基于高光谱植被指数的西北玉米不同时期叶绿素含量估测

Hyperspectral vegetation index monitoring of chlorophyll content of different corn growth stage in Northwest China

以陕西省扶风县马席村、巨良农场和杨凌区揉谷乡种植的大田玉米为试验材料,分别测定玉米抽雄期、灌浆期和乳熟期的冠层光谱反射率和叶片叶绿素含量,分析冠层各光谱植被指数与叶片叶绿素含量之间的相关关系,建立玉米叶绿素含量估测模型。结果表明,以单变量光谱植被指数估算叶绿素含量,抽雄期的最佳模型由修正叶绿素吸收反射率指数(Modified chlorophyll absorption reflectivity index,MCARI)建立,灌浆期最佳模型由垂直植被指数(Perpendicular vegetation index,PVI)建立,乳熟期最佳模型由植被衰老反射率指数(Plant senescence reflectance index,PSRI)建立。随着玉米生长期的推进,叶片衰老,用PSRI所建立的模型来监测玉米叶绿素含量的效果较好,可为高光谱遥感在玉米长势监测提供理论依据和技术支持。

Aiming to promote the hyperspectral vegetation index application in corn condition monitoring.Field corns in Maxi,Juliang and Yangling area were used to establish the quantitative relationship between spectral vegetation index and the corn chlorophyll content.The canopy spectral reflectance and chlorophyll content were measured at tasseling stage,filling stage and milk stage.The coefficient between them was analyzed.And the relationship between them was used to establish the corn chlorophyll content monitoring model.The results showed that the best vegetation index to estimate the chlorophyll content was the modified chlorophyll absorption reflectivity index（MCARI）at the stage of tasseling.At the stage of filling,the best vegetation index to estimate the chlorophyll content was perpendicular vegetation index（PVI）.And plant senescence reflectance index（PSRI）was the best at the stage of the milk stage.Along with the plant growth and leaf senescence,a PSRI model was proved to be valid for monitoring the corn chlorophyll content.It provided theoretical basis and technical support for the hyperspectral remote sensing in the corn growth monitoring.