Analysis shows strong correlations for these two crops.
The coefficient of determination (R?) for wheat for four
different correlations (LAIG - NDVIgz,4, LAIG - NDVIg,
LAIgG - NDVly; s and LAIG — NDVlIys) were found to be
0.70, 0.69, 0.72 and 0.71, respectively. In contrast, R° for
rice for these relationships were poor and were found to
be 0.02, 0.08, 0.2 and 0.1, respectively.
4. CONCLUSION
The models for estimation of LAIg from freely available
Landsat 5 TM were developed for the conditions in
Australia. The resolution of satellite images are
reasonably good to correlate point data measured at
sample points in different farms. Developed models can
be applied with any satellite images which are having
thermal bands (e.g. NOAA-AVHRR, ASTER, MODIS)
All models developed for corn and wheat have very
promising co-relations for the derivation of LAIg. These
strong correlations allow for the potential use of
developed models to estimate ground based LAI and they
can be used to address various agricultural landscape
issues within irrigated agriculture of Murray Darling
Basin in Australia. However the corresponding
relationships for rice are weak, most probably this is due
to the mixed spectral reflectance of plant-water-soil, as
rice crop is grown in flooded fields throughout the
cropping season. The possible reasons for weak
relationships for the rice crop are currently being
investigated using various modelling techniques and field
investigations which will be reported separately in the
future research.
Among all models, the atmospherically corrected
relationships are higher in accuracy. Moreover, the
correction based MLS model showed the highest
coefficient of determination. However, any model could
be used based on the availability of data and requirement.
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