Labor-saving studies in relation to berry thinning by promoting elongation of the cluster of seedless tetraploid grape cultivars derived from 'Kyoho' through the application of gibberellin
2011
Udo, Y. (Yamanashi Fruit Tree Experiment Station, Yamanashi-shi (Japan)) | Kobayashi, K. | Saito, N. | Mitsumori, M.
With the objective of promoting elongation of the cluster through the application of gibberellin, a labor-saving technique related to berry thinning was developed targeting tetraploid grape cultivars derived from 'Kyoho'. (1) First, the treatment condition was examined. The treatment timing was when the shoots bore 5 leaves. The treatment concentration was 5 ppm, and the method was hand-spraying. It was determined that the spray treatment to the cluster was suitable. (2) When the treatment was performed, the cluster at flower thinning became 1.2 to 1.5 times longer than without any treatment, and, at berry thinning time, both the number of berries per cluster and the cluster filling decreased. The fruit quality was almost identical to that of fruit that had been treated in the conventional method. (3) When treatment was performed, the number of working hours necessary for berry thinning was reduced by about 20 to 50%. In the labor-saving results, varietal and annual differences were recognized. (4) From the results above, by treating clusters with gibberellin at a concentration of 5 ppm when shoots bore 5 leaves, it became apparent that it was possible to both reduce the number of working hours necessary for berry thinning and produce fruit of sufficient quality.
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