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Canopy clumpiness and radiation penetration in a young hedgerow apple orchard
Year:
1995
Authors :
Cohen, Shabtai
;
.
Volume :
76
Co-Authors:
Cohen, S., Department of Environmental Physics and Irrigation, Agricultural Research Organization, Volcani Center, P.O. Box 6, Bet Dagan, 50250, Israel
Mosoni, P., Department of Viticulture. University of Horticulture and Food Industry, Budapest, Hungary
Meron, M., Migal Galille Technology Center, Kiryat Shmona, 10200, Israel
Facilitators :
From page:
185
To page:
200
(
Total pages:
16
)
Abstract:
Model inversion procedures for computing leaf area index (LAI) from radiation measurements depend on foliage organization in space. The objective of this study is to find the parameters quantifying the geometry of a 5-year-old hedgerow apple orchard and to test the assumptions in the radiation penetration model serving to derive LAI. Leaves within contour intervals of photosynthetic photon flux density (PPFD) were picked and their area determined. Calculated extinction coefficients for these intervals were positively correlated with LAI. Clumpiness factors (i.e. independent leaf area layer thicknesses for the negative; binomial model) δ, for these contour intervals, showed that the canopy is very clumpy on the outside (7 < δ < 15 for average-sized 'normal' trees, and 3 < δ < 7 for smaller than average 'weak' trees) and close to random on the inside (2 < δ < 4 for normal trees and 1 < δ < 3 for weak trees). Cluster analysis theory shows that leaves in the upper part of the tree were clustered around leafy shoots whereas lower in the canopy clustering around shoots weakened. A model of gap frequency in a stand of vertical columns of leaves was used to evaluate gap frequency in a tree composed of long leafy shoots. Assuming that the density of the vertical columns. is proportional to the cumulative LAI traversed by a ray predicts a light penetration profile similar to that measured in the apple trees. The results imply that measurement of LAI of the upper part of the canopy with inversion techniques may result in severe underestimations. Similarly, radiation penetration in this part of the canopy is underestimated by simple turbid medium models. © 1995.
Note:
Related Files :
Apple orchard
canopy clumpiness
leaf area index
Malus spp.
radiation penetration
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More details
DOI :
10.1016/0168-1923(95)02226-N
Article number:
Affiliations:
Database:
Scopus
Publication Type:
article
;
.
Language:
English
Editors' remarks:
ID:
21880
Last updated date:
02/03/2022 17:27
Creation date:
16/04/2018 23:47
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