Effect of60 Co- γirradiation on the germination of tomato seeds and early seedling growth.

Two different germination status of tomato cultivar 1479 and yellow pot-cultivate were irradiated by 60 Co-γ rays from 0 Gy to 800 Gy.The effects of the radiation on seed germination and early seedling growth characters were investigated by the method of germination box testing.Different varieties showed significant differences to sensitivity of 60Co-γ rays.The results indicated that the inhibitory effect of 60Co-γ rays on germi-nation of 1479 was much larger than that of yellow pot-cultivate,which mainly manifested in the germination rate and germination velocity.Different germination status of seeds showed different sensitivity to irradiation.30% PEG priming seeds had a stronger sensitivity compared with dry seeds.Although high-dose radiation could not inhibit seeds germination completely,inhibited the growth of the seedlings significantly,mainly demonstrated by the differentiation and growth of radicle.Semi-lethal dose(LD50) could be used to determine the appropriate dose of 60Co-γ irradiation,and yellow pot was 500 Gy to 600 Gy,1479 was 400 Gy to 500 Gy.