Abstract
1. The water economy of plants was studied in water-cultured tobacco plants reported in a previous paper3) by means of abrupt changing of culture solution level.2. Equations 2 and 3 were formulated quantitatively to elucidate the water economy of plants, and they could clarify the main effective factors as follows: a) The active root/leaf area ratio (the ratio of mg. fresh weight of root active in water absorption Cw to leaf area of plant in sq. cm. F), which well indicated the grading of a water level lowering, had the direct effect on the water economy of an entire plant, and remained almost constant under normal conditions of the plant growth. b) The transpiration rate kept a constant value of 5-6mg./sq.cm./hr./cm. Hg in the range of 4.5-.7 of the Cw/F ratio, but below 4.5 of Cw/F, the transpiration rate decreased linearly with the depression of the active root/leaf area ratio. c) The water amount absorbed through 1mg. of submerged fresh roots was assessed to be 1mg./hr. under the given conditions (25°, ca. 1cm. Hg of saturation deficit). d) The water amount in leaves was expressed on leaf area basis, and designated in terms of leaf water index (LWI, mg. H2O/sq. cm.). The index represents the water condition of leaves more clearly than the water content expressed on dry weight basis does.2) By substituting the above factors in Equation 3, the leaf water deficit of the tobacco leaves accompanied with lowering the culture solution level was calculated. The trend of the calculated curve was fairly similar to the observed. This may prove that the obtained equations will be applicable to the general discussion of water enocomy of plants with variously developed root systems.
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Claims 7
Claim · model-written summary
Equations 2 and 3 clarified the main factors of tobacco water economy.
- Taxon
- Tobacco Plant
Nicotiana tabacumt0 - Outcome
- main effective factorse0
- Value
- Equations 2 and 3e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Equations 2 and 3 were formulated quantitatively to elucidate the water economy of plants, and they could clarify the main effective factors as follows:”
t0“Tobacco Plant”
Claim · model-written summary
The active root to leaf area ratio directly affected whole-plant water economy and remained nearly constant during normal growth.
- Taxon
- Tobacco PlantNicotiana tabacumt0
- Organ / stage
- roote0
- Outcome
- water economy of an entire plante0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The active root/leaf area ratio (the ratio of mg. fresh weight of root active in water absorption Cw to leaf area of plant in sq. cm. F), which well indicated the grading of a water level lowering, had the direct effect on the water economy of an entire plant, and remained almost constant under normal conditions of the plant growth.”
t0“Tobacco Plant”
Claim · model-written summary
Transpiration was constant at 5-6mg./sq.cm./hr./cm. Hg in the reported ratio range.
- Taxon
- Tobacco PlantNicotiana tabacumt0
- Outcome
- transpiration ratee0
- Direction
- kept a constant valuee0
- Value
- 5-6mg./sq.cm./hr./cm. Hge0
- Qualifier
- in the range of 4.5-.7 of the Cw/F ratioe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The transpiration rate kept a constant value of 5-6mg./sq.cm./hr./cm. Hg in the range of 4.5-.7 of the Cw/F ratio”
t0“Tobacco Plant”
Claim · model-written summary
Below a Cw/F ratio of 4.5, transpiration declined linearly with the active root to leaf area ratio.
- Taxon
- Tobacco PlantNicotiana tabacumt0
- Organ / stage
- roote0
- Outcome
- transpiration ratee0
- Direction
- decreasede0
- Qualifier
- below 4.5 of Cw/Fe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“below 4.5 of Cw/F, the transpiration rate decreased linearly with the depression of the active root/leaf area ratio.”
t0“Tobacco Plant”
Claim · model-written summary
Submerged fresh roots absorbed 1mg./hr. per 1mg. under the given conditions.
- Taxon
- Tobacco PlantNicotiana tabacumt0
- Organ / stage
- submerged fresh rootse0
- Outcome
- water amount absorbede0
- Value
- 1mg./hr.e0
- Qualifier
- 25°, ca. 1cm. Hg of saturation deficite0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The water amount absorbed through 1mg. of submerged fresh roots was assessed to be 1mg./hr. under the given conditions (25°, ca. 1cm. Hg of saturation deficit).”
t0“Tobacco Plant”
Claim · model-written summary
Leaf water index represented leaf water status more clearly than dry-weight water content.
- Taxon
- Tobacco PlantNicotiana tabacumt0
- Outcome
- water condition of leavese0
- Direction
- more clearlye0
- Comparator
- water content expressed on dry weight basise0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The index represents the water condition of leaves more clearly than the water content expressed on dry weight basis does.”
t0“Tobacco Plant”
Claim · model-written summary
The calculated leaf water deficit curve was fairly similar to observations.
- Taxon
- Tobacco PlantNicotiana tabacumt0
- Outcome
- trend of the calculated curvee0
- Direction
- fairly similare0
- Comparator
- the observede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The trend of the calculated curve was fairly similar to the observed.”
t0“Tobacco Plant”