Studies on the Flowering and Fruiting of the Passion Fruit Tree (Passiflora edulis S_<IMS)

The passion fruit tree is one of the sub-tropical fruit trees and its fruit has recently become important as a source of fruit juice and as an additive flavour to various juice as well as fresh fruit. In Japan however the history of the cultiva-tion of the plant is quite new and naturally it presents various unknown factors in its cultivation and fruiting, The authors have conducted research on the causes of fruitless and preventive measures therefore and have obtained the fllowing results. 1. The plant blossoms and bears fruit continuously during the period from Feb-ruary to May and from about the fifth joint upwards counting from the base of new branches grown from each axil. 2. Time of flowering appeares to have some relation to its temperature and begins to flower simultaneously when the temperature reaches 16℃ to 17℃., and when the temperature had gotten higher, it flowers early in the mornig. The time required from the start to full bloom was about one hour and the period of flower-ing about 24 hours. 3. Fruiting was very poor in its natural state and its percentage was only 5.2％. By artificial pollination such as bud pollnation one day ahead of flowering, self-fertilization and cross-fertilization results as high 96％, were obtained. 4. The storage test of the pollen showed no practical trouble for fruiting within 2 days from the time of collection storage room temperature : min. 14.3℃, max. 25.4℃, opt. 20.5℃., but when the storage time exceeded 4 days the fertiliza-tion power greatly decresed. 5. The fertilizing ability of the pistil was about same from the bud one day ahead flowering to tbe day following bloom, but when 2 days had elapsed from the time of bloom, the fertilizing ability rapidly decreased. 6. The sdudies showed that the passion fruit tree could glow, flower and fruit even in a frosty district in winter, if it was protected in a glass-house or in a vinyl-house without any additional heating.