Detection and Microscopy of Alnus glutinosa Pollen

Alnus glutinosa is important woody plant in Lithuanian forest ecosystems. Knowledge of 12 fluorescence properties of black alder pollen is necessary for scientific and practical purposes. By 13 the results of the study we aimed to evaluate possibilities of identifying Alnus glutinosa pollen 14 fluorescence properties by modeling ozone effect and applying two different fluorescence-based 15 devices. To implement experiments, black alder pollen was collected in a typical habitat during the 16 annual flowering period in 2018-2019. There were three groups of experimental variants, which 17 differed in the duration of exposure to ozone, conditions of pollen storage before the start of the 18 experiment, and the experiment start time. Data for pollen fluorescence analysis were collected 19 using two methods. The microscopy method was used in order to evaluate the possibility of 20 employing image analysis systems for investigation of pollen fluorescence. The second data 21 collection method is related to the automatic device identifying pollen in real time, which uses the 22 fluorescence method in the pollen recognition process. Data were assessed employing image 23 analysis and principal component analysis (PCA) methods. Digital images of ozone-exposed pollen 24 observed under the fluorescence microscope showed the change of the dominant green colour 25 towards the blue spectrum. Meanwhile, the automatic detector detects more pollen whose 26 fluorescence is at the blue light spectrum. It must be noted that assessing pollen fluorescence several 27 months after exposure to ozone, no effect of ozone on fluorescence remains. 28