[en] Four month old seedlings of custard apple were transplanted in a sector of a Gamma Garden having a 600 Ci ⁶⁰Co γ-source in the center. The dose rates were 90-105, 195-240 and 480-640 mR/h. The cumulative doses averaged to 946, 2,064 and 5,300 R. Observations of tree height, trunk thickness and number of branches were performed at regular intervals. During the first fruiting season the number of fallen fruits and the number and weight of edible fruits were recorded. The trees in all 3 radiation zones grew taller than the controls for about 18 months. Radiation-induced greater thickness of the trunk was seen for 27 months, while an increase in the number of branches was observed throughout the experimental period (4 years). As to the fruiting pattern, inspite of the fewer fruits in the irradiated trees they gave higher fruit yield per tree. (MG)