Neither Cadmium (Cd) nor lead (Pb) is necessary for crop growth, and they both cause severe soil pollution in many countries. A cross‐stress experiment was designed to investigate the feasibility of diagnosing the type and the level of Cd–Pb cross‐stress by observing rice canopy hyperspectral images. Two‐way analysis of variance and random forest algorithm were employed to select the sensitive indices for Cd–Pb cross‐stress diagnosing. Following the exploration of bandwidth expansion from 1 to 20 nm, the final sensitive indices were proposed. We proposed two indices for distinguishing the two heavy metals named: the cadmium stress vegetation index (CSVI) and the lead stress vegetation index (LSVI). The diagnostic accuracies of CSVI distinguishing the four different Cd‐stressed levels (0, 2, 5, 8 mg L⁻¹) reached 0.85, 0.92, 0.96, and 0.92, respectively, while the precision for four Pb‐stressed levels (0, 50, 100, 500 mg L⁻¹) based on the LSVI were 0.92, 0.94, 0.96, and 0.96, respectively. The two indices are CSVI = [(R₇₇₂ + R₇₇₃ + R₇₇₄ + … + R₇₈₉) ‐ ( R₇₅₄ + R₇₅₅ + R₇₅₆ + … + R₇₇₁)]/18, LSVI = [(R₇₁₁ + R₇₁₂ + R₇₁₃ + … + R₇₁₈) – (R₇₀₃ + R₇₀₄ + R₇₀₅ + … + R₇₁₀)]/8, located in near‐infrared ranges with 18 and 8 nm bandwidth, respectively. Therefore, it was feasible to diagnose the type and the level of Cd–Pb cross‐stress by examining the hyperspectral dataset of the rice canopy. Finally, the experiment compared the diagnostic ability of the proposed indices with the typical spectral indices for the physiological characterization of rice. The results showed that the proposed indices had state‐of‐the‐art distinguishing accuracies.

中文翻译：

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两种高光谱指数，可从Arice冠层光谱中检测镉和铅污染

作物生长不需要镉（Cd）和铅（Pb），它们在许多国家都造成严重的土壤污染。设计了交叉应力实验，通过观察水稻冠层高光谱图像来研究诊断Cd-Pb交叉应力的类型和水平的可行性。采用方差的双向分析和随机森林算法来选择Cd–Pb交叉应力诊断的敏感指标。在探索从1到20 nm的带宽扩展之后，提出了最终的敏感指标。我们提出了两个指数来区分两种重金属：镉胁迫植被指数（CSVI）和铅胁迫植被指数（LSVI）。CSVI的诊断准确性可区分四种不同的Cd应激水平（0、2、5、8 mg L ^-1）分别达到0.85、0.92、0.96和0.92，而基于LSVI的四个Pb应力水平（0、50、100、500 mg L ^-1）的精度分别为0.92、0.94、0.96和0.96 。这两个索引是CSVI = [（R ₇₇₂  +  R ₇₇₃  +  R ₇₇₄  +…+  R ₇₈₉）-（R ₇₅₄  +  R ₇₅₅  +  R ₇₅₆  +…+  R ₇₇₁）] / 18，LSVI = [（R ₇₁₁  +  R ₇₁₂  +  R ₇₁₃  +…+  R ₇₁₈）–（R₇₀₃  +  R ₇₀₄  +  R ₇₀₅  +…+  R ₇₁₀）] / 8，分别位于18和8 nm带宽的近红外范围内。因此，通过检查水稻冠层的高光谱数据集来诊断Cd–Pb交叉应力的类型和水平是可行的。最后，实验比较了所提出指标与典型光谱指标对水稻生理特性的诊断能力。结果表明，提出的指数具有最新的区分精度。