Effects of the foliar application of SADH（succinic acid-2, 2-dimethylhydrazide）at the concentration of 5,000 ppm 22 days or 13 days before full bloom(called hereafter early application and late application, respectively) on the growth of shoots, the occurrence of bud necrosis and the set of seeded and seedless berries were studied in a 'Kyoho' vine grown in the orchard of Shimane University.
Although both SADH treatments depressed the shoot elongation, the early application was more depressive for it until full bloom and the late one was so after full bloom. In addition, the late application had more depressive effects than the early one for the growth in internode until the 20th node and also in shoot thickness at the 6th and 11th internodes.
Each lateral bud on a shoot consisted of a central bud and usually two additional axillary buds in the cultivar, and both the SADH treatments remarkably inhibited the occurrence of necrosis in the central buds until the 25th node. However, the early application tended to be more effective for the buds located under the 8th noae and the late one for those above the 13th node. As for the occurrence of necrosis in the axillary buds, the early application was more inhibitive than the late one.
Due to the early applicatlon, the number of seeded berries per cluster increased to more than 3 times and the number of seedlees berries reduced to about 2/3 as compared to those of the untreated control. The late application was less effective than the early one for the set of either seeded or seedless berries.