Seed germination and seedling growth of different varieties of Linum usitatissimum under ⁶⁰Co-γ irradiation

To investigate the effects of irradiation on Linum usitatissimum seeds, nine varieties of L. usitatissimum were irradiated with different doses of ⁶⁰Co-γ radiation, and the effects of radiation on seed germination and seedling growth were examined. The results indicated that the effects of radiation on seed germination varied among the different varieties. With the exception of Longya 9 and Longya 10, the seed germination rate of the other seven varieties was negatively correlated with radiation dose, and the germination rate and relative emergence rate decreased with increasing dose. Semi-lethal doses for the L. usitatissimum varieties Longya 14, Longya 13, Dingya 17, Tianya 10, Longya 9, Zhangya 3, Longya 11, Longya 10, and Longya 12 were 6 668, 6 521, 6 462, 6 417, 6 399, 5 869, 5 786, 5 716, and 5 681 Gy, respectively. Lower doses (lower than 1 000 Gy) of radiation increased the germination rate of Longya 9 and Longya 14. At high doses (higher than 12 000 Gy), the rate of germination and seedling growth were markedly inhibited. Although seeds were able to germinate, seedling growth rate was significantly inhibited and the rate was 0. With the exception of Zhangya 3 and Longya 13, the plant height and root length of the other seven varieties increased under low-dose irradiation, and decreased at high dose. The results of this study will provide a theoretical basis for mutation breeding and acceleration of the breeding process of L. usitatissimum.