CORN CROPS 



SYSTEMS OF SELECTION 



63. Mass Selection in corn is the method of selecting 

 from a large field a number of individuals that conform 

 nearest to some ideal type. Seed of these plants is mixed 

 together and planted a second year and again a large 

 number of ears are selected and mixed for planting an- 

 other year, and so on for many years. 



It was discovered, however, that of two ears much alike 

 in appearance, perhaps one might yield 25 per cent to 50 

 per cent more than the other when used as seed corn. 

 The importance of testing each ear separately was at once 

 recognized. 



In pedigree selection after the first mother ears are 

 selected, a separate record is kept on the performance of 

 each ear or its progeny. For example, if it is desired to 

 select for a type bearing ears low on the stalk, a hundred 

 such ears might be selected from a large field. If mass 

 selection is practiced, they are mixed together and planted 

 the following year and the method continued for several 

 years. If pedigree selection is followed, each ear is planted 

 in a separate row and a record made of the percentage of 

 low ears produced by each mother ear. Seed ears are 

 only saved from those mother ears producing a large 

 percentage of low ears, the remainder being discarded. 

 Perhaps ten mother ears out of the first 100 will be found 

 to transmit the desired quality. From the progeny of 

 these ten ears, 100 ears may again be saved, each to be 

 planted in a separate row. This may be continued for 

 several years, the performance record being kept for every 

 year. By keeping a record on each family separate it 

 will be possible to gradually discard those families not 

 transmitting the desired quality and keep only those that 

 are most desirable. 



