Vibrating Characteristics of Berry of Grapes 'Pione' through Transporting Simulation and Prevention of Berry-Drop Caused Mechanically by Shaking

Abstract

We examined the vibrating characteristics of bunches and berries of grape 'Pione' (Vitis vinifera x V. labrusca) by giving horizontal and vertical shakings with some different frequencies (Hz) and G values, and studied the effects of the treatment of KT-30 (synthetic cytokinin) and uses of a styrofoam net on the reduction of berry-drop. It was confirmed that bunches and berries of the grapes vibrated violently under the condition based on Japanese Industrial Standards, and they vibrated more intensively by horizontal shaking than by vertical shaking. At the fine of the vertical shaking fixed at 1.0G, berries vibrated slightly at 5 Hz, but bunches vibrated violently at 9-11Hz. In the case of the shaking at fixed 10Hz, berries vibrated slightly at 0.2G, bunches vibrated violently at 0.6G, and whole bunches vibrated more violently and vertically at 1.0G. Berry-drop occurred at 1.4G, and bunches sprang up at 1.6G. At the fine of horizontal shaking, berries vibrated more violently at a low frequency than by the vertical shaking. Treatment with KT-30 considerably prevented immediate berry-drop after the shaking. Berry-drop of treated grapes occurred several at the fine over 2 days after the shaking, but the number of berry-drops was below 50% of that in the grapes not treated with KT-30. The number of berry-drops of grapes treated with 20 ppm of KT-30 was less than that of grapes treated with 5 ppm of KT-30. It is postulated that the cause of the decrease of berry-drop may be the increase of strength against pulling off berry from the peduncle. As the treatment with high concentration of KT-30 brought about a delay of berry-coloring and the decreases in Brix and sugar-acid ratio, it was considered that the treatment with 5 ppm of KT-30 was preferred as the practical concentration. By using a Styrofoam net as a shock absorber, the number of berry-drops decreased to below 50% over a 2 day period after the shaking. The above results indicate that the number of berry-drops is reduced with treatment of KT-30 or a Styrofoam net. By combining these treatments, berry-drop seems to be reduced even more. As the treatment with KT-30 is favorable to decrease berry-drop, that is appropriate for elongation of the harvest period.