Translated Titles

Relationship between Canopy Reflectance and Plant Water Content in Rice under Different Soil Water and Nitrogen Conditions


田永超(Yong-Chao Tian);曹卫星(Wei-Xing Cao);姜东(Dong Jiang);朱艳(Yan Zhu);薛利红(Li-Hong Xue)

Key Words

水稻 ; 土壤水分 ; 植株含水率 ; 反射光谱 ; 比值植被指数 ; 监测模型 ; Rice ; Soil water ; Plant water content ; Spectral reflectance ; Ratio vegetation index ; Monitoring model



Volume or Term/Year and Month of Publication

29卷2期(2005 / 03 / 01)

Page #

318 - 323

Content Language


Chinese Abstract

研究了不同土壤水氮条件下水稻(Oryza sativa)冠层光谱反射特征和植株水分状况的量化关系。结果表明,水稻冠层近红外光谱反射率随土壤含水量的降低而降低,短波红外光谱反射率随土壤含水量的降低而升高。相同土壤水分条件下,高氮水稻的冠层含水率高于低氮水稻的冠层含水率;同一水分条件下,高氮处理的可见光区和短波红外波段光谱反射率低于低氮处理,近红外波段光谱反射率高于低氮处理。发现拔节后比值植被指数(R810/R460)与水稻叶片含水率和植株含水率呈极显著的线性相关,模型的检验误差(Root mean square Error, RMSE)分别为0.93和1.50。表明比值植被指数R810/R460可以较好地监测不同生育期水稻叶片和植株含水率。

English Abstract

The ability to non-destructively monitor crop water status by remote sensing is of significant importance for optimizing of crop irrigation systems and precision farming. In order to develop quantitative models for monitoring rice water status by canopy reflectance spectra, an investigation was conducted to study the relationship between canopy reflectance characteristics and plant water status under different water and nitrogen levels with different pot and pool experiments. The results showed that the crop spectral reflectance decreased in the visible wavelength regions and shortwave infrared (SWIR) (1 400-1 700 nm) regions with increasing water supply, because absorption of visible light (450-700 rim) by leaf chlorophyll was aggravated whereas the spectral reflectance in the near infrared (NIR) (750-950 nm) wavelength regions increased. A high reflectance spectra flat roof formed which remained throughout the entire growth period. Under different water regimes, canopy reflectance showed similar patterns of change. Under the same water supply, the canopy spectral reflectance in the visible wavelength and SWIR regions was lower under high nitrogen supply than under low nitrogen supply rates but showed an opposite pattern in the NIR wavelength regions. Canopy reflectance in single hands is often subject to interference by biomass, background and so on, but the ratio of two bands can alleviate interference due to topography and enlarge the difference of spectral reflectance between vegetation types thus improving the precision of estimates by spectral reflectance. Consequently, in order to eliminate some of the interferences for distinguishing leaf and canopy structure and establish the best predictive model for assessing leaf water content, all regressions between ratio indices, normalized difference indices and leaf and plant water content were conducted. The results indicated that there was a linear relationship between the vegetation index ratio (R810/R460) and canopy leaf water content and plant water content after jointing stage regardless of leaf nitrogen levels, with an RMSE of 0.93 and 1.50, respectively, for model testing. It is concluded that the vegetation index ratio of R810/R460 can be used to monitor leaf water content and plant water content at different growth stages of rice.

Topic Category 生物農學 > 植物學
生物農學 > 生物環境與多樣性