Effects of low-level laser radiation of high power density at the Drimiopsis maculata, as an example

Abstract

In medicine, low-level laser irradiation (LLLT) in red and infrared spectral ranges is widely used for treating patients. Flexible quartz fibers with 500 μm and 400 μm diameters and with expected high density radiation power (HDRP) at the output were used for LLLT. However, mechanisms of HDRP stimulating effects at the organism of animals and plants are not clear yet. The aim of this work was to study effects of LLLT high power density at biological objects, for example, at Drimiopsis maculata, a plant with high photosensitivity. Materials and methods. The study was conducted in Laboratory of Laser Optics of the State Tyumen Oil and Gas University. Plants were divided into 5 groups the bulbs of which were exposed to LLLT with wavelength of 0.67 μm and 0.85 μm and exposure 3 and 6 minutes. One group of plants was taken as controls; they had no any irradiation. Laser light was emitted by two semiconductor lasers generating in wavelength 0.67 μm and 0.85 μm and having flexible quartz fibers with the diameter of optical part 400 μm and 500 μm, respectively. At lightguide outputs, HDRP for LLLT with wavelength 0.67 μm was 4,000 mW/sq cm, and for LLLT with wavelength 0.85 μm was 4,100 mW/sq cm, which was significantly higher than HDRP values used in clinical practice. Results. LLLT effects in all the experimental groups at the immediate observation period have shown more pronounced defoliation of plants, more active flowering phase and development of flowering shoots and inflorescences, as compared to the controls. In the later period (from 1 to 4 months) one could see an inhibited growth in most experimental groups.