الفهرس 
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Abstract
SUMMARY
The present work was conducted in the Horticultural Department, Texas
A&M University, Texas, USA through Channel System with Agricultural Botany
Department, Genetics Branch, Faculty of Agriculture, Zagazig University, Banha
Branch as an attempt to produce haploid onion plants (n) through anther and
ovary culture techniques. Effects of some factors and their combinations and
modifications were studied for haploid induction.
The two onion genotypes used in this study were TGY1015 and 1025 were
taken from Texas A&M University farm to find out their ability to produce haploid
plants through androgenic and parthenogenic techniques using two types of
media; MS medium (Murashige and Skoog, 1962) and B5 medium (Gamborg
et al., 1968). Before culturing anthers or ovaries, they were exposed to cold
temperature pretreatment at 4°C for different periods. Also, three sucrose
concentrations were applied at different ages of cultured anthers and ovaries.
a. Induction of Haploid Plants through Anther Culture in Onion (Allium cepa
L.)
The anthers of the two onion genotypes used in the present study did not
respond to any factor, factor combination or modification. Accordingly, no
haploid plantlets were obtained from onion anther culture technique.
b. Induction of Haploid Plants through Ovary Culture in Onion (Allium cepa
L.)
During the first 2 to 3 weeks, most of onion cultured ovaries swelled and
turned to dark brown, then died. Simultaneously, the rest of the onion cultured
ovaries swelled at the base and turned into white. Eight to ten weeks later, ovary
walls had split out and the plantlets started to emerge.
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Eight to ten more weeks later, the emerging plantlets grew on a shootsuitable
medium and increased in size, in spite of the remarkable low incidence
of regeneration (about 0.43% haploid out of the actual initial number of the
cultured onion ovaries).
After four to five more months, haploid plantlets were transferred to a
misttint over a sterile potting soil under the natural environmental conditions.
Those expressed regular development concurrent with clear differences
compared to the diploid ones (2n). Haploids were less in size and growth.
Factors affecting in vitro ovary culture
1. Genotype
The potential of the genotype 1025 was greater than that of 1015 in
producing haploid plantlets through ovary culture technique under all other
applied treatments.
2. Ovary age
The highest average number of regenerated plantlets was achieved
when onion ovaries were excised from flowers three to five days before
anthesis. The minimum average number of regenerated plantlets occurred
when the onion ovaries were excised six to ten days before anthesis. These
results were recorded for both onion genotypes used in this study.
3. Temperature pretreatment
The exposure of unpollinated onion ovaries to 4°C for four days as a
cold temperature pretreatment proved to be the most favorable in
production the highest number of regenerated plantlets, irrespeet of
genotype and suaose application.
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4. Media type
Murashige and Skoog basal medium (MS) was better than that of
Gamborg (B5) in increasing the response rate of the cultured onion ovaries
for development into haploid plantlets.
5. Sucrose concentration
Sucrose concentration of 10%, was significantly better than the 5% and
15% in increasing the average number of survivals of regenerated plantlets
from cultured onion ovaries.
6. Interaction between sucrose concentration and genotype
Irrespect of sucrose concentration, genotype 1025 produced
significantly more rehenerated plantlets than did 1015. At 5% or 15%
sucrose, no significant difference was recorded in the average number of
survival regenerated plantlets derived from the cultured onion ovaries of the
two genotypes used.
7. Interaction between sucrose concentration and ovary age
At the level 10% sucrose, the highest number of the regenerated
plantlets was obtained when the onion ovaries were excised three to five
days before anthesis from genotypes 1015 and 1025.
8. Interaction between sucrose concentration and temperature
pretreatment
A significant increase in the average number of onion cultured ovaries
which differentiated into plantlets occurred when the unfertilized ovaries
were exposed to 4°C for 4 days as a temperature pretreatment in the
presence of 10% suaose. Insignificant inaease in the response of the
onion cultured ovaries to be differentiated into haploid plantlets was
recorded because of the combination effect.
Findings of the present study show that maximum haploid production from
ovaries had been achieved with the genotype 1025, 10% sucrose, temperature
pretreatment at 4°C for a period of four days, MS medium and ovary age of
three to five days before anthesis.