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Abstract The mam objectives of this study are to increase of genetic variabilities either using of gamma radiation with different doses on different cultivars or by utilizing somaclonal variation occured during indirect regeneration (tissue culture techniques). Meanwhile, comparison between behaviour of mutated plants in vivo and in vitro. The plants resulted either from the field or from tissue culture which showed variation or mutation were subjected to cytogenetic screening during both MI and M2 generations to identify different types of mutations. This experiment was carried out at the Researchal Lab. of Cytology and Tissue Culture in the Faculty of Agriculture at Moshtohor deplartment of Agric. Botany, Genetics Branch, during the period from 199Jlto 1996. The experiment included five varieties, i.e. Giza 3, Giza 461, Giza 429, Giza 716 and Giza Blanka ofFaba bean (Vicia faba). The moistened seeds were irradiated by gamma rays with different doses, i.e. 5, 10,20 and 30 Krad. Some important vegetative characters were studied. Also, cytological studies included mitotic, meiotic and calli cells to detect the chromosomal aberrations and polypoidy were conducted. Somaclonal variations were detected during the tissue culture studies. I. Some Vegetative and Yield dlaracten : 1. The germination percentage was highly affected by increasing the irradiation dose. It was decreased with increasing the irradiation dose. The most lethal dose was 30 Krad. Giza 3 was the most sensitive variety to the gamma :raysirradiation. 2. The shoot length was significantly increased in Ml plants especially, with lower doses in Giza 3, Giza 461, Giza 429, Giza 716 and Giza Blanka. Also, it was found that the shoot length slight decreased in case ofM2 plants in most the treated varieties. 3. The number of branches was increased at the lower doses in the most varieties and decreased at the higher doses in Ml and M2 plants. 4. Concerning number of flowers per plant, it was detected that, with a few exceptions particularly at the lower doses, the number of flowers was decreased as compared to the control in plants ofMl and M2. 5. For number of pods per plant, it was revealed that highly reduction in number of pods per branch in all the treated varieties in M2 plants with gamma rays which negatively affected the yield per plant, while it increased over than the control at the most doses in MI plants. 6. Concerning the fruit setting percentage, most of used doses affected positively on friut setting in MI plants. In the other hand, it revealed highly decrease in fruit setting in Giza 3, Giza716 and Giza Blanka in M2 plants at all doses than the control. 7. The pod length was slight decreased or increased than the control at used doses in MI and M2 plants. 8. For number of seeds per pod, the treated varieties with all the inadiated doses revealed a reduction in seed nmnber per pod in the most varieties. 9. A significant reduction in yield, with exception at 5 Kant in MI plants, was detected in all the studied varieties with the used doses comparing to control. An inaase in yield was found at dose 5 Kant in Giza 429, Giza 716 and Giza BIanka. II. Cytological Studies on Mitotic, Meiotic and Callus Cells : Results showed that the gamma irradiation has an inhibitor effect on the rate of mitotic division, which increased by increasing the dosage of irradiation. This effect was obvious in Giza 461, Giza 429 and Giza 3 more than Giza 716 and Giza Blanka. All the used irradiation doses decreased the percentage of normal cells in prophase which decreased with the increasing doses. While the precentage of normal cells increased in metaphase and the effect of gamma irradiation doses was little on anaphase and telophase stages. The effect of gamma irradiation on root tips of these plants lead to induction of many types of chromosomal aberrations like micronuclei, chromatid bridges, lagging, chromosomal fragmentation, star,C-metaphase and spindle detrioration. In spite of that the percentage of occuring the chromosomal aberrations was differed in the different treatments, it was clear that this percentage increased wifh the increasing dosage. Also” a high percentage of cbromosomal abenations was found in meiotic division which increased with increased dosage. The most important chromosomal aberrations were micronuclei chromatid bridges, lagging, chromosomal fragmentation and more specifically Jagging and fragmentations. The cytological studies in caIIii revealed that polyploidy, haploidy and cbromosomal breakage were the most importaDt abnonnaIities. -Tissue culture studies : 1.Ganborg medium induced the lowest nicroses and increased growth, proliferation and chlorophyll with high extent. 2. Shoot tip and one node cutting explants had some what similar effect on all parameters studied except the number of plants resulted from one node cuttings which surpossed those resulted from shoot tips. 3. Generations number had no effect on any of studied explant development or growth parameters. 4. Mature embryo and the second stage embryo produced the best development either in plantlets regeneration and chlorophyll in case of mature embryo (third stage) or only increased in callus production in case of using the second stage of enbryo as explant. However, the first stage embryo failed completely to induce any sign of success. 5. Somaclonal variations oecured greatly when leaf discs followed with intrnode segments were used as explants and this may be due to the callus type resulted from those 2 explants. In most cases leaf discs and internode segments produced friable callus while shoot tip segments produced compacted callus. Genetic variations which led to somaclonal variations were occured regularly in friable callus than compacted ones that developed into somattic embryos. |