雷竹冠层叶片反射光谱特征及其对叶片水分变化的响应

王鑫梅; 张劲松; 潘庆梅; 谢锦忠; 张玮; 孟平

doi:10.13275/j.cnki.lykxyj.2019.03.010

雷竹冠层叶片反射光谱特征及其对叶片水分变化的响应

Spectral Reflectance Characteristics of Phyllostachys violascens Canopy Leaves in Response to Water Change

摘要

摘要:
目的研究雷竹冠层叶片反射光谱特征及其水分敏感波段，筛选与叶片水分指标相关性较高的光谱指数，为雷竹叶片水分的非破坏性估算提供参考。
方法以重要笋用竹种雷竹为研究对象，通过自然失水法研究叶片反射光谱对叶片水分变化的响应特征，以常用反射光谱指数对叶片水分指标进行相关性检验，对不同反射光谱指数与叶片相对含水量进行了回归方程拟合。
结果雷竹叶片含水量与其光谱反射率在近红外区呈负相关关系；光谱反射率敏感性分析表明，在1 400~1 600、1 800~2 000 nm波段附近，光谱反射率对叶片水分变化较其他波段敏感；不同光谱指数与叶片水分指标的相关性分析及回归方程拟合结果表明，在所选光谱指数中水分胁迫指数MSI（R₈₂₀/R₁₆₀₀）、比值指数SRI（R₁₃₀₀/R₁₄₅₀）与叶片相对含水量的拟合效果较好。
结论雷竹叶片水分含量与其光谱反射率在近红外区，尤其1 400~1 600、1 800~2 000 nm波段附近呈负相关关系，水分胁迫指数MSI（R₈₂₀/R₁₆₀₀）、比值指数SRI（R₁₃₀₀/R₁₄₅₀）对雷竹叶片相对含水量的估算精度较其它光谱指数更高。

Abstract:
Objective To study the water-sensitive reflectance spectra bands of Phyllostachys violascens canopy leaves and screen the suitable reflectance spectral indexes of leaf water content, aiming at nondestructive estimation of leaf water content.
Method The present study investigated the canopy leaf reflectance spectrum characteristics of Ph. violascens during isolated natural water loss process. The correlation between reflectance spectral indexes and leaf water indicators were calculated and analyzed. The regression equation between leaf relative water content (RWC) and reflectance spectral indexes were also calculated.
Result The leaf water content and its spectral reflectance were negatively correlated in the near-infrared region. The spectral reflectance sensitivity analysis showed that the spectral reflectance in 1 400~1 600 nm and 1 800~2 000 nm was significantly changed with the decrease of the leaf water content. Correlation analysis and regression model between different spectral reflectance indexes and RWC showed that moisture stress index MSI(R₈₂₀/R₁₆₀₀)and simple ratio index SRI(R₁₃₀₀/R₁₄₅₀) had higher correlation with RWC.
Conclusion The leaf water content has negative correlation with the spectral reflectance in the near-infrared region especially 1 400~1 600 nm and 1 800~2 000 nm. The MSI(R₈₂₀/R₁₆₀₀) and simple ratio index SRI(R₁₃₀₀/R₁₄₅₀) has higher accuracy for estimating RWC of Ph. violascens leaves than other reflectance spectral indexes.

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