Self Sterility and Cross Sterility in the Apple. 



65 



own pollen is slight even with those varieties which will self 

 fertilize. This is especially true when it is realized that each 

 of the selfings within table I represent the flower cluster and 

 not individual flowers. 



The results from the different methods of pollination are 

 chiefly negative in character. The three different groups show 

 no material difference in the set of the fruit for the three meth- 

 ods. This is of interest in connection with the results of polli- 

 nation with pollen of the same tree and the results of pollina- 

 tion with pollen of a different tree but of the same variety. The 

 results are in each case approximately the same. This would 

 be expected in view of the probable fact that the trees of a given 

 variety are ultimately of the same origin, coming as they do 

 from the same original seedling. Such results indicate the rela- 

 tive stability of the buds and the trees which grow from them 

 in their presumably hereditary behavior to crossing with dif- 

 ferent kinds of pollen. 



It shows further the probability that the planting of a large 

 block of trees of the same variety, if it is self sterile, will not 

 tend to a larger crop of fruit because for these self sterile varie- 

 ties the pollen of other trees of the same variety is no more 

 compatible than the pollen of the tree itself when applied to 

 the stigmas. 



It is of considerable interest to gather together the results 

 on the self sterility of the apples varieties as it has been deter- 

 mined by the different states, both to determine on as large 

 numbers as possible the amount of sterility which exists and 

 also to see whether the technique or climatic conditions of one 

 state favor the fruiting of varieties normally incompatible to 

 their own pollen in other climates. For this purpose the results 

 on self sterility of the different varieties have been collected and 

 brought together in table 2. 



TABLE 2. 



Self Fertility and Self Sterility in the Varieties of the Apple. 



Variety 



Number selfed 



Number fruit 

 matured 



Number fruit not 

 matured 



Arkansas Black* 

 Autumn Sweet 4 

 Baldwins- 



100 



50 



169 



1 



100 

 50 

 168 



