The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part B7. Beijing 2008
3.4 The red edge feature of the canopy and leaf for spr-
wheat
Like most of the green vegetation, there are “double peak” or
“multi-peak” phenomena for the spr-wheat at growth stage,
just the “double peak” feature is not notably because of the im
pacts of the soil spectral at the beginning of the growth stage,
and it disappeared until the wheat mature and the leaf turn to
yellow.
0. 007
| 0.006
| 0.005
u ' e 0. 004
5 ° o.oo3
s ^
2, 0.002
.g
^ 0.001
0
660 680 700 720 740 760 780
waveband(nm)
- - - - jointing stage booting stage -heading stage
—x—filling stage milkinem stage -ripening stage
Figure.4 the first derivative spectra of canopy red edge for
spr-wheat in different stage
735
J 730
0
■{? 725
Q
■g 720
| 715
o 710
■2 705
o 700
Q.
| 695
690
jointing booting heading filling milking ripening
growth stage
Figure.5 The position of the red edge change of canopy for spr-
wheat in different four densities in different stage
From the Fig.4 and Fig.5, the red edge position of the canopy
reflectance is at 700~730nm region during the growth stage,
Additionally, by the grown stage from the joinging stage to
heading stage, there were “red shift” phenomena weakly and
from heading stage to ripening stage, there were “blue shift”
phenomena remarkably, and for the X red , D X red and Sred of
the canopy and leaf spectra are decrease from jointing stage to
ripening. This shows that the X red, D X red and Sred are the
signal of the wheat growing, it also shows that the red edge po
sition maybe the indicator for the vegetation in stress status.
table. 1.
From Fig.6,Fig.7 and the table.2, The leaf area indices
(LAI),the above ground fresh biomass, above ground dry bio
mass , plant height, chlorophyll are significantly correlative to
the spectral Vegetation Indices: normalized difference vegeta
tion index(NDVI), soil adjusted vegetation index (SAVI),
ratio vegetation index (RVI) »difference vegetation index (DVI)
and perpendicular vegetation index (PVI), etal, and the rela
tionship of PVI with plant height and above ground fresh-
biomass-weitht(FW) is the best(R=0.
563,P<0.01;r=0.685,P<0.01), and the LAI have the best rela
tionship with DVI (r=0.694,P<0.01) and the relativity are the
best between the spectral index(R670/440) and the chlorophyll
among the selected spectral index(r=-0.846,P<0.01), X red and
plant chlorophyll content are good correlation. This indicated
that some right spectral variables would be used to estimate the
LAI, ADM, the PH and chlorophyll for spr-wheat. Furthermore,
the correlation of the spectral index and the biochemical prop
erties of vegetation are effected by the different cultivars.
Figure.6 the relationship between the spectral indices and the
LAI
3.5 The relationship of the hyperspecral data and the
biophysical Parameters
For the sake of analyzing the correlations among the ground
dry weight (ADM), the plant height (PH) and the hyperspectral
variable, we selected the rate of the special band and the red
edge parameter to built the following spectral variable listed in