BULLETIN 287 



SELF STERILITY AND CROSS STERILITY IN THE 



APPLE. 1 



John W. Gowen. 



SUMMARY 



The results herein presented show that every apple grower 

 should provide suitable varieties for pollinators if large de- 

 pendable crops are to be secured. 



The results presented in Tables 1 and 2 show the apple 

 varieties which will self fertilize. No difference is noted in the 

 fruit set when a variety is self pollinated, when it is pollinated 

 with the pollen from different flowers on the same tree, or when 

 it is pollinated with pollen from different trees of the same 

 variety. 



A large amount of sterility is observed in the different 

 varieties. Out of 119 varieties only 42 set fruit, and of that 42 

 only 15 had a set of fruit which was even moderately commer- 

 cially profitable. 



Tables 3 and 4 show the results of cross pollinations with- 

 in the apple. Most varieties are capable of ready cross fertili- 

 zation with the pollen of other varieties. Over ^ °f those 

 varieties pollinated with pollen of other varieties set fruit sat- 

 isfactorily. 



Results are presented to show that it is necessary to test 

 a variety for cross compatibility before any conclusion can be 

 drawn for the variety. 



As pointed out the yield of orchards made up of one block 

 of self sterile trees may be materially increased by the intro- 

 duction of other varieties. 



The size, color, and quality of the fruit is shown to remain 

 practically the same as the standard for the mother parent. 



Papers from the Biological Laboratory, Maine Agricultural Experi- 

 ment Station, No. 133. 



