不同品种夏玉米光谱特征差异及其与农学参量相关性研究

Differences of Spectral Reflectance,and Correlation Between Reflectance and Agronomical Parameters in Different Cultivars of Summer Maize

研究测定了不同品种夏玉米在六个典型生育期地上部分全氮、叶绿素含量、干生物量、叶面积指数(LAI)以及冠层光谱反射率,利用不同方法比较了不同品种玉米光谱特征的差异,系统分析了单波段反射率、可见光和近红外波段组合而成的8种常见植被指数与相应时期不同农学参量的相关性。结果表明:不同品种夏玉整个生育期不同品种冠层在可见光范围内反射率差异一直没有达到显著水平,苗期和拔节期在近红外区域反射率也无显著差异,从孕穗期到乳熟期在近红外区域反射率差异增大,普遍呈显著性差异。采用F检验法可以准确地反映不同品种在不同波段反射率的差异。常见光谱植被指数从拔节期到孕穗期绝大部分都可以准确反映不同品种夏玉米的农学参量,以GRVI最佳,它不仅可以区分不同品种夏玉米在中后期的长势,又可以准确拟合这段时期作物的农学参量。

At six typical growth stages of different cultivars in summer maize,field experiments were conducted to measure total nitrogen of above ground,chlorophyll content,dry biomass,leaf area index（LAI） and canopy spectral reflectance,to study the contrast of reflectance between different cultivars in summer maize with different methods,and to analyze the correlation between the single wavebands,NDVI/RVI and other vegetation indices that visible light and near infrared combined and agronomical parameters.The results showed that：there were differences of reflectance in different cultivars of summer maize.Non-significant difference occurred in visible light reflectance at each stage and in near-infrared at former stages;however,reflectance difference became larger and significant difference occurred in near-infrared region from booting to filling.Using F-test can reflect the difference of reflectance in different wavelengths accurately and precisely.Agronomical parameters can be estimated exactly by major vegetation indices,and GRVI was the best.GRVI（560,760） could not only distinguish growth status of different cultivars from middle to latter stages,but also simulate the parameters precisely.