激光诱导击穿光谱的油茶炭疽病检测

Detection of Anthracnose in Camellia Oleifera Based on Laser-Induced Breakdown Spectroscopy

油茶产业具有良好的经济和生态效益,深受国家重视。目前,炭疽病侵害油茶树日益加重,严重地降低了产量,导致油茶产业的效益直接受损。所以找到一种快速、准确、方便的油茶炭疽病检测方法是非常必要的。激光诱导击穿光谱(LIBS)是一种低成本、微损伤、无残留的技术,能够对多种成分快速实时检测。采用LIBS结合化学计量学方法对油茶炭疽病的定性检测方法进行研究。实验样品采摘于油茶种植区,分别采集了100片健康油茶叶片和100片感染炭疽病的油茶叶片。将采集的叶片进行微处理,即首先进行反复冲洗去除叶片表面污渍,然后进行分类、装袋和标号,最后进行LIBS光谱采集实验。实验设备为海洋光学的MX2500+, LIBS实验参数设置为激光能量50 mJ,最优延迟时间2μs,每个叶片采集6条光谱数据,并求其平均。在油茶叶片LIBS光谱的波长251.432 nm处观察到Si的特征峰、分别在252.285, 259.837和385.991 nm处观察到Fe的特征峰、分别在260.568, 279.482和280.108 nm处观察到Mn的特征峰。实验结果:油茶叶片中的微量元素Si, Fe, Mn的LIBS信号与油茶叶片的健康程度有直接关系,健康油茶叶片中Si, Fe和Mn的特征峰强度明显高于感染炭疽病的油茶叶片中Si, Fe和Mn的特征峰强度;此外,利用LIBS技术结合MSC光谱预处理和PCA分类法,对油茶叶片的健康和感染炭疽病的两个状态进行分类处理。PC1, PC2和PC3的贡献率分别为80%, 12%和6%,建立三维模型分类,可以清晰地将油茶叶片的两种状态区分出来。同时,还利用PLS-DA建立模型,模型的识别率高达90%以上,可以对油茶叶片两种类别进行较好的分类。以上两种化学计量方法都可以区分油茶叶片的健康和染病两种状态。研究表明了利用LIBS技术检测油茶炭疽病是可行的。可以利用LIBS技术对油茶叶片的微量元素和营养元素进行定量检测,为定量检测提供了参考。提出了一种快速检测油茶炭疽病的新方法。

The camellia oleifera industry has good economic and ecological benefits, and is highly valued by the state. At present, the anthracnose disease encroaches camellia oleifera tree day by day aggravates, reduces the production seriously, causes the benefit of camellia oleifera industry to suffer directly. So it is necessary to find a fast, accurate and convenient method for anthracnose detection. Laser-Induced Breakdown Spectroscopy(LIBS) is a low-cost, slightly damaged, and no-residue technology that can quickly and real-time detect a variety of ingredients. The qualitative detection method of anthracnose of camellia oleifera was studied by LIBS combined with stoichiometry. The samples were collected from the camellia oleifera planting area. 100 healthy camellia oleifera leaves and 100 anthracnose infected camellia oleifera leaves were collected respectively. The collected blades were micro-treated, namely, the surface stains of the blades were washed repeatedly to remove, then classified, bagged and labeled, and finally LIBS spectrum acquisition experiment was carried out. The experimental equipment was MX2500+ of ocean optics, the LIBS experimental parameters were set as 50 mJ laser energy, and the optimal delay time was 2. Six spectral data were collected from each blade and averaged. The characteristic peak of Si was observed at 251.432 nm of the LIBS spectrum of camellia oleifera leaves, and the characteristic peak of Fe was observed at 252.285, 259.837 and 385.991 nm, and the characteristic peak of Mn was observed at 260.568, 279.482 and 280.108 nm, respectively. Results: the LIBS signals of trace elements Si, Fe, Mn in camellia oleifera leaves are directly related to the health degree of camellia oleifera leaves. In addition, this experiment used LIBS technology combined with MSC spectral pretreatment and PCA classification to classify the two states of camellia oleifera leaf health and anthracnose infection. The contribution rates of PC1, PC2 and PC3 are 80%, 12% and 6% respectively. The establishment of three-dimensional model classification can clearly distinguish the two states of camellia oleifera leaves. At the same time, the PLS-DA model was also used in this paper, and the recognition rate of the model was up to over 90%, which could be used to better classify the two categories of camellia oleifera leaves. The above two stoichiometric methods can distinguish the health and disease of camellia oleifera leaves. The results showed that it was feasible to detect anthrax of camellia oleifera by LIBS. Quantitative detection of trace elements and nutrient elements in camellia oleifera leaves can be carried out by using LIBS technology, which provides a reference for quantitative detection. A new method for rapid detection of anthracnose of camellia oleifera.