Abstract:
The seeds of Nitraria tangutorum were exposed to different doses of gamma radiation from 60Co gamma rays based on
the two irradiation modes of without dose rate and with dose rate of 25Gy/hr. The effects of different irradiation modes and
irradiation dose on the seed germination rate, emerged seedling rate and phenotypic characters of seedling have been
studied. The semi-lethal dose and critical dose were determined for different irradiation mode. It has been found that there
were the differences of irradiation effects between the two irradiation modes. Promotion effect on the seed germination rate,
emerged seedling rate, seedling height and ground diameter in lower dose treatment were observed, while inhibition in
higher dose. As compared to control, the irradiation effects on the seed germination rate and seedling height and ground
diameter present the very remarkable differences at above 1500Gy dose without dose rate mode, while above 2400Gy with
dose rate mode. The negative relativity exists between the relative emerged seedling rate and irradiation dose, the emerged
seedling rate decreased with increasing dose. The semi-lethal dose based on the emerged seedling rate was 985Gy and
1363Gy for the irradiation without dose rate and with 25Gy/hr dose rate, respectively. The Appropriate 60Co gamma
irradiation dose for the Nitraria tangutorum seeds was ranging from 950 Gy to 1500Gy without dose rate irradiation mode,
while 1300Gy to 2400Gy with 25Gy/hr dose rate mode.
