100 BREEDING CROP PLANTS 



was thought possible that minor modifying factors were some- 

 times present which influenced the degree of fruitfulness of the 

 lateral florets. 



FIG. 23. Individual spikes of Fz generation of cross of Svanhals X Manchuria 

 representing phenotypic progeny classes in which the lemmas of the lateral 

 florets are rounded and awnless. From left to right: The two-rowed class which 

 will breed true in F 3 ; low fertility class which will give two-rowed, low fertility 

 and intermedium in F 3 ; intermedium which will breed true for intermedium 

 habit in /*V (After Harlan and Hayes, 1920.) 



Crosses between intermedium and six-rowed forms gave 

 intermediates of high fruitfulness in F\ and a ratio of six-rowed to 

 intermediates in FZ which indicated a single factor difference. 

 Intermedium forms crossed with two-rowed gave awnless forms 



