This experiment was carried out to study the effectiveness of chemical
mutagen sodium azide, SA at different concentrations 0,0.5,0.75 and 1 mM. Gamma
irradiation at doses of 0, 10, 20, 30 and 40 Gy was also used to test its effect on
improving salinity tolerance of the Spunta potato cultivar by shoot tips culture, as well
as to produce plants grown under different levels of sea salt 0, 1000,2000,4000 and
8000 ppm, aiming to induce and select in vitro salt tolerant plant lines. Subcultures
were done to the plantlets four times under sea salt concentrations , the obtained
results indicated that gradual increase of sea salt levels was negatively correlated
with all growth parameters (sur/ivai percentage, plant length and number of leaves),
survival percentage was 99.72% at the 4th subculture. Exposure to gamma irradiation
at low doses (10 and 20 Gy) either alone or combined with sea salt application had
stimulative effects on growth parameters, meanwhile higher doses (30 and 40 Gy)
adversely affected all the tested parameters. The concentration of 0.75 mM SA
improved survival percentage while SA had negative effect on other growth
parameters. Concerning RAPD (Random Amplification of Polymorphic DNA) genetic
difference between treatments and the control plants were detected. However, the
presence of polymorphic bands with three 10-mer primers, enables possible early
detection of mutation in vitro.