马铃薯叶片光化学吸收与反射光谱关联分析及检测

Correlation Analysis and Detection of Photochemical Absorption and Reflectance Spectra of Potato Leaves

为开展马铃薯叶片PSⅡ叶绿素荧光参数无损检测研究,利用高光谱成像系统采集200个感兴趣区域样本点的光谱图像并提取反射率,使用封闭式叶绿素荧光成像系统采集相应样本点的qP值。采用SPXY算法将总样本按照2∶1的比例划分为建模集(135个样本)和验证集(65个样本),采用联合区间偏最小二乘法(Synergy interval partial least squares,siPLS)和随机蛙跳(Random frog,RF)算法各筛选出18个敏感波长,并用选择的特征波长建立偏最小二乘回归(Partial least squares regression,PLSR)模型。结果表明:siPLSPLSR模型的建模集决定系数R2c为0.6285,验证集决定系数R2v为0.6103;RFPLSR模型的建模集决定系数R2c为0.7093,验证集决定系数R2v为0.6872。结果表明利用RF算法筛选的特征波长对马铃薯叶片qP值检测的解释性优于siPLS算法,特征波长在518.72~640.64 nm、650~800 nm和850~1000 nm范围,体现了荧光发射信号是马铃薯作物光化学吸收qP值的重要响应特征,且叶片光化学吸收与叶绿素含量、叶片结构、水分含量等属性紧密关联。绘制叶片qP值分布图为分析马铃薯叶片光化学吸收和光合作用动态提供了直观的分析手段,可为马铃薯作物光合活性评价及复杂生理生化动态监测提供支持。

In order to carry out the non-destructive detection of chlorophyll fluorescence parameters of potato leaves,hyperspectral images of 200 regions of interest(RoI)were collected and the average reflectance was extracted.Then qP values of the corresponding areas were measured by the closed chlorophyll fluorescence imaging system of Fluorcam.Sample set partitioning based on joint XY distance(SPXY)algorithm was used to divide the samples into calibration set(135 samples)and validation set(65 samples)according to the ratio of 2∶1.Algorithms of synergy interval partial least squares(siPLS)and random frog(RF)were used to select feature wavelengths,and the partial least squares regression(PLSR)model was established with the selected wavelengths.The results showed that the calibration accuracy of siPLSPLSR model was 0.6285,the validation accuracy was 0.6103,and the calibration accuracy of RFPLSR model was 0.7093,the validation accuracy was 0.6872.The interpretation of potato leaves by RF method was better than that by siPLS method.Selected wavelengths mainly distributed in the range of 518.72~640.64 nm,650~800 nm and 850~1000 nm,which reflected that fluorescence emission signal was an important response characteristic of photochemical absorption in potato crops.And it also showed that the photochemical absorption was closely related to chlorophyll content,leaf structure,water content and other attributes.The mapping of qP values distribution in leaves provided an intuitive method for the analysis of photochemical absorption and photosynthesis dynamics of potato leaves.The study provided a way for the evaluation of photosynthetic activity,which could also be applied in monitoring of complex physiological and biochemical dynamic of potato crops.