Flower bud differentiation and development of grapes

Abstract

(1) Studies of flower bud differentiation and development of Koshu and Delaware grape varieties had been conducted at Osaka and Gitu 1927 to 1931.
(2) The growing points of both varieties were recognized in the shape of crotch or Sympodium in mid-June. The symptom in this stage is like that of egg plants and tomatoes.
(3) Time of flower clusters differentiation of these varieties was mid-June in the buds of the young shoots and formation of secondary clusters in the differentiated clusters was late June.
(4) Second dusters formation of Delaware in the buds was observed in June 20 to July 10, third clusters July 8 to August 7, the forth August 29 to September 19 and their subdivision of the differentiated clusters, that is development of secondary, tertiary and quaternary clusters, observed from November 16 to December 28.
(5) Second flower clusters in the buds of Koshu began to differentiate on July 10, and the differentiation of third flower cluster was rare. Time of the third flower cluster differentiation was from July 30 to October 19.
(6) Calyx formation of Delaware was observed at first April 11 in the next year when individual flower bud was to differentiate. Flower buds were observed with the unaided eye on May 9 and pollen grains and ovules appeared on May 16.
(7) Flower buds of grape vines are much like to those of persimmons and chestnuts, showing delayed development of flower organs during winter. Calyx or petals are formed from March to April and make rapid development until flowering and fruiting.