Effect of Stress Caused by Electromagnetic Stimulation on the Fluorescence Lifetime of Chlorophylls in Alfalfa Leaves
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Department of Biophysics, University of Life Sciences, Lublin, Poland
Department of Plant Production Technology and Commodity Science, University of Life Sciences, Lublin, Poland
Department of Analysis and Differential Equations, Faculty of Mathematics and Computer Science, University of Warmia and Mazury, Olsztyn, Poland
Chełkowski Institute of Physics, University of Silesia, Katowice, Poland
Agata Dziwulska-Hunek   

Department of Physics, University of Life Sciences, Akademicka 13, 20-950 Lublin, Poland, Akademicka 13, 20-950 Lublin, Poland
Online publish date: 2019-04-29
Publish date: 2019-05-28
Submission date: 2018-04-23
Final revision date: 2018-07-02
Acceptance date: 2018-07-12
Pol. J. Environ. Stud. 2019;28(5):3133–3143
The experimental material consisted of leaves obtained from 6- and 2-year-old alfalfa plants. Samples were obtained from a field experiment. One day prior to sowing, seeds were stimulated using He-Ne laser light with a surface power density of 6 mW∙cm-2 – free-fall exposure (L) repeated three times; alternating magnetic field with 30 mT induction and 30 s (P) exposure time; and a combination of laser light and magnetic field (L+P). The results of the stimulation treatments were referenced to non-stimulated samples (control – K). The obtained values of fluorescence lifetime varied from 8.98 to 12.90 ns (t1) and from 3.84 to 5.14 ns (t2). The physical factors applied caused an extension of the lifetimes (t1 and t2), as well as an increase in the chlorophyll a and carotenoid content in 6-year-old cv. Radius leaves, as compared to the control. Contrary observations (i.e., a decrease in the aforementioned indicators) were made for cv. Ulstar (old). In the case of magnetic field stimulation, the longest fluorescence lifetimes, the highest concentrations of chlorophyll a and carotenoids were noted for cv. Radius (old). The content of chlorophyll a was significantly higher in young Lucerne than in older plants.