Abstract
AbstractThe transpiration of a leaf can be described by the Penman-Monteith equation as the sum of two terms, one giving the transpiration driven by the absorption of radiation and the other by diffusion to the unsaturated ambient air. Both terms for this relation may readily be calculated by a computer program. A model is developed to predict the energy absorbed from the incident radiation flux by a canopy and by young developing leaves for tomato. Solar radiation has a greater effect on the upper parts of the plants because they are exposed to the full incident light plus that reflected from below whereas lower parts of the canopy are progressively shaded. Humidity tends to act over the complete canopy. Hence a greater change in humidity would be required to maintain transpiration from the upper leaves at reduced irradiance than from the lower ones. The accumulation rate of calcium would be closely linked to the transpiration. Since calcium will not, in general, be redistributed subsequently, the model can explain the deficiency in calcium levels in leaves that develop during periods of low solar intensity and high humidity. It provides a basis for compensating by lowering the humidity of the environment by use of an evaporative equivalence factor relating vapour pressure deficit to radiation incident on the crop. It is estimated that the rate of transpiration should be at least 2.2 times the rate of leaf expansion to prevent any appreciable yield loss from calcium deficiency and that a total of 8.7 MJ m-2 d_l of radiation and of radiation equivalent would be required, 0.04 kPa vapour pressure deficit compensation per MJ m_2 d_1 shortfall.
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Claims 8
Claim · model-written summary
Solar radiation has a greater effect on the upper parts of tomato plants than on progressively shaded lower canopy parts.
- Taxon
- tomato
Solanum lycopersicumt0 - Organ / stage
- upper parts of the plantse1
- Treatment
- Solar radiatione1
- Outcome
- effect on the upper parts of the plantse1
- Direction
- greatere1
- Comparator
- lower parts of the canopye1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“tomato leaves”
e1“Solar radiation has a greater effect on the upper parts of the plants because they are exposed to the full incident light plus that reflected from below whereas lower parts of the canopy are progressively shaded”
Claim · model-written summary
A greater change in humidity would be needed to maintain upper-leaf transpiration at reduced irradiance than lower-leaf transpiration.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- reduced irradiancee1
- Outcome
- transpiration from the upper leavese1
- Direction
- greatere1
- Comparator
- the lower onese1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“tomato leaves”
e1“Hence a greater change in humidity would be required to maintain transpiration from the upper leaves at reduced irradiance than from the lower ones”
Claim · model-written summary
The calcium accumulation rate in tomato leaves would be closely linked to transpiration.
- Taxon
- tomatoSolanum lycopersicumt0
- Outcome
- accumulation rate of calciume1
- Qualifier
- closely linked to the transpiratione1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“tomato leaves”
e1“The accumulation rate of calcium would be closely linked to the transpiration”
Claim · model-written summary
The model can explain calcium deficiency in tomato leaves that develop during periods of low solar intensity and high humidity.
- Taxon
- tomatoSolanum lycopersicumt0
- Outcome
- deficiency in calcium levels in leavese1
- Qualifier
- periods of low solar intensity and high humiditye1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“tomato leaves”
e1“the model can explain the deficiency in calcium levels in leaves that develop during periods of low solar intensity and high humidity”
Claim · model-written summary
Lowering environmental humidity with an evaporative equivalence factor is proposed to compensate for low radiation in tomato crops.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- use of an evaporative equivalence factore1
- Outcome
- compensating by lowering the humidity of the environmente1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“tomato leaves”
e1“It provides a basis for compensating by lowering the humidity of the environment by use of an evaporative equivalence factor relating vapour pressure deficit to radiation incident on the crop”
Claim · model-written summary
Transpiration should be at least 2.2 times the rate of leaf expansion to prevent appreciable yield loss from calcium deficiency in tomato.
- Taxon
- tomatoSolanum lycopersicumt0
- Outcome
- rate of transpiratione1
- Value
- 2.2 timese1
- Qualifier
- to prevent any appreciable yield loss from calcium deficiencye1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“tomato leaves”
e1“the rate of transpiration should be at least 2.2 times the rate of leaf expansion to prevent any appreciable yield loss from calcium deficiency”
Claim · model-written summary
A total of 8.7 MJ m-2 d_l of radiation and radiation equivalent would be required for tomato.
- Taxon
- tomatoSolanum lycopersicumt0
- Outcome
- radiation and of radiation equivalente1
- Value
- 8.7 MJ m-2 d_le1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“tomato leaves”
e1“a total of 8.7 MJ m-2 d_l of radiation and of radiation equivalent would be required”
Claim · model-written summary
Vapour pressure deficit compensation of 0.04 kPa per MJ m-2 d-1 of radiation shortfall is required in tomato.
- Taxon
- tomatoSolanum lycopersicumt0
- Outcome
- vapour pressure deficit compensatione1
- Value
- 0.04 kPae1
- Qualifier
- per MJ m_2 d_1 shortfalle1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“tomato leaves”
e1“0.04 kPa vapour pressure deficit compensation per MJ m_2 d_1 shortfall”