300 
JULIAN DATE 
line) and 
x) and 1985 
of GLAD in 
ï 
§ 
14000 16 000 ° 
1 MASS KG/HA) 
line), 
PVIC 
1984 (x) 
abd 
ÏENNESSC 
are 
but are 
not 
[high daily 
ghts) caused 
), ND (NDC), 
ire computed, 
it sugar mass 
ng season is 
iteorological 
phenomena cause the less regular pattern for 1985. An 
attempt to predict sugar yield for 1985 from 1984 
relationships by remote sensing methods only would be 
senseless. 
5 CONCLUSIONS 
Remote sensing of sugar beet biomass with the purpose 
of sugar yield estimation implies essentially an 
indirect measurement of subterranean plant parts. Due 
to meteorological factors experimental results did 
not indicate simple relationships between crop canopy 
and root biomass. Cover percentage could be estimated 
rather precisely although further experiments using 
more data are necessary to confirm these results. 
Estimated GLAI is likely to be used in prediction 
models which should also include meteorological 
factors. Without doubt sugar beet yield prediction 
with remote sensing methods only are prone to produce 
results as inaccurate as most agromet models. The 
ultimate solution appears to be a procedure 
incorporating both meteo and remote sensing 
parameters. 
It was also concluded that spectral reflectance data 
derived from CIR film yield results comparable to 
those obtained by using more widely applied 
radiometers. 
AKNOVLEDGEMENTS 
This research is part of IWONL contract No. 4555. 
Field equipment and computer hardware of the Centre 
for Remote Sensing of Vegetation (CEVA) were used 
throughout the experiments. 
The authors gratefully aknowledge EUROSENSE NV for 
development of the CIR films, Luc Vandekerckove wrote 
customized software on the PDP 11/34. Peter Haelvoet 
and Dirk Tietens cheerfully assisted for densito 
métrie measurements, GLAI calculations and drawings. 
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