Abstract –– This paper has as principal objective to

determine the value of some parameters of light that are determinants in the activation or inhibition of the growth stimulus of wheat seeds (Triticum aestivum L). In this case intensity and dose, as important parameters, were considered. GaAlAs laser with λ=850 nm was used to irradiate the biological system. The growth of main shoot was considered. All data were processed using statistical methods. Results obtained indicate that when the appropriate light parameters are used activation can occur.

Keywords –– Laser diode, high level laser radiation, photo-

bio-stimulation, biological system. Triticum aestivum L, wheat., IR (Infrared) radiation.

I. INTRODUCTION

There are a lot of researchers that have been studying the stimulation of different biological systems like Escherichia coli, DNA replication and division, neurons and lymphocytes, blood and spleen cells. In all the cases they determine optimal values for the parameters of light and analyze the responses at these values using statistical processes. It is important to stay that the variety of biological systems require different parameters of light to produce stimulation. In most of the cases He-Ne lasers with λ=632.8 nm are the grounds of these studies. In some cases they vary the wavelength to obtain a λ=650 nm or for using near infrared radiation [1-6].

In the laser photo-biostimulation there are three levels at

which various aspects of stimulation can be considered: molecular, cellular and organism levels. For these three levels exist light parameters that can activate or inhibit natural processes.

There are three factors that are determinant to obtain an

early photochemical and photobiological response in a biological system; these parameters are the light wavelength (nm), intensity (W/m2) and dose (J/m2). If appropriate light parameters are used, activation or inhibition in the grow stimulus will occur.

Laser sources are handy tools providing many advantages like efficient fiber optic delivery of light to irradiate interior body parts, high monochromaticity and easy wavelength tunability. With laser light different phenomena of live organisms in different wavelengths, at

which they are not exposed, can be investigated. Up today He-Ne lasers with λ=632.8 nm, semiconductors lasers, and LED´s in the range of l=600-1000 nm are used. It is important to stay that we only irradiate one time and the next reactions occur in the dark [5].

II. METHODOLOGY A semiconductor IR laser with λ=850nm was used to produce photo-biostimulation effects due some evidence shows that IR laser light penetrate deeper in tissues than red laser light. The optical powers obtained at the output were: 12.5, 25, 50 and 100 mW/cm2. The exposition times were 15, 30, 60 and 120 seconds. Once the exposition levels and times were defined, the radiation process was made. For each treatment control was used. The biological system was radiated once and after that seeds were put in germination for 7 days. The humidity and temperature conditions were controlled, 60% and 250 C respectively After 7 days the main shoot of the seeds was registered. Data were statistically processed afterwards.

III. RESULTS

A. Intensity of 12.5 mW/cm2.

Main shoot growth for an intensity of I = 12.5mW/cm2

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Fig. 1. Main shoot growth for an intensity of 12.5 mW/cm2 and irradiation

times of 15, 30, 60 and 120 s.

Photobiostimulation effects caused by a high power IR laser with λ=850nm in wheat (Triticum aestivum L)

Hernández M.1, Michtchenko A.2, Gallegos F. J.3

1,2,3Instituto Politécnico Nacional, ESIME-SEPI, Zacatento, C.P. 07738, México, D.F. Phone (55) 57296000 E-mail: mahhhevi@hotmail.com, amichtchenko@ipn.mx, fgallegosf@ipn.mx .

2008 5th International Conference on Electrical Engineering, Computing Science and Automatic Control (CCE 2008)

IEEE Catalog Number: CFP08827-CDR ISBN: 978-1-4244-2499-3 Library of Congress: 2008903800 978-1-4244-2499-3/08/$25.00 ©2008 IEEE

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Fig. 1. shows that for a time of 120 s and an irradiation intensity of 12.5 mW/cm2, the main shoot growth 20.9% more than the control level. B. Intensity of 25 mW/cm2.

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Fig. 2. Main shoot growth for an intensity of 25 mW/cm2 and irradiation times of 15, 30, 60 and 120 s.

Fig 2. shows an inhibition in the growth of the main shoot of 7.5% with respect to the control level when seeds were irradiated with an intensity of 25 mW/cm2 and an irradiation time of 30 s. In the same figure we can also observe a maximum growth of the main shoot when seeds were irradiated with an intensity of 25 mW/cm2 and an irradiation time of 120 s. In this case the growth of the main shoot was 12.9% with respect to the control level. C. Intensity of 50 mW/cm2.

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Fig. 3. Main shoot growth for an intensity of 50 mW/cm2 and irradiation

times of 15, 30, 60 and 120 s.

Fig. 3. shows a maximum stimulation when seeds were irradiated with an intensity of 50 mW/cm2 and an irradiation time of 15 s. In this case the growth of the main shoot was 12.3% with respect to the control level. D. Intensity of 100 mW/cm2.

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Fig. 4. Main shoot growth for an intensity of 100 mW/cm2 and irradiation

times of 15, 30, 60 and 120 s. Fig. 4. shows a maximum stimulation when seeds were irradiated with an intensity of 100 mW/cm2 and an irradiation time of 30 s. In this case the growth of the main shoot was 8.3% with respect to the control level.

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Fig. 5. Main shoot growth for all intensities and irradiation times..

