Abstract
SUMMARY The possible interacting effects of shading and N supply on number of grains of Triticum aestivum L. (cv. Buck Ñandú) were investigated at Balcarce, Argentina, during the 1988/89 and 1989/90 growing seasons. Shading was imposed from c. 13 days before anthesis to 6 days after, and four rates of N fertilization were supplied within each shading treatment around the date of terminal spikelet formation. Water and other nutrients were not limiting. Total grain yield was strongly correlated with grain number/m 2 , regardless of shading or N supply. At the highest N rates, grain number and dry weight of spikes at anthesis were linearly related to a photothermal quotient, i.e. the ratio of intercepted photosynthetically active radiation (PAR) to mean temperature minus 4·5 °C, during the period from 20 days before anthesis to 10 days after. The response of grain number to the photothermal quotient was interpreted in terms of the supply of assimilates to the spike at anthesis, which determined flower survival. The response of dry weight of spikes to photothermal quotient was interpreted in terms of crop growth rate since there was a linear relationship between crop growth rate and intercepted radiation. The lowest N rates reduced the number of grains/m 2 , at any given photothermal quotient. Since the reduction in grain number also occurred at any given dry weight of spikes, it cannot be explained by a reduced supply of assimilates to the spikes. Grain number responded directly to the supply of N to the spike, probably through the survival of differentiated flowers. The relationship between spike growth rate and crop growth rate was not affected by N supply. Crop growth rate was reduced by reduced N supply, because less radiation was intercepted and because radiation-use efficiency was lowered. These results indicate that current models for determining yield and number of grains/m 2 , based on crop growth, are not adequate when N is deficient.
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Claims 10
Claim · model-written summary
Total grain yield was strongly correlated with grain number per square metre, regardless of shading or N supply.
- Taxon
- Triticum aestivum L.
Triticum aestivume0 - Material
- Buck Ñandúe0
- Treatment
- shading or N supplye1
- Outcome
- Total grain yielde1
- Setting
- Balcarce, Argentinae0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Triticum aestivum L. (cv. Buck Ñandú) were investigated at Balcarce, Argentina, during the 1988/89 and 1989/90 growing seasons”
e1“Total grain yield was strongly correlated with grain number/m 2 , regardless of shading or N supply”
Claim · model-written summary
At the highest N rates, grain number and spike dry weight at anthesis were linearly related to the photothermal quotient.
- Taxon
- Triticum aestivum L.Triticum aestivume0
- Material
- Buck Ñandúe0
- Treatment
- highest N ratese1
- Outcome
- grain number and dry weight of spikes at anthesise1
- Qualifier
- photothermal quotiente1
- Setting
- Balcarce, Argentinae0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Triticum aestivum L. (cv. Buck Ñandú) were investigated at Balcarce, Argentina, during the 1988/89 and 1989/90 growing seasons”
e1“At the highest N rates, grain number and dry weight of spikes at anthesis were linearly related to a photothermal quotient”
Claim · model-written summary
The grain number response to the photothermal quotient is interpreted as driven by assimilate supply to the spike, which determines flower survival.
- Taxon
- Triticum aestivum L.Triticum aestivume0
- Material
- Buck Ñandúe0
- Outcome
- grain numbere1
- Qualifier
- supply of assimilates to the spike at anthesis, which determined flower survivale1
- Setting
- Balcarce, Argentinae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Triticum aestivum L. (cv. Buck Ñandú) were investigated at Balcarce, Argentina, during the 1988/89 and 1989/90 growing seasons”
e1“The response of grain number to the photothermal quotient was interpreted in terms of the supply of assimilates to the spike at anthesis, which determined flower survival”
Claim · model-written summary
The spike dry weight response to the photothermal quotient is interpreted as driven by crop growth rate.
- Taxon
- Triticum aestivum L.Triticum aestivume0
- Material
- Buck Ñandúe0
- Outcome
- dry weight of spikese1
- Qualifier
- crop growth ratee1
- Setting
- Balcarce, Argentinae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Triticum aestivum L. (cv. Buck Ñandú) were investigated at Balcarce, Argentina, during the 1988/89 and 1989/90 growing seasons”
e1“The response of dry weight of spikes to photothermal quotient was interpreted in terms of crop growth rate since there was a linear relationship between crop growth rate and intercepted radiation”
Claim · model-written summary
The reduction in grain number at a given spike dry weight is interpreted as not explained by reduced assimilate supply.
