In order to explore the effect of 60Co-γ ray radiation on Clerodendrum trichotomum, one-year-old Clerodendrum trichotomum rooting seedlings under different doses of 60Co-γ ray (0, 15, 25, 35, 45 Gy) were used to testify the impacts on growth and physiological indexes. The results showed that the increase of irradiation dose could aggravate the injury on shoots and leaves of Clerodendrum trichotomum root-turion seedlings, and the injury rate was positively correlated with radiation dose. Under low radiation dose, there was no significant difference in the net increment height and the new shoot diameter from the control group. With the increase of irradiation dose, the inhibitory effect gradually increased. The LD50 of the tiller root-turion seedlings was 41.07 Gy. The root activity generally increased with the increase of radiation dose. The content of chlorophyll a, chlorophyll b and total chlorophyll increased first and then decreased with the increase of irradiation dose. Along with the process of the growth, the promotion effect of low dose was declined. The chlorophyll fluorescence parameters Fv/Fm and Fv/Fo gradually decreased with the increase of irradiation dose, which was significantly lower than that of the control group at 45 Gy. With the increase of irradiation dose, the soluble sugar content increased first and then decreased, which was higher than that in the control group. Under 35 Gy, there were high damage rates and rich damage types with the inhibited growth inhibited, but the vitality could be maintained by increasing the soluble sugar content and the root activity, indicating that the 35 Gy was the suitable dose for radiation breeding in Clerodendrum trichotomum. The results provided a scientific basis for radiation breeding in Clerodendrum trichotomum.
In order to study the irradiation effects of 60Co-γ rays on different cotton varieties and screen drought-tolerant mutants. Three different cotton varieties (Lu Mian 532, K638 and K836) were irradiated by 250 Gy of 60Co-γ rays. Results showed that 60Co-γ rays irradiation significantly decreased the germination rate, germination potentiality and emergence rate of the three cotton varieties. Compared to non-irradiation the germination rate, germination potentiality and emergence rate of K836 were decreased by 38.9, 45.9 and 48.5%, respectively, and those decreased were greater than in Lu Mian 532 and K638. 60Co-γ rays irradiation significantly decreased the photosynthetic rate(Pn), transpiration rate (Tr) and chlorophyll content (Chl), cotton growth and seed cotton yield of K836, but 60Co-γ rays irradiation did not affect Lu Mian 532 and K638. Many plants with morphogenesis changes were found in the M1 generation population of K836, but few was found in the M1 generation populations of Lu Mian 532 and K638, suggested that 250 Gy of 60Co-γ rays was an appropriate dose for K836 to induce mutant, but the appropriate dose for Lu Mian 532 and K638 should be moderately raised. The M2 and M3 seeds of medium mature variety K836 were sowed in automated rain-shelter in Linqing and field in Dunhuang, respectively, for screening drought tolerant mutants. And screened 3 drought tolerant mutants, which established a theoretical foundation in breeding drought tolerant cotton varieties by 60Co-γ rays irradiation.