A STUDY OF THE FORMATION AND DEVELOPMENT OF 



THE FLOWER BUDS OF JONATHAN AND GRIMES 



GOLDEN IN RELATION TO DIFFERENT TYPES 



(CLOVER SOD, BLUE GRASS SOD, COVER 



CROP, AND CLEAN TILLAGE) OF SOIL 



MANAGEMENT. 



R. S. KIRBY UNDER THE DIRECTION OF J. N. MARTIN. 



SUMMARY. 



The data so far obtained are insufficient to warrant conclu- 

 sions as to what is true as a rule. This summary simply states 

 briefly what was found during 1916 and 1917 eoncerning the 

 formation and development of flower Imds in these two varieties 

 of apples, growing on plots representing four types of soil man- 

 agement in the Council Bluff's orchard humus Experiments of 

 the Sections of Pomology and Soils of the Iowa Experiment 

 Station. 



1. Flower ])uds were formed, that- is, differentiated from 

 leaf buds, earlier on sod plots than on plots receiving some cul- 

 tivation each year. 



2. The earliest time at wliich flower l>uds were formed oc- 

 curred on clover sod, with a low percentage of soil moisture. 

 Flower buds formed earlier on a clover sod than on a blue grass 

 sod having slightly less soil moisture. On the other hand, flower 

 buds formed earlier on a blue grass sod than on a clover sod hav- 

 ing about 21/2 per cent more soil moisture. These facts indicate 

 two things: first, that the addition of nitrates in the clover sod 

 causes the flower l)uds to form earlier ; and second, that the 

 amount of soil moisture is a very important ■J not the chief ex- 

 ternal factor in determining the time at which flower buds form. 



3. The fonnation of flower buds began about the first of 

 July on the plots where it occurred earliest and extended until 

 the middle of September on the plots where it oecurred latest, 

 thus occupying a period of about two and one-half months. The 

 time occupied by each tree in fonning flower buds was about 

 four weeks. 



4. Trees in sod produced the largest proportion of flower 

 buds and those in clover sod, which supposedly contained the 

 most nitrates, produced a much larger proportion of flower buds 

 than those in blue grass sod. 



