il. XXXVIII, Part 7B 
In: Wagner W., Székely, B. (eds.): ISPRS TC VII Symposium - 100 Years ISPRS, Vienna, Austria, July 5-7, 2010, IAPRS, Voi. XXXVIII, Part 7B 
oved based on 
;tance values in 
spectral curves 
edge position in 
l the specified 
Tarom 
Figure 2: The canopy of seven rice variety to be measured 
Neda 
3. RESULT AND DISCUSSION 
After spectral measurements, the result of performed 
processes on data was spectral curves at 2500-350 nm 
wavelengths. All the curves were quality reviewed and the 
noise spectra in water absorption feature were removed 
based on the standard deviation of all reflectance values in 
each wavelength. Figure 3 shows spectral characteristics 
of studied rice cultivars after necessary prepossessing. 
The first derivative Curve in the range of red edge 
wavelengths calculated (Figure 4) and the highest value 
obtained in this range as the maximum possible slope is 
determined as the red edge position for each of the seven 
cultivars (Fig. 6). Based on these results, the red edge 
position of the hybrid cultivar was the highest wavelength 
(724 nm) than the rest of rice cultivars. REP of Tarom, 
Khazar, Neda was at 716 nm while for Nemat, Shiroudi 
and Fajr were determined at 700, 694 and 694 nm, 
respectively (Figure 5). The results showed that Hybrid 
variety was the most likely variety than the others and has 
the highest chlorophyll and nitrogen concentrations 
inverse Shiroudi and Fajr variety based on spectral 
characteristics. 
2 0.5 
i 
— Fajr 
—Hybrid 
—Khazar 
— Neda 
— Nemat 
\ , 
X/, 
—7 
arom 
ik 
1 
iff 
t 
& 
$0 
1150 1350 1550 
Wavelength (nm) 
Figure 3: Spectral reflectance curves of seven rice variety of north of Iran 
Red edge region are relatively insensitive to changes of 
biophysical factors such as soil cover percentage, optical 
properties, canopy structure, atmospheric effects, 
irradiance and solar zenith angle (Shaffi et al., 2006; 
Clevers, 1999 and 2000), therefore this region is a reliable 
range to investigate the biochemical variables form 
canopy reflectance. The obtained Results from literatures 
proved the Relationship between chlorophyll and red edge 
position so that with increasing chlorophyll and nitrogen 
concentration the REP moves towards the longer 
wavelengths (Boochs et al, 1990 ^Curran et al., 1990 s 
Fillella and Penuelas 1994; Shaffi et al., 2006). The 
obtained results by Nemat Zade and Sattari (2003) also 
Allah Gholipour (2007) show that Hybrid variety is a 
high-yielding variety equal to 25-20% times than the other 
variety in this study. REP of Hybrid rice that positioned at 
longer wavelength could indicate more 
chlorophyll/nitrogen concentration and leaf area index, 
rather than the other varieties. Mutanga and Skidmore 
(2007) studied the relationship between REP and nitrogen 
content of grass vegetation. They indicated that nitrogen 
content correlated well with wavelength at 713nm and 
725 nm as determined REP. 
3