HYBRIDIZATION METHODS IN CORN BREEDING. 



103 



which produced them, as may be shown by two series of facts. In the 

 first place, the hybrids between strains A and B which were reported 

 last year as producing from 74.4 to 78.6 bushels per acre have this 

 year yielded 79.8 bushels per acre. A slight increase in the other 

 cultures for 1909 as compared with those for 1908 makes this slight 

 increase in yield of the hybrid between strains A and B simply a 

 measure of the better climatic conditions of 1909 as compared with 



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v / \ \n \ x v % ^ f 



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CROSS-FERTILIZED, SELF-FERTILIZED, AND HYBRIDIZED CORN. 

 The lines between self-fertilized and hybridized series indicate the parentages of the latter. 



1908. The important feature of this result is that the F x hybrids 

 between strains A and B maintain essentially the same yielding capac- 

 ity in successive years, while other hybrid strains produce quite dif- 

 ferent yields, varying from 61.5 bushels per acre to 98.4 bushels per 

 acre. This fact, therefore, speaks for the view that the yield is a 

 result of the particular hybrid combination. The second fact which 



