimilation in response to a lack of soil water.”
t0“wheat”
Claim · model-written summary
Vigorous vegetative growth stimulated by high soil nitrogen caused the water deficit.
- Taxon
- wheatTriticum aestivumt0
- Outcome
- water deffcite0
- Qualifier
- vigorous vegetative growth stimulated by a high level of soil Ne0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The water deffcit was due to vigorous vegetative growth stimulated by a high level of soil N”
t0“wheat”
Claim · model-written summary
Inadequate pre-anthesis reserve retranslocation failed to compensate for lost post-anthesis assimilation.
- Taxon
- wheatTriticum aestivumt0
- Outcome
- lack of post-anthesis assimilatione0
- Qualifier
- inadequate apparent retranslocation of pre-anthesis reservese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“there was inadequate apparent retranslocation of pre-anthesis reserves to compensate for the lack of post-anthesis assimilation.”
t0“wheat”
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