228 ILLINOIS DAIRYMEN'S ASSOCIATION. , 



For a satisfactory breeding plot, about 20 to 40 selected seed ears are 

 required. If the breeder desires to make only physical improvement then 

 he should select, say, 40 of the most nearly perfect ears which it is possi- 

 ble to pick out by inspection or by exact physical measurements. If it is 

 desired to improve the composition or quality of the corn as well as the 

 physical properties, then at least 200 physically perfect ears should be 

 selected, and, from these 200 ears, the 40 ears which are most suitable as 

 seed for the particular kind of corn which it is desired to breed should be 

 selected, either by mechanical examination of sections of kernels, which 

 anybody can make, or by chemical analysis, or by a combination of these 

 two methods. In our own work we now commonly select by physical 

 inspection or measurement the 200 ears; then, from these 200 ears, we 

 select by mechanical examination of sections of kernels the best 50 or 100 

 ears, and from this lot we finally select by chemical analysis the best 20 

 to 40 seed ears for planting. This combination of methods effects a very 

 satisfactory seed selection and requires only one-half as much chemical 

 work as would be required if the method of chemical analysis alone were 

 employed. 



Table 2 shows very fairly the degree of seed improvement which may 

 be accomplished by these different methods of selection, when breeding 

 to change only the protein content of ocrn. 



It may be stated that equally satisfactory results may be obtained in 

 chemical' selection by mechanical examination for securing seed ears of 

 high or low oil content. For example, the writer has selected by mechan- 

 ical examination, from a lot of 272 ears of corn, 18 ears for high oil con- 

 tent which averaged 5.24 per cent of oil; and, from the same lot of corn, 

 30 ears were selected for low oil content which averaged 4.13 per cent 

 oil, making an average difference of 1.11 per cent of oil. 



