水稻细条病对叶片反射率和日光诱导叶绿素荧光的影响

Effect of rice bacterial leaf streak on leaf reflectance and solar-induced chlorophyll fluorescence

【目的】研究水稻细条病对叶片反射率和日光诱导的叶绿素荧光(SIF)的影响,为水稻细条病的多源遥感监测研究提供参考。【方法】以大田自然发病水稻为研究对象,分别采集健康和不同感病程度叶片的叶绿素、反射率光谱和SIF光谱,分析不同感病程度下叶片反射率和SIF光谱的变化特征及其相应的植被指数和SIF产量指数变化特征,并且综合植被指数和SIF产量指数构建病害等级监测模型。【结果】随着病害程度加重,叶片叶绿素含量呈现梯度递减趋势;健康和感病叶片之间的反射率光谱和SIF光谱呈现显著差异;基于反射率的植被指数随病害程度的加重呈现梯度变化规律;近红外波段(740 nm)SIF产量指数随病害程度的加重呈现梯度变化规律,而红光波段(685 nm)SIF产量指数仅在健康至中度感病阶段呈现梯度变化规律;基于全波段(650~850 nm)的SIF产量指数在健康、轻度和中度感病时差异较小,在重度感病时差异显著;植被指数与病害等级的相关性整体强于SIF产量指数,其中,简单比值指数(SR)模型预测精度最高,R2达到0.899。【结论】针对已有明显细条病病斑的叶片,植被指数的监测效果整体优于SIF产量指数。

【Objective】The effect of bacterial leaf streak(BLS)on rice leaf reflectance and solar-induced chlorophyll fluorescence(SIF)was studied to provide reference for the multi-source remote sensing monitoring of BLS.【Method】Rice leaves with BLS in the field were monitored on chlorophyll content,reflectance spectra,and SIF spectra,then the variation trends of reflectance spectra and SIF spectra under different BLS levels,and the corresponding vegetation index and SIF yield index were interpreted to construct a BLS-level monitoring model.【Result】The chlorophyll content of leaves showed a gradient decreasing trend with the development of BLS,with remarkable differences in leaf reflectance and SIF spectra between the healthy and infected leaves.The vegetation index based on reflectance and SIF yield index at near-infrared(740 nm)both showed gradient changes with the development of BLS,while SIF yield index at red wavelength(685 nm)only changed gradually among the healthy,slight and moderate infected leaves.The SIF yield index based on full-spectrum(650 to 850 nm)showed small variation among the healthy,slight and moderate infected leaves,but changed significantly among the severely infected leaves.The correlation between vegetation index and BLS level was higher than that between SIF yield index and BLS level,and the simple ratio index(SR)model showed the highest prediction accuracy with R2 reaching 0.899.【Conclusion】For diseased leaves with obvious lesion,the accuracy of monitoring BLS through vegetation index is generally higher than that of SIF yield index.