Abstract
The dynamics of stomatal response and canopy apparent photosynthesis in grain sorghum [ Sorghum bicolor (L.) Moench] were studied throughout a growing season in relation to water stress. Treatments received irrigation weekly at 100% soil water deficit replacement or no irrigation on the extremes of a sprinkler irrigation gradient conducted on a fine sand (Typic Ustipsamment). Stomatal resistance was sensitive to small reductions in leaf water potential during the vegetative period. During the reproductive period the stomata became nearly insensitive to leaf water potential and remained open at low leaf water potentials. Maximum midday deficits in leaf water potential due to drought stress were in the range of 0.1 to 0.2 MPa during the vegetative period, 0.3 to 0.4 MPa during the reproductive period and exceeded 0.5 MPa during grain filling. Stored soil water was steadily depleted in the unirrigated treatment. Water stress reduced grain and dry matter yields 36 and 37% respectively. Photosynthesis per unit leaf area was not decreased by water stress during the reproductive and grain filling periods. The rate of canopy apparent photosynthesis was reduced by 14 to 26% but this was solely a result of less leaf area in the stressed treatment. Canopy evapotranspiration was greatly reduced in the water stressed treatment but evapotranspiration per unit leaf area was apparently unaffected by water stress during all or a large portion of the post‐vegetative period. Reduction in leaf area was an important mechanism for transpiration control under drought stress during the entire reproductive and grain filling periods. Stomatal resistance was not a major transpiration control mechanism. In the absence of increased stomatal resistance both transpiration and photosynthesis per unit leaf area were not reduced during the continually intensifying seasonal drought.
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Claims 15
Claim · model-written summary
Vegetative stomatal resistance was sensitive to small leaf water potential reductions.
- Taxon
- grain sorghum
Sorghum bicolort0 - Organ / stage
- vegetative periode0
- Outcome
- Stomatal resistancee0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Stomatal resistance was sensitive to small reductions in leaf water potential during the vegetative period”
t0“Grain Sorghum”
Claim · model-written summary
Reproductive stomata were nearly insensitive to leaf water potential.
- Taxon
- grain sorghumSorghum bicolort0
- Organ / stage
- reproductive periode0
- Outcome
- stomata became nearly insensitive to leaf water potentiale0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“During the reproductive period the stomata became nearly insensitive to leaf water potential and remained open at low leaf water potentials”
t0“Grain Sorghum”
Claim · model-written summary
Maximum midday leaf water potential deficit was 0.1 to 0.2 MPa in vegetative growth.
- Taxon
- grain sorghumSorghum bicolort0
- Organ / stage
- vegetative periode0
- Outcome
- Maximum midday deficits in leaf water potentiale1
- Value
- 0.1 to 0.2 MPae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“0.1 to 0.2 MPa during the vegetative period”
t0“Grain Sorghum”
t1“Changes in Grain Sorghum Stomatal and Photosynthetic Response to Moisture Stress across Growth Stages1”
e1“Maximum midday deficits in leaf water potential due to drought stress were in the range of 0.1 to 0.2 MPa during the vegetative period, 0.3 to 0.4 MPa during the reproductive period and exceeded 0.5 MPa during grain filling”
Claim · model-written summary
Maximum midday leaf water potential deficit was 0.3 to 0.4 MPa in reproduction.
- Taxon
- grain sorghumSorghum bicolort0
- Organ / stage
- reproductive periode0
- Outcome
- Maximum midday deficits in leaf water potentiale1
- Value
- 0.3 to 0.4 MPae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“0.3 to 0.4 MPa during the reproductive period”
t0“Grain Sorghum”
t1“Changes in Grain Sorghum Stomatal and Photosynthetic Response to Moisture Stress across Growth Stages1”
e1“Maximum midday deficits in leaf water potential due to drought stress were in the range of 0.1 to 0.2 MPa during the vegetative period, 0.3 to 0.4 MPa during the reproductive period and exceeded 0.5 MPa during grain filling”
Claim · model-written summary
Maximum midday leaf water potential deficit exceeded 0.5 MPa during filling.
