检疫性杂草假高粱与近缘植物种子的波谱鉴别方法

Seed identification between Sorghum halepense (aquarantine weed) and its closed species based on ultraviolet spectrum

为便于出入境检验检疫部门正确、快速地鉴别出假高粱[Sorghumhalepense（L．）Pers]及其近缘种，以石油醚作为溶剂，获取了假高粱、高梁[Sorghum bicolor（L．）Moenchi、黑高粱（Sorghum almum Parodi）和苏丹草[Sorghumsudanense（Piper）Stapf]种子12份样品的浸提液，应用UnicamUV540型紫外分光光度计，将狭缝设置成1nm，扫描速率0．5s，获得了200～400nm波长范围内每种植物种子在200个紫外波段上的吸光度．借助于SPSS16．0软件，应用单因素方差分析，过滤掉差异性小的波段，明确了假高粱与近缘植物种子问存在显著和极显著差异的63个波段．对这63个波段上的吸光度数据应用主成分分析进一步筛选出了信息负荷量大的18个波段．以这18个波段上的吸光度数据为指标，以12个样品为对象，做出了它们的紫外光谱图、聚类图和二维排序图．上述方法能较好地将假高粱与其他3种近缘杂草种子鉴别开．为比较通过单因素方差分析和主成分分析后筛选的光谱数据对鉴别假高粱与其他3种近缘植物种子的效果，直接基于200个波长上的吸光度数据，应用相同的软件和参数，也做出了假高梁、高粱、黑高粱和苏丹草12个样品的紫外光谱图、聚类图和二维排序图，说明筛选出的这些敏感波段能够更简便、有效地识别假高梁和其近缘植物种子，为今后应用紫外光谱法鉴别假高粱与同属近缘的其他3种植物种子提供了技术参数．

Summary Sorghum halepense （L.） Pers is an important quarantine weed, which is native to the Mediterranean region, and now is considered as one of the ten worst weeds in the world. The species is mainly dispersed by seeds. Sorghum almum Parodi is also an important weed, and Sorghum bicolor （L.） Moench and Sorghum sudanense （Piper） Stapf are two cultivated plants. Due to their morphological similarity, it is difficult for entry-exit inspection and quarantine departments to properly and quickly identify the seeds of S. halepense from those of its closed species. Therefore, how to identify the seeds of S. halepense from those of its congeneric species is urgently needed. In this paper, seeds from the above four species were extracted with petroleum ether to get their extractions, which were analysed by ultraviolet （UV） spectrophotometer （Unicam UV540） to get 200 UV absorbance data within 200- 400 nm with 1 nm slit and at a scan rate of 0.5 s. From these 200 absorbance data, the sensitive wavelengths whose absorbance data could be separated each other were firstly identified by SPSS 16.0 using one- way analysis of variance （ANOVA）. From these preliminarily-selected sensitive wavelengths, more sensitive wavelengths with high information load were further identified by principal component analysis （PCA）. With the absorbance data of these informative wavelength spectra in relation to four species, both cluster analysis and PCA were applied to produce a dendrogram and a two-dimensional scatter plot, respectively. In order to verify the effect of the informative wavelengths which were selected by one-way ANOVA and PCA, a spectrum chart, a dendrogram, a two-dimensional scatter plot from PCA were directly produced on the basis of the absorbance data corresponding to the 200 wavelengths. According to the above procedures, sixty-three wavelengths were preliminarily seleeted by using ANOVA. From these wavelengths, eighteen informative wavelengths from 283 to 300 nm with a step of 1 nm were identified by PCA. On the dendrogram, the scatter plot and the spectrum chart produced based on these eighteen informative wavelengths, the seed samples of S. halepense and its three congeneric species were well separated each other. All these three schemes were better than those on the basis of the absorhanee data corresponding to the 200 wavelengths in the seed identifieation of these four Sorghum species. The above results indicate that the extraction scheme with petroleum ether, and the selected eighteen informative wavelengths by ANOVA and PCA, as well as the charts by cluster analysis, PCA, or directly based on absorbance data are effective to identify the seeds of S. halepense from those of S. bicolor, S. almum and S. sudanense .