2008 5th International Conference on Electrical Engineering, Computing Science and Automatic Control (CCE 2008)

IEEE Catalog Number: CFP08827-CDR ISBN: 978-1-4244-2499-3 Library of Congress: 2008903800 978-1-4244-2499-3/08/$25.00 ©2008 IEEE

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IV. DISCUSSION The statistical tool for agricultural science was needed to analyze all data obtained from experiments. Fig 1 shows the highest stimulation for all experiments, 20.9% with respect to the control level. The conditions to obtain this maximum stimulation were an intensity of 12.5 mW/cm2 and an irradiation time of 120 s. Fig 2. shows that the second maximum stimulation was obtained for an intensity of 25 mW/cm2 and an irradiation time of 120 s with a value of 12.9% with respect to the control level. Fig 2. also shows that an inhibition can occur when seeds were irradiated with an intensity of 25 mW/cm2 and an irradiation time of 30 s. Different studies show that suitable doses of He-Ne and CO2 lasers in continuous wave mode, have positive effects in accelerating plant growth and metabolism [12]. Qi explain that laser light improve the concentrations of proteins and enzymes in Insatis indigotica. [13] Xiang explains that the effects of laser irradiation on an organism level are chiefly due to a light effect, and electromagnetic effect, a temperature effect, and a pressure effect [14]. The low-power laser, especially the laser of a visible wavelength, emits little heat and has little pressure effect. Therefore, some researchers have suggested that the mechanism by laser irradiation produces its effects through its light and electromagnetic effects.

V. CONCLUSION It is important to stay that the mechanisms of light in biological systems and how light modify the molecular structures of these biological systems are unknown and are in study. The biostimulation effect exists for this biological system. The highest stimulation was obtained for an intensity of 12.5 mW/cm2 and an irradiation time of 120 s. For a different biological system parameters maybe be equal but there will be need to experiment with light parameters to optimizes these for a specific system.

REFERENCES

[1] Michtchenko A., “Efectos de fotobioestimulación provocados por la

radiación del láser de baja intensidad en la aceleración en crecimiento de semillas”, memorias del 4to. Congreso Internacional de Ingeniería Electromecánica y de Sistemas, 2005.

[2] Krötzsch E., Michtchenko A., Lomelí-Rivas A. , “Efectos de bioestimulación de radiación laser de baja potencia sobre la proliferación de fibroblastos humanos”, memorias del 3er Congreso

Internacional de Ingeniería Electromecánica y de Sistemas, ,pp 88,90, 2002.

[3] Shimizu-Sato S., Huq E., Tepperman J. M., “A light switchable gene promoter system”, Nature Biotechnology, Quail P. H., Vol 20, pp.1041-1044, 2002,October,

[4] Fankhauser C., “The Phytocromes a Family of red/far-red absorbing photoreceptors”, Journal of Biological Chemistry, Vol. 276, pp. 11453-11456, 2001.

[5] Tiphlova O.A., Karu T.I., “Stimulation of Escherichia Coli Division by Low–Intensity Monochromatic Light”, Photochem. Photobiol, V.48, pp. 467-471, 1988.

[6] Ouf S.A, Abdel-Handy N.F., “Influence of He-Ne Láser Irradiation of Soybean Seeds on Seed Mycoflora, Growth, Nodulation, and resistence to Fusarium solani”, Folia Microbiology, Vol. 44 , pp. 388-390, 1999.

[7] Vasilevski G., Bosev D., “Resuslts of the effect of the laser light on some vegetables”, Proc. First Balkan Symp, pp. 473-479, 1989.

[8] Sudha Rani G., Agrawal D. C., Rai K. P., Thakur S. N., “Physiological responses of Vigna radiate L. to nitrogen and argon laser irradiation”, Indian J. Plant Physiol, Vol. XXXIV, No. 1, pp. 72-76, 1991.

[9] Sudha Sudha Rani G., Agrawal D. C., Rai K. P., Thakur S. N., “Growth responses of Vigna radiate seeds to laser irradiation UV-A region”, Physiol. Plant., vol 63, pp. 133-134, Copenhagen, 1985.

[10] Pilet P. E. and Golaz F.,”Effect of white light on the growth of aseptically cultured maize roots”, Plant Science, Elsevier Scientific Publishers Ireland Ltd., Vol. 38, pp. 115-119, 1999.

[11] Plummer J.A., Bell D.T., “Germination in Photosensitive Seeds: Does Phytochrome Stimulate Metabolism”, Plant Physiol., Vol. 24, pp. 389–394, 1997.

[12] Voronkov LA, Tsepenyuk DY, “Influence of laser irradiation on cotton leaf apparatus”, Biol Nauk, 11.

[13] Qi Z, Casi SW, Wang XL, “The effect of He-Ne laser irradiation on soluble protein synthesis”, Chin J Northwest Univ 30, 45-48, 2000.

[14] Xiang Y, “Laser Biology”, Human Science and technology Press, Changsha.

2008 5th International Conference on Electrical Engineering, Computing Science and Automatic Control (CCE 2008)

IEEE Catalog Number: CFP08827-CDR ISBN: 978-1-4244-2499-3 Library of Congress: 2008903800 978-1-4244-2499-3/08/$25.00 ©2008 IEEE

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