192 FUNDAMENTALS OF FRUIT PRODUCTION 



entiation undoubtedly occurred in the spring. Hand pollination in some 

 cases resulted in the formation of fruits with seeds of normal appearance 

 and in Oldenburg without such assistance a considerable proportion 

 of the crop actually harvested developed from secondary bloom. 



Apple trees in tropical climates, though they blossom little, seem not 

 to be restricted in the time of fruit-bud formation. 



The conclusion seems warranted that a fruit bud may be formed 

 at any time, though ordinarily the period is rather restricted. The 

 period evidently can be varied somewhat by cultural treatments, includ- 

 ing perhaps any practice that modifies the rate of growth. In general 

 the earlier the period of differentiation, the greater the number of fruit 

 buds finally formed, but as shown elsewhere, with some qualifications, 

 the less hardy those buds are. 



Winter Stages. — Kraus^^* has described in detail the development of 

 the individual flower within the bud. The sepals are differentiated first, 

 followed closely by the primordia of the petals. Either simultaneously 

 with, or directly after, their appearance those of the stamens are laid 

 down; after these come the primordia of the carpels. The ovules do not 

 appear until the resumption of growth in the spring. 



During November and December in Virginia, Drinkard^^ found 

 little development of the gross parts of the apple flower but noted some 

 cytological changes. "During December," he states, "the pollen 

 mother cells developed large, prominent nuclei. . . . Nearly all changes 

 which occurred during the month of January took place in the stamens. 

 ... On February 19, there was some indication of renewed develop- 

 ment in the anthers; these had enlarged appreciably on February 24. 

 . . . Early in March there was a beginning of development of ovules 

 in the cells of the ovary. These became very distinct by March 22. At 

 the same time tetrad formation was going on in the pollen mother cells." 



Drinkard found some development during the winter in buds of pear 

 also. In the peach, growth during winter seemed more active. The ovule 

 appeared late in December and tetrad formation in the pollen mother cells 

 late in January, in both instances considerably in advance of the apple. 

 Similarly the plum was found to show more or less development, practi- 

 cally throughout the winter. These observations are of interest in con- 

 nection with the differences in hardiness of fruit buds discussed elsewhere. 



However, it has been reported that in New York fruit buds do not 

 develop from the middle of November until about the first of March^o^ 

 ■ and in Wisconsin no evidences of activity were found from the beginning 

 of freezing weather until after the middle of March. ^^ In fact it was 

 stated that there was no change in pear flowers from Dec. 1 to Mar. 30.^^ 

 Albert reports pear blossoms to be unchanged until March, though he 

 records development in the pistils of the filbert during November and 

 December. In Japanese quince he found that development is arrested 



