In: Wagner W„ Székely, B. (eds.): ISPRS TC VII Symposium - 100 Years ISPRS, Vienna, Austria, July 5-7,2010, IAPRS, Vol. XXXVIII, Part 7B 
SPECTRAL REFLECTANCE OF RICE CANOPY AND RED EDGE POSITION 
(REP) AS INDICATOR OF HIGH-YIELDING VARIETY 
M. Abbasi 1 , A.A. Darvishsefat 2 , M. E. Schaepman 3 
'Department of Forestry, Faculty of Earth Science and Natural Resource, Shahrekord University, Shahrekord. 
Iran 
2 Department of Forestry, Faculty of Natural Resource, University of Tehran, Karaj. Iran 
3 University of Zurich, Winterthurerstrasse 190, CH - 8057 Zurich, p +41 44 635 51 60 
Michael.Schaepman@geo.uzh.ch, adarvish@ut.ac.ir, mozhgan.abasi@gmail.com 
KEY WORDS: Spectral reflectance, rice, red edge position, first derivative, high-yielding variety 
ABSTRACT: 
Rice is the staple food in Iran. More than 80 percent of rice area is distributed in the two northern provinces of Mazandaran 
and Gilan, so that investment in increasing the quantity and quality can impact an effective role in economic independence 
and sustainable agriculture. Increased efficiency in rice production is possible through varietal technology, advances in yield 
enhancement, and the successful development of hybrid technology. Nondestructive methods such as study the spectral 
reflectance of rice fields is a reliable way in remote sensing study. In this study we tested the possibility to predict high- 
yielding rice varieties based on the spectral reflectance data in the red edge position (REP). Spectral reflectance of rice 
canopies from 350 to 2500 nm were acquired under clear sky in rice filed. The obtained results indicate that REP of Hybrid, 
Tarom, Neda and Khazar varieties are at longer wavelength, so they are predicted as more productive rice varieties. 
1. INTRODUCTION 
Remotely sensed data provide considerable potential for 
estimating agricultural area and yield forecasting at local, 
regional, and global scales (Kamthonkiat, et al., 2005; 
Xiao et ah, 2006; Serra et ah, 2007, Khajeddin & 
Pourmanafi, 2007; Ansari Amoli & Alimohmmadi, 2007). 
Estimation these information by remote sensing mainly 
depended on the spectral characteristics of field crops. 
Many studies using rice spectral reflectance data has been 
done to estimate its product and health condition at red 
edge region (Yang and Cheng, 2001; Xue, et ah, 2004; 
Shen et ah, 2007;Wang et ah, 2008). 
Some parameters such as chlorophyll content, nitrogen, 
LAI, biomass and relative water content were studied in 
the first derivative reflectance curve in the red edge region 
(Jago et ah, 1999; Yoder and Pettigrew-Crosby, 1995; 
Skidmore and Mutanga 2007). This position is the point 
of maximum slope on the reflectance spectrum of 
vegetation between red and near-infrared wavelengths. 
Technically, the red edge is a spectral reflectance feature 
characterized by darkness in the red portion of the visible 
spectrum, due to absorption by chlorophyll, contrasting 
strongly with high reflectance in the NIR, due to light 
scattering from refraction along interfaces between leaf 
cells and air spaces inside the leaf (Bonham-Carter, 1988; 
Dawson and Curran, 1998, Tinetti et ah, 2006). Field crop 
reflectance actually was a kind of mixed reflectance, 
influenced not only by rice canopy but also by soil. 
Extraction REP which is based on derivative analysis 
minimizes interpolation errors and soil background effects 
and computationally, it is one of the simpler curve fitting 
techniques (Shafri et ah, 2006). 
Hybrid varieties have the potential to raise the yield of 
rice and thus overall rice productivity and profitability in 
the north of Iran. So this has led the public and private 
sectors to develop the use of hybrid rice technology in 
recent years. Successful deployment of using hybrid rice 
in sustainable management, however, requires 
information about the area and productivity of different 
rice cultivars. Spectral field reflectance could use in 
remote sensing data for accessing this information. The 
increase reflectance in the near infrared range and caused 
a shift in the position of the red edge toward longer 
wavelengths depend upon the productivity element in 
vegetation; have shown the most productivity of some 
cultivar rather than the other ones. The objectives of this 
study were to prepare the spectral fingerprint of most 
important rice cultivars of northern of Iran and study the 
red edge position related to high-yielding of different rice 
varieties. 
2. MATERIAL AND METHODS