Laser On Soybean Uv-b Radiation Damage The Protective Effect And Optical Effect

The laser has been widely used in the field of biology with the development of laser technology, but the mechanism of the bio-effect of laser was not clear because of the complexity of biology. In this paper, (1) The germinating soybean was irradiated by a semiconductor laser (650nm, 3.97mW.mm^-2) and incoherent red light which was transformed from low-dose semiconductor laser (3.97mW.mm^-2) by a converter for 3 min respectively, and the optical effect of laser protection soybean damaged by UV-B irradiation was studied. (2) The germinated soybean was pre-irradiated for 1min, 3min, 5min and 7min by low-dose He-Ne laser, and then irradiated by enhanced UV-B irradiation when the sixth leafage was unwrapped, the morphology and biomass were studied when matured. We found that:(1)The pre-irradiation of semiconductor laser could keep the concentration of chlorophyll and carotenoids in the same level with that of the control, while the incoherent red light could not. The changes of the concentration of soluble protein also showed that the light effect doesn't work in this process. The incoherent red light did not reduce the MDA concentration, but it increased the activity of SOD.(2) The concentration of CPDs was detected by means of ELISA. The laser pretreatment (3.97mW.mm^-2) could reduce the concentration of CPDs which was produced by UV-B irradiation (10.08kJ.m^-2), while the incoherent red light could not. The hyperchromic effect of DNA was the same with the CPDs. This suggested that the laser can protect the DNA from damage by UV-B, but it appears that the optical effect does not involve in this process.(3) There is no significant difference in plant height, the area of the first pair of leaves, fresh weight and dry weight of leaf, stem and root of the soybean seedling among each treatment of this experiment. It needs further research whether the difference had not exhibit in infancy or the treatments could not induce difference.(4) The concentration of chlorophyll was reduced when the soybean was irradiated by UV-B only, but it was increased when pre-irradiated by He-Ne laser. The concentration of carotenoids has no difference in all treatments. The concentration of nucleic acid in the soybean irradiated by laser was higher than that irradiated by UV-B.(5) UV-B irradiation had not influence on the morphology and biomass, and this was no relation with whether the soybean was pre-irradiated by laser or not. When treated with He-Ne laser, the 3min-treatment increased the plant height and the percentage of fruit, while the 5min-treatment reduced the number of pods. This result showed the irradiation of laser took effect till the soybean later growth period.The temperature just increased 0.1 °C when the soybean seeding was irradiated 3min by semiconductor laser, and we can eliminate the heat effect in this experiment, meanwhile the pressure effect and electromagnetic effect was very weak, so we can infer that the effect of low-dose laser on plant should be synergetic effect, and that the laser has long-term effect on plants.