Abstract
In parts of peninsular India, sorghum ( Sorghum bicolor L.) is grown during the dry season using water stored in the root zone. The optimum application of nitrogen is difficult to assess because no comprehensive model exists for the interaction of water and N. To explore this system as a basis for modelling in the first instance and ultimately for better management, sorghum (cv. SPH–280) was grown in the post-rainy season at ICRISAT (Andhra Pradesh, India) with and without irrigation and at six rates of nitrogen from zero to 150 kg/ha applied before sowing. The biomass of top components was measured weekly and of roots every 2 weeks. Interception of solar radiation was monitored continuously in all treatments. Leaf expansion was strongly influenced both by water and by N, whereas specific leaf area was almost independent of treatment. In the irrigated treatment, the Biomass Radiation Coefficient ( e ) for the main growth period was almost independent of N application at 1·3–1·4 g/MJ and was also independent of leaf N. In consequence, the main source of differences in yield was a decrease in radiation interception with decreasing N. In contrast, without irrigation, biomass, yield, e and leaf N were all maximal at 60 kg/ha N. At 33 days after emergence (DAE), root mass was almost independent of N whether water had been applied or not, but was somewhat smaller with irrigation. Later, root, leaf, and panicle mass all responded to N and to water, but stem mass was unresponsive to N with irrigation. There was evidence of translocation from stem to grain in most treatments. With irrigation, a maximum grain yield of 4·8 t/ha was obtained at 150 kg/ha N and without irrigation the maximum was 3·2 t/ha at 90 kg/ha.
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Claims 16
Claim · model-written summary
Leaf expansion was strongly influenced by water and nitrogen.
SorghumNot reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaf expansion was strongly influenced both by water and by N”
t0“sorghum”
Claim · model-written summary
Specific leaf area was almost independent of treatment.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“specific leaf area was almost independent of treatment”
t0“sorghum”
Claim · model-written summary
Under irrigation, the biomass radiation coefficient was nearly independent of nitrogen application and measured 1·3–1·4 g/MJ.
- Treatment
- N applicatione0
- Outcome
- Biomass Radiation Coefficiente0
- Direction
- almost independente0
- Value
- 1·3–1·4 g/MJe0
- Qualifier
- In the irrigated treatmente0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In the irrigated treatment, the Biomass Radiation Coefficient ( e ) for the main growth period was almost independent of N application at 1·3–1·4 g/MJ”
t0“sorghum”
Claim · model-written summary
Under irrigation, the biomass radiation coefficient was independent of leaf nitrogen.
Not reportedCompound
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“was also independent of leaf N”
e1“Biomass Radiation Coefficient ( e )”
t0“sorghum”
Claim · model-written summary
Under irrigation, radiation interception decreased as nitrogen declined and accounted for the main yield differences.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the main source of differences in yield was a decrease in radiation interception with decreasing N”
t0“sorghum”
Claim · model-written summary
Without irrigation, biomass was maximal at 60 kg/ha nitrogen.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“without irrigation, biomass, yield, e and leaf N were all maximal at 60 kg/ha N”
t0“sorghum”
Claim · model-written summary
Without irrigation, yield was maximal at 60 kg/ha nitrogen in the reported joint result.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“without irrigation, biomass, yield, e and leaf N were all maximal at 60 kg/ha N”
t0“sorghum”
Claim · model-written summary
Without irrigation, the biomass radiation coefficient was maximal at 60 kg/ha nitrogen.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“without irrigation, biomass, yield, e and leaf N were all maximal at 60 kg/ha N”
e1“Biomass Radiation Coefficient ( e )”
t0“sorghum”
Claim · model-written summary
Without irrigation, leaf nitrogen was maximal at 60 kg/ha nitrogen.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“without irrigation, biomass, yield, e and leaf N were all maximal at 60 kg/ha N”
t0“sorghum”
Claim · model-written summary
At 33 days after emergence, root mass was almost independent of nitrogen under either water treatment.
- Treatment
- Ne0
- Outcome
- root masse0
- Direction
- almost independente0
- Qualifier
- At 33 days after emergence (DAE)e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At 33 days after emergence (DAE), root mass was almost independent of N whether water had been applied or not”
t0“sorghum”
Claim · model-written summary
At 33 days after emergence, root mass was somewhat smaller with irrigation.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“root mass was almost independent of N whether water had been applied or not, but was somewhat smaller with irrigation”
t0“sorghum”
Claim · model-written summary
Later root, leaf and panicle mass responded to nitrogen and water.
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Later, root, leaf, and panicle mass all responded to N and to water”
t0“sorghum”
Claim · model-written summary
With irrigation, stem mass was unresponsive to nitrogen.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“stem mass was unresponsive to N with irrigation”
t0“sorghum”
Claim · model-written summary
Stem to grain translocation was evident in most treatments.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“There was evidence of translocation from stem to grain in most treatments”
t0“sorghum”
Claim · model-written summary
Irrigated sorghum achieved maximum grain yield of 4·8 t/ha at 150 kg/ha nitrogen.
- Treatment
- 150 kg/ha Ne0
- Outcome
- grain yielde0
- Direction
- maximume0
- Value
- 4·8 t/hae0
- Qualifier
- With irrigatione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“With irrigation, a maximum grain yield of 4·8 t/ha was obtained at 150 kg/ha N”
t0“sorghum”
Claim · model-written summary
Without irrigation, maximum grain yield was 3·2 t/ha at 90 kg/ha nitrogen.
- Treatment
- 90 kg/hae0
- Outcome
- grain yielde1
- Direction
- maximume0
- Value
- 3·2 t/hae0
- Qualifier
- without irrigatione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“without irrigation the maximum was 3·2 t/ha at 90 kg/ha”
e1“grain yield”
t0“sorghum”
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