Canopy spectra of plots of rice field treated with different nitrogen levels were periodically and continually measured during the whole growing period and LAI of the crop at several important growing stages was also determined. The results showed that despite different growing stages, rice canopy spectral reflectance changed regularly when the nitrogen fertilizer application rate increased. With the application rate of nitrogen fertilizer increasing, the canopy spectral reflectance increased at 710~1220nm, but decreased at 460~680nm. The variation of the canopy spectral reflectance at different nitrogen levels were analyzed and compared. The results showed that the canopy spectral reflectance was sensitive to nitrogen levels in 560~610nm and 710~760nm before milking. After transforming canopy spectral reflectance into normalized difference vegetation index (NDVI), (R760-R560)/(R760+R560) was significantly different at different nitrogen levels. In addition, the correlation coefficient between LAI and canopy spectral reflectance was low before the heading period, however, was high after the heading period.
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吕雄杰,潘剑君,张佳宝.水稻冠层光谱反射特征及其与叶面积指数关系研究[J].土壤,2004,36(6):648-653,684. L Xiong-jie, PAN Jian-jun, ZHANG Jia-bao. RICE CANOPY SPECTRAL REFLECTANCE AND LEAF AREA INDEX[J]. Soils,2004,36(6):648-653,684