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Leaf area estimates from measurements of photosynthetically active radiation in wheat canopies
Year:
1984
Authors :
Fuchs, Marcel
;
.
Volume :
32
Co-Authors:
Fuchs, M., Evapotranspiration Laboratory, Kansas State University, Manhattan, KS 66506, United States
Asrar, G., Evapotranspiration Laboratory, Kansas State University, Manhattan, KS 66506, United States
Kanemasu, E.T., Evapotranspiration Laboratory, Kansas State University, Manhattan, KS 66506, United States
Hipps, L.E., Utah State University, Logan, UT, United States
Facilitators :
From page:
13
To page:
22
(
Total pages:
10
)
Abstract:
Transmission of photosynthetically active radiation (PAR) measured with quantum sensors in three wheat cultivars during periods of clear sky were used to indirectly determine the leaf area index (LAI). The exponential description of direct and diffuse radiation penetration, which depends on leaf inclination, was correlated to the transmission measurements at various solar zenith angles. The highest correlations were found for fixed leaf inclinations of 60 and 75°, and for the spherical leaf angle distribution. Angular shape coefficients corresponding to these leaf inclinations were then used to solve the exponential equation for LAI taking incoming PAR to be direct. This was shown to be an acceptable approximation when the proportion of direct radiation in the incoming PAR was higher than 0.85. Predictions of LAI were found to be within 0.7 units for a range of LAI from 1.5 to 5.0. A statistical analysis of the results indicated that the most suitable leaf inclination was a combination of 60 and 75° fixed angles, and spherical distribution. © 1984.
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DOI :
10.1016/0168-1923(84)90024-8
Article number:
Affiliations:
Database:
Scopus
Publication Type:
article
;
.
Language:
English
Editors' remarks:
ID:
19255
Last updated date:
02/03/2022 17:27
Creation date:
16/04/2018 23:27
You may also be interested in
Scientific Publication
Leaf area estimates from measurements of photosynthetically active radiation in wheat canopies
32
Fuchs, M., Evapotranspiration Laboratory, Kansas State University, Manhattan, KS 66506, United States
Asrar, G., Evapotranspiration Laboratory, Kansas State University, Manhattan, KS 66506, United States
Kanemasu, E.T., Evapotranspiration Laboratory, Kansas State University, Manhattan, KS 66506, United States
Hipps, L.E., Utah State University, Logan, UT, United States
Leaf area estimates from measurements of photosynthetically active radiation in wheat canopies
Transmission of photosynthetically active radiation (PAR) measured with quantum sensors in three wheat cultivars during periods of clear sky were used to indirectly determine the leaf area index (LAI). The exponential description of direct and diffuse radiation penetration, which depends on leaf inclination, was correlated to the transmission measurements at various solar zenith angles. The highest correlations were found for fixed leaf inclinations of 60 and 75°, and for the spherical leaf angle distribution. Angular shape coefficients corresponding to these leaf inclinations were then used to solve the exponential equation for LAI taking incoming PAR to be direct. This was shown to be an acceptable approximation when the proportion of direct radiation in the incoming PAR was higher than 0.85. Predictions of LAI were found to be within 0.7 units for a range of LAI from 1.5 to 5.0. A statistical analysis of the results indicated that the most suitable leaf inclination was a combination of 60 and 75° fixed angles, and spherical distribution. © 1984.
Scientific Publication
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