A study has been conducted on the rootstock cross area, trunk cross area and total growth with 195 selected plants, a primary effect product from Bigareau Burlat, Pobeda Krimska and Kozerska cherry varieties, during the first MV1 generation after the gamma radiation with Cz¹³⁷. Graft branches were exposed to dosages of 25Gy, 35Gy and 45Gy at the Institute of Radiobiology and Radiopreservation in Sofia. The graft was taken during dormant buds onto a Prunus mahaleb rootstock. The average values of all study parameters with the selected plants are 10 to 50% smaller in comparison with the controls (plants not treated with radiation). The highest reduction of total plant growth is noticed at Kozerska variety. The average value is 40% smaller in contrast to the control. The average values for this characteristic provide statistical significant differences for all radiation dosages with the selected plants in contrast to the control.  The highest difference was noticed with the dosage of 25 Gy, where the total growth is 50% smaller than the control. A very high positive correlation is determent between the rootstock and trunk cross area, as well as between the rootstock and trunk cross area and with the total growth in all of the tested varieties. Negative correlation between the radiation dosage and the total growth is detected for Pobeda Krimska and Kozerska. This kind of correlation is not present in Bigareau Burlat. 

Key words: Prunus avium L., gamma radiation, dosage, rootstock and trunk cross area, total growth.