| The Isatis indigotica seeds and the seedlings damaged by enhanced UV-B irradiation (10.08 kJ.m-2.d-1) were exposed to He-Ne laser (5.23 m W mm-2, radiated for 5 min) radiation In order to determine whether or not He-Ne laser caused the changes of thermodynamic parameters of seeds and had a long-term physiochemical effects and whether or not He-Ne laser has the protects and repairs capacity of the seedlings from enhanced UV-B damage. The results from the experiments indicated chiefly that:1. The seeds embryos of Isatis Indogotica were exposed to He-Ne laser irradiation. Subsequently, the thermodynamic parameters were calculated according to thermograms of seeds germination tested with calorimeter at 25C, And the changes in physiological characters ( net photosynthetic rate, stomatal conductance, water utilization efficiency and concentration of chlorophyll) , biochemical characters (soluble sacchrides, soluble protein, pyruvic acid, and the activities of three kinds of enzymes) and the growth (biomass and leaves area) were measured when the seedlings of He-Ne laser pretreated seeds developed at stage of 24-25 days in comparison with those of untreated seeds. We found that the thermodynamic parameters in H,( S)e,( S)c, and during germination at 250C changed significantly with He-Ne laser pretreatment seeds , and that the physiological characters, e.g. stomatalconductance, water utilization efficiency, net photosynthetic rate and chlorophyll concentration, the biochemical characters, e.g. the concentration of soluble sacchrides, soluble protein and the activities of a-amylase, GPT and GOT, and the biomass and leaf areas were statistically significant improved. These changes suggested that the pretreatment with He-Ne laser not only had a short-term biology effect (which enhanced inner energy of seeds) but also a long-term biology effect (which contributed to the acceleration of the growth and development of seedlings).2. The seeds pretreated with He-Ne laser was cultivated in petri dishes in a growth chamber with humidity (Model: 515HD.USA) until the seedlings were 2d old, and then were subjected to UV-B radiation for 6d under photosynthetically active radiation (220 umol m-2 s-1). Afterwards, great changes of UV-B injured seedlings, respectively, in the activities of enzymes (SOD, CAT and POD) and the concentration of malonndiadlehyde (MDA), proline and UV absorbing compounds were measured to test the protect capacity of He-Ne laser pretreatment. Results from this experiment indicated that: MDA concentration of the seedlings was decreased, the activities (SOD, CAT and POD), the concentration of proline and UV absorbing compounds were enhanced with laser pretreatment; and finally UV-B stress resistance were enhanced significantly with He-Ne laser pretreatment.3 The seedlings damaged by enhanced UV-B irradiation were exposed to He-Ne laser radiation under photosynthetically active radiation, the great changes were observed from followed results:3.1 Great changes of UV-B injured seedlings not only' in the activities of enzymes (SOD, CAT and POD) but also in the concentration of malonndiadlehyde (MDA), proline and UV absorbing compounds were measured to test the repair capacity of He-Ne laser on cleaning the free radical induced by UV-B radiaon. Results from this experiment indicated that MDA concentration of the seedlings was decreased, the activities (SOD, CAT and POD), the concentration of proline and UV absorbing compounds wereenhanced with laser treatment; and finally UV-B stress resistance were enhanced significantly with He-Ne laser.3.2 Great changes in physiological characters (net photosynthetic rate, stomatal conductance, water utilization efficiency and concentration of chlorophyll); biochemical characters (soluble protein, the activities of proteiase, GOT, GPT and free amino acid) were measured to test the repair capacity of He-Ne laser. We found that the physiological characters, e.g. stomatal conductance, water utilization efficiency, net photo...
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