Influence of He−Ne laser irradiation of soybean seeds on seed mycoflora, growth, nodulation, and resistance toFusarium solani

Abstract

Laser irradiation of soybean seeds for 3 min caused a clear reduction in the number of seed-borne fungi which became more pronounced as the irradiation time was extended. Pretreatment of the seeds with methylene blue, methyl red and carmine enhanced the effect of laser. Rhizoctonia solani, Alternaria tenuissima, Cercospora kikuchii and Colletotrichum truncatum were completely eliminated when the seeds were pretreated with a dye and irradiated for 10 min. Seed germination was stimulated on exposure of the seed to 1-min irradiation. At such dose, most of the dyes were accelerators while the higher doses were inhibitory to seed germination. Chlorophyll a, chlorophyll b and carotenoid content of developed plants differed, depending on the irradiation dose and dye treatment of the seeds. In seeds irradiated for 1 or 3 min, chlorophyll a formation was less affected than chlorophyll b formation. In seeds irradiated for 10 min, both the chlorophyll contents were decreased especially in the presence of some applied dyes. On the other hand, there was an increase in carotenoid content of soybean leaves when the laser dose increased. The number and dry mass of nodules were mostly greater (as compared to the corresponding control), when the seeds irradiated for 1 or 3 min were pretreated with methyl red, chlorophenol red, crystal violet and methylene blue. Irradiation of pre-sowing seeds greatly protected soybean stands against F. solani. The disease incidence differed somewhat when the irradiated seeds were pretreated with dyes. The reduction in disease incidence was accompanied by accumulation of high proline and phenol levels in the infected root tissues of soybean, suggesting that these compounds have a certain role in the prevention of disease development.

Changes in the germination process and growth of pea in effect of laser seed irradiation

“…In some researches opinion, presowing physical treatments of seeds are environmentally safe because they only modify biochemical and physiological processes in seeds, which, in consequence, accelerate seedling emergence and improve plant development (Chen et al, 2005a;Podleśny et al, 2012;Rubinov, 2003). Physical treatments, such as laser irradiation, do not replace chemical methods, but they can supplement them (Ouf and Abdel-Hardy, 1999;Vasilevski, 2003). Laser beams are monochromatic, coherent, and parallel; hence, they seem to be particularly suited for stimulating seeds (Ćwintal et al, 2010;Hernandez et al, 2006;Muszyński and Gładyszewska, 2008;Makarska et al, 2004).…”

Thermal Effects of Laser Irradiation on Maize Seeds

“…It was interesting to study the role of laser irradiation in the temperature changes of maize seeds in two conditions, natural and pretreated with a black dye, and to find that seed coloration modified the temperature changes in seeds exposed to the LILI. Ouf and Abdel-Hady (1999) found that the effect of pretreating the soybean seeds with different dyes (methyl red, crystal violet, and methylene blue) caused a more pronounced effect of laser light on germination when compared with non-irradiated seeds. Also, when the laser was used to reduce the fungal contamination of the soybean seeds, particularly when the seeds were pretreated with dyes, the methylene blue was the most effective dye in enhancing the fungicidal effect of laser irradiation.…”

“…Some authors have found that it is possible to increase the effect of laser irradiation by the use of photosensitizers as artificial dyes (Ouf and Abdel-Hady, 1999); in this sense, the present study is focused on identifying thermal changes that occur in the untreated and dyed seeds when they are irradiated with laser light. The seed industry uses agrochemicals, such as: artificial dyes, fungicides, fertilizers, etc.…”

Laser treatment may enhance growth and resistance to fungal infection of hard wheat seeds

“…Other authors have reported the effects of laser irradiation on growth and development of bacteria as Escherichia coli, Irradiation of the bacteria E. coli with a He-Ne laser (632.8 nm) within a range of values produced two maximum values in the growth stimulation before reaching a minimum value, after which the growth was observed [35]. On the other hand, in fungi [22] reported that laser irradiation of soybean seeds for 3 min caused a clear reduction in the number of seed-borne fungi which became more pronounced when the irradiation time was extended using a laser of He-Ne with = 632.8 nm and power of 7.3 mW. The production of alkaline protease, blood heamolysis, pyocyanine and MICs values of (amikacin and piperacillin) were reduced significantly by irradiation with red light from 2W diode laser with 805nm wavelength and power density 7.07 W/cm 2 with respect to both light energy dose and exposure times in Pseudomonas aeruginosa [36].…”