高光谱数据探讨水稻叶片叶绿素含量对叶片及冠层光谱反射特性的影响

Discussing Effects of Different Chlorophyll Concentration to Leaf and Canopy Reflectance by Hyperspectral Data

为了考察叶绿素含量变化对叶片及冠层反射率的影响,利用PROSPECT模型和FCR模型,模拟叶片叶绿素含量变化(20μg/cm2、22μg/cm2、24μg/cm2、26μg/cm2、28μg/cm2、30μg/cm2)时的叶片反射率和叶面积指数变化(1、3、5)时的冠层反射率。叶片及冠层反射率的变化大小,用同一波段上反射率的标准差来衡量,研究的波段范围为400～940nm,波段间隔为5nm。研究发现叶绿素对叶片反射率的影响,在710nm波长处最大,标准差变化曲线在550nm、710nm、795nm和830nm处形成4个峰值,对冠层反射率的影响,与叶面积指数大小有关,叶面积指数为1、3、5时,叶绿素对冠层反射率影响最大的波长分别为715nm、720nm和725nm,标准差变化曲线分别在550nm和715nm、550nm和720nm、550nm和725nm形成了两个峰值。

To study the influence of chlorophyll concentration on rice leaf and canopy reflectance, simulating changes of leaf and canopy reflectance with different chlorophyll concentration by PROSPECT and FCR model. The serials of chlorophyll concentrations are 20 μg/cm\+2,22 μg/cm\+2,24 μg/cm\+2,26 μg/cm\+2,28 μg/cm\+2 and 30 μg/cm\+2. The different leaf area indexes (LAI) are 1,3 and 5. The change extent of reflectance is valued by STDEV (Standard Error Variation) in the same wavelength, the wavelengths range from 400 nm to 940 nm, and the interval is 5 nm. In the research we know that the strongest influence on leaf reflectance is in 710 nm, and the STDEV curves form four peaks in 550 nm, 710 nm, 795 nm and 830 nm. The influence of chlorophyll concentration on canopy reflectance changes with different LAI. For different LAI value 1,3 and 5, 715 nm, 720 nm and 725 nm are strongest affected, and the STDEV curves form two peaks in different LAI, they are 550 nm and 715 nm, 550 nm and 720 nm, 550 nm and 725 nm.