The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Voi. XXXVII. Part B7. Beijing 2008
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3. EXPEEERIMENTAL RESULTS AND DISCUSSION
3.1 The canopy and leaf hyperspectral feature for spr-
wheat in different stage
In different growth stage, the hyperspectral reflectance of the
canopy level and the leaf level are different, the hyperspectral
reflectance of the canopy level and the leaf level are different,
and that of the canopy is highest at jointing stage and lowest at
ripening stage in the visible (VIS) region and in the shortwave
infrared (SWIR) and the spectral variation trend is similar,
meanwhile, that is highest at flowering-filling stage in the
near infrared region. The green peak disappeared at ripening
stage. On the contrary, the leaf hyperspectral reflectance is
highest at jointing stage than other stage in the near infrared
region, and the reflectance in green region is falling at ripening
stage.
In summary, the spectral difference is significant to monitoring
the growth status in different stage.
Figure. 1 The canopy and leaf hyperspectral for spr-wheat in
growth stage
3.2 The charactering of the canopy and leaf for spr-wheat
in different density
Fig.lA~Fig.lD show the reflectance of canopy and leaf at the
booming and ripening stages in seven density scales (dl~d7 in
dicate from sparse to bushy). It shows that the curves were
similar but the reflectance values are different. The spectral dif
ferences are clear for the canopy and leaves of spr-wheat under
different density levels, and the canopy spectral reflectance are
gradually getting smaller in the visible (VIS) region and bigger
in the near infrared (NIR) region along with density level in
creasing at booting stage, but this change is not evidence at rip
ening stage. The difference of the spectral reflectance of the
leaf from the top on the main stem is little in VIS region and
great in NIR region at booting stage and this difference in VIS
and NIR is coherence along with the different density. At rip
ening stage, the spectral reflectance of the leaf is bigger in
middle density level. And the leaf reflectance of D7 was the
least because of the competitive growth, the LAI of the D7 was
the least and the leaf reflectan was lower. Moreover, the other
breeds have the same variety trends.
dl d2 d3 d4 d5 d6 d7
0.4
waveband (nm)
850
1350 1850
waveband (nm)
2350
leaf
Figure.2 The charactering of the canopy hyperspectral for spr-
wheat in different density at booting stage
3.3 The hyperspectral in different for the spr-wheat
The hyperspectral reflectance of the canopy and the leaf for the
four spr-wheat breeds in the same density were compared and
it indicated that there are no obviously difference in these four
kinds spr-wheat in canopy spectral reflectance, while the spec
tral reflectance difference of leaf level is clearly in the near in
frared (NIR) region at booting stage, and the biggest is the
Longchun8139, Dingxi24 the second, Heshangtou the third and
Gaoyuan602 spr-wheat the forth. The difference of reflectance
maybe connected with the bearing feature for each cultivar.
The longchun8139 is a kind of earliness species and the plant
growth is blooming. And the grown stage of Dingxi24 is longer
and the leaf is bigger and the color of the leaf is thicker, the
leaf of Gaoyuan602 and Heshangtou is little. It indicates the
possibility to identify the wheat type using the hyperspectral
reflectance data by the experiment.
0.6
Heshantou
Figure.3 The leaf hyperspectral of the different species spr-
wheat