基于高光谱指数的叶片尺度叶绿素荧光参数反演

Retrieval of Leaf-scale Chlorophyll Fluorescence Parameters Based on Hyperspectral Index

在叶片尺度上,基于高光谱植被指数反演实际光合速率(Phi2)、非调节的光能耗散(PhiNO)、非光化学淬灭(PhiNPQ)、相对叶绿素含量(RC)4个叶绿素荧光参数,分析不同氮素处理下叶片光谱反射率和4个叶绿素荧光参数在不同时期的变化特征。结果表明,可见光波段在过量施氮下叶片反射率低于不施氮处理;在近红外波段,叶片光谱反射率随着施氮量的增大而增大。随着玉米的生长,不施氮处理下Phi2逐渐减少,PhiNPQ逐渐增加;过量施氮下Phi2先增加后减少,PhiNO和PhiNPQ先降低后增加。RC在不同施氮条件下均随着生育时期发展先增加后减少。Phi2和PhiNPQ与归一化植被指数(NDVI)的相关性最好,PhiNO与改进型叶绿素吸收比值指数(MCARI)的相关性最好,RC与红边植被指数(CIred edge)的相关性最好。

In this study, hyperspectral vegetation indices based on leaf scale hyperspectral reflectance were se-lected to estimate the chlorophyll fluorescence parameters including actual photosynthetic rate(Phi2), non-regulato-ry energy dissipation(Phi NO), non-photochemical quenching(Phi NPQ), and relative chlorophyll content(RC). Be-sides, the leaf spectral reflectance and chlorophyll fluorescence parameters dynamic characteristics were analyzedunder different nitrogen treatments. The results showed that, with a rise of N treatment rate, spectral reflectance de-creased in visible wavelength with increasing N level, opposite trends were found in the near-infrared region. Underzero nitrogen application, the Phi2 decreased with the development of maize growth period, while the Phi NPQ in-creased with the development of maize growth period. Under the treatment of excessive nitrogen application, thePhi2 increases at the beginning and then decreases, while Phi NO and Phi NPQ decreases firstly and then increases.Under different nitrogen treatments, RC increases firstly and then decreases with the development of the growth peri-od. The Phi2 and Phi NPQ have the best correlation with the normalized difference vegetation index(NDVI), the Phi-NO has the best correlation with Modified chlorophyll absorption ratio index(MCARI), and RC has the best correla-tion with Red edge model(CIred edge).