Stern, R.A., MIGAL, Galilee Technology Center, P.O. Box 831, Kiryat Shmona 11016, Israel
Ben-Arie, R., Fruit Storage Research Laboratory, Kiryat Shmona 10200, Israel
Neria, O., Fruit Storage Research Laboratory, Kiryat Shmona 10200, Israel
Flaishman, M., Department of Fruit Trees, Institute of Horticulture, Volcani Center, P.O. Box 6, Bet Dagan 50250, Israel

The effects of the synthetic cytokinins BA and CPPU on fruit size of the small fruited 'Royal Gala' apple were examined during four consecutive years (1999-2002) in the warm climate of Israel. CPPU at a concentration of 10 ppm and BA at a concentration of 50 ppm caused an appreciable (>50%) and significant increase in fruit size when applied two weeks after full bloom. The large increase in fruit size occurred with (BA) or without (CPPU) some thinning. Therefore, the main effect was attributed to the direct stimulation of fruit cell division. Both cytokinins increased fruit size without affecting fruit shape and seed number, and with no reduction in the return bloom or yield of the following year. Our findings demonstrate that BA and CPPU have a significant potential to improve fruit size of 'Royal Gala' apple without any negative effects on fruit quality at harvest or in storage of 0°C. Preliminary results with 'Red Delicious' apple indicate that these cytokinins may be used for other cultivars as well.