Spectral feature analysis for assessment of water status and health level in coast live oak (Quercus agrifolia) leaves
Spectral feature analysis for assessment of water status and health level in coast live oak (Quercus agrifolia) leaves
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DOI：
10.1080/01431160410001705114
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发表时间：
2004-10
影响因子：
3.4
通讯作者：
R. Pu;L. Foschi;Peng Gong
中科院分区：
文献类型：
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作者：
R. Pu;L. Foschi;Peng Gong
从306个海岸生栎（Quercus agrifolia）叶片样品的反射率和相对含水量（RWC %）进行了测定。从沿着每条光谱反射率曲线的10个光谱斜率中提取最大（或最小）一阶导数（1D）及其相应的波长位置（WP）。这些光谱特征（1Ds和WP）和相应的RWC的橡树叶之间进行了相关性分析。还分析了两个健康水平的橡树叶，健康和感染的光谱特征和RWC之间的方差。结果表明，橡树叶片的一些导数光谱特征（1Ds和WPs）与RWC之间存在较高的相关性。所有306个叶谱覆盖了广泛的橡树叶RWC（包括健康、受感染和新死亡），最大在1200附近的吸收谷两侧的（或最小）导数值，发现1400和1940 nm谷的波长和1200 nm谷右侧的波长以及1400 nm和1940 nm谷两侧的波长具有高相关性与RWC;并且选择260个仅为绿色和绿黄色叶片的样品（仅包括健康和感染水平），在1400 nm谷的右侧、在1940 nm谷的左侧和在红色孔处的WP各自与叶片RWC具有稳定的关系。对20个光谱特征的方差分析结果表明，在0.95置信水平下，两个健康水平对应的部分光谱特征差异显著，尤其是上述波长位置特征差异显著。
Reflectance and relative water content (RWC %) were measured from a total of 306 coast live oak (Quercus agrifolia) leaf samples. The maximum (or minimum) first derivative (1D) and its corresponding wavelength position (WP) were extracted from 10 spectral slopes along each spectral reflectance curve. A correlation analysis was conducted between these spectral features (1Ds and WPs) and the corresponding RWC of oak leaves. An analysis of the variance of spectral features and RWC was also carried out between two health levels of oak leaves, healthy and infected. The results indicate that high correlations exist between some derivative spectral features (1Ds and WPs) and the RWC of oak leaves. With all 306 leaf spectra covering a wide range of RWC of oak leaves (including healthy, infected and newly dead), maximum (or minimum) derivative values at both sides of the absorption valleys near 1200, 1400 and 1940 nm and the WP of the right side of the 1200 nm valley and of both sides of the 1400 nm and 1940 nm valleys were found to have high correlations with RWC; and with a selection of 260 samples of only green and green–yellowish leaves (including only healthy and infected levels), the WPs at the right side of the 1400 nm valley, at the left side of the 1940 nm valley and at the red well each have a stable relationship with leave RWC. The result of an ANOVA of 20 spectral features suggests that the difference of some spectral features corresponding to two health levels of oak leaves is significant at a 0.95 confidence level, especially for the above-mentioned wavelength position features.