Abstract: We studied the effect of tomato root tip cells radiated tomato dry seeds with ⁶⁰Co-r Ray, after they grew root in the water, observed chromosome bridge, chromosome fragments (including lagging chromosome), adhesion, micronucles ect abnormal chromosome type. The result show that the abnormal rate is lowest, when irradiation dose is in range 5-10 Krad; it is the highest and the types of abnormal chromosome is the most abundant, when the irradialion dose is in 10-20 Krad. In this range, quantity of the chromosome fragment is increasing, when the irradiation dose is enhanced, poly-bridge exist, besides single chromosome bridge. Chromosome are damaged seriously, when the irradiation dose is over 20 Krad. This dose is harmful to growth of tomato and the cells. By C. K. experiment and statistics. We can say, the irradiation dose controls the splits of root tip's cells.

Key words: Tomato, ⁶⁰Co-r ray, Abnormal chromosome, Adhesion, Chromosome fragment, Chromosome bridge, Micronucles