الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 132 |  |  |
| | | from | 132 | | |
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.