Vergara - 1976 - Physiological and morphological adaptability of ri

ixucitotiaiixixna or THE RICE (can? 121
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0700
(ma?)
IRBGQPL 11- .1971)
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oo=1s t
é
M127‘)
g 1000
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g
0 697 O 697 0 697
Irradiation intensity on leaf surface lW-mql
4. Partition of solar radiation energy among the leaves of rice canopies (ljdagawa et a1“
1974a)
increase of solar elevation. more leaf area is illuminated by more intense radiation
and the solar energy partition function is characterized by the curve with a
peak between 140 to 210 w/m= and with a greater dispersion in the higher irradianee
range. The mean irradianee of leaves at a leaf area depth of L was
found to be well approximated by
3(1) = ilStI-T“ (7)
where dS,(L) is the sum of dotvnttrard radiation components at level L. It was
found experimentally that the value of rn is a decreasing function of solar elevation
ranging from l.l at h o = 19° to Q81 at h O = 65°. The sum of dotvntt-‘ard
components of radiation fluxes at a level L can be approximately expressed as
6810/) = [SAW + SAW] “PF RJJ (3)
where k. is the extinction coefficient characterizing the attenuation of the sum
of downward radiation components in the rice crop, Figure 2A show‘ that the
extinction coefficient k, decreased gradually with stwlar elevation from 1.0 at
h, = 10° to 0.55 at h, = ?O°