Abstract
Under natural light conditions, the radiation impinging upon foliage from sky is composed of the direct and the diffuse radiation. The intensity of direct radiation within foliage is determined with the extinction coefficient for one beam, and the intensity of diffuse radiation with Monsi and Saeki's formula concerning the ratio of light intensity inside and outside of foliage in isotropic light beam.Our theoretical extinction coefficient for one beam (KD) corresponds to the ratio of the horizontal projection to the actual area in a leaf. In the foliage that consists of leaves orientating at right angles to the sun, KD=cosecH (H, sun elevation). In the foliage with random arrangement of leaves inclined at a fixed angle (α) to the horizontal, KD=cosα in H≥α, and in H<α KD={cosα⋅sin-1 (cotα⋅tanH)+(sinα⋅cotH)√1-cot2α⋅tan2H}2/π. Using these equations and Monsi and Saeki's formula, the relative light intensities under sunny conditions were calculated as a function of leaf area index and sun elevation. The calculated light intensity had a diurnal minimum at H=30°, in α=80° as well as in leaves with a phototropic movement. This result agrees with the observation of Brougham in perennial ryegrass community and in white clover community under sunny conditions. Disagreement among some observers as to the relative light intensity measurements was elucidated on the basis of our theoretical analysis of extinction coefficient for one beam. Light transmission of each leaf leads to the increase of light intensity within foliage, and light reflection from foliage surface results in the decrease of light intensity. Consequently, the theoretical equations whether which include or not the terms concerned with transmission and reflection bring about the same light intensities.
Abstract from the paper’s OpenAlex record, shown for indexing and research. Copyright remains with the authors or the publisher. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 5
Claim · model-written summary
The theoretical extinction coefficient for one beam in foliage of leaves orientated at right angles to the sun is KD = cosec H, with H the sun elevation.
Verbatim
e0“In the foliage that consists of leaves orientating at right angles to the sun, KD=cosecH”
Claim · model-written summary
Calculated relative light intensity in foliage under sunny conditions had a diurnal minimum at sun elevation 30 degrees for leaves inclined at 80 degrees and for leaves with phototropic movement.
- Outcome
- diurnal minimume1
Not reportedTaxonSetting
Verbatim
e1“The calculated light intensity had a diurnal minimum at H=30°, in α=80° as well as in leaves with a phototropic movement”
Claim · model-written summary
The calculated diurnal minimum of light intensity agrees with the observation of Brougham in a perennial ryegrass community under sunny conditions.
- Taxon
- perennial ryegrass
Lolium perennee1 - Outcome
- diurnal minimume0
- Setting
- sunny conditionse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The calculated light intensity had a diurnal minimum at H=30°, in α=80° as well as in leaves with a phototropic movement”
e1“This result agrees with the observation of Brougham in perennial ryegrass community and in white clover community under sunny conditions”
Claim · model-written summary
The calculated diurnal minimum of light intensity agrees with the observation of Brougham in a white clover community under sunny conditions.
- Taxon
- white clover
Trifolium repense1 - Outcome
- diurnal minimume0
- Setting
- sunny conditionse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The calculated light intensity had a diurnal minimum at H=30°, in α=80° as well as in leaves with a phototropic movement”
e1“This result agrees with the observation of Brougham in perennial ryegrass community and in white clover community under sunny conditions”
Claim · model-written summary
Theoretical equations that include or omit the terms for leaf transmission and reflection give the same light intensities within foliage.
Not reportedTaxon
Verbatim
e0“the theoretical equations whether which include or not the terms concerned with transmission and reflection bring about the same light intensities”