镉胁迫水稻潜热通量与冠层结构参数变化遥感分析

Cadmium stress analysis based on the changes in latent heat flux and canopy structural parameter of rice using remotely sensed data

为了更准确地监测农田水稻镉污染状况,结合水稻冠层能量平衡和结构参数LAI(Leaf area index),构建水稻生理功能敏感指数P_f(Physiological function sensitivity index),分析水稻镉胁迫水平:首先利用遥感影像数据和实测数据,基于能量平衡模型模拟实验区水稻潜热通量LE(Latent heat flux),然后结合LE与LAI构建水稻生理功能敏感指数P_f,最后根据P_f识别水稻镉胁迫。结果表明,镉胁迫越重水稻LE、LAI和P_f值越小,LE可将水稻镉胁迫区分为重度和轻度/中度两个水平;LAI可将水稻镉胁迫区分为中度/重度和轻度胁迫两个水平;P_f能更好地将水稻镉胁迫区分为轻度、中度和重度三个水平,其区分准确度分别为70.59%、69.05%和84.79%。P_f能有效诊断并定量分析水稻镉污染胁迫状况,为作物重金属污染监测提供重要参考。

A physiological function sensitivity index（Pf）, created by combining the rice canopy energy balance model and the structural pa-rameter Leaf Area Index（LAI）, is proposed in order to analyze the cadmium stress level of rice. Firstly, the latent heat flux（LE）of rice was simulated based on an energy balance model using remote sensing and in situ measured data, and then the Pf, which can reflect the physio-logical function of rice, was developed using LE and the LAI. Finally, the cadmium stress in rice was evaluated using the Pf. The results show that higher cadmium stress generally corresponds to smaller values of LE, the LAI, and the Pf. LE could only distinguish high cadmium stress from other levels（medium/low）and the LAI could only discriminate high and medium cadmium stress from low stress;however, the Pf could differentiate the three levels of cadmium stress of rice. The classification accuracies of Pf for high, medium, and low stress were 70.59%, 69.05%, and 84.79%, respectively. Pf can effectively discriminate different cadmium stress levels;therefore, it is an important ref-erence for monitoring heavy metal stress of crops.