- Taxon
- grain sorghumSorghum bicolort0
- Organ / stage
- grain fillinge0
- Outcome
- Maximum midday deficits in leaf water potentiale1
- Direction
- exceedede0
- Value
- 0.5 MPae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“exceeded 0.5 MPa during grain filling”
t0“Grain Sorghum”
t1“Changes in Grain Sorghum Stomatal and Photosynthetic Response to Moisture Stress across Growth Stages1”
e1“Maximum midday deficits in leaf water potential due to drought stress were in the range of 0.1 to 0.2 MPa during the vegetative period, 0.3 to 0.4 MPa during the reproductive period and exceeded 0.5 MPa during grain filling”
Claim · model-written summary
Unirrigated soil water was steadily depleted.
- Taxon
- grain sorghumSorghum bicolort0
- Treatment
- unirrigated treatmente0
- Outcome
- Stored soil watere0
- Direction
- depletede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Stored soil water was steadily depleted in the unirrigated treatment”
t0“Grain Sorghum”
Claim · model-written summary
Water stress cut grain yield by 36%.
- Taxon
- grain sorghumSorghum bicolort0
- Treatment
- Water stresse0
- Outcome
- graine0
- Direction
- reducede0
- Value
- 36 and 37%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Water stress reduced grain and dry matter yields 36 and 37% respectively”
t0“Grain Sorghum”
Claim · model-written summary
Water stress cut dry matter yield by 37%.
- Taxon
- grain sorghumSorghum bicolort0
- Treatment
- Water stresse0
- Outcome
- dry matter yieldse0
- Direction
- reducede0
- Value
- 37%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Water stress reduced grain and dry matter yields 36 and 37% respectively”
t0“Grain Sorghum”
Claim · model-written summary
Photosynthesis per leaf area was not decreased by water stress in reproduction and filling.
- Taxon
- grain sorghumSorghum bicolort0
- Treatment
- water stresse0
- Outcome
- Photosynthesis per unit leaf areae0
- Direction
- not decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Photosynthesis per unit leaf area was not decreased by water stress during the reproductive and grain filling periods”
t0“Grain Sorghum”
Claim · model-written summary
Canopy apparent photosynthesis fell by 14 to 26%.
- Taxon
- grain sorghumSorghum bicolort0
- Treatment
- water stresse1
- Outcome
- rate of canopy apparent photosynthesise0
- Direction
- reducede0
- Value
- 14 to 26%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The rate of canopy apparent photosynthesis was reduced by 14 to 26%”
t0“Grain Sorghum”
e1“water stress during the reproductive and grain filling periods”
Claim · model-written summary
Reduced leaf area alone explained lower canopy photosynthesis.
- Taxon
- grain sorghumSorghum bicolort0
- Organ / stage
- leaf areae0
- Outcome
- canopy apparent photosynthesise1
- Qualifier
- less leaf areae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“this was solely a result of less leaf area in the stressed treatment”
t0“Grain Sorghum”
t1“Changes in Grain Sorghum Stomatal and Photosynthetic Response to Moisture Stress across Growth Stages1”
e1“The rate of canopy apparent photosynthesis was reduced by 14 to 26%”
Claim · model-written summary
Canopy evapotranspiration was greatly reduced under water stress.
- Taxon
- grain sorghumSorghum bicolort0
- Treatment
- water stressed treatmente0
- Outcome
- Canopy evapotranspiratione0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Canopy evapotranspiration was greatly reduced in the water stressed treatment”
t0“Grain Sorghum”
Claim · model-written summary
Evapotranspiration per leaf area was apparently unaffected after vegetative growth.
- Taxon
- grain sorghumSorghum bicolort0
- Treatment
- water stresse0
- Outcome
- evapotranspiration per unit leaf areae0
- Direction
- unaffectede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“evapotranspiration per unit leaf area was apparently unaffected by water stress during all or a large portion of the post‐vegetative period”
t0“Grain Sorghum”
Claim · model-written summary
Leaf area reduction was important to drought transpiration control.
- Taxon
- grain sorghumSorghum bicolort0
- Organ / stage
- leaf areae0
- Outcome
- transpiration controle0
- Qualifier
- Reduction in leaf areae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Reduction in leaf area was an important mechanism for transpiration control under drought stress during the entire reproductive and grain filling periods”
t0“Grain Sorghum”
Claim · model-written summary
Stomatal resistance was not a major transpiration control mechanism.
- Taxon
- grain sorghumSorghum bicolort0
- Outcome
- transpiration controle0
- Qualifier
- Stomatal resistancee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Stomatal resistance was not a major transpiration control mechanism”
t0“Grain Sorghum”
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