Studies on wheat canopy structure by hyperspectral remote sensing

Chino. 选择株型差异较大的冬小麦品种，并通过部分品种不同密度试验，分析了冠层结构的两个重要指标叶向值（LOV）与叶面积指数（LAI）与光谱特征参量的关系，同时对20个不同处理进行了聚类分析。结果表明，不同生育阶段株型指标LOV和群体大小指标LAI对光谱的贡献是不同的，前期（以拔节期为主）LOV对光谱的影响要大些，后期主要受LAI的影响；对拔节期包括品种和密度在内的共20个处理进行聚类分析，划分了株型和群体大小的不同组合4个（A-株型直立，群体较小；B-株型直立，群体较大；C-株型披散，群体较小；D-株型披散，群体较大）；拔节期不同类组冠层光谱反射率在400～700 nm范围内反射率由高到低的顺序为ABCD，700～1 150 nm范围内顺序与其相反，并且差异更加显著，此期是利用光谱识别株型的最佳时期；利用近红外波段光谱特征值（拔节期到孕穗期光谱反射率的增量△R890与拔节期反射率R890）做散点图发现，不同类组在散点分布上具有显著差异，通过纵向反射率的差异以及横向两个阶段反射率增量的差异可以对不同群体冠层结构特征进行初步识别。

Inglés. Some wheat varieties were selected in this experiment, and different density treatments were arranged. The results were as follows: 1) Leaf Orientation Value (LOV) and Leaf Area Index (LAI) of wheat had different contributions to canopy spectra, for example, LOV affected greatly canopy spectra more than LAI in jointing stage, but LAI had more effects on spectra after the ground was near to be covered completely. 2) 20 treatments including different varieties and densities were arranged in this experiment, the result of cluster analysis showed that all these treatments can be parted into four clusters: A-erect type and low LAI, B-erect type and high LAI, C-horizontal type and low LAI, D-horizontal type and high LAI. Their spectral reflectance had obvious difference in 400-700 nm and 700-1 150 nm at jointing, which indicated that jointing stage was an important stage in plant type recognition. 3) There was an obvious distribution difference among different clusters in scatter plot (X=△R890, Y=R890), △R890 was the reflectance dispersion of booting stage and jointing stage. It was seen from the Y-axis direction that R890 of a horizontal type variety was higher than erect type ones, and seen from the X-axis direction, the greater △R890 was the lower population one within the same type varieties, which indicted that the combination of plant-type and the population magnitude can be identified qualitatively by this method.