304 
by Daughtry et al., (1993) were used as background materials in the simulation of canopy reflectance. A total of 
840 canopy reflectance, 20 levels of LAI ranging from 0.1 to 4.5 (0.1 to 1.0 in 0.1 interval, 1.25, 1.5, 1.75, 2, 2.25, 
2.5, 3, 3.5, 4, and 4.5), with 42 different soils as background were simulated. In conjunction with these reflectance 
spectra, the fraction of absorbed photosynthetically active radiation ( Fa^ = [ A^ r /Incident PAR ] ) were 
simulated. 
Figure 6 is a presentation of vegetation indices plotted against Fa^ r . These vegetation indices were 
calculated using the results from the SAIL model simulation. The normalizedoifference vegetation index (NDVI) 
was calculated using (NIR - RED)/(NIR + RED). For the calculation of the soil adjusted vegetation index 
(SAVI; Huete, 1988), a soil isoline factor of 0.5 resulted in the smallest variation for canopies with LAI less than 
or equal to 2. Thus, SAVI was calculated as [(NIR - RED)/(NIR + RED + 0.5)] X (1.5). the ratio of (750-850 
nm and 600-690 nm were used for the SR. Before full canopy closure, NDVI (Fig. 6(a)) and SR (Fig. 6(b)) are 
highly variable in the assessment of Fa par due to the variations in the soil background reflectance. The effects of 
soil backgrounds were significantly reauced by SAVI (Fig. 6(c)) and CARI (Fig. 6(d)). 
In order to compare variability of these vegetation indices at lower LAI, canopy reflectance were simulated 
at LAI ran ging from 0.05 to 2.0 in 0.05 interval, and the vegetation indices were calculated. The parameters used 
for this simulation were the same as the previous simulation. The statistical procedure Student-Newman-Kuels 
mean test was conducted to these vegetation indices. Table 3 is a presentation of the test results, where means 
TABLE 3. Student-Newman-Kuels test for variables, means with the same letter are not significantly 
different at a significance level of 1 % (a = 0.01). 
LAI 
SNK (CARI) 
SNK (NDVI) 
SNK (SAVI) 
SNK (SR) 
2.00 
A 
A 
A 
A 
1.95 
B A 
A 
B A 
B A 
1.90 
B 
B A 
B AC 
B C 
1.85 
C 
B A 
B D A C 
D C 
1.80 
D 
B AC 
B D E C 
D E 
1.75 
E 
B AC 
DEC 
F E 
1.70 
F 
B D A C 
F D E 
F G 
1.65 
G 
B D A C 
F EG 
H G 
1.60 
H 
E B D A C 
F H G 
H I 
1.55 
I 
E B D A C F 
I H G 
J I 
1.50 
J 
E B D C F 
I H J 
J K 
1.45 
K 
E D G C F 
I K J 
L K 
1.40 
L 
E H D G F 
K J 
L M 
1.35 
M 
EH G F 
L K 
N M 
1.30 
N 
H GIF 
L M 
N O 
1.25 
O 
H J G I 
N M 
P O 
1.20 
P 
H J K I 
N O 
P Q 
1.15 
Q 
J K I 
P O 
R Q 
1.10 
R 
L J K 
P Q 
R S 
1.05 
S 
L KM 
R Q 
T S 
1.00 
T 
L N M 
R S 
T U 
0.95 
U 
N M 
T S 
V U 
0.90 
V 
O N 
T U 
V W 
0.85 
w 
O P 
V u 
X W 
0.80 
X 
Q P 
V 
X Y 
0.75 
Y 
Q R 
w 
Z Y 
0.70 
Z 
S R 
X 
Z A 
0.65 
A 
S T 
Y 
B A 
0.60 
B 
U T 
Z 
B C 
0.55 
C 
U V 
A 
D C 
0.50 
D 
V 
B 
D E 
0.45 
E 
w 
C 
F E 
0.40 
F 
X 
D 
F G 
0.35 
G 
Y 
E 
H G 
0.30 
H 
Z 
F 
H I 
0.25 
I 
A 
G 
J I 
0.20 
J 
B 
H 
J I K 
0.15 
K 
C 
I 
J L K 
0.10 
L 
D 
J 
L K 
0.05 
M 
E 
K 
L