- Taxon
- Triticum aestivum L.Triticum aestivume0
- Material
- Buck Ñandúe0
- Outcome
- reduction in grain numbere1
- Qualifier
- cannot be explained by a reduced supply of assimilates to the spikese1
- Setting
- Balcarce, Argentinae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Triticum aestivum L. (cv. Buck Ñandú) were investigated at Balcarce, Argentina, during the 1988/89 and 1989/90 growing seasons”
e1“Since the reduction in grain number also occurred at any given dry weight of spikes, it cannot be explained by a reduced supply of assimilates to the spikes”
Claim · model-written summary
The lowest N rates reduced grain number per square metre at any given photothermal quotient.
- Taxon
- Triticum aestivum L.Triticum aestivume0
- Material
- Buck Ñandúe0
- Treatment
- lowest N ratese1
- Outcome
- number of grains/m 2e1
- Direction
- reducede1
- Qualifier
- at any given photothermal quotiente1
- Setting
- Balcarce, Argentinae0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Triticum aestivum L. (cv. Buck Ñandú) were investigated at Balcarce, Argentina, during the 1988/89 and 1989/90 growing seasons”
e1“The lowest N rates reduced the number of grains/m 2 , at any given photothermal quotient”
Claim · model-written summary
Grain number responds directly to N supply to the spike, probably through survival of differentiated flowers.
- Taxon
- Triticum aestivum L.Triticum aestivume0
- Material
- Buck Ñandúe0
- Treatment
- supply of N to the spikee1
- Outcome
- grain numbere1
- Qualifier
- through the survival of differentiated flowerse1
- Setting
- Balcarce, Argentinae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Triticum aestivum L. (cv. Buck Ñandú) were investigated at Balcarce, Argentina, during the 1988/89 and 1989/90 growing seasons”
e1“Grain number responded directly to the supply of N to the spike, probably through the survival of differentiated flowers”
Claim · model-written summary
The relationship between spike growth rate and crop growth rate was not affected by N supply.
- Taxon
- Triticum aestivum L.Triticum aestivume0
- Material
- Buck Ñandúe0
- Treatment
- N supplye1
- Outcome
- relationship between spike growth rate and crop growth ratee1
- Direction
- not affectede1
- Setting
- Balcarce, Argentinae0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Triticum aestivum L. (cv. Buck Ñandú) were investigated at Balcarce, Argentina, during the 1988/89 and 1989/90 growing seasons”
e1“The relationship between spike growth rate and crop growth rate was not affected by N supply”
Claim · model-written summary
Reduced N supply reduced crop growth rate, through less intercepted radiation.
- Taxon
- Triticum aestivum L.Triticum aestivume0
- Material
- Buck Ñandúe0
- Treatment
- reduced N supplye1
- Outcome
- Crop growth ratee1
- Direction
- reducede1
- Qualifier
- less radiation was interceptede1
- Setting
- Balcarce, Argentinae0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Triticum aestivum L. (cv. Buck Ñandú) were investigated at Balcarce, Argentina, during the 1988/89 and 1989/90 growing seasons”
e1“Crop growth rate was reduced by reduced N supply, because less radiation was intercepted and because radiation-use efficiency was lowered”
Claim · model-written summary
Current crop models for yield and grain number are not adequate when N is deficient.
- Taxon
- Triticum aestivum L.Triticum aestivume0
- Material
- Buck Ñandúe0
- Outcome
- models for determining yield and number of grains/m 2e1
- Qualifier
- not adequate when N is deficiente1
- Setting
- Balcarce, Argentinae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Triticum aestivum L. (cv. Buck Ñandú) were investigated at Balcarce, Argentina, during the 1988/89 and 1989/90 growing seasons”
e1“These results indicate that current models for determining yield and number of grains/m 2 , based on crop growth, are not adequate when N is deficient”
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