不同生育期冬小麦高光谱数据与SPAD值的相关分析

Correlation Analysis of Hyperspectral Data and SPAD Value of Winter Wheat in Different Growing Stage

利用ASD便携式野外光谱仪和SPAD-502叶绿素计实测了冬小麦冠层的高光谱反射率与SPAD值.建立了基于归一化植被指数(NDVI)与比值植被指数(RVI)不同生育期冬小麦SPAD值估算模型.结果表明:从返青期到灌浆期,可见光波段,冠层光谱反射率与SPAD值负相关,在"红边"处,由负相关变成正相关.一阶导数光谱与SPAD值相关系数在有些波段要高于冠层原始光谱与SPAD值的相关系数.在返青期,NDVI与RVI估算效果相当(估算模型R2分别为0.7957,0.8027).在拔节期、抽穗期、灌浆期,NDVI估算效果较好(估算模型R2分别为0.8096,0.7557,0.5033).

The canopy hyperspectral reflectance and chlorophyll content （ SPAD ） of winter wheat were measured by the ASD portable spectrometer and portable chlorophyll meter SPAD-502. The SPAD estimation models of winter wheat were established based on NDVI,RVI in different growth periods. The results showed that the spectral reflectance was negatively correlated with SPAD in visible bands,while the correlation coeffi-cient was positively near the red edge from reviving to heading. The correlation coefficient of first derivative spectral reflectance and SPAD were better than that of canopy reflectance and SPAD in some bands. At the re-greening stage,the SPAD estimation model based on NDVI has about the same accuracy as the SPAD estima-tion model based on RVI（R^2=0. 7957,0. 8027,respectively）. The SPAD estimation models based on NDVI （ R^2=0. 8096,0. 7557,0. 5033,respectively） were better than that based on RVI at the elongation stage,head-ing stage and filling stage.