Study On Irradiation Effect Of Seeds And Tissue Culture Of Chrysanthemum Cinerariifolium Trev.

This thesis studied on the biologic effect of (60)~C0-γirradiation through the observation and assay of the rate of germination, seedling formation and the growth of the young seedlings of the M1 generation which were germinated from the seeds irradiated with different dosages. 21 mutants of morphology were selected from the M1 generation, and the GC assay was conducted to analyze the content of pyrethrins. There were 2 mutants of increased pyrethrins content being found. The fast propagation and regeneration were primarily studied for the future research of the mutants in vitro. The results were concluded as following.1. The effect of the (60)~Co-γirradiation on the rate of germination and seedlingIt showed that the relatively low dosage of the irradiation could stimulate the germination to some extent while the high restrained it. Simultaneously, the speed of the germination was delayed with both the low and high dosage. The result of influence of irradiation on the seedling rate showed that 10Gy＞CK＞20Gy＞80Gy＞40Gy, while the survival rate of the seedling showed that CK＞40Gy＞10Gy＞20Gy＞80Gy.2. The effect of irradiation on the characteristics of the young seedlingIt showed that the low dosage as 10Gy could stimulate the growth of the true leaf while the high restrained it. The restraining effect was obvious on the plant height,. With the increasing of the dosage of the irradiation, the degree of restraining was enhanced.3. The field screening of the mutants of the irradiationThe morphologies of 225 seedlings of the M1 generation were analyzed and 21 mutant plants were selected. Only the lowest height of mutant was found for the plant height mutation. Both the forward and negative mutating directions were found of the length and morphological index of leaf while only the negative mutating was found of the leaf area. Neither mutating direction of the tiller number and true leaf was showed. The most negative mutation was found to be the average width of the plant, and the next is the height. There was only one plant showed forward mutation while all other mutants were negative. Most of the mutants were found with the 80Gy treatment.4. The determination of the pyrethrins contentThe result of TLC showed that the extract of leaves contained the pyrethrins.The contents of pyrethrins of the leaf extract were determined by gas chromatography using an internal standard analysis. Three components of pyrethrinsⅠcould be detected in most of the samples, and one of three components of pyrethrinsⅡknown as pyrethrinⅡcould not be detected. There were relatively more samples of the control and the 40Gy irradiation treatment being detected pyrethrinsⅡ. Concerning the total content of the pyrethrins, the reducing effect to some extent was showed.The contents of pyrethrins of mutants screened in field were determined by GC. The mutant No.2-53 was found to contain higher pyrethrinⅠ, CinerinⅡ, and JasmolinⅡcompared to the control. The component CinerinⅡlevel of the mutant No.1-67 was higher than the control.The level of component CinerinⅠextracted from the leaves of the two-year old seedling was found to be significantly higher than the one-year old.5. Tissue culture of the pyrethrumThe best medium for fast propagation in vitro is MS+BA 2.0mg/L + NAA 0.2-0.3 mg/L. The root could be preferably induced on medium MS+NAA0.3, while the medium MS+NAA0.1 was for the elongation of root.The callus induction rate of petiole was higher than the leaf. The best medium for callus induction of leaf was MS+KT 1.6 mg/L +2,4-D 2.0 mg/L. Both the effect of the different concentration of KT and 2,4-D was significant, and so was interaction of this two hormone.The result of direct induction of shoot from leaves was not ideal. Long period was needed to form the shoots and the rate was quite low. The browning was a serious problem of the inoculation in vitro.