高温胁迫下基于高光谱成像的茄子萎蔫程度判别

Discrimination of eggplant wilting degree under high temperature stress based on hyperspectral imaging

  • 摘要: 【目的】建立基于高光谱成像技术的茄子幼苗萎蔫程度无损判别方法,开展高温胁迫下基于高光谱成像判别茄子萎蔫程度研究,为茄子耐热性高通量精准鉴定及耐热茄子种质资源高通量筛选提供参考依据。【方法】以高温敏感茄子自交系KY幼苗植株为研究对象,采用SOC710VP高光谱成像系统(光谱分辨率1.3 nm,光谱范围400~1000 nm),采集高温胁迫后茄子幼苗不同萎蔫等级植株的冠层图像。对比无处理和标准正态变量变换(SNV)、标准化(AUT)、归一化(NOR)、Savitzky-Golay平滑(SG)、多元散射校正(MSC)5种预处理方法的效果。基于Kennard-Stone算法划分训练集和测试集,分别构建偏最小二乘判别分析(PLS-DA)和支持向量机(SVM)的全波段及基于竞争性自适应重加权算法(CARS)提取特征波段的萎蔫等级判别模型。【结果】不同萎蔫等级茄子植株的平均反射率存在差异,在400~1000 nm波段的平均反射率随萎蔫等级升高而降低。与无处理相比,5种预处理均能够有效降低杂散光的噪声,其中SG处理能消除随机信号,提高样本的信噪比。在PLS-DA模型中,SG预处理后的模型判别效果最佳,训练数据集与测试数据集的准确率分别达97.00%和98.00%。采用CARS提取特征波段可有效减少数据维度,其中结合SG预处理所建模型的性能最优。SVM模型中,采用不同核函数时,SNV预处理结合线性核函数、SG预处理结合多项式核函数均取得较高的判别准确度。综合比较,SG-PLS-DA模型性能稳定且判别效率高。【结论】高光谱成像技术可用于茄子萎蔫程度的快速评价,SG预处理方法结合PLS-DA判别模型可实现茄子幼苗高温胁迫后萎蔫程度的快速、无损和准确判别,为茄子耐热表型的高通量鉴定提供可行方法。

     

    Abstract: 【Objective】This study aimed to establish a non-destructive discrimination method for the eggplant seedling wilting degree based on hyperspectral imaging technology,and to conduct research on discrimination of eggplant wilting degree under high temperature stress based on hyperspectral imaging,thereby providing reference for high-throughput precise identification of eggplant heat tolerance and high-throughput screening of heat-tolerant eggplant germplasm resour-ces.【Method】The seedlings of eggplant inbred line KY sensitive to high temperature were used as the research objects. The SOC710VP hyperspectral imaging system(with a spectral resolution of 1.3 nm and a spectral range of 400-1000 nm)was used to collect canopy images of eggplant seedlings at different wilting levels after high temperature stress. The effects of five pretreatment methods,including variable transformation (SNV), autoscaling (AUT), normalization (NOR), Savitzky-Golay smoothing (SG), and multiplicative scatter correction (MSC), were compared. Based on the training set and test set divided by the Kennard-Stone algorithm, a wilting level discrimination model was constructed using partial least squares discriminant analysis (PLS-DA) and support vector machine (SVM) with full bands and feature bands extracted by the competitive adaptive reweighted sampling (CARS) algorithm.【Result】Differences were found in the average reflectance of plants at different wilting levels,and the average reflectance in the 400-1000 nm band decreased with the increase of wilting levels. All five pretreatments could effectively reduce the noise of stray light compared with the situation without treatments,among which the SG treatment could remove random signals and improve the signal-to-noise ratio of samples. In the PLS-DA model,the model after SG pretreatment showed the best discrimination effect,with the accuracy of the training data set and test data set reaching 97.00% and 98.00% respectively. The use of CARS to extract feature bands could effectively reduce data dimensions,and the model performance was optimal when combined with SG pretreatment. In the SVM model applying different kernel functions, higher discrimination accuracy was achieved under SNV pretreatment combined with linear kernel function and SG pretreatment combined with polynomial kernel function. Overall,the SG-PLS-DA model had stable performance and high discrimination efficiency.【Conclusion】The hyperspectral imaging technology is applicable for rapid evaluation of wilting degree of eggplant. The combination of SG pretreatment and PLS-DA discrimination model can achieve rapid,non-destructive, and accurate discrimination of wilting degree of eggplant seedlings after high temperature stress,thereby providing a feasible method for high-throughput identification of heat-tolerant eggplant phenotypes.

     

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