THE BREEDING OF CORN 193 



productive plants and to propagate them without the in- 

 termixture of blood from inferior sorts. 



234. Start with the best variety. — The initial step 

 in the improvement of corn is the selection of the best 

 variety for the existing conditions. It is a waste of time 

 and money to attempt the breeding or improvement of 

 varieties not well adapted to the soil or climate. The 

 value of any variety is conditioned on its yield, quality, 

 and adaptation. The adaptation of the variety is really 

 the deciding factor that determines whether it i may be 

 successfully grown in any locality. The work of the 

 agricultural experiment stations has demonstrated beyond 

 question that corn varieties differ as regards climatic 

 adaptation and therefore differ in point of yield. Some 

 tests reported by the Alabama Station at Auburn a few 

 years ago showed differences in the yield of corn varieties 

 as high as 160 per cent. The best variety can be selected 

 only as a result of a carefully conducted variety test. 



235. Mass selection. — The simplest method of im- 

 proving corn is by mass selection. In following this method 

 the grower selects from the field a large number of ears 

 from plants that conform nearest to the ideal type. The 

 next year all of this selected seed is mixed and planted. 

 From the crop thu^ produced the best individuals are 

 again selected, the seed mixed and planted the succeeding 

 year. This method of sfelection is followed year after 

 year, lyiass selection does not recognize a difference be- 

 tween the individuals selected as regards their ability to 

 produce, as by this method a performance record for 

 single plants, such as is kept in pedigree selection, is 

 impossible. 



236. Value of mass selection. — Rapid improvement 

 by mass selection is not possible. However, if the breeder 



