Effect of Gibberellins on the Shattering in Kyoho Grapes. E. TAKAHASHI, T. KIKITSU, M. NAKAMURA. and K. NAGASAWA, Faculty of Horticulture, Chiba University, Matsudo, Japan. Tech. Bull. Fac. Hort. Chiba Univ., No.21: 19-23. 1973. It is well known that the shattering phenomenon in Kyoho grapes may occur severely when they are grown in volcanic ash soil particularly in a year of heavy rain fall. In this study, the effect of gibberellins (GA), comparing with B-995, on the prevention of the shattering in Kyoho grapes was investigated. GA decreased the number of clusters which did not set berries and increased the number of berries per cluster. GA_<4+7> at 100ppm was most effective in increasing berry set. The percentage of berries per cluster observed on July 8 was increased 5 to 6-fold by GA treatment. GA increased the peduncle and pedicels weight and the peduncle diameter, especially more effective at 100ppm. By GA teratment, the peduncle and pedicels weight was increased 2.5 to 3-fold. GAinduced parthenocarpic berries and enlarged their size. The size of parthenocarpic berries induced by GA treatment, however, was smaller than that of seeded berries, and about 800f parthenocarpic berries was intermediate (5.5-6.4g) and small (<5.5g) berries as compared with large (>6.4g) berries. The growth pattern of GA-induced parthenocarpic berries showed a double sigmoid shaped curve. GA had not much effect on the total soluble solids and the total acidity. The pigment production contained in the parthenocarpic berries treated with GA_<4+7> at 100ppm was found to be highest compared to other GA treated berries.