Table 2. Regressions of sugar beet cover percentage 
and spectral parameters in 1984. 
Parameter 
Regression type 
Corr. coeff. 
VI 
power fit 
.83 
PVI 
power fit 
.90 
ID 
power fit 
.94 
GREENNESS 
logarithmic fit 
.85 
Table 2 shows the results of best fit regression 
calculations for the 1984 data. 
These were again used to compute predicted cover 
percentages based on 1985 spectral data. All values 
exceeding complete coverage were set at 100 X. 
Regressions ux predicted versus averaged measured 
values are displayed in Figure 6. Due to limited 
availability of low cover data the slope of the 
regressions lines is strongly influenced by few 
points. Predicted values based on Greenness approach 
closely the 1:1 line. 
Accurate cover percentage estimation can give 
important indications on seedling establishment. 
Figure 6. Relationship between measured and predicted 
cover percentage for sugar beets. Complete cover 
prediction points are omitted for clarity. 
4.3. Sugar mass 
Sugar mass (kg/ha) was calculated from fresh root 
weight data and sugar content (%) analysis. Evolution 
of both measured biomass parameters in the course of 
the growing season is displayed in Figure 7. While 
sugar content is similar in both growing seasons, 
root mass is considerably lower in 1985. 
The "leaf area duration" concept was applied by 
computing GLAD values. A6 Figure 8 shows, and 
confirming what is known from sugar beet physiology 
research, prolongued availability of a large amount 
of phoyosynthetically active crop canopy does not 
necessarily result in increased sugar accumulation. 
Rather increased leaf development occurs at the 
expense of root growth which in turn has limited sink 
capacity. Unusually advantageous weather conditions 
Figure 7. White sugar percentage (full line) and 
fresh root mass (dashed line) in 1984 (x) and 1985 
(+). 
Figure 8. White sugar mass in function of GLAD in 
1984 (x) and 1985 (+). 
Figure 9. Relation between NEKC (full line), PVIC 
(dashed line) and white sugar mass in 1984 (x) abd 
1985 (+). Relations with VIC and GREENNESSC are 
similar to NDC and PVIC respectively but are not 
shown. 
in September and October 1985 (high daily 
temperatures, low rainfall and cool nights) caused 
spectacular sugar accumulation. 
Accumulated spectral values for VI (VIC), ND (NDC), 
PVI (PVIC) and Greenness (Greennessc) were computed. 
Some of these values are plotted against sugar mass 
in Figure 9. 
A linear relationship for the 1984 growing season is 
apparent, while the above explained meteorological 
phenomena 
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REFERENCES 
Allen, E.J 
growth c 
94:583-e 
Analogides 
starting 
ty. Proc 
Andrieu B. 
ques et 
la rhizc 
on Rem. 
Badhwar, G 
Satellit 
maps as 
hierarch 
265-281. 
Boehnel, F 
tu mease 
tral cha 
beets. 
Detectic 
sing tec 
Europear 
Colwell, J 
yield fc 
Symp. or 
1254. 
De Wulf, 1 
indicati 
